bluuebunny/crossref_metadata_2025_split huggingface dataset:
Behavioral thermoregulation by the white rat at high ambient temperatures
Authors: Clark Richard V. 
Published: June 2005

AbstractAt ambient temperatures greater than 40°C, rats must spread salvia on themselves to prevent lethal hyperthermia. This study examined the effect of other behavioral parameters on a rat's ability to thermoregulate. The animals were exposed to 42°C in a cylindrical wire cage; records of time spent saliva spreading and moving about the cage were made; and body temperatures were measured with thermocouples implanted in the animals' abdominal cavities. Very little time spent saliva spreading was necessary for an animal to become thoroughly wetted on its ventral surface. Once wetted, an animal's thermoregulatory ability depended on its amount of locomotion. Animals which spent a considerable amount of time climbing about the cage were unable to stabilize their body temperatures and suffered increasing hyperthermia. Those which had low levels of locomotion were able to hold a constant body temperature for an hour or more. Several of the animals were given seven successive exposures to 40°C, followed by a second exposure to 42°C. Most of these animals showed greatly improved thermoregulatory abilities in the second exposure at 42°C as compared with the first, and this improvement was associated with markedly decreased locomotion. Several animals showed increased saliva spreading, but this change was not well correlated with improved thermoregulatory ability. It was concluded that low levels of locomotion are essential for evaporative cooling by saliva spreading to be adequate, and that repeated exposures to heat can modify an animal's behavior to the type associated with prolonged thermoregulation.
Seasonal effects of hyper‐osmotic sodium chloride on urea production in the frog, Rana pipiens
Authors: Jungreis Arthur M. 
Published: June 2005

Abstract
Spring‐summer frogs, Rana pipiens, acclimated at 22.5°C or 27°C were dehydrated in 0.15 M NaCl for up to 24 hours. After 10 or 24 hours of treatment, the concentration of urea in serum increases relative to the concentrations of urea measured in serum of frogs kept in tap water or 0.125 M NaCl.
The increase in the concentration of urea in serum of spring‐summer frogs was associated with an increase in body urea and an increased rate of urea production.
When fall‐winter frogs, acclimated at 20°C, were dehydrated in 0.15 M NaCl for 12.5 hours, no increase in the concentration of urea in serum was observed, relative to frogs treated with tap water or 0.125 M NaCl. After 48 hours, the concentration of urea in serum of frogs treated with 0.15 M or 0.125 M NaCl was the same, but both were significantly greater than tap water treated frogs.
The metabolic basis for the increase in the rate of urea production observed in spring‐summer but not fall‐winter frogs in response to hyperosmotic sodium chloride is discussed.
Bearing of genetic data on the interpretation of the subunit structure of octanol dehydrogenase of Drosophila
Authors: Ogonji Gilbert Odhiambo 
Published: June 2005

AbstractGenetic analysis of A, B, and B′ octanol dehydrogenase isozyme variants extracted from five geographic strains of Drosophila albirostris isozyme variants shows that these are distinguished by multiple alleles at one locus. A comparison of isozyme patterns of single fly and mass homogenates of true breeding variants and of their hybrids suggests that the difference in the variants are due to a regulatory locus. A tetrameric enzymatic structure, stemming from the activity of two structural genes, can account for the isozymes found in electrophoretic positions 3 to 7.
Regulation in grafts of partially dissociated and reaggregated portions of Fundulus embryonic shields
Authors: Oppenheimer Jane M. 
Published: June 2005

AbstractPortions of Fundulus embryonic shields, usually posterior or anterior halves, were partially dissociated into cell clumps and separate cells by exposure to salt solution lacking magnesium and calcium ions; the dissociates were reaggregated in salt solution containing these ions, then immediately grafted to extraembryonic regions of host gastrulae. Technical difficulties prevented complete dissociation of the shield portions and complete retrieval of the dissociates, but a number of hosts bearing secondary complexes differentiated in association with the grafts developed successfully to late stages.Complexes associated with grafts derived from posterior shield portions frequently formed tails, and differentiated, with few exceptions, the same range of structures described earlier as having differentiated when either unfragmented or mechanically minced shield portions were grafted. In the parts of the new graft complexes remaining attached to the yolksac epithelium, the secondary structures formed were often in topographic disarray, but in the free tails that grew out from these complexes, the axial structures frequently attained normal topographic relationships.Complexes associated with grafts derived from anterior shield portions frequently formed, among other structures, highly differentiated eyes, often with normal retinal stratification, sometimes accompanied by lens, cornea, iris, or optic nerve.The high degree of organization of tails developing in association with grafts of posterior origin, and of eyes in association with grafts of anterior origin, is possibly explicable not by cellular self‐sorting and self‐assembly, but rather by embryonic field phenomena.
DNA base sequence heterogeneity in the order galliformes
Authors: Schultz Gilbert A. , Church Robert B. 
Published: June 2005

AbstractNucleotide substitution that has occurred in the repeated DNA base sequences of several species of galliformes since their origin has been investigated by DNA/DNA hybridization. The results of competition experiments and the thermal stabilities of interspecific DNA/DNA hybrids indicate that a considerable amount of base substitution has occurred between species within the Family Phasianidae. A specific group of genes, the ribosomal RNA cistrons, have been found to be conserved relative to the average DNA base sequences. Gallus domesticus DNA shows considerable base sequence heterogeneity with respect to Phasianus colchicus DNA and is about as divergent from the other members of the Family Phasianidae as are some species outside the family.
Activity and localization of acid hydrolases in the dorsal tail fin of Rana pipiens during metamorphosis
Authors: Greenfield Phyllis , Derby A. 
Published: June 2005

AbstractThe specific and total activities of acid phosphatase (AcP), hyaluronidase (HU), β‐N‐acetylglucosaminidase (NAG) and lactate dehydrogenase (LDH) of tail fin are constant during prometamorphosis. During climax, as the fin is resorbed, the activities of the hydrolases increase while the specific activity of LDH remains constant and the total activity decreases. The apparent Km and pH optimum of the hydrolases are the same at prometamorphosis and climax. Similar changes in enzyme activities are found in pieces of prometamorphic fin induced to resorb in vitro by thyroxine treatment. AcP, NAG and LDH are found, but in different proportions, in both fragments of prometamorphic fins separated into epidermis and mesenchymal core. NAG and LDH are more concentrated in the epidermis while AcP is more concentrated in the core. A higher percentage of NAG and AcP activity is found in the mitochondrial‐lysosomal and supernatant subcellular fractions at climax than at prometamorphosis. In addition, the specific activities of these enzymes are higher in the mitochondrial‐lysosomal and supernatant fractions at climax while the specific activity and subcellular distribution of LDH is constant. The increase in activity of the hydrolases of the fin which occurs in synchrony with resorption during spontaneous metamorphosis or that induced in vitro by thyroxine suggests that these events are related and that the hydrolases are concerned with the degradation of the connective tissues of the fin during regression.
Local action of thyroxine on amphibian metamorphosis. V. Cell division in the eye of anuran larvae effected by thyroxine‐cholesterol implants
Authors: Kaltenbach Jane Couffer , Hobbs Ann Witherell 
Published: June 2005

AbstractTo determine whether or not thyroxine stimulates cell division in the tadpole eye by acting directly upon ocular tissues, thyroxine‐cholesterol and cholesterol control pellets were implanted into the vitreous chambers on opposite sides of young Rana larvae. From 1 to 20 days later some of the larvae were exposed to tritiated thymidine. Scintillation counting indicated more radioactivity in the thyroxine‐treated eyes than in the contralateral control eyes, and radioautography showed that it was located in nuclei in the ora serrata of the retina and in the epithelia of the lens and cornea. Mitotic figures were found in similar locations in the eyes of tadpoles fixed at five day intervals, up to 45 days after pellet implantation; striking increases in mitotic activity were induced in the eyes containing thyroxine implants. As long as 35 days post implantation there was little, if any, advancement of metamorphic changes in other regions of the tadpoles including such structures as the hind limbs and the control eyes; even development of accessory ocular structures near the thyroxine‐treated eyes (such as eyelids, nictitating membrane and extrinsic ocular muscles) was not enhanced. The precocious unilateral stimulation of cell division in the retina, lens, and cornea of eyes containing thyroxine implants indicates a direct, local action of thyroxine upon ocular tissues. This suggests that during normal metamorphosis cell division in the eye is probably brought about by the direct, peripheral action of thyroid hormone.
Sperm penetration through zona pellucida and perivitelline space in the hamster
Authors: Yang W. H. , Lin L. L. , Wang J. R. , Chang M. C. 
Published: June 2005

