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J. Jason West, MD

• Cardiology Fellow, Department of Medicine, Division of Cardiovascular
• Medicine, University of Virginia, Charlottesville, VA, USA

Gene exchange between Neanderthals and the lineage of modern humans occurred several times in the Middle East and in Europe 30 pain tailbone treatment buy sulfasalazine online from canada,000­85 hip pain treatment relief sulfasalazine 500 mg buy cheap,000 years ago treatment for elbow pain from weightlifting purchase sulfasalazine 500 mg overnight delivery, starting soon after Homo sapiens emerged from Africa monterey pain treatment medical center discount sulfasalazine on line. Interbreeding also occurred during roughly the same timeframe in Asia between the ancestors of modern humans and the Denisovans already indigenous there pain management treatment for fibromyalgia buy 500 mg sulfasalazine free shipping. Mating within this population occurs at random, the three genotypes are selectively neutral, and mutations occur at a negligible rate. What is the frequency of the A allele in the second generation (that is, the generation subsequent to the founder generation) Answer this question requires calculation of allele and genotype frequencies and an understanding of the HardyWeinberg equilibrium principle. To calculate allele frequencies, count the total alleles represented in individuals with each genotype and divide by the total number of alleles. Given the conditions of random mating, selectively neutral alleles, and no new mutations, allele frequencies do not change from one generation to the next; f(A) = p = 0. The genotype frequencies for the second generation would be those calculated for part (b) because in one generation the population will go to equilibrium. Yes, in one generation a population not at equilibrium will go to equilibrium if mating is random and no selection or significant mutation exists. The genotype frequencies will be the same in the third generation as in the second generation. Two alleles have been found at the X-linked phosphoglucomutase gene (Pgm) in a Drosophila persimilis population in California. Assuming the population is at Hardy-Weinberg equilibrium, what are the expected genotype frequencies in males and females Answer this problem requires application of the concept of allele and genotype frequencies to X-linked genes. Three different genes (red, blue, and green) each have two alleles; one recessive allele for each gene has deleterious effects. The following graph depicts changes in the frequencies of these alleles in populations of infinite size over time; in each case, the frequency of the allele in question (q) is 0. If a population is at Hardy-Weinberg equilibrium, the genotype frequencies are p2, 2pq, and q2. Alleles do disappear from real populations, but not in the populations examined in the graph. For the green gene, the change in q is steeper than for the other genes, meaning that q must be the highest negative number in any given generation. The rate of change decreases for each gene in every successive generation because each generation has a successively smaller proportion of homozygotes for the recessive allele who would be subject to selection. The populations of infinite size would always have heterozygous individuals who would retain the deleterious allele but would not be selected against. Thus, genetic drift would eventually cause the deleterious allele to be lost from the population. For each gene (identified by the fitness of the recessive homozygotes), calculate q between the parental generation and the first generation of progeny (q = frequency of the recessive deleterious allele). Assume that the relative fitnesses of heterozygotes and of homozygotes for the dominant allele are 1. Then calculate q (the frequency of the recessive allele in the first generation of progeny). Which of the three genes (blue, red, or green) is the one for which the relative fitness of the recessive homozygote is 0. Briefly explain why q will become a smaller negative number in each successive generation for all of these three genes. Briefly explain why q would never go to 0 in any of these populations of infinite size. When an allele is dominant, why does it not always increase in frequency to produce the phenotype proportion of 3:1 (3/4 dominant: 1/4 recessive individuals) in a population In a certain population of frogs, 120 are green, 60 are brownish green, and 20 are brown. What are the expected frequencies of the genotypes if the population is at Hardy-Weinberg equilibrium A large, random mating population is started with the following proportion of individuals for the indicated blood types: 0. What will be the allele and genotype frequencies after one generation under the conditions assumed for Hardy-Weinberg equilibrium What will be the allele and genotype frequencies after two generations under the conditions assumed for Hardy-Weinberg equilibrium A dominant mutation in Drosophila called Delta causes changes in wing morphology in Delta / + heterozygotes. Homozygosity for this mutation (Delta / Delta) is lethal prior to the adult stage. In a population of 150 flies, it was determined that 60 had normal wings and 90 had abnormal wings. Using the allele frequencies calculated in part (a), how many total zygotes must be produced by this population in order for you to count 160 viable adults in the next generation Given that there is random mating, no migration, and no mutation, and ignoring the effects of genetic drift, what are the expected numbers of the different genotypes in the next generation if 160 viable offspring of the population in part (a) are counted Is the population at Hardy-Weinberg equilibrium with respect to either or both of the Q and R genes Alkaptonuria is a recessive autosomal genetic disorder associated with darkening of the urine. In the 740 Chapter 21 Variation and Selection in Populations United States, approximately 1 out of every 250,000 people has alkaptonuria. Assuming Hardy-Weinberg equilibrium, estimate the frequency of the allele responsible for this trait. In this population, what is the ratio of carriers to individuals affected by alkaptonuria If a woman without alkaptonuria had a child with this trait with one husband then remarried, what is the chance that a child produced by her second marriage would have alkaptonuria Alkaptonuria is a relatively benign condition, so there is little selective advantage to individuals with any genotype; as a result, your assumption of Hardy-Weinberg equilibrium in part (a) is reasonable. Could you also use the assumption of Hardy-Weinberg equilibrium to estimate the allele frequencies and carrier frequencies of more severe recessive autosomal conditions such as cystic fibrosis A huge flood opened a canyon in the mountain range separating populations 1 and 2. They were then able to migrate such that the two populations, which were of equal size, mixed completely and mated at random. It is the year 1998, and the men and women sailors (in equal numbers) on the American ship the Medischol Bounty have mutinied in the South Pacific and settled on the island of Bali Hai, where they have come into contact with the local Polynesian population. What is the allele frequency of the N allele in the sailor population that mutinied Alleles of genes on the X chromosome can also be at equilibrium, but the equilibrium frequencies