bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vivo ovarian uptake and processing of vitellogenin in the rainbow trout, Salmo gairdneri
Authors: Tyler Charles R. , Sumpter John P. , Bromage Niall R. 
Published: June 2005

AbstractThe in vivo uptake and processing of vitellogenin (VTG) into developing oocytes of rainbow trout were studied. Oestrogenized trout injected with 32P and 3H‐leucine incorporated these labels into newly synthesized vitellogenin. This dual‐labelled VTG was purified from the serum and injected intraperitoneally into sexually maturing female trout. The 32P. 3H‐VTG was readily taken up from the peritoneal cavity into the blood, without degradation, and thus became available for sequestration by developing oocytes. Ovarian uptake of 32P. 3H‐VTG was very rapid. Eight h after injection, approximately half of the labelled VTG was in the blood, but this figure had fallen to 12% after 48 h, and to 0.2% after 2 weeks. This fall in blood 32P. 32H‐VTG level coincided with increases in the level of both radiolabels in the ovary. Eight hours post‐injection, a significant amount of 32P. 32H‐VTG was found in the ovary homogenate. Most of this material was intact, primarily representing VTG bound to the follicle surface. However, small amounts were contained within the follicles and probably represented newly sequestered VTG which had not yet been degraded into the yolk proteins, lipovitellin and phosvitin. Twenty‐four hours post‐injection, approximately 25% of the injected 32P. 3H‐VTG had been sequestered by the ovary. Although a small proportion of the labels were associated with intact VTG, the majority of the 3H and 32P eluted with lipovitellin and phosvitin, respectively, the yolk proteins derived from VTG. After 2 weeks, nearly 70% of the 32P. 3H‐VTG initially injected had been incorporated into the ovaries, all of which was present as labelled yolk proteins. The rate of uptake of VTG was highest in the fish with the largest follicles, where it approached 120 ng.mm2 follicle surface h−1. The results demonstrate that both the uptake and processing of VTG by trout oocytes are rapid features that are reflected in the rate of ovary growth seen during exogenous vitellogenesis.
Catfish plasma lipoproteins: In vivo studies of apoprotein synthesis and catabolism
Authors: Smith M. A. K. , McKay M. C. , Lee R. F. 
Published: June 2005

AbstractThree distinct lipoprotein classes, very‐low‐density (VLDL), low‐density (LDL), and high‐density (HDL), were isolated from plasma of channel catfish, Ictalurus punctatus. HDL was the major lipoprotein class, accounting for 22–32% of the total plasma protein. The major peptide of VLDL and LDL was an apoB‐like protein (molecular mass 250,000 daltons). When a protease inhibitor was added to the plasma, there was no evidence of apoC‐ or apoE‐like proteins in catfish VLDL. The major peptide of HDL in male catfish was an apoAI‐like peptide (molecular mass 25,000 daltons). The major peptide of the HDL of female catfish undergoing vitellogensis had a molecular mass of 92,000 daltons. Plasma lipoprotein metabolism was investigated by measurement of plasma titers and the synthesis and catabolic rates of apoVLDL, apoLDL, and apoHDL. Apoprotein synthesis rates (ks) were measured in fed, 3‐day‐fasted, and 20‐day‐fasted channel catfish by continuous infusion of 14C‐tyrosine. In vivo synthesis rates of plasma apoproteins have not been previously measured. Analysis of data required the derivation of a series of equations that accounted for the kinetics of secretion of plasma proteins and their equilibration with an extravascular compartment. The plasma titer of apoVLDL was closely correlated to dietary intake, although apoVLDL synthesis rates did not significantly change with fasting. ApoLDL plasma titers significantly decreased after a 20‐day fast but not after a 3‐day fast. Fasting resulted in a significant increase in apoLDL synthesis. The apoHDL titer and synthesis rates were not significantly affected by fasting. Male and female fish have similar apoVLDL and apoLDL titers and synthesis rates. ApoHDL plasma titers and synthesis rates were significantly higher in females (14.0 ± 1.6 mg ml−1; ks = 34.9% ± 15.3% day−1) than in males (9.0 ± 1.6 mg ml−1; ks = 8.7% ± 2.6% day−1). The higher apoHDL titer and synthesis rate in female fish were due to the presence of a peptide (molecular mass 92,000 daltons) not present in males.
Thyroid status influences in vitro thyrotropin and growth hormone responses to thyrotropin‐releasing hormone by pituitary glands of hatchling slider turtles (Pseudemys scripta elegans)
Authors: Denver Robert J. , Licht Paul 
Published: June 2005

AbstractThe effects of thyroidal feedback on thyrotropin (TSH), growth hormone (GH) and prolactin (PRL) secretion by pituitary glands, and on TSH responsiveness of thyroids in hatchling turtles, Pseudemys scripta elegans, were investigated by in vitro techniques. Pituitaries were stimulated in culture with 0, 1, 10, or 100 ng/ml thyrotropin‐releasing hormone (TRH) at intervals up to 36 hr; hormones were estimated by RIA. TSH release was elevated by all doses of TRH during the first 2 hr of stimulation (1.8 to 3.6‐fold) and secretion rates increased further during the following 4 hr, with a dose response between 1 and 10 ng/ml TRH. TSH release then returned to initial basal levels and showed the same response to TRH on the second day. GH secretion was also elevated by all doses of TRH tested. A progressive increase in basal GH secretion over time in vitro suggested that GH might normally be under inhibitory control. Medium concentrations of PRL were nondetectable at all times and thus were not measured in subsequent experiments. In vitro thyroxine (T4) secretion by thyroids from these same turtles showed a dose response when stimulated with 5–20 ng/ml purified sea turtle TSH for 8 or 20 hr.Treatment of turtles in vivo with 0.5 μg T4 at 2 hr or daily for up to 2 wk prior to sacrifice greatly reduced in vitro basal TSH secretion and the response to 10 ng/ml TRH. In contrast, several of the T4treatments significantly elevated basal GH secretion. Plasma TSH was markedly elevated after 4 wk treatment with a goitrogen, methimazole, and this was accompanied by increased basal TSH secretion and responsiveness to TRH by pituitaries in vitro; basal GH secretion was reduced but the response of GH to TRH was unaffected. The response of in vitro thyroidal T4 output to TSH was augmented in hyperthyroid animals (⩾ 1 wk T4) and was abolished by methimazole treatment. These data demonstrate a clear thyroidal feedback in the regulation of chelonian TSH secretion and are consistent with an involvement of TRH in the control of pituitary TSH and GH. While the site(s) of the inhibitory actions of T4 are unknown, changes in the functional properties of the pituitary thyrotropes are involved; the somatotropes appear to be less dependent on T4.
Pathways of inorganic carbon fixation in the endosymbiont‐bearing lucinid clam Lucinoma aequizonata. Part 1. Purification and characterization of the endosymbiotic bacteria
Authors: Distel D. L. , Felbeck H. 
Published: June 2005

AbstractTwo simple techniques by which the sulfur‐oxidizing endosymbiotic bacteria may be purified from the bacteriocyte tissues of the marine bivalve Lucinoma aequizonata, are described. Tissue homogenates are prepared from symbiont‐containing tissues, and symbionts are recovered by centrifugation through gradients of Percoll density gradient medium. The high density of the endosymbionts (probably because of the presence of numerous sulfur deposits within the cells) allows clean, rapid, and efficient separation of these cells from host cells and cell constituents. Light and electron microscopy and enzymatic and biochemical techniques are used to demonstrate the identity, quality, and purity of the symbiont isolates from this lucinid clam. The techniques described here for L. aequizonata, have also been used successfully to purify sulfur‐oxidizing endosymbionts from a variety of marine invertebrates, including the bivalves L. annulata, Lucina floridana, Calyptogena magnifica, and Codakia orbicularis, and from the vestimentiferan tubeworms Riftia pachyptila, and Tevnia jerichonana. Such preparations should prove useful for investigating these and similar sulfur‐oxidizing symbioses.
Pathways of inorganic carbon fixation in the endosymbiont‐bearing lucinid clam Lucinoma aequizonata. Part 2. Analysis of the individual contributions of host and symbiont cells to inorganic carbon assimilation
Authors: Distel D. L. , Felbeck H. 
Published: June 2005

AbstractThe incorporation of 14C from H14CO−3 into acid‐soluble metabolites was examined in the endosymbiont‐containing gills and purified symbionts of the lucinid clam Lucinoma aequizonata. HPLC, paper chromatography, and enzymatic techniques were used to identify and quantify compounds into which label was incorporated in continuous and pulse‐labeling experiments. Both symbiont and host cells fix carbon in considerable quantities; however, each incorporates carbon into a distinctly different subset of compounds. In intact gills the initial carbon fixation product is malate. Label subsequently accumulates in succinate, glucose phosphate, glutamate, alanine, and glycogen. In the symbiont cells carbon is incorporated into aspartate, 3‐phosphoglycerate, malate, and citrate. Purified symbionts incorporate carbon into the same compounds in the same proportions as do symbionts that are exposed to labeled H14CO−3 while still within the host tissues. Under the conditions tested, purified symbionts released no significant quantities of labeled compounds into the incubation medium.
A quantitative study of command elements for abdominal positioning behavior in the crayfish Procambarus clarkii
Authors: Larimer James L. , Pease Craig M. 
Published: June 2005

