bluuebunny/crossref_metadata_2025_split huggingface dataset:
More mog genes that influence the switch from spermatogenesis to oogenesis in the hermaphrodite germ line of Caenorhabditis elegans
Authors: Graham Patricia L. , Schedl Tim , Kimble Judith 
Published: May 2005

AbstractThe Caenorhobditis elegans XX animal possesses a hermaphrodite germ line, producing first sperm, then oocytes. In this paper, we report the genetic identification of five genes, mog‐2, mog‐3, mog‐4, mog‐5, and mog‐6, that influence the hermaphrodite switch from sper‐matogenesis to oogenesis. In mcg‐2‐mog‐6 mutants, spermatogenesis continues past the time at which hermaphrodites normally switch into oogenesis and no oocytes are observed. Therefore, in these mutants, germ cells are transformed from a female fate (oocyte) to a male fate (sperm). The fem‐3 gene is one of five genes that acts at the end of the germline sex determination pathway to direct spermatogenesis. Analyses of mog;fem‐3 double mutants suggest that the mog‐2‐mog‐6 genes act before fem‐3; thus these genes may be in a position to negatively regulate fem‐3 or one of the other terminal regulators of germline sex determination. Double mutants of fem‐3 and any one of the mog mutations make oocytes. Using these double mutants, we show that oocytes from any mog;fem‐3 double mutant are defective in their ability to support embryogenesis. This maternal effect lethality indicates that each of the mog genes is required for embryogenesis. The two defects in mog‐2‐mog‐6 mutants are similar to those of mog‐1: all six mog genes eliminate the sperm/oocyte switch in hermaphrodites and cause maternal effect lethality. We propose that the mog‐2‐mog‐6 mutations identify genes that act with mog‐1 to effect the sperm/oocyte switch. We further speculate that the mog‐1‐mog‐6 mutations all interfere with translational controls of fem‐3 and other maternal mRNAs. © 1993 Wiley‐Liss, Inc.
Sequence analysis of translationally controlled maternal mRNAs from Urechis caupo
Authors: Rosenthal Eric 
Published: May 2005

AbstractFertilization of Urechis coupo oocytes stimulates dramatic changes in the pattern of protein synthesis. This shift is brought about entirely through selective translation of the large pool of maternal mRNAs synthesized and stored during oogenesis. My laboratory has identified cDNA clones to more than 20 different Urechis maternal mRNAs. These have been used to determine whether the complementary mRNAs are translated in oocytes or embryos, and to analyze the polyad‐enylation status of the mRNAs at different stages. For 14 of the mRNAs, multiple, overlapping cDNA clones were isolated, and the complete sequence of the mRNA molecule was determined. Of these 14 mRNAs, half are from the subset that is translated in growing and full‐grown oocytes, but not in embryos. These 7 mRNAs have poly(A) tails before fertilization. The other 7 are from the subset that is not translated at any time before fertilization, and has very short poly(A) tails in oocytes. After fertilization these mRNAs are recruited onto polysomes and extensively polyadenylated. The sequence data from the two classes of maternal mRNAs was compared in an attempt to identify consensus sequences that could regulate translation directly, or indirectly, by controlling polyadenylation or secondary structure formation. Two features of the sequences correlate very well with the translation and polyadenylation of the different mRNAs‐the identity of the base immediately preceding the AUG start codon, and the presence of the sequences UUUUA and UUUUUA in the 3′ untranslated region. © 1993 Wiley‐Liss, Inc.
Antisense attenuation of Wnt‐1 and Wnt‐3a expression in whole embryo culture reveals roles for these genes in craniofacial, spinal cord, and cardiac morphogenesis
Authors: Augustine Karen , Liu Edison T. , Sadler T. W. 
Published: May 2005

