bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gonadotropin‐releasing hormone in the molly Poecilia latipinna: Molecular form, quantity, and location
Authors: Coe Imogen R. , Grier Harry J. , Sherwood Nancy M. 
Published: June 2005

AbstractThe molecular forms of gonadotropin‐releasing hormone (GnRH) present within the brain of the teleost Poecilia latipinna were characterized using high‐performance liquid chromatography (HPLC) and radioimmunoassay (RIA). The forms present appear to be similar to the previously identified forms of salmon GnRH and chicken GnRH‐II. Immunocytochemical studies showed the presence of GnRH‐immunoreactive cells in the posterior ventral telencephalon, preoptic area, and midbrain tegmentum. One male fish possessed immunoreactive cells in the nucleus glomerulosus, an area which has not previously been reported to contain GnRH containing cells. GnRH fibers were found extensively throughout the brain, located within the telencephalon, the optic tectum, the hypothalamus, and the midbrain. © 1992 Wiley‐Liss, Inc.
Quantification and localization of ornithine decarboxylase in the embryonic palate
Authors: Gawel‐Thompson Kathleen J. , Greene Robert M. 
Published: June 2005

AbstractOrnithine decarboxylase (ODC; EC4.1.1.17), the key enzyme in polyamine biosynthesis, and intracellular polyamines increase rapidly and markedly in tissues and cells that are actively proliferating as well as differentiating and decrease as these processes cease. ODC activity has also been implicated as playing a role in the proliferation and differentiation of cells derived from the developing palate. Ornithine decarboxylase activity was thus quantified and ODC localized in the developing murine palate in vivo. Levels of ODC activity showed little variation during the ontogeny of the palate, averaging 126 pmol CO2/mg protein/hr. When difluoromethylornithine (DFMO), an irreversible inhibitor of ODC activity, was administered to pregnant mice throughout the period of palate development (days 11–14), palatal tissue ODC activity was reduced by 85%. No craniofacial malformations were observed, however. The lack of a teratogenic effect by DFMO treatment could be due to sufficient remaining ODC activity in craniofacial tissue and/or maintenance of intracellular polyamine levels by the activity of a polyamine transport system. The activity of this system was demonstrated by the ability of palatal tissue in vivo to take up radiolabeled putrescine. The presence of a polyamine transport system was previously suggested by the demonstration of such a system in palate mesenchymal cells in vitro.Dramatic temporal and spatial shifts in tissue patterns of immunolocalization for ODC in developing palatal tissue were also seen. Immunostaining for ODC was evenly distrubuted in oral, nasal, and medial edge palate epithelial cells on day 12 of gestation. The basal aspects of epithelial cells were, however, more intensely stained. Mesenchymal cells exhibited a peri‐nuclear immunostaining pattern. On days 12 and 13 of gestation, the staining patterns for ODC in palate epithelial and mesenchymal cells were comparable. On day 14 of gestation, all regions of the palate epithelium, particularly the medial edge epithelia, were immunostained for ODC, whereas the intensity of staining in the mesenchymal cells was significantly reduced. This study represents essential initial observations toward understanding the role that ODC may play in normal craniofacial development. © 1992 Wiley‐Liss, Inc.
Characterization of leukotriene C4 binding sites in the brain of the American bullfrog, Rana catesbeiana
Authors: Herman Ceil A. , Charlton Gregory A. , Chiono Matt 
Published: June 2005

