bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fertilization envelope in diapause eggs of Pontella mediterranea (crustacea, copepoda)
Authors: Santella L. , Ianora A. 
Published: February 2005

AbstractThe sequence and timing of morphological changes during envelope formation was followed in diapause eggs of Pontella mediterranea (Crustacea, Copepoda). The multilayer coat enveloping these eggs resulted from the exocytosis of 4 types of cortical vesicles that sequentially released their contents in the perivitelline space. These included small high‐density vesicles (hDV) with electron‐dense material, vesicles (V) with dense ring granules and a uniform matrix contained within the same compartment, large high‐density (HDV) vesicles, and large moderately dense (MDV) vesicles. All of these cortical vesicles were present in newly spawned, fertilized eggs. Their exocytosis resulted from egg activation. One of these cortical vesicles (V) was similar in morphology to the intracisternal granules precursors of endogenous yolk. Intracisternal granules, characteristic of previtellogenic oocytes of many crustaceans, were present in previtellogenic oocytes of P. mediterranea but disappeared in later stages of oocyte development once yolk formation was completed. We discuss the role of cortical vesicles in the formation of the complex extracellar coat enveloping copepod diapause eggs. © 1992 Wiley‐Liss, Inc.
Immunological evidence for a P2 protamine precursor in mature rat sperm
Authors: Stanker Larry H. , McKeown Cathy , Balhorn Rod , Lee Catherine , Mazrimas Joe , Goralka Michael , Wyrobek Andy 
Published: February 2005

AbstractHigh molecular weight proteins in Rattus norvegicus that are immunoreactive with an antiprotamine 2 specific antibody but not with an anti‐protamine 1 specific antibody are described. These proteins were detected by coupling high‐performance liquid chromatography (HPLC) with an enzyme‐linked immunosorbent assay (ELISA). Briefly, following HPLC separation of rat sperm nuclear proteins, the HPLC fractions were probed with the antibodies. We estimate that the antibody probes are 100–1000 times more sensitive than UV absorbance measurements. Immunoblot analysis following acid‐urea electrophoretic separation of rat sperm nuclear proteins, and of the HPLC fractions, also detected putatie protamine 2 precursor proteins. The proteins reactive with the anti‐protamine 2 antibody are most likely not mature protamine 2, since they were detected in a region of the chromatogram where we would not expect protamine 2 to migrate based on the chromatographic locations of human and mouse protamine 2. Likewise, the immunoblotting experiments demonstrated that the anti‐protamine 2 antibody recognized proteins with slower electrophoretic mobilities than would be expected for a mature protamine 2. An anti‐protamine 1 monoclonal antibody, Hup1 N, that binds rat protamine 1 is also described. Hup 1 N allowed for identification of the HPlc fractions that contained rat protamine 1. Finally, we demonstrated that Hup 1 N binds protamine 1 from a large number of species, suggesting a conserved epitope for Hup 1 N. © 1992 Wiley‐Liss, Inc.
Molecular cloning of a novel mRNA sequence expressed in cleavage stage mouse embryos
Authors: Miyamoto Hiroshi , Matsushiro Aizo , Nozaki Masami 
Published: February 2005

AbstractIn an approach to study genes transcribed during early mouse development, a cDNA library was constructed from poly(A) RNA isolated from the 8‐cell morula. The cDNA library was differentially screened with labelled cDNA probes synthesized on poly(A) RNA isolated from the 8‐cell morula or unfertilized eggs. Six clones which increased in abundance in the 8‐cell morula were selected and further analyzed. Sequencing analyses showed that some of these clones corresponded to RNA transcripts from B1 and B2 repetitive sequences, as well as mRNA for cytochrome C oxidase I and NADH dehydrogenase III derived from the mitochondrial genome. One clone was not identical to any known sequences. The unidentified sequence (M025) was found at low levels in the unfertilized egg, but increased at the 2‐cell stage. The predicted amino acid sequence revealed that the M025 gene may encode a Ca2+ binding protein. © 1993 Wiley‐Liss, Inc.
Human male infertility may be due to a decrease of the protamine P2 content in sperm chromatin
Authors: Belokopytova Irina A. , Kostyleva Elena I. , Tomilin Alexey N. , Vorob'ev Vladimir I. 
Published: February 2005

