bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the contribution of cyclooxygenase 1 and cyclooxygenase 2 to the production of PGE2 and PGF2 alpha in epithelial cells from bovine endometrium
Authors: Parent J , Villeneuve C , Fortier MA
Published: March 2004

In ruminants, the production of prostaglandins by the endometrium is critical for recognition of pregnancy. In the absence of an embryonic signal, luteolytic pulses of PGF(2 alpha) are released by the uterus. In contrast, the presence of a viable conceptus reduces the production of PGF(2 alpha) relative to PGE(2) and prevents luteolysis through the release of trophoblastic interferon (IFN-tau). Initially, it was thought that epithelial and stromal endometrial cells were specialized in the production of a single type of prostaglandin. However, purified cell populations of both types of cell can produce PGF(2 alpha) and PGE(2); therefore, selective production of PGF(2 alpha) and PGE(2) must be regulated within each type of cell. Two distinct prostaglandin synthases, cyclooxygenase 1 and cyclooxygenase 2, are involved in prostaglandin production and each may catalyse the production of a different prostaglandin. This possibility was investigated in cultured epithelial cells from bovine endometrium. Cells were treated with oxytocin or arachidonic acid, and expression of cyclooxygenase 1 and cyclooxygenase 2 proteins was monitored over time and correlated with prostaglandin accumulation. Cells were also treated with increasing doses of inhibitors of cyclooxygenase 1 or cyclooxygenase 2 (non-steroidal anti-inflammatory drugs; NSAIDs) with or without arachidonic acid or oxytocin: flurbiprofen (0-50 micromol l(-1)) was used as a non-selective inhibitor; valeryl salicylate (0-500 micromol l(-1)) was used as a cyclooxygenase 1 inhibitor and NS-398 (0-1 micromol l(-1)) was used as a cyclooxygenase 2 inhibitor. After stimulation with arachidonic acid or oxytocin, prostaglandin production and expression of cyclooxygenase 2 protein were increased. All inhibitors were able to block basal and stimulated prostaglandin production. These results indicate that in endometrium most, if not all, prostaglandin production is probably processed through cyclooxygenase 2.
Disruption of imprinting in cloned mouse fetuses from embryonic stem cells
Authors: Ogawa H , Ono Y , Shimozawa N , Sotomaru Y , Katsuzawa Y , Hiura H , Ito M , Kono T
Published: March 2004

Cloned mice typically display abnormal development, such as overgrowth of fetuses and placentae. Quantitative expression analysis of eight imprinted genes (H19, Igf2, Igf2r, Air, Peg1/Mest, Peg3, Nuronatin (Nnat) and Ndn) and an alternate transcript of Igf2 (P0) in embryonic stem cloned fetuses and placentae at days 9.5, 12.5 and 17.5 after mating was carried out by real time PCR to investigate whether epigenetic modification of imprinted genes is responsible for overgrowth of the fetus and placental hypertrophy. In addition, the methylation pattern through the bisulphite sequencing method in differentially methylated regions of H19 and Igf2r was examined in day 9.5 fetuses and placentae. The results showed clearly that the expression of H19 gene decreased in cloned fetuses at days 12.5 and 17.5 after mating and in placentae at day 17.5 after mating, and Igf2 was also repressed in fetuses at days 9.5 and 12.5 after mating and in placentae at day 17.5 after mating. In contrast, the transcription of P0, which is a placental-specific transcript variant of Igf2, increased at more than four times the control in cloned placenta at day 12.5 after mating. Day 9.5 fetuses that have developed normally revealed only hypermethylated alleles in the H19 differently methylated region (DMR), and both hyper- and hypomethylated alleles in the Igf2r DMR2. These results show that inappropriate reprogramming in some imprinted genes affects the development of cloned embryos, and that aberrant P0 Igf2 transcription in particular may cause the overgrowth of cloned fetuses and placentae.
Absence of mDazl produces a final block on germ cell development at meiosis
Authors: Saunders PT , Turner JM , Ruggiu M , Taggart M , Burgoyne PS , Elliott D , Cooke HJ
Published: March 2004

The autosomal gene DAZL is a member of a family of genes (DAZL, DAZ, BOULE), all of which contain a consensus RNA binding domain and are expressed in germ cells. Adult male and female mice null for Dazl lack gametes. In order to define more precisely the developmental stages in germ cells that require Dazl expression, the patterns of germ cell loss in immature male and female wild-type (+/+, WT) and Dazl -/- (DazlKO) mice were analysed. In females, loss of germ cells occurred during fetal life and was coincident with progression of cells through meiotic prophase. In males, testes were recovered from WT and DazlKO males obtained before and during the first wave of spermatogenesis (days 2-19). Mitotically active germ cells were present up to and including day 19. Functional differentiation of spermatogonia associated with detection of c-kit positive cells did not depend upon expression of Dazl. RBMY-positive cells (A, intermediate, B spermatogonia, zygotene and preleptotene spermatocytes) were reduced in DazlKO compared with WT testes. Staining of cell squashes from day 19 testes with anti-gamma-H2AX and anti-SCP3 antibodies showed that germ cells from DazlKO males were unable to progress beyond the leptotene stage of meiotic prophase I. It was concluded that in the absence of Dazl, germ cells can complete mitosis, and embark on functional differentiation but that, in both sexes, progression through meiotic prophase requires this RNA binding protein.
Spermatogenesis in testes of Dazl null mice after transplantation of wild-type germ cells
Authors: R R , Speed R , Taggart M , Cooke HJ
Published: March 2004

