bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biochemical aspects of conceptus–endometrial interactions
Authors: Bazer Fuller W. , Roberts R. Michael 
Published: June 2005

AbstractMammalian conceptuses must provide a chemical signal to the maternal system to insure maintenance of corpus luteum (CL) function and of progesterone production and continuation of uterine endometrial secretory activity. These events insure that the developing conceptus is provided with appropriate nutrients, regulatory enzymes and endocrine state allow successful establishment and maintenance of pregnancy. Pig blastocysts begin to produce estrogens by Day 11 of pregnancy, which prevents secretion of the uterine luteolytic factor (PGF2α) in an endocrine direction, but allows secretion in an exocrine direction, i.e., into the uterine lumen. Therefore, CL are “protected.” Blastocyst estrogens also trigger secretion of a group of proteins, including uteroferrin, an iron transport protein, and a family of protease inhibitors whose biosynthesis within the uterine glandular epithelium is under the control of progesterone. Estrogen also appears to promote accumulation of glucose and fructose within the uterine lumen. A complex in vivo “culture medium” is thereby established to promote conceptus development. Pig blastocysts do not undergo invasive implantation within the uterine lumen although they produce the protease, plasminogen activator. Invasion may be prevented by endometrial secretion of progesterone‐induced protease inhibitors which are produced in large amounts. in addition to estrogens of conceptus origin, calcium and prostaglandins PGF2α and E2 may affect the uterine vasculature, water and electrolyte transport, capillary permeability, conceptus steroid production, and related events during pregnancy. The blastocysts of the large domestic animals also secrete proteins which include a large glycoprotein (Mr ∼ 600,000) and a small acidic protein (Mr ∼ 17,000). The latter has been purified from sheep and named ovine trophoblast protein. I. These proteins may play unique roles in early pregnancy with respect to establishment and maintenance of pregnancy in the ewe, sow, mare, and cow.
Direct calorimetry of marine invertebrates entering anoxic states
Authors: Hammen C. S. 
Published: June 2005

AbstractMetabolic rates of 10 species of invertebrates were determined as they depleted the dissolved oxygen in a small volume of water, and entered anoxic states. The animals included eight marine forms (four mollusks, two brachiopods, a crustacean, and a polychaete), a brackish‐water crab, and a freshwater oligochaete. Rates of heat production (QH) were calculated from measurements of temperature change in a heat‐retention calorimeter. Rates of oxygen consumption (QO) were calculated from concurrent decreases in oxygen concentration (CO) determined by polarographic oxygen sensor.When the water was fully saturated with oxygen, QH and QO of all species were equal, and most rates were 1–7 J/hr‐gm wet weight. A swimming crustacean and the oligochaete had rates five times higher, possibly due to high activity. QO decreased with CO in all species. However, the relation was species specific, most animals showing overreaction to declining CO. In Callinectes only partial regulation of QO was observed at CO above 55% saturation. In all species, QH decreased more slowly than QO over most of the CO range, and decreased rapidly at some critically low CO.The relation between metabolic rate and oxygen saturation was summarized in the fraction (KO) of the fully aerobic rate found when CO was at exactly onehalf saturation, analogous to a Michaelis constant, but not implying a particular mechanism. The KO for QO averaged 0.70, and the KO for QH in 8 species averaged 0.22. In two bivalves QH was often above the initial fully aerobic level at intermediate CO.
Calorimetric techniques for metabolic studies of cells and organisms under normal conditions and stress
Authors: Hammerstedt Roy H. , Lovrien Rex E. 
Published: June 2005

AbstractWhen cells are subjected to stress, an early result is a shift in type and rate of metabolism to reflect their new conditions. The availability of metabolites, their endogenous vs exogenous origins, and the rates at which they can be used, besides availability of oxygen, dictate cell and tissue response. Measurement of heat output in such a response is a means for monitoring cells and tissues. Differential heat conduction calorimeters are reviewed to provide a listing of instrument parameters important in optimum practical use. Data obtained with one cell system, mammalian sperm, are presented to provide an example of how the combination of calorimetry and carbon balance, plus calculation from thermodynamic constants, permit an assessment of the importance of endogenous metabolism to total cellular metabolism.
Heat dissipation and energetic efficiency in animal anoxibiosis: Economy contra power
Authors: Gnaiger Erich 
Published: June 2005

AbstractThis survey on calorimetry and thermodynamics of anoxibiosis applies classical and irreversible thermodynamics to interpret experimental, direct calorimetric results in order to elucidate the sequential activation of various biochemical pathways. First, the concept of direct and indirect calorimetry is expanded to incorporate the thermochemistry of aerobic and anoxic metabolism in living cells and organisms. Calorimetric studies done under normoxia as well as under physiological and environmental anoxia are presented and assessed in terms of ATP turnover rate. Present evidence suggests that unknown sources of energy in freshwater and marine invertebrates under long‐term anoxia may be important.During physiological hypoxia, thermodynamically grossly inefficient pathways sustain high metabolic rates for brief periods. On the contrary, under long‐term environmental anoxia, low steady‐state heat dissipation is linked to the more efficient succinate, propionate, and acetate pathways. In the second part of this paper these relationships are discussed in the context of linear, irreversible thermodynamics. The calorimetric and biochemical trends during aerobic‐anoxic transitions are consistent with thermodynamic optimum functions of catabolic pathways. The theory predicts a decrease of rate with an increase of thermodynamic efficiency; therefore maximum rate and maximum efficiency are mutually exclusive. Cellular changes of pH and adenylate phosphorylation potential are recognized as regulatory mechanisms in the energetic switching to propionate production. While enzyme kinetics provides one key for understanding metabolic regulation, our insight remains incomplete without a complementary thermodynamic analysis of kinetic control in energetically coupled pathways.
Photoperiodic control of the ovarian cycle in the rosefinch, Carpodacus erythrinus
Authors: Tewary P. D. , Dixit Anand S. 
Published: June 2005

AbstractThe gonadal responses of female rosefinches (Carpodacus erythrinus) have been described and investigated with lighting regimens of various combinations. It is evident that the ovarian cycle is photoperiodically regulated. The rosefinch has a definite photoperiodic threshold to its gonadal activities, the rate of growth being greater in longer photoperiods. A refractory period has also been found in its ovarian cycle, which requires at least 7 weeks of short day treatment for its dissipation.
Characteristics and functional significance of daily cycles in serum gonadotropin hormone levels in the goldfish
Authors: Hontela Alice , Peter Richard E. 
Published: June 2005

AbstractGoldfish were subjected to 12L:12D/12°C, 16L:8D/20°C, or to an outdoor pond regime for various lengths of time at several times of year. Serum gonadotropin hormone (GTH) levels were determined through 24‐h periods and ovaries were examined histologically. Low and uniform serum GTH levels were found throughout the day in fish under 12L:12D/12°C for 32 days in November; significant fluctuations were found under this regime after 32 days in March. In fish held under 16L:8D/20°C, a peak in serum GTH levels was detected after 7 days in November and after 13 days in March. GTH levels were high and uniform throughout the day after 32 days in November and March. Patterns of daily cycles in serum GTH levels of fish kept in an outdoor pond were similar to the patterns detected in the laboratory under similar conditions of photoperiod and temperature. Fluctuating serum GTH levels were correlated with greater oocyte growth than constant low levels. Constant high serum GTH levels were correlated with oocyte atresia.
Cellular aspects of alloimmune reactions in sponges of the genus Axinella I. Axinella polypoides
Authors: Buscema Marco , Van de Vyver Gysèle 
Published: June 2005

AbstractAllograft rejection in sponges has been repeatedly reported to be associated with cytotoxicity and tissue necrosis. The present work was undertaken in order to investigate the cellular aspects of antagonistic allograft rejection in Axinella polypoides, as part of an extended analysis of sponge immune reactions. Allografts were made by parabiosis of sponge branches, and their reaction was followed using light, transmission, and scanning electron microscopy. Rejection began paradoxically with the strong adherence of the parabionts. After three days, the zone of contact was characterized by extensive archaeocyte invasion, intensive phagocytosis, and cell lysis. Phagocytosis, achieved by the accumulated archaeocytes, involved healthy spherulous cells, and a substantial accumulation of cellular debris resulting from lysis of randomly dispersed single cells, mainly archaeocytes. The reaction lasted seven to nine days, after which cleavage of the reaction zone occurred, resulting in the separation of the parabionts. The reaction appeared to be limited to the former zone of contact, leaving a scar of denuded skeleton network. Our results clearly point out the role of archaeocytes in the rejection processes of Axinella polypoides; they suggest that cell lysis in antagonistic rejection of sponges depends on cytotoxic interactions between archaeocytes, since these cells appear to achieve both cytotoxicity, or killing activity, and phagocytosis. Some aspects of histoincompatibility in sponges and their analogies with those found in vertebrates are discussed.
Modifications of some erythrocyte parameters in hibernating vertebrates, revealed by cytofluorometric techniques
Authors: Barni S. , Gerzeli G. 
Published: June 2005

AbstractThe variations of the glycoconjugate concentrations (PAS‐positive material), with special reference to the membrane sialic component have been studied during the annual cycle in erythrocytes of three mammalian species (Erinaceus europaeus, Glis glis, Talpa europaea) and of one amphibian species (Rana esculenta). In R. esculenta the structural modifications of nuclear chromatin (different degree of compactness) have also been examined through the propidium iodide intercalation at different concentrations.The membrane sialic components during hibernation increase in Rana (457%), Glis (304%), and Erinaceus (244%), and decrease in Talpa (59%), not really a hibernating species. These data can be related with a slowing down of erythropoiesis and with the increase of the average length of erythrocyte life in the winter. Residual glycoconjugate components are also modified with a similar, but less evident, pattern. The changes in the fluorescence fading during the annual cycle show a substantial independence from the concentration index of the PAS‐positive material; this fact might be related to molecular modifications or heterogeneity of the substrate.The DNA‐propidium iodide intercalation in frog erythrocyte chromatin decreases during the hibernation, possibly related to a reduced functional activity of cells.
Detection of conspecific odors by the female broad‐headed skink, Eumeces laticeps
Authors: Cooper William E. , Vitt Laurie J. 
Published: June 2005

AbstractThe potential abilities of adult female E. laticeps to detect conspecific odors and to discriminate between male and female conspecific odors were investigated by comparisons of tongue extrusion rates emitted in response to chemical stimuli presented on moist cotton applicators. Postreproductive females treated with estradiol‐17β to stimulate possible increases in sensitivity to odors associated with the breeding season showed significantly higher tongue‐flick rates to the cloacal odors of both sexes than to distilled water. There was no evidence that the females discerned any difference between male and female odors. Estrogen‐injected females had somewhat higher tongue‐flick rates than did untreated postreproductive females, but the differences were not significant. Tongue extrusion rates of estrogen‐injected females were substantially lower than those of testosterone‐implanted males for all odor stimuli. It is argued, but not demonstrated, that female E. laticeps respond to the cloacal odors as stimuli arising from conspecific or at least closely related skinks.
Exogenous ecdysteroids elicit low‐threshold sensory responses in spiny lobsters
Authors: Spencer Maribeth , Case James F. 
Published: June 2005

AbstractElectrophysiological recordings from chemoreceptors in the lateral antennule of Panulirus interruptus reveal low threshold detection of 10−3 M β‐ecdysone or 10−12 M α‐ecdysone with a latency of less than 1 second. Responses to either α‐ or β‐ecdysone were recorded from juvenile, female (with and without spermatophores or bearing eggs), and male lobsters in intermolt and premolt stages. Receptors responding to α‐ecdysone did not respond to 2.9 × 10−11 M β‐ecdysone. The behavioral function of this low threshold detection is not known, but ecdysteroids may be important in intra‐ or interspecific communication. The short latency of this neural response to ecdysteroids strongly implicates interaction with a membrane‐associated component. Thus, the chemoreceptors in the lateral antennule of P. interruptus may provide a valuable system for the study of the affinity and specificity of membrane‐bound ecdysteroid receptors for comparison to previously described cytoplasmic and nuclear ecdysteroid receptors and membrane‐associated receptors specific for other steroid compounds.
Biochemical characterization of the hatching process of Ilyanassa obsoleta
Authors: Sullivan Charles H. , Bonar Dale B. 
Published: June 2005

AbstractThe biochemical nature of the hatching substance released by Ilyanassa obsoleta embryos was examined by assessing the biological activity of the hatching substance after several treatments. Active preparations of the hatching substance capable of dissolving the egg capsule plug were inactivated in sodium dodecyl sulfate, 2‐mercaptoethanol, some proteases, EGTA, and upon boiling. Coincident with the release of the hatching substance from embryos was the appearance of several proteins and protease activity. However, specific protease inhibitors did not abolish hatching activity. The hatching substance had maximum activity at pH 7.0 and 20°C and may have a native molecular weight in excess of 100,000 daltons. These characteristics of the Ilyanassa hatching substance are very similar to the properties of the well‐studied hatching enzymes of several other embryos, yet it is still uncertain if the hatching substance is functioning as an enzyme.
Appearance of a Purkinje shift in the developing retina of the chick
Authors: Chen De‐Mao , Goldsmith Timothy H. 
Published: June 2005

AbstractThe development of rod and cone function was studied in late embryonic and posthatch chicks by measuring the spectral sensitivity of the electroretinogram (ERG) of opened eyecups to 100‐msec flashes and 25‐Hz stimuli. At the time of hatching the ERG is dominated by cone activity: the response‐energy curves for different wavelengths are parallel, and the spectral sensitivity of the dark‐adapted eye is maximal near 580 nm. During the first week after hatching, rods make a progressively greater contribution to the ERG: the response‐energy functions cease to be parallel, and the spectral sensitivity maximum to dim flashes moves to about 510 nm while the maximum for brighter lights remains at 580 nm. Only the cones are able to follow the 25‐Hz stimulus. Spectral sensitivity of the eye to 25‐Hz stimuli, measured on red‐ or orange‐adapting backgrounds, reveals the presence at the time of hatching of two photopic processes with λmax at 415 nm and 580 nm, with evidence for a third in the region 470–510 nm.
Regulation of mouse oocyte growth: Probable nutritional role for intercellular communication between follicle cells and oocytes in oocyte growth
Authors: Herlands Rosalind L. , Schultz Richard M. 
Published: June 2005

AbstractIntercellular communication, as determined by two different assay procedures, was established in vitro between mouse oocytes free of adhering follicle cells and monolayers of either follicle or 3T3 cells. Both of these cell types are known to be able to form homologous gap junctions, and follicle cells naturally form heterologous gap junctions with oocytes in vivo. Monolayers of L cells that are communication deficient did not establish intercellular communication with oocytes as determined by the two different assays for intercellular communication. The diameter of oocytes cultured for 4 days in medium or on monolayers of L cells decreased markedly, 9.7 and 13.1 μm, respectively. In contrast, oocytes cultured for 4 days on follicle cell monolayers increased on the average about 4.7 μm in diameter. Oocytes cultured for 4 days on monolayers of 3T3 cells decreased slightly in diameter, i.e., 2.1 μm. Results from these experiments support a nutritional role for intercellular communication between follicle cells and oocytes in oocyte growth.
Immunocytochemistry of luteinizing hormone‐releasing hormone in brains of bullfrogs (Rana catesbeiana) during spontaneous metamorphosis
Authors: Crim Joe William 
Published: June 2005

AbstractThe distribution of immunoreactive luteinizing hormone‐releasing hormone (ir‐LH‐RH) in brains of bullfrogs (Rana catesbeiana) during spontaneous metamorphosis has been studied by combination of an unlabeled antibody enzyme immunocytochemical technique and an adjacent serial section approach. In prometamorphic tadpoles, immunocytochemical staining for ir‐LH‐RH was absent from the brain, including a structurally simple median eminence (ME) and perikarya in the anterior preoptic area (aPOA). In metamorphic tadpoles, speckled patches of immunostaining occurred over the outer layer of a modestly developed ME; coincident faint staining of a small number of medial, unpaired cell bodies was localized in the aPOA. In newly metamorphosed juvenile frogs, more diffuse and intense staining of the outer layer of the ME accompanied increased morphological differentiation of this neurohemal area; immunoreactive perikarya again were found in the aPOA, but an increased number of neurons exhibited comparatively greater (moderate) immunostaining. Changes in the quality of immunostaining and in the numbers of cells stained, therefore, were coincident with metamorphic development. Concomitant alterations of ir‐LH‐RH immunostaining and progressive structural development of the ME suggest a coordinated differentiation of brain neuroendocrine systems during metamorphosis of the bullfrog tadpole.
Cannibals of Oxytricha bifaria (ciliata, hypotrichida): I. A crowding‐dependent cell differentiation
Authors: Ricci Nicola , Riggio Daniela C. 
Published: June 2005

AbstractThe morphology, the history, and the fate of cannibals (CNB) of Oxytricha bifaria (Ciliata, Hypotrichida) were studied. It was found that (1) the starvation somewhat hinders CNB formation; (2) the number of cells per unit volume is linearly correlated (r > 0.9) to the number of CNB formed; (3) there is a peak of CNB formation in the first 2 days from the onset of the appropriate conditions; (4) CNB have either an irregular or a roundish shape visibly different from the subelliptical shape of a normal cell; (5) their linear dimensions (200–220 μm × 90–100 μm) are almost twice those of normal cells (100 × 50 μm); (6) the peristomial funnel between the Adoral Zone Membranelles (AZM) and the Undulating Membranelles (UM) is ∼ 30° wide, twice that of a normal cell (∼ 15°); (7) the cell cycle lasts as long as 15 h at 22°C (vs. 7–8 h for normal cells); (8) the macronuclear S phase takes 50% of the macronuclear cycle, vs. 25–30% for normal cells; (9) the food vacuoles, each containing one oxytricha, may be up to 10–15/CNB; (10) the food vacuoles undergo some kind of “digestive cycle,” consisting of six well‐recognizable steps; (11) when a CNB is isolated in bacterial food, it passes through four successive cell binary fissions before reaching the morphology and the size of a normal O. bifaria.
Experimental studies on positioning and sizing of the cytoproct in Paramecium tetraurelia
Authors: Dubielecka Bozena , Kaczanowska Janina 
Published: June 2005

AbstractIn this study, attention was focused on the location and length of a single cortical compound organelle—the cytoproct of Paramecium tetraurelia. Different cells were genically or epigenetically modified in their total size and/or morphology and biometrical parameters of the cytoproct position and size were tested.Morphometrical and developmental studies revealed that the length of the cytoproct is established during every morphogenetical process. A genically induced miniaturization of cell dimensions brings about a significant decrease of the size of the cytoproct and a decrease in its distance from the oral apparatus. Wild‐type alleles introduced into miniaturized and modified cells lead to the recovery of the normal morphometry of all progeny during subsequent generations (three).Studies on doublet cells (homopolar twin cells) with an altered positioning of the oral apparatuses, and/or the variable length of the cell, allowed us to test the spatial determinants involved in the cytoproct positioning on terms of cell latitude. It is suggested that size and location of the cytoproct of Paramecium tetraurelia are directly correlated with the total length of the cell and are largely independent to the location of the oral apparatus. Theoretical implications of these results are briefly discussed.