AbstractBasic chromosomal proteins were extracted from the sperm of fertile and infertile human males. The relative proportions of protamine 1, 2, and 3 were determined by scanning microdensitometry following electrophoresis of total protamine in polyacrilamide gels. The findings were as follows: (1) The proportion of protamine P(2 + 3) in sperm obtained from infertile males was lower than that in fertile males. (2) Protamine P(2 + 3) in infertile human males showed reduced affinity to DNA. The possibility that some cases of human male infertility may be due to mutation within the protamine P2 gene is discussed. © 1993 Wiley‐Liss, Inc.
Mechanistic studies of the plasma membrane block to polyspermy in mouse eggs
Authors: Horvath Peter M. , Kellom Theresa , Caulfield Jeanne , Boldt Jeffrey 
Published: February 2005

AbstractThe mechanisms responsible for the plasma membrane associated block to polyspermy in mouse eggs were studied. Reinsemination experiments using zona‐free eggs indicated that, after fertilization, the egg plasma membrane is altered such that sperm binding to the egg plasma membrane is blocked, except in the region of the second polar body. Activation of the egg with either ethanol or strontium chloride did not result in a block to polyspermic penetration, as artificially activated eggs displayed identical penetration levels as to nonactivated control eggs. The penetrability of activated eggs was not altered by the presence or absence of the zona pellucida during activation. Lectin staining for egg cortical granule material indicated that activation did cause cortical granule exocytosis; however, activated eggs remained penetrable. These data support the following conclusions: (1) an alteration in the ability of the egg plasma membrane to allow sperm adherence accounts for the block to polyspermy; (2) establishment of the plasma membrane block to polyspermy is sperm dependent, since artificial egg activation does not result in a block response; (3) the contents of the egg's cortical granules do not play a role in the establishment of the plasmalemma block response. © 1993 Wiley‐Liss, Inc.
Evidence of new antigens in the mouse cumulus oophorus during preovulatory cumulus expansion
Authors: Amiel M.‐L. , Moos J. , Tesarik J. , Testart J. 
Published: February 2005

AbstractThe effects of an antiserum (anti‐COC) against ovulated mouse cumulus‐oocyte complexes (COC) on in vitro fertilization of mouse oocytes were studied. Preincubation of ovulated COC with various concentrations of anti‐COC led to dose‐dependent impairment of fertilization rates as well as to a decrease in the number of spermatozoa attached to the zona pellucida. Anti‐COC was used to probe Western blots of cumulus proteins. These cumuli were obtained from 2 experimental groups of mice corresponding to 2 different maturational stages (preovulatory immature COC or preovulatory mature COC). Two antigens (70 and 80 kDa) present in cumulus intercellular matrix from mature COC were only found as traces in matrix from immature COC. In addition, the protein pattern of the cumulus intercellular matrix was different from that of cumulus cells, whatever the COC maturational stage. These results indicate the appearance of new proteins in the cumulus oophorus during preovulatory expansion and are consistent with the contraceptive action of anti‐COC. © 1993 Wiley‐Liss, Inc.
Cloning and sequencing of baboon and cynomolgus monkey intraacrosomal protein SP‐10: Homology with human SP‐10 and a mouse sperm antigen (MSA‐63)
Authors: Freemerman Alex J. , Wright Richard M. , Flickinger Charles J. , Herr John C. 
Published: February 2005

AbstractIn this study, cDNAs encoding the intraacrosomal protein SP‐10 were cloned and sequenced from baboon (Papio papio) and macaque (Macaca fasicularis) testis libraries and the sequence compared to that of human SP‐10. Two alternatively spliced SP‐10 cDNAs were obtained from both baboon and macaque testis libraries. The two cDNAs in each species contained open reading frames encoding proteins of exactly 285 and 251 amino acids. A 98% homology between baboon and macaque SP‐10 was found at the protein and DNA levels. An 85% and 89% homology between baboon and macaque SP‐10 and human SP‐10 was present at the protein and DNA level, respectively. A mouse intraacrosomal protein, MSA‐63, considered to be an SP‐10 homologue, exhibited an overall 53% homology to nonhuman primate SP‐10 and a 60% homology to human SP‐10 at the protein level. Polymerase chain reaction analysis of testis mRNA confirmed the existence of two alternately spliced SP‐10 mRNAs in both nonhuman primates. Primer extension analysis indicated a common major transcriptional start site in baboon, macaque, and human SP‐10 67 nucleotides 5′ to the ATG codon. The amino acid sequence data for nonhuman primate SP‐10s suggest that antibodies generated by vaccinating baboons and macaques with human SP‐10 will likely recognize nonhuman primate SP‐10, supporting the testing of an SP‐10 contraceptive vaccine based on human SP‐10 in these nonhuman primate models. © 1993 Wiley‐Liss, Inc.
Differential sensitivity of progesterone‐ and zona pellucida‐induced acrosome reactions to pertussis toxin
Authors: Tesarik Jan , Carreras Alfonso , Mendoza Carmen 
Published: February 2005

