Diversity and dynamics of rare and of resident bacterial populations in coastal sands

Coastal sands filter and accumulate organic and inorganic materials from the terrestrial and marine environment, and thus provide a high diversity of microbial niches. Sands of temperate climate zones represent a temporally and spatially highly dynamic marine environment characterized by strong physical mixing and seasonal variation. Yet little is known about the temporal fluctuations of resident and rare members of bacterial communities in this environment. By combining community fingerprinting via pyrosequencing of ribosomal genes with the characterization of multiple environmental parameters, we disentangled the effects of seasonality, environmental heterogeneity, sediment depth and biogeochemical gradients on the fluctuations of bacterial communities of marine sands. Surprisingly, only 3–5% of all bacterial types of a given depth zone were present at all times, but 50–80% of them belonged to the most abundant types in the data set. About 60–70% of the bacterial types consisted of tag sequences occurring only once over a period of 1 year. Most members of the rare biosphere did not become abundant at any time or at any sediment depth, but varied significantly with environmental parameters associated with nutritional stress. Despite the large proportion and turnover of rare organisms, the overall community patterns were driven by deterministic relationships associated with seasonal fluctuations in key biogeochemical parameters related to primary productivity. The maintenance of major biogeochemical functions throughout the observation period suggests that the small proportion of resident bacterial types in sands perform the key biogeochemical processes, with minimal effects from the rare fraction of the communities

Why prevent, diagnose and treat congenital toxoplasmosis?

Evidence that prevention, diagnosis and treatment of toxoplasmosis is beneficial developed as follows: anti-parasitic agents abrogate Toxoplasma gondiitachyzoite growth, preventing destruction of infected, cultured, mammalian cells and cure active infections in experimental animals, including primates. They treat active infections in persons who are immune-compromised, limit destruction of retina by replicating parasites and thereby treat ocular toxoplasmosis and treat active infection in the fetus and infant. Outcomes of untreated congenital toxoplasmosis include adverse ocular and neurologic sequelae described in different countries and decades. Better outcomes are associated with treatment of infected infants throughout their first year of life. Shorter intervals between diagnosis and treatment in utero improve outcomes. A French approach for diagnosis and treatment of congenital toxoplasmosis in the fetus and infant can prevent toxoplasmosis and limit adverse sequelae. In addition, new data demonstrate that this French approach results in favorable outcomes with some early gestation infections. A standardized approach to diagnosis and treatment during gestation has not yet been applied generally in the USA. Nonetheless, a small, similar experience confirms that this French approach is feasible, safe, and results in favorable outcomes in the National Collaborative Chicago-based Congenital Toxoplasmosis Study cohort. Prompt diagnosis, prevention and treatment reduce adverse sequelae of congenital toxoplasmosis