Effect of collection time on the viability of banana pollen grains

The objective of this study was to assess the pollen viability of six improved diploid banana plants (AA) collected in different periods of the day, in two seasons of the year (winter and summer), using in vitro germination test and staining. Pollen grains collected at 8 am (anthesis), 10 am, 12 pm, 2 pm and 4 pm were evaluated. We used a culture medium for pollen germination containing 15% sucrose, 0.01% H3BO3, 0.01% KNO3, 0.03% Ca(NO3)2.4H2O, and 0.02% MgSO4.7H2O, solidified with 0.8% agar, adjusted to different pH. The pollen viability was evaluated by staining with 2,3,5-triphenyltetrazolium chloride (TTC). The highest pollen germination rates and viability were obtained at 8 am and the lowest at 4 pm, in both seasons. The average in vitro germination percentage and viability level were negatively influenced by the number of hours after anthesis. During the summer, the pollen viability and in vitro germination rates were highest when compared to winter period. The results presented can help at the selection of genetic materials and enable inferences on the best pollen collection time for use in cross breeding programs for plant improvement

A realização do teste anti-hiv no pré-natal: os significados para a gestante El establecimiento de la lucha contra la prueba del vih en pre-navidad: significados para el embarazo The establishment of anti-hiv test in pre-natal: meanings for pregnancy

O estudo teve por objetivo conhecer e analisar o significado da realização do teste anti-HIV no pré-natal para as gestantes. Trata-se de uma pesquisa com abordagem qualitativa e foi realizada em um Hospital Escola e em uma Maternidade do município do Rio de Janeiro. Como recurso técnico-metodológico utilizou-se o discurso do sujeito coletivo (DSC). Após a análise dos discursos verificamos que para as gestantes a realização do teste significa a possibilidade de prevenir a transmissão vertical do HIV e como parte da assistência pré-natal. O pré-natal foi considerado pelas gestantes uma excelente oportunidade para a realização do teste anti HIV, para o conhecimento da condição sorológica e início precoce do tratamento. Conclui-se que o teste, para a maioria das gestantes, representa a possibilidade de proteger o filho do HIV, além de fazer parte da construção do papel materno a partir de um cuidado concreto com a saúde do bebê.<br>El estudio que tenía para que el objetivo sepa y analice el significado de la realización del anti-VIH de la prueba en el prenatal para las mujeres embarazadas. Uno está sobre una investigación con acercamiento cualitativo y fue ejecutado en una escuela del hospital y una maternidad de la ciudad de Rio de Janeiro. Como recurso técnico-metodológico el discurso del ciudadano colectivo fue utilizado (DSC). Después de que el análisis de los discursos, nosotros verificamos que para las mujeres embarazadas la realización de la prueba significa la posibilidad para prevenir la transmisión vertical del VIH y como parte de la ayuda prenatal. El prenatal era considerado por las mujeres embarazadas una ocasión excelente para la realización del anti VIH de la prueba, para el conocimiento de la condición sorological y del principio precoz del tratamiento. Se concluye que la prueba, para la mayoría de las mujeres embarazadas, representa la posibilidad para proteger al hijo del VIH, más allá de ser parte de la construcción del papel maternal de un cuidado bien-tomado del concreto con la salud del bebé.<br>The study had as objective, the knowledge and the analyzis of the meaning of the accomplishment for the test anti-HIV in the prenatal one for the pregnant women. One is about a research with qualitative approach and was carried through in a Hospital School and a Maternity at the city of Rio de Janeiro. As a resource of technician-methodological, the speech of the collective citizen was used (DSC). After the analysis of the speeches we verified that, for the pregnant women the accomplishment of the test means the possibility to prevent the vertical transmission of the HIV and as part of the prenatal assistance. The prenatal one was considered by the pregnant women an excellent chance for the accomplishment of the test anti HIV, for the knowledge of the serological condition and precocious beginning of the treatment. It is concluded that the test, for the majority of the pregnant women, represents the possibility to protect the son of the HIV, beyond being part of the construction of the maternal paper from a well-taken care of concrete with the health of the baby

Influence of melatonin on the development of functional nicotinic acetylcholine receptors in cultured chick retinal cells

The influence of melatonin on the developmental pattern of functional nicotinic acetylcholine receptors was investigated in embryonic 8-day-old chick retinal cells in culture. The functional response to acetylcholine was measured in cultured retina cells by microphysiometry. The maximal functional response to acetylcholine increased 2.7 times between the 4th and 5th day in vitro (DIV4, DIV5), while the Bmax value for [125I]-alpha-bungarotoxin was reduced. Despite the presence of alpha8-like immunoreactivity at DIV4, functional responses mediated by alpha-bungarotoxin-sensitive nicotinic acetylcholine receptors were observed only at DIV5. Mecamylamine (100 µM) was essentially without effect at DIV4 and DIV5, while dihydro-ß-erythroidine (10-100 µM) blocked the response to acetylcholine (3.0 nM-2.0 µM) only at DIV4, with no effect at DIV5. Inhibition of melatonin receptors with the antagonist luzindole, or melatonin synthesis by stimulation of D4 dopamine receptors blocked the appearance of the alpha-bungarotoxin-sensitive response at DIV5. Therefore, alpha-bungarotoxin-sensitive receptors were expressed in retinal cells as early as at DIV4, but they reacted to acetylcholine only after DIV5. The development of an alpha-bungarotoxin-sensitive response is dependent on the production of melatonin by the retinal culture. Melatonin, which is produced in a tonic manner by this culture, and is a key hormone in the temporal organization of vertebrates, also potentiates responses mediated by alpha-bungarotoxin-sensitive receptors in rat vas deferens and cerebellum. This common pattern of action on different cell models that express alpha-bungarotoxin-sensitive receptors probably reflects a more general mechanism of regulation of these receptors