under the Hardy-Weinberg assumptions must be calculated separately for the two sexes. For a gene with two alleles A and a at frequencies of p and q, respectively, write expressions that describe the equilibrium frequencies for all the genotypes in men and women. Approximately 1 in 10,000 males in the United States is afflicted with hemophilia, an X-linked recessive condition. If you assume that the population is at Hardy-Weinberg equilibrium, what proportion of American females would be hemophiliacs About how many female hemophiliacs would you expect to find among the 170 million women living in the United States In 1927, the ophthalmologist George Waaler tested 9049 schoolboys in Oslo, Norway, for red-green color blindness and found 8324 of them to be normal and 725 to be color blind. He also tested 9072 schoolgirls and found 9032 that had normal color vision while 40 were color blind. Assuming that the same sex-linked recessive allele c causes all forms of red-green color blindness, calculate the allele frequencies of c and C (the allele for normal vision) from the data for the schoolboys. Explain your answer by describing observations that are either consistent or inconsistent with this hypothesis. On closer analysis of these schoolchildren, Waaler found that there was actually more than one c allele causing color blindness in his sample: one kind for the prot type (cp) and one for the deuter type (cd). Through further analysis of the 40 color-blind females, he found that 3 were prot (cp/cp), and 37 were deuter (cd/cd). Based on this new information, what are the frequencies of the cp, cd, and C alleles in the population examined by Waaler Calculate the frequencies of all genotypes expected among men and women if the population is at equilibrium. Do these results make it more likely or less likely that the population in Oslo is indeed at equilibrium for red-green color blindness The equation p2 + 2pq + q2 = 1 representing the Hardy-Weinberg proportions examines genes with only two alleles in a population. Derive a similar equation describing the equilibrium proportions of genotypes for a gene with three alleles. Calculate the frequencies of individuals in this population with the four possible blood types, assuming Hardy-Weinberg equilibrium. In Problems 15­17, you will see that because mating between individuals within populations at Hardy-Weinberg equilibrium is random, it is possible to predict mating frequencies: that is, the proportion of all matings in the population between individuals of particular genotypes or phenotypes. If a population is at Hardy-Weinberg equilibrium, develop mathematical expressions in terms of p and q that predict the following mating frequencies: a. Between an aa homozygote and an Aa heterozygote Considering your answers to parts (a)­(f): g. Demonstrate this latter point by setting p equal to an arbitrary number between 0 and 1 such as 0. Can you develop a simple, general rule for calculating the mating frequencies between individuals of the same genotype versus the mating frequencies between individuals of different genotypes Some people can taste the bitter compound phenylthiocarbamide while others cannot. This trait is governed by a single autosomal gene; the allele for tasting is completely dominant with respect to the allele for nontasting. Assuming that the population is at Hardy-Weinberg equilibrium for this gene and that mating is purely random: a. What are the allele frequencies for the tasting allele T [= (p)] and for the nontasting allele t [= (q)] Of all the matings in the population, what proportion will be between two nontasters Of all the matings in the population, what proportion will be between a taster and a nontaster Of all the matings in the population, what proportion will be between a taster male and a nontaster female What proportion of all of the progeny produced by all matings between a taster male and a nontaster female will be nontasters Of all the matings in the population, what proportion will be between two tasters Androgenetic alopecia (pattern baldness) is a complex trait in humans governed by several genes, but suppose a human population exists in which a single autosomal allele determines pattern baldness. Assuming random mating, what proportion of all matings should be between a bald man and a nonbald woman If a nonbald couple produces a bald son, what is the probability that their next son will be bald A woman with androgenetic alopecia has a daughter, but nothing is known about the father. The figure has dots aligned on both sides to help you find the crucial bands; it will help to use a straight-edge as a guide. If so, identify this person and describe the degree of relationship to the criminal. What is the probability that any random male in the United States would share the same genotype as the murderer (the match probability) Explain why the assumption in part (f) that the sample is representative cannot be completely accurate. Why is the elimination of a fully recessive deleterious allele by natural selection difficult in a large population and less so in a small population In the late 1960s, four cases of retinitis pigmentosa, which progressively leads to blindness, were found among the 240 descendants of these settlers remaining on the island. Explain the high incidence of this disease on Tristan da Cunha relative to that seen in Britain. Small population size causes genetic drift because of chance sampling of different alleles from one generation to the next. We can predict how much genetic drift occurs for a given population size using binomial sampling statistics. With a population of size N, we can estimate that 95% of the time the allele frequency (p) in the next generation will be within p(1 - p) the confidence interval of p ± 1. How are the results in parts (a) and (b) related to the consequences of a population bottleneck Three basic predictions underlie genetic drift in populations: (1) As long as the population size is finite, some level of genetic drift will occur; thus, without new mutations, all variation will drift either to fixation or to loss. What is the allele frequency of a new autosomal mutation immediately after it occurs in a diploid population of size N = 100,000 What is the allele frequency of a new autosomal mutation immediately after it occurs in a diploid population of size N = 10

