bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of single‐layered multiconductor transmission lines using the Fourier transform and mode‐matching techniques
Authors: Park Hyun H. , Kwon Jong‐Hwa , Lee Jae W. , Eom Hyo J. 
Published: January 2003

AbstractThe Fourier transform and mode‐matching techniques are applied in the analysis of single‐layered multiconductor transmission lines with finite strip thickness. Based on a quasi‐static approach, the problem is formulated to obtain simultaneous equations for the modal coefficients of the potential distributions between transmission lines. Residue calculus is applied to represent the potential distributions in convergent series form. Analytical closed‐form expressions for the self and mutual capacitances are developed. Numerical computations are performed to compare the validity of the proposed with other published data. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 315–317, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10752
Wavelength‐tunable actively mode‐locked fiber‐ring laser using an F‐P LD as a modulator and a tunable comb filter
Authors: Zhao Chun‐Liu , Ma Ning , Yuan Shuzhong , Yang Shiquan , Kai Guiyun , Zhao Qida , Xiaoyi Dong 
Published: January 2003

AbstractA wavelength‐tunable actively mode‐locked erbium fiber ring laser is demonstrated using an F–P semiconductor as a modulator and a tunable comb filler. Continuous wavelength tuning is enlarged to 6 nm by successively choosing different cavity modes of the F–P LD and tuning the temperature of the LD. The ∼2‐GHz frequency pulse is generated with a side‐mode suppression ratio over 30 dB in the entire tuning range. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 318–320, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10753
Application of CAD load‐pull techniques in mixer design
Authors: Velazquez Arturo , Lazaro Antonio , Pradell Luis , Comeron Adolfo 
Published: January 2003

AbstractThis work describes the application of a commercial CAD software to implement load‐pull techniques in the design of microwave mixers. This method is used to generate conversion‐loss regions when a diode is pumped and operated as a mixer circuit. Emphasis is placed on the inclusion of image and out‐of‐band terminations to optimize the operating conditions required to obtain low conversion loss. An X‐band 5‐dB conversion‐loss mixer is designed and tested using this method. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 320–323, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10754
Spherical bodies present within the germinal vesicle of Podarcis sicula previtellogenic oocyte derive from the temporaneous inactivation of ribosomal genes
Authors: Loredana Ricchiari , Marina Prisco , Stefania Tammaro , Chiara Maria Motta , Isabella Pugliese , Piero Andreuccetti 
Published: January 2003

AbstractIn the present paper we have investigated the origin of the spherical bodies (SBs) present within the germinal vesicle of about 400 μm previtellogenic oocytes in the lizard Podarcis sicula. In particular, we have attempted to clarify whether they derive from the single, large nucleolus present in early diplotenic oocyte as a consequence of ribosomal gene inactivation. We have, therefore, experimentally induced a decrease in rRNA synthesis by injecting animals with D‐galactosamine or by exposing them to low temperatures. The investigations carried out have demonstrated that both treatments induce significant ultrastructural changes in the nucleolar apparatus and in particular fragmentation and the formation of SBs comparable to those observed in germinal vesicle under physiological conditions. These results indicate that the germinal vesicle of Podarcis sicula has a nucleolar apparatus that significantly changes its aspect according to its functional status and reveal that in this species, the time course of rRNA synthesis is peculiar with respect to any other vertebrate oocyte studies so far. Mol. Reprod. Dev. 64: 321–328, 2003. © 2003 Wiley‐Liss, Inc.
Ultrastructural modifications in bovine oocytes maintained in meiotic arrest in vitro using roscovitine or butyrolactone
Authors: Lonergan Patrick , Faerge Inger , Hyttel Poul Maddox , Boland Maurice , Fair Trudee 
Published: January 2003

