bluuebunny/crossref_metadata_2025_split huggingface dataset:
Induction of the shift in melanin synthesis in lethal yellow (Ay/a) mice in vitro
Authors: Tamate Hidetoshi B. , Takeuchi Takuji 
Published: May 2005

AbstractAlleles 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.
Triploidy permits survival of an inviable amphibian hybrid
Authors: Elinson Richard P. , Briedis Andris 
Published: May 2005

AbstractHybrids between species frequently arrest early in development. In the frog hybrid Rana catesbeiana female × Rana clamitans male, the embryo shows a characteristic development to an exogastrula which dies. This hybrid can be rescued by pressure suppression of the second polar body, which results in the addition of another haploid set of R catesbeiana chromosomes to the embryo. The triploid hybrid expresses genes from both species and can develop normally through metamorphosis. The results show that an R catesbeiana egg containing a full haploid set of R clamitans chromosomes is capable of development and that the usual developmental arrest caused by the R clamitans genome responds to chromosomal dosage.
Intracellular cAMP in Dictyostelium discoideum: Characterization of an aggregation‐deficient mutant with elevated cAMP pools
Authors: Chan Fred K. , Coukell M. Barrie 
Published: May 2005

AbstractForty aggregation‐deficient mutants of Dictyostelium discoideum were screened for changes in intracellular cAMP during the first 10 hr of starvation. The pools in 39 of the mutants remained low and relatively static during this period. However, amoebae of one mutant, strain HC151, exhibited significantly elevated levels of intracellular cAMP during vegetative growth and for several hours after starvation. A more detailed analysis of this mutant indicated that the elevated cAMP pools in these cells are a consequence of the premature appearance and partial activation of an adenylate cyclase. The mutation(s) altering adenylate cyclase regulation in this strain appears to map in linkage group IV. Complementation tests between strain HC151 and another mutant, HH201, which has recently been shown to produce an adenylate cyclase activity precociously [1], indicated that the mutations affecting adenylate cyclase activity in these strains map at different loci. Although both of these mutations behave recessively in heterozygous diploids with respect to gross development, an examination of early cAMP metabolism and terminal spore differentiation in these diploids suggest that these mutations are at least partially expressed during some stage(s) of the developmental cycle.
Unlinked structural genes for the developmentally regulated isozymes of sn‐glycerol‐3‐phosphate dehydrogenase in mice
Authors: Kozak Leslie P. , Burkart Donna L. , Hjorth J. Peter 
Published: May 2005

AbstractGenetic variants that affect the heat stability and ionic charge of the adult isozyme of glycerol‐3‐phosphate dehydrogenase (EC 1.1.1.8) map to a gene, Gdc‐1, located on chromosome 15. A second isozyme of glycerol‐3‐phosphate dehydrogenase, structurally homologous to the product of the Gdc‐1 locus and expressed predominantly in undifferentiated tissues, has previously been identified. We have now discovered an electrophoretic variant of this embryonic isozyme. This expression is determined by a codominant allele of the gene, Gdc‐2, that maps to the distal end of chromosome 9 as inferred from the observed gene order Mpi‐1–d‐Mod‐1–Gdc‐2.
Expression of genetically distinct superoxide dismutases in the maize seedling during development
Authors: Baum James A. , Scandalios John G. 
Published: May 2005

AbstractImmunoassays for the cytosolic and mitochondrial superoxide dismutases (SOD) of maize were developed and used to study the expression of these proteins in the maize seedling. The genetically distinct proteins, SOD‐3 and SOD‐4, are preferentially expressed in the scutellum, comprising approximately 1% of the total water‐soluble protein of that tissue. SOD‐2, SOD‐3, and SOD‐4 are synthesized in the scutellum during early sporophytic development, probably on cytosolic ribosomes. Two‐dimensional gel electrophoresis of crude scutellar extracts indicates that significant changes occur in the protein composition of the maize scutellum following seed imbibition. Using the immunoassays, a maize line exhibiting a significant reduction in cyanide‐sensitive SOD protein was identified.
Developmental abnormalities in Drosophila induced by heat shock
Authors: Mitchell Herschel K. , Petersen Nancy S. 
Published: May 2005

AbstractWe have for some years been making use of phenocopies in Drosophila, as induced by heat shock, as tools for studies of the molecular events in morphogenesis [18, 21, 22]. In this paper, we have brought together some accumulated information on the conditions for phenocopy production, on a temporal sequence of sensitivity to induction, and on the nature of many of the morphogenetic abnormalities that can be induced. In general, the induction of phenocopies by heat shock requires conditions drastic enough to turn off transcriptional activities but not extreme enough to prevent recovery. This situation is most easily achieved in pupal stages where heat resistance is high, but even in this range, resistance varies with the stage of development.The phenocopies described resemble, for the most part, mutants that affect structures derived from epithelial differentiation or muscle development.
Polygenic analysis of pattern formation in Drosophila: Specification of campaniform sensilla positions on the wing
Authors: Thompson James N. , Hellack Jenna J. , Kennedy John S. 
Published: May 2005

AbstractThis study was designed to measure the degree of correlation between vein formation and the specification of campaniform sensillae positions in the wing of Drosophila melanogaster. The campaniform sensillae are sensory organs placed at various locations on the wing. Those on the third longitudinal vein (L3) were the focus of this analysis. The system of polygenic modifiers of vein length is comparatively simple, as shown in whole chromosome assays of selected lines. This variability provides a sensitive method of altering vein‐forming ability and of assessing correlated changes in other parts of the vein pattern. In selection lines of veinlet, sensillae were displaced toward the base of the wing as vein length decreased by distal loss of vein material. Changes in the amount of vein were, however, not directly proportional to changes in sensillae positions. The more distal sensillae were shifted the largest amount. In the mutant tilt, in which reduced L3 vein‐forming competence results in subterminal gaps, distal campaniform sensillae were almost completely eliminated. The remaining sensillae were shifted toward the base of the wing where vein formation is normal. The placement of sensillae therefore appears to be sensitive to the same underlying determinants involved in vein‐forming competence.
Neural development in an imaginal disc mutant of Drosophila melanogaster
Authors: White Kalpana 
Published: May 2005

AbstractThe 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.
Partial deficiencies in the myelin proteins of developing mice heterozygous for the shiverer mutation
Authors: Cammer Wendy 
Published: May 2005

AbstractThe central nervous system of the shiverer mouse is known to be severely deficient in myelin. Animals heterozygous for this autosomal‐recessive mutation were crossed, and the myelin proteins were examined in the brains and spinal cords of shiverers and unaffected littermates among the offspring. In the brains and spinal cords of nine of the 14 unaffected littermates examined, the quantities of the myelin basic and proteolipid proteins were lower than normal. Furthermore, in the brains of heterozygotes 33 to ∼ 150 days old, the myelin basic and proteolipid proteins were reduced in amount, compared to wild‐type controls; the myelin basic protein was also present in subnormal amounts in the spinal cords from heterozygous animals at the ages of 17 to 150 days. More severe reductions in the quantities of the myelin proteins were observed in central nervous system tissue from homozygous shiverer mice, and the quantity of the myelin proteolipid protein in the central nervous system of the shiverer mouse, expressed as a ratio to the control value at each age, underwent a developmental decline. In heterozygotes, as well as shiverers, the peripheral nerves were also deficient in the P1 and Pr proteins, which are the same as the basic proteins in rodent central nervous system myelin. The findings regarding heterozygotes suggest that the defective primary gene product in the shiverer mouse could be the myelin basic protein itself or a protein required for a rate‐limiting step in the processing of the myelin basic protein.
The late‐replicating X chromosome in digynous mouse triploid embryos
Authors: Endo Sumiyo , Takagi Nobuo , Sasaki Motomichi 
Published: May 2005

AbstractUsing BrdU‐labeling and acridine orange staining, the behavior of X‐chromosome replication was studied in 28 XXX and 19 XXY digynous mouse triploids. In some of these the paternal and maternal X chromosome could by cytologically distinguished. Such embryos were obtained by mating chromosomally normal females with males carrying Cattanach's X chromosome which contains an autosomal insertion that substantially increases the length of this chromosome. In the XXX triploids there were two distinct cell lines, one with two late‐replicating X chromosomes, and the other with only one late‐replicating X. The XXY triploids were also composed of two cell populations, one with a single late‐replicating X and the other with no late replicating X chromosome. Assuming that the late‐replicating X is genetically inactive, in both XXX and XXY triploids, cells from the embryonic region tended to have only one active X chromosome, whereas those from the extra‐embryonic membranes tended to have two active X chromosomes. The single active X chromosome was either paternal or maternal in origin, but two active X chromosomes were overwhelmingly maternal in origin, suggesting paternal X‐inactivation in extra‐embryonic tissues.
Mutant alleles that are altered in quantitative, organ‐specific behavior
Authors: Freeling Michael , Cheng David S.‐K. , Alleman Mary 
Published: May 2005

