Local BMP receptor activation at adherens junctions in the Drosophila germline stem cell niche.

According to the stem cell niche synapse hypothesis postulated for the mammalian haematopoietic system, spatial specificity of niche signals is maximized by subcellularly restricting signalling to cadherin-based adherens junctions between individual niche and stem cells. However, such a synapse has never been observed directly, in part, because tools to detect active growth factor receptors with subcellular resolution were not available. Here we describe a novel fluorescence-based reporter that directly visualizes bone morphogenetic protein (BMP) receptor activation and show that in the Drosophila testis a BMP niche signal is transmitted preferentially at adherens junctions between hub and germline stem cells, resembling the proposed synapse organization.

Protective effects of the flavonoid quercetin in chronic nitric oxide deficient rats.

Objectives: The present study analysed, for the first time, the effects of the flavonoid quercetin in rats after chronic inhibition of nitric oxide (NO) synthesis with Nomega-nitro-L-arginine methyl ester (L-NAME).

Design: Rats were divided randomly into five different treatment groups for 6 weeks: (1) vehicle (control, 1 ml of 1% methylcellulose once daily); (2) vehicle plus L-NAME (75 mg/100 ml in drinking water); (3) quercetin (10 mg/kg p.o.