AbstractPertussis toxin‐sensitive guanine nucleotide‐binding regulatory proteins (G proteins) have previously been shown to mediate the zona pellucida‐induced acrosome reaction in mammalian sperm. In this study we compared the inhibitory effect of pertussis toxin on the zona‐induced acrosome reaction in human spermatozoa with that on the reaction induced by progesterone, another physiological acrosome reaction‐promoting stimulus associated with the ovulated oocyte. Up to the concentration of 1 μg/ml, pertussis toxin did not produce any direct effects on the acrosome reaction frequency nor did it influence sperm movement and viability. However, preincubation of spermatozoa with the toxin at a concentration of 100 ng/ml completely abolished the increase in the acrosome reaction frequency upon subsequent exposure to solubilized zona pellucida material. In contrast, the same treatment did not impair the ability of spermatozoa to initiate the acrosome reaction in response to progesterone. Moreover, the preincubation with pertussis toxin did not modify the changes in the intracellular concentration of calcium ions occurring after progesterone addition. These data suggest that different physiological stimuli may utilize different signal transduction pathways to induce the human sperm acrosome reaction. © 1993 Wiley‐Liss, Inc.
Cellular localization of the mRNAs of the somatic and testis‐specific cytochromes c during spermatogenesis in the rat
Authors: Morales Carlos R. , Hake Laura E. , Hecht Norman B. 
Published: February 2005

AbstractDuring mammalian spermatogenesis, two forms of cytochromes c, cytochromes cs and ct, are present in male germ cells. During meiosis, cytochrome ctbegins to replace cytochrome cs. At least four size classes of cytochrome cs mRNA are expressed in all somatic cells and in early stages of male germ cells. In addition, a cytochrome cs transcript of 1.7 kB has been detected in rodent testes and is abundant in post meiotic male germ cells. Here we utilize “in situ” hybridization to define the cellular sites where the four ubiquitous cytochrome cstranscripts, the 1.7 kB cytochrome cs transcripts and the testis‐specific cytochrome ct transcripts are expressed in the rat. Low levels of cytochrome cs mRNAs are detected in Leydig cells, myoepithelial cells, Sertoli cells, all types of spermatogonia, and during meiotic prophase. The 1.7 kB cytochrome cs mRNA is first detected in late stages of meiotic prophase and reaches its highest levels in steps 1 to 9 spermatids. No cytochrome cs mRNAs are detected in spermatids between steps 10 to 19. Low levels of cytochrome ct mRNAs, initially detected in zygotene spermatocytes, reach maximal levels in round spermatids. For all three probes the majority of the silver grains are localized randomly throughout the cytoplasm, suggesting that neither the translating nor non‐translating (the 1.7 kB mRNA) forms of cytochrome cs mRNA nor the cytochrome ct mRNAs are sequestered during spermatogenesis. The absence of cytochrome cs or ct mRNAs in steps 10–19 spermatids suggest that the cytochrome ct protein does not turn over rapidly in late stage male germ cells. © 1993 Wiley‐Liss, Inc.
Histone H1 kinase activity in bovine oocytes following calcium stimulation
Authors: Collas Philippe , Sullivan Eddie J. , Barnes Frank L. 
Published: February 2005

