), bem como a testemunha sem tratamento herbicida. A toxicidade dos tratamentos herbicidas foi avaliad a aos 7, 15 e 30 DAT (dias após tratamento). Os res ultados obtid os nos experimentos em condições de campo e em casa de vegetação, de forma geral, evidenciam que o biótipo sensível é controlado pelo glyphosate e pelos demais herbicidas avaliados. Demonstram ainda que o biótipo resistente apresenta-se, igualmente ao biótipo sensível, altamente suscetível aos herbicidas com mecanismo de ação distinto daquele do glyphosate. Entretanto, o biótipo resistente mostra baixa resposta ao herbicida glyphosate, mesmo se este for empregado em doses elevadas, evidenciando ter adquirido resistência a esse produto. (0,360, 720, 1,440, 2,880 and 5,760 g ha -1 ), and also the herbicides paraquat and 2,4-D as standards. The greenhouse experiments had increasing rates of glyphosate (0, 360, 720, 1,440, 2,880 and 5,760 Palavras-chave: resistência a herbicidas, inibidores da EPSPs. ABSTRACT -Glyphosate is a non-selective herbicide used for over 20 years to control weeds in Rio Grande do Sul. Horseweed (Conyza bonariensis) is a common weed in Rio Grande

The weight percentage and mean size of the 10±63 lm terrigenous silt fraction (termed`sortable silt') of ®ne-grained marine sediments have recently been argued to be proxies for near-bottom palaeocurrent intensity. This paper details the accuracy and precision of the Sedigraph 5100 and the Coulter Multisizer IIe in determining the weight percentage and mean size of the sortable silt at abundances characteristic of deep-ocean sediments. Three sortable silt standards and a ®ne silt/clay diluent were generated from natural deep-sea sediment of the Iceland Basin. These were used to produce silty clays with standard additions of sortable silt ranging from 1% to 20% of the total by weight. Accuracy was measured relative to the size of the pure spike measured by each instrument. At sortable silt abundance >5%, the Sedigraph and the Coulter Multisizer estimate both weight percentage and mean grain size precisely and accurately, while below 5%, instrumental noise degrades their performance. On the basis of the Sedigraph results, a series of percentage errors is de®ned, which may be applied to sortable silt mean size and weight percentage estimates used in palaeoceanographic near-bottom current reconstruction. It is suggested that, ideally, palaeocurrent reconstructions should be based on Sedigraph determinations of the 0±63 lm grain size distribution, yielding both mean and abundance, or on Coulter Multisizer determinations of the sortable silt grain size mean. The Coulter Multisizer may prove especially useful in regions of very depleted (<5%) sortable silt component.

Dermatitis herpetiformis (DH) is a chronic subepidermal blistering disease, in which a perivascular cellular infiltrate, composed mainly of CD4+ T lymphocytes together with a varying number of neutrophils and eosinophils, is thought to be important in the pathogenesis of blister formation. The aim of this study was to investigate the potential role of cytokines such as the interleukins IL-4 and IL-5 and to quantify the distribution of T cells as well as their state of activation using alkaline phosphatase-antialkaline phosphatase and reverse transcriptase-polymerase chain reaction (RT-PCR) procedures in seven patients with typical clinical and histological features of DH. A strong extracellular staining with anti-IL-4 monoclonal antibody was detected in the upper dermis with a prevalent perivascular pattern in perilesional areas, whereas in the dermal-epidermal separation sites there was an intense, scattered distribution. IL-5 was intensely expressed, mainly at the intracellular level, by eosinophils and lymphocytes. Concerning RT-PCR, five DH patients showed a strong positive signal for both IL-4 and IL-5 cytokines while two patients showed a faint signal for both IL-4 and IL-5; these last two cases were histologically poor in inflammatory cells. In view of these results, it can be hypothesized that the recruitment of eosinophils and neutrophils in DH may be induced not only by granulocyte macrophage colony-stimulating factor and IL-8 as previously demonstrated, but also by Th2 cytokines as well.

A caracterização da habilidade competitiva da soja, em função da resposta diferencial dos cultivares, pode fornecer subsídios valiosos tanto para o melhoramento genético como para o manejo de plantas daninhas. Várias características da cultura podem associar-se com a competitividade; contudo, em soja, poucos estudos foram realizados com a finalidade de identificá-las. Com os objetivos de avaliar a variabilidade existente em cultivares de soja quanto à competitividade com plantas concorrentes e identificar aqueles portadores de habilidade competitiva superior, foi conduzido experimento a campo, em Cruz Alta-RS, na safra 2000/01. Testaram-se duas condições de competição (ausência ou presença de nabo-forrageiro durante a fase de desenvolvimento vegetativo da soja), combinadas com 11 cultivares da cultura. A presença do nabo durante os primeiros 60 dias do ciclo da soja reduziu estatura de planta, área foliar, massa da parte aérea seca, emissão e crescimento de ramos. Os cultivares de soja responderam diferentemente à interferência do nabo, indicando existir variabilidade genética para competitividade, o que permite selecionar genótipos de soja portadores de habilidade competitiva superior. De outra parte, ocorreu maior supressão do crescimento de plantas de nabo em função da presença dos cultivares de soja 'CD 201' e 'Fepagro RS 10'.