bluuebunny/crossref_metadata_2025_split huggingface dataset:
Contractile proteins and nonerythroid spectrin in oogenesis of Xenopus laevis
Authors: Ryabova L. V. , Virtanen I. , Wartiovaara J. , Vassetzky S. G. 
Published: February 2005

AbstractThe distribution of contractile proteins, actin and myosin, and an actin‐binding protein, spectrin, was studied in oogenesis of Xenopus laevis. These proteins are present in oocytes already at the previtellogenic stages, which are characterized by their diffuse distribution. The localization of proteins changed with the beginning of vitellogenesis. At all vitellogenic stages, including the fully grown oocyte, animal–vegetal differences were noted in localization of actin and myosin: in the animal hemisphere they appear as fibrillar‐like structures, while in the vegetal one they are localized around the yolk platelets. By the end of the oocyte's growth, a cortical gradient appeared: predominant localization of actin and myosin in the cortical area. As the oocyte maturation proceeded, the distribution of actin and myosin again became diffuse and nonuniform, so that a cortical gradient appears. At the beginning of vitellogenesis spectrin is distributed as a network all over the ooplasm, while in the fully grown oocyte it is localized mostly in teh subcortical area of the animal hemisphere and, as individual inclusions, in other regions of the oocyte. No spectrin is found by the end of maturation. Actin, myosin, and spectrin are also present in the oocyte's nuclei. Changes in the distribution of contractile proteins and spectrin during oocyte maturation are discussed with respect to the development of cortical contractility, as well as to the changes in spatial distribution of yolk platelets and regional sensitivity of the maturing oocyte to cytochalasin B. © 1994 Wiley‐Liss, Inc.
Characterization of a cell surface glycoprotein associated with maturation of rat spermatozoa
Authors: Eccleston Eric D. , White Thomas W. , Howard James Bryant , Hamilton David W. 
Published: February 2005

AbstractThe principal galactose oxidase/NaB[3H]4‐labeled membrane protein of rat caudal epididymal spermatozoa was isolated by hydrophobic interaction chromatography. The protein is released from the membrane by the action of phosphatidylinositol specific phospholipase C, and thereby its properties are transformed from those of a protein anchored to the hydrophobic membrane to those of a hydrophilic solution protein. Because it is the only membrane‐associated protein released by the enzyme which did not absorb to a propylaspartate resin, a simple, single step purification procedure was devised.Although the amino terminus of the protein is blocked to Edman degradation, the majority of the protein structure was determined from a series of tryptic peptides and from limited acid hydrolysis. Approximately 65% of the protein mass is carbohydrate which is primarily attached through O‐glycosidic bonds to the 18 threonines. The molecular weight of the glycoprotein was estimated to be 16,600, considerably smaller than the Mr = 26,000 to 37,000 previously determined by gel electrophoresis. The anomalous electrophoretic behavior is undoubtedly due to the large percentage of carbohydrate. The distribution of carbohydrate on the protein side chains suggests the protein may form a positively charged, specialized scaffolding for the presentation of the carbohydrate moieties. Because the appearance of the ability to label the protein with galactose oxidase is correlated with sperm maturation in the epididymis, the glycoprotein structures may be an important componetn in the fertilization process. The combination of linkage by glycosylphosphatidylinositol and low molecular weight mucin‐like structure indicates this may be a member of a new class of membrane proteins. © 1994 Wiley‐Liss, Inc.
Major human epididymis‐specific gene product, HE3, is the first representative of a novel gene family
Authors: Kirchhoff Christiane , Pera Ilka , Rust Werner , Ivell Richard 
Published: February 2005