AbstractThe influence of number of Ca2+ stimulations on the profile of histone H1 kinase activity in bovine oocytes was investigated. A Ca2+ stimulation consisted of transferring oocytes directly from culture medium to mannitol containing 100 μM Ca2+ and pulsing oocytes with a 0.2 kVcm−1, 20 μsec discharge. One, three, or six Ca2+ stimulations were given, each 22 min apart. Oocytes were frozen from 0 to 8 hr after the first stimulation at indicated time points and assayed for histone H1 kinase activity. H1 kinase activity was quantified using a densitometer and expressed as a percent of activity in nonpulsed metaphase II oocytes. Stimulating oocytes in the absence of Ca2+ in the pulsing medium did not inactivate H1 kinase. In the presence of Ca2+, however, H1 kinase was rapidly inactivated after stimulation. A single stimulation decreased H1 kinase activity to 44% ± 11% of its initial level in 1 hr. However, H1 kinase was dramatically reactivated at 2 hr after the stimulation and reached 122% ± 22% of the initial activity at 6 hr. With three stimulations, basal H1 kinase activity was 21% ± 3% and was obtained in 30 min. H1 kinase reactivation started at 4 hr after the first stimulation and level of activity reached 38% ± 15% at 8 hr. Six stimulations also led to rapid H1 kinase inactivation and to a basal activity of 14% ± 0.4%. With six stimulations, however, basal H1 kinase activity was maintained over at least 8 hr, and no reactivation occurred during this period. Basal H1 kinase activity obtained after six stimulations was similar to that of fertilized oocytes. Immunoprecipitation of p34cdc2 with an anti‐cdc2 antibody strongly suggested an identity between histone H1 kinase and maturation‐promoting factor. The data indicate that histone H1 kinase activity in oocytes could be regulated by the number of Ca2+ stimulations. A single Ca2+ stimulation led to H1 kinase inactivation, followed by reactivation of the kinase. Increasing the number of Ca2+ stimulations delayed the onset and reduced the extent of H1 kinase reactivation in the first parthenogenetic cell cycle. © 1993 Wiley‐Liss, Inc.
Differential expression of activation‐induced cytidine deaminase (AID) in nodular lymphocyte‐predominant and classical Hodgkin lymphoma
Authors: Greiner Axel , Tobollik Stephanie , Buettner Maike , Jungnickel Berit , Herrmann Kathrin , Kremmer Elisabeth , Niedobitek Gerald 
Published: February 2005

AbstractActivation‐induced cytidine deaminase (AID) is indispensable for class switch recombination and somatic hypermutation of immunoglobulin genes. Expression of AID has been detected in germinal centre centroblasts and in lymphomas derived from germinal centre cells. However, in situ studies of AID expression have until now been hampered by a lack of antibodies suitable for immunohistochemistry. To overcome this problem, an AID‐specific monoclonal antibody suitable for immunohistochemical staining of formalin‐fixed, paraffin wax‐embedded tissue sections has been generated. This antibody was shown to detect AID expression in normal germinal centre B‐cells as well as in non‐Hodgkin lymphomas with a putative germinal centre origin. Using this antibody, a virtually exclusive cytoplasmic localization of AID in normal and neoplastic B‐cells is shown. Employing a combination of immunohistochemistry and AID‐specific in situ hybridization, it is demonstrated that AID is consistently expressed in the neoplastic cells of nodular lymphocyte‐predominant Hodgkin lymphoma (HLnlp) but only infrequently in classical HL (cHL). This is in keeping with the notion that tumour cells of HLnlp represent transformed germinal centre B‐cells showing evidence of somatic hypermutation. AID represents an additional marker useful in the differential diagnosis of HLnlp and cHL. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Wavelet‐accelerated Monte Carlo sampling of polymer chains
Authors: Ismail Ahmed E. , Stephanopoulos George , Rutledge Gregory C. 
Published: February 2005

AbstractWe introduce a new method for coarse‐graining polymer chains, based on the wavelet transform, a multiresolution data analysis technique. This method, which assigns a cluster of particles to a coarse‐grained bead located at the center of mass of the cluster, reduces the complexity of the problem significantly by dividing the simulation into several stages, each with a small fraction of the number of beads in the overall chain. At each stage, we compute the distributions of coarse‐grained internal coordinates as well as potential functions required for subsequent simulation stages. We show that, with this wavelet‐accelerated Monte Carlo method, coarse‐grained Gaussian and self‐avoiding random walks can reproduce results obtained from atomistic simulations to a high degree of accuracy in orders of magnitude less time. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 897–910, 2005
Aspects of holography in the AdS/CFT correspondence
Authors: Sieg C. 
Published: February 2005

