摘要:

AbstractZn2+‐dependent acidp‐nitrophenylphosphatase (Zn‐AcPase) from liver ofRana esculentawas 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

ISSN:0022-104X    

DOI:10.1002/jez.1402540202

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe effects of temperature on the apparent Michaelis‐Menten constant (Km) of pyruvate were determined for M4‐lactate dehydrogenases (LDHs) of 15 species of the teleost family Sciaenidae from habitats differing in average temperature and temperature range. The central question addressed was whether adaptive difference in the effect of temperature on an important kinetic parameter, Km, reflect selection based on the range of temperatures experienced by the species, the highest temperature encountered by the species, or both of these factors.For the M4‐LDHs of all 15 species, the Kmof pyruvate was conserved between 0.1 and 0.4 mM pyruvate over the species' physiological temperature range. However, large increases in Kmof pyruvate commonly were found at temperatures a few degrees C above the species' upper habitat temperature. Distinctions were found between the responses of the enzymes of eurythermal and stenothermal sciaenids. For the most eurythermal species, e.g.,Sciaenops ocellatus, Micropogonias undulatus, andRoncador stearnsii, Kmof pyruvate varied only about twofold between 10 and 30°C, the temperatures which encompass most of the habitat ranges of these species. For the most stenothermal species, e.g.,Cynoscion striatusandMicropogonias furnieri, with habitat temperature ranges of 14–18°C, sharp increases in Kmoccurred at temperatures above 20°C. We hypothesize that thermal stability of Kmvalues is more strongly selected by maximal habitat temperature than by the amount of variation in habitat temperature, and that adaptation to high temperatures may pre‐adapt enzymes for euryther

ISSN:0022-104X    

DOI:10.1002/jez.1402540203

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

年代:1990

数据来源: WILEY

摘要:

AbstractWe have previously extracted vanadobin, a substance binding vanadium ions in ascidian blood cells. The present study examined which of several types of blood cell contains this substance, using a combination of cell fractionation, chromatographies, and neutron activation analysis. The vanadium‐containing blood cell type, so‐called vanadocyte, is the signet ring cell inAscidia sydneiensis sameaas well asA. ahodori, and vanadobin was extracted from a homogenate of signet ring cells, but not from morula cells, although the latter have previously been considered to be the vanadocy

ISSN:0022-104X    

DOI:10.1002/jez.1402540204

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

年代:1990

数据来源: WILEY

摘要:

AbstractTwo different lectins (termed BnA‐I and BnA‐II) with distinct carbohydrate specificities were identified and subsequently isolated from the marine bryozoanBugula neritina. BnA‐I hemagglutinating activity was inhibited by N‐acetylated hexosamines, their polymers, and glycoproteins rich in these moieties. BnA‐II‐induced hemagglutination was not blocked by any simple sugars but could be inhibited by several complex glycoproteins (e.g., thyroglobulin and orosomucoid). Both lectins required the presence of Ca+ + for reactivity and were purified by affinity chromatographic procedures. Purified BnA‐I was determined to have a native molecular weight of 240 Kd and appeared to be a hexameric homopolymer while BnA‐II was shown to be a 65–70 Kd monomer. Both lectins showed seasonality in expression, BnA‐I appearing in animal extracts prepared in the spring and fall while BnA‐II was expressed only during

ISSN:0022-104X    

DOI:10.1002/jez.1402540205

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

年代:1990

数据来源: WILEY

摘要:

AbstractIn elasmobranchs, triglycerides are stored in the liver, which appears to be the primary site for lipolysis and oxidation of fatty acids, a major product being ketone bodies. The objective of this study was to obtain comparative information about properties of ketone body and phosphoenolpyruvate formation by liver ofSqualus acanthias(spiny dogfish, a representative elasmobranch) by using an isolated hepatic mitochondrial system we have previously described for studying respiration and glutamine‐dependent citrulline synthesis. Acetate and palmitoyl‐CoA are stoichiometrically converted to ketone bodies at a rapid rate. The capability of mitochondria to convert short‐chain fatty acids to ketone bodies indicates that the previously reported inability of dogfish mitochondria to utilize short‐chain fatty acids to support respiration is not due to absence of nucleoside monophosphate kinase activity. At least two acyl‐CoA synthetase activities are present in mitochondrial extracts, one specific for acetate and another with specificity for longer‐chain fatty acids. Utilization of palmitoyl‐CoA is carnitine‐dependent and is inhibited by low concentrations of malonyl‐CoA. Pyruvate and alanine are also rapidly metabolized to ketone bodies. Phosphoenolpyruvate is formed at a significant rate from a number of substrates, including in particular aspartate and malate in the presence of α‐ketoglutarate. The osmolytes urea and trimethylamine oxide activate and inhibit, respectively, phosphoenolpyruvate formation; in contrast, these osmolytes inhibit and activate, respectively, ketone body and citrulline formation by isolated mitochondria. The results are consistent with the reported unique functions of dogfish liver in lipid metabolism and indicate that the basic enzymatic processes at the level of mitochondria appear to be analogous to those present