AbstractDifferential screening of a human epididymal cDNA library led to the isolation and characterization of a major epididymis‐specific cDNA clone family, referred to as HE3. More detailed sequence and PCR analysis identified two different but homologous gene transcripts, HE3α and HE3β. The former represents an mRNA of ca. 1 kb, encoding a putative small secretory polypeptide of 14903 MW. The HE3β transcript was only found as incomplete 3′ fragments. Analysis of human genomic DNA by Southern blotting suggested the presence in the human genome of at least three independent HE3‐related genes. Isolation of genomic clones for the HE3α gene showed this to contain a single intron of 1.4 kb in the 5′ noncoding region. Although genomic clones corresponding to HE3β could not be found, a third highly homologous gene, HE3γ, was identified as a potential pseudogene. Neither nucleotide nor encoded amino acid sequences of the HE3 gene family are related to any other known sequence in the central databases, and thus represents a novel human gene family, with at least three nonallelic members. Northern hybridization analysis showed that HE3 gene products are specifically expressed in the human epididymis, and not in any other tissue examined. Furthermore, except for the pig, no other nonprimate species has been identified to express homologous sequences in the epididymis. RNase protection assays showed that both the HE3α and HE3β, but not the HE3γ genes, are expressed in the human epididymis. © 1994 Wiley‐Liss, Inc.
Low‐affinity nerve growth factor receptor is expressed during testicular morphogenesis and in germ cells at specific stages of spermatogenesis
Authors: Russo Mario A. , Odorisio Teresa , Fradeani Andrea , Rienzi Laura , De Felici Massimo , Cattaneo Antonino , Siracusa Gregorio 
Published: February 2005

AbstractNerve growth factor (NGF) is essential for neuronal development and differentiation. Recent reports have shown that its low‐affinity receptor (LNGFR) is expressed and developmentally regulated in a broad range of embryonic and adult tissues outside the nervous system, although the functions of the receptor in such tissues remain unknown. Recently, NGF and LNGFR have been detected in adult mouse, rat, and human testis.The results of the present work demonstrate that LNGFR is expressed much before the onset of spermatogenesis in both mouse and rat testis. In situ hybridization shows that the mRNA for LNGFR is expressed in the peritubular cells of the embryonic mouse testis. Immunohistochemical analysis of the rat testis shows LNGFR‐expressing cells to be scattered in the intertubular compartment in the embryonic testis, and to become organized in a cellular layer that surrounds myoid cells of the seminiferous tubules during postnatal development. Furthermore, in peripuberal and adult mouse and rat testis we have identified the expression of an abundant and shorter mRNA of 3.2 kb that cross hybridizes to the low‐affinity NGF receptor transcript (3.7 kb). This shorter mRNA species, which appears at the beginning of spermatogenesis in the adult, has been identified by in situ hybridization and by Northern blot with RNA isolated from homogeneous populations of meiotic germ cells to be expressed by pachytene spermatocytes and round spermatids. Our results suggest a complex developmental role for LNGFR during testicular morphogenesis and identify the expression, at specific stages of spermatogenesis, of a new germ cell—specific transcript homologous to the receptor RNA. © 1994 Wiiey‐Liss, inc.
Polyadenylation and deadenylation of maternal mRNAS during oocyte growth and maturation in the mouse
Authors: Paynton Barbara V. , Bachvarova Rosemary 
Published: February 2005

AbstractWe previously showed that, during mouse oocyte maturation, specific maternal mRNAs (actins) are deadenylated, while others (hypoxanthine phosphoribosyltransferase:HPRT) are adenylated. As in other systems, these changes can be correlated with changes in transiational activities. Maturation‐specific polyadenylation in Xenopus depends on the presence of a U‐rich cytoplasmic polyadenylation element (CPE) close to the 3′ end of the RNA. RNAs that lack CPEs appear to be deadenylated by default when meiosis resumes. We show here that this default program also applies to maturing mouse oocytes. Microinjected β‐ and γ‐actin 3′ UTR (untranslated region) transcripts lacking CPEs but including polyA tails (100–200 N) behave as endogenous maternal actin mRNAs and are at deadenylated by maturing oocytes. “Nonsense” transcripts taht do not include CPEs, but that do contain polyA tails, are also deadenylated. β‐ and γ‐Actin 3′ UTRs with short polyA tails (50–80 N) are stable and exhibit no detectable change in adenylation when injected into growing, fullgrown, or maturing oocytes. In contrast, HPRT 3′ UTRs, which include the CPE UUUUAAAU and a short polyA tail (50 N), are polyadenylated during maturation. HPRT 3′ UTR transcripts with long polyA tails (100–200 N) are more extensively deadenylated by growing and full‐grown oocytes that retain germinal vesicles than by maturing oocytes. The presence of CPEs may be required for polyA tail shortening and translational inactivation of stable mRNAs during oocyte growth and subsequent selective readenylation and translation during meiotic maturation. We propose that the absence of CPEs on maternal mRNAs translationally active during oogenesis enables them to retain polyA tails of sufficient length for recruitment onto polysomes and later allows for their deadenylation by default and removal from polysomes after meiosis resumes. © 1994 Wiley‐Liss, Inc.
Immunolocalization of proacrosin/acrosin in rabbit sperm during acrosome reaction and in spermatozoa recovered from the perivitelline space
Authors: Valdivia M. , Yunes R. , Melendez J. , de Ioannes A. E. , Leyton L. , Becker M. I. , Barros C. 
Published: February 2005

