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  • Genetics  (597)
  • Wiley-Blackwell  (597)
  • Blackwell Publishing Ltd
  • 1985-1989  (462)
  • 1980-1984  (135)
  • 1925-1929
  • 1
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 532-541 
    ISSN: 0192-253X
    Keywords: Variegation ; Transposable elements ; Thylakoid membranes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Y18 is a nuclear gene of soybean (Glycine max) necessary for normal chloroplast development. An unstable allele (Y18-m) of the Y18 gene has been previously characterized genetically [Peterson and Weber: Theor Appl Genet 39:156-162, 1969.] Plants homozygous for the unstable allele produce leaves that exhibit a variegated pattern of green and yellow leaf sectors, indicating somatic mutability events. Germinal instability is detected by the recovery of either pure breeding dominant green (rare) or pure breeding recessive yellow (frequent) plants from the mutable stock. In contrast to most unstable genes identified in other plant systems, the Y18-m mutation is from the dominant green state to the recessive yellow state, producing a pattern of “reverse variegation.” Current work has focused on further characterization of this mutation at the whole plant level as well as at the biochemical level. These results include observations on the cell- and tissue-type specificity of the mutation, stability of the recessive yellow mutation, and a biochemical analysis of mutant and normal thylakoid membranes to identify the specific polypeptides affected by the y18 mutation. Several polypeptides of the thylakoid membranes are missing, and many, including the major light harvesting complex (LHCP) polypeptides, are reduced. Messenger RNAs for LHCPII were also reduced to a greater extent than other leaf transcripts in the yellow sectors of variegated plants. A comparison of Y18-m to other soybean mutable genes and transposable element insertions is made.
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 2 (1981), S. 319-336 
    ISSN: 0192-253X
    Keywords: maize ; mitochondrial DNA ; recombinant DNA ; cms-T ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Recombinant DNA and hybridization techniques have been used to compare the organization of mitochondrial DNA (mtDNA) from normal (N) and Texas male sterile (T) cytoplasms of maize. Bam H1 restriction fragments of normal mtDNA were cloned and used in molecular hybridizations against Southern blots of Bam H1 digested N and T mtDNA. Fifteen of the 35 fragments were conserved in both N and T as indicated by hybridization to comigrating bands in their restriction patterns. Only three fragments produced autoradiographs whose differences could reasonably be attributed to single changes in the cleavage site of the enzyme while approximately half (17/35) of the clones resulted in more complicated differences between N and T. The autoradiographs produced by these 17 clones indicated multiple cleavage site changes and/or sequence rearrangements of the mtDNA. Patterns of six of these 17 clones indicated partial duplication of the sequence and two showed variation in the intensity of hybridization between N and T, which may be related to the molecular heterogeneity phenomenon found in maize mitochondrial genomes. The large proportion of changes observed between N and T mtDNA indicates that rearrangements may have played an important role in the evolution of the maize mitochondrial genome.
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 2 (1981), S. 349-356 
    ISSN: 0192-253X
    Keywords: agouti locus ; lethal yellow gene ; MSH ; dibutyryl cyclic AMP ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Alleles at the agouti locus determines the type of pigment produced in hair-bulb melanocytes. In order to analyze the mechanism of agouti gene function, an attempt was made to induce the shift in melanin synthesis in vitro. Skin explants from newborn yellow mice with genotype Ay/a were cultured with the method using membrane-filter and roller tube. Production of black pigment in the hair bulbs was observed when the explants were cultured in the presence of α-melanocyte stimulating hormone (α-MSH). Electron-microscopic observation indicates that the induced black pigments are eumelanin that is normally found in hair-bulb melanocytes of genotypically black mice. The eumelanin synthesis was also induced by cAMP, DbcAMP, or theophylline. This α-MSH-induced eumelanin synthesis was suppressed by actinomycin D or cycloheximide, suggesting that the α-MSH-induced eumelanogenesis requires de novo transcription and/or translation.
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 3 (1982), S. 143-154 
    ISSN: 0192-253X
    Keywords: imaginal neurogenesis ; visual development ; genetic mosaics ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The neural phenotype of an imaginal disc degenerate mutant l(1)d deg-3 was studied in histological sections. The mutant larvae showed severe abnormalities in the imaginal neural development. Gynandromorphs, which are composed of genetically mutant and nonmutant cells, were generated and analyzed as late larvae. The results of mosaic analysis were consistent with l(1)d deg-3 gene acting autonomously in the imaginal disc and imaginal neural cells. The optic lobe development patterns observed in the larval mosaics provided evidence for an eye disc-optic lobe interaction during the late third instar larval stage.
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 31-48 
    ISSN: 0192-253X
    Keywords: B cell development ; IgM ; mouse ; tumor metastasis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The regulation of IgM expression was studied in clones derived from a murine B lymphocyte cell line, WEHI279.1. During normal B cell development IgM heavy chain synthesis increases concomitantly with heightened IgM secretion and reduced cell-surface IgM. However, in these subclones, the levels of membrane-bound and secreted IgM were regulated independently of one another. The amount of IgM secreted by the cells was tightly coupled to the amount of heavy chain synthesis, suggesting that the major control of secretion is pretranslational. Surface IgM exhibited a more complex regulation, with both pre- and posttranslational components. Variation in the expression of both forms of IgM occurred at high frequency. Although IgM expression follows a unidirectional pathway in nontransformed cells, the variability in these tumor cells was reversible and cellautonomous. High levels of phenotypic variability may be important in the ability of transformed cells to escape the immune response.
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  • 6
    ISSN: 0192-253X
    Keywords: catalase ; Drosophila ; development ; turnover ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The ontogenetic and tissue-specific expression of catalase (E.C. 1.11.1.6) has been determined in a wild type strain of Drosophila melanogaster derived from a natural population. Two distinct peaks of activity are observed during development with the first peak occurring in late third instar larvae just prior to puparium formation, and the second and larger of the two peaks occurring during metamorphosis. These peaks of catalase activity are coincident with the two major peaks of ecdysone titer. Of the tissues assayed, larval malpighian tubules, gut, and fat body demonstrated the highest specific activities. Adult abdomen exhibited a two- to three-fold higher specific activity than either head or thorax. Of the abdominal tissues assayed, malpighian tubules and abdominal wall had the highest specific activities. Malpighian tubules were the only sexually dimorphic tissue with respect to catalase activity and are apparently largely responsible for an overall increase observed in female abdominal activity. Catalase-specific CRM levels parallel the enzyme activity levels indicating that these tissue-specific activity differences reflect differences in the rate of accumulation of catalase molecules.Turnover studies employing the catalase inhibitor 3-amino-1,2,4-triazole were conducted on head, thorax, and abdomen of male adult flies. Rates of catalase degradation were similar in the three body segments with a slightly higher rate in abdominal tissue. Therefore the different steady state levels observed largely reflect different rates of catalase synthesis.
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  • 7
    Electronic Resource
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 99-115 
    ISSN: 0192-253X
    Keywords: differential allelic expression ; Zea mays ; isozyme ; endosperm ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The timing of gene expression in the endosperm of developing F1 maize kernels was investigated. Zymogram analysis revealed the presence of maternally derived allelic gene products on all days investigated, but activity of paternally derived allelic gene products is not detectable until days 6-8 postpollination, depending on the particular cross used and the enzyme investigated. This pattern holds true for eight different isozymes of five different enzyme systems, including catalase, alcohol dehydrogenase, glutamate-oxaloacetate transaminase, endopeptid́ase, and aminopeptidase. An increase in specific activity for catalase, alcohol dehydrogenase, and endopeptidase correlates precisely with the day of visualization of the paternally derived allelic gene product on the zymograms. Rocket immunoelectrophoresis confirms a dramatic increase in catalase and alcohol dehydrogenase protein levels on the day the paternally derived allelic gene product is first detected on zymograms. Appropriate crosses utilizing three different allelic variants revealed the presence of enzyme of maternal plant origin within the endosperm prior to day 6 postpollination.Maize kernels were cultured in vitro on an agar-based medium as early as 3 days postpollination. Using medium supplemented with actinomycin D or cycloheximide, it was possible to localize the critical time periods for transcription and translation of the paternally derived allele in the F1 hybrids. For aminopeptidase (AMP-1, AMP-3) and endopeptidase (ENP-1), transcription occurs as early as 3-4 days postpollination, and translation of the transcripts starts at about 4-5 days postpollination. Although the evidence is indirect, it is likely that the maternally derived allele of the F1 kernels is activated (ie, begins transcribing) synchronously with the paternally derived allele during this early developmental time period.
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  • 8
    Electronic Resource
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 129-141 
    ISSN: 0192-253X
    Keywords: cytokin mutant ; habituation ; Nicotiana ; tissue culture ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cultured leaf tissues of Nicotiana tabacum L. cv. “Havana 425” normally require an exogenous source of cytokinin for rapid growth; stem-cortex tissues do not - ie, they exhibit the cytokinin-habituated phenotype. We found that plants regenerated from cloned cortex and leaf tissues from one particular plant differed in leaf-tissue phenotype: Leaf tissues derived from leaf cells exhibited the normal, nonhabituated phenotype, whereas leaf tissues derived from cortex cells were cytokinin-habituated. This difference in leaf phenotype was not found using leaf and cortex cells from six other donor plants. The inheritance of the habituated leaf trait was studied in tissues from cortex-derived plants and hybrids between these plants and normal plants. F1 hybrids were intermediate between the parental types in degree of habituation. No differences were found between reciprocal hybrids. These results suggest that the habituated leaf trait is an incompletely dominant, nuclear trait. Both parental and intermediate phenotypes were recovered in the F2 progeny. The frequency of habituated leaf progeny in the F2 and backcross populations provide evidence that the trait is regulated at a single genetic locus.
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  • 9
    Electronic Resource
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 159-165 
    ISSN: 0192-253X
    Keywords: trisomy ; monosomy ; aneuploidy ; chimeras ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mouse trisomy 15 ↔ 2n aggregation chimeras have been produced and analyzed at 19 days of gestation. We have found that these chimeras are viable and in most instances normal in external appearance, unlike trisomy (Ts)-15 embryos which are severely growthretarded and die midway through gestation. Trisomic cells were found in all tissues of fetal chimeras, with proportions not significantly different from those of the controls in kidney, heart, liver, and brain, but significantly reduced in thymus and spleen. Ts-15 cells do not, therefore, exhibit a proliferative advantage during fetal development of tissues susceptible to Ts-15-related lymphoid malignancies. However, the presence of Ts-15 cells in the placenta may be associated with placental overgrowth. One fetus containing a monosomy 3 cell population was also observed, the first term fetal chimera with monosomic cells that has been detected.