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Even though all of the nuclear chromosomes in all of the cells of the clone are derived only from the somatic nuclear donor marianjoy integrative pain treatment center buy discount sulfasalazine line, the cloned animal and this donor are not perfectly identical in all respects pain treatment with antidepressants sulfasalazine 500 mg purchase free shipping, for several reasons: (1) the mitochondrial genomes of the clone come from the oocyte donor davis pain treatment center cheapest generic sulfasalazine uk, not the nuclear donor pain treatment while on suboxone purchase sulfasalazine 500 mg mastercard. Few people could afford the high costs of the cloning procedure pain in thigh treatment buy cheapest sulfasalazine, and furthermore, some ill-informed clients were disappointed to find that the clone they received was not in fact exactly the pet they knew. Research on cloned animals enables scientists to better understand basic processes such as gene imprinting. Drug companies are investing in reproductive cloning technology with an eye toward being able to generate large numbers of high-producing transgenic animals. Dolly was cloned by scientists in Scotland, in part with funding from a pharmaceutical company. Cloned animal Before Dolly died in 2003, she gave birth to five progeny who live on. Finally, several endangered species have been cloned for the purpose of their preservation. Even if the scientific problems can be overcome, drug companies will encounter many regulatory hurdles before making these plant-produced vaccines available to humans. Because the regulations are less strict, considerable recent attention has been placed instead on feeding transgenic vaccine-making plants to domestic animals, so as to protect them from various diseases caused by pathogenic organisms. The improvements conferred by the transgenes include enhanced nutritional value; increased shelf life; increased yield or plant size; and resistance to stress, herbicides, or infestations by plant viruses or insects. We discuss here two of the most commercially important transgenic crops that are currently in wide use. More than 90% of the soybeans grown in the United States are transgenic plants resistant to glyphosate, the active ingredient in the herbicide called Roundup. Farmers spray fields of herbicide-resistant soybeans with Roundup to kill weeds with no harm to the soybeans, thus saving much labor and time. This protein is made naturally by the bacterium Bacillus thuringiensis to protect itself from being eaten by the caterpillars. Bt protein is lethal to insect larvae that ingest it, but not to other animals, including humans. Because the engineered corn manufactures its own natural insecticide, farmers can avoid using costly chemical pesticides that damage farmworkers and the environment. More than 10 billion acres of land around the world is used to grow Bt-expressing crops, not only corn but also canola, cotton, corn, papaya, potato, rice, soybean, squash, sugar beet, tomato, wheat, and eggplant. Atlantic salmon normally take three years to grow to their full size of about 9 pounds; their growth hormone gene is shut off during the coldest months when food is scarce, and so they grow only about eight months of the year. Transgenic Animals Model Human Gain-of-Function Genetic Diseases Animal models of human genetic diseases have for decades been an important tool for scientists trying to understand disease biochemistry so as to design and test new drugs and other treatments. The idea of an animal model for a monogenic human disease is simple-to generate an animal with a corresponding mutation and a similar disease phenotype. You should note that because transgenes are added to otherwise wild-type genomes, transgenic animals made by the techniques just described can serve as models only for dominant, gain-of-function mutations. Mice are mammals, and similar versions of most human genes are present in their genome. But for the study of human neurological disorders, unfortunately, mice cannot replicate the complex effects of some gene mutations on brain functions and behavior. Instead, scientists have recently begun to model human diseases in transgenic laboratory monkeys-rhesus macaques. The first transgenic primate model for a human neurological disorder was for Huntington disease. These monkeys show disease symptoms similar to those of people with Huntington disease, 18. Experiments with primates raise substantial ethical concerns for many people, so the future of primate models for human genetic diseases is unclear. As of this writing in 2016, the United States National Institutes of Health is in the process of phasing out most, though not all, invasive research on primate species. If the normal phenotype is restored, then the transgene identifies the gene that was mutated. Many crops, such as corn, soybean, canola, and cotton have been genetically modified to express Bt protein which discourages insect predation. We focus here mostly on methods to alter specific genes in mice, which are the animal of choice for many studies relevant to human biology. However, at the end of this section we describe an exciting new technique just coming into widespread use that is applicable to many different species. Homologous recombination then replaces the normal copy of the gene in the bacterial genome with the mutant copy. First, for a chromosome containing a targeted gene to be transmitted to progeny, gene targeting has to occur in germ-line cells. Second, given the low efficiency of homologous recombination, investigators need to screen through a large number of germ-line cells to obtain one with the desired mutation. Discuss how scientists employ a bacteriophage site-specific recombination system to generate knockin mice. In the previous section, you saw that genes can be transferred easily into random locations in the genomes of many animals and plants. Here we will explore more advanced technology that enables scientists to change specific genes in virtually any way desired-that is, targeted mutagenesis. Inject into blastocyst (d) Individual neomycin-resistant cell clones are tested to identify a clone where integration occurred by homologous recombination. This blastocyst is then placed in the uterus of another black female, where it can develop into a live-born mouse. If the germ line of the Chimera chimera contains agouti-derived cells, then some of the o spring of this mating will be agouti (which is dominant to black). Agouti brothers and sisters with the knockout allele can subsequently be mated with each other to produce mice homozygous for the knockout allele (not shown). Geneticists mate the chimeric mice to wildtype mice to generate nonmosaic heterozygous progeny. These progeny are called knockout mice because they contain a chromosome with an amorphic (knocked out) allele of the targeted gene. The geneticists then cross heterozygous knockout mice to each other to generate homozygous mutants. In a more general sense, knockout mice are invaluable for helping researchers understand the function of any gene in a mammalian organism. Conditional Knockout Mice Reveal Functions of Essential Genes For some genes, it is impossible to generate homozygous knockout mice. These so-called essential genes may be required for early stages of development of the animal, or for some process crucial to the viability of all cells. To investigate what the product of an essential gene does in the organism, researchers can use gene targeting to create mosaic individuals in which most cells are homozygous for wild-type alleles of the gene, and only certain cells are homozygous for mutant alleles. In an alternative application of the same kind of technology, the entire animal can remain homozygous for the wild-type allele until it reaches adulthood, after which the investigator can direct that some or even all of its cells become homozygous for the mutant allele. Mice with genes that can be inactivated specifically when investigators alter the environmental conditions are conditional knockout mice. Uses of mouse knockouts the first knockout mouse was created in 1989, and eight years later the three scientists who developed this technology were awarded a Nobel Prize. As nearly every human gene has a counterpart in the mouse that has the same or a similar function, knockout mice are useful for studies of a variety of human diseases caused by loss of gene