Dazl knockout male mice are infertile because their germ cells are unable to complete the first meiotic prophase in the first wave of spermatogenesis and thereafter decrease in number due to a block at the A-aligned to A1 transition. The ability of the surviving somatic components of the testes to retain their function in the absence of mature germ cells was tested by injecting marked wild-type germ cell suspensions containing spermatogonial stem cells. Comparison of the frequency and extent of colonization of Dazl knockout testes with that of testes chemically depleted of germ cells showed little if any difference. It was concluded that Dazlko testes seem unimpaired in their ability to support spermatogenesis. Therefore, Dazlko testes provide a useful and reliable recipient in which to evaluate spermatogonial stem cells. The results furthermore demonstrate that the somatic compartment of the testis of these animals retains functionality.
Effect of platelet-activating factor (PAF) on stallion sperm motility, capacitation and the acrosome reaction
Authors: Odeh AI , Dascanio JJ , Caceci T , Bowen J , Eng LA
Published: March 2004

Phospholipids are an essential component of all mammalian cells; platelet activating factor (PAF=1-O-alkyl-acetyl-sn-glycero-3-phosphocholine) is a signalling phospholipid that has many biological properties in addition to platelet activation. PAF receptors have been detected on stallion spermatozoa; therefore, the aim of this study was to evaluate the effect of synthetic PAF on the motility, capacitation and the acrosome reaction of stallion spermatozoa. Treatment of ten stallion semen samples with 10(-4)-10(-13) mol PAF l(-1) resulted in significant differences in motility and capacitation (r(2)=0.81 and 0.83, respectively). Statistical analysis indicated that PAF also has an effect on acrosome reaction (r(2)=0.20). PAF concentrations, incubation time and their interaction had a highly significant (P<0.01) effect on motility. After capacitation in vitro with PAF, and induction of the acrosome reaction by progesterone, transmission electron microscopy was conducted on the spermatozoa of three stallions to detect the true acrosome reaction. Differences in PAF concentrations were highly significant (r(2) for intact: 97.2; reacted: 89.8; and vesiculated: 98.1). The results indicate that a lower concentration of PAF enhances motility and induces capacitation of stallion spermatozoa, whereas a higher concentration of PAF induces the acrosome reaction.
Expression of CA-125 by progestational bovine endometrium: prospective regulation and function
Authors: McDonnel AC , Van Kirk EA , Austin KJ , Hansen TR , Belden EL , Murdoch WJ
Published: March 2004

Cancer antigen 125 (CA-125) is expressed by malignant human ovarian surface epithelial cells and derivatives of the Mullerian duct system. This study explored the expression, regulation, and function of CA-125 in the bovine uterus. CA-125 was localized by immunohistochemistry to the apical surfaces of epithelial cells lining the endometrium and proximal glands of the late luteal phase and early pregnancy; antigen was not detected during oestrus or the postpartum period. Production of CA-125 by bovine endometrial cells in vitro was upregulated by progesterone and interferon-tau. Immunopurified CA-125 from uterine flushes of dioestrous or pregnant cows was similar in biochemical composition (as determined by gel electrophoresis and amino acid content) to the human antigen isolated from incubation medium conditioned by the ovarian cancer cell line OVCAR-3. Bovine CA-125 inhibited complement-induced lysis of antibody-sensitized sheep erythrocytes. It is suggested that endometrial CA-125 exerts a progestational role in part by protecting maternal and embryonic cells from immune targeting and lysis.
Expression of inter-alpha-trypsin inhibitor heavy chains in endometrium of cyclic and pregnant gilts
Authors: Geisert RD , Ashworth MD , Malayer
Published: March 2004

Attachment of the placenta to the uterus in pigs involves extracellular interaction between the expanding trophoblastic membrane and the thick glycocalyx present on the uterine epithelial microvilli. Formation of complexes between members of inter-alpha-trypsin inhibitor family may function in the maintenance of the extracellular matrix. This study investigated the change in the inter-alpha-trypsin inhibitor heavy chains (ITIH1, ITIH2, ITIH3 and ITIH4) during the oestrous cycle and early pregnancy in pigs. Gene expression of ITIH1, ITIH2, ITIH3 and ITIH4 was detected in the endometrium of cyclic and pregnant gilts; however, gene expression of ITIH was not altered throughout the oestrous cycle or early pregnancy. Western blot analysis with an ITIH antiserum identified the possible linkage forms of ITIH with the serine protease inhibitor, bikunin. Pregnancy altered the release of the various inter-alpha-inhibitor forms from the endometrium during the period of trophoblastic attachment. The results from this study indicate that the inter-alpha-trypsin inhibitor family plays an important role in maintenance of the uterine surface glycocalyx during placental attachment in pigs.
Sequence of interleukin 1beta actions on corpus luteum regression: relationship with inducible cyclooxygenase and nitric oxide synthase expression
Authors: Estevez A , Tognetti T , Luchetti CG , Sander V , Motta AB
Published: March 2004

