bluuebunny/crossref_metadata_2025_split huggingface dataset:
Frequency of X‐Y chromosome dissociation in mouse spermatocytes from interstrain crosses, recombinant inbred strains, and chimeras: Possible involvement of paternal genome imprinting
Authors: Krzanowska Halina , Wabik‐Śliz Barbara 
Published: February 2005

AbstractThe frequency of dissociation of the X‐Y chromosome bivalent in diakinesis‐metaphase I spermatocytes differs significantly between two inbred mouse strains, CBA (29%) and KE (7%), that were used to obtain reciprocal F1 hybrids, and to develop recombinant inbred (R1) strains. The level of X‐Y dissociation was significantly higher in (KExCBA)F1 hybrids sired by the CBA males (24%) than in reciprocal F1 hybrids (12%), revealing the inheritance after the father. Among 14 RI strains, nine were concordant with KE, one with CBA, and four had intermediate phenotype, significantly different from both progenitor strains. This shows that at least two genes are involved, and their possible linkage with agouti and Trf loci is suggested. The linkage with agouti was confirmed by testing additional 10 CBXE incipient RI strains. There was no significant difference in the level of X‐Y dissociation between EXCB RI strains derived from the original cross sired by the CBA males and CBXE RI strains derived from the reciprocal cross. The involvement of the Y chromosome‐linked factors was unlikely because it was found earlier (Krzanowska, 1989: Gamete Res 23:357–365) that two congenic strains, KE and KE.CBA, differing with respect to the source of the Y chromosome, had the same level of X‐Y dissociation. Thus, the difference obtained between reciprocal F1 hybrids is interpreted in terms of paternal genome imprinting imposed by CBA males and propagated only in the presence of some alleles derived from this strain.Analysis of six KE ⟷ CBA‐T6 chimeras, among them three germ line chimeras, points to the conclusion that the tendency to low or high level of X‐Y chromosome dissociation is expressed rather autonomously by KE or CBA‐T6 spermatocytes (as recognized by a marker chromosome pair), respectively, and was not modified by the presence of somatic cells of the opposite strain. © 1994 Wiley‐Liss, Inc.
Use of PCR‐based methods for selection of integrated transgenes in preimplantation embryos
Authors: Wilmut I. , Colman A. , Garner I. , S. Carver A. , Cousens C. , T.O'Neill G. 
Published: February 2005

AbstractThe production of transgenic animals from ungulate species is an inefficient and expensive procedure. The development of selection methods to identify the small number of transgenic preimplantation embryos produced following DNA microinjection of one‐cell embryos would greatly reduce both the cost and effort of these procedures. This study has examined the fate of the ovine β‐lactoglobulin‐human α1‐antitrypsin (AATB) minigene construct or a subfragment of this following microinjection into one‐cell mouse embryos. It has examined two PCR‐based methods that were designed to identify a biochemical difference between microinjected DNA constructs to select preimplantation stage embryos in which chromosomal integration of exogenous DNA has occurred. The two methods involved the modification of the AATB DNA construct either by dam‐methylation or the substitution of dTTP by dUTP. The dam‐sensitive DNA endonuclease Dpnl, that was used to digest nonintegrated AATB sequences at sites located between PCR oligonucleotide sequences, was found to interfere with the activity of the subsequent PCR reaction. Analyses of the fate of dUTP‐DNA indicated that either repair or replication of microinjected DNA interfered with the ability to distinguish between integrated and nonintegrated DNA constructs in the mid‐preimplantation stage embryo. The distribution of microinjected AATB DNA between the blastomeres of individual four and eight‐cell stage embryos was also examined by the PCR reaction. Microinjected DNA was not found to be evenly distributed between all the blastomeres of individual embryos. © 1994 Wiley‐Liss, Inc.
Sex‐related growth rate differences in mouse preimplantation embryos in vivo and in vitro
Authors: Peippo Jaana , Bredbacka Peter 
Published: February 2005

