摘要:

Two proteases, assayed with fluorogenic peptides and tentatively designated Rcand Kc, have been isolated from nuclei of rat testis cells by differential extraction with acetic acid, removal of some proteins at pH 4.5, and polyacrylamide gel electrophoresis followed by electroblotting onto nitrocellulose paper. Protease R hydrolyzes t‐Butyl‐oxycarbonyl‐Val‐Pro‐Arg‐7‐amino‐4‐methyl‐coumarin and other peptides in which arginine is joined to 7‐amino‐4‐methyl‐coumarin by amide linkage. Protease Kchas a preference for peptides terminating in lysine‐7‐amino‐4‐methylcoumarin amide. Neither of these proteases is active against Glu‐Phe‐7‐amino‐4‐methyl‐coumarin amide or Carbobenzoxy‐Arg‐7‐amino‐4‐methyl‐coumarin. Proteases Rcand Kcpartially hydrolyze [3H] methyl ‐labeled histones H3 + H4 to trichloroacetic acid ‐ soluble peptides. Activities similar to proteases Rcand Kcare also found in cytoplas‐mic fractions of testis homogenates.

ISSN:0373-4137    

DOI:10.1080/11250008709355566

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Proteases Rcand Kcof the nuclei of rat testis cells exhibit considerable differences in susceptibility to various protease inhibitors. Protease Rcis inhibited by D‐phenylalanyl‐L‐propyl‐L‐arginine chlormethylketone and p‐nitrophenyl‐p1‐guanidino ben‐zoate. Protease Kcis inhibited by Nα‐p‐tosyl‐L‐lysine chlormethylketone, N‐p‐tosyl‐phenylalanine chlormethylketone, N‐carbobenzoxy‐L‐phenylalanine chloromethylketone and p‐nitrophenyl‐p'‐guanidino‐benzoate. Neither protease is inhibited by 10 mM phenylmethanesulphonyl‐fluoride or p‐chloromercuri‐benzoate. p‐nitrophenyl‐p1‐guanidino‐benzoate is a substrate for protease Rcwith release of p‐nitrophenol, however the protease activity is not restored during a period of 8 hours after removal of excess p‐nitrophenyl‐p1‐guanidino‐benzoate. Both proteases can bind to immobilized soybean trypsin inhibitors.

ISSN:0373-4137    

DOI:10.1080/11250008709355567

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The anterior intestine of the gastropodAchatina fulicagenerated a small serosa‐negative potential which ranged from 1.0 to 7.5 mV when bathed in normal salinein vitro.The associated short‐circuit current averaged 75μA/cm2.The electrical potential does not depend on K+, Mg2+, Ca2+or Na+but requires Cl‐on the mucosal side. The electrical gradient is reduced by furosemide, cyanide, 2,4‐dinitrophenol and anoxia but not by ouabain. The transmural potential difference and short‐circuit current were predominantly dependent upon aerobic metabolism. However, a finite residual electrical component was dependent upon glycolytic energy. It is suggested that the role of active chloride transport across the intestinal epithelium may be to facilitate fluid absorption from the lumen into the haemolymph.

ISSN:0373-4137    

DOI:10.1080/11250008709355568

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A population ofEuplotescollected from the mouths of the Rhône was assigned to the morphospeciesE. charon.The 27 strains established in the laboratory were found capable of producing protective cysts in response to environmental salinities exceeding 502. and, with the exception of two, all of them formed mating pairs. Mating interactions appeared to be controlled by a system of multiple mating types, probably inherited via alleles condominant at the genetic locusmat.Cells in the G1cell‐cycle stage, which occupies 62% of the generation time, as well as cells in the S stage could mate. Mating was followed by an unusually long period of immaturity of 120–180 fissions. In the conjugants, the micronucleus performed four divisions, one preliminary and three pregamic; the macronucleus persisted unchanged. Cytological observations suggested that the two gamete nuclei derive from different products of the preliminary micronuclear mitosis. The synkaryon regularly performed three metagamic divisions and, in the exconjugants, the old macronucleus underwent complete resorption following an unusual phenomenon of positional inversion. The first metagamic division was determinative for the origin of the new macronucleus and micronucleus.