AbstractWnt‐1 and Wnt‐3a proto‐on‐cogenes have been implicated in the development of midbrain and hindbrain structures. Evidence for such a role has been derived from in situ hybridization studies showing Wnt‐1 and ‐3a expression in developing cranial and spinal cord regions and from studies of mutant mice whose Wnt‐1 genes have undergone targeted disruption by homologous recombination. Wnt‐1 null mutants exhibit cranial defects but no spinal cord abnormalities, despite expression of the gene in these regions. The absence of spinal cord abnormalities is thought to be due to a functional compensation of the Wnt‐1 deficiency by related genes, a problem that has complicated the analysis of null mutants of other developmental genes as well. Herein, we describe the attenuation of Wnt‐1 expression using antisense oligonucleotide inhibition in mouse embryos grown in culture. We induce similar mid‐ and hindbrain abnormalities as those seen in the Wnt‐1 null mutant mice. Attentuation of Wnt‐1 expression was also associated with cardiomegaly resulting in hemostasis. These findings are consistent with the possibility that a subset of Wnt‐1 expressing cells include neural crest cells known to contribute to septation of the truncus arteriosus and to formation of the visceral arches. Antisense knockout of Wnt‐3a, a gene structurely related to Wnt‐1, targeted the forebrain and midbrain region, which were hy‐poplastic and failed to expand, and the spinal cord, which exhibited lateral outpocketings at the level of the forelimb buds. Dual antisense knockouts of Wnt‐1 and Wnt‐3a targeted all brain regions leading to incomplete closure of the cranial neural folds, and an increase in the number and severity of outpocketings along the spinal cord, suggesting that these genes complement one another to produce normal patterning of the spinal cord. The short time required to assess the mutant phenotype (2 days) and the need for limited sequence information of the target gene (20‐25 nu‐cleotides) make this antisense oligonucleotide/ whole embryo culture system ideal for testing the importance of specific genes and their interactions in murine embryonic development. © 1993 Wiley‐Liss, Inc.
Embryonic expression of the single Tribolium engrailed homolog
Authors: Brown Susan J. , Patel Nipam H. , Denell Robin E. 
Published: May 2005

AbstractWe have cloned and sequenced the single Tribolium homolog of the Drosophila engrailed gene. The predicted protein contains a homeobox and several domains conserved among all engrailed genes identified to date. In addition it contains several features specific to the invected homologs of Bombyx and Drosophila, indicating that these features most likely were present in the ancestral gene in the common ancestor of holometabolous insects. We used the cross‐reacting monoclonal antibody, 4D9, to follow the expression of the Engrailed protein during segmentation in Tribolium embryos. As in other insects, Engrailed accumulates in the nuclei of cells along the posterior margin of each segment. The first Engrailed stripe appears as the embryonic rudiment condenses. Then as the rudiment elongates into a germ band, Engrailed stripes appear in an anterior to posterior progression, just prior to morphological evidence of the formation of each segment. As in Drosophila (a long germ insect), expression of engrailed in Tribolium (classified as a short germ insect) is preceeded by the expression of several homologous segmentation genes, suggesting that similar genetic regulatory mechanisms are shared by diverse developmental types. © 1994 Wiley‐Liss, Inc.
Correlated evolution of the cis‐acting regulatory elements and developmental expression of the Drosophila Gld gene in seven species from the subgroup melanogaster
Authors: Ross Jennifer L. , Fong Peter P. , Cavener Douglas R. 
Published: May 2005

AbstractThe tissue‐specific expression patterns of glucose dehydrogenase (GLD) exhibit a high degree of inter specific variation in the adult reproductive tract among the species in the genus Drosophila. We chose to focus on the evolution of GLD expression and the evolution of the Gld promoter in seven closely related species in the mela‐nogaster subgroup as a means of elucidating the relationship of changes in cis‐acting regulatory elements in the Gld promoter region with changes in tissue‐specific expression. Although little variation in tissue‐specific patterns of GLD was found in nonreproductive tissues during development, a surprisingly high level of variation was observed in the expression of GLD in both developing and ma‐ture reproductive organs. In some cases this variation is correlated with changes in sequence elements in the Gld promoter which were previously shown to direct tissue‐specific expression in the reproductive tract. In particular D. teissieri adult males do not express GLD in their ejaculatory ducts, atypical of the melanogaster subgroup species. The Gld promoter region of D. teissieri specifically lacks all three of the TTAGA regulatory elements present in D. melanogaster. The TTAGA elements were previously shown to direct reporter gene expression to the ejaculatory duct. Together these data suggest the absence or presence of the TTAGA elements may be responsible for variation in the absence or presence of GLD in the ejaculatory duct among species. © 1994 Wiley‐Liss, Inc.
Quantitative genetics of butterfly wing color patterns
Authors: Paulsen Susan M. 
Published: May 2005

