bluuebunny/crossref_metadata_2025_split huggingface dataset:
A possible effect of the Na+ concentration in oviductal fluid on amino acid uptake by cleavage‐stage mouse embryos
Authors: van Winkle Lon J. , Campione Allan L. , Kester Samara E. 
Published: June 2005

AbstractTwo‐ and four‐cell mouse embryos exhibited both Na+‐dependent and Na+‐independent components of zwitterionic α‐amino acid transport, which we tentatively ascribe to the A and L amino acid transport systems, respectively. Uptake of taurine was virtually all Na+‐dependent and is probably via the β system. Na+‐independent L‐lysine uptake by two‐cell embryos may have been via system y+. The small amount of lysine transport which was Na+‐dependent (30% of the total) could not be attributed to any well known transport system and may have been due to the early ontogenetic expression of a newly described transport system which predominates in preimplantation blastocysts. We conclude that the rate of Na+‐dependent amino acid transport in two‐cell mouse embryos could be significantly affected in situ by changes in the [Na+] which are known to occur in oviductal fluid.
The 3, 4‐didehydroretinal chromophore of goldfish porphyropsin
Authors: Tsin Andrew T. C. , Santos Frank R. 
Published: June 2005

AbstractThe isomeric configuration of the 3,4‐didehydroretinal chromophore of goldfish porphyropsin was determined by high performance liquid chromatography (HPLC) and by the regeneration of this visual pigment with authentic isomers of 3,4‐didehydroretinal. A nonisomerizing, quantitative method using hydroxylamine and methylene chloride was employed to extract the 3,4‐didehyroretinal chromophore from the rod outer segment membrane (containing the porphyropsin). When this extracted chromophore was injected into the HPLC, only a single major peak was observed and this peak coeluted with the authentic 11‐cis 3,4‐didehydroretinyl oxime. This suggests that the chromophore of goldfish porphyropsin is 11‐cis 3,4‐didehydroretinal. When the bleached rod outer segments (containing the opsin) were incubated with different 3,4‐didehydroretinal isomers (13‐cis, 11‐cis, 9‐cis, and all‐trans), only the 11‐cis isomer resulted in the degeneration of porphyropsin. This also suggests that the porphyropsin chromophore exists in the 11‐cis configuration.
Surface contractile activity associated with isolated asters in cylindrical sand dollar eggs
Authors: Rappaport R. , Rappaport Barbara N. 
Published: June 2005

AbstractThe purpose of this investigation was to explore the capacity of isolated asters of the mitotic apparatus of elicit contractile activity in adjacent cell surface. When a fertilized Echinarachnius parma egg with an intact mitotic apparatus was confined in an 82‐μm‐i.d. silicone rubber capillary, the furrow developed at the midpoint between the asters. The mitotic apparatus could be broken by inserting and ejecting the egg from the capillary. The asters of a broken mitotic apparatus were usually abnormally far apart. When asters were as far as 68 μm apart, furrowing occurred; when the intervening distance was greater, there was no furrowing. When the asters were too far apart to establish a furrow between them, constrictions appeared adjacent to one of the asters. The constrictions could shift or could cut through the asters that appeared to elicit them. Cylindrical cells in 0.015 M ethyl urethane formed furrows when the mitotic apparatus was intact but formed neither furrows nor astral constrictions when the asters were far apart. Astral constrictions did not form in the presence of an active furrow. They were frequently temporary and they appeared to be slower and less acute than normal furrows. Single asters remaining after half of the amphiaster was removed had the same effect as widely separated asters. The form of the constriction was related to the position of the aster in the cylinder. When the aster was centered, the constriction resembled a furrow; but when it was near one of the poles, the adjacent surface pulled away from the capillary wall and the radius of curvature at the pole decreased. When initially distant asters were pushed together, a furrow formed between them. These results contribute to a better understanding of the interaction between the mitotic apparatus and the egg surface and the formation of the cleavage mechanism.
Inhibition of nuclear maturation in fully grown porcine and mouse oocytes after their fusion with growing porcine oocytes
Authors: Fulka J. , Motlík J. , Fulka J. , Crozet Nicole 
Published: June 2005

