Interactions of leptospira with environmental bacteria from surface water.

Leptospires can persist for months in nutrient-poor aqueous environments prior to transmission to a mammalian host. Interactions with environmental bacteria and biofilm formation are possible mechanisms of persistence of leptospires in the environment. Bacteria isolated from rivers in the Ecuadorian rainforest were tested for their ability to support leptospiral viability. We found that co-culture with Sphingomonas spp., but not Flavobacterium spp. or Delftia spp., enabled survival of L. biflexa and L. meyeri for up to a year in distilled water. We also found that L. interrogans biofilms formed in distilled water contained viable organisms that rapidly dispersed into the planktonic phase in the presence of nutrients in serum or EMJH medium. These data inform our understanding of leptospiral survival strategies that enable long-term persistence in nutrient-poor conditions yet allow rapid mobilization when nutrients become available.

Lamina-associated polypeptide 2 (LAP2) expression in fish and amphibians.

Somatic and germinal cells of 15 fish and 33 amphibian species were examined by SDS-PAGE followed by immunoblotting to determine the expression of LAP2 (lamina-associated polypeptide 2). LAP2 expression in frogs, salamanders and fish does not vary with the mode of reproduction. In fish and frog cells, a rim-like LAP2 positive region was detected around the nucleus by indirect immunofluorescence microscopy. The cell distribution and expression patterns of LAP2 in fish, frogs and salamanders are comparable with those found in Xenopus and zebrafish. The mammalian somatic cell pattern, which may also occur in gymnophione amphibians, includes LAP2alpha, beta and gamma as major isoforms, whereas LAP2alpha does not occur in cells of fish, frogs and salamanders. In fish, LAP2gamma is the major isoform of somatic cells, suggesting that LAP2gamma may be ancestral. However, in the rainbow trout, as in frogs and salamanders, LAP2beta was the major somatic isoform. Fish and frog sperm only express low molecular weight polypeptides. In contrast, fish and frog oocytes express an oocyte-specific LAP2 isoform of high molecular weight. In the toad Bufo marinus this isoform becomes upregulated in pre-vitellogenic oocytes of 150-200 microm in diameter. The absence of LAP2alpha and the differential expression of LAP2 isoforms in somatic and germ cells, as found in fish and frogs, may be ancestral vertebrate characters. In spite of differences in developmental time, the LAP2 isoforms of somatic cells are upregulated during gastrulation, suggesting that LAP2 may be implicated in the early development of fish and frog.

Mircobial community composition in petroleum-contaminated and uncontaminated soil from Francisco de Orellana, in the northern Ecuadorian Amazon.

The microbial compositions of two soils from the northern Ecuadorian Amazon (Francisco de Orellana province), one contaminated with petroleum and the other uncontaminated, were compared. Classical culture and molecular techniques were used to analyze microbial diversity. The cultivable Bacteria from contaminated soil belonged to betaproteobacteria (16.6%), gammaproteobacteria (66.6%), and Firmicutes (16,6%), whereas in uncontaminated soil, cultivable Bacteria were identified as gammaproteobacteria (80%) and Firmicutes (20%). Analysis of the 16S rRNA showed that in the contaminated soil proteobacterial populations (alpha-, beta- and deltaproteobacteria) were more abundant than acidobacterial populations. The Shannon index (H cent ) was used to estimate diversity in the contaminated and uncontaminated soil. Diversity was higher in the uncontaminated (H cent = 2.16) than in the contaminated (H cent = 1.72) soil sample. Further studies are needed to determine whether the differences between contaminated and non-contaminated soil samples were due to spontaneous bioremediation microbial activity.