AbstractIn this study, specific binding sites for [3H]‐LTC4 on membrane preparations from American bullfrog (Rana catesbeiana) brain were characterized. Binding assays were done in the presence of serine (5mM) borate (10 mM) for 30 min at 23°C. Under these conditions, no metabolism of LTC4 to LTD4 occurred. Specific binding of [3H]‐LTC4 reached steady state within 10 min, remained constant for 60 min, and was reversible with the addition of 1,000‐fold excess unlabelled LTC4. Scatchard analysis of the binding data indicated a single class of binding sites with an estimated Kd of 89.83 nM and Bmax of 43.79 pmol/mg protein. Competition binding studies demonstrated that LTD4 and LTE4 were ineffective in displacing [3H]‐LTC4 from its binding site. The Ki for LTC4 was 51 nM. S‐decylglutathione, glutathione and hematin had Ki values of 44, 312,602, and 25,576 nM, respectively. The mammalian cysteinyl leukotriene antagonist L‐660,711 inhibited specific binding of [3H]‐LTC4, with a Ki of 87,149 nM. Guanosine‐5′‐0‐3‐thiotriphosphate (GTPγS) did not affect specific binding of [3H]‐LTC4 indicating that, like mammalian LTC4 receptors, a Gi protein is not involved in the transduction mechanism. The LTC4 binding site in bullfrog brain demonstrates both similarities and differences from its mammalian counterpart. © 1992 Wiley‐Liss, Inc.
The problem of the number of tarsomeres in the regenerated cockroach leg
Authors: Tanaka Akira , Akahane Hitomi , Ban Yukari 
Published: June 2005

AbstractThere are 5 tarsomeres in the normal cockroach leg, but this number is often reduced in regenerated legs. In order to examine this complicated situation, fore‐, mid‐, and hindlegs of German cockroaches were amputated at 11 different tarsal levels and at 18 different times during the last instar. When tarsi were amputated at or proximal to the 3rd tarsomere, 4‐segmented tarsi regenerated. When legs were amputated distal to the 3rd tarsomere, the regenerated tarsi had 5 segments. Three‐segmented tarsi rarely regenerated when legs were amputated proximal to the 3rd tarsomere and in the latter half of the instar period. The lengths of all tarsomeres of regenerated tarsi were measured together with those of unoperated contralateral tarsomeres, and the ratios of the former to the latter were calculated. The ratios ranged from 28 to 138% for the various tarsomeres and levels of amputation. From a comparison of the ratios and morphological observations, it was suggested that the 3rd tarsomere of the normal 5‐segmented tarsus has disappeared in the regenerated 4‐segmented tarsus. Pads and disto‐lateral spines of tarsomeres were observed on unoperated and regenerated tarsi. It was of interest that double spines were often found on the 4‐segmented tarsi, mostly on the 2nd tarsomere, just proximal to the position of the missing 3rd tarsomere. This observation supported the idea that the 3rd tarsomere has not simply disappeared, but has probably fused with the 2nd tarsomere. © 1992 Wiley‐Liss, Inc.
Immunological characterization of oviductal glycoproteins associated with the zona pellucida of the golden hamster egg
Authors: Abe Hiroyuki , Ookata Kayoko , Abe Miki , Oikawa Taneaki 
Published: June 2005

AbstractThree monoclonal antibodies (MAbs) were produced against materials obtained from the golden hamster oviduct. The MAbs (C11E8, C8B11, and A3D5) selectively reacted with the zona pellucida (ZP) of oviductal eggs. An immunohistochemical study demonstrated that all MAbs bound strongly to the epithelial cells of the oviduct and, to a lesser extent, of the uterus, the cervix, and the vagina. Weak reactions were also observed with some other tissues. All immunohistochemical reactions were completely eliminated by treatment of tissues with periodic acid, suggesting that the antigenic determinants that react with the MAbs are carbohydrate in nature. Antigens that reacted with the MAbs were characterized by immunoblotting analyses of 1‐ or 2‐dimensional polyacrylamide gels after electrophoresis to fractionate tissue extracts under reducing conditions. With the oviductal extract, C11E8 and A3D5 specifically bound to broad bands that corresponded to macromolecules of more than 200 and 160 kD, respectively, whereas C8B11 reacted with a broad range of macromolecules, with the strongest reactivity being detected at molecular weights (MWs) higher than 160 kD. The macromolecules that reacted with the MAbs had carbamilation trains, suggestive of extensive microheterogeneity with respect to charge and size. Similar substances of high MW were not detected in extracts of tissues from the other reproductive organs. In addition, one MAb‐positive oviductal antigen bound to the ZP of ovarian eggs, but the others did not bind to the ZP of ovarian eggs. This result indicates that the binding activity is specific for the oviductal glycoproteins. We have thus established clones that produce 3 different MAbs with strong affinity for oviduct‐specific glycoproteins, one of which is associated with the ZP of the golden hamster. © 1992 Wiley‐Liss, Inc.
Inhibition of Ca2+ uptake in freshwater carp, Cyprinus carpio, during short‐term exposure to aluminum
Authors: Verbost Pieter M. , Lafeber Floris P. J. G. , Spanings Franciscus A. T. , Aarden Elisabeth M. , Bonga Sjoerd E. Wendelaar 
Published: June 2005

