Biosynthesis of hepatitis B virus surface antigen in Escherichia coli

Hepatitis B is a widespread viral disease. In the absence of cell cultures capable of propagating the virus (HBV) an efficient vaccine has been prepared from viral envelopes isolated from the plasma of chronic carriers. The major polypeptide of the envelope is one of molecular weight 25,000 which carries the surface antigen (HBsAg). Therefore, the biosynthesis of this polypeptide in Escherichia coli may offer an alternative procedure to produce HbsAg free from human proteins. Recently, the HBV genome has been cloned in E.coli. Determination of its primary structure allowed the localization of the gene (called gene S) coding for HBsAg and the synthesis of the core antigen in E.coli has been reported. We have constructed a derivative of bacteriophage lambda carrying a fusion between the beta-galactosidase gene (lacZ) and the HBsAg coding sequence (lambdalacHBs-1). Infection of E.coli with lambdalacHBs-1 leads to the biosynthesis of a polypeptide of molecular weitht 138,000 carrying antigenic determinants of HBV surface antigen.     

Vitamin D3 sulfoconjugate distribution and evolution in pregnant or lactating rats]

24 hrs after intravenous injection of vitamin D3 35S sulfoconjugate the radioactivity in kidney is about twice as much in pregnant Rats as in lactating Rats. It decreases from 24 to 48 hrs in pregnant but increases in lactating Rats kidneys. Hydrolysis of vitamin 3H D3 sulfate is detected in kidney and liver extracts, the ratio of free vitamin D3 on vitamin D3 sulfate is higher in pregnant than in lactating animals. Mammary glands of lactating Rats contain mainly the unchanged vitamin D3 sulfate which can be hydrolysed by new born suckling pups.     

Experimental verification of Landauer's principle linking information and thermodynamics

In 1961, Rolf Landauer argued that the erasure of information is a dissipative process. A minimal quantity of heat, proportional to the thermal energy and called the Landauer bound, is necessarily produced when a classical bit of information is deleted. A direct consequence of this logically irreversible transformation is that the entropy of the environment increases by a finite amount. Despite its fundamental importance for information theory and computer science, the erasure principle has not been verified experimentally so far, the main obstacle being the difficulty of doing single-particle experiments in the low-dissipation regime. Here we experimentally show the existence of the Landauer bound in a generic model of a one-bit memory. Using a system of a single colloidal particle trapped in a modulated double-well potential, we establish that the mean dissipated heat saturates at the Landauer bound in the limit of long erasure cycles. This result demonstrates the intimate link between information theory and thermodynamics. It further highlights the ultimate physical limit of irreversible computation.     

tRNA splicing endonuclease mutations cause pontocerebellar hypoplasia

Pontocerebellar hypoplasias (PCH) represent a group of neurodegenerative autosomal recessive disorders with prenatal onset, atrophy or hypoplasia of the cerebellum, hypoplasia of the ventral pons, microcephaly, variable neocortical atrophy and severe mental and motor impairments. In two subtypes, PCH2 and PCH4, we identified mutations in three of the four different subunits of the tRNA-splicing endonuclease complex. Our findings point to RNA processing as a new basic cellular impairment in neurological disorders.     

Effets précoces de l'hormone de croissance sur les phosphates sériques et urinaires du rat

Summary From the kinetic study of the effects of one single growth hormone (GH) injection on the phosphate metabolism, it appears that the influence of GH on the serum phosphate level is biphasic: a decrease is followed by an increase. Conversely GH leads to an early decrease of the urinary phosphate excretion.     

Performance constraints in decathletes

Physical performance by vertebrates is thought to be constrained by trade-offs between antagonistic pairs of ecologically relevant traits and between conflicting specialist and generalist phenotypes, but there is surprisingly little evidence to support this reasoning. Here we analyse the performance of world-class athletes in standardized decathlon events and find that it is subject to both types of trade-off, after correction has been made for differences between athletes in general ability across all 10 events. These trade-offs may have imposed important constraints on the evolution of physical performance in humans and other vertebrates.     

The genetics of plant metabolism

Variation for metabolite composition and content is often observed in plants. However, it is poorly understood to what extent this variation has a genetic basis. Here, we describe the genetic analysis of natural variation in the metabolite composition in Arabidopsis thaliana. Instead of focusing on specific metabolites, we have applied empirical untargeted metabolomics using liquid chromatography-time of flight mass spectrometry (LC-QTOF MS). This uncovered many qualitative and quantitative differences in metabolite accumulation between A. thaliana accessions. Only 13.4% of the mass peaks were detected in all 14 accessions analyzed. Quantitative trait locus (QTL) analysis of more than 2,000 mass peaks, detected in a recombinant inbred line (RIL) population derived from the two most divergent accessions, enabled the identification of QTLs for about 75% of the mass signals. More than one-third of the signals were not detected in either parent, indicating the large potential for modification of metabolic composition through classical breeding.