bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid modulation of gill Na+ + K+‐dependent ATPase activity during acclimation of the killifish Fundulus heteroclitus to salinity change
Authors: Towle David W. , Gilman Mary E. , Hempel John D. 
Published: June 2005

AbstractThe enzymatic properties of membrane‐bound Na+ + K+‐ATPase from gills of killifish acclimated to fresh water, to 16‰ sea water, or to 30‰ sea water appear to be identical, indicating that the same enzyme may function to absorb Na+ in low salinities and excrete Na+ at the gills in high salinities. Ammonium ion is an effective substitute for K+: in the ATPase reaction itself, in blocking phosphorylation of the ATPase protein, and in inhibiting the binding of ouabain to the enzyme. The specific activities of the Na+ + K+‐ATPase in the three different salinities are consistent with the expected Na+ pumping rates: higher in fresh water and 30‰ sea water than in 16‰ sea water. Within one‐half hour after transfer of killifish from one salinity to another, gill Na+ + K+‐ATPase activities reach equilibrium levels. The rapid increase in Na+ + K+‐ATPase activity in gill microsomes of fish acclimating from fresh water to 30‰ sea water is accompanied by a slow decrease in the number of binding sites for ouabain, supporting the idea that acclimation to short‐term salinity changes may involve modifications in the catalytic rate rather than the number of Na+ + K+‐ATPase molecules.
Fluorescence identification of zoochlorellae: A rapid method for investigating alga‐invertebrate symbioses
Authors: Williamson Craig E. 
Published: June 2005

AbstractUsing fluorescence microscopy I have developed a technique for the rapid identification and enumeration of zoochlorellae which does not require sectioning. Chlorophyll in algal symbionts fluoresces bright red when excited by ultra‐violet light. In a test of this system using green and white Spongilla lacustris I found a ratio of 42:1 (green:white) in the number of symbionts and a similar ratio of 36:1 in the amount of chlorophyll a and b present.
Chemotactic behavior of the sperm of chitons (Mollusca: Polyplacophora)
Authors: Miller Richard L. 
Published: June 2005

AbstractObservations of sperm behavior in the vicinity of gradients of egg‐water or alcohol extracts of whole freshly‐spawned eggs of several chitons reveal what appear to be directed movements of sperm up the gradient, resulting in the aggregation of motile sperm at the gradient source. Plots of the tracks of the sperm approaching the gradient source show that the cells increase the time during which they move toward the source and decrease the time spent moving away. Although this resembles the kinesis behavior shown by bacteria in a gradient, the path directions are markedly non‐random. The reorientation behavior of thigmotactic sperm involves enlargement of the normal circular path diameter in the direction of the source and an alternation of tight loops and wide circular arcs, with the latter made in the direction of the source. The form of the path of attracted chiton sperm is like that observed during chemotaxis of the sperm of the hydroid Tubularia and the tunicate Ciona and resembles the behavior of Ciona sperm in that there is no increase in velocity as the cells move up the gradient. However, unlike the cnidarian and urochordate cases, the attracting substances extracted from chiton eggs do not act species‐specifically.
The effect of nerve growth factor and limb regeneration on the spinal and sympathetic ganglia of Triturus
Authors: Grillo R. S. , Detmar C. F. , Mitchell O. G. 
Published: June 2005

AbstractIn Triturus administration of NGF causes hypertrophy of neuronal perikarya of third dorsal root ganglia and post‐subclavian sympathetic ganglia.Two classes of neurons were characterized cytologically in the third dorsal root ganglia. Some evidence is presented which indicates that Class I neurons respond more vigorously to NGF. It is suggested that Class I neurons are similar to the medio‐dorsal neuroblasts of chick embryos in their response to NGF.Forelimb amputation did not cause neuronal hypertrophy in either third dorsal root ganglia or post‐subclavian sympathetic ganglia.The incorporation of (3H)‐uridine increases to a highly significant extent in third dorsal root ganglia following NGF treatment or limb amputation. When NGF treatment and limb amputation were combined, no further increase in (3H)‐uridine incorporation was noted. This suggests that RNA synthesis is maximally stimulated by either NGF treatment alone or limb amputation alone.
Persistence of circadian activity rhythms in pinealectomized European Starlings (Sturnus vulgaris)
Authors: Rutledge James T. , Angle Marlane J. 
Published: June 2005