Corpus luteum regression has been described in terms of: (i) functional luteolysis - a reversible decline in serum progesterone concentration; and (ii) structural luteolysis - irreversible morphological changes and tissue remodelling events within the cellular membrane. In rats, PGF(2alpha) and interleukin 1beta (IL-1beta) are involved in structural luteolysis, PGF(2alpha) by increasing ovarian lipid peroxidation, and IL-1beta by reducing progesterone and increasing PGF(2alpha) concentrations. The aim of the present report was to determine whether by an early action IL-1beta is able to regulate functional luteolysis. Thus, ovarian explants from rats at the mid-stage of corpus luteum development were incubated during short periods with either 15 or 25 ng IL-1beta ml(-1). At 15 ng ml(-1), IL-1beta inhibited progesterone after 4 and 8 h of culture without affecting PGF(2alpha) production, and a longer incubation (21 h) was needed to increase PGF(2alpha) production. In contrast, IL-1beta enhanced PGF(2alpha) concentrations at 8 h only at the higher dose (25 ng ml(-1)). The observed reduction in progesterone synthesis at the lower dose of IL-1beta before the increase in PGF(2alpha) concentrations led to the hypothesis that IL-1beta regulates functional luteolysis (progesterone diminution) before it affects structural luteolysis (PGF(2alpha) increase). The fact that the early IL-1beta action was described at 4 h but no effects on inducible nitric oxide synthase and inducible cyclooxygenase expression were found before this time led to the suggestion that these inductions were not necessary for the early IL-1beta action described.
Stimulatory effects of fasting on vascular endothelial growth factor (VEGF) production by growing pig ovarian follicles
Authors: Galeati G , Spinaci M , Govoni N , Zannoni A , Fantinati P , Seren E , Tamanini C
Published: March 2004

The aim of this study was to investigate the effect of fasting on both vascular endothelial growth factor (VEGF) production and VEGF mRNA expression in growing ovarian follicles (>5 mm in diameter) from gilts at 48 h after equine chorionic gonadotrophin (eCG) treatment. The concentrations of VEGF and albumin were measured in the follicular fluid of single follicles, and VEGF mRNA was determined in the follicle wall. Fasting resulted in a significant increase in VEGF concentrations in follicular fluid (20.64+/-0.72 versus 10.79+/-0.86 ng ml(-1), P<0.001), but it did not affect the total amount of VEGF mRNA in the follicle wall compared with that of fed animals. However, VEGF mRNA in the theca and granulosa compartments increased and decreased, respectively, compared with that of fed animals. The concentrations of albumin measured in follicular fluid as an index of vessel permeability were higher in fasted than in animals fed normally, most likely as a result of the increased VEGF production. Follicular steroidogenesis was impaired in fasted animals. Progesterone was the most abundant steroid in the follicular fluid and oestradiol was present in lower concentrations, thus indicating an alteration in the steroidogenic enzymatic cascade. In conclusion, fasting induces an increase in both VEGF production and vessel permeability. Such a reaction is unable under severe food deprivation to preserve follicle function, but may represent a mechanism that regulates blood vessel extension and distribution in relation to tissue requirements and availability of systemic nutrient.
Correlation between DNA synthesis in the second, third and fourth generations of spermatogonia and the occurrence of apoptosis in both spermatogonia and spermatocytes
Authors: Blanco-Rodriguez J , Martinez-Garcia C , Porras A
Published: March 2004

In the seminiferous epithelium, both DNA synthesis and apoptosis occur at equivalent stages in various species, with apoptosis taking place mainly at the same stages as DNA replication in the second, third and fourth spermatogonial generations. As preservation of the cellular associations found at these stages may have some functional significance, it is important to determine whether there is a correlation between these cellular events. In this study, pairs of immunoperoxidase-stained adjacent testis sections from rats, mice, rabbits and cats in which either bromodeoxyuridine incorporated into the newly synthesized DNA strand (BrdU labelling) or DNA 3' end labelling of the apoptotic DNA fragments (TUNEL assay) were detected were compared. In addition, both events were analysed in double-labelled sections. These two methods revealed a clear correlation between the occurrence of DNA replication in the second to fourth generations of spermatogonia and most physiological apoptosis taking place in both spermatogonia and spermatocytes in the three different mammalian orders (Rodentia, Lagomorpha and Carnivora). This correlation may result from the synchronization of mitotic spermatogonial and meiotic spermatocyte cell cycle checkpoints operating at these stages.
Non-random distribution of spermatogonia in rats: evidence of niches in the seminiferous tubules
Authors: Chiarini-Garcia H , Raymer AM , Russell LD
Published: March 2004

The relationships and distribution of spermatogonia were studied as a function of the stage of the seminiferous epithelium cycle in rats. Primitive spermatogonia in the mouse are located along regions of the basal lamina that face the interstitium. Before studying the distribution of spermatogonia in rats, it was necessary to characterize the various types of spermatogonia, as recently performed for mice. The Strauss' linear index (Li) selectivity method was then used and spermatogonia of the A(single) (A(s)) to A(aligned) (A(al)) lineage were preferentially found to be located in regions opposing the interstitium at stages V, VII and IX of the spermatogenic cycle. Because relatively little tubule-to-tubule contact occurs in rats, the aim of this study was to determine whether tubule-to-tubule contact or tubule proximity (or alternatively, the amount of interstitium) was an important factor in spermatogonial position. In this regard, another method (tubule proximity) was devised to determine spermatogonial position that accounted for the presence of adjacent tubules. This method showed that the position of tubules, rather than tubule contact, was more accurate than the Li method in determining the location of spermatogonia in the rat. The results also showed a non-random distribution of spermatogonia resembling that of the mouse, and that tubule-to-tubule contact is not essential for the positioning of spermatogonia. In conclusion, the results of this study strongly indicate that the most primitive type A spermatogonia (A(s), A(paired) and A(al)) in rats are present in niches located in those areas of the seminiferous tubules that border the interstitial tissue.
Comparison of accumulation and altered steroid secretion by placental tissue treated with TCDD and natural mixture of PCDDs-PCDFs
Authors: Augustowska K , Gregoraszczuk E EL , Grochowalski A , Milewicz T , Mika M , Krzysiek J , Chrzaszcz R
Published: March 2004