AbstractThe participation of acrosin in mammalian sperm penetration through the zona pellucida has been amply debated. In this paper we report the immunolocalization—by silver enhanced immunogold technique using ACRO‐8C10 monoclonal antibody to human acrosin—of proacrosin/acrosin on ejaculated rabbit spermatozoa incubated in vitro in a capacitating medium and on spermatozoa recovered from the perivitelline space. After incubation in a capacitating medium, four different patterns were observed: (1) no labeling on acrosome intact spermatozoa; (2) labeling on the rim of the head; (3) labeling on the whole acrosome area; and (4) no labeling on acrosome reacted spermatozoa. At the start of incubation, spermatozoa with pattern 1 were the most abundant, whereas at the end of the 32 h incubation period, patterns 2 and 3 were the most frequent. On the other hand, 625 perivitelline spermatozoa were recovered from 17 fertilized rabbit eggs, of which 26% were labeled with the anti‐acrosin monoclonal antibody ACRO‐8C10 in two different areas: (1) only on the equatorial region; and (2) only on the postacrosomal area. These results are consistent with the idea that proacrosin/acrosin remains associated to the acrosome reacted spermatozoa for long periods of time, and that proacrosin/acrosin associated to perivitelline spermatozoa could be responsible for the second penetration of fresh rabbit eggs by perivitelline spermatozoa. © 1994 Wiley‐Liss, Inc.
Oocyte morphology in dominant and subordinate follicles
Authors: Assey R. J. , Hyttel P. , Greve T. , Purwantara B. 
Published: February 2005

AbstractThe structure of oocytes aspirated from the dominant and its subordinate follicles was investigated from the achievement of follicular dominance to ovulation. Ovulation was induced in 18 heifers and 5 cows by injection of cloprostenol at days 8–14 (day 0 = day of ovulation), and follicular development was monitored by ultrasonography. The animals were slaughtered at days 3–11, but animals slaughtered on days 8–11 were given a second injection of cloprostenol at day 7 to allow ovulation of the dominant follicle of the first follicular wave. Oocytes were aspirated from the dominant (largest) and two largest subordinat efollicles and processed for transmission electron microscopy, whereas the follicular fluids were analyzed for concentrations of estradiol‐17β (E2) and progesterone (P4).Dominant follicular growth was associated with increase in the concentration of E2 and P4 in the follicular fluid, which was E2‐dominated. From days 3–7, the dominant oocytes had pronounced junctional contacts with the cumulus cells and a nonundulating nuclear envelope but showed an increase in the number of lipid droplets and a decrease in the size of Golgi complexes, the size of cortical granule clusters, and the number of microvilli stacks. After cloprostenol injection on day 7, but before the anticipated LH surge, the dominant oocytes showed a reduced oocyte cumulus contact, vacuolization of the nucleolus, undulation of the nuclear envelope, and dispersal of the mitochondrial clusters. The morphological alterations occurring in the dominant oocytes before the anticipated LH surge are suggested to be a prerequisite for the oocyte to achieve the competence to undergo final maturation. Subordinate follicles ceased growing at about days 3–4 and their follicular fluid had low E2:P4 ratio or was P4‐dominated. Subordinate oocytes displayed degenerative features in their cumulus investment and nuclear activation and maturation especially after day 5. The structural changes associated with oocyte degeneration showed similarities with the processes seen before and during final maturation of the dominant oocytes. © 1994 Wiley‐Liss, Inc.
Transcription of circular and noncircular forms of Sry in mouse testes
Authors: Zwingman Theresa , Fujimoto Hirokazu , Lai Li‐Wen , Boyer Timothy , Ao Asangla , Stalvey John R. D. , Blecher Stan R. , Erickson Robert P. 
Published: February 2005

