bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of day length and reproductive state on diel rhythms of luteinizing hormone levels in the plasma of white‐crowned sparrows, Zonotrichia leucophrys gambelii
Authors: Wingfield John C. , Vleck Carol M. , Farner Donald S. 
Published: June 2005

AbstractPlasma levels of LH were measured through the course of 24 hours in photosensitive and photorefractory, adult male white‐crowned sparrows, Zonotrichia leucophrys gambelii, exposed to both long (20L, 4D) and short (8L, 16D) days. In photorefractory birds held on both long and short days there is an increase in plasma levels of LH late in the subjective day or soon after the onset of the scotophase. These levels remain high for most of the night and decline to low levels just after the onset of the photophase. In addition there is a second increase in circulating LH, 3–5 hours after the onset of the photophase, with a second minimum about 10 hours later.A similar rhythm occurs in photosensitive birds held on short days. Plasma levels of LH increase late in the day and remain high throughout most of the night. Lowest levels were measured just after onset of photophase. In contrast, circulating LH in photosensitive birds exposed to long days showed no discernable diel rhythm. During the night, plasma levels of LH of photorefractory birds, and also photosensitive birds on short days, are as high as those of photosensitive birds on long days.
Mouse sperm motility affected by factors in the T/t complex
Authors: Tessler Steven , Carey Joan E. , Olds‐Clarke Patricia 
Published: June 2005

AbstractMotility characteristics of epididymal sperm from tw32/+ and T/+ males of several strains were compared to those of sperm from the congenic, wild‐type mice. Epididymal sperm from C57BL/6‐tw32/+ (B6‐tw32/+) males showed a significant decline in vigorous motility and a significant increase in adhesivity to glass during 7.5 hours in vitro, while sperm from B6‐+/+ males showed no changes in these characteristics. The apparent mean velocities of epididymal sperm were: B6‐tw32/+, 32 μ/sec; C3H‐tw32/+, 60; B6XC3H hybrids (F1*‐tw32/+), 44; and C3HXB6 hybrids (F1‐tw32/+), 58. Each of these values was significantly lower than that of sperm from their congenic wild‐type strains: B6‐+/+, 115; C3H‐+/+, 177; F1*‐+/+, 168 and F1‐+/+, 195 μ/sec. B6‐T2J/+ sperm had velocities intermediate to the congenic +/+ and tw32/+ genotypes, whereas C3H‐T/+ sperm velocity was not significantly different from C3H‐+/+. These differences in measured sperm velocity may not reflect real differences in swimming speed, but rather may indicate a difference in the shape of swimming trajectories. Erratic and convoluted swimming trajectories were observed for the majority of sperm from tw32/+ males of all genotypes. Differences in motility patterns of sperm from tw32/+ males could play a role in the abnormally high transmission of tw32 through the male.
A comparison of cell proliferation patterns in the digestive tract of ascidians
Authors: Ermak Thomas H. 
Published: June 2005

AbstractCell proliferation patterns in the postbranchial digestive tract of a variety of ascidian species were investigated with autoradiography and tritiated thymidine. Based upon the distribution of radioactive nuclei, gut cell populations were classified as either static, expanding, or renewing. In most ascidians, renewing populations occur in the esophagus and stomach, but expanding populations sometimes occur in all or part of the intestine. From species to species, the number of cell renewal units (pairs of germinal and mature zones) in each portion of the digestive tract increases with increasing organ size, and this multiplication of renewal units follows the folding patterns in the gut. Cell turnover is fastest and the size of a cell renewal unit smallest at the anterior end of the gut. The smallest colonial ascidians have a single renewal unit per cell population in the esophagus and stomach and an expanding population in the intestine. Epithelial folding and multiplication of cell renewal units occurs in solitary species of increasing body size. One cell population occurs on the stomach folds of more primitive solitary ascidians, two of those of advanced species. The digestive diverticulum, which only occurs in two families, is renewed much the same as the stomach, and probably evolved from that organ. In the intestine of primitive solitary ascidians, renewing populations only occur at the anterior end; with evolutionary advancement, renewing populations line the entire intestine.
The male factor in fertilization of rat eggs in vitro
Authors: Shalgi Ruth , Kaplan Ruth , Nebel L. , Kraicer P. F. 
Published: June 2005

AbstractBoth epididymal and ejaculated spermatozoa give usable rates of fertilization of superovulated oocytes in vitro. The epididymal sperm gave higher rates, but ejaculated sperm were preferred because intra‐donor variation was lower than inter‐donor variation. A selected population of 14 male donors had normally distributed fertilizing capacity with a mean and standard deviation of 77 ± 14% (2,823 eggs). Successive ejaculates usually gave similar rates of fertilization. An attempt was made to eliminate dead and agglutinated cells from the ejaculated sperm by filtration through a column of glass beads. Despite the expected marked improvement in the average motility, the eluted spermatozoa were incapable of fertilizing. We concluded that the preferred source of spermatozoa for fertilization in vitro is ejaculated sperm. In the rat, motility and cell morphology are not adequate criteria for fertilizing capacity of treated spermatozoa.
Sperm capacitation in the fallopian tube of the hamster and its suppression by endocrine factors
Authors: Viriyapanich P. , Bedford J. M. 
Published: June 2005

AbstractEvidence obtained in the rabbit, an induced ovulator, has created a general view that the sperm capacitation ability of the oviduct cannot be modified significantly by ovarian steroids. The possibility that this may not be so in the reproductive tract of cyclic species has been investigated by timed transfer of eggs and spermatozoa into female hamsters maintained in different endocrine states. In estrous females, few native eggs were penetrated by 5 hours, but a majority were penetrated 6–6.5 hours after insemination of fresh epididymal spermatozoa directly into the ovarian bursa. This indicates that a time of approximately 5–6 hours is required for capacitation in the hamster oviduct alone. Up to 2 hours were needed for most eggs to be penetrated after their transfer to oviducts containing fully capacitated spermatozoa. Subsequent experiments using these criteria showed that the ability of the oviduct to support fertilization was affected significantly by the endocrine state of the female. It was not influenced noticeably by ovariectomy. However, whereas maximal levels were seen on days 1,3, and 4, fertilization was reduced significantly (P < 0.001) on day 2 of the estrous cycle when progesterone levels had been elevated for approximately 48 hours. Fertilization of eggs transferred to inseminated oviducts was also reduced comparably in ovariectomized hamsters injected with 3 mg of progesterone twice per day for 9–12 days, and in those that were 8–10 days pregnant. The prospects for complete suppression of capacitation in species with more prolonged cycles and the relevance of this for contraception and analysis of the factors responsible for capacition are discussed.
Post‐exercise acid‐base balance and ventilatory control in Birgus latro, the coconut crab
Authors: Smatresk N. J. , Cameron J. N. 
Published: June 2005

AbstractThere is a postexercise acidosis in the coconut crab, Birgus latro, which is initially due to an elevation in the hemolymph P, and a metabolic acidosis which is only partially due to lactic acid. Hyperventilation following exercise causes a respiratory alkalosis that helps to restore acid‐base balance. The ventilatory receptors appear to be internally located, and ventilation is stimulated by a drop in the hemolymph pH or [HCO], but not by P or P. Amelioration of the metabolic acidosis in normal crabs occurs in 1 hour despite elevated lactate levels. Crabs with their gills removed showed only a transient lag in both respiratory and metabolic recovery from acidosis, indicating the dominance of the branchial lung of Birgus in gas exchange. The data suggest that intra‐ and extracellular transfers may be significant in acid‐base regulation.
A survey of blood and tissue nitrogen compounds in terrestrial decapods of Palau
Authors: Henry Raymond P. , Cameron James N. 
Published: June 2005

AbstractTerrestrial decapods have significant levels of ammonia, uric acid and free amino acids in their blood, but blood is hypo‐osmotic to local seawater by as much as 300 mOsm/kg. Blood water content is approximately 90%, with protein making up virtually all the difference, whereas tissue water is between 70% and 80%. The tissue free amino acid pool is composed primarily of glycine, serine, proline, alanine and arginine, which are typical of all crustaceans. The size of the muscle pool is reduced in comparison to aquatic species, while that of gill is comparable. Tissue ammonia levels are very low in comparison to FAA, but these levels are significantly higher in gill than in muscle.
Maintenance of mating reactivity and capacity of transferring meiotic induction by an activated to a homotypically united cell in Blepharisma
Authors: Santangelo Giovanni , Nobili Renzo 
Published: June 2005

AbstractThe two complementary mating types of Blepharisma japonicum, I and II, undergo cell pairing if activated by the complementary gamones. Pairs form in three possible combinations: I–I, II–II, I–II. In the two former unions (homotypic pairs), no nuclear changes occur in the cells. In the third union (heterotypic pairs), a diffusible factor produced during the first 2 hours of cell contact is assumed to induce meiosis and other nuclear changes in the cells. When cells were surgically separated during the first 2 hours after the onset of pairing, the behavior of cells from heterotypic pairs with respect to the occurrence of meiosis was alike in 93% of the cases. Cells of heterotypic pairs, separated from 0.66 to 2.66 hours after mixing complementary mating types, can homotypically reunite with gamone‐activated cells of their own mating type. The capacity of separated cells to reunite decreases as the time of heterotypic union increases. In 32 cases out of 80, separated cells whose partner underwent meiosis reunited, and three of them were able to induce macronuclear changes correlated to meiosis in the homotypically united cells.
A note on the inhibition of in vitro meiotic maturation of mammalian oocytes by dibutyryl cyclic AMP
Authors: Jagiello Georgiana , Ducayen Mercedes B. , Goonan William D. 
Published: June 2005

AbstractCytogenetic data are presented which indicate species differences in the response of oocytes maturing in vitro in the presence of dibutyryl cyclic AMP (dbcAMP). Inhibition of ewe oocyte maturation was noted at germinal vesicle, MI, and MII in the presence of 25–750 μg/ml of dbcAMP. Cow oocytes were primarily affected at MI and MII by similar concentrations, and only 750 μg/ml delayed golden hamster oocytes at these stages. These findings highlight the variability between the responses of the oocytes of these mammals and the rat, mouse, or pig.
Western fence lizard (Sceloporus occidentalis) chemical signals. II. A replication with naturally breeding adults and a test of the cowles and phelan hypothesis of rattlesnake olfaction
Authors: Duvall David 
Published: June 2005

AbstractThe capacity of naturally breeding western fence lizards (Sceloporus occidentalis biseriatus) to discriminate and respond to conspecific and control chemical cues was examined. Lizards were presented with markings and exudates of male and female donors, as well as cologne (a pungency control) and water, in a successive discrimination procedure. Behavioral actions quantified after exposure to the different chemical cue types included lingual extrusions (tongue flicks and substrate licks), rapid nasal inhalations, and the performance of push‐up visual displays. Initial latencies to lingual investigation of the different extracts and markings also were recorded as a measure of the extent to which nasal olfaction would switch on the tongue‐Jacobson's organ (vomeronasal olfactory) system. Although no sex differences in total levels of response were noted, males and females exhibited significant lingual discriminations equally to exudates collected from male or female conspecifics. Push‐up visual displays also were noted in response to conspecific markings. Cologne‐marked surfaces, however, elicited nonsignificant levels of lingual investigation and push‐up displaying. Latencies to initial tongue flicks, but not substrate licks, were significantly shorter when any material other than water was present. Therefore, as suggested by Cowles and Phelan ('58), nasal olfaction may indeed be more of a “quantitative,” distance sensing system that responds to the presence of any pungent substance by initiating further investigation via the tongue‐Jacobson's organ system. The latter appears to be more “qualitative,” or discriminating, as indexed by relatively greater levels of lingual investigation of conspecific markings than cologne. No differences were noted in rapid nasal inhalation activity. The results suggest that pheromone markings, along the ground or other surfaces, may be important to spacing and territorial maintenance in nature. This could occur through direct pheromone effects on signal recipients, or indirectly, through the stimulation of increased push‐up activity, which could make lizards more visible to one another.
Correlation of juvenile hormone titer changes with reproductive tract development in the posteclosion Monarch butterfly
Authors: Herman W. S. , Lessman C. A. , Johnson G. D. 
Published: June 2005

AbstractThe posteclosion growth of the reproductive tracts of male and female Monarch (Danaus plexippus) butterflies was quantified over a 30‐day period of storage in summer conditions. Concomitantly, the Galleria bioassay was used to quantify hemolymph juvenile hormone (JH) titers in both sexes. The data demonstrated rapid posteclosion growth, lasting for about one week, of the female ovaries and colleterial glands and the male accessory glands, tubular glands, and ejaculatory ducts. This rapid growth was not directly related to increased animal weight, but it was associated with high JH titers. The highest titers observed were found in females on the third day after eclosion. Subsequently, most of the above organs exhibited a reduced growth rate that appeared to depend upon increased body weight. Butterflies examined during this latter stage (from about 8‐30 days posteclosion) exhibited significant reductions of hemolymph JH. JH injections into both sexes showed that most organs known to be JH‐sensitive retained hormone sensitivity during the period of reduced growth. The growth of female receptacle glands and bursa copulatrix and the male testes and seminal vesicle‐vas deferens complex was not directly comparable to those organs discussed above.
The role of calcium in maintaining motility in mouse spermatozoa
Authors: Heffner Linda J. , Storey Bayard T. 
Published: June 2005

AbstractMaintenance of mouse sperm motility requires exogenous Ca+2 in most, but not all, samples of epididymal spermatozoa. In these samples, the loss of motility with time is the same in Tris/NaCl buffer containing 1.7 mM Ca+2 (medium TNC) as it is in complete culture medium used for in vitro fertilization (medium CM) over the first 2 hours; spermatozoa in medium TNC lose motility at more rapid rate thereafter. The cation specificity for maintenance of motility is unusual in that both Sr+2 and Mg+2 substitute for Ca+2, with Mg+2 being the more effective. In the absence of Ca+2, these samples of mouse epididymal spermatozoa in Tris/NaCl buffer (medium TN) lose motility in about 30 minutes. If Ca+2 is added after incubation in TN for 15 minutes, motility is maintained as well as it is in medium TNC. If Ca+2 is added at 30 minutes, motility is partially restored. But if Ca+2 is added after 60 minutes, there is no restoration of motility. Spermatozoa suspended in medium TNC lose motility rapidly on addition of EGTA in excess of the Ca+2 present. Attempts to show uptake of Ca+2 by spectrophotometric assay, by effects of Ca+2 on oxidative metabolism, and by electron probe X‐ray microanalysis were unsucessful; motility is not maintained by entry of Ca+2 into the cells. Our results are consistent with a Ca+2 site on the plasma membrane and suggest that these sites function as oligomers of ordered subunits whose structure requires Ca+2. In the absence of Ca+2, the ability to form the oligomer is lost with time, possibly due to an irreversible conformational change.
Metabolic responses of striped bass (Morone saxatilis) to temperature acclimation. II. Alterations in metabolic carbon sources and distributions of fiber types in locomotory muscle
Authors: Jones Peter L. , Sidell Bruce D. 
Published: June 2005

AbstractThe effects of temperature acclimation on (1) fiber‐type distribution, and (2) alternate metabolic fuels for energy supply within different skeletal muscle fiber types in striped bass (Morone saxatilis) were examined. Histochemical analysis demonstrated an increase in the proportional cross sectional area of oxidative red fibers from 9.03% to 15.03% during cold acclimation (25°‐5°C). The rate of oxygen consumption was 1.78 times greater in red muscle than white in 25°C acclimated fish. This ratio increased to 2.32 in 5° fish. Oxidation of both 14C‐U‐glucose and 14C‐1‐palmitate was significantly greater in red muscle than in white at both acclimation temperatures. A lack of thermal compensation for metabolism of 14C‐U‐glucose was exhibited by both fiber types. Red muscle showed a dramatic increase in rate of 14C‐1‐palmitate oxidation after cold acclimation. Activities of glycolytic enzymes confirmed a high glycolytic capacity in white muscle; glycolytic capacities were dependent on acclimation temperature in both fiber types. Only red muscle showed a positive compensation for activities of key enzymes from aerobic metabolism. The results indicate an increasing reliance on aerobic metabolism of fat in the swimming musculature at cold acclimation temperatures. The capacity for sustained swimming under these conditions is conserved by (1) an increase in the relative proportion of red fibers, and (2) an enhanced capacity for energy supply in the red muscle by oxidative metabolism of stored lipid.
The role of the blood in the temperature dependence of oxidative metabolism in decapod crustaceans. II. Interspecific adaptations to latitudinal changes
Authors: Mauro Nicholas A. , Mangum Charlotte P. 
Published: June 2005

AbstractThe effects of acclimation temperature on hemocyanin‐oxygen (HcO2) transport were examined in two species of decapod crustaceans representing different geographic and thermal ranges. In the coldwater species Cancer borealis and the warmwater species Menippe mercenaria, the performance of the HcO2 transport system is maximized at 15 °C, a summer temperature in the northern habitat and a winter temperature in the southern habitat. In C. borealis little unloading at the tissues occurs at 5 °C, and in M. mercenaria oxygenation at the gill is incomplete at 25 °C. The temperature coefficients describing rates of ventilation, heartbeat, and total oxidative metabolism fall within a narrow range (Q10 = 1.9−3.6), providing no indication of ventilatory or cardiovascular adjustments that would allow the HcO2 transport system to function at the maximum level at different temperatures. Comparison of the HcO2 equilibrium properties suggests that HcO2 affinity has been selected for a particular thermal range, but not cooperativity or pH dependence. The thermal limits of the O2 transport system are set by both the direct effect of temperature on HcO2 equilibrium and the indirect effect via the Bohr shift that accompanies the change in blood pH with temperature.
Experimental studies of the origin and expression of metameric pattern in the chick embryo
Authors: Meier Stephen , Jacobson Antone G. 
Published: June 2005

AbstractOn either side of Hensen's node of the fully extended primitive streak of the chick embryo (stage 4) the mesoderm is already organized into circular domains called somitomeres. As Hensen's node regresses, paraxial somitomeres are added in tandem and are early morphological representatives of metameric pattern in the mesoderm. These organized circular domains of mesenchyme cells are best visualized with stereo pair scanning electron microscopy. Experiments suggested that a prepattern of segmentation exists in and around the fully extended primitive streak. Streaks divested of Hensen's node can generate some paraxial somites, but only if surgically split down the midline. We assessed metameric pattern formation in nodeless streaks, both severed and unsevered down the midline. Operated blastoderms were cultured 15 hours, fixed, dissected, processed for scanning electron microscopy, and photographed in stereo. Split nodeless streaks produced a cranial to caudal sequence of somitomeric development. This sequence is similar to the sequential maturational events seen in the segmental plate of older embryos. The least mature somitomeres, toward the posterior end of the severed edge, appear as circular domains of radially oriented cells, looking much like the first somitomeres to emerge near Hensen's node of the stage 4 streak. More cranially along the severed edge, somitomeres are morphologically more mature, being more condensed, with cells oriented about a central myocoele. At the most cranial end of the severed piece, somitomeres are the most mature, having contracted about their centers to create intersomitomeric gaps that permit their identification with light microscopy as individual “somites.” Embryos from which the node was removed, but the streak left intact, generated only the most primitive somitomeric pattern repetitively along either side of the primitive groove. We conclude that regression of Hensen's node provides for the timely initiation of morphogenesis of somitomeres from a prepattern of segmentation that already exists.
Adaptive lung growth during chronic cold plus hypoxia is age‐dependent
Authors: Lechner Andrew J. , Grimes Margaret J. , Aquin Lynn , Banchero Natalio 
Published: June 2005

AbstractWealing male guinea pigs (Cavia porcellus) of initial body weight 207–271 g and 2–3 weeks of age were exposed for up to 16 weeks to combined cold (Ta = 6°C) and hypoxia (ambinet P = 85 torr) before analysis (range of body weights at sacrifice, 253–932 g). The body growth rate of the cold + hypoxia guinea pigs was not different from that of the control animals raised at Ta = 22°C and an ambient P = 133 torr. After 3 weeks of cold + hypoxia exposure, and a mean body weight of 402 g, the weight‐specifi lung volume, VL, of 3.59 ± 0.29 ml/100 g BW (mean ± SEM) in cold + hypoxia was significantly greater than the value of 2.65 ± 0.16 for age‐ and weight‐matched controls. However, by week 16 of exposure, there wer no significant differences in VL betweent he experimentals (2.24 ± 0.08) and the controls (2.04 ± 0.15). Similar relationships were found between the two groups for weight‐specific alveolar epithelial and capillary endothelial surface areas. Although chronic exposure to both increased oxidative demand and reduced oxygen availability trasiently increased the pulmonary dimensions suitable for gas exchange, normal adult dimensions were ultimately achieved. Furthermore, the similarity of lung growth in cold plus hypoxia to the patterns reported for exposure to cold or hypoxia alone suggests a common and rather nonspecific response mechanism for such adaptive growth in the lung.