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  • 10
    Electronic Resource
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 145-158 
    ISSN: 0192-253X
    Keywords: tetrahymena ; mating type ; differentiation ; macronucleus ; starvation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mating type differentiation in Tetrahymena thermophila is known to regularly involve stable hereditary alterations at a single chromosomal locus in the somatic (macro)nucleus. This differentiation is directionally affected by the temperature at which new macronuclei develop after fertilization. We now report large and predictable effects of delayed refeeding of conjugating pairs upon mating type differentiation, particularly among mat-2 homozygotes. The mating types whose frequency is affected the most are IV, VI, and VII, a set different from that most affected by temperature. We interpret our observations to reveal the existence of a second system which can participate in mating type differentiation, with different specificity from the system influenced by temperature under conditions of early refeeding of conjugating pairs. These observations enrich the phenomenology surrounding mating type differentiation in T thermophila and provide additional, easily controllable experimental conditions for the manipulation of mating type frequencies.
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  • 11
    ISSN: 0192-253X
    Keywords: dedifferentiation ; Dictyostelium ; aggregation ; mutant ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: During slime mold development, cells acquire the capacity to rapidly recapitulate morphogenesis in roughly a tenth the original time. When developing cells are disaggregated and refed, they completely loss this capacity in a rapid and synchronous step referred to as the “erasure event.” The erasure event sets in motion a program of dedifferentiation during which developmentally acquired functions are lost at different times. In this report, we describe the phenotype of HI4, which is a mutant partially defective in the dedifferentiation program but normal in all aspects of growth, morphogenesis, and rapid recapitulation. HI4 cells progress through the erasure event, losing in a relatively normal fashion (I) the capacity to rapidly recapitulate later stages of morphogenesis, (2) the capacity to release a cAMP signal, and (3) the capacity to respond chemotactically to a cAMP signal. However, erased HI4 cells abnormally retain the capacity to rapidly reaggregate, even though they have lost chemotactic functions. Erased HI4 cells also abnormally retain EDTA-resistant cohesion (contact sites A) and the surface glycoprotein gp80. It appears that erased HI4 cells rapidly reaggregate owing to random collisions followed by tight cell cohesion.
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  • 12
    Electronic Resource
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 185-198 
    ISSN: 0192-253X
    Keywords: maternal effects ; Polycomb locus ; Drosophila ; homoeosis ; Enhancer of Polycomb ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A mutation or deficiency of the Enhancer of Polycomb (E(Pc)) locus acts as a dominant enhancer of the adult mutant phenotypes of a group of similar homoeotic loci (Polycomb, Polycomblike, extra sex comb, and lethal(4)29). The E(Pc) mutation has a recessive lethal effect, and homo- and hemizygotes die as late embryos or larvae which appear cuticularly normal. E(Pc) also acts as a dominant enhancer of the embryonic homoeotic syndromes associated with Polycomb. Polycomblike, and lethal(4)29 mutations: its effect on the extra sex comb syndrome has not been effectively evaluated. At least for the interaction with Polycomb mutations, evidence is presented that the Enhancer of Polycomb locus has a maternal as well as a zygotic effect, and that its effect on Polycomb expression is not at the level of transcription. We suggest that the Enhancer of Polycomb locus acts specifically to regulate the activities of this set of homoeotic loci, and that E(Pc) recessive lethality results from noncuticular homoeotic defects which arise as a consequence of their reduced activity. In the context of this hypothesis, no present data allow us to distinguish whether Enhancer of Polycomb is a nonhomoeotic locus regulating the function(s) of Polycomb and related genes or is itself a homoeotic locus.
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  • 13
    ISSN: 0192-253X
    Keywords: marine molluscs ; heterozygosity ; growth ; selection models ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We examine several models that may account for the observation that in populations of marine molluscs in general, and of the American oyster (Crassostrea virginica) in particular, the growth of an individual is related to its degree of heterozygosity and, also, that the number of heterozygous individuals in the population is less than expected on the assumption of random mating and no selection. We classify these models into nonselective, selective, and mixed models. We conclude that mixed models are the most likely to apply to real populations, but cannot exclude selective models. Nonselective models appear least likely. Current evidence favors a model that assumes that heterozygotes enjoy a fitness advantage as adults, primarily because of their faster growth, and that the lower numbers of heterozygotes in the population result from some form of nonrandom fertilization. One possible source of nonrandom fertilization is variation in the time of spawning of individuals due to differences in body size.
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  • 14
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 6 (1985), S. 39-58 
    ISSN: 0192-253X
    Keywords: Drosophila melanogaster ; trisomy 3L ; dosage compensation ; heat shock ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Production of trisomic-3L Drosophila melanogaster has allowed further investigation of compensated levels of gene expression in autosomal trisomies. We find that four enzyme loci on this arm produce diploid levels of gene product in trisomic-3L larvae. For one of these genes, we show that all three alleles are expressed at similar levels. Two genes on 3L display dose-dependent levels of gene product, and their location, relative to the four compensating loci, indicates that these two classes of genes are not regionally separated. In trisomic-2R larvae, the level of enzyme produced from on 2R-linked gene was dose dependent. In contrast, measurements of five loci on the X chromosome in metafemales (X trisomies) suggest that most genes are compensated in these individuals. Heat-shock gene expression in trisomic-3L salivary glands was qualitatively similar to diploids. The quantities of the small hsps (from the 67B cluster on 3L) suggest that these four genes respond independently to the trisomic condition; two produce compensated levels of protein, whereas the other two produce dose-dependent levels of protein. The amount of hsp 83 produced in trisomies was similar to diploids (compensated). However, quantification of hsp 83 RNA showed that a dose-dependent level of transcript was produced. This implies that hsp 83 compensation is controlled post-transcriptionally.
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  • 15
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 6 (1985), S. 75-75 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 16
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 6 (1985), S. 59-74 
    ISSN: 0192-253X
    Keywords: Dictyostelium discoideum ; cell cohesion ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Three stage-specific cohesive systems operate in D. discoideum: VEG, elaborated by vegetative cells: AR, by aggregation competent cells; and PAR, by post aggregation stage cells. Previous study of a mutant strain JC-5 had shown the stability of its PAR system (but not the AR) to be temperature sensitive. However, the phenotypic expression of this mutation termed Coh A is complicated by the presence in that strain of a preexisting mutant gene Rde A, which accelerates developmental events generally and alters the pattern of morphogenesis. Genetic evidence presented here indicates that the two mutations have been separated by parasexual recombination yielding a Coh A, Rde A+ segregant class of which strain JC-36 is a prototype.At the permissive temperature, JC-36 follows a morphogenetic sequence like that of the wild type in respect to timing, morphogenetic pattern, and spore appearance. At the restrictive temperature, it forms normal aggregates at the usual time but exhibits two morphogenetic aberrancies during post aggregative development. First, fruit construction is arrested at a stage approximating the 16 hr “Bottle” stage of the wild type, though more squat and blunt tipped, and then the aggregate regresses. Cytodifferentiation into spores and stalk cells is also blocked. Second, a shift of slugs migrating normally at the permissive temperature to the restrictive causes the latter to disintegrate progressively as they leave clumps of cells behind them within the flattened sheath.JC-36 cells developing at the restrictive temperature also exhibited a decrease in EDTA resistant cohesivity attributable on two grounds to the sensitivity of the PAR system. In addition, the disappearance of the AR system completed in the wild type by the Mexicanhat (18-19 hr) stage is indefinitely arrested at an intermediate level in JC-36.
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  • 17
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 6 (1985) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 18
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 6 (1985), S. 93-100 
    ISSN: 0192-253X
    Keywords: heat shock ; phenocopy ; forked ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Heat shock uncovers the recessive forked phenotype when heterozygotes between f36a and wild-type are heated during sensitive periods in pupal development. We call the phenocopy of a mutant in such a heterozygote a heterocopy. The heterocopy in f36a/+ is virtually identical to the mutant phenotype; however, bristles on different parts of the body are affected during different sensitive periods. We discuss the hypothesis that the heat shock acts by affecting expression of the wild-type gene product corresponding to the mutant gene. The sensitive period for heterocopy induction in a specific tissue is proposed to correspond to the normal time of gene expression for the forked gene product in a particular tissue.
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  • 19
    ISSN: 0192-253X
    Keywords: Tripsacum dactyloides ; Zea mays ; tripsacoid maize ; abnormal development ; ribosomal DNA ; restriction site change ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Some of the derivatives of a cross of maize (Zea mays L.) × Tripsacum dactyloides (L) L (2n = 72) have abnormal development leading to strange and striking morphologies. The Tripsacum chromosomes in these “tripsacoid” maize plants (with Tripsacum-like characteristics) were eliminated and the maize chromosomes were recovered through repeated backcrossing to maize. As an initial attempt to analyze the DNA alterations in tripsacoid maize, we have detected a few restriction site changes in the ribosomal DNA repeat of these plants (Hpa II, Bal I, Sst I, Mbo II, and Sph I) and a new Sph I site was mapped to the spacer region between the 26S and 17S genes. Several possible mechanisms for the generation of a new restriction site are discussed, and we propose that the transient presence of Tripsacum genome during the backcrossing in some way induced a rapid amplification and fixation of new restriction sites in a relatively short period of time.
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  • 20
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 6 (1985), S. 151-151 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 21
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 6 (1985), S. 113-132 
    ISSN: 0192-253X
    Keywords: eliminated DNA ; facultatively persistent sequences ; macronuclear development ; Tetrahymena thermophila ; phenotypic assortment ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: During conjugation in the ciliated protozoan, Tetrahymena thermophila, a somatic MAC-ronucleus develops from the germinal MICronucleus. Ten to 20 percent of the MIC genome is eliminated during this process. Three repetitive families have been identified which have different levels of repetition in the MIC and are eliminated to different degrees in the MAC. Some members of two of these families persist in the MAC. In this study, we have looked at these persistent sequences in the MAC of cell lines from a variety of sources including several inbed strains, two sets of caryonides, caryonidal subclones, and vegetatively aged cell clones. The results suggest that the sequences that remain in the MAC have a genetic predisposition to persist. However, epigenetic variations occur as the MAC develops so that only some of the persistent sequences are actually observed in a particular MAC. Polymorphisms may be generated if alternative processing of a single MIC segment occurs. These polymorphisms can later be resolved by phenotypic assortment during vegetative growth. These facultatively persistent sequences appear to differ from sequences previously described in this organism.