ISSN:0373-4137    

DOI:10.1080/11250008709355569

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The study of the gamete maturation and the seasonal reproductive cycle ofSolatopupahas been carried out by the histological analysis of both the ovotestes and the genital ducts of specimens which were periodically sampled from a natural, outcrossing population.S. similishas been demonstrated to be a true hermaphrodite, since both types of its gametes begin to differentiate together and probably undergo simultaneously the meiotic prophase; however, it could be considered functionally protandrous because male gametes come to maturity in spring and summer, while egg maturation and growth is delayed until the late winter. Mature sperms are stored throughout the year in a portion of the ovotestis duct (or first hermaphrodite duct) which functions as a seminal vesicle: thus, functional protandry is certainly not important as a self‐sterility mechanism. The behavioural and adaptive significance of this pattern of gametic maturation and auto‐sperm storage are also discussed.

ISSN:0373-4137    

DOI:10.1080/11250008709355570

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The shell‐boring gastropodOcinebrina edwardsisustains itself by preying on mussels. In the laboratory these drills, when presented with a choice between well fed and starved prey, were attracted to a statistically significant degree (P < 0.01) towards the well fed mussels. Chemical signals, i. e. attractant and/or repellent substances which were being continually emitted by the mussels, informed the predators from a distance as to the physiological condition of their prey. Results of any predation tests which fail to take this aspect into consideration may be biased and tests carried out on animals which have been kept for a long time in captivity are to be avoided.

ISSN:0373-4137    

DOI:10.1080/11250008709355571

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The production of free medusoids is considered to be a transition from the production of medusae to the abolition of this stage of the life cycle, within a generalized process of paedomorphosis occurring within hydromedusae, in which the hydroid stage is the larva and the medusa stage the adult. The discovery of a species of Haleciidae producing free medusoids allows the reconstruction of the phylogeny of this family according to the following sequence of genera:Campalecium(producing medusae);Hydrantbeaproducing free medusoids);Hydrodendron(with sporosacs and nematophores);Scoresbia(with sporosacs and nematothecae);Ophiodissa(with sporosacs and nematothecae, branched);Phylactotbeca(with sporosacs, differentiated nematothecae and hydrothecae, branched). The affinities of the medusa stages betweenCampaleciumandEucbeilotaindicate that the Haleciidae originated by the evolution of hydroids of the family Campanulinidae s.l. The Haleciidae evolved further, giving rise to the Plumulariidae. The phylogeny of the Haleciidae is compared with that of the Campanulariidae, in which the reduction of the motile sexual stages is probably followed by the formation of the peculiar medusa ofObelia, considered here as deriving from fixed gonophores. Probably different processes can occur in the evolution of hydromedusae, according to both the gradualistic and the punctuated equilibria hypotheses.

ISSN:0373-4137    

DOI:10.1080/11250008709355572

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Dugesia anceps(Kenk, 1930), formerlyPlanaria dubiaBorelli, 1895, is a poorly known species from southern South America (Paraguay and Argentina). In this paper an anatomical as well as histological description is made and the previous identifications by Böhmig (1902) and Hyman (1959) are discussed. It can be distinguished from the other Neotropical species by the following characters: the ventral testes; the anteriorly curved spermiducts, ending in two intrapenial sperm vesicles that run downwards and unite at the base of the penis papilla to form a narrow ejaculatory duct; the long penis which has an ample male atrium; a relatively small copulatory bursa and a short but well defined female atrium with infranucleate epithelium.Dugesia ancepsis the most abundant species of triclads in the mesosaprobe streams of southern Buenos Aires Province (Argentina).

ISSN:0373-4137    

DOI:10.1080/11250008709355573

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Aspidiophorus polystictos, a new marine species of Gastrotricha Chaetonotida is described and compared with the species of the groupA. marinus ‐ A. mediterraneus.This species is characterized by the subrectangular shape of the scales. The life cycle of individuals reared under laboratory conditions is described for the first time in marine Chaetonotida. A parthenogenetic phase precedes a hermaphroditic phase as in several freshwater Chaetonotidae.

ISSN:0373-4137    

DOI:10.1080/11250008709355574

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

In this paper a new species of the subfamily Exogoninae (Polychaeta, Syllidae) is described:Exogone cognettiin. sp., collected in the Bay of Calvi (Northern Corsica). The species is similar toE. microtentaculataWestheide (Galapagos Island) and toE. atlánticaPerkins (Florida), but clearly differs from them in the shape and disposition of the setae, in the shape of the anal cirri and in the dimensions of the proventriculus.

ISSN:0373-4137    

DOI:10.1080/11250008709355575

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor