bluuebunny/crossref_metadata_2025_split huggingface dataset:
Forskolin and mouse oocyte maturation in vitro
Authors: Sato Eimei , Koide S. S. 
Published: June 2005

AbstractOocytes isolated from mature follicles undergo spontaneous maturation when cultured in vitro. Forskolin, an adenylate cyclase stimulator, inhibited resumption of meiosis of cumulus‐free mouse oocytes in vitro. Germinal vesicle breakdown (GVBD) was prevented in more than 85% of the oocytes treated by forskolin at concentrations of 20 μg/ml and higher. The inhibiting effect of forskolin was dose‐dependent and reversible. FSH, LH, FSH plus LH, estrogen, progesterone, and estrogen plus progesterone did not reverse the block induced by forskolin in cumulus‐free and cumulus‐enclosed oocytes. The present results suggest that intracellular cAMP may play a role in the regulation of oocyte maturation.
Patterned regeneration of internal femoral structures in the cockroach, Periplaneta americana L.
Authors: Kaars C. , Greenblatt S. , Fourtner C. R. 
Published: June 2005

AbstractThe morphology of the nerve and tracheal supply to the extensor tibiae muscle in normal legs was compared to that in regenerate legs. In normal femurs, the extensor nerve and trachea extend along the posterior surface of the extensor muscle. The nerve and trachea are closely associated and branch coincidently at regular intervals. In regenerate femurs, the nerve and trachea are not closely associated with each other, and both structures differ from normals in their branching patterns. The results suggest that tissue level interactions during regeneration differ from those during embryogenesis.
Jelly release in the eggs of the white sturgeon, Acipenser transmontanus: An enzymatically mediated event
Authors: Cherr Gary N. , Clark Wallis H. 
Published: June 2005

AbstractThe thin electron‐dense jelly layer that coats A. transmontanus eggs is released and hydrates when the eggs contact freshwater. This jelly release is dependent on a trypsin‐like protease and divalent cations since specific trypsin inhibitors and Ca++‐Mg++‐free freshwater block release. Chymotrypsin inhibitors have no effect on jelly release. The jelly consists of protein and carbohydrate and is the only layer of the egg envelope that contains sialic acid. The major component of jelly is a glycoprotein with a molecular weight of 110,000 daltons.
Angiotensin‐converting enzyme activity in tissues of the rainbow trout
Authors: Galardy R. , Podhasky P. , Olson K. R. 
Published: June 2005

AbstractAngiotensin‐converting enzyme activity (ACE) was assayed in homogenized rainbow trout tissues and plasma. The physiological role of ACE was examined by injection of the ACE inhibitor captopril (SQ 14,225) into the dorsal aorta of chronically cannulated trout. Gills and corpuscles of Stannius exhibited greatest ACE activity and contained over 30 times more enzyme than plasma on a per‐wet‐weight basis. ACE was barely detectable in skeletal muscle, liver, and kidney tissues. Captopril lowered dorsal aortic pressure (DAP) within 1 min after injection. Pressure fell 5–7 mm Hg below control over the next 30 min and remained at this level for an additional hour. Because the gills receive the entire cardiac output they are, like the mammalian lungs, ideally situated to regulate plasma hormone levels. Activation of angiotensin II (AII) appears to be only one example of branchial metabolic capability.
Effects of insulin on the fine structure of hepatocytes from winter‐acclimatized carps: Studies on protein synthesis
Authors: Sáez Lino , Amthauer Rodolfo , Rodríguez Esteban , Krauskopf Manuel 
Published: June 2005

AbstractMale and female winter‐acclimatized carps were injected with insulin. This treatment resulted in a sharp decrease in the liver glycogen content. Although an increase in the ribosomal RNA level was also observed, a cell‐free system obtained from the hormone‐treated fish exhibited less amino acid incorporation activity as compared to the control fish. However, polysomes from insulin‐treated fish exhibited a higher amino acid incorporating activity when a soluble fraction of untreated winter carps was used.Insulin induced a profound change in the cytoarchitecture of the winter carp hepatocyte. The cytoplasm and nuclei showed all the features of the summer carp liver cell. The nucleolar components were totally intermingled suggesting a high rate of gene expression as in the case of the summer‐acclimatized fish.
Effects of light‐deprivation on development of photopositive behavior in Xenopus laevis tadpoles
Authors: Copp Newton H. , McKenzie Tracey 
Published: June 2005

