Distribution of non-AT(1), non-AT(2) binding of (125)I-Sarcosine(1), Isoleucine(8) angiotensin II in neurolysin knockout mouse brains

The recent identification of a novel binding site for angiotensin (Ang) II as the peptidase neurolysin (E.C. 3.4.24.16) has implications for the renin-angiotensin system (RAS). This report describes the distribution of specific binding of 125I-Sarcosine1, Isoleucine8 Ang II (125I-SI Ang II) in neurolysin knockout mouse brains compared to wild-type mouse brains using quantitative receptor autoradiography. In the presence of p-chloromercuribenzoic acid (PCMB), which unmasks the novel binding site, widespread distribution of specific (3 microM Ang II displaceable) 125I-SI Ang II binding in 32 mouse brain regions was observed. Highest levels of binding >700 fmol/g initial wet weight were seen in hypothalamic, thalamic and septal regions, while the lowest level of binding <300 fmol/g initial wet weight was in the mediolateral medulla. 125I-SI Ang II binding was substantially higher by an average of 85% in wild-type mouse brains compared to neurolysin knockout brains, suggesting the presence of an additional non-AT1, non-AT2, non-neurolysin Ang II binding site in the mouse brain. Binding of 125I-SI Ang II to neurolysin in the presence of PCMB was highest in hypothalamic and ventral cortical brain regions, but broadly distributed across all regions surveyed. Non-AT1, non-AT2, non-neurolysin binding was also highest in the hypothalamus but had a different distribution than neurolysin. There was a significant reduction in AT2 receptor binding in the neurolysin knockout brain and a trend towards decreased AT1 receptor binding. In the neurolysin knockout brains, the size of the lateral ventricles was increased by 56% and the size of the mid forebrain (-2.72 to +1.48 relative to Bregma) was increased by 12%. These results confirm the identity of neurolysin as a novel Ang II binding site, suggesting that neurolysin may play a significant role in opposing the pathophysiological actions of the brain RAS and influencing brain morphology

One sixth of Amazonian tree diversity is dependent on river floodplains

Amazonia’s floodplain system is the largest and most biodiverse on Earth. Although forests are crucial to the ecological integrity of floodplains, our understanding of their species composition and how this may differ from surrounding forest types is still far too limited, particularly as changing inundation regimes begin to reshape floodplain tree communities and the critical ecosystem functions they underpin. Here we address this gap by taking a spatially explicit look at Amazonia-wide patterns of tree-species turnover and ecological specialization of the region’s floodplain forests. We show that the majority of Amazonian tree species can inhabit floodplains, and about a sixth of Amazonian tree diversity is ecologically specialized on floodplains. The degree of specialization in floodplain communities is driven by regional flood patterns, with the most compositionally differentiated floodplain forests located centrally within the fluvial network and contingent on the most extraordinary flood magnitudes regionally. Our results provide a spatially explicit view of ecological specialization of floodplain forest communities and expose the need for whole-basin hydrological integrity to protect the Amazon’s tree diversity and its function

Correlações entre caracteres agronômicos em dois ciclos de seleção recorrente em milho-pipoca Correlations among agronomic traits in two recurrent selection cycles in popcorn

Com o propósito de monitorar o comportamento de blocos gênicos em diferentes gerações de seleção recorrente em milho pipoca, quantificaram-se as correlações fenotípica, genotípica e de ambiente entre caracteres agronômicos, em dois ciclos de seleção recorrente. O primeiro ciclo foi formado por famílias de irmãos completos e o segundo ciclo por famílias S1. Embora não significativa, em ambos os ciclos, houve correlação genotípica negativa entre capacidade de expansão e rendimento de grãos. Para o segundo ciclo, as maiores magnitudes de correlação genotípica positiva ocorreram entre rendimento de grãos, número de espigas sadias e estande, indicando a possibilidade de sucesso na seleção de uma ou outra, com base no rendimento de grãos. Embora não significativa e em baixa magnitude, houve acréscimo da correlação genotípica entre rendimento de grãos e capacidade de expansão do primeiro para o segundo ciclo, denotando aumento na concentração de alelos favoráveis na população.<br>This work was carried out to estimate environment, genotypic and phenotypic correlations among traits in two intrapopulational recurrent selection cycles in popcorn. The first cycle was composed by full sib families and the second cycle by S1 families. Seventy-five families of full sib and two hundred and twenty two families S1 were evaluated in randomized complete block design with two replicates in two environments. Although not statistically significant, genotypic correlation between grain yield and popping expansion was negative in both selection cycles. For the second cycle of recurrent selection, the highest positive estimates of genotypic correlations were found between: grain yield and number of ears and grain yield and stand, indicating the perspective of the success for selection based on grain yield. Although in less magnitude there was an increase in genotypic correlation between the grain yield and popping expansion from the first to the second cycle of recurrent selection, indicating increase in the favorable allele frequencies in both traits