bluuebunny/crossref_metadata_2025_split huggingface dataset:
Na is essential for activation of the inseminated sea urchin egg
Authors: Chambers Edward L. 
Published: June 2005

AbstractThe presence of at least 2.5 mM Na during the first several min after insemination is requied for the activation of sea urchin eggs. Of those chemical species examined that exist entirely as cations, and which did not activate the unfertilized egg, only Li substitutes for Na. Ammonium and other amines, with pKa values between 9 and 10.8, in the complete absence of Na (a) can induce nuclear activation of unfertilized eggs, and (b) permit the development of the early fertilized egg through the stage that normally requires Na.
Effects of epididymal occlusion on sperm maturation in the hamster
Authors: Cummins J. M. 
Published: June 2005

AbstractHamster epididymal spermatozoa were isolated in the caput, corpus and cauda regions for one, two and three days. Sperm suspensions from these regions were assessed for morphology, motility, viability; and for fertility by A.I. The ability to capacitate was tested by checking for acrosome reactions when the sperm were cultured under defined capacitating conditions at 37°C in vitro.Normal, mature cauda sperm were highly fertile (overall 77% of ova fertilized) and showed 50–80% incidence of acrosome reactions after six hours in culture. Isolation for up to three days had no effect.Immature sperm from the caput and corpus were poorly motile, infertile, and did not manifest an acrosome reaction. Isolation for one and two days produced improvements in motility, and distal migration of the cytoplasmic droplet akin to normal maturation, however the sperm remained infertile and did not capacitate in vitro. Survival after three days isolation was poor.Thus the development of fertilizing ability in hamster epididymal spermatozoa is closely related to the ability to manifest an acrosome reaction in vitro; however it is only poorly correlated with motility and morphology. Completion of sperm maturation in this species appears to require the environment of the cauda epididymidis.
Changes in the shape of the developing vertebrate nervous system analyzed experimentally, mathematically and by computer simulation
Authors: Jacobson Antone G. , Gordon Richard 
Published: June 2005

AbstractTwo forces are necessary and sufficient to produce the transformation of the newt neural plate from a hemispheric sheet of cells one cell thick to a keyhole shape. These forces are: (1) a regionally programmed shrinkage of the surface of the neural plate (accomplished by contraction of the apical surfaces of the neural plate cells and elongation of these cells perpendicular to the plate); and (2) displacement of the whole sheet caused by elongation of either the notochord or the overlying neural plate cells in the antero‐posterior direction. A computer simulation and mathematical analysis (“morphodynamics”), together with experiments and observations on embryos, were used to deduce the morphogenesis of the neural plate from these forces.
Release of DNA template restrictions in rabbit spermatozoa and rat liver nuclei
Authors: Zirkin Barry R. , Boison Adele , Heston W. D. W. , Coffey Donald S. 
Published: June 2005

AbstractThe effects of disulfide reduction on DNA template activity of rabbit sperm and rat liver nuclei are compared. After treatment of rabbit spermatozoa with 5 mM dithiothreitol and 1% Triton X‐100 for 90 minutes at room temperature, sperm nuclei decondense and nuclear template restrictions for DNA synthesis are released. By contrast, similar thiol treatment of isolated rat liver nuclei fails to release DNA template restrictions. These results suggest a significant difference in the control of template activity in mammalian sperm and somatic cell nuclei.
Correlation of enzymatic activity, muscle myoglobin concentration and lung morphology with activity metabolism in snakes
Authors: Ruben John A. 
Published: June 2005

AbstractIn vitro activity of the anaerobic enzymes phosphofructokinase and lactic dehydrogenase from axial muscle tissue of Coluber constrictor, Crotalus viridis and Lichanura roseofusca was shown to correlate with levels of lactate production during activity by these snakes. Additionally, gross and histological lung structure and axial muscle myoglobin concentration were investigated in these species. Coluber was shown to have the most complex lung structure and highest muscle myoglobin content. These are interpreted to be correlated with high aerobic scope in Coluber. Finally, the ophidian saccular lung is postulated to assist in maintanance of high tidal volume.
The regeneration of brachial nerves of contralateral origin into denervated fused newt forelimbs
Authors: Goshgarian Harry G. 
Published: June 2005