function. One of the first monogenic diseases modeled in a knockout mouse was cystic fibrosis. Thus, the eye cells-and only the eye cells- are homozygous for a knockout of the gene. You can see why floxed alleles are called conditional knockouts: these alleles function normally in all tissues, except in those cells in which Cre is made and deletes sequences from the gene. Only in eye cells but not elsewhere in the body, Cremediated site-specific recombination at the loxP sites removes the exon from both copies of the floxed transgene. The construct contains two introns and an exon of the gene to be conditionally knocked out. One intron has a loxP site within it, while the other intron contains a drug resistance gene flanked by two loxP sites. Finally, geneticists perform a series of crosses to generate a mouse that is homozygous for the floxed gene and also carries a transgene that expresses Cre at a specific time or in a specific tissue. Generate mice containing both floxed gene and cre transgene Eye cells: exon removed m­ m­ Int IoxP ron Int IoxP ron Eye-specific regulatory region cre cre transcription only the eye Cells outside of eye: exon remains m+ m+ Int IoxP ron Int IoxP ron Exon Exon Int IoxP ron Int IoxP ron Eye-specific regulatory region cre No cre transcription 18. If this is the case, it is likely that after Cre expression the animal with the floxed allele will be eyeless. Alternatively, the targeted gene may be essential only in tissues outside of the eye, in which case the eyes (and indeed the whole animal) will be normal. Yet another possibility is that the gene is required in the eye for a specific function, such as forming the retina; in this case, Cre expression in homozygotes for the floxed gene would result in malformed retinas. Interestingly, the juxtaposition of knockout and wildtype cells in mosaic animals can allow scientists to determine whether a gene product expressed in one cell can affect the function of a neighboring cell. For example, an investigator may want to create a mouse that has a particular missense mutation that changes one amino acid in a protein to a different amino acid. After removal of the drug resistance gene by Cre expression, the loxP site that remains in the intron will not interfere with splicing. Knockin mice homozygous for the mutant gene will produce only the mutant form of the protein, although mice heterozygous for the knocked-in mutation may also be valuable if the mutation has dominant effects. This ability to replace a gene in the mouse genome with an allele engineered to have any change of interest is important for the creation of mouse models for certain genetic diseases in humans. Many inherited diseases are associated not with a completely amorphic allele of a gene, but rather with missense mutations in the codons for specific amino acids that might have hypomorphic, hypermorphic, or neomorphic effects. Until recently, only the mouse genome could be altered with this kind of precision. Of wider importance, researchers can apply the same tools in animals other than mice, or even in cultured cells, opening up many possibilities for the study of gene function and to establish new models for human diseases. Such a mutation can knockout the function of a gene, for example if it corresponds to a frameshift mutation in an open reading frame. These ideas were largely ignored for several more years until the mechanism of resistance became clarified. The spacer sequences are fragments of bacteriophage genomes captured by the host cell and integrated into the host genome by the action of two bacterially encoded Cas proteins (Cas1 and Cas2). These examples of the ways bacterial cells degrade viral chromosomes demonstrate the importance of basic science research: Topics that might have seemed obscure at the outset can have immense practical applications once they are understood. These technologies are remarkably efficient, such that researchers can mutate simultaneously both copies of a target gene in a diploid genome, immediately producing a mutant homozygote. Such efficiencies eliminate tedious and time-consuming steps of genetic crosses to create plants or animals whose genomes contain multiple modified genes. The key step of this technology is the introduction at that location of a double-strand break that can be repaired by nonhomologous end-joining or by homologous recombination. Describe problems associated with the use of viral vectors to introduce therapeutic genes into the cells of patients. In all of the examples discussed to this point in the chapter, the ultimate goal has been to change the genomes of germline cells so that stable lines of experimental organisms can be created. Although gene therapy in humans is still experimental, recently some promising successes have been achieved. For other diseases in which the affected cells can be removed from the body, more potent ex vivo gene therapy can be used. In the recombinant retroviral genome, the therapeutic gene replaces the gag, pol, and env genes. These cells produce virus-like particles containing the therapeutic gene, but no viruses that can replicate by themselves within cells. For a disease caused by a loss of gene function, such as cystic fibrosis, the therapeutic gene would simply be a wild-type copy of the gene whose function was lacking. A different strategy is required to combat gain-of-function conditions such as Huntington disease, in which expression of a mutant protein (or in other cases overexpression of the normal protein) causes the aberrant phenotype. In such cases, the therapeutic gene would need somehow to inactivate the disease gene or its protein product. Finally, for diseases with complex genetic origins such as cancer, the most generally useful strategy might be more indirect. The therapeutic gene could be injected into retinal cells, for example, or inhaled into the lungs. Patients administered the altered cells regained immune system function and were able to resist infection. Of nine children treated at that time, eight are still alive and have successfully resisted many infections. However, four of the patients eventually developed leukemia because the retroviral vector had inserted adjacent to a gene involved in cell proliferation; one of these children has succumbed to the cancer. At the beginning of the chapter, we discussed how a form of congenital blindness has been partially cured by gene therapy. In the majority of cases, the patients regained at least some sight and suffered no ill effects from the gene therapy. Gene therapy is still experimental; you can see that many technical problems need to be surmounted for gene therapy to become standard medical practice. Nonetheless, results to date are sufficiently encouraging so that researchers around the world are testing new ideas to treat more conditions with gene therapies. One problem associated with retroviral vectors is that their integration can result in genome mutation and in some cases can cause cancer in the patient. Although these embryos were never placed in a womb, this publication opened a firestorm of controversy because some descendants of embryonic cells eventually will become sperm or eggs that could be passed down to future generations. In other words, these studies demonstrated forcefully that gene editing technology is becoming powerful enough that humans will soon be able to change their own evolutionary destiny.