Explants of human placental tissue harvested immediately after expulsion were used to determine differences between accumulation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and polychlorinated dibenzo-p-dioxin (PCDD)-polychlorinated dibenzo-p-furans (PCDF) environmental mixture, and their influence on placental steroidogenesis. Explants were cultured in vitro for 5 days in media supplemented each day with either TCDD or a mixture of PCDD-PCDF. Media were collected every day for steroid content analysis by radioimmunoassay. At 24 h after the last treatment, the tissue was frozen for further analysis of the content of TCDD or other congeners present in the mixture. Determinations of TCDD and all 17 PCDDs and PCDFs were performed using gas chromatography equipped with DB-5 MS and DB-17 capillary columns. In the control tissue, the amounts of both TCDD and mixture components were close to the limit of detection of the method. In the treated tissue, the TCDD accumulation was 94% of the total exposure to TCDD. The most toxic congeners 2,3,7,8-TCDD, 2,3,7,8-tetrachlorodibenzofuran, 1,2,3,7,8-pentachlorodibenzo-p-dioxin (PeCDD), 1,2,3,7,8-pentachlorodibenzo-p-furans (PeCDF) and 2,3,4,7,8-PeCDF showed the highest accumulation, which covered >50% of the total toxic equivalents present in this mixture. During the first 3 days of exposure to TCDD there was no effect on the conversion of dehydroepiandrosterone to oestradiol, whereas on days 4 and 5 of exposure, a twofold decrease in oestradiol secretion was observed. However, a small but significant increase in oestradiol secretion was noted at all times of exposure to the PCDD-PCDF mixture. All observed changes in oestradiol secretion were not accompanied by changes in progesterone secretion after exposure to TCDD or the PCDD-PCDF mixture. In conclusion, a high accumulation of TCDD in the placental tissue resulted in a decrease in oestradiol secretion and in vivo this could result in a decrease in blood flow through the placenta. From the mixture, PeCDD and PeCDF in the higher amount accumulated in the placental tissue caused an increase in oestrogen secretion and as a consequence could activate oxytocin secretion from the pituitary and early pregnancy outcome.
Ovarian gonadotrophin surge-attenuating factor (GnSAF): where are we after 20 years of research?
Authors: Fowler PA , Sorsa-Leslie T , Harris W , Mason HD
Published: March 2004

When gonadotrophin-stimulated IVF methods were being developed in the 1970s and 1980s, understanding of the physiology of FSH improved. In addition to its classic actions of stimulating aromatase activity and oestradiol secretion by ovarian granulosa cells, FSH was found to stimulate the ovarian production of an uncharacterized hormone known by its specific effect of reducing pituitary responsiveness to GnRH. This hormone has been called gonadotrophin surge-attenuating factor (GnSAF), gonadotropin surge-inhibiting factor (GnSIF), various abbreviations (GnSAF/IF, GnSIF/AF) and also attenuin. Although first described in the 1980s, GnSAF has still not been convincingly characterized and no published candidate amino acid sequences conclusively relate to GnSAF bioactivity. On the basis of superovulation studies and in vitro experimentation into the roles of steroids in regulating LH, GnRH and GnRH self-priming, the concept that GnSAF has a role in the regulation of LH secretion, the timing of the LH surge and the prevention of premature luteinization developed. For at least a decade, understanding of the specific GnSAF effects of reducing pituitary sensitivity to GnRH, especially GnRH self-priming and antagonizing the stimulatory effects of oestradiol on GnRH-induced LH secretion, supported this concept. However, improved knowledge of the changes in GnSAF bioactivity in follicular fluid and serum in women requires revision of this concept. The present authors propose that the main role of GnSAF is probably the negative regulation of pulsatile LH secretion, mainly during the first half of the follicular phase, indicating a critical role in the regulation of folliculogenesis and oestradiol secretion.
Variation in ovarian morphology in four species of New World moles with a peniform clitoris
Authors: Rubenstein NM , Cunha GR , Wang YZ , Campbell KL , Conley AJ , Catania KC , Glickman SE , Place NJ
Published: March 2004

Female moles of the Old World genus Talpa display a curious suite of reproductive features that include a peniform clitoris and ovaries with a discrete interstitial gland or testis-like region (so-called 'ovotestes'). The masculinization of the female external genitalia in Talpa has accordingly been linked with secretion of androgens from the interstitial gland region of the fetal gonad. Although their ovarian morphology has received less attention, some species of New World moles also have ovaries with a pronounced interstitial gland (for example star-nosed mole, Condylura cristata), whereas females of other species do not (for example eastern mole, Scalopus aquaticus). Although it is difficult to determine the sex of both Old and New World moles, published accounts describing the external genitalia of female moles are available only for Talpa. The hypothesis that masculinization of the female external genitalia in moles is associated with the presence of an ovarian interstitial gland (OIG) was tested in the present study by using a comparative approach to determine whether these features are ever found in isolation of one another. Three genera of North American moles (Scapanus, Condylura and Neurotrichus) were studied and a peniform clitoris was found in all three species, but OIG were found in only two of three genera. The ovaries of S. latimanus and S. orarius were unremarkable, with no evidence of a discrete interstitial gland or testis-like region. Mapping these results onto recent talpid phylogenies indicates that loss of the bipolar ovarian morphology is a derived trait in Scapanus, and conclusively demonstrates that masculinization of the external genitalia in female moles can develop in the presence or absence of 'ovotestes'.
Involvement of enzymes of amino acid metabolism and tricarboxylic acid cycle in bovine oocyte maturation in vitro
Authors: Cetica P , Pintos L , Dalvit G , Beconi M
Published: March 2004

