bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scanning electron microscope studies of sea urchin fertilization I. Eggs with vitelline layers
Authors: Tegner Mia J. , Epel David 
Published: June 2005

AbstractThe surface coats of sea urchin eggs and the events of fertilization which take place on these surfaces were examined with the scanning electron microscope (SEM). Gametes of Strongylocentrotus purpuratus and Lytechinus pictus were considered in detail; eggs of seven other echinoids were examined for comparative purposes. Jelly coats, preserved by varying the pH of fixation, were found to vary in morphology and solubility properties between species. The vitelline layers of the nine echinoids are characterized by arrays of projections which are impressions of cytoplasmic microvilli in the vitelline layer. After sperm bind to the egg surface via the acrosomal process, fine filaments, apparently an egg response to insemination, further connect some sperm heads and tails to the egg. The cortical reactions spread out as a wave from where the fertilizing sperm fused with the egg; separation of the vitelline layer proceeds as a smooth wave front in S. purpuratus eggs and as a series of localized separations in L. pictus eggs. The fertilization membranes of S. purpuratus and Allocentrotus fragilis zygotes are expanded replicas of their respective vitelline layers, suggesting that fertilization membranes are formed by an unfolding of the vitelline layer.
Mammalian carbonic anhydrase isozymes : Evidence for A third locus
Authors: Holmes Roger S. 
Published: June 2005

AbstractStarch gel electrophoretic patterns of carbonic anhydrase (CA) isozymes were examined from tissue extracts of sheep, mice, rabbits, and chickens. In addition to the widely distributed and extensively studied B and C isozymes, an additional isozyme (called CA‐A) was observed, which was predominantly localized in muscle tissue. Immunochemical studies showed the A isozyme to be homologous with CA‐B. Developmental and tissue distribution analyses suggested that a third locus (A) is involved in carbonic anhydrase synthesis in mammals.
Photoperiodic control of antler cycles in deer. III. Decreasing versus increasing day lengths
Authors: Goss Richard J. 
Published: June 2005

AbstractDeer were exposed for three years to photoperiods which increased or decreased two hours every four months, starting at 4L/20D or 20L/4D, respectively. Under both sets of conditions, antlers were repeatedly shed and replaced, usually in synchrony with every other time the day lengths were changed. On decreasing days, antler cycles were omitted as the photoperiod passed the equinox (12L/12D). On increasing days, the equinoctial photoperiod induced prolonged episodes of antler growth.The tendency for the antler replacement cycle to lock onto alternate changes in artificial photoperiods is consistent with the seasonal growth of antlers every other time the day lengths change in the natural environment. It is suggested that antler replacement is triggered neither by shortening nor lengthening days, but by the alternation of such changes irrespective of the direction of the shift in the photoperiod.
Effects of various low temperatures, cryoprotective agents and cooling rates on the survival, fertilizability and development of frozen‐thawed mouse eggs
Authors: Parkening T. A. , Tsunoda Y. , Chang M. C. 
Published: June 2005

AbstractFrozen mouse eggs were examined to determine the effects of low temperatures, concentration of cryoprotective agents and cooling rates on their survival, fertilizability in vitro and subsequent development. Dimethyl sulfoxide administered at 1.5 M concentration was found to be the most effective cryoprotective agent. Upon thawing, 51% and 56% of the eggs appeared to be normal after having been cooled at 0.33°C/min to − 30°C and −50°C, but only 18% of the eggs appeared to be normal after having been cooled at the same rate to − 75°C. When eggs were cooled at 0.33°C/min to −45°C and the cooling rate increased to 1°C/min from −45°C to −75°C, 44% and 72% appeared normal upon thawing. Of the normal eggs fertilized in vitro from C3H mice, 65% cleaved to the 2‐cell stage and 24% of the 2‐cell eggs developed into blastocysts. Following the transfer of 17 blastocysts into three recipient mice, one mouse delivered three normal young.
Qualitative patterns of protein synthesis in the mouse oocyte
Authors: Golbus Mitchell S. , Stein Madelyn P. 
Published: June 2005

