bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glycogen metabolism in the developing chick glycogen body: Functional significance of the direct oxidative pathway
Authors: Benzo Camillo A. , De Gennaro Louis D. , Stearns Susan B. 
Published: June 2005

AbstractGlucose‐6‐phosphate dehydrogenase, 6‐phosphogluconate dehydrogenase, and glucose‐6‐phosphatase were quantitatively determined for the first time in glycogen body tissue from late embryonic and neonatal chicks. For comparative purposes, the activities of these enzymes were examined also in liver and skeletal muscle from pre‐ and post‐hatched chicks. The present data show that both the embryonic and neonatal glycogen body lack glucose‐6‐phosphatase, but contain relatively high levels of glucose‐6‐phosphate dehydrogenase and 6‐phosphogluconate dehydrogenase. The activity of each dehydrogenase in either embryonic or neonatal glycogen body tissue is two‐ to five‐fold greater than that found in muscle or liver from pre‐ or post‐hatched chicks. The relatively high activities observed for both dehydrogenases in the glycogen body, together with the absence of glucose‐6‐phosphatase activity in that tissue, suggest that the direct oxidative pathway (pentose phosphate cycle) of glucose metabolism is a functionally significant route for glycogen utilization in the glycogen body. It is hypothesized that the glycogen body is metabolically linked to lipid synthesis and myelin formation in the central nervous system of the avian embryo.
A reexamination of cleavage patterns in eutherian mammalian eggs: Rotation of blastomere pairs during second cleavage in the rabbit
Authors: Gulyas Bela J. 
Published: June 2005

AbstractThe pattern of cleavage was examined during second and third furrowing of the rabbit egg. Two‐cell eggs, collected just prior to onset of second cleavage, were continuously observed in a culture chamber, which was kept at 37°C. Semi‐cinematographic techniques were used to photograph progressive stages of cleavage. It was demonstrated that the pattern of cleavage in the rabbit differs from that in the sea urchin, because the blastomeres at the 4‐cell stage are arranged crosswise in the former, while they are situated next to each other in the latter. The crosswise arrangement of the blastomeres in the rabbit at the 4‐cell stage is a consequence of a 90° rotation of the polar axis in one hemisphere of the egg. Subsequently, due to the rotation of the original polar axis in one hemisphere, the third cleavage plane through one half of the egg is transverse to the third cleavage plane through the other half. Evidence is provided to show that the crosswise configuration of blastomeres at the 4‐cell stage occurs in other eutherian mammals. It is proposed that this rotational cleavage pattern be recognized as distinct from those of radial, spiral and bilateral.
The influence of environmental salinity on hemocyanin function in the blue crab, Callinectes sapidus
Authors: Weiland A. L. , Mangum C. P. 
Published: June 2005

AbstractThe effects of inorganic ions and of the hydrogen ion on oxygen‐binding properties of most respiratory pigments are opposite. The addition of salt to the medium increases oxygen affinities, and the addition of H+ decreases oxygen affinities of crustacean hemocyanins. These oxygenation properties, as observed in vitro, suggest that the oxygen‐transport system must adapt to ionic changes in the blood.In fact, decreases in the salt concentration of the blood of estuarine blue crabs are accompanied by increases in pH, probably resulting from the input of ammonia produced in deamination of the intracellular pool of free amino acids as the cells conform to osmotic changes in body fluids. The result is a stability of hemocyanin function until the blood becomes very dilute.As the acclimation salinity is reduced from 35 to 15 o/oo, the ionic effects on respiratory transport are balanced and there is no change in total oxygen uptake. At 5 o/oo salinity, however, the higher blood pH is manifested in an elevation of the total oxygen concentration of prebranchial blood, probably because the Bohr shift is no longer opposed by a critical level of salt in the blood. Under these conditions the role of hemocyanin in aerobic respiration is reduced at high environmental oxygen levels, but it may be enhanced in hypoxic waters.
Pineal and serum melatonin at midday and midnight following pinealectomy or castration in male rats
Authors: Pang Shiu Fun , Ralph Charles L. 
Published: June 2005