Few studies demonstrate at a biochemical level the metabolic profile of both cumulus cells and the oocyte during maturation. The aim of the present study was to investigate the differential participation of enzymatic activity in cumulus cells and in the oocyte during in vitro maturation (IVM) by studying the activity of enzymes involved in the control of amino acid metabolism, alanine aminotransferase (ALT) and aspartate aminotransferase (AST); and the tricarboxylic acid (TCA) cycle, isocitrate dehydrogenase (IDH) and malate dehydrogenase (MDH). No NAD-dependent isocitrate dehydrogenase (NAD-IDH) activity was recorded in cumulus-oocyte complexes (COCs). ALT, AST, NADP-dependent isocitrate dehydrogenase (NADP-IDH) and MDH enzymatic units remained constant in cumulus cells and oocytes during IVM. Specific activities increased in oocytes and decreased in cumulus cells as a result of IVM (P<0.05). Similar activity of both transaminases was detected in cumulus cells, unlike in the oocyte, in which activity of AST was 4.4 times greater than that of ALT (P<0.05). High NADP-IDH and MDH activity was detected in the oocyte. Addition of alanine, aspartate, isocitrate + NADP, oxaloacetate or malate + NAD to maturation media increased the percentage of denuded oocytes reaching maturation (P<0.05), in contrast to COCs in which differences were not observed by addition of these substrates and co-enzymes. The activity of studied enzymes and the use of oxidative substrates denotes a major participation of transaminations and the TCA cycle in the process of gamete maturation. The oocyte thus seems versatile in the use of several oxidative substrates depending on the redox state.
Hormonal and behavioural changes during the mating season and pregnancy in Alpine marmots (Marmota marmota)
Authors: Exner C , Wehrend A , Hospes R , Einspanier A , Hoffmann B , Heldmaier G
Published: March 2004

Under natural and artificial conditions, Alpine marmots (Marmota marmota) are true hibernators with a single breeding season starting immediately upon emergence from hibernation. Over three mating and breeding seasons, hormonal and mating patterns of colony-housed reproductive female marmots were investigated after exit from hibernation. Blood samples were taken for progesterone, oestrogen and relaxin assays with parallel ultrasound investigations. Copulations were observed from the first day after exit from hibernation until the end of pregnancy and reached a maximum number on day 37 before parturition. Mating behaviour was observed between the dominant animals as well as between dominant and subdominant group members. In the first week after exit from hibernation, plasma progesterone was detected in half of the animals. During the third week, progesterone concentrations were significantly higher in pregnant than in non-pregnant animals or animals that had aborted. Immediately after emerging from hibernation, all successfully mated females showed higher serum relaxin values than non-successfully mated animals and this increase in relaxin concentration lasted until the end of pregnancy. The total concentration of oestrogen did not differ between pregnant and non-pregnant animals. The results of this study indicate that progesterone and relaxin might be useful indicators of early pregnancy in Alpine marmots.
Effect of neonatal chronic stress on expression of Hsp70 and oestrogen receptor alpha in the rat oviduct during development and the oestrous cycle
Authors: Mariani ML , Ciocca DR , Gonzalez Jatuff AS , Souto M
Published: March 2004

A chronic unpredictable stress model used to produce depressive disorders in adult rats was applied to neonatal rats to investigate whether this type of stress can induce changes in the expression of Hsp70 and oestrogen receptor alpha in the oviduct, as detected by immunohistochemistry. Rats stressed during neonatal development showed changes in the expression pattern of Hsp70. In neonatal control rats, Hsp70-positive cells observed in the isthmus did not show any changes. Moreover, rats exposed to this stress model that reached adulthood had higher expression of Hsp70 in the isthmus (P<0.01) but not in the ampulla during oestrus than did the control rats. In contrast, during dioestrus, no significant changes were noted in adult rats that were stressed during neonatal development or in rats that were stressed in adulthood. These findings indicate that the isthmus is very sensitive to stressful stimuli and that repeated pre-weaning stress can change the expression of heat shock proteins in early and adult life. These subtle changes of expression in the oviduct did not affect the fertility of the rats that reached adulthood or that were mated under unstressed conditions. However, the control animals stressed during adulthood showed a disruption of the oestrous cycle: this finding is not observed in rats stressed during neonatal development that show an attenuated oestrous cycle disruption induced by chronic stress in adulthood. Moreover, there was dissociation between the expression of oestrogen receptor alpha and Hsp70. The amount of oestrogen receptor alpha remained constant in the epithelium of the oviduct in the control and in the stressed rats. Expression of oestrogen receptor alpha was noted in the stroma of the oviduct without the concomitant expression of Hsp70. It is possible that in certain cells and tissues Hsp70 is not necessary for oestrogen receptor alpha to be functional or Hsp70 might be present at very low amounts but is sufficient for the receptor to function.
Mating-induced cumulus-oocyte maturation in the shrew, Suncus murinus
Authors: Kaneko T , Iida H , Bedford JM , Oda S , Mori T
Published: March 2004