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  • 22
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 6 (1985) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 23
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 6 (1985), S. 133-150 
    ISSN: 0192-253X
    Keywords: vitellogenesis ; Drosophila melanogaster ; egg shell ; oogenesis ; vitellogenin ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Ovarian follicle cells of wild type Drosophila melanogaster simultaneously secrete yolk polypeptides (YP1, YP2 and YP3) and vitelline membrane proteins. In order to understand the relationship between these two secretory activities, we have investigated the ultrastructure of a female sterile mutation that alters YP1 secretion and vitelline membrane deposition. Homozygous fs(1)1163 females lay eggs that collapse and contain reduced quantities of YP1. Secretory granules in follicle cells contain an electron-translucent component that is assembled into the developing vitelline membrane in both mutant and wild-type ovaries, and an electron-dense component that disperses after secretion in wild-type ovaries. Mutant ovaries differ from wild-type by (1) having larger secretory granules (2) forming clumps of the dense secretory component within the developing vitelline membrane (3) accumulating more tubules in the cortical ooplasm of vitellogenic oocytes, and (4) possessing altered yolk spheres. Mutant ovaries implanted into wild-type hosts showed no improvement in the secretory granules and slight improvement in the vitelline membrane clumps but amelioration of the oocyte phenotypes. Since genetic evidence suggests that the fs(1)1163 mutation resides in or near the Yp1 gene and biochemical data show that the mutation alters YP1 structure, we conclude that the ultrastructural phenotypes are due to a structurally abnormal YP1 in the mutant. The alteration in vitelline membrane structure caused by the dense clumps could account for collapsed eggs and, hence, the female sterility of the mutant.
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  • 24
    ISSN: 0192-253X
    Keywords: ecdysteroid ; prothoracic gland ; temperature sensitive ; Drosophila ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The dominant temperature-sensitive mutation L(3)3DTS (DTS-3) in Drosophila melanogaster causes lethality of heterozygotes during the third larval instar at the restrictive temperature (29°C). Temperature-shift experiments revealed two distinct temperature-sensitive periods, with lethal phases during the third larval instar (which may persist for 4 weeks) and during the late pupal stage. At 29°C mutant imaginal discs are unable to evert in situ, but did evert normally if cultured in the presence of exogenous ecdysterone or when implanted into wild-type larval hosts. The only morphologically abnormal tissue present in the lethal larvae is the ring gland, the prothoracic gland being greatly hypertrophied in third instar DTS-3 larvae. Injection of a single wild-type ring gland rescued these mutant larvae, indicating that the mutant gland is functionally, as well as morphologically, abnormal. Finally, the mutant larvae were shown to have less than 10% of the wild-type ecdysteroid levels. These results are all consistent with a proposed lesion in ecdysteroid hormone production in DTS-3 larvae. A comparison with the phenotypes of other “ecdysone-less” mutants is presented.
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    ISSN: 0192-253X
    Keywords: Dictyostelium discoideum ; revertants of stmF mutants ; cGMP metabolism ; cGMP-specific phosphodiesterase ; suppressor mutations ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: stmF mutants of Dictyostelium discoideum produce long, banded aggregation streams on growth plates and exhibit altered cGMP metabolism. To learn more about the role of cGMP in chemotaxis and the nature of the defect in these mutants, 15 nonstreaming (Stm+) revertants of two stmF mutants were isolated and characterized. Fourteen of the revertants continued to show the elevated cAMP-induced cGMP response and very low cGMP-specific phosphodiesterase (cGPD) activity characteristic of their stmF parents. Parasexual genetic analysis revealed that many of these Stm+ revertants carried phenotypic suppressors unlinked to stmF. One Stm+ revertant, strain HC344, exhibited a low, prolonged cGMP response and relatively high cGPD activity throughout development. To determine whether the elevated cGPD activity in this revertant resulted from increased enzyme production or enhanced enzyme activity, cGPDs were partially purified from the wild-type strain, the stmF parent and revertant HC344, and properties of the enzymes were compared. cGPDs from the stmF mutant and the revertant showed similar differences from the wild-type enzyme in kinetic properties, thermal stability, and sensitivity to certain inhibitors. These results suggest that stmF is the structural gene of the cGPD. In addition, the unusual cGMP response in revertant HC344 appeared to be due to increased production of an altered cGPD.
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    Developmental Genetics 6 (1985), S. 199-212 
    ISSN: 0192-253X
    Keywords: ultrastructure ; cell death ; Drosophila melanogaster ; imaginal disk ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The temperature-sensitive mutant l(3)c43hs1 is lethal at the restrictive temperature late in the last larval instar and has wing disks that show excessive growth when larvae are reared at 25°C. Such mutant disks give rise to defective wings showing duplications and deficiencies. Abnormal folding patterns are localized to the region between the wing pouch and the area where adepithelial cells are found; the disks retain an epithelial morphology. Apoptotic cell death is distributed throughout the wing disks without any obvious concentration of dead cells in a specific area. Cell death is seen as early as 12 hr after a shift to the restrictive temperature. Temperature shift experiments also show that cell death precedes the onset of overgrowth, but since the spatial distribution of death is not localized to the regions of abnormal folds, it is unlikely that cell death and overgrowth are causally related.
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    Developmental Genetics 6 (1985), S. 179-197 
    ISSN: 0192-253X
    Keywords: embryonic development ; phenocopies ; heat shock ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Heat shock of pre-adult Drosophila disrupts development and causes phenotypic abnormalities. Type of abnormality depends on developmental stage at time of shock. Defects probably result from disruption of stage specific processes by the heat shock response (which includes reduction of normal mRNA and protein production). This study uses heat shock to study stage specific processes in early development. Short, intense shocks (2-3 min, 42-43°C) are administered to carefully staged embryos within the first 5 h of development. Stage specific defects occur following shock at syncitial blastoderm or later. Abnormal segmentation follows shock at syncitial or cellular blastoderm. Segmentation is also disrupted by shocks 1 h after the onset of gastrulation, but not by shocks at the onset of gastrulation. Segmentation defects include phenocopies of pair rule mutants, which lack parts of alternate segments. Defective shortening of the germ band is common following shock at the onset of gastrulation. Germ band shortening normally occurs several hours after the time of shock; thus heat shock specifically affects control of a later developmental process. Development does not simply cease at the time of the distrupted process; rather a specific step in the developmental sequence is omitted or altered. Stage specific defects do not occur following pre-blastoderm shock. Pre-blastoderm eggs have few or no normal processes controlled by transcription, and poor ability to induce the heat shock response. This suggests that stage specific defects require disruption of transcription controlled processes. Pre-blastoderm eggs survive a 3-min shock less well than older eggs. The ability of older eggs to induce the heat shock response probably enhances survival. The mutant hairy was also investigated. Extreme alleles show a striking pair rule phenotype, while a weak allele does not. Heat shock of animals heterozygous or homozygous for the weak allele at blastoderm specifically increases the frequency of the extreme hairy phenotype. Thus heat shock may disrupt the same developmental process as is altered by the mutation.
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    Developmental Genetics 6 (1985) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
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  • 29
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    Developmental Genetics 6 (1985), S. 247-255 
    ISSN: 0192-253X
    Keywords: Drosophila ; triploid intersexes ; sex differentiation ; dosage compensation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Triploid intersexes homozygous for a mutant (msl-2) known to impede the hyperactivation of the X chromosome in diploid males differentiate into adults, sexually indistinguishable from their heterozygous sibs. A shift toward female sexual differentiation mediated by manipulating the rearing temperature is accompanied by an apparent increase in the level of an X-linked gene product. This unexpected result is rationalized in terms of differential lethality of individuals at the two extremities of the distribution of X-activity levels in intersexes raised at a particular temperature. No evidence of a mosaicism comparable to the sexual mosaicism exhibited could be found with respect to an X-linked gene product in triploid intersexes.
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    Developmental Genetics 6 (1985), S. 239-246 
    ISSN: 0192-253X
    Keywords: Drosophila melanogaster ; germ line ; somatic line ; pole cell transplantation ; mosaics ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The Drosophila melanogaster mutant fs(1)1304 is an ovary autonomous female sterile mutant that causes abnormal morphology of the egg. Vitellogenesis proceeds at an abnormally slow rate in homozygous females. We have used pole cell transplantation to construct germ line mosaics in order to determine whether the 1304 defect depends upon the genotype of the germ line cells (oocyte or nurse cells) or the somatic line (follicle cells). We have found that the germ line is the primary target tissue where the mutant gene is expressed.
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    Developmental Genetics 6 (1985), S. 295-296 
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    Keywords: Life and Medical Sciences ; Genetics
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  • 32
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    Developmental Genetics 6 (1985), S. 269-280 
    ISSN: 0192-253X
    Keywords: UV ; DNA repair ; photoreactivation ; algae ; dark repair ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The response of Volvox to ultraviolet irradiation was analyzed. Young individuals isolated from a synchronous culture were exposed to UV light (120 J/m2) and subjected to variable lenght periods of dark following irradiation. The major effect of the UV treatment was the inability of the gonidia present in the colonies at the time of irradiation to continue and complete the developmental program. Individuals show a heightened sensitivity to UV for a limited period immediately following inversion and are insensitive at other stages of development. The cytotoxic effect of UV during this interval is completely reversed by the immediate exposure to white light and is increased with longer periods of dark treatment prior to exposure to white light. The temporal profile of the sensitivity defines a smooth curve in which the maximal sensitivity occurs three hours after inversion. The response to higher doses of UV (up to 500 J/m2) is a nonlinear increase in cytotoxicity and is disproportionanately greater in those individuals just prior to the period of maximal sensitivity than those later in development. The results suggest that Volvox has at least two pathways for the repair of UV damage and that one of these, the principal dark repair pathway, is temporarily deficient in the gonidia of young individuals.
