RESUMO
During fertilization in Chlamydomonas, flagellar adhesion between mt(+) and mt(-) gametes induces a cAMP-dependent signal transduction pathway that prepares the gametes for cell fusion and zygote formation. Previously, our laboratory identified a homeodomain protein (GSP1) whose expression was restricted to the cell bodies of mt(+) gametes and whose transcript level was up-regulated during flagellar adhesion. In this report, we describe a new form of GSP1 that appears early during gamete interactions. Immunoblot analysis showed that in addition to the 120-kDa form of GSP1 normally present in mt(+) gametes, a 122-kDa form was detected when the cells were mixed with mt(-) gametes. The more slowly migrating form of GSP1 was detectable within minutes after gametes were mixed together, and its appearance did not require new protein synthesis. Thus, the 122-kDa form represents a post-translational modification of the pre-existing 120-kDa form of GSP1. Moreover, conversion to the 122-kDa form did not require cell fusion. Although the 120-kDa form was expressed 10 h after vegetative cells were transferred to gametic induction medium, the 122-kDa form was detected only after mt(+) gametes were induced to undergo the sexual signaling that accompanies fertilization. Incubation of mt(+) gametes with dibutyryl cAMP led to the appearance of the 122-kDa form of GSP1, and the cyclic nucleotide-dependent protein kinase inhibitor H-8 inhibited the adhesion-induced conversion. Incubation of GSP1 immunoprecipitated from signaling mt(+) gametes with alkaline phosphatase showed that the conversion was due to phosphorylation. The results indicate that flagellar adhesion induces a rapid, cAMP-dependent phosphorylation of the homeodomain protein GSP1 early during fertilization in Chlamydomonas.
Assuntos
Chlamydomonas reinhardtii/metabolismo , Flagelos/fisiologia , Proteínas de Homeodomínio/metabolismo , Animais , Adesão Celular/genética , Adesão Celular/fisiologia , Chlamydomonas reinhardtii/genética , Chlamydomonas reinhardtii/crescimento & desenvolvimento , AMP Cíclico/fisiologia , Eletroforese em Gel de Poliacrilamida , Proteínas de Homeodomínio/química , Immunoblotting , Peso Molecular , Mutação , Fosforilação , Proteínas de Plantas , Reprodução/genética , Transdução de Sinais , Fatores de TempoAssuntos
Epifise Deslocada/terapia , Adolescente , Pinos Ortopédicos/efeitos adversos , Criança , Epifise Deslocada/diagnóstico por imagem , Feminino , Necrose da Cabeça do Fêmur/etiologia , Humanos , Complicações Intraoperatórias , Masculino , Manipulação Ortopédica/efeitos adversos , Complicações Pós-Operatórias , Radiografia , Estudos RetrospectivosRESUMO
The index of refraction and absorptive properties are estimated in nuclear matter consisting of protons and neutrons and in nuclear matter charge neutralized by electrons.