Hydatiform moles are growths of undifferentiated tissues that form within the uterus during an abnormal molar pregnancy pain treatment for liver cancer cheap 500 mg sulfasalazine with amex. Most hydatiform moles are benign sciatica pain treatment options buy 500 mg sulfasalazine otc, but because they sometimes can develop into cancers treatment pain post shingles order sulfasalazine 500 mg overnight delivery, these moles should be removed surgically when they are detected pain treatment center university of rochester cheap sulfasalazine 500 mg otc. Hydatiform moles are diploid cells with the normal numbers of genes and chromosomes advanced pain treatment center edgewood ky discount sulfasalazine 500 mg buy line. Why do you think they develop as undifferentiated tissues rather than as normal embryos Prader-Willi syndrome is caused by a mutation in an autosomal maternally imprinted gene. Label the following statements as true or false, assuming that the trait is 100% penetrant. Copies of the gene received from the mother are not expressed, but copies received from the father are expressed. One allele encodes a 60K (Kilodalton) blood protein; the other allele encodes a 50K blood protein. You then look at their children: Jill is producing only the 50K protein, while Bill Jr. With the accumulated data, what can you now say about the genotypes of Joan and Bill Sr. Indicate whether the copy of the gene from the male in generation I in the accompanying diagram is expressed in the germ cells and somatic cells of the individuals listed. In each of the two crosses, placental tissue was isolated whose origin was strictly from the fetus (this can be separated by dissection from placental tissue originating from the mother). Why was it important to perform reciprocal crosses to determine whether any of the genes were imprinted For example, a gene that is maternally imprinted in fetal placental tissue is not imprinted at all in the fetal heart. A method for detecting methylated CpGs involves the use of a chemical called bisulfite, which converts cytosine to uracil but leaves methylated cytosine untouched. You want to know whether a particular CpG dinucleotide at one location in the genome is methylated on one or both strands in a tissue sample. Using the bisulfite method, can you tell if this CpG dinucleotide in the tissue sample is hemimethylated (methylated on one strand) or methylated on both strands Honeybees (Apis mellifera) provide a striking example of environmental effects on eukaryotic gene expression and thus phenotype. Fertile queens and sterile workers are both female bees with the same diploid genomes. Queen Worker interference that is described in a later problem; the details are unimportant here. The hunchback gene, a gene necessary for proper patterning of the Drosophila embryo, is translationally regulated. It turns out that the diet of the larval (larvae are young developing insects) females controls their development as either workers or queens. When the hive needs new queens, a few female larvae are fed royal jelly, a substance secreted by worker bees, instead of the normal diet of nectar and pollen. Investigators determined that many genes are more highly CpG-methylated in the larval-stage workers than in the larval-stage queens. How can you test if gene X expression is obliterated in worms that have eaten the bacteria transformed with a plasmid containing your construct Male persimmon flowers have rudimentary, nonfunctional carpels (the female sex organ that includes the ovary), while female flowers have stamens and anthers (male sex organs), but no pollen is produced. Arabidiposis have so-called perfect flowers-individual flowers have both male and female structures. What do the results with transformed Arabidopsis suggest is one role of this protein in persimmon sex determination Speculate about possible mechanisms that could account for the rudimentary development of the nonfunctional carpels in male persimmon flowers. Drosophila females homozygous for loss-of-function mutations in the gene aubergine are sterile. Problem 29 in Chapter 13 described a phenomenon called hybrid dysgenesis that occurs when males from so-called P strains, whose genomes have P element transposons, mate with females from M strains, whose genomes lack P elements. In the germ lines of the hybrid progeny, frequencies of mutations and chromosomal rearrangements are elevated and can lead to sterility. What elements of gene expression do these techniques account for and what elements do they ignore Researchers know that Fru-M controls male sexual behavior in Drosophila because inappropriate Fru-M expression in females causes them to behave like males: Such females display male behaviors that are oriented toward other females. Describe a transgene construct that scientists could generate and insert into Drosophila females that would have the same effect as the mutant you described in (a). Would you expect a null mutation in Sxl to cause lethality in males or in females Which of these sex transformations would be caused by null alleles of tra and which would be caused by constitutively active alleles of tra As discussed in Problem 41, some Sxl alleles are lethal to females and others are lethal to males. Is the function of Sxl in regulating the synthesis of Msl-2 protein sufficient to explain the sex-specific lethality caused by both kinds of alleles Predict the effect of loss-of-function mutations in msl-2 on male and female fertility and viability. Now, for many of these children, the success of gene therapy trials provides hope not only for a halt A statue in front of the Institute of Cytology and Genetics in to the retinal degeneration characteristic of the disease, Novosibirsk, Russia pays homage to the laboratory mouse. In this article, you will learn about two general strategies for altering genomes: creation of transgenic organisms and targeted mutagenesis. Yellow and orange signals indicate the amplitude of cortical activation in response to a controlled amount of light shined on the eyes of these animals. Explain how researchers use the Ti plasmid from Agrobacterium to insert genes into plant genomes. In this section we will discuss some of the ways researchers can make transgenic organisms. Once introduced into a cell, the transgene has to be replicated and maintained as the cell divides. In most cases, these goals are accomplished by integrating the transgene into a random location in the genome of the host cell. However, in some species, the transgenes can be maintained outside of the host chromosomes, either as an extrachromosomal array (in C. Finally, in order for the transgene to be propagated between generations of a multicellular organism, it is crucial that cells containing the transgene have the ability to develop eventually into gametes. In animals, this requirement means that the transgene must be incorporated into a germ-line cell. In contrast, in plants, almost any cell can carry the transgene because entire plants can be regenerated from isolated cells. We describe here methods to create transgenic mice, flies, and plants that illustrate many of these points. These techniques are in large part based on our knowledge of natural gene transfer mechanisms. The pronuclei come close together, their nuclear membranes