Pronase reduces intramembranous particle density in uterine epithelial cells in vivo

The proteolytic enzyme, pronase, was injected into the uterine lumen of rats. This treatment removed half the intramembranous particles (IMPs) from the apical plasma membrane of the uterine epithelial cells but tight junctions of these cells were unaffected. We conclude that at least some of the IMPs are proteinaceous in nature and suggest that IMPs not affected by pronase may be deeply embedded in the lipid bilayer.     

The cucumber mosaic virus 1a protein regulates interactions between the 2b protein and ARGONAUTE 1 while maintaining the silencing suppressor activity of the 2b protein

The cucumber mosaic virus (CMV) 2b viral suppressor of RNA silencing (VSR) is a potent counter-defense and pathogenicity factor that inhibits antiviral silencing by titration of short double-stranded RNAs. It also disrupts microRNA-mediated regulation of host gene expression by binding ARGONAUTE 1 (AGO1). But in Arabidopsis thaliana complete inhibition of AGO1 is counterproductive to CMV since this triggers another layer of antiviral silencing mediated by AGO2, de-represses strong resistance against aphids (the insect vectors of CMV), and exacerbates symptoms. Using confocal laser scanning microscopy, bimolecular fluorescence complementation, and co-immunoprecipitation assays we found that the CMV 1a protein, a component of the viral replicase complex, regulates the 2b-AGO1 interaction. By binding 2b protein molecules and sequestering them in P-bodies, the 1a protein limits the proportion of 2b protein molecules available to bind AGO1, which ameliorates 2b-induced disease symptoms, and moderates induction of resistance to CMV and to its aphid vector. However, the 1a protein-2b protein interaction does not inhibit the ability of the 2b protein to inhibit silencing of reporter gene expression in agroinfiltration assays. The interaction between the CMV 1a and 2b proteins represents a novel regulatory system in which specific functions of a VSR are selectively modulated by another viral protein. The finding also provides a mechanism that explains how CMV, and possibly other viruses, modulates symptom induction and manipulates host-vector interactions.     

Pigments and ultrastructures of pigment cells in xanthic sailfin mollies (Poecilia latipinna).

Electron micrographs of skin from xanthic (gold) sailfin mollies revealed numerous xanthophores, as well as scattered melanophores. The melanophores were seen to contain premelanosomes in various stages of development. This is consistent with the fact that xanthic mollies have been shown to be tyrosinase positive. Melanosomes in xanthic mollies appear to develop by one of two pathways: 1) from an endoplasmic reticulum-derived vesicle which develops an internal lamellar framework, and 2) by fusion of multiple Golgi-derived vesicles which lack an internal lamellar framework. Analysis of the pigments in the skin of the xanthic mollies identified four colorless pteridine pigments (xanthopterin, isoxanthopterin, neopterin, and pterin) and a carotenoid with an absorbance spectrum similar to beta-carotene. It appears that, unlike some other poeciliid fishes, sailfin mollies do not use pteridine pigments for orange coloration. Rather, they appear to rely primarily on carotenoids.