AbstractButyrolactone‐I (BL‐I) and roscovitine (ROSC) are selective inhibitors of the cyclin‐dependent kinases, and both have been shown to reversibly inhibit meiotic resumption in cattle oocytes for 24 hr without having a negative affect on subsequent development to the blastocyst stage. The aim of the present study was to describe the morphological changes occurring in fully grown immature and in vitro matured bovine oocytes following exposure to either BL‐I or ROSC for 24 hr at concentrations known to be consistent with normal development. Immature bovine cumulus oocyte complexes, recovered from the ovaries of slaughtered heifers, were incubated for 24 hr in the presence of one of the inhibitors. They were then either fixed immediately and processed for transmission electron microscopy (TEM), or cultured for a further 24 hr in the absence of the inhibitor, in conditions permissive to maturation, and subsequently processed for TEM. A control group of oocytes were processed for TEM immediately upon recovery (0 hr) or following in vitro maturation (IVM) for 24 hr. In general, incubation with either inhibitor disrupted the integrity of the surrounding cumulus cells and affected their subsequent expansion during IVM. Within the oocyte cytoplasm, swelling of the mitochondrial cristae was immediately noticeable following meiotic inhibition in the presence of ROSC, while an increased population of pleomorphic mitochondria and mitochondria with electron lucent matrices following BL‐I treatment was not observed until after the subsequent IVM period. Both inhibitors caused degeneration of the cortical granules, effectively reducing the population, most noticeably following IVM. At the level of the nucleus, both inhibitory treatments caused convolution of the nuclear membrane, furthermore, aberrant structures were observed within the nucleoplasm of ROSC‐treated cumulus oocyte complexes (COCs). In conclusion, while it has been shown that inhibition of meiotic resumption using specific cdk inhibitors is possible and that such oocytes are capable of undergoing maturation, fertilization, and early embryo development, there is as yet no definitive proof that oocytes treated in this way can ultimately give rise to normal offspring. We have shown here that some modifications are induced in the oocytes at the ultrastructural level. Whether or not these modifications are compatible with normal gestation and the birth of a live calf remain to be elucidated. Mol. Reprod. Dev. 64: 369–378, 2003. © 2003 Wiley‐Liss, Inc.
Increase in macrophages in the testis of cathepsin a deficient mice suggests an important role for these cells in the interstitial space of this tissue
Authors: Korah Nadine , Smith Charles E. , D'Azzo Alessandra , El‐Alfy Mohammed , Hermo Louis 
Published: January 2003

AbstractCathepsin A (PPCA) is a lysosomal carboxypeptidase that functions as a protective protein for α‐neuraminidase and β‐galactosidase in a multienzyme complex. In the present study, the testes of PPCA −/− mice from 2 to 10 months of age were compared with those of their wild type counterparts. While germ and Sertoli cells appeared comparable in appearance and distribution, the mean profile area of seminiferous tubules showed a significant decrease between wild type and PPCA −/− mice, suggesting changes to the seminiferous tubules and their contents. In addition, macrophages in the interstitial space (IS) of PPCA −/− mice were large, spherical, and filled with pale lysosomes, unlike those seen in wild type mice, and a quantitative analysis of their frequency per unit area of IS in PPCA −/− mice revealed a significant increase compared to that of wild type mice; this was also the case for their mean profile area. Absence of mitotic figures, cycling cells, or degenerating figures in the IS suggests that the major recruitment of macrophages appears to be from the circulation. In the IS, Leydig cells also showed an accumulation of large pale lysosomes in PPCA −/− mice, and their frequency also increased significantly as compared to wild type mice. In the electron microscope, a close association of Leydig cell microvilli with the surface of macrophages was pronounced in PPCA −/− mice. Since macrophages and Leydig cells interact by secreting various factors between each other, and considering the fact that Leydig cells show an accumulation of large pale lysosomes in PPCA −/− mice, it is suggested that macrophages accumulate as a result of abnormalities occurring in Leydig cells. Taken together, the data on increase in frequency of macrophages suggests important functions for these cells in both wild type and PPCA −/− mice. Mol. Reprod. Dev. 64: 302–320, 2003. © 2003 Wiley‐Liss, Inc.
Expression of retinol‐binding protein and cellular retinol‐binding protein in the bovine ovary
Authors: Brown J. Alison , Eberhardt Dawn M. , Schrick F. Neal , Roberts Mary P. , Godkin James D. 
Published: January 2003