AbstractSex‐related growth rate differences in preimplantation mouse embryos were investigated. In experiment I, Day 3 embryos were recovered from reproductive tracts, classified according to developmental stage, and cultured for 24 hr in CZB medium containing glucose. Each embryo was then reclassified and stained for measurement of number of nuclei and finally sexed using the polymerase chain reaction. In experiment II, Day 4 embryos were recovered, classified, stained, and sexed as in experiment I immediately after recovery. Morphologically, there were no differences between the sexes in either of the experiments on Day 4. However, based on number of nuclei, the data showed that in vitro conditions support the development of male embryos to the blastocyst stage compared to female embryos. Furthermore, growth rate differences were observed in vivo on Day 3, as females compacted earlier than males. These results suggest that the increased cell proliferation in cultured male embryos is an artifact caused by the in vitro environment. The variation may be due to sex differences in embryonal energy metabolism during the preimplantation stage. The growth difference implies different in vitro requirements of male and female embryos. © 1995 Wiley‐Liss, Inc.
Effect of estradiol and progesterone on c‐myc expression in the sea star testis and the seasonal regulation of spermatogenesis
Authors: Marsh Adam G. , Walker Charles W. 
Published: February 2005

AbstractAnalysis of the expression of cell cycle control genes provides a sensitive assay for mitotic and meiotic progression under experimental conditions. Transcription of the c‐myc proto‐oncogene and thymidine incorporation into DNA were both used to assay the mitogenic effects of estradiol and progesterone on the testicular germinal epithelium of the starfish Asterias vulgaris. Experimental in vitro studies during the annual spermatogenic cycle show that testes are not sensitive to mitotic stimulation by estradiol alone, whereas progesterone alone is mitotically inhibitory. The germinal epithelium can only be mitotically stimulated by estradiol after pretreatment with progesterone. The net increase in mitotic activity following a progesterone to estradiol transfer is dependent on the length of progesterone pretreatment. Overall, the seasonal pattern of testicular estradiol and progesterone levels evident in field populations of A. vulgaris (Hines et al., 1992a: Endocrinology 100:1468–1471) do not appear to be responsible for initiating spermatogonial mitosis at the onset of the annual spermatogenic cycle. Expression rates of the c‐myc proto‐oncogene are substantially more sensitive than thymidine incorporation in quantifying mitotic activity. Measuring proto‐oncogene expression provides an ideal experimental approach to investigations of the regulatory mechanisms that control growth and reproduction in marine organisms. © 1995 Wiley‐Liss, Inc.
Cloning and expression of a rat placental cDNA encoding a novel cathepsin L‐related protein
Authors: Conliffe Phyllis R. , Ogilvie Susan , Simmen Rosalia C. M. , Michel Frank J. , Saunders Paul , Shiverick Kathleen T. 
Published: February 2005

AbstractCathepsin L is a major lysosomal cysteine protease produced by mouse placenta and fibroblasts. This study characterizes a novel cathepsin L‐related mRNA expressed in rat placenta. Immunological and nucleotide screening of a rat placental library identified six positive clones, the largest, pCLRP‐9, being 924 base pairs in length. The combined sequences of all the clones contain an open reading frame of 711 nucleotides, a termination codon, a polyadenylation site, and 197 nucleotides of 3′ untranslated region, but lack the 5′ translation initiation codon. The pCLRP nucleotide sequence showed 60–64% identity to those of mouse, rat, and human cathepsin L. The deduced amino acid sequence of pCLRP codes for 237 amino acids, which align with the carboxy‐terminal sequence of cathepsin L and has the active site residues characteristic of the cysteine protease family. Northern blot analysis showed hybridization of pCLRP with a major mRNA transcript of 1.3 kilobases expressed in placenta, but not kidney or liver. In contrast, a cDNA for mouse pro‐cathepsin L hybridized with a transcript of 1.7 kilobases expressed in rat kidney, as well as placenta. During late gestation, steady‐state levels of rat placental pCLRP mRNA were highest on day 18, whereas those of mouse procathepsin L were greatest on day 20 of gestation. Antiserum to mouse cathepsin L cross‐reacted with four proteins of molecular weights 36,000 to 42,000 in rat placental culture medium, of which two were absent in the kidney. These data indicate that rat placenta expresses several species of cathepsin L‐type proteins, which may be involved in placental function and nutrient supply. © 1995 Wiley‐Liss, Inc.
Expression of the mouse testis‐determining gene Sry in male preimplantation embryos
Authors: Cao Qiu Ping , Gaudette Michelle F. , Robinson Douglas H. , Crain William R. 
Published: February 2005

AbstractThe testis‐determining factor in the mouse is encoded by the Sry gene on the Y chromosome. Transcripts of this gene have been shown previously to be present in the genital ridge at the beginning of gonadal differentiation (11.5 days post coitum) and in adult testis. In this study, RNA transcripts of the Sry gene are also detected in male blastocyst‐stage embryos (3.5 days post coitum) at approximately 40–100 copies per cell, long before overt sex differentiation. These results indicate that preimplantation mouse embryos have sexually dimorphic gene expression at least with respect to Sry transcripts. In addition, at least some of the Sry RNA transcripts in blastocysts are circular, as has been reported for Sry transcripts from adult testis. The appearance of Sry transcripts in blastocysts at this level raises the possibility that sex determination begins earlier during embryonic development than previously thought. © 1995 Wiley‐Liss, Inc.
Poly (A) binding protein is bound to both stored and polysomal mRNAs in the mammalian testis
Authors: Gu Wei , Kwon Yunhee , Oko Richard , Hermo Louis , Hecht Norman B. 
Published: February 2005

AbstractRNA‐binding proteins that bind to the 3′ untranslated region of mRNAs play important roles in regulating gene expression. Here we examine the association between the 70 kDa poly (A) binding protein (PABP) and stored (RNP) and polysomal mRNAs during mammalian male germ cell development. PABP mRNA levels increase as germ cells enter meiosis, reaching a maximum in the early postmeiotic stages, and decreasing to a nearly nondetectable level towards the end of spermatogenesis. Most of the PABP mRNA is found in the nonpolysomal fractions of postmitochondrial extracts, suggesting that PABP mRNA is either inefficiently translated or stored as RNPs during spermatogenesis. Virtually all of the testicular PABP is bound to either polysomal or nonpolysomal mRNAs, with little, if any, free PABP detectable. Analysis of several specific mRNAs reveals PABP is bound to both stored (RNP) and translated forms of the mRNAs. Western blot analysis and immunocytochemistry indicate PABP is widespread in the mammalian testis, with maximal amounts detected in postmeiotic round spermatids. The presence of PABP in elongating spermatids, a cell type in which PABP mRNA is nearly absent, suggests that PABP is a stable protein in the later stages of male germ cell development. The high level of testicular PABP in round spermatids and in mRNPs suggests a role for PABP in the storage as well as in the subsequent translation of developmentally regulated mRNAs in the mammalian testis. © 1995 Wiley‐Liss, Inc.
Activin βA subunit is expressed in bovine oviduct
Authors: Gandolfi F. , Modina S. , Brevini T. A. L. , Passoni L. , Petraglia F. , Lauria A. , Artini P. 
Published: February 2005

AbstractIt is evident that members of several growth factor families are actively involved in embryogenesis from its earliest phases. Several reports also indicate the oviduct as a possible source of growth factors, suggesting an active role of this organ in mammalian embryonic development. The aim of this study was to investigate the presence of activin/inhibin subunits in bovine oviduct since activin is a well‐characterised morphogen in amphibian development. The presence of transcripts for α. βA, and βB subunits was investigated by analysing oviduct epithelial cells mRNA with reverse transcription‐polymerase chain reaction (RT‐PCR). Moreover, antisera specific for the three subunits were used for the Western blot analysis of the proteins secreted by oviduct epithelial cells in vitro and for their immunohistochemical localisation in different oviductal regions. Oviduct epithelial cells expressed only the βA‐subunit gene. Immunoreactive material was present among in vitro secreted proteins, indicating that the transcript is translated into a polypeptide that has been localised in the epithelium of both the ampullary and isthmic tract of the organ. Consistent with these results, the antisera for the α and βB subunits did not recognise any specific antigen either among secreted proteins or in the sections. These results indicate that βA subunit gene is expressed in bovine oviduct epithelial cells, and the protein is secreted in vitro and can be found along the whole extension of the organ. In the absence of α or βB subunits, this suggests that activin A is present in bovine oviduct. Such a finding would be consistent with an embry‐otrophic activity of this organ, but definitive conclusions on the target tissue and the specific functions of oviductal activin require further studies. © 1995 Wiley‐Liss, Inc.
Cumulus cell function during bovine oocyte maturation, fertilization, and embryo development in vitro
Authors: Zhang Li , Jiang Shie , Wozniak Patricia J. , Yang Xiangzhong , Godke Robert A. 
Published: February 2005

