bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metabolic changes in coho and chinook salmon resulting from acute insufficiency in pancreatic hormones
Authors: Plisetskaya Erika M. , Sheridan Mark A. , Mommsen Thomas P. 
Published: June 2005

AbstractAcute deficiency in pancreatic peptides (insulin, somatostatin‐25, glucagon, and glucagon‐like peptide) was invoked for 9–12 hr in coho, Oncorhynchus kisutch, and chinook, O. tshawytscha, salmon by administration of specific antisera raised against purified salmon hormones.Insulin‐deficient fish were hyperglycemic, had diminished glycogen content in the liver (Plisetskaya et al., '88a, elevated liver triacylglycerol lipase activity, and higher concentration of plasma triiodothyronine (T3) compared to a control group of fish injected with nonspecific rabbit serum. After immunoneutralization of somatostatin‐25, fish remained normoglycemic, with higher liver glycogen content, decreased lipase activity, and elevated plasma levels of insulin, while the levels of T3 declined. The induced deficiency in glucagon family peptides led to comparatively smaller changes: liver glycogen content was increased after anti‐glucagon‐like peptide (aGLP) injection and transient hyperglycemia was apparent following anti‐glucagon (aGLU) administration. Circulating levels of insulin remained unaffected for at least 9 hr following aGLU and aGLP treatments. The velocity of pyruvate kinase at 2.5 mM phosphoenolpyruvate (V2.5) was depressed, especially after the combined administration of aGLU + aGLP.The effectiveness of immunoneutralization experiments was greatly dependent on the particular stage of the fish life cycle. Antisera against fish pancreatic peptides proved to be a suitable tool in the studies of hormonal regulation of fish metabolism.
Farnesoic acid as a major product of release from crustacean mandibular organs in vitro
Authors: Tobe S. S. , Young D. A. , Khoo H. W. , Baker F. C. 
Published: June 2005

AbstractIncubation of mandibular organs (MO) from the crab Scylla serrata with medium containing [2‐14C]‐acetate and [methyl‐3H]‐methionine results in the biosynthesis and release of, predominantly, farnesoic acid and of methyl farnesoate. The identity of each was confirmed by liquid chromatography and gas chromatography/mass spectrometry (GS/MS). Farnesoic acid is released into the incubation medium at a rate tenfold greater than methyl farnesoate. Release of the acid was linear over an 8‐hr incubation period. However, the amount of farnesoic acid within the MO did not equal the quantity of methyl farnesoate in the glands. Analysis of haemolymph extracts by GC/MS confirmed the presence of methyl farnesoate but farnesoic acid was not detected. These data suggest that farnesoic acid is released by the MO of S. serrata and either rapidly metabolized or sequestered by the tissues. It is possible that farnesoic acid may be a prohormone and converted into other isoprenoid products.
Some effects of salmon calcitonin on calcium metabolism in the crustacean Orchestia during the molt cycle
Authors: Sellem Evelyne , Graf Fraņclois , Meyran Jean‐claude 
Published: June 2005

AbstractIn the terrestrial amphipod Orchestia cavimana, investigations of the variations of the total hemolymphatic calcium during the normal molt cycle revealed that a calcium balance is maintained in intermolt, as observed in numerous crustaceans. During premolt, hypercalcemia occurs, related to the marked calcium reabsorption from the old cuticle, which may promote the storage of a part of this calcium within the midgut posterior caeca. The calcium levels fall after exuviation to late postmolt to the low basal levels of intermolt; this may reflect the imbalance between the rates of calcification of the newly secreted cuticle and uptake of calcium within the posterior caeca.Administration of salmon calcitonin lowers calcium levels in intermolt and early premolt, when endogenous calcitonin‐like activity and ecdysteroid titers are low, but has no effect in late premolt when endogenous calcitonin‐like activity is important.
Time‐ and temperature‐dependent appearance of vitellogenin in Golgi vesicles and serum after estrogen treatment of salmon (Salmo salar)
Authors: Olin T. , Westman A. , von der Decken A. 
Published: June 2005

