摘要:

AbstractDevelopment ofArtemia salinaembryos in the presence of ethidium bromide, an inhibitor of mitochondrial transcription, results in a dose dependent increase in the specific activity of lactate dehydrogenase, and a concomitant decrease in the specific activity of a cyanide‐resistant superoxide dismutase. The inhibition of mitochondrial function by ethidium bromide appears to exert opposite effects on the nuclear cistrons encoding lactate dehydrogenase and superoxide dismutase, and suggests that a common mitochondrial signal may exert diametric effects on nuclear cistrons whose products are characteristic of alternate states of respiratio

ISSN:0022-104X    

DOI:10.1002/jez.1402340102

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe skeletal plates and teeth of the echinoidParacentrotus lividuscontain a heterogeneous assemblage of macromolecules that are not part of the connective tissue, but are presumably intimately associated with the mineral phase. Upon dissolution of the Mg‐calcite mineral phase, some of these molecules are insoluble. The insoluble fractions of the teeth and skeletal plates are quite different, the former being predominantly protein and the latter, primarily some unknown nonproteinaceous material. The soluble constituents are similar in both tissues. These hydrophilic macromolecules have been partially separated and characterized. In both hard parts, two distinct classes of macromolecules are present, as indicated by the amino acid compositions of their protein constituents. These two classes of macromolecules are also present in the shells of a foraminifer and in various mollusks, both of which are formed by the “organic matrix‐mediated” biomineralization process. The locations of these macromolecules in the teeth and skeletal plates are not known, nor whether they form coherent structures. It is therefore premature to conclude that these macromolecules do function as an organic matrix, although the results presented are in agreement with such an interpr

ISSN:0022-104X    

DOI:10.1002/jez.1402340103

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

年代:1985

数据来源: WILEY

摘要:

AbstractAngiotensin II was infused intravenously in spiny dogfish sharks (Squalus acanthias). There were no significant effects on arterial blood pressure, glomerular filtration rate, urine flow, or Na excretion either in comparison with pre‐ and postinfusion values or in comparison with values measured in a control group of fish given elasmobranch saline intravenously. In other dogfish, glomerular filtration rate, urine flow, and Na and K excretory rates were measured for 3 days following implantation of desoxycorticosterone (DOCA), adrenocorticotropin (ACTH), or spironolactone; a control group was given no drug. There were no significant differences between these four groups of fish with respect to any of the measured parameters. These results suggest that the dogfish kidney is not a target organ for several substances known to affect renal function, either directly or indirectly, in other animal

ISSN:0022-104X    

DOI:10.1002/jez.1402340104

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

年代:1985

数据来源: WILEY

摘要:

AbstractFast and slow muscles from the claws and abdomen of the American lobsterHomarus americanuswere examined for adenosine triphosphatase (ATPase) activity and for differences in myofibrillar proteins. Both myosin and actomyosin ATPase were correlated with fiber composition and contractile speed. Four distinct patterns of myofibrillar proteins observed in sodium dodecyl sulfate‐polyacrylamide gels were distinguished by different assemblages of regulatory and contractile protein variants. A total of three species of troponin‐T, five species of troponin‐I, and three species of troponin‐C were observed. Lobster myosins contained two groups of light chains (LC), termed “alpha” and “beta.” There were three α‐LC variants and two β‐LC variants. There were no apparent differences in myosin heavy chain, actin, and tropomyosin. Only paramyosin showed a pattern completely consistent with muscle fiber type: slow fibers contained a species (105 kD) slightly smaller than the principle variant (110 kD) in fast fibers. It is proposed that the type of paramyosin present could provide a biochemical marker to identify the fiber composition of muscles that have not been fully characterized. The diversity of troponin and myosin LC variants suggests that subtle differences in physiological performance exist within the broader categories of fast‐

ISSN:0022-104X    

DOI:10.1002/jez.1402340105

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe variability of sperm histones in frogs has been studied by cytochemical and amino acid analyses. Cytochemically,Ranasperm proteins fall into Bloch's ('69, '76) type 4 somatic‐like histone category, whileXenopusandBufohave type 3 intermediate sperm histones. Extractability in 5% trichloroacetic acid (TCA) at different temperatures splits this type 3 category into two groups: type 3B intermediate sperm histones ofBufoare extractable at 85–90°C, whileXenopusintermediate type 3A sperm histones require temperatures of 95–100°C for extraction. Amino acid analysis confirms thatRanasperm histones are of the nucleosomal type, with a testis‐specific, very lysine‐rich H1 histone. The sperm protein inBufois richer in arginine than the proteins inXenopus. Both of these genera contain lysine and histidine as well as arginine in their sperm proteins. These results confirm earlier electrophetic data (Kasinsky et al., '78) and indicate that sperm histones in the order Anura can vary markedly between diffe