AbstractThe development of amphibian sensory systems and behavior is generally considered to proceed normally without reference to sensory experience during embryonic or larval stages. Most of the supporting research, however, has concentrated on the retinotectal (visual) systems of anurans and has ignored behaviors directed by other sensory systems. We demonstrate that early exposure to light is necessary for the development of photopositive behavior in Xenopus laevis tadpoles, a behavior probably directed by the pineal complex. Light‐deprivation during the tadpoles' first 10 days of development results in a long‐lasting reduction in the tadpoles' light preference. The development of a strong light preference is not influenced by light‐deprivation before the tadpoles are 2 days old or after the tadpoles are 10 days old, but light‐deprived tadpoles recover a weak light preference after subsequent days of rearing in the light. Lengthening the tadpoles' exposure to light during the first 10 days of development produces increasingly strong light preferences. Considering the important role of the pineal complex in guiding phototactic behaviors in anurans, we suggest that light‐deprivation alters photopositive behavior in Xenopus tadpoles by altering the development of the pineal complex.
The culture of 12‐ and 13‐day rat embryos using continuous and noncontinuous gassing of rotating bottles
Authors: Priscott P. K. , Yeoh G. C. T. , Oliver I. T. 
Published: June 2005

AbstractA technique for the culture of 12‐ and 13‐day rat embryos is presented. The culture method described utilizes the opening of the extraem‐bryonic membranes together with a simple bottle rotator during incubation to facilitate tissue oxygenation. This method was compared with a more elaborate device that enabled constant gassing during incubation. Best results were obtained with 12‐day embryos cultured for 24 hr in closed bottles. Thereafter, there was a marked falloff in embyronic development in culture. Optimal medium conditions were 25% rat serum in tissue culture medium with a gas phase of 60% O2, 5% CO2, 35% N2. The culture method described allows for larger numbers of embryos to be cultured more simply than previous methods and should be valuable to workers wishing to study embryos in the more advanced stages of organogenesis.
Photoperiodic control of antler cycles in deer. VI. Circannual rhythms on altered day lengths
Authors: Goss Richard J. 
Published: June 2005

AbstractGroups of sika deer were exposed to light and dark periods of equal lengths but different from 12 hr. Light cycles were 4.94L/4.94D, 6L/6D, 8L/8D, and 21L/21D. In all experiments, deer underwent circannual cycles of antler replacement, testis size, molting, and coat color. The results indicate that the previously reported abolition of circannual cycles on 12L/12D was due to the 12‐hr duration of the light or dark periods, not their equivalence. They also eliminate the possibility that the circannual cycle might be the sum of 365 circadian cycles. Circannual antler cycles appear to be expressed under artificial light cycles to which the deer cannot entrain.
Transepithelial potential measurements in the isolated, perfused head of a marine teleost
Authors: Claiborne J. B. , Evans David H. 
Published: June 2005

AbstractThe transepithelial potential (TEP) across the gills of a seawater teleost, the long‐horned sculpin (Myoxocephalus octodecimspinosus), was measured both in vivo and utilizing an isolated, perfused head preparation (IPHP). The TEP of the IPHP was compared to that of the whole animal while in normal seawater and Na‐ or Cl‐free seawater. The TEP or the IPHP in seawater was similar to that measured in vivo ( + 7.7 versus +7.2 mV, respectively). Na‐free seawater induced a depolarization of both the IPHP and the intact fish, while Cl‐free seawater hyperpolarized the TEP in vivo.The positive TEP of the sculpin, measured both in vivo and in vitro, is indicative of a transbranchial Na+ to Cl− permeability ratio greater than unity. The IPHP of the sculpin exhibits differential ion permeabilities similar to that of the whole animal. TEP comparisons described here should be applied to other IPHP systems now in use.
Does vitamin A act on pattern formation via the epidermis or the mesoderm?
Authors: Maden M. 
Published: June 2005