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    Developmental Genetics 6 (1985), S. 281-291 
    ISSN: 0192-253X
    Keywords: DNA insertion ; reversion ; variegation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A spontaneous white mutation recovered in Drosophila mauritiana is unstable and reverts to normal eye color at a frequency greater than 4 per 1,000 ×-chromosomes. Germ line reversion occurs at a high rate in D. mauritiana males and in interspecific hybrid females, while the rate is depressed in D. mauritiana females. These events are not restricted to the germ line, as cases of variegated patterns of eye pigmentation, indicating somatic reversion, are recovered at a frequency comparable to that of the male germ line reversion rate. Germ line reversion events are genetically stable, while the somatic variegation patterns are not heritable. The patterns of eye pigment variegation produced suggests that reversion events are occurring throughout development. Whole genome DNA digests blotted and probed with the cloned D. melanogaster white gene indicate that this unstable white mutation in D. mauritiana is associated with an insertion of DNA that is lost upon reversion to wild type, indicating that this DNA insert is in fact a transposable element.
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    Developmental Genetics 6 (1985), S. 297-297 
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    Keywords: Life and Medical Sciences ; Genetics
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  • 35
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    Developmental Genetics 7 (1986) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
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  • 36
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    Developmental Genetics 7 (1986), S. 65-73 
    ISSN: 0192-253X
    Keywords: long interspersed repeated DNA ; demethylation ; myeloma cells ; aging ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Sequences of DNA that hybridize on Southern blots with cloned EcoR1 1.3 kb (ER1) of long interspersed repeated sequence (L1Md) of mouse have been examined in genomic DNA of neonatal mice, livers and brains of adult mice (3, 10, 27, and 30 mo old), and the solid myeloma tumor MOPC-315. The isoschizomers Hpa II (CCGG or mCCGG) and Msp I (CCGG or CmCGG) were used to assess methylation. We found that the L1Md sequence is fully methylated in young animals but demethylated in myeloma. Demethylation of L1Md sequence also occurred in aged animals. By scanning the autoradiogram, we found that approximately 8% of the 104-105 copies have been demethylated in 27-mo-old liver.
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    Developmental Genetics 7 (1986), S. 75-80 
    ISSN: 0192-253X
    Keywords: DNA replication ; eggshell ; female sterile mutant gene amplification ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: K575 is a temperature-sensitive female sterile mutant which shows abnormal chorion structure and subnormal amounts of the major chorion proteins at the restrictive temperature. These phenotypes apparently result from a temperature-sensitive defect in amplification. Both clusters of chorion genes are affected, indicating that the gene operates in trans.
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    Developmental Genetics 7 (1986), S. 117-117 
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    Keywords: Life and Medical Sciences ; Genetics
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  • 39
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    Developmental Genetics 8 (1987), S. 1-9 
    ISSN: 0192-253X
    Keywords: T/t-complex ; LT mice ; parthenogenesis ; recombination ; gene-mapping ; primitive streak ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Ovarian teratomas that result from parthenogenetic activation of oocytes provide a double tool for developmental geneties. First, they provide a way of measuring recombination between a gene and its centromere. Second, in the absence of crossing over there is the potential of producing tumors that are homozygous for genes that would be lethal in the course of in utero embryonic development. We have applied both aspects to several t- haplotypes containing different early acting t-lethal genes. In a study of 26 tumors, genotyped by Southern blot analysis of the major histocompatibility complex (MHC), we measured the distance between the centromere and the start of the t-complex as 5.6 ± 2.3 cM. We found a marked deficiency of t-homozygous genotypes among the tumors we studied, although T/T genotypes formed teratomas at levels comparable to controls. None of the lethal t-haplotypes we studied permit homozygous embryos to develop to the primitive streak stage, while T/T embryos do develop essentially normally through that stage. Thus, although the total number of tumors observed from t-bearing mice was small, the great difference in the incidence of t/t tumors versus the incidence of T/T tumors suggests strongly that the parthenogeretic embryos that convert to teratocarcinomas must first pass through some of the stages of normal early development, including the formation of three germ layers and the primitive streak.
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    Developmental Genetics 8 (1987), S. 27-34 
    ISSN: 0192-253X
    Keywords: W locus ; mouse ; chromosome 5 lethal ; implantation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A recessive lethal mutant linked to Wsh causes the death of homozygous embryos between 4.5 and 5.5 days postcoitum (pc). Histological examination of implantation sites from intercross and backcross matings indicates that homozygotes are not all evident at 4.5 days pc, when embryos have begun to form trophectoderm giant cells and primitive endoderm, but are degenerating by 5.5 days pc, with only a few primary giant cells remaining after this time. The mutants thus form blastocysts that initiate the implantation process but the inner cell mass and polar trophectoderm fail to develop further. In vitro examination and culture of blastocysts indicated that the mutant homozygotes hatch from the zona pellucida and outgrow, although they do so somewhat more slowly than normal embryos. After 3 days of culture, the inner cell masses of mutant outgrowths may be smaller than normal. Since the gene has no known heterozygous effect and the primary gene function remains unknown, the mutant has been given the provisional symbol l(5)-1 for the first lethal on chromosome 5.
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    Developmental Genetics 8 (1987), S. 179-185 
    ISSN: 0192-253X
    Keywords: differentiation ; melanogenesis ; tyrosinase ; albino ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Albino mutation in animals blocks pigmentation owing to a deficiency in tyrosinase, although it does not affect the differentiation of colorless melanocytes from the neural crest. In the albino Japanese quail (al, sex-linked), it was demonstrated that morphologically normal melanocytes differentiated from neural crest cells in culture and that these cells contained unmelanized melanosomes as expected for the mutant cells. The mutant melanocytes, however, were shown to exhibit tyrosinase activity in the Golgi-endoplasmic reticulum-lysosome region and in the Golgi vesicles. Our results seem to indicate that the mutation at the al locus affects the transport of tyrosinase from the Golgi area to melanosomes.
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    Developmental Genetics 8 (1987), S. 187-187 
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    Keywords: Life and Medical Sciences ; Genetics
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    Developmental Genetics 8 (1987) 
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    Keywords: Life and Medical Sciences ; Genetics
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    Developmental Genetics 8 (1987), S. i 
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    Keywords: Life and Medical Sciences ; Genetics
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  • 45
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    Developmental Genetics 9 (1988), S. 549-559 
    ISSN: 0192-253X
    Keywords: adhesion proteins ; development ; mutations ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Three separate mechanisms of cell-cell adhesion have been shown to appear at different stages of development in Dictyostelium discoideum. During the first few hours of development, the cells synthesize and accumulate a glycoprotein of 24,000 daltons (gp24) that is positioned in the membrane. The time of appearance of gp24 correlates exactly with the time of appearance of cell-cell adhesion in two strains in which temporal control varies by several hours. Antibodies specific to gp24 are able to block cell-cell adhesion during the first few hours of development but not during later development. By 8 hr of development, another glycoprotein, gp80, that is not recognized by antibodies to gp24 accumulates on the surface of cells. This membrane protein mediates an independent adhesion mechanism during the aggregation stage that is resistant to 10 mM EDTA. Antibodies specific to gp80 can block EDTA-resistant adhesion during this stage. During subsequent development, gp80 is removed from the cell surface and replaced by another adhesion mechanism that is insensitive to antibodies to either gp24 or gp80.A λgtll expression vector carrying a Dictyostelium cDNA insert was isolated that directs the synthesis of a fusion protein recognized by antibodies specific to gp24. This cDNA was used to probe a genomic library. A clone carrying a 1.4-kb insert of genomic DNA was recognized by the cDNA and shown to hybridize to a 0.7-kb mRNA that accumulates early in development. This unusually small RNA could code for the small protein, gp24. Southern analysis of restriction fragments generated by various enzymes on Dictyostelium DNA with both the cDNA and genomic clones indicated the presence of two tandem copies of the gene. This may account for the failure to recover mutations resulting in the lack of gp24.Mutations have been recovered that result in the lack of accumulation of gp80, and cells carrying these mutations have been shown to be missing the second adhesion mechanism. These mutant strains are able to complete development because the other adhesion mechanisms are not impaired. Sequential addition of adhesion mechanisms provides a means for the formation of multicellular organisms from previously solitary cells.
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    Developmental Genetics 10 (1989), S. 63-69 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
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    Developmental Genetics 10 (1989), S. 53-62 
    ISSN: 0192-253X
    Keywords: Mouse T-locus ; Two-dimensional gel electrophoresis ; Embryonic development ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: T and Tc are dominant mutations in the mouse that affect neuroaxial development when heterozygous and cause embryonic death when homozygous. Embryos were analyzed individually by two-dimensional gel electrophoresis at 9½ days gestation, 1 day before homozygotes die in utero. A comparison of the protein patterns of mutant homozygotes with those of their littermates revealed a set of proteins (T-proteins) that showed isoelectric point (pl) polymorphism. All the T-proteins were more basic in mutant homozygotes. These polymorphisms could be detected, although they were less pronounced, in embryos as young as 7½-day presomite stages, when it is impossible to distinguish homozygous mutants grossly. Interestingly, the same proteins show a pl shift from basic to acidic in wild-type embryos during development from 7½ to 9½ days. Thus, it appears that in T and Tc mutants a developmentally specific posttranslational acidic modification of these proteins is disturbed. The likely cause of the abnormality is a defect in some mechanism for phosphorylation, since the T-proteins of wild-type embryos were shifted to higher pls by phosphatase treatment. This disturbance appears to be localized to axial structures (neural tube, somites, and surrounding mesenchyme) since only these structures, and not the rest of the mutant homozygous embryos, contain abnormally basic T-proteins.
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    Developmental Genetics 10 (1989), S. 106-111 
    ISSN: 0192-253X
    Keywords: Bithorax complex ; Variable penetrance suppression ; Enhancement ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Two modifiers of bithorax1 phenotypic expression are described. An X-chromosome region is associated with sexual dimorphism in bx1 penetrance. It is hypothesized that sexual dimorphism is in part due to a lack of dosage compensation of the modifier, in males. A third chromosome region that segregates with the pink peach allele is implicated in mediating temperature sensitivity. By appropriate combinations of modifiers, both sexual dimorphism and temperature sensitivity can be greatly reduced.