AbstractDevelopmental processes exert their influence on the evolution of complex morphologies through the genetic correlations they engender between traits. Butterfly wing color patterns provide a model system to examine this connection between development and evolution. In butterflies, the nymphalid groundplan is a framework used to decompose complex wing patterns into their component pattern elements. The first goal of this work has been to determine whether the components of the nymphalid groundplan are the products of independent developmental processes. To test this hypothesis, the genetic correlation matrices for two species of butterflies, Precis coenia and Precis evarete, were estimated for 27 wing pattern characters. The second purpose was to test the hypothesis that the differentiation of serial homologs lowers their genetic correlations. The “eyespots” found serially repeated across the fore‐ and hindwing and on the dorsal and ventral wing surfaces provided an opportunity to test this hypothesis. The genetic correlation matrices of both species were very similar. The pattern of genetic correlation measured between the different types of pattern elements and between the homologous repeats of a pattern element supported the first hypothesis of developmental independence among the elements of the groundplan. The correlation pattern among the differentiated serial homologs was similarly found to support the second hypothesis: pairs of eyespots that had differentiated had lower genetic correlations than pairs that were similar in morphology. The implications of this study are twofold: First, the apparent developmental independence among the distinct elements of wing pattern has facilitated the vast diversification in morphology found in butterflies. Second, the lower genetic correlations betweendifferentiated homologs demonstrates that developmental constraints can in fact be broken. The extent to which genetic correlations readily change, however, remains unknown. © 1994 Wiley‐Liss, Inc.
Developmental quantitative genetic models of evolutionary change
Authors: Atchley William R. , Xu Shizhong , Vogl Claus 
Published: May 2005

AbstractDiscussions about evolutionary change in developmental processes or morphological structures are predicated on specific quantitative genetic models whose parameters predict whether evolutionary change can occur, its relative rate and direction, and if correlated change will occur in other related and unrelated structures. The appropriate genetic model should reflect the relevant genetical and developmental biology of the organisms, yet be simple enough in its parameters so that deductions can be made and hypotheses tested. As a consequence, the choice of the most appropriate genetic model for polygenically controlled traits is a complex tissue and the eventual choice of model is often a compromise between completeness of the model and computational expediency. Herein, we discuss several developmental quantitative genetic models for the evolution of development and morphology. The models range from the classical direct effects model to complex epigenetic models. Further, we demonstrate the algebraic equivalency of the Cowley and Atchley epigenetic model and Wagner's developmental mapping model. Finally, we propose a new multivariate model for continuous growth trajectories. The relative efficacy of these various models for understanding evolutionary change in developmental and morphological traits is discussed. © 1994 Wiley‐Liss, Inc.
Diverse programs of ascus development in pseudohomothallic species of Neurospora, Gelasinospora, and Podospora
Authors: Raju Namboori B. , Perkins David D. 
Published: May 2005