AbstractThe temperature‐dependent time course of vitellogenesis was examined in presmolt salmon (Salmo salar). Fishes were kept at 8°C or 16°C and injected with 17‐β‐estradiol. The rise in translation activity in liver preceeded that of RNA. At both acclimation temperatures, vitellogenin appeared in the Golgi vesicles at 3 days after the initial hormone injection. At 8°C, vitellogenin was detectable in the serum on day 7 and at 16°C on day 3 after the initial hormone treatment. At 8°C, protein synthesis per g wet weight of liver as well as vitellogenin content in the Golgi vesicles and in serum continued to rise during the 2 weeks of treatment. At 16°C, protein synthesis per g wet weight of liver reached a plateau during the second week of hormone treatment. A similar trend was seen in the vitellogenin content in the Golgi vesicles and the serum, suggesting a limiting step in either the translation or the export process of the protein at elevated temperature. The results indicate a correlation between translation activity, accumulation of vitellogenin in the Golgi vesicles, and concentration of vitellogenin in the blood.
β‐Adrenergic blockers prevent short photoperiod‐induced gonadal regression, but not melatonin‐induced regression in male syrian hamsters
Authors: Champney Thomas H. 
Published: June 2005

AbstractPineal melatonin synthesis is regulated by norepinephrine at β‐adrenergic receptors on pinealocytes. Melatonin released from the pineal is believed to be responsible for short photoperiod‐induced gonadal regression. By blocking melatonin production at the β‐adrenergic receptor with β‐adrenergic antagonists, short photoperiod‐induced gonadal regression was prevented. Propranolol or nadolol injected daily in the late afternoon prohibited short photoperiod‐produced testicular regression in male Syrian hamsters. Likewise, propranolol and nadolol pellets were able to block short photoperiod‐induced gonadal regression. Interestingly, in the presence of β‐adrenergic antagonists, gonadal regression was still produced by daily afternoon injections of melatonin. These results indicate that propranolol or nadolol can be used to “pharmacologically pinealectomize” hamsters and block the physiological action of the pineal.
Development of porcine embryos from the one‐cell stage to blastocyst in mouse oviducts maintained in organ culture
Authors: Krisher Rebecca L. , Petters Robert M. , Johnson Bryan H. , Bavister Barry D. , Archibong Anthony E. 
Published: June 2005

AbstractSuccessful development of porcine embryos from the one‐cell stage to the blastocyst stage has been accomplished using mouse oviducts in organ culture. One‐cell embryos were transferred to mouse oviducts maintained in organ culture and were cultured for 6 days. Control embryos from each donor pig were cultured in a modified Krebs‐Ringer bicarbonate medium. Thus control and experimental embryos obtained from the same individual pig could be directly compared. At the end of the culture period, all embryos were scored for the stage of development attained and stained to allow the cell number of each embryo to be counted. In medium alone, only 35.7% of the one‐cell embryos reached the morula or blastocyst stage, whereas 78.1% of the one‐cell embryos transferred to mouse oviducts reached the morula or blastocyst stage. Of those embryos reaching the morula or blastocyst stage, cell numbers were similar for the two treatments (medium alone vs. oviduct culture). The procedure described for mouse oviduct organ culture provides a simple method for culturing early‐stage pig embryos to the morula or blastocyst stage prior to embryo transfer.
Fate mapping the avian neural plate with quail/chick chimeras: Origin of prospective median wedge cells
Authors: Schoenwolf Gary C. , Bortier Hilde , Vakaet Lucien 
Published: June 2005

AbstractThe origin of prospective M cells, which are median neuroepithelial cells that become wedge‐shaped during bending of the neural plate and eventually form the midline floor of the neural tube, was determined by constructing quail/chick chimeras and using the quail nucleolar marker to identify quail donor cells in chick host blastoderms. Two possible sites of prospective M‐cell origin in the epiblast were examined: a single, midline rudiment located just rostral to Hensen's node and paired rudiments flanking the cranial part of the primitive streak. Our results suggest that M cells arise exclusively from the midline, prenodal rudiment. From this rudiment, M cells extend caudally throughout the entire length of the neuroepithelium. This new information on the origin of prospective M cells will aid in the analysis of their role in neurulation.
Induction of the acrosome reaction in ejaculated goat spermatozoa by preincubation in chemically defined medium
Authors: Kusunoki Hiroshi , Sakaue Morito , Kato Seishiro , Kanda Sunao 
Published: June 2005

