A. S. Costa

Morfologia do vírus do mosaico comum da mandioca

Exames no microscopio electronico de preparacoes feitas pelo metodo do «dipping», de plantas infetadas com o virus do mosaico comum da mandioca (VMCM), demonstraram a presenca de particulas alongadas e flexiveis, com 13mμ de diâmetro e cerca de 500mμ de comprimento normal (CN) nas plantas infetadas, mas nao nas sadias (controles). Particulas similares, em grande quantidade, foram as unicas presentes em preparacoes altamente purificadas e infetivas. Essas particulas, quando contrastadas negativamente, nao mostraram possiveis detalhes ultra-estruturais. Medicoes comparativas entre o VMCM e o virus X da batatinha (VXB), que se assemelham morfologicamente, demonstraram que o CN do VMCM foi consistentemente menor que o do VXB em cerca de 17 mμ. Em testes serologicos cruzados, com antissoro para VMCM e VXB de titulos relativamente altos (1/4096), nenhum grupo antigenico aos dois virus pode ser demonstrado. Devido a morfologia das particulas, o VMCM pode ser incluido entre os virus relacionados com o VXB, dos grupos 4 a 6 da classificacao dos virus de planta de forma alongada, proposta por Brandes e Wetter. As particulas desses virus tem sido descritas como filamentosas e flexiveis, de CN entre 480 e 580 mμ. A pequena mas perceptivel diferenca na morfologia, o fato de que grupos antigenicos comuns nao puderam ser demonstrados, e as grandes diferencas no comportamento em relacao as molestias causadas pelo VMCM e o VXB, indicam nao serem eles proximamente relacionados. O VMCM poderia ser considerado como uma entidade distinta dentro do grupo taxonomico dos virus de planta alongados, representado pelo VXB.

Morfologia do vírus do mosaico do picão

Electron microscopical observations were made on exudates obtained from plants of Bidrus pilosa, Chenopodium amaranticolor Leonolis nepaetifolia, Helianthus annums. Nicotiana tabucum, Cassia occidentalis, Chenopodium ambrosioides, and Physalis floridona infected with a virus that induces mosaic on the first named species. The presenes of a flexible thread with a normal length 720 mm. x 12-13 mm was recorded in the exudates from the: diseased plants, but not in those from the healthy ones, and is considered to represent the causal virus.

Moléstias de vírus do algodoeiro

Four virus diseases can be encountered in. cotton plantings (Gossypimn hirsutum) in the state of Sao Paulo: (a) common yellow mosaic due to the Abutilon mosaic virus; (b) vein mosaic due to an unidentified virus; (c) green mosaic induced by the Brazilian tobacco streak virus and (d) cotton anthocyanosis due to o persistent virus transmitted by the cotton or melon aphid, Aphis gossypii. Cotton yellow mosaic occurs in all plantings, but the percentage of infected plants is usually low; vein mosaic is of rare occurrence; percentage of infection with green mosaic can be high late in the season. The theree types of mosaic are of minor importance under most conditions, no control measure being necessary. Cotton anthocyanosis is at present the most important virus disease of this plant in Sao Paulo. Late in the season practically all plants become infected. Seed treatment with systemic insecticides and field spraying after the effect of the seed treatment wears off are recommended to reduce aphid infestation and therefore minimize secondary spread of the disease.

Estado nutricional de adolescentes do Maranhão, Brasil, por critérios nacional e internacional

This study sought to compare national and international criteria for assessing the nutritional status of adolescents. A cross-sectional analytical study was conducted in the period from July 2007 to January 2008 with a representative sample comprised of 1256 adolescents from the state of Maranhao. Body mass index (BMI) for age and gender was used to diagnose underweight, normal weight and overweight, using the criteria proposed by Conde and Monteiro and the World Health Organization (WHO). Chi-square, McNemar concordance and Spearman correlation tests were applied. According to the criteria of Conde and Monteiro and the WHO, there were significant differences among the boys with respect to low weight and obesity. It was observed that there was no significant divergence between the two criteria, and a significant positive correlation (0.011) between the two criteria was detected. With this analysis it can be seen that there are many divergences between the criteria used, therefore the best option and the advantage of using one or the other cannot be singled out. However, it should be stressed that the national criterion can also be used more, since there are no significant differences with the criteria advocated by the Ministry of Health of the WHO.

