bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential degradation of myofibrillar proteins by four calcium‐dependent proteinase activities from lobster muscle
Authors: Mattson Joanne M. , Mykles Donald L. 
Published: June 2005

AbstractFour calcium‐dependent proteinases (CDPs I, IIa, IIb, and III) were isolated from lobster claw and abdominal muscles. In order to determine the substrate specificities of the CDPs, each enzyme was incubated with either native purified myosin or actomyosin from lobster deep abdominal muscles. After incubation in the presence or absence of 5 mM Ca2+, reaction mixtures were separated by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and examined in 2 ways: (1) the fragment patterns from the degradation of the myosin heavy chain were identified with immunoblotting, and (2) gels were stained with Coomassie blue and densitometrically scanned to quantify the degradation of the major myofibrillar proteins. CDPs IIa and IIb were the most effective in degrading myosin heavy chain, actin, troponin‐T2, tropomyosin, troponin‐I1 and ‐I5, troponin‐C1, and myosin β‐light chain; the major difference between the 2 enzymes was that CDP IIa also degraded myosin α‐light chain. CDP III effectively hydrolyzed myosin heavy chain, actin, troponin‐T2, tropomyosin, troponin‐I5, troponin‐C1, and myosin β‐light chain. CDP I was the least efficient of the 4 CDPs in degrading myofibrillar proteins; only actin, troponin‐T2, and troponin‐I5 were readily hydrolyzed. All the CDPs recognized similar cleavage sites within the myosin heavy chain, since the proteolytic fragment pattern produced by each enzyme on the myosin heavy chain in reaction mixtures containing either actomyosin or myosin was essentially identical. These results show that the 4 CDPs share catalytic properties but differ in substrate specificities, particularly when presented with a complex assemblage of potential substrates. © 1993 Wiley‐Liss, Inc.
Brain evolution in decapod crustacea
Authors: Sandeman D. C. , Scholtz G. , Sandeman R. E. 
Published: June 2005

AbstractA survey of the morphology of the brains (cerebral ganglia) of 13 species of decapods shows that all have common areas of neuropil that are developed to differing degrees in the different groups. The neuropils of the paired accessory lobes, however, appear to have evolved de novo in the Reptantia. Phylogenetic relationships within the Reptantia suggest that the accessory lobes were initially large but became reduced in size during the evolution of the brachyurans and anomalans. © 1993 Wiley‐Liss, Inc.
Uncoupling the correlates of locomotor costs: A factorial approach
Authors: Myers M. J. , Steudel K. , White S. C. 
Published: June 2005

AbstractAlthough the metabolic cost of running has been found to vary systematically with running speed and body mass in animals, no mechanistic model of cost determination has been widely accepted. Because two suggested cost determinants—mechanical power output and the rate of force application—covary with running speed when gait (stride frequency) is unconstrained, examining the influence of each factor on cost has been problematic.We experimentally uncoupled the usual relationships between three readily manipulated cost correlates—speed, stride frequency, and mass distribution—to study the determinants of the cost of running in humans along a section of the cost response surface. Two levels of each cost correlate were used in a factorial design in which subjects ran at all eight combinations of factor levels while rate of oxygen consumption (
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), mechanical power, and contact time were measured as response variables. Contact time and mechanical power were measured from high‐speed cinefilm.Mechanical power accounted for 88%, and contact time (rate of force application) 57%, of speed‐related
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variation. Variation in cost produced by changes in stride frequency and mass distribution were largely explained by mechanical power. Contact time was not significantly correlated with overall variation in
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, while mechanical power output explained 80% of that variation. For the range of conditions tested, we conclude that the mechanical power derived from muscular contractions is an important determinant of the cost of running. While we have shown that the rate at which muscles shorten is not the sole determinant of the cost of running, the extent to which this factor influences cost remains unclear. © 1993 Wiley‐Liss, Inc.
Functional and structural characterization of hemocytes of the solitary ascidian, Halocynthia roretzi
Authors: Azumi Kaoru , Satoh Noriyuki , Yokosawa Hideyoshi 
Published: June 2005

AbstractIn invertebrates, hemocytes play important roles in defense mechanisms. The hemocytes of a solitary ascidian, Halocynthia roretzi, are a source of two antibacterial substances (halocyamines) and a lipopolysaccharide‐binding (LPS‐binding) hemagglutinin that is capable of agglutinating various bacteria. Furthermore, a metallo‐protease is released from the hemocytes in response to treatment with LPS, a calcium ionophore, or phorbol ester. In the present study, we attempted to fractionate the hemocytes to determine which of them contain the LPS‐binding hemagglutinin and release the metallo‐protease in response to various stimuli. The hemocytes of H. roretzi can be separated into five groups (L1‐L5) by discontinuous density gradient centrifugation in a solution of bovine serum albumin. The various populations of hemocytes exhibit structural differences that can be monitored by electron microscopy and flow cytometric analysis. The LPS‐binding hemagglutinin, together with halocyamines, was found in group L5, which consists of only one type of hemocyte. The hemocytes in groups L1, L3, and L4 released the metallo‐protease in response to various stimuli, whereas at least those in group L5 did not. These results indicate that the various groups of hemocytes of H. roretzi can be distinguished functionally from one another on the basis of cellular responses and the ability to produce defense substances. © 1993 Wiley‐Liss, Inc.
Comparison of the renal sodium‐D‐glucose cotransporter in marine organisms
Authors: Morrison‐Shetlar Alison I. 
Published: June 2005

AbstractA phylogenetic comparison of the structural and functional properties of the sodium‐D‐glucose cotransporter from a variety of marine species is presented. Found in the apical membrane of epithelial cells of kidney and intestine, this transport protein mediates the uphill movement of glucose coupled to the downhill movement of sodium ions. Monoclonal antibodies to the rabbit cotransporter react with a 78,000 Da protein in renal brush border membranes from skate, dogfish, and flounder, but not toadfish (which lacks functional expression of the cotransporter). Amplification of cotransporter DNA sequences by the polymerase chain reaction correlates well with the antibody results. Additional molecular studies of the sodium‐D‐glucose cotransporter promise to elucidate further the structure‐function relationship, particularly with respect to species‐specific stoichio‐metries. © 1993 Wiley‐Liss, Inc.
Effects of growth rate, temperature, season, and body size on glycolytic enzyme activities in the white muscle of atlantic cod (Gadus morhua)
Authors: Pelletier Dany , Guderley Helga , Dutil Jean‐Denis 
Published: June 2005

AbstractIn the fast‐growing Atlantic cod (Gadus morhua), the specific activities of the glycolytic enzymes phosphofructokinase (PFK), pyruvate kinase (PK), and lactate dehydrogenase (LDH) in white muscle were positively correlated with growth rate. For PFK and PK, season modified the relationship between growth rate and enzyme activity. This effect may be due to differences in the initial condition of the fish used for the experiments in the different seasons. Acclimation temperature only affected the activity of LDH, but its effect was slight compared to that of growth rate and season. No relationship was found between glycolytic enzyme activities in white muscle and body size of wild cod ranging from 20 to 80 cm in length. These relationships suggest that in their natural habitat, cod are opportunistic feeders which increase the metabolic capacities of their muscles once food becomes available. © 1993 Wiley‐Liss, Inc.
Melatonin‐induced desensitization in amphibian melanophores
Authors: Rollag Mark D. , Lynch G. Robert 
Published: June 2005

AbstractVideo‐microscopic examination of pigment granule translocation in cultured amphibian melanophores provides continuous, real‐time observation of cellular responses to hormonal and pharmacologic agents and is particularly useful for studying the mechanisms underlying melatonin‐induced pigment aggregation. We have used such video‐microscopic technology to show that pigment cells become refractory to prolonged melatonin treatment and that the speed at which the desensitized condition becomes evident is dependent upon the countervailing concentration of antagonistic hormone, alpha‐melanocyte stimulating hormone (MSH). When melanophores were treated with 10 nM melatonin, desensitization occurred within 30 minutes in the presence of 5 ng/ml MSH, whereas five hours of melatonin treatment was required before the desensitized state was observed in the presence of 1 ng/ml MSH. The persistence of desensitization after melatonin removal depends upon the duration of initial melatonin exposure. When melanophores were treated with melatonin (10 nM) in the presence of 10 ng/ml MSH for two hours, the desensitized condition lasted less than 30 minutes; if the initial melatonin treatment was increased to four hours, however, the melanophores remained in the desensitized state for more than two hours after the melatonin was removed from the medium. During the course of these treatments, there was no substantial degradation of melatonin activity; i.e., a second population of melanophores responded normally to the melatonin‐containing media overlying desensitized melanophores. © 1993 Wiley‐Liss, Inc.
Stage‐related production of 21‐hydroxylated progestins by the dogfish (Squalus acanthias) testis
Authors: Barry Terence P. , Thomas Peter , Callard Gloria V. 
Published: June 2005

AbstractUsing shark (Squalus acanthias) testicular microsomes and [3H]progesterone ([3H]P) and [3H]17α‐hydroxyprogesterone ([3H]17α‐P) and [3H]17α‐hydroxyprogesterone ([3H]17α‐P) as substrates, two major products of 21‐hydroxylase action were identified; respectively, 21‐hydroxy‐4‐pregnen‐3‐one (11‐deoxycorticosterone, DOC) and 17α,21‐dihydroxy‐4‐pregnen‐3‐one (11‐deoxycortisol, S). Additional products of 17α‐hydroxylase/C‐17,20‐lyase action were detected: 17α‐hydroxyprogesterone (17αP), testosterone (T), and androstene‐dione (AE). When microsomes derived from tissues in premeiotic (PrM), meiotic (M), and postmeiotic (PoM) stages of spermatogenesis were compared, maturation‐related increases were observed with both 21‐hydroxylase (3‐ to 20‐fold) and 17 α‐hydroxylase (2‐ to 6‐fold). With [3H]P as tracer, the half‐maximal substrate concentrations (Km = 0.2–1.0 μM) and maximal reaction velocities (Vmax = 9–25 pmol/mg protein/min) were similar for both enzymes when assayed in the same preparation, suggesting they compete for available substrate. Also, the presence of 1‐ or 10‐fold molar excess radioinert DOC reduced conversion of [3H]P to 17α‐hydroxylated products. [3H]DOC itself was a substrate of 17α‐hydroxylation but not C‐17,20‐lyase action. Expression of 21‐hydroxylase and 17α‐hydroxylase activities in cultured spermatocysts (intact germ cell/Sertoli cell units) was confirmed by detection of immunoreactive 17α,20β,21‐trihydroxy‐4‐pregnen‐3‐one (20β‐S), S, 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (17α,20β‐P), DOC, P and T in spent media. 20β‐S and S secretion increased and 17α,20β‐P decreased progressively with stage of maturation, but DOC was similar in all stages. P secretion was maximal and T lowest in M‐stage spermatocysts, but when DOC (0.1 μM) was added to PrM or PoM spermatocysts, T output decreased. Taken together, the data suggest that 21‐hydroxylating pathways, via direct and indirect mechanisms, affect accumulation of bioactive steroids (P and T) differentially by stage of spermatogenic development. Whether 21‐hydroxylated progestins produced in shark testis have paracrine or endocrine actions in their own right remains to be investigated. © 1993 Wiley‐Liss, Inc.
Similar responses to pharmacological agents of 1,2‐OAG–induced compaction‐like adhesion of two‐cell mouse embryo to physiological compaction
Authors: Ohsugi Mami , Ohsawa Takuro , Semba Reiji 
Published: June 2005

AbstractA comparison was made of responses to pharmacological agents between cell adhesion induced by an activator of Ca2+‐phospholipid‐dependent protein kinase (PKC) and physiological compaction in mouse embryos. An activator of PKC, 1‐oleoyl‐2‐acetyl‐sn‐glycerol (1,2‐OAG) induced the compaction‐like adhesion of cells in two‐cell embryos within 5–10 min and the adhesion lasted during the course of treatment for 1 h. W‐7 and W‐5 (calmodulin antagonists) and cytochalasin B and cytochalasin D (inhibitors of the polymerization of microfilaments) each completely interfered with the 1,2‐OAG–induced adhesion of cells. Two‐cell embryos having once shown evidence of cell adhesion in response to 1,2‐OAG were decompacted when they were transferred to a medium that contained 1,2‐OAG and any one of the agents described above. Colchicine and colcemid (inhibitors of the polymerization of microtubules) and tunicamycin (an inhibitor of N‐linked protein glycosylation) each had no effect on the 1,2‐OAG–induced adhesion of cells. In Ca2+ ‐free medium, treatment with 1,2‐OAG failed to induce any cell adhesion. These results are very similar to those reported for physiological compaction at the late eight‐cell stage. Thus, the compaction‐like adhesion of cells in mouse embryos at the two‐cell stage appears to be a calmodulin‐dependent process, requiring assembled microfilaments and extracellular Ca2+ ions but not microtubules or N‐linked glycoproteins as is the case for the physiological compaction. © 1993 Wiley‐Liss, Inc.
Cloning and chromosomal mapping of mouse seminal vesicle protein F
Authors: Yoo‐Warren Heeja , Willse Ann Gore , Hull Jacqueline , Brownell Elise 
Published: June 2005

AbstractSeminal vesicle proteins (SVPs) are made by male rodents, and form the copulatory plug following mating. Here we report a partial nucleotide sequence of a mouse clone homologous to rat SVP F. Unexpectedly, we found that SVP F‐related transcripts are expressed at high levels in mouse skeletal muscle. We mapped mouse SVP F to mouse chromosome 15 using somatic cell hybrid lines. © 1993 Wiley‐Liss, Inc.
Modulatory effects of adenosine on Porichthys luminescence
Authors: Mallefet J. , Baguet F. , Fauville C. 
Published: June 2005

AbstractThe modulatory effects of exogenous applications of adenosine on luminous organs (photophores) of the fish Porichthys were studied. Pretreatment of photophores with adenosine (10−7 to 10−3 M) potentiated both phases of adrenaline induced luminescence. The first peak of light (Lmax1) showed a 3‐fold increase following 10−7 M adenosine treatment; a maximal increase of 12‐fold was observed with 10−3 M adenosine. The second peak of light (Lmax2) exhibited a similar dose‐response curve, but the maximal increase was attained with 10−4 M adenosine. The potentiating effect of 1 uM adenosine on light emission triggered by adrenaline increased for adrenaline concentrations ranging from 10−7 to 10−4 M for Lmax1, but it remained stable for Lmax2. All 4 P1‐purinergic agonists tested at the final concentration of 10−4 M induced a potentiation of adrenaline luminescence with the following rank of potency: L‐PIA > NECA > CADO ≥ CHA = ADO for Lmax1 and NECA > CADO > ADO > CHA > L‐PIA for Lmax2. The potentiating effect of adenosine was antagonized with the following rank of potency by the P‐1 purinergic antagonists: CPT > DPMX ≥ AMINO > THEO for Lmax1 and CPT > AMINO > THEO ≥ DPMX for Lmax2. According to the classification of purinergic receptors, our results suggest that P1‐purinergic receptors might be implicated in the adenosine potentiation of Porichthys adrenaline luminescence. Experiments also showed that nor‐adrenaline luminescence is inhibited by 1 uM adenosine pretreatment. Further work will be necessary to elucidate the mechanism involved in the modulatory roles played by the purinergic receptors on adrenaline and noradrenaline luminescence in Porichthys photophores. © 1993 Wiley‐Liss, Inc.
Extent of mosaicism in experimentally produced diploid/triploid chimeric trout
Authors: Nilsson Eric E. , Cloud J. G. 
Published: June 2005

AbstractChimeric rainbow trout embryos have been produced by injecting isolated blastomeres into intact recipient blastulae. In order for chimeric fish to be useful in studies of development, it is necessary to determine whether the various organs or tissues of the resultant chimera have an equal probability of arising from the injected cells derived from donor embryos. The objective of this investigation is to determine the proportion of cells in the blood, liver, and brain tissues of rainbow trout chimeras that are derived from the injected cells. Blastomeres isolated from normal diploid blastulae were microinjected into age‐matched triploid recipient embryos, and the treated embryos grown until 4 weeks post hatch. Samples of blood, liver, and brain tissues were dispersed; the cell nuclei were labeled with propidium iodide, and the samples subjected to flow cytometric analysis to determine the proportions of diploid and triploid nuclei. The proportion of cells that were diploid varied among the resultant chimeric trout. Analysis of variance on the proportion of diploid cells in each sample indicated that there was no significant effect of tissue type. These results support the hypothesis that the isolated cells of the donor embryo are no more likely to colonize one tissue or organ type of a chimera than another. © 1993 Wiley‐Liss, Inc.
Role of prolactin and the gonads in seasonal physiological changes in the collared lemming (Dicrostonyx groenlandicus)
Authors: Gower Barbara A. , Nagy Tim R. , Stetson Milton H. 
Published: June 2005

AbstractOn a seasonal basis, collared lemmings undergo a number of physiological and morphological changes. Short photoperiod exposure results in a molt to a white pelage, an increase in body weight, a reduction in relative body fat content, an increase in relative water content, and the development of a bifid claw. Treatment with the dopamine agonist, CB‐154, resulted in a reduction in serum prolactin and the development of the white pelage in lemmings housed under 16L:8D, while treatment with the dopamine antagonist, sulpiride, prevented the winter molt in animals transferred to 8L:16D. Castration under 16L:8D resulted in an increase in body weight and an enlargement of the bifid claw. Castrated animals also molted more readily when treated with CB‐154 and developed a relatively greater carcass water content. Treatment with CB‐154 increased relative carcass fat content. These findings suggest that, in the collared lemming, seasonal changes in pelage parameters are regulated by prolactin, with gonadal hormones playing a modulating role. Body weight, water content, and bifid claw size appear to be influenced by gonadal hormones. © 1993 Wiley‐Liss, Inc.
Characterization of phosphotyrosyl protein phosphatase from the hepatopancreas of the shrimp Penaeus japonicus (Crustacea: Decapoda)
Authors: Chuang Nin‐Nin , Wang Pei‐Cheng 
Published: June 2005

AbstractPhosphotyrosyl protein phosphatase, purified from the hepatopancreas of Panaeus japonicus, is a monomeric enzyme with a relative mass (Mr) of 28,000, as estimated by size‐exclusion FPLC on a SuperoseTM 12. It has a hydrophobic domain and can be extracted with the detergent CHAPS. The specific activity of the purified enzyme was 9,800 units/mg of protein. The purified enzyme had an isoelectric point less than 4.6, and an optimal pH of 6.5 with either a synthetic peptide or autophosphorylated receptors for insulin as the substrate. The purified phosphotyrosyl protein phosphatase from shrimp hepatopancreas dephosphorylated human and shrimp receptors for insulin and was inactivated by ZnCl2, LiCl, MgCl2, and NaF. © 1993 Wiley‐Liss, Inc.
Development of the ectopically transplanted primordium of epithelial hypophysis (anterior neural ridge) in Bufo japonicus embryos
Authors: Kikuyama Sakae , Inaco Hiroo , Jenks Bruce G. , Kawamura Kosuke 
Published: June 2005

AbstractIt has recently been demonstrated that the epithelial pituitary of the toad is not stomodeal, but placodal, in origin. The placodal cells in the anterior part of the neural ridge (ANR) of the open neurulae are the exclusive source of the epithelial pituitary gland. The present study was undertaken to see the self‐differentiating ability of these cells in an ectopic environment. Bufo japonicus embryos at the tailbud stage received implants of either the ANR from open‐neurula‐stage embryos, or the pituitary primordium from tailbud‐stage embryos (the ANR derivative beneath the forebrain floor) into the tail. Development of the pars intermedia and the pars distalis was monitored immunohistochemically using antisera against both synthetic α melanophore‐stimulating hormone (αMSH) and bullfrog prolactin (PRL). Neither the immunoreactive αMSH cells nor the immunoreactive PRL cells differentiated from the neural ridge when it was dislocated from the original site at the open neurula stage. On the other hand, in grafts of the pituitary primordium transplanted from the tailbud‐stage embryos, immunoreactive PRL cells developed invariably and immunoreactive αMSH cells were detected at an incidence of 72%. The significance of the role of brain tissue surrounding the pituitary anlage in differentiation of the pars intermedia and pars distalis is discussed. © 1993 Wiley‐Liss, Inc.
Circadian timing of a daily rhythm of hemolymph insulin‐like peptide titers inHelisoma(Mollusca)
Authors: Sevala V. M. , Sevala V. L. , Kunigelis S. C. , Saleuddin A. S. M. 
Published: June 2005

AbstractThe hemolymph titers of insulin‐like peptide inHelisoma duryihave been determined using a radioimmunoassay. When animals were raised in a mixed photoperiod (12L:12D), the titer displayed two significant peaks of immunoreactivity during photophase, one after “lights on” (08:00 h) and the other before “lights off” (18:00 h). During the entire scotophase the titer remained low. This daily rhythm is maintained in continuous darkness and differing temperature regimes with a period of approximately 24 h. The free running period of the rhythm is temperature compensated. Therefore the hemolymph insulin‐like peptide titer is controlled by a circadian timing system. In older non‐growing snails, the titer was high without significant oscillations. Since the insulin‐like peptide is involved in shell growth and/or shell regeneration inHelisoma, circadian modulation can provide a precise control of shell growth and/or shell regeneration in this species. © 1993 Wiley‐Liss, Inc.
Probing the functions of endogenous lectins: Effects of a monoclonal antibody against the neural crest‐stage lectin of Xenopus laevis on trunk development
Authors: Milos Nadine C. , Frunchak Yvette N. , Mohamed Zarina 
Published: June 2005

AbstractTrunk neural crest of Xenopus laevis has been confronted prior to migration with whole or fragments of a monoclonal antibody raised against the carbohydrate‐binding site of the endogenous neural crest‐stage galactoside binding lectin (Milos et al.: Anat. Embryol., 182:319–327 '90). External fin formation was inhibited in confronted regions but extensive internal matrix develops suggesting interiorization of fin tissue. In the regions of missing fin, the myotomes overgrew the neural tube and dorsal root ganglion neuronal numbers became more variable. Melanophore numbers in regions of missing fin did not change but a significantly greater proportion of the pigment cells localized on the muscle surface that had overgrown the neural tube suggesting that the pigment cell population redistributed itself to occupy a greater myotomal area. © 1993 Wiley‐Liss, Inc.