bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vitro and in vivo characterization of blastemal cells from regenerating newt limbs
Authors: Maier C. Eberhardt , Miller Robert H. 
Published: June 2005

AbstractTo better characterize the cells involved in newt limb regeneration, blastemal cells from accumulation and differentiation phase blastemas were grown in dissociated cell culture, and their morphology and antigenic phenotype determined using a variety of antibodies directed against intermediate filaments, cell adhesion molecules, and extracellular matrix molecules. In addition to previously described blastemal cell morphologies, many of the cells in these cultures had a round cell body, with an eccentrically placed nucleus and a cytoplasm filled with autofluorescent granules. The majority of accumulation phase blastemal cells labeled with antibodies against GFAP, vimentin, 22/18 as well as with antibodies against NCAM, L‐1, laminin, and fibronectin. The majority of differentiation phase blastemal cells had a similar phenotype but lacked expression of vimentin and fibronectin.Comparison of the blastemal phenotype in vitro and in vivo showed similar expression characteristics. However, in differentiation phase blastemas, laminin immunoreactivity was concentrated in specific locations. In addition, the proliferation of cultured blastemal cells is stimulated by the addition of a crude brain extract, consistent with previous studies in vivo and in vitro. Taken together, these observations suggest that dissociated cultures of newt limb blastemal cells provide a suitable model for the analysis of the cell and molecular mechanisms involved in limb regeneration. © 1992 Wiley‐Liss, Inc.
Biocalcification mechanism in gorgonians: 45Ca uptake and deposition by the mediterranean red coral Corallium rubrum
Authors: Allemand Denis , Grillo Marie‐Christine 
Published: June 2005

AbstractThe biocalcification of Mediterranean red coral Corallium rubrum (Anthozoa, Octocorallia) was investigated by using 45Ca as a tracer to follow calcium transport and deposition. Kinetic experiments were performed by tracing the appearance of radioisotope in the three studied compartments of the apical part of the red coral: tissue fraction, spicules, and axial skeleton. The results demonstrate that calcium is absorbed by tissue before being deposited in the skeletal structures. The interval of time required by calcium to reach the site of calcification is about 1 hour. The spicule fraction represents the most important site of 45Ca deposition in comparison with the other two compartments.By using different kinds of inhibitors, we demonstrate that calcium enters the cell along its electrochemical gradient via verapamil‐sensitive calcium channels and is concentrated in spicule‐forming vesicles or exported to the site of axis formation by an energetic process whose activation energy is 12 Kcal/mol for both skeletal structures.Modifications of the CO2/HCO3− buffering system were used to examine the possible origins of inorganic carbon for CaCO3 formation. Our results suggest that metabolic CO2 may serve as a main source. The carbonic anhydrase enzyme appears to be involved in the hydratation of CO2 to HCO3, this latter ion being subsequently transported to the calcification site by a Cl−/HCO3− exchanger. © 1992 Wiley‐Liss, Inc.
Role of thyroid hormone in intermediary metabolism of propranolol or alloxan‐treated Calotes versicolor
Authors: Jacob Valsa , Oommen Oommen V. 
Published: June 2005

AbstractAdministration of L‐thyroxine (T4) to thyroidectomized Calotes versicolor significantly increased the activity of glucose‐6‐phosphatase (G‐6‐Pase) (liver and kidney), the concentrations of blood glucose and total protein (liver and kidney), and decreased hepatic cholesterol when compared to thyroidectomized lizards. Propranolol injections in thyroidectomized lizards increased the cholesterol concentration and did not change the other parameters. The activity of G‐6‐Pase and blood glucose content was stimulated, whereas the total protein and cholesterol contents were decreased after alloxan treatment. Administration of T4 to thyroidectomized animals pretreated with propranolol or alloxan significantly elevated the activity of G‐6‐Pase, the concentrations of blood glucose, and total protein, and reduced hepatic cholesterol level when compared to drug‐treated lizards. From the results, it is evident that thyroid hormone has an independent stimulatory influence on intermediary metabolism in C. versicolor irrespective of the involvement of adrenaline or insulin. © 1992 Wiley‐Liss, Inc.
Calcitonin‐like immunoreactivity in the blue crab: Tissue distribution, variations in the molt cycle, and partial characterization
Authors: Cameron James N. , Thomas Peter 
Published: June 2005

AbstractCalcitonin‐like immunoreactivity has been found in blood and tissues of the marine blue crab, Callinectes sapidus Rathbun. The activity in blood rises significantly during the immediate premolt (D4) stage, but tissue immunoreactivity does not vary significantly with molt stage. The immunoreactivity to antisalmon calcitonin serum is due to a 27.2 kDa protein that shows strong similarities in amino acid composition to a similar protein in a lobster and to human calcitonin precursor. The protein is most abundant in the midgut glands (hepatopancreas), but is also found in significant quantities in several other tissues. Immunoreactivity in the blood appears to be primarily due to the same molecular weight fraction, with secondary contributions from smaller molecules, closer in size to vertebrate calcitonin. A physiological function of the calcitonin‐like substance in calcium transport during or after molt has yet to be demonstrated. © 1992 Wiley‐Liss, Inc.
Specificity and early ontogeny of historecognition in the hydroid Hydractinia
Authors: Lange R. G. , Dick M. H. , Müller W. A. 
Published: June 2005

AbstractThe marine hydroid Hydractinia is a model system for study of historecognition in invertebrates. Present knowledge of this system comes from fusibility studies involving intraspecific (i.e., isogeneic and allogeneic) encounters of adult‐stage stolonal tissues. Little is known about the ability of Hydractinia to recognize and respond to xenogeneic tissue, about allorecognition by tissues other than stolonal, and about the ontogeny of historecognition. We have investigated these questions with stolonal‐encounter and grafting experiments, using the species H. echinata and H. symbiolongicarpus. We find that (a) Hydractinia employs the nematocyst effector system against the closely related hydroid Podocoryne and the more distantly related Eirene; (b) unlike intraspecific encounters, these interspecific encounters elicit nematocyst discharge by Hydractinia over a distance of up to 50 μm prior to stolonal contact; (c) the capability for historecognition is not restricted to stolonal tissues; (d) the capacity to display incompatibility, or rejection, arises between the late larval stage and early post‐metamorphosis; and (e) embryo grafts of H. symbiolongicarpus, but not those of H. echinata, appeared to show limited tolerization. © 1992 Wiley‐Liss, Inc.
Activity patterns of the wing muscles of the pigeon (Columba livia) during different modes of flight
Authors: Dial Kenneth P. 
Published: June 2005

AbstractThe temporal sequence of activity patterns and intensities (voltage per wingbeat) of electromyograms (EMGs) from 17 muscles in the shoulder and forelimb of the pigeon (Columba livia) were measured during five modes of flight (level flapping, takeoff, landing, vertical ascending, and near vertical descending flight). EMG signals were referenced to wing position using high‐speed movie film. Most muscles exhibited EMG activity during phases within a wingbeat cycle not expected a priori. All muscles exhibited some level of activity within each wingbeat cycle and during all modes of flight. Intensity of EMG activity varied significantly between different modes of flight. Most shifts in temporal patterns were minor with the exception of the humerotriceps. © 1992 Wiley‐Liss, Inc.
Effects of the nonsteroidal ecdysone mimic RH 5849 on larval crustaceans
Authors: Clare Anthony S. , Rittschof Daniel , Costlow John D. 
Published: June 2005

AbstractThe effects of the nonsteroidal ecdysone mimic RH 5849 on larvae of a crab (Rhithropanopeus harrisii) and the cypris larva of a barnacle (Balanus amphitrite) have been investigated. Larvae were exposed to exogenous RH 5849 in the concentration range of 0.1–10.0 mg/L. The two lowest concentrations tested (0.1 and 1.0 mg/L) accelerated molting of crab zoeae. RH 5849 did not induce premature apolysis. A concentration of 10 mg/L RH 5849 was toxic to zoeae: these larvae underwent apolysis but not ecdysis and subsequently died. Attachment and metamorphosis of barnacle cyprids was enhanced by 10.0 mg/L RH 5849. Increased attachment may be a result of physiological aging of larvae by the ecdysone mimic. Increased metamorphosis is consistent with the stimulatory effect of 20‐hydroxyecdysone on this process. RH 5849 was first demonstrated as an ecdysone mimic in insects (Wing, Science, 241:467–469, '88). The present study provides preliminary evidence for a similar action in crustaceans. © 1992 Wiley‐Liss, Inc.
Steroid hormone‐induced male sex determination in an amniotic vertebrate
Authors: Wibbels Thane , Bull James J. , Crews David 
Published: June 2005

AbstractIn many reptiles, sex is determined by the temperature at which the eggs are incubated (i.e., temperature‐dependent sex determination, or TSD). Past studies have shown that exogenous steroid hormones can override the effects of temperature and induce female sex determination. However, past attempts to induce male sex determination have consistently failed. In the present study, sex determination was studied in a turtle with TSD. By utilizing an incubation temperature regimen that resulted in approximately a 1:1 sex ratio in the control group, sex determination was shown to be sensitive to both exogenous androgen and estrogen treatments: androgen induced the production of male hatchlings, whereas estrogen induced the production of female hatchlings. This is the first report of an amniotic vertebrate in which an exogenous steroid hormone induces male sex determination. © 1992 Wiley‐Liss, Inc.
Immunoglobulin‐containing cells in chick embryo urogenital tissues: A new site for early B lineage cells in endothermic vertebrates
Authors: Zettergren Leslie D. , Cutlan Robert T. 
Published: June 2005

AbstractWe have employed histological and immunofluorescent staining procedures in order to characterize the distribution of μ+ B lineage cells in tissue sections prepared from developing chicken embryo urogenital tissues (UGTs) between 14 and 21 days of incubation. B lineage cells were observed in tissue sections prepared from developing UGTs, especially the mesonephros and its associated tissue, throughout the sample period. The highest densities of μ+ B lineage cells were observed in tissue sections prepared from 18 day embryos. The μ+ UGT cells were distributed singly and in clusters in subcapsular regions and within the peritubular interstitium of the mesonephros. These observations (1) are consistent with those which suggest nonbursal site(s) for origin of cells in B lineage, (2) may help account for the varying effects of embryonic caudectomy performed between the second and third days of incubation and surgical bursectomy performed close to hatching, (3) may help provide new insights on the effects of sex hormones on B cell development, and (4) suggest fundamental ontogenetic and phylogenetic similarities between developing vertebrate immune systems. © 1992 Wiley‐Liss, Inc.
Environmental factors affecting ventilation in the ascidian, Pyura praeputialis
Authors: Evans B. K. , Huntington R. 
Published: June 2005

AbstractVentilatory behaviour in the Australian cunjevoi Pyura praeputialis is described in terms of the rate of ciliary pumping and the frequency of the squirting reflex. These two behaviours were examined during conditions of low pO2, high pCO2, high and low pH, and low salinity. Ciliary pumping was impaired during hypoxic, low pH, and hyposaline conditions, and was enhanced by conditions of high pH. Squirting behaviour was increased during hypoxic and hyposaline conditions. While the results for ciliary pumping may be due to direct effects on the cilia themselves, the experiments on squirting behaviour show that Pyura is able to detect and produce a coordinated response to hypoxia and hyposalinity. The adaptive significance of these responses is discussed. © 1992 Wiley‐Liss, Inc.
Continuous cell movements rearrange anatomical structures in intact sponges
Authors: Bond Calhoun 
Published: June 2005

AbstractTime‐lapse cinemicrography was used to record the active movements of cells in living intact sponges. Each of the three main cell types (pinacocytes, mesohyl cells, and choanocytes) continuously moved and rearranged themselves so that the internal anatomy of the sponge was continuously remodeled. The shape and appearance of the sponges' anatomical structures often changed substantially within a few hours.The most motile were the mesohyl cells, with many moving as fast as one cell‐length per minute (15 μm/min). Mesohyl cell locomotion was often accompanied by displacements of spicules, canals, and choanocyte chambers; the patterns of these displacements suggested that the mesohyl cells were providing the motive forces for these rearrangements. The locomotion of the pinacocytes varied according to position: those along the outer sponge margins were most active, whereas those in other parts of the surface moved relatively little. Choanocytes were never observed to undergo independent locomotion but were always found grouped together in choanocyte chambers. These choanocyte chambers interacted with pinacocytes and mesohyl cells to form excurrent canals, which continuously moved, fused with, and branched from one another.These observations suggest that the experimental phenomenon of sponge cell‐reaggregation and reconstitution, discovered by H. V. Wilson, represents an extreme version of morphogenetic processes that normally go on continuously within intact sponges. The results from the present study also suggest that these cellular rearrangements are controlled by active cell movements and behavioral responses that include but are not limited to selective cell adhesion. © 1992 Wiley‐Liss, Inc.
Effects of diapause on lethal Yellow (Ay/Ay) mouse embryos
Authors: Papaioannou Virginia E. , Gardner Richard L. 
Published: June 2005

AbstractOne of the problems in studying early acting recessive lethal genes is recognizing the homozygotes prior to their demise. Molecular probes can assist in this task, but their use generally requires removal of cells and consequent damage to the embryo, which may compromise its subsequent development. The present study was undertaken in an attempt to distinguish intact, living, lethal yellow (Ay/Ay) embryos from Ay/ae and ae/ae littermates before implantation by placing them in implantation delay or diapause. After 2 days in the reproductive tract of prepubertal females, the great majority of presumptive lethal Ay/Ay embryos had failed to hatch from the zona pellucida and they exhibited a marked deficiency of cells relative to controls, particularly in the inner cell mass. This argues against a stage‐specific role for the gene in implantation. © 1992 Wiley‐Liss, Inc.
Mitochondrial respiration in locust flight muscles
Authors: Suarez Raul K. , Moyes Christopher D. 
Published: June 2005

AbstractHighly coupled mitochondria isolated from locust flight muscles display substrate preferences consistent with the use of carbohydrate and lipid as the major metabolic fuels during flight. Maximal rates of coupled respiration expressed per milligram mitochondrial protein exceed by severalfold published values obtained using vertebrate muscle mitochondria. These differences in maximal rates of coupled respiration in vitro are apparent even when rates are expressed per unit mitochondrial marker enzyme (citrate synthase) activity or per unit mitochondrial volume (exchangeable water space). Locusts in flight achieve a greater fraction of the flux measured in vitro through cytochrome oxidase than mammals exercising at maximum aerobic capacity. These data suggest that besides possessing “better” mitochondria, locusts may possess higher capacities for O2 (and/or substrate) delivery, allowing the achievement of higher rates of respiration in vivo than in mammals. © 1992 Wiley‐Liss, Inc.
Dopamine catabolism in goldfish (Carassius auratus) brain and pituitary: Lack of influence of catecholestrogens on dopamine catabolism and gonadotropin secretion
Authors: Sloley B. Duff , Trudeau Vance L. , Peter Richard E. 
Published: June 2005

AbstractThe catabolic pathways for dopamine degradation in the goldfish brain and pituitary were investigated. The major dopamine catabolite formed in vivo after L‐dihydroxyphenylalanine or dopamine injection was dihydroxyphenylacetic acid. Homovanillic acid and 3‐methoxytyramine are also formed but to a much lesser extent. In vitro studies also indicate that the major dopamine catabolite produced by pituitary tissue is dihydroxyphenylacetic acid. Pargyline at a dose which, in mammals, inhibits both monoamine oxidase A and B, and clorgyline at a dose which inhibits monoamine oxidase A, elevates dopamine concentrations in goldfish pituitary. Deprenyl at a dose which inhibits mammalian monoamine oxidase B or dinitrocatechol (OR‐468) which inhibits catechol‐O‐methyltransferase had no effects on pituitary dopamine concentrations in goldfish. Basal serum gonadotropin concentrations are reduced by injection of monoamine oxidase inhibitors but not by injection of the catechol‐O‐methyltransferase inhibitor. The neurotoxin 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP), which appears to require monoamine oxidase for its activity, selectively depletes noradrenaline and dopamine in the goldfish brain and pituitary. Intraperitoneal injection of large amounts of the catecholestrogens 2‐hydroxyestradiol or 4‐hydroxyestradiol (1 μg/g each hour for 5 hours) has no effect on brain or pituitary dopamine concentrations or serum gonadotropin levels. Catecholestrogens are normally not detectable in goldfish brain and pituitary; however, following intraperitoneal injection substantial amounts are measurable in the brain and pituitary. © 1992 Wiley‐Liss, Inc.
Taurine efflux, band 3, and erythrocyte volume of the hagfish (Myxine glutinosa) and lamprey (Petromyzon marinus)
Authors: Brill Susan R. , Musch Mark W. , Goldstein Leon 
Published: June 2005

AbstractHypoosmotic stress in skate RBC causes cell swelling followed by the release of solutes (osmolytes) to bring about a regulatory volume decrease (RVD). The β‐amino acid, taurine, is a primary osmolyte in RVD of skate RBC. Taurine efflux is inhibited by stilbene disulfonates and other inhibitors of the anion exchanger, band 3, suggesting that band 3 is involved in the release of taurine during RVD in skate RBC. Since RBC of the cyclostomes, hagfish and lamprey, are reported to be deficient in band 3, we examined taurine efflux, quantity of band 3, and volume response in these RBC. There was no significant increase in taurine efflux when hagfish RBC were exposed to hypoosmotic medium, and the rate of taurine efflux in these RBC was markedly lower than that in skate RBC. Hagfish RBC plasma membranes show only 11% of the level of 3H2DIDS bound to skate RBC membranes. In addition, DIDS‐sensitive sulfate exchange is much lower in hagfish compared with skate RBC. Similarly, lamprey RBC showed little taurine efflux compared with skate, and the amount of 3H2DIDS binding to these RBC membranes was 24% that of skate. Finally, although both hagfish and lamprey RBC swell in hypoosmotic medium, the lamprey cells show an RVD while the hagfish cells do not. Thus, in the RBC of the two cyclostomes, one showing an RVD and the other not, low band 3 is associated with low volume‐activated taurine efflux. These results support the hypothesis that band 3 is involved in volume‐activated taurine efflux. © 1992 Wiley‐Liss, Inc.
Influence of hypothalamic‐pituitary‐adrenocortical hormones on reproductive hormones in gray wolves (Canis lupus)
Authors: Kreeger Terry J. , Seal Ulysses S. , Plotka Edward D. 
Published: June 2005

AbstractThe release of hypothalamic‐pituitary‐adrenocortical hormones was studied in intact and neutered gray wolves (Canis lupus) to determine how these hormones interact and affect reproductive hormones. Experiments were performed on adult wolves anesthetized with 400 mg ketamine and 50 mg promazine. Intravenous (i.v.) injections with 50 μg ovine corticotropin releasing factor (oCRF) significantly increased adrenocorticotropin (ACTH; P ≤ 0.01), cortisol (CORT; P ≤ 0.004), and progesterone (P ≤ 0.036), but not β‐endorphin (P ≥ 0.52). Since neutered wolves demonstrated dose‐dependent elevations in response to ACTH, it was concluded that the progesterone was secreted from the adrenal gland. Basal luteinizing hormone (LH) concentrations in neutered wolves were similar before and 60 min after i.v. injection of 1, 5, or 25 IU ACTH (P ≥ 0.36) or 2.2 mg/kg cortisol (P = 0.42). Neither 25 IU ACTH (P = 0.55) nor 0.22 mg/kg dexamethasone (P = 0.49) altered the LH response to injection of LH releasing hromone in neutered wolves. Chronic administration of 0.22 mg/kg/day dexamethasone for 3 d did not alter baseline LH concentration (P = 0.75). Injection of 1.0 mg/kg naloxone (NAL), however, increased LH concentrations relative to baseline values in both intact (P = 0.032) and neutered (P = 0.0005) female wolves, but no in intact (P = 0.19) or neutered males (P = 0.07). These results indicated that in gray wolves (1) oCRF stimulated the release of pituitary and adrenal hormones in a fashion similar to that of other mammals; (2) the adrenal cortex was capable of secreting progesterone into the systemic circulation; (3) exogenous glucocorticoids did not alter LH concentrations; and (4) endogenous opioids may modulate LH secretion in female wolves. © 1992 Wiley‐Liss, Inc.
The possible role of vena cava peptides in regulation of the branchial hearts of Sepia officinalis L. (cephalopoda)
Authors: Fiedler Armin 
Published: June 2005

AbstractAn analysis was made of the effects of 5 neuropeptides on the isolated branchial heart of Sepia officinalis. There is evidence to suggest that these 5 neuropeptides occur in the neurosecretory system of the vena cava (NSV system) of cephalopods. YGGFMRFamide and oxytocin caused concentration‐dependent increases in pressure amplitude in the perfused preparations, with their effects on heart rate being negligible. The molluscan neuropeptide FMRFamide hardly had any effect on the branchial heart beat when applied alone, but it counteracted the positive inotropic actions of noradrenaline. FLRFamide and α‐melanotropin had no effect in our system. None of the peptides tested in bioassays on branchial hearts was as efficient as a perfusate obtained from the cephalic vein of Sepia (including the NSV area) that had been stimulated by electrical irritation of the attached visceral nerves. These findings suggest that there may be further neurohormones in the NSV system that are released into the vessel lumen. It is suggested that the branchial hearts of Sepia in vivo are influenced by humoral peptides from the NSV system and that these peptides may act directly on target myocytes or may alter (i.e., potentiate or oppose) the effects of other cardioactive compounds. © 1992 Wiley‐Liss, Inc.