bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vitro fertilization of two species of deer mouse eggs by homologous or heterologous sperm and penetration of laboratory mouse eggs by deer mouse sperm
Authors: Fukuda Y. , Maddock M. B. , Chang M. C. 
Published: June 2005

AbstractNewly ovulated eggs from immature deer mice (Peromyscus maniculatus and P. polionotus) and mature laboratory mice (Mus musculus) treated with PMSG and HCG were inseminated in vitro with spermatozoa recovered from the cauda epididymidis of mature males. The time required for capacitation of deer mouse sperm in culture was estimated to be about two to five hours based on the dispersal of sperm agglutination and increase of sperm motility. The rate of sperm penetration through the zona pellucida of deer mouse eggs by homologous or heterologous sperm was relatively high (72–91%) but that of laboratory mouse eggs by deer mouse sperm was low (20–21%). After penetration through the zona pellucida, a high proportion of deer mouse eggs (79–93%) were fertilized by homologous or heterologous deer mouse sperm but no laboratory mouse eggs were fertilized by sperm of two species of deer mice. The zona pellucida was dissolved in a higher proportion of laboratory mouse eggs cultured with P. maniculatus (45%) than with P. polionotus sperm (3.4%), but this did not happen by incubation of deer mouse eggs with homologous or heterologous sperm. It seems that there is little difference in sperm penetration and fertilization between these two closely related species of deer mice but the reactions between the mouse eggs and deer mouse sperm are quite different.
The effect of collagen on the cyclic AMP content of embryonic somites
Authors: Kosher Robert A. , Savage Mary P. 
Published: June 2005

AbstractPrevious studies have demonstrated that collagen substrates stimulate in vitro somite chondrogenesis, and that agents that elevate intracellular cyclic AMP levels inhibit the ability of somites to respond to the inductive influence of collagen. In the present investigation, radioimmunoassay was utilized to compare the cyclic AMP content of somite explants cultured on purified Type I collagen substrates with control explants cultured on Millipore filters. During the period of culture, the cyclic AMP content of collagen‐treated explants is significantly lower than the cyclic AMP content of control explants. The cyclic AMP content of collagen‐treated explants is 66% of control values as early as one hour following the initiation of culture, and the cyclic AMP content of collagen‐treated explants remains lower than controls throughout the 3day culture period. The greatest difference in the cyclic AMP content of collagen‐treated and control explants is observed at the seventeenth hour of culture, at which time the cyclic AMP content of collagen‐treated explants is 56% of controls. These results combined with previous studies provide support for the hypothesis that collagen elicits a reduction in the cyclic AMP content of embryonic somites and that this reduction is necessary to trigger chondrogenic differentiation.
Direct evidence for formation of hybrid vesicles by fusion of plasma and outer acrosomal membranes during the acrosome reaction in boar spermatozoa
Authors: Russell Lonnie , Peterson Rudolph , Freund Matthew 
Published: June 2005

AbstractA variety of treatment procedures was utilized to identify the origin and composition of the vesicles formed during the acrosome reaction of boar spermatozoa. Whether the acrosome reaction occurred spontaneously or was induced chemically the vesicles were hybrid vesicles composed of roughly equal proportions of plasma and outer acrosomal membranes.
Clarification of studies on the origin of thymic lymphocytes
Authors: Volpe E. Peter , Tompkins Robert , Reinschmidt Dana 
Published: June 2005

AbstractThe thesis that lymphocytes originate in situ by the direct transformation of epithelial cells within the thymic primordium in anurous frogs is untenable. On the contrary, in both the leopard frog and the African clawed toad, the lymphocytes that first appear in the embryonic thymus are derived from extrathymic lymphopoietc cells that invade the developing organ. The exact source of origin of the invading lymphopoietic cells remains problematic.
In vitro synthesis of RNA by Xenopus spermatogenic cells. I. Evidence for polyadenylated and non‐polyadenylated RNA synthesis in different cell populations
Authors: Kalt Marvin R. 
Published: June 2005

