bluuebunny/crossref_metadata_2025_split huggingface dataset:
The mechanism of blood flow redistribution within the carotid labyrinth of the toad, Bufo marinus
Authors: Smith D. G. , Rogers D. C. , Chamley‐Campbell J. , Campbell G. R. 
Published: June 2005

AbstractThe mechanism of flow redistribution in the carotid labyrinth of the toad, Bufo marinus, was investigated by exposing saline‐perfused labyrinths and cultured explants of cells from the pars capillaris or p. cavernosa to various vasoactive compounds. In addition, the presence of smooth muscle myosin and tropomyosin was demonstrated by immunofluorescence histochemistry. Explants from the p. capillaris were found to be unresponsive to all agonists tested, whereas those from the p. cavernosa were contracted by each of angiotensin, adrenaline, and acetylcholine. The same agonists always reduced the proportion of total perfusion leaving the labyrinth via the external carotid artery while simultaneously raising the overall resistance to flow through the organ. It is concluded that flow through the external carotid artery is controlled by smooth muscle cells encircling it at its base or by others surrounding the radicles to the ring vessel: Flow through the p. capillaris to the internal carotid is not controlled by β‐cells or their processes. Internal carotid flow may be controlled actively by constriction of the internal carotid itself, or passively as a consequence of altered pressure gradients within the labyrinth during constriction of the external carotid artery.
Cephalic flexure formation in the chick embryo
Authors: Goodrum Gail R. , Jacobson Antone G. 
Published: June 2005

AbstractThe cephalic flexure, found in all vertebrate brains, is a ventrally directed bend through the mesencephalon, and a ventral bulging and elongation of the prosencephalon. Most sources say the cephalic flexure is caused by differential growth. We have measured the changing angle of flexure through time and find that flexure occurs between chick embryo stages 10 to 15. We measured, during these stages, the lengths, thicknesses, and volumes of the floor and roof of the mesencephalon and of the prosencephalon. As expected, during flexure the mesencephalic roof elongates much more than the floor. Both roof and floor increase in thickness, and mesencephalic roof volume increases twice as much as floor volume. However, prosencephalon, which does not bend, also has differential growth between roof and floor, but the growth is taken up in complex changes of shape other than flexure. There are sufficient numbers of mitoses in the brain to account for the observed tissue growth, assuming accompanying cell enlargement. We deleted brain parts adjacent to the mesencephalon before flexure and the mesencephalon bent, so migration of cells from or to these adjacent parts to contribute to the differential growth of the mesencephalon is unlikely. We reduced cerebrospinal fluid pressure during flexure by explanting heads to the chorioallantoic membrane, or into New cultures. The mesencephalon of explanted heads bends, but the prosencephalon fails to elongate. We conclude that differential growth may be necessary for mesencephalic flexure in the chick embryo, but other factors that decide the disposition of the products of growth in space must determine the shape.
Accumulation of DNA, RNA, and protein by cultured rat embryos following maternal administration of a teratogenic dose of trypan blue
Authors: Fisher D. L. 
Published: June 2005

AbstractThe effect of trypan blue on the rates of DNA, RNA, and protein accumulation in rat embryos was investigated using a system of whole embryo culture. Embryos were isolated on the 10th gestational day (sperm day = Day 0) either 4 or 24 hr after maternal injection. The cultivation period was for 24 or 42 hr. The rate of DNA and RNA accumulation in the embryo following either a 4‐ or 24‐hr previous maternal treatment was significantly decreased at both 24 and 42 hr of cultivation. Protein values were significantly reduced after a 4‐hr maternal exposure, but only slightly reduced after a 24‐hr maternal exposure. No significant differences in DNA, RNA, or protein content were observed at the beginning of cultivation, following either a 4‐ or 24‐hr previous maternal treatment. The percentage of embryos establishing a visceral yolk sac circulation was greatly reduced, and this supports the conclusion that trypan blue interferes with yolk sac function. The most obvious teratogenic insults include failure of neuropore closure, retention of a dorsiflexed position, and cranial edema.
Detection of modifications in the tail of capacitated guinea pig sperm using lectins
Authors: Talbot P. , Chacon R. 
Published: June 2005