AbstractAlthough its expression in adult testis was immediately apparent, the role for Sry (sex determining region, Y) in testicular function remains elusive. We have performed transcriptional studies in an effort to elucidate potential roles of Sry by studying the time and location of its transcription in mouse testes. Northern analyses and more sensitive nuclease protection assays detected transcripts in 28‐day‐old testes and beyond. The highly sensitive technique of reverse transcription polymerase chain reaction (RTPCR) could not detect Sry expression in 14‐day testes when primers for the most conserved portion of the gene, the high mobility group (HMG) box, were used, but primers for the circular form detected Sry transcription at all postnatal stages studied. The same HMG box primers were able to detect expression of Sry in XX, Sxra or Sxrb testes. This suggested that Sry is expressed in cells other than germ cells, which was confirmed with studies on fractionated cells—RTPCR detected transcription of Sry in the highly pure interstitial cell fraction. However, Leydig cells and a Leydig cell tumor were negative for Sry expression. We performed in situ studies in an attempt to localize the expression of Sry in the testes. Abundant expression of an Sry cross‐hybridizing transcript was found in spermatogonia, in early spermatocytes, and in some interstitial cells with antisense probes to the HMG box or a more specific, 3′ region, whereas the sense probe gave little or no hybridization. It is probable that the circular transcripts, which are seen in reverse transcriptase positive (RT+) and RT− reactions by PCR because of the RT activity of Taq polymerase, are responsible for the hybridization seen in spermatogonia and spermatocytes, whereas linear and circular forms are detected later. Thus Sry is expressed in pre‐ and postmeiotic germ cells and in somatic cells of the testes. © 1994 Wiley‐Liss, Inc.
Isolation and identification of germ cells from fetal bovine ovaries
Authors: Lavoir M.‐C. , Basrur P. K. , Betteridge K. J. 
Published: February 2005

AbstractGonadal cell suspensions were made from bovine fetuses of 35–55‐, 56–80‐, and 80–130‐day age groups corresponding to the periods predominated by primordial germ cells (PGCs), oogonia, and meiotic cells, respectively. Germ cells identified on morphological criteria prior to their isolation from suspensions were compared histochemically and morphologically with cells in cryosections, impression smears, and semithin sections of similar gonads. Oocytes were distinguished by their chromosomal configurations in cell spreads.In suspensions from 35–55‐day fetuses, cells considered to be PGCs stood out by their size, large nucleus, intracytoplasmic vesicles, and occasional blebbing. The somatic cells were smaller and contained little cytoplasm and few vesicles. In bovine gonads, in contrast to murine gonads, alkaline phosphatase (AP) activity was not specific enough to identify germ cells once they had entered the gonad. In ovaries from the 56–80‐day age group, cells similar to PGCs, but slightly larger and with more cytoplasmic vesicles, were identified as oogonia. The cytoplasmic vesicles stained positively for lipid. In ovaries of 80–130‐day fetuses, oogonia, oocytes, degenerating germ cells, and multinucleate germ cells were recognized. Degenerating germ cells exhibited a variety of morphological characteristics and were consistently positive for acid‐phosphatase activity. Binucleate germ cells appeared around day 85 of gestation, while multinucleate germ cells were seen from day 95. It was concluded that bovine mitotic germ cells can be isolated from gonadal cell suspensions and that the best time to recover them is between 50 and 70 days of gestation. © 1994 Wiley‐Liss, Inc.
Regulation of the fertilization current in ascidian oocytes by intracellular second messengers
Authors: Tosti Elisabetta , Dale Brian 
Published: February 2005

AbstractNeomycin, injected into ascidian oocytes to a final concentration of 10–50 mM, inhibits both the fertilization current and the surface contraction, showing that phosphoinositide hydrolysis is required for these early activation events. Sperm‐activated fertilization currents are not inhibited in the presence of 100 μg/ml intracellular heparin, suggesting that these currents are not directly gated by InsP3. The sulfhydryl reagent thimerosal at 100 μM, in contrast, significantly increases the fertilization current presumably by sensitizing the channel receptor. Since heparin inhibits the surface contraction, InsP3 receptors are shown to play a role in the propagation of the activation response in ascidian oocyte. Depleting intracellular calcium stores by microinjecting 50 mM EGTA into oocytes does not activate fertilization channels; however, subsequent fertilization of these EGTA loaded oocytes leads to a significantly larger and faster fertilization current. Thus in contrast to somatic cells studied to date, second messenger operated plasma membrane channels in ascidian oocytes are not gated by calcium released from intracellular stores. © 1994 Wiley‐Liss, Inc.
Activation of embryonic genes during preimplantation rat development
Authors: Zernicka‐Goetz Magdalena 
Published: February 2005