AbstractPremeiotic and postmeiotic (haploid) gene expression during spermatogenesis in the anuran, Xenopus laevis, was studied by analyzing the accumulation of radioactively labelled cytoplasmic polyadenylated [poly (A +) ] and non‐polyadenylated [poly (A ‐) ] RNAs. Dissociated spermatogenic cells were labelled and maintained in an in vitro system capable of supporting cell differentiation. Labelled cells were separated by density gradient centrifugation into subpopulations enriched for individual spermatogenic stages. RNA was extracted and purified from each cell fraction, and separated into poly (A +) and poly (A ‐) species. Comparison of poly (A +) to non‐poly (A) radioactivity in cells labelled with tritiated uridine or adenosine demonstrated that (1) all cell fractions produced significant quantities of polyadenylated RNA relative to total RNA synthesis; and (2) that a cell fraction enriched for pachytene spermatocyte RNA contained up to 15% of total cytoplasmic and 35% of total polysomal RNA labelled as poly (A +) containing species. RNA was also characterized by sucrose density gradient centrifugation and polyacrylamide gel electrophoresis. All cell types showed typical poly (A ‐) peaks of 4S, 18S and 28S, corresponding to tRNA (4S) and rRNAs (18, 28S) respectively. Spermatids and spermatozoa had additional absorbance peaks at 13 and 21S which cosedimented with Xenopus oocyte mitochondrial rRNA. Patterns of incorporation of uridine and adenosine into poly (A +) RNA in all germ cell fractions tested were complex. In all cases, major areas of radioactivity were found in a broad band sedimenting between 6–17S. Spermatid fractions showed a prominent peak of incorporation at 6–8S, while pachytene cells also showed heavier poly (A +) peaks in the 17–25S region. A non‐polyadenylated RNA species sedimenting at 6–8S with a relatively rapid rate of turnover was also observed in spermatids. From these results it is concluded that synthesis of transfer, ribosomal, and putative messenger RNA species continues in spermatogenic cells throughout all but the very last stages of spermatogenesis in Xenopus.
Neural control of light emission in Photuris larvae: Identification of Octopamine‐Sensitive adenylate cyclase
Authors: Nathanson James A. , Hunnicutt Edward J. 
Published: June 2005

AbstractOctopamine, a putative phenylethylamine neurotransmitter present in the firefly, has been found to be a potent stimulator of cyclic AMP synthesis in the larval light organ. In the same tissue, octopamine causes a small inhibition of phosphodiesterase activity. Because of the relatively simple anatomical relationships present in the larval light organ, compared with that of the adult, this preparation should offer an attractive model for studying the biochemistry of neurohumoral control of light emission.
Mouse embryo attachment to substratum and interaction of trophoblast with cultured cells
Authors: Glass Robert H. , Spindle Akiko I. , Pedersen Roger A. 
Published: June 2005

AbstractHatching, attachment, and trophoblast outgrowth of mouse embryos in vitro were examined as a model for implantation. Mouse embryos attached and grew out on glass cover slips that were partially covered with cultured mouse cells (L cells, liver cells, transformed JLS‐VII cells, and teratocarcinoma cells). Scanning electron microscopy showed that processes of these cells made contact with trophoblast, but there was no evidence of cell lysis or of phagocytosis of the cells by trophoblast. Time‐lapse cinematography showed that after contact the cultured mouse cells retracted from the trophoblast, which then spread into the areas vacated by those cells. This suggests a means by which the trophoblast gains entry into the endometrium without destruction of maternal cells.Neuraminidase (100 or 250 units/ml) had no effect on attachment of mouse embryos to glass. However, attachment was inhibited by trypsin at concentrations of 0.25%, 0.025%, and 0.0025%. Treatment of early blastocysts with diazooxonorleucine, an inhibitor of glycoprotein synthesis, decreased the number of embryos hatching from the zona pellucida; treatment at the late blastocyst stage decreased hatching to a lesser extent. Among the late blastocysts that did hatch, the number forming trophoblast outgrowths was lower than in controls. These results suggest that glycoproteins may be of importance for embryo hatching, attachment, and outgrowth.
Mammalian lung development: The possible role of cell proliferation in the formation of supernumerary tracheal buds and in branching morphogenesis
Authors: Goldin Geoffrey V. , Wessells Norman K. 
Published: June 2005