AbstractPorcine ovarian oocytes, isolated from follicles of 5 mm in diameter (large oocytes), were fused either together or with oocytes isolated from follicles of 0.5 mm in diameter (small oocytes). In giant cells composed of two large oocytes (control) germinal vesicle breakdown (GVBD) occurred and two metaphase I chromosome sets (M I) were observed 24 to 30 h after fusion. By contrast, in giant cells composed of one large and one small porcine oocyte, both germinal vesicles (GVs) remained well conserved after 24–30 h of culture. An identical situation was observed after fusion and cultivation of small porcine and large mouse oocytes isolated from preovulatory follicles. The results demonstrate the presence of inhibiting activity in the ooplasm of small porcine oocytes that prevents nuclear maturation of large porcine and mouse oocytes fused to them. This maturation inhibiting activity can be overcome by preincubating large porcine oocytes for more than 14 h before fusion with small oocytes. During preincubation the ooplasm produces sufficient amount of maturation promoting factor (MPF) to overcome the inhibiting activity present in small porcine oocytes thus inducing GVBD and chromatin condensation both in small and large oocytes.
Inhibition of 45Ca2+ uptake in the eggs and embryos of the sea urchin, Anthocidaris crassispina, by several calcium antagonists, anion transport inhibitor, and chloride transport inhibitors
Authors: Fujino Yukio , Mitsunaga Keiko , Fujiwara Akiko , Yasumasu Ikuo 
Published: June 2005

AbstractThe rate of45Ca2+ uptake was close to zero in unfertilized eggs. It rapidly increased after fertilization and then decreased within 1 hr. The rate remained low between 1 and 12 hr after fertilization (until shortly after hatching). Thereafter, the rate gradually increased during developmental period between 15 (the mesenchyme blastula stage) and 30 hr after fertilization (the prism stage). It then decreased 40 hr after fertilization (the pluteus stage). In embryos assayed 30 and 40 hr after fertilization, about 70 and 40 percent, respectively, of 45Ca2+ was found in the spicules. During the whole period of early development, 45Ca2+ uptake was inhibited by diltiazem and verapamil (calcium antagonists), ruthenium red (known to inhibit45Ca2+ uptake in mitochondia and also Ca2+ ‐ATPase in plasma membrane), and 4,4′‐diisothiocyano‐2,2′‐disulfonic acid stilbene (an anion transport inhibitor). Ethacrynic acid and furosemide (chloride transport inhibitors), inhibited 45Ca2+ uptake between 24 and 40 hr after fertilization. These results suggest that 45Ca2+ is transported through a Ca2+ channel and/or a Ca2+ ‐pump and that electrosilent transport of Ca2+ is achieved by anion transport.
Long‐term adaptation to low salinities in the euryhaline shrimp Crangon franciscorum (Stimpson)
Authors: Shaner Stephen W. , Crowe John H. , Knight Allen W. 
Published: June 2005

AbstractThe euryhaline shrimp Crangon franciscorum is a hyper‐hypoosmotic regulator, its hemolymph being iso‐osmotic with the medium near 27‰ salinity. Shrimp collected from low salinity environments are physiologically very distinct from those collected from high salinity environments. Individuals from low salinity habitats exhibit better survival, a lower water content and apparent permeability to water, and a decreased rate of sodium loss in low salinities when compared to shrimp from high salinity habitats. These differences persist after several days of adaptation to low salinity, however after acclimation to a low salinity for a longer time (5–6 weeks in this study), these differences disappear.
Purification and characterization of an N‐acetyl‐β‐D‐glucosaminidase from cortical granules of Xenopus laevis eggs
Authors: Prody Gerry A. , Greve L. Carl , Hedrick Jerry L. 
Published: June 2005

AbstractThe enzyme N‐acetyl‐β‐D‐glucosaminidase was purified from the cortical granules of Xenopus laevis eggs using affinity chromatography, gel filtration, and density gradient centrifugation. The enzyme had a molecular weight of 37,000–40,000 as determined by polyacrylamide gel electrophoresis and density gradient centrifugation, had a Km for p‐nitrophenyl‐β‐D‐N‐acetyl‐glucosaminide of 0.66 mM and a Ki for glucosamine of 4.3 mM. The kinetic properties of the cortical granule enzyme were similar to the enzyme isolated from jack bean. Treatment of unfertilized eggs with the enzyme isolated from cortical granules or jack bean rendered eggs unfertilizable. Loss of fertilizability was proportional to the product of time and enzyme concentration, consistent with an enzymatic mechanism being responsible for the loss of fertilizability. The amount of enzyme present in the perivitelline space was approximately the same as that which reduced fertilizability by 50% in one hour. We suggest that the action of cortical granule N‐acetyl‐β‐D‐glucosaminidase on egg integuments may function as a block to polyspermy at fertilization.
Control of panting in the desert iguana: Roles for peripheral temperatures and the effect of dehydration
Authors: Dupré R. Keith , Crawford Eugene C. 
Published: June 2005

