bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distinct patterns of expression of the D‐type cycling during testicular development in the mouse
Authors: Ravnik Stuart E. , Rhee Kunsoo , Wolgemuth Debra J. 
Published: May 2005

AbstractThe three D‐type cyclins have been shown to be differentially expressed in a number of isolated cell types and cell lines, suggesting distinct roles in cell cycle regulation in particular cell lineages. The testis provides unique opportunities to study genes involved in cell cycle regulation, since it contains cells in both mitosis and meiosis as well as differentiated cells with little proliferation activity. Major transcripts of 4.2 kb, 6.8 kb, and 2.3 kb were detected in the adult mouse testis by Northern hybridization analyses for cyclin D1, cyclin D2, and cyclin D3, respectively. Additional transcripts of 1.8 and 2.7 kb were detected by Northern hybridization for cycin D3 in the testis, but not in other tissues, and these transcripts were limited to germ cells. Northern and in situ hybridization analyses of normal and germ cell‐deficient testes showed the surprising result that cyclin D1 was expressed in a pattern consistent with expression in the non‐dividing Sertoli cells. Cyclin D2 levels appeared slightly enriched in germ cell‐deficient testes as compared to intact testis, but in situ hybridization analysis did not reveal any distinct cellular localization. Also surprising was the observation that cyclin D3 expression was highest in the non‐dividing, haploid, round spermatids. The possible roles of these cyclins in the events of spermatogenesis are discussed. © 1995 Wiley‐Liss, Inc.
Genomic organization of a mouse glyceraldehyde 3‐phosphate dehydrogenase gene (Gapd‐s) expressed in post‐meiotic spermatogehic cells
Authors: Welch J. E. , Brown P. R. , O'Brien D. A. , Eddy E. M. 
Published: May 2005

AbstractThe Gapd‐s gene encodes an isoform of the glyceraldehyde 3‐phosphate dehy‐drogenase enzyme expressed only in post‐meiotic spermatogenic cells. Two clones containing the Gapd‐s gene were isolated from a mouse genomic library. Sequencing and restriction enzyme analysis demonstrated that this single‐copy gene contains 11 exons and spans 9596 base pairs. The locations of Gapd‐s exons and introns are conserved when compared to the corresponding portions of the chicken and human somatic Gapd genes. The promoter region contains no TATA box, although there is a potential SP1 recognition site within exon 1. Like other TATA‐less genes, primer extension analysis reveals some heterogeneity in the site of transcription initiation with Gapd‐s transcripts initiating from three discrete sites. Northern analysis demonstrated that a 1.5‐kb Gapd‐s mRNA is expressed in the testis in at least three mammalian orders, indicating that the Gapd‐s gene appeared early in mammalian evolution. Using GAPD‐deficient bacteria, mouse GAPD‐S was shown to be capable of functioning as a glycolytic enzyme. Since GAPD has been proposed to be a key enzyme regulating glycolysis in spermatogenic cells, GAPD‐S may represent a potential target for toxicological or contraceptive agents affecting fertility by interfering with glycolysis. © 1995 Wiley‐Liss, Inc.
The CpG‐rich promoter of human LDH‐C is differentially methylated in expressing and nonexpressing tissues
Authors: Bonny Christophe , Goldberg Erwin 
Published: May 2005

AbstractA comparison of nucleolide sequences of murine LDH‐a and Ldh‐c genes and human LDH‐A, LDH‐B, and LDH‐C reveals that mouse Ldh‐c has lost the CpG “island” present in the genes for the somatic isozymes. However, the human LDH‐C gene has a CpG‐rich region of 230 bp surrounding its promoter. Endonuclease sensitivity coupled with polymerase chain reaction (PCR) demonstrate the presence of nine heavily methylated sites in this region in different somatic cells. The same sites are specifically hypomethy‐lated in expressing tissues. 3′ sites bordering the CpG‐rich region appear to be methylated in both expressing and nonexpressing tissues. Furthermore, the methylated promoter forms a specific complex in vitro with a methyl‐DNA binding protein. Evolutionary and functional implications of these observations are discussed. © 1995 Wiley‐Liss, Inc.
Developmental regulation of the ovine β‐lactoglobulin/human serum albumin transgene is distinct from that of the β‐lactoglobulin and the endogenous β‐casein genes in the mammary gland of transgenic mice
Authors: Baruch Ariela , Shani Moshe , Hurwitz David R. , Barash Itamar 
Published: May 2005

