Light controls stamen elongation via cryptochromes,phytochromes and COP1 through HY5 and HYH

In Arabidopsis, stamen elongation, which ensures male fertility, is controlled by the auxin response factor ARF8, which regulates the expression of the auxin repressor IAA19. Here, we uncover a role for light in controlling stamen elongation. By an extensive genetic and molecular analysis we show that the repressor of light signaling COP1, through its targets HY5 and HYH, controls stamen elongation, and that HY5 – oppositely to ARF8 – directly represses the expression of IAA19 in stamens. In addition, we show that in closed flower buds, when light is shielded by sepals and petals, the blue light receptors CRY1/CRY2 repress stamen elongation. Coherently, at flower disclosure and in subsequent stages, stamen elongation is repressed by the red and far‐red light receptors PHYA/PHYB. In conclusion, different light qualities – sequentially perceived by specific photoreceptors – and the downstream COP1–HY5/HYH module finely tune auxin‐induced stamen elongation and thus male fertility.     

Comparative studies of the immunogenicity and protective potential of biofilm vs planktonic Staphylococcus aureus vaccine against bovine mastitis using non-invasive mouse mastitis as a model system

This study was undertaken to compare the immunogenicity and protective potential of biofilm vs planktonic Staphylococcus aureus vaccine for the prevention of mastitis using the mouse as a model system. Mice immunized with formalin-killed whole cell vaccine of S. aureus residing in a biofilm when delivered via an intramammary route produced a cell mediated immune response. Mice immunized with this biofilm vaccine showed significant reductions in colonization by S. aureus in mammary glands, severity of clinical symptoms and tissue damage in mammary glands in comparison with the mice immunized with formalin-killed whole cells of planktonic S. aureus. The planktonic vaccine administered by a subcutaneous route produced a significantly higher humoral immune response (IgG₁ and IgG) than the biofilm vaccine. However, considering the host response, tissue damage, the clinical severity and colonization of S. aureus in mammary glands, the biofilm vaccine performed better in immunogenicity and protective potential when administered by the intramammary route.     

Experimental evidence suggesting that nitric oxide diffuses from tissue into blood but not from blood into tissue

The aim of this study was to evaluate in vivo whether nitric oxide (NO) is able to diffuse from blood into tissues and vice versa from tissues into blood. We used an in vivo model of intestinal ischemia (superior mesenteric artery occlusion) selectively increasing NO levels in intestinal tissue and an infusion of L-arginine selectively increasing NO levels in blood. In this model we followed formation of nitrosyl complexes of hemoglobin (Hb-NO) in blood and nitrosyl-diethyldithiocarbamate-iron complexes (DETC--Fe--NO) in ischemic intestine and normoxic tissues by means of electron paramagnetic resonance spectroscopy. NO trapping by DETC--Fe in the tissues resulted in a reduction of Hb--NO levels in blood accompanied by the formation of water-insoluble DETC--Fe-NO complexes in ischemic intestine and normoxic tissues both during ischemia and during reperfusion. Administration of L-arginine increased NO levels in blood but neither in ischemic intestine nor in normoxic tissue. Our data suggest that NO released in blood from endothelial cells does not diffuse into tissue. In contrast, NO formed in tissue diffuses into blood. The latter indicates that NO formed in tissues may exert its biological activities systematically.