AbstractExpression of the embryonic genome has been examined during preimplantation rat development. Proteins synthesized at different stages of embryogenesis were labelled with [35S]methionine and then separated by one‐dimensional gel electrophoresis. A major transformation in the pattern of protein synthesis has been observed between the two‐ and the four‐cell stages of embryonic development. Also the culture of embryos with an inhibitor of transcription (α‐amanitin) has shown that the first α‐amanitin‐sensitive events take place during the late two‐cell stage. However, inhibition of transcription does not arrest the embryo development up to the four‐cell stage. Taken together, the results indicate that in rats the initiation of embryonic gene activation occurs at the late two‐cell stage. However, the first two cleavage divisions can occur in the absence of transcription. © 1994 Wiley‐Liss, Inc.
Evidence for a strong paternal effect on human preimplantation embryo development and blastocyst formation
Authors: Janny Laurent , Menezo Yves J. R. 
Published: February 2005

AbstractIn human in vitro fertilization (I.V.F.), it was first assumed that all the embryos obtained had the same developmental potential whatever the quality of sperm. However, this has not been confirmed. We have used the coculture technique and determined the blastocyst formation rate in three groups of patients: group 1: patients with normal sperm count (>20 × 106/ml), motility (>30%), and morphology (>50%); group 2: patients treated by I.V.F. with frozen donor sperm; group 3: patients with severely impaired sperm quality (<3 × 106 forward motile and morphologically normal spermatozoa per ml). In group 1, we found a strong correlation between cleavage rate and blastocyst formation rate (P < 0.0001) with a blastocyst formation rate comprised between 40% and 50%. This was not true for the two other groups for which the overall number of blastocysts obtained and the number of patients having at least one blastocyst were severely reduced (P < 0.0001). These data are discussed in terms of DNA quality, timing of formation of the pronuclei, and delays in cell cycles at the time of genomic activation. These observations lead to a new approach to the study of fertilizing ability of poor quality sperm. It may help in the decision as to whether couples treated for male infertility should be excluded from I.V.F. protocols. © 1994 Wiley‐Liss, Inc.
Epididymal glycoprotein involved in rat sperm association
Authors: Fornes Miguel W. , Burgos Mario H. 
Published: February 2005

AbstractRecently, a new head‐to‐head sperm association was described in the rat during epididymal transit. This association was called a rosette and a filamentous and PAS‐positive material was also described joining the sperm heads. The begining of rosette formation in the epididymis and the linking material between heads have remained unclear. Epididymides of adult rats were fixed by vascular perfussion and thin sections of the principal regions were studied by transmission electron microscopy (TEM). The first evidence of rosette formation was observed in the distal corpus. Rosettes were isolated from the distal corpus and processed for immunogold and immunofluorescence microscopy to detect an epididymal glycoprotein called DE. This glycoprotein is secreted by the corpus epididymis and appears to be involved in sperm maturation. Colloidal gold marks and fluorescence were observed in the linking material between the sperm heads. The results presented here show that rosettes begin to appear following the sites of DE secretion and permit us to postulate that DE is involved in rosette formation and constitutes another example of gamete‐epididymal interaction. © 1994 Wiley‐Liss, Inc.
Characterization of the main egg envelope proteins of the sea bass Dicentrarchus labrax L. (teleostea, serranidae)
Authors: Scapigliati Giuseppe , Carcupino Marcella , Taddei Anna Rita , Mazzini Massimo 
Published: February 2005

AbstractFish eggs are surrounded by a resistant acellular coat commonly called the chorion or zona radiata. This study characterizes the eggshell proteinaceous content of unfertilized eggs of the sea bass Dicentrarchus labrax, with a view to the prepration of immunogens. Solubilization of the purified eggshells was achieved in 8 M urea followed by one‐ and two‐dimensional gel electrophoresis. Glycoproteins were detected using concanavalin‐A in one and two‐dimensional gels, and the principal glycoproteins had a molecular weight of 47 kDa and 170 kDa. Partial purification of a few polypeptides in the 45 kDa to 55 kDa range was achieved by gel filtration chromatography. Although whole eggshells were relatively insoluble even in 8 M urea, partial purification of these polypeptides enable them to dissolve completely in solutions at low ionic strength. © 1994 Wiley‐Liss, Inc.