bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fertilization and developmental competence of bovine oocytes derived from different categories of antral follicles
Authors: Pavlok A. , Lucas‐Hahn A. , Niemann H. 
Published: February 2005

AbstractThis study investigated the capacity of healthy oocytes derived from follicles of different size to undergo normal fertilization and early embryonic development in vitro and full‐term development in vivo. Ovaries were collected from a local abattoir and dissected and classified as follows: group A, >4–8 mm (large); group B, >2–4 mm (medium); and group C, >1–2 mm (small). Oocytes were isolated by puncturing the follicular wall and pressing of the follicle. Only healthy‐looking cumulusoocyte complexes (COC) were used for in vitro maturation. Oocytes were fertilized in vitro by frozen/thawed semen from one bull. Approximately one‐fourth of all oocytes was fixed and stained 15–20 h after fertilization, to determine penetration rates. The remaining eggs were transferred to culture medium and were cultivated for up to 9.5 days. Cleavage was observed 65 h and 7 days after fertilization. Expanded, hatching, and hatched blastocysts were fixed and stained after 9.5 days of culture. A total of 86 blastocysts derived from group A and B oocytes was nonsurgically transferred to synchronized recipients 7–8 days after onset of culture. A total of 6.624 follicles were dissected from 265 ovaries, and 1,485 oocytes were isolated from 1,671 group A follicles, 3,509 oocytes from 3,862 group B follicles, and 965 oocytes from 1,091 group C follicles. The fertilization rate, rate of normal fertilization, rate of polyspermy, and rate of other abnormal fertilization features were as follows: group A, 84.9%, 43.2%, 34.1%, 7.6%; group B, 83.6%, 44.8%, 31.1%, 7.8%; and group C, 61.7%, 13.1%, 33.7%, 19.1%. The cleavage rate and the percentage of embryos with 5–8 cells after 65 h amounted in group A to 68.9% and 36.9%; in group B, 64.3% and 32.7%; and in group C, 19.7% and 0.4%, respectively. The percentage of blastocysts on days 7 and 9.5 as well as the rate of hatched blastocysts were 27.7%, 24.8%, and 21.7%, respectively, in group A; 20.9%, 19.2%, and 16.8%, respectively, in group B; and zero in group C. Transfer of 38 blastocysts of group A to 19 recipients led to 10 pregnancies; transfer of 48 blastocysts to 24 recipients of group B resulted in 12 pregnancies. It is concluded that blastocysts from follicles ranging from >2 to 8 mm in size have a similar developmental potential. Oocytes from 1‐ to 2‐mm follicles, however, have a significantly lower competence to undergo in vitro maturation and fertilization and, under the conditions of our experiments, completely lack the capability to cleave beyond the 8‐cell stage.
Expression of growth factor ligand and receptor genes in the preimplantation bovine embryo
Authors: Watson Andrew J. , Hogan Aileen , Hahnel Ann , Schultz Gilbert A. , Wiemer Klaus E. 
Published: February 2005

AbstractThe sensitive technique of mRNA phenotyping with the reverse transcription‐polymerase chain reaction was employed to determine the patterns of gene expression for several growth factor ligand and receptor genes during bovine preimplantation development. Several thousand bovine embryos encompassing a developmental series from one‐cell zygotes to hatched blastocysts were produced by the application of in vitro maturation, fertilization, and oviductal epithelial cell embryo coculture methods. Transcripts for transforming growth factor (TGF‐α) and platelet‐derived growth factor (PDGF‐A) are detectable in all preimplantation bovine stages as observed in the mouse. Transcripts for TGF‐β2 and insulin‐like growth factor (IGF‐II) and the receptors for PDGF‐α, insulin, IGF‐I, and IGF‐II are also detectable throughout bovine preimplantation development, suggesting that these mRNAs are products of both the maternal and the embryonic genomes in the cow, whereas in the mouse they are present only following the activation of the embryonic genome at the two‐cell stage. In contrast to the mouse embryo, IGF‐I mRNA was detected within preimplantation bovine embryos. Basic fibroblast growth factor (bFGF) is a maternal message in the bovine embryo, since it is only detectable up until the eight‐cell embryo stage. Bovine trophoblast protein (bTP) mRNA was detectable within day 8 bovine blastocysts. As was observed in the mouse, the transcripts for insulin, epidermal growth factor (EGF), or nerve growth factor (NGF) were not detectable in any bovine embryo stage. Analyses of this type should aid the development of a completely defined culture medium for the more efficient production of preimplantation bovine embryos.
Sea urchin small RNA ribonucleoprotein particles: Identification, synthesis, and subcellular localization during early embryonic development
Authors: LeBlanc Janine M. , Infante Anthony A. 
Published: February 2005