AbstractMouse oocytes were found to sythesize proteins actively at the germinal vesicle, metaphase I, metaphase II, and pronuclear (6 hours post‐fertilization) stages. The qualitative pattern of protein components being sythesized in vitro, as demonstrated using polyacrylamide gel electrophoresis, changed throughout maturation and fertilization. Oocytes were arrested at metaphase I by ≥ 0.1 μg/ml cycloheximide or actinomycin D. The protein pattern in oocytes cultured in the presence of actinomycin D progresses to a metaphase II pattern in spite of the nuclear maturation arrest, indicating a dissociation between meiotic maturation and the changes in the pattern of proteins synthesized at different stages of maturation.
Role of asterosaponin A in starfish spawning induced by gonad‐stimulating substance and 1‐methyladenine
Authors: Ikegami Susumu 
Published: June 2005

AbstractA polypeptide hormone, gonad‐stimulating substance (GSS), induces oocyte maturation and spawning in starfish through the production of 1‐methyladenine (1‐MA) in the follicle cells. Asterosaponin A (ASA) obtained from the ovary of Asterias amurensis inhibits the spawning induced by the application of GSS on isolated ovarian fragments of Asterias. The action of ASA is not ascribable to its surface‐active property since various natural and synthetic surface‐active agents failed to affect GSS‐induced spawning. ASA antagonized the action of 1‐MA in inducing spawning of isolated ovarian fragments. However, ASA did not inhibit 1‐MA‐induced maturation of isolated oocytes. When ovarian fragments were placed in sea water containing ASA and GSS or 1‐MA, oocytes inside the fragments underwent germinal vesicle breakdown. The application of acetylcholine to these ovarian fragments resulted in an immediate shedding of mature oocytes. ASA did not affect calcium‐induced spawning in the ovarian fragments which were pretreated with calcium‐free sea water to dissolve the follicular envelope.
Analysis of mouse oogenesis in vitro. Oocyte isolation and the utilization of exogenous energy sources by growing oocytes
Authors: Eppig John J. 
Published: June 2005

AbstractA method is described for the dissociation of mouse ovaries and the isolation of oocytes free of somatic cells by agitating pieces of ovary in collagenase and deoxyribonuclease in a calcium and magnesium free salt solution. This method yielded about 50% of the growing oocytes from immature mice.The utilization of exogenously administered 14C‐labelled energy sources by oocytes in various growth stages was determined by measurement of evolved 14CO2. Little or no evolution of 14CO2 was detected from oocytes of any size incubated in 14C‐glucose, lactate or succinate. The production of 14CO2 from 14C‐pyruvate increased logarithmically when plotted against increasing oocyte volume with a plateau occurring after oocytes reached a volume of 65,500 μm3 (50 μ diameter). Thus, the pattern of energy metabolism for oocyte maturation and early egg cleavage, wherein glucose and lactate are not utilized as efficiently as pyruvate, has been established by the earliest stages of oocyte growth.
Preparation of tissue‐specific cell‐aggregating factors from embryonic neural tissues
Authors: Hausman R. E. , Knapp L. W. , Moscona A. A. 
Published: June 2005

AbstractTissue‐specific cell‐aggregating factors were previously obtained from the supernatant media of embryonic cell cultures. We describe here that such factors can be extracted from cell‐membrane preparations derived directly from embryonic tissues: neural retina, cerebrum, and spinal cord of chick embryos.
Relation between nerve fiber number and pectoral fin regeneration in the teleost
Authors: Ǵeraudie Jacqueline , Singer Marcus 
Published: June 2005

AbstractThe number of nerve fibers per unit of amputation surface area has been determined in four teleosts capable of regenerating their fins (Gobius paganellus, Gobius minutus, Ictalurus nebulosus and Fundulus heteroclitus) and in two non‐regenerating ones (Cottus bubalis and Blennius pholis.) The number of nerve fibers is about 16 in the non‐regenerating fins and varies between 25 and 35 in the regenerating ones. These data, correlated with previous ones obtained on tetrapods, affirm the principle that there is a phylogenetic decline in the quantitative innervation of the vertebrate appendage. Moreover, they show that in the fish a quantitative neuronal threshold must also be satisfied in order for fin regeneration to occur. The threshold, in terms of fiber number, is higher than in the urodele amphibian. However, the fibers appear to be of smaller caliber; and so, the total amount of neuroplasm at the amputation surface which is required for regeneration may be similar to that for the amphibian.
Environmental influence on ovulation and embryonic development in Rana pipiens
Authors: Lehman Grace C. 
Published: June 2005