AbstractTo determine whether the effect of vitamin A on pattern formation in the regenerating axolotl limb was due to a change in the blastemal mesoderm or the epidermis, tissue grafts were exchanged between normal and retinoic acid‐treated animals. The results were conclusive. The combination of treated epidermis and untreated mesoderm resulted in normal regenerates. The combination of treated mesoderm and untreated epidermis produced regenerates that were serially duplicated in the proximodistal axis just as the controls were. We may, therefore, conclude that vitamin A acts on the mesodermal cells of the blastema in causing proximodistal duplications.
Luminal composition and maturation of spermatozoa in the male genital ducts of the Port Jackson shark, Heterodontus portusjacksoni
Authors: Jones Russell C. , Jones Nigel , Djakiew Daniel 
Published: June 2005

AbstractThe functions of the epididymis of H. portusjacksoni were studied to assess the significance of its structural differentiation and to provide a basis for assessing the evolution of the vertebrate epididymis. It was shown that posttesticular sperm maturation occurs within the epididymis. The maturation process involves the development of the capacity for motility, and the formation of sperm bundles. However, the process does not involve ultrastructural changes. Micropuncture studies of the epididymal luminal fluids showed that in the region where sperm mature the ducts absorb most of the extracellular fluid leaving the testis, and secrete a denser proteinaceous fluid. Determinations of sodium and potassium showed that there is a barrier to the free movement of these ions between blood and the lumen of the genital ducts. The ratio of sodium:potassium was high (36.6:1) in the ductuli efferentes, but reduced to a ratio of 3.4:1 at the distal end of the epididymis. The epididymal fluids contain membrane‐bound, cytoplasmic bodies 3–4 μm in diameter which form a separate layer from spermatozoa during centrifugation. The bodies contain mitochondria, ribosomes, endoplasmic reticulum, lipid droplets, and a lower concentration of sodium than the surrounding fluid. It is concluded that the epididymis in the shark carries out some of the main functions of the mammalian epididymis.
Distribution of a proteinase inhibitor of epididymal origin in the tissues and secretions of the male reproductive tract of mice
Authors: Poirier Gary R. , Nicholson Nanette 
Published: June 2005

AbstractMonoclonal antibodies to a low molecular weight, acid‐stable acrosin‐trypsin inhibitor isolated from epidiyml homogenates were used to localize the inhibitor in tissues and secretions of the male reproductive tract of mice. The inhibitor, identified by indirect immunofluorescence, is present in the testes and in the apical portion of the epithelial cells from the caput region of the epididymis of both intact and efferentiectomized animals. Sperm isolated from the testes and caput epididymal region show inhibitor‐positive fluorescence on the anterior acrosomal region. The inhibitor could not be localized on ductus or electroejaculated sperm or ductus sperm previously incubated in a purified inhibitor solution. Furthermore, the inhibitor was not visible in the copulatory plug of recently inseminated animals or on sperm recovered from the uterus or from an artificial capacitating medium. The inhibitor could be detected by an enzyme‐linked immunosorbent assay in the supernatants of detergent treated or frozen‐thawed caput sperm but not of ductus sperm. The data suggest that the inhibitor, made in both the testes and caput epididymis where it associates with the sperm, is lost from the sperm or irreversibly masked during the epididymal sojourn.
Partially irreversible cold‐induced lipid phase transitions in mammalian sperm plasma membrane domains: Freeze‐fracture study
Authors: Holt W. V. , North R. D. 
Published: June 2005

AbstractIn an effort to investigate the nature of the cellular injury caused when mammalian spermatozoa are cooled prior to cryopreservation, the occurrence of thermal phase transitions amongst the lipid components of the sperm plasma membrane was investigated by the use of freeze‐fracture electron microscopy. The mechanisms by which glycerol and egg yolk exert protective effects during semen cooling and freezing were also examined.Ram and blackbuck spermatozoa, maintained at 30°C prior to fixation at this temperature, exhibited randomly distributed intramembranous particles over the acrosomal, postacrosomal, and flagellar regions of the plasma membrane. In contrast, spermatozoa fixed at 5°C after slow cooling to this temperature exhibited particle clustering over the postacrosomal region of the head as well as over the tail. These effects were not influenced by the presence of egg yolk or glycerol during the cooling procedure, although these substances protected the spermatozoa against loss of motility.Particle clustering over the sperm tail, induced by the slow cooling process, was found to be only partially reversible. The extensive areas of particle‐free lipid, noted to result from the cooling procedure, were absent if the spermatozoa were rewarmed to 30°C; however, the original distribution of particles was not restored and numerous small particle‐free domains persisted. It is proposed that this type of irreversible change within the sperm plasma membrane may contribute to the loss of motility and fertility suffered by spermatozoa after cooling and freezing. Furthermore, it is suggested that protective substances such as egg yolk may exert their effects by countering these deleterious changes, rather than by preventing their occurrence.
Regeneration of whole limbs in toad tadpoles treated with retinol palmitate after the wound‐healing stage
Authors: Niazi I. A. , Ratnasamy C. S. 
Published: June 2005

