Integrins: regulators of embryogenesis.

Integrins are heterodimeric transmembrane glycoproteins involved in cell-cell and cell-extracellular matrix adhesion. They also participate in cytoskeletal rearrangements, co-regulation of growth factor activities and activation of signal transductions. This review describes experimental approaches that have given new insights into the integrin functions during embryogenesis.

Polar organization of gamma-tubulin in acentriolar mitotic spindles of Drosophila melanogaster cells.

The spindle pole localization of gamma-tubulin was compared in wild type and acentriolar cultured Drosophila cells using polyclonal antibodies specifically raised against the carboxy terminal amino acid sequence of Drosophila gamma-tubulin-1 (-KSEDSRSVTSAGS). During interphase, gamma-tubulin was present in the centrosome of wild type cells and accumulated around this organelle in a cell cycle dependent manner. In contrast, no such structure was observed in acentriolar cells.

Effect of hydrogen peroxide on cytoskeletal proteins of Drosophila cells: comparison with heat shock and other stresses.

Hydrogen peroxide, which was shown to trigger the heat-shock response by activating the immediate binding of the heat-shock factor to DNA heat shock regulatory elements in the promoter of heat-shock genes of Drosophila cells, has also been reported to enhance the synthesis of actin. We show here that very short and transient H2O2 treatments, from 1 s to 2 min, are sufficient to induce an increase of actin synthesis. This increase becomes apparent 2 to 3 h after the short H2O2 treatment.

Cyclin B is associated with centrosomes in Drosophila mitotic cells.

We have studied by way of confocal laser scanning microscopy the subcellular localization of cyclin B in Drosophila-cultured cells and report here evidence that a part of the cyclin B cell pool is closely associated with the centrosome. This cyclin B centrosomal signal is strong in prophase and metaphase but disappears during anaphase. Moreover, the signal is absent in the acentriolar Drosophila cell line 1182-4.

Overall study of the in vitro plasma clotting system in an invertebrate, Liocarcinus puber (Crustacea Decapoda): considerations on the structure of the Crustacea plasma fibrinogen in relation to evolution.

An overall study of the in vitro plasma coagulation system in the crab Liocarcinus puber has been carried out using various analytical methods, namely thromboelastography, spectrophotometrical examination, and a new one based on changes of the mechanical impedance of the developing clot. From the results reported here the clotting pattern in this species appears surprisingly complex for an invertebrate and unexpectedly closer to that of the vertebrates. Indirect evidences suggest that the fibrinogen polypeptide chains in this species and very likely in the other crustacean, are very different from those of the vertebrates.

Cross induced coagulations between human and crustacean clotting factors. Considerations on the clotting processes.

1. Cross induced coagulations show that human factor XIII and crustacean coagulin are to some extent functionally equivalent and may be substituted for each other. 2.

[Coagulation of hemolymph in Crustacea. Electrophoretic demonstration of a plasmatic component in the course of hemostasis in a group A crustacean (Cancer pagurus)].

Coagulation assays in vitro of plasmatic extract from Cancer pagurus reveal the existence of a plasmatic coagulation in this species which was considered as yet as lacking a such process. Electrophoretical analysis of this extract before and after coagulation shows the presence of a plasmatic component probably involved in the formation of the clot.

[Coagulation of the hemolymph in Macropipus puber (L)., Crustacea, Decapoda. Electrophoretic demonstration of a plasma component intervening in hemostasis].

Electrophoretical and immuno-electrophoretical analysis of plasma, serum and some plasmatic extracts of Macropipus puber (L). have evidenced the presence in the plasma of a component absent in the serum. This component which disappears from the plasmatic extracts after their coagulation must therefore plays a role in the clotting processes.

[Hemolymph coagulation in Macropipus puber (L.) Crustacea Decapoda. Respective roles of hemolymph and plasma].

The process of coagulation of the hemolymph in Macropipus puber (L.) Crustacea Decapod depends on one or several plasmatic factors and on a thermo-labile cellular factor which does not seem to be specific. The existence of these factors has been demonstrated.