Genetic characterization of cytological region 77A-D harboring the presenilin gene of Drosophila melanogaster.

We performed a systematic lethal mutagenesis of the genomic region uncovered by Df(3L)rdgC-co2 (cytological interval 77A-D) to isolate mutations in the single known Presenilin (Psn) gene of Drosophila melanogaster. Because this segment of chromosome III has not been systematically characterized before, inter se complementation testing of newly recovered mutants was carried out. A total of 79 lethal mutations were isolated, representing at least 17 lethal complementation groups, including one corresponding to the Psn gene. Fine structure mapping of the genomic region surrounding the Psn transcription unit by transgenic rescue experiments allowed us to localize two of the essential loci together with Psn within an approximately 12-kb genomic DNA region. One of these loci, located 3' to Psn, encodes a Drosophila protein related to the yeast 60S ribosomal protein L10 precursor. We also determined which of the newly recovered lethal mutant groups correspond to previously isolated lethal P-element insertions, lethal inversion breakpoints, and lethal polo gene mutants. Point mutations were identified in all five recovered Psn alleles, one of which results in a single amino acid substitution G-E at a conserved residue in the C-terminal cytoplasmic tail of the protein, suggesting an important functional role for this C-terminal domain of Presenilin. In addition, some viable mutations were recovered in the screen, including new alleles of the clipped and inturned loci.

The cleavage of beta-chain in bovine fibrinogen DH fragment (95 kDa) leads to a significant increase in its anticlotting activity.

It is shown that in the presence of Ca2+ plasmin converts bovine fibrinogen fragment DH (95 kDa) into DLA fragment by the cleavage of its beta-chain Arg372-Thr373 bond. DLA fragment consists of two components (82 and 12 kDa) held together by non-covalent bonds and has 3.5-fold higher anticlotting activity than DH fragment. The DH to DLA fragment conversion leads to the destabilization of thermolabile domains of the latter without the loss of their compact structure. The results obtained show that the activation of DH fragment by the cleavage of its Arg372-Thr373 bond bears some resemblance to the general activation of proenzyme into enzyme.

Localization of a fibrin polymerization site complementary to Gly-His-Arg sequence.

Dansyl-labeled tetrapeptide Gly-His-Arg-Pro which mimics the central fibrin polymerization site was used to investigate its binding to a number of fibrinogen fragments containing different numbers of domains. The tetrapeptide was found to bind to fragments DH(95 kDa), DL(82 kDa) and DY(63 kDa) but not to the TSD(28 kDa) fragment. The DY fragment differs from the TSD by the presence of beta and beta C domains. Therefore these domains, which are formed by the C-terminal part of the beta chain, possess a polymerization site complementary to the Gly-His-Arg containing counterpart.

[Comprehensive laboratory diagnosis of intravascular blood coagulation syndrome in late gestosis]. / Kompleksnaia laboratornaia diagnostika sindroma vnutrisosudistogo svertyvaniia krovi pri pozdnykh gestozakh.

A chronic form of intravascular blood coagulation (the DIC syndrome) is an obligatory pathogenetic mechanism in the organism of pregnant women with late gestoses. In order to find the DIC-syndrome and to provide urgent protective measures comprehensive laboratory diagnostics of the hemostatic pathologies is necessary. Analysis of clinician data has shown an optimal quantity and sequence of tests, among which some are traditional and several have been worked out by the authors. This approach can be recommended for corresponding medical institutions as such that provides obtaining exact and informative data about the state of blood coagulation with minimal amounts of human plasma.

[An analysis of a disorder in the fibrin-forming phase in virtually healthy middle-aged and elderly subjects by using the ancistron test]. / Analiz porushennia fazy fibrynoutvorennia u praktychno zdorovykh osib pokhyloho ta starechoho viku za dopomohoiu antsytronovoho testu.

Damages in the fibrin-formation phase initiated by activation of the blood coagulation system and fibrinolysis and promoted by interaction between fibrinogen and its derivatives (dissolved fibrinogen, products of fibrin and fibrinogen lysis) and by the presence of various blood coagulation inhibitors were found in 34% of practically sound old people and in 47% of people of senile age. It is shown very significant to apply the "ancistrone time" test developed on the basis of enzyme ancistrone-H isolated from the venom of snake Agkistrodon halys halys for estimating the fibrin-formation phase both on the model system and in practically sound people of old and senile age. The ancistrone test permits rapidly (for 30-60s) obtaining qualitative and quantitative characteristic of the fibrinogen level in the blood plasma, of the products of fibrin and fibrinogen lysis, of the blood coagulation inhibitors.