ISSN:0022-104X    

DOI:10.1002/jez.1402540206

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe dynamics of the early patterning processes leading to the regeneration of a head in tissue excised from the body column ofHydra oligactiswere examined by using a monoclonal antibody, CP8. This antibody displays position‐specific binding, labeling the head ectodermal epithelial cells. During regeneration of a head, antibody labeling is present well before morphological signs of the head, at a time correlated with the determination of the tissue (Javois et al.,Dev. Biol.,117:607–618, '86). By quantifying antibody labeling during regeneration of three different pieces of tissue excised from the body column, it was found that the dynamics of the early patterning processes as visualized by CP8 labeling varied. The pattern of labeling observed as well as the spread of labeled tissue suggested that the amount and geometry of apical tissue in the regenerate played a critical role in the patterning processes. Contrary to the labeling pattern observed in heads which formed during bud development or which regenerated following decapitation (Javois et al., '86), not all the CP8+ tissue was confined to the head structures in these regenerates. Several alternative explanations for this surprising result are presented. The usefulness of these data in refining pattern formation models by more explicitly constraining their parameters is discus

ISSN:0022-104X    

DOI:10.1002/jez.1402540207

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

年代:1990

数据来源: WILEY

摘要:

AbstractImmunochemical studies demonstrate that the undecapeptide substance P (SP) may be detected by radioimmunoassay in newt limb regenerates and that SP is localized in the blastemal epidermis by immunofluorescence and peroxidase‐antiperoxidase staining. Immunoreactive SP is predominantly distributed at the periphery of epidermal cells, suggesting the presence of SP binding sites on the cell surface; the basal germinative layer of the epidermis and blastemal mesenchyme cells remain unreactive. The pattern of SP immunoreactivity in the blastema was compared with that of four other tachykinin‐family peptides (eledoisin, kassinin, substance K, and neuromedin K) and with three non‐tachykinin neural peptides (bombesin, neurotensin, and metenkephalin). With the exception of neurotensin, which showed weak staining in the basal layer but an absence in the peripheral layers of the epidermis, none of the peptides examined exhibited immunoreactivity in the blastema epidermis comparable to that

ISSN:0022-104X    

DOI:10.1002/jez.1402540208

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe progression of squamation and the formation of ctenii in developing juveniles of completely ambicolorate specimens of the Japanese flounder,Paralichthys olivaceus(Temmink et Schlegel), have been examined and compared with those of normally colored fish. The squamation developed with a similar pattern on both the ocular and blind sides of completely ambicolorate fish and of normal fish. In the normal fish, formation of ctenii occurred only on the ocular side and not on the blind side. In the completely ambicolorate fish, the formation of ctenii occurred on both the ocular and the blind side, but the formation of ctenii on the blind side differed from that on the ocular side in both normal and completely ambicolorate fish in terms of both mode and pattern. On the blind side of ambicolorate fish, the formation of ctenii progressed not from the lateral axis as is the case in the normal fish, but from the dorsal and ventral edges just after the formation of ctenii reached the edges on the ocular side, suggesting the diffusion of an unknown factor(s) through the dermal tissue.

ISSN:0022-104X    

DOI:10.1002/jez.1402540209

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

年代:1990

数据来源: WILEY

摘要:

AbstractAvoidance of fracture damage to the zona pellucida during freezing and thawing is essential for the successful freezing of rabbit embryos. The aim of this study was to examine the effects of encapsulation of rabbit embryos in calcium alginate gel, prior to freezing, on damage to the non‐cellular components (zona and mucin coat) caused by freezing and thawing, and on the survival of embryos after thawing in vivo as well as in vitro. Morulae immersed in 2% sodium alginate in Ringer solution were aspirated into a Pasteur pipette. The contents of the pipette were then ejected into a 110 mM solution of calcium chloride. After 30 min, 1‐ to 2‐mm long semi‐solid cylinders, each including one embryo, were cut off with a surgical blade. In the presence of 11% dimethyl sulfoxide, the encapsulated embryos were cooled by the standard method and stored in liquid nitrogen. After rapid thawing, the alginate gel was mechanically removed from around the embryos, and the embryos were morphologically evaluated and allocated to different groups for examination of their development in vitro or in vivo. The percentage of embryos with an intact zona was higher in the encapsulated group than in the non‐encapsulated group (95.3% vs. 76.5%,P<0.001). The encapsulation markedly reduced the occurrence of damage to the mucin coat (from 43.1% to 8.5%,P<0.001). The frozen and thawed embryos that were released from alginate gel developed normally in vitro (86.3%) and in vivo (54.2%). The results suggest that encapsulation of rabbit embryos in alginate gel prior to freezing improves the percentage of transferable embryos after thawing and increases the number of offspring that originate from frozen and thawe

ISSN:0022-104X    

DOI:10.1002/jez.1402540210

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

年代:1990

数据来源: WILEY

摘要:

AbstractIn order to determine if differentiatedXenopusretina is capable of undergoing regeneration and duplicative pattern formation, we devised a new surgical technique for removal of the temporal two‐thirds of the retina. In a series of progressively older larval eyes starting with late tailbud stage embryos (stage 38) and extending to limb‐bud stage tadpoles (stage 48), nasal onethird‐sized eye fragments successfully regenerated to form nearly normal sized eyes over 75% of the time. Histological preparations showed that early wound healing involved the formation of a neuroepithelium at the ventro‐temporal region of the fragment. The pigmented retinal epithelium and associated retinal tissue appeared to be involved in this process. Animals from each stage were reared through metamorphosis and electrophysiologic techniques were employed to determine visuo‐tectal projections. Seventy percent of stage 38 animals showed evidence of pattern‐duplicated projections. Ninety percent of their responding tectal points showed duplicate innervation from two retinal regions. Older animals (stages 44 to 48) showed less duplication. Only 52% of their responding tectal points duplicated (P<0.001). Thus, fully differentiatedXenopusretina can undergo regeneration and duplicative pattern formation similar to that shown by embryonic ret

ISSN:0022-104X    

DOI:10.1002/jez.1402540211

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

年代:1990

数据来源: WILEY