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    Developmental Genetics 10 (1989) 
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    Keywords: Life and Medical Sciences ; Genetics
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    Developmental Genetics 10 (1989), S. 123-123 
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    Keywords: Life and Medical Sciences ; Genetics
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    Developmental Genetics 10 (1989), S. 210-219 
    ISSN: 0192-253X
    Keywords: Intron ; Alcohol dehydrogenase ; Enhancer ; Promoter ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have used in vitro mutagenesis and somatic transformation [Sofer and Martin, 1987a; Martin et al., 1986] to investigate the role of cis-acting sequences in the control of alcohol dehydrogenase gene expression in larvae of Drosophila melanogaster. Two sets of experiments were carried out. In the first, a series of aeletions were constructed in the region upstream of the proximal transcriptional start site. In the second, one or both introns were removed from within the structural gene. These constructs (on circular plasmids) were injected into Adh-null embryos and ADH activity was assayed in third instar larvae of the injected generation. The first set of experiments indicated that there are at least three distinct regulatory regions essential for larval activity located in the 5′ flanking region of the gene. One, in an area that includes the TATA box, was found to be necessary but not sufficient for larval ADH activity. Two others, further upstream, seemed to have enhancer-like properties because their absence could be compensated by a second copy of the Adh gene on the same plasmid molecule. The second set of experiments showed that neither the tis-sue distribution nor amount of ADH activity was affected by the removal of one or both introns from the Adh gene.
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    Developmental Genetics 10 (1989), S. 220-231 
    ISSN: 0192-253X
    Keywords: Drosophila ; Fat body ; Ecdysone ; cis-acting regulatory elements ; Development ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The P1 gene, together with the LSP-1a, -1β, and -ly, LSP-2, and P6 genes, is expressed exclusively in the larval fat body of D. melanogaster during the third instar. In vivo mapping of the cis-acting regulatory sequences of the P1 gene was carried out using hybrid constructs with three different reporter genes and a combination of transient and germline transformation assays. This revealed that regulatory elements involved in the setting up of the temporal and spatial specificities of transcription of the P1 gene are located in a short DNA region immediately upstream of the mRNA transcription start. This region includes on element that behaves as a fat-body transcriptional enhancer and element(s) required for ecdysone inducibility of transcription of the P1 gene.
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    Developmental Genetics 10 (1989), S. 232-238 
    ISSN: 0192-253X
    Keywords: Transcriptional regulation ; Alternate splicing ; Neurotransmitters ; Learning ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The gene Ddc encodes two isoforms of the enzyme dopa decarboxylase in Drosophila. These gene products catalyze the final steps in the synthesis of the biogenic amines sero-tonin and dopamine. This article summarizes recent progress in understanding the tissue- and cell-specific regulation of Ddc, which occurs at both the transcription and alternate splicing levels. In addition, results that are pertinent to understanding the roles of biogenic amines in the neurophysiology of Drosophila are discussed.
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  • 54
    ISSN: 0192-253X
    Keywords: Transposable element ; Transcription factor ; Suppression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have used the yellow gene of Drosophila melanogaster as a model system in which to study the molecular mechanisms by which the gypsy retrotransposon causes mutant phenotypes that can be reversed by nonalleiic mutations at the suppressor of Hairy-wing locus. This gene encodes a 109,000 dalton protein that contains an acidic domain and 12 copies of the Zn finger motif, which are characteristic of some transcription factors and DNA binding proteins. The suppressible y2 allele is caused by the insertion of the gypsy element at -700 bp from the start of transcription of the Yellow gene, resulting in a phenotype characterized by mouth parts and denticle belts in the larvae, and by bristles in the adults, that show wildtype coloration, but mutant wings and body cuticle in the adult flies. This phenotype is the result of the interaction of gypsy sequences homologous to mammalian enhancers with tissue-specific yellow transcriptional regulatory elements located upstream from the gypsy insertion site and responsible for the expression of the yellow gene in the mutated tissues. This interaction is dependent on the binding of the su(Hw) protein to the specific gypsy sequences involved in the induction of the mutant phenotype.
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    Developmental Genetics 10 (1989), S. 249-260 
    ISSN: 0192-253X
    Keywords: Regulatory genes ; Pc group ; Drosophila embryogenesis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A wide variety of gain of function mutations have been induced in the Posterior Sex Comb (Psc) - Aristapedioid (Arp) - Suppressor 2 of zests(Su(z)2) region of the second chromosome of Drosophila. This region contains at least three apparently related genes, two of which we have been studying. Psc1 has previously been used to identify Psc as a Pc group gene; however, it is a complex mutation with both gain and loss of function character. We report here that the Pc group character of Psc is not due to a gain of function and presumably reflects the function of the wild-type gene. We also provide evidence for a maternal function for Psc, as well as the neighboring Su(z)2 gene.Su(z)2 does not appear to be a Pc group gene as it does not act in a synergistic fashion with other PC group genes in promoting posteriorly directed transformations. However, we have found that mutations in Su(z)2 do interact in a variety of interesting ways with mutations in Pc group genes.
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    Developmental Genetics 10 (1989), S. 311-317 
    ISSN: 0192-253X
    Keywords: β-globin ; Human erythroleukemia cells ; RNA transcripts ; K562 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Previous studies have indicated that control and hemin-treated human eryth-roleukemia K-562 cells fail to produce adult-type β-globin mRNA transcripts and to translate them into nascent β-globin chains. Expression of the β-globin DNA sequences in K-562 cells can occur, however, under certain conditions. To readdress this issue and to examine the possibility of whether these cells produce immature and untranslatable β-globin RNA transcripts, we prepared total cyto-plasmic RNA from control and inducer-treated cells and performed Northern blot hybridization analysis using 5′ end-labeled fragments of the human β-globin DNA rather than 3′ end fragments as probes. Although hybridization of both cytoplasmic and nuclear K-562 RNA with a32P-labeled 3′ end fragment (1.6kb Bam H1 cut) coding for a large part of the first exon of β-globin failed to detect β-globin RNA transcripts, hybridization with a 5′ end 32P-labeled 2.0kb Bam H1 fragment (coding for the third exon and part of the second) revealed the presence of relatively small (〈7S) RNA molecules both in nuclear and cytoplasmic fraction. S1 nuclease mapping of both cytoplasmic and nuclear RNA with the use of 5′ end-labeled 2.0 kb Bam H1 fragment of human β-globin DNA indicated protection of a small portion located 64bp 5′ upstream from the Bam H1 site of the second exon. The amount of protected portion was relatively higher in K-562 cells undergoing erythroid maturation. These findings suggest that control and differentiating K-562 cells synthesize β-globin-like RNA transcripts that are 3′ end short, immature, and unable to give rise to adult β-globin chains. These results also indicate that K-562 cells may lack factors that are unique for transcription and processing of the human β-globin RNA transcripts.
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    Developmental Genetics 10 (1989), S. 345-345 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
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    Developmental Genetics 10 (1989) 
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    Keywords: Life and Medical Sciences ; Genetics
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    Developmental Genetics 10 (1989), S. 347-347 
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    Keywords: Life and Medical Sciences ; Genetics
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  • 60
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    Developmental Genetics 10 (1989), S. 339-344 
    ISSN: 0192-253X
    Keywords: Delayed processing ; Splicing ; Transcription ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This study deals with the pattern of developmental expression of the catalase gene in mice. We have used a mouse catalase 2 kb cDNA (pMCT-1) and its 1.4 kb 5′ fragment as probes to characterize the transcripts during embryonic development and differentiation. Total RNA was isolated from 8 days postconceptus (p.c.) whole embryos and from livers and carcasses of 13, 15, and 18 day p.c. embryos as well as from the livers of newborn and adult mice of the S.W. strain. The RNA was applied on slot blots, and run on agarose gels to generate northern blots. Blots were hybridized with the 32P-labeled cDNA probe under different stringency conditions. Autoradiograms were scanned with a densitometer to quantify relative hybridization signals of RNA samples obtained from two or three individual mice representing each stage of development.The catalase transcript is detectable as early as 8 days p.c. with the beginning of somite formation. At this stage, it is primarily in the form of a 12.2 kb transcript. One additional band (2.4 kb) is also apparent at this stage although at a very low intensity. The intensity of the two bands increases with development, particularly during 13-18 days p.c. in liver and carcass. The 2.4 kb RNA band increases sharply from day 8 through 13, 15, and 18 days p.c. and is confined primarily to the liver. Interestingly, only the 2.4 kb RNA band is seen at and after birth. The 2.4 kb RNA is the known mature message of the catalase gene in mice. The presence of large catalase-specific RNA species (seen during development in utero only) is interpreted as the primary transcript of this gene. The complete and efficient processing of this primary transcript takes place only after birth and primarily in the liver, which may be related to the physiological role of this enzyme in oxygen metabolism, particularly stressful superoxides, expected with independent respiration. At a lower stringency wash of the northern blots, a 9.5 kb RNA was seen during a narrow window of in utero development. This 9.5 kb band may represent an uncharacterized catalase-related gene with a possible role in development and differentiation.
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    Developmental Genetics 10 (1989), S. 349-355 
    ISSN: 0192-253X
    Keywords: SV40 promoter ; Expression vector ; Drug resistance ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have previously demonstrated systemic resistance to methotrexate (MTX) in transgenic mice carrying a foreign, mutant dihydrofolate reductase (DHFR, E.C. 1.5.1.3) gene. The new gene was introduced as a cDNA cloned into an expression vector driven by the simian virus 40 (SV40) early promoter. Previous physiologic studies suggested that transgenic mice tolerated drug doses invariably lethal to controls on the basis of gastrointestinal (GI) resistance to MTX. In the present study we evaluated foreign gene expression at the RNA level in the three major sites of MTX toxicity: intestine, liver, and bone marrow.The transgene was transcriptionally active in small bowel, and levels of expression were high in animals tolerating the largest doses of MTX. The gene was also expressed in the liver in some pedigrees, but was not detected in hemopoietic tissues of any of the pedigrees tested. Our studies correlate the site of expression of a drug resistant dhfr gene with an altered physiologic response to MTX, and demonstrate that transgenic mice can be used as a test system for expression of genes considered for use in somatic gene therapy.
