摘要:

AbstractThermal hysteresis proteins (THPs), which depress the freezing point of water by a non‐colligative process, are common in freeze‐avoiding polar marine fish and terrestrial arthropods where they function as antifreezes. However, some freeze‐tolerant arthropods and plants also produce THPs in winter, raising the question of whether these proteins are involved in the abilities of these organisms to survive the freezing of their extracellular fluids. The centipedeLithobius forficatusis one of these freeze‐tolerant, THP‐producing organisms.Cells isolated from the midgut of both winter‐ and summer‐collectedL. forficatuswere frozen at various temperatures, either with or without the addition of THPs purified from the beetleDendroides canadensis, and the survival of the cells was evaluated. The presence of THPs (0.02 mg/ml) in the bathing medium produced a statistically significant increase in cell survival, indicating a cryoprotective function for the THPs. The LT50(temperature of 50% survival) of cells for summer centipedes was shifted from −8.2°C to −15.0°C, and that of cells of winter centipedes was shifted from −12.1°C to −15.1°C by addition of THPs. Also, cells from summer‐collected centipedes which had been incubated in media containing THPs and then washed in buffer without THPs to remove the protein from the media prior to freezing demonstrated significantly increased survivorship after freezing (LT50= −14.5). Immunofluorescence studies of these cells indicated that the THPs were present in the cells and/or on the cell membrane. The presence of THPs in the medium also provided some protection to cells frozen under conditions designed to promote the potentially damaging process of recrystallization. (THPs are well known for their ability to inhibit recrystallization.) Therefore, THPs do appear to function as a component in the suite of adaptations which permit freeze tolerance inL. forfi

ISSN:0022-104X    

DOI:10.1002/jez.1402720402

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe δ isoenzyme of protein kinase C (PKC‐δ), purified from the plasma membrane of the hepatopancreas of the shrimpPenaeus monodonis specifically phosphorylated at tyrosine residues, as demonstrated by specific dephosphorylation by phosphotyrosyl protein phosphatase from the hepatopancreas of the shrimpPenaeus monodon. The specific activity of purified PKC‐δ was 200 units/mg of protein. The subunits of Mr 66,000, 62,000, and 58,000 of PKC‐δ were not autophosphorylated after the addition of phosphatidylserine and diolein. However, the purified PKC‐δ was active and catalyzed the phosphorylation of myelin basic protein. The kinase activity of the purified PKC‐δ could be decreased after treatment with phosphotyrosyl protein phosphatase. © 1995

ISSN:0022-104X    

DOI:10.1002/jez.1402720403

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

年代:1995

数据来源: WILEY

摘要:

AbstractParvalbumin from anaerobic white skeletal muscle of striped bass (Morone saxatilis) was characterized and the hypothesis tested that parvalbumin concentration varies with body size and thermal acclimation. Two parvalbumin isotypes (molecular weights 8.7 and 10.3 kDa, with pIs of 4.63 and 4.90, respectively) were identified from whole‐muscle extracts by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE), immunoblotting with a monoclonal antibody specific for parvalbumin, and two‐dimensional PAGE of heat‐treated supernatants. Total concentrations of parvalbumin were exceptionally high, ranging from 5.2 to 12.3 mg·g−1wet wt. or 0.55 to 1.29 millimoles per kg wet wt. of tissue. There was a significant inverse relationship between body size and total parvalbumin titer in white muscle (r = −0.89,P<.001), with small fish (2 kg). However, only concentration of the 8.7 kDa isotype varied between animals of different size. Given that parvalbumin can bind two calcium ions with high affinity, the higher titer of parvalbumin in muscles of small fish may be partially responsible for a higher tail‐beat frequency and faster rate of muscle relaxation than in larger animals. Lower titers of parvalbumin also may prolong the active state of muscle contraction in large striped bass and promote higher muscle force production than in small animals. In contrast to the effects of body size on parvalbumin content, thermal acclimation at cold termperature (5°C) for 8–10 weeks did not change the concentration of parvalbumin in white muscle. ©

ISSN:0022-104X    

DOI:10.1002/jez.1402720404

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe flagelliform or coronata glands of the orb‐web spider,Nephila clavipes, have been studied and compared to other silk‐producing glands from the organism. The glands, which produce silk for the double filament of the core thread in the sticky spiral, exhibit three distinct morphological areas: tail, sac, and duct. Electrophoretic separation of the solubilized contents of the glands yields an uppermost diffuse band of high molecular size, preceded by a stepladder of well‐defined peptides, which have been shown to be products of discontinuous translation in three other sets of glands. The luminal contents do not migrate as a discrete and well‐defined band as those of the other glands, but rather as a diffuse area, typical of glycosylated proteins. Fibroin synthesis is stimulated by the mechanical depletion of the organism's stored silks, as in otherNephilaglands, judged by the increased intensity of the bands and also by the structural alterations seen in cross sections of the glands' tails. © 1995 Wiley

