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  • 1
    Electronic Resource
    Electronic Resource
    Plant tubulin genes: Structure and differential expression during development (1987)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 8 (1987), S. 435-460 
    Details
    ISSN: 0192-253X
    Keywords: tubulin genes ; microtubules ; Arabidopsis thaliana ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Microtubules are important components of the cytoskeleton of plant cells and play key roles in plant growth and morphogenesis. Recent molecular studies have begun to elucidate the structure and expression of plant genes coding for the major components of microtubules, α- and β-tubulin. Tubulin amino acid sequences deduced from the DNA sequences of eight higher plant tubulin genes are 79-87% homologous with constitutively expressed mammalian tubulins. The genome of the model plant system Arabidopsis thaliana contains four dispersed α-tubulin sequences and at least seven β-tubulin sequences, only two of which appear to be linked. Of the five A. thaliana genes whose expression has been analyzed, the transcripts of one α-tubulin and one β-tubulin gene are constitutively expressed in roots, leaves, and flowers. A second α-tubulin gene is expressed predominately in flowers; the transcripts of the second and third β-tubulin genes are found predominately in leaves or in roots, respectively.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020080511
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  • 2
    Electronic Resource
    Electronic Resource
    Neurochemical characterization of embryonic brain development in trisomy 19 (Ts19) mice: Implications of selective deficits observed for abnormal neural development in aneuploidy (1987)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 8 (1987), S. 267-279 
    Details
    ISSN: 0192-253X
    Keywords: mental retardation ; Down syndrome ; cholinergic neurons ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In this study, we examined the neurochemical profiles of selected brain regions (cerebral hemispheres, diencephalon/brainstem) in fetal (day 14 to 18 gestation) trisomy 19 (Ts19) mice. The neurochemical characteristics we observed in Ts19 mice were quite different from those we observed previously in Ts16 mice. Choline acetyltransferase (ChAT) activity was reduced significantly in the cerebral hemispheres, but not in the brainstem/diencephalon, of the fetal Ts19 mouse brain, suggesting a selective vulnerability of telencephalic cholinergic neurons. Additionally, the activity of glutamic acid decarboxylase (GAD) was reduced significantly in both hemispheres and diencephalon/brainstem of late gestation Ts19 fetuses, suggesting a selective vulnerability of GABAergic neurons as well. While the levels of catecholaminergic and dopaminergic markers were reduced significantly at late gestational ages, the relative rate of turnover of dopamine (DA), measured by the ratio of DOPAC/DA, was elevated significantly in Ts19 mice. Neither reduction in the thickness of various cellular zones of the cerebral cortex nor reduced cell density of the cerebral cortex accounts for the alterations in neurochemical parameters observed in Ts19 mice. These results suggest that the effects of the triplication of specific genes on the respective chromosomes, rather than a generalized disruption of developmental homeostasis resulting from extra chromosomal material, may produce selective alterations in neurochemical and neuroanatomical markers observed in these two mouse trisomies.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020080409
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  • 3
    Electronic Resource
    Electronic Resource
    Tumor formation and morphogenesis on different Nicotiana sp and hybrids induced by Agrobacterium tumefaciens T-DNA mutants (1987)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 8 (1987), S. 61-71 
    Details
    ISSN: 0192-253X
    Keywords: Agrobacterium insertion mutants ; hormone equilibria ; differentiation ; dedifferentiation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A series of experiments are presented that have been performed to observe the interactions between Agrobacterium tumefaciens strains mutated in the T-DNA genes involved in indoleacetic acid and cytokinin biosynthesis and several Nicotiana species and hybrids. Infections were induced on leaf cuttings of Nicotiana debneyi, N. knightiana, N. clevelandii, N. bigelovii var bigelovii, N. bigelovii var quadrivalvis, N. glauca, N. langsdorffii, the amphidiploid tumorous hybrid N. glauca × N. langsdorffii, and a nontumorous mutant of it. The effect of deletions of the Ti plasmid varied according to plant genotype. Insertion mutants in iaaM and iaaH suppressed tumor formation in N. langsdorffii, reduced it in N. bigeloviivar quadrivalvis, had no effect in N. glauca and the two amphidiploid hybrids, and promoted tumorigenesis when compared to the wild-type Agrobacterium strain B6S3 in N. bigelovii N. debneyi, and N. knightiana. The same mutations induced shoot formation in N. glauca, increased it in N. debneyi, and suppressed root formation in N. knightiana. On the other hand, an insertion mutation of the isopentenyl transferase gene (ipt-) had no effect in N. bigelovii var quadrivalvis, N. debneyi, the tumorous hybrid, suppressed tumor formation in N. langsdorffii, and inhibited it in N. glauca, the nontumorous hybrid, N. bigelovii var bigelovii, and N. knightiana. Insertion in ipt suppressed shoot formation in the nontumorous hybrid and inhibited it in the nontumorous amphidiploid and N. debneyi, while promoting root formation in N. glauca and N. debneyi.The suggestion of the existence of specific hormone equilibria necessary for the shift to each morphogenetic pattern was supported by experiments with exogenous hormone treatments of three genotypes (N. glauca, N. langsdorffii, and the nontumorous N. glauca × N. langsdorffii).