AbstractSmall RNAs in sea urchins were examined in order to characterize developmental changes in their level, subcellular localization, synthesis, and association with proteins and other RNAs. Small RNAs such as the U snRNAs, 5S and 5.8S rRNAs, and 7S RNAs were identified by their mobility on highly cross‐linked acrylamide gels. In addition, 7SL and U1 RNAs were identified by northern blot hybridization to cloned human and sea urchin probes, respectively. The level, subcellular localization, and association with proteins or RNA do not change for most small RNAs from fertilization to blastula, even though this is the time when the stored maternal pool of many small RNAs is being supplemented and replaced by embryonically synthesized RNAs. New embryonic synthesis of small RNAs was first detected at the 8–12 hr blastula stage. Although the predicted subsets of the total small RNA pool can be found in the appropriate subcellular compartment, newly synthesized small RNAs have a predominantly cytoplasmic localization. All of the newly synthesized small RNAs were found to be constituents of small RNPs. The RNPs containing newly synthesized small RNAs had sedimentation rates indistinguishable from their maternal counterparts. Thus, on the basis of sedimentation rate, no gross differences could be detected between maternal and embryonic small RNP pools. These small RNPs include a cytoplasmic RNP containing newly synthesized U1 snRNA and the sea urchin signal recognition particle (SRP) containing the 7SL RNA. We have also identified a small RNP bearing the 5S rRNA which is present in both eggs and embryos. The presence of multiple, abundant, small RNAs and RNPs that are maintained at constant levels in particular subcellular fractions throughout development suggests that small RNAs may be involved in many more cellular activities than have so far been described.
Cyanide‐resistant reduction of nitroblue tetrazolium and hydrogen peroxide production by the rabbit blastocyst
Authors: Manes Cole 
Published: February 2005

AbstractThe ability of the rabbit blastocyst to reduce nitroblue tetrazolium (NBT) to formazan in the presence of cyanide was assayed as an indicator of extramitochondrial oxidase activity capable of generating the superoxide radical. A cytochemical method initially developed for the detection and localization of hydrogen peroxide production at the ultrastructural level in phagocytosing leukocytes (Briggs et al.: J Cell Biol 67:566, 1975) was also applied to the blastocyst. The results demonstrate that the rabbit blastocyst acquires the ability to reduce NBT by a cyanide‐insensitive process and to generate hydrogen peroxide between the fourth and fifth days postcoitum. The enzymatic activity responsible is apparently an NAD(P)Hdependent oxidase in the outer, microvillous plasma membrane of the trophoblast.
Thyroid stimulating hormone enhancement of bovine oocyte maturation in vitro
Authors: Younis Abdelmoneim I. , Brackett Benjamin G. 
Published: February 2005

AbstractEfforts to improve bovine embryonic development in vitro involved study of effects of thyroid stimulating hormone (TSH) alone or in combination with LH on bovine oocyte maturation (IVM). Putative effects were assessed by observing cumulus expansion (CE), fertilization (IVF), and development to morulae/blastocysts (M/B). Effects of prolactin (PRL) were also investigated. Variables for the 24‐hr IVM interval were no hormone (control), TSH (0.1, 0.5, or 1.0 μg/ml) or PRL (10, 100, or 1000 μg/ml), luteinizing hormone (LH) (0, 10, or 100 μg/ml) + TSH (0.1 or 0.5 μg/ml), and serum (20%, v/v) + 0.5 μg TSH/ml; data were from 4–5 trials for each IVM treatment. Higher proportions of oocytes exhibited complete CE with hormones or serum than without (P < 0.05). All oocytes (with and without CE) were inseminated with heparin‐capacitated sperm. A higher proportion of inseminated oocytes cleaved after IVM with 0.5 μg TSH/ml (53.4%) than for other TSH treatments (P < 0.05). The combination of TSH (0.1 and 0.5 μg/ml) with 10 μgLH/ml for IVM enabled higher proportions (P < 0.05) of ova to fertilize (67.4 and 69.2%) than did medium alone (28.3%), LH (10 μg/ml) alone (54.1%), or serum + 0.5 μg TSH/ml (55.6%). No improvement in proportions undergoing fertilization was seen after addition of TSH to 100 μgLH/ml for IVM. Frequency of CE and cleavage did not differ among PRL treatments. More M/B developed from cleaved ova after IVM with LH or TSH than with PRL or no hormone (P < 0.05). Data document the beneficial influences of TSH and LH during IVM on the quality of the resulting ova.
Highly acetylated H4 is associated with histone displacement in rat spermatids
Authors: Meistrich Marvin L. , Trostle‐Weige Patricia K. , Lin Rueyling , Allis C. David , Bhatnagar Yogendra M. 
Published: February 2005