AbstractPrevious studies involving the end‐to‐end fusion of the forelimbs of the adult newt have demonstrated that new limbs can regenerate from the transected ends of proximo‐distally reversed limb segments. The limb regeneration could only have been initiated by nerve fibers of contralateral origin. The purpose of the present study is to describe histologically the manner in which nerve fibers of contralateral origin regenerate through the junction of fused limbs into the opposite limb. The first sign of nerve regeneration into the opposite limb was observed at eight days post fusion. The nerves crossed over into the opposite, originally denervated limb in a highly dispersed manner. These nerve fibers eventually aggregated, however, either under the skin or within persisting nerve trunks. By 19 days post fusion the nerve fibers had reached the elbow region of the originally denervated limb and by 25 days they were seen at the most proximal extent of the limb. The diameters of the axons seemed smaller than the diameters of regenerating axons observed in non‐fused newt forelimbs.
Activation of the dormant podocyst of Chrysaora quinquecirrha (schyphozoa) by removal of the cyst covering
Authors: Black R. E. , Enright Rosemary T. , Sung Lan‐Ping 
Published: June 2005

AbstractScyphistomae of the jellyfish, Chrysaora quinquecirrha, produce encysted basal buds called podocysts. Podocysts remain dormant for periods of 0 to 25 months at 25 ° C and 15 o/oo salinity. If the cyst coat is punctured it is repaired and 92% of cysts remain dormant, while about 3% excyst and form polyps in a few days and about 5% are nonviable. If the cyst coat is removed entirely, it is always replaced by a new thinner one. Sixty to 75% of the viable cysts then excyst and form polyps, while 25 to 40% remain dormant within the new covering. Removal of the new coat from these results in unusually rapid formation of polyps. The cytological events to excystment are described. Incorporation of radioactive phenylalanine into cellular protein is greatly stimulated by removal of the cyst covering. Free amino acids in the podocyst are at much lower levels than in polyp tissue.
The reacquisition of cell adhesiveness following tissue disaggregation by eleven different agents
Authors: Wiseman Lawrence L. , Hammond William R. 
Published: June 2005

AbstractDisaggregation of seven‐day embryonic chick neural retina tissue by eleven different agents produces cells which require variable periods of time to become aggregation competent in culture. The time required between cell isolation and the beginning of inter‐cellular adhesion in rotation culture is dependent upon the particular isolating agent used and ranges from zero to sixty minutes.
Induction of meiosis by injection of heterologous protein kinase and phosphorylase kinase in Xenopus laevis oocytes
Authors: Moreau Marc , Guerrier Pierre , Doree Marcel 
Published: June 2005

AbstractMeiosis reinitiation has been triggered by injection of beef heart protein kinase or rabbit phosphorylase kinase into Xenopus laevis oocytes. Successful injections are followed by germinal vesicle breakdown, chromosome condensation, formation of a normal meiotic spindle, and appearance of an amplifiable maturation promoting factor. Meiosis reinitiation does not occur when the enzymes are introduced into the oocytes simultaneously with EGTA or after pretreatment with cycloheximide. Antipain, an antiprotease which abolishes the response of oocytes to progesterone, does not suppress the meiosis reinitiation induced by injection of protein kinase or phosphorylase kinase.
Electrophoretic introduction of calcium ions into the cortex of Xenopus laevis oocytes triggers meiosis reinitiation
Authors: Moreau Marc , Doree Marcel , Guerrier Pierre 
Published: June 2005

AbstractMeiosis reinitiation has been triggered via electrophoretic driving of Ca++ into the cortex of Xenopus laevis oocytes freed from functional follicle cells by collagenase treatment. Mg++ could not be substituted for Ca++. Ca++ induced maturation resembles progester‐one induced maturation in so far both are inhibited by cycloheximide, give rise to amplifiable MPF in the cytoplasm of treated oocytes and allow chromosome condensation and the formation of a normal meiotic spindle.
Vaginal opening and early estrous cycles in rats raised at a low ambient temperature
Authors: Nazian S. J. , Piacsek B. E. 
Published: June 2005

AbstractRats raised from day 2 of life at an ambient temperature of 10° showed delayed vaginal opening when compared to controls raised at 22°. Coldraised animals were also lighter in weight at the time of vaginal opening and had significantly longer estrous cycles. Low temperature may cause these effects either by suppressing prolactin secretion or, more probably, by elevating thyroid hormone levels which in turn suppress serum gonadotropin concentrations.
28 s and 18 s ribonucleic acid from mammalian spermatozoa
Authors: Betlach Charles J. , Erickson Robert P. 
Published: June 2005

AbstractThe majority of RNA in spermatozoa from the epididymis and ductus deferens of mice was found to be 28 s and 18 s RNA. This RNA was also seen in human ejaculated spermatozoa. Our evidence indicates that little or none of the 28 s and 18 s RNA is transcribed in the maturing mouse spermatozoa and that the majority is synthesized in the primary spermatocyte. This RNA may be necessary to maintain post‐meiotic translation during spermatogenesis.
The role of divalent cations in activation of the sea urchin egg. I. Effect of fertilization on divalent cation content
Authors: Azarnia Roobik , Chambers Edward L. 
Published: June 2005

AbstractThe Ca and Mg content of unfertilized sea urchin eggs (3 and 21 μmole/ml eggs) remains remarkably constant over periods of hours, even when the eggs are suspended in Ca‐ or Mg‐free sea water. After fertilization the Ca content of eggs in regular sea water increases sharply by about 20%, followed by a decrease to the unfertilized level by 40 minutes. However, if the fertilized eggs are washed three minutes in Ca‐free sea water a sharp decrease in the Ca content occurs amounting to 30% of the total in the first 40 minutes, with little change thereafter. Suspension of the eggs in Ca‐free sea water results in an even greater loss of Ca amounting to about 43% of the total in the same time interval, followed by a continuing slow loss. It is concluded that fertilization initiates the intracellular release of Ca, which is then extruded. For unwashed eggs this change is masked by the simultaneous generation of new extracellular coats with high affinity for Ca.Changes in the Mg content of fertilized eggs follow the same general pattern except that absorption of this divalent cation to the extracellular coats is minimal.
Ultrastructural characterization of the accessory lobes of Lachi (Hofmann's nuclei) in the nerve cord of the chick. I. Axoglial synapses
Authors: De Gennaro Louis D. , Benzo Camillo A. 
Published: June 2005

AbstractLight microscopic observations of the accessory lobes of Lachi of one‐day‐old chicks show that this tissue contains abundant amounts of glycogen and consists of cells which are similar in appearance to those of the glycogen body. Ultrastructural studies reported here for the first time confirm the presence of glycogen‐rich cells in the accessory lobes and reveal that these cells are intimately associated with nerve axons. The finding of synaptic complexes and other junctional specializations between nerves and accessory lobe cells suggests that they may have a functional relationship with the nervous system. It is felt that the accessory lobe cells may be neuroglia, possibly of the astrocytic type, which have an innate capacity for glycogen storage. While the functional significance of such glycogen remains obscure, the close morphological association between neurons and the accessory lobe cells enhances the hypothesis put forth by us regarding the glycogen body, namely that neural glycogen is involved in myelin synthesis in the avian nervous system.
Respiratory behaviour of sea‐urchin spermatozoa. II. Sperm‐activating substance obtained from jelly coat of sea‐urchin eggs
Authors: Ohtake Hideki 
Published: June 2005

AbstractA sperm‐activating substance (SAS) was obtained from the jelly coat of sea‐urchin ova and its chemical properties were investigated in three seaurchin species. The SAS was partially purified from the jelly coat of pseudocentrotus eggs through several steps of purification by procedures consisting of charcoal adsorption, on Sephadex G‐15 columns. The partially purified SAS was found to contain a ninhydrin‐positive material and is inactivated by pronase digestion. The molecular weight of SAS was estimated as about 630 by gel‐filtration through Sephadex G‐25, and the isoelectric‐point of SAS is located at about pH 5.3 by isoelectrofocusing method. The SAS is non‐volatile, alcohol‐soluble, and labile in a diluted alkaline or acid solution. The origin of SAS is discussed.
Chemotactic behavior of mutants of the nematode Caenorhabditis elegans that are defective in their attraction to NaCl
Authors: Dusenbery David B. 
Published: June 2005

AbstractWild‐type C. elegans and 16 derivative strains previously selected for defective attraction to NaCl and shown to carry single‐gene mutations were tested for their responses to nine chemical stimuli to which the wild‐type responds. These were the attractants Na+, Cl−, OH−, cyclic AMP, CO2 in borate buffer, and pyridine and the repellents D‐tryptophan, CO2 in phosphate buffer, and acid. All together 563 measurements were performed. Most strains were defective in most responses but responded normally to some chemical stimuli. In a few cases mutant strains avoided a chemical that attracted the wild‐type. Analysis of the patterns of defective responses among these mutants indicates that there are probably at least four different receptors. If results previously reported are included, the minimum number of receptors is increased to six. These mutations appear to have rather discrete effects on behavior.
Electron microscope assessment of fertilization of rabbit ova treated with Concanavalin A and Wheat Germ Agglutinin
Authors: Gordon M. , Dandekar P. V. 
Published: June 2005

AbstractZonaless rabbit ova, exposed to Concanavalin A or Wheat Germ Agglutinin, then to uterine capacitated sperm produce pronuclear, 2 and 4 stage embryos that are indistinguishable from controls. Absence of cortical granules indicates that the ova were fertilized and not merely activated. Survival of lectin‐bearing receptors during the period necessary for fertilization was evaluated in ova marked with ferritin‐conjugated lectin.
The relationship between growth, developmental stage and postamputation age of the regeneration blastema of the newt, Notophthalmus viridescens
Authors: Connelly Thomas G. 
Published: June 2005

AbstractThe growth of the regeneration blastema of the newt forelimb has been quantitated and analyzed as a function of postamputation age, developmental stage animal weight, animal length, and cross sectional diameter of the blastemal base in both the anteroposterior and dorsoventral dimensions. Correlation coefficients computed for these variables show that growth of the regenerate in both length and volume is more closely correlated with developmental stage than postamputation age. In addition, the results show a linear relation between the loge (regenerate length) and developmental stage, and between regenerate length and volume. Thus, length can be used to assess growth of the regenerate according to a developmental rather than a chronological time scale. There were no significant correlations between regenerate length or volume and animal length, animal weight or cross sectional dimensions of the blastemal base. These results show that one can use a randomly selected population of animals and study the growth of the regeneration blastema by relating to a developmental time scale through a logarithmic transformation of the linear growth data.
Acetylcholinesterase isozymes in developing mouse tissues
Authors: Henderson Nanine S. 
Published: June 2005

AbstractSeveral isozymes of acetylcholinesterase are separated by 10% acrylamide gel electrophoresis of mouse blood, brain, heart, muscle and tongue tissues. Two isozymes migrating near the origin are described which show changes in relative activity during development. The faster of the two bands is proportionately higher in concentration in embryonic tissues and is highly specific for the acetylthiocholine iodide substrate. This isozyme corresponds to the erythrocyte membrane AChE in electrophortic mobility and substrate specificity. The slower of the two bands is predominant in adult tissues and exhibits considerable cross reaction with the butyrylthiocholine iodide substrate. During embryonic and postnatal developmental stages there is a gradual shift from the faster migrating isozyme toward a predominance of the slower migrating isozyme.
The kinetics of rosette‐forming cell response against sharp erythrocytes in the lizard
Authors: Pillai P. Subramonia , Muthukkaruppan Vr. 
Published: June 2005

AbstractThe immune response of the lizard Calotes versicolor to sheep erythrocytes (SRBC) has been studied in terms of the appearance of rosette‐forming cells (RFC) and plaque‐forming cells (PFC). Two distinct RFC peaks were observed in the spleen, one within three days and the other, between six and ten days after immunization with 0.1 ml of 2.5%, 0.25% or 0.025% SRBC. Lower doses of antigen induced greater and quicker first RFC peaks, whereas higher doses stimulated increasing numbers of PFC as well as quicker appearance of second RFC peak. The early increase in RFC response is suggested to be due to “helper” activity and the second peak to the proliferation of precursors of antibody producing cells. Formalinised SRBC induced the formation of the first RFC peak but not the second, thus supporting the above suggestion. The interesting possibilities with regard to the dissociation of various cellular events during the development of antibody response in the lizard immune system are discussed.
Developmental expression and biochemical characterization of catalases and aminopeptidases of Nassarius obsoleta
Authors: Nelson Mark S. , Scandalios John G. 
Published: June 2005

AbstractElectrophoretic analysis of catalase isozyme patterns of Nassarius obsoleta indicates that these isozymes are products of two separate loci. Five aminopeptidase isozymes have also been detected in N. obsoleta and the data suggest that at least two loci encode these aminopeptidase isozymes. Experiments designed to test for the interconvertibility of the isozymes indicate that the two catalase isozymes and that two of the five aminopeptidase isozymes tested were not conformational artifacts but distinct genetic products. No change in catalase isozyme expression, but considerable quantitative variation in catalase specific activity was noted during early developmental stages of N. obsoleta. Both qualitative and quantitative changes were noted in aminopeptidase expression during early developmental stages. This paper also describes several physicochemical parameters for each of the two enzymes under study.
Physiology and chemistry of cerebrospinal fluid, aqueous humor and endolymph in Squalus acanthias
Authors: Maren Thomas H. 
Published: June 2005

AbstractBy means of the appropriate isotopes injected into the spiny dogfish, Squalus acanthias, the transfer of all major ions into cerebrospinal fluid (CSF), aqueous humor (A) and endolymph (E) was studied. In addition, the effect of raising pCO2 in sea‐water upon HCO concentration of these fluids was measured. In the several types of experiments, acetazolamide or methazolamide was used to inhibit completely carbonic anhydrase. The rates of fluid formation and ion transfer in CSF and A were fairly close, but those for E were far slower. The general pattern of ion transport in the three fluids were the same, Na+ (or Na+ + K+ in E) entry > Cl‐ entry, and the difference was HCO. The greater rate constants for HCO, increase in its entry rate by elevation of pCO2, and inhibition of its appearance by the sulfonamides, show that this is a special case of transport; the ion is formed in secretory cells from gaseous CO2 + OH‐. Secretory cells at sites of formation of all the fluids contain both carbonic anhydrase and Na+‐K+‐ATP‐ase, which subserve HCO formation and Na+ (or K+) transport. Comparison of these results with studies in mammals show that the vertebrate pattern for secretion of these three fluids is well established in the elasmobranch.
Molecular aspects of chloride cell formation in Oncorhynchus. II. Isolation and characterization of gill transfer RNA's during active salt secretion
Authors: Conte F. P. 
Published: June 2005

AbstractThe transfer ribonucleic acids (tRNAs) from gill filaments of coho salmon, Oncorhynchus kisutch, have been isolated and were separated into individual species of acceptor tRNAs by reversed‐phase column chromotography. Crude tRNAs isolated from gill filaments undergoing active salt excretion were acylated with 14C‐amino acids and combined with tRNAs acylated with 3H‐amino acids, but obtained from non‐secreting filaments. The radioactively labeled tRNA mixture was cochromatographed and the results showed significant differences in the elution profiles of tRNAasp and tRNAtyr. These elution profiles may reflect the differentiation of the chloride cell population that is found within the gill epithelium.
Volume regulation of muscle fibres in the killifish, Fundulus heteroclitus
Authors: Schmidt‐Nielsen Bodil 
Published: June 2005

AbstractCell volume regulation has been observed in vitro in many tissues. In the killifish it was studied in vivo during transfer from SW to FW and from FW to SW. It was found that the cell water content in acclimated fish varies inversely with the osmolality of the medium. During transfer from SW to FW the plasma osmolality decreased. Cell swelling was prevented through net loss of solutes from the cells. The solutes lost were not potassium or sodium and are presumed to be organic solutes. During transfer from FW to SW the plasma osmolality increased, cell shrinkage occurred and no significant increase in cell solute content could be found during eight hours. During prolonged acclimation cell water content returns to a higher value.
Cytological changes in chloride cells following altered ionic media
Authors: Doyle William L. 
Published: June 2005

AbstractThe rock‐eel, Pholis, and guppy, Lebistes, adapted to fresh or saltwater were exposed to low concentrations of unnatural ions or transport inhibitors including thiocyanate, potassium and ouabain, which caused cytological alterations in the chloride cells of the gills. Some of the other substances used caused generalized damage to intracellular membranes. Highly ordered geometric arrays of the tubular reticulum were produced under certain conditions. The conditions of the experiments suggest that the tubular reticulum plays a role in ionic segregation and that the normal configuration of the reticulum is dependent on the ionic composition of the intracellular milieu.