An autosomal genomic scan for loci linked to type 2 diabetes in northern Han Chinese

We report the results of a genome-wide scan conducted in 219 individuals from 34 large multiplex nuclear pedigrees from the northern Han Chinese population at an average resolution of about 10 cM. Nonparametric two-point and multipoint linkage analyses were performed to detect evidence of linkage with type 2 diabetes in this study. On chromosome 1 four regions showed evidence of linkage with type 2 diabetes in northern Han Chinese. Of these regions a marker D1S193 (73 cM) showed evidence of linkage (two-point nonparametric linkage 2.409), and another region (around 190 cM) was a replication of several other studies performed in different ethnic populations. Evidences of linkage have been confirmed by typing additional markers (average distance 1-5 cM) flanking these two positive regions on chromosome 1. We also found indication of linkage with type 2 diabetes on chromosomes 2, 10, 12, 18, 20, and 22 by two-point linkage analyses.

Inhibition of LZIP-mediated transcription through direct interaction with a novel host cell factor-like protein

Host cell factor 1 (HCF-1) is a cellular transcriptional coactivator which coordinates the assembly of enhancer complex through direct interactions with viral and cellular trans-activators such as VP16, Oct-1, LZIP, and GA-binding protein. These interactions are mediated by the beta-propeller domain comprising the first 380 residues of HCF-1 with six kelch repeats. Here we describe the identification and characterization of a novel HCF-like kelch repeat protein, designated HCLP-1. HCLP-1 is a ubiquitously expressed nuclear protein which is composed almost entirely of a six-bladed beta-propeller. HCLP-1 selectively interacts with LZIP but not with VP16. The physical interaction between HCLP-1 and LZIP leads to the repression of the LZIP-dependent transcription. The HCLP-1-binding domain of LZIP maps to residues 109-315, which contain the bZIP DNA-binding motif. Electrophoretic mobility shift assay demonstrates that HCLP-1 indeed interferes with the binding of LZIP to its DNA target. Thus, HCLP-1 serves a transcriptional co-repressor function mediated through its inhibitory interaction with the LZIP transcription factor. Our findings suggest a new mechanism for transcriptional regulation by HCF-like proteins.

The apparent specificity of NotI (5'-GCGGCCGC-3') is enhanced by M.FnuDII or M.BepI methyltransferases (5'-mCGCG-3'): cutting bacterial chromosomes into a few large pieces

The restriction endonuclease (ENase) NotI is blocked by methylation within its recognition sequence at 5'-GCGGCmCGC-3'. This sensitivity to methylation can be used to enhance the specificity of NotI in vivo and in vitro. Modification by M.FnuDII or M.BepI methyltransferases (MTase) (5'-mCGCG-3') will block NotI (5'-GCGGCCGC-3') cleavage at overlapping MTase/ENase sites 5'-CGCGGCCGC-3' (equivalent to 5'-GCGGCCGCG-3'), and increase the apparent cleavage specificity of NotI about twofold. This 'cross-protection' procedure reduces the number of NotI fragments in the genomes of Escherichia coli and Bacillus subtilis, as resolved by pulsed field electrophoresis. Application of this method to large DNAs in vitro requires the preparation of highly purified DNA MTases.

Cloning and characterization of an abundant Plasmodium knowlesi antigen which cross reacts with Gambian sera

A 110 kDa Plasmodium knowlesi antigen, termed PK110, has been identified on the basis of messenger RNA abundance in late schizonts. Most Plasmodium genes previously cloned have been identified by immune sera, which have selected immunodominant antigens composed of repeating epitopes. Although PK110 was not selected by immune sera, it also contains amino acid repeats, indicating that this structure may be a common feature of malarial proteins. Determination of 296 codons in the PK110 gene revealed the presence of thirteen tandem repeats of twelve amino acids whose consensus sequence is E E T Q K T V E P E Q T. A termination codon interrupts the fourteenth repeat, indicating that these repeats are at the C-terminus of the protein. Indirect immunofluorescence experiments with sera raised against the lambda gt11 fusion protein indicate that PK110 is present in intra-erythrocytic late schizonts. Cloned PK110 is recognized by Gambian sera, and shares epitopes with Plasmodium ovale. PK110 does not cross react immunologically or by DNA hybridization with Plasmodium falciparum.

Two unique restriction endonucleases from Neisseria lactamica

Two new site-specific endonucleases, N1a III and N1a IV, have been isolated from Neisseria lactamica. N1a III recognizes the sequence, CATG, and cleaves 3' of the sequence to produce a four base 3' extension. N1a IV recognizes the sequence, GGNNCC, and cleaves between the two N's to produce blunt ended fragments.

A type II restriction endonuclease with an eight nucleotide specificity from Streptomyces fimbriatus

A new site-specific endonuclease, Sfi I, has been isolated from Streptomyces fimbriatus . This is the first report of a type II restriction endonuclease whose recognition specificity requires eight nucleotides. Sfi I cleaves the sequence, GGCCNNNN / NGGCC , symmetrically to produce a three base, 3' extension.