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    Developmental Genetics 10 (1989), S. 356-364 
    ISSN: 0192-253X
    Keywords: Glucose intolerance ; Insulin resistance ; Diabetes mellitus ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We are investigating human insulin gene expression in transgenic mice. An 8.8 kilobase (kb) human genomic DNA fragment, including the insulin gene (1.4 kb) and 2 kb of 5′ human flanking sequences, was introduced into mouse embryos by pronuclear microinjection. Two lines of transgenic mice have been established, both of which carry the intact human gene in multiple copies. Animals from both lines have significantly higher insulin levels than control mice, and the degree of hyperinsulinemia shows a positive correlation with human gene copy number in the two lines. Expression of the human gene is confirmed by the detection of human C-peptide in plasma. Tissue specificity of expression is maintained, with human insulin mRNA detectable only in the pancreas. The transgenics maintain normal fasting blood glucose in spite of their high insulin levels, but preliminary studies show them to be glucose intolerant when given a glucose load. These mice provide a model system for further studies on the regulation of insulin gene expression and on the effects of chronic hyperinsulinemia on glucose homeostasis.
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  • 63
    ISSN: 0192-253X
    Keywords: Pentraxins ; Acute phase protein ; Lipopolysaccharide ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: To analyze the regulation of human serum amyloid P component (SAP) gene expression, we have produced seven transgenic mice. The 3.3 kb human SAP genes containing about 0.8 kb of 5′ and 1.5 kb of 3′ flanking region were injected into fertilized eggs of C57BL/6 mice. In five of the seven transgenic mice, human SAP was detected in the sera and serum concentrations were higher than that of human serum in three lines. The human SAP gene was expressed only in the liver. Amounts of human mRNA in the liver and serum concentrations of human SAP were roughly proportional to the copy number of the integrated gene. Human SAP production lowered the serum levels of mouse endogenous SAP. With the intraperitoneal administration of lipopolysaccharide, the mRNA levels in the liver and serum levels of mouse SAP increased several-fold in both the control and transgenic mice. On the other hand, neither the mRNA nor the serum levels of human SAP increased significantly.
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    Developmental Genetics 10 (1989), S. 386-392 
    ISSN: 0192-253X
    Keywords: Vestigial ; Cell death ; Modifier genes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: An analysis of the modifiers affecting the expression of the vg gene was performed. We selected for weak and strong expression of the vg mutant in 2 segregating populations obtained by crossing a vestigial stock with an Oregon laboratory stock (O) and with a wild strain (B) captured near Bologna, Italy. The selection for enlarged wings was more effective in the vg B population where wild wings appeared from the lCth generation. The assay of the three major chromosomes showed that the modifiers are located on chromosomes 2 and 3. The mutant imaginal disc cell death phenotype is evident in vg/vg strains that have a wild-type wing phenotype. It is suggested that the selected modifiers do not prevent cell death but induce regenerative growth.
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  • 65
    ISSN: 0192-253X
    Keywords: Monoclonal antibodies ; Myogenesis ; Adult isoforms ; Quail ; Chicken ; Muscle development ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have raised monoclonal antibodies (Mabs) to myosin heavy chain isoforms (MHCs) that have specific patterns of temporal expression during the development of quail pectoral muscle and that are expressed in very restricted, tissue-specific patterns in adult birds. We find that an early embryonic, a perinatal, and an adult-specific, fast myosin heavy chain a.e co-expressed at different levels in the pectoral muscle of 8-12 day quail embryos. The early embryonic MHC disappears from the pectoral muscle at approximately 14 days in ovo, whereas the perinatal MHC persists until 26 days post-hatching. The adult-specific MHC accumulates preferentially and eventually completely replaces the other isoforms. These Mabs cross-react with the homologous isoforms of the chick and detect a similar pattern of MHC expression in the pectoral muscle of developing chicks. Although the early embryonic and perinatal MHC isoforms recognized by our Mabs are expressed in the pectoral muscle only during distinct developmental stages, our Mabs also recognize MHC isoforms present in the heart and extraocular muscle of adult quail. Immunofingerprinting using Staphylococcus aureus protease V8 suggests that the early embryonic and perinatal MHC isoforms that we see are strongly homologous with the adult ventricular and extraocular muscle isoforms, respectively. These observations suggest that at least three distinct MHC isoforms, which are normally expressed in adult muscles, are co-expressed during the early development of the pectoral muscle in birds. In this respect, the pattern of expression of the MHCs recognized by our Mabs in developing, fast muscle is very similar to the patterns described for other muscle contractile proteins.
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    Developmental Genetics 10 (1989) 
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    Keywords: Life and Medical Sciences ; Genetics
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    Developmental Genetics 10 (1989), S. 460-472 
    ISSN: 0192-253X
    Keywords: Transposable elements ; Maize ; Mutation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The high frequency of mutations in Mutator stocks of maize is the result of transposition of Mu elements. Nine different Mu elements that share the 220 bp Mu terminal inverted repeats have been described. Mul elements have been found inserted into most of the molecularly characterized mutant alleles isolated from Mutator stocks, and most Mutator stocks contain a high number of Mul elements (10-60). However, it is clear that additional Mu elements, which share the Mul termini but have unrelated internal sequences, can also transpose in Mutator stocks. We were interested in comparing the mutation frequency and type of elements that inserted into a particular locus when Mutator stocks with differing numbers of Mul elements were utilized. Furthermore, previous studies with Mu-induced mutations have demonstrated that the element that inserted most frequently was Mul. Therefore, to try to obtain Mu elements different from Mul we utilized a stock that had a low number (3-6) of Mul elements as well as a Mutator stock with a more typical number of Mul elements (20-60).Utilizing both stocks, we isolated numerous mutants at one gene, Bronze1 (Bz1), and compared the type of elements inserted. In this paper we report that both the high and low Mu1 stocks produced bz1 mutants at frequencies characteristic of Mutator stocks, 6.6 and 4.3 ± 10-5, respectively. We describe the isolation of 20 bz1 mutations, and the initial molecular characterization of eight unstable mutations: two from the high Mu1 stock and six from the low Mu1 stock. The six alleles isolated from the low Mu1 stock appear to contain deleted Mu1 elements, and the two alleles isolated from the high Mu1 stock contain elements very similar to Mu1. When the mutants from the low Mu1 stocks were examined, it was found that the Mu1 -related elements increased from 3-6 copies to 9-20 copies in one generation. The high number of Mu1 -related elements was maintained in subsequent out-crosses. This spontaneous activation and amplification of Mu -related elements occurred in at least 1% of the low Mu1 plants.
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    Developmental Genetics 10 (1989), S. 482-506 
    ISSN: 0192-253X
    Keywords: Mutator ; Transposable elements ; Controlling elements ; Autonomous elements ; Regulator elements ; Mutable genes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The Mutator transposable element system (Mu) of maize has been responsible for the induction of numerous mutable aleurone mutants of maize. Unlike similar mutants induced by other transposable element systems, the mutability of Mu-induced mutants did not seem initially to be regulated by an independent autonomous or regulator element. However, in a continuing study of two Mu-induced a1 mutable mutants (a1-Mum2) and a1-Mum3, lines have been obtained that give evidence of an independently segregating regulator of somatic mutability. Data from several generations of crossing are presented indicating that intense somatic mutability in many of these stocks is under the control of an independent regulator. However, testing of other lines, which initially gave evidence of the presence of an independent regulator, were negative. Some of these latter lines could be expected to have Mutator elements that were modified (methylated) at sites recognized by certain restriction endonucleases. Modification of Mu elements, which is known to affect the expression of somatic mutability, might, at times, be responsible for producing conditions that mimic the segregation of an independent regulator. Lines with stable derivatives of the a1-Mum2 and a1-Mum3 can recover intense somatic mutability by crossing with germinally active Mutator stocks. Thus, active Mutator lines contain regulator elements and evidence is presented suggesting that such lines have multiple copies of these elements. Most a1- Mum2 and a1-Mum3 stocks segregating for a regulator do not have germinal Mutator activity. Thus the presence of one or a few putative regulator elements does not necessarily account for the high level of germinal activity in most Mutator stocks.
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    Developmental Genetics 10 (1989), S. 542-551 
    ISSN: 0192-253X
    Keywords: Glycine max ; Transposable element ; Transposon tagging ; Genetic instability ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: An unstable mutation for anthocyanin pigmentation in soybean (Giycine max [L.] Merr.) was identified in 1983. The mutability is conditioned by an allele at the w4 locus that is recessive to wild type. The population containing the mutable allele is known as the w4-mutable line. Most plants in the line have chimeric flowers with purple sectors on a near-white background. The mutable allele yields germinal revertants at a rate that varies from 5 to 10% per generation, and the revertant alleles are stable. Approximately 1% of the progenies derived from germinal revertant plants contain mutations at other loci These features, as well as the occurrence of pale flower phenotypes and changes of state, suggest that a transposable element system is producing the unstable phenotype.Several new mutants were isolated in an experiment designed to tag loci. The first three chlorophyll-deficient mutants found (CD-1, CD-2, and CD-3) are inherited as single-gene recessives. Each of the mutants lacks the same two mitochondrial malate dehydrogenase (MDH) bands. No recombination has been detected between the MDH phenotype and the chlorophyll-deficient phenotype. Genetic data indicate that the three mutants are allelic, and additional evidence suggests that each of the CD mutants is the result of a deletion. In the CD-1, CD-2, and CD-3 mutants, the deletions result in the silencing of an MDH locus, atypical chloroplast development, and an altered chlorophyll composition. Additional mutants for root necrosis, partial and near sterility, chlorophyll deficiency, and flower color isolated from the transposon tagging study have provided material for future research.
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    Developmental Genetics 3 (1982), S. 129-142 
    ISSN: 0192-253X
    Keywords: glycerol phosphate dehydrogenase ; turnover ; Drosophila ; gene dosage ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In vivo radiolabeling of Drosophila melanogaster sn-glycerol-3-phosphate dehydrogenase (E.C. 1.1.1.8; GPDH) has been accomplished by microinjection of 3H-leucine into anesthetized flies. Comigration of immunoprecipitated radiolabeled GPDH with purified 14C-labeled GPDH-1 in SDS polyacrylamide disc gels has established the monospecificity of our immunoprecipitation technique. Short-term uptake experiments have demonstrated that maximum radiolabel incorporation of total TCA precipitable protein and immunoprecipitable GPDH-1 occurs within 4 hours postinjection, with GPDH-1 accounting for approximately 1% of the total radiolabeled TCA precipitable protein. In order to develop the parameters for turnover studies of GPDH in Drosophila, a comparative analysis of the rates of synthesis and degradation of GPDH-1 in flies bearing two and three doses of the structural gene have been conducted by the construction of adult flies aneuploid and euploid for the cytogenetic region 25F-26B on the left arm of chromosome II. Short-term uptake studies have demonstrated that the rate of GPDH-1 synthesis in the three-dose flies is approximately 1.58 times that found in the two-dose euploid flies. This value is in close agreement with data obtained for steady-state levels of CRM by rocket immunoelectrophoresis. In contrast, longterm pulse-chase experiments have revealed that rates of GPDH-1 degradation in these aneumploid and euploid flies appear to be identical. These data suggest that the rate of GPDH-1 synthesis in Drosophila is primarily regulated by a tightly linked cis-acting element which appears to act autonomously with respect to gene copy number as well as steady-state GPDH protein levels.
