High Lineage Diversity Research Articles

Archaeal and bacterial community composition of sediment and plankton from a suboxic freshwater pond

We studied the composition of archaeal and bacterial communities present in the sediment and plankton of a shallow suboxic-to-anoxic freshwater pond with high organic matter input, as an example of a kind of inland freshwater system widely distributed in forests of temperate regions. Molecular surveys based on small subunit rRNA genes showed a remarkably high diversity of lineages within the Bacteria, with a total of 18 phyla or candidate divisions being detected, in addition to a few highly divergent phylotypes of unknown affiliation. We identified members of the five subdivisions of the Proteobacteria, as well as Acidobacteria, Verrucomicrobia, Planctomycetes, Bacteroidetes, Chlorobi, Actinobacteria, Firmicutes, Chloroflexi, Gemmatimonadetes, Spirochaetes, Fibrobacteres and the candidate divisions OD1, OP11, TM6, WS1, WS6 and Termite Group 1 (”Endobacteria”). Candidate division OD1 and beta-Proteobacteria were dominant in the environmental libraries of plankton and sediment, respectively. Archaea were also very diverse, but only members of the Euryarchaeota, including Methanosarcinales, Methanomicrobiales and some divergent lineages, were identified. The application of various species richness estimators confirmed the highly diverse nature of both plankton and sediment samples. The pond is a microbial-based complex ecosystem mainly fueled by the degradation of allochthonous organic matter that maintains tightly coupled carbon and sulfur cycles.

Predictive Performance of the Modification of Diet in Renal Disease and Cockcroft-Gault Equations for Estimating Renal Function

Recent recommendations emphasize the need to assess kidney function using creatinine-based predictive equations to optimize the care of patients with chronic kidney disease. The most widely used equations are the Cockcroft-Gault (CG) and the simplified Modification of Diet in Renal Disease (MDRD) formulas. However, they still need to be validated in large samples of subjects, including large non-U.S. cohorts. Renal clearance of (51)Cr-EDTA was compared with GFR estimated using either the CG equation or the MDRD formula in a cohort of 2095 adult Europeans (863 female and 1232 male; median age, 53.2 yr; median measured GFR, 59.8 ml/min per 1.73 m(2)). When the entire study population was considered, the CG and MDRD equations showed very limited bias. They overestimated measured GFR by 1.94 ml/min per 1.73 m(2) and underestimated it by 0.99 ml/min per 1.73 m(2), respectively. However, analysis of subgroups defined by age, gender, body mass index, and GFR level showed that the biases of the two formulas could be much larger in selected populations. Furthermore, analysis of the SD of the mean difference between estimated and measured GFR showed that both formulas lacked precision; the CG formula was less precise than the MDRD one in most cases. In the whole study population, the SD was 15.1 and 13.5 ml/min per 1.73 m(2) for the CG and MDRD formulas, respectively. Finally, 29.2 and 32.4% of subjects were misclassified when the CG and MDRD formulas were used to categorize subjects according to the Kidney Disease Outcomes Quality Initiative chronic kidney disease classification, respectively.