The musk shrew, Suncus murinus, is an induced ovulator, the cumulus oophorus of which is unusual in several respects: it has no matrix, it always induces the acrosome reaction and it appears to be essential for fertilization. The present study documents distinctive features of the cumulus oophorus before and after ovulation, and of copulation-induced maturation of the ovulatory follicle, which has no antrum. In unmated females, potentially responsive ovarian follicles are distinguishable from large secondary follicles by differentiation of the granulosa into outer and inner cell layers, the latter being characterized particularly by intracellular glycogen deposits. The average number of responsive follicles equates with the number that ovulate. By about 10 h after mating, meiosis has reached metaphase II, with extrusion of the first polar body. Coincidentally, a cavity has developed between the inner and outer follicular layers, demarcating the smaller cells of the granulosa from the glycogen-rich cells of the cumulus oophorus. Subsequently, the glycogen becomes restricted primarily to the inner cumulus, and the corona cells began to retreat from the zona pellucida surface to form an unusual very distinct perizonal space that is clearly evident at the time of ovulation. The cumulus is stabilized by gap and tight junctions, and presents a smooth external surface that appears to initiate the acrosome reaction. After fertilization, at which time the zona pellucida becomes more resistant to both trypsin and dithiothreitol, the cumulus develops intercellular lacunae, and is eventually discarded about 15 h after ovulation.
Fold maps on 4-manifolds
Authors: Saeki Osamu
Published: March 2004

We give a complete characterization of those closed orientable 4-manifolds which admit smooth maps into R^3 with only fold singularities. We also clarify the relationship between the existence problem of fold maps and that of linearly independent vector fields on manifolds.
Elementary modifications and line configurations in P^2
Authors: Schenck Henry K.
Published: March 2004

Associated to a projective arrangement of hyperplanes

{\mathcal A}

in P^n is the module D

({\mathcal A})

, which consists of derivations tangent to

{\mathcal A}

. We study D

({\mathcal A})

when

{\mathcal A}

is a configuration of lines in P^2. In this setting, we relate the deletion/restriction construction used in the study of hyperplane arrangements to elementary modifications of bundles. This allows us to obtain bounds on the Castelnuovo-Mumford regularity of D

({\mathcal A})

. We also give simple combinatorial conditions for the associated bundle to be stable, and describe its jump lines. These regularity bounds and stability considerations impose constraints on Teraos conjecture.
Sur une conjecture de Mukai
Authors: Bonavero Laurent , Casagrande Cinzia , Debarre Olivier , Druel Stéphane
Published: March 2004

Generalizing a question of Mukai, we conjecture that a Fano manifold

X

with Picard number

\rho_X

and pseudo-index

\iota_X

satisfies

\rho_X(\iota_X - 1) \leq \mathrm{dim}(X)

. We prove this inequality in several situations:

X

is a Fano manifold of dimension

\leq 4

,

X

is a toric Fano manifold of dimension

\leq 7

, or

X

is a toric Fano manifold of arbitrary dimension with

\iota_X\geq \mathrm{dim}(X) / 3 + 1

. Finally, we offer a new approach to the general case.

Généralisant une question de Mukai, nous conjecturons quáune variété de Fano

X

de nombre de Picard

ρ_X

et de pseudo-indice

ι_X

vérifie

ρ_X(ι_X − 1) ≤ \mathrm{dim}(X)

. Nous démontrons cette conjecture dans plusieurs situations :

X

est une variété de Fano de dimension

≤ 4

,

X

est une variété de Fano torique de dimension

≤ 7

ou

X

est une varété de Fano torique de dimension arbitraire avec

ι_X ≥ \mathrm{dim}(X)/3 + 1

. Enfin, nous présentons une approche nouvelle pour le cas général.
Dynamical properties of the space of Lorentzian metrics
Authors: Mounoud Pierre
Published: March 2004

We study the mechanisms of the non properness of the action of the group of diffeomorphisms on the space of Lorentzian metrics of a compact manifold. In particular, we prove that nonproperness entails the presence of lightlike geodesic foliations of codimension 1. On the 2-torus, we prove that a metric with constant curvature along one of its lightlike foliation is actually flat. This allows us to show that the restriction of the action to the set of non-flat metrics is proper and that on the set of flat metrics of volume 1 the action is ergodic. Finally, we show that, contrarily to the Riemannian case, the space of metrics without isometries is not always open.
On Waring's problem for several algebraic forms
Authors: Carlini Enrico , Chipalkatti Jaydeep V.
Published: March 2004

We reconsider the classical problem of representing a finite number of forms of degree d in the polynomial ring over n + 1 variables as scalar combinations of powers of linear forms. We define a geometric construct called a 'grove', which, in a number of cases, allows us to determine the dimension of the space of forms which can be so represented for a fixed number of summands. We also present two new examples, where this dimension turns out to be less than what a naïve parameter count would predict.
How genes causing unfit hybrids evolve within populations: a review of models of postzygotic isolation
Authors: Hayashi T. I. , Kawata M.
Published: March 2004

The main subject for models of postzygotic isolation has been how reproductive isolation genes (RI genes) which cause hybrid inviability or sterility spread within populations despite their deleterious effects. The models are divided into three categories according to the within‐population effect of RI genes in their fixation process. (1) The beneficial effect model, where RI genes are assumed to spread within populations by a positive selective force via natural or sexual selection. (2) The neutral effect model, where RI genes are assumed not to affect the fitness of individuals in their fixation process and to be spread by genetic drift. (3) The deleterious effect model, where RI genes are assumed to exhibit some (slightly) deleterious effects in their fixation process and to be spread by genetic drift. Factors that affect the applicability of these models are discussed. If a selective force such as sexual conflict or natural selection facilitates the evolution of RI genes, the beneficial effect model should be applied. Many empirical studies have suggested that positive selection plays an important role in the evolution of hybrid male sterility. If the mutation rates of RI genes are low, and the specificity of epistatic interaction causing hybrid inviability or sterility is high, the neutral effect model should be applied. However, if the opposite condition applies, the deleterious effect model should be applied.
Biology of reproductive isolation in Drosophila: toward a better understanding of speciation
Authors: Sawamura K. , Tomaru M.
Published: March 2004

Mechanisms of premating and postmating isolation between Drosophila melanogaster and its sibling species, D. simulans, D. mauritiana, and D. sechellia, are reviewed here. As D. melanogaster has been used as a “model organism” in a variety of studies, we can apply much knowledge about this species to interspecific hybridizations. Mating success between species is low because of species specificity of pheromonal and acoustic signals and the receivers, although other factors are also involved. On the other hand, genetic incompatibility between species results in inviability and sterility in F1 and backcross hybrids. Studies of reproductive isolation between these Drosophila species will shed light on animal speciation and the origin of biodiversity.
Indirect effects mediated by compensatory shoot growth on subsequent generations of a willow spittlebug
Authors: Nozawa A. , Ohgushi T.
Published: March 2004

We investigated whether oviposition by the spittlebug Aphrophora pectoralis on Salix miyabeana and S. sachalinensis in fall 1998 affected shoot growth pattern and further oviposition by subsequent generations of the willow spittlebug in early September 1999 and 2000. Spittlebug oviposition enhanced the growth of current‐year shoots on 1‐year shoots with oviposition (O‐shoots) compared to those without oviposition (N‐shoots): the length of current‐year shoots increased in 1999 and 2000, the number of current‐year shoots increased in 2000 despite a decrease in 1999, and the shoot abscission rate decreased during the 1999 winter. The number of egg masses per current‐year shoot was greater on O‐shoots than on N‐shoots in 1999, and this tendency was reinforced in 2000. The total number of egg masses was greater on O‐shoots than on N‐shoots in 2000, although there was no significant difference in 1999. There is thus a positive feedback system between spittlebug attack and compensatory growth on willow.
Backward chromosome movement in crane‐fly spermatocytes after UV microbeam irradiation of the interzone and a kinetochore
Authors: Wong Raymond , Forer Arthur
Published: March 2004

Single anaphase chromosomes (in crane‐fly spermatocytes) moved backwards after double irradiations with an ultraviolet light (UV) microbeam, first of the interzone and then of a kinetochore: the chromosome irradiated at the kinetochore moved backwards rapidly, across the equator and into the other half‐spindle. High irradiation doses at the kinetochore were required to induce backward movement. Single irradiations of kinetochores or interzones were ineffective in inducing backward movements.
EXORDIUM regulates brassinosteroid‐responsive genes
Authors: Coll-Garcia Danahe , Mazuch Jeannine , Altmann Thomas , Müssig Carsten
Published: March 2004

In a screen for potential mediators of brassinosteroid (BR) effects, the EXORDIUM (EXO) protein was identified as a regulator of BR‐responsive genes. The EXO gene was characterized as a BR‐up‐regulated gene. EXO overexpression under the control of the 35SCaMV promoter resulted in increased transcript levels of the BR‐up‐regulated KCS1, Exp5, δ‐TIP, and AGP4 genes, which likely are involved in the mediation of BR‐promoted growth. 35S::EXO lines grown in soil or in synthetic medium showed increased vegetative growth in comparison to wild‐type plants, resembling the growth phenotype of BR‐treated plants. Thus, the EXO protein most likely promotes growth via the modulation of gene expression patterns.
Expression and differential cell distribution of low‐threshold Ca2+ channels in mammalian male germ cells and sperm
Authors: Treviño Claudia L , Felix Ricardo , Castellano Laura E , Gutiérrez Carolina , Rodrı́guez Delany , Pacheco Judith , López-González Ignacio , Gomora Juan Carlos , Tsutsumi Victor , Hernández-Cruz Arturo , Fiordelisio Tatiana , Scaling Allison L , Darszon Alberto
Published: March 2004

Numerous sperm functions including the acrosome reaction (AR) are associated with Ca2+ influx through voltage‐gated Ca2+ (CaV) channels. Although the electrophysiological characterization of Ca2+ currents in mature sperm has proven difficult, functional studies have revealed the presence of low‐threshold (CaV3) channels in spermatogenic cells. However, the molecular identity of these proteins remains undefined. Here, we identified by reverse transcription polymerase chain reaction the expression of CaV3.3 mRNA in mouse male germ cells, an isoform not previously described in these cells. Immunoconfocal microscopy revealed the presence of the three CaV3 channel isoforms in mouse spermatogenic cells. In mature mouse sperm only CaV3.1 and CaV3.2 were detected in the head, suggesting its participation in the AR. CaV3.1 and CaV3.3 were found in the principal and the midpiece of the flagella. All CaV3 channels are also present in human sperm, but only to a minor extent in the head. These findings were corroborated by immunogold transmission electron microscopy. Tail localization of CaV3 channels suggested they may participate in motility, however, mibefradil and gossypol concentrations that inhibit CaV3 channels did not significantly affect human sperm motility. Only higher mibefradil doses that can block high‐threshold (HVA) CaV channels caused small but significant motility alterations. Antibodies to HVA channels detected CaV1.3 and CaV2.3 in human sperm flagella.
Critical assessment of a proposed model of Shaker
Authors: Lainé Muriel , Papazian Diane M , Roux Benoı̂t
Published: March 2004

Detailed three‐dimensional structures at atomic resolution are essential to understand how voltage‐activated K+ channels function. The X‐ray crystallographic structure of the KvAP channel has offered the first view at atomic resolution of the molecular architecture of a voltage‐activated K+ channel [Jiang et al. (2003) Nature 423, 33]. In the crystal, the voltage sensors are bound by monoclonal Fab fragments, which apparently induce a non‐native conformation of the tetrameric channel. Thus, despite this significant advance our knowledge of the native conformation of a Kv channel in a membrane remains incomplete. Numerous results from different experimental approaches provide very specific constraints on the structure of K+ channels in functional conformations. These results can be used to go further in trying to picture the native conformation of voltage‐gated K+ channels. However, the direct translation of all the available information into three‐dimensional models is not straightforward and many questions about the structure of voltage‐activated K+ channels are still unanswered. Our aim in this review is to summarize the most important pieces of information currently available and to provide a critical assessment of the model of Shaker recently proposed by Lainé et al. [Neuron 39 (2003) 467].
Nitric oxide differentially regulates pro‐ and anti‐angiogenic markers in DLD‐1 colon carcinoma cells
Authors: Hellmuth Markus , Paulukat Jens , Ninic Raiko , Pfeilschifter Josef , Mühl Heiko
Published: March 2004

Inducible nitric oxide (NO) synthase (iNOS) appears to be a marker of tumor progression in colon carcinogenesis. Here we investigated effects of NO on selected chemokines that differentially regulate angiogenesis, namely pro‐angiogenic interleukin (IL)‐8 as well as tumor‐suppressive interferon‐inducible protein‐10 (IP‐10) and monokine induced by interferon‐γ (MIG). These chemokines are expressed by DLD‐1 colon carcinoma cells after stimulation with IL‐1β/interferon‐γ. Expression of IL‐8 was markedly upregulated by NO. Moreover, NO enhanced expression of vascular endothelial growth factor (VEGF). In contrast, expression of IP‐10 and MIG was suppressed by NO. The present data are consistent with previous observations that link NO to enhanced tumor angiogenesis and imply that NO‐mediated upregulation of IL‐8 and VEGF as well as downregulation of IP‐10 and MIG may contribute to this phenomenon.
Enzymatic activity of toxic and non‐toxic type 2 ribosome‐inactivating proteins
Authors: Barbieri Luigi , Ciani Marialibera , Girbés Tomás , Liu Wang-yi , Van Damme Els J.M , Peumans Willy J , Stirpe Fiorenzo
Published: March 2004

Ribosome‐inactivating proteins (RIPs) display adenine polynucleotide glycosylase activity on different nucleic acid substrates, which at the ribosomal level is responsible for the arrest of protein synthesis. Some type 2 RIPs, namely ricin and related proteins, are extremely toxic to mammalian cells and animals whilst other type 2 RIPs (non‐toxic type 2 RIPs) display three to four logs less toxicity. We studied whether a correlation exists between toxicity on cells and enzymatic activity on nucleic acids. All type 2 RIPs differ in their depurinating activity on the different substrates with differences of up to one to two logs. The toxicity of type 2 RIPs is independent of their enzymatic activity on nucleic acids or on ribosomes.
The euro and European identity: symbols, power and the politics of European monetary union
Authors: Kaelberer Matthias
Published: March 2004

This article assesses the relationship between money, collective identity, and European integration. The recent move of the European Union (EU) toward a common currency – the euro – seems to contradict the conventional ‘one nation/one money’ assumption about the association between states, territory and money creation. However, from a broad macro-historical perspective, the process of European monetary unification is not as exceptional and unique as it is often made out to be. I argue that the relationship between money and collective identity is reciprocal. On the one hand, money is a purposeful political tool in the construction of identities. On the other hand, in order to function properly, money requires some degree of collective identity among its users. Thus, the article examines the role of the euro as part of an explicit project to facilitate the development of a European identity as well as the required level of European identity necessary for a successful functioning of the euro. The key identity aspect at stake in the relationship between money and identity is not an affective relationship between citizens and country, but rather a relationship of trust. During the process of modernisation, trust has become rather abstract and institutionalised. To support a modern relationship of trust, identity does not have to rest on deep affective feelings of belonging. Diffuse identity, based on utilitarian or contractual factors and as part of evolving hybrid identity structures, is sufficient.
Social constructivisms in global and European politics: a review essay
Authors: Checkel Jeffrey T.
Published: March 2004

Social constructivism has come of age in contemporary international relations (IR) theory. Indeed, more and more submissions to presses and journals in both Europe and America characterise themselves as constructivist or situate their arguments vis à vis those of constructivists. In substantive terms and as the three books under review attest, constructivists also now offer detailed empirical studies that amplify and enrich their earlier conceptual and meta-theoretical critiques of mainstream approaches. Yet, as with any maturing research programme, there are gaps to be filled and challenges to be met. These include a better appreciation and theorisation of domestic politics; more explicit attention to research methods; further work on the linguistic turn so central to much of constructivism; and, finally, a rethink of attempts to build bridges.