Translation Levels Control Multi-Spanning Membrane Protein Expression

Attempts to express eukaryotic multi-spanning membrane proteins at high-levels have been generally unsuccessful. In order to investigate the cause of this limitation and gain insight into the rate limiting processes involved, we have analyzed the effect of translation levels on the expression of several human membrane proteins in Escherichia coli (E. coli). These results demonstrate that excessive translation initiation rates of membrane proteins cause a block in protein synthesis and ultimately prevent the high-level accumulation of these proteins. Moderate translation rates allow coupling of peptide synthesis and membrane targeting, resulting in a significant increase in protein expression and accumulation over time. The current study evaluates four membrane proteins, CD20 (4-transmembrane (TM) helixes), the G-protein coupled receptors (GPCRs, 7-TMs) RA1c and EG-VEGFR1, and Patched 1 (12-TMs), and demonstrates the critical role of translation initiation rates in the targeting, insertion and folding of integral membrane proteins in the E. coli membrane

Diurnally Entrained Anticipatory Behavior in Archaea

By sensing changes in one or few environmental factors biological systems can anticipate future changes in multiple factors over a wide range of time scales (daily to seasonal). This anticipatory behavior is important to the fitness of diverse species, and in context of the diurnal cycle it is overall typical of eukaryotes and some photoautotrophic bacteria but is yet to be observed in archaea. Here, we report the first observation of light-dark (LD)-entrained diurnal oscillatory transcription in up to 12% of all genes of a halophilic archaeon Halobacterium salinarum NRC-1. Significantly, the diurnally entrained transcription was observed under constant darkness after removal of the LD stimulus (free-running rhythms). The memory of diurnal entrainment was also associated with the synchronization of oxic and anoxic physiologies to the LD cycle. Our results suggest that under nutrient limited conditions halophilic archaea take advantage of the causal influence of sunlight (via temperature) on O2 diffusivity in a closed hypersaline environment to streamline their physiology and operate oxically during nighttime and anoxically during daytime

Gestation at birth, mode of birth, infant feeding and childhood hospitalization with infection

INTRODUCTION: Infections are a leading cause of mortality and morbidity in preschool children. We aimed to assess the impact of the co-occurrence of cesarean section, early birth and formula feeding on hospitalization with infection in early childhood. MATERIAL AND METHODS: Population-based retrospective record-linkage cohort study of 488 603 singleton livebirths ≥32 weeks' gestational age in New South Wales, Australia, 2007-2012. Multivariable Cox-regression was used to estimate independent and combined adjusted associations of gestational age, mode of birth (vaginal or cesarean section by labor onset) and formula feeding with time to first and repeat hospitalization with infection for children less than five years of age. RESULTS: In all, 95 346 (19.5%) children were hospitalized with infection, and of these 24.8% (23 615) more than once. Median age at first and repeat hospitalization was 1.1 and 1.7 years, respectively. Earlier gestation, modes of birth other than spontaneous vaginal, and formula feeding were independently associated with an increased risk of first and repeat hospitalization with infection. At 32-36 weeks' gestation, co-occurrence of perinatal factors (cf. spontaneous vaginal birth at 39+ weeks without formula feeding) was associated with a 2-fold and 1.5-fold increased risk of first and repeat hospitalization, respectively. For births at 37-38 weeks, the increased risk was 1.5-fold and 1.25-fold for first and repeat hospitalization, respectively. CONCLUSIONS: Cesarean section, labor induction, birth at <39 weeks and formula feeding increase the risk of infection-related hospitalization in childhood, which increases further when these factors co-occur. Reducing early planned birth and supporting breastfeeding are potentially cost-effective approaches to reducing the risk of hospitalization

Bilateral phaeochromocytomas in von Hippel-Lindau disease: diagnosis by adrenal vein sampling and catecholamine assay.

Three unrelated patients with von Hippel-Lindau disease had phaeochromocytomas diagnosed as a result of screening in their third decade. All had raised 24-h urinary noradrenaline levels and obvious unilateral adrenal tumours on ultrasound scanning and computed tomography. The contralateral adrenal appeared either normal or equivocally abnormal using the same imaging techniques. Radiolabelled meta-iodo-benzylguanidine uptake and enhanced T2-weighted magnetic resonance signals confirmed the ipsilateral lesion, but showed no abnormality in the contralateral adrenal. Nevertheless, venous sampling demonstrated abnormally elevated noradrenaline:adrenaline ratios (normal &lt; 1) in blood draining both adrenals in all three patients. All underwent bilateral adrenalectomy: histological examination confirmed bilateral phaeochromocytomas in all three patients, with the smaller adrenal showing tumours between 3 and 11 mm in diameter. A fourth patient with von Hippel-Lindau disease was also evaluated because of a left 'suprarenal' mass discovered by ultrasound scanning. Urinary and plasma catecholamines were normal. Computed tomography showed a normal right adrenal, with a left para-aortic mass lying superior to the left adrenal. Magnetic resonance scanning showed an enhanced T2 signal from the mass, which also showed positive uptake with radiolabelled mIBG. At operation, a non-secretory left para-aortic paraganglioma was found. Venous sampling suggested that the left adrenal was normal, and this was confirmed on histology. Venous sampling for catecholamine assays is effective in locating small bilateral phaeochromocytomas and defining a normal adrenal gland, and can be useful in preventing unnecessary or repeat operations in patients with non Hippel-Lindau disease