AbstractThe surfaces of uncapacitated, capacitated, and trypsinized guinea pig sperm have been compared using 10 lectins. A previously described assay was used to assess the degree and pattern of agglutination induced by each lectin. Our method of evaluating the agglutination pattern was significantly improved by observing assay plates with an inverted phase contrast microscope at 200 or 320 × magnification rather than with a dissecting microscope. Following in vitro capacitation or trypsinization, the agglutinability of sperm by SBA, DBA, and WGA increased, and the agglutination pattern induced by SBA, DBA, WGA, and RCA120 changed to a predominantly reticular form. These changes did not occur when sperm were incubated in Ham's F‐10, a control medium which does not support capacitation. Since binding of these lectins is inhibited by N‐acetyl‐D‐galactosamine (SBA, DBA), D‐galactose (SBA, RCA120, DBA), or N‐acetyl‐D‐glucosamine (WGA), we conclude that surface receptors containing these residues are affected by capacitation. By examining assay plates with an inverted phase contrast microscope, we were able to show that the change in the agglutination pattern for all four lectins was due to an increase in agglutinability of the principal piece of the flagellum. It is suggested that the modification of the principal piece detected by this lectin assay may be important in the development of activated motility. Results further show that capacitation and trypsin treatment affect the sperm surface in a similar manner, and are thus consistent with the idea that a trypsin‐like enzyme may modify the sperm during capacitation.
Inhibition of mouse blastocyst attachment and outgrowth by protease inhibitors
Authors: Kubo Harumi , Spindle Akiko , Pedersen Roger A. 
Published: June 2005

AbstractEffects of protease inhibitors on development of mouse blastocysts and fibrinolytic activity of trophoblast were examined by growing embryos on monolayers of decidual cells in the presence of inhibitors. Nitrophenol‐p‐guanidino benzoate (NPGB) was the most effective inhibitor; 10−4 M NPGB inhibited attachment and trophoblast outgrowth by 24% and 66%, respectively, and inhibited the fibrinolytic activity of trophoblast by 86%. The effects of NPGB were reversible, as demonstrated by the embryos' ability to attach and resume normal development when transferred to NPGB‐free medium. Soybean trypsin inhibitor and ϵ‐aminocaproic acid were less effective than NPGB in inhibiting blastocyst development. When 10−4 M NPGB and 350 μg/ml of soybean trypsin inhibitor were added together, blastocyst development and fibrinolytic activity were inhibited more severely than when either inhibitor was added alone. We suggest that at least two types of proteolytic activities in mouse blastocysts are involved in implantation, attachment requiring trypsin‐like activity, and trophoblast outgrowth requiring both plasminogen activator and trypsin‐like activity.
Lens of the hydromedusan Cladonema studied by SDS gel electrophoresis and immunofluorescent technique
Authors: Weber Christian 
Published: June 2005

AbstractThe lens of the medusa Cladonema radiatum contains protein components. Three different protein fractions were found in SDS‐polyacrylamide gels. Each sample used for electrophoresis contained extracts of 60 ocelli of Cladonema. Direct comparisons show correspondence between the electrophoretic mobilities of the three fractions and bands of amphibian and bovine lens proteins and antigen‐antibody reaction of bovine lens antibodies to Cladonema lens crystallins.
Epidermal cell migration during attempted closure of skin wounds in the adult newt: Observations based on cytochalasin treatment and scanning electron microscopy
Authors: Donaldson Donald J. , Dunlap Mary K. 
Published: June 2005