break down, and the maternal- and paternal-derived chromosomes intermingle so that their sister chromatids separate on the same spindle for the first mitotic division. At the conclusion of this mitosis, each cell of the two-cell embryo has a single diploid nucleus. The injected, fertilized egg is then implanted into the oviduct of a pseudo-pregnant female, where it can continue its development as an embryo. Integration can occur prior to the first mitosis, in which case the transgene will appear in every cell of the adult body. Alternatively, integration may occur somewhat later, after the embryo has completed one or two cell divisions; in such cases, the mouse will be a mosaic of cells, some with the transgene and some without it. As long as the transgene is present in germ-line cells, the transgene will be transmitted to the next generation. A mouse formed from a gamete containing a transgene can then be mated with other mice to establish stable lines of transgenic animals. Autonomous P elements contain a gene for transposase protein, and the transposon ends are inverted repeats. Transposase binds the inverted repeats, "cuts" the transposon out of the genome, and "pastes" it into a new location. Drosophila geneticists use P elements as vectors (vehicles) for transfer of genes into germ-line cells-a process called P element transformation. A widely used marker gene is the wild-type white gene (w+), which confers normal red eye color to flies with mutations in their endogenous white genes (w-). One plasmid was made by cloning the transgene into the vector; this plasmid now contains the transgene and the w+ marker gene, both located within the P element inverted repeats. After the injected embryos mature into adults, researchers cross each adult to w- flies. If a recombinant P element integrates into a chromosome of a germ-line precursor cell, some gametes produced by the injected animal will carry a chromosome with the recombinant P element. Investigators can recognize transgenic progeny (flies containing the recombinant P element) because they will have red (w+) eyes. These red-eyed flies can be used in cross schemes to establish stable lines of transgenic flies. A recombinant P element containing a transgene will not subsequently mobilize and move around the genome in flies of this stable line because laboratory strains of Drosophila do not contain P elements, so no transposase will be present. Researchers inject this plasmid, along with a helper plasmid containing the P element transposase gene, into w- host embryos where transposition occurs in some germ-line cells. When adults with these germ cells are mated with w- flies, some progeny will have red eyes and an integrated transgene. Researchers infect plants with Agrobacterium tumefaciens bacteria containing two plasmid constructs. Investigators select for single cells or seeds with a transgene insertion by growing cells or seeds in the presence of herbicide. Discuss examples of how transgenic organisms serve to produce proteins needed for human health. Explain the use of transgenic animals to model gain-of-function genetic diseases in humans. These examples of methods used for constructing transgenic organisms show how scientists can take advantage of natural processes to alter genomes. Studies with transgenic model organisms enable researchers to understand better the functions of particular genes and their regulation and to model certain human diseases in animals. Transgenes Assign Genes to Phenotypes In many genetic investigations, the available information may not allow scientists to pinpoint the gene responsible for a particular phenotype. The construction of transgenic organisms often allows investigators to resolve ambiguities. Therefore, the malformed eyes are due to the loss of gene B, not to the loss of gene A. For example, if homozygous m-/m- flies carrying a wild-type gene A transgene have malformed eyes, but m-/m- flies carrying a wild-type gene B transgene have normal eyes, you would conclude that the loss of gene B is the cause of the mutant phenotype; in other words, m = gene B. Here, we remind you that the function of these reporter constructs can be monitored only when they are introduced into eukaryotic organisms as transgenes. Bacteria are unable to perform many important posttranslational operations, including proper folding or cleavage of certain polypeptides, or modifications such as glycosylation and phosphorylation. To circumvent such problems, drug companies can sometimes use transgenic mammalian or plant cells that grow suspended in liquid culture. However, cell cultures produce only low yields of recombinant proteins, and growing the cells is expensive. The use of transgenic animals and plants to produce protein drugs is sometimes called pharming, a combination of the words farming and pharmaceutical. Pharming technology is still in its infancy; so far (in 2016), only one "pharmed" drug is available to patients, but many more are in development. The method used most commonly for the production of human protein drugs in transgenic animals is protein expression in the mammary glands, because proteins secreted into the milk can be purified at a high yield. Individual transgenic animals produced by pronuclear injection will have variable numbers of transgene copies, and the transgene array will be present at different random genomic locations. These variations result in large differences in the human protein yield among individual injected animals. One way to enhance the value of a rare, highproducing animal is by reproductive cloning: using somatic cell nuclei of transgenic adults to generate other animals with the identical genomes. Not surprisingly, the same pharmaceutical companies that are developing the technology to produce drugs in transgenic animals are funding the development of animal cloning technology. The Tools of Genetics Box entitled Cloning by Somatic Cell Nuclear Transfer describes the most commonly used reproductive cloning technology. Vaccine production in transgenic plants Like transgenic animals, plants carrying transgenes can be used for the production of human protein drugs. Transgenic plants have particular advantages for making vaccines, antigens of a disease-causing agent that stimulate an immune response to that particular foreign substance. Vaccine proteins produced by transgenic crop plants such as tobacco, sunflower, spinach, potatoes, rice, soybeans, corn, or tomatoes could be stored in the leaves or seeds. Edible vaccines could be especially advantageous for less-developed countries: No refrigeration is required for seed transport, plants could be grown on site, and no needles, syringes, or medical professionals would be necessary. Despite the theoretical promise of producing vaccines in transgenic plants, trials to date have had only partial success, and many problems need to be overcome before any of these vaccines can be marketed. One major difficulty is controlling the dose of the antigen: Individual plants can vary in the amount of antigen they produce, and too little antigen will result in an ineffective vaccine. Cloning in this sense refers to reproductive cloning, in which the genome of a single somatic cell from one individual now becomes the genome of every somatic cell in a different individual.

