An experimental study was made of the distribution of the primary hypoblastic cells in the lower layer of the avian blastoderm throughout primitive streak formation and until stage 10 (Hamburger & Hamilton, 1951). The primary hypoblast of stage XIII (Eyal-Giladi & Kochav, 1976) chick blastoderms was exchanged for either an [H3]thymidine-labelled similar chick hypoblast, or a quail primary hypob...

symptoms of the leaf scorch disease on the leaves of oleander infected by xylella fastidiosa appearing for the first time in lebanon were confirmed by elisa tests and anatomical observations of sections of petioles by a scanning electron microscope. xylella fastidiosa was detected in the xylem forming bacterial aggregates in the lumen of tracheary elements. the bacterium colonizes and invades t...

purpose: to present a case of pseudoxanthoma elasticum (pxe) with ocular involvement and visual loss. case report: a 36 year old male presented with severe visual loss since 2 years ago. on funduscopy peau d’orange appearance and angioid streaks were evident. the diagnosis of pxe was confirmed by skin biopsy of papular lesions on the neck. conclusion:  ocular findings may be helpful in the diag...

Bacterial leaf streak caused by Xanthomonas oryzae pv. oryzicola (Xoc) is one of the most important diseases in rice. However, little is known about the pathogenicity mechanisms of Xoc. Here we have investigated the function of three HD-GYP domain regulatory proteins in biofilm formation, the synthesis of virulence factors and virulence of Xoc. Deletion of rpfG resulted in altered production of...

Xanthomonas translucens is the causal agent of bacterial leaf streak, the most common bacterial disease of wheat and barley. To cause disease, most xanthomonads depend on a highly conserved type III secretion system, which translocates type III effectors into host plant cells. Mutagenesis of the conserved type III secretion gene hrcT confirmed that the X. translucens type III secretion system i...

Xanthomonas oryzae pv. oryzicola (Xoc) causes bacterial leaf streak (BLS) in rice, a serious bacterial disease of rice in Asia and parts of Africa. The virulence mechanisms of Xoc are not entirely clear and control measures for BLS are poorly developed. The solo LuxR proteins are widespread and shown to be involved in virulence in some plant associated bacteria (PAB). Here, we have cloned and c...

Harpins are produced by gram-negative phytopathogenic bacteria and typically elicit hypersensitive response (HR) in non-host plants. The characterization of harpins in Xanthomonas species is largely unexplored. Here we demonstrate that Xanthomonas produce a highly conserved single-stranded DNA-binding protein (SSB(X)) that elicits HR in tobacco as by harpin Hpa1. SSB(X), like Hpa1, is an acidic...