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020080202
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  • 4
    Electronic Resource
    Electronic Resource
    Coh A, a mutation affecting the post aggregative related (par) cohesive system of Dictyostelium discoideum (1985)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 6 (1985), S. 59-74 
    Details
    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.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020060105
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  • 5
    Electronic Resource
    Electronic Resource
    Developmental genetics of the soybean urease isozymes (1987)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 8 (1987), S. 375-387 
    Details
    ISSN: 0192-253X
    Keywords: urease ; isozymes ; clones ; null mutants ; soybean ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The soybean (Glycine max [L.] Merr.) contains two urease isozymes whose expression is regulated in a tissue-specific and temporal manner. The ubiquitous urease is expressed in all tissues examined (leaf, embryo, seed coat, cell culture); the embryo-specific urease is synthesized exclusively in the developing embryo. The embryo-specific urease accumulates during seed development while the ubiquitous urease is found in highest levels during early development of both leaves and seeds. We have isolated mutants which fall in three phenotypic classes lacking one or both urease isozyme activities. Genetic analysis has thus far identified three unlinked loci which control the expression of urease(s). Genomic and cDNA clones of urease structural genes have also been recovered and we are working to assign these to genetic loci by sequence and RFLP analyses. That the ubiquitous urease isozyme is expressed in cell culture makes it possible to include cell culture in physiological and developmental studies. Additionally, we have developed direct selections for urease-negative mutants, and their revertants, in cell culture. These selections will facilitate the study of the expression of cloned urease genes in genetically transformed tissue.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020080508
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  • 6
    Electronic Resource
    Electronic Resource
    Multiplicity of functions for the otu gene products during Drosophila oogenesis (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 91-120 
    Details
    ISSN: 0192-253X
    Keywords: actin filament bundles ; ethyl methane sulfonate ; female sterile mutants ; in terallelic complementation ; oocyte determination ; ovarian tumor genes ; phenocritical thresholds ; polyfusomes ; polytene nurse cell chromosomes ; polytrophic meroistic ovaries ; pseudonurse cells ; Q-T-P-O values ; rhodaminyl phalloidin ; temperature-sensitive mutants ; transformed oocytes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The ovarian tumor gene behaves as if it encodes a product (OGP), which is required durirng several early steps in the transformation of oogonia into functional oocytes. Seventeen ethyl methane sulfonate-induced mutations have been studied, and their mutant phenotypes can be explained as graded responses by individual germ cells to different levels of OGP synthesized by the mutant germ cells themselves. The lowest and highest levels of OGP appear to be produced by otu10 and otu14, respectively. The 15 mutants with intermediate OGP levels are temperature sensitive; subnormal temperatures improve ovarian development, while above-normal temperatures suppress it. A subgroup ofthese mutants are unable to form a system of actin microfilament bundles in the cortical cytoplasm of their nurse cells during stage 10B, and these defective nurse cells are unable to transport their cytoplasm to the oocyte, as normally happens between stages 10B and 12. In addition to its role in the actin-mediated transport of nurse cell cytoplasm, OGP also appears to alter the morphology of giant polytene chromosomes, which form as the nurse cells undergo endocycles of DNA replication. Genetic evidence suggests that otu also encodes a second product (SP) that is utilized late in oogenesis. SP is required for the synthesis in the ooplasm of glycogen-rich, beta yolk spheres. Products of the otu gene also play a vital but unknown role in embryogenesis.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020090203
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  • 7
    Electronic Resource
    Electronic Resource
    Murine “housekeeping” enzyme (genetic locus:Idh-1) is regulated in an allele-specific manner (1987)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 8 (1987), S. 135-150 
    Details
    ISSN: 0192-253X
    Keywords: mouse ; NADP-isocitrate dehydrogenase ; electrophoresis ; gene regulation ; allele-specific expression ; heart ; kidney ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The murine “housekeeping” enzyme, cytosolic NADP-isocitrate dehydrogenase (E.C. 1.1.1.42) (genetic locus:Idh-1), exhibited a complex pattern of allele-specific expression. Protein electrophoresis on cellulose-acetate gels and determination of relative enzymatic activity by means of densitometry revealed that in heart tissue (but not liver tissue) of certain hybrid crosses the AA-homodimer was underrepresented relative to total enzymatic activity, and the degree of underrepresentation changed during development. In mixtures of homozygous tissue extracts of heart tissue (but not liver tissue) the AA-homodimer was underrepresented relative to the BB-homodimer. Relative activity of allelic