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In an attempt to dissect the virulence mechanisms of Yersinia ruckeritwo adjacent genes, yrpAand yrpB, encoding putative peptidases belonging to the U32 family, were analyzed. Similar genes, with the same genetic organization were identified in genomic analysis of human-pathogenic yersiniae. RT-PCR studies indicated that these genes form an operon in Y. ruckeri. Transcriptional studies using an yrpB::lacZYfusion showed high levels of expression of these genes in the presence of peptone in the culture medium, as well as under oxygen-limited conditions. These two factors had a synergic effect on gene induction when both were present simultaneously during bacterial incubation, which indicates the important role that environmental conditions in the fish gut can play in the regulation of specific genes. LD50experiments using an yrpAinsertional mutant strain demonstrated the participation of this gene in the virulence of Y. ruckeri.

Existen muchas publicaciones que apoyan el papel de los lípidos en la fertilidad. Sin embargo, se sabe poco sobre su impacto en los gametos masculinos y femeninos. Nuestro estudio tuvo como objetivo investigar las relaciones entre los niveles de lípidos en plasma sanguíneo, líquido folicular y plasma seminal con la respuesta ovárica y concentración espermática, independientemente de la edad y el índice de masa corporal (IMC).

Six putative GTP binding proteins were detected by ultraviolet light in the presence of [α-32P]GTP during the developmental cycle of Streptomyces coelicolor. Four out of six were true GTP binding proteins. Immunological reactions carried out with antiserum which recognizes the α-common subunit of G regulatory proteins identified two bands of 67 kDa and 30 kDa. Studies with [γ-32P]GTP showed significant changes in protein phosphorylation during the cell cycle. The results show that at least three different systems of GTP protein interaction are present in S. coelicolor.