AbstractIn carp exposed to pH 5.2 in fresh water, the Ca2+ influx from the water is reduced by 31% when compared to fish in water of neutral pH. At pH 5.2, the Ca2+ influx but not Na+ uptake is decreased by aluminum (Al). Al reduces Ca2+ influx dose‐dependently: a maximum 55% reduction was observed after 1–2 h exposure to 200 μg·1−1 (7.4 μM) Al. Branchial Ca2+ efflux is less sensitive to Al and affected only by exposure for more than 1 h to high Al concentrations. Na+ influx is not affected by concentrations Al up to 400 μg·1−1. Na+ efflux, similarly to Ca2+ efflux, increased when fish were exposed for more than 1 h to 400 μg·l−1 Al. © 1992 Wiley‐Liss, Inc.
Mechanisms by which calcium ionophore and phorbol ester modulate steroid production by goldfish preovulatory ovarian follicles
Authors: Kraak Glen Van Der 
Published: June 2005

AbstractRecent studies have shown that agents that increase intracellular calcium content (calcium ionophore A23187) and activate protein kinase C (phorbol 12‐myristate 13‐acetate; PMA) modulate basal and cAMP‐stimulated steroid production by goldfish preovulatory ovarian follicles. This report describes studies evaluating sites in the steroidogenic cascade (pre‐ and postadenylyl cyclase) influenced by calcium and protein kinase C. PMA (12.5–400 nM) inhibits hCG stimulated cAMP production, whereas phorbol 12, 13‐dideconate, an inactive phorbol ester that does not activate protein kinase C, was without effect. Earlier studies suggested that PMA also acts post cAMP formation, but this action was shown to be exerted prior to cholesterol side‐chain cleavage as metabolism of 25‐hydroxycholesterol to testosterone was not inhibited by PMA. A high dosage of A23187 (4000 nM) inhibited the stimulatory action of hCG on cAMP and testosterone production; lower dosages of A23187 were without effect. In contrast, a wide range of A23187 dosages (250–4,000 nM) enhanced conversion of 25‐hydroxycholesterol to testosterone. This effect appears to be exerted at the level of the cholesterol side‐chain cleavage enzyme as A23187 did not affect conversion of exogenous pregnenolone to testosterone. These data demonstrate specific regulatory actions of calcium and protein kinase C at multiple sites in the steroidogenic cascade both proximal and distal to cAMP generation. © 1992 Wiley‐Liss, Inc.
Development of the chick chorioallantoic capillary plexus under normoxic and normobaric hypoxic and hyperoxic conditions: A morphometric study
Authors: Burton G. J. , Palmer M. E. 
Published: June 2005