AbstractWe study quantities which are important for the realization of the holographic principle in the AdS/CFT correspondence: boundaries, geodesics and the propagators of scalar fields. They should play a role in the holographic setup in the BMN limit as well. We review the backgrounds and their relations that are relevant in the AdS/CFT correspondence and in its BMN limit. We describe the realization of the holographic principle in the AdS/CFT correspondence and summarize proposals of how to translate it in the BMN limit. We analyze the boundaries, geodesics and propagators of scalar fields in detail and observe how they behave in the limiting process from AdS5×S5to the 10‐dimensional plane wave, which is the spacetime in the BMN limit.
Characterization of deep levels in n‐GaN by combined capacitance transient techniques
Authors: Py M. A. , Zellweger Ch. , Wagner V. , Carlin J.‐F. , Buehlmann H.‐J. , Ilegems M. 
Published: February 2005

AbstractDeep centers in undoped n‐GaN grown by Hydride Vapor Phase Epitaxy were characterized by Deep Level Transient Spectroscopy (DLTS), revealing four known levels with activation energies in the range 0.17–0.94 eV. Deeper levels in the bandgap were observed by photocapacitance (PHCAP) experiments. A correspondence can be established for the dominant DLTS level observed both by thermal and optical experiments, exploiting the temperature as a key parameter in PHCAP measurements. The Franck–Condon shift dF–C for this level was estimated around 0.33 eV, in close agreement with results obtained by Hacke and coworkers in a more elaborate way. The tentative assignment of most levels is discussed on the basis of literature, pointing out unsettled origins for some of them. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Terahertz investigation of high quality indium nitride epitaxial layers
Authors: Meziani Y. M. , Maleyre B. , Sadowski M. L. , Ruffenach S. , Briot O. , Knap W. 
Published: February 2005

AbstractWe report on the optical characterization of InN layers in the THz range and magnetic fields up to 13 T. The results are interpreted using the dielectric function formalism, with contributions of cyclotron resonance, phonons, plasmons and helicon wave excitations. We show how THz radiation transmission measurements can provide an optical contactless method of determining the quality (carrier density and momentum scattering rate) in the InN layers. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electron transport properties of AlGaAs/GaAs heterostructure containing a d‐doping in the quantum well
Authors: Rekaya S. , Bouzaïene L. , Sfaxi L. , Hjiri M. , Contreras S. , Robert J. L. , Maaref H. 
Published: February 2005

AbstractElectronic properties of the Si δ‐doped AlGaAs/GaAs heterostructure such as the electron density and electron mobility have been studied when the Al concentration in the vicinity to the silicon (xAl(Si)) is varied. Shubnikov–de Haas and quantum Hall effect measurements at 4.2 K have been carried out to investigate the existence of a quasi‐two‐dimensional electron gas (2DEG) in such structures. We have studied the effects of the Al concentration xAl(Si) on the electronic properties. Results show an improvement of the electron transport properties when xAl(Si) decreases. But as far as the electron mobility is concerned, a slight difference between the theoretical and experimental values was observed. The value of interface charge density (NBI) is necessary to explain the experimental mobility at low temperature. For NBI ≈ 6 × 109 cm–2, we have obtained a good agreement between the theoretical and experimental electron mobility. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Donor ionization energy in bulk GaAs for different donor concentrations and magnetic fields
Authors: Bisotto I. , Jouault B. , Raymond A. , Zawadzki W. , Strasser G. 
Published: February 2005

AbstractWe present the analysis of magnetotransport measurements of n‐type GaAs samples grown by MBE technique. The samples cover a wide range of donor concentrations, from 4.0 × 1014 cm–3 to 3.0 × 1016 cm–3. Experiments were performed for a wide range of temperatures and magnetic fields. The apparition of a magnetic freeze‐out for conduction electrons allows us to extract the binding energy of donors as a function of the magnetic field as well as the impurity concentration. The measured binding energies decrease as the doping level increases. This behavior is due to the overlap of the wavefunctions of neighbouring impurities which results in the formation of an impurity band. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic field effects on the near field spectra of quantum dots
Authors: Zora Anna , Simserides Constantinos , Triberis Georgios 
Published: February 2005

AbstractWe theoretically investigate the linear near field absorption spectra of semiconductor quantum dots under magnetic field of variable orientation. We examine if the application of the magnetic field alone is sufficient to cause – increasing the spot illuminated by the near field probe – “unexpected” features to the absorption spectra. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)