bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stage‐specific and tissue‐specific expression characteristics of differentially expressed genes during mouse spermatogenesis
Authors: Guo Rui , Yu Zuoren , Guan Jikui , Ge Yehua , Ma Jing , Li Sai , Wang Shali , Xue Shepu , Han Daishu 
Published: January 2004

AbstractSpermatogenesis occurs in successive mitotic, meiotic, and post‐meiotic phase, and involves a number of unique processes including meiosis and dramatic morphological changes. The unique differentiation mechanisms of spermatogenesis suggest the existence of germ‐cell‐specific molecules. The most straight forward strategy to elucidate differentiation mechanisms is to identify and characterize differentiation‐specific molecules and their associated genes in germ cells. However, only a few genes specifically involved in spermatogenesis have been studied. In the present study, six different types of spermatogenic cells (primitive type A spermatogonia, type B spermatogonia, preleptotene spermatocytes, pachytene spermatocytes, round spermatids, and elongating spermatids) were isolated from Balb/c mice testes using velocity sedimentation and Atlas cDNA arrays containing 1,176 known mouse genes were used to determine the gene expression profiles of the spermatogenic cells. The expression of 260 genes were detected in six different stages of spermatogenic cells and a number of genes showed differential expression. The 23 differentially expressed genes were further analysed by reverse transcription polymerase chain reaction (RT‐PCR) for their stage‐specific and tissue‐specific expression characteristics. Based on the results of RT‐PCR, six genes highly express in both primitive type A and type B spermatogonia, four genes up‐regulate in type B spermatogonia, two genes up‐regulate in spermatocytes, two genes up‐regulate in spermatids, three genes express constantly from primitive A spermatogonia to elongating spermatids, two genes express constantly from primitive A spermatogonia to round spermatids, two genes do not change in their expression during spermatogenesis, two genes can be detected highly in adult testis, but are undetectable in spermatogenic cells. The tissue‐specific expression characteristics of the 23 genes showed that some of them specifically expressed in testes or other tissues. These data provide new information for further studies into spermatogenesis‐related genes and may lead to the identification of genes with potential relevance to the differentiation of spermatogenic cells. In addition, some of these genes could be considered to be used as the molecular markers for different stages of spermatogenic cells. Mol. Reprod. Dev. 67: 264–272, 2004. © 2004 Wiley‐Liss, Inc.
Aromatase inhibitor induces complete sex change in the protogynous honeycomb grouper (Epinephelus merra)
Authors: Bhandari Ramji Kumar , Higa Mikihiko , Nakamura Shigeo , Nakamura Masaru 
Published: January 2004

AbstractThe protogynous hermaphrodite fish change sex from female to male at the certain stages of life cycle. The endocrine mechanisms involved in gonadal restructuring throughout protogynous sex change are not clearly understood. In the present study, we implanted maturing female honeycomb groupers with nonsteroidal aromatase inhibitor (AI), Fadrozole (0, 1, and 10 mg/fish) and examined changes in gonadal structures and serum levels of sex steroid hormones 2½ months after implantation. The ovaries of control females had oocytes undergoing active vitellogenesis, whereas AI caused females to develop into functional males. These males had testes, which were indistinguishable in structure from those of normal males, but bigger in size, and completed all stages of spermatogenesis including accumulation of large amount of sperm in the seminiferous tubules. AI significantly reduced the serum levels of estradiol‐17β (E2) and increased levels of testosterone (T), 11‐ketotestosterone (11‐KT), and 17α, 20β‐dihydroxy‐4‐pregnen‐3‐one (DHP). Further, AI suppressed in vitro production of E2, and stimulated the production of T and 11‐KT in the ovarian fragments of mature female. In the honeycomb grouper, suppression of both in vitro and in vivo production of E2 and degeneration of oocytes by AI suggests that AI induces complete sex change through inhibition of estrogen biosynthesis, and perhaps, subsequent induction of androgen function. Mol. Reprod. Dev. 67: 303–307, 2004. © 2004 Wiley‐Liss, Inc.
Rapid PKA‐catalysed phosphorylation of boar sperm proteins induced by the capacitating agent bicarbonate
Authors: Harrison R.A.P. 
Published: January 2004