Ocorrência de vírus esférico causando faixa amarela das nervuras da couve em São Paulo

Particulas esferoidais de 50-60mμ de diâmetro foram encontradas em preparacoes semipurificadas e em preparacoes rapidas de plantas de couve infetadas com um virus que induz faixa amarela das nervuras (VFANC). Essas particulas tem um capsideo aparentemente icosaedral, constituido de 92 capsomeros de 50-60 A de diâmetro. Quando tratadas com acetato de uranila, revelaram a existencia de uma zona central, que se impregna fortemente com este corante, possivelmente constituida de nucleoproteina. Tais particulas nao foram encontradas em plantas sadias, mas foram nelas detectadas, apos serem inoculadas por uniao de tecidos, por meios mecânicos ou por afideos com VFANC. Particulas similares foram encontradas em seccoes ultra-finas de tecido foliar de couve infetado com o VFANC, porem apresentavam um diâmetro ligeiramente menor, da ordem de 35-45mμ. Invariavelmente, essas particulas foram encontradas em meio as inclusoes citoplasmaticas de forma e dimensoes variadas, constituidas de uma massa amorfa, granular e densa. Tais inclusoes puderam tambem ser observadas em seccoes mais espessas e montadas para microscopia optica. Possivelmente o VFANC pertence ao grupo do virus do mosaico da couve-flor, dada a semelhanca na morfologia das particulas e nas molestias induzidas.

Microscopia electrônica de estirpes do vírus Y da batatinha que ocorrem em São Paulo

Seven isolates of the potato virus Y collected from various sources in the state of Sao Paulo, Brazil, were compared in their morphology with the typical potato strain The preparations were made by the exudate or dipping methods and examined in a Siemens Elmiskop I electron-microscope Elongated, flexible virus particles found in the preparations of all isolates did not differ significantly from the normal length, about 730 mm, reported for the potato Y virus in other places. One of the isolates, designated as YP (normal length 723.8 mμ.) showed a tendency to be slightly shorter than the average and two others, YW and YWRio (normal lengths 737 mμ and 737.8 mμ) were slightly longer than this value. The similarity in the morphology of all isolates is considered as satisfactory evidence that they are all related.

Ocorrência do vírus do mosqueado do morangueiro no estado de São Paulo

Verificou-se a ocorrencia de estirpes do virus do grupo denominado mosqueado («strawberry mottle») em plantacoes de morangueiro no Estado de Sao Paulo. Variedades antigas, como a Dr. Morere. acham-se totalmente infetatas. sendo portadoras sem sintomas. Alguns clones novos plantados apenas por poucos anos em campo, ja se acham parcialmente infetados, indicando que ha transmissao da molestia sob condicoes naturais. Sintomas de palidez das nervuras, mosqueado, paralisacao no crescimento e encrespamento sao apresentados por plantas de Fragaria vesca infetadas pelos virus desse grupo. Numerosas especies de plantas-teste habituais foram inoculadas com diferentes isolados do virus, por meio do vetor, mas os resultados foram geralmente negativos. Afidios viruliferos, colonizados sobre plantas novas de Cassia accidentalis, Chenopodiam quinoa, Leonotis nepaetifolia e Leonurus sibiricus. induziram o aparecimento de sintomas. Nao se conseguiu retransmitir o virus dessas especies para F. vesca, existindo, portanto, duvidas sobre a verdadeira identidade do virus que infetava tais plantas. O virus do mosqueado nao foi aparentemente transmitido pela semente. Tambem nao se mostrou transmissivel mecânicamente para Frogaria vesca. O virus obtido por inoculacao com o vetor em Chenopodium quinoa e que se supoe ser o do mosqueado, pode se transmitido mecânicamente de C. quinoa para C. quinoa. mas nao para F. vesca. O pulgao Pentatrichopus fragaefolii mostrou-se eficiente vetor do mosqueado, conseguindo-se obter em media mais de 50% de infeccao em infestacoes com 1 afidio por planta. Aphis gossypii tambem transmitiu o virus do mosqueado, mas com muito menor eficiencia. Nao se conseguiu transmitir o mosqueado com uma especie de Cuscuta que ocorre comumeute em Campinas. Em testes de transmissao por enxertia de folhas, os resultados foram muito fracos devido ao mau pegamento. O pulgao Pentatrichopus fragaefolii tornou-se virulifero quando alimentado em planta infetada por 30 minutos. Com o aumento no periodo de alimentacao na fonte de virus aumentou a eficiencia de transmissao. Insetos viruliferos foram capazes de infetar plantas sadias quando alimentados sobre elas por 15 minutos. Insetos viruliferos alimentados por 1 hora em planta sadia ainda retinham o virus. Apos 6 horas de alimentacao ja nao mais o retinham.

