bluuebunny/crossref_metadata_2025_split huggingface dataset:
Salt and water balance and antennal gland function in three pacific species of terrestrial crab (Gecarcoidea lalandii, Cardisoma carnifex, Birgus latro). II. The effects of desiccation
Authors: Harris R. R. , Kormanik Gregg A. 
Published: June 2005

AbstractThe rates of body water loss and the maximum tolerable losses in the three Indo‐Pacific species of land crab (Gecarcoidea lalandii, Cardisoma carnifex and Birgus latro) were similar to those of other terrestrial decapod crustaceans of marine origin. During dehydration, the haemolymph osmolalities and Na and Cl concentrations increased in all species; and in Gecarcoidea and Cardisoma, corresponding increase in urine concentrations were found. Thus the U/B ratios of all three parameters did not change significantly from those of hydrated animals. As in other crabs, a urine hyperosmotic to the haemolymph was not produced during desiccation.Clearance of the filtration marker inulin from the haemolymph ceased in these two species, so reduced urine production is suggested to be an important mechanism in limiting water loss. No post‐filtration withdrawal of fluid from the antennal gland, which would be indicated by an increase in inulin U/B ration to in excess of unity, appeared to take place under these conditions.During desiccation the extracellular solute volume in Gecarcoidea and Cardisoma remained relatively constant, in contrast to Birgus, where a significant decrease in volume, equivalent the volume of body water lost, occurred. This suggests that in Birgus the intracellular volume is conserved. The consequence of this in Birgus the intracellular volume decrease on the measurement of clearance rates is discussed. It is suggested, from indirect evidence, that in Birgus the antennal gland continued to produce urine during desiccation.The increases in haemolymph solute concentrations, while the extracellular spaces remain unchanged, requires a net movement of solutes into the haemolymph in Gecarcoidea and Cardisoma. In Birgus the increase in haemolymph concentration is less than would be expected if it was inversely proportional to the decrease in extracellular volume, implying some removal of solutes from this compartment.
The energy metabolism of the leech Hirudo medicinalis in anoxia and muscular work
Authors: Zebe E. , Salge U. , Wiemann C. , Wilps H. 
Published: June 2005

AbstractThe medical leech Hirudo medicinalis has only small reserves of glycogen (˜ 40 μmol/g fresh weight), but malate is present in comparatively high concentrations (8 to 10 μmol/gm fresh weight) in the tissues and in the blood. Leeches are able to survive several days of anoxia at 20°C. From the onset of anoxia the level of malate drops rapidly and concomitantly the concentration of succinate rises in converse manner. After the initial phase, both metabolites do not change significantly. Then large quantities of propionate accumulate which, in part, are also excreted into the surrounding water. In contrast, continuous swimming causes the concentration of lactate to rise steeply and lactate is the dominant end product. There is only a modest decrease in the concentration of malate whereas succinate does not change. These distinct patterns of metabolite concentrations arising in anoxia and in muscular activity seem to indicate that different modes of energy metabolism are used in both situations.
An acrosome reaction in natantian sperm
Authors: Clark Wallis H. , Kleve Maurice G. , Yudin Ashley I. 
Published: June 2005

AbstractSperm of the natantian Sicyonia ingentis are highly polarized with a conical cap and single spike extending from a spherical main body. The acrosome consists of a spiraled spike and two glycoprotein cap components: the anterior granule and the membrane pouches. During sperm‐egg interaction, the spike is lost and the cap membrane folds back, exposing the two glycoprotein acrosomal components. At this point, the anterior granule lies directly adjacent to the oolemma and has replaced the spike as the anterior end of the sperm. Treatment of sperm with ionophore A23187 initiates the acrosome reaction, thereby facilitating the experimental sequencing of the reaction. The ionophore‐induced reaction begins with the spike's loss of its spiraled nature, the appearance of filaments in the spike core, and the immediate depolymerization of the spike into a granular mass. As the spike retracts, the membrane pouches swell. The cap membrane in the area of the retracted spike ruptures and begins to fold back. As seen during natural sperm‐egg interaction, the anterior granule becomes the new anterior end of the sperm after loss of the spike. Several known artificial activators of sperm were tested, but only the divalent cation ionophore A23187 successfully induced the acrosome reaction. The use of artificial seawater with different ionic properties showed that the acrosome reaction is dependent on the influx of Ca++ ions.
Microsphere studies of amphibian systemic blood flow redistribution during dehydration, hypovolemia, and salt load
Authors: Hillman Stanley S. , Sommerfeldt R. W. 
Published: June 2005

AbstractSystemic blood flow distribution was monitored in a variety of anuran amphibians using trapping of 54‐μm mean radionuclide‐labeled micro‐spheres during control, dehydration, hypovolemia, and salt load treatments. The head was the only region which showed significant increases in its proportion of systemic blood distribution in both dehydration and hypovolemia relative to controls. Proportionate declines in blood flow were observed to skeletal muscle regions during dehydration and hypovolemia. Salt loading had no effect on blood flow distribution. The redistribution results are consistent with sympathetic reflex control during hypovolemia and dehydration. The magnitude of the cerebral redistribution did not correlate with a species' tolerance to dehydration.
The epidermal melanocyte population in the skin of ultraviolet‐irradiated crested newt
Authors: Losa Massimo , Zavanella Teresa , Milani Silvano 
Published: June 2005

AbstractThe response of the epidermal melanocyte population to repeated ultraviolet (UV) exposure (wavelength spectrum 275–350 nm) has been investigated in the crested newt, Triturus cristatus carnifex. The effects of different doses of UV light were studied. The animals were killed 7 months after the first UV exposure. Only a slight decrease in the number of pigment cells was found after 85 sequential irradiations with a total dose of 1.3 × 105 J/m2, whereas striking decreases were observed when the same total dose was fractionated into 14 exposures or when a double dose was given in 57 exposures. The relationship between the square roots of the epidermal melanocyte densities and single doses appeared to be roughly linear, at least over the range of doses administered. The main factor in melanocyte damage seemed to be the single dose of irradiation rather than the cumulative dose administered. Decreased melanin content of the keratinocytes was observed in most irradiated animals.
The spatial pattern of RNA in fully grown oocytes of an amphibian, Xenopus laevis
Authors: Capco David G. 
Published: June 2005

AbstractThe possibility that maternal RNA may be localized in specific oocyte regions was examined in fully grown oocytes of Xenopus laevis. These oocytes were subdivided into six regions perpendicular to their animal‐vegetal axis. Each region was analyzed to determine the amount of total cellular RNA, poly(A)+RNA, and newly synthesized ribosomal RNA. As would be expected from current evidence, total cellular RNA was found to exist in a gradient‐like fashion, highest at the animal pole and lowest at the vegetal pole. However, poly(A)+RNA and newly synthesized ribosomal RNA had significantly different spatial patterns from each other and from total cellular RNA. In addition, evidence suggests that newly synthesized ribosomal RNA requires two to three days before it is uniformly distributed within the oocyte. These results suggest that a mechanism may exist to create different spatial patterns for different classes of RNA.
The role of the blood in the temperature dependence of oxidative metabolism in decapod crustaceans. I. Intraspecific responses to seasonal differences in temperature
Authors: Mauro Nicholas A. , Mangum Charlotte P. 
Published: June 2005

AbstractTotal oxygen uptake in the blue crab Callinectes sapidus doubles with a rise in ambient temperature in the range 15–25°C, and increases precipitously (Q10=4.92) in the range 5–15°C. Both systemic and cellular phenomena are responsible for the pattern. At summer temperatures, where motor activities are maximal, the oxygen affinity of blue crab hemocyanin is low, and considerable volumes of oxygen are delivered to the tissues. At winter temperatures, where feeding and locomotion virtually cease, the hemocyanin‐oxygen (HcO2) affinity is so high that little oxygen can be extracted by the tissue and O2 is transported entirely in the free form. At the transitional temperature of 15°C, a seasonal acclimation of HcO2 affinity permits appreciable oxygen delivery to the tissues in the spring, but curtails oxygen delivery in the fall.Both muscle and hepatopancreas utilize the hexose monophosphate shunt (HMS) in carbohydrate metabolism. Specific activities of the enzymes participating in the HMS are greater in hepatopancreas than muscle, and the sensitivity of O2 uptake to the glycolytic inhibitor iodoacetate (10−2 M) is smaller. The temperature dependence of O2 uptake in the range 15–25°C is much smaller in hepatopancreas than in muscle. The ratio of C‐1/C‐6 labeled glucose utilization indicates that, at low temperature, the activity of the HMS in hepatopancreas is five times greater than that of glycolysis. Thus, the low thermal sensitivity of O2 uptake in hepatopancreas appears to be due to a change in the relative contribution of the two pathways to total carbohydrate metabolism.There is no evidence of a compensatory response of intermediary metabolism in muscle, which comprises the major fraction of total biomass. The thermal dependence of O2 uptake by the animal exceeds that of either hepatopancreas or muscle, due to the large increase in HcO2 affinity, and hence a decrease in tissue O2 supply, at low temperature.
The effect of neurogenic stimulation on the development and growth of bony tissues
Authors: Bubenik G. A. , Bubenik A. B. , Stevens E. D. , Binnington A. G. 
Published: June 2005

AbstractIn order to elucidate the mechanisms of neurogenic control of bone devlopment and growth, the effects of traumatic and electric stimulation on the development, size, and shape of antler bone tissue were investigates. Unilateral growth of antler in a female deer was initiated after traumatic stimulation of the frontal bone. Electrical stimulation of antler nerves or antler periosteum resulted in an increase in more than 70% in antler length and over 40% in weight. Stimulation of antler nerves also resulted in abnormal shape of antlers. The role of periosteal nerves and the participation of the central nervous system in the responses to stimulation is discussed.
Evidence that secondary neurulation occurs autonomously in the chick embryo
Authors: Costanzo Renée , Watterson Ray L. , Schoenwolf Gary C. 
Published: June 2005

AbstractOther investigations have demonstrated that pressure, exerted by fluid contained within the lumen of the closed neural tube, plays an important role in the morphogenesis of cranial regions of chick embryos. In this study, we investigated whether this pressure is involved also in the formation of the secondary portion of the neural tube‐the portion formed by canalization of a solid mass of cells. To determine this, the posterior neuropore was prevented from closing (resulting in myeloschisis localized to the lumbosacral region) by removing the portion of the vitelline membrane covering the embryo, and reincubating for various periods. Secondary neurulation occurred normally in embryos exhibiting lumbosacral myeloschisis, demonstrating that this process occurs autonomously in chick embryos. Additional experimental studies are needed to ascertain what specific mechanisms cause the secondary portion of the neural tube to form.
RNA synthesis in immature mouse oocyte development
Authors: Fourcroy Jean L. 
Published: June 2005

AbstractOocyte development in several nonmammalian species is characterized by the synthesis of large quantities of ribonucleic acids during lampbrush stages of meiosis. These are stored in the oocyte and used during later oocyte maturation and early embryogenesis. This autoradiographic study examined the incorporation and persistence of ribonucleic acid in mouse oocytes during comparable stages of development. At each age examined, fetal through juvenile, the radiolabeled RNA precursors were incorporated into mouse oocytes during the growth stages. The RNAase‐digestible label appeared first over nucleoli and meiotic chromosomes, becoming cytoplasmic after 24 hours, and remaining cytoplasmic through all remaining stages. Once incorporated the label persisted during subsequent oocyte growth and maturation through preimplantation embryo stages with apparently undiminished levels. It is suggested that this persistently labeled RNA represents maternal RNA stored for use during early embryonic development.
Mice produced from eggs fertilized in vitro at a very low sperm:egg ratio
Authors: Thadani Vijay M. 
Published: June 2005

AbstractZone‐free mouse eggs were fertilized in vitro very small numbers of randomly selected sperm that had been capacitated in vitro (5–10 sperm per egg). The resulting embryos developed to the blastocyst stage in vitro, and gave rise to progeny after transfer to recipient foster mothers. Under similar conditions zone‐intact eggs were not fertilized. These data support the view that most sperm are genetically and physiologically competent to fertilize an egg, provided that they can gain access to its surface.
Cell allocation in preimplantation mouse chimeras
Authors: Spindle Akiko 
Published: June 2005

AbstractThe mechanism of cell allocation in the preimplantation mouse chimera was studied in aggregation chimeras of 4‐ and 8‐cell stage embryos. To follow the fate of cells, some embryos were labeled by a 16‐h incubation (at the 2‐cell stage) with 3H‐thymidine. At the 4‐8‐cell stage both labeled and unlabeled embryos were treated with pronase to remove the zona pellucida and then aggregated in various combinations: one labeled 8‐cell and three unlabeled 4‐cell embryos (labeled 8‐cell chimeras); one labeled 4‐cell and three unlabeled 8‐cell embryos or two labeled 4‐cell and two unlabeled 8‐cell embryos (labeled 4‐cell chimeras). Autoradiography of air‐dried preparations of inner cell masses isolated from the chimeras at the blastocyst or late blastocyst stage by immunosurgery revealed that labeled 8‐cell embryos contributed a disproportionately large number (over 60%) of their descendant cells to the inner cell mass of labeled 8‐cell chimeras. By contrast, in labeled 4‐cell chimeras only 8% (with one labeled 4‐cell embryo) or 31% (with two labeled 4‐cell embryos) of inner cell mass cells were derived from the labeled embryos. These results suggest that cell allocation in preimplantation mouse chimeras is not a random process and that cells of embryos developing ahead of others are preferentially allocated to the inner cell mass.
Pulmonary oxygen diffusing capacity of the lizard Tupinambis teguixin
Authors: Glass Mogens L. , Johansen Kjell 
Published: June 2005

AbstractPulmonary oxygen diffusing capacity (DLO2) and perfusion (Q̇L) have been measured by a rebreathing technique in the lizard Tupinambis teguixin at 25°C and 35°C. Both variables increased with temperature and at 35°C the values were Q̇L = 35 ml·kg−1·min−1; and DLO2 = 4.29 μmol·kg−1·min−1· Torr−1. These values are low compared to those for similar‐sized mammals or birds.
High levels of glutathione attained during postnatal development of rat testis
Authors: Calvin Harold I. , Turner Sheila I. 
Published: June 2005

AbstractThe concentration of glutathione (GSH) in rat testis increases approximately 3‐fold between 8 and 29 days of age, coinciding with the initial wave of meiosis, and is then maintained during spermiogenesis. In the adult rat, mM tissue GSH concentrations rank approximately as follows: liver > testis = kidney > caput epididymidis. However, with respect to protein content, relative GSH levels are testis = liver > kidney. In addition to its possible role during meiosis, the high concentration of GSH attained by developing germinal epithelium may be necessary for the biosynthesis and processing of sperm proteins containing SH and SeH.
Cinephotomicrographic observations on intracellular bubble formation in Tetrahymena
Authors: Hemmingsen Edvard A. 
Published: June 2005

AbstractA miniature cuvette pressure chamber for microscopy and highspeed (400 frames per second) cinephotographic recordings was developed to study intracellular bubble formation in Tetrahymena. The investigations show, for the first time, that intracellular bubble formation can occur, but only when the nitrogen gas supersaturations are higher than 150 atm. However, substantial fractions of the cell populations remain unaffected by exposures to gas supersaturations as high as 200 atm.
The presence of 17β‐hydroxysteroid dehydrogenase activity in preimplantation rat and mouse blastocysts
Authors: Wu Jung‐Tsung , Lin Guey‐Meei 
Published: June 2005

AbstractWhen Day 5 rat blastocysts and Day 4 and 5 mouse blastocysts were cultured in 53 μl of medium containing 1340 or 2680 pg [3H]estradiol (E2), large amounts of [3H]estrone (E1) were detected in the medium at daily intervals for up to 5 days. This indicates the presence of 17β‐hydroxysteroid dehydrogenase in the embryos. The activity was higher at a higher concentration of E2 and was also higher in mouse than in rat blastocysts. In the mouse, the activity was higher in Day 5 than Day 4 blastocysts during the first day in culture; then it decreased in Day 5 but increased in Day 4 blastocysts. The importance of E2 in embryonic development and implantation as suggested by others may be related to the activity of 17β‐hydroxysteroid dehydrogenase.
A novel pore system in the eggshells of the mallee fowl, Leipoa ocellata
Authors: Board Ron G. , Perrott Hugh R. , Love Glyn , Seymour Roger S. 
Published: June 2005

AbstractThe outer orifice of the funnel‐shaped pores in the eggshell of the mallee fowl, Leipoa ocellata, contain irregularly shaped pieces of crystalline material. The whole of the outer surface of the shell is covered with spheres containing amorphous calcium phosphate but little organic material. Thus they would not be expected to support microbial growth and they would not be corroded by organic acids produced by microorganisms in the incubation mounds.
A new method for the immobilisation of teleost embryos for time‐lapse studies of development
Authors: King Gillian M. , Gordon Richard , Karmali Karim , Biberman Leslie J. 
Published: June 2005

AbstractThe transparent embryo of the zebrafish (Brachydanio rerio) can be dechorionated mechanically and immobilised up to 2 weeks in 5% methylcellulose mucilage so that its development can be followed by time‐lapse cinematography. The developmental sequence parallels that of the chorionated or dechorionated free‐swimming controls except the yolk supply is used at a slower rate, which allows normal development to be followed past the stage when feeding presents a problem. Because of its high viscosity the methylcellulose mucilage changes shape slowly and can be manipulated as if it were a solid gel. The embryo can easily be removed by placing a drop of the mucilage containing it in water so that the mucilage softens and the embryo swims away. After a short period of adjustment the swimming and feeding behaviours are identical to those of controls. This immobilisation procedure enables time‐lapse movies to be made of the development of embryos or larvae that normally show locomotory behaviour. This may be a useful procedure for immobilisation of other embryos for developmental studies and as a test system for water pollutants and teratogens that cause abnormal development.
The blastocoelic fluid of sea urchin embryo induces exogastrulation
Authors: Ishihara Katsutoshi , Tonegawa Yasuto , Suyemitsu Takashi , Kubo Hideo 
Published: June 2005

AbstractThe exogastrula‐inducing activity of the blastocoelic fluid of sea urchin embryo was demonstrated by adding it to the culture medium of the late blastula stage. The active substance was separated by gel filtration and ultrafiltration, and its molecular weight was found to be in the range from 10,000 to 50,000. The activity was destroyed by trypsin and heat treatment. Since the treated embryos developed normally into pluteus larvae, except for the extrusion of archenteron toward the outside, the morphogenetic activity of the blastocoelic fluid was assumed to be exerted on the endoderm. Close examination of the exogastrulation process suggests that the evagination was due to some force pushing the endodermal plate toward the outside of the embryo.
Development of peroxisomes in amphibians. I. Cytochemical and biochemical studies on the small intestine
Authors: Dauca M. , Calvert R. , Menard D. , Hugon J. S. , Hourdry J. 
Published: June 2005

AbstractThe ontogeny of intestinal microperoxisomes was studied by cytochemical and biochemical methods during the development of two anuran amphibian species (Rana catesbeiana and Alytes obstetricans). The catalase activity was localized after incubation in DAB medium and studied biochemically by a spectrophotometric method. Microperoxisomes were found to be present in the intestinal epithelial cells of these amphibians. The primary enterocytes of aquatic larvae showed very few microperoxisomes. After metamorphosis the absorptive cells of the new secondary epithelium exhibited a drastically increased number of microperoxisomes per cell section. These organelles showed circular profiles and had a diameter ranging from 0.36 to 0.40 μm. The intestinal catalase activity was low in the tadpoles, increased steadily after metamorphosis, and peaked in the adults. Moreover, at eath developmental stage, the proximal segments always exhibited the highest catalase activity. The present study shows that the number of microperoxisomes as well as the catalase activity increases with the maturation of the intestinal epithelial cells in developing anuran amphibians.