AbstractFertile eggs from the domestic fowl were incubated under normobaric normoxic (21% O2), hypoxic (14% O2), and hyperoxic (40% O2) conditions in order to examine the influence of the prevailing oxygen level on the growth and maturation of the chorioallantoic memorane. Eggs were sampled at regular stages throughout incubation for morphometric analysis. Under normoxic conditions, maturation of the capillary plexus occurred in two distinct stages, both of which contributed to a reduction in the thickness of the air‐blood barrier. Between days 6 and 10, the capillaries sprouted and fused to form a dense plexus. Subsequently, between days 10 and 14, this plexus invaginated into the chorionic epithelium. Differentiation of the chorioallantoic membrane appeared maximal by the end of this period. Hypoxia resulted in diminished growth of the embryo and chorioallantoic membrane, but in accelerated maturation of the capillary plexus. Hyperoxia had a less marked effect but appeared to retard the final invagination of the plexus, resulting in a thicker air‐blood barrier. © 1992 Wiley‐Liss, Inc.
An aerodynamic valve in the avian primary bronchus
Authors: Wang Ning , Banzett Robert B. , Nations Christopher S. , Jenkins Farish A. 
Published: June 2005

AbstractThe segmentum accelerans in geese is a constriction in the caudal end of the primary bronchus. Experimental evidence suggests that this part of the airway functions as an inspiratory aerodynamic valve, accelerating the incoming airstream past the ventrobronchial openings. The luminal diameter of the segmentum accelerans dilates in the presence of elevated CO2 levels, probably through relaxation of smooth muscle. Physiological control of the segmentum acelerans may permit inspiratory aerodynamic valving to be maintained throughout a wide range of ventilatory flows. © 1992 Wiley‐Liss, Inc.
Acid‐base regulation in pulmonate molluscs
Authors: Barnhart M. Christopher 
Published: June 2005

AbstractEvidence is presented for a role of CO2 in acid‐base regulation by air‐breathing gastropods. In the land snail Otala lactea, alterations of PCO2 account for pH adjustment during acute temperature change and in compensation for metabolic acidosis. CO2 release from the gastropod lung appears to be more closely coupled with ventilation than is O2 uptake, because O2 uptake is limited to a greater extent by diffusion through the lung epithelium. Cutaneous CO2 release may account for half of CO2 release from active snails, and the loss of this route during withdrawal into the shell partly accounts for elevation of CO2 during dormancy. Further CO2 accumulation and consequent acidosis during dormancy is attributable to hypoventilation of the lung. Although respiratory acidosis appears to be involved in metabolic depression during dormancy, the mechanism of influence on cellular metabolism is unknown and is probably indirect. Unlike the respiration of whole animals, respiration of isolated tissues of Otala is insensitive to PCO2. © 1992 Wiley‐Liss, Inc.
Mechanisms of ion and acid‐base regulation at the gills of freshwater fish
Authors: Goss G. G. , Perry S. F. , Wood C. M. , Laurent P. 
Published: June 2005

AbstractThis review examines the branchial mechanisms utilized by freshwater fish to regulate internal acid‐base status and presents a model to explain the underlying basis of the compensatory processes. Rainbow trout, Oncorhynchus mykiss, and brown bullhead, Ictalurus nebulosus, were examined under a variety of experimental treatments which induced respiratory and metabolic acid‐base disturbances. Acid‐base regulation was achieved by appropriate adjustments of Na + and Cl− net fluxes across the gills which, in turn, were accomplished by variable contributions of three different branchial mechanisms: 1) differential changes in Na+ and Cl− diffusive effluxes, 2) changes in internal substrate (H+, HCO3 −) availability, and 3) morphological adjustments to the gill epithelium. Differential diffusive efflux of Na+ over Cl− was involved only during periods of metabolic alkalosis. The importance of internal substrate availability was demonstrated using a two‐substrate model. According to the model, ionic flux rates (JinCl−, JinNa +) are determined not only by the concentration of the external ion (Na+, Cl−) but also by the concentration of the internal counterion (H+, HCO3−). This system provides for an “automatic negative feedback” to aid in the compensation of metabolic acid‐base disturbances. Morphological alteration of the gill epithelia and the associated regulation of chloride cell (CC) fractional area is an essential third mechanism which is especially important during respiratory acid‐base disturbances. Specifically, fish vary the availability of the CC associated Cl−/HCO3 − exchange mechanism by physical covering/uncovering of CCs by adjacent pavement cells. © 1992 Wiley‐Liss, Inc.
Control and consequences of adrenergic activation of red blood cell Na+/H+ exchange on blood oxygen and carbon dioxide transport in fish
Authors: Thomas Serge , Perry Steve F. 
Published: June 2005

