RESUMO
Size-advantage and low-density models have been used to explain how mating systems favor hermaphroditism or gonochorism. However, these models do not indicate historical transitions in sexuality. Here, we investigate the evolution of bidirectional sex change and gonochorism by phylogenetic analysis using the mitochondrial gene of the gobiids Trimma (31 species), Priolepis (eight species), and Trimmatom (two species). Trimma and Priolepis formed a clade within the sister group Trimmatom. Gonadal histology and rearing experiments revealed that Trimma marinae, Trimma nasa, and Trimmatom spp. were gonochoric, whereas all other Trimma and Priolepis spp. were bidirectional sex changers or inferred ones. A maximum-likelihood reconstruction analysis demonstrated that the common ancestor of the three genera was gonochoristic. Bidirectional sex change probably evolved from gonochorism in a common ancestor of Trimma and Priolepis. As the gonads of bidirectional sex changers simultaneously contain mature ovarian and immature testicular components or vice versa, individuals are always potentially capable of functioning as females or males, respectively. Monogamy under low-density conditions may have been the ecological condition for the evolution of bidirectional sex change in a common ancestor. As T. marinae and T. nasa are a monophyletic group, gonochorism should have evolved from bidirectional sex change in a common ancestor.
Assuntos
Peixes/classificação , Peixes/fisiologia , Filogenia , Processos de Determinação Sexual/fisiologia , Animais , Feminino , Peixes/anatomia & histologia , Peixes/genética , Genes Mitocondriais/genética , Masculino , Reprodução/imunologia , Processos de Determinação Sexual/genética , Comportamento Sexual Animal/fisiologiaRESUMO
The milk protein, lactoferrin, is known to have antibacterial, antiviral, and antifungal activities. To explore the possibility of conferring disease resistance in plants by expressing this protein, the gene for the full-length human lactoferrin (HLF), as well as the N-lobe, the N-terminal half molecule (HLFN), was introduced into rice plants and expressed constitutively under the control of the cauliflower mosaic virus 35S promotor. Western blot analysis of leaves from HLF-transgenic rice plants showed an 80 kDa-band, which was about 1-2 kDa less than human milk lactoferrin. HLFN was expressed as a 45-kDa protein and retained its heparin-binding property. Deglycosylation experiments suggested that both proteins produced by the plants had plant-type oligosaccharide chains. The transgenic rice plants were assessed for resistance against disease-causing bacteria, virus, and fungi. Of the pathogens tested, significant resistance against Burkholderia (Pseudomonas) plantarii, the causative agent of bacterial seedling blight disease, was observed in the transgenic plants expressing HLF or HLFN.
Assuntos
Imunidade Inata/imunologia , Lactoferrina/genética , Oryza/genética , Doenças das Plantas , Plantas Geneticamente Modificadas/genética , Western Blotting , Burkholderia/efeitos dos fármacos , Burkholderia/crescimento & desenvolvimento , Caulimovirus/genética , Regulação da Expressão Gênica de Plantas , Glicosilação , Heparina/metabolismo , Humanos , Imunidade Inata/genética , Lactoferrina/metabolismo , Lactoferrina/farmacologia , Oligossacarídeos/metabolismo , Oryza/metabolismo , Oryza/microbiologia , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Folhas de Planta/genética , Folhas de Planta/metabolismo , Folhas de Planta/microbiologia , Plantas Geneticamente Modificadas/metabolismo , Plantas Geneticamente Modificadas/microbiologia , Regiões Promotoras Genéticas/genética , Engenharia de Proteínas , Estrutura Terciária de Proteína , Reoviridae/efeitos dos fármacos , Reoviridae/crescimento & desenvolvimento , Transfecção , Transformação Genética , Xanthomonas/efeitos dos fármacos , Xanthomonas/crescimento & desenvolvimentoRESUMO
Recent molecular biological studies have revealed that some photosymbiotic invertebrates dwelling in coral reefs host several genetically different dinoflagellates, Symbiodinium species, as symbionts. However, little is known about the difference in physiologic characteristics among these symbionts living in a single host, because some Symbiodinium strains are difficult to culture in vitro. To isolate some of these Symbiodinium strains, we have developed an agar culture medium plate containing antibiotics and a giant clam tissue homogenate. Using-this medium we isolated two new Symbiodinium strains from two molluscan hosts, Tridacna crocea and Pteraeolidia ianthina, each of which hosted two different Symbiodinium strains belonging to Symbiodinium C and D, respectively. The tissue homogenate was essential for the growth of Symbiodinium D. Although it was not essential for the growth of Symbiodinium C, it did stimulate the initial growth. For the isolation of some Symbiodinium strains, isolation medium containing host homogenate is effective.