AbstractMelatonin has been extracted by chloroform from rat serum and quantified by the Rana pipiens tadpole bioassay. Like pineal melatonin, serum melatonin was high at mid‐dark and low at mid‐light. This finding suggests a diurnal rhythm of serum melatonin in the rat. Serum samples obtained at middark had melatonin levels ranging from 0.02 to 0.05 ng per ml of serum. When rats were pinealectomized, melatonin activity in the serum was abolished. Thus, rat serum melatonin may originate primarily from the pineal. There was no significant change in pineal melatonin content nor in serum melatonin concentrations 7 or 12 days following orchidectomy.
Anhydrobiosis in nematodes: Evaporative water loss and survival
Authors: Crowe John H. , Madin K. A. C. 
Published: June 2005

Abstract
Nematodes, Aphelenchus avenae, can be induced to become anhydrobiotic by drying in aggregates (pellets) (>90 mg wet weight) at 97% relative humidity (RH). When the rate of weight loss exceeds 3% hr−1 survival is low.
The number of animals in a pellet that survive exposure to dry air increases with time at 97% RH.
The time required for recovery is shortened by rehydration at high humidities before the animals are placed in water and advances with the length of time they are in dry air.
The proportion of animals recovering in water that will survive rapid dehydration decreases with the time they are in water.
A hypothetical scheme for the events of the induction of anhydrobiosis and recovery is presented.
Anhydrobiosis in nematodes: Carbohydrate and lipid metabolism during dehydration
Authors: Madin K. A. C. , Crowe John H. 
Published: June 2005

Abstract1. Changes in the chemical composition of pellets of the nematode Aphelenchus avenae were studied as the worms experienced evaporative water loss during 72 hours at 97% RH.2. Lipid content declines rapidly during the first 24 hours, and decreases to about 60% of the original by the end of 72 hours.3. Glycogen content declines to about 50% of original by the end of 24 hours, and to 10% of original by 72 hours.4. Glucose content remains constant.5. Glycerol and trehalose contents both increase rapidly, reaching about 700% of the 24‐hour content by the end of 72 hours, in each case.6. Strong correlations between survival in dry air and glycerol and trehalose contents were observed.
Mast cell histamine and ovarian follicular growth in the lizardAnolis carolinensis
Authors: Jones Richard E. , Tokarz Richard R. , Roth Jan J. , Platt James E. , Collins Allan C. 
Published: June 2005

AbstractThe hypothesis is proposed that histamine released from mast cells in the theca of ovarian follicles increases thecal hyperemia and vessel permeability, and thus plays a role in follicular growth inAnolis carolinensis. Mast cells are present in the stroma and theca, and the number of thecal mast cells increases as follicles grow. The levels of histamine in follicular walls varies with follicular size. Histamine causes vasodilatation of thecal vessels. Antihistamine blocks the effects of histamine and, when given alone, stimulates vasoconstriction. Antihistamine also blocks estradiol‐induced growth of large follicles. These findings are consistent with the above hypothesis.
Effect of limb regeneration on size increase at molt of the shore crabs Hemigrapsus oregonensis and Pachygrapsus crassipes
Authors: Kuris Armand M. , Mager Marc 
Published: June 2005

AbstractSize increase at molt is reduced following multiple limb regeneration in the shore crabs, Hemigrapsus oregonensis and Pachygrapsus crassipes. Limb loss per se does not influence postmolt size. Effect of increasing number of regenerating limbs is additive. Postmolt size is programmed early in the premolt period of the preceding instar and is probably not readily influenced by water uptake mechanics at ecdysis. A simple model for growth, molting, and regeneration in heavily calcified Crustacea is developed from the viewpoint of adaptive strategies and energetic considerations.
Initiation of meiotic maturation in Xenopus laevis oocytes by the combination of divalent cations and ionophore A23187
Authors: Wasserman William J. , Masui Yoshio 
Published: June 2005

AbstractMeiotic maturation was induced in Xenopus laevis oocytes when the external Ca++ or Mg++ion concentration was raised above 5 mM in the presence of the ionophore. Ionophore‐divalent cation‐induced maturation appears to be due to the stimulation of the oocyte itself. Cytoplasm of responding oocytes induced maturation when microinjected into ovarian oocytes. Cycloheximid, an inhibitor of progesterone‐induced maturation, inhibited the maturational response induced by the ionophore and divalentications. Ethidium bromide, an inhibitor of the follicular response to human chorionic gonadotropin, had no effect. The possible roles that Ca++ and Mg++ may play in the initiation of maturation are discussed.
Evidence that insect dorsal unpaired medican (DUM) neurons are octopaminergic
Authors: Hoyle Graham 
Published: June 2005

AbstractThe dorsal unpaired median neuron innervating the extensortibiae (DUMETi) of locusts and grasshoppers, as well as some other DUM neurons, cause long‐term inhibition of the slow intrinsic rhythm of contraction of the muscle by releasing a neurohumoral agent. Large, (600 – 1900 A), dense‐core vesicles are present in the nerve terminals. The inhibitory action is mimicked by infusion into the leg of a minute (0.01 ml.) drop of locust saline containing a very low concentration (10−6 M) of dopamine or noradrenaline, or an extraordinarily low concentration of octopamine (2.5 × 10−9 M). The amplitude and frequency of the contractions slowly return to normal Neither the cell body nor the neuron fluoresces with the Falck‐Hillarp treatment, even after a period of ligature has caused an accumulation of vesicles. Octopamine does not fluorescence with this treatment. Accordingly, it is suggested that this neuron, and the other efferent DUM neurons, are octopaminergic.
Polymerization of sperm actin in the presence of cytochalasin‐B
Authors: Sanger Joseph W. , Sanger Jean M. 
Published: June 2005

AbstractThe polymerization of globular actin to fibrous actin which occurs when sperm are activated, was not inhibited by cytochalasin‐B. The acrosomal filaments and its component actin filaments formed in the presence of cytochalasin‐B; and once formed, the actin filaments did not depolymerize when exposed to cytochalasin‐B.
Comparative strategies in the investigation of neural networks
Authors: Kennedy Donald 
Published: June 2005

AbstractComparative studies on nervous systems, though infrequently undertaken for the purpose of comparison, have yielded some important generalities about the formats of nervous networks, and about the cell biology of certain neural types. In the first category, it is clear that convergent evolutionary processes arrived at very similar networks to accomplish reciprocal and lateral inhibition, and load‐compensation in “resistance reflexes.” A newer general network format is described, command‐derived inhibition, in which the central nervous elements controlling a rapid movement deliver presynaptic inhibition to the terminals of sensory neurons that carry reafferent excitation from the movement. It is argued that such circuits occur in several groups of animals, and that they include as a special class the efferent inhibitory neurons innervating acoustico‐lateralis receptors in vertebrates.The properties of circuit elements that now seem to constitute useful generalizations include size principle (the inverse relationship between size and excitability in a variety of neurons), and the late differentiation of sensory neurons, failure to decussate, and their inability to mediate inhibition. Many other generalities have emerged, only to fall; one conclusion from such searches is that many supposedly “basic” properties of cell types or neural circuits are in fact not phylogenetically conservative, however much the physiologist may expect them to be.
Identified neurons and the future of neuroethology
Authors: Hoyle Graham 
Published: June 2005

AbstractEthologists have, in effect, opened up a vast area for physiological study by drawing attention to fixed action patterns and other stereotyped forms of instinctive behavior and by implying common physiological mechanisms underlying common behaviors in related species. Examples of such behavior in invertebrates are considered, to establish guidelines as to which behaviors may most profitably be studied by comparative neurophysiologists. These include: escape swimming and other locomotor patterns, and courtship behavior. The chosen forms should be ones in which there is a good prospect of recording intracellularly from the central neurons involved in the behavior. These neurons must be ones that can be identified individually if the biophysical events that cause the behaviors are to be described in critically acceptable terms. It is desirable that both genetic and developmental research be combined with the behavioral and physiological studies. Advantages and disadvantages of various types of invertebrates are compared, and it is concluded that a large insect offers the best overall prospects for neuroethology.
Comparative studies of purinergic nerves
Authors: Burnstock G. 
Published: June 2005