AbstractDuring the development of the lung, branching morphogenesis of the epithelium requires the presence of bronchial mesenchyme. Although it has been demonstrated that continuing morphogenesis is dependent upon growth through proliferation, there is no direct evidence to suggest that the specific pattern of branching is a consequence of differential mitotic activity which is influenced by the appropriate mesenchymal tissue. The induction of supernumerary buds in the tracheal epithelium of the mouse by transplantations of bronchial mesenchyme provides a means for analysing the role of cell proliferation in the formation of bronchial buds. We have addressed the problem by examining the ability of the tracheal epithelium, at different stages of development, to respond to bud induction by bronchial mesenchyme, and attempted to correlate this with the labeling index and 3H‐thymidine uptake in the trachea at the respective stages. It has been found that both the 11‐day‐old and 12‐day‐old tracheal epithelia initiate supernumerary buds in response to bronchial mesenchyme although the initiation in 12‐day‐old embryonic trachea occurred somewhat later than in the 11‐day‐old explants. The 13‐day‐old trachea failed to elicit buds after the tracheal mesenchyme had been stripped following treatment with 3% trypsin‐pancreatin. A decrease in cell proliferation in the tracheal epithelium (as revealed by autoradiography and scintillation counting following 5‐hour labeling with tritiated thymidine) between 11 and 13 days of development could contribute to these varying responses to bud induction. Further autoradiographic studies whereby the labeling index in the induced bud and the tracheal epithelium of the same explant have been compared, have revealed a continued high level of labeling in the branching bud and a concomitant decrease in labeling of the trachea. These data suggest that the bronchial mesenchyme either acts as a mitotic stimulator or provides conditions permissive to continued mitotic activity.
The gill arch of the mullet, Mugil cephalus. II. Modification in surface ultrastructure and Na,K‐ATPase content during adaptation to various salinities
Authors: Hossler Fred E. , Ruby John R. , McIlwain Thomas D. 
Published: June 2005

AbstractThe effect of salinity changes on the surface ultrastructure and Na, K‐ATPase content of the gill filament of mullent was determined using scanning electron microscopy and 3H‐ouabain binding. The number of ouabain binding sites/mg wet weight of tissue increased with increasing salinity. Mullet adapted to fresh water, or to salinities of 10, 26 and 45 g salt/liter exhibited ouabain binding capacities of about 1, 2, 4 and 5 pmoles ouabain bound/mg wet weight of tissue. Ouabain binding was strongly effected by ATP and KCI, whereas bound 3H‐ouabain was uneffected by the addition of unlabelled ouabain. Similarly, epithelial pores on the filament surfaces exhibited ultrastructural features which were indicative of the various salinities to which the fish were adapted. In fresh water, the pores were broad (average diameter 3‐6 μ) and shallow, and a cellular mass protruded from the pores above the epithelial surface. In 10 g salt/liter, the pores averaged 1–5 μ in diameter, were slightly deeper, and contained obvious, protruding cellular extensions. In 45 g salt/liter, the pores were narrower (average diameter 1–3 μ), considerably deeper, and exhibited fewer, less obvious cellular extensions in their interior. Because the pores likely represent the apical pits of ion secreting chloride cells and because the Na, K‐ATPase has been localized in chloride cells, these observations likely represent two different manifestations of the same process, adaption of chloride cells for osmotic regulation.
Mechanisms of ammonia and acid extrusion by the little skate, Raja erinacea
Authors: Evans David H. , Kormanik Gregg A. , Krasny Edward J. 
Published: June 2005

AbstractThe little skate (Raja erinacea) excretes ammonia and titratable acid at a rate of 6.37 and 40–95 μM. 100g‐1. hr‐1, respectively, at an external pH of 7.8 to 8.0. Transfer into Na‐ and K‐free artifical sea water does not alter the rate of ammonia efflux but reduces titratable acid efflux to zero. Addition of amiloride (10‐4M) to the external sea water does not alter the ammonia efflux but reduces the titratable acid efflux by 49%. Thus, while ammonia efflux is apparently not via Na (or K)/NH4 exchange, excretion of titratable acid is apparently via Na (or K)/H exchange.
Enzyme changes accompanying thermal acclimation in two species of pleurocerid snails
Authors: Pugh Charles R. , Ultsch Gordon R. , Lindahl Ronald 
Published: June 2005