AbstractSurgical removal of pineal glands from adult male European Starlings (Sturnus vulgaris) does not alter circadian perch‐hopping activity rhythms characteristic of this species maintained in constant darkness. The average free‐running period of the activity rhythms of ten pinealectomized birds was 24.61 hours, compared to the previously reported period of 24.48 hours for intact starlings under identical conditions. These results conflict with those reported for three other passerine species in which pinealectomy abolishes circadian activity patterns. In addition, the data do not support the recently proposed model of Menaker and Zimmerman that suggests that the pineal gland is the site of the self‐sustained oscillator in the circadian timing system of birds.
Surface modification of guinea pig sperm during in vitro capacitation: An assessment using lectin‐induced agglutination of living sperm
Authors: Talbot Prudence , Franklin L. E. 
Published: June 2005

AbstractPlant lectins have been used to advantage to study carbohydrate‐containing cell surface receptors in numerous systems. In this study, a simple, reliable assay was developed to quantitate lectin‐induced agglutinability of sperm. This assay was used successfully to compare some of the surface properties of uncapacitated and capacitated guinea pig sperm. Capacitation was induced by incubating sperm in minimum capaciting sperm in minimum capacitation medium (MCM) or modified Tyrodes solution (T‐PL). Control incubations were done in Ham's F‐10 or Hank's balanced salt solution which do not support capacitation. At timed intervals during incubation, sperm samples were assessed for pattern and degree of lectin‐induced agglutination. Results establish that: (1) soybean agglutinin (SBA) and to a lesser extent concanavalin A (Con A) induced agglutinability of guinea pig sperm increase during in vitro capacitation in MCM; (2) a similar increase in SBA induced agglutinability occurs during capacitation in T‐PL, but not in the non‐capacitating media; and (3) for sperm incubated in MCM or T‐PL, there is a significant increase in tail to tail agglutination after capacitation. The results with SBA demonstrate that D‐galactose and/or N‐acetyl‐D‐galactosamine containing receptor sites or the guinea pig sperm surface are affected by capacitation, and this effect occurs, at least in part, in the sperm tail. Possible explanations for the observed increase in agglutinability are discussed. The agglutination assay may prove useful as a direct test for the occurrence of capacitation and may be especially valuable for species having a small acrosome or limited number of eggs.
Z‐line and supercontraction in the hydraulic muscular systems of insect larvae
Authors: Carnevali M. Daniela Candia 
Published: June 2005

AbstractAn electron microscopic study has been made on the body wall muscles from Lepidoptera (Noctua pronuba, Philosamia cynthia) and Diptera larvae (Tipula tipula), whose locomotion is based on a hydraulic muscle antagonism.All the fibers examined had interrupted Z‐bands, formed of single dense bodies, irregularly placed around the sarcomere; myosin filaments could pass through the spaces between one Z‐body and the next, making it possible for the sarcomere to shorten its resting length by up to 60%. In supercontracted muscles, both the thick and the thin filaments pass through the Z‐line; since these actin filaments are very long, they can overlap and interact with the myosin filaments of the adjacent sarcomeres.The muscles examined can be placed in the category of supercontracting muscles and can be considered a type of striated muscle, with morphological and functional characteristics similar to those of helical or smooth muscle.
Cell proliferation in the intestinal epithelium of Xenopus laevis tadpoles
Authors: Marshall J. A. , Dixon K. E. 
Published: June 2005

AbstractLight microscope, electron microscope and autoradiographic techniques were used to determine whether, in the small intestinal epithelium of feeding tadpoles of Xenopus laevis, proliferation is limited to particular cells or to particular regions. Mitotic figures were classified as apical, medial or basal according to their position relative to the gut lumen. Apically dividing cells represent 75% of all mitoses and were identified on histological and ultrastructural criteria as specialized principal cells or rarely, as specialized gland cells. This interpretation was confirmed by autoradiographic evidence that specialized principal and gland cells incorporate (3H) thymidine into DNA. Basally dividing cells represent 25% of all mitoses and medial mitotic figures are very rare. Histological and ultrastructural evidence indicated that basal and medial mitotic figures are due to the division of intra‐epithelial lymphocytes and it was demonstrated that lymphocytes incorporate (3H) thymidine into DNA. Growth and replacement in the epithelium are therefore due to the mitotic activity of specialized cells. The results also suggest that all specialized cells can divide and that proliferation is not localized in particular regions of the epithelium as it is in other vertebrates. The significance of these conclusions for the interpretation of nuclear transplantation experiments using donor nuclei from intestinal epithelial cells is briefly discussed.
Development of the compound eyes of dragonflies (odonata). III. Adult compound eyes
Authors: Sherk Truman E. 
Published: June 2005