AbstractAlthough it is generally held that panting is a physiological mechanism for the regulation of brain temperature during heat stress, a number of studies have pointed to the importance of peripheral input for the initiation of the panting response in a variety of animals. By presenting ambient heat loads of 47°, 54°, 58°, and 65°C, and measuring skin, ear and core temperatures of the desert iguana, Dipsosaurus dorsalis, at the onset of panting, we found that the skin temperature at panting onset was independent of ambient heat load. This suggests that skin (peripheral) temperature is the body temperature on which the central thermoregulatory center cues to initiate thermal panting. Peripheral temperature control of panting was retained when the plasma osmolality of the desert iguana was increased by 100 mOsm/kg H2O to simulate dehydration. Dehydration to 80% initial body weight (IBW) resulted in a progressive increase in panting threshold (skin) from 42°C for untreated lizards to 42.5°C at 90% IBW to 43.3°C at 80% IBW. Injection of 80% IBW lizards with a volume of 10 mM NaCl equivalent to weight loss resulted in a decrease in panting threshold to 40.8°C. Injection with 1% body weight 3000 mM NaCl produced a dramatic increase in panting threshold to 45.9°C. These data suggest that the desert iguana responds to dehydration by elevating panting threshold, thus promoting water conservation. These data also suggest that changes in plasma osmolality may be involved in the “setting” of panting threshold.
The role of K+ and Cl− conductances in chloride secretion by the opercular epithelium
Authors: Degnan Kevin J. 
Published: June 2005

AbstractThe opercular epithelium of the teleost Fundulus heteroclitus, when mounted in a lucite chamber under short‐circuited conditions, secretes Cl− at a rate equivalent to the short‐circuit current (Isc). The transepithelial Na+ movements are passive and proceed by a paracellular pathway. The addition of 2 × 10−3 M Ba2+ to the serosal bathing solution inhibited the Isc 76.8% with no effect on the transepithelial conductance (Gt). The addition of 5 × 10−4 M Cu2+ to the mucosal bathing solution inhibited the Isc 79.6% and reduced the Gt 35.6%. These inhibitory effects of Ba2+ and Cu2+ on the Isc were initiated within 1 minute after exposure with maximum effects occurring within 20 and 30 minutes, respectively. Simultaneous 36Cl− and 22Na+ unidirectional fluxes were performed on paired epithelia from the same fish. Serosal Ba2+ and mucosal Cu2+ inhibited the Cl− secretory flux 30.2 and 58.9%, respectively. The resulting net Cl− flux after inhibition was not significantly different from the mean measured Isc. Neither ion had significant effects on the Cl− influx (mucosa to serosa) or the unidirectional Na fluxes. These results indicated that the effects of both Ba2+ and Cu2+ were most likely exclusive to the transcellular Cl− pathway. Ba2+ is proposed to inhibit Cl− secretion by blocking the basolateral K+ channels, depolarizing the cell, and reducing the electrochemical driving force for Cl− across the apical membrane. Cu2+ is proposed to inhibit Cl− secretion by blocking the apical membrane Cl− channels. The results are in keeping with the proposed mechanism for Cl− secretion by indicating that the Cl− exit step across the apical membrane occurs via Cl− conductive channels and is driven passively by a favorable electrical gradient.
Cell allocation in half‐ and quadruple‐sized preimplantation mouse embryos
Authors: Rands Gillian F. 
Published: June 2005

AbstractThe size of preimplantation mouse embryos was experimentally manipulated in order to examine the consequences for the allocation of cells to the two primary tissues, trophectoderm and inner cell mass (ICM). Half embryos were produced by the mechanical lysis of one cell at the two‐cell stage and quadruple embryos by the aggregation of four whole eight‐cell embryos. Such procedures are shown not only to alter the absolute number of cells that are assigned to the trophectoderm and ICM, but also to disturb significantly the proportions of these two tissues in the blastocyst. The proportion of trophectoderm is directly related to the surface area of the morula, as is predicted by a purely epigenetic scheme for cell allocation.
The behaviour of insect plasmatocytes in vitro: Changes in morphology during settling, spreading, and locomotion
Authors: Davies D. H. , Preston T. M. 
Published: June 2005