AbstractSeveral contemporary micromanipulation techniques, such as sperm microinjection, nuclear transfer, and gene transfer by pronuclear injection, require removal of cumulus cells from oocytes or zygotes at various stages. In humans, the cumulus cells are often removed after 15–18 hr of sperm‐oocyte coincubation to assist the identification of the fertilization status. This study was designed to evaluate the function of cumulus cells during oocyte maturation, fertilization, and in vitro development in cattle. Cumulus cells were removed before and after maturation and after fertilization for 0,7,20, and 48 hr. The cumulus‐free oocytes or embryos were cultured either alone or on cumulus cell monolayers prepared on the day of maturation culture. Percentages of oocyte maturation, fertilization, and development to cleavage, morula, and blastocyst stages and to expanding or hatched blastocysts were recorded for statistical analysis by categorical data modeling (CATMOD) procedures.Cumulus cells removed before maturation significantly reduced the rate of oocyte maturation (4–26% vs. 93–96%), fertilization (0–9% vs. 91–92%), and in vitro development at all stages evaluated. Cumulus cells removed immediately prior to in vitro fertilization (IVF) or 7 hr after IVF reduced the rates of fertilization (58–60% and 71%, respectively, vs. 91–92% for controls), cleavage development (40–47% and 53–54% vs. 74–78% for controls), and morula plus blastocyst development (15% and 24% vs. 45%, P < 0.05). Cumulus cell co‐culture started at various stages had no effect on fertilization and cleavage development but significantly improved rates of embryo development to morula or blastocyst stages (P < 0.05). Cumulus cell removal at 20 hr after IVF resulted in similar development to controls (P > 0.05) at all stages tested in this study. The intact state of surrounding cumulus cells of oocytes or embryos appears to be beneficial before or shortly after insemination (at or before 7 hr of IVF) but not essential at 20 hr after IVF. © 1995 Wiley‐Liss, Inc.
Atrial natriuretic peptide: A chemoattractant of human spermatozoa by a guanylate cyclase‐dependent pathway
Authors: Anderson Robert A. , Feathergill Kenneth A. , Rawlins Richard G. , Mack Stephen R. , Zaneveld Lourens J. D. 
Published: February 2005

AbstractAtrial natriuretic peptide (ANP), found in mammalian ovarian granulosa cells and oocytes (Kim et al., 1992, 1993), induces the human acrosome reaction (Anderson et al., 1994). The purpose of the present study was to determine whether ANP, as eggderived peptides from sea urchins, can act as a chemoattractant to human spermatozoa. Small lengths of capillary tubing that contained different concentrations of ANP were suspended over a suspension of washed spermatozoa. The number of spermatozoa that entered the tubing was determined. More than twice the number of spermatozoa moved into the tubing that contained a maximally effective concentration of ANP, as compared with tubing that contained only medium. The concentration of ANP that produced a half‐maximal effect was 0.7 nM. The effect was blocked by LY83583, an inhibitor of guanylate cyclase. ANP produced more than a twofold increase in the rate of cGMP formation, an effect that was blocked by LY83583. Human ANP (5–27), a fragment of the intact peptide, had no chemoattractant activity. These findings suggest that a specific sperm receptor exists for the chemoattractant activity of ANP that is associated with guanylate cyclase. The chemoattractant activity of ANP is independent of the presence of extracellular calcium ions and is independent of the action of ANP as a stimulus of the acrosome reaction. There is no association between the chemoattractant activity of follicular fluid and the follicular fluid concentration of ANP. These data suggest that factors besides ANP are responsible for the chemoattractant activity of follicular fluid. The present study adds to evidence that human ANP is a potent modulator of human sperm function. © 1995 Wiley‐Liss, Inc.
Role of glucose in mouse preimplantation embryo development
Authors: Martin Karen L. , Leese Henry J. 
Published: February 2005

