Import and processing of the precursor of the delta subunit of tobacco chloroplast ATP synthase

Surgical strategy for recurrent common bile duct stones: a 10-year experience of a single center

Recurrence of common bile duct stones (CBDS) is common after surgical stone extraction, but the causes of recurrence are not fully understood. This study aimed to report the experience of treating recurrent CBDS. A total of 106 consecutive cases of recurrent CBDS treated from January 2006 to December 2015 were included. During surgery, the choledochoscopic pass-through test was performed to assess the structure and function of the duodenal papilla. The choledochoscopic pass-through test revealed 62 patients (58.49%) with incomplete closure of the lower end of the common bile duct, and 28 (26.42%) with stenosis at the lower common bile duct. Intra-operative bile bacterial culture was positive in 98 (92.45%) patients. The rate of complete stone clearance was 99.1%. The total recurrence rate of CBDS was 3.13%. The long-term success rate of surgical treatment (excellent and good) reached 92.7% .Duodenal papilla (Oddi sphincter) dysfunction is the main cause of recurrent CBDS. Common bile duct exploration with stone extraction, hilar ductoplasty, and Roux-en-Y hepaticojejunostomy can effectively eliminate the recurrence of CBDS and reduce the incidence of post-hepaticojejunostomy complications. Thus, it is an optimal surgical procedure for recurrent CBDS.

Assembly of F1F0-ATP synthases

F1F0-ATP synthases are multimeric protein complexes and common prerequisites for their correct assembly are (i) provision of subunits in appropriate relative amounts, (ii) coordination of membrane insertion and (iii) avoidance of assembly intermediates that uncouple the proton gradient or wastefully hydrolyse ATP. Accessory factors facilitate these goals and assembly occurs in a modular fashion. Subcomplexes common to bacteria and mitochondria, but in part still elusive in chloroplasts, include a soluble F1 intermediate, a membrane-intrinsic, oligomeric c-ring, and a membrane-embedded subcomplex composed of stator subunits and subunit a. The final assembly step is thought to involve association of the preformed F1-c10-14 with the ab2 module (or the ab8-stator module in mitochondria)--mediated by binding of subunit δ in bacteria or OSCP in mitochondria, respectively. Despite the common evolutionary origin of F1F0-ATP synthases, the set of auxiliary factors required for their assembly in bacteria, mitochondria and chloroplasts shows clear signs of evolutionary divergence. This article is part of a Special Issue entitled: Chloroplast Biogenesis.

Tobacco cytochrome b5: cDNA isolation, expression analysis and in vitro protein targeting

A full-length clone encoding cytochrome b5 has been isolated from a tobacco leaf cDNA library in lambda gt11 by PCR using degenerate primers. This cDNA encodes a protein of 139 residues which exhibits a high degree of homology to other cytochrome b5s, the message for which is expressed predominantly in developing seeds and in pigmented flower tissue. In the developing tobacco seed the mRNA is abundant at very early stages (< 10 days after flowering). Southern analysis indicated that more than one gene encodes cytochrome b5 in the tobacco genome. In vitro transcription and translation studies of the cDNA indicated that the protein inserts into the ER membrane by a non-SRP-mediated pathway and that the C-terminus of the protein is required for targeting and insertion.