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    Developmental Genetics 3 (1982) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
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    Developmental Genetics 3 (1982), S. 275-282 
    ISSN: 0192-253X
    Keywords: Drosophila ; sex chromosomes ; gene dosage ; gene expression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In Drosophila, the ratio of the number of X chromosomes to sets of other chromosomes initiates a series of events which result in sexual differentiation. In addition, this ratio establishes dosage compensation, a mechanism which equalizes the products of X-linked genes in males and females. The present review discusses possible genetic entities responsible for the interpretation of chromosomal sex and subsequent sex-mediated regulation during development.
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    Developmental Genetics 3 (1982), S. 309-327 
    ISSN: 0192-253X
    Keywords: Drosophila melanogaster ; DNA polymerase ; developmental enzyme profile ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: An assay procedure was developed that allowed the first reproducible measurement of DNA polymerase activity in all developmental stages of Drosophila melanogaster. Evidence is presented that the same enzymatic species is present in extracts of embryos, pupae, and adults of both sexes and that this activity has many properties similar to vertebrate α-polymerases. Polymerase activity per individual is low in embryos and rises steadily through larval instars, reaches a peak in early pupae, declines through the late pupal period, and remains low in newly eclosed adults of both sexes. A dramatic increase is observed in adult females as mature oocytes are formed. This pattern of enzyme activity is completely coincident with changes in DNA levels during development, and suggests that the Drosophila enzyme, like vertebrate α-polymerases, functions in cellular DNA replication. Two mutagen-sensitive mutants, deficient in both replication on undamaged templates and postreplication repair, were found to have normal levels of this α-polymerase activity. Our results suggest that a single enzymatic species of α-polymerase holoenzyme exists in Drosophila and is common to all developmental stages of this organism.
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    Developmental Genetics 3 (1982), S. 283-297 
    ISSN: 0192-253X
    Keywords: Dictyostelium discoideum ; cAMP-unresponsive mutants ; parasexual genetic analysis ; cell differentiation ; chemotaxis to folate and cAMP ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: To find mutants of Dictyostelium discoideum that are unable to respond to exogenous cAMP signals (frigid mutants), amoebae of 218 independent aggregation-deficient mutants were treated in suspension with artificial pulses of cAMP and screened for the capacity to form EDTA-resistant cohesion sites. Eleven frigid mutants were identified and further characterized. Using parasexual genetic techniques, these strains were assigned to five complementation groups (fgdA-E) and the fgd loci were mapped in three linkage groups: fgdA and D in group II, fgdC in group III, and fgdB and E in group VII. Biochemical and physiological experiments with these strains indicated that fgd mutants are of two general types. When starved, strains in groups fgdB, D, and E failed to produce detectable levels of membrane-associated cAMP phosphodiesterase, surface cAMP receptors, or extracellular phosphodiesterase inhibitor, and the cells continued to respond chemotactically to folate. Thus, these strains are probably arrested in the vegetative phase or very early in development. In contrast, strains in groups fgdA and C produced low levels of cAMP receptors and secreted phosphodiesterase inhibitor. Moreover, after starvation, some of these mutants elicited a weak chemotactic response to cAMP. Therefore, unlike the former group of mutants, these strains appear to initiate development when starved, but the process is blocked at an early stage.
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    Developmental Genetics 4 (1983), S. 1-20 
    ISSN: 0192-253X
    Keywords: gene transfer ; mouse embryos ; genetic engineering ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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    Developmental Genetics 4 (1983), S. 21-29 
    ISSN: 0192-253X
    Keywords: agouti locus ; embryonic lethal ; ax ; lethal nonagouti ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The time and mode of action of the homozygous ax gene, lethal nonagouti, has been investigated on the inbred AX/Pa background. Heterozygotes were mated inter se to produce 25% homozygous embryos and heterozygotes were mated with homozygous, nonagouti mice to provide control litters. Comparisons of the frequency of mating success, the ratio of implantation sites to ovarian ovulation sites, and the average litter sizes between experimental and control matings all indicated that ax/ax embryos are not lost prior to implantation. Histological examination of pregnant uteri indicated that ax/ax embryos are first evident as abnormal blastocysts at 4.5 days post coitum (pc). These implant and develop to varying degrees, some differentiating trophoblast giant cells and a primitive endoderm layer. Growth is retarded and only small, disorganized clumps of tissue remain by 7.5 and 8.5 days pc. The time and mode of gene action of lethal nonagouti is thus different from its allele, lethal Yellow.
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    Developmental Genetics 4 (1983), S. 61-68 
    ISSN: 0192-253X
    Keywords: cell adhesion ; macromolecular ; sponge factors ; Dictyostelium ; adhesion-blocking antiserum ; staggerer mutant ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cellular adhesion is what keeps cells together in multicellular organisms. Cells adhere to each other, to extracellular matrices, and to the substratum. Biochemical analyses of these processes have suggested some of the types of surface molecules which may be involved, but definitive evidence must rely on effective reconstruction of functional membranes or genetic alteration of the pertinent genes. Together these approaches may give us a better understanding of how cells sort out and form tissues during development.
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  • 78
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    Developmental Genetics 4 (1983), S. 77-97 
    ISSN: 0192-253X
    Keywords: behavioral mutation ; Drosophila ; flightlessness ; temperature sensitive ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mutations in 13 genes with temperature-sensitive (ts), flightless phenotypes have been examined. All hop and fly well when raised at the permissive temperature, but fly poorly, or not at all, when raised at the restrictive temperature. The mutations were divided into three groups on the basis of their temperature-sensitive periods (TSPs) for flightlessness. The TSPs for mutations at five loci, fli-C1, D1, E1, I1, and shak A1, in the first group are confined to 24 to 48 hr interval during early pupal development. Mutations in the second group, including eag101, fli B1, and futs1 have continuous TSPs 3 to 4 days in length, extending from late larval through the early pupal stages. The flight TSPs for mutations in the third class, including fli J1, fli K2, flrd H3, and flrd N1, are almost continuous, and span most of the larval and pupal periods. Many of the mutations have pleiotropic phenotypes, including semilethality and lethality, and wing posture and cuticle abnormalities, with discernible TSPs. One of the more intriguing pleiotropic phenotypes is the ts optomotor response exhibited by fli J2, the TSP for which extends from late larval through late pupal stages.
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  • 79
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    Developmental Genetics 4 (1983), S. 69-76 
    ISSN: 0192-253X
    Keywords: Polysphondylium ; cellular slime mold ; microcysts ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mutants were selected that are incapable of differentiating microcysts, a resting stage formed in response to high osmotic conditions. In the selection procedure amebae that failed to encyst were removed by flotation in 46% Percoll. Genetic crosses among 15 mutant strains were made by means of the macrocyst sexual cycle. Eleven of the strains mapped to three loci. Mutations at two of these loci (cysA and cysB) produced no observable alteration in the aggregation-fruiting pathway, although one set of strains altered at the cysA locus carried defects at a second unlinked site which blocked aggregation. The single strain that defined the third locus (cysC) is aggregateless. These results confirm the conclusion that there are several genes whose function is essential to microcyst development and is exclusive to this pathway. It remains uncertain whether there are other genes whose action is crucial to both encystment and to aggregation/fruiting.
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  • 80
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    Developmental Genetics 4 (1983), S. 143-143 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 81
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    Developmental Genetics 4 (1983), S. 117-127 
    ISSN: 0192-253X
    Keywords: Physarum polycephalum ; differentiation ; food supply ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The effect of food supply on the onset of asexual and sexual plasmodium formation in Physarum polycephalum was studied. Asexual differentiation occurs readily in amoebae carrying the matAh mating type allele. The density at which these amoebae begin to differentiate is influenced by the ind locus, which controls the production of a diffusible inducer. The alleles ind-1 and ind-2 are known. Strains carring the ind-1 allele begin plasmodium formation at a low amoebal density (rapid differentiation), while strains carring the ind-2 allele differentiate at a higher amoebal density (slow differentiation). The onset of differentiation is characteristic of the strain and did not change with a 20-fold variation in the number of food bacteria available. Sexual differentiation occurs between compatible amoebal strains. For a given pair of amoebal strains the onset of plasmodium formation occurs at a characteristic cell density that is determined by the genetic backgrounds of the strains. The ind locus is one of the genes that influences this cell density. Plasmodia are formed at a lower cell density in crosses involving compatible amoebae carrying the ind-1 allele than they are in crosses with strains carrying the ind-2 allele. As was found for asexual differentiation, an approximate 20-fold variation in the food supply did not affect the initiation of sexual plasmodium formation. These results suggest that in most cases starvation does not trigger the differentiation of amoebae into plasmodia. The time of onset of plasmodium formation is determined largely by genetic factors.