AbstractIn boar spermatozoa, the capacitating agent bicarbonate has been shown to induce rapid changes both in plasma membrane lipid architecture and in motility; in each case, a PKA‐dependent pathway is involved. Early bicarbonate‐induced changes in protein phosphorylation were probed using a commercial antibody against the phosphorylated form of the consensus substrate site for cyclic AMP‐dependent protein kinase. The antibody detected relatively few bands in sperm extracts, of which only a small number showed incubation‐dependent changes. While the quantitative response varied between boar ejaculates, in general terms bicarbonate induced phosphorylation increases in bands of 96, 64, and 59 kDa within 80 sec. The changes reached a maximum after about 160 sec, declined somewhat thereafter, and then increased again slowly as incubation progressed further (up to 21 min). The bicarbonate‐induced increases were strongly dependent on the presence of BSA in the incubation medium. They were inhibited by H89 (PKA inhibitor) but not by GF (PKC inhibitor), and were enhanced by papaverine (phosphodiesterase inhibitor) and by calyculin (protein phosphatase inhibitor). The cyclic AMP analogue cBIMPS was able to mimic bicarbonate action though its effect was less dramatic. Stearated Ht31, a permeable inhibitor of PKA's binding to A‐kinase anchoring protein, did not affect either the intensity or the specificity of the bicarbonate‐induced phosphorylation changes, though it blocked motility entirely. Immunocytochemical studies revealed marked bicarbonate‐dependent phosphorylation changes in the post‐acrosomal region of the head and in the neck, midpiece, and anterior regions of the tail. Fractionation of stimulated spermatozoa showed that all bands detectable with the antibody were bound to heads and to midpieces and associated large tail fragments; no bands were detected in either small tail or membrane fragments or in the cytoplasmic fraction. Differential extraction of the midpiece/large tail fraction revealed two protein bands with closely similar electrophoretic mobilities to the 96‐ and 59‐kDa phosphorylated bands; MALDI‐TOF analyses of these bands revealed both to be members of the Odf2 family. Mol. Reprod. Dev. 67: 337–352, 2004. © 2004 Wiley‐Liss, Inc.
Enhancement of prostacyclin synthesis at the beginning of formation of caprine corpora lutea
Authors: Kawate Noritoshi , Tsuji Makoto , Tamada Hiromichi , Inaba Toshio , Sawada Tsutomu 
Published: January 2004

AbstractWe examined changes in the levels of prostacyclin (PGI2) synthase mRNA and 6‐keto‐PGF1α, a stable metabolite of PGI2, in the caprine corpus luteum (CL) during its development and subsequent maintenance. We also looked at the effects of a potent GnRH antagonist (GA), which is known to suppress the release of luteinizing hormone (LH), on the PGI2 synthase mRNA level and the 6‐keto‐PGF1α content during CL development. Goats were divided into a control group (n = 12) and a GA‐treated group (n = 6). They were treated with saline or GA (50 μg/kg, s.c.) on days 0 (day of ovulation), 4, and 8 (control only), and the CL were collected from a subset of goats (n = 3 for each day) on days 0 (no saline), 4, 8, or 14 (control only). Ribonuclease protection assay was performed to quantify the mRNA in the CL using specific cRNA probes generated by RT‐PCR and in vitro transcription. The 6‐keto‐PGF1α content in the CL was measured by radioimmunoassay. The level of PGI2 synthase mRNA and the 6‐keto‐PGF1α content in the CL in the control group decreased from day 0 to day 4 (P < 0.01), and did not change thereafter from day 4 to day 14. Levels of PGI2 synthase mRNA and 6‐keto‐PGF1α content in the CL on days 4 and 8 were not affected by treatment with GA. These results suggest that PGI2 synthesis is regulated upward at the beginning of caprine CL formation; this may play a role in initiating CL development. This study also suggests that changes of PGI2 synthesis during CL development are probably not regulated by LH. Mol. Reprod. Dev. 67: 308–312, 2004. © 2004 Wiley‐Liss, Inc.
Expression of mRNAs for DNA methyltransferases and methyl‐CpG‐binding proteins in the human female germ line, preimplantation embryos, and embryonic stem cells
Authors: Huntriss J. , Hinkins M. , Oliver B. , Harris S.E. , Beazley J.C. , Rutherford A.J. , Gosden R.G. , Lanzendorf S.E. , Picton H.M. 
Published: January 2004