AbstractGoniobasis cahawbensis is a stream snail that experiences an annual temperature cycle. G. cochliaris is limited in distribution to springs, and their immediate vicinities, which are characterized by nearly constant annual temperatures. The present study sought to determine whether temperature dependent biochemical differences exist that might account for the differential distribution of these congeneric pleurocerid snails.Eight enzymes were examined following acclimation to 10°, 17° and 24°C. No significant temperature dependent qualitative differences in enzyme phenotypes were demonstrable in either species by starch‐gel electrophoresis for malate dehydrogenase, glucose‐6‐phosphate dehydrogenase, phosphogluconate dehydrogenase, phosphoglucomutase, superoxide dismutase and acetyl and butyryl esterases. Significant quantitative differences were observed in three of these enzymes. G. cahawbensis cytosol malate dehydrogenase activity increased significantly with increasing acclimation temperature, while G. cochliaris malate dehydrogenase activity remained unchanged. The activities of glucose‐6‐phosphate dehydrogenase did not differ significantly between acclimation temperatures for either species; however, the overall activity of both enzymes was significantly higher for G. cochliaris. Appreciable levels of LDH activity were not demonstrable by electrophoresis or enzymatic assay.
The time and location of the acrosome reaction during sperm transport in the female rabbit
Authors: Overstreet J. W. , Cooper G. W. 
Published: June 2005

AbstractMotile spermatozoa with lifted or absent acrosomal caps (“reacted acrosomes”) were observed by phase contrast microscopy exclusively in the oviduct of the rabbit reproductive tract during the first 16 hours post coitum (p.c.). They were first identified at six hours p.c. in flushings from the lower isthmus of the oviduct and were present in both the lower and upper isthmus two hours later. Motile spermatozoa with reacted acrosomes appeared in the lower ampulla (the site of fertilization) at ten hours p.c. Such spermatozoa were obtained from all regions of the oviduct at 12 and 16 hours p.c. but they always constituted a minority of the freely swimming spermatozoa recovered. The percentage of spermatozoa with activated motility was higher following the acrosome reaction, and their apparent swimming speeds were lower than those of intact spermatozoa. The role of ovulation in the induction of acrosome reactions was studied in females artificially inseminated per vaginam (AI), with or without the induction of ovulation, and in females mated either two hours before or two hours after ovulation. The proportion of motile spermatozoa with reacted acrosomes in the isthmus and ampulla of non‐ovulatory females 12 hours after AI was similar to their proportions in these regions 12 hours after mating or 12 hours after AI with induced ovulation. Four hours after delayed matings, i.e., two or six hours after ovulation, motile spermatozoa were confined to the tubal isthmus and none had undergone the acrosome reaction. These findings indicate that the products of ovulation and the endocrine changes associated with ovulation in the rabbit need not be directly involved in the induction of the acrosome reaction in vivo.
Neurites grow faster towards the cathode than the anode in a steady field
Authors: Jaffe Lionel F. , Poo Mu‐Ming 
Published: June 2005

AbstractWe explanted fragments of embryonic chick dorsal root ganglia on to polylysine coated glass and cultured them in a medium containing one unit of nerve growth factor plus enough methylcellulose to give viscosities from 0.01–3,000 poise. We allowed them to grow out in the absence of a field, and then selected explants with halos of neurites which were relatively dense, relatively symmetrical, and practically free of glial cells. These selected explants were then exposed to electrical fields of up to 140 mV/mm for some hours.In media with viscosities of one poise or less, the field some times dragged the central cell mass of an explant towards the anode. However, in cases where the central cell mass did notmove, fields of 70–140 m V/mm induced that sector of each neurite halo which faced the cathode to grow out several times faster than the one facing the anode.This neurite growth response showed little or no dependence upon viscosity (although it was inhibited by movements of the central cell mass). We speculate that it is mediated by lateral electrophoresis of the receptors for nerve growth factor along the plasma membranes of the neurites.
Possible adaptive significance of low red cell organic phosphates in crocodiles
Authors: Grigg Gordon C. , Gruca Margie 
Published: June 2005