AbstractWe compared the developmental pattern of expression of the sheep β‐lactoglobulin (BLG), the chimeric BLG/human serum albumin (HSA), and the endogenous murine β‐casein genes in the mammary gland of virgin, pregnant and lactating transgenic mice, both at the RNA (expression) and protein (synthesis and secretion) levels. The BLG and casein genes were expressed at very low levels in virgin animals and during early stages of pregnancy. The increase in the expression of these genes started at the second half of pregnancy and reached a peak between the end of pregnancy and day 10 of lactation. The accumulation of their RNA coincided with that of the corresponding proteins, indicating a transcriptional control of expression of these genes. The expression and secretion patterns of the endogenous casein gene in transgenic and nontransgenic mice were indistinguishable. The hybrid BLG/HSA gene constructs displayed distinct patterns of expression in virgin animals and at early stage of pregnancy, from that of the BLG transgene or the endogenous mouse milk protein gene. High levels of expression (17–60% of that on day 18 of pregnancy) were detected in the mammary gland of virgin animals. At day 5 of pregnancy there was a dramatic decrease in HSA synthesis and secretion in all transgenic strains tested. The down‐regulation, revealed by immunoprecipitation and immunohistochemical studies, demonstrated that at that stage of pregnancy only 10–18% of ductal structures contained HSA expressing cells in contrast to the majority of ducts expressing HSA in virgin animals. These morphological studies also demonstrated that the down‐regulation in HSA synthesis and secretion was correlated with the transition from ducts comprised of a single layer of epithelial cells (characteristic of the virgin state) to ducts composed of multilayers of such cells. In two of the three transgenic strains tested, the down‐regulation at the protein level was associated with a similar decrease in HSA transcripts. In the exceptional strain no. 23, HSA transcripts continued accumulating even at this stage. The differences in the control of expression at the RNA level between these transgenic strains were also confirmed by in situ hybridization. Our results suggest the involvement of at least two regulatory mechanisms effective at early stages of gestation in the control of expression/secretion of the HSA transgene targeted for expression in the mammary gland by the BLG milk protein promoter. These putative mechanisms may play key roles in the interplay between normal mammogenesis and lactogenesis. Thus, transgenic mice expressing BLG/HSA gene constructs at early stages of gestation would be valuable in further dissecting these mechanisms. © 1995 Wiley‐Liss, Inc.
Embryonic regulation of histone ubiquitination the sea urchin
Authors: Jasinskiene Nijole , Jasinskas Algimantas , Langmore John P. 
Published: May 2005

AbstractWe have used quantitative 2‐D protein electrophoresis and immunoprecipitation to study the patterns of histone ubiquitination at 10 h and 36 h of embryonic development in Strongylocentrotus purpuratus. Variants csH2A, αH2A, βH2A, γH2A, δHA, H2AF./Z, αH2B, βH2B, and γH2B showed up to sevenfold differences in level of monoubiquitination between variants, and individual variants showed up to sixfold changes during development. At 36 h of embryogenesis, the late variants were less ubiquitinated than the early variants, althoug h the overall level of ubiquitination was appreciably greater than at 10 h. Antiubiquitin antibodies were used to precipitate formaldehyde‐fixed chromatin fragments in order to estimate the degree of ubiquitination of the early histone genes. The 5′ regulatory region of the active H3 gene appeared to be at least twice as ubiquitinated as the adjacent upstream spacer. However, the absolute level of ubiquitination of the early histone gene repeat seemed to be independent of transcriptional activity. These results show that variant‐specific ubiquitination of histones is a part of the developmental program in sea urchin embryos, but is not clearly correlated with transcriptional activity of the early histone genes, except perhaps in the regulatory regions. © 1995 Wiley‐Liss, Inc.
Phenotypic diversity of 188 rice embryo mutants
Authors: Hong Soon‐Kwan , Aoki Toshiyuki , Kitano Hidemi , Satoh Hikaru , Nagato Yasuo 
Published: May 2005