AbstractThe aim of the present study was to examine the effects of the elimination of energy substrate from the medium and the effects of the preincubation vessel, temperature, and time on the induction of the acrosome reaction in ejaculated goat spermatozoa in chemically defined medium. Washed spermatozoa were resuspended in Brackett–Oliphant (BO) medium or substrate‐free BO medium to give a high concentration and preincubated in open test tubes or sealed glass tubes at 37.0 or 39.5°C for 1, 2, or 3 h. Sperm acrosome reaction was evaluated using a simplified triple‐stain technique and a hamster test. It was found that the goat sperm acrosome reaction occurred more readily in the sealed glass tubes than in open test tubes, in substrate‐free BO medium than in BO medium, and at 39.5 than at 37.0°C. During preincubation with substrate‐free BO medium in sealed glass tubes at 39.5°C, the optimum time necessary to induce the acrosome reaction in goat spermatozoa was 2–3 h.
Catecholamine release by catecholamines in the eel does not require the presence of brain or anterior spinal cord
Authors: Hathaway Charles B. , Brinn Jack E. , Epple August 
Published: June 2005

AbstractThe catecholamine‐producing chromaffin cells of the American eel are strongly innervated by fibers, which, by ultrastructural criteria, seem to be cholinergic. However, neither removal of the brain nor removal of the brain combined with extirpation of the anterior spinal cord prevents the release of catecholamines into the circulation by catecholamines. It appears that the chromaffin cells are controlled by both nervous and humoral stimuli, and that at least some of the latter do not require the presence of “preganglionic” innervation.
Evidence that somatic and sympathetic nervous system neurotransmitters, not circulating epinephrine, mediate the immediate responses to a sudden threat in the American alligator (Alligator mississippiensis)
Authors: deRoos Roger , Rumpf Ronald P. , Berry Michael W. 
Published: June 2005

AbstractThe qualitative and quantitative temporal effects of a 2‐min handling stress, both with and without pretreatment with tubocurarine, and the intraaortic infusion of epinephrine, both with and without pretreatment with a combination of phentolamine and propranolol, on plasma lactate, glucose, and hematocrit levels were compared in the American alligator (Alligator mississippiensis). The drugs and epinephrine were administered, and serial blood samples were collected, via a nonocclusive cannula chronically placed in the left aortic arch. Plasma lactate and glucose were measured by standard enzymatic procedures. Plasma lactate rose approximately 92% by the end of the 2‐min handling period and to maxima of 1,091 ± 476% greater than the time‐zero levels by 15 min. The hematocrit also increased rapidly to maxima of 11 ± 3.1% greater than the time‐zero levels by 5 min. Plasma glucose levels did not change significantly. The handling‐induced lactate and hematocrit increases were prevented by pretreatment with tubocurarine that blocks acetylcholine receptors at the skeletal muscle neuroeffector junction. Epinephrine infusion resulted in delayed, comparatively slow increases in plasma lactate, glucose, and the hematocrit. The peak levels for lactate were 334 ± 92% by 6 hr, for glucose were 135 ± 8% by 90 min, and for hematocrit were 10.9 ± 5.6% by 90 min. Pretreatment with the combination of phentolamine and propranolol that blocks mammalian “alpha” and “beta” adrenergic receptors, respectively, prevented the epinephrine‐induced increases in glucose and hematocrit levels, but not the plasma lactate increases. The results support the conclusion that the immediate responses of the alligator to a sudden threat are mediated by the synergistic effects of the somatic nervous system neurotransmitter acetylcholine, released at the skeletal muscle neuroeffector junction, and the sympathetic nervous system neurotransmitter (presumably norepinephrine), released at the neuroeffector junctions of the relevant visceral tissues and organs. In contrast, the participation of adrenal chromaffin tissue epinephrine secretion in the immediate responses is precluded by the long circulation and response times.
Temporal separation of rhabdom shrinkage and mvb formation in the light‐adapting crayfish retina
Authors: Piekos W. Barry 
Published: June 2005

AbstractBy using experimental light regimes, it is possible to alter independently the timing of both multivesicular body (MVB) production and decreases in rhabdom diameter. As a result, two distinct phases of MVB synthesis are revealed, neither of which appears temporally linked to rhabdom shrinkage. This supports the idea that MVB production and diminishing rhabdoms are not causally related in the manner predicted by the lysosome‐related‐body (LRB) hypothesis of rhabdom cycling. Furthermore, a statistically significant relationship is found between midday rhabdom enlargement and a decrease in the fractional volume of MVBs.
Notochordal induction of cell wedging in the chick neural plate and its role in neural tube formation
Authors: Smith Jodi L. , Schoenwolf Gary C. 
Published: June 2005

AbstractCells in the median hinge point (MHP) of the bending chick neural plate are tightly apposed to the underlying notochord. These cells differ from those in adjacent lateral neuroepithelial areas (L) in that MHP cells are short and mainly wedge‐shaped and line a furrow, whereas L cells are tall and mainly spindle‐shaped and do not line a furrow. Cell generation time also differs in these regions. These consistent differences are detectable only after the notochord has formed and established contact with the neural plate; it is unclear whether they result from self‐differentiation or induction. Two experiments were performed to evaluate the hypothesis that MHP characteristics develop owing to inductive interactions between the notochord and overlying neuroepithelial cells. First, notochordless chick embryos were generated to determine whether midline neuroepithelial cells still developed typical MHP characteristics. In the absence of the notochord, such characteristics did not develop. Second, isolated segments of quail notochord were transplanted subjacent to L of chick hosts to ascertain whether the notochord is capable of inducing MHP characteristics in L cells. When transplanted notochordal segments established apposition with host L cells, the apposing L cells usually developed typical MHP characteristics. Collectively, these results provide strong evidence that the notochord plays an inductive role in the formation of MHP characteristics. This investigation further revealed that bending can occur in the absence of MHP characteristics, forming a neural tube with an abnormal morphology. Thus, the formation of such characteristics, particularly cell wedging, is not required for bending but plays a major role in generating the normal cross‐sectional morphology of the neural tube.
Steady‐state and dynamic properties of photomechanical light and dark adaptation in the eye of the shrimp Eualus gaimardii (crustacea, natantia)
Authors: Nordtug Trond , Krekling Sturla 
Published: June 2005

AbstractA reflectometric method was used to study dark and light dark adaptation in shrimps (Eualus) by recording the reflectometric response to alternating periods of light‐off and light‐on that varied in intensity. We found that 1) During light‐off and light‐on periods the response slowly attained an upper and lower asymptotic level, respectively, followed by a steady‐state phase of these levels. The steady‐state level correlated strongly with the position of the distal screening pigment. 2) Steady‐state response plotted against log intensity defined an intensity‐response function representing the dynamic range of the distal pigment and consequently that of the effective aperture. The threshold where the pigment departed from its fully light‐ and dark‐adapted position was 10−5.5 and 10−9.5 W/cm2, respectively. Over this interval the intensity‐response function was linear and the increase in effective aperture equalled about .5 log unit gain in image brightness per log unit change in intensity. 3) The intensity‐response function showed cyclic shifts along the intensity continuum caused by endogeneous factors. 4) The duration of light adaptation was constant while rate of change increased linearly as a function of log intensity. Dark adaptation had similar properties at low intensities, thereafter its rate of change was constant while the duration increased linearly. These findings are consistent with the idea that the distal pigment is controlled by two hormones, the dark‐adapting hormone being subordinated to the light‐adapting one. Both the size of the dynamic intensity range and the temporal properties of light and dark adaptation showed that the photomechanical mechanism is well adapted to cope with twilight viewing conditions.
Changes in ornithine decarboxylase activity and polyamine content and effects of polyamine inhibitors in the regenerating planarian Dugesia (G) tigrina
Authors: Saló Emili , Baguñà Jaume 
Published: June 2005

AbstractOrnithine decarboxylase (ODC), the diamine putrescine, and the polyamines spermidine and spermine have been shown to be present in the intact and regenerating planarian Dugesia (G) tigrina. As early as 1 hour after cutting, ODC activity increases, with maxima at 8 hours and 2 days of regeneration, mainly in regions near the wound. Putrescine varied like ODC, with maxima at 8 hours and 3 days, when cell proliferation is highest, whereas spermidine and spermine had lesser and later increases, merely in regions near the wound, with peaks at 5 days of regeneration when cell differentiation is greatest. The inhibitors of polyamine synthesis difluoromethylornithine (DFMO) and methylglyoxal bis(guanylhydrazone) (MGBG) decreased the levels of putrescine, spermidine, and spermine and lowered the rates of cell proliferation and differentiation. DFMO especially decreased the level of putrescine and the rate of cell proliferation, whereas MGBG reduced mainly the levels of spermidine and spermine and the rate of cell differentiation. On the basis of these observations, we suggest that, in planarian regeneration, ODC and putrescine are mainly involved in the control of cell proliferation, whereas spermidine and spermine are more related to cell differentiative processes.
Bacterial action of fertilization envelope extract from eggs of the fish Cyprinus carpio and Plecoglossus altivelis
Authors: Kudo Shigeharu , Inoue Matsuhisa 
Published: June 2005

AbstractThe vitelline envelope (VE) and fertilization envelope (FE) in eggs of the fish Cyprinus carpio and Plecoglossus altivelis were purified by homogenization of eggs or embryos in 5 mM Tris—HCl buffer, pH 7.0, containing 2 mM ethylenediamine tetraacetic acid disodium salt (EDTA), except for processing of VEs in Plecoglossus eggs, and by repeated washing with the same buffer. To extract the outermost layer material, the purified VEs and FEs were processed overnight at 4°C in 5 mM Tris‐HCl buffer, pH 7.0, containing 8 mM 2‐mercaptoethanol, 2 mM EDTA, 0.3 M α‐lactose, 0.3 M glucose, and 0.9% NaCl. Since extraction of the outermost layer of the VEs of Cyprinus eggs in this solution was found to be ultrastructurally incomplete, further sonication in the same buffer was necessary. The solution extracted from purified VEs or FEs was dialyzed against 5 mM Tris‐HCl buffer, pH 7.0, followed by lyophilization. The extracts from the FEs from both fish species contained two kinds of lectins, one agglutinated human B‐type erythrocytes and the other nonspecifically agglutinated fish spermatozoa, and both extracts had a strong bactericidal effect on Vibrio anguillarum that was isolated from diseased cultured fish, but not on Aeromonas hydrophila and Escherichia coli. The extracts of purified VEs from eggs of both fish had no bactericidal effect on the bacteria examined, nor any agglutination effect on human erythrocytes and fish spermatozoa.
Effect of sensory input from the tongue on jaw movement in normal feeding in the opossum
Authors: Thexton A. J. , Crompton A. W. 
Published: June 2005

AbstractOpossums were presented with solid and liquid foods. The movements of the jaw and tongue were recorded cineradiographically together with recordings of the EMG activity in muscles opening the jaw and moving the base of the tongue (hyoid). The jaw opening in each cycle was in two stages–01 and 02; 01 had a constant amplitude irrespective of the food ingested. Ingestion of liquid (which involved continuous accumulation of a liquid bolus in the valleculae prior to swallowing) was associated with cycles of oral movement in which 02 was small; tongue retraction was associated with this opening. In contrast, solid and semisolid food ingestion was associated with large angles of jaw opening in 02 that also coincided with the tongue retraction. In this latter case a characteristic pattern of EMG activity, in which all the muscles moving the hyoid were simultaneously active, was added to the pattern seen in lapping; this additional activity had an EMG pattern that was consistent with a jaw opening reflex. The findings contrast with other reports that the jaw opening reflex is suppressed in mastication. Experimentally induced tongue contact with a variety of solid surfaces during lapping (an activity involving accumulation of a liquid bolus in the valleculae) induced neither increased jaw opening nor the additional EMG pattern. However, in situations when there was no bolus in the valleculae, additional jaw opening activity was elicited when the tongue contracted solids intra‐ or extra‐orally. It is suggested that the ability of sensory input, from the anterior tongue, to elicit a jaw opening reflex and to change the type of jaw/tongue cycle was dependent upon the extent of bolus accumulation in the valleculae and therefore indirectly upon the consistency of the food.