bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of streptomycin on the structure and function of the photoreceptor apparatus of Euglena gracilis
Authors: Ferrara Romano , Banchetti Rosalba 
Published: June 2005

AbstractThe progressive modification of the photoreceptor apparatus, induced by addition of streptomycin (SM) to cultures of dark‐bleached Euglena, is correlated with the change of the photomotor response. One of the effects of drugtreatment is the reduction of carotenoid synthesis; the total carotenoid content decreases from 0.20 to 0.01 pg/cell after seven weeks of treatment. The parallel progressive reduction of the stigma vesicles and their carotenoid content is observed by electron microscopy. Micrographs and microscopic fluorescence observations do not indicate alterations of the paraflagellar body (PFB). During the SM‐treatment the initial positive phototactic response decreases until it disappears after five weeks.The loss of the absorbing properties of the stigma prevents the cell from orienting itself towards the light. The probability that the cell orients seems to depend on the light modulation amplitude and the light/dark ratio on the PFB due to the shading device. After seven weeks of SM‐treatment we observe a cell movement away from the illuminated zone. The mechanism of this escape is discussed.
Three dimensional structure of the endochorion in wild type Drosophila melanogaster
Authors: Margaritis Lukas H. , Petri William H. , Kafatos Fotis C. 
Published: June 2005

AbstractThe endochorion of the Drosophila melanogaster eggshell has been isolated and its structure examined by transmission and scanning electron microscopy. In the main shell the thin inner endochorion (floor) shows small pits or pores and characteristic fenestrae crossed by irregular strands; vertical columns surrounded by air spaces separate this layer from the thick outer endochorion (roof) which is covered by a regular, external reticulum of thin fibers. The endochorion of the respiratory horns has sharply divided dorsal and ventral surfaces, with characteristic structures somewhat reminiscent of the floor and the external reticulum of the roof, respectively.
Electrophysiological responses of chemosensitive sensilla in the wolf spider
Authors: Drewes Charles D. , Bernard Rudy A. 
Published: June 2005

AbstractElectrophysiological recordings from single, open‐pored sensilla on the pedipalps of intact wolf spiders confirm the presence of numerous chemosensory neural units in the sensilla. The presence of one or two mechanosensory neurons in these sensilla is also confirmed.
The nature and development of sex attractant specificity in cockroaches of the genus Periplaneta. III. Normal intra‐ and interspecific behavioral responses and responses of insects with juvenile hormone‐altered antennae
Authors: Schafer Rollie 
Published: June 2005

AbstractMale cockroaches of the species Periplaneta americana rely on a female‐produced airborne pheromone to initiate courting behavior. The male responds to the presence of the pheromone with rapid, oriented locomotion. Contact with the female (or other males or larvae) elicits wing‐raising and other responses characteristic of male courtship behavior. Males of other species within the genus Periplaneta also respond to a female‐produced pheromone, but with less intensity than P. americana. Cross‐species testing shows that P. brunnea males respond to the Periplaneta pheromone with the same intensity elicited by the P. brunnea pheromone. A second reaction group containing P. australasiae, P. fuliginosa, and P. japonica also responds to the P. americana pheromone and their conspecific pheromones, but with a low intensity characteristic of these species. Alteration of the antennal morphology of P. americana males can be experimentally induced by manipulating the level of juvenile hormone during development. Males with a full adult complement of olfactory receptors all respond behaviorally to the pheromone. Adult males with larval antennae produced by bilateral treatment with exogenous juvenile hormone‐mimic do not respond to the pheromone, although they are completely adult in other respects.
Activation of hamster eggs by pricking
Authors: Uehara T. , Yanagimachi R. 
Published: June 2005

AbstractWhen mature unfertilized eggs of the golden hamster were pricked with a glass needle, nearly 80% of them were activated. The diameter of needle was of critical importance for the successful induction of activation. It appeared that extracellular calcium was not necessary for the establishment (reception) of stimulation by pricking but was necessary for later phases of activation. The possible mechanisms by which pricking with a needle triggers the activation of the egg were compared with the mechanisms by which divalent ionophore induces activation.
Kinetics of sperm penetration into and the zona reaction of mouse ova inseminated in vitro
Authors: Wolf D. P. , Hamada M. , Inoue M. 
Published: June 2005

AbstractThe kinetics of capacitated epididymal sperm penetration into cumulus‐intact and completely cumulus‐free mouse ova were studied. Penetration was complete within two hours of insemination in cumulus‐intact ova incubated with 2 × 105 sperm/ml, as evidenced by the attainment of constant values for the mean number of sperm/penetrated ovum. A reduction in sperm viability was not a factor in the cessation of zonae penetration, since high penetration levels were obtained when fresh ova were added to 3‐hour inseminations containing “aged” sperm. With completely cumulus‐free ova, capacitated sperm penetration was initiated between one and two hours post‐insemination, and penetration levels increased over the entire 6‐hour incubation period. Final penetration levels for cumulus‐free ova were generally lower than for their intact counterparts. A constant value for the mean number of sperm/penetrated ovum was obtained after three hours of sperm exposure, indicating that the cumulus‐free ovum also underwent a zona reaction. Similar results were observed when sperm were capacitated in the presence or absence of cumulus and/or epididymal components, suggesting that inadequate capacitation was not the causative agent in the altered penetration of cumulus‐free ova. These results indicate that a zona reaction occurs in both ovum types, although in many cases only after multiple sperm penetration has occurred. In addition, evidence was obtained for a cumulus‐dependent enhancement in the rate of sperm penetration which could not be related to a cumulus involvement in sperm capacitation.
Variations in macromolecular antifreeze levels in larvae of the darkling beetle, Meracantha contracta
Authors: Duman John G. 
Published: June 2005

AbstractOverwintering larvae of the darkling beetle, Meracantha contracta, produce a macromolecular antifreeze that is similar in activity to the glycoproteinaceous and proteinaceous antifreezes found in some cold‐water, marine teleost fishes. The antifreeze is not present in the hemolymph of the Meracantha larvae in summer, but its production begins by late September in the wild population. The antifreeze reaches a maximum concentration in February, decreases slowly through spring, and disappears by early June. The supercooling points of the larvae are lowest in February, when the antifreeze levels are highest, and increase as the antifreeze concentrations in the hemolymph decrease in the spring. Larvae collected in mid‐February and warm‐acclimated lost the antifreeze within 12 days. Larvae collected in early September and cold‐acclimated required nearly two months to produce concentrations of antifreeze comparable to those of overwintering larvae. Temperature seems to be the major environmental factor responsible for the control of antifreeze levels in Meracantha; however, other environmental factors may also be involved.
Indirect immunofluorescent identification of 19S immunoglobulin‐containing cells in the intestinal mucosa of Xenopus laevis
Authors: Michea‐Hamzehpour Mehrbanou 
Published: June 2005

AbstractThe lymphoid structures in the gastrointestinal tract of immunized and non‐immunized, adult Xenopus laevis were studied by light and fluorescent microscopy. Serial sections stained with May‐Grun̈nwald Giemsa showed that lymphoid aggregations and scattered lymphoid cells are present along the whole digestive tract. The aggregations are few and rather small in the oesophagus and stomach, they are particularly voluminous in the duodenum.An indirect immunofluorescent technique using antisera against Xenopus laevis 19S and 7S immunoglobulins and their heavy polypeptide chains, revealed the presence of immunoglobulin‐containing cells in the duodenal region. The oesophagus and stomach were devoid of these. It has been shown that the immunoglobulins produced in the duodenal lamina propria are formed of both heavy and light polypeptide chains, and that the heavy chains are of the 19S H‐type.
Nuclear decondensation of mammalian spermatozoa: Changes during maturation and in vitro storage
Authors: Beil Richard E. , Graves Charles N. 
Published: June 2005

AbstractSwelling of the spermatozoan nucleus and decondensation of the chromatin occur soon after penetration of spermatozoa into the egg cytoplasm. This decondensation was duplicated in vitro by incubating pre‐ejaculatory ram, rabbit and bovine spermatozoa and also stored post‐ejaculatory bovine spermatozoa in 1% sodium dodecyl sulfate and 2.0 mM dithiothreitol. Spermatozoa obtained from the testis and epididymal caput, corpus and cauda showed a progressive resistance to nuclear decondensation, while no change was evident in the decondensation time of spermatozoa obtained from the epididymal cauda, vas deferens and ejaculated semen. There was also a significant increase in decondensation time after the spermatozoa had been stored in vitro at 25°C. This increased resistance to nuclear decondensation in the in vitro stored spermatozoa, reflecting an increase in cross‐linking within the spermatozoan histones by formation of disulfide bonds, may account for part of the increased embryonic mortality observed when spermatozoa are stored in vitro prior to insemination.
Low NA+ concentration: A factor contributing to diminished uptake and incorporation of amino acids by diapausing mouse blastocysts?
Authors: Van Winkle Lon J. 
Published: June 2005