AbstractAt similar conditions of temperature and PCO2 whole blood oxygen affinity of C. porosus is similar to that of its hemolysate as measured by other authors. Like other crocodilians so far measured, C. porosus, C. novaeguinea and C. johnstoni have low levels of red cell organic phosphates. A major role of CO2 in determination of oxygen affinity has been described previously for hemolysates of C. porosus and we confirm this in whole blood. Interestingly, however, O2 affinity may be less sensitive to pH. Low oxygen affinity, insensitivity of O2 affinity to organic phosphates, and low levels of red cell organic phosphates are features that C. porosus shares with mammals having low red cell 2,3‐DPG. These mammals share with C. porosus a capability for shortlived bursts rather than sustained activity.At low levels of organic phosphate it is known for human blood that the fixed‐acid Bohr effect is much reduced. We propose that lowering red cell organic phosphates may be an adaptive strategy to reduce the fixed acid Bohr‐effect in animals subject to large changes in plasma pH. Such changes may be associated with a prolonged dive or other behavioural event which depends on anaerobic glycolysis.
The Wind‐Kessel effect of the bulbus arteriosus in trout
Authors: Farrell A. P. 
Published: June 2005

AbstractPressure/volume curves were determined for the bulbus arteriosus and ventral aorta. The curves show a high degree of compliance over the 40 to 60 cm H2O pressure range, a range that is similar to ventral aortic blood pressures in trout. Hypoxic, adrenergic and cholinergic treatments all altered the shape of the pressure/volume curves. Arterial blood flow is therefore depulsed in vivo and the extent of depulsation may be regulated.
Electrophoretic analyses of lactate dehydrogenase C4 in testes and vesicular glands of normal and male sterile translocation mice
Authors: Holmes Roger S. , Andrews Sandra , Jones Janet T. 
Published: June 2005

AbstractLactate dehydrogenase (LDH) C4 activity was observed in testis extracts from normal mice but was progressively reduced in mice carrying the male‐sterile translocations T31H, T32H, T37H, T38H, T40H and T42H, with no detectable activity being observed in the last two mice. None of the vesicular gland extracts from these male‐steriles showed LDH‐C4 activity, unlike normal mice. The differential LDH‐C4 activity in male‐sterile testes is interpreted as reflecting the varying stages of the spermatogenic defect during meiosis. In general, early meiotic defects exhibited no LDH‐C4 activity whereas late stage (usually after metaphase‐1 stage) defect animals exhibited some activity. The results also provide evidence for contaminating sperm being the source of normal vesicular gland LDH‐C4 activity.
The interaction of nerves of opposite regenerating polarity in fused newt forelimbs
Authors: Goshgarian Harry G. 
Published: June 2005

AbstractPrevious studies involving nerve interactions and limb regenerative processes were carried out on adult newts after their forelimbs were amputated through the distal radius and ulna and fused end‐to‐end. On the basis of limb regeneration results at the junction of the fused limbs, it was postulated that regenerating nerves from each limb (i.e., nerves of opposite polarity) would not invade the foreign territory of the contralateral limb if it were already normally innervated. A direct study of this nerve interaction, however, was not made in this earlier study. The present investigation was designed to obtain direct histological and electrophysiological evidence for the interaction of nerves of opposite regenerating polarity in fused newt forelimbs. The primary objective was to determine how the regenerating nerves would interact in the establishment of innervation territories—first, at the fusion zone, which represents the junction of the normal innervation territories of the nerves of each limb; and secondly, half way up one of the limbs, where interaction would occur in a territory normally innervated by only one of the regenerating nerves. The results showed that when nerves of opposite regenerating polarity approached one another at the junction of the fused limbs a discontinuation of axonal growth occurred; no indication of overlap of nerves into foreign territory was seen. When the nerves were allowed to interact within one of the fused limbs, however, an overlap of nerve fibers and a functional “double innervation” of that limb was demonstrated. These results are discussed in terms of possible mechanisms for the establishment of innervation territories in salamander limbs. The question of nerve‐muscle reinnervation specificity is also raised.
The first appearance of muscle spindles in the iliofibularis muscle of the frog during metamorphosis
Authors: Butler Richard 
Published: June 2005

AbstractThe iliofibularis muscle of the frog was studied histologically at different developmental stages during metamorphosis in order to determine when muscle spindles first appear. The earliest stage at which spindles were positively identified was stage XVIII, and they appear relatively complete as judged by their morphology. An analysis of the reports of variations in the numbers of neurons in frog spinal ganglia suggest that muscle spindles may in fact be induced as early as stage X.