AbstractEpidermal closure of skin wounds on newt limb explants was inhibited to equal degrees by cytochalasins B,D and dihydiocytochalasin B (H2CB). The cytochalasin solvent, dimethylsulfoxide (DMSO), had no effect on migration at the low concentration present in the cytochalasin and control solutions. However, a 5% DMSO solution completely blocked mobility. Wounds on limb explants and limbs in situ responded similarly to cytochalasin treatment. Inhibition of migration by H2CB was reversible even when protein synthesis was reduced by 73%. Scanning electron microscopy of wound epithelium migrating on nucleopore filters revealed extensive lamellipodia on marginal cells and the first row of submarginal cells. Cytochalasin treatment produced plications in the upper surface and free edge of the normally smooth lamellipodia. This disturbance of the free edge revealed focal adhesions with the substratum. The fact that migration was inhibited by CD and H2CB (two cytochalasins with an affinity for contractile proteins but without some of the side effects of CB) leads us to conclude that epidermal cells utilize actin or actin‐like proteins during wound closure. These results increase the likelihood that tissue cells of all types, whether in vitro or in vivo, share a common biochemical basis for cell movement.
Shunts in the gill filament in tadpoles of Rana temporaria and Bufo bufo (amphibia, anura)
Authors: De Saint‐Aubain Marie Louise 
Published: June 2005

AbstractVascular shunts in the gill filament have been discovered in larvae of Rana temporaria and Bufo bufo by means of Indian ink and latex injections. These shunts offer a nonrespiratory flow path to the dorsal aorta. They are morphologically different from the shunts seen in urodeles. Contractility of the shunts is indicated and influence on gill blood flow proposed.
1‐Methyladenine induced stimulation of protein phosphorylation and Na+ pump does not require the presence of the nucleus
Authors: Doree M. 
Published: June 2005

Abstract1‐Methyladenine, which induces meiosis reinitiation in starfish oocytes, stimulates 32P incorporation into proteins and activates the ouabain‐sensitive Rb+ influx in anucleated fragments obtained from full‐grown Marthasterias glacialis oocytes. This shows that hormone‐induced stimulation of protein phosphorylation and Na+ pump does not require the presence of the nucleus. Stimulation of protein phosphorylation is, however, delayed and reduced with respect to intact oocytes.
The role of oxygen and light in guiding “photoaccumulation” in the Paramecium bursaria‐Chlorella symbiosis
Authors: Cronkite Donald , van den Brink Sue 
Published: June 2005

AbstractGroups of Paramecium bursaria, containing the symbiotic alga Chlorella, aggregate in a “light trap” – a spot of light in a dark field. Cell populations conform to the shape of the light trap because (1) individual cells in the light either move slowly or not at all; and (2) individuals also, upon leaving the spot of light, undergo a short avoiding reaction – a step‐down response – changing the direction of their forward movement back toward the light. Upon removing the light source, cells become more motile and disperse from the area of the light trap. A similar result is produced in the light by the addition of 10−6 molar 3‐(3,4‐dichloropheny1)‐1,1‐dimethyl urea, (DCMU), which completely inhibits the photosynthetic evolution of O2 by Chlorella‐bearing P. bursaria. However, in the presence of DCMU the step‐down response is not affected. We conclude that P. bursaria accumulates in light through two mechanisms: an “aeroreceptor” senses changes in concentrations of O2 and a “photoreceptor” senses decrease in light intensity. Additionally, methods of quantifying photobehavior have been developed and have been used to show that blue light is a more effective inducer of step‐down photobehavior than is red light. Further studies are underway to examine the roles of ions and of the symbiont in mediating the response of P. bursaria to light.
Improved visualization of apical vesicles in chloride cells of fish gills using an osmium quick‐fix technique
Authors: Bradley Timothy J. 
Published: June 2005