AbstractRecent evidence indicates that mammalian gametogenesis and preimplantation development may be adversely affected by both assisted reproductive and stem cell technologies. Thus, a better understanding of the developmental regulation of the underlying epigenetic processes that include DNA methylation is required. We have, therefore, monitored the expression, by PCR, of the mRNAs of DNA methyltransferases (DNMTs), methyl‐CpG‐binding domain proteins (MBDs), and CpG binding protein (CGBP) in a developmental series of amplified cDNA samples derived from staged human ovarian follicles, oocytes, preimplantation embryos, human embryonic stem (hES) cells and in similar murine cDNA samples. Transcripts of these genes were detected in human ovarian follicles (DNMT3A, DNMT3b1, DNMT3b4, DNMT1, MDBs1–4, MeCP2, CGBP), germinal vesicle (GV) oocytes (DNMT3A, DNMT3b1, DNMT1, MDBs1–4, MeCP2, CGBP), mature oocytes (DNMT3A, DNMT3b1, DNMT1, CGBP), and preimplantation embryos (DNMT3A, DNMT3b1, DNMT1, DNMT3L, MBD2, MDB4, CGBP). Differential expression of DNMT3B gene transcripts in undifferentiated (DNMT3b1) and in vitro differentiated human ES cells (DNMT3b3) further demonstrated an association of the DNMT3b1 transcript variant with totipotent and pluripotent human cells. Significantly, whilst the murine Dnmt3L gene is both expressed and essential for imprint establishment during murine oogenesis, transcripts of the human DNMT3L gene were only detected after fertilisation. Therefore, the mechanisms and/or the timing of imprint establishment may differ in humans. Mol. Reprod. Dev. 67: 323–336, 2004. © 2004 Wiley‐Liss, Inc.
Minimal path broadcast networks
Authors: Farley Arthur M. 
Published: January 2004

AbstractBroadcasting is the communication process whereby a message that is initially known by one site becomes known to all sites of a network. Messages are transmitted by calls from senders to sets of receivers. In path broadcasting, a site can call nonneighboring sites over paths in the network. A call occupies all sites and edges on the path followed by the call; thus, any calls made concurrently must be vertex‐disjoint. We discuss the design of sparse networks that allow path broadcasting to be completed in minimum time under three different path broadcast models. © 2004 Wiley Periodicals, Inc.
An exact algorithm for the min‐cost network containment problem
Authors: Pesenti Raffaele , Rinaldi Franca , Ukovich Walter 
Published: January 2004

AbstractA network design problem which arises in the distribution of a public utility provided by several competitive suppliers is studied. The problem addressed is that of determining minimum‐cost (generalized) arc capacities in order to accommodate any demand between given source–sink pairs of nodes, where demands are assumed to fall within predetermined ranges. Feasible flows are initially considered as simply bounded by the usual arc capacity constraints. Then, more general linear constraints are introduced which may limit the weighted sum of the flows on some subsets of arcs. An exact cutting plane algorithm is presented for solving both of the above cases and some computational results are reported. © 2004 Wiley Periodicals, Inc.
The absolute center of a network
Authors: Dvir Dov , Handler Gabriel Y. 
Published: January 2004

AbstractThis paper presents a new algorithm for finding an absolute center (minimax criterion) of an undirected network with n nodes and m arcs based on the concept of minimum‐diameter trees. Local centers and their associated radii are identified by a monotonically increasing sequence of lower bounds on the radii. Computational efficiency is addressed in terms of worst‐case complexity and practical performance. The complexity of the algorithm is 0(n2 ℓg n + mn). In practice, because of its very rapid convergence, the algorithm renders the problem amenable even to manual solution for quite large networks, provided that the minimal‐distance matrix is given. Otherwise, evaluation of this matrix is the effective computational bottleneck. An interesting feature of the algorithm and its theoretical foundations is that it synthesizes and generalizes some well‐known results in this area, particularly Halpern's lower bound on the local radius of a network and properties of centers of tree networks. © 2004 Wiley Periodicals, Inc.
Open string fields and D‐branes
Authors: Rastelli L. 
Published: January 2004

AbstractThese lecture notes review some modern developments in open string field theory. We begin with a discussion of the physical motivations and general framework of open SFT. We then briefly introduce and contrast the two basic formalisms, Boundary SFT and cubic SFT, and summarize the main results about tachyon condensation obtained with both approaches. Next, we review the Vacuum SFT conjecture, according to which D‐brane solutions correspond to string fields that are projectors of Witten's *‐algebra. We describe the Boundary CFT technique to compute *‐products and construct projector solutions. We argue that VSFT accounts precisely for the expected moduli space of D‐branes.
On (orientifold of) type IIA on a compact Calabi‐Yau
Authors: Misra A. 
Published: January 2004