ISSN:0022-104X    

DOI:10.1002/jez.1402720405

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe development and regeneration of the adrenal glands were examined by stereological and morphological methods in 20‐day‐old fetal, as well as 3‐day‐ and 14‐day‐old neonatal male rats born to dams treated with dexamethasone (Dx) on day 16 of gestation. In the fetuses and 3‐day‐old rats, zona fasciculata (ZF) and zona reticularis (ZR) were analyzed as one inner zone (IZ), while in 14‐day‐old animals they were analyzed separately. Single Dx treatment (1.5 mg/kg b.w.) of the dams led to atrophic changes in the adrenal cortex of the fetuses. These changes were visible to a certain degree up to the 14th neonatal day.Administration of Dx to pregnant rats induced a significant decrease of both adrenal weight and volume, as well as the volume of zona glomerulosa + capsule (ZG + C) and IZ, both in fetuses and 3‐day‐old rats. This was due to a decrease in the number but not the volume of cortical cells. Also, necrotic cortical cells, infiltrations and resorption zones accompanied by the presence of macrophages, giant cells and lymphocytes were observed. In 14‐day‐old animals, the degree of atrophic changes in the adrenal cortex was reduced. Changes were observed only in ZR which was decreased in volume resulting from both a significant decrease of the volume and number of cortical cells. Then number of macrophages was somewhat increased, while giant cells were not present. However, the total number of parenchyma cells in ZG was increased, pointing to the possibility of renewal of cortical cells within this zone.The results of the present study demonstrate that even a single Dx dose given to pregnant rat during the period critical for the development of the hypothalamo‐pituitary‐adrenal system in the fetuses leads to marked changes in the structure and function of the fetal adrenal glands which are partially maintained up to the 14th day of postnat

ISSN:0022-104X    

DOI:10.1002/jez.1402720406

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe characteristics of cytochrome P450c21 (21 hydroxylase; E.C. 1.14.99.10) were determined in interrenal tissue from blacktip shark (Carcharhinus limbatus). Consistent with other vertebrates, 21‐hydroxylase activity was enriched in the microsomal fraction of the interrenal and was dependent upon a source of reducing equivalents. The reduced form of nicotinamide adenine dinucleotide phosphate supported the highest level of activity. Specific activity increased with increasing temperature (Q10= 2.5) with a maximum at 35°C. At 30°C, maximal 21‐hydroxylase activity reached a plateau around pH 7.5. Elasmobranchs maintain high concentrations of intracellular nitrogenous compounds known to disturb protein function. While urea (400 mM) had no apparent effect upon 21‐hydroxylase activity, trimethylamine oxide (200 mM) inhibited conversion of progesterone to 11‐deoxycorticosterone by 23%. This inhibition was not reversed by urea. Potassium chloride (150 mM) inhibited 21‐hydroxylase activity by 33%. Kinetic parameters of shark 21‐hydroxylase were determined for [3H]progesterone (Km= 80 nM; Vmax= 2.94 nmol/min/mg protein) and [3H]17α‐hydroxyprogesterone (Km= 90 nM; Vmax= 0.89 nmol/min/mg protein). Substituted progestins were used to determine the steric specificity of this enzyme. Of thirteen steroid substrates studied, nine were metabolized, indicating a relatively broad specificity. The addition of trimethylamine oxide did not alter the substrate specificity. Although the blacktip shark homolog of cytochrome P450c21 is similar in some respects to other vertebrate forms, its temperature dependence, preferential use of progesterone and broad substrate specificity are unusual characteristics. © 199

ISSN:0022-104X    

DOI:10.1002/jez.1402720407

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

年代:1995

数据来源: WILEY

摘要:

AbstractHomeobox‐containing genes may play an important role in establishing embryonic patterns during development of vertebrates. Retinoic acid is able to induce expression of Hox genes in cells in culture and to alter expression patterns in the developing vertebrate embryos. Using wholemount in situ hybridization, we have examined and compared the expression patterns of a homeobox‐containing gene, Msx‐1, in early normal and vitamin A‐deficient quail embryos. At gastrulation stage, Msx‐1 is primarily expressed in the posterior half of both normal and vitamin A‐deficient embryos. However, the gene is expressed wider and stronger in the vitamin A‐deficient embryos. At neurulation stages, Msx‐1 is continuously expressed in the posterior region up to Hensen's node and in the edge of the neural fold in both normal and vitamin A‐deficient embryos. Notably, in the vitamin A‐deficient embryos, Msx‐1 is expressed more strongly and is also expressed ectopically in the anterior and precardiac regions. These results provide evidence that endogenous retinoids are involved in the normal expression of Msx‐1 in avian embryo and that the expression of Msx‐1 is downregulated by endogenous and physiological retinoids in vivo during early avian embryogenesi

ISSN:0022-104X    

DOI:10.1002/jez.1402720408

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe important roles played by glycoconjugates in the recognition of gametes and in fertilization are well documented. In the present study, the nature and distribution of carbohydrate residues of the plasma membrane of spermatozoa ofDrosophila melanogasterwere characterized by use of FITC‐conjugated lectins as probes. The plasma membrane bound agglutinins fromConcanavalia ensiformis(Con A) andPisum sativum(PSA), native and succinylated agglutinins from wheat germ (WGA and s‐WGA), the A4isoform of agglutinin‐I fromGriffonia simplicifolia(GSA‐I A4), and, to a lesser extent, the lectins fromDolichus biflorus(DBA),Lotus tetragonolobus(LTA), andGlycine maximus(SBA). Each lectin gave a specific pattern of binding. The extent of binding of Con A, WGA, s‐WGA, and GSA‐I A4over the acrosomal region was greater than over nonacrosomal regions, indicating the concentration of α‐mannose/α‐glucose, β‐N‐acetylglucosamine, and α‐N‐acetylgalactosamine residues in this area of the plasma membrane. The surface of the sperm failed to react with lectins fromRicinus communis(RCA‐I),Limulus polyphemus(LPA), andLimax flavus(LFA) and with the B4isoform of agglutinin‐I fromGriffonia simplicifolia‐I (GSA‐I B4). The plasma membrane over the nucleus did not react with any of the lectins tested.Quantitative analysis of binding of Con A, s‐WGA, and GSA‐I A4to spermatozoa showed that only Con A bound consistently to the sperm surface, showing high affinity for the acrosomal area of the plasma membrane. The other lectins tested bound only to limited and variably sized fractions of the total population of sperm. Therefore, only residues of α‐mannose/α‐glucose are a constitutive component of the plasma membrane, and they are characteristic of the acrosomal area. Con A can be used as a marker of the acrosome portion of sperm fromDrosophilafor visualization and assessment of acrosome status; labelling with FITC‐conjugated Con A provides a simple and reliable method for visualization of the acrosome ofDrosophilasperm that is otherwise detectable only by ultr

ISSN:0022-104X    

DOI:10.1002/jez.1402720409

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

年代:1995

数据来源: WILEY

摘要:

AbstractIn order to characterize the participation of growth factors in gonadal differentiation and development, we examined patterns of expression of the α subunit of inhibin, transforming growth factor‐β (TGF‐β), basic fibroblast growth factor (basic FGF) and insulin‐like growth factor‐II (IGF‐II) immunohistochemically in experimentally induced ovotestes. Ovotestes were derived from ovaries of fetal rats on gestational day (GD) 13 that had been co‐grafted with fetal testes (GD 17) beneath the kidney capsule of adult castrated males and examined on the 7th, 14th and 21st days after transplantation (TD). Reactivity with antibodies against the α subunit of inhibin and basic FGF was observed in the Sertoli cells in both ovotestes and testes on TD 14 and on TD7, 14 and 21, respectively. Expression of IGF‐II was also recognized in the Leydig/interstitial cells in both types of graft on TD 14 and 21. Therefore, the gonadal somatic cells in the testicular region of the ovotestes had immunohistochemical properties similar to those in the co‐grafted testes. However, the somatic cells in the ovarian region of the ovotestes had immunohistochemical profiles different from those in solitary grafted ovaries. The germ cells in the ovotestes showed some differences in patterns of expression when compared with those in co‐grafted testes and solitary grafted ovaries: expression of basic FGF was recognized in the germ cells in ovotestes on TD 21 but not in co‐grafted testes; expression of IGF‐II was recognized in the germ cells in ovotestes on TD 21 but not in solitary grafted ovaries. These results indicate that the immunohistochemical properties that reflect expression of growth factors in female gonadal somatic cells were changed to properties that resemble those of male gonads by the co‐grafted fetal tes

ISSN:0022-104X    

DOI:10.1002/jez.1402720410

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

年代:1995

数据来源: WILEY

ISSN:0022-104X    

DOI:10.1002/jez.1402720401

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

年代:1995

数据来源: WILEY