Cloning, sequencing and analyzing of the heavy chain V region genes of human polyreactive antibodies

The heavy chain variable region genes of 5 human polyreactive mAbs generated in our laboratory have been cloned and sequenced using polymerase chain reaction (PCR) technique. We found that 2 and 3 mAbs utilized genes of the VHIV and VHIII families, respectively. The former 2 VH segments were in germline configuration. A common VH segment, with the best similarity of 90.1 % to the published VHIII germline genes, was utilized by 2 different rearranged genes encoding the V regions of other 3 mAbs. This strongly suggests that the common VH segment is a unmutated copy of an unidentified germline VHIII gene. All these polyreactive mAbs displayed a large NDN region (VH-D-JH junction). The entire H chain V regions of these polyreactive mAbs are unusually basic. The analysis of the charge properties of these mAbs as well as those of other poly- and mono- reactive mAbs from literatures prompts us to propose that the charged amino acids with a particular distribution along the H chain V region,especially the binding sites (CDRs), may be an important structural feature involved in antibody polyreactivity.

Cloning and sequencing of 23 kDa membrane protein of Chinese Schistosoma japonicum

Abstract Objective To develop the vaccine of Chinese Schistosomiasis japonicum, we try to prepare the 23kDa membrane protein of Schistosoma japonicum Chinese strain with the gene cloning techniques. Methods A pair of primers P1 and P2 was systhesized according to the DNA sequence of the 23kDa membrane protein of Schistosoma mansoni, a BamH1 site was added at 5' end of the primer P1 and the Sall site was added at the 5' end of the primer P2. The gene DNA fragment of the 23kDa membrane protein (SjC23) of Schistosoma japonicum was amplified from the cDNA library of Schistosoma japonica by PCR, the purified target DNA fragment was inserted into the vector pUC18/19 to form the recombinant, and sequenced in Livopool University, UK and Fudan Universtiy, China respectively. The DNA sequence was analyzed with Dnasis software, and the amino sequence was deduced with the SWISS PORT software. Results The size of DNA of 23kDa membrane protein of Schistosoma japonica Chinese strain (SjC23) was 657bp, and it was the same size as that of Sm23 and Sj23 Philippine strain. The DNA sequence of Sj23 Chinese strain (SjC23) was 100% in homology with the SjC23 Philippine strain, and 79.5% in homology with Sm23. The deduced amino acid sequence of SjC23 was 84% in homology with the Sm23, and 100% in homology with Philippine strain. There were two hydrophilic domains in the SjC23, one was located at the N terminal (amino acid 36-56), and another was at the C terminal (amino acid 108-183). Conclusions The gene of the 23kDa membrane protein of Schistosoma japonica Chinese strain has been cloned, and this work has laid the foundation for the development of the vaccine of Schistosoma japonica Chinese strain.

Isolation and sequence analysis of a Dof protein gene(PtDof1) in Populus

Both cDNA and DNA clones of PtDof1 （GenBank Accession No. FJ402844 and FJ402845） were isolated from plants grown in tissue culture ofPopulus tornentosa. The DNA sequence is 1597 bp including two exons and one intron. The cDNA is 969 bp in length with a 765 bp open reading frame which is capable of encoding 255 amino acids. The deduced amino acids sequence of the PtDofl protein shares 65%, 56% and 55% identity with Vitis vinifera （CAO48618）, Nicotiana tabacum （CAA08755） and Glycine max （ABI 16022） Dof protein by blast analysis in GenBank. Phylogenic analysis suggests PtDof1 gene could belong to the Dofgene family. PtDofl protein contains an unusual conserved single zinc finger with the pattern of C-X2-C-X21-C-X2-C, which may play a functional role in tissue-specific expression and possibly the auxin response of endogenous plant genes.

Cloning and sequence analysis of chitin synthase gene fragments of Demodex mites

To our knowledge,few reports on Demodex studied at the molecular level are available at present.In this study our group,for the first time,cloned,sequenced and analyzed the chitin synthase(CHS) gene fragments of Demodex folliculorum,Demodex brevis,and Demodex canis(three isolates from each species) from Xi'an China,by designing specific primers based on the only partial sequence of the CHS gene of D.canis from Japan,retrieved from GenBank.Results show that amplification was successful only in three D.canis isolates and one D.brevis isolate out of the nine Demodex isolates.The obtained fragments were sequenced to be 339 bp for D.canis and 338 bp for D.brevis.The CHS gene sequence similarities between the three Xi'an D.canis isolates and one Japanese D.canis isolate ranged from 99.7% to 100.0%,and those between four D.canis isolates and one D.brevis isolate were 99.1%-99.4%.Phylogenetic trees based on maximum parsimony(MP) and maximum likelihood(ML) methods shared the same clusters,according with the traditional classification.Two open reading frames(ORFs) were identified in each CHS gene sequenced,and their corresponding amino acid sequences were located at the catalytic domain.The relatively conserved sequences could be deduced to be a CHS class A gene,which is associated with chitin synthesis in the integument of Demodex mites.