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  • 1
    Electronic Resource
    Electronic Resource
    Biochemical genetics of hybrid sunfish: Differential survival of heterozygotes (1974)
    Springer
    Biochemical genetics 11 (1974), S. 205-219 
    Details
    ISSN: 1573-4927
    Keywords: heterosis ; heterozygosity ; hybrids ; isozymes ; sunfish ; Centrarchidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Allelic segregation in reciprocal backcrosses involving the largemouth bass (Micropterus salmoides) and the F1 hybrid (largemouth bass × smallmouth bass, M. dolomieui) was investigated to determine the extent of euheterosis and luxuriance. The frequencies of allelic isozymes encoded in the lactate dehydrogenase E, malate dehydrogenase B, and isocitrate dehydrogenase loci were determined for reciprocal backcross progeny subjected to different selection pressures. The progeny of the backcross (male F1 × female largemouth bass) underwent a rapid loss of heterozygous individuals in a natural pond environment. When the offspring of this same mating were placed in artificial pools, where cannibalism is the main source of mortality, heterozygosity was advantageous. There was a marked correlation of increased heterozygosity at these enzyme loci with an increased growth rate. None of the above responses to selection was observed when the F1 hybrid served as the maternal parent in the reciprocal backcross. A maternal factor in the egg cytoplasm may influence the expression of heterosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00486056
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  • 2
    Electronic Resource
    Electronic Resource
    Esterase polymorphism in the corn earworm, Heliothis zea (Boddie): A survey of temporal and spatial allelic variation in natural populations (1975)
    Springer
    Biochemical genetics 13 (1975), S. 885-898 
    Details
    ISSN: 1573-4927
    Keywords: Heliothis zea ; esterases ; isozymes ; allelic variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Allelic variation at the Est-II locus was investigated in 22 natural populations of Heliothis zea from maize, separated spatially and temporally. Of the four alleles observed, Est-II b was the predominant one in every population. The relative frequency of Est-II b ranged from 0.57 to 0.85, with a mean of 0.72±0.06, and proved to be remarkably stable in space and time. Temporal changes in Est-II allele frequencies were observed at two of the sampling localities; however, principal component analysis and multiple correlation of genetic and environmental components have provided persuasive evidence that abiotic environmental or geographic variation is not related to differences in Est-II allele frequencies. Possible factors responsible for the maintenance of this polymorphism are discussed and include possible effects of the chemical composition of host plants and pesticides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00484418
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  • 3
    Electronic Resource
    Electronic Resource
    Genetic and molecular analysis of nonrandom dimer assembly of the creatine kinase isozymes of fishes (1978)
    Springer
    Biochemical genetics 16 (1978), S. 811-829 
    Details
    ISSN: 1573-4927
    Keywords: isozymes ; creatine kinase ; fishes ; dimer ; restricted assembly
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Species within many families of actinopterygian bony fishes (class Osteichthyes) have a two-banded allelic isozyme phenotype in individuals heterozygous at the creatine kinase A locus. This two-banded pattern is formed by the presence of the two homodimeric isozymes and the absence of the expected heterodimer. Sharks and amphibians have retained the ability to form all three allelic isozymes in individuals which are heterozygous. Reversible denaturation procedures were able to assemble the different allelic CK-A subunits within a species to form CK-A2 heterodimers. Furthermore, heterodimers were formed from different CK-A subunits from highly divergent species after this in vitro molecular hybridization process. It is concluded from these studies that the polypeptidebinding sites of creatine kinase are structurally conservative in most fishes and that the absence of a heterodimer in heterozygous individuals is not due to a structural incompatibility between the different A subunit types or to an instability of the heterodimer during electrophoresis. A temporal and/or spatial isolation of allelic CK-A subunit synthesis and assembly, within differentiated skeletal muscle, appears to have evolved in the actinopterygian bony fishes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00484738
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  • 4
    Electronic Resource
    Electronic Resource
    Increasing tubC β-tubulin synthesis by placing it under the control of a benA β-Tubulin upstream sequence causes a reduction in benA β-tubulin level but has no effect on microtubule function (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 16 (1990), S. 214-220 
    Details
    ISSN: 0886-1544
