RESUMO
We investigated the genetic distances and taxonomic status among species of Helobdella, a genus of non-blood-feeding leeches, based on mitochondrial cytochrome c oxidase subunit I sequences. Sampling included 20 specimens representing nine nominal species collected in 11 states in Mexico as well as previously published sequences of different species of Helobdella from several places. A neighbor-joining tree, as well as identification of diagnostic nucleotides, was used to suggest the presence of seven species of Helobdella in Mexico including potentially two undescribed forms.
Assuntos
Código de Barras de DNA Taxonômico , Sanguessugas/classificação , Sanguessugas/genética , Animais , DNA Mitocondrial/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Evolução Molecular , Genes Mitocondriais , Variação Genética , Sanguessugas/enzimologia , México , Dados de Sequência Molecular , Filogenia , Especificidade da EspécieRESUMO
Hementerin (HT) is an 80 kDa fibrino(geno)lytic metalloprotease, purified from saliva of the leech Haementeria depressa. In the present report, the effect of HT on several functional parameters of human platelets was assessed. HT inhibited platelet aggregation and ATP release induced by different agonists such as ADP, adrenaline, collagen, thrombin, and arachidonic acid. HT did neither modify the expression of platelet glycoproteins (Ib, IIb-IIIa, Ia-IIa, IV) nor intraplatelet fibrinogen levels, whereas it markedly decreased CD62P and CD63 levels after the stimulation with thrombin. HT significantly increased thrombin-induced platelet Ca2+ intracellular levels, cGMP content and nitric oxide synthase (NOS) activity. The effect of HT on platelet aggregation was reversed by two NOS inhibitors, N(omega)-Nitro-L-arginine methyl ester and 2 N(G)-Nitro-L-arginine. In summary, these results indicate that HT is an effective inhibitor of human platelet aggregation, presumably through activation of the platelet's nitridergic pathway.
Assuntos
Sanguessugas/enzimologia , Óxido Nítrico/metabolismo , Ativação Plaquetária/efeitos dos fármacos , Extratos de Tecidos/farmacologia , Trifosfato de Adenosina/metabolismo , Animais , Cálcio/metabolismo , GMP Cíclico/metabolismo , Fibrinogênio/análise , Metaloproteases/farmacologia , Óxido Nítrico Sintase/metabolismo , Agregação Plaquetária/efeitos dos fármacos , Inibidores da Agregação Plaquetária/farmacologia , Glicoproteínas da Membrana de Plaquetas/efeitos dos fármacos , Trombina/farmacologiaRESUMO
The fibrino(geno)lytic protein designated hementerin contained in crude extracts of the salivary complex of Haementeria depressa leeches was purified to apparent homogeneity by gel filtration, ion exchange chromatography and preparative SDS-PAGE. It is a single-chain 80 kDa, PhMeSO2F-resistant, calcium-dependent, metalloproteinase, which specifically degrades fibrin(ogen) through a plasminogen-independent pathway. The amino terminal sequence of 8 residues shows 80% similarity with hementin, another fibrino(geno)lytic protein purified from Haementeria ghilianii leeches. However, their activities differ somewhat in terms of kinetics and with regard to the structure of the fibrin(ogen) fragments they may produce. Cleavage by hementerin of fibrinogen Aalpha, gamma and Bbeta chains, in that order, produces 270 kDa to 67 kDa fragments which differ from those produced by plasmin. Hementerin was also able to degrade cross-linked fibrin although at a lower rate as compared to fibrinogen. In conclusion, hementerin is a plasminogen-independent fibrino(geno)lytic metalloproteinase that degrades fibrinogen faster than fibrin, prevents blood coagulation and destroys fibrin clots in vitro.