bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modalities of the action of temperature on sexual differentiation in field‐developing embryos of the European pond turtle Emys orbicularis (Emydidae)
Authors: Pieau Claude 
Published: June 2005

AbstractThis paper is a study of sex ratios among turtle (Emys orbicularis) hatchlings and young from eggs incubated in the ground, as a function of soil temperature during the gonadal thermosensitive period. Five experiments were performed in Brenne (France) during the summers of 1974, 1975, and 1979. In all these experiments, the sex ratios were found to be skewed. In one experiment, the percentage of males was nearly 50%, whereas the number of females was reduced and the other individuals displayed an intersexual phenotype (the gonads were ovotestes). In the other experiments, the number of males was reduced, whereas the number of females approached 50% or was superior to 50% and the other animals displayed an intersexual (ovotestes) or indeterminate (thin atypical gonads) phenotype. The soil temperature was registered at the same depth as the eggs, and the temperature curves were analyzed for the 12 days following the beginning of the gonadal thermosensitive period (stage 16 of embryonic development). This analysis shows that the first half of this period is the most important for gonadal sexual differentiation. In the first experiment, temperature remained below or surpassed slightly the threshold temperature of 28.5°C (at which males and females, but also intersexes, are obtained). These conditions favored male differentiation. Then, the maxima were higher, allowing female differentiation which was either typical (2 cases of 21 only) or partial (intersexes which are probably genetic females). In the other experiments, the maxima were high, reaching 35 to 40°C, from the very beginning of the thermosensitive period, and although alternating with low minima (inferior to 25°C) they favored female differentiation and inhibited male differentiation. Therefore, intersexes, indeterminates, and probably some phenotypic females would correspond to genetic males.
Twinning and conjoined placentation in mice
Authors: Wan Yu‐Jui , Wu Tsung‐Chieh , Damjanov Ivan 
Published: June 2005

AbstractSpontaneous and experimentally induced twinning and conjoined placentation were studied in Swiss‐Webster (SW) mice. Conjoined placentation was noticed at a rate of 0.4% for twins and 0.06% for triplets. Placentally conjoined embryos were either symmetrical or asymmetrical. A single spontaneous monozygotic conjoined twin was observed among 2,000 blastocysts cultured in vitro. The yield of twins could not be increased by manipulating explanted embryos in vitro, or by treating in utero during the early postimplantation stage of development with vincristine.
The photo‐gonadal response of a migratory bunting: Evidence of an external coincidence system
Authors: Prasad B. N. , Kumar Vinod , Tewary Reader P. D. 
Published: June 2005

AbstractMale redheaded buntings (Emberiza bruniceps) were subjected to continuous darkness (DD) or short days (8L/16D) after photo‐stimulation (15L/9D) for either 15 or 30 days. Two groups of birds (four each), after photo‐stimulation for 30 days, were continued on a regimen of 15L/9D. Another two groups (of four each) of photo‐sensitive birds were also subjected to DD or 8L/16D; they served as controls. The effect of transfer to DD or 8L/16D on the size of testes was found not be dependent upon the size attained at the time of transfer. The rate of testicular regression was nearly the same under both the treatments, i.e., in those birds transferred either to DD or to 8L/16D. The birds that were maintained on 15L/9D maintained enlarged testes; this excluded the possibility of the onset of photo‐refractoriness during the treatment period. On the other hand, testes were not photo‐stimulated in the photo‐sensitive birds subjected to DD or 8L/16D. These results are consistent with the Bünning‐Pittendrigh avian external coincidence model, but could be explained alternatively by a relatively simple internal coincidence model. Nevertheless, the application of the law of parsimony suggests the acceptance of the hypothesis of the external coincidence model.
Vagal control of pulmonary blood flow in Ambystoma mexicanum
Authors: De Saint‐Aubain M. L. 
Published: June 2005

AbstractThrough direct observations on Ambystoma mexicanum it is found that the pulmonary artery contracts during stimulation of the vagus nerve and during acetylcholine treatment. In addition, contraction of the artery is a response to lung deflation and also occurs when the vagus fibers from the lung wall are sectioned; lung inflation and atropine treatment produce dilatation of the artery. Hypercapnia and noradrenaline had no effect on pulmonary vasomotor tone. The constrictor is located between the ductus Botalli and the lung, where histological examination showed a concentrically arranged layer of smooth muscle cells. It is suggested that the vagus nerve contains afferent fibers from stretch receptors in the lung wall inhibiting the vasomotor tone in the pulmonary artery. It is further suggested that the pulmonary vasoconstrictor in A. mexicanum is homologous to the vasoconstrictor previously found in a similar location in anurans and reptiles.
Growth, differentiation, and function of the testes in the toad Bufo bufo bufo (L.), with special reference to regulatory capacities: Effects of unilateral castration, hypophysectomy, and excision of bidder's organs
Authors: Barker Jøorgensen C. , Billeter Elisabeth 
Published: June 2005

AbstractFunction and compensatory growth of the testis have been studied in male toads of varying ages, ranging from postmetamorphosis to adults. All experiments lasted 2 months, starting about September 1. Spermatogenesis was normal in sexually immature, 1‐year‐old toads. The fastest growing young toads developed secondary sex characteristics, the thumbpads, during the experiment. The data suggest that size is more influential than age in determining the onset of sexual maturation. But body size is not the only factor which influences sexual maturation. The growth response of the remaining testis to unilateral castration decreased with increasing age and size of the toads. Two months after operation the remaining testis had reached the size of two testes in the young toads, whereas the testis showed no significant compensatory growth in the adultsized toads, wether sexually immature or mature. Hypophysectomy reduced body growth in young toads and prevented a testicular growth response to unilateral castration. Young toads, but not adults, with excised Bidder's organs had larger testes than the control toads. In hypophysectomized, young toads spermatogenesis was still active 2 months after the operation.
Sexual differentiation in Pelmatohydra robusta. I. Response to a temperature change is dependent on the duration of an asexual period after hatching
Authors: Noda Koichi 
Published: June 2005

AbstractPelmatohydra robusta were cultured at 18°C in an asexual state for 1‐8 months after hatching and then transferred to 10°C to induce sexual differentiation. When hydra were transferred to the lower temperature within a few months after hatching, they required a much longer time for the formation of mature germ cells than did hydra transferred 6‐8 months after hatching. This indicates that the onset of budding in P. robusta is not always accompanied by sexual maturation. An asexual period of 6‐7 months was required for P. robusta to become sufficiently mature for sexual differentiation. During the asexual period, the growth required for sexual maturation progressed uniformly within a clone, regardless of the budding status of the individual polyps. This indicates that part (or all) of a clone is not rejuvenated by budding.
Mating‐type dependent cell pairing in Oxytricha hymenostoma. IV. Macronuclear DNA content
Authors: Banchetti Rosalba , Cetera Rosanna , Nobili Renzo , Ricci Nicolo , Seyfert Hans‐Martin 
Published: June 2005

AbstractThe cytophotometric study of vegetative cells of Oxytricha hymenostoma showed that the two complementary strains 295 and 301 differ from each other in their macronuclear DNA content: 902 arbitrary units (U) for 295 and 1365 U for 301.During paraconjugation, a phenomenon involving the total fusion of two complementary partners into a unique, new cellular entity, the macronuclear DNA content/pair does not change strikingly: for the first 3 hr, in fact, the macronuclear DNA content per pair ranges around 2250 U, such a value being very close to that of a 295 cell (902 U) plus that of a 301 cell (1365 U). Only at stages 6 and 7, an increase of the macronuclear DNA content occurs (+9%), which is likely to be due to anomalous replication bands. Finally, at stages 8 and 9, the macronuclear DNA content/pair progressively decreases, dropping to values as small as 2025 U, in spite of the apparently normal replication bands, passing through the macronuclear, soon before the first binary fission of the paraconjugant cell.
Amphotericin B and the elasmobranch rectal gland: Implications for the relationship between oxygen consumption and ion transport
Authors: Shuttleworth T. J. 
Published: June 2005

AbstractIn slices of the dogfish rectal gland, amphotericin B produced increases in oxygen consumption and ouabain binding similar to those produced by cyclic AMP, except that the increases induced by the latter were inhibited by furosemide whereas those resulting from the addition of amphotericin B were unaffected by the diuretic. Unlike cyclic AMP, however, amphotericin B failed to stimulate secretion by the isolated perfused gland. These results support the suggestion that the increases in ouabain binding and oxygen consumption produced by cyclic AMP result simply from an increased sodium entry into the cells, and as such can be mimicked by amphotericin B, whereas secretion rate itself depends on some additional, cyclic AMP‐induced process. The implications of this for determinations of the relationship between rates of oxygen consumption and ion transport are discussed.
A biochemical and morphological investigation of alkaline phosphatase and Ca+2‐ATPase during initial mineralization in chick embryonic tibia
Authors: Sandhu Harinder S. , Jande Sohan S. 
Published: June 2005

AbstractBiochemical analysis of the enzymes alkaline phosphatase and Ca+2‐ATPase in the membrane fraction obtained from chick embryonic tibias showed a positive correlation between the elevated activity of these two enzymes and the onset of mineralization. Histochemistry further showed an increased intensity of alkaline phosphatase at the time of the onset of mineralization. It seems that both of these enzymes are involved in the process of mineralization.
Glycogen, protein, and lipid content of green, aposymbiotic, and nonsymbiotic hydra during starvation
Authors: Cook Clayton B. , Kelty Marcia O. 
Published: June 2005

AbstractGlycogen and protein levels during starvation were determined for symbiotic and aposymbiotic Hydra viridis, and for a brown hydra, H. littoralis. Glycogen content in green hydra increased over a 2‐week period; this appears to be the first report of an animal which accumulates a food reserve during prolonged starvation. These hydra also retained a greater proportion of tissue protein than either of the other groups. Relative utilization of glycogen was similar in aposymbiotic and brown hydra, although initial glycogen stores of brown hydra were ten times larger. Aposymbionts had a proportionately higher rate of protein loss than brown hydra. Food reserves of starving green hydra are augmented by photosynthetic products of symbiotic algae, while starving brown hydra rely on large stores of all reserves, including lipids.
Suppression of male pronuclear movement in frog eggs by hydrostatic pressure and deuterium oxide yields androgenetic haploids
Authors: Briedis Andris , Elinson Richard P. 
Published: June 2005

AbstractThe disruptive effects of microtubule‐specific agents on pronuclear movement illustrate the requirement of an intact cytoskeletal system for movement. In this study, we investigated the effects of high hydrostatic pressure and deuterium oxide (D2O) on fertilized Rana pipiens eggs during the time of pronuclear migration. The eggs were either pulsed for six min with 3000, 5000, or 7000 psi or placed for ten min in 80% D2O between the time of second polar body emission and first cleavage. Both treatments disrupted male pronuclear migration as shown by eccentric first cleavage furrows. Treatment of eggs prior to pronuclear association resulted in haploid production. The androgenetic origin of the haploid embryos was demonstrated using morphological and isozymal markers produced by the cross Rana pipiens ♀ × Rana utricularia ♂. Eggs treated with D2O also yielded embryos with neural defects identical to those following ultraviolet irradiation. This study complements the recent reports on pressure‐suppression of the second polar body and of first cleavage by showing that the selective suppression of microtubular function between these two events produces an entirely different set of genetic and developmental consequences.
Nonuniform distribution of enzymes in fish eggs
Authors: Klyachko Olga S. , Korzh Vladimir P. , Gorgolyuk Sofia I. , Timofeev Andrei V. , Neyfakh Alexander A. 
Published: June 2005

AbstractThe distribution of enzymes in the blastoderm and the yolk was investigated in the eggs of the bony fish, Misgurnus fossilis. The total activities of lactate dehydrogenase (LDH), glucose‐6‐phosphate dehydrogenase (G‐6‐PD), and aldolase (ALD) did not change during early development. However, the enzymes were redistributed in the egg: at the blastula stage the blastoderm contains about 60% of the total ALD activity and 80% of the total LDH and G‐6‐PD activities.The “free cytoplasm” volume, in which the enzymic proteins can be solubilized, is greater in the yolk than in the blastoderm. Low levels of homologous enzymes from other species injected into the egg are distributed between the blastoderm and the yolk in the same way as are the native enzymes; they are primarily localized in the blastoderm. Injected exogenous enzyme concentrates preferentially in the yolk, apparently being distributed proportionately with respect to the “free cytoplasm” volumes. The ratio of these “free cytoplasmic” volumes, determined by distribution of the injected enzyme (LDH), in the yolk and in the blastoderm is 6.8. On the basis of our results we propose that many egg enzymes are noncovalently bound to blastoderm structures, and that the “nonbound” fraction of the enzymes in the cytosol is distributed proportionally to the “free cytoplasm” volumes in the blastoderm and in the yolk.Fractionation of the subcellular constituents of blastoderm extracts by ultracentrifugation or by gel filtration on Sepharose in the presence of an excess of LDH reveals the high‐molecular weight LDH‐containing complexes. These complexes are absent in the yolk and in the unfertilized eggs. These results are consistent with the hypothesis that the binding of the enzyme to subcellular structures in the blastoderm is an important mechanism in ooplasmic segregation.
Cuticle ultrastructure with respect to the lipid waterproofing barrier
Authors: Hadley Neil F. 
Published: June 2005

AbstractLipids (waxes) deposited on or incorporated in the epicuticle provide an important waterproofing barrier in most terrestrial insects and arachnids. Although the chemical nature of these lipids is well documented, ultra‐structural evidence for their association with specific cuticular layers and sublayers is less conclusive. Difficulties here include relating layers observed with the electron microscope with layers seen under light microscopy, plus the fact that much lipid is removed in normal preparative procedures for electron microscopy. Moreover, epicuticular layers which presumably are lipid‐rich are often resistant to organic solvents. The latter suggests that if lipid is present, much of it is bound, possibly to protein. Preliminary studies using new techniques such as myrcene partitioning and freeze‐fracture microscopy which improve lipid rétention and visualization have yielded some promising results. Scanning electron microscopy of surface waxes, in contrast, has revealed complex lipid accumulations which can be altered or removed by appropriate organic solvents. Surface waxes no doubt supplement lipids associated with epicuticular layers in restricting water loss, with the effectiveness of the former being dependent upon their thickness, physical structure and arrangement, and their chemical composition. Pore and wax canals are likely the major routes via which lipids are transported from sites of synthesis to the epicuticle, but the exact mechanisms involved must still be resolved.
A new system for concurrent measurement of respiration and water loss in arthropods
Authors: Quinlan Michael C. , Hadley Neil F. 
Published: June 2005

AbstractA new, flow‐through system for the concurrent measurement of water loss and CO2 production from arthropods is described. The system employs an Al2O3 sensor to measure the moisture content of the air stream, and an infrared gas analyzer to determine the CO2 content. The system responds rapidly, is accurate, and provides a continuous record of both variables at constant or increasing temperatures. Preliminary studies on the house cricket, Acheta domesticus, showed that water loss and V̇ were highly variable depending upon the activity of crickets and that water loss increased greatly as a result of oral and anal discharges of fluid. Occlusion of the mouth and anus (paraffin) reduced water loss and V̇ at 30°C by 82 and 46%, respectively. Strong correlations between V̇ and water loss were observed in crickets whose mouth and anus had been sealed, both in long‐term (3 hour) isothermal studies and under conditions of rapidly increasing temperature.
Physiological processes related to nitrogen excretion in cockroaches
Authors: Cochran Donald G. , Mullins Donald E. 
Published: June 2005

AbstractSeveral patterns of uric acid voiding exist among various cockroach species. The impact of dietary nitrogen levels on these patterns has now been examined. Blattella germanica, Supella longipalpa, and Latiblattella inornata do not void uric acid even when maintained on diets containing 10.6% nitrogen for up to 30 days. Two species of Nahublattella void some uric acid on that diet, but high mortality was observed by 15 days. Parcoblatta fulvescens voids increasing amounts of uric acid as formed pellets when dietary nitrogen is increased, and suffers no untoward effects. The partitioning of injected 14C‐purine (hypoxanthine) by Parcoblatta was shown to occur first by conversion to 14C‐uric acid. Thereafter, 14C is found in evolved 14CO2, feces, egg cases, and whole body. The partitioning of 14C is influenced by the level of dietary nitrogen available. On a nitrogen‐restricted diet, larger amounts of 14CO2 are evolved but little 14C occurs in the feces. When nitrogen is abundant, reduced amounts of 14CO2 are evolved and more 14C is voided with the feces. 14C‐containing compounds, including 14C‐uric acid, are incorporated into egg cases. Radiolabel remaining in the injected insects at the end of the experiment was also influenced by the dietary regime. These results are discussed in relation to the flow of uric acid through Parcoblatta and its utilization by this insect.
Novel uptake systems for atmospheric water vapor among insects
Authors: Rudolph Dieter , Knülle Willi 
Published: June 2005

AbstractUptake of water vapor from subsaturated atmospheres in the Psocodea is accomplished by an oral device. During uptake paired lingual sclerites of the ventral hypopharynx are brought into a typical absorbing position. Vapor condensation proceeds onto a fluid layer covering this surface. This fluid presumably originates from a pair of dorsal labial glands. The condensed vapor is transferred from the site of condensation to the entrace of the gut via a sclerotized tubule traversing the hypopharynx. Propulsion of the fluid is achieved by a cibarial sucking pump which operates intermittently. Below the critical equilibrium humidity (CEH) the fluid layer dries up, the salivarium is closed, and uptake of vapor ceases. Uptake of water vapor is a feature common to the whole order Psocoptera and is apparently not related to specific environmental conditions. Among the ectoparasitic descendants from the Psocopteran stock the absorbing system is preserved in both groups of the Mallophaga (Amblycera and Ischnocera); the faculty has, however, been lost independently by single species in both lines. In these species structural components of the uptake device are modified or reduced. The faculty appears to be completely absent in the Anoplura. The distribution of vapor uptake among the Phthiraptera is neither correlated with the type of host nor the mode of nutrition. The CEHs of the Mallophagans (43 to 52% relative humidity: R. H.) are markedly lower than those of the Psocoptera (58 to 85% R. H.). The uptake rates of most Mallophagans are extraordinarily high. A novel case of anal vapor uptake is reported in flea larvae and a preliminary account of rectal structures, possibly involved in vapor uptake, is given.
Physiological and psychophysical spectral sensitivities of the cichlid fish, Hemichromis bimaculatus
Authors: Bell David M. 
Published: June 2005

AbstractElectrophysiological and psychophysical spectral sensitivities of the teleost Hemichromis bimaculatus (Pisces; Cichlidae) were determined by measurement of electroretinogram b‐wave magnitude and optomotor response threshold. The physiological and behavioral curves exhibit trivariance and trichromacy, respectively, with peaks occurring in the 460–478, 546, and 623–646 nm spectral regions. A 20‐nm shift to the red is seen in the physiological curves upon strong light adaptation, accompanied by an order of magnitude decline in overall sensitivity. Photopic physiological and behavioral sensitivities correspond in sensitivity, but differ in dominant peaks, with the red and green spectral sensitivities dominating the respective curves. The common spectral peaks correspond with suspected vertebrate photopigments, correlate with the visually oriented nuptial and parental behaviors of the cichlids, and imply cone dominance in the retina of this teleost.
Photoperiodic regulation of the gonadal recrudescence in common Indian Rosefinch: Dependence on circadian rhythms
Authors: Kumar Vinod , Tewary P. D. 
Published: June 2005

AbstractMale Rosefinches, previously treated with short days (8L: 16D), were held under six different light regimes (resonance light cycles) in which a main 6‐hr photophase was combined with varying durations of scotophases (6L/6(2n + l)D)L, light phase; D, dark phase; n, number of multiples of 6D.
; one group was also placed under long days (15L:9D) which served as control. Birds placed under long days as well as 6L:6D, 6L:30D, 6L:54D showed complete gonadal growthand development, while birds under 6L:18D, 6L:42D, 6L:66D showed no testicular growth and behaved as if they had been exposed to short days. These results are consistent with the Bünning hypothesis and indicate that the photoperiodic time measurement in Common Indian Rosefinches (Carpodacus erythrinus) involves an endogenous rhythm of approximately 24 hr in duration.