bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification, synthesis, and characterization of the yolk polypeptides of Plodia interpunctella
Authors: Shirk Paul D. , Bean Daniel , Millemann Audrey M. , Brookes Victor J. 
Published: June 2005

AbstractThe mature eggs of Plodia interpunctella were found to contain four major polypeptides. These yolk polypeptides (YPs) were found to have approximate molecular weights of 153,000 daltons (YP1), 69,000 daltons (YP2), 43,000 daltons (YP3), and 33,000 daltons (YP4) as determined by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE). In addition, we found YP1 was resolved by a 5% polyacrylamide gel into two separate polypeptides of 153,000 and 147,000 daltons. All of the YPs could be labeled in vivo or in vitro with [35S]‐methionine. Yolk peptide 1 and YP3 were synthesized by fat body of pharate adult and adult females and secreted into the hemolymph. Yolk peptide 2 and YP4 were synthesized and secreted into incubation medium by ovaries that contained vitellogenic oocytes, but these polypeptides were not found in the hemolymph. Fat bodies of males synthesized and secreted an immunoprecipitable polypeptide similar to YP3 as well as immunoprecipitable polypeptides larger than 200,000 daltons that had no counterparts in the oocytes. Peptide mapping by protease digestion showed each YP to be cleaved into unique fragments, suggesting that no precursor‐product relationship exists between the YPs. Ion exchange chromatography and gel permeation chromatography separated the yolk proteins into two groups with approximate molecular weights of 462,000 and 264,000 daltons. By resolving these peaks on SDS‐PAGE, it was found that YP1 and YP3 formed the 462,000‐dalton yolk protein and YP2 and YP4 formed the 264,000‐dalton yolk protein.
Identification and characterization of glycoproteins secreted by the skin of the day 16 fetal mouse
Authors: Janzen R. G. , Van Blerkom J. , Runner M. N. 
Published: June 2005

AbstractThe secretion of tissue‐specific proteins during mouse skin development, was investigated by incubating day 16 fetal skin explants in the presence of [35S]methionine and analyzing the medium electrophoretically. The medium was found to contain five proteins, which could be classified into two groups according to molecular weight. The kinetics of release of these proteins indicated that they were specifically secreted and not released by cytolysis. Mapping of the proteins by partial proteolytic digestion revealed that although the digestion patterns between the two molecular weight groups were different, within each group similar patterns were seen, suggesting that they were structurally related. Incubation in the presence of tunicamycin resulted in the decrease in molecular weight of the secreted proteins, indicating that the proteins were glycosylated. The results suggest that the two groups of structurally related glycoproteins were secreted by the peridermal layer of the fetal skin.
Cell death in cultured dorsal and ventral chick wing bud epithelia
Authors: Boutin Eugenie L. , Fallon John F. 
Published: June 2005

AbstractWe have examined the fate of cultured stage 20 and 25 dorsal and ventral wing bud epithelia and have found evidence that the requirements of apical ectodermal ridge and nonridge limb ectoderms for in vitro survival are different. As previously reported for the apical ectodermal ridge (Boutin and Fallon, '84), dorsal and ventral ectoderms were extensively necrotic after 12 hours of culture in serum‐containing medium. The survival of dorsal and ventral limb epithelia at 18 hours was not improved by a collagen substratum, 10% Nuserum, epidermal growth factor, nerve growth factor, multiplication‐stimulating activity, insulin, or insulin, transferrin, and selenium. This is in contrast to our observations on the ridge which remains vital for at least 24 hours in insulin or insulin, transferrin, and selenium.
Blastema cell cycle in vitro and attempted restimulation of blastema cell cycling in denervated blastemata of the adult newt, Notophthalmus viridescens
Authors: Tomlinson Bruce L. , Globus Morton , Vethamany‐Globus Swani 
Published: June 2005

AbstractThe durations of the adult newt blastema cell‐cycle phases were determined in vitro. In both ganglionated (G) and nonganglionated (nG) blastemata the total cell‐cycle time was 62 hr; G1 + ½M, S, and G2 + ½M were 18, 37, and 7 hr, respectively. The lack of a significant difference in the durations of cell‐cycle phases between G and nG explants suggests that nerve withdrawal does not influence the rate of progression through the cycle. A novel strategy was employed involving cell‐cycle suppression (denervation in vivo) and continuous labeling followed by restimulation with nerves in vitro, in anticipation that nerve‐dependent restricted cells will resume cycling. The data indicate that following prolonged denervation (48 hr), blastema cells may become refractory to neurotrophic factor.
Regional differences in the distribution of myogenic and chondrogenic cells in axolotl limb blastemas
Authors: Cameron Jo Ann , Hinterberger Timothy J. 
Published: June 2005

AbstractThe distribution of myogenic and chondrogenic cells was determined for axolotl limb blastemas at the medium bud stage, before precartilage condensation occurred. Myogenic potential of midstylopod (upper) and distal‐zeugopod (lower) amputation level blastemas, divided into distal, proximal‐core, and proximal‐peripheral regions, was assayed in vitro. Significantly more myonuclei were observed in upper level proximal‐periphery cultures than in ones from any of the other regions. Since cartilage cells give rise almost exclusively to cartilage in the regenerate (Steen, 1968), a heritable cell marker, triploidy, was used to trace the location of chondrogenic cells in histological sections of upper level early and medium bud blastemas. Although there was mixing of the graft cartilage‐derived cells and host soft‐tissue‐derived cells, the previous cartilage cells were found more frequently within the core region at early and medium bud stages. The results of these studies indicate that more chondrogenic cells are present in the core from a very early stage, and that more myogenic cells are present in the proximal periphery by the medium bud stage.
Reconstruction of a thyroid gland equivalent from cells and matrix materials
Authors: Bell E. , Moore H. , Mitchie C. , Sher S. , Coon H. 
Published: June 2005

AbstractA living thyroid gland equivalent has been fabricated with a cultivated strain of rat thyroid cells (FRTL), dermal or thyroid fibroblasts, and matrix materials. The mixture becomes tissuelike in vitro by virtue of interactions between fibroblasts and collagen. Initially in vitro the thyroid cells are uniformly distributed as single cells and a small number of clusters containing less than 10 cells. When implanted into thyrodectomized hosts the thyroid cells in the tissue lattice become organized into follicles containing a colloidlike material. The follicles were found in clusters in sizes up to 0.3 mm. The clusters are vascularized. It is thought that they arise within clones rather than by an aggregation process. Using an antithyroglobulin antibody it was shown that both thyroid cells and the colloidlike material within follicles reacted positively. Development of follicles was strictly dependent on whether hosts were thyroidectomized. In nonthyroidectomized hosts no follicles were observed. We conclude that an organotypic structure can develop in vivo from a “gland‐equivalent” fabricated with adult cells and matrix materials combined in vitro, and that cells cultivated for years in vitro retain the capacity to express differentiated functions in a reconstituted organ equivalent in vivo.
Peptidergic pathways in the avian brain
Authors: Blähser Sabine 
Published: June 2005

AbstractThe results obtained by topographical studies on the immunoreactive peptide systems in the embryonic and adult avian brain (domestic fowl, domestic mallard, pigeon, Japanese quail, and zebra finch) can be realized only by means of phylogenetical comparisons. The comparative studies mainly demonstrate a fascinating constancy of the immunological properties and the spatial distribution of the neuropeptides. Independent of the development of the neopallium, and the increasing cerebral complexity, the spatial distribution of the neuropeptides, the location of their main perikaryal accumulations which are interconnected by immunoreactive fiber projections (and thereby forming widespread but continuous peptide systems) remain nearly unchanged during vertebrate evolution. The recognition of the neuropeptides as integral parts of the central nervous system is demonstrated by the fact that neuropeptidergic structures connect sensory inputs with central nervous areas as well as with the peripheral endocrinium.
Immunohistochemistry of the hypothalamic neuropeptides and anterior pituitary cells in the Japanese quail
Authors: Mikami Shin‐Ichi , Yamada Shizuhiro 
Published: June 2005

AbstractThe pars distalis of the avian adenohypophysis consists of well‐defined cephalic and caudal lobes which are distinct in their cellular constituents. Immunocytochemical investigations on the pituitary hormones of the pars distalis of the Japanese quail reveal five types of secretory cells, adenocorticotropin (ACTH) cells, prolactin (PRL) cells, thyroid‐stimulating hormone (TSH) cells, growth hormone GH (STH) cells, and FSH/LH (gonadotropic) cells. The ACTH cells, TSH cells, and PRL cells are restricted to the cephalic lobe, and GH (STH) cells are confined to the caudal lobe, while FSH/LH cells are distributed throughout the cephalic and caudal lobes.The median eminence of birds has distinct anterior and posterior divisions, each with different neuronal components. The avian hypophysial portal vessels also consists of two groups, anterior and posterior. The peculiar arrangement and distribution of the avian hypophysial portal vessels are possibly related to the distribution of neuropeptides in the two divisions of the median eminence and to the cytological and functional differentiation of two lobes of the pars distalis.The localization of perikarya and fibers containing luteinizing hormone releasing hormone (LHRH), somatostatin, vasotocin, mesotocin, corticotropin‐releasing factor (CRF), vasoactive intestinal polypeptide (VIP), glucagon, metenkephalin, and substance P in the hypothalamus and median eminence of the Japanese quail has been investigated by means of immunohistochemistry using antisera against the respective neuropeptides. LHRH‐, somatostatin‐, VIP‐, met‐enkephalin‐, and substance P‐immunoreactive fibers are localized in the external layer of the anterior and posterior divisions of the median eminence, while CRF‐ and vasotocin‐reactive fibers are demonstrated only in the external layer of the anterior division of the median eminence. The metenkephalin fibers are thicker in the anterior median eminence but the substance P fibers are more abundant in the posterior division. Mesotocin fibers occur only in the internal layer of the median eminence and neural lobe.
Ontogeny of hypothalamo‐adenohypophyseal‐gonadal (HAG) interrelationships in the chick embryo
Authors: Woods James E. , Thommes Robert C. 
Published: June 2005

AbstractIn the male chick embryo the components of the hypothalamo‐adenohypophyseal‐testicular axis initially function independenty of each other. It is not until days 12.5–13.5 that the adenohypophysis begins to regulate testosterone synthesis and secretion; on day 13.5 plasma testosterone reaches a maximum embrynic level. This feed forward regulation of the pituitary‐testicular unit appears to involve a cause and effect relation between a statistically significant increase in the number of testicular interstitial cell LH receptors on days 12.5 and 13.0 and anincrease in plasma LH levels on day 13.5 (up‐regulation). Subsequently, events occur that are interpreted as indicative of the feedback phase of this endocrine axis. Plasma LH levels decrease after day 13.5. Also on day 13.5 and al subsequent embryonic days, there is a significant decline in the volume density of testicular LH receptor‐positive interstitial cells (IC) associated with an internalization of the LH receptor complexes and a marked decline in plasma testosterone levels (down‐regulation). It is strongly suggested that the decline in the number of LH receptor‐positive ICs and the internalization of the LH receptor complexes in indicative of a “desensitization” of the ICs followed by a decrease in testosterone synthesis and secretion. Comparable events that occur in the female embryo with respect to the development of the hypothalamo‐adenohypophyseal‐ovarian axis are also discussed in this minireview.
Thyroidal influence on body growth
Authors: King David B. , May James D. 
Published: June 2005

AbstractThis review of thyroid influence on body growth in poultry is organized around the following parameters of growth: 1) increase in body weight and skeletal size, 2) muscle growth, and 3) growth of cartilage and bone. The greatest effect of goitrogens on growth of embryos occurs during late embryogenesis at a time when normal thyroid hormone levels are increasing. Posthatching growth is reduced in severely hypothyroid animals, and body weight gain is affected more than bone growth. Thyroid hormone replacement restores body growth of thyroidectomized chickens, but supplemental hormone in normal animals has no beneficial effect on growth. Excessive T3 (fed at 1 ppm) is detrimental to growth and feed efficiency. No clear correlation between thyroid hormone concentration and growth rate of normal chickens has been identified. Growth depression in sex‐linked dwarf birds is at least partially reversed by supplemental T3. Muscle growth is reduced in goitrogen‐treated chickens and the growth reduction is reversed by supplemental thyroxine. Total DNA accumulation is reduced in hypothyroid chickens, but muscle mass relative to DNA content is normal following long‐term treatment; this suggests some regulation of muscle mass relative to DNA content. T3 increases the number of muscle fiber nuclei in hypothyroid chickens and the uptake of 3H‐thymidine into nuclei within the basal lamina. T3 directly stimulates growth and maturation of embryonic chick cartilage and enhances the in vitro action of somatomedins on cartilage growth. There is little information concerning the role of the thyroid in posthatching cartilage and bone growth in poultry.
Aspects of the neuroendocrine control of ovulation and broodiness in the domestic hen
Authors: Sharp Peter J. , Macnamee Michael C. , Talbot Richard T. , Sterling Robert J. , Hall Terence R. 
Published: June 2005

AbstractThe neuroendocrine control of ovulation and broodiness in the domestic hen involves complex interactions between hypothalamic neuropeptides, neurotransmitters, and ovarian steroids which regulate the secretion of luteinizing hormone (LH) and prolactin. Nuclear progesterone receptor is localized in many neurons throughout the hypothalamus but is absent from LHRH neurons. Hence, the positive feedback action of progesterone on LH release is not mediated by a genomic mechanism within the LHRH neuron. Precursors of 5‐hydroxytryptamine (5HT) and dopamine (Da) inhibit the preovulatory release of LH, while the turnover rates of these neurotransmitters in the anterior hypothalamus decrease when preovulatory levels of LH are at their highest. Further, a population of receptors for 5HT which occurs in the anterior hypothalamus in laying birds is absent in nonlaying, incubating hens. Taken together, these observations suggest that the preovulatory surge of LH is mediated by a transitory decrease in the inhibitory action of 5HT and possibly DA, on the secretion of LHRH. Neurons containing 5HT may play a role in the regulation of prolactin release and, more specifically, in the control of broodiness. Drugs which enhance the function of 5HT neurons stimulate prolactin release while increased prolactin secretion in incubating hens is associated with an increase in the turnover of 5HT in the anterior hypothalamus. No receptors for 5HT were demonstrable in the anterior pituitary gland, showing that the prolactin‐releasing activity of 5HT must be mediated by a prolactin‐releasing factor (PRF). A candidate for a physiological PRF is vasoactive intestinal polypeptide (VIP). Cell bodies containing VIP are abundant in the basal hypothalamus and have terminals in the median eminence. Further, VIP stimulates prolactin release in incubating hens both in vivo and in vitro and this response of the pituitary gland to VIP is enhanced after “priming” with estrogen. Dopamine may also play a role in the regulation of prolactin release in incubating hens. When plasma prolactin levels are high, DA exerts an inhibitory effect on prolactin release. It is suggested that the secretion of prolactin in incubating hens is regulated by a short‐loop feedback mechanism which stimulates the turnover of hypothalamic DA.
Steroidogenesis in granulosa cells during follicular maturation: Evidence for desensitization‐resensitization during the ovulation cycle
Authors: Hertelendy F. , Asem E. K. 
Published: June 2005

AbstractOutput of progesterone, the end product of the steroidogenic pathway, was studied in isolated chicken granulosa cells in relation to follicular maturation and during the ovulation cycle with particular reference to the period between the LH peak and ovulation. The evidence gathered from a series of experiments conducted during the past 2–3 years in the authors' laboratory indicate that the steroidogenic capacity of granulosa cells during follicular maturation is regulated not so much by receptors‐coupled adenylatete cyclase activity as has been proposed by other investigators, but by the activity of key steroidogenic enzymes, particularly the cholesterol 20,22 demolase. Furthermore, granulosa cells undergo cyclic sensitization following the endogenous LH surge reaching maximal responsiveness about 1 hr before oviposition. This is followed by a rapid desensitization shortly before ovulation. This desensitization extends to the second and subsequent developing follicles probably in proportion to the evolving LH receptors. It is suggested that granulosa cells remain in such a desensitized state for several hours postovulation, during which time progesterone responses to LH are attenuated and consequently ovulation does not occur prematurely. It is proposed that this intraovarian mechanism is an important component of the physiological events that regulate the ovulation cycle in the domestic fowl.
Regulation of prolactin and its role in gallinaceous bird reproduction
Authors: El Halawani M. E. , Burke W. H. , Millam J. R. , Fehrer S. C. , Hargis B. M. 
Published: June 2005

AbstractThere are major changes in ciruclating luteinizing hormone (LH), prolactin (PRL), estrogens (E), and progesterone (P) in relation to the onset of reproduction, egg laying, incubation, and care of young. LH levels increase in the prelaying period, followed some days later by increased circulating levels of E, P, and PRL. Levels of these hormones tend to stabilize during egg laying with periodic ovulatory cycle changes. Around the onset of incubation PRL levels increase, while LH, E, and P levels fall. During incubation PRL reaches very high levels, falling sharply when incubation is terminated. Stimulatory effects of hypothalamic neurotransmitters, peptides, and ovarian steroids on PRL secretion have been shown. The prelaying increase is dependent on E and P and the high levels of incubation require a functional serotonergic system. The causal relationships and roles of PRL in incubation of gallinaceous birds are, however, still unclear.
Is the avian circadian system a neuroendocrine loop?
Authors: Cassone Vincent M. , Menaker Michael 
Published: June 2005

AbstractAvian circadian organization is a result of a complex interaction of photoreceptive and oscillatory components. The known components include the pineal gland, the lateral eyes, the suprachiasmatic nuclei (SCN), and extraocular brain photoreceptors. The pathways by which these components integrate circadian rhythmicity suggest a neuroendocrine loop in which the SCN inhibits pineal and ocular oscillators during the course of subjective day via a multisynaptic neuronal pathway which includes the superior cervical ganglia (SCG). During the night, the pineal in turn inhibits SCN activity via its secretion of the hormone melatonin into the blood circulation. This neuroendocrine loop, it is proposed, synchronizes multiple oscillators within each component and maintains the stability and precision of the system.
Adrenal gland: Some evidence for the structural and functional zonation of the steroidogenic tissues
Authors: Holmes W. N. , Cronshaw James 
Published: June 2005

AbstractThere are two regions of steroidogenic tissue in the bird adrenal gland: a subcapsular zone (SCZ) 40–60 cells thick consisting of cells with irregularly shaped nuclei, relatively little smooth endoplasmic reticulum, and mitochondria with shelflike cristae that surrounds an inner zone (IZ) of tissue comprised of smaller cells with rounded nuclei, a more abundant endoplasmic reticulum, and mitochondria with tubular cristae. The cristae in the mitochondria of IZ cells, but not hte SCZ cells, seem to be quite labile and only assume the tubular configuration when subjected to corticotropic stimulation. The properties of the steroidogenic cells in the two zones are quantitatively distinct, the cells of the SCZ producign relatively more aldosterone and relatively less corticosterone than the cells of the IZ. The corticotropic responsiveness of the IZ cells is dependent on the synthesis of protein in the cytoplasm and a normal pattern of microfilament assembly. The dose responsiveness of both the IZ and the SCZ cells in vitro is a complex quadratic function of the corticotropin concentration to which they are exposed; the semilogarithmic linear response to corticotropin is restricted to a narrow midrange of concentrations, and at high concentrations cells from both zones of the gland respond submaximally. Throughout the dose‐response range, however, the steroidogenic cells of the IZ are more sensitive and more responsive to corticotropic stimulation than are the cells of the SCZ.
Stress and adrenal function
Authors: Harvey S. , Phillips J. G. , Rees A. , Hall T. R. 
Published: June 2005

AbstractThe natural environment is composed of various potentially hostile stressors. It is a basic requirement of life that the cells of an organism must be maintained within closely defined physiological limits. The maintenance of a constant interior mileu results from physiological and behavioural homeostatic adaptations. The physiological regulation of homeostatis is achieved by complex endocrine interactions, principally by the hormones secreted from the adrenal glands. In this brief review the responses of the avian adrenal glands to stressful stimuli, the mechanism of adrenal activation, and the function of the adrenal responses will be considered.