AbstractThe distribution of ommatidial diameters and interommatidial angles, as determined by measuring the angles between the optic axes of adjacent ommatidia, are mapped across the surface of the compound eyes of a variety of species selected for different adult behaviors, developmental histories, and taxonomic positions. The size of the visual fields, prey capture foveas, foveas composed of large dorsal ommatidia, and other specializations in the numbers of ommatidia that view various directions in the visual field are discussed in relation to adult behavior.Advanced species have less resemblence between their larval and adult eyes than primitive species. In contrast to their larvae, adults increase the monocular resolution of each eye at the expense of binocular vision. Most species have foveas which view in approximately the anterior direction, instead of in a region of binocular overlap, and many species have foveal bands which view along the horizon. Some advanced perching species, which approach their prey and other odonates from below, have an additional vertical foveal band that views along a vertical plane from the anterior direction to a more dorsal direction. The most unusual foveal band is seen in active flying species. The large dorsal ommatidia of the migratory Anax junius, which cover approximately one third of the eye surface, view a narrow region of the visual field that extends along a plane from the most lateral direction of one eye to a dorsal direction, and continues without interruption to the most lateral direction of the other eye.
Identification of eight‐cell tw32 homozygous lethal mutants by aberrant compaction
Authors: Granholm Nels H. , Johnson Phyllis M. 
Published: June 2005

AbstractEarly cleavage stage (4‐ and uncompacted 8‐cell) embryos from experimental (+/tw32 × +/t32) and control (♂ +/tw32 × ♀ +/T) matings were recovered at 56 hours post coitum, cultured, separated into uncompacted and compacted 8‐cell embryo groups, and either analyzed histologically for cytoplasmic lipids or cultured through the morula‐to‐blastocyst transformation. Abnormal compaction was associated with excess cytoplasmic lipids at the 8‐cell stage (P < 0.01). Also, 89.2% (33/37) of the original uncompacted experimental embryos underwent developmental arrest characteristic of tw32 homozygous lethals. Thus, aberrant compaction, a newly reported symptom of the tw32/tw32 syndrome, affords a visual means to identify tw32 homozygotes at 8‐cell stages.
In vitro inhibition of mouse dental development by tetracycline
Authors: Kerley Michael A. , Kollar Edward J. 
Published: June 2005

AbstractEmbryonic molars and incisors were dissected from mandibles of 15‐day post‐fertilization C57BL/10 mouse embryos and were cultured in vitro for six days on agar‐solidified Eagle's basal medium. Experimental explants were cultured on medium which was the same as the control except that 50, 75 or 100 μg/ml tetracycline was added. Treated explants of both incisors and molars were suppressed in development and reduced in size. Enamel organs and dental papillae of all tooth germs subjected to higher tetracycline concentrations were abnormal in structure and differentiation of ameloblasts and odontoblasts was inhibited. Explants treated with higher dosage levels of the drug were more severely affected than those exposed to lower concentrations. Recovery from the suppression induced by tetracycline was observed in explants transferred to control medium for four days of growth following treatment. Differentiated ameloblasts and odontoblasts observed in the recovering tooth germs indicated that the inhibition in development was temporary. The results of this study showed that tetracycline can alter dental development in vitro prior to mineralization. The observed inhibition may be related to a disruption of collagen biosynthesis which is thought to play a role in the controlling epithelial‐mesenchymal interaction involved in tooth germ morphogenesis.
Uptake OF Ca2+ is one of the earliest responses to fertilization of sea urchin eggs
Authors: Paul Miles , Johnston Randal N. 
Published: June 2005