AbstractRetinol (vitamin A) is essential for reproduction, and retinoids have been suggested to play a role in ovarian steroidogenesis, oocyte maturation, and early embryonic development. Retinol is transported systemically and intercellularly by retinol‐binding protein (RBP). Within the cell, cellular retinol‐binding protein (CRBP) functions in retinol accumulation and metabolism. Since the actions of retinoids are mediated, in part, by retinoid‐binding proteins, the objective of this study was to investigate cell‐specific expression of RBP and CRBP in the bovine ovary. Immunocytochemical analysis (ICC) localized RBP to the thecal and granulosa cell layers of antral and preantral follicles with the most intense staining in the cells of large, healthy follicles. The tunica adventitia of arterial blood vessels also exhibited RBP staining. Immunostaining of CRBP was most intense in the granulosa cells of preantral follicles and present, but diminished, in thecal and granulosa cells of antral follicles. Within the corpus luteum, both proteins were observed in large luteal cells, but only RBP was observed in small luteal cells. Northern blot analysis demonstrated that thecal and granulosa cells from antral follicles and luteal tissue expressed RBP and CRBP mRNA. Synthesis and secretion of RBP by thecal cells, granulosa cells, and luteal cells were demonstrated by immune‐complex precipitation of radiolabeled RBP from the medium of cultured cells or explants, followed by SDS–PAGE and fluorography. Follicular fluid was collected from small (<5 mm) and large (8–14 mm) follicles, pooled according to follicular size, and analyzed for retinol, RBP, estradiol‐17β, and progesterone. Concentrations of retinol, RBP, and estradiol were greater in the fluid of large follicles. Results demonstrate retinoid‐binding protein expression by bovine ovaries and provide physical evidence that supports the concept that retinoids play a role in ovarian function. Mol. Reprod. Dev. 64: 261–269, 2003. © 2003 Wiley‐Liss, Inc.
Polychlorinated biphenyls affect gene expression in the rabbit preimplantation embryo
Authors: Kietz Silke , Fischer Bernd 
Published: January 2003

AbstractPolychlorinated biphenyls (PCBs) have been shown to be embryotoxic. The mechanism(s) of action is not clearly understood. The toxic effects could be either direct or indirect. Furthermore, PCB congeners vary in their toxic potential. They can be classified in coplanar PCBs binding to the transcription factor aryl hydrocarbon receptor (AhR), which induce subsequent changes in gene expression, and noncoplanar PCBs exhibiting AhR‐independent effects. In order to investigate possible mechanisms, 5 and 6 days old preimplantation rabbit embryos were exposed in vitro to low levels of coplanar (PCB 77, 126, and 169) or noncoplanar PCBs (PCB 28, 52, 101, 118, 138, 153, and 180). The PCB effects were studied by semiquantitative RT‐PCR analysis of AhR target genes (cytochrome P450 (CYP) 1A1, 1A2, UDP‐glucuronosyl transferase 1, glutathione S‐transferase π1 and aldehyde dehydrogenase) and dioxin‐responsive genes (IL 1β, PAI 2, Cox 2, TGFα, EGF, erbB 1–4, c‐fos, c‐jun, HSP 90, cyclophilin 40), and by differential display (DD) RT‐PCR. CYP 1B1 mRNA and AhR protein were localized by in situ hybridization and immunohistochemistry, respectively. From the AhR target genes studied only CYP 1B1, and cyclooxygenase 2 showed an increase in mRNA levels after coplanar and noncoplanar PCB. Interleukin 1β and plasminogen activator inhibitor 2 were downregulated. CYP 1B1 mRNA showed a stage specific inducibility at day 6, but not at day 5. By DD RT‐PCR we identified six new genes previously not reported to be regulated by PCBs. The mRNAs encoding the subunits 1, 2, 4, and 5 of the NADH ubiquinone oxidoreductase and β‐globin showed a decrease, whereas trichohyalin mRNA was increased after PCB exposure. Coplanar and noncoplanar PCB congeners elicited similar responses on the mRNA levels of the studied genes. Exposure to coplanar PCBs did not result in the AhR being translocated to the nucleus. Our results show that (i) PCBs induce changes in gene expression in rabbit day 5 and 6 preimplantation embryos and imply (ii) that the transcriptional changes observed were not mediated by the nuclear AhR. Mol. Reprod. Dev. 64: 251–260, 2003. © 2003 Wiley‐Liss, Inc.
Acquisition of transcriptional competence in the 1‐cell mouse embryo: Requirement for recruitment of maternal mRNAs
Authors: Aoki Fugaku , Hara Kentaro T. , Schultz Richard M. 
Published: January 2003