AbstractWe have identified 188 embryo mutants of rice and characterized them into six groups based on their phenotypes: (1) embryoless in mature seed, (2) deletion of embryonic organ(s), (3) abnormal position of embryonic organs, (4) abnormal embryo size, (5) defect in organ morphology, and (6) variable abnormal phenotypes in spite of single mutations. Three types of organless mutants are obtained: small globular embryo, club‐shaped embryo, and large embryo. Although 12 shootless mutants derived from at least three loci are identified, only three radicleless mutants are recovered, which produce normal adventitious roots after germination. In reduced embryo mutants, every embryonic organ is reduced, in contrast to giant embryo mutants in which only scutellum is enlarged. Considerable number of mutants are categorized into (5) and (6) in the above. These diverse embryo mutants would serve as promising materials for genetic study of embryogenesis. © 1995 Wiley‐Liss, Inc.
Transient reduction in secreted 32 kD chitinase prevents somatic embryogenesis in the carrot (Daucus carota L.) variant ts11
Authors: de Jong Anke J. , Hendriks Theo , Meijer Ellen A. , Penning Maarten , Schiavo Fiorella L. , Terzi Mario , van Kammen Ab , de Vries Sacco C. 
Published: May 2005

AbstractAt the nonpermissive temperature, somatic embryos of the temperature‐sensitive (ts) carrot (Daucus carota L.) cell variant ts11 only proceed beyond the globular embryo stage in the presence of medium conditioned by wild‐type cells. The causative component in the conditioned medium has been identified as an acidic 32 kD endochitinase. An antiserum raised against the 32 kD chitinase detected this protein in culture medium from ts11 embryo cultures grown at the permissive temperature as well as at the nonpermissive temperature. No difference in biochemical characteristics or in effect on ts11 embryo development could be detected between the 32 kD chitinase purified from wild‐type cultures and the chitinase from ts11 cultures grown at the permissive or at the nonpermissive temperature. Compared to the amount present in a ts11 embryo culture at the permissive temperature, a reduction in the amount of 32 kD chitinase was observed during the temperature‐sensitive period at the nonpermissive temperature. These results imply that the arrested embryo phenotype of ts11 is not the result of a structural difference in its 32 kD chitinase, but is the result of a transient decrease in the amount of 32 kD chitinase present. Morphological observations indicate that the ts11 phenotype is pleiotropic and also affects the cell wall of nonembryogenic cells. © 1995 Wiley‐Liss, Inc.
Expression of knotted1 marks shoot meristem formation during maize embryogenesis
Authors: Smith Laurie G. , Jackson David , Hake Sarah 
Published: May 2005

AbstractThe formation of shoot and root meristems that ultimately give rise to all tissues of the plant body occurs for the first time during embryogenesis. Meristem formation has traditionally been defined in terms of the appearance of histological features of meristems; this approach has led to varying interpretations of the timing of meristem formation relative to other events in embryogenesis. Markers that would provide more objective criteria for the analysis of meristem formation have not been widely available. The maize homeobox gene, knotted1 (kn1), is expressed in shoot meristems throughout postembryonic stages of shoot development. In order to determine whether this gene is expressed in the shoot meristem from its earliest inception, we examined the expression of kn1 in embryos at a series of stages by in situ hybridization to kn1 mRNA and immunolocalization of KN1 protein. Our results show that the onset of kn1 expression is temporally and spatially coincident with the earliest histologically recognizable signs of shoot meristem formation in the embryo, and thus provides a valuable marker for this process. © 1995 Wiley‐Liss, Inc.
Regionalisation of cell fate and morphogenetic movement of the mesoderm during mouse gastrulation
Authors: Parameswaran Maala , Tam Patrick P. L. 
Published: May 2005

AbstractThe developmental fate of cells in the epiblast of early‐primitive‐streak‐stage mouse embryos was assessed by studying the pattern of tissue colonisation displayed bylacZ‐expressing cells grafted orthotopically to nontransgenic embryos. Results of these fate‐mapping experiments revealed that the lateral and posterior epiblast contain cells that will give rise predominantly to mesodermal derivatives. The various mesodermal populations are distributed in overlapping domains in the lateral and posterior epiblast, with the embryonic mesoderm such as heart, lateral, and paraxial mesoderm occupying a more distal position than the extraembryonic mesoderm. Heterotopic grafting of presumptive mesodermal cells results in the grafted cells adopting the fate appropriate to the new site, reflecting a plasticity of cell fate determination before ingression. The first wave of epiblast cells that ingress through the primitive streak are those giving rise to extraembryonic mesoderm. Cells that will form the mesoderm of the yolk sac and the amnion make up a major part of the mesodermal layer of the midprimitive‐streak‐stage embryo. Cells that are destined for embryonic mesoderm are still found within the epiblast, but some have been recruited to the distal portion of the mesoderm. By the late‐primitive‐streak‐stage, the mesodermal layer contains only the precursors of embryonic mesoderm. This suggests that there has been a progressive displacement of the midstreak mesoderm to extraembryonic sites, which is reminiscent of that occurring in the overlying endodermal tissue. The regionalisation of cell fate in the late‐primitive‐streak mesoderm bears the same spatial relationship as their ancestors in the epiblast prior to cell ingression. This implies that both the position of the cells in the proximal‐distal axis and their proximity to the primitive streak are major determinants for the patterning of the embryonic mesoderm. © 1995 Wiley‐Liss, Inc.
Mesodermal patterning during avian gastrulation and neurulation: Experimental induction of notochord from non‐notochordal precursor cells
Authors: Yuan Shipeng , Darnell Diana K. , Schoenwolf Gary C. 
Published: May 2005

AbstractThe cells that are normally fated to form notochord occupy a region at the rostral tip of the primitive streak at late gastrula/early neurula stages of avian and mammalian development. If these cells are surgically removed from avian embryos in culture, a notochord will nonetheless form in the majority of cases. The origin of this reconstituted notochord previously had not been investigated and was the objective of this study. Chick embryos at late gastrulal early neurula stages were cultured, and the rostral tip of the primitive streak including Hensen's node was removed and replaced with non‐node cells from quail epiblast to ensure that the cells normally fated to be notochord would be absent and that healing of the blastoderm would occur. Embryos were allowed to develop for 24 hr, and the presence and origin (host or graft) of the notochord were assessed using antibodies against notochord or quail cells. Two notochords typically developed; both were almost exclusively of host origin. The primitive streak, and in some cases adjacent tissues, was removed from another group of embryos in an attempt to estimate the mediolateral position and extent of the cells required to form reconstituted notochord. Additional experimental embryos with and without grafts were transected at various rostrocaudal levels in an attempt to estimate the rostrocaudal extent of the cells required to form reconstituted notochord. Finally, various levels of the primitive streak either were placed in a neutral environment (the germ cell crescent) or were grafted in place of the node. Collective results from all experiments indicate that the areas lateral to the rostral portion of the primitive streak, estimated to have a rostrocaudal span of less than 500 μm and a mediolateral extent of less than 250 μm, are critical for formation of the reconstituted notochord. Fate mapping and histological examination of this region identify 4 possible precursor cell populations. Further studies are underway to determine which of the 4 possible precursor cell types forms or induces the reconstituted notochord, and which tissue interactions underlie this change in cell fate. © 1995 Wiley‐Liss, Inc.
Translational control of activin in Xenopus laevis embryos
Authors: Klein Peter S. , Melton Douglas A. 
Published: May 2005

AbstractActivin is a potent mesoderm inducing factor present in embryos of Xenopus laevis. Recent evidence has implicated activin in the inhibition of neural development in addition to the well‐established induction of mesoderm in ectodermal explants. These diverse effects are critically dependent on the concentration of activin yet little is known about the mechanisms regulating the level of activin in the embryo. We report that the 3′ untranslated region (3′ UTR) of activin βB mRNA inhibits the translation of activin in embryos. Microinjection of activin mRNA from which the 3′ UTR has been deleted is 8–10‐fold more potent in inducing mesoderm than mRNA containing the 3′ UTR. Truncation of the 3′ UTR also leads to a marked enhancement of activin protein levels in embryos but has no effect when the truncated mRNA is translated in vitro. The 3′ UTR also confers translational inhibition on a heterologous mRNA. These data show that a maternal factor(s) present in X. laevis regulates the translation of injected activin βB mRNA. This factor(s) could be responsible for regulating the levels of endogenous activin βB protein during mesoderm induction and the specification of ectodermal derivatives such as neural and epidermal tissues. © 1995 Wiley‐Liss, Inc.
Characterization of a gene trap insertion into a novel gene, cordon‐bleu, expressed in axial structures of the gastrulating mouse embryo
Authors: Gasca Stephan , Hill David P. , Klingensmith John , Rossant Janet 
Published: May 2005

AbstractWe have used a gene trap (GT) vector and embryonic stem (ES) cell chimeras to screen for insertions of the lacZ reporter gene into transcription units that are spatially and temporally regulated during early mouse embryogenesis. GT vectors which can act as both a reporter and a mutagen have been previously used to isolate new genes that are essential for mouse development. In this paper we describe a GT insertion which displays a very restricted pattern of expression in the gastrulating embryo. β‐Galactosidase activity was first detected at 7.5 days post‐coitum (E7.5) in the node region of the embryo and extended to the midline structures at E8.0. At E9.5 expression was restricted to the floor plate, the notochord, the roof of the gut, and the liver anlage. Expression appeared in the somites at E10.0 and later became more widespread. We used rapid amplification of cDNA ends‐polymerase chain reaction (RACE‐PCR) to clone a partial 360 base pair (bp) cDNA representing an endogenous sequence and containing an open reading frame (ORF) fused in frame to the lacZ reporter gene. The sequence showed no homology to any known protein or protein domain. An overlapping 1,200 bp fragment from a wild‐type cDNA library was cloned and it detected the same pattern of expression as the reporter gene in E7.5, E8.5, and E9.5 wild‐type embryos. It hybridized to a 5.4 kb lacZ fusion transcript and to an endogenous transcript of 6.5 kb. The gene was mapped to chromosome 11 and was named cordon‐bleu (cobl). No phenotype was detected in mice homozygous for the insertion. However, the insertion may not cause a complete disruption of the gene function. The pattern of expression of cobl is very similar to that of hepatic nuclear factor 3β (HNF3β) and sonic hedgehog (Shh), both of which are involved in axial patterning. Therefore, the product of the cobl gene may also prove to be an important component of the genetic pathway regulating vertebrate axis formation. © 1995 Wiley‐Liss, Inc.
Epithelial proliferation and differentiation in the mammary gland do not correlate with cFABP gene expression during early pregnancy
Authors: Binas B. , Gusterson B. , Wallace R. , Clark A. J. 
Published: May 2005

AbstractCardiac fatty acid binding protein (cFABP) is abundantly expressed in the nondividing, functionally differentiated mammary ephithelium. It is very closely related, if not identical to, a previously described protein termed mammary derived growth inhibitor (MDGI). In vitro studies suggest that low concentrations of diffusible cFABP/MDGI may play a hormone‐like role in limiting proliferative activity and promoting functional differentiation of this tissue, but no in vivo data to support this idea have been published. To test this hypothesis, we compared the levels of cFABP mRNA with both the epithelial DNA labelling index and levels of β‐casein mRNA in wild‐type mice. We also investigated the effect of a precocious experimental increase of cFABP levels in the mammary gland of transgenic mice on the labelling index and β‐casein mRNA levels. This was accomplished by expressing a bovine cFABP cDNA under the control of the ovine β‐lactoglobulin (BLG) gene promoter. We found that although both the DNA labelling index, β‐casein mRNA levels, and cFABP mRNA levels in wild‐type mice are developmentally regulated, they do not correlate with each other during early pregnancy in individual mice. Moreover, a three‐ to fourfold increase of total cFABP mRNA in two transgenic lines did not affect the DNA labelling index or the levels of β‐casein mRNA, an established marker of differentiation of the mammary epithelium, at this developmental stage. These data suggest that epithelial DNA synthesis, β‐casein gene expression, and expression of the cFABP gene are regulated independently in the proliferatively active mammary gland and that the rapidly dividing mammary epithelial cells are not susceptible to the action of cFABP during early pregnancy. © 1995 Wiley‐Liss, Inc.