AbstractMeiosis and ascospore development in the four‐spored pseudohomothallic ascomycetes Neurospora tetrasperma, Gelasinospora tetrasperma, Podospora anserina, and P. fefraspora have been reexamined, highlighting differences that reflect independent origins of the four‐spored condition in the different genera. In these species, as in the heterothallic eight‐spored N. crassa, fusion of haploid nuclei is followed directly by meiosis and a postmeiotic mitosis. These divisions take place within a single unpartitioned giant cell, the ascus, which attains a length of >0.1 mm before nuclei are enclosed by ascospore walls. Two basically different modes underlie the delivery of opposite mating type nuclei into each of the four ascospores in the different genera. In N. tefrasperma on the one hand, the mating type locus is closely centromere‐linked. Mating types therefore segregate at the first meiotic division. The second division spindles of N. tefrasperma overlap and are usually parallel to one another, in contrast to the their tandem arrangement in N. crassa. As a result, nonsister nuclei of opposite mating type are placed close together in each half‐ascus and a pair is enclosed in each ascospore. In the Podospora and Gelasinospora species on the other hand, the second‐division spindles are in tandem, with sister nuclei of opposite mating type associated as a pair in each half‐ascus. It is established for P. anserina and inferred for P. fetraspora and G. fefrasperma that a single reciprocal crossing over almost always occurs in the mating type‐centromere interval, ensuring that mating types segregate at the second meiotic division and that nuclei of opposite mating type are enclosed in each ascospore.Other differences are also seen that are less fundamental. Neurospora tetrasperma differs from the other species in the orientation of chromosomes and spindle pole body plaques at interphase (I.) Third‐division spindles are oriented parallel to the ascus wall in Gelasinospora but across the ascus in Podospora and Neurospora. The two Podospora species differ from one another in nuclear behavior following mitosis in the young ascospores. In P. tefraspora, two of the four nuclei migrate into the tail cell, which degenerates, leaving one functional nucleus of each mating type. In P. anserina, by contrast, only one of the four nuclei moves into the tail cell, leaving the germinating ascospore with two functional nuclei of one mating type and one of the other.The pseudohomothallic condition with its heterokaryotic vegetative phase has significant consequences for both the individual organism and the breeding system. Genetic controls of development and recombination are complex. Inbreeding is not obligatory. © 1994 WiIey‐Liss, Inc.
Ontogeny of gene expression in Pomoxis (pisces: Centrarchidae)
Authors: Epifanio John M. , Philipp David P. 
Published: May 2005

AbstractThe regulation of gene expression during embryogenesis was investigated in white and black crappie (Pomoxis spp.) and their reciprocal interspecific F1 hybrids. The schedule of morphological development and the timing of isozyme expression were compared among the two species and both reciprocal maternal half‐sibling F1 hybrids. Although absolute rates of morphological development differed in response to incubation temperature, relative rates of morphological development (normalized to the onset of retinal pigment deposition) were similar among all crosses. Furthermore, these relative rates were similar to those previously documented for other centrarchid species. To assess differences in ontogenetic patterns of gene expression among the crosses, we examined expression for 39 enzymeencoding loci. Expression was not detected in the embryos for 16 loci due to low or nonexistent activity. Enzymatic activity from eight other loci were continuously detected throughout embryogenesis as a result of maternal enzyme in the egg. However, 15 loci initiated expression during the early development period investigated (fertilization through yolk sac absorption). We observed temporal variability in expression of these 15 loci among the crosses, either in the form of differential expression between parental species or as disturbances in the ontogeny of expression in interspecific hybrids. Such variability in expression suggests that some of the gene regulating mechanisms have diverged since Pomoxis species shared a common ancestral genome. © 1994 Wiley‐Liss, Inc.
Zfy is transcribed in the normal mouse epididymis and in the XXSxr (“sex reversed”) testis
Authors: Mastrangelo Peter , Zwingman Theresa , Erickson Robert P. , Blecher Stan R. 
Published: May 2005

AbstractThe presence of the mutation Sex reversed (Sxr), a copy of a Y‐chromosomal segment that gets transferred to an X chromosome, causes the resulting XXSxr mice to develop as apparent males. However, several features of male sexual development are abnormal in these animals. The testes are small and aspermatogenic, and the epididymides lack the initial segment. Testes and epididymides show abnormalities of extracellular matrix. In this study we examined transcription of the conserved Y chromosomal gene Zfy, which has an X‐chromosomal homologue (Zfx). Northern blotting showed Zfy to be expressed in the testes of XXSxr animals, except for those that carry the coat‐marker gene Tabby (Ta), despite the lack of germ cells in XXSxr mice. Reverse transcription polymerase chain reaction (RT‐PCR) studies detected Zfy in mRNA in testes even when Ta was present. RT‐PCR also demonstrated Zfy transcription in epididymides of normal males, though not in XXSxr mice. Previous authors reported an absence of Zfy transcription in XXSxr testes; Zfy transcription in normal testes has been ascribed to germ cells. Our observation indicates that this idea requires re‐evaluation. The occurrence of Zfy transcription in the normal epididymis is similarly a novel finding that may help explain those aspects of epididymal development that occur in the absence of androgen. © 1994 Wiley‐Liss, Inc.
Developmentally regulated expression of fibroblast growth factor receptor genes and splice variants by murine embryonic stem and embryonal carcinoma cells
Authors: McDonald Fiona J. , Heath John K. 
Published: May 2005

