Xu Huibi

A β-d-glucan from the sclerotia of Pleurotus tuber-regium (Fr.) Sing

An alkali-soluble polysaccharide (Hunai polysaccharide, 1) from the fruit body of Pleurotus tuber-regium (Fr.) Sing was shown to be homogeneous by gel permeation chromatography and its molecular weight was approximately 4.3 x 10(5). Complete acid hydrolysis, periodate oxidation, Smith degradation, methylation, FT-IR and 13C NMR analysis, complex formation with Congo Red, indicated that 1 has a beta-(1 --> 3)-linked D-glucopyranosyl backbone with a single beta-D-glucopyranosyl group at O-6 of every third glucose residue.

Study of immune function of cancer patients influenced by supplemental zinc or selenium-zinc combination

Since hair Zn and serum Zn are usually decreased in cancer patients, and Zn deficiency, may reduce the function of T-cells, granulocytes, and Nk cells, we observed in cancer patients the influences of the Zinc or Selenium-Zinc on DNCB skin delayed hypersensitivity mediated by T cell, and the effects of Zinc on oxidative metabolic function of neutrophils and level of serum interferon that potentiate NK cell activity. The results showed that DNCB skin reaction was strengthened, the oxidative metabolic function of neutrophils and serum interferon level were increased by the drugs. It is reasonable to expect that Zinc or Selenium-Zinc is instrumental in restoring failing immunocompetence of cancer patient.

Prevention of axial elongation in myopia by the trace element zinc

The effect of the trace element zinc on the change in the axial length and diopters and the variations of activities of superoxide dismutase (SOD) and nitric oxide synthase (NOS), and the content of NO in the retino pigmental epithelium choroid homogenate of the myopic eyes in form-sense-deprived chicks were studied. The results show that zinc can inhibit the elongation of axis oculi and increase the diopters in myopia. Meanwhile, the activities of SOD and NOS and the content of NO are significantly increased compared with the model group, indicating that zinc can be used to prevent and treat myopia to a certain extent.

In silico identification of silkworm selenoproteomes

Selenium (Se) is an essential trace element in vivo. Its biological function is mainly exerted through selenoproteins. Selenocysteine (Sec), the active site of selenoproteins, is incorporated into the protein at an in-frame TGA codon under the guidance of Sec insertion sequence (SECIS) element in the 3′-untranslated region (UTR) of the gene. In this work, a method was developed and a series of programs were edited by PERL language to in silico identify selenoproteomes from the genome of domesticated silkworm (Bombyx mori). Out of 18510 annotated genes, 6348 was terminated with TGA codons, 249 containing both in-frame TGAs and SECIS elements in the 3′-UTRs. Alignments of those selenoprotein candidates with their cysteine (Cys)-containing homologs revealed that 52 genes had TGA/Cys pairs and similar flanking regions around the in-frame TGAs. Restricted by the pattems of SECIS elements only 5 genes were screened out to fully meet the requirements for selenoproteins. Among them glutathione S-transferase (GST) has been reported as a microbial selenoprotein, the other four are novel selenoproteins annotated as CG6024, CG5195, ATP-binding cassette transporter subfamily A (ABCA), and nuclear VCP-like protein. Derived from the general properties of GST, ABCA and VCP, silkworm selenoproteins may play important roles in redox regulation, Se storage and transportation, as well as cell apoptosis.

New Selenoproteins Identified in silico from the Genome of Anopheles gambiae

Selenoprotein is biosynthesized by the incorporation of selenocysteine into proteins, where the TGA codon in the open reading frame does not act as a stop signal but is translated into selenocysteine. The dual functions of TGA result in mis-annotation or lack of selenoproteins in the sequenced genomes of many species. Available computational tools fail to correctly predict selenoproteins. Thus, we developed a new method to identify selenoproteins from the genome of Anopheles gambiae computationally. Based on released genomic information, several programs were edited with PERL language to identify selenocysteine insertion sequence (SECIS) element, the coding potential of TGA codons, and cysteine-containing homologs of selenoprotein genes. Our results showed that 11365 genes were terminated with TGA codons, 918 of which contained SECIS elements. Similarity search revealed that 58 genes contained Sec/Cys pairs and similar flanking regions around in-frame TGA codons. Finally, 7 genes were found to fully meet requirements for selenoproteins, although they have not been annotated as selenoproteins in NCBI databases. Deduced from their basic properties, the newly found selenoproteins in the genome of Anopheles gambiae are possibly related to in vivo oxidation tolerance and protein regulation in order to interfere with anopheles’ vectorial capacity of Plasmodium. This study may also provide theoretical bases for the prevention of malaria from anopheles transmission.

Research progress of selenoproteins in the endoplasmic reticulum

Selenium is an essential micronutrient in mammals. The major biological form of this micronutrient is the amino acid selenocysteine, which is presented in the active sites of selenoproteins. 7 of 25 mammalian selenoproteins have been identified as residents of the endoplasmic reticulum (ER), including type 2 iodothyronine deiodinase (DI2), the 15-kDa selenoprotein, and selenoproteins K, M, N, S, and T. Most of these proteins are poorly characterized except for DI2. However, recent studies implicate some of them play the role in redox regulation, quality control of protein folding in the ER, retrotranslocation of misfolded proteins from the ER to the cytosol, and regulation of calcium homeostasis, ER stress and inflammation. This review summarizes recent findings about the structure, function, and physiological and pathological roles of the ER-resident selenoproteins. In addition, some future works on these proteins are suggested.