bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hormone‐induced ovulation in Ambystoma tigrinum: Influence of prolactin and thyroxine
Authors: Norris David O. , Duvall David 
Published: June 2005

AbstractTreatment of hypophysectomized or intact neotenic tiger salamander larvae (Ambystoma tigrinum) with ovine prolactin (PRL) increased sensitivity of the ovary to the ovulation‐inducing hormones, human chorionic gonadotropin and luteinizing hormone (LH). Effects of pretreatment in vivo with PRL or thyroxine (T4) on the responsiveness of ovarian fragments in vitro to ovulation‐inducing agents, LH, or progesterone (PROG) in the presence or absence of PRL were observed. In November (prior to normal spawning occurring from January through May) in vivo and in vitro treatment with PRL increased the number of oocytes producing polar bodies and the number of eggs ovulated in vitro. In April addition of PRL in vitro increased polar body formation and ovulations in response to LH or PROG, but in vivo pretreatment with PRL had no effect. Pretreatment in vivo with T4 blocked the in vitro enhancement observed with PRL. Thus, endogenous PRL may play a role in the development of ovarian sensitivity to ovulatory hormones at the level of the oocyte, and T4 may inhibit this action.
Synaptic mechanisms that generate network oscillations in the absence of discrete postsynaptic potentials
Authors: Anderson William W. , Barker David L. 
Published: June 2005

AbstractSynaptic mechanisms were examined in the pyloric network of the lobster stomatogastric ganglion which generate network oscillations in the absence of discrete postsynaptic potentials (PSPs). In normal saline, the unstimulated pyloric network underwent weak bursting in only a few cells. Stimulation of the input nerve, or bath application of the input neurotransmitter dopamine, produced similar vigorous bursting in many pyloric neurons. In saline‐containing tetrodotoxin (TTX) plus dopamine, action potentials and corresponding discrete PSPs were blocked, but the underlying slow wave oscillations in network neurons continued. No oscillations occurred in TTX‐saline without dopamine. The generation of these nonspiking network oscillations can be explained by the interaction between two synaptic mechanisms which do not produce discrete PSPs: neurotransmitter activation of bursting pacemaker oscillations in a single network neuron, and graded inhibition between network neurons.
Uptake and binding of prostaglandins in a marine bivalve, Modiolus demissus
Authors: Freas William , Grollman Sigmund 
Published: June 2005

AbstractThe existence of specific PGA2 binding sites was demonstrated in the 12,000 × g supernatant fraction of homogenized gill tissue from Modiolus demissus (Geukensia demissus). The binding of prostaglandins at these sites was pH‐dependent, time‐dependent, and reversible. The binding was more specific for prostaglandin A2 (PGA2) than prostaglandin E2 (PGE2) or prostaglandin F2α (PGF2α). Binding was enhanced by calcium and magnesium. For calcium the binding kinetics exhibited a Km of 7 mM; for magnesium the Km was 15 mM. The amount of PGA2 bound/mg protein at saturating cation concentration was determined to be 0.20 pmoles/mg for both calcium and magnesium. A dissociation constant (Kd) of 9.8 × 10−5 M was calculated by Scatchard plot analysis for the PGA2 binding site. Binding was inhibited by 20 mM Cu+ +, 10−3 M ATP and 10−3 M GTP. These low‐affinity binding sites may perform an important role in the physiological action of prostaglandins in marine bivalves.
Survival of mouse embryos after freezing and thawing in the presence of erythritol
Authors: Miyamoto Hajime , Ishibashi Takehiko 
Published: June 2005

AbstractEight‐cell mouse embryos were frozen by using erythritol as the cryoprotective agent. The samples were cooled slowly (1°C/min) to temperatures between − 15 and − 75°C before direct transfer into liquid nitrogen (− 196°C). The most effective concentration of erythritol for freezing of embryos was 0.6 M, and the optimal exposure time of embryos to 0.6 M erythritol at 0°C prior to freezing appeared to be 60 min under the conditions used. The embryos in erythritol survived slow thawing (∼20°C/min), only when cooled slowly to temperatures between − 30 and − 60°C before transfer into liquid nitrogen, and survived rapid thawing (∼500°C/min), only after transfer from − 25 to − 40°C. The highest survival rates of slowly thawed embryos were obtained after transfer to − 196°C from − 35 (63%) and − 40°C (64%), and the highest survival rates of rapidly thawed embryos were obtained after transfer from − 30°C (54%). Mouse embryos that survived freezing and thawing with erythritol as the cryoprotective agent were capable of developing to full‐term fetuses.
Light and time correlated migration of invasive hemocytes in the crayfish compound eye
Authors: Waterman Talbot H. , Piekos W. Barry 
Published: June 2005

AbstractThe number and radial distribution of hemocytes discovered periodically invading the retinas of crayfish compound eyes (Figs. 1–3) were measured under a variety of light and dark adaptation programs (Fig. 4, Table 1). Overall the density of these cells in the eye was significantly less in light than in darkness (Figs. 5–8, Table 2). The corresponding hemocyte ebb and flow occurred in intercellular spaces between retinulas, not in blood vessels which are absent from decapod crustacean eyes everywhere distal to the basement membrane.Hemocytes under all conditions were most dense just below the basement membrane. Within the retina their occurrence ranged from maximum at the basement membrane to minimum or zero near the distal tip of the rhabdom, beyond which they rarely occurred (Figs. 5, 6, Table 3). The effectiveness of light in reducing hemocyte concentrations was maximal distally and minimal proximally and hence had a gradient inverse that for cell density (Fig. 8).Bilateral experiments with one eye covered and the other exposed showed that light could independently and unilaterally induce hemocyte emigration from the retina (Fig. 5). But in time‐of‐day experiments hemocyte movements occurring before the programmed cyclic diurnal illumination changes proved that endogenous control mechanisms must also participate (Fig. 7). Such experiments also showed the fewest retinal hemocytes (≈︁0) at 18:00 hours, when the rate of rhabdom synthesis should be near maximum.So far no direct phagocytic uptake of identifiable photoreceptor membrane has been found in crayfish retinal hemocytes. Nevertheless these cells were seen to make junctionlike contacts with retinular cells and appeared to be actively ingesting interstitial detritus in the retina at levels coincident with the radial extent of the rhabdoms (Figs. 1–3). Previously phagocytic wandering cells were known to participate in photoreceptor membrane turnover in teleost eyes and in reptile pineal organs although fixed retinal pigment epithelial cells are normally involved in this function in birds and mammals.
Possible involvement of macrophages in embryo–maternal relationships during ovum implantation in the rat
Authors: Tachi C. , Tachi Sumie , Knyszynski Ahuva , Lindner H. R. 
Published: June 2005

AbstractDistribution of phagocytic cells in the rat endometrium during the estrous cycle and early gestation was examined by histological, electron microscopic, and histochemical techniques. The results show that numerous macrophages emerge around the nidus shortly after the onset of ovum implantation. Such macrophages, however, were not present within the decidua, suggesting that this tissue may be a protective barrier against the migration of phagocytic cells towards the implants. Approximately 48 hours after the onset of implantation, the number of endometrial macrophages decreased dramatically.
Isolation of epithelial cells from the corpus epididymidis and analysis for glycerylphosphorylcholine, sialic acid, and protein
Authors: Hoffmann David S. , Killian Gary J. 
Published: June 2005

AbstractEnzymatically dispersed cells from the rat corpus epididymidis were separated by unit gravity sedimentation and centrifugal elutriation. Based on differential cell counts, principal cells isolated by centrifugal elutriation were 55% pure, while basal cells and fibroblasts were 88% and 61% pure, respectively. Compared to unit gravity separation, purity was an average of 7% higher in principal and basal cell fractions obtained by elutriation. Viability was>87% by either method, but yields following elutriation averaged 23% higher for basal cells, 78% higher for principal cells, and 290% for fibroblasts than corresponding yields following unit gravity separation. Analyses for epididymal secretory products indicated that cellular content (μutmoles/109 cells) of glycerylphosphorylcholine (GPC), sialic acid, and protein was greater in principal cells than other cell types (p<.05). When expressed on the basis of cellular volume, concentraions of GPC and protein also were significantly greater in basal and principal cells than fibroblasts (p<.05). Caput sperm contained significantly more GPC than either corpus or cauda sperm (p<.005). Protein concentrations in caput and corpus sperm were similar, but concentrations were lower in cauda sperm (p<.005). Levels of sialic acid did not vary among sperm from different epididymal regions. It was concluded that principal cells from the corpus epididymidis contain major quantities of three epididymal secretory products and that regional differences in the function of the epithelium are present.
Alteration of annulate lamellae in the in vitro progesterone‐treated, full‐grown Rana pipiens oocyte
Authors: Kessel Richard G. , Subtelny Stephen 
Published: June 2005

AbstractIn full‐grown but immature Rana pipiens ovarian oocytes, stacks of annulate lamellae are preferentially localized in the ooplasm between the germinal vesicle and the animal pole. Furthermore, the largest stacks of these porous cytomembranes tend to be localized deeper in the ooplasm in proximity to the germinal vesicle, while smaller, but variable‐sized stacks of annulate lamellae are found closer to the oolemma of the animal pole. Manually defolliculated, full‐grown oocytes were cultured in progesterone for periods of 1, 3, 5, 6, 9, 12, 16, 18, and 22 hours at 18°C. Annulate lamellae were observed in the animal pole ooplasm after 1, 3, 5, 6, and 9 hours of in vitro culture in progesterone at 18°C. In contrast, annulate lamellae were not observed in fully grown oocytes cultured in the progesterone for 12, 16, 18, or 22 hours at 18°C. Rather, many localized areas in the animal pole ooplasm were observed that contained large numbers of closely packed vesicles of different size. The largest clusters of vesicles were present in the ooplasm near the germinal vesicle. Progressing toward the oolemma of the animal pole, the vesicular clusters appeared to become smaller in area. These clusters of vesicles were not observed in either untreated control oocytes at 3–22 hours of culture, or in those treated with progesterone for 1, 3, 5, 6, or 9 hours. The results suggest that after the appropriate maturation‐inducing treatment with progesterone, annulate lamellae lose their integrity, probably by a process of vesiculation. This represents one of the first morphological changes which occurs during the induction of meiotic maturation. The alteration of annulate lamellae observed in the progesterone‐treated oocytes occurs prior to complete germinal vesicle breakdown, for under the experimental conditions described, the germinal vesicle nuclear envelope did not completely break down until between 18 and 22 hours of culture in progesterone.
Hyperphagia and the control of ingestion in the female mosquito, Culiseta inornata (Williston) (Diptera: Culicidae)
Authors: Owen William B. , McClain Elizabeth 
Published: June 2005

AbstractHyperphagia resulted in all females of Culiseta inornata that were fed 1 M sucrose after the ventral nerve cord was severely damaged or severed in either abdominal segment I, II, or III. Hyperphagia also occurred in 42% of females fed successive higher concentrations of sucrose ranging from 0.25–2.0 M. The conclusions are: (1) Signals from receptors in the anterior abdominal segments limit the intake of sugary liquids; (2) this type of receptor is absent from the ventral diverticulum; and (3) excitatory input from oral receptors may dominate inhibitory input from abdominal stretch receptors.
Developmental properties of induced buds from a nonbudding mutant of Hydra viridis
Authors: Novak Patricia L. , Lenhoff Howard M. 
Published: June 2005

AbstractThe apical portions of the nonbudding mutant of Hydra viridis were induced to bud by grafting to them basal portions of wild type hydra of the same species. The induced buds had unusual developmental and morphogenetic properties that frequently showed characteristics of both wild type and mutant animals. The rate and extent of bud induction varied depending upon the body region of the wild type tissue grafted to mutant tissue. The gastric region induced the most buds at the highest rate. Induced buds containing cells from both the wild type and the nonbudding mutant were referred to as “heterocytes”. Wild type heterocytes were more like the mutant. Mutant heterocytes had regeneration properties characteristic of both the wild type and mutant animals depending upon how long they had been fed. The initial budding rates of the wild type heterocytes varied, but eventually all wild type heterocytes transformed into animals of mutant phenotype. These observations suggest that complex interactions are taking place in the heterocytes composed of cells derived from both the wild type and the nonbudding mutant.
Photo‐thermoperiodic effects on fat stores in the green anole, Anolis carolinensis
Authors: Ferrell Blaine R. , Meier Albert H. 
Published: June 2005

AbstractA circadian rhythm of thermosensitivity is set by a photoperiodic schedule (LD 12:60) in lizards at 20°C so that the coincidence of 6‐hour thermoperiods (30° C) with a thermosensitive phase is stimulatory for fattening. The thermosensitive phase reoccurs every 24 hours. Thermoperiodism involves circadian mechanisms similar to those which have been described for photo‐periodism.
Effects of pinealectomy and melatonin on the photoperiodic gonadal response of the male lizard Anolis carolinensis
Authors: Underwood Herbert 
Published: June 2005

AbstractThe effects of pinealectomy and exogenous melatonin treatment on the photoperiodic testicular response in the lizard Anolis carolinensis were examined at two times of year. In the summer (July–August) neither pinealectomy nor melatonin affected the photoperiodic response. In the fall (September–October) pinealectomy had a progonadal effect in lizards maintained on either LD 8:16 or LD 14:10 photoperiods. Melatonin blocked the gonadal development in response to pinealectomy on LD 8:16 but melatonin did not inhibit the acceleration in testicular development caused by pinealectomy on LD 14:10. However, melatonin did inhibit testicular development in intact (nonpinealectomized) anoles exposed to LD 14:10.These results show that pinealectomy can modify testicular function in Anolis, that the effects of pinealectomy are seasonal, and that melatonin may be a reproductively active factor involved.
Immunohistochemical localization of phosphoglycerate kinase isozymes in mouse testes
Authors: Vandeberg John L. , Lee Chi‐Yu , Goldberg Erwin 
Published: June 2005

AbstractWe have used specific antibodies against mouse phosphoglycerate kinase (PGK) isozymes in an immunohistochemical technique to determine which cells in testicular cross sections contain PGK‐A and which contain PGK‐B. Phosphoglycerate kinase‐A is highly concentrated in interstitial cells and is weakly expressed in Sertoli cells and throughout the germinal epithelium. Phosphoglycerate kinase‐B is highly concentrated in spermatids and spermatozoa, but it is not detectable in stage 8 spermatids or earlier gametogenic stages, or in somatic cells of the testis. These results confirm that PGK‐B is a sperm‐specific isozyme in mice.
Loss of pH sensitivity of amino acid incorporation during early development of the horseshoe crab, Limulus polyphemus L
Authors: Bannon G. A. , Shen S. S. , Brown G. G. 
Published: June 2005

AbstractEmbryos of the primitive arthropod, Limulus polyphemus L., exhibit a 5–50‐fold increase in amino acid incorporation approximately 6–8 hours after fertilization, which is not concomitant with cytoplasmic alkalization. Lowering of intracellular pH before this increase occurs will prevent the initiation of amino acid incorporation. However, lowering the internal pH after the increase has occurred does not inhibit the incorporation rate. These results suggest that amino acid incorporation in Limulus embryos is a pH‐sensitive event before the increase occurs, but becomes pH insensitive after the increase in incorporation rate has been initiated.
Linkage disequilibrium between the T/t complex and Pgk‐2 in wild mice
Authors: Rudolph Natalie S. , Vandeberg John L. 
Published: June 2005

AbstractLinkage disequilibrium between the T/t complex and Pgk‐2 – two loci flanking the murine major histocompatibility complex on chromosome 17‐ has been found in a population of wild mice. By subjecting 78 wild males to progeny testing, we extracted 15 recessive t haplotypes of the T/t complex and assigned 12 of them to the tw5 complementation group. We also determined the allelic phase of T/t, Pgk‐2, and Ce‐2 on both chromosomes from each wild male. The allele Pgk‐2c was always associated with a t haplotype, although the converse was not true.
Haemolymph gas transport, acid‐base regulation, and anaerobic metabolism during exercise in the land crab (Cardisoma carnifex)
Authors: Wood Chris M. , Randall D. J. 
Published: June 2005

AbstractHaemolymph gases, acid‐base status, and metabolite levels were studied in Cardisoma carnifex at rest and after 10 minutes of mild (0.2 body lengths/second) or severe (exhausting, 0.5 BL/second) exercise. O2 transport is very similar to that in aquatic crabs. At rest, arterial haemocyanin saturation is ≃ 87%, venous saturation is ≃ 45%, and tissue utilization is ≃57%. During exercise, Ṁ rises 2–3‐fold. Ps fall so that O2 transport is shifted onto the steep part of the dissociation curve, venous saturation decreases markedly while arterial saturation remains high, and cardiac output rises. These adjustments raise the P gradient at the respiratory surface, tap the haemolymph O2 store, and maintain or increase the a–v O2 difference so that utilization reaches ≃82%. Postexercise acidosis augments these effects via the Bohr shift. Resting P's are low (≃15 torr) for an air‐breather, and Pa changes minimally despite 2.5–5‐fold evaluations in Ṁ. All haemolymph gas levels return to normal within 0.5–1.0 hours. Postexercise acidosis is largely metabolic, and smaller than in aquatic crabs. Lactate anions and protons enter the haemolymph in equivalent amounts and totally account for the metabolic acidosis. Elevated NH3 and pyruvic acid levels have negligible influence. During recovery, the metabolic acid load is reduced faster than the lactate load, resulting in alkalosis, possibly because of CaCO3 mobilization from the carapace. Exercise metabolism appears largely anaerobic, but changes in haemolymph lactate levels do not correlate with the O2 debt. However, the “excess lactate” concept which compensates for pyruvate elevation gives a good index of the debt. All changes are more marked after severe than after mild exercise, but the patterns are similar.
Localization of protein absorption during transport of food in the intestine of the grasscarp, Ctenopharyngodon idella (Val.)
Authors: Stroband H. W. J. , van der Veen F. H. 
Published: June 2005

AbstractThe uptake of protein and amino acids in the intestine of young (18 months old) and adult grasscarp has been studied with the inert marker (Cr2O3) method. The absorption of protein takes place in the anterior 40–50% of the gut.The second intestinal segment (± 25% of gut length) has the ability to absorb macromolecules of protein. Ferritin (mol wt 400,000) was found in pinocytotic vesicles in enterocytes of this second segment. On the basis of morphological and histochemical evidence, it has previously been suggested that the pinocytotic uptake of whole protein molecules might be related to the lack of peptic digestion in stomachless fishes. A major quantitative function in protein absorption, however, cannot be attributed to the second gut segment, and proteins appear to be digested adequately in these stomachless animals. The function of this part of the gut and the role of the stomach in protein digestion in other vertebrates remain to be explained.The absorption of individual amino acids in the intestine of the grasscarp suggests that essential amino acids are preferentially absorbed. The rapid disappearance of lysine and arginine from the chyme points to a tryptic breakdown of proteins.
Application of the thermodilution technique for measuring cardiac output and assessing cardiac stroke volume in crabs
Authors: Burnett Louis E. , de Fur Peter L. , Jorgensen Darwin D. 
Published: June 2005

AbstractA thermodilution technique is used to measure the flow of hemolymph through the heart of crabs. The technique consists of injecting a small volume of cold filtered sea water into the ventricle and monitoring temperature changes with time in an artery immediately downstream from the heart using a surgically implanted thermocouple. An experimental evaluation of the method affirms that it is a direct measure of the bulk flow of hemolymph through the heart. Values of cardiac output determined in this manner fall within the range of Fick estimates of hemolymph flow made on animals treated similarly. Since measurement of cardiac output by thermodilution can be achieved in a matter of seconds, simultaneous monitoring of heart rate permits the calculation of cardiac stroke volume. In two species of crabs examined, much of the variation in cardiac output is accounted for by changes in stroke volume rather than changes in heart rate.
Metabolism and ultrastructure of dormant podocysts of Chrysaora quinquecirrha (scyphozoa)
Authors: Black Robert E. 
Published: June 2005

AbstractOxygen uptake by the podocyst of the scyphozoan, Chrysaora quinquecirrha, is about one‐fourth that of the scyphistoma, based on total protein, but is nearly equal to that of the scyphistoma when calculated on the basis of total DNA. Opening the podocyst cuticle causes a two to threefold increase in oxygen consumption within the first hour.Podocysts held for 11–13 months at 25°C retain viability, even though more than half of the DNA, one‐third of the protein, and one‐fifth of the lipid are lost. Ultrastructural observations indicate that the cyst contains a population of active cells, with numbers of mitochondria and microvilli, and a mass of internal yolkfilled cells, some of which are lysed and/or phagocytized during dormancy. The active cells acquire many phagocytic vacuoles containing large particles. This may represent a unique mechanism for prolonged survival in the dormant condition.
Effects of ammonia on liver lysosomal functionality in Salmo gairdneri rich
Authors: Arillo A. , Margiocco C. , Melodia F. , Mensi P. 
Published: June 2005

AbstractSalmo gairdneri specimens were exposed for 4–48 hours to three different concentrations of un‐ionized ammonia (UIA). An increase in lysosomal sensitivity to osmotic shock and in total proteolytic activity occurs in the liver. The amount of this increase depends upon the exposure time or upon environmental and tissue ammonia levels. On the other hand ammonia does not affect lysosome hydrolases activity in vitro.