ISSN:0022-104X    

DOI:10.1002/jez.1402340106

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

年代:1985

数据来源: WILEY

摘要:

AbstractWe have examined, under a number of conditions, the aggregation behavior of Schneider Line 2 cells established originally from embryos ofDrosophila melanogaster. The work presented in this paper 1) further establishes appropriate conditions for the study of cellular adhesion inDrosophilacell lines; 2) shows that the adhesive capacity ofDrosophilacell line cells, under our experimental conditions, depends upon the presence of CA2+but not Mg2+; 3) shows thatDrosophilacell line cells will not aggregate in the cold; and 4) shows that trypsin treatment inhibits the aggregation of cell line cells, although high concentrations of calcium ions interfere with the action of trypsin.

ISSN:0022-104X    

DOI:10.1002/jez.1402340107

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

年代:1985

数据来源: WILEY

摘要:

AbstractIn studies of amphibian neurulation, the terms “neural ridge,” “neural fold,” and “neural crest” are sometimes used as synonyms. This has occasionally led to the misconception that grafting of the neural crest is equivalent to grafting of the neural fold. The neural fold, however, is composed of three parts: the neural crest, prospective neural tube tissue, and epidermis. In order to investigate how these neural fold components move during neurulation, time‐lapse photography, electron microscopy, and grafting were performed.Ambystoma mexicanumembryos were photographed during neurulation at regular intervals. The photographs were analyzed to find the position of those cells at beginning of neurulation that end up on the line of fusion as the neural folds close. Posteriorly, these cells are already on the emerging neural fold. In the anterior neural folds, however, these cells are located in the lateral epidermis. Electron microscopy of the neural folds confirms the presence of epidermis. To follow the movement of the cells differentiating into melanophores (neural crest), neural fold parts were grafted into albino hosts. The crest cells differentiating into melanophores following ectopic grafting are located in the flank of the neural fold that is in contact with the neural plate. In grafts from the outside (distal) flank, no melanophores developed. Semithin sections show that the third part of the neural fold consists of apically constricted cells known to differentiate into neural tissue. Because the neural folds consist of epidermis, neural tissue, and neural crest, neural fold and neural crest cannot be use

ISSN:0022-104X    

DOI:10.1002/jez.1402340108

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

年代:1985

数据来源: WILEY

摘要:

AbstractPrevious studies have shown that hamster sperm release a significant amount of hyaluronidase before and independently of the normal acrosome reaction. In this study, we have used improved methods for in vitro incubation to investigate the time course of the release of hyaluronidase and hexosaminidase from hamster sperm. When hamster sperm are incubated in medium which allows capacitation, 34 to 47% of the total mechanically extractable hyaluronidase and 34 to 51% of β‐N‐acetylhexosaminidase are released into solution prior to and independently of the normal acrosome reaction (ARx). An additional 40 to 50% of the hyaluronidase and 34 to 51% of the hexosaminidase are released at the time of the normal ARx. Control experiments indicate that the early release is not due to the presence of dead sperm in culture and that the normal ARx is required for the second release. Increasing amounts of TCA‐precipitated bovine serum albumin in the culture medium stimulated the early (1 hr) release of both enzymes. The data are consistent with the ideas that a significant amount of both enzymes is released from the sperm surface by 1 hr of incubation and that about the same amount of each enzyme is released during the normal ARx. Hyaluronidase and hexosaminidase release at the time of the acrosome reaction was measured for the first time using hamster sperm. The biphasic release of these enzymes may indicate that they have a dual function in fertilization and may help explain how sperm can penetrate the cumulus and corona radiata without undergoing an acrosome re