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  • 82
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    Developmental Genetics 4 (1983) 
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    Keywords: Life and Medical Sciences ; Genetics
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  • 83
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    Developmental Genetics 4 (1983), S. 229-230 
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    Keywords: Life and Medical Sciences ; Genetics
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  • 84
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    Developmental Genetics 4 (1983) 
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    Keywords: Life and Medical Sciences ; Genetics
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  • 85
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    Developmental Genetics 4 (1983), S. 199-210 
    ISSN: 0192-253X
    Keywords: aging ; Drosophila ; behavior ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The question as to the role that genes play in determining life-span is essentially unresolved. Although it is well documented that genotype influences longevity, this is no way demonstrates that life-span is genetically determined. In the present study we examine five temperature-sensitive mutations for their effect on the aging process. At the permissive temperature (22°C ), the longevity of each mutant strain is comparable to that of wild type. However, at the restrictive temperature (29°C ) the life-span of these mutants is severely curtailed. Using behavior loss as a landmark of adult physiological age, we examined each of these strains for its pattern of behavior loss relative to longevity, and compared each to a wild-type strain. In four of the mutations the pattern of behavior loss relative to longevity was severely altered at one or both temperatures. However, one strain, adl-16tsl displayed a pattern of behavior loss that was indistinguishable from wild type at both 22°C and 29°C. At 29°C not only was the longevity decreased, the pattern of behavior loss was also compressed into a shorter time period. The compression of the pattern of behavior loss was proportional to the reduction in life-span. Thus it appears that this mutation, adl-16tsl, may accelerate the normal aging process when placed at 29°C. The potential utility of these types of mutants for studying the aging process is discussed.
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  • 86
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    Developmental Genetics 4 (1983), S. 231-231 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
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  • 87
    ISSN: 0192-253X
    Keywords: Drosophila ; small heat-shock protein genes ; ecdysterone ; regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The four small heat shock protein genes of Drosophila are tightly linked at the level of DNA, and are coordinately regulated. In cultured cell lines their expression is induced by high temprature shock and by physiological doses of ecdysterone. In vivo, small heat shock gene expression is developmentally regulated. Using recombinant DNA clones we have characterized and compared small hsp gene induction in response to the two independent stimuli.
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  • 88
    ISSN: 0192-253X
    Keywords: chimera ; cell interactions ; sex reversed ; sex determination ; melanocyte ; intersex ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The manufacture of mammalian chimeras by aggregating embryos of different genetic constitutions makes possible the study of the genetic control of cellular interactions during embryonic development. Several different chimeric combinations have been made to study the role of the sex-reversed mutation in gonadogenesis and in gametogenesis. Sex reversed directs the gonad to become a testis and thus renders a SxrXX mouse sterile since gonocytes with two X chromosomes cannot complete gametogenesis in a testis. However, SxrXX gonocytes in the ovary of a female chimera become normal oocytes. The competitive interactions of genetically different melanoblasts in populating hair follicles and of primordial germ cells in populating the gonad have been revealed in chimeras. Chimeras have also been used to rescue inviable teraploid embryos and to permit teteraploid cells to display their differentiative capacities in normal tissue environments. We conclude that the genotype affects the capacity of cells to elaborate and to respond to inductive stimuli at each step in differentiation. The fine tuning of cellular interactions becomes apparent in chimeras made from embryos of different genotype.
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  • 89
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    Keywords: retrovius ; chromosomal evolution ; feline genetics ; somatic cell genetics ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A combination of technical advances (most notably heterologous cell fusion, high resolution G-banding, and molecular cloning) has contributed to an accelerated advance in genetic analysis in mammals. The present human genetic map contains over 400 gene assignments and the map is growing rapidly as each new molecular clone or immunological reagent is developed. In our laboratory, we have developed a panel of rodent X human somatic cell hybrids that have been utilized in chromosome assignment of several classes of genes including oncogenes (ras, raf) and endogenous human retroviral sequences (ERVL, 2, etc). Using similar techniques, a biochemical genetic map of the domestic cat has been derived. The cat has 19 chromosome pairs and, to date, 40 genes have been mapped to 16 linkage or syntenic groups. Comparison of linkage relationships between homologous enzymes has revealed a striking conversation of chromosomal linkage association between cat and man. A comparison of syntenically homologous, highly extended high resoultion G-banded chromosomes between the two mammalian families revealed that 20-25%, by length, of the human karyotype can be precisely aligned (chromomere to chromomere) between cats and man despite the evolutionary divergence of the species nearly 80 million years ago.Moderately repetitive families of retrovirus-related DNAs exist within the feline and the human genomes. We have isolated molecular clones of several members of the feline RD-114 retrovirus family from a genomic library of normal cat cellular DNA. The endogenous sequences analyzed were similar to each other in that they were colinear with RD-114 proviral DNA, were bounded by long terminal redundancies, and conserved many restriction sites in the gag and pol regions. Several sequences were apparently deleted, relative to the previously characterized inducible RD-114 genome. The env regions of a number of endogenous RD-114 sequences examined were substantially deleted or diverged; a subset of these sequences contained information at the position of the env region that was not homologous to inducible RD-114. The RD-114 virogenes were dispersed to several cat chrosomes that were localized using a panel of rodent x cat somatic cell hybrids. A comparison of the genetic properties of endogenous human retroviral sequences revealed several similarities between the human and feline status of endogenous retroviruses.
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    Developmental Genetics 4 (1983), S. 451-451 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
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  • 91
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    Developmental Genetics 5 (1984) 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
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  • 92
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    Developmental Genetics 4 (1983), S. 407-424 
    ISSN: 0192-253X
    Keywords: selection ; enzyme ; control-gene ; DNA polymorphism ; Drosophila ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The control of alcohol dehydrogenase (ADH) activity in natural populations of Drosophila melanogaster is chromosomally diverse and due to variation in allotype, enzyme level, and possibly post-translational modification. A comparative study of evolution in Adh structural gene variations with those loci modifying ADH expression has been carried out in large model populations maintained in environments that varied in temperature and food. Broadly based measures of gene expression were obtained as ADH activity and ADH protein level (determined immunologically) from individual flies whose allotype was also determined. The response to selection by “regulatory” or modifier loci compared with ADH allotypes was found to vary with environment, and its direction was not necessarily predictable from the kinetic properties of allele products. Selection for dominance modification of ADH activity in relation to Adh allotype was also observed. Analysis of genotype-environment interaction discerned two main types of response. Two major classes of chromosomal types, identified from restriction endonuclease map variations in a 12-kb region of DNA containing the Adh transcriptional unit, were present in the population. These two types of chromosome were in turn associated with the two types of interaction between genotypes and the environment. The results implicate polylmorphism for the control of genotypeenvironment interaction in populations, a genetically complex unit of selection, and a degree of evolutionary independence between structural and regulatory genes.
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  • 93
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    Developmental Genetics 4 (1983), S. 425-438 
    ISSN: 0192-253X
    Keywords: polymorphism ; enzyme ; control gene ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A study was made of environmental and genetic factors affecting the quantity and disposition of the alcohol dehydrogenase (ADH) protein in Drosophila melanogaster. It was found that the amount of enzyme per fly is greatly influenced by the environmental conditions in which it develops. A critical factor is the concentration of yeast in the medium. A high concentration of yeast can double the quantity of ADH. The yeast appears to act through the provision of protein, and the protein to act through the provision of threonine, which is already known to induce ADH in fungi.Various genetic factors affect the quantity of enzyme. Males have more ADH than females. Files homozygous for the Fast allele have more ADH than those homozygous for the slow allele, and the difference is greater in females than in males. One particular line (ve), homozygous for Slow, has approximately half the normal quantity of enzyme, and the quantity segregates with the electrophoretic allele. Lines differ in the relative amounts of ADH in the gut (including Malpighian tubules) and the fat body. In general it seems that slow lines have relatively more enzyme in the fat body. In a cross between ve and a line homozygous to Fast, the difference in tissue distribution segregated with the electrophoretic allele. It is argued, but not demonstrated, that the differences in quantity and tissue distribution are due to nucleotide substitutions in noncoding regions close to, or within, the structural gene.It seems likely that the observed environmental and genetic differences in the quantity and disposition of ADH will influence the relative selective values of the electrophoretic genotypes.
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  • 94
    ISSN: 0192-253X
    Keywords: Drosophila ; electrophoretic variation ; quantitative variation ; ecology ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Electrophoretic variation at three enzyme loci-alcohol dehydrogenase (Adh), glycerophosphate dehydrogenase (Gpdh), triosephosphate isomerase (Tpi)- is compared in Australian Drosophila melanogaster populations at three levels of spatial heterogeneity; among breeding sites, within populations, and between populations at the geographic level. Heterogeneity at the breeding site level greatly exceeds that among adults within populations, indicating greater intermixing at the mobile adult stage than at the developmentally immature and less migratory larval stage. Heterogeneity at the microspatial level is large relative to the geographic level at two of these loci.Spatial patterns of variation in ecological phenotypes are also considered. It is argued that electrophoretic variants may contribute little to an understanding of this quantitative variation, and that a more useful approach in ecological genetics is to consider ecological phenotypes as primary data.
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    Developmental Genetics 5 (1984), S. 1-25 
    ISSN: 0192-253X
    Keywords: maize ; endosperm ; mutants ; Life and Medical Sciences ; Genetics
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  • 96
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
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  • 97
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    Developmental Genetics 5 (1984), S. 43-58 
    ISSN: 0192-253X
    Keywords: ciliate genetics ; Tetrahymena malaccensis ; karyonidal inheritance ; macronuclear assortment ; selfing ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mating type determination in Tetrahymena malaccensis is karyonidal, ie, the four new macronuclei developing in a single conjugating pair are independently determined as to which of the six known mating types they will express. Occasional selfing clones are similar to those in T thermophila, in that any one is capable of stabilizing at a restricted range of mating types. The genetic basis of mating type potentialities is incompletely resolved. T malaccensis may, like T thermophila and T canadensis, have a single multiallelic locus that controls the array of types. Quantitative considerations suggest, however, that other loci may be involved.
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  • 98
    ISSN: 0192-253X
    Keywords: gonad differentiation ; gene expression ; two-dimensional micro gel electrophoresis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Gonadal protein patterns were studied during development in the rat by two-dimensional micro-gel electrophoresis. Specific proteins were detected in both the male and the female sex at the morphologically indifferent state (two female- and one male-specific) and during differentiation. At the onset of gonadal differentiation (day 14) two additional sex-specific proteins were discovered in the male and two in the female. These proteins remained expressed during further development. One testicular protein was restricted to the cytosol of the tunica albuginea. The other one was absent from the tunica. In the female gonad, the two proteins were membrane-specific, one present in germ cells, the other in somatic cells. In the testis, one additional protein was discovered at postnatal day 1. Thus according to biochemical criteria there is no indifferent state of gonadal development. The testis and ovary express sex-specific genes both before and after the onset of gonadal differentiation.
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    Developmental Genetics 5 (1984), S. 63-63 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
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    Developmental Genetics 5 (1984) 
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    Keywords: Life and Medical Sciences ; Genetics
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