AbstractSperm penetration through zona pellucida was observed in tubal fluid containing eggs and spermatozoa, which had been recovered under a layer of paraffin oil previously insufflated with a mixture of 5% CO2 and 95% air and warmed to 38°C before each experiment. A Nikon F 35 mm camera and a Bolex Rex‐5 16 mm movie camera, synchronized with Xenon‐gas flash epuipment, were used with a microscope for recording this fast‐occurring phenomenon. In golden hamsters, 284, 306, 312 and 293 tubal eggs were recovered in paraffin oil after 4, 4.5, 5 and 5.5 hours, respectively, following delayed mating; 1, 11, 13 and 8 eggs were observed to be either attached or approached by spermatozoa, of which 1, 9, 10 and 1 eggs respectively were subsequently penetrated by the spermatozoa. The change in the CO2 tension of the paraffin oil had no apparent effect on the incidence of in vitro fertilization. Nevertheless, either the containment of eggs and spermatozoa in the small space between a cover slip and glass slide, or the dilution of tubal fluid with the liquid medium of 0.1 ml hamster serum and 0.4 ml CDM 199 was detrimental to the in vitro environment of fertilization. As in a previous investigation, most spermatozoa penetrated obliquely through the zona pellucida, but very few spermatozoa penetrated directly through it. The duration of time for spermatozoa to traverse the zona pellucida varied from about 4 to 22 minutes. Although almost all tubal eggs were completely penetrated as a result of fertilization in the oviduct of golden hamsters, yet a rather high percentage, 36%, of spermatozoa penetrated incompletely through the zona pellucida in vitro. Following sperm penetration through the zona pellucida, the vibration of ooplasm was initially induced by the impact of the two gametes, and then the rotation of ooplasm was subsequently caused by the migration of spermatozoa in the perivitelline space. Nearly 40 hamster eggs were observed and photographed in vitro during the process of fertilization, the largest number of mammalian fertilizations yet reported.
The passage of extracellular tracers through the follicular epithelium of lizard ovaries
Authors: Neaves William B. 
Published: June 2005

AbstractLanthanum, a tracer of extracellular space in fixed tissue, readily traverses the follicular epithelium of the lizard Anolis carolinensis. Saccharated iron oxide injected into living lizards and peroxidase administered in vitro pass through the extracellular spaces of the follicular epithelium and accumulate in the zona pellucida. Micropinocytotic uptake of iron and peroxidase by the oocyte occurs in larger follicles which show signs of yolk accumulation. These findings confirm the morphological absence of sealing junctions in the follicular epithelium and demonstrate an extracellular route whereby materials carried in the circulation may reach the oocyte without passing through the cytoplasm of follicular cells.
Distribution of the cytoplasmic activity inducing germinal vesicle breakdown in frog oocytes
Authors: Masui Yoshio 
Published: June 2005

AbstractFull‐grown oocytes of Rana pipiens were dissected out of the follicles and induced to undergo germinal vesicle breakdown (GVBD) in vitro by progesterone treatment. When the progesterone treatment was carried out after displacing the germinal vesicle (GV) from the animal half to the vegetal half by centrifugation (200–400 × G for 10 minutes), a considerable delay of GVBD took place although all the GVs eventually broke down. GVs displaced near the vegetal pole frequently migrated towards the animal pole and gave off a polar body in the equatorial zone of the oocyte. When an oocyte was tightly constricted along the equatorial line with thread so that the migration of the GV was prevented, the frequency with which the GV broke down in the vegetal half was considerably decreased depending on the tightness of constriction. The ooplasm in the animal and vegetal halves of the progesterone‐treated oocytes was tested for GVBD inducing activity by injecting it into untreated oocytes which contain an intact GV. It was found that the ooplasm from the vegetal half induced GVBD in the recipients with a lower frequency than that from the animal half. To localize the GVBD inducing activity in the ooplasm, oocytes were centrifuged after progesterone treatment at the interface between Ringer's solution and Ficoll solution. The GVBD inducing activity of the ooplasm of the animal pole was increased after removal of yolk and pigment granules by a brief centrifugation (4000 × G for 5–10 minutes). Prolonged centrifugation (4000 × G for 2 hours) brought about stratification of the ooplasm. From the centripetal to the centrifugal side, five layers were distinguished: oil cap, fluid hyaline ooplasm, gelatinous hyaline ooplasm, pigment granules and yolk. The highest activity of GVBD induction was found in the hyaline ooplasm. Based on these results, a mechanism of the GVBD induction in the frog oocyte is discussed.
Changes in macromolecular synthesis in Triturus presumptive epidermis stimulated by inducing agent
Authors: Imoh Hiroshi , Sasaki Naoi , Kawakami Izumi , Hayashi Hirofumi 
Published: June 2005

AbstractSyntheses of macromolecules, DNA, RNA, and protein, were studied in isolated presumptive epidermis of Triturus gastrulae using radio active carbon dioxide as tracer.The explants cultured in the absence of inducing agents synthesized DNA, RNA, and protein for at least three days after explantation. Throughout the three days, DNA synthesis continued at an almost constant rate and patterns of newly synthesized proteins fractionated on polyacrylamide gel electrophoresis were similar. Activation of ribosomal RNA synthesis was observed to occur during culture. These facts suggest that, in the explants cultured in the absence of inducing agents, cell multiplication continued and the set of proteins synthesized changed little over a three‐day period.In the explants in which structures were induced by rat liver homogenate, syntheses of macromolecules differed from those in the control in some respects. There was a peak of active DNA synthesis around ten hours after induction treatment, and the phase of DNA synthesis was followed by active RNA synthesis. After three days of induction the pattern of newly synthesized proteins obtained by gel electrophoresis differed greatly from that seen earlier in the induction process and from that of controls.
Developmental biology of annual fishes. I. Stages in the normal development of Austrofundulus myersi Dahl
Authors: Wourms John P. 
Published: June 2005

AbstractComparative studies of annual fish development reveal a unique developmental pattern in which embryogenesis occurs within a reaggregated mass of previously dispersed cells. The normal development of Austrofundulus myersi Dahl, a representative annual fish, has been divided into 46 stages. Cleavage during Stages 1–11 produces a typical teleost blastula. At Stage 12 (a flat, hollow blastula), the blastomeres segregate into two populations. One population composed of deep blastomeres will disperse as amoeboid cells, while the other, an hemispherical shell of outer blastomeres, flattens to form the enveloping cell layer. The cells of the enveloping cell layer become multinucleate and the layer functions as an extra‐embryonic membrane which is shed at hatching. When epiboly commences (Stage 14), the deep blastomeres come together as a consolidated mass and then migrate outward as individual amoeboid cells into the space formed between the expanding enveloping cell layer and periblast. When epiboly is concluded (Stage 19), the deep blastomeres have completely dispersed over the surface of the periblast. The dispersed phase usually lasts for several days. Prior to epiboly and during the dispersed phase, no germ ring, embryonic shield, or axial organization is present. The dispersed cells come together to form a definitive aggregate (Stage 22) by day 4. Embryogenesis within the reaggregated mass of previously, dispersed cells produces a typical teleost embryo. The definitive embryonic axis and solid neural keel appear by Stage 28 (day 10). Growth and organogenesis proceeds and hatching occurs at Stage 44. Development through Stage 44 requires 39–40 days in non‐diapausing eggs. Eggs of A. myersi may enter diapause at three distinct stages: (1) dispersed cell phase; (2) long somite embryo; and (3) late pre‐hatching.
Physiological effects of trypan blue on chick embryos
Authors: Hoffman David J. , Ramm Gordon M. 
Published: June 2005

AbstractTen‐day chick embryos (1) received yolk sac injections of 0.1 ml of 1.5% trypan blue in sterile saline, (2) received 0.1 ml of sterile saline or (3) were handled and returned to the incubator and examined five hours later. Trypan blue treated embryos exhibited decreased survival rate and significant decreases in plasma glucose, chloride, CO2 content and blood pH. Plasma potassium and embryonic wet weight were significantly elevated, but little change occurred in plasma sodium or hematocrit. Embryos frequently exhibited hemorrhaging after treatment. Saline treatment caused a small but significant decrease in plasma chloride and only a slight decrease in survival rate.The immediate response to trypan blue was markedly similar to that of hypoxia, presenting additional evidence in support of the view that trypan blue may interfere with the normal oxygen consumption of the embryo.
An ultrastructural study of strobilation in Chrysaora quinquecirrha with special reference to neurosecretion
Authors: Crawford Marsha A. , Webb Kenneth L. 
Published: June 2005

AbstractScyphistomae and strobilae of the scyphozoan Chrysaora quinquecirrha were fixed and sectioned for electron microscopy. The polyps were divided into four classes on the basis of their stage of development: non‐strobilating (scyphistomae), neck‐formation, segmentation, and metamorphosis. Ultrastructural preparations revealed neurosecretory cells containing numerous membrane‐bounded granules in scyphistomae and necked polyps. At the time of neck‐formation the neurosecretory granules were mpst concentrated in the cell body and at segmentation, most concentrated in the axons of the neurites. By metamorphosis most of the neurosecretory product had disappeared from the axons. Other changes which appear to accompany strobilation included both a decrease in glycogen and contraction of muscles along the inner edge of the epidermis.
The relationship of gonadogenesis, molting and growth during postembryonic development of the free‐living nematode, Panagrellus silusiae: Selective inhibition of gonadogenesis using hydroxyurea
Authors: Westgarth‐Taylor B. , Pasternak J. 
Published: June 2005

AbstractDuring postembryonic development of the free‐living nematode, Panagrellus silusiae, there are three diverse developmental processes: growth, molting and gonadogenesis. By treating synchronously growing worms with hydroxyurea at various times during the postpartum period it was possible to induce selective blockage of gonad formation without interfering appreciably with the temporal patterns of growth or molting. Gonad formation was differentially susceptible to hydroxyurea treatment. The presence of the drug during the early phases of gonadogenesis prevented completion of the process while administration later in the postpartum cycle was without effect.Long term treatment with hydroxyurea caused cuticular anomalies in adult
worms after the final molt had been completed.Treatment with puromycin, actidione, actinomycin D, cold or removal of
nutrients during the early stages of postpartum development reversibly blocked
postembryonic development. Nitrosoguanidine blocked postembryonic develop
ment irreversibly.The results suggest that gonad development is not obligatory for growth or
molting but continued body growth and molting are essential for gonado
genesis. It was not possible to divorce the molting process from body growth.
Pituitary‐adrenal interaction and growth of the embryonic avian adrenal gland
Authors: Girouard R. J. , Hall B. K. 
Published: June 2005

AbstractPossible interactions between the anterior pituitary and the adrenal gland in the embryonic chick were investigated. Hypophysectomy by partial decapitation, and treatment of embryos with dexamethasone phosphate (a potent corticosteroid) both significantly reduced the growth of the adrenal gland, indicating a dependence of the adrenal gland on the pituitary for normal growth and the potential for negative feedback between the adrenal and the pituitary.The hyperplasia of the host adrenal gland known to follow injection of
homogenates of adrenal glands was inhibited when homogenates were injected
into embryos whose ACTH production had been inhibited by dexamethasone.
It was concluded that the response of the embryonic adrenal gland to growth
stimulating agents was mediated via the anterior pituitary.