Nitrogen cycle: what governs nitrogen loss from forest soils?

Nitrogen is lost as dissolved organic compounds in stream waters from unpolluted South American forests, but it is lost mainly as inorganic nitrate in streams flowing from North American forests that suffer nitrogen deposition from the atmosphere. From this it has been inferred that the standard thinking about how nature deals with nitrogen in soils and waters needs to be re-evaluated and that the conventional wisdom of how nitrogen is absorbed and released by plants must be wrong. We disagree, however, on the grounds that there are other, more likely interpretations of the new results.     

Restriction enzyme-generated siRNA (REGS) vectors and libraries

Small interfering RNA (siRNA) technology facilitates the study of loss of gene function in mammalian cells and animal models, but generating multiple siRNA vectors using oligonucleotides is slow, inefficient and costly. Here we describe a new, enzyme-mediated method for generating numerous functional siRNA constructs from any gene of interest or pool of genes. To test our restriction enzyme-generated siRNA (REGS) system, we silenced a transgene and two endogenous genes and obtained the predicted phenotypes. REGS generated on average 34 unique siRNAs per kilobase of sequence. REGS enabled us to create enzymatically a complex siRNA library (>4 x 10(5) clones) from double-stranded cDNA encompassing known and unknown genes with 96% of the clones containing inserts of the appropriate size.     

Étude biochimique des poissons: 1. Variations semestrielles de la teneur en eau et en protéines du tissu musculaire de la truite Arc-en-ciel (Salmo gairdnerii Rich)

Summary The authors have noted, during the reproductive cycle of the Rainbow trout (Salmo gairdnerii Rich), important variations concerning water and total proteins content. This study shows a great correlation between the biological process and biochemical variations.