AbstractIn young Bufo melanosticus tadpoles at the spatula stage of limb development, the left hindlimb was amputated through the shank and the right hindlimb was left intact. One day later, when the amputation surface was covered by wound epidermis, the tadpoles were immersed in 15 IU/ml of retinol palmitate solution for 2 days up to blastema formation and thereafter reared in plain water. Contrary to the situation in untreated controls, all the resultant regenerates of the vitamin‐treated tadpoles were complete limbs containing elements from the pelvic girdle to the phalanges. Retinol palmitate treatment inhibited the development of the foot in the unamputated right limbs. These results show that retinol palmitate has a different effect on dedifferentiating cells of a regenerating limb from that on cells that are differentiating in a normally developing limb.
β‐Alanine transport in the isolated hepatocytes of the elasmobranch Raja erinacea
Authors: Shuttleworth T. J. , Goldstein L. 
Published: June 2005

AbstractCells were isolated from the liver of the skate and the uptake of β‐alanine followed using [14C]‐β‐alanine. The isolated hepatocytes showed good viability, were found to accumulate β‐alanine from the incubation medium, and did so in a manner indicating a transport system involving a saturable carrier. The data for the rate of β‐alanine uptake suggest that this may be a rate‐limiting step in the oxidation of the amino acid by the liver. Experiments indicated that the transport system could distinguish β‐alanine from certain structurally similar molecules (L‐alanine and taurine, but not γ‐amino butyrate). Cells isolated from fish adapted to a diluted environment (50% seawater) showed no significant change in the uptake rate. However, evidence indicates that, over the range of β‐alanine concentrations occurring in the fish, the uptake rate would be acutely sensitive to small changes in the concentration in the blood, thus forming a self‐regulating system for the metabolism of β‐alanine.
Fate of stored secretion following ligation of the seminal vesicle–coagulating gland in the rat
Authors: Brown Randall D. , Shepherd Benjamin A. , Martan Jan 
Published: June 2005

AbstractUnilateral ligation of the seminal vesicle‐coagulating gland complex in castrated and testes intact sexually mature rats resulted in a significant asymmetry in weight after 14 days, with ligated glands heavier in both groups. Differences in weight between glands resulted from ligation, and the primary route by which stored secretion is eliminated from these glands is by spontaneous ejaculation rather than resorption via the glandular epithelia.
Neuromuscular relationships during claw regeneration in Californian snapping shrimp
Authors: Stephens Philip J. , Leferovich John M. 
Published: June 2005

AbstractWe have examined the innervation patterns of the two excitor axons to the closer muscle in the dimorphic (snapper and pincer) claws of Californian snapping shrimp (Alpheus californiensis). In both claws the fastcloser excitor (FCE) axon supplies all of the closer muscle fibers. The slowcloser excitor (SCE) axon, however, makes functional connections only with fibers on the dorsal and ventral margins, which are composed of slow‐type fibers in the large snapper claw and of intermediate‐type fibers in the smaller pincer claw. The central band of fast fibers in the pincer closer muscle is not innervated by the SCE.During claw regeneration, the closer muscle is initially composed of a population of fast fibers in the pincer and intermediate‐type fibers in the snapper. The innervation patterns of the two excitatory motor axons in regenerating claws at this stage are the same as in fully developed claws. During the first intermolt period some fast‐closer muscle fibers in the pincer claw differentiate into intermediate‐type fibers, but the axon innervation patterns do not change. If the correlation between SCE axon innervation pattern and the regional distribution of different muscle fiber types is indicative of nerve‐muscle interactions, the present data suggest that the trophic influence must proceed from nerve‐to muscle.
Induction of starfish oocyte maturation by maturation‐promoting factor of mouse and surf clam oocytes
Authors: Kishimoto Takeo , Yamazaki Kimie , Kato Yoshihiro , Koide Samuel S. , Kanatani Haruo 
Published: June 2005

