Raças de Xanthomonas spp. associadas à mancha-bacteriana em tomate para processamento industrial no Brasil Races of Xanthomonas spp. associated to bacterial spot in processing tomatoes in Brazil

A grande diversidade genética dos agentes causadores da mancha-bacteriana dificulta sobremaneira o desenvolvimento de variedades de pimentão e tomate com resistência durável. Setenta e dois isolados de Xanthomonas spp. provenientes de campos comerciais de tomate para processamento industrial dos estados de Goiás, Minas Gerais, Pernambuco e Bahia foram classificados em raças com base nas reações de genótipos diferenciais de tomateiro (Walter, Hawaii 7998 e NIL 216) e de Capsicum (ECW [Early Calwonder], ECW-10R, ECW-20R, ECW-30R e PI235047). As plantas foram inoculadas no estádio de três a cinco folhas verdadeiras por infiltração de suspensão bacteriana (5 ´ 10(8) UFC/ml) na superfície abaxial da folha. Em seguida, foram mantidas em câmara de crescimento em fotoperíodo de 12 h/12 h (luz/escuro) a 28ºC. A reação de hipersensibilidade foi observada até 36 horas após a inoculação, dependendo do genótipo da hospedeira. Foram identificadas as raças T1P2, T1P8 e T3 em X. axonopodis pv. vesicatoria; a raça T2 em X. vesicatoria; e as raças T2P7 e T2P8 em X. gardneri. A presença dos genes avrRxv e avrXv3 nos isolados que causaram reação de hipersensibilidade em 'Hawaii 7998' (raça T1) e 'NIL 216' (raça T3), respectivamente, foi confirmada por reação em cadeia da polimerase (PCR) usando iniciadores específicos. Este é o primeiro relato da ocorrência no Brasil das raças T3, T1P8, T2P7 e T2P8.<br>The great genetic diversity of the causal agents of bacterial spot is the main problem to the development of tomato and pepper varieties with durable resistance. Seventy two strains of Xanthomonas spp. collected from commercial fields of processing tomatoes in the states of Goiás, Minas Gerais, Pernambuco, and Bahia were classified in races according to their reactions on differential genotypes of tomato (Walter, Hawaii 7998 and NIL 216) and Capsicum [ECW (Early Calwonder), ECW-10R, ECW-20R, ECW-30R and PI 235047]. Bacterial suspensions (5 ´ 10(8) UFC/ml) were infiltrated in the abaxial leaf face of the plants at the three to five true-leaf stage. The plants were then kept in a growth chamber at 28ºC and a 12-h light/dark photoperiod. The response reactions were observed up to 36 hours after inoculation, depending on the genotype. Races T1P2, T1P8 and T3 were identified in X. axonopodis pv. vesicatoria; race T2 in X. vesicatoria; and races T2P7 e T2P8 in 'X. gardneri'. The presence of genes avrRxv and avrXv3 was confirmed by polymerase chain reaction (PCR) with specific primers in strains that produced hypersensitive reaction on 'Hawaii 7998' (races T1) and 'NIL 216' (race T3), respectively. This is the first report of races T3, T1P8, T2P7 and T2P8 in Brazil

B Cells Specific for Bromelain-Treated Erythrocytes are not Derived from Adult Rat Bone Marrow

As part of an evolutionary layered hematopoietic system, the B lymphocyte compartment consists of different lineages of B lymphocytes, which evolve sequentially during ontogeny. In mice, there is ample evidence for the existence of at least two lineages, a layer of B-1 cells (Ly-1 B cells) and the evolutionary more advanced layer consisting of conventional B cells. In a previous study we were unable to detect B-1 cells in the rat as determined by phenotypic markers. Here we studied the possible existence of putative B-1 cells in the rat based on some functional and developmental characteristics as have been described for mouse B-1 cells. We show that B cells secreting antibodies that recognize bromelain-treated mouse red blood cells (BrMRBC) can be identified in rat spleen, whereas these cells (in contrast to DNP-specific B cells) are virtually absent in lethally X-irradiated and bone marrow (BM) reconstituted animals. The number of anti-rMRBC-secreting B cells could not be restored to control levels by reconstitution with fetal liver cells or by cotransfer of 107 cells from peritoneal cavity, lymph node or Peyer's patches or up to 2x10(8) splenocytes. Although our findings thus suggest that B-1 cells (or B-1 like cells) may be present in rats, formal proof for the existence of such a lineage in rats awaits definition of these cells at the progenitor level

Altered erythrocytes and a leaky block in B-cell development in CD24/HSA-deficient mice

The heat stable antigen (HSA, or murine CD24) is a glycosyl phosphatidylinositol-linked surface glycoprotein expressed on immature cells of most, if not all, major hematopoietic lineages, as well as in developing neural and epithelial cells. It has been widely used to stage the maturation of B and T lymphocytes because it is strongly induced and then repressed again during their maturation. Terminally differentiated lymphocytes, as well as most myeloid lineages, are negative for HSA. Erythrocytes are an exception in that they maintain high levels of HSA expression. HSA on naive B cells has been shown to mediate cell-cell adhesion, while HSA on antigen-presenting cells has been shown to mediate a costimulatory signal important for activating T lymphocytes during an immune response. Here, we characterize mice that lack a functional HSA gene, constructed by homologous recombination in embryonic stem cells. While T-cell and myeloid development appears normal, these mice show a leaky block in B-cell development with a reduction in late pre-B and immature B-cell populations in the bone marrow. Nevertheless, peripheral B-cell numbers are normal and no impairment of immune function could be detected in these mice in a variety of immunization and infection models. We also observed that erythrocytes are altered in HSA-deficient mice. They show a higher, tendency to aggregate and are more susceptible to hypotonic lysis in vitro. In vivo, the mean half-life of HSA-deficient erythrocytes was reduced. When infected with the malarial parasite Plasmodium chabaudi chabaudi, the levels of parasite-bearing erythrocytes in HSA-deficient mice were also significantly elevated, but the mice were able to clear the infection with kinetics similar to wild-type mice and were immune to a second challenge. Thus, apart from alterations in erythrocytes and a mild block in B-cell development, the regulated expression of HSA appears to be dispensable for the maturation and functioning of those cell lineages that normally express it

Sexual health promotion and nursing

The HIV epidemic provides continued impetus for effective sexual health promotion. Sexual health promotion in nursing practice has traditionally been equated to prevention at primary, secondary and tertiary levels. Increasing demands on practitioners to address the psycho-social aspects of sexual health, together with a greater emphasis on primary prevention, is leading to the adoption of theoretical paradigms from the behavioural sciences and the increasing use of counselling skills. The limitations of individualist interventions for primary prevention are explored, and the assumption that health care professionals are effective promoters of sexual health is questioned. The importance of placing sexual health and nursing practice within a wider social, political and cultural context is emphasized