RESUMO
The paper is devoted to a reaction-diffusion system of equations describing phytoplankton and zooplankton distributions. Linear stability analysis of the model is carried out. Turing and Hopf stability boundaries are found. Emergence of two-dimensional spatial structures is illustrated by numerical simulations. Travelling waves between various stationary solutions are investigated. Transitions between homogeneous in space stationary solutions and Turing structures are studied.
Assuntos
Modelos Biológicos , Fitoplâncton/fisiologia , Zooplâncton/fisiologia , Animais , Simulação por Computador , Comportamento Predatório/fisiologia , Fatores de Tempo , Movimentos da ÁguaRESUMO
A new isoflavone glycoside, echinoside (7), together with 7-hydroxyisoflavone, kaempferol-4'-methylether, kaempferol-7-methylether, myrecetin-3-O-alpha-L-rhamnoside, kaempferol and kaempferol-3-O-alpha-L-rhamnoside, has been isolated from the whole plant of Echinops echinatus. The structure of echinoside has been established by chemical and spectral data. This is the first report of the occurrence of these flavonoids in E. echinatus.
Assuntos
Echinops (Planta)/química , Flavonoides/química , Flavonoides/isolamento & purificação , Estrutura MolecularRESUMO
Conserved and consensus sequences of several members of scorpion toxin families have been analyzed. Multiple sequence alignment define the highly conserved residues that play important structural role in formation of toxin subgroups. Scorpion toxins have characteristic feature in signature pattern {(GA)}- K-C {(LIVM)}-X (2)- K- C- C-X-C) }. where lysine and cysteine residues are well conserved in the polypeptide. The toxins show two major groups, one with conserved active region GKCMNKGKC and second with CTPK. There is variability in position of lysine and arginine in different toxins. Most of the scorpion toxins contain six conserved cysteines involved in disulphide bonds. From the evolutionary analysis it is concluded that Leiurus is a primitive ancestral species from which probably various toxins have evolved during the evolution.
Assuntos
Biologia Computacional , Evolução Molecular , Escorpiões , Toxinas Biológicas/metabolismo , Sequência de Aminoácidos , Animais , Domínio Catalítico , Sequência Consenso , Dados de Sequência Molecular , Filogenia , Alinhamento de Sequência , Canais de Sódio/metabolismo , Toxinas Biológicas/químicaRESUMO
A new triterpene glycoside, arjunetoside, together with oleanolic and arjunic acids has been isolated from the root bark of Terminalia arjuna. The structure of arjunetoside has been established as 3-O-beta-D-glucopyranosyl-2alpha,3beta, 19alpha-trihydroxyolean-12-en-28-oic acid, 28-O-beta-D-glucopyranoside by chemical and spectral data.
Assuntos
Glicosídeos/isolamento & purificação , Extratos Vegetais/isolamento & purificação , Terminalia/química , Triterpenos/isolamento & purificação , Cromatografia em Camada Fina , Glicosídeos/química , Índia , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Metilação , Estrutura Molecular , Ácido Oleanólico/química , Ácido Oleanólico/isolamento & purificação , Extratos Vegetais/química , Raízes de Plantas/química , Plantas Medicinais/química , Espectrofotometria Infravermelho , Triterpenos/químicaRESUMO
From the whole plant of Eclipta alba, a new triterpene saponin, named eclalbatin, together with alpha-amyrin, ursolic acid and oleanolic acid were isolated. The structure of eclalbatin has been established as 3-O-beta-D-glucopyranosyl-3-beta-hydroxy-olean-12-en-28-oic acid, 28-O-beta-D-arabinopyranoside (1) on the basis of chemical and spectral data.