AbstractEnvironmental effects on ovulation and embryogenesis in Rana pipiens were assessed using both freshly‐captured fall animals and laboratory‐conditioned females which had undergone vitellogenesis in the laboratory. Frogs in both categories were divided into two groups. Ovulation was hormonally induced in one group of females prior to cold exposure and in the second group of animals following an 8‐week period at 4°C with an 8L 16D photoperiod. The incidence of both ovulation and normal embryonic development was increased following exposure of the animals to low temperatures and short daylength. Those animals which only partially ovulated prior to cold treatment did not respond to hormone injections following the period of cold exposure. Examination of the ovaries of these females revealed a much greater degree of oocyte resorption than was found in frogs whose initial ovulation was induced only after exposure to cold temperatures. The administration of ovulation‐inducing hormones prior to artificial hibernation may thus have initiated a phase of oocyte resorption which progressed even at 4°C.The incidence of ovulation was similar in wild‐caught and laboratory‐conditioned females, but eggs from the latter showed a much lower percentage of development to Shumway stage 20. This effect may have been related to differences in the environmental factors to which the two groups were exposed during oogenesis.
Inhibition of hamster sperm acrosome reaction and fertilization by oligomycin, antimycin A, and rotenone
Authors: Rogers B. Jane , Ueno Marilynn , Yanagimachi Ryuzo 
Published: June 2005

AbstractEffects of respiratory inhibitors (oligomycin, antimycin A and rotenone) on hamster sperm acrosome reaction and fertilization were studied. Hamster spermatozoa were incubated in a mixture of a modified Tyrode's solution and heat‐treated human serum in the presence and absence of inhibitors. Oligomycin (2.4 × 10−6 M), antimycin A (2.5 × 10−6 M) and rotenone (2.5 × 10−6 M) all reduced the incidence of the sperm acrosome reaction and fertilization without markedly affecting sperm motility. Antimycin A was the most effective in reducing the incidence of acrosome reaction. A reduction in the rate of fertilization was found in the presence of all of these respiratory inhibitors. The reduction in the incidence of acrosome reaction and fertilization by respiratory inhibitors implies an intimate relationship between high energy production (via respiration and oxidative phosphorylation) and capacitation and the acrosome reaction of spermatozoa. The necessity of oxidative metabolism for efficient capacitation and acrosome reaction of spermatozoa is suggested.
Factors influencing ovulation in the Mexican axolotl as revealed by induced spawnings
Authors: Humphrey Rufus R. 
Published: June 2005

AbstractAxolotl females may be induced to spawn by injecting them with small doses of FSH prior to mating. Data on the different categories of spawnings obtained by this procedure have established the following points.
Spawnings of injected females completely without fertile eggs are small (173 eggs average). Courtship occurred in some of the matings (spermatophores found) but not in all. Spawnings of injected but uninseminated females re‐mated with a second (or third) male, not becoming inseminated, but all having some eggs fertilized by contact with spermatophores (showing courtship) are likewise small (219). It can be concluded that courtship of the injected female, even by two successive males, does not stimulate ovulation of additional eggs.
Insemination of injected females induced additional ovulation more or less frequently, depending upon whether the female was inseminated by the first, or a subsequent male with whom she was mated. Insemination by the first male, within 15 hours after the female had been injected with FSH, resulted in stimulation of ovulation in 36 of 54 spawnings (67%). The 36 spawnings averaged 593 eggs per spawning. In contrast, insemination by a second or third male, more than 15 hours after the female was injected with FSH, resulted in stimulation of additional ovulation in only 4 of 21 spawnings (19%).
Survival time of spermatozoa in inseminated females has been established. Considerable numbers of spermatozoa capable of fertilizing eggs survive for about one week. A few survive for 11 to 12 days, but none was found after 14 days.
Stages in the post‐hatching development of Aplysia californica
Authors: Kriegstein Arnold R. 
Published: June 2005