AbstractQuick‐fixation with buffered osmium is a well established technique for fixing rapid forms of cell motility, e.g., metachronal ciliary beat. One proposed mechanism of salt transport in the gills of saltwater fish is a vesicular shuttle in the apical tubulovesicular system of gill chloride cells. We decided to use the osmium quick‐fix technique to see if rapid fixation causes modification of observed gill ultrastructure. Gill chloride cells from two species of fish, Fundulus heteroclitus and Poecilia reticulata, were examined ultrastructurally under two conditions of fixation: (1) Conventional fixation in glutaraldehyde followed by osmium or (2) quick‐fixation for 20 seconds in osmium tetroxide buffered with Na cacodylate followed by conventional fixation. Following osmium quick‐fixation, the ultrastructure of the apical tubulovesicular system is substantially different, such that more vesicles are seen in the cortical region and membrane fusion events between vesicles and the apical membrane are much more prevalent. The appearance of other portions of the chloride cell, e.g., mitochondria, tubular reticulum, cell junctions, was identical under the two conditions of fixation. These results suggest that a rapid vesicular shuttle is present in the chloride cell apex. A model indicating how such a shuttle might be instrumental in transepithelial ion transport is presented and evaluated. We currently lack sufficient information to accept or reject any of the current models of ion transport. It is anticipated that the osmium quick‐fix technique will serve as a useful tool in further studies of the morphology, movements, and function of apical vesicles in fish chloride cells.
Induction of budding in a nonbudding mutant of Hydra viridis as a result of grafts using wild type tissue with varying compositions of interstitial and nerve cells
Authors: Novak Patricia L. , Lenhoff Howard M. 
Published: June 2005

AbstractIn order to determine if the interstitial cell or its derivative nerve cells play a role in inducing buds, experiments were conducted in which grafts using wild type tissue of varying cell compositions were made with the nonbudding mutant. Wild type specimens of H. viridis lacking i‐cells but possessing nerve cells as well as lacking both i‐cells and nerve cells were prepared using various combinations of hydroxyurea and colchicine. Wild type tissue lacking i‐cells but possessing nerve cells stimulated the mutant tissue to bud. Wild type tissue without i‐cells and nerve cells, however, was unable to induce budding. Chimeric hydra consisting of epithelial cells from wild type hydra and i‐cell lineages from the mutant reproduced asexually by budding as do wild type epithelial animals repopulated with wild type i‐cells. Chimeric hydra, however, were unable to induce budding when grafted back to the mutant. From the results of these experiments dealing with properties and induction of budding, we propose that nerve cells can influence adjacent epithelial tissues to form buds.
Development of swimming behavior in sea urchin embryos. II
Authors: Maruyama Y. K. 
Published: June 2005

AbstractThe previous study has revealed that sea urchin prehatching embryos exhibited either clockwise or counterclockwise spin on the animal—vegetal axis, whereas the hatched embryos showed only counterclockwise spin. This behavioral change at hatching was analyzed in the present study by testing the “mechanical interaction hypothesis” proposed in the previous paper. Observations of the spinning behavior have been made of (1) embryos without the fertilization membrane (denudation experiment), (2) those embedded in fibrin gel at the prehatching or free‐swimming stages (maintenance or induction experiments), and (3) those liberated into seawater after the embedding (liberation experiment). The results have provided evidence to support the hypothesis that the duality of the spinning behavior in the prehatching embryos is due to a mechanical or hydrodynamic interaction between the cilia and the inner surface of the fertilization membrane, independent of the developmental stage of the embryo proper. Thus it is concluded that the change in the spinning behavior of embryos after hatching is brought about solely by their release from the fertilization membrane.
Fine structure of the micropylar apparatus of the chum salmon egg, with a discussion of the mechanism for blocking polyspermy
Authors: Kobayashi Wataru , Yamamoto Tadashi S. 
Published: June 2005

AbstractThe micropylar apparatus of the eggs of the chum salmon, Oncorhynchus keta, was examined by scanning and transmission electron microscopy. The apparatus consists of a funnel‐shaped vestibule, from the bottom of which extends the micropylar canal, about 5 μm, in diameter. The canal traverses the entire zona pellucida interna of the egg envelope, about 30 μm in thickness. At its inner end, the diameter of the micropylar canal is the same as the width of the sperm head, about 2 μm. The lower portion of the canal is occupied by a conspicuous outgrowth of the ooplasmic surface, 3–10 μm in length.The first contact of the ooplasmic surface with a fertilizing spermatozoon occurs at the apex of the outgrowth in the micropylar canal. The surface of the outgrowth undergoes changes immediately after penetration by a fertilizing spermatozoon that prevent supernumerary spermatozoa from penetrating the ooplasm. As the formation of the perivitelline space takes place, the outgrowth withdraws from the micropylar canal. Supernumerary spermatozoa, however, cannot enter the perivitelline space and are eliminated from the canal lumen. In addition, the micropylar canal decreases in diameter at the region near its inner end and forms a mechanical barrier to the passage of supernumerary spermatozoa.
Only acrosome‐reacted spermatozoa can bind to and penetrate zona pellucida: A study using the guinea pig
Authors: Huang T. T. F. , Fleming A. D. , Yanagimachi R. 
Published: June 2005