AbstractSea urchin eggs take up Ca for 10 min following insemination (determined as uptake of 45Ca from the SW (3)). Although 90% of this uptake occurs after the beginning of the cortical reaction and may represent external binding of Ca to the egg surface coats, there is a brief phase of uptake (0–30 sec) which precedes the cortical reaction; this may represent a Ca flux into the eggs.
The excretion of NH4+ and its ouabain sensitivity in aquatic annelids and molluscs
Authors: Mangum C. P. , Dykens J. A. , Henry R. P. , Polites G. 
Published: June 2005

AbstractAmmonia is excreted against a molecular gradient in several species of annelids and molluscs. Ammonia excretion is also inhibited by exposure to ouabain in concentrations that do not affect circulation or ventilation. These results indicate that ammonia crosses the excretory epithelium in the ionized form, and that the process is linked to the activity of the Na+ + K+ ATPases.
Penetration of the zona‐free or intact eggs by foreign spermatozoa and the fertilization of deer mouse eggs in vitro
Authors: Hanada A. , Chang M. C. 
Published: June 2005

AbstractZona‐free eggs were introduced to fresh or preincubated sperm suspensions and the penetration of eggs by foreign spermatozoa was examined, as evidenced by enlargement of the sperm head and formation of the male pronucleus. It was found that zona‐free hamster eggs can be penetrated by guinea‐pig, deer mouse and rabbit spermatozoa but zona‐free rat, mouse and rabbit eggs cannot be penetrated by guinea‐pig spermatozoa. Furthermore, zona‐free rat and mouse eggs cannot be penetrated by spermatozoa from two species of deer mice and the Mongolian gerbil. The zona pellucida of a few intact rat eggs can be penetrated by mouse (6%) and by P. leucopus spermatozoa (14%) but enlargement of the sperm head and formation of pronuclei were observed in the former but not in the latter. It seems that (1) sperm capacitation is required for the penetration of zona‐free eggs, (2) the attachment of foreign spermatozoa to eggs may indicate their potential ability of penetration in some cases, (3) there is a certain affinity between the vitellus of one species and spermatozoa from another species, (4) the block to the entry of foreign spermatozoa is not only in the zona pellucida but also in the vitelline membrane, (5) zona‐free hamster eggs can be penetrated by spermatozoa of six species, (6) mouse spermatozoa can penetrate zona‐free eggs of three species, and (7) fertilization of intact P. maniculatus eggs can be achieved in vitro.
Rabbit acrosin: Immunological dissimilarity to rabbit trypsin
Authors: Dudkiewicz Alan B. , Lehnhardt William F. , Johnson David A. , Travis James , Williams William L. 
Published: June 2005

AbstractAntibodies obtained from guinea pigs injected with rabbit pancreatic trypsin together with antibodies raised in rabbits against bovine acrosin or bovine pancreatic trypsin were reacted against various mammalian trypsins and acrosins in double diffusion tests. The results of immunodiffusion analyses reveal antigenic dissimilarity between rabbit acrosin and rabbit trypsin.
Serum protein depletion by cultured rat embryos
Authors: Klein Norman W. , Minghetti Phillip P. , Jackson Susan K. , Vogler Mary A. 
Published: June 2005

AbstractCultures of 10‐day rat embryos depleted a protein band with a molecular weight of approximately 125,000 from the rat serum medium. Delayed centrifuged serum differed from immediately centrifuged serum by a reduction in the staining intensity of the 125,000 molecular weight protein band and by the absence of two high molecular weight (>200,000) protein bands.
High levels of inosine monophosphate in the erythrocytes of elasmobranchs
Authors: Coates Michael , Paton Barbara C. , Thompson Judith 
Published: June 2005

AbstractThe acid soluble organic phosphates of the erythrocytes of three species of elasmobranchs were assayed by chromatography on Dowex 1 anion exchange columns. Organic phosphates in the peaks eluted from these columns were identified by their ultraviolet absorption spectra and by further chromatography on paper. All three species are unusual amongst the vertebrates in that their erythrocytes contain high levels of inosine monophosphate (IMP). IMP has little effect on the oxygen affinity of the hemoglobins of the two species tested.
Radioautographic and biochemical studies of secretion of venom protein in the South American rattlesnake Crotalus durissus terrificus
Authors: Marchi F. , Haddad A. , De Lucca F. L. 
Published: June 2005