AbstractThe presence of highly acetylated histone H4 during spermatogenesis was studied to evaluate its correlation with the events of gene transcription, histone deposition, and histone displacement. We utilized an antibody raised to a pentaacetylated synthetic peptide that preferentially recognizes highly (tetra‐ and tri‐) acetylated forms of rat testis H4. Electrophoretic separation of histones from enriched fractions of spermatogenic cells followed by detection of these forms by staining and by immunoblotting using this antibody showed that the highly acetylated forms were limited almost exclusively to spermatids beginning at step 11 of development. Immunofluorescence generally confirmed this result but also detected a high degree of acetylation in steps 9 and 10. Immunofluorescence also revealed a striking polarity in the progression of histone from the spermatid nucleus. Highly acetylated H4 was displaced from the anterior to the caudal portion of the spermatid nucleus during steps 11 and 12, along with other histones, prior to their displacement by transition proteins. Thus, while monoacetylated and low levels of diacetylated forms of H4 were associated with stages at which histone deposition and transcription occur, the more highly acetylated forms appeared in high levels only at the stage at which histone displacement occurs.
Sperm capacitation in the domestic cat (Felis catus) and leopard cat (Felis bengalensis) as studied with a salt‐stored zona pellucida penetration assay
Authors: Andrews J. C. , Howard J. G. , Bavister B. D. , Wildt D. E. 
Published: February 2005

AbstractThe ability of domestic cat or leopard cat spermatozoa to penetrate zonae pellucidae (ZP) of salt‐stored, domestic cat oocytes was examined as an assay for sperm capacitation. Ovarian oocytes were recovered after ovariectomy and matured in vitro for 18–36 h. Following removal of cumulus cells, the oocytes were used fresh, or stored (4°C, 0.5‐24 weeks) in a HEPES‐buffered hypertonic salt solution. Electroejaculated, washed sperm (2‐4 × 106 sperm/ml) were preincubated for 1.0 h (38°C, 5% CO2 in air) and then co‐incubated (2 × 105 sperm/ml) with fresh or stored oocytes for 6.0 h. Gametes were incubated in a protein‐free, modified Tyrode's solution (TLP‐PVA) or in the same medium containing 4.0 mg/ml bovine serum albumin (BSA; TALP‐PVA). Treatments were compared for percentage ZP penetration (defined as sperm heads reaching more than halfway through the ZP) as an index of sperm capacitation. In both the domestic cat and leopard cat, there was no difference (P > 0.05) in sperm penetration of fresh ZP (domestic cat, 42.5 ± 5.4%; leopard cat, 38.6 ± 2.8%) or stored ZP (domestic cat, 32.4 ± 4.2%; leopard cat, 27.6 ± 2.3%). Sperm incubated in protein‐free medium (TLP‐PVA) were less capable (P<0.05) of ZP penetration (domestic cat, 14.6 ± 5.9%; leopard cat, 7.9 ± 3.0%) than sperm incubated in medium TALP‐PVA containing BSA (domestic cat, 60.3 ± 5.9%; leopard cat, 58.4 ± 3.0%). These data indicate that (1) albumin facilitates capacitation and ZP penetrating ability of cat spermatozoa; (2) domestic cat ZP appear to lack a block to heterospecific penetration by “foreign” (leopard cat) sperm; and (3) penetration of stored domestic cat ZP can be used as an index of sperm capacitation in the domestic cat and the leopard cat.
Changes in protein synthesis pattern during in vitro maturation of goat oocytes
Authors: Le Gal F. , Gall L. , De Smedt V. 
Published: February 2005

AbstractThe regulation of meiotic events of goat oocytes from prophase I to metaphase II was studied by inhibiting protein synthesis at different times of the transition and by analyzing the changes in the protein synthesis pattern during maturation. Protein synthesis was required for germinal vesicle breakdown (GVBD). Nevertheless, the concomitant event to the rupture of germinal vesicle, i.e., chromosome condensation, took place even in a cycloheximide‐containing medium. The transition from metaphase I to metaphase II was also protein synthesis dependent as evidenced by experiments using this protein synthesis inhibitor. The inhibition was partly reversible, i.e., after removal of the drug, oocytes were able to progress until metaphase I but could not proceed beyond this stage. Changes in the protein synthesis pattern were studied by radiolabelling of oocytes with [35S]methionine. These changes were correlated with the nuclear status of the oocyte: At GVBD, a polypeptide of 25 kD disappeared, while one of 27 kD appeared. At the same time, a polypeptide of 33 kD appeared, whereas concomitantly one of 34 kD became barely detectable and finally disappeared as the maturation progressed. During maturation, the synthesis of a 67 kD polypeptide increased and became predominant at the end of the maturation process. The synthesis of actin decreased after 18 hr of culture from a very high to a low level of synthesis. © 1992 Wiley‐Liss, Inc.
Assessment of Pisum sativum agglutinin in identifying acrosomal damage in stallion spermatozoa
Authors: Farlin M. E. , Jasko D. J. , Graham J. K. , Squires E. L. 
Published: February 2005

AbstractThe use of fluorescein‐conjugated Pisum sativum agglutinin (FITC‐PSA) was evaluated for its ability to distinguish acrosome‐intact from acrosome‐damaged stallion spermatozoa. Incubation of fresh (acrosomeintact) and frozen‐thawed (acrosome‐damaged) spermatozoa with FITC‐PSA resulted in acrosome‐intact spermatozoa that exhibited no fluorescence, while acrosome‐damaged spermatozoa exhibited fluorescent staining over the rostral portion of the head and equatorial segment. Experiments using mixtures of various ratios of acrosome‐intact and acrosome‐damaged spermatozoa determined the precision (intrasample coefficient of variation), and linearity (increased percentage of spermatozoa with PSA binding, with increased percentage of frozenthawed spermatozoa in a sample) of FITC‐PSA binding. The binding of FITC‐PSA increased in samples as the portion of frozen‐thawed (acrosome‐damaged) to fresh (acrosomeintact) spermatozoa increased. A positive correlation existed (r = 0.98, P < 0.05) between the percentage of FITC‐PSA bound sperm and the proportion of damaged spermatozoa added to a sample. Location of PSA lectin binding on acrosome‐damaged spermatozoa, determined by electron microscopy using gold‐conjugated PSA, was to components of the outer acrosomal membrane and acrosomal matrix. These results demonstrate that FITC‐PSA binding may be useful in determining acrosomal integrity of fresh and frozen‐thawed stallion spermatozoa. © 1992 Wiley‐Liss, Inc.
Release of tissue‐type plasminogen activator by activated rat eggs and its possible role in the zona reaction
Authors: Zhang X. , Rutledge J. , Khamsi F. , Armstrong D. T. 
Published: February 2005

AbstractThe resumption of meiosis results in synthesis of tissue‐type plasminogen activator (tPA) in the rat and mouse oocytes (Haurte et al., Cell 43:551–558, 1985). The present study demonstrates that freshly ovulated rat oocytes released their tPA into the surrounding medium upon in vitro activation by sperm penetration or treatment with a calcium ionophore. The presence of a neutralizing monoclonal anti‐tPA antibody during in vitro activation by the calcium ionophore inhibited the activation‐induced zona hardening and also preserved the ability of the oocyte to be penetrated by sperm subsequent to activation. Rat oocytes undergo zona hardening during in vitro maturation in the absence of serum, presumably as a result of spontaneous cortical granule release, based on findings in mice and hamsters. In the present study, the anti‐tPA antibody prevented the zona hardening and enhanced partition by spermatozoa of rat oocytes that were matured in vitro without serum. Collectively, the observations reported here suggest a possible role of tPA released during the cortical granule reaction in the zona reaction, which contributes to the block to polyspermy.
The role of TGF‐βs in mammalian development and neoplasia
Authors: Akhurst Rosemary J. , Fitzpatrick David R. , Fowlis Deborah J. , Gatherer Derek , Millan Fergus A. , Slager Hans 
Published: February 2005

AbstractTo date, three mammalian TGF‐β isoforms have been identified, each encoded by different genetic loci. Through each is very similar in primary amino acid structure, there are clear differences both in the mature bioactive peptide region and in the latency‐associated peptide, which could potentially confer differential biological specificity.As one route to investigate differential biological function in vivo we have used gene specific probes for in situ hybridization studies to examine the distribution of RNA transcripts during mammalian embryogenesis. Mouse embryos from 6 to 14.5 gestational age and human embryos from 32 to 57 days post‐fertilization have been probed. A general conclusion from these studies is that each TGFβ gene has a distinct, through overlapping, pattern of transcript distribution and that this pattern, in most cases, is conserved between mouse and man. We have focused on the biological function the TGF‐betas play in certain epithelia and in cardiogenesis, which will be discussed in this presentation. © 1992 Wiley‐Liss, Inc.
The role of growth factors in embryonic induction in Xenopus laevis
Authors: Dawid Igor B. , Taira Masanori , Good Peter J. , Rebagliati Michael R. 
Published: February 2005

AbstractEstablishment of the body pattern in all animals, and especially in vertebrate embryos, depends on cell interactions. During the cleavage and blastula stages in amphibians, signal(s) from the vegetal region induce the equatorial region to become mesoderm. Two types of peptide growth factors have been shown by explant culture experiments to be active in mesoderm induction. First, there are several isoforms of fibroblast growth factor (FGF), including aFGF, bFGF, and hst/kFGF. FGF induces ventral, but not the most dorsal, levels of mesodermal tissue; bFGF and its mRNA, and an FGF receptor and its mRNA, are present in the embryo. Thus, FGF probably has a role in mesoderm induction, but is unlikely to be the sole inducing agent in vivo. Second, members of the transforming growth factor‐β (TGF‐β) family. TGF‐β2 and TGF‐β3 are active in induction, but the most powerful inducing factors are the distant relatives of TGF‐β named activin A and activin B, which are capable of inducing all types of mesoderm. An important question relates to the establishment of polarity during the induction of mesoderm. While all regions of the animal hemisphere of frog embryos are competent to respond to activins by mesoderm differentiation, only explants that include cells close to the equator form structures with some organization along dorsoventral and anteroposterior axes. These observations suggest that cells in the blastula animal hemisphere are already polarized to some extent, although inducers are required to make this polarity explicit.How do inducing factors affect the differentiation of the responsive tissue? One approach to this question has been to look for gene expression in response to induction, especially the activation of regulatory loci like homeobox genes. Several homeobox‐containing genes including Mix.1, Xhox3, X1Hbox1, and X1Hbox6, goosecoid and members of a new class of genes named Xlim, are activated by inducing factors with different patterns of expression in the embryo. Differential expression of regulatory genes probably controls the formation of distinct tissues in an orderly pattern during embryogenesis. © 1992 Wiley‐Liss, Inc.
The bone morphogenetic protein family and osteogenesis
Authors: Wozney John M. 
Published: February 2005

AbstractThe BMPs (bone morphogenetic proteins) are a group of related proteins originally identified by their presence in bone‐inductive extracts of demineralized bone. By molecular cloning, at least six related members of this family have been identified and are called BMP‐2 through BMP‐7. These molecules are part of the TGF‐beta superfamily, based on primary amino acid sequence homology, including the absolute conservation of seven cysteine residues between the TGF‐betas and the BMPs. The BMPs can be divided into subgroups with BMP‐2 and BMP‐4 being 92% identical, and BMP‐5, BMP‐6, and BMP‐7 being an average of about 90% identical. To examine the individual activities of these molecules, we are producing each BMP in a mammalian expression system. In this system, each BMP is synthesized as a precursor peptide, which is glycosylated, processed to the mature peptide, and secreted as a homodimer. These reagents have been used to demonstrate that single molecules, such as BMP‐2, are capable of inducing the formation of new cartilage and bone when implanted ectopically in a rodent assay system. Whether each of the BMPs possesses the same inductive activities in an animal is the subject of ongoing research. Based on the chondrogenic and osteogenic abilities of the BMPs in the adult animal, the expression of the mRNAs for the BMPs has been examined in the development of the embryonic skeleton by in situ hybridization. These studies demonstrate that the BMP mRNAs are spatially and temporally expressed appropriately for the proteins involved in the induction and development of cartilage and bone in the embryonic limb bud. Furthermore, primary preparations of limb bud cells respond to BMP‐2, as do several cell lines of the osteoblastic lineage. In addition to expression in the skeletal system, various of the BMP mRNAs are expressed in distinct tissues, suggesting additional roles during development. © 1992 Wiley‐Liss, Inc.