bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ascites tumor fluid and bovine serum albumin as supplements in presomite mouse embryo cultures
Authors: Meneses Juanito J. , Pedersen Roger A. 
Published: June 2005

AbstractThe growth of presomite mouse embryos in culture was studied using mouse Ehrlich ascites tumor fluid and bovine serum albumin as supplements to the tissue culture medium. The best development was observed with a mixture of 10–20% ascites fluid and 2% bovine serum albumin. During 48 h of culture under these condition, embryos grew from egg cylinders to complex structures with neural folds and other organ rudiments. Most embryos had beating hearts, numerous pigmented red blood cells, and a fused chorioallantoic placenta. The results suggest that factors in ascites fluid support differentiation and growth of mouse embryos. Addition of bovine serum albumin was also beneficial for development. Differential sister chromatid staining of cultured embryos showed that ascites fluid increased the rate of clel proliferation as compared with medium containing bovine serum albumin alone, or bovine serum albumin and fetal calf serum. These results with abundant, and readily available supplements may facilitate certain studies of mouse embryo development.
Nitrogen excretion by embryos of an altricial bird, the redwing blackbird (Agelaius phoeniceus)
Authors: Packard Gary C. , Packard Mary J. 
Published: June 2005

AbstractSmall quantities of urea and soluble urates are present in eggs of redwing blackbirds at oviposition, but no ammonia can be detected in eggs before the ninth day of a 12‐day incubation. Urea‐nitrogen accumulates relatively slowly in eggs during development, whereas urate‐nitrogen accumulates more rapidly. At hatching, 71% of the waste‐nitrogen accumulated in eggs is in the form of urates, 26% in urea, and 3% in ammonia. Thus, the general pattern of nitrogen excretion described for embryos of precocial birds applies also to those of an altricial species.
Developmental profile of the heat shock response in early embryos of Drosophila
Authors: Bergh Sandra , Arking Robert 
Published: June 2005

AbstractDrosophila melanogaster embryos reared at 22°C were subjected to a mild heat shock (40 min at 37°C) at various ages in order to determine whether there are changes in the heat shock response during embryogenesis. The effects of the heat shock were measured by assaying (1), subsequent developmental abnormalities (2), developmental time (3), hatchability, and (4), the ability to synthesize the heat shock proteins as assayed by 35S‐methionine pulse labeling followed by protein separations using both one and two‐dimensional polycrylamide gel electrophoresis. Our data show that, first, proteins with molecular weights similar to those of six of the seven major heat shock proteins are normally found in the embryo at control temperatures (22°C); second, that the pregastrula embryo (stages 2–6) is not capable of displaying any aspect of the heat shock response upon treatment, although it may possess all of the so‐called heat shock proteins; third, that the complete heat shock response is acquired very rapidly by early gastrula embryos; and fourth, that the heat shock treatment brings about developmental delays and/or abnormalities, depending on the developmental stage of the embryo at the time of the treatment. These developmental abnormalities appear to stem from the failure of early embryos to completely inhibit their synthesis of non‐heat‐shock proteins. In the light of these findings, it becomes important not to base conclusions about the putative presence of a heat shock response in a particular tissue or developmental stage solely on the presence or absence of the heat shock proteins.
Cyclic GMP levels during regeneration in Hydra oligactis and its distribution in steady‐state animals
Authors: Berkowitz Michele S. , Lesh‐Laurie Georgia E. 
Published: June 2005

AbstractTo assess the involvement of cyclic guanosine 3′, 5′‐monophos‐phate (cGMP) in regulating cell division versus cell differentiation in regenerating systems, a radioimmunoassay study of the distribution and concentration of cGMP in steady‐state and regenerating Hydra oligactis was undertaken. In steady‐state animals, uniformly low cGMP levels were observed in the hypos‐tome‐tentacle, and upper‐, mid‐, and lower‐gastric regions. The peduncle/basal disc region, however, evidenced markedly higher levels of this cyclic nucleotide. Removal of the animal's interstitial cell population, using nitrogen mustard, did not alter this distribution. Animals lacking interstitial cells, however, exhibited greater concentrations of cGMP/cell than did untreated controls. During distal, whole animal regeneration increased cGMP concentrations were noted during wound healing and 3 hr antecedent to tentacle elaboration. A similar pattern was observed in the distal 1 mm of regenerating tissue. Basal disc regeneration was accompanied by only a single elevation in cGMP levels, concomitant with basal disc reformation. Wounded, but nonregenerating, animals likewise showed only a single rise in cGMP levels; this increase occurred during wound healing. The data, therefore, are consistent with changes in cGMP concentrations occurring in association with periods of DNA synthesis (e.g., tentacle elaboration and restructuring of the wounded surface). The distribution data and nitrogen mustard studies allow the further conclusion that the changes in cGMP recorded reflect activities of the epithelial cell population.
Electrical stimulation of the starfish's radial nerve in vitro induces the release of a gonadotrophin
Authors: Desantis Mark , Cloud J. G. 
Published: June 2005

AbstractIn starfish a neuropeptide responsible for the induction of ovulation and the reinitiation of meiotic maturation in fully grown oocytes appears to be released from the radial nerves at the time of spawning. The objectives of this investigation were to determine if the radial nerve would release this gonadotrophin when electrically stimulated in vitro and to locate other possible sources of this factor. Electrical stimulation of radial nerves isolated from the starfish, Pycnopodia helianthoides, resulted in the release of the gonadotrophin. Significant amounts of this neuropeptide were detected neither in other tissues of the starfish nor in mammalian nervous tissue.
Photoperiod perception in the blind mole rat (Spalax ehrenbergi, Nehring): Involvement of the Harderian gland, atrophied eyes, and melatonin
Authors: Pevet P. , Heth G. , Hiam A. , Nevo E. 
Published: June 2005

AbstractThe involvement of the Harderian gland, atrophied eyes, and melatonin in the perception of photoperiodic changes has been studied in the mole rat, a fossorial blind mammal the thermoregulatory capacity of which is photoperiod‐dependent. When transferred from a long photoperiod to a short one, mole rats increase their resistance to cold, a perfectly reversible phenomenon.After 2 weeks under short photoperiod the thermoregulatory capacities of animals without Harderian glands are less than those of the controls. The Harderian gland appears thus to be implicated in the detection of photoperiodic changes. After 5 weeks, however, the Harderianectomized animals had perfectly integrated the photoperiodic change, so demonstrating that other photoreceptor organs exist. The atrophied eyes, which, under these conditions, do not seem to play an important role, are involved when the animals are transferred from short photoperiod to long photoperiod. Melatonin, but not 5‐methoxytryptamine, appears to be a crucial compound in such a phenomenon.These results, which demonstrate that in mammals (at least in the mole rat, as in nonmammalian vertebrates), nonocular photoreceptors exist, suggest that the mechanism by which mammals integrate photoperiodic changes is not the same when the animals are transferred from long to short photoperiod as when transferred from short photoperiod to long photoperiod.
A nerve‐conditioning lesion accelerates limb regeneration in the newt
Authors: Maier C. Eberhardt , McQuarrie Irvine G. , Singer Marcus 
Published: June 2005

AbstractA nerve‐conditioning lesion induced sustained acceleration of limb regeneration. Newt limb nerves were subjected to a conditioning lesion by unilateral axotomy at the elbow 2 weeks prior to amputating both limbs above the elbows. Limbs on the side that had received a conditioning lesion began the regeneration process 3–4 days earlier than contralateral controls and this difference was observed up to recognizable digit formation. Limb buds on the conditioned sides had a twofold greater axonal density than contralateral counterparts at 2 weeks after amputation. Since limb bud formation is dependent on a sufficient quantity of axonal regrowth, accelerated limb regeneration is apparently due to accelerated reinnervation.
Evidence that the ectoderm is the affected germ layer in the wingless mutant chick embryo
Authors: Carrington Jill L. , Fallon John F. 
Published: June 2005

AbstractWe grafted normal flank ectoderm to the denuded presumptive wing bud mesoderm of stages 14–15 wingless embryos. When this was done, the wingless wing bud mesoderm was capable of inducing a ridge in the grafted ectoderm, maintaining that ridge, and growing out to form a wing. However, when stage 17–18 wingless wing bud mesoderm was combined with a normal leg bud ectodermal jacket, the recombinant bud failed to grow out to form a wing (Zwilling, '56a; and this report). When normal ectoderm was first grafted to a wingless host at stages 14–15, and the resulting stage 18 wing bud was removed and then the mesoderm recombined with a normal ectodermal jacket, the double recombinant bud could form a distally complete wing. However, these wings had some deficiencies compared to similar double recombinants made with normal mesoderm. These results show, first, that the ectoderm is affected by the wingless gene and, second, that there may be a prelimb bud stage interaction between wingless ectoderm and mesoderm such that, by stage 17, the wingless mesoderm becomes defective as a result of the ectodermally expressed mutation. Deficiencies in wingless mesoderm double recombinants indicate that the mesoderm may be sensitive to manipulation, possibly because the ectoderm has affected the mesoderm to some extent before stage 14. We believe it is not possible to determine the affected germ layer in wingless after the limb bud arises. However, after using the prelimb bud recombinant technique which we have designed, it becomes apparent that the ectoderm is affected by the wingless gene.
Cell death in the posterior necrotic zone of the developing chick wing measured by the loss of membrane integrity
Authors: MacCabe Jeffrey A. , Brewton Randolph G. 
Published: June 2005

AbstractCell death in the posterior necrotic zone (PNZ) of the developing chick wing was examined in organ culture using a 51chromium release assay. This isotope is incorporated into the cytoplasm of mesenchymal cells and is released from the tissue very slowly. A sudden increase in 51Cr release coincides with cell death and lysis. There is no evidence of an increase in membrane permeability prior to histological evidence of cell lysis. Lysis begins at late stage 22 or early stage 23 and lasts for 9 hours. Approximately 3,500 cells lyse in the PNZ during this period of time, resulting in a considerable decrease in cell density in the tissue.
Neuronal organization of the avian paraventricular nucleus: Intrinsic, afferent, and efferent connections
Authors: Korf Horst‐W. 
Published: June 2005

AbstractThe heterogeneous paraventricular nucleus (PVN) of birds offers favorable conditions for the analysis of intrinsic, afferent, and efferent connections of neuroendocrine systems. Paraventricular neurons are successfully impregnated with the Golgi‐technique. The findings indicate a direct influence of the cerebrospinal fluid (CSF) on the magnocellular neurons that, via their axon terminals in the neural lobe of the pituitary, are also exposed to the hemal milieu. The magnocellular neurons are intermingled with parvocellular elements which may represent local interneurons. A group of parvocellular nerve cells is identified as CSF‐contacting neurons. This type of cell forms a basic morphologic component of the avian neuroendocrine apparatus.Immunocytochemical and ultrastructural studies further support the concept of neuronal interactions between parvocellular and magnocellular elements. Moreover, these findings speak in favor of the existence of recurrent collaterals of the magnocellular neurons.Nerve cells giving rise to afferent connections to the PVN are located in the limbic system and autonomic areas of the upper and lower brainstem. Further afferents may originate from the subfornical organ, the organon vasculosum laminae terminalis, the ventral tegmentum, and the area postrema. Via efferent projections, the PVN is connected to the nucleus accumbens, lateral septum, several hypothalamic nuclei, the neural lobe of the pituitary, the organon vasculosum laminae terminalis, the subfornical organ, the pineal organ, the area postrema, the lateral habenular complex, and various autonomic areas of the reticular formation in the upper and lower brainstem and the spinal cord.In conclusion, the PVN may be regarded as an integral component of the neuroendocrine apparatus reciprocally coupled to the limbic system, several circumventricular organs, and various autonomic centers of the brain.
Effects of gonadal steroids and adrenergic agonists on avian growth and feed efficiency
Authors: Weppelman R. M. 
Published: June 2005

AbstractThe effects of gonadal steroids and adrenergic agonists in growing poultry are reviewed. Estrogens, used commercially to caponize, improve muscle palatability and weight gain but are hyperlipidemic and adversely affect feed efficiency. Their ability to caponize results from the fact that negative feedback regulation of gonadotropin secretion is mediated by estrogen synthesized within the male's central nervous system. Androgens are strongly anabolic in avian species but are deleterious to growing bone. Thus, androgens depress growth and efficiency when given before epiphyseal closure but stimulate gain and improve efficiency when given afterwards. The beta‐adrenergic agonist clenbuterol improves the growth and efficiency of broiler chickens. The effects of beta‐agonists on muscle, adipogenic tissue, and the endocrine system are presented as possible mechanisms for these actions.
Organization and activation of behavior in quail: Role of testosterone metabolism
Authors: Balthazart Jacques , Schumacher Michael 
Published: June 2005

AbstractIn quail, the hypothalamus enzymatically transforms testosterone (T) into estradiol (E2) estradiol (E2), 5α‐dihydrotestosterone (5α‐DHT). During the embryonic life, the 5β‐androstanes are inactive androgens. The decrease of 5β reductase with age during sexual maturation corresponds to a potentiation of the effects of T as shown by experiments that compared the effects of T and 5α‐DHT in adult and young quail. T metabolism is also involved in the activation of male behavior in the adult. T aromatization is probably essential for behavioral activation, but nonaromatizable androgens such as methyltrienolone, and to some extent 5α‐DHT, can also stimulate sexual behavior in castrates. These enzymatic activities show a clear neuroanatomical localization and are sexually dimorphic. Males produce more active metabolites (E2, 5α‐DHT) than females, which could explain the male's greater sensitivity to T treatments. It thus appears that T metabolism is involved in the differentiation and activation of behavior in quail.
Prolactin and parenting in the pigeon family
Authors: Silver Rae 
Published: June 2005

AbstractThe relationship between plasma prolactin and: (1) crop growth; (2) incubation; (3) brooding; and (4) feeding young in Columbiformes is reviewed. There is a good parallel between changes in crop growth and plasma prolactin fluctuations during the breeding cycle. Prolactin does not play a role in the initiation of incubation, though it can maintain the response. Toward the end of breeding, a decline in prolactin precedes the decline in incubation (of infertile eggs) or brooding (of young), while exogenously administered prolactin can prolong the response. There is no evidence of a necessary relationship between prolactin secretion and parental feeding of young, as this behavior can precede and outlast the secretion of the hormone during breeding.
Interrelation of the avian immune and neuroendocrine systems
Authors: Glick Bruce 
Published: June 2005

AbstractOur understanding of immunology and endocrinology has been enriched by studies with different avian species. Numerous experiments have identified the role of the avian thymus and bursa of Fabricius in the immune response and the interrelation of these glands and their cellular products with the neural endocrine system. The growth pattern of the thymus and bursa are influenced by steroids. Increases in thymi growth appear to be controlled, in part, by fluctuations in thyroid activity. Sex‐linked dwarf (SLD) chicks have lower T3levels than normal chicks, but normal levels of growth hormone. The poor agglutinin response of SLD chickens to low concentrations of sheep red blood cells (0.1–1.0%) may be overcome by increasing the percentage of sheep erythrocytes to 5 or injecting growth hormone, which may enhance the conversion of T4to T3. Castration impaired cell‐mediated immunity but surgical removal of the thyroid did not significantly influence the humoral response to sheep erythrocytes orBrucella. Embryonic hypophysectomy reduced the number of B cells in the late embryo. Lesioning the anterior pituitary in 9‐day‐old chicks markedly reduced several parameters of cell‐mediated immunity. In ovo bursectomy at 68 hr markedly increased the size of the adrenals and testes, numbers of Leydig cells, and levels of circulating testosterone but not corticosterone. On the basis of identification of lymphokines or cytoplasmic granules, lymphocytes and other cells of the lymphomyeloid complex are candidates for an endocrine role. A circuitry between the lymphocyte and neuroendocrine system has been identified in mammals and should be extended to Aves.
Renal handling of sodium chloride and its control in birds
Authors: Nishimura Hiroko , Miwa Toichiro , Bailey John R. 
Published: June 2005

AbstractAvian kidneys show features of both mammalian and non‐mammalian kidneys, possessing 1) cortical reptilian‐type (RT) and medullary mammalian‐type (MT) nephrons, 2) blood supplies from renal arterial and renal portal systems, and 3) a primitive macula densa. To determine how these morphological characteristics contribute to unique renal functions, we examined first a possible functional link between the renal tubules and the preglomerular vasculature and, second, the function of the loop of Henle of the MT nephrons. Infusion of 5% NaCl (2.0 ml/kg/h) into the renal portal system of the pullet Gallus domesticus caused diuresis and natriuresis in the infused side, whereas infusion of the same dose into the systemic circulation showed no effect. Infusion of 10% NaCl at a higher flow rate into either the renal portal or systemic routes caused hypernaturemia and a prolonged antidiuresis, presumably due to a release of arginine vasotocin. Plasma renin activity (PRa) decreased during renal portal infusion of hypertonic saline, suggesting that increases in intratubular or peritubular NaCl levels may suppress PRA. The thick limb of the loop of Henle (TLH) isolated from the MT nephron of the quail Coturnix coturnix revealed a lumen‐positive, furosemide‐sensitive transepithelial voltage (Vt) that requires the presence of both Na and Cl. Net water flux (Jv) was nearly zero when the TLH was perfused and bathed with isosmotic solution. Net water flux increased only slightly and osmotic water permeability (Lp) was low when the osmotic gradient was imposed. Vasotocin altered neither Vt, Jv, nor Lp. Chloride efflux was higher than Cl influx, and net Cl absorption was comparable to that of the TLH of the mammalian kidney. Thus, it appears that the TLH of MT nephrons acts as a diluting segment that contributes to the diluting and concentrating functions of the bird kidney.
Role of protein synthesis and ninhydrin‐positive substances in acclimation of Paramecium tetraurelia to high NaCl
Authors: Cronkite D. L. , Gustafson A. N. , Bauer B. F. 
Published: June 2005

AbstractParamecium tetraurelia, stock 51s, will not survive if shifted from normal medium to medium with 80–100 mM NaCl. But, if first kept in medium with 50 mM NaCl for at least 45–60 min, cells survive in medium with 80–100 mM NaCl. After shifting to medium with 50 mM NaCl, cells increase internal levels of ninhydrin‐positive substances (NPS) for the first 30 min, then decrease them again over the next 90 min. Total internal osmolarity probably remains constant over this 90 min since contractile vacuole output is constant. Treatment with the protein synthesis inhibitor G418 (geneticin) prevents acclimation in cells in 50 mM NaCl, but does not prevent the changes in NPS levels. Thus NPS are not sufficient to account for acclimation, nor is there evidence that they are required.
Phospholipase A2 from liver microsomal membranes of thermally acclimated rainbow trout
Authors: Neas N. P. , Hazel J. R. 
Published: June 2005

AbstractHydrolysis of exogenous one‐acyl,2[3H]‐oleoyl phosphatidyl choline by intracellular phospholipase A2 to yield free [3H]‐oleate and lysophosphatidylcholine was measured in isolated liver microsomes from warm (20°)‐ and cold (5°C)‐acclimated rainbow trout, Salmo gairdneri. Unlike mammalian phospholipase A2, which is not typically microsomal, over 18% of the total phospholipase A2 activity from trout liver occurred in the microsomes. Specific activity in microsomal preparations (4.07 nmole · hr−1 · mg−1) represented a 1.4‐fold purification of clarified liver homogenates (2.93 nmole· hr−1mg−1). The accumulation of free fatty acid was a function of both the duration and the protein concentration of the assay. Activity was enhanced fourfold in the presence of 0.1% Triton X‐100. Free Ca++ stimulated activity up to 100 μM, but was not an absolute requirement of the enzyme. Maximal activity occurred at pH 8.0–8.5 at 20°C assay temperature and pH 9.0 at 5°C. Acclimation history did not influence the pH optima of the enzyme. Thermal acclimation did, however, result in perfect compensation of enzymatic rate; phospholipase A2 activity from cold‐acclimated trout was not significantly different from that of warm‐acclimated trout when measurements were made at their respective acclimation temperatures. This perfect compensation for temperature as well as the unique intracellular localization of trout liver phospholipase A2 implicate the enzyme in a deacylation‐reacylation cycle that could be partially responsible for the thermally modulated restructuring previously observed in microsomal membranes of this species.