AbstractMaturation‐promoting factor (MPF) has been known to be produced in the cytoplasm of starfish and amphibian oocytes, where it triggers meiotic maturation. Cytoplasm obtained from maturing oocytes of either mouse or surf clam was found to induce maturation when injected into immature starfish oocytes. These facts suggest that MPF is also produced in oocytes of the mouse and surf clam and that MPF acts in a general, nonspecific manner in mammals, echinoderms, and molluscs.
Differences in phosphorylation of the two large subunits of brine shrimp Na, K‐ATPase
Authors: Churchill Lynn 
Published: June 2005

AbstractAnalysis of purified Na,K‐ATPase from brine shrimp nauplii revealed two molecular forms of the α subunit separable by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis [G.L. Peterson, R.D. Ewing, S.R. Hootman, and F.P. Conte (1978) J. Biol. Chem. 253:4762]. The molecular form with lower mobility is designated α1 and the one with higher mobility, α2 in a neutral or alkaline gel system. Differences in Na+‐dependent, K+‐sensitive phosphorylation of these two molecular forms have been investigated by directly measuring the radioactivity present in each phosphoprotein after separation of the two forms by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. In the presence of Na+, Mg2+, and ATP, when the ATP concentration is above 1 μM, both α subunits are phosphorylated, although the phosphoprotein content of α1 is considerably greater than that of α2. Below 1 μM ATP, the phosphoprotein content of α2 is even further reduced. These striking differences in phosphorylation at low ATP concentrations are not due to a greater instability of the α2 phosphoprotein during the long electrophoresis times or during fixation, staining, and destaining. The proportion of total phosphoprotein content in α2, as well as the relationship between phosphoprotein content and ATP concentration, is unchanged when the radioactive analysis is performed on frozen gels that have been electrophoresed for shorter times, even though the actual amount of phosphorylation is 15 times greater than with fixed gels. Since the concentration of α1 and α2 vary during development [G.L. Peterson, L. Churchill, J.A. Fisher, and L.E. Hokin (1982) J. Exp. Zool. 221:295], the differences in phosphorylation may be relevant to differences in Na,K‐ATPase activity during different development stages.
Absence of branchial edema in perfused heads of rainbow trout (Salmo gairdneri)
Authors: Perry S. F. , Lauren D. J. , Booth C. E. 
Published: June 2005

AbstractUsing scanning electron microscopy, a histological comparison was made between gills from unperfused, blood‐perfused and saline‐perfused trout heads. All gills examined appeared non‐edematous, and no other morphological abnormalities were evident. The results are compared with those from a similar study using isolated eel holobranchs in which saline‐perfusion resulted in severe and irreversible branchial edema.
Catalase, glutathione peroxidase, and superoxide dismutase in the rete mirabile and gas gland epithelium of six species of marine fishes
Authors: Morris Shirley M. , Albright John T. 
Published: June 2005

AbstractRete mirabile and gas gland epithelium from the swim bladders of six species of marine fishes were assayed for catalase, glutathione peroxidase, and superoxide dismutase activity. Correlation of the results of these assays with measurements of the concentration of oxygen in the lumen of the normal steady state swim bladders revealed that swim bladders in species containing higher levels of oxygen also exhibited higher levels of superoxide dismutase activity in the rete mirabile/gas gland epithelium region. There appeared to be no correlation between oxygen concentration and the level of catalase or glutathione peroxidase activity. Induction of the inflatory reflex in Opsanus tau by a single deflation of the swim bladder resulted in an increase in the percent of oxygen in the swim bladder lumen 18 to 24 hours later, but this was not accompanied by any significant increases in antioxidant enzyme activity. Swim bladders that were deflated three times at 24‐hour intervals showed further increases in oxygen concentration at the end of the 72‐hour period but no alteration in superoxide dismutase activity.