Purification and partial characterization of peptidase-1, a sex-linked enzyme in Pleurodeles waltl (urodele amphibian).

Peptidase-1 is a sex-linked enzyme, which can be purified from the liver of the amphibian urodele Pleurodeles waltl. We estimated its apparent molecular mass as 170 kDa by gel filtration chromatography. The enzyme is composed of two subunits with apparent molecular masses of 90 and 99 kDa. It is strongly inhibited by ethylenediaminotetraacetic acid, ethylene glycol bis(beta-aminoethyl ether)-N,N-tetraacetic acid, and 1,10-phenanthroline, indicating that peptidase-1 is a metallopeptidase. Peptidase-1 has optimal activity at 55 degrees C and pH 8.5. This acidic enzyme displays two apparent isoelectric points, at 4.9 and 5.2, and is essentially located in the cytosolic subcellular fraction.

Ovarian development and correlated changes in hemolymphatic ecdysteroid levels in two spiders, Coelotes terrestris and Tegenaria domestica (Araneae, Agelenidae).

Oocyte development during the first vitellogenic cycle of Coelotes terrestris and Tegenaria domestica is described. Under the present conditions, this development took about 40 days during which the oocytes went through six stages of maturation. For the first time presence of ecdysteroids is reported in adult females of spiders. Hemolymphatic ecdysteroid peaks were observed in both species at the transition between previtellogenesis and vitellogenesis. 20-Hydroxyecdysone and ecdysone were present in slightly different ratios in C. terrestris as well as T. domestica. These data largely agree with current views of ovarian development in Arthropods.

The larval integument of Calliphora erythrocephala Meigen (Diptera : Calliphoridae) during metamorphosis. Changes in macromolecular content and in incorporation rate of labelled precursors.

The amount of proteins, RNA and DNA in the larval integument of Calliphora erythrocephala, decreased markedly when metamorphosis began. The total incorporation per epidermis of labelled precursors also decreased at this time, but far less in RNA than in DNA and proteins. Thus, incorporation, when expressed in terms of specific activity, decreased in proteins, remained stable in DNA and increased in RNA. The significance of these results is discussed.

[Regression of chick embryo tail gut. Stage of determination of cell degeneration and role of the associated mesenchyme]. / La régression de l'intestin caudal chez l'embryon de poulet. Stade de détermination des dégénérescences cellulaires et rôle du mésenchyme associé.

In chick embryo the complete degeneration of the tail gut is carried out between H and H stages 20 to 24 and cell alterations are noticeable from stage 19. This paper reports a study to ascertain whether degeneration of the tail gut cells is already determined. The tail guts of donor embryos were taken at stages 17 to 20 and implanted into the leg bud of 4 to 5-day host embryos. In another series, stage 19 tail guts were implanted with their associated mesenchyme. The fate of the implants was histologically studied in the hosts at different times during their subsequent development. The younger grafts formed tubular structures almost identical to the normal tail gut. Implanted stage 19 tail guts with practically no mesenchyme did not degenerate; they maintained their structure but did not differentiate further. The tail guts implanted with associated mesenchyme degenerated, and stage 20 tail guts also regressed. The death of the tail gut cells was not determined until the degeneration processes had actually begun, the fate of the tail gut cells depending on their environment.

[Morphogenesis of the imaginal abdominal epidermis in Calliphora erythrocephala (Insecta,Diptera)]. / Morphogenèse de l'épiderme imaginal de l'abdomen de Calliphora erythrocephala (Insecte, Diptère).

The morphogenesis of the abdominal epidermis in Calliphora erythrocephala begins by a cellular proliferation which proceeds slowly in larvae and rapidly in pupae. This allows histoblasts to glide and invade the whole abdominal surface. As soon as the new epidermal sheet has become continuous, differentiation begins. Generalized epidermal cells show an intense activity which leads to the deposition of imaginal cuticle from the 6th day after pupation onwards. After cuticle deposition they darken and become inactive although they remain alive, even after emergence. Trichogen and tormogen cells are even more active than generalized epidermal cells, especially the trichogen cell in which polyribosomes and microtubules are abundant. The former are possibly involved in microtubule synthesis. After cuticle deposition the trichogen and tormogen cells undergo degeneration. Their nuclei contract, rough endoplasmic reticulum breaks down and cytoplasm breaks up into fragments through infoldings which proliferate from the plasma membrane. Finally only generalized epidermal cells and sensory cells remain alive in the adult.

[Acid phosphatase activity in the hemolymph of the fly Calliphora erythrocephala during metamorphosis]. / Activité de la phosphatase acide dans l'hémolymphe de la mouche Calliphora erythrocephala au cours de la métamorphose

Acid phosphatase is present in the haemolymph of the fly Calliphora erythrocephala. The activity of this enzyme has been studied during development; it shows a marked increase during hours following pupation. This increase of activity may be related to the histolytic processes which are acting during metamorphosis.