bluuebunny/crossref_metadata_2025_split huggingface dataset:
Control of key carbohydrate‐metabolizing enzymes by insulin and glucagon in freshly isolated hepatocytes of the Marine teleost Hemitripterus americanus
Authors: Foster G. D. , Moon T. W. 
Published: June 2005

AbstractThe effects of scombroid insulin (10−7 M) and bovine glucagon (10−7 M) on key regulatory enzymes of glycolysis and gluconeogenesis are examined in freshly isolated hepatocytes of the sea raven, Hemitripterus americanus, following a 45 and 180 min incubation. Glucagon increased the Vopt of PEPCK, PK, GPT, and LDH, but decreased the substrate activity ratios of both PK and PFK‐1 (the latter only at inhibitory ATP concentrations) at 180 min. Glucagon also decreased Fru‐2,6‐P2 levels at both 45 and 180 min. Insulin decreased the Vopt for LDH at 180 min and decreased the F6P activity ratio for PFK‐1 at both 0.5 mM and 1.5 mM ATP at 45 and 180 min, with larger decreases occurring at the later time period (to 13% of the control value). Insulin also decreased Fru‐2,6‐P2 concentrations at 180 min and increased alanine uptake. PEPCK and PK were not affected by insulin. These data indicate that glucagon alters the characteristics of a variety of enzymes in the glycolytic/gluconeogenic sequence, while the major impact of insulin is at the level of PFK‐1 and alanine uptake.
Factors influencing the affinity and capacity of T3‐binding sites in hepatic nuclei of rainbow trout, Oncorhynchus mykiss
Authors: Bres O. , Cyr D. G. , Eales J. G. 
Published: June 2005

AbstractThe effects of several variables were tested on the in vitro binding affinity (Ka) and maximum binding capacity (MBC) of saturable 3,5,3′‐triiodo‐L‐thyronine (T3)‐binding sites (putative thyroid hormone receptors) extracted from hepatic nuclei of immature rainbow trout held on a 12L:12D photocycle at 12°C. Neither Ka nor MBC varied during the daily photocycle, nor were they influenced by the growth rate, food ration, or a 13‐fold chronic elevation in plasma T3. However, MBC was inversely correlated with fish size and was depressed significantly by two injections of 17β‐estradiol (E2) or starvation for 3 or 12 days. The Ka was uninfluenced in either case. Since both E2 and starvation also depress T3 levels in the blood, the decrease in MBC could be secondary to this change. The drug ipodate, which depresses plasma T3, also lowered the MBC. However, MBC remained low in ipodate‐treated trout given exogenous T3, thus suggesting that the effect of ipodate was not due to T3 deprivation. It remains to be shown, therefore, that plasma T3 depression itself can modify MBC. It is concluded that increasing body size and catabolic states, both of which are associated with a decrease in specific growth rate, tend to decrease the abundance of hepatic T3 receptors.
Purification and subcellular localization of Zn‐dependent acid p‐nitrophenylphosphatase in frog liver and comparison with other vertebrates
Authors: Panara F. , Massetti N. , Angiolillo A. , Fagotti A. , Pascolini R. 
Published: June 2005

AbstractZn2+‐dependent acid p‐nitrophenylphosphatase (Zn‐AcPase) from liver of Rana esculenta was purified to homogeneity. The purified enzyme moves as a single electrophoretic band at pH 8.3 in 7.5% acrylamide and was coincident with the enzyme activity. The enzyme has a molecular weight of 102,000 ± 5,000D and is a dimer with two apparently similar polypeptide chains of 48,000 ± 3,000D as determined by sodium dodecylsulfate gel electrophoresis. Zn‐AcPase from frog liver requires Zn2+ ions for catalytic activity; other bivalent cations have little or no effect. The enzyme with a pI of 7.07 does not appear to be a glycoprotein and was associated with the soluble fraction after liver cell fractionation.The biochemical and molecular properties of frog liver Zn‐AcPase were compared with that of the enzyme partially purified from carp (Cyprinus carpio), pike (Esox lucius), and rat (Rattus norvegicus).
Nutritional state modulates hormone‐mediated hepatic glycogenolysis in chinook salmon (Oncorhynchus tshawytscha)
Authors: Klee Michael , Eilertson Carmen , Sheridan Mark A. 
Published: June 2005

AbstractJuvenile chinook salmon were used to investigate the interaction of nutritional state and hormones (glucagon, epinephrine) on hepatic glycogenolysis. Experiments were conducted in vitro on liver removed from animals of varying nutritional states: fed 1 week, fasted 1 week, fed 3 weeks, fasted 3 weeks, and fasted 1 week/refed 2 weeks. Basal glycogen breakdown in liver isolated from continuously fed (1 week and 3 weeks) fish proceeded at insignificant levels, whereas glycogen breakdown in liver isolated from fasted animals progressed rapidly during the course of incubation. However, no difference in the pattern of glycogen breakdown between liver isolated from animals fasted for 1 week and those fasted for 3 weeks was observed. The presence of glucose in the incubation medium retarded glycogen breakdown in the livers from fasted fish. Both epinephrine and glucagon stimulated glucose release from liver isolated from fish fed continuously and from fish fasted 1 week; epinephrine appeared more potent in this regard than glucagon. Epinephrine also stimulated glucose release from liver isolated from fish fasted 3 weeks, whereas glucagon was without significant glycogenolytic effect on this tissue. Insulin inhibited epinephrine‐ and glucagon‐stimuluated glucose release. These results suggest that glucagon plays a role in modulating nutrition‐associated adjustments in metabolism during the early stages of fasting and that, with extended fasting, the liver loses its sensitivity to glucagon with regard to glycogenolysis.
Variability of the immune response in freshwater sponges
Authors: Van De Vyver G. , Holvoet S. , Dewint P. 
Published: June 2005

AbstractThe variability of the immune response of four species of freshwater sponges, common in Belgium, Ephydatia fluviatilis, Ephydatia mulleri, Spongilla lacustris, and Eunapius fragilis, has been analyzed at the cellular level.For each species, strains, which are the collection of all the sponge individuals able to fuse compatibly their aquiferous system, were collected in natural ponds and isolated.In most cases, the general immune response corresponds to a three‐step process restricted to the zone of contact. This process includes: the fusion of the sponges coming into contact, a local cell accumulation, and the separation of the alien sponges.The variability of the immune reaction mainly concerns the existence and the duration of the fusion step and the possible secretion of a collagen barrier between the separated alien sponges. In contrast, for all the combinations studied, the accumulated cells differentiate and organize themselves in two facing layers of pinacocytes.In some allocombinations, involving S. lacustris strain δ, a general reaction was recorded. In these pairings, after the initial fusion, the alien sponges undergo a temporary involution followed by the segregation and reconstitution of two separated functional sponges.Our exhaustive analysis leads to the conclusion that the alloimmune responses vary according to the species and even within a single species, according to the strains paired. In contrast, all the xenocombinations undergo a similar process consisting in the direct and complete separation of the sponges.These results demonstrate the possibility for freshwater sponges to diversify their responses to nonself and consequently to discriminate between different nonself.
Water channels and water canals in the gill of the freshwater mussel, Ligumia subrostrata: Ultrastructure and histochemistry
Authors: Kays W. T. , Silverman H. , Dietz T. H. 
Published: June 2005

AbstractThe apical surface of all epithelial cells of the gills of Ligumia subrostrata either are ciliated or contain microvilli or show both structures. The ciliated cells on the gill filaments direct water through the ostia at the base of each gill filament. All the water passing through the gills and out the exhalent siphon must pass through the narrow water canals and into the central water channels. All of the epithelial cells lining the lateral water canals are mitochondria‐rich. In addition, the central water channel epithelia contain clusters of mitochondria‐rich cells, but many of the epithelial cells are mitochondria‐poor. With the exception of the lateral ciliated cells, the lamellar epithelium of the surface filaments contains relatively mitochondria‐poor cells. The mitochondria‐rich epithelial cells of the water canals and water channel display the most histochemically intense reaction products for carbonic anhydrase and cytochrome oxidase. The mitochondria‐rich cells of the water canal and water channel epithelia may be the principal cells responsible for salt transport in these mussels.
Differential limb regeneration in diploid and triploid Rana pipiens larvae with reference to spinal motor neuron development
Authors: Pollack Emanuel D. , Maheras‐Rarick Helen M. 
Published: June 2005

AbstractDevelopmental manipulations that can alter nerve‐limb relationships can assist in understanding the neural control of limb regeneration. Pressure‐induced triploidy in Rana pipiens tadpoles results in alterations of the quantitative characteristics of the spinal motor neurons that innervate the limbs, whereas the limbs appear unaltered. Unilateral midthigh amputations at larval stages IX, XI, and XIII of diploid and triploid animals resulted in complete regeneration for only stage IX animals regardless of ploidy. Nevertheless, triploid limbs regenerated much faster than did diploids, an event that can be related to the differential dynamics of nerve fiber extension and/or the altered numbers and sizes of triploid spinal motor neurons. Although normal limb development from stage IX to the endpoint at stage XVIII was the same in diploids and triploids, the rate of regeneration in triploids was nearly twice that of diploids. The data of this noninvasive means of altering the quantitative relationship of nerve‐to‐peripheral target suggest a unique means of studying nerve‐dependent limb regeneration in an animal that progressively loses its regenerative capability during development.
Effect of temperature on gonadal sex differentiation in the sea turtle Lepidochelys olivacea: An organ culture study
Authors: Merchant‐Larios H. , Villalpando I. 
Published: June 2005

AbstractGonadal sex differentiation is controlled by the temperature of egg incubation in the sea turtle Lepidochelys olivacea. The physiological mechanism involved in this phenomenon is not understood. Here, we studied the differentiation of gonads isolated from embryos at different stages of development which previously had been incubated at either male‐ or female‐producing temperatures (28°C or 32°C respectively) and cultured at the alternative temperature. We found that morphologically bipotential gonads can undergo sexual differentiation in vitro. Under these conditions the sexual differentiation of isolated gonads was not influenced by the temperature during culture. However when whole embryos were further incubated, the gonads remained sensitive to incubation temperatures for at least three more stages of development. These results suggest that an extragonadal physiological mechanism may mediate the effect of temperature on gonadal sex determination.
Seasonal shifts in odor acuity by starlings
Authors: Clark Larry , Smeraski Cynthia A. 
Published: June 2005

AbstractA passerine bird, the European Starling Sturnus vulgaris, demonstrated a seasonal ability to respond to odor cues. Cardiac conditioned responses were most evident when birds were in breeding condition. Once birds were in nonbreeding condition, responding to odors all but ceased. For birds in breeding condition, threshold sensitivity to the odor cyclohexanone was comparable to levels reported for nonpasserine birds (0.3% vapor saturation or 3.778 × 1014 molecules/ml). In contrast, the threshold level during the postreproductive phase of the annual cycle was 10% vapor saturation (1.256 × 1016 molecules/ml). a level high enough to implicate the trigeminal system as the modality mediating chemosensory perception. The strong cyclic responding pattern suggests links between photoperiodically controlled endocrine production, breeding behavior, and olfactory sensitivity.
Testicular response to melatonin or suprachiasmatic nuclei ablation in the spotted skunk
Authors: Berria Matthew , Desantis Mark , Mead Rodney A. 
Published: June 2005

AbstractTestes of the Western spotted skunk enlarge and regress seasonally. The pineal hormone, melatonin, may be important in timing this seasonal reproductive activity. Likewise, the suprachiasmatic nuclei (SCN) have been implicated as possible neural regulators of pineal and reproductive events. These experiments were conducted to determine whether ablation of the SCN or constant administration of melatonin alters timing of the seasonal pattern of testicular regression and recrudescence. Male skunks (n = 24) were treated as follows: six received two empty Silastic capsules, six received two melatonin‐filled Silastic capsules, six received sham lesions to the SCN, and six received lesions to the SCN (SCNx). All skunks were exposed to a natural photoperiod and had regressed testes at the onset of the experiment. Four of six males from the SCNx group had an average of 94 ± 11.3% of these nuclei destroyed. Sham SCNx, animals with <40% of the SCN ablated, and males with empty capsules did not have fully enlarged testes until October. SCNx and melatonin‐treated skunks exhibited a hastening of testicular recrudescence with maximal testis size being reached in June. Skunks with lesions to the SCN maintained enlarged testes for 5 months while all other groups exhibited rapid regression after attaining maximal testis size. Testicular regression occurred from July through October in animals receiving continuous melatonin, while controls exhibited recrudescence during this same period. Our data suggest that the SCN, melatonin, and thus the pineal gland, play a role in regulating the seasonal testicular cycle of the spotted skunk.
The “love dart” of the snail Helix aspersa injects A pheromone that decreases courtship duration
Authors: Adamo Shelley A. , Chase Ronald 
Published: June 2005

AbstractDuring the courtship of Helix aspersa, the snails push calcareous darts into one another. To examine the importance f this unusual action for the normal expression of their sexual behaviour, one group of Helix aspersa was prevented from exchanging darts by surgically removing their dart sacs. Another group of Helix aspersa had their digitiform glands surgically removed. These glands secrete a mucus that coats the dart. Glandless snails were capable of exchanging darts, but the darts lacked their normal mucus coating. Both dartless and glandless pairs required more courtship time to reach copulation than did sham‐operated controls. Therefore, it appears that it is the mucus from the digitiform gland, not the mechanical action of the dart, which affects courtship duration.Injections of gland homogenate decreased the courtship duration of sexually receptive, dartless, and glandless snails. Gland homogenate also increased the size of the recipient's genital eversion, and retarded locomotion. The mucus was only effective if it entered the circulatory system of a sexually receptive snail at a specific stage of genital eversion.The active agent in the digitiform gland mucus fulfills the requirements for the substance to be classified as a pheromone. It enters the circulatory system of the conspecific via inoculation by the dart.
Development of monosex female Oreochromis mossambicus broodstock by integrating gynogenetic technique with endocrine sex reversal
Authors: Pandian T. J. , Varadaraj K. 
Published: June 2005

AbstractAll female Oreochromis mossambicus were produced by judiciously combining endocrine sex reversal with selective breeding as well as gynogenesis. The combination of gynogenesis and endocrine sex reversal doubled the number of sex reversed males (XX‐‘♂♂’) and reduced the time cost from 12 to 6 months, in comparison to those produced by the combination of endorcine sex reversal with selective breeding. Programmes for commercial production and maintenance of XX‐♂ and XX‐♀ broodstock for large‐scale production of monosex female and monosex triploid sterile female populations are presented.
Clinal variation in the specific activity of lactate dehydrogenase‐B
Authors: Crawford Douglas L. , Place Allen R. , Powers Dennis A. 
Published: June 2005

AbstractLDH‐B4 specific activity was determined from Fundulus heteroclitus collected in the field and from laboratory‐acclimated fish from four latitudinally distinct populations. The differences in the enzyme activity between populations for both field‐caught and laboratory‐acclimated fish are significant, with the northern populations having the highest LDH‐B4 enzyme activity. This clinal variation in enzyme activity is consistent with an evolutionary mechanism that compensates for lower environmental temperatures in colder northern latitudes.
Gastrointestinal transit and lipid assimilation efficiencies in three species of sub‐antarctic seabird
Authors: Jackson Sue , Place Allen R. 
Published: June 2005

AbstractUsing tritium‐labeled glycerol triether ([3H] GTE) as a nonabsorbable lipid‐phase marker and tritium‐labeled polyethylene glycol 4000 ([3H] PEG) as a nonabsorbable aqueous‐phase marker, we examined gastrointestinal transit of homogenized Antarctic krill (Euphausia superba) meals fed to white‐chinned petrels (Procellaria aequinoctialis), sooty albatrosses (Phoebetria fusca), and rockhopper penguins (Eudyptes chrysocome). The aqueous‐phase marker was excreted significantly more rapidly than was the lipid‐phase marker by the two procellariiform species, whereas no differential transit rates for the two markers were observed in the penguins. Aqueous‐phase marker recoveries after 48 hours from the three species were statistically indistinguishable (78.6% ± 3.7%, n = 5; 71.9% ± 11.3%, n = 7; and 77.0% ± 9.4%, n = 4, respectively). Lipid‐phase marker recovery from the penguins after 48 hours was nearly complete (83.8% ± 19.3%, n = 5, and 92.7% ± 14.8%, n = 5, for two dietary lipid supplements, see below), whereas less than 50% of the original dose of lipid marker was recovered from the two procellariiform species. Substantial lipid‐phase marker was recovered as stomach oils from the procellariiforms.Assimilation efficiencies of [1‐14C] tripalmitin dissolved in wax ester and [1‐14C] cetyl oleate dissolved in triglyceride were compared for the same three seabirds by comparing 3H/14C ratios in the food and feces of birds simultaneously fed one of the above 14C‐labeled lipids, and the non‐metabolizable marker [3H] GTE. The petrel and the albatross showed high assimilation efficiencies (> 80%) of both 14C‐labeled neutral lipids. Rockhopper penguins consistently excreted [3H] GTE faster than did adult sooty albatrosses and were significantly less efficient at assimilating both neutral lipids (62% and 45% respectively). Sooty albatross fledglings excreted lipids significantly more slowly than did adults of this species, but lipid assimilation efficiencies did not differ with age. Gut measurements showed that the intestine of the rockhopper penguin was three and six times as long as those of the sooty albatross and white‐chinned petrel respectively.
Regional variations in the tightness of the ectodermal epithelium in the developing chick embryo: A study using ion‐sensitive microelectrodes
Authors: Carnan Elspeth , Gillespie J. I. 
Published: June 2005

AbstractIn 2‐day‐old avian embryos there is a rosto‐caudal gradient of interstitial pH (Gillespie and McHanwell: Cell Tissue Res., 247:445–451, '87). Neither the developmental significance nor the basic cellular mechanisms underlying this phenomenon has been studied. The present paper provides information about the interstitial potassium and calcium ion concentrations and the movement of these ions across the ectodermal epithelium. The data suggests a possible explanation for the longitudinal pH gradient in the embryo.The concentrations of potassium and calcium ions in the interstitial spaces were measured with ion‐sensitive and conventional microelectrodes. In embryos bathed in solution containing 1 mM potassium, the potassium concentration in the region of the mesencephalon was 5.1 ± 0.7 mM while in the region of the unsegmented mesoderm it was significantly lower at 3.3 ± 0.4 mM (mean ± S.E., n = 16). If embryos are exposed to extra‐embryonic solutions containing 30 mM potassium, the K+ concentration in the mesencephalon is 13.0 ± 0.8 mM and higher at 15.4 ± 1.2 mM in the unsegmented mesoderm (n = 12). In embryos bathed in solutions containing 0.1 mM calcium, the interstitial calcium was found to be 1.1 ± 0.52 mM in the mesencephalon and 0.42 ± 0.19 mM in the unsegmented mesoderm (n = 3). In comparison, embryos bathed in solution containing 10 mM calcium had 1.9 ± 0.2 mM rostrally compared to 3.71 ± 0.63 mM caudally (n = 10). Thus it is possible to generate intra‐embryonic ion gradients dependent upon the extra‐embryonic ion concentration.These results show, firstly, that the rate of potassium exchange across the ectodermal epithelium is lower in the rostral regions compared to more caudal regions, suggesting a regional variation in the tightness of the epithelium. Secondly, unlike H+ ions, potassium and calcium ions are passively distributed across the ectodermal epithelium.The properties of the ectodermal epithelium are discussed in relation to the pH gradient and to their possible relevance to normal embryonic development.
Structural spermatophore proteins and a trypsin‐like enzyme from the accessory reproductive glands of the male grasshopper,Melanoplus sanguinipes
Authors: Cheeseman M. T. , Gillott C. , Ahmed I. 
Published: June 2005

AbstractSome of the major structural spermatophore proteins and a trypsin‐like enzyme have been identified from the accessory reproductive glands of the male migratory grasshopper,Melanoplus sanguinipes.Polyclonal antibodies raised against the purified major soluble spermatophore protein (SP62) of M, 62,000 were used in Western blots to identify a soluble Mr85,000 putative precursor protein and, by immunohistochemistry and by partial proteolysis with staphylococcal V8 protease followed by Western blotting, an insoluble putative precursor protein from short hyaline gland three (SH3). The protein SP62 was formed in vitro by the incubation of crude homogenates of accessory gland tissues, seemingly by an interaction between SH3 secretion and soluble proteins from the remainder of the gland complex. In addition to the immunological similarity between SH3 secretion and SP62, there was also a strong similarity between the amino acid compositions of SH3 secretion and sodium dodecyl sulfate (SDS)‐extracted spermatophores. A family of white gland proteins (designated A‐group white gland proteins; WGPA) that showed intermale and intergland variations were also structural spermatophore proteins. Reserves of the major Mr22,000 and 21,000 forms declined by about 24 μg at mating. Polyclonal antibodies raised against these Mrforms recognized an additional Mr28,200 form in white glands one to three and a Mr9,600 counterpart in white gland four. WGPA‐immunoreactive proteins were evidently incorporated into the spermatophore as insoluble products. Both WGPA and SP62 antigens were localized chiefly in the outermost layers of the spermatophore but also occurred in the inner core. Crude homogenates of accessory glands hydrolyzed three trypsin substrates and an aminopeptidase substrate. The role that these enzymes might play in spermatophore formation is discussed.