AbstractPurinergic nerves supply the gastrointestinal tract of vertebrates, including fish, amphibians, reptiles and birds, as well as mammals. Their cell bodies are located in Auerbach's plexus and their axons extend in an anal direction before innervating mainly the circular muscle coat. In the stomach they are controlled by preganglionic cholinergic fibres of parasympathetic origin.They are involved in “receptive relaxation” of the stomach, “descending inhibition” in peristalsis and reflex relaxation of oesophageal and internal anal sphincters.The terminal varicosities of purinergic nerves are characterised by a predominance of “large opaque vesicles,” which can be distinguished from the “large granular vesicles” found in small numbers in both adrenergic and cholinergic nerves. Stimulation of purinergic nerves with single pulses produces hyperpolarisations of up to 25 mV (inhibitory junction potentials) in smooth muscle cells. These potentials are unaffected by atropine, adrenergic neuron blocking agents or sympathetic denervation, but are abolished by tetrodotoxin. The “rebound contraction” which characteristically follows cessation of purinergic nerve stimulation is probably due to prostaglandin.Evidence that ATP is the transmitter released from purinergic nerves includes: (1) synthesis and storage of ATP in nerves; (2) release of ATP from the nerves when they are stimulated; (3) exogenously applied ATP mimicking the action of nerve‐released transmitter, both producing a specific increase in K+ conductance; (4) the presence of Mg‐activated ATPase, 5′‐nucleotidase and adenosine deaminase, enzymes which inactivate ATP; (5) drugs (including quinidine, some 2‐substituted imidazolines, 2‐2′pyridylisatogen and dipyridamole) which produce similar blocking or potentiating effects on the response to exogenously applied ATP and nerve stimulation.Speculations are made about the evolution and development of the nervous system, including the possibility that purinergic nerves are a primitive nerve type.
Disruption of normal forelimb regeneration in adult Notophthalmus viridescens by sublethal concentrations of trypan blue
Authors: Dearlove G. E. , Lopez S. , Dresden M. H. 
Published: June 2005

AbstractThe effects of the vital dye trypan blue (TpB) on the regeneration of amputated newt forelimbs were examined. Administration of the dye (10 μg/g body weight) via IP injection during the early wound healing and dedifferentiation phases of regeneration inhibited the normal regenerative response. The accumulation phases of regeneration are similarly halted but only by greater concentrations of TpB (50 μg/g body weight) while redifferentiation and morphogenesis are only affected by still greater concentrations of the dye (100 μg/g body weight). In addition to abolishing the regenerative response, low levels of TpB were also capable of inducing skeletal abnormalities in the regenerates as might be expected from previous reports on the teratogenicity of the dye. The in vitro action of newt hyaluronidase (as well as purified testicular hyaluronidase) on hyaluronate was diminished by TpB, with virtually complete inhibition observed at initial reaction mixture concentrations of 100 μg/ml. The results of this study suggest that TpB acts to disrupt the normal regenerative response by preventing dedifferentiation and remodeling, perhaps by inhibition of various necessary lytic enzyme functions or by interference with normal intercellular communications.
Hydrolysis of the hen egg vitelline membrane by cock sperm acrosin and other enzymes
Authors: Ho Jenny J. L. , Meizel Stanley 
Published: June 2005

AbstractA technique utilizing Pregnant Mare's Serum Gonadotropin and Human Chorionic Gonadotropin treatment of hens (Gallus domesticus), followed by manual ovulation of the excised follicles, was developed to obtain a large number of mature ova. The intact ova were used to test whether acrosin, partially purified from the spermatozoa of the cock (Gallus domesticus), partially purified rabbit testicular acrosin and commercial preparations of several hydrolytic enzymes could dissolve the inner vitelline membrane. Enzymes were applied to pieces of filter paper placed on the ovum. Cock acrosin and endopeptidases such as trypsin, chymotrypsin, collagenase and elastase hydrolyzed the membrane whereas exopeptidases such as leucine aminopeptidase and carboxypeptidase A did not. Phospholipase A, sulfatase, hyaluronidase, β‐glucuronidase and rabbit testicular acrosin also failed to hydrolyze the membrane. Cock acrosin hydrolysis of the ovum surface was inhibited by soybean trypsin inhibitor. The surface of the ovum over the germinal disc region was hydrolyzed more quickly by cock acrosin than the surface over other regions of the ovum.Acrosin from cock sperm caused the release of trichloroacetic acid soluble material absorbing at 280 nm from sonicated preparations of inner vitelline membranes. Hydrolysis was greatest at pH 8.0 and was inhibited by soybean trypsin inhibitor.
Development of locomotor behavior in wild type and spastic (sp/sp) Axolotls, Ambystoma mexicanum
Authors: Ide Charles F. , Tompkins Robert 
Published: June 2005

AbstractThe homozygous recessive spastic mutant found in the Mexican axolotl shows violent coiling and thrashing behavior when subjected to strong tactile or electrical stimulation. In order to establish the time of onset of the first behavioral manifestation of the spastic gene, an ethological analysis of the ontogeny of swimming behavior in mutants and wild type siblings was undertaken. The locomotor patterns shown by embryos in response to an electrical stimulus were analyzed quantitatively from the embryonic early flexure stage through the larval early feeding stage. Spastic larvae failed to show dorsal‐up swimming frequencies equal to those of sibling controls from day 12 (Harrison stage 40) of development indicating a lack of equilibrium. Both spastics and their siblings showed “sinusoid swimming” and “coiling” behavior in response to an aversive stimulus through day 18 (Harrison stage 46, early feeding stage) of development. From day 18, wild type siblings abruptly decreased “coiling” behavior and showed strong “escape swimming” in response to an intense stimulus. Spastics never developed “escape swimming” patterns but retained a mixture of “sinusoid swimming” and “coiling” patterns characteristic of pre‐feeding stage larvae.
Programmed collagen synthesis during postembryon development of the nematode Panagrellus silusiae: effect of transcription and translation inhibitors
Authors: Pasternak J. , Leushner J. R. A. 
Published: June 2005

AbstractDuring postembryonic development of the free‐living nematode Panagrellus silusiae, collagen synthesis is temporally regulated with an increase in production occurring prior to each molt. Under certain conditions when actinomycin D treatment blocked both growth and ecdysis the programmed synthesis of collagen was not altered. Thus, the programming of postembryonic collagen synthesis is not perforce geared to either growth or ecdysis. Actinomycin D inhibits transcription by 70% in this organism when growth is completely blocked. Additional agents (viz., cordycepin and α‐amanitin) that are known to interfere with messenger RNA utilization and production in other systems disrupt the normal pattern of collagen synthesis and prevent both growth and ecdysis in Panagrellus. Each peak of collagen synthesis, therefore, requires new RNA synthesis, presumably messenger RNA. Two known inhibitors of translation (puromycin and cycloheximide) perturb the regulated pattern of collagen production as well as growth and ecdysis. We infer that the formation of a new cuticle at each molt is dependent upon de novo collagen synthesis during each intermolt period and that growth and ecdysis require ongoing translation throughout postembryonic development.
Failure of gonadotropins to induce in vitro maturation of mouse oocytes treated with dibutyryl cyclic AMP
Authors: Nekola Mary V. , Smith Dianne Moore 
Published: June 2005

AbstractIn sufficient concentration, dibutyryl cAMP (DBC) prevents the spontaneous in vitro maturation of mouse oocytes. The effects of luteinizing hormone (LH) and follicle stimulating hormone (FSH) on this inhibition were tested in an oil‐free chamber‐slide culture system. Mouse oocytes devoid of cumulus cells were incubated in the presence of DBC and/or gonadotropins. Oocytes cultured with follicle cells were similarly treated. Whether follicle cells were present or absent, DBC (100 or 50 μg/ml) prevented germinal vesicle breakdown in more than 95% of the oocytes cultured. Neither LH nor FSH in a wide range of concentrations acted directly on the oocytes or indirectly through the follicle cells to initiate maturation in oocytes incubated with 100 μg DBC/ml. The combination of LH (5 μg/ml) and FSH (10 μg/ml) was also ineffective in overcoming the block induced by either 100 or 50 μg DBC/ml. Maturation of oocytes in each of the DBC‐free LH or FSH treatments was comparable to that occurring in control medium which did not contain exogenous gonadotropins or DBC. It was concluded that cultured oocytes treated with DBC are not a satisfactory model for studying the steps by which gonadotropins trigger the resumption of meiosis in mammalian oocytes.