bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetics of microcystless mutants of polysphondylium pallidum
Authors: Francis David , Rupar Mark 
Published: May 2005

AbstractMutants 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.
Behavioral mutants of Drosophila melanogaster. IV. Analysis of developmentally temperature‐sensitive mutations affecting flight
Authors: Homyk Theodore , Grigliatti Thomas A. 
Published: May 2005

AbstractMutations 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.
Gene expression during early kernel development in Zea mays
Authors: Chandlee Joel M. , Scandalios John G. 
Published: May 2005

AbstractThe 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.
Food deprivation is not a prerequisite for the amoebal to plasmodial transition in Physarum polycephalum
Authors: Pallotta Dominick , Blanchard Serge , Larue Hélène 
Published: May 2005

AbstractThe 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.
Evidence for a Mendelian factor controlling the cytokinin requirement of cultured tobacco cells
Authors: Meins Frederick , Foster Rachel , Lutz Joseph D. 
Published: May 2005

AbstractCultured 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.
Production and properties of mouse trisomy 15 ⟷ diploid chimeras
Authors: Epstein Charles J. , Smith Sandra , Cox David R. 
Published: May 2005

AbstractMouse 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.
A dedifferentiation‐defective mutant of Dictyostelium that retains the capacity to aggregate in the absence of chemotaxis
Authors: Soll David R. , Mitchell Lee H. , Hedberg Christopher , Varnum Barbara 
Published: May 2005

AbstractDuring 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.
The Notch locus of Drosophila melanogaster: A molecular analysis
Authors: Artavanis‐Tsakonas Spyros , Grimwade Brian G. , Harrison Richard G. , Markopoulou Katerina , Muskavitch Marc A. T. , Schlesinger‐Bryant Ruth , Wharton Kristi , Yedvobnick Barry 
Published: May 2005

AbstractGenetic analysis has suggested that neurogenesis in D melanogaster is under the control of a small number of genes. We have initiated a molecular study of the genes involved in this developmental event and started our analysis with the Notch locus, which is one of the best characterized loci in D melanogaster in terms of its genetic structure and developmental effects. In this paper we report on the molecular characterization of the Notch locus.We describe the molecular cloning of Notch and present evidence that the entire locus is defined by approximately 40 kb of genomic DNA. The transcriptional activity of these sequences during development has been examined and the results indicate that an approximately 10.5‐kb‐long poly A+ RNA is essential for wild type Notch activity. Mapping of this RNA within the physical map of Notch indicates that it is the processed product of an approximately 40‐kb primary transcription unit spanning the entire Notch locus. More detailed analysis of the 10.5 kb RNA localizes several exons and identifies a small repetitive sequence that seems to be present in the mature Notch transcript. Structural details of a selected number of Notch locus mutations are presented and discussed. Preliminary data on the molecular structure of Notch‐homologous DNA sequences in closely related species are also presented.
The regulation and function of small heat‐shock protein synthesis
Authors: Berger Edward M. 
Published: May 2005

AbstractThe 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.
Expression of the developmentally regulated catalase (cat) genes in maize
Authors: Scandalios J. G. , Tsaftaris A. S. , Chandlee J. M. , Skadsen R. W. 
Published: May 2005

AbstractThe catalase (H2O2:H2O2 oxidoreductase; E.C.1.11.1.6; CAT) gene‐enzyme system in Zea mays L (maize) represents an ideal model for studying the molecular basis of developmental gene regulation in higher eukaryotes. This system comprises a family of structural genes that are highly regulated, both temporally and spatially, during maize development.In maize, there are four distinct forms (isozymes) of catalase that are readily discernible by convetional separation procedures. Three of the catalases have been studied in detail from a genetic and biochemical viewpoint. The catalases CAT‐1, CAT‐2, and CAT‐3 are encoded by the distinct, unlinked genes Cat1, Cat2, and Cat3, respectively. Each of the structural genes is highly regulated both spatially and temporally in its expression. Cat1 is expressed primarily in the endosperm, aleurone, pericarp, and scutellum of developing kernels, and in the root, shoot, and scutellum of very young seedlings. Cat2 is expressed primarily in the scutellum and leaf during postgerminative sporophytic development. Cat3 is expressed, for the most part, in the shoot and pericarp of young seedlings.A number of regulatory variants have been recovered that affect the developmental program of expression of the catalases. Analysis of one variant allowed for the identification of a temporal regulatory gene (Car1) that specifically alters the developmental program of the Cat2 structural gene by acting to regulate the rate of CAT‐2 protein synthesis. Cat1 has been mapped on chromosome 1S, 37 map units (m.u.) from the Cat2 structural gene. Another variant line has been isolated which lacks expression of the Cat2 gene in its tissues at all stages of development. Isolated polysomes from this line (A16) were translated in vitro, and the products were immunoprecipitated with CAT‐2‐specific antibodies. No CAT‐2 was detectable in the A16 labeled immunoprecipitates, whereas CAT‐2 was readily detected in the normal line, W64A, under similar conditions.The temporal and spatial expression of the Cat structural genes is not only influenced by genetic factors (as above), but is also responsive to exogenously applied environmental signals: light, hormones, and temperature. The mechanisms by which such signals specifically affect CAT‐2 expression will be discussed.
A Molecular approach to chromosome organization
Authors: Spierer Pierre 
Published: May 2005

AbstractA 315 kb walk in the genetically well characterized rosy region of the Drosophila chromosomes permits a molecular analysis of chromosome organization. Polytene chromosome bands in this region range from less than 7 kb to about 160 kb and the level of DNA replication is constant within bands and among bands and interbands. A good numerical and topographical correspondence is found between chromomeric units and genetic units.
Minimal selection requirements for the correlation between heterozygosity and growth, and for the deficiency of heterozygotes, in oyster population
Authors: Zouros E. , Foltz D. W. 
Published: May 2005

AbstractWe 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.
Natural selection for the control of alcohol dehydrogenase activity in populations of Drosophila melanogaster
Authors: Birley A. J. 
Published: May 2005

AbstractThe 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.
Spatial variation of biochemical and ecological phenotypes in Drosophila: Electrophoretic and quantitative variation
Authors: Hoffmann A. A. , Nielsen K. M. , Parsons P. A. 
Published: May 2005

AbstractElectrophoretic 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.
Gene expression during gonadal differentiation in the rat: A two‐dimensional gel electrophoresis investigation
Authors: Müller Ulrich , Schindler Hubert , Schempp Werner , Schott Klaus , Neuhoff Volker 
Published: May 2005

AbstractGonadal 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.
Karyonidal inheritance of mating types in tetrahymena malaccensis
Authors: Simon Ellen M. , Nanney David L. 
Published: May 2005

AbstractMating 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.
Allelic differences in initial expression of paternal alleles at an isocitrate dehydrogenase locus in rainbow trout (Salmo gairdneri)
Authors: Danzmann Roy G. , Ferguson Moira M. , Allendorf Fred W. 
Published: May 2005

AbstractWe examined a temporal series of embryos from 14 full‐sib families of rainbow trout with starch gel electrophoresis to determine the time of initial detection of enzyme produced by ldh‐3. Maternal enzyme was detected in unfertilized eggs, whereas paternal alleles showed evidence of initial expression after gastrulation and epiboly. Two alleles, 40 and 71, were expressed synchronously several days before the 114 allele. Measurement of enzyme activity by spectrophotometric analysis and serial dilution supported these observations. The degree of delay of expression of the 114 allele between families was coupled with other estimates of developmental rate. These data suggest the existence of allelic variation at a cis‐acting genetic element controlling the pattern of ontogenetic expression of structural alleles at Idh‐3.