AbstractWe study the gauged sigma model and its mirror Landau‐Ginsburg model corresponding to type IIA on the Fermat degree‐24 hypersurface in WCP4[1,1,2,8,12] (whose blow‐up gives the smooth CY3(3,243)) away from the orbifold singularities, and its orientifold by a freely‐acting antiholomorphic involution. We derive the Picard‐Fuchs equation obeyed by the period integral as defined in [1, 2], of the parent 𝒩 = 2 type IIA theory of [3]. We obtain the Meijer's basis of solutions to the equation in the large and small complex structure limits (on the mirror Landau‐Ginsburg side) of the abovementioned Calabi‐Yau, and make some remarks about the monodromy properties associated based on [4], at the same and another MATHEMATICAlly interesting point. Based on a recently shown 𝒩 = 1 four‐dimensional triality [6] between Heterotic on the self‐mirror Calabi‐Yau CY3(11,11), M theory on ${CY_3(3,243)\times S^1\over{\bf Z}_2}$ and F‐theory on an elliptically fibered CY4 with the base given by CP1 × Enriques surface, we first give a heuristic argument that there can be no superpotential generated in the orientifold of of CY3(3,243), and then explicitly verify the same using mirror symmetry formulation of [2] for the abovementioned hypersurface away from its orbifold singularities. We then discuss briefly the sigma model and the mirror Landau‐Ginsburg model corresponding to the resolved Calabi‐Yau as well.
Aspects of stability and phenomenology in type IIA orientifolds with intersecting D6‐branes
Authors: Ott T. 
Published: January 2004

AbstractIntersecting branes have been the subject of an elaborate string model building for several years. After a general introduction into string theory, this work introduces in detail the toroidal and \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$\mathbb{Z}_N$\end{document}‐orientifolds. The picture involving D9‐branes with B‐fluxes is shortly reviewed, but the main discussion employs the T‐dual picture of intersecting D6‐branes. The derivation of the R‐R and NS‐NS tadpole cancellation conditions in the conformal field theory is shown in great detail. Various aspects of the open and closed chiral and non‐chiral massless spectrum are discussed, involving spacetime anomalies and the generalized Green‐Schwarz mechanism. An introduction into possible gauge breaking mechanisms is given, too. Afterwards, both 𝒩 = 1 supersymmetric and non‐supersymmetric approaches to low energy model building are treated. Firstly, the problem of complex structure instabilities in toroidal ΩR‐orientifolds is approached by a \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$\mathbb{Z}_3$\end{document}‐orbifolded model. In particular, a stable non‐supersymmetric standard‐like model with three fermion generations is discussed. This model features the standard model gauge groups at the same time as having a massless hypercharge, but possessing an additional global B‐L symmetry. The electroweak Higgs mechanism and the Yukawa couplings are not realized in the usual way. It is shown that this model descends naturally from a flipped SU(5) GUT model, where the string scale has to be at least of the order of the GUT scale. Secondly, supersymmetric models on the \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$\mathbb{Z}_4$\end{document}‐orbifold are discussed, involving exceptional 3‐cycles and the explicit construction of fractional D‐branes. A three generation Pati‐Salam model is constructed as a particular example, where several brane recombination mechanisms are used, yielding non‐flat and non‐factorizable branes. This model even can be broken down to a MSSM‐like model with a massless hypercharge. Finally, the possibility that unstable closed and open string moduli could have played the role of the inflaton in the evolution of the universe is being explored. In the closed string sector, the important slow‐rolling requirement can only be fulfilled for very specific cases, where some moduli are frozen and a special choice of coordinates is taken. In the open string sector, inflation does not seem to be possible at all.
The demographic transition revisited as a global process
Authors: Reher David S. 
Published: January 2004

