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  • 1
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 1 (1979), S. 1-1 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0192-253X
    Keywords: developmental mutants of Physarum ; apogamic mutants ; the amoebal-plasmodial transition ; myxomycete genetics ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In the heterothallic myxomycete Physarum polycephalum, uninucleate amoebae normally differentiate into syncytial plasmodia following heterotypic mating. In order to study the genetic control of this developmental process, mutations affecting the amoebal-plasmodial transition have been sought. Numerous mutants characterized by self-fertility have been isolated. The use of alkylating mutagens increases the mutant frequency over the spontaneous level but does not alter the mutant spectrum. Three spontaneous and 14 induced mutants have been analyzed genetically. In each, the mutation appears to be linked to the mating type locus. In three randomly selected mutants, the nuclear DNA content is the same in amoebae and plasmodia, indicating that amoebal syngamy does not precede plasmodium development in these strains. These results indicate that a highly specific type of mutational event, occurring close to or within the mating type locus, can abolish the requirement for syngamy normally associated with plasmodial differentiation. These mutations help define a genomic region regulating the switch from amoebal to plasmodial growth.
    Additional Material: 1 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0192-253X
    Keywords: Drosophila melanogaster ; pupae ; heat shock ; protein synthesis ; phenocopies ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Pupae of Drosophila melanogaster were heat-shocked under conditions required to induce phenocopies in more than 90% of the flies that subsequently emerge. The effects of these treatments on protein synthesis in two tissues (thoracic epithelium and brain) were followed for several hours after the heat treatments. Results from pulse-labeling and protein separations on sodium dodecylsulfate (SDS) acrylamide gels showed a virtually complete cessation of protein synthesis immediately after the shock, followed by a noncoordinate resumption of the starting pattern. Similar experiments following double heat shocks demonstrated a more rapid resumption of synthesis of heat shock proteins after two successive heat treatments than after a single one.
    Additional Material: 5 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 1 (1979), S. 123-132 
    ISSN: 0192-253X
    Keywords: nonrandom X-inactivation ; maternal X chromosome expression ; mouse ; extraembryonic membrane ; X chromosome ; PGK-1 ; chorionic ectoderm ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: An electrophoretic variant of the X-linked enzyme phosphoglycerate kinase (PGK-1) has been used to study regulation of X chromosome expression in the diploid derivatives of the trophectoderm at 8-8.5 days post coitum in the mouse. These derivatives included the chorionic ectoderm and the polar trophoblast. The biochemical analysis suggests that only the maternally derived X chromosome (Xm) is expressed in the diploid trophectoderm derivatives. Cell selection and maternal tissue contamination were ruled out as possible causes of the observed Xm expression. From these and other results, we conclude that all derivatives of the trophectoderm, along with the primitive endoderm, express only Xm, whereas derivatives of the primitive ectoderm show random X chromosome expression.
    Additional Material: 5 Ill.
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  • 6
    ISSN: 0192-253X
    Keywords: Dictyostelium discoideum ; alkaline phosphatase mutant ; linkage analysis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Alkaline phosphatase is one of several enzymes that accumulate in a temporally regulated sequence during the development of Dictyostelium discoideum. These enzymes can be used to monitor specific gene expression; moreover, isolation and analysis of mutations in the structural gene(s) can serve to indicate some of the essential steps in programmed synthesis and morphogenesis. A mutation (alpA) which affects the activity and substrate affinity of alkaline phosphatase was isolated in D discoideum using a procedure for screening large numbers of clones. Alkaline phosphatase activity at all stages of vegetative growth and development was altered by the mutation. Several physical properties of the enzyme from growing cells and developed cells were compared and found to be indistinguishable. It is likely that a single enzyme is responsible for the majority of alkaline phosphatase activity in growth and development. The mutation is coexpressed in diploids heterozygous for alpA and maps to linkage group III. One of the haploid segregants isolated from these diploids carries convenient markers on each of the six defined linkage groups and can be used for linkage analysis of other genetic loci.
    Additional Material: 3 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 1 (1979), S. 167-179 
    ISSN: 0192-253X
    Keywords: agouti locus ; hair pigment patterns ; melanocyte metabolism ; tissue microenvironment ; eumelanin ; phaeomelanin ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This study was conducted to assess microenvironmental variability within integumental tissue of genetically identical mice with respect to a specific cellular response: cyclic synthesis of yellow and black pigment by hair bulb melanocytes. Crosses were performed within and between inbred strains of mice that were isogenic with the exception of a single gene substitution at the agouti locus. Agouti locus genes included the Avy, Aw, A, atd, at, ax, am, and a alleles. The pigment patterns of dorsal, flank, and ventral hairs of the first and third hair generations and of hairs growing in special integumentary areas such as the pinna, tail, and hind foot were studied. It was found that the amount of yellow pigment synthesized by hair bulb melanocytes within genetically identical mice is both agedependent and conditioned by the integumentary environment. Furthermore, the special integumentary regions produce hairs with a variety of pigment patterns in which the distribution and relative amounts of black and yellow pigments do not necessarily conform to dominance relationships expected among agouti locus alleles as judged by their effects on the pigmentation of the dorsal pelage. We conclude that within genetically uniform integumental tissues, microenvironmental differences occur and are reflected as alterations in the metabolic pattern of differentiated cells.