AbstractThe settling, spreading and locomotory behaviour of the plasmatocytes from three lepidopteran species (Ephestia kuehniella, Pieris brassicae and Aglais urticae) on a glass substratum in vitro has been examined using light and scanning electron microscopy. Immediately upon withdrawal from the haemocoel plasmatocytes are ovoid (E. kuehniella) or spindle‐shaped. These cells are usually seen to undergo a series of three distinct morphological changes in response to cell‐substratum contact. 1) The initial stable attachment, beneath the nuclear region, is followed by a rapid rounding‐up with a concomitant initiation of surface ruffling and filopod production. 2) Cell‐substratum contact is consolidated by an increase in area and the establishment of additional contacts at suitable (cell‐free) sites around the periphery by filopodia. 3) Spreading proceeds with the production of lamellae which expand within the interfilopodial space.The shape of fully spread plasmatocytes is variable but only locomoting cells are clearly polarized. Locomotion is triggered during spreading in response to cell‐cell contact; colliding partners then polarise and exhibit brief evasive translocations over a short distance. It has also been shown that plasmatocytes translocate over the surface of glass implants during the early stages of encapsulation in vivo.
Sexual differences and steroid‐induced changes in metabolic activity in toadfish sonic muscle
Authors: Pennypacker Keith R. , Fine Michael L. , Mills Richard R. 
Published: June 2005

AbstractSince the male oyster toadfish (Opsanus tau) is more active in sound production than the female, we hypothesized that sonic muscles of the male are biochemically specialized to perform more work. In order to categorize the muscle biochemically and test for sexual differences, we measured the activity of two anaerobic enzymes, 3‐phosphoglyceraldehyde dehydrogenase (3PG) and lactic dehydrogenase (LDH), and two aerobic enzymes, malate dehydrogenase (MDH) and glutamic oxaloacetic transaminase (GOT). Males exhibited greater 3PG and GOT activity than females (p < 0.05). Both MDH and LDH showed little activity in either sex. High 3PG and low LDH levels indicate a substained level of glycolysis, with pyruvate shuttled into aerobic metabolism, and high GOT activity indicates a high level of aerobic metabolism. From this and other data, we conclude that toadfish sonic muscle can be classified as fast‐twitch oxidative glycolytic or fast‐twitch fatigue resistant. The endocrine basis for these sexual differences was examined by implanting steroid pellets into ovariectomized females. Testosterone induced a doubling of 3PG activity (p < 0.02), and dihydrotestosterone induced an eight‐fold increase (p < 0.0005) in GOT concentration over controls. The steroids had no effect on LDH and MDH activities. Hormones, therefore, trigger one of the fundamental sexual differences underlying toadfish communication, namely a difference in metabolism, providing the male with the capacity for increased sound production.
Glutamate catabolism in mitochondria from Mya arenaria mantle: Effects of pH on the role of glutamate dehydrogenase
Authors: Moyes Christopher D. , Moon Thomas W. , Ballantyne James S. 
Published: June 2005

AbstractThe role of glutamate dehydrogenase (GDH) in amino acid catabolism of the mantle of Mya arenaria was examined using coupled mitochondria and in vitro enzyme activity measurements. The maximal activities of mitochondrial glutamate‐oxaloacetate transaminase (GOT) and glutamate‐pyruvate transaminase (GPT) are fourfold and twofold greater, respectively, than GDH (deaminating). Based on pH profiles, the relative activities of these enzymes in vivo may be highly dependent on mitochondrial pH. Addition of ADP resulted in a 15‐fold activation of GDH (deaminating) and a shift in the pH optimum from 8.1 to 8.6. The in vitro activity of GDH was sufficient to account for all NADH produced in intact mitochondria oxidizing glutamate. In intact mitochondria at pH 7.4 and 8.2, addition of the aminotransferase inhibitor aminooxyacetic acid (AOA) had no effect on the state 3 rate of glutamate oxidation. However, at pH 6.7 in situ GDH (deaminating) activity was insufficient to maintain the rate of glutamate oxidation in the absence of transaminase activity. Glutamate oxidation between pH 6.4 and 8.0 is limited by the electron transport system. At pH 8.3, transport of glutamate into the mitochondria may be rate limiting. Mitochondria oxidizing glutamate in state 4 in the presence of phosphate or in state 2 in the absence of phosphate demonstrated increased oxygen consumption in response to the uncoupler carbonyl m‐chlo‐rophenyl‐hydrazone (CCCP). These studies suggest that in spite of low activities compared to vertebrates, GDH activities could be physiologically significant in amino acid metabolism of Mya arenaria mantle.
Pattern‐deficient forelimb regeneration in adult bullfrogs
Authors: Tomlinson Bruce L. , Tomlinson Donna E. , Tassava Roy A. 
Published: June 2005

AbstractThis study was designed to test the ability of adult bullfrogs (Rana catesbeiana) to regenerate forelimbs, both with and without various experimental treatments. Distal humerus‐level forelimb amputations provided with additional deviated (sciatic) nerve and/or repeated soft‐tissue injury exhibited considerable outgrowth. However, control sham‐operated forelimbs also produced regenerates with comparable frequency, size, and morphological complexity. The lengths of the regenerates ranged from 0.4 to 2.6 cm, representing an outgrowth of 10–65% of the portion removed by the distal humerus amputation plane; some regenerates exhibited an external morphology indicative of digitlike structures. Some outgrowths were flexible but only one was capable of independent movement. Victoria Blue staining of whole regenerates revealed a variety of internal cartilage elements. Staining showed a single solid mass of cartilage in some regenerates while others had several individual and variably shaped cartilages projecting distally. Histological analysis also revealed the presence of connective tissue, striated muscle, and abundant nerve fibers in addition to the individual cartilage elements. We have tentatively termed these responses pattern‐deficient regeneration.
The early lethality of autosomal monosomy in the mouse
Authors: Magnuson Terry , Debrot Sylvain , Dimpfl Joan , Zweig Adam , Zamora Teodosia , Epstein Charles J. 
Published: June 2005

AbstractUsing male mice doubly heterozygous for pairs of Robertsonian translocation chromosomes that have one arm in common, mouse embryos monosomic for 11 of the 19 autosomes have been generated. All of these monosomies result in death prior to or during the implantation period, with only rare survivors being detected 6 days after fertilization. For some of the monosomies the onset of lethality can be detected during the third or fourth day of development, but others do not begin to die until sometime after the late blastocyst stage on day 4. Retardation of development, as revealed by decreased cell numbers, is often detectable prior to or after the onset of the lethal period. The period during which death occurs may spread over several days and does not coincide with any of the developmental landmarks of the pre‐ or peri‐implantation period. Genetic factors that may affect the rate of cellular proliferation or other aspects of embryonic development appear to play an important role in determining exactly when individual monosomies result in death. The universal early lethality of the autosomal monosomies leads to the conclusion that a large number of loci scattered over all of the autosomes are involved in processes that are so concentration dependent that a 50% reduction is sufficient to produce very serious consequences.
Stimulation of 17α,20β‐dihydroxy‐4‐pregnen‐3‐one production in the granulosa cells of amago salmon, Oncorhynchus rhodurus, by cyclic nucleotides
Authors: Nagahama Yoshitaka , Kagawa Hirohiko , Adachi Shinji , Young Graham 
Published: June 2005

AbstractThe effects of partially purified chum salmon gonadotropin (SGA), forskolin, dibutyryl cAMP and cGMP, and the phosphodiesterase inhibitors theophylline and 3‐isobutyl‐1‐methyl‐xanthine (IBMX) on the production of 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (maturation‐inducing steroid in amago salmon, 17α,20β‐diOHprog) by amago salmon, Oncorhynchus rhodurus, granulosa layers in vitro were examined. All test agents, with the exception of dibutyryl cGMP, significantly stimulated the production of 17α,20β‐diOHprog when granulosa layers were incubated in the presence of 17α‐hydroxyprogesterone, but not in its absence; 1 μg/ml SGA, 1, 10, and 100 μM forskolin, 1 mM dibutyryl cAMP, 1 mM theophylline, and 1 mM IBMX stimulated production to levels about 2–17 times those of the untreated controls. These results indicate that gonadotropin directly acts on amago salmon granulosa cells to stimulate 17α,20β‐diOHprog production, possibly by enhancing the activity of 20β‐hydroxysteroid dehydrogenase, the enzyme involved in the conversion of 17α‐hydroxyprogesterone to 17α,20β‐diOHprog, via an adenylate cyclase‐cAMP‐dependent mechanism.