AbstractWith dramatic declines in fertility taking place throughout the world, it is increasingly important to understand the demographic transition as a global process. While this universality was a cornerstone of classic transition theories, for many decades it was largely neglected by experts because fertility in the developing world did not seem to follow the expected pattern. When comparing earlier and more recent transition experiences, important similarities and disparities can be seen. Everywhere mortality decline appears to have played a central role for fertility decline. The differences in the timing of the response of fertility to mortality decline, with very small gaps historically and prolonged ones in more recent transitions, plus the much more rapid decline in vital rates in many developing countries, constitute an important challenge to any general explanation of the process. The specific characteristics of recent transitions have led to decades of higher population growth rates, and promise to give way to much more rapid dynamics of population ageing in many countries. This may limit the ability of newcomers to take full advantage of the demographic transition for the social and economic modernisation of their societies. Copyright © 2004 John Wiley & Sons, Ltd.
Spaces of silence: single parenthood and the ‘normal family’ in Singapore
Authors: Wong Theresa , Yeoh Brenda S. A. , Graham Elspeth F. , Teo Peggy 
Published: January 2004

AbstractAlternative family forms have begun to emerge in the Confucian societies of East and Southeast Asia, concomitant with widespread demographic changes and new socioeconomic conditions. In Singapore, the state tends to configure ‘single parents’ – including divorcees, unmarried parents and widowed parents – as ‘unfortunate’ and constituting an unhealthy trend, in opposition to the normal, dual‐parent household. This paper examines how single parents in Singapore reconfigure their definitions of the family both discursively and through practical means, in response to the ‘traditional’, Confucian concept of the complete family propounded by the government. Through in‐depth interviews with middle‐class Chinese Singaporean single mothers and fathers, this paper also explores how single parents employ strategies at two levels: in practical decisions relating to childcare; and discursively, through the articulation of remarriage and fertility desires, in which patriarchal notions of the roles of husband/wife and mother/father are embedded. Copyright © 2004 John Wiley & Sons, Ltd.
Forced or free movers? The motives, voluntariness and selectivity of interregional migration in the Nordic countries
Authors: Lundholm Emma , Garvill Jörgen , Malmberg Gunnar , Westin Kerstin 
Published: January 2004

AbstractThis paper examines interregional migration within the five Nordic countries, Sweden, Norway, Denmark, Finland and Iceland, focusing on the impacts on migration decisions. A background to the study is the regional demographic polarisation of the five countries and the debate about labour market migration. The main questions of the study are: (a) What motives, apart from those relating to the labour market, are important to interregional migrants? (b) Do migrants perceive their decision to move as voluntary? (c) Are migration decisions in conflict with peoples' life projects, values and attitudes? The empirical analysis is based on 9600 responses to a survey conducted in all five countries, with participants including both those who have changed resident municipality in the last two years (migrants) and those who have lived in the same municipality for more than five years (stayers). The study reveals that only about one in five migrants give employment as a major motive for moving. Environmental and social factors are often more important. The majority of migrants claim that their decision to move is voluntary. The results also confirm previous research suggesting that migrants are more likely to be young, single people and have a higher educational level than stayers. There is also evidence that migration is often compatible with migrants' values and preferences. Copyright © 2004 John Wiley & Sons, Ltd.
Brief report: Test–retest reliability of self‐reported adolescent risk behaviour
Authors: Flisher Alan J , Evans Janet , Muller Martie , Lombard Carl 
Published: January 2004

AbstractThere is a paucity of test–retest reliability data for adolescent self‐reports of a wide range of risk behaviours. Grade 8 and 11 Students (N=358) completed a questionnaire on two occasions between 10 and 14 days apart. It included items about use of various substances, violent behaviour, suicidality, and sexuality. Cohen's kappa was almost perfect for 1 item (κ=85.4%); in the substantial range (61–80%) for 4 items; and in the moderate range (41–60%) for 3 items. For the remaining 7 items, the percentage agreement was higher than 92.0%. The questionnaire thus demonstrates adequate test–retest reliability.
Subcellular localization of MAK‐V/Hunk protein kinase expressed in COS‐1 cells
Authors: Korobko Elena V. , Kiselev Sergey L. , Korobko Igor V. 
Published: January 2004

AbstractMAK‐V/Hunk is a MARK/Par‐1‐related protein kinase, whose function is unknown. We studied the subcellular localization of MAK‐V/Hunk in COS‐1 cells by immunofluorescence. It has a nucleocytoplasmic distribution and is localized to the centrosome, as indicated by co‐localization with γ‐tubulin. A putative kinase‐deficient mutant, with a mutation in the invariant lysine residue in the catalytic domain, was not targeted to the nucleus or centrosome. These results suggest that the nuclear and centrosomal targeting of MAK‐V/Hunk is specific, and is likely to be coupled to its catalytic activity.