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Constant Association (constant + association)
Selected AbstractsDisease complex in coffee involving Meloidogyne arabicida and Fusarium oxysporumPLANT PATHOLOGY, Issue 3 2000B. Bertrand Coffee corky-root disease, also called corchosis, was first detected in 1974 in a small area of Costa Rica where the root-knot nematode Meloidogyne arabicida is the dominant species. An epidemiological study revealed a constant association between Meloidogyne spp. and Fusarium sp. in cases of corky root. No corky root appears to have been reported in association with Meloidogyne exigua, which is the prevalent root-knot nematode on coffee in Costa Rica. Fusarium spp. are often cited as components of disease complexes in association with nematodes. Combined inoculations using M. arabicida or M. exigua with Fusarium oxysporum under controlled conditions showed that only the combination with M. arabicida produced corky-root symptoms on Coffea arabica cvs Caturra or Catuai. Fusarium oxysporum alone was nonpathogenic. Meloidogyne exigua or M. arabicida alone caused galls and reduction in shoot height, but no corky-root symptoms. When cultivars susceptible and resistant to M. arabicida were studied under field conditions for 5 years, all the susceptible cultivars exhibited corky-root symptoms on 40,80% of their root systems. Cultivars that were resistant to M. arabicida but not to M. exigua showed no corky root. These observations lead to the conclusion that corky-root disease has a complex etiology, and emphasize the dominant role of M. arabicida as a predisposing agent to subsequent invasion by F. oxysporum. Consequently, genetic resistance to M. arabicida appears to provide an effective strategy against the disease. [source] Male and female range use in a group of white-bellied spider monkeys (Ateles belzebuth) in Yasuní National Park, EcuadorAMERICAN JOURNAL OF PRIMATOLOGY, Issue 2 2010Stephanie N. Spehar Abstract Spider monkeys (Ateles sp.) live in a flexible fission,fusion social system in which members of a social group are not in constant association, but instead form smaller subgroups of varying size and composition. Patterns of range use in spider monkeys have been described as sex-segregated, with males and females often ranging separately, females utilizing core areas that encompass only a fraction of the entire community range, and males using much larger portions of the community range that overlap considerably with the core areas of females and other males. Males are also reported to use the boundary areas of community home ranges more often than females. Spider monkeys thus seem to parallel the "male-bonded" patterns of ranging and association found among some groups of chimpanzees. Over several years of research on one group of spider monkeys (Ateles belzebuth) in Yasuní National Park, Ecuador, we characterized the ranging patterns of adult males and females and evaluated the extent to which they conform to previously reported patterns. In contrast to ranging patterns seen at several other spider monkey sites, the ranges of our study females overlapped considerably, with little evidence of exclusive use of particular areas by individual monkeys. Average male and female home range size was comparable, and males and females were similar in their use of boundary areas. These ranging patterns are similar to those of "bisexually bonded" groups of chimpanzees in West Africa. We suggest that the less sex-segregated ranging patterns seen in this particular group of spider monkeys may be owing to a history of human disturbance in the area and to lower genetic relatedness between males, highlighting the potential for flexibility some aspects of the spider monkeys' fission,fusion social system. Am. J. Primatol. 72:129,141, 2010. © 2009 Wiley-Liss, Inc. [source] Dynamic organization of COPII coat proteins at endoplasmic reticulum export sites in plant cellsTHE PLANT JOURNAL, Issue 6 2009Sally L. Hanton Summary Protein export from the endoplasmic reticulum (ER) is mediated by the accumulation of COPII proteins such as Sar1, Sec23/24 and Sec13/31 at specialized ER export sites (ERES). Although the distribution of COPII components in mammalian and yeast systems is established, a unified model of ERES dynamics has yet to be presented in plants. To investigate this, we have followed the dynamics of fluorescent fusions to inner and outer components of the coat, AtSec24 and AtSec13, in three different plant model systems: tobacco and Arabidopsis leaf epidermis, as well as tobacco BY-2 suspension cells. In leaves, AtSec24 accumulated at Golgi-associated ERES, whereas AtSec13 showed higher levels of cytosolic staining compared with AtSec24. However, in BY-2 cells, both AtSec13 and AtSec24 labelled Golgi-associated ERES, along with AtSec24. To correlate the distribution of the COPII coat with the dynamics of organelle movement, quantitative live-cell imaging analyses demonstrated that AtSec24 and AtSec13 maintained a constant association with Golgi-associated ERES, irrespective of their velocity. However, recruitment of AtSec24 and AtSec13 to ERES, as well as the number of ERES marked by these proteins, was influenced by export of membrane cargo proteins from the ER to the Golgi. Additionally, the increased availability of AtSec24 affected the distribution of AtSec13, inducing recruitment of this outer COPII coat component to ERES. These results provide a model that, in plants, protein export from the ER occurs via sequential recruitment of inner and outer COPII components to form transport intermediates at mobile, Golgi-associated ERES. [source] Effect of inhibitors of mitogen-activated protein kinase kinase on ,1B -adrenoceptor phosphorylationAUTONOMIC & AUTACOID PHARMACOLOGY, Issue 1-2 2009R. Alcántara-Hernández Summary 1,Mitogen-activated protein kinases mediate hormone/neurotransmitter action on proliferation and differentiation and participate in receptor regulation. The effect of inhibitors of mitogen-activated kinase kinase (MEK) on ,1B -adrenoceptor phosphorylation state and function was studied using different cell lines. It was observed that at nanomolar concentrations the MEK inhibitors, PD98059 (2,-amino-3,-methoxyflavone) and UO126 [1,4-(diamino-2,3-dicyano/1,4-bis-(2-aminophenylthio)-butadiene], increased ,1B -adrenoceptor phosphorylation and diminished the functional response of this receptor to noradrenaline. These agents did not alter the action of lysophosphatidic acid. 2,Staurosporine (IC50 , 0.8 nm) (a general protein kinase inhibitor) and bis-indolyl-maleimide I (IC50 , 200 nm) (a selective protein kinase C inhibitor) inhibited PD98059-induced ,1B -adrenoceptor phosphorylation. In contrast, neither wortmannin (phosphoinositide 3-kinase inhibitor) nor genistein (protein tyrosine kinase inhibitor) had any effect. The data suggest the possibility that MEK might exert control on the activity of the enzymes that regulate receptor phosphorylation, such as G-protein-coupled receptor kinases, protein kinase C or serine/threonine protein phosphatases. 3,Coimmunoprecipitation studies showed a constant association of total extracellular signal-regulated kinase 2 (ERK2) with ,1B -adrenoceptors. Association of phospho-ERK 1/2 to ,1B -adrenoceptors increased not only in response to agonist but also in response to agents that increase ,1B -adrenoceptor and ERK1/2 phosphorylation [such as endothelin-1, phorbol 12-myristate-13-acetate (PMA) and epidermal growth factor (EGF)]; not surprisingly, PD98059 decreased this effect. 4,Our data show that blockade of MEK activity results in increased ,1B -adrenoceptor phosphorylation, diminished adrenoceptor function and perturbation of receptor,ERK1/2 interaction. [source] | ||||||||||