AbstractUptake and incorporation of 14C amino acids by normal and diapausing blastocysts was found to be Na+ dependent with one exception. Delayed embryos preincubated 25 h in medium containing 124 mM Na+ had labeling characteristics independent of the Na+ concentration present during labeling. Since diapausing embryos preincubated 25 h in low Na+ medium (55 mM) retained their Na+ dependent labeling characteristics, delayed blastocysts may be in a low Na+ environment in situ. Low Na+ may explain why delayed blastocysts are unable to utilize radioactive methionine in vivo (Weitlauf and Greenwald, '68).
The synthesis and localization of glycosaminoglycans in striated muscle differentiating in cell culture
Authors: Ahrens Patricia Buckley , Solursh Michael , Meier Stephen 
Published: June 2005

AbstractDay 3 mass muscle cultures incorporated 35SO4= and 3H· glucosamine into specific glycosaminoglycans that were identified by a variety of methods (enzyme susceptibility, nitrous acid degradation, electrophoresis, thin layer chromatography). More than 75% of the newly synthesized glycosaminoglycans appeared in the medium. In the medium, the glycosaminoglycans consisted of primarily hyaluronic acid (∼35%) and chondroitin sulfate (∼40%) with smaller amounts of chondroitin (∼15%) and heparan sulfate (∼10%). Among the glycosaminoglycans that remained in the cell layer, chondroitin sulfate (∼45%) and heparan sulfate (20‐40%) predominated and only a small amount of chondroitin (∼15%) and hyaluronic acid (∼5%) were present. In both the medium and cell layer, greater than 80% of the chondroitin sulfate was chondroitin‐6‐sulfate. Although mass cultures contain some non‐muscle cell types which undoubtedly contributed to total glycosaminoglycan synthesis, susceptibility of the autoradiographic grains associated with cells in muscle clones to testicular hyaluronidase digestion suggests that at least some glycosaminoglycans (chondroitin sulfate, in particular) were synthesized by muscle cells.Transmission electron microscopy revealed the presence of ruthenium red staining globular units along the surfaces of myotubes. Destruction of the integrity of surface associated ruthenium red stained material by both Streptomyces hyaluronidase and testicular hyaluronidase suggests that both hyaluronic acid and chondroitin sulfate are present on muscle cell surfaces.
Characterization of the divalent cation activated adenosine triphosphatase from the membrane of the cardiac cell of Modiolus demissus demissus
Authors: Watts John A. , Pierce Sidney K. 
Published: June 2005

AbstractCell‐surface membranes from Modiolus demissus possess diva‐lent cation stimulated adenosine triphosphatase (ATPase) activity. The ATPase activity was stimulated by Ca2+ and to a lesser extend by Mg2+ in the presence of 3 mM ATP. When Ca2+ and Mg2+ were combined in the sea‐water ratio of 1:5, constant ATPase activity, intermediate between that in the presence of Ca2+ or Mg2+ alone, was observed from 10:50 mM to 1:5 mM Ca2+ Mg2+ The maximum rate of substrate hydrolysis occurred at pH 7.5–7.7, 37–45°C and with 3–5 mM ATP. Other triphosphate substrates were cleaved but ADP, AMP or p‐nitro‐phenylphosphate were not, showing that the enzyme is a triphosphatase Mg2+ ATPase activity was not inhibited by ouabain or ruthenium red, and only slightly inhibited by ethacrynic acid, while La3+ had a slight stimulatory effect.
Organ culture of mammalian skin and the effects of ultraviolet light and testosterone on melanocyte morphology and function
Authors: Glimcher Mark Edward , Garcia Raul I. , Szabó George 
Published: June 2005

AbstractScrotal skin of black Long‐Evans rats and human thigh skin were maintained in vitro as organ cultures for as long as 14 days, and examined histologically using the combined skin splitting and Dopa techniques. Selected rat skin cultures received testosterone in the culture medium and/or were irradiated with ultraviolet light (290–320 nm UVL). With increased time in culture, scrotal melanocytes round up and there is an increase in epidermal pigmentation. Human skin behaves similarly; after eight days in vitro human melanocytes also become rounded, but remain strongly Dopa‐positive. Addition of exogenous testosterone to cultured rat skin maintains dendritic morphology of melanocytes, but cell body size is still reduced. UVL irradiation stimulates melanocytes in rat skin cultures, maintaining their dendritic morphology and increasing epidermal and dermal pigmentation. Cultured skin receiving both UVL and testosterone illustrates a synergistic effect. Electron microscopic examination of cultured rat skin shows the presence of large melanosome complexes in keratinocytes, much larger than those found in vivo. Melanocytes appear to be active as they contain an extensive Golgi zone, rough endoplasmic reticulum, and melanosomes in various stages of formation. Dermis contained many dermal melanocytes and macrophages laden with melanosomes, correlating with the increased visible dermal pigmentation in vitro.This UVL stimulation of melanocytes in our skin organ cultures contrasts with the lack of melanogenic stimulation found in melanoma cell cultures. Our findings suggest that the intact epidermal melanin unit may be necessary for UVL stimulation of melanocytes.
Calcium redistribution in individual cells correlated with ionophore action on motility
Authors: Babcock Donner F. , Stamerjohn David M. , Hutchinson Thomas 
Published: June 2005

AbstractIntact bovine epididymal spermatozoa were rapidly frozen (but otherwise unfixed) and examined in the cryogenic stage of a scanning electron microscope equipped with an energy‐dispersive x‐ray analysis system. Distributions of calcium (also of P, S, K and Cl) were determined in 0.1 μm2 areas from the acrosome, nucleus, midpiece and flagella of cells that were subjected to a variety of conditions experimental that altered sperm total calcium content.Spectrophotometric measurements using the metallochromic indicator, murexide, showed that a net accumulation of calcium followed in vitro incubation of sperm in the presence of this cation. Accumulated calcium was distributed homogenously amongst the cell population, but was apparently concentrated in the mitochondria contained within the sperm midpiece as determined by electron microanalysis of individual cells. A net loss of previously accumulated calcium followed treatment of sperm with low levels of the divalent cation ionophore, A23187. Electron microanalysis indicated a corresponding depletion of mitochondrial calcium content. In contrast, subsequent treatment of sperm with high levels of A23187 resulted in net calcium uptake as determined by murexide absorbance changes. Electron microanalysis indicated that this reaccumulated calcium was distributed throughout the intracellular space. No significant changes in the intracellular concentrations or distributions of other elements were observed following ionophore treatment. These results support previous suggestions that the mechanism of motility activation mediated by A23187 involves an action of increased intracellular Ca2 + concentrations upon the contractile apparatus of the sperm flagella.
Further evidence in support of a role for hamster sperm hydrolytic enzymes in the acrosome reaction
Authors: Lui Chung W. , Meizel Stanley 
Published: June 2005

AbstractThe effects of trypsin inhibitors and phospholipase inhibitors on the acrosome reaction of washed cauda epididymal sperm of golden hamsters were studied using two different incubation systems. One incubation system, a non‐synchronous acrosome reaction inducing system, included the use of a highly purified BSA and a protein‐free motility factor preparation from hamster adrenal gland. The other system was a relatively synchronous acrosome reaction‐inducing‐system utilizing the calcium ionophore A23187. Acrosome reactions were inhibited by three low molecular weight synthetic trypsin inhibitors, benzamidine, NPGB and TLCK, when they were added five minutes prior to the initial occurrence of acrosome reactions in the non‐synchronous system or five minutes prior to induction of acrosome reactions by A23187 in the synchronous system. Two phospholipase A inhibitors, p‐bromophenacyl bromide and mepacrine, were also effective in inhibiting hamster sperm acrosome reactions in both incubation systems. TPCK, an inhibitor of several non‐trypsin‐like proteases, indomethacin, a prostaglandin synthetase inhibitor, and soybean trypsin inhibitor, a large molecular weight polypeptide, did not inhibit acrosome reactions. The inhibition of those acrosome reactions induced by A23187 provides further indirect evidence that the effective inhibitors were functioning at a site within the sperm. The overall results provide: (1) further support for our earlier work suggesting the involvement of an internal trypsinlike enzyme (presumably acrosin) rather than an exogenous trypsin‐like enzyme in the hamster sperm acrosome reaction and (2) the first evidence suggesting the possibility that a sperm phospholipase may also be involved in the mammalian acrosome reaction.
Polymorphism, genetic stability, and autosomal location of trimeric nucleoside phosphorylase in Peromyscus eremicus cell lines
Authors: Maxwell Beth Lynn , Siciliano Michael J. 
Published: June 2005

AbstractNucleoside phosphorylase (NP: EC 2.4.2.1) has not been demonstrated to be an extensively polymorphic enzyme locus in mammals. We have studied NP electrophoretically in five independently derived cell lines established from Peromyscus eremicus as well as in various tissues of a sixth animal. Four different NP phenotypes involving three different alleles were resolved. The data suggest that (1) the enzyme is trimeric and its genetic locus is polymorphic in P. eremicus, (2) heterozygous enzyme phenotypes are stable during long‐term culture, and (3) the enzyme locus is autosomal in Peromyscus.
Physical factors and neurosecretion in the control of reproduction in Melampus (Mollusca: Pulmonata)
Authors: Price Christopher H. 
Published: June 2005

AbstractMelampus bidentatus a saltmarsh snail living in the high littoral zone, lays eggs in phase with the moon, three to four times in early summer. Repetitive cycles of aggregation, egglaying, and dispersion were quantified in field studies. Physiological preparedness for breeding begins with an essential winter vernalization (<5°C). Breeding condition (growth of ovotestis, etc.) is induced in early spring only after both photoperiodic (>14 hours per 24 hours) and temperature (>15°C) thresholds are exceeded. Animals collected during winter could be induced to lay eggs if given spring‐like conditions; progressively shorter induction periods were effective as spring approached. Yearround histological studies of neurosecretory cells in the central ganglia of field animals showed staining patterns in two groups of neurons that were closely related to reproductive events. The medium cells (N =7) of the lateral lobe in each cerebral ganglion showed an accumulation of neurosecretory material (NSM) only in April, during the period when the natural photoperiod first exceeds 14 hours. These cells may mediate the light requirement and stimulate early reproductive events, such as ovotestis growth. The giant cells (N = 15) of the visceral ganglia stained heavily only during the reproductive season. They showed repetitive cycles of accumulation and subsequent depletion of NSM in phase with egg‐laying cycles. These neurons, signalled by some unknown but semilunar‐related cue, apparently synthesize and store NSM prior to each egglaying; release of this material may initiate the behavioral and physiological events of egg deposition.
Quantitative determination of titers of anti‐zona serum
Authors: Tsunoda Y. , Sugie T. , Mori J. 
Published: June 2005

AbstractThe titers of rabbit antiserum against isolated mouse zonae pellucidae were examined by several methods in connection with inhibitory effect on fertilization.The titers determined by zona precipitate, zona dissolution, indirect immunofluorescence and in vitro fertilization tests were 24, 21 to 24, 27 and 24, respectively. Cytotoxic effect could not be detected from zona antibody. The indirect immunofluorescence was most sensitive for detection of zona antibody but did not represent the extent of inhibitory effect on fertilization. The titer obtained by zona precipitate test was most close to the titer obtained by inhibitory effect on in vitro fertilization.The present study also demonstrated that at least 0.0375 ml of antiserum per female mouse, equivalent to 0.15–0.25% of body weight, was necessary for inhibition of fertilization in vivo by passive immunization with anti‐zona serum.
Evidence for the continuation of meiosis and spermiogenesis in in vitro cultures of spermatogenic cells from Xenopus laevis
Authors: Risley Michael S. , Eckhardt Ronald A. 
Published: June 2005

AbstractSpermatogenic cells were obtained from Xenopus laevis testes by collagenase dissociation and subsequently separated into two fractions by density gradient centrifugation in Metrizamide and by unit gravity sedimentation in bovine serum albumin gradients. One fraction was highly enriched for primary spermatocytes while the other fraction was highly enriched for early‐mid stage spermatids. The cells from each fraction were cultured separately in modified DNOM medium for 23 days to determine the extent to which differentiation could be maintained in vitro. Differential cell counts revealed that early‐mid stage spermatids continues to differentiate in vitro through the stages of cytoplasmic shedding. Spermatocytes passed through both meiotic divisions throughout the 23 day period and produced spermatids which also differentiated through the cytoplasmic shedding stages. The results demonstrated that significant differentiative potential is retained by Xenopus spermatogenic cells cultured in vitro even after dissociation and cell separation procedurs.