AbstractProtein secretion was investigated in the main venom gland of the South American rattlesnake, using radioautographic and biochemical techniques after a single intracardiac injection of L‐(3,5‐3H)tyrosine. All the snakes were injected at the fourth day of the secretory cycle and killed at 1/2, 1, 2, 4, 8 and 24 hours after injection. Most of the radioactive amino acid is cleared from the blood stream up to four hours after injection. On the other hand the specific activity (c.p.m./mg of protein) of the intracellular proteins reaches a peak at the 4‐hour time interval decreasing aftewards. There was a good correlation between the values of the specific activity of the intracellular proteins and those of the silver grain density over the secretory cells at the several time intervals after the injection of 3H‐tyrosine. The results of the quantitative analysis carried out in light‐ and electron‐microscope radioautographs led to the conclusion that venom proteins are synthesized in the rough endoplasmic reticulum of the secretory cells, transferred to the Golgi apparatus from where they are carried to the secretory tubule lumen by the secretion granules. The fact that the values of the relative concentration of the radioactivity of the intracisternal granules double at the last three time intervals, strongly suggests that these structures are formed by the aggregation of the amorphous material present inside the cisternae of the rough endoplasmic reticulum.
Structure, function, and long‐term maintenance of the isolated turtle colon
Authors: Lefevre M. E. , Reisman L. 
Published: June 2005

AbstractWe describe the 5‐day maintenance of sacs of turtle colonic mucosa in enriched bathing solutions. The mean maximum transepithelial potential difference (PD) developed by the sacs in Ringer solution enriched with tissue‐culture medium and gassed with 95% air‐5% CO2 was 126 mV at 24 hours. Lower values were observed in other solutions. The PD of 24‐hour sacs was partially or totally inhibited by ouabain, replacement of Na by choline in mucosal bathing fluids, or removal of Ca from serosal bathing fluids. The sacs transported Na in excess of H2O forming a dilute mucosal solution. The responses of four different sac preparations (normally oriented or everted, and stripped normally oriented or everted) to long incubation were compared. Stripped normally oriented tissue developed the highest PD and maintained the lowest water content. The morphology of fresh and long‐incubated tissue was examined. This investigation demonstrates that the turtle colon can be maintained in vitro for long periods, and it provides information on the morphology and physiology of this tissue.
Differential concanavalin A‐induced agglutination of eight‐cell preimplantation mouse embryos before and after compaction
Authors: Rector J. T. , Granholm N. H. 
Published: June 2005

AbstractEight‐cell mouse embryos undergo a morphogenetically significant process termed compaction during which blastomeres flatten against one another maximizing their areas of cell‐cell contact. Data presented here show striking differences (P<0.01) in Con A‐induced agglutination between groups of uncompacted and compacted embryos suggesting that the compaction process is accompanied by changes in blastomere surface properties.
Toxicity of bog water to embryonic and larval anuran amphibians
Authors: Saber Peter A. , Dunson William A. 
Published: June 2005

AbstractA survey of the amphibians of a north temperate zone bog revealed that a number of species common in suitable locations nearby were absent from the bog. Several species of anuran larvae and embryos suffered high mortality when placed in the naturally acidic stream draining the bog. Mortality of bullfrog larvae (Rana catesbeiana) placed at a number of sites along the natural pH gradient (pH 3.9–6.6) formed by this stream was significantly greater than in those placed in a clearwater control stream (pH 6.6–6.9). This lethality of stream water even at moderate pH's near 6.0 indicates that a toxic factor other than acidity may be involved. In the laboratory, mortality of clawed frog (Xenopus laevis) embryos was significantly greater in unaltered bog water (pH 4.0–4.3) than in bog water neutralized with sodium hydroxide or in charcoal filtered tap water. The latter two conditions did not show significant mortality differences. This implies that low pH is the principal source of toxicity for Xenopus.
The strategy of growth in the mesonephric kidney of adult Xenopus laevis
Authors: Goldin Geoffrey , Fabian Barry 
Published: June 2005

AbstractPartially nephrectomized adult Xenopus laevis were injected with tritiated thymidine on the sixth post‐operative day when only the cells of the distal tubules synthesize DNA. Autoradiographs prepared from animals killed after a further four days of recovery in the absence of the isotope revealed the presence of labelled proximal tubule cells. This suggests that the distal tubule of the nephron contains a population of ‘nephrogenic cells’ which give rise to new proximal tubule cells as well as to new distal tubule cells.