AbstractWe develop a statistical method to estimate the total number of command elements devoted to abdominal positioning behavior in crayfish. We assumed that all command elements can be identified, that each identified cell is equivalent to a tagged individual in a population, and that the cells were sampled randomly. Samples of 29, 30, 20, and 35 cells from abdominal ganglia A3, A4, A5, and A6, respectively, were taken from our catalog. We characterized each cell using several morphological and physiological criteria, determined how many times each identified cell was present in the sample, and estimated the total number of command elements using both a maximum likelihood method and a modification of the Lincoln index. The larger the proportion of identified cells seen only once in the sample, the more identified cells there were that were unrepresented in the sample. We estimate there are approximately 34, 60, 86, and 98 command elements in ganglia A3, A4, A5, and A6, respectively.Using a slightly different data set we show that the motor output of unipolar cells is more often stronger in the direction of the cell's axonal projection. In bipolar command elements, the output strength was uncorrelated with the relative sizes of the two projecting axons.No two cells in our sample were completely identical, and this morphological variability sometimes made it difficult to determine whether or not two cells obtained from different individuals were the same identified cell. We discuss why caution should be exercised in studies requiring precision in cell identification.
Culture of newt cells from different tissues and their expression of a regeneration‐associated antigen
Authors: Ferretti Patrizia , Brockes Jeremy P. 
Published: June 2005

AbstractWe have established culture conditions for cells from normal limb, early limb regenerate (blastema), heart, and liver of the newt Notophthalmus viridescens. Whereas heart and liver cells had a relatively short life in culture, limb cells have shown no sign of senescence over more than 1 year in culture. Cultured cells from all these tissues express to differing extents the regeneration‐associated antigen 22/18. The antigen is intracellular and filamentous, and its expression appears to be regulated by culture density. Furthermore, 22/18 antigen is turned off in limb and blastemal cultures following differentiation into muscle, as also occurs in vivo.
Electrophysiological study of the effects of cardiodilatin 1–16 on the frog spinal cord in vitro
Authors: De Santis A. , Cariello L. , Miralto A. , Russo P. , Tota B. 
Published: June 2005

AbstractUsing the isolated spinal cord of the frog, hemisected and further divided into two distinct quadrants, we studied electrophysiological changes produced by peptides present in the atrial natriuretic factor (ANF) preprohormone. ANF and related peptides (atriopeptin I and atriopeptin III) did not affect the frog spinal cord. The 1–16 fragment from cardiodilatin (10−5 M) induced slow depolarization in ventral and dorsal nerve stumps. The depolarization was associated with an increase of the evoked dorsal root potentials and depression of the fast component of the reflex responses. When depolarization approached its maximum value, spontaneous slow potentials appeared progressively similar to the evoked potentials, and became rhythmic until they reached a frequency of one potential every 15–20 seconds. The effects of cardiodilatin 1–16 are localized at dorsal horn level. It is suggested that this substance exerts a modulatory effect on frog cord physiology.
Chronic low humidity‐stress in the lizard Anolis carolinensis: Changes in diurnal corticosterone rhythms
Authors: Summers Cliff H. , Norman Mark F. 
Published: June 2005

AbstractPlasma corticosterone levels of female lizards (Anolis carolinensis) were sampled at 4‐h intervals before and after a photothermal regimen known to stimulate ovarian growth in January and February, respectively. Female A. carolinensis have a diurnal cycle in plasma corticosterone with a daily peak at 1700 h in lizards with unstimulated ovaries exposed to short photophase and low temperature (12L 20°C:12D 20°C). Stimulation of ovarian growth by increasing the temperature and lengthening the photophase (14L 32°C:10D 20°C; 80% relatively humidity) caused an 8‐hr shift in the phase of the corticosterone peak to 0900 h. In lizards exposed to stimulatory temperature and photoperiod but also to low humidity (<35%) corticosterone exhibited a biphasic rhythm, with peaks at both 0900 and 1700 h. These results suggest that conditions which stimulate reproductive activity also cause a phase shift in the daily rhythm of plasma corticosterone. The results also suggest that chronic low humidity during these stimulatory conditions creates a biphasic rhythm of plasma corticosterone in this species. Therefore, a natural condition, low humidity, may be a chronic stressor of the lizard Anolis carolinensis.
Directional cell movement during early development of the teleost Blennius pholis: II. Transformation of the cells of epithelial clusters into dendritic melanocytes, their dissociation from each other, and their migration to and invasion of the pectoral fin buds
Authors: Trinkaus J. P. 
Published: June 2005

AbstractAfter clusters of pigmented epithelial cells have rested immobile in the yolk sac of Blennius pholis for 2–4 days (Trinkaus, '88), their constituent cells transform into mesenchymal, dendritic melanocytes. Then these melanocytes dissociate from one another and migrate directionally toward the developing pectoral fin bud (PFB) on either side. Each of these changes takes place in a proximodistal sequence, starting with the epithelial cluster closest to each PFB. Even individual clusters conform to this sequence, the proximal side dissociating first. Eventually, all melanocytes reach and invade the PFB. This is a 100% efficient morphogenetic cell movement. At the completion of this developmental sequence, each PFB is filled with melanocytes arranged in an arc with their filopodia extending outward and the yolk sac is bereft of pigment cells. The form and surface activity of these cells in relation to their motility and to their rate of movement are considered in detail. Attempts to understand the forces involved in giving directionality to these cell migrations are described. Finally, the significance of these observations for morphogenetic cell movements generally and for the relation between epithelial and mesenchymal cells is discussed briefly.
Extraretinal photoreception in lacertilian tail regeneration: The lateral eyes are not involved in photoperiodic photoreception in the Gekkonid lizard, Hemidactylus flaviviridis
Authors: Ndukuba Patrick I. , Ramachandran A. V. 
Published: June 2005

AbstractThe tail of the Gekkonid lizard, Hemidactylus flaviviridis was autotomized and subjected to eight different photoperiodic lengths during the period of tail regeneration, namely, (1) continuous light (LL: LD 24:0) of high intensity; (2) continuous light (LL: LD 24:0) of low intensity; (3) continuous (total) darkness (DD: LD 0:24); (4) normal light and darkness (NLD: LD 12:12); (5) 18 hours light and 6 hours darkness (LD 18:6); (6) 6 hours light and 18 hours darkness (LD 6:18); (7) 16 hours light and 8 hours darkness (LD 16:8); and 8) 8 hours light and 16 hours darkness (LD 8:16). In an attempt to determine the potential contribution of the lateral eyes, or vision, on photoperiodic photoreception in H. flaviviridis during the process of tail regeneration, some animals had both the lateral eyes surgically removed (bilateral orbital enculeation) and the enucleated animals were exposed, along with the normal (unoperated) ones, to the various photoperiodic regimes. Our observations demonstrate that blinded Hemidactylus regenerate their lost (autotomized) tails similar to their sighted (unoperated) counterparts and under LL, LD 18:6, and LD 16:8 better than sighted (unoperated) animals exposed to DD and NLD experimental lighting regimens. We, therefore, conclude that photoperiodic control of regeneration in the Gekkonid lizard, H. flaviviridis is mediated entirely by extraretinal photoreceptor(s) situated in the brain region of the head. Having established that the lateral eyes, or retinae, do not participate in photoperiodically significant photoreception and under the presumption that an extraretinal light receptor(s) may be involved, we discuss the pineal organ as the possible transmitter of the photic stimulus in these animals.
Effects of in vivo beta‐adrenoceptor blockade on hepatic carbohydrate metabolism in rainbow trout
Authors: Moon T. W. , Walsh P. J. , Perry S. F. , Mommsen T. P. 
Published: June 2005

AbstractRainbow trout, Salmo gairdneri, received intraarterial injections of saline or the beta‐adrenoceptor antagonist propranolol 1 h prior to sacrifice. Liver glycogen content in vivo and glycogen depletion, total glucose production, lactate gluconeogenesis, and oxidation in isolated hepatocytes in vitro were assessed. A significant handling‐induced glycogen depletion was prevented by prior beta‐adrenergic blockade. Reported maximal glycogen phosphorylase activities could not account for the apparent rate of glycogen depletion. Glycogen depletion continued throughout the hepatocyte isolation procedures and the rates were independent of the presence of propranolol. Epinephrine (5 × 10−7 M) or dibutyryl cAMP (1 × 10−5 M) stimulated total glucose production and lactate gluconeogenesis but not oxidation. Prior beta‐adrenoreceptor blockade depressed total glucose production, but the extent of epinephrine or dibutyryl cAMP activation was independent of the presence of propranolol in the incubation. Gluconeogenesis was depressed but only in the presence of propranolol. These results suggest that stress‐induced catecholamine surges during the preparatory phase of hepatocyte isolation in rainbow trout modify the carbohydrate metabolism of these cells during incubation.
Epinephrine stimulates prostaglandin synthesis by bullfrog lung from warm‐acclimated, but not cold‐acclimated, animals
Authors: Herman Ceil A. , Martinez Jeanelle M. 
Published: June 2005

AbstractExogenous prostaglandins (PGs) have been shown to have differing effects on frog lung contractility. In this study, prostaglandin synthesis was measured in lung tissues from warm‐acclimated (WA, 22°C) and cold‐acclimated (CA, 5°C) American bullfrogs, Rana catesbeiana, incubated for 30 min at 5° or 22°C. Media were assayed by radioimmunoassay for PGE2, PGF2α, 6‐keto PGF1α (the metabolite of PGI2), and thromboxane (TX)B2 (the metabolite of TXA2). PGE2 was produced in greatest quantity by tissues from WA and CA animals, at both incubation temperatures. Epinephrine stimulated PGE2, PGF2α, and TXB2 synthesis at 22°C but only stimulated PGE2 production at 5°C. In tissues from CA frogs, epinephrine did not stimulate prostaglandin synthesis at either incubation temperature. Ibuprofen (10−5 M) inhibited basal and epinephrine‐stimulated prostaglandin synthesis in tissues from WA frogs incubated at 22°C. The beta receptor antagonist propranolol (10−6M) blocked the epinephrine‐stimulated synthesis of PGE2, PGF2α and TXB2, suggesting epinephrine stimulates prostaglandin synthesis through beta receptor activation. The absence of stimulation by epinephrine in lung from CA animals, but not in 5°C incubations of tissues from WA animals, suggests that a modification of beta receptors occurs during prolonged cold exposure.
Effects of epinephrine and norepinephrine on glucose release from chinook salmon (Oncorhynchus tshawytscha) liver incubated in vitro
Authors: Sheridan Mark A. , Muir Nancy A. 
Published: June 2005

AbstractThe effects of two catecholamines, epinephrine (EP) and norepinephrine (NE), on carbohydrate metabolism were studied by incubating chinook salmon liver in vitro. Basal release of glucose over the course of a 5‐h incubation was 7.93 ± 1.70 μmol/g dry weight. Both EP and NE (2 × 10−7 M) stimulated glucose release rapidly during the first hour. After 5 h, EP and NE significantly increased glucose release over basal levels to 43.55 ± 9.01 and 32.75 ± 6.17 μmol/g dry weight, respectively. Epinephrine‐ and NE‐stimulated glucose release was dose dependent, with a minimum effective dose of 10−9 M. ED50 for both agents was approximately 2 × 10−7 M; maximal stimulation occurred at 10−5 M. No difference in potency between the two catecholamines was found. The effects of adrenergic agonists and antagonists were also studied. Alpha‐agonists, methoxamine and phenylephrine, had no effect on glucose release. Isoproterenol, a β‐agonist, stimulated glucose release in a manner similar to EP. The β‐antagonist, propranolol, inhibited both catecholamine‐ and isoproterenol‐stimulated glucose release. Alpha‐antagonists (phentolamine, prazosin, and yohimbine) had no effect on either catecholamine‐ or isoproterenol‐stimulated glucose release. Epinephrine and NE stimulate glycogen phosphorylase activity; propranolol inhibits catecholamine‐stimulated phosphorylase activity. These results indicate that catecholamines stimulate glucose mobilization in salmon liver by promoting glycogenolysis mediated through β‐adrenergic receptors.
Distribution and genetic basis of arginine kinase in wild type and flightless mutants of Drosophila melanogaster
Authors: James Judith M. , Collier Glen E. 
Published: June 2005

AbstractArginine kinase (AK) activity in Drosophila melanogaster has been localized to specific tissues, traced through developmental stages, and inferred to be the product of a single gene. AK is most abundant in muscle, particularly in larval and adult body‐wall muscle and digestive tract, and in adult indirect flight muscle (IFM) and legs. Low but detectable levels are present in larval imaginal discs, brain, salivary glands, and adult head and reproductive tract. Electrophoretic analysies of a series of developmental stages, as well as prepupal and adult tissues, show only one cytoplasmic isozyme. Since an allozymic variant has the same altered electrophoretic mobility in all stages and tissues, a single structural gene is inferred for AK. A variety of flightless mutants were compared to wild type in regard to AK activity and distribution.