    Keywords: Aspergillus ; benomyl ; chimeric gene ; tubulin mutants ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have constructed a chimeric β-tubulin gene that places the structural gene for the tubC β-tubulin of Axpergillus nidulans under the control of the benA β-tubulin promoter. Introduction of cither this chimeric gene or a second wild-type ben.A gene into a benomyl-resistant benA22 strain causes it to become benomyl sensitive, indicating that the introduced genes are functional. Analysis of the tubulin proteins synthesized in benA22 strains into which a second wild-type benA β-tubulin gene was transformed showed that the total amount of β-tubulin protein was the same as in the parental strain with a single benA gene. Thus the level of β-tubulin must be regulated. This was also true of transformants carrying an extra copy of the chimeric β-tubulin gene. The total amount of β-tubulin was the same as in the parental strain. Two-dimensional gel analysis showed that the endoge-nous benA22 and the introduced chimeric tubC gene contributed equally to the total β-tubulin pool. Th; fact that one-half of the benA β-tubulin could be replaced by tubC β-tubulin with no effect on the growth of the cells suggests that the benA and tubC β-tubulins are functionally interchangeable.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970160308
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  • 5
    Electronic Resource
    Electronic Resource
    A guanine nucleotide-binding regulatory protein in human sperm mediates acrosomal exocytosis induced by the human zona pellucida (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 31 (1992), S. 78-86 
    Details
    ISSN: 1040-452X
    Keywords: G protein ; Pertussis toxin ; ADP-ribosylation ; Human sperm ; Acrosome reaction ; Zona pellucida ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Guanine nucleotide-binding regulatory proteins play key intermediary roles in regulating zona pellucida-mediated acrosomal exocytosis in mouse and bull sperm. Since human sperm possess a Gi-like protein and undergo the acrosome reaction in response to the human zona pellucida, we investigated whether this G protein plays a regulatory role in this exocytotic process. Zonae pellucidae isolated from eggs that had been inseminated but had shown no signs of fertilization after retrieval for in vitro fertilization and embryo transfer were pooled into groups of ≥50 in order to reduce variability in biological responses due to the possible presence of ZP that had undergone modifications associated with the polyspermy block. Acid-solubilized zonae pellucidae were incubated with capacitated sperm, and the sperm then assessed for the acrosome reaction using both the P. sativum agglutinin and chlortetracycline fluorescence assays; both assays gave similar results. Sperm incubated with solubilized zonae pellucidae at a final concentration of 2, 4, or 6 ZP/μl underwent acrosomal exocytosis to a similar extent as compared with A-23187. Sperm were incubated with 1 μg/ml pertussis toxin during capacitation to functionally inactivate the Gi-like protein. Pertussis toxin treatment of sperm did not affect sperm motility and the ability of the cells to bind to structurally intact zonae pellucidae. Pertussis toxin, however, completely inhibited the percentage acrosome reactions induced by solubilized zonae pellucidae. By contrast, the A-23187-induced acrosome reaction was insensitive to PT treatment. Pertussis toxin inhibition of the zona pellucida-induced acrosome reaction occurred in a concentration-dependent manner with maximal effects observed at 100 ng/ml PT. These data suggest that the pertussis toxin-sensitive Gi-like protein in human sperm plays an important regulatory role in the acrosome reaction induced by the human zona pellucida.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080310114
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  • 6
    Electronic Resource
    Electronic Resource
    Activation of a G protein in mouse sperm by the zona pellucida, an egg-associated extracellular matrix (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 31 (1992), S. 297-306 
    Details
    ISSN: 1040-452X
    Keywords: Acrosome reaction ; Signal transduction ; Pertussis toxin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mammalian sperm possess a guanine nucleotide-binding regulatory protein (G protein), with properties similar to Gi, that appears to be involved in the signal transduction pathway required for zona pellucida (ZP)-mediated acrosomal exocytosis. Mouse sperm treated with pertussis toxin (PT), a toxin that functionally inactivates Gi proteins, bind to the ZP of mouse eggs but are inhibited from undergoing acrosomal exocytosis. We have measured high-affinity GTPase activity and GTPγ[35S] binding in mouse sperm homogenates incubated in the absence and presence of ZP glycoproteins isolated from either ovulated eggs or from ovarian homogenates to determine whether this extracellular matrix can activate the sperm-associated Gi protein. An increase in GTP hydrolysis (∼50% over basal activity) and GTPγ[35S] binding (∼25-60% over basal activity) is observed when sperm homogenates are incubated in the presence of solubilized ZP glycoproteins, and the increase in GTPase activity is dependent on the concentration of ZP added to the homogenates. Accompanying this increase is a reduction in the ability of PT to catalyze in vitro [32P]ADP-ribosylation of a Mr = 41,000 sperm Gi protein, suggesting that the increase in GTPase activity and GTPγ[35S] binding is associated with the activation of a PT-sensitive sperm G protein(s). The ability of the ZP to stimulate high-affinity GTPase activity in these homogenates appears to be dependent on the capacitation state of the sperm from which the homogenates are prepared. These data suggest that a component(s) of the ZP may function in a manner similar to that of other ligands by binding to a sperm surface-associated receptor and subsequently activating a G protein coupled to an intracellular signal transduction cascade(s) required for induction of acrosomal exocytosis.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080310411
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  • 7
    Electronic Resource
    Electronic Resource
    Rapid, nonradioactive, and quantitative method to analyze zona pellucida modifications in single mouse eggs (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 38 (1994), S. 91-93 
    Details
    ISSN: 1040-452X
    Keywords: Zona pellucida ; Egg activation ; Mouse ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A rapid, nonradioactive method to monitor the ZP2 to ZP2f conversion in the zona pellucida of single mouse eggs has been developed. This assay is based on the chemiluminescent detection of biotinylated ZP2 and ZP2f following electrophoresis under reducing conditions and electrophoretic transfer to Immobilon P. This method is about 10 times faster and detects similar extents of ZP2 to ZP2f conversion following A23187-induced egg activation, when compared to the commonly used radioiodination procedures. © 1994 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080380115
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  • 8
    Electronic Resource
    Electronic Resource
    Identification and localization of integrin subunits in oocytes and eggs of the mouse (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 40 (1995), S. 211-220 
    Details
    ISSN: 1040-452X
    Keywords: Integrin ; Oocyte ; Egg ; Mouse ; Fertilization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Results of a recent study have implicated egg integrins in sperm binding to the egg plasma membrane (Blobel et al., 1991: Nature 356:248-252). In this report, immunoprecipitation was used to identify, and confocal immunofluorescence microscopy was used to localize, several different integrin subunits in mouse eggs. Antibodies to α2, α5, αv, and β1 subunits, as well as antibodies to the fibronectin receptor (FNR; α5β1 and/or α3β1) and vitronectin receptor (VNR; αvβ3 and/or αvβ5), detect polypeptides of the appropriate molecular weights following immunoprecipitation. β1 is localized preferentially to either the microvillar or amicrovillar membrane/cortical regions of eggs, and these asymmetric localizations depend on the antibody used. Proteins recognized by anti-FNR antibodies are localized preferentially to the amicrovillar membrane/cortical region. Germinal vesicle-intact oocytes display a symmetric plasma membrane distribution using β and FNR antibodies, and the asymmetric distribution develops as a consequence of oocyte maturation and is clearly observed by metaphase I. In contrast to the membrane localization of these integrin subunits, α2, α5, and VNR are predominantly localized in the cytoplasm of both oocytes and eggs. In the oocyte, each of these integrin subunits is uniformly distributed throughout the cytoplasm. Oocyte maturation is associated with a redistribution of α5 and VNR, leading to an asymmetric cytoplasmic distribution with an increased localization towards the spindle. αv, which is localized in the plasma membrane/cortex of both oocytes and eggs, does not show such a change during oocyte maturation. Results of these experiments are discussed in the context of a role for integrins in mediating sperm plasma membrane-egg plasma membrane interactions leading to egg activation. © 1995 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080400210
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  • 9
    Electronic Resource
    Electronic Resource
    Activation of a Gi protein in digitonin/cholate-solubilized membrane preparations of mouse sperm by the Zona pellucida, an egg-specific extracellular matrix (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 40 (1995), S. 355-363 
    Details
    ISSN: 1040-452X
    Keywords: Sperm ; Signal transduction ; G protein ; Zona pellucida ; Receptor ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mammalian sperm possess guanine nucleotide-binding regulatory proteins (G proteins) that are involved in signal transduction pathways leading to zona pellucida (ZP)-mediated acrosomal exocytosis. We have previously examined ZP-G protein dynamics in mouse sperm homogenates, as well as cell-free membrane preparations, and our data support the existence of ZP receptor-G protein complexes in sperm membranes. However, the composition of this complex has not been identified due to experimental limitations of the membrane preparations. In the present study, a detergent-solubilized preparation from mouse sperm membranes that retained the signaling properties of cell homogenates and cell-free membrane preparations was developed using buffers containing digitonin and cholate. GTPγS, a poorly hydrolyzable analogue of GTP, bound to these solubilized preparations in a specific and concentration-dependent fashion that reached saturation at 100 nM. Incubation of this solubilized membrane preparation with heat-solubilized ZP resulted in an increase in specific GTPγS binding in a concentration-dependent manner, with a maximal response at 4-6 ZP/μl. Mastoparan (50 μM) increased GTPγS binding to levels similar to that seen with solubilized ZP. Mastoparan plus ZP stimulated GTPγS binding to the same extent as mastoparan or ZP alone. Pertussis toxin completely inhibited ZP-stimulated GTPγS binding and decreased mastoparan-stimulated GTPγS binding by 50-60%. Purified ZP3, the ZP component that possesses quantitatively all of the sperm binding and acrosomal exocytosis-inducing activities of the intact ZP, stimulated GTPγS binding to an extent similar to that of solubilized ZP. The properties of this solubilized membrane preparation are similar to those found in the cell homogenates and cell-free membrane preparations, suggesting that the components involved in ZP3-mediated signal transduction are effectively solubilized and are responsive to the ZP3 ligand. © 1995 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080400312
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  • 10
    Electronic Resource
    Electronic Resource
    Phosphate uptake and control of fibroblast growth (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 92 (1977), S. 115-128 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Previous studies have shown that growth to quiescence of fibroblast-like cells is accompanied by a large decrease in the rate of phosphate uptake. Since 3T3 cells can be arrested in the G1 (or G0) phase of the cell cycle by lowering the concentration of phosphate in the medium, we examined the possibility that the decline in phosphate uptake observed during growth to quiescence might be a key event in the inhibition of DNA synthesis and cell division.The experimental approach consisted of controlling the rate of phosphate uptake by varying the phosphate concentration in the medium. Kinetic experiments showed that phosphate uptake in both growing and quiescent cells was partly accounted for by simple diffusion as well as carrier-mediated uptake. In fact, diffusion of phosphate into the growing cells was 2.5-fold greater than in the quiescent cells.When phosphate uptake was measured in 3T3 cells plated at different initial densities, we found an inverse relationship between phosphate uptake and cell density, showing that phosphate uptake was correlated with growth rate and did not decline simply as a consequence of time in culture.Measurements of phosphate demonstrated that the lowered rate of phosphate uptake by quiescent cells was not due merely to a reduction of phosphate in the medium. To check the possibility that release of a previously described transport inhibitor might account for the decline in phosphate uptake observed as cells grow to quiescence, we removed media from growing and non-growing cultures and tested its ability to support phosphate uptake. We found that the medium from growing cultures supported a higher rate of phosphate uptake than the medium from the quiescent cultures did, indicating that a transport inhibitor was being released. In addition, we found that the amount of inhibitor released was proportional to the concentration of phosphate in the medium.To directly determine if the decline in phosphate uptake was a key event in the decline in DNA synthesis as cells grew to quiescence, we switched growing cultures to a medium with low phosphate immediately after cell attachment. This lowered the rate of phosphate uptake to a level below that of quiescent cells grown in the usual concentration of phosphate. This was done for 3T3, Polyoma virus-transformed 3T3, human diploid foreskin, and secondary chick embryo cells. Measurements of DNA synthesis and cell number showed that this lowered rate of phosphate uptake had virtually no effect on cell growth, directly demonstrating that the decline in phosphate uptake observed during growth to confluency was not causing the decline in DNA synthesis. In addition, measurements of intracellular phosphate pool size showed that changes in phosphate uptake were not directly paralleled by changes in intracellular phosphate pool size, and that intracellular phosphate pool size was not regulating DNA synthesis or cell division during growth to quiescence.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040920114
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