No single mitochondrial genetic code functions in all organisms pain treatment devices safe 500 mg sulfasalazine, and the mitochondria of higher plants use the universal code foot pain treatment home remedies cheap 500 mg sulfasalazine with mastercard. The genetic codes of some mitochondria therefore probably diverged from the universal code by a series of mutations occurring some time after the organelles became established components of eukaryotic cells pain treatment video purchase sulfasalazine 500 mg on-line. Contrast the variation in chloroplast genomes among species with that of mitochondrial genomes quadriceps pain treatment purchase 500 mg sulfasalazine fast delivery. Chloroplasts capture solar energy and store it in the chemical bonds of carbohydrates through the process of photosynthesis pain treatment after knee replacement order sulfasalazine 500 mg without a prescription. Embedded in the membranes of internal structures called thylakoids are the light-absorbing pigment chlorophyll and light-absorbing proteins, as well as proteins of the photosynthetic electron transport system. During the light-trapping phase of photosynthesis, the energy of photons of light from the sun boosts electrons in chlorophyll to higher energy levels. The energized electrons are then conveyed to an electron transport system that uses the energy to convert water to oxygen and protons. The energy stored in the bonds of these nutrient molecules fuels the activities of both the plants that make them and the animals that eat the plants. The genomes they carry are much more uniform in size than the genomes of mitochondria. Like mitochondria, chloroplasts contain more than one copy of their genome-usually 15­20 copies. Drugs that inhibit bacterial translation, such as chloramphenicol and streptomycin, inhibit translation in chloroplasts, as they do in mitochondria. This technique has been particularly important for investigations of chloroplast genomes, as we describe here. Scientists have also been successful in transforming the mitochondria of the yeast S. The gene for spectinomycin resistance is typically used in biolistic transformation. Plant cells with nontransformed chloroplasts that survive drug selection would be white and weak. Transformation of the chloroplast genome has considerable potential for altering the properties of commercially important crop plants. The risk that introduced genes will spread to neighboring plant populations is therefore low. Researchers have used this protocol to identify chloroplast genes encoding novel subunits of photosynthetic enzymes in several plant species. These high-energy molecules are used subsequently to convert carbon dioxide and water into carbohydrates. This cooperative arrangement did not happen overnight, but instead developed over evolutionary time. Evidence indicates that the ancient ancestors of these organelles and the cells that contain them were free-living organisms that entered into symbiotic relationships. Nuclear and Organellar Genomes Cooperate with One Another Several biochemical processes require components from both the organelles and the nucleus. As one example, cytochrome c oxidase, the terminal protein of the mitochondrial electron transport chain, in most organisms is composed of seven subunits. The remaining four are encoded by nuclear genes whose messages are translated on ribosomes in the cytoplasm; these proteins must then be imported into mitochondria. In all organisms, nuclear genes encode the majority of the proteins needed for gene expression in mitochondria and chloroplasts. Because mitochondria and chloroplasts do not carry genes for all the proteins they need to function and reproduce, these organelles must be provisioned constantly with molecules imported from other parts of the cell. Mitochondria and chloroplasts thus cannot exist independently of the cells in which they are found. Mitochondria and Chloroplasts Originated from Bacteria Chloroplasts are remarkably similar in size and shape to certain photosynthetic bacteria alive today. These likenesses suggest that mitochondria and chloroplasts started out as free-living bacteria that merged with the ancestors of modern eukaryotic cells to form a cellular community in which host and guest benefited from the group arrangement. The endosymbiont theory In the 1970s, Lynn Margulis was one of the first biologists to propose that mitochondria and chloroplasts originated when ancient precursors of eukaryotic cells established a symbiotic relationship with, and ultimately engulfed, certain bacteria. The primitive cells carrying a mitochondrionlike or chloroplast-like bacterial cell would have gained an edge in the fierce competition for energy production and eventually evolved into complex eukaryotes. So much evidence now supports this hypothesis that it is generally accepted as the endosymbiont theory. The molecular evidence for the endosymbiont theory includes the following facts: 1. Inhibitors of bacterial translation, such as chloramphenicol and erythromycin, block mitochondrial and chloroplast translation but have no effect on eukaryotic protein synthesis in the cytoplasm. Scientists estimate that the endosymbiotic event(s) giving rise to mitochondria occurred as long as 2 billion years ago, while the endosymbiosis resulting in chloroplasts happened perhaps 500 million years later. These events are so ancient that the exact processes that were involved are understood only dimly. Some scientists theorize that instead of an early primitive eukaryotic cell engulfing a bacterium, the first eukaryotic cell might have emerged from a symbiosis between archaea and bacteria. We have seen, for example, that some of the genes required for oxidative phosphorylation and photosynthesis reside in the nuclear genome; they may have been transferred there from the organellar genome. The idea that genes can move from the organelle to the nucleus has important implications. First, once copies of such genes are incorporated into nuclear chromosomes, the copy in the organelle would become redundant and then could be lost. If the gene was originally necessary for independent growth of the endosymbiotic bacterium, then the proto-organelle could no longer survive outside of the host cell. Second, different evolutionary lineages of eukaryotes could have moved different subsets of organellar genes to the nucleus, resulting in some of the enormous diversity of current-day organellar genomes. Researchers have some understanding of the mechanisms by which genes transfer between an organelle and the nucleus. Gene transfer between organelle and nucleus In the time since the original endosymbiotic events that gave rise to mitochondria and chloroplasts, some genes 530 Chapter 15 Organellar Inheritance Mitochondria and Chloroplasts learning objectives 1. Describe genetic studies which showed that yeast mitochondria are inherited biparentally. One of the questions that geneticists ask of any given species is whether the progeny of a cross obtain their organelles from both parents (biparental inheritance), or from just one parent (uniparental inheritance), which can be either maternal (if all the organelles come from the mother) or paternal. Each mating type can generate both male and female mating cells, where the male cells are considerably smaller than the female cells. If the original haploid cells had different alleles of a gene on a nuclear chromosome, Mendelian inheritance dictates that half the spores in the octad would contain one allele, and the other half the other allele (4:4 segregation). In 1952, Mary and Herschel Mitchell isolated a mutant Neurospora strain they called poky that exhibited a slow growth phenotype. They crossed the poky mutant strain of one mating type, which was also wild type for the gene ad+ (can synthesize adenine), to a strain of the other mating type with normal growth (poky+) that was also ad- (requires an adenine supplement). Surprisingly, however, all of the spores were either uniformly poky+ or poky-; the segregation of the slow growth phenotype was therefore 8:0. The poky trait thus exhibits nonMendelian inheritance because maternal and paternal gametes do not make