isozymes varied as a function of tissue (heart versus liver), age, and the parental source of the Idh-1a allele, but did not vary as a function of sex.Allele-specific expression was also exhibited in kidney tissue of the same animals. In adult male kidney tissue extracts from heterozygotes, the AA-hornodimer was underrepresented relative to total enzymatic activity; in adult female kidney tissue extracts from heterozygotes, a more codominant phenotype was observed. Tissue extracts from immature hybrid animals exhibited a phenotype midway between the adult male and adult female phenotypes. Tissue extracts from castrated males exhibited a phenotype equivalent to that seen in females. Relative activity of allelic isozymes in kidney varied as a function of age and sex, but did not vary as a function of the parental source of the Idh-1a allele.While cytosolic NADP-IDH is a “housekeeping” enzyme, expressed in multiple tissues of the mouse, differences in the relative intensities of allelic isozyme bands provide evidence for tissue- and stage-specific regulatory variation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020080303
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  • 8
    Electronic Resource
    Electronic Resource
    A Ca2+-dependent signal transduction system participates in coupling expression of some cAMP-dependent prespore genes to the cell surface receptor (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 359-369 
    Details
    ISSN: 0192-253X
    Keywords: cAMP ; Ca2+ ; signal transduction ; cell surface receptor ; gene expression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Elevated levels of cAMP are essential for the expression of many postaggregation prespore and prestalk mRNA species and for the suppression of some growth phase mRNAs. Here we review evidence that this regulation is mediated by cAMP interacting at the cell surface receptor. These effects of cAMP on gene expression can occur under conditions where the receptor-associated adenylate cyclase is inactivated and in concentrations that are consistent with receptor binding. A number of differences are noted in the mechanism by which cAMP regulates prespore and prestalk genes. Finally, evidence is reviewed for the role of a Ca2+-dependent signal transduction system in coupling the expression of some of the prespore mRNAs to the cAMP receptor. This signal transduction system does not appear to be involved in the expression of the cAMP-dependent prestalk gene.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020090417
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  • 9
    Electronic Resource
    Electronic Resource
    The role of polyfusomes in generating branched chains of cystocytes during Drosophila oogenesis (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 70-86 
    Details
    ISSN: 0192-253X
    Keywords: Arrested cleavage ; Centrosome ; contractile ring ; Fusome ; Germarium ; Models of dividing cells ; Oocyte/nurse cell syncytium ; Ovarian tumor mutation ; POlytrohic meroistic ovary ; Ring canal ; Spindle elongation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Three-dimensional models were constructed utilizing the information gained from electron micrographs of serial sections of two clones of cystocytes undergoing their terminal divisions. In each clone a polyfusome connected all eight cystocytes together. Each of the spindles was oriented so that one pole touched the polyfusomes, while the other pointed away from it. This positioning of spindles ensures that one cell of each dividing pair retains all previously formed canals, while the other receives none. The two cells that eventually come to contain the maximum number of canals and fusomal material are the ones that differentiate as pro-oocytes, while the others become nurse cells. The orientation of each spindle suggests that the polyfusome formed at one division determines the placement of the cytoskeletal fibers that anchor the spindles formed at the next division. There is a centripetal gathering together of new canals following each cycle of cystocyte division, which is thought to result from the subsequent contraction of the polyfusomal system. Females homozygous for the otu1 mutation are characterized by ovarian tumors, which result when germarial cystocytes undergo supernumerary divisions and fail to differentiate into either nurse cells or oocytes. An analysis of electron micrographs taken of serially sectioned, mutant germaria showed that most germ cells were single or belonged to clusters of two or three interconnected cells. Therefore otu1 cystocytes are unable to undergo a sustained series of arrested cleavages. These cystocytes contain fusomal material that shows ultrastructural differences from normal polyfusomes. We conclude: (1) that a normal polyfusomal system is a necessary prerequisite for the production of a branched chain of cystocytes and for their subsequent differentiation into pro-oocytes and nurse cells; and (2) that a product encoded by the otu+ gene is essential for the construction of a functional polyfusome.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020100203
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  • 10
    Electronic Resource
    Electronic Resource
    Hyperinsulinemia in transgenic mice carrying multiple copies of the human insulin gene (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 356-364 
    Details
    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.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020100503
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