AbstractThe expression of the four fibroblast growth factor receptor (FGF‐R) genes was examined in murine embryonic stem (ES) cells, embryonal carcinoma (EC) cells, and their differentiated derivatives. FGF‐R1 and FGF‐R4 were found to be expressed constitutively in all samples examined. The expression of FGF‐R2 and FGF‐R3 was, however found to increase significantly upon differentiation of both ES and EC cells. Examination of splice variants of the third immunoglobulin domain (Iglll) of the extracellular region of the FGF‐R2 revealed that whilst Iglllc transcripts were expressed upon ES cell differentiation, Iglllb transcripts (which confer specificity for the ligand FGF‐7) were expressed in both ES cells and their differentiated progeny. FGF‐R3 transcripts were also expressed in ES cells, but variont FGF‐R3 transcripts containing the Iglllb region were expressed upon differentiation. The findings suggest that the repertoire of FGF‐R expression in embryonic cell types is developmentally regulated at the level of both gene expression, and alternative splicing and different members of the FGF‐R family can exhibit distinct patterns of both gene and splice variant expression. © 1994 Wiley‐Liss, Inc.
Interactions between tassel seed genes and other sex determining genes in maize
Authors: Irish Erin E. , Langdale Jane A. , Nelson Timothy M. 
Published: May 2005

AbstractThe tassel seed mutations of maize cause sex reversal of the florets of the tassel, such that the normally staminate florets develop pistils. Although these mutations have been recognized for many years, little is known about how they act. We have tested the hypothesis that the tassel seed genes interact directly with each other and with other genes controlling sex determination in a single genetic pathway by the construction and analysis of double mutants. On the basis of the phenotypes of the double mutants, the tassel seed mutations were placed into two groups: ts1, ts2, Ts5 and ts4, Ts6. Both groups of tassel seed mutations were additive with the masculinizing mutation dwarf, indicating independent modes of action. Interactions of tassel seed mutations with silkless varied, allowing the ordering of the action of the various tassel seed mutations relative to silkless. Both groups of tassel seed mutations were epistatic with regard to sex expression to mutations that alter both architecture of the plant and distribution of male and female florets, Teopod 1, terminal ear, and teosinte branched. Thus, there are at least two separate genetic pathways that control the sex of florets in maize tassels. In addition, analysis of double mutants revealec that all tassel seed genes tested play a role in the regulation of flower morphogenesis as well as pistil suppression. © 1994 Wiley‐Liss, Inc.
Cell cycle mutation in Paramecium tetraurelia discriminates between sexual and vegetative functions
Authors: Adl Sina M. , Berger James D. 
Published: May 2005

AbstractThe temperature‐sensitive mutation cc1 blocks a number of cell cycle processes in Paramecium including macronuclear DNA synthesis, oral morphogenesis, and the later stages of micronuclear mitosis. Oral morphogenesis and micronuclear mitosis also occur in the sexual pathway. This study shows that cc1 cells can proceed through conjugation or autogamy under restrictive conditions; neither stomatogenesis nor micronuclear mitosis is blocked. Fertilization and macronuclear determination occur normally, but DNA synthesis in macronuclear anlagen is blocked. Therefore, this mutation discriminates between oral replacement during meiosis and vegetative prefission stomatogenesis, and between mitotic spindle elongation during the pregamic and postzygotic divisions and spindle elongation during the vegetative cell cycle. These results point to a fundamental regulatory difference between morphogenesis in the vegetative and sexual pathways. © 1994 Wiley‐Liss, Inc.
Action of the Tunicate locus on maize floral development
Authors: Langdale Jane A. , Irish Erin E. , Nelson Timothy M. 
Published: May 2005

AbstractThe co‐dominant Tunicate (Tu) mutation in maize causes nonreproductive structures in both the male and female inflorescences to be enlarged. This mutation also affects sex determination, permitting the development of pistils in the normally staminate tassel. In order to characterize the role of the normal tu gene product, we have analysed genetic interaction between Tu and other mutations that perturb specific stages of floral development. Synergistic interactions observed suggested that the tu product functions in at least three stages of floral development–determination of spikelet primordia, differentiation of non‐reproductive organs and pistil abortion in the tassel. © 1994 Wiley‐Liss, Inc.