ISSN:0022-104X    

DOI:10.1002/jez.1402340109

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe acrosome reaction inAcipenser transmontanussperm can be induced by a 66,000 dalton glycoprotein that is present in Layer 3 (L3) of the egg envelope and in egg water only following exposure of the eggs to fresh water. When egg water is fractionated on Sepharose CL 6B, the 66,000 dalton glycoprotein‐containing fractions possessacrosome reactioninducing activity. Egg water may be species‐specific in its ability to elicit the acrosome reaction, as demonstrated by the fact that it has no effect on the sperm ofAcipenser fulvescens. Egg jelly possesses no acrosome reaction, inducing activity. The major carbohydrate‐containing component of the egg envelope is L3, a layer that contains galactose residues. L3 possesses a 70,000 dalton glycoprotein prior to freshwater exposure and lacks the 66,000 dalton component. If isolated from polyacrylamide gels, the 70,000 dalton glycoprotein elicits acrosome reactions in what appears to be a species specific manner. After freshwater exposure, L3 contains both the 70,000 dalton glycoprotein and the 66,000 dalton glycoprotein that is also present in egg water. The appearance of the 66,000 dalton inducer can be blocked by the incubation of eggs in fresh water containing inhibitors of trypsin activity. Thus, the soluble inducer in egg water may be proteolytically derived from a higher molecular weight complex in the egg env

ISSN:0022-104X    

DOI:10.1002/jez.1402340110

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

年代:1985

数据来源: WILEY

摘要:

AbstractForskolin, a reversible stimulator of the catalytic subunit of adenylate cyclase, has been used to determine: (1) whether an increase in hamster cumulus cell cyclic adenosine monophosphate (cAMP) results in an elevation of intraoocyte cAMP and an accompanying increase in the maintenance of meiotic arrest (%GV where GV is germinal vesicle) when heterologous coupling is maintained, (2) whether the hamster oolemma possesses the catalytic subunit of adenylate cyclase in an amount adequate to stimulate sufficient cAMP synthesis to maintain arrest, and 3) whether release from meiotic arrest is accompanied by a decrease in the content of intraoocyte cAMP. Intracellular cAMP was determined by RIA, functional metabolic coupling was assessed by determination of the fraction of radiolabeled uridine marker transferred from the cumulus mass to the oocyte, and meiotic stage was determined cytogenetically.While the %GV of both cumulus‐enclosed (intact) and cumulus‐free (denuded) oocytes was dose‐dependent upon forskolin, that of intact oocytes was much more sensitive to the drug (intact: ID503.4 μM; denuded: ID5065.0 μM, where ID50is the dose of forskolin that inhibits the maturation of 50% of cultured oocytes). Forskolin stimulated a significant, dose‐dependent increase in the amount of cAMP within the cumulus mass [(r) = 0.789, P<0.001)], the intact oocyte [(r) = 0.715, P<0.001], and the denuded oocyte [(r) = 0.673, P<0.01)]. The cAMP content of intact oocytes was significantly greater than that of denuded oocytes above 6.25 μM forskolin (25 μM forskolin: 9.28 ± 1.01 vs. 3.98 ± 0.15 fmol cAMP, intact and denuded oocytes, respectively; P<0.001, paired t test). A highly significant positive correlation was established between the amount of cAMP in groups of cumulus masses and that in the corresponding enclosed oocytes [(r) = 0.635, P<0.001]. The enhanced sensitivity of meiotic arrest in intact, as compared to denuded, oocytes was due to the presence of adherent cumulus cells but was not attributable to a significant increase in the cAMP content of intact oocytes (at 6.25 μM forskolin; %GV intact = 73.0 ± 10.7, denuded = 20.3 ± 7.4; fmol cAMP intact = 5.02 ± 1.50; denuded = 4.63 ± 0.81). The arresting action of forskolin on intact oocytes was transient and fully reversible, but release from arrest was not accompanied by a decrease in either intraoocyte cAMP or heterologous metabolic coupling. These data show that (1) the hamster oocyte can synthesize cAMP (2) when heterologous metabolic coupling is maintained cumulus cell cAMP may be transferred to the hamster oocyte, and (3) that release from forskolin‐maintained meiotic arrest is not correlated with a decline in intraoocyte cAMP or in heterologous coupling. The findings indicate that forskolin stimulates hamster cumulus cells to produce a “factor,” which may not be cAMP, to

ISSN:0022-104X    

DOI:10.1002/jez.1402340111

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

年代:1985

数据来源: WILEY