Morfologia das partículas do vírus do anel do pimentão

Tubular particles, about 25 m¼ wide, with an axial channel 4 m¼ in diameter, were found in leaf dip or purified preparations and also within tissues, from plants infected with pepper ringspot virus (PRSV), but not in uninoculated control plants. The particle length determinations showed two prevalent types of particles in vitro, respectively with ca. 55 m¼ and 200 m¼ in normal length. These values were independent of the virus isolate, host plant or preparative procedures for electron microscopy employed. In thin section profiles, a dense rim was observed bordering the axial channel, in cross section of particles stained with uranyl acetate, which might represent the location of the viral nucleic acid in the virion. The long, 200 m¼, particles can be separated from the short, 55 m¼ particles through sucrose gradient density ultracentrifugation, when it can be demonstrated that only the longer particles are infective. Incubation of purified preparations with ribonuclease and/or trypsin, did not affect infectivity or the structure of the virions. However, in some experiments, the trypsin treatment induced an end-to-end aggregation of the particles. Purified preparations lose infectivity after being heated for 10 minutes at 65-70°C. Simultaneously a generalized degradation of virions is noticeable. The end product of this degradation is a powdery material, composed of granules 30-40 Ao in diameter. In ultrathin sections of PRSV-infected tissues, ordered aggregates of particles, similar to those found in vitro,were observed in the cytoplasm. Such inclusions consisted of long (200 m¼) particles only. In no instance, groups of typical 55 m¼, short particles were found, and this suggests that they are fragments of the longer, 200 m¼. particles, rather than products of self multiplication.

Microscopia electrônica de inclusões citoplas máticas e alterações celulares associadas ao vírus do mosaico da cenoura

A virus, inducing mosaic and malformation of carrot leaves (Daucus carota L.), was found in Piedade, SP. It was termed carrot mosaic virus (CMV), and is both mechanically and aphid transmitted. Morphologically it belongs to the potato virus Y group (15m¼ x 740m¼). Electron microscopic examination of thin sections of leaf tissues from carrot or coriander (Coriandrum sativum L.) infected with CMV demonstrated the presence of cytoplasmic inclusions, usually in the form of dense bands. They could reach sizes up to 0.2¼ x 4¼ and were detectable even under light microscopic examination. These bands, at higher magnification, showed to be built up of thin lamella (10-15m¼ thick), closely apposed. Occasionally individual or group of lamella appeared to loose from the bands, producing other type of profile, such as pin wheels and rings. CMV particles were sometimes observed in the vicinity of these inclusions, often laying parallel to their surface. These inclusions are identical to those observed in tissues infected with other components of the potato Y virus group, and their detection seems to corroborate the previous inclusion of CMV in this group, basead on particle morphology. Besides these cytoplasmic inclusions, some cells contained a large number of vesicles in the cytoplasm, apparently associated with Golgi complex activity.

Deficiências minerais nas fôlhas induzidas por moléstias e pragas

Virus diseases or the toxicogenic effect induced by insect feeding influence the mineral content of affected plants. Some of the changes induced result in leaf deficiencies similar to those associated with lack of the available element in the soil. Application of the lacking element in most cases does not promote a favorable response with exception of the zinc deficiency associated with tristeza infection in citrus. It is suggested that the negative or positive response might depend on the symptom being primary or secondary. It is pointed out that fertilizer recommendations based on foliar diagnosis should always take into consideration that the deficiencies encountered are not necessarily theresult of lack of the available element in thesoil, but sometimes of the interference of virus diseases, insect toxins, and other factors.