AbstractWe have examined the behavior of guinea pig spermatozoa towards the guinea pig zona pellucida in vitro. Experiments were designed to determine whether the state of capacitation or the acrosome reaction determined the ability of the spermatozoa to attach to the zona. Freshly collected cauda epididymal spermatozoa are acrosome‐intact (AI) and, by definition, uncapacitated. These cells could not attach (at least persistently) to the zona. We then sampled spermatozoa from a progressively capacitating population at various time intervals. At no point did AI spermatozoa from such samples have the ability to attach to the zona. On the other hand, acrosome‐reacted (AR) spermatozoa that appeared in increasing number during this capacitation period rapidly and firmly adhered to the zona. Adhesion by AR spermatozoa prepared in several ways culminated in successful zona penetration and fertilization of the ovum. The data provide unequivocal evidence that AR guinea pig spermatozoa attach to zonae and fertilize the ova. We find no evidence that AI spermatozoa firmly attach or bind to the zona, regardless of their state of capacitation.
Formation of the block to polyspermy in ascidian eggs: Time course, ion requirements, and role of the accessory cells
Authors: Lambert Charles C. , Lambert Gretchen 
Published: June 2005

AbstractThe eggs of Ascidia nigra become incapable of fertilization by a second sperm about 21 seconds after fertilization by the initial sperm. Removal of the follicle cells slows the rate and lowers the percentage of fertilization but has no influence on the block to polyspermy. Similar numbers of sperm are found in the perivitelline spaces of polyspermic and monospermic eggs subjected to high sperm concentrations, suggesting that the block to polyspermy is at the egg surface. Like other polyspermy blocks in marine invertebrates, that of ascidians requires Na+ for formation.
Electrophoretic protein patterns in fast and slow muscles of the lobster, Homarus americanus
Authors: Meiss Dennis E. , Lyerla Timothy A. , Cain Scott , Costello Walter J. 
Published: June 2005

AbstractThe protein arrays of the claw and abdominal muscles of the lobster Homarus americanus were examined by sodium dodecyl sulfatepolyacrylamide gel electrophoresis. The gel protein patterns revealed consistent differences in several major bands that could be correlated with the physiological properties of the muscle. Fast‐type muscle, independent of innervation, showed a common protein pattern distinct from the slow muscles, which had a common pattern of their own. These results suggest that functional properties of crustacean muscle fibers are expressed in their protein composition.
Transport‐related ATPases as probes of tissue function in three terrestrial crabs of Palau
Authors: Towle David W. 
Published: June 2005

AbstractDistribution and properties of Na+ + K+‐dependent ATPase and Cl−/HCO‐activated ATPase were used as probes of tissue function in relation to salt and water regulation in three terrestrial crabs, Cardisoma carnifex, Gecarcoidea lalandii, and Birgus latro. Of the three predominant tissues in the branchial chamber, gill consistently exhibited highest specific activity of both enzymes, indicating that terrestrial crabs may use ion regulation by the gills as an important mechanism of salt and water balance. Branchial epithelium lining the cavity does not appear to be important in regulation of monovalent ions, although it is highly specialized in B. latro as a respiratory organ. Pericardial sac also lacks the biochemical machinery for active salt and water uptake. Antennal gland of all three species showed high activity of Na+ + K+‐ATPase, perhaps facilitating water retention by that organ. Na+ + K+‐ATPase activity of intestine showed wide species‐related variation, and was enhanced in B. latro exposed to freshwater. The gill of B. latro maintained constant high activity of the Na+ + K+‐ATPase, irrespective of environmental conditions.