background: nicotine can pass through placental blood barrier and accumulate in the developing organs of fetus. also, entering the breast milk, nicotine can have an effect on the neonates. investigations have showed that collagen iv is one of the most important micro vessels basement membrane components. objective:  in this study, the effect of maternal nicotine exposure in pre and postnatal pe...

Pili appear to promote the pathogenicity of gonococci (Gc)' by mediating their attachment to human hosts' mucosal surfaces (1, 2) . Although all Gc pili are assumed to have adherence-promoting properties, they exhibit structural diversity between strains and among variants of a given strain (3-8). This diversity is due to differences in the amino acid sequences of their pilus subunit (pilin) po...

The structural similarity between the pilin glycan and the O-antigen of Pseudomonas aeruginosa 1244 suggested that they have a common metabolic origin. Mutants of this organism lacking functional wbpM or wbpL genes synthesized no O-antigen and produced only non-glycosylated pilin. Complementation with plasmids containing functional wbpM or wbpL genes fully restored the ability to produce both O...

The bundle-forming pilus (BFP) of enteropathogenic Escherichia coli (EPEC) is an important virulence factor. We examined the role of divergent alleles of bfpA encoding bundlin, the BFP pilin protein, in pilus biogenesis, pilus interactions, and immune responses. We found that the BFP biogenesis machine from an EPEC strain that expresses one bundlin type is capable of assembling all other bundli...

Antipeptide antibodies were used to detect, purify, and characterize nonfilament F-pilin in the cell envelope of an F'tra+ strain of Escherichia coli. Affinity-purified goat antibodies raised against a peptide corresponding to the amino-terminal 14 amino acids of F-pilin detected F-pilin in immuno-overlay ("Western") blots of electrophoretically separated inner and outer membrane proteins. As e...

Helicobacter pylori colonizes the gastric mucosa of humans and, if left untreated, this will result in a lifelong gastritis. Although infection is usually asymptomatic, it can manifest clinically as peptic or duodenal ulcers. Additionally, colonization with H.pylori is believed to induce gastric atrophy and increase the risk of gastric cancer. New genotypes of H. pylori are generated by recombi...

The human pathogen Eikenella corrodens expresses type IV pili and exhibits a phase variation involving the irreversible transition from piliated to nonpiliated variants. On solid medium, piliated variants form small (S-phase), corroding colonies whereas nonpiliated variants form large (L-phase), noncorroding colonies. We are studying pilus structure and function in the clinical isolate E. corro...

Force production by type IV pilus retraction is critical for infectivity of Neisseria gonorrhoeae and DNA transfer. We investigated the roles of pilus number and the retraction motor, PilT, in force generation in vivo at the single-molecule level and found that individual retraction events are generated by a single pilus fiber, and only one PilT complex powers retraction. Retraction velocity is...

Natural genetic transformation is widely distributed in bacteria and generally occurs during a genetically programmed differentiated state called competence. This process promotes genome plasticity and adaptability in Gram-negative and Gram-positive bacteria. Transformation requires the binding and internalization of exogenous DNA, the mechanisms of which are unclear. Here, we report the discov...

The ATPase protein PilT mediates retraction of type IV pili (Tfp). Tfp retraction of Neisseria gonorrhoeae causes many signal transduction events and changes in gene expression in infected epithelial cells. To find out whether a pilT mutation and lack of Tfp retraction, respectively, lead also to gene regulation in bacteria, we performed microarrays comparing the transcriptional profiles of the...