AbstractMouse preimplantation embryos consume pyruvate preferentially during the early developmental stages, before glucose becomes the predominant energy substrate in the blastocyst. To investigate the importance of the switch to glucose utilization at the later developmental stages, mouse embryos from F1 hybrid mice (CBA/Ca × C57BL/6) were cultured from the one‐and two‐cell stages (22 and 46 h post hCG, respectively) for 5 days in a modified medium, M16, containing 0.33 mM pyruvate and 5 or 23 mM D+L‐lactate, in the presence and absence of 1 mM glucose (M16+G and M16‐G, respectively). Nutrient uptakes were also determined over this time. Some embryos cultured in M16‐G were transferred to M16+G at 94 or 118 h post hCG. Embryos cultured from the two‐cell stage in M16+G exhibited the characteristic fall in pyruvate consumption between the morula and the blastocyst stage; those cultured from the two‐cell stage in M16‐G compensated for the lack of glucose by consuming increasing amounts of pyruvate, from 2.78 pmol/embryo/h at 58 h post hCG to 5.21 pmol/embryo/h at 154 h post hCG. However, the percentage of embryos developing to the blastocyst stage, the hatching rate, and blastocyst cell numbers (50.6 ± 2.5 [28] vs. 105 ± 3.8 [37]) were all lower in this group. When exposed to glucose at 94 or 118 h post hCG, embryos cultured from the two‐cell stage in M16‐G readily consumed glucose in preference to pyruvate, although the characteristic fall in pyruvate consumption was not observed. One‐cell embryos cultured continuously in M16‐G were only able to develop to the morula stage, after which time they degenerated. In these embryos pyruvate was readily consumed between 22 and 94 h post hCG, before falling from 2.77 pmol/embryo/h at 83 h post hCG to 0.045 pmol/embryo/h at 130 h post hCG. Transfer of these embryos to M16+G at 94 and 118 h post hCG did not support development to the hatching blastocyst stage. The results show that mouse preimplantation embryos from F1 hybrid mice (CBA/Ca × C57BL/6) need only be exposed to glucose for less than 24 h between 22 and 94 h post hCG in order to develop from the morula to the blastocyst stage in vitro. However, the exposure time needs to be increased to between 24 and 72 h in order that blastocyst cell numbers reach control levels. The importance of glucose before the morula stage may relate to the need to synthesize glycogen for later use. If the obligatory requirement for glucose is fulfilled, embryos are able to utilize pyruvate in the absence of glucose at the later stages of development. These results show that the mouse preimplantation embryo can, to some extent, adapt metabolically to changes in its external environment. © 1995 Wiley‐Liss, Inc.
Detection of Y‐bearing porcine spermatozoa by in situ hybridization using digoxigenin‐labeled, porcine male‐specific DNA probe produced by polymerase chain reaction
Authors: Kawarasaki Tatsuo , Kohsaka Tetsuya , Sone Masaru , Yoshida Mitsutoshi , Bamba Kimio 
Published: February 2005

AbstractThis study was carried out to determine whether Y‐bearing porcine spermatozoa could be detected by in situ hybridization using a digoxigenin (Dig)‐labelled DNA probe specific to the Y chromosome produced by polymerase chain reaction (PCR). A conventional PCR (with Dig‐dUTP) was performed using a set of oligonucleotide primers (5′‐AAGTGGTCAGCGTGTCCATA‐3′ and 5′‐TTTCTCCTGTATCCTCCTGC‐3′) for 236 bp fragment of porcine male‐specific DNA sequence and 1.25 × 104 template white blood cells obtained from a boar. When fluorescence in situ hybridization with the Dig‐labelled DNA probe was applied to the metaphase chromosome spreads prepared from both boar and gilts, the fluorescein signal was only detected on the long arm of the Y chromosome. In addition, immunocytochemical detection with the Dig‐labelled DNA probe and alkaline phosphatase‐labeled anti‐Dig was applied to both sperm nuclei pretreated with dithiothreitol and white blood cells; 51% of sperm nuclei and 96% of white blood cells obtained from boar were labelled, whereas none of white blood cells obtained from gilts were labelled with the Dig‐labelled DNA probe. The results indicated that in situ hybridization with porcine male‐specific DNA probe produced by PCR made possible the direct visualization of Y‐bearing porcine spermatozoa by in situ hybridization. © 1995 Wiley‐Liss, Inc.
Synthesis and accumulation of p34cdc2 and cyclin B in mouse oocytes during acquisition of competence to resume meiosis
Authors: Chesnel Franck , Eppig John J. 
Published: February 2005

AbstractThis study tests the hypothesis 033 that growing murine oocytes, which are incompetent to resume meiosis, are deficient in their content of p34cdc2 and/or cyclin B, the two subunits of maturation promoting factor (MPF). Accumulation of the two MPF components occurred in an asynchronous manner in growing oocytes. Cyclin B content reached maximal levels in oocytes that were not yet competent to undergo germinal vesicle breakdown (GVB), the first obvious morphological manifestation of the resumption of meiosis. Thus, the amount of cyclin B is not the limiting factor rendering these growing oocytes incompetent to undergo GVB. In contrast, synthesis and accumulation of p34cdc2 increased during the period of oocyte growth in vivo when they became competent to undergo GVB. A similar increase in the amount of p34cdc2 also occurred in cultured granulosa cell‐free oocytes despite the lack of oocyte growth, but these cultured oocytes did not become GVB competent. Thus, the accumulation of p34cdc2 is probably necessary, but not sufficient, for mouse oocytes to become competent to undergo GVB. This accumulation occurs autonomously in oocytes independently of growth or of the participation of follicular somatic cells. © 1995 Wiley‐Liss, Inc.