AbstractIn order to study the development of the nervous system of the marine mollusc, Aplysia californica, it is necessary objectively to assess the maturity of individual specimens. This can be done by defining stages in the life cycle. The post‐hatching development can be divided into four phases: planktonic, metamorphic, juvenile, and adult. These phases can be further subdivided into 13 stages on the basis of behavioral and morphological characteristics visible in living specimens: Stage 1, newly hatched; Stage 2, eyes develop; Stage 3, the larval heart beats; Stage 4, maximum shell size is reached; Stage 5, the propodium develops; Stage 6, red spots appear; Stage 7, the velum is shed; Stage 8, eyebrows appear; Stage 9, pink color develops; Stage 10, white spots appear; Stage 11, rhinophores grow; Stage 12, the genital groove forms; Stage 13, egg laying begins.Reconstructions from serial sections taken from specimens fixed at each of these stages reveal the sequence of formation of the major organ systems. The nervous system develops gradually. The cerebral and pedal ganglia are present at Stage 1, the optic ganglia develop at Stage 2, the abdominal, pleural, and osphradial ganglia at Stage 3, the buccal ganglia at Stage 5, and the genital ganglion at Stage 13.Because Aplysia develops gradually, it is possible to analyze the contribution which gastropod torsion makes to the different phases of the life cycle. The Aplysia embryo undergoes 120° torsion prior to Stage 1. The major visceral organs, the digestive system, heart, gill, and visceral nervous system, develop subsequently in their post‐torsional positions. After metamorphosis, there is a partial de‐torsion which involves only the digestive system. Torsion of the digestive system may therefore be beneficial only to the pre‐metamorphic larva, and not to the postmetamorphic juvenile.
Urea transport in the dogfish kidney
Authors: Hays Richard M. , Levine Sherman D. , Myers Jack D. , Heinemann Henry O. , Kaplan Michael A. , Franki Nicholas , Berliner Henry 
Published: June 2005

AbstractThere is increasing evidence that urea movement across many epithelia involves more than passive diffusion. Of particular interest is the observation that urea transport across the erythrocyte membrane and across the vasopressin‐stimulated urinary bladder of the toad occurs by facilitated diffusion, and can be selectively inhibited by phloretin and chromate. These inhibitory agents have been employed in studies of renal urea reabsorption by the spiny dogfish Squalus acanthias. Both agents inhibit urea reabsorption; the effect of chromate is of particular interest, since it blocks urea reabsorption to a proportionately greater extent than sodium reabsorption, and does so irreversibly.
Microtubules in the “chloride cell” of the gill and disruptive effects of colchicine on the salt balance of the sea water adapted Mugil capito
Authors: Maetz J. , Pic P. 
Published: June 2005

AbstractElectron‐microscopic examination of the gill of the grey mullet, Mugil capito adapted to sea water, reveals the presence of numerous microtubules in the apical region of the mitochondria‐rich cells. No microtubules are found in other types of epithelial cell. Exposure of the fish to colchicine (10−4M) for four hours induces a 20% increase of plasma Na and Cl. Colchicine leaves the water permeability of the gill unchanged but Cl and Na exchange fluxes are inhibited by 30–50% and the gill potential pattern is altered. Salt gain replaces salt excretion across the gill. The K dependent Na and Cl efflux components, independent of the gill potential shift produced by K, are totally inhibited by colchicine. Exposure to lumicolchicine is not followed by a significant change of these Na and Cl efflux‐components and potential pattern. The possibility that microtubules intervene in the salt excretion process across the chloride cells is discussed.
Characterization of gill (Na+ K)–activated adenosine triphosphatase from chinook salmon, Oncorhynchus tshawytscha
Authors: Johnson S. L. , Ewing R. D. , Lichatowich J. A. 
Published: June 2005

Abstract(Na +K)‐activated ATPase activity from gills of yearling spring chinook was examined using a new rapid assay method. Characterization of the enzyme activity was performed. Optimal activity was obtained at pH 7.2 in the presence of 240 mM NaCl, 120 mM KCl, 20 mM MgCl2 and 10 mM Na2ATP. Maximal inhibition of the enzyme was observed in the presence of 0.5 mM ouabain. Differential centrifugation indicated that 75% of the enzymatic activity was sedimented at 1000 × g. Only 8% of the activity was found in the microsomal pellet. Treatment with 0.1% sodium deoxycholate liberated activity from the 1000 × g pellet and elevated the activity of the microsomal pellet from 8% to 51% of the total activity. This treatment caused a loss of 20% of the original activity of the preparation.Statistical analysis of the sampling procedure for gill (Na +K)‐activated ATPase activity indicated that there was small variation in the technique itself when compared to variation between the individual gill arches and between individual fish. Results indicate that for meaningful comparisons of groups of fish, the sampling of the gill arches must be standardized and a large number of individual fish must be sampled.
Killifish opercular skin: A flat epithelium with a high density of chloride cells
Authors: Karnaky Karl J. , Kinter William B. 
Published: June 2005

AbstractIn teleosts the head region, particularly the gills, plays the key role in osmoregulatory NaCl transport, presumably by mechanisms located in the chloride cell. As interest has focused on specific mechanisms of chloride cell function, two classical preparations, the intact fish and the isolated, perfused gill, have continued to serve as the only available model systems. However, both of these preparations have severe limitations, e.g., as they are not flat sheets, they cannot be studied readily under the ideal thermodynamic conditions achieved with the short‐circuit current technique. The present study describes the histology and ultrastructure of a particular area of skin in the head region of both killifish (Fundulus heteroclitus) and sea raven (Hemitripterus americanus). This skin lies on the inside of the operculum and possesses a flat epithelium containing chloride cells. In the present study the identity of the chloride cell in this epithelium was definitively established with the electron microscope. Although the opercular epithelium from the marine sea raven contains few chloride cells, that from the euryhaline killifish adapted to pond water, 100%‐, and 200% artificial seawater is predominately chloride cells. Significantly, the teleost gill has never been reported to contain more than 10% chloride cells. Thus the opercular skin of the killifish can serve as a model to study the adaptive role of chloride cells in euryhaline teleosts. A separate electrophysiological study has demonstrated that the short‐circuit current technique can be applied to this skin.
Renal tubule ion transport and collecting duct function in the elasmobranch little skate, Raja erinacea
Authors: Stolte H. , Galaske R. G. , Eisenbach G. M. , Lechene C. , Schmidt‐Nielsen B. , Boylan J. W. , Antkowiak D. , Patel Y. , Niermann U. 
Published: June 2005

AbstractRenal micropuncture and microdissection techniques with ultra‐micro fluid analysis have been applied to evaluate single nephron function in the skate, Raja erinacea.We have divided the skate nephron into three proximal tubular segments (PTS I‐III), three distal coilings (DC I‐III), and a countercurrent loop system located between the proximal segments and the distal coilings.The collecting duct is the principal site of urinary dilution. Following exposure of the fish to 75% seawater for about 24 hours, the sodium concentration difference between the end collecting duct lumen and plasma is decreased sufficiently to account for the urinary dilution. The principal site for magnesium, phosphate and sulphate secretion appears to be PTS II. This segment is located on the ventral surface of the kidney. PTS II is also the main nephron site for reabsorption of sodium and chloride in excess of water.
Free amino acids in tissues of the skate Raja erinacea and the stingray Dasyatis sabina: Effects of environmental dilution
Authors: Boyd Thomas A. , Cha Chung‐Ja , Forster Roy P. , Goldstein Leon 
Published: June 2005

AbstractConcentrations of individual free amino acids were determined in various tissues of the skate (Raja erinacea) and the stingray (Dasyatis sabina), and the relationship of cellular free amino acid concentrations to intracellular osmoregulation was investigated by adapting these elasmobranchs to halfstrength seawater. Each tissue characteristically had high levels of certain specific amino acids. Skate wing muscle contained high concentrations of sarcosine and β‐alanine, skate heart had high concentrations of taurine, and skate erythrocytes had high levels of taurine and β‐alanine. Amino acid levels in skate plasma were very low. High concentrations of taurine and glutamate were found in stingray brain. Adaptation of skates and stingrays to half‐strength seawater was accompanied by significant decreases in concentrations of the major free amino acids in skate wing muscle and erythrocytes and in stingray brain, but not in skate heart. The data suggest that in these elasmobranchs certain specific free amino acids are selectively involved in intracellular osmoregulatory mechanisms.
Cyclic AMP regulation of active chloride transport in the rectal gland of marine elasmobranchs
Authors: Stoff Jeffrey S. , Silva Patricio , Field Michael , Forrest John , Stevens Arthur , Epstein Franklin H. 
Published: June 2005

AbstractActive transport of chloride in the salt secreting rectal gland of the dogfish Squalus acanthias is markedly stimulated by the addition of theophylline (0.01 to 5 mM) or dibutyryl cyclic AMP (0.05 mM) during in vitro perfusion. The effect occurs promptly and may persist for two hours. Specific hormonal effectors have not yet been identified. The isolated perfused rectal gland thus offers a unique opportunity to examine the cellular mechanisms of active chloride secretion.