    Additional Material: 1 Ill.
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  • 8
    ISSN: 0192-253X
    Keywords: sea urchin embryo ; hnRNA ; mRNA ; 5′ terminal cap ; turnover ; synthesis rate ; methylation ; developmental changes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The relationship between heterogeneous nuclear RNA (hnRNA) and messenger RNA (mRNA) synthesis has been studied as a function of the development of the sea urchin embryo through the use of methyl incorporation. Several parameters in the metabolism of capped hnRNA and mRNA of early blastula and late gastrula stages have been investigated by measuring the kinetics of transfer of methyl groups from S-adenosylmethionine to the 5′ cap structures in nuclear and cytoplasmic RNA: 1The rate constants for the decay of hnRNA caps and the synthesis of mRNA caps are equal to within experimental error. This equality indicates a flux of precursor hnRNA caps to mRNA caps with a very high degree of conservation of the hnRNA caps. This conservation holds for each embryonic stage.2From literature data on the labeling kinetics of GTP and mRNA, we have calculated the decay constant of a putative mRNA precursor component of hnRNA. The value of this constant is very close to that for the decay constant of hnRNA caps. Hence, all hnRNA caps and some portion of their associated hnRNA sequences behave kinetically as the pre-mRNA fraction. This kinetically ascribed pre-mRNA comprises approximately 30% of the hnRNA mass.3The part of the hnRNA which does not serve as precursor to mRNA turns over at least twice as rapidly as the pre-mRNA fraction.4During development from early blastula to late gastrula, the rate of hnRNA cap synthesis drops from 2 × 103 molecules/min/cell to half of this value. This decline is parallel to the decline in total hnRNA synthesis and thereby confirms the constant degree of capping of hnRNA, as previously reported. We infer that the pre-mRNA fraction of hnRNA remains nearly constant during this developmental period.
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 1 (1979), S. 195-204 
    ISSN: 0192-253X
    Keywords: apterous mutant ; Drosophila melanogaster ; juvenile hormone ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The apterous (ap) mutant in Drosophila melanogaster exhibits phenotypes of wing deficiency, precocious adult death, and nonvitellogenic oocyte development. The latter phenotype previously has been shown to result from juvenile hormone (JH) deficiency in the adult stage. To explore the relationship between the hormone deficiency and the other phenotypes, the expression of each phenotype was measured in five alleles of ap (including a new, chemically-induced allele, ap77f) as wing length, survival five days after eclosion, and initiation and progress of vitellogenic oocyte development. No correlation could be found between severity of wing phenotype and that of precocious adult death or nonvitellogenesis. However, the latter phenotypes were correlated in both ap homozygotes and allelic heterozygotes, since adults that survive have wild-type vitellogenesis, and those fated for precocious death fail to develop vitellogenic oocytes. These results indicate that no relationship exists between wing and JH deficiencies, but that precocious adult death is related to hormone deficiency  -  probably through pleiotropy, rather than through causality.
    Additional Material: 4 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 1 (1979), S. 205-218 
    ISSN: 0192-253X
    Keywords: Tetrahymena thermophila ; genomic exclusion ; micronucleus ; macronucieus ; nucleocytoplasmic interactions ; developmental cytogenetics ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Genomic exclusion is an aberrant form of conjugation of Tetrahymena thermophila in which the genome of a defective conjugant is excluded from the genotype of the exconjugant progeny. This paper is concerned with the cytogenetic and nucleocytoplasmic events of genomic exclusion in senescent clones A*III and C*. In crosses between A*III or C* and strain B, functional, haploid gametic nuclei are formed only in the strain B cell. In some instances one of the gametic nuclei divides prior to transfer of the migratory gametic nucleus, and both products then undergo DNA synthesis. Two alternative cytogenetic pathways are followed after transfer of the migratory nucleus. In the first, the conjugants separate without further micronuclear divisions. This pathway was most common in A*III genomic exclusion. In exconjugants the former gametic nuclei undergo both DNA synthesis and (presumably) intranuclear separation of centromeres to restore micronuclear diploidy. The old macronucleus of each exconjugant is retained without autolysis. This class of exconjugant survives and contributes genes to future sexual progeny. In the second cytogenetic pathway the gametic nuclei divide and macronuclear anlagen are formed, as in normal conjugation. This pathway was more common in C* genomic exclusion. The initial DNA content of the anlagen ranges from haploid to diploid. Following two to three rounds of DNA synthesis, further macronuclear development ceases and the anlagen appear to undergo autolysis. The old macronucleus condenses and also undergoes autolysis, as in normal conjugation. Except for rare C* exconjugants, in which macronuclear development is completed, anlagen-bearing genomic exclusion exconjugants die. Death may be caused by aneuploidy, errors in the timing or receptivity to signals for autolysis, or the inability of anlagen-bearing exconjugants to feed. Anlagenbearing conjugants are frequently abnormal with respect to the number of anlagen and micronuclei. Most of the anomalies can be explained by postulating errors in the timing of both developmental signals and nuclear divisions. Rare conjugants in which gametic nuclei divide but do not give rise to macronuclear anlagen are also observed. In these instances, the old macronuclei condense and undergo autolysis. Destruction of the old macronucleus therefore is independent of the presence of macronuclear anlagen and requires cell pairing in order to be initiated.
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