The β‐subunits of the Snf1 kinase in Saccharomyces cerevisiae,Gal83 and Sip2, but not Sip1, are redundant in glucose derepression and regulation of sterol biosynthesis

The conserved Snf1/AMP‐activated protein kinase family is one of the central components in the nutrient sensing and regulation of the carbon metabolism in eukaryotes. It is also involved in several other processes such as stress resistance, invasive growth and ageing. Snf1 kinase is composed of a catalytic α‐subunit Snf1, a regulatory γ‐subunit Snf4 and one of three possible β‐subunits, Sip1, Sip2 or Gal83. We used a systematic approach to study the role of the three β‐subunits by analysing all seven possible combinations of β‐subunit deletions together with the reference strain. Previous studies showed that the three β‐subunits are redundant for growth on alternative carbon sources. Here we report that the mutant strain with only SIP1 expressed (sip2Δgal83Δ) could utilize acetate, but neither ethanol nor glycerol, as alternative carbon source. We also showed that Gal83 is the most important isoform not only for the growth on non‐fermentable carbon sources, but also for regulation of ergosterol biosynthetic genes, under glucose‐limited condition. Furthermore, we found that Sip2, but not Sip1, can take over when Gal83 is deleted, but to a lesser extent. However, Sip1 may be sufficient for some other processes such as regulation of the nitrogen metabolism and meiosis.     

Sip1Ab gene from a native Bacillus thuringiensis strain QZL38 and its insecticidal activity against Colaphellus bowringi Baly

In this study, we collected 540 soil samples from northeast China and isolated the wild-type strain of Bacillus thuringiensis (Bt) by identifying and cloning 9 Bt strains that expressed the secreted insecticidal protein (Sip) gene. We selected the strain QZL38 for further study. The sip gene was identified from the Bt strain QZL38 using polymerase chain reaction (PCR). We sequenced a 1095-base pair fragment of DNA that encodes 364 amino acid residues of a 41.18?kDa pro-toxin and compared it with the registered Sip1Ab protein amino acid residue sequence. The sequence was submitted to GenBank with the accession no. KP231523, and the gene was named sip1Ab. The Sip1Ab protein expressed in Escherichia coli showed insecticidal activity against Colaphellus bowringi Baly, with an LC50 of 1.051?μg?mL^?1. To identify the active fragment of the Sip1Ab toxin, four pairs of primers with different truncation positions were designed, and the recombinant proteins were expressed in E. coli. The truncated Sip protein expressed in E. coli showed insecticidal activity against C. bowringi Baly. The insecticidal activity of the recombinant proteins against C. bowringi Baly from the Sip1Ab signal peptide after removal of 30 amino acid residues showed an LC50 of 1.078?μg?mL^?1. Sip proteins may play an important role in the prevention and control of the C. bowringi Baly.     

Genetic and physical mapping of the natural resistance-associated macrophage protein 1 (NRAMP1) in chicken

The chicken natural resistance-associated macrophage protein 1 (NRAMP1) gene has been mapped by linkage analysis by use of a reference panel to develop the chicken molecular genetic linkage map and by fluorescence in situ hybridization. The chