摘要:

AbstractThe native 108,000 dalton Ca2+‐dependent proteinase (CDP) and its 115,000 dalton protein inhibitor (CDPI) were purified from bovine skeletal muscle using native polyacrylamide gel electrophoresis and were used to elicit antibody production in rabbits and BALB/c mice. Polyclonal antibodies were purified as IgG fractions by column chromatography; monoclonal antibodyies were produced by the hybridoma technique. Indirect immunofluorescence localizations of CDP and CDPI in tissues ofCrotalus atroxshow both proteins to be ubiquitous. Both occur in the cytoplasm and are absent from the cell membrane and the nucleus; CDPI is also present in the I‐band of skeletal mus

ISSN:0022-104X    

DOI:10.1002/jez.1402410302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractHepatocytes of the small skate(Raja erinacea)were isolated by collagenase perfusion and evaluated by a variety of functional and morphologic criteria. Cell yield was 1.45 × 108± 1.3 × 107cells per isolation, and as long as 8 h after isolation 98% of the hepatocytes excluded Trypan blue and no leakage of lactate dehydrogenase (LDH) or cell associated potassium could be detected. Oxygen consumption averaged 1.6 ± 0.5 nmol/min/mg cell protein, was not stimulated by 1 mM succinate, and also remained stable for up to 8 h following isolation. However, 2,4,‐dinitrophenol (5 × 10−5M) produced a 55% increase in oxygen utilization while ouabain, (1 mM) or sodium removal decreased oxygen consumption by 31 ± 6 and 33 ± 7%, respectively, indicating that a significant portion of the cells energy utilization is coupled to the activity of plasma membrane Na+, K+‐ATPase.Light microscopic studies showed that the individual hepatocytes had diameters of 28 ± 5 μm and contained large lipid droplets. Electron microscopy revealed groups of three to five cells with normal ultrastructure and tight junctions and desmosomes surrounding a single bile canaliculus.These studies indicate that skate hepatocytes can be isolated in high yield that retain their structural polarity in the form of clusters of cells formed around a single bile canaliculus. These hepatocytes remain morphologically intact and metabolically stable for a prolonged period of time. Isolated skate hepatocyte preparations should be a useful experimental model to study hepatic metabolism in marine species, not only because of their viability but also because they retain their apical and basolateral membrane polarity, a feature that is usually lost in other isolated hepatocyt

ISSN:0022-104X    

DOI:10.1002/jez.1402410303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractEnvironmental cues terminating embryonic diapause and a potential regulatory mechanism involving depressed pH were investigated in the encysted embroyos of the brine shrimp,Artemia. Two species,Artemia franciscanaandArtemia monica, were used for this comparative study. To determine if alteration of intracellular pH (pHi) can terminate diapause, the pHiof diapause cysts was manipulated by exposure to NH3and CO2. Alkalinization did not result in activation of cysts from either species but acidification activatedA. franciscanacysts.A. monicadid not respond to acidification. The pHiof aerobic diapausing embryos was determined using31P nuclear magnetic resonance spectroscopy. During diapause, embryos from both species had pHi's similar to those reported for activated (nondiapause) embryos, indicating that diapause is not imposed by depressed pHi, as is the case during suppression of metabolism under anaerobic conditions. Diapause embryos were exposed to varying conditions of temperature, salinity, and oxygen to determine what conditions are necessary to break diapause.A. franciscanacysts were activated by cold temperature or salinites above 2.0 M NaCl, whileA. monicacysts only responded to cold temperature. The availability of oxygen did not influence either population's ability to terminate diapause. The results are discussed with respect to each population's environment and potential mechanisms of diapause regulation.

ISSN:0022-104X    

DOI:10.1002/jez.1402410304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe genetics, gross morphology, histology, and experimental production of a phenocopy of a new mutant gene in the Mexican axolotl (Ambystoma mexicanum) are described. The mutant phenotype, termed pin‐head (pi), is characterized at the hatching stage by craniofacial abnormalities including reduced interocular distance (including cases of cyclopia). Rostral head structures such as the olfactory organs, eyes, forebrain, and oral cavity are primarily affected. More posterior structures beginning with the pharynx, otic vesicles, hindbrain, notochord, and gills appear normal. The mutant gene shows variable penetrance and appears to be a simple recessive with increased penetrance when fertile eggs are reared to the hatching state at 10°C (cold sensitivity). Evidence that this gene may affect prechordal mesoderm and plate development is presented. Phenocopies of thepimutant were produced by the surgical removal of the prechordal mesoderm and plate from neural plate stage embry

ISSN:0022-104X    

DOI:10.1002/jez.1402410305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe specific binding of125I‐ovine prolactin (oPRL) to renal membrane preparations fromPseudemys scripta elegans, Ambystoma tigrinum, andRana catesbeianawas characterized. All three membranes showed specific oPRL binding that was dependent upon time, temperature, pH, and membrane concentration. Scatchard analysis of the binding of125I‐oPRL revealed high‐affinity sites with KAvalues of 2.1 × 1010, 3.6 × 1010, and 1.25 × 1010M−1for kidney membranes ofPseudemys, Ambystoma, andRana, respectively. In addition, there was a low‐affinity site on theAmbystomamembranes. The binding capacities ranged from 31 to 70 fmol/mg of membrane protein. The hormonal specificity of these membranes was studied by competing increasing amounts of oPRL, human growth hormone (hGH) derived from recombinant DNA techniques, bovine (b) GH, and human placental lactogen (hPL) with125I‐oPRL. The oPRL standard and hGH were the most potent competitors in all three assays, although hGH was not as potent as the oPRL. Human PL was moderately active in the turtle kidney assay, weakly active in theAmbystomaradioreceptor assay, and inactive in the bullfrog assay. Bovine GH had low potency on the turtle membranes and was inactive in the amphibian assays. The results of these studies indicate that the characteristics of renal PRL receptors ofPseudemys, Ambystoma, andRanaare similar to those of lactogenic receptors throughout the vertebrates. In addition, these data provide evidence for the first time of renal PRL receptor

ISSN:0022-104X    

DOI:10.1002/jez.1402410306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractJuvenile coho salmon (Oncorhynchus kisutch) were acclimated to seawater beginning at one of two stages of development. The first group was seawater‐acclimated before the 1‐ to 2‐month period of elevated plasma thyroxine (T4) concentration associated with the parr to smolt transformation (smoltification). The second group was seawater‐acclimated midway through the period of elevated T4levels. Two measures of thyroid activity were used to compare seawater‐acclimated salmon with their controls remaining in fresh water. The baseline concentrations of thyroid hormones were assayed throughout a 9‐ or 10‐week period, and at the end of 9 or 10 weeks the responsiveness to a single injection of 0.2 IU bovine thyrotropin was measured. Transfer to seawater before the smoltification‐associated T4elevation prevented the rise in thyroid hormone concentrations and reduced the response to bovine thyrotropin. Transfer of salmon during the period of elevated T4levels did not change thyroid hormone concentrations; however, the response to thyrotropin was greater in seawater‐acclimated fish than in fish still in fresh water. We conclude that the longterm response of the thyroid to seawater acclimation is partly a function of the stage of development at the

ISSN:0022-104X    

DOI:10.1002/jez.1402410307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractIn normal conjugation ofParamecium bursaria, pairs always consist of cells of different mating types and no selfing pairs are induced with detached cilia from cells of a complementary mating type. This suggests that the initial ciliary agglutination (the mating reaction) is mating‐type specific but that the subsequent formation of conjugating pairs is not mating‐type specific as in the other species ofParamecium. The mechanism to exclude the formation of selfing pairs in normal conjugation is suggested to be the requirement of long‐lasting specific ciliary adhesion for the formation of firm

ISSN:0022-104X    

DOI:10.1002/jez.1402410308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThere is a uniform increase in nuclear and cell size of erythrocytes, leukocytes, brain cells, and retinal cells in triploid coho and Atlantic salmon. In spite of the potentially drastic effects of this on their physiology and behavior, triploid fish appear to function as successfully as normal fish under aquaculture conditions. Triploid fish are easily produced, reared, and identified and should make useful tools for basic and applied research.

ISSN:0022-104X    

DOI:10.1002/jez.1402410309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractDespite the high cost of lactation alone, concurrent preganncy and lactation (CPL) is widespread among rodents. Many species that exhibit CPL delay implantation of the litter in utero while nursing. The first purpose of this study was to describe the pattern of energy allocation during CPL in a species with a large degree of overlap between gestation and lactation. Resting metabolic rate, food consumption and mass changes of Norway rat dams and litters, digestive efficiency and urinary energy loss of dams, and pup tissue energy equivalents were determined for CPL dams and for dams that were only lactating (C). CPL dams had significantly higher metabolic rates than C dams. Food consumption, pup growth, tissue energy equivalents, and assimilation efficiency were similar for both groups. The energy equivalent of mass change was greater for C dams, which gained in maternal mass (lipid) during lactation, than for CPL dams, which only increased in mass because of the litter in utero. The second purpose of this study was to investigate the suggestion that delayed implantation during CPL evolved as a mechanism to lower peak energy demands during CPL. Concurrently pregnant and lactating dams were injected with estrone (ECPL dams) on days 3–16 of lactation to prevent them from delaying implantation. A group of dams that were only lactating also received estrone injections (EC dams). ECPL dams produced smaller offspring at weaning than EC dams. This effect was more pronounced for large‐littered dams. These results indicate that the increased metabolic cost of a concurrent pregnancy is met by diverting energy into production of pup tissue rather than maternal tissue and that delayed implantation likely evolved as a means to decrease the peak energy demands of

ISSN:0022-104X    

DOI:10.1002/jez.1402410310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractA description of some properties of the cortical granule products (CGP) is provided. After activation, cortical granules (CG) discharge their content to the perivitelline space where most of these products remain. Two types of CGP preparations were used: one obtained by activating oocytes deprived of their vitelline envelope (tCGP), and the other obtained by activating oocytes covered by the vitelline envelope (vCGP). Both types of CGP were similar as regarding their capacity to modify oocyte sensitivity to spermatolysin. CGP modify the vitelline envelope (VE) of unactivated dejellied oocytes, which becomes insensitive to spermatolysin. This activity depends on both CGP concentration in the incubation media and the length of the incubation period. Once the effect of CGP on the oocyte is established it can not be completely eliminated by extensive washings, suggesting a lectin‐type association with the componenets of the VE. Treatment of dejellied oocytes with CGP results in fertility loss. The biological activity of CGP is related to thermolabile and nondialyzable substances. Lytic activity of spermatolysin on isolated VE is inhibited by CGP at a concentration at which trypsin inhibitors from soybean, lima bean, and ovomucoid are ineffective. The electrophoretic pattern of CGP indicates that most of the proteins present in the vCGP are derived from the VE. Ultrastructural modifications are observed in dejellied deposed oocytes after incubation with CG

ISSN:0022-104X    

DOI:10.1002/jez.1402410311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY