Characteristics of C-4 photosynthesis in stems and petioles of C-3 flowering plants

Most plants are known as C-3 plants because the first product of photosynthetic CO2 fixation is a three-carbon compound. C-4 plants, which use an alternative pathway in which the first product is a four-carbon compound, have evolved independently many times and are found in at least 18 families. In addition to differences in their biochemistry, photosynthetic organs of C-4 plants show alterations in their anatomy and ultrastructure. Little is known about whether the biochemical or anatomical characteristics of C-4 photosynthesis evolved first. Here we report that tobacco, a typical C-3 plant, shows characteristics of C-4 photosynthesis in cells of stems and petioles that surround the xylem and phloem, and that these cells are supplied with carbon for photosynthesis from the vascular system and not from stomata. These photosynthetic cells possess high activities of enzymes characteristic of C-4 photosynthesis, which allow the decarboxylation of four-carbon organic acids from the xylem and phloem, thus releasing CO2 for photosynthesis. These biochemical characteristics of C-4 photosynthesis in cells around the vascular bundles of stems of C-3 plants might explain why C-4 photosynthesis has evolved independently many times

HIV-1 Envelope Subregion Length Variation during Disease Progression

The V3 loop of the HIV-1 Env protein is the primary determinant of viral coreceptor usage, whereas the V1V2 loop region is thought to influence coreceptor binding and participate in shielding of neutralization-sensitive regions of the Env glycoprotein gp120 from antibody responses. The functional properties and antigenicity of V1V2 are influenced by changes in amino acid sequence, sequence length and patterns of N-linked glycosylation. However, how these polymorphisms relate to HIV pathogenesis is not fully understood. We examined 5185 HIV-1 gp120 nucleotide sequence fragments and clinical data from 154 individuals (152 were infected with HIV-1 Subtype B). Sequences were aligned, translated, manually edited and separated into V1V2, C2, V3, C3, V4, C4 and V5 subregions. V1-V5 and subregion lengths were calculated, and potential N-linked glycosylation sites (PNLGS) counted. Loop lengths and PNLGS were examined as a function of time since infection, CD4 count, viral load, and calendar year in cross-sectional and longitudinal analyses. V1V2 length and PNLGS increased significantly through chronic infection before declining in late-stage infection. In cross-sectional analyses, V1V2 length also increased by calendar year between 1984 and 2004 in subjects with early and mid-stage illness. Our observations suggest that there is little selection for loop length at the time of transmission; following infection, HIV-1 adapts to host immune responses through increased V1V2 length and/or addition of carbohydrate moieties at N-linked glycosylation sites. V1V2 shortening during early and late-stage infection may reflect ineffective host immunity. Transmission from donors with chronic illness may have caused the modest increase in V1V2 length observed during the course of the pandemic

Análise crítica da Carta Brasileira de Prevenção Integrada na Área da Saúde na Perspectiva da Educação Física através do enfoque radical de promoção da saúde

O presente trabalho pretende contribuir para que a área profissional e o campo do saber referente à Educação Física apreendam a saúde de forma ampliada, superando o enfoque biologicista hegemônico. Possui caráter qualitativo e baseou-se em pesquisa de fontes bibliográficas para a confecção de monografia de conclusão do curso de especialização em Saúde Pública, na Escola Nacional de Saúde Pública Sergio Arouca da Fundação Oswaldo Cruz. Analisou-se criticamente a Carta Brasileira de Prevenção Integrada na área da Saúde na perspectiva da Educação Física - publicação do Conselho Federal de Educação Física (CONFEF), em 2006, a partir do enfoque radical da Promoção da Saúde. Esse enfoque pode ser sintetizado na proposta de articulação entre saúde e condições de vida, ressaltando as inter-relações de equidade social, através do aumento da capacidade da participação popular, intersetorialidade, fomento de políticas públicas saudáveis, criação de ambientes favoráveis à saúde e reorientação do sistema de saúde, baseando-se numa visão ampliada do processo saúde-doença e reconhecendo a multideterminação desse processo (OMS, 1986; Buss, 2000, 2001, 2007; Pedrosa, 2004). Concluiu-se que o documento analisado biologiza e medicaliza a Educação Física em sua relação com a sociedade. Recomenda-se que o mesmo seja revisto a partir da perspectiva crítica ligada à área da Educação Física, a qual relaciona a atividade física e a saúde com questões sociais mais amplas que impedem que os sujeitos tomem decisões mais saudáveis, tais como os condicionantes econômicos, culturais, étnicos e políticos.This work intends to provide a contribution so that the professional area and the field of knowledge referring to Physical Education view health in a broader way, overcoming the biological focus which usually occurs. It has a qualitative character and was based on research into bibliographic sources in order to develop a monograph upon the completion of the Public Health specialization course at the National School of Public Health Sergio Arouca, of the Oswaldo Cruz Foundation. The Brazilian Charter of Integrated Prevention in the Field of Health in the Perspective of Physical Education, a document written by the Federal Council of Physical Education (CONFEF) in 2006, was critically analyzed based on the radical focus of Health Promotion. This focus can be summarized as an articulation between health and life conditions, emphasizing social equity interrelations, through the increase in the capacity for popular participation, intersectoriality, promotion of healthy public policies, creation of environments that are favorable to health, and through a reorientation of the health system, based on a broader view of the health-disease process and on the recognition of the multi-determination of this process (OMS, 1986; Buss, 2000, 2001, 2007; Pedrosa, 2004). We concluded that the document that we analyzed assumes a biological and medical view concerning the relation between Physical Education and society. We recommend that this document is revised based on the critical perspective connected with the Physical Education field, which relates physical activities and health to broader social issues which prevent subjects from making healthier decisions, such as economic, cultural, ethnic and political conditioning factors