AbstractThree new mutant alleles of maize alcohol dehydrogenase‐1 (Adh 1) were recovered following allyl alcohol selection of pollen. Each is altered in quantitative, organ‐specific, regulatory properties. All mutant sites act in cis to the structural gene component. One mutant arose spontaneously, one followed indirectly from irradiation with high Z accelerated particles, and one was induced by an autonomous mutator system. Each mutant is assessed in three organs by utilizing ADH allozyme ratios that were quantified at the level of ADH enzyme activity and either [3H]‐Leu incorporation into newly synthesized ADH 1 subunits or direct protein determinations. One mutation simultaneously raises Adh 1 expression in one organ and lowers it in another, another affects expression in one organ only, and another is extremely underexpressed in all organs but is unstable. This unstable allele has generated derivative mutant alleles that have less or zero ADH expression. We do not yet know whether or not coding sequences are involved in these mutants. We conclude that information for organ specificity and quantitative behavior resides near or within Adh 1 coding sequences.
Murine adult hematopoietic cells produce adult erythrocytes in fetal recipients
Authors: Blanchet Jean Paul , Fleischman Roger A. , Mintz Beatrice 
Published: May 2005

AbstractBone marrow cells from normal adult mice were introduced by microinjection via the placenta into W/Wv genetically anemic fetuses of 11 days' gestation. After birth, erythrocytes were fractionated by fluorescence‐activated cell sorting on the basis of antibody binding to a fetal‐specific antigen (Ft). Lysates of Ft‐positive, i.e., fetal, erythrocytes did not detectably contain hemoglobin of the donor type, as judged from electrophoresis of strain‐specific hemoglobin variants. Thus, adult hematopoietic bone marrow cells did not resume fetal differentiation despite their post‐transplant maturation in a fetal environment.
Temporal control of urate oxidase activity during development of the third‐instar larva of Drosophila: The role of 20‐hydroxyecdysone
Authors: Kral Leos G. , Johnson Daniel H. , Wing Mark , Friedman Thomas B. 
Published: May 2005

AbstractThe tissue‐specific enzyme urate oxidase is confined exclusively to the Malpighian tubules of Drosophila melanogaster and expressed only in the third‐instar larva and the adult. Shortly before pupariation urate oxidase activity declines precipitously and is not detectable 24 hours later. That 20‐hydroxyecdysone is the factor that triggers the disappearance of urate oxidase activity in late third‐instar larvae is demonstrated using the temperature sensitive mutant ecd1 which at the nonpermissive temperature of 29°C fails to accumulate a sufficient concentration of 20‐hydroxyecdysone necessary for puparium formation and thus remains a third‐instar larva for 1 to 2 weeks before death. Both the life cycle and the temporal profile of urate oxidase activity in ecd1 larvae at 19°C is identical to that of the wild type. However, at 29°C ecd1 third‐instar larvae retain high urate oxidase activity. A precipitous decline in urate oxidase activity is observed when ecd1 larvae at 29°C are fed 20‐hydroxyecdysone. These data implicate 20‐hydroxyecdysone in the process that controls the rapid decline of urate oxidase activity at the time of puparium formation. In whole homogenates of Malpighian tubules, the urate oxidase polypeptide was identified in SDS‐polyacrylamide gels by its Rf with respect to homogeneously pure Drosophila urate oxidase and also by immunoprecipitation with rabbit anti‐Drosophila urate oxidase IgG. Throughout development the amount of the urate oxidase polypeptide is correlated with the magnitude of urate oxidase activity.
XY female mice express H‐Y antigen
Authors: Johnson Lawrence L. , Sargent Evelyn L. , Washburn Linda L. , Eicher Eva M. 
Published: May 2005

AbstractKaryotypically XY individuals of the C57BL/6J‐YPOS mouse stock develop as females or hermaphrodites, but never as normal males. The aberrant sexual development results from the interaction of the C57BL/6J genetic background with the M. poschiavinus‐derived Y chromosome. XY females from this stock were assayed for H‐Y antigen. By the criteria of skin‐grafting, the cell‐mediated lympholysis test, and the popliteal lymph node assay, these XY females are antigenically indistinguishable from normal C57BL/6 males. Implications for the hypothesis that H‐Y antigen induces formation of the mammalian testis are discussed.
Drosophila salivary gland proteins and pupation
Authors: Sarmiento Loveriza A. , Mitchell Herschel K. 
Published: May 2005

AbstractPulse‐labeling experiments of salivary glands from the prepupal stages of development showed selectively high rates of synthesis of a set of low molecular weight proteins (6K–12K). These proteins are stably maintained in the salivary glands during prepupal development and are subsequently transported to the pupation fluid (found between the pupal case and the prepupal cuticle) when pupation occurs. These small polypeptides are very basic with the major components having isoelectric points of 8.6–8.7 and the minor components having isoelectric points of 9.1–9.5. This study shows the continuing function of the salivary glands—specifically, the synthesis and secretion of a set of proteins with a putative role in pupation.
The relationship between gene dosage, gene expression, and sex in Drosophila
Authors: Lucchesi John C. 
Published: May 2005

AbstractIn 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.
Adaptation of Drosophila to temperature: Heat‐shock proteins and survival in Drosophila melanogaster
Authors: Stephanou G. , Alahiotis S. N. , Christodoulou C. , Marmaras V. J. 
Published: May 2005

AbstractTwo stocks of Drosophila melanogaster, one sensitive (6.5% survival) and one resistant (76.24%) to heat shock (40°C/25 min) were derived through indirect selection [1]. Genetic analysis of heat‐sensitive and heat‐resistant lines we had selected revealed that the survival rate is chiefly determined by cytoplasmic inheritance but also depends to some extent on the nucleus [1]. The ability of the fly to survive thermal stress was found to have an excellent correlation with the kinetics of protein synthesis in ovaries or glands subjected to heat treatment. The incorporation rate of 35S‐methionine into proteins was found to be higher for strains exhibiting higher survival (R1, R1S1) than for strains with a lesser ability (S1, S1 R1) to survive heat shock. Moreover, the intensity of labeling of the proteins synthesized and especially of the hsps (heat‐shock proteins) after the heat shock is higher in the R1 and R1S1 stocks than in the S1 and S1R1 stocks. This convergence between survival and the cellular level of hsps (both manipulated by selection) bears on the physiological significance of these proteins which seems to participate in the control of the survival as an additive component.
Developmental genetic analysis of lethal alleles at the ewg locus and their effects on muscle development in Drosophila melanogaster
Authors: Fleming Robert J. , Zusman Susan B. , White Kalpana 
Published: May 2005

AbstractThe recessive X‐linked mutation erect wing (ewg), in Drosophila melanogaster, was characterized as a flightless behavioral mutant which specifically lacked the dorsal longitudinal flight muscles [1]. This mutation was mapped distal to the X chromosomal locus yellow, and further to the cytological segment 1 A 1 to 1 B2‐3 [2]. Several lethal complementation groups have been mapped to this interval [3]. Our complementation tests show that ewg is allelic to one lethal complementation group in the region 1 A 1 to 1 B2‐3. A further analysis of ewg and several lethal alleles isolated at this locus was undertaken in the present investigation. Most of the lethal alleles at this locus lead to a late embryonic or early larval lethal phase, indicating that the ewg+ gene product is necessary for the development of more than just the dorsal longitudinal flight muscles. Intragenic complementation was observed for some of the ewg lethal alleles. Genetic mosaics with ewg lethal alleles showed that mutant cell clones in cuticular structures are viable. Mosaic analysis is consistent with a mesodermal defect associated with the locus.
Lethal nonagouti (ax): Description of a second embryonic lethal at the agouti locus
Authors: Papaioannou Virginia E. , Mardon Helen 
Published: May 2005

AbstractThe 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.
The control of IgM expression in a murine B cell lymphoma
Authors: Irick Holly A. , Sibley Carol H. 
Published: May 2005

AbstractThe 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.
Genetic analysis of cell adhesion
Authors: Loomis William F. 
Published: May 2005

AbstractCellular 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.