AbstractWe previously suggested that the transcriptional machinery is rate‐limiting for genome activation in the preimplantation mouse embryo (Aoki et al., 1997: Dev Biol 181:296‐307), suggesting that genome activation requires the synthesis of some proteins following fertilization. To test this hypothesis, transcriptional activity was measured in 1‐cell embryos in which protein synthesis was inhibited by cycloheximide from the time shortly after insemination. Transcription in both the male and female pronuclei, as assessed by BrUTP incorporation, was markedly inhibited when assayed 14 hr post‐insemination. This result suggested that newly synthesized proteins derived from maternally recruited mRNA, and not maternally derived proteins that were post‐translationally modified following fertilization/egg activation, were critical for the acquisition of transcriptional competence. To test this hypothesis, mobilization of maternally recruited mRNAs was inhibited by treating the embryos with 3′‐deoxyadenosine (3′‐dA), which prevents polyadenylation of mRNA. The results demonstrated that the transcriptional activity was markedly decreased in the embryos cultured with 2 mM 3′‐dA, whereas 3′‐deoxyguanosine had little inhibitory effect, and suggest that recruitment of maternal mRNAs is essential for acquisition of transcriptional competence. Mol. Reprod. Dev. 64: 270–274, 2003. © 2003 Wiley‐Liss, Inc.
Sperm mediated gene transfer in pig: Selection of donor boars and optimization of DNA uptake
Authors: Lavitrano Marialuisa , Forni Monica , Bacci Maria Laura , Di Stefano Carla , Varzi Vincenzo , Wang Hongjun , Seren Eraldo 
Published: January 2003

AbstractTransgenic animals are produced primarily by microinjecting exogenous DNA into the male pronuclei of a zygote. Microinjection is successful in mice but not efficient in farm animals, limiting its general utility. We have pursued an alternative technology for producing transgenic animals: Sperm Mediated Gene Transfer (SMGT). Based on our finding that sperm cells bind and internalize exogenous DNA, we used sperm as a vector for transmitting, not only their own DNA, but also, the exogenously‐introduced gene of interest to the zygote. SMGT is highly efficient (up to greater than 80%) and relatively inexpensive; it can be used in species refractory to microinjection, whenever reproduction is mediated by gametes. In this report, we describe the procedure for selection of sperm donors and optimization of DNA uptake that are the key steps for the successful outcome of SMGT. We found that the nominal parameters that boar sperm should possess to serve as a good vector for exogenous DNA are the quality of semen based on standard parameters used in conventional animal breeding programs (volume, concentration, presence of abnormal sperm cells, motility at time of collection, and high progressive motility after 2 hr) and the ability of the sperm cells to take up and internalize exogenous DNA. The results described provide significant advances in SMGT technology applied to pigs, so that transgenic pigs can be efficiently obtained. Mol. Reprod. Dev. 64: 284–291, 2003. © 2003 Wiley‐Liss, Inc.
Expression of growth hormone and its transcription factor, Pit‐1, in early bovine development
Authors: Joudrey E.M. , Lechniak D. , Petrik J. , King W.A. 
Published: January 2003

AbstractDuring bovine embryogenesis, bovine growth hormone (bGH) contributes to proliferation, differentiation, and modulation of embryo metabolism. Pituitary‐specific transcription factor‐1 (Pit‐1) is a transcription factor that binds to promoters of GH, prolactin (PRL), and thyroid‐stimulating hormone‐beta (TSHβ) encoding genes. A polymorphism in the fifth exon of the bGH gene resulting in a leucine (Leu) to valine (Val) substitution provides an Alu I restriction site when the Leu allele is present. To determine the onset of embryonic expression of the bGH gene, oocytes derived from ovaries homozygous for Leu alleles were fertilized in vitro with spermatozoa obtained from a Val homozygote. For each developmental stage examined, three separate pools of embryos composed of approximately 100 cell samples underwent RNA isolation, reverse transcription to cDNA, and amplification by nested PCR (nPCR). Bovine GH gene transcripts were identified at 2‐ to 4‐cell (n = 162), 8‐ to 16‐cell (n = 73), morulae (n = 51), and blastocyst (n = 15) stages. Likewise, transcripts for Pit‐1 were detected at 2‐cell (n = 125), 4‐cell (n = 114), 8‐cell (n = 56), 12‐to‐32‐cell (n = 32), morulae (n = 68), and blastocyst (n = 14) stages. After digestion with Alu1, bGH cDNA was genotyped by restriction fragment length polymorphism (RFLP) analysis. Bovine GH mRNA was present in all pools of stages examined. Both Leu and Val alleles (maternal and paternal) were only detected in pools of embryos that had reached 8‐ to 16‐cell stage. Results suggest that transcription of the bGH gene begins at the 8‐ to 16‐cell stage in bovine embryos, possibly under control of the transcription factor, Pit‐1, and that RFLP analysis of the bGH gene can be used to determine parental origin of transcripts in early embryonic development. Mol. Reprod. Dev. 64: 275–283, 2003. © 2003 Wiley‐Liss, Inc.
Cleavage stage porcine embryos may have differing developmental requirements for karyopherins α2 and α3
Authors: Cabot Ryan A. , Prather Randall S. 
Published: January 2003