equal contributions to the phenotypes of the progeny. The larger female mating cell provides all of the mitochondria to the cytoplasm of the transient diploid cell and to all eight spores. When uniparental inheritance occurs, progeny most often inherit their organelles from the maternal parent (maternal inheritance), but many exceptions exist. For example, in bananas inheritance of the chloroplast genome is maternal while that of mitochondrial genomes is paternal. Recall that Neurospora colonies are Mechanisms leading to maternal inheritance of organelles Differences in gamete size help explain maternal inheritance in species such as Neurospora crassa in which the male gamete is much smaller than the female gamete. As a result, the zygote receives a very large number of maternal organelles and at most a very small number of paternal organelles. However, zygote size is not the only mechanism leading to maternal inheritance of organelles. In some plants, the early divisions of the zygote distribute most or all of the paternal organellar genomes to cells that 15. All of the spores are Poky because this phenotype is controlled by a mitochondrial gene, and all the mitochondria are supplied by the larger female gamete. Variants of Organellar Genomes Segregate During Cell Division A single eukaryotic cell may harbor thousands of mitochondria, and a single plant cell may have dozens of chloroplasts. Moreover, each of these organelles may contain multiple copies of the organellar genome. These facts have important consequences for the inheritance of traits determined by genes on the organelle chromosomes. Variegated plants typically have variegated, solid green, and solid white branches (sectors). In certain animals, details of fertilization prevent a paternal cell from contributing its organelles to the zygote. For example, in the prevertebrate chordates called tunicates, fertilization allows only the sperm nucleus to enter the egg, while it physically excludes the paternal mitochondria. In yet another mechanism that occurs in many animals, the zygote destroys the paternal organelles after fertilization. Many very young children disappeared along with the young adults, and close to 120 babies that were born to women in detention centers. To this end, they gathered information from eyewitnesses, such as midwives and former jailers, and set up a network to monitor the papers of children entering kindergarten. By the time a democracy had replaced the military regime and the grandmothers could argue their legal cases before an impartial court, children abducted at age 2 or 3 or born in 1976 were 7­10 years old. Although the external features of the children had changed, their genes-relating them unequivocally to their biological families-had not. The grandmothers, who had educated themselves about the potential of genetic tests, sought help with the details of obtaining and analyzing such tests. Starting in 1983, the courts agreed to accept their test results as proof of kinship. Statistical analyses can establish the probability that a child shares genes with a set of grandparents. To validate their approach, King and colleagues amplified sequences from three children and their three maternal grandmothers without knowing who was related to whom. Today, the grandchildren-the children of Los Desaparecidos (the Disappeared)-have reached adulthood and attained legal independence. The progeny phenotypes always resembled those of the source of the female gamete (Table 15. But this distribution is not precise, so the two daughters of a heteroplasmic cell do not receive exactly the same proportions of wildtype and mutant chloroplasts. Once a cell becomes homoplasmic, it cannot become heteroplasmic again (except by new mutation), and so all of its descendants from that point on are homoplasmic. Chance cytoplasmic segregation of chloroplasts explains at least in part how a plant that is heteroplasmic for wild-type and mutant chloroplasts could have a mixture of heteroplasmic, homoplasmic wild-type, and homoplasmic mutant cells. During mitosis, cells homoplasmic for mutant chloroplasts can arise, and they establish the white patches and also white branches. Cells homoplasmic for wild-type chloroplasts also arise and establish the solid green branches. This phenomenon, where a particular fraction of wild-type organelles is sufficient for the normal phenotype, is called the threshold effect. The precise fraction of wild-type organelles needed to avoid a mutant phenotype will depend on the particular gene and mutation. Female gametes from flowers on white branches are homoplasmic for mutant chloroplasts; they always give rise to solid white plants (which ultimately die because they cannot photosynthesize). Flowers from green branches give rise to eggs homoplasmic for wild-type chloroplasts and therefore solid green (nonvariegating) progeny. The variegated plant considered as a whole is heteroplasmic because it came from a heteroplasmic egg-one that contained both wild-type and mutant chloroplasts. For example, the solid white areas of the plant are homoplasmic for mutant chloroplasts. In variegated branches, the green sectors are composed mainly of heteroplasmic cells. Cytoplasmic segregation gives rise to some homoplasmic mutant cells that form the white areas, and also some homoplasmic wild-type cells in the green areas. Like the somatic cells, eggs in variegated branches can be homoplasmic (for either wild-type or mutant chloroplasts) or heteroplasmic. All eggs and somatic cells in solid green or solid white branches are homoplasmic for wild-type or mutant chloroplasts, respectively. Two kinds of events can lead to cytoplasmic segregation of the genomes within an originally heteroplasmic organelle. As a result, some genomes replicate many times, while others do not replicate at all. Whether or not an individual organelle will function normally (wild type) or not (mutant) is potentially subject to threshold effects. Therefore, just like the cells they inhabit, the phenotype of an individual organelle- whether it is functionally wild-type or mutant-is affected by its relative fractions of wild-type and mutant genome copies. Some Organisms Exhibit Biparental Inheritance of Organellar Genomes Although uniparental inheritance of organelles is the norm among most metazoans and plants, certain single-celled yeasts and some plants inherit their organellar genomes from both parents-that is, in a biparental fashion. In this section, we look at the example of the budding yeast Saccharomyces cerevisiae. This fact was discovered in the early 1960s, when researchers found that chloramphenicol inhibits the growth of wild-type yeast on media containing a nonfermentable source of carbon (glycerol or ethanol); but the drug does not inhibit yeast growth on medium containing glucose, a fermentable carbon source. These investigators realized that growing yeast on glycerol or ethanol, which makes the cells depend on their mitochondria for growth, could allow the isolation of mutants in mitochondrial genes.

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References

• Frat JP, Thille AW, Mercat A, et al. High-flow oxygen through nasal cannula in acute hypoxemic respiratory failure. N Engl J Med. 2015;372(23):2185-2196.
• Tawil R, McDermott MP, Mendell JR, Kissel J, Griggs RC. Facioscapulohumeral muscular dystrophy (FSHD): Design of natural history study and results of baseline testing. FSH-DY Group. Neurology. 1994;44(3 Pt 1):442-446.
• Hintz SR, Kendrick DE, Stoll BJ, et al: Neurodevelopmental and growth outcomes of extremely low birth weight infants after necrotizing enterocolitis. Pediatrics 115:696, 2005.
• Soliman DE, Maslow AD, Bokesch PM, et al: Transoesophageal echocardiography during scoliosis repair: comparison with CVP monitoring. Can J Anaesth 45(10):925-932, 1998.
• Thoma A, Khadaroo R, Grigenas O, et al. Oromandibular reconstruction with the radial-forearm osteocutaneous flap: experience with 60 consecutive cases. Plast Reconstr Surg1999;104: 368-380.
• Chan YX, Alfonso H, Chubb SA, et al: Higher dihydrotestosterone is associated with the incidence of lung cancer in older men, Horm Cancer 8(2):119n126, 2017.