AbstractThe catecholamines, adrenaline and noradrenaline, are released into the circulation of fish during a variety of physical and environmental disturbances that share the common feature of a requirement for enhanced blood oxygen transport. Indeed, the dominant factor controlling the mobilization of catecholamines from chromaffin tissue is a depression of blood oxygen content usually coinciding with a reduction of hemoglobin‐O2 (Hb‐O2) binding to 50–60% saturation. The elevation of plasma catecholamine levels, under such conditions, activates a β‐adrenergic cyclic AMP‐dependent Na + /H+ exchanger on the red blood cell (rbc) membrane. The adrenergic responsiveness of the rbc Na + /H+ exchanger to catecholamines varies both within and between species. Such inter‐ and intra‐specific differences may reflect, in part, the availability of cell surface β‐adrenoceptors that are functionally coupled to adenylate cyclase.The activation of rbc Na + /H + exchange and the accompanying profound adjustments of intracellular and extracellular acid‐base status, nucleoside triphosphate (NTP) levels, and cooperativity of Hb‐O2 binding have important consequences on both O2 and CO2 transfer and transport in the blood that vary markedly at the sites of oxygenation (the gill) and deoxygenation (the tissues) thereby enabling simultaneous amelioration of O2 loading and unloading. At the gill, oxygen transfer is enhanced owing to increases in Hb‐O2 affinity and capacity while at the tissues, oxygen delivery is facilitated by a reduction of Hb‐O2 affinity. This reduction in affinity at the tissues is a consequence of the combined effects of increased cooperativity of Hb‐O2 binding and a rise in venous PCO2 (PvCO2) caused by the titration of HCO3 − by H+ extruded by the rbc Na + /H+ exchanger. This elevation of PvCO2 may contribute to the rise in arterial PCO2 (PaCO2) observed after adrenergic activation of rbc Na + /H+ exchange that is caused primarily by impairment of rbc CO2 excretion related to modification of the intracellular acid‐base status. © 1992 Wiley‐Liss, Inc.
Tissue specificity of crustacean tropomyosin
Authors: Miyazaki Jun‐Ichi , Makioka Toshiki , Fujiwara Yoshihiro , Hirabayashi Tamio 
Published: June 2005

AbstractThe tropomyosin isoform distribution in muscle and nonmuscle tissues of crustaceans was investigated by two‐dimensional gel electrophoresis and immunoreplica tests. All five crustacean species examined in this study showed extensive molecular heterogeneity and tissue specificity of tropomyosin. The results were different from those previously reported with the horseshoe crab, that is, horseshoe crab tropomyosin was heterogeneous but not tissue‐specific. In this respect, therefore, the distribution of crustacean tropomyosin isoforms is more similar to that of vertebrate tropomyosin isoforms rather than that of horseshoe crab tropomyosin isoforms. Furthermore, crustacean nonmuscle tissues contained tropomyosin isoforms of high electrophoretic mobilities, which were possible counterparts of so‐called vertebrate nonmuscle isoforms of low molecular weights. However, it is rather difficult to expect that each tropomyosin isoform has a tissue‐specific function, since the patterns of isoform composition were not consistent among the examined crustaceans except for those of cardiac isoforms, which were unique to the hearts in all the examined crustaceans and correlated with the expression of presumed actin of compound peptides, which specifically appeared in the hearts. Therefore, the cardiac isoforms of crustacean tropomyosin are suggested to play tissue‐specific regulatory roles. © 1992 Wiley‐Liss, Inc.
Presence of gonadotropin‐releasing hormone immunoreactivity in dogfish and skate brains
Authors: Lovejoy D. A. , Ashmead B. J. , Coe I. R. , Sherwood N. M. 
Published: June 2005