AbstractNumerous cellular proteins are able to localize to the nucleus due to the fact that they possess a nuclear localization signal (NLS) in their amino acid sequence. Nuclear localization sequences recognized by the importin α/β heterodimer are found in cellular proteins capable of performing many diverse functions, ranging from chromatin remodeling to cell cycle regulation. Evidence has been presented that suggests individual importin α homologues are present at varying levels in different adult tissues. Other data have shown that specific subsets of NLSs found in different cellular proteins are recognized by individual importin α homologues with varying affinities. This evidence led us to hypothesize that due to the specific cargoes they carry, the mammalian embryo has different developmental requirements for individual importin α homologues. The results of the studies presented here indicate that importin α/β‐mediated import occurs throughout early cleavage in the porcine embryo, as determined by a reporter protein microinjection assay, and that multiple importin α homologues are present throughout early cleavage, as determined by immunocytochemical analysis. An RNA interference approach was used in an attempt to determine the developmental requirements for specific importin α homologues during early cleavage in the porcine embryo. Results from this study showed that fertilized porcine embryos injected with double stranded RNA (dsRNA) corresponding to the importin α homologue karyopherin α3 had significantly fewer nuclei following four days of culture than did embryos injected with dsRNA for another importin α homologue, karyopherin α2, or two control groups. This is the first report indicating that mammalian embryos may have differential developmental requirements for specific nuclear trafficking pathways. Mol. Reprod. Dev. 64: 292–301, 2003. © 2003 Wiley‐Liss, Inc.
Instability of crab vitellogenin and its immunological relatedness with mammalian atherogenic lipoproteins
Authors: Warrier Sudha R. , Subramoniam T. 
Published: January 2003

AbstractVitellogenesis is the process of accumulation of vitellogenin (Vg) in rapidly growing oocytes of oviparous animals and its' subsequent transformation into lipovitellin (Lv). Lipovitellin, which forms the major yolk protein, serves as a principal nutrient reserve for the developing embryo. In the present study, Vg and Lv were purified from the hemolymph and ovary, respectively of the crab Scylla serrata by gel filtration followed by preparative gel electrophoresis. It was observed that purified Vg, but not Lv, possessed an intrinsic protease activity with which it underwent autoproteolysis giving rise to several smaller proteins. Furthermore, urea‐mediated unfolding studies by UV‐spectral analysis revealed clearly that Vg was easily disrupted by urea whereas Lv was resistant. Taken together, these results suggest that although Lv had a stable conformation, its precursor Vg was labile and highly sensitive to degradation. Another aspect that was investigated in the present study was the immunological kinship of crab Vg and Lv to mammalian atherogenic lipoproteins, the low density lipoprotein (LDL), very low density lipoprotein (VLDL), and apolipoprotein B (apoB). By Western blot analysis, it was demonstrated that crab Vg and Lv were immunoreactive to antibodies to human LDL, VLDL, and apoB. These observations suggest the existence of common epitope recognition sites in crab Vg and mammalian lipid transferring proteins. This corroborates well with our earlier study on the recognition of crab Vg receptor by mammalian lipoproteins. Mol. Reprod. Dev. 64: 329–340, 2003. © 2003 Wiley‐Liss, Inc.