bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of hypoxia and body size on the energy metabolism of lungless tadpoles, Bufo woodhousei, and air‐breathing anuran larvae
Authors: Feder Martin E.
Published: June 2005

Unlike most anuran larvae, tadpoles of Bufo woodhousei (toads) lack lungs. To investigate the consequences of lunglessness and its interaction with the body size of larvae, resting and active tadpoles were exposed to hypoxia. In resting larvae, rates of O2 consumption (\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document}) were proportional to aquatic PO2, even though larvae increased buccopharyngeal ventilation considerably in hypoxia. Whole body lactate concentrations increased only in severe hypoxia. Hypoxia also depressed the \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document} of active larvae, which accumulated lactate even in normoxic water. Air‐ and water‐breathing tadpoles (Rana berlandieri and Xenopus laevis) can maintain greater routine \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document} in hypoxia than can Bufo tadpoles. However, Bufo tadpoles can extract more O2 from hypoxic water than can Rana and Xenopus tadpoles, when all are breathing only water.

The critical Po2 of active larvae and the gill ventilatory frequency of resting larvae were proportional to body size. By contrast, large and small Bufo tadpoles were similar in routine \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document} in hypoxia, the ration \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document} max:\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document} routine, and tolerance of hypoxia. Also, small tadpoles accumulated more lactate than large tadpoles when swimming at similar absolute velocities for the same times. Thus, lunglessness apparently does not limit the size of Bufo tadpoles by forcing reliance upon cutaneous gas exchange.
Current problems in human in vitro fertilization and embryo implantation
Authors: Nayudu P. L. , Lopata A. , Leung P. C. S. , Johnston W. I. H.
Published: June 2005

Recently, in several centers, there have been striking in creases in the pregnancy rates from human in vitro fertilization (IVF). Some of the improvements are 1) refinement and individualization of ovulation induction with clomiphene citrate and human menopausal gonadotropin and timing of hCG administration, aided by monitoring of plasma estradiol, cervical mucus characteristics, and follicle size and number; 2) preincubation of oocytes before insemination; 3) improvements in embryo transfer procedures, including smaller diameter catheters, smaller fluid volume, and the inclusion of a high proportion of serum in the transfer medium.

Although there are still unresolved problems at all stages it would be of significant assistance to the induction and culture if a noninvasive monitor of oocyte maturity and health were available. The appearance of the living oocyte under the light microscope has proved of limited diagnostic value.

With this aim in mind, the microscopic appearance of cumulus cells and follicular fluid protein levels have been assessed with respect to their usefulness in indirect oocyte assessment. Follicular fluid proteins from patients who had become pregnant after the transfer of a single embryo have been separated by broad spectrum pH isoelectric focusing. The complex band profiles were quantitated by laser beam densitometry.

Statistical analyses of the results, grouped according to the performance of the oocyte and resulting embryo following IVF, indicate that there are differences between the groups in which the oocytes fertilized, cleaved, and produced pregnancies and those which did not. Further studies are underway to assess the predictive value of the individual isoelectric focusing profiles. Also being investigated is their possible usefulness in monitoring ovulation induction regimens.
In vitro development of the mammalian embryo
Authors: Sanyal Mrinal K. , Naftolin Frederick
Published: June 2005

Normal growth and differentiation of mammalian embryos in vitro during the preimplantation period appear to be dependent upon the availability of appropriate metabolic substrates. For preimplantation embryos, defined conditions of culture have been achieved only in a few laboratory species. There is now evidence that differentiation factors isolated from fetal calf serum and human placental cord serum may promote further development of blastocysts. Postimplantation rat and mouse embryos can be cultured during the organogenesis period with rat or human sera in roller bottles. The embryonic differentiation of the rat at this stage of development is progressively retarded in such cultures with male rat serum. The embryonic development is not improved, even in sera obtained from rats at different days of gestation (12, 15–16, and 20–21). Inability to grow placental tissues simultaneously with embryos, accumulation of unfavorable substances, and rapid depletion of nutrients contribute to the retardation of embryonic growth. To improve growth and differentiation of conceptuses, a continuous culture system with the possibility of infusion of increasing concentrations of oxygen in the roller bottle gas atmosphere has been developed. This improved method allows considerable continuous growth and differentiation from the neurula stage with development of numerous primary organs.

Utilizing these in vitro culture methods during pre‐ and postimplantation periods, it is now possible to assess embryotoxic or teratogenic potential of drugs and chemical agents. The postimplantation culture procedure allows a more precise assessment of mechanisms associated with anomalous embryonic differentiation. Bioactivation of teratogens and effects of active toxic metabolites on organ primordium differentiation have been shown by combining embryo culture with a hepatic microsomal activating system. Microinjection of teratogens and cells into conceptus compartments is being used to elucidate specific anomalous differentiation processes.
Biochemical aspects of conceptus–endometrial interactions
Authors: Bazer Fuller W. , Roberts R. Michael
Published: June 2005

Mammalian 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

Metabolic 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

When 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

This 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

The 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

Goldfish 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

Allograft 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

The 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

The 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

Electrophysiological 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

The 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

The 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

Intercellular 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

The 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

The 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

In 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.
Cholesterol turnover and ecdysone content in tissues of normal and de‐eyestalked crabs (Cancer antennarius)
Authors: Vensel William H. , Spaziani Eugene , Ostedgaard Lynda S.
Published: June 2005

Groups of male intact, premolt and postmolt crabs, and those induced into premolt by de‐eyestalking (DE), were injected with [14C]cholesterol and selected organs were removed 24 hr later. Total as well as labeled cholesterol were measured. Values were corrected for handling loss and for extracellular (inulin) tissue volumes. Gonad had the highest endogenous cholesterol concentration (∼ 3 mg/gm), followed in order by Y organs (∼ 2 mg/gm), hypodermis, hepatopancreas, muscle, and hemolymph. Significant differences between stages for any tissue were no more than 2‐fold. However, specific activity (radioactivity/unit weight total cholesterol) of Y organs in intact premolts was 2‐ to 9‐fold higher than other organs in the same group. Shortly after DE (24 hr), Y organ specific activity was elevated as much as 164‐fold over other tissues of this group, 26 × above premolt Y organs and up to 114 × higher than Y organs of other stages. Qualitatively, similar increases occurred in hepatopancreas after DE and in muscle and hypodermis in early postmolt. The combined data include the demonstration that very rapid turnover of the free cholesterol pool occurs in Y organs in earliest premolt. Further, the large uptake of cholesterol by Y organs occurred against a steep cholesterol gradient, indicating active transport into Y‐organ cells.

With the lower detection limit at 20 ng (HPLC), ecdysone was found in all tissues extracted, 20‐hydroxyecdysone only in hemolymph and hepatopancreas. Y organs contained the highest concentrations of ecdysone and contained the hormone in more stages than other tissues. No ecdysone could be detected in Y‐organs 24 hr after DE, but it was accumulated progressively with time to 45 days after DE. Together with the findings on cholesterol, these data indicate that Y organs in early premolt rapidly take up and convert sterol precursor accompanied by equally rapid secretion, without accumulation, of ecdysone.
Relationship between insecticide‐induced short and wry neck and cervical defects visible histologically shortly after treatment of chick embryos
Authors: Wyttenbach Charles R. , Hwang Julia D.
Published: June 2005

In order to clarify the anatomical precursor of short and wry neck, 48‐hr chick embryos were injected with 6.25–200 μg of the organophosphate (OP) insecticide diazinon and recovered either at 96 hr for histological evaluation or at 19 days for gross observation. Among embryos recovered at 96 hr, all receiving a dose of 25–200 μg showed, in serial cross sections, the cervical notochord severely folded in the vertical, horizontal, and diagonal planes and the adjacent neural tube variously folded (often with branching of its canal), deformed by the notochord, rotated, and/or displaced from the midline. Virtually all embryos injected with 6.25 or 12.5 μg were fully free of such abnormalities. The coinjection of 2‐pyridinealdoxime methochloride (2‐PAM, which protects the embryo from certain OP insecticide‐induced teratisms) along with 200 μg of diazinon markedly reduced the notochord and neural deformations caused by diazinon alone. The occurrence of short neck but not wry neck at 19 days paralleled the 96‐hr cervical histology: pronounced in all embryos receiving ⩾25 μg, virtually nonexistent in those receiving 6.25 or 12.5 μg. Though more marked at higher doses, wry neck occurred to varying extents at all doses, 6.25‐100 μg. We conclude that 1) the primary insecticide effect is upon the notochord rather than the neural tube, 2) short neck is a direct consequence of notochord folding, 3) wry neck is apparently not linked with notochord folding, and 4) vertebral fusion is not the consequence solely of muscle paralysis as argued elsewhere. We propose that the notochord folds because diazinon disrupts normal formation of its sheath.
Localization of NaK ATPase activity in the nautilus siphuncle
Authors: Greenwald L. , Verderber Gustav , Singley Carl
Published: June 2005

The siphuncle of the chambered nautilus (Nautilus spp) can transport cameral liquid against osmotic pressure gradients, and is presumed to be able to transport against hydrostatic pressure gradients. It is hypothesized that the mechanism of such transport involves “local osmosis” in which the siphuncle actively trasports sodium into the blind‐ended sacs of the siphuncle cells' basolateral labyrinth. This study supports this hypothesis since NaK ATPase activity was localized only over the membranes of the labyrinth. The appearance of the reaction product required potassium and was inhibited by ouabain, a specific inhibitor of the NaK ATPase.
Intercellular junctions between the follicle cells and oocytes of Xenopus laevis
Authors: Browne Carole L. , Werner William
Published: June 2005

During development, the oocytes of Xenopus laevis establish junctional contact with the follicle cells enveloping them. These junctions have alternatively been described as desmosomes and as gap junctions. In this paper the morphology of these junctions has been examined in gonadotropin‐stimulated and ‐unstimulated animals at all stages of development. Contact between the oocyte and follicle cell plasmamembranes is visible in stage I oocytes as thickenings in the membranes, separated by intercellular spaces of 20nm or greater. By stage III in unstimulated oocytes and stage II in gonadotropin‐stimulated oocytes, intermembrane spaces at these junctional contacts are often reduced to 2 to 7 nm in width. These narrow intermembrane spacespersist through early stage IV, with greater frequency of occurrence in oocytes taken from hormonally stimulated animals. The closeness of these junctional contacts, and the permeability of the junctional spaces to intercellular tracer substances, supports the evidence that these are gap junctions.
Shell characteristics of eggs laid at 2,800 M by hens transported from sea level 24 hours after hatching
Authors: Leon‐Velarde F. , Whittembury J. , Carey C. , Monge C.
Published: June 2005

No significant differences in eggshell conductance and permeability to gases, pore area, shell thickness, or egg mass were found when eggs laid by hens transported to 2,800 m as 1‐day‐old chicks were compared to eggs laid by the parental stock at sea level. These results fail to confirm findings of Rahn et al. ('82) which suggested that alterations of eggshell structure could be associated with changes in barometric pressure.

The conductance to gases (G) of the avian eggshell is a function of the sizes and numbers of pores through the shell (Ap) and shell thickness (L) (Ar et al., '74). The average values of Ap and L characteristic of each species are thought to result from rigorous natural selection, since they control the rates of gaseous exchange between the embryo and its environment and influence its survival to hatching (Ar and Rahn, '80). The average conductance to water vapor (G) of eggs laid by montane populations of wild birds and acclimatized domestic fowl is significantly decreased below sea level values in approximate proportion to the decreased in barometric pressure (PB) at each collecting location (Wangensteen et al., '74; Rahn et al., '77; Carey et al., '83; Leon‐Velarde et al., '84). The decreased conductance is considered to be important for embryonic survival at high altitude since it appears to offset the increased tendency of water vapor to diffuse from the egg at low PB and to result in rates of water loss that are independent of PB in at least one species (Carey et al., '83).
An elevated content of a unique lipid in dystrophic chicken embryonic myoblast membranes
Authors: Kester Mark , Privitera C. A.
Published: June 2005

A unique lipid, ethanolamine plasmalogen, is not only present abnormally in the plasmalemmae of erythrocytes from ex ovo dystrophic chickens but is also present abnormally in the membranes from embryonic myoblasts of in ovo dystrophic chickens.
ATP and the autonomy of the contractile vacuole in Amoeba proteus
Authors: Pothier F. , Couillard P. , Forget J.
Published: June 2005

Contractile vacuole function in amoebae treated with immobilizing (5 mM) and nonimmobilizing (0.125 mM) concentrations of ATP has been studied. In ATP‐immobilized amoebae, most vacuolar parameters are accelerated, especially the rate of output which passes from 30 to 70 μm3/sec. This favors the concept of an autonomous vacuole, fully functional in the absence of any bulk contribution to it from remote points of the cell. A lower concentration of ATP (0.125 mM), which does not inhibit movement, causes a still greater acceleration of vacuolar function. Work is in progress to elucidate the site and mode of action of exogenous ATP on Amoeba.
Bright light flashes of 0.5 milliseconds reset the circadian clock of a microchiropteran bat
Authors: Joshi Dilip , Chandrashekaran M. K.
Published: June 2005

A phase response curve for the circadian rhythm in the flight activity of the cave dwelling bat, Hipposideros speoris, constructed with 0.5‐msec light flashes of very high intensity reported here is the first of its kind for any mammalian system and is unlike any other phase response curves constructed for other nocturnal mammals.
Intra‐ and interspecies transfer of endosymbionts in Euplotes
Authors: Fujishima M. , Heckmann K.
Published: June 2005

Fresh water Euplotes species with a “9 type 1 pattern” of frontoventral cirri (E. patella type) depend upon symbiotic bacteria that live in their cytoplasm. Aposymbiotic cells of these species are unable to divide and eventually die if not reinfected in time. We have investigated 1) whether two types of bacterial symbionts found in stocks of E. aediculatus can replace each other and 2) whether the ability to divide can be restored for aposymbiotic cells, not only by their own endosymbionts, but also by endosymbionts of other Euplotes species. We reinfected aposymbiotic cells by injecting symbiont‐containing cytoplasm into them. The results show that the two types of symbionts found in E. aediculatus stocks can replace each other. This allows us to interpret the type 7 symbiont as a secondary invader that has displaced the original omikron‐like symbiont in some E. aediculatus stocks. Finding that the symbionts of E. woodruffi are able to support growth of E. aediculatus and that those of E. plumipes support growth of E. eurystomus suggests that all Euplotes species with a 9 type 1 cirrus pattern have the same deficiency with respect to cell division. The deficiency is best explained by assuming that it is caused by a hereditary defect that arose long ago in the common ancestor of this group of species. That many of the donor‐recipient combinations we tried did not lead to a resumption of growth and cell division of the recipients probably reflects secondary adaptations of the endosymbionts to the cytoplasm of their host species, so that they no longer have the ability to grow in other environments.
Thermal hysteresis antifreeze proteins in the midgut fluid of overwintering larvae of the beetle Dendroides canadensis
Authors: Duman John G.
Published: June 2005

Freeze‐susceptible insects (those that die if frozen) must lower the freezing and supercooling points of their body fluids in winter. Although it is well known that many overwintering insects concentrate antifreezes such as polyols (glycerol, sorbitol, etc.) and/or thermal hysteresis proteins in the hemolymph, antifreezes have not previously been found in gut fluid.

Overwintering freeze‐susceptible larvae of the Pyrochroid beetle Dendroides canadensis accumulated glycerol, sorbitol, and thermal hysteresis proteins (THPs) in the hemolymph. Although polyols were not found in the midgut fluid, THPs began to be accumulated in the autumn, and in midwinter THP levels were the same in midgut fluid and hemolymph. Midgut THP concentrations decreased in late April, and THPs were gone from the midgut by June. This seasonal increase in THPs is thought to be partially responsible for the decrease in the supercooling point of midgut fluid from ∼ −5°C in summer to ∼ −25°C in winter, although cessation of feeding in winter is also likely to be important.

Proteolytic enzyme activities were at least as high in January as in June, and the THPs appear to be somewhat susceptible to these midgut enzymes, thus raising the question of how THPs are concentrated and maintained in their presence. One possible answer is that the enzymes are extremely temperature sensitive and that temperatures above 25°C are required for high levels of activity.
Lens‐forming transformations in the outer cornea of larval Xenopus laevis induced by implanted spinal ganglia
Authors: Filoni Sergio , Bosco Luigi , Cioni Carla , Burani Paola
Published: June 2005

Lumbar ganglia innervating regenerating and normal hindlimbs were removed from larval Xenopus laevis at stage 56–57 (according to Nieuwkoop and Faber, '56) and implanted between the outer and inner corneas of larvae of the same species at stage 50. The control experiments consisted of implanting fragments of liver beneath the outer cornea or of merely separating the two corneas. Results show that the ganglia innervating regenerating limbs and normal ganglia can induce visible lens‐forming transformations in the outer cornea, although the percentage of successful cases obtained after the implant of normal ganglia is noticeably lower than that of the ganglia that innervate regenerating limbs. The results are interpreted as due to the action of a neurotrophic factor capable of replacing the action of the retinal factor(s) and produced either by ganglion cells that innervate regenerating limbs or by normal ganglion cells. Nevertheless, normal ganglia are thought to produce less of this substance than ganglia innervating regenerating limbs. No lens‐forming transformations have ever been found in the controls.
High survival of mouse embryos after rapid freezing and thawing inside plastic straws with 1–2 propanediol as cryoprotectant
Authors: Renard J. P. , Babinet C.
Published: June 2005

A method for obtaining a high survival rate of frozen‐thawed mouse embryos is presented. Eight‐cell mouse embryos were frozen inside small plastic straws in the presence of 1–2 propanediol and stored at −196°C. After thawing, the embryos were diluted for only 5 min in a 1.0 M sucrose solution to remove the 1–2 propanediol from the cells. At high rate of thawing (∼2500°C/min) more than 88% of the embryos survived in vitro to the blastocyst stage provided that the dilution of propanediol was performed rapidly during thawing. At a lower rate of thawing (∼300°C/min), survival tended to be higher (94.7%) when dilution was done 5 min after thawing. When the frozen‐thawed embryos were transferred to the oviducts of day 1 pseudopregnant recipients either directly after the dilution of 1–2 propanediol or after 24 or 48 hr of culture, a high proportion of them (65.9%) develop normally to viable fetuses.
Local variation of the cell surface in chum salmon sperm as revealed by their agglutination reaction
Authors: Jaana Haruo , Yamamoto Tadashi S.
Published: June 2005

The sperm of the chum salmon, Oncorhynchus keta, possesses a bilaterally symmetrical organization by virtue of lateral extensions of the tail flagellum. An active movement of these sperm was induced immediately after incubation in well water but ceased within 2 min. A marked swelling of the cell body with coiling of the axoneme was observed during the incubation. Concanavalin A (Con A), Ricinus communis agglutinin (RCA60), and egg agglutinin from chum salmon eggs were able to induce sperm agglutination; reticular aggregates of the sperm were formed by the activity of egg agglutinin, whereas irregularly shaped clumps were produced by Con A and RCA60. Soybean agglutinin, Ulex europeus agglutinin, and wheat germ agglutinin were unable to induce sperm agglutination. Electron microscopy revealed that the aggregate or clump formations brought about by egg agglutinin and lectins are largely due to the elongation and entanglement of lateral extensions of different sperm flagella; no head‐to‐head attachment was observed. Although the aggregate formation by egg agglutinin was not inhibited by any of the sugar inhibitors used, sperm agglutination by Con A or RCA60 was blocked either by α‐methyl‐D‐mannoside or N‐acetyl‐D‐galactosamine. Con A binding sites of the cell surface detected by means of fluorescein isothiocyanate‐ or ferritin‐conjugated Con A were found to be restricted to the sperm tail, mostly to the surface of its lateral extensions. Polyethylene glycol also induced the elongation of lateral extensions of the tail flagellum; the actual fusion between different sperm occurred at the tips of these elongated extensions. No head‐to‐head or head‐to‐tail fusion was observed. We conclude that a local variation in the physiological property of the cell surface existing in the chum salmon sperm is correlated with the differential distribution of carbohydrate residues in the plasma membrane. These results in relation to early events in the fertilization of teleost eggs are discussed.
“Trophic” effect of transferrin on amphibian limb regeneration blastemas
Authors: Mescher Anthony L. , Munaim Syeda Iffat
Published: June 2005

In light of the recent demonstration that one “neurotrophic factor” of peripheral nerves is the iron‐transport glycoprotein transferrin, we tested the effects of heterologous transferrin on cellular events in cultured newt forelimb blastemas. Addition of transferrin to medium containing 1% fetal bovine serum resulted in DNA labeling and mitotic activity approximately twice as high as that of blastemas cultured in medium with 1% serum alone. Blastemas maintained for 24 hr in medium with 1% serum were stimulated to increased levels of DNA synthesis by the addition of transferrin, and this response was dose‐dependent. Varying the concentrations of iron and transferrin in the medium gave results indicating that the glycoprotein's trophic effect is due to its ability to furnish iron to the cells in an appropriate manner. Results of the study are consistent with the hypothesis that blastema cell proliferation is promoted by transferrin or transferrin‐like factors released from nerves.
Permeability of the integument of the horseshoe crab, Limulus polyphemus, to water, sodium, and bromide
Authors: Dunson William A.
Published: June 2005

Mean water movements across the double chitin membrane of the Limulus gill are 5,000–7,000 μmoles/cm2 · h. The carapace is much less permeable to water than the gill; this difference is probably due primarily to the greater thickness of the carapace. Variations in serum sodium concentration due to salinity changes do not affect the rates of water diffusion across the gills or carapace. The cause of a substantial variation between individuals in integumental water permeability is unknown. The sodium influx across the carapace of Limulus (0.7–1.6 μmoles/cm2 · h) is only a fraction that of the unidirectional water flux under the same conditions (0.5 M NaCl on both sides). This difference may be attributed to the greater size of the sodium ion in solution. There is no apparent effect of variations in carapace thickness on the sodium influx. The double chitin gill membrane is similarly low in sodium and bromide permeability (about 0.5–0.6 μmole/cm2 · h). Thus it appears that the gills may have a relatively passive role in ionic regulation. Their low rates of ionic diffusion help to restrict the loss or intake of salts as the salinity changes. However, the high gill permeability to water must pose a severe problem for an animal coping with changes in external salinity.