AbstractGonadotropin‐releasing hormone (GnRH) immunoreactivity was studied in two species of elasmobranchs, spiny dogfish (Squalus acanthias) and black skate (Bathyraja kincaidii). Immunoreactive material in brain sections was identified using the avidin‐biotin technique with the horseradish peroxidase reaction. Although there were a few GnRH immunoreactive cells, GnRH fibers were greatest in the telencephalon of both species and were associated primarily with the terminal nerve system. In the dogfish, many immunoreactive fibers extended towards the ventromedial surface of the caudal forebrain. This site may be the locus for neurosecretion. GnRH fibers were found in the preoptico‐hypophyseal tract of dogfish, but not in the media eminence or pituitary. Immunoreactive material was less abundant in other regions of the brain, although a diffuse fiber network throughout the brain including the brain stem was observed. © 1992 Wiley‐Liss, Inc.
Analysis of puberty‐accelerating pheromones
Authors: Price Monica A. , Vandenbergh John G. 
Published: June 2005

AbstractTwo experiments were performed to test putative puberty‐accelerating pheromones. In the first experiment, 37 weanling female house mice of the ICR strain were exposed to 1 of the following 3 treatments: an airborne mixture of 0.05 M isoamylamine and 0.05 M isobutylamine, fresh male mouse urine, or distilled water, as the control. Neither the amine mixture nor the male urine accelerated first estrus in the mice following airborne exposure to these compounds. In the second experiment, 37 weanling female mice of the same strain were exposed to the same chemicals as in the first experiment by direct contact to the oro‐nasal groove. The mixture of isoamylamine and isobutylamine did not accelerate puberty, but direct contact with the male urine accelerated puberty as evidenced by uterine weights. © 1992 Wiley‐Liss, Inc.
Intratesticular control of spermatogenesis in the frog, Rana esculenta
Authors: Minucci Sergio , Di Matteo Loredana , Fasano Silvia , Baccari Gabriella Chieffi , Pierantoni Riccardo 
Published: June 2005

AbstractAdult intact and hypophysectomized (PDX) frogs, Rana esculenta, were treated with a gonadotropin releasing hormone agonist (GnRHA, HOE 766) and/or cyproterone acetate (CPA), the antiandrogen, in order to investigate the regulation of primary spermatogonial (I SPG) multiplication in vertebrates. Treatment with GnRHA (injections containing 900 ng administered for 12 days on alternate days) caused a significant increase of the mitotic index (MI) of I SPG in PDX animals and a further MI increase of SPG was observed when 0.66 mg CPA was given concomitantly with GnRHA. The treatment with 0.66 mg CPA in combination with GnRHA also increased secondary spermatocyte (II SPC) appearance. Moreover, number of nests containing spermatids (SPT) decreased as CPA, in combination with GnRHA, was administered in increasing doses (0.33 and 0.66 mg/injection). Intact animals treated with CPA (0.66 mg/injection) showed a time‐dependent I SPG multiplication increase which reached highest values after 28 days. Secondary SPC also proliferated until day 28; meanwhile the number of nests containing SPT decreased. Neither testosterone nor R5020 (a progestin which is not converted to androgens) modified the basal and GnRHA‐induced spermatogonial proliferation. These results confirm that in the frog, Rana esculenta, spermatid formation is impaired by CPA treatment and that I SPG multiplication is enhanced by a direct effect of GnRHA; moreover, we suggest that the abence of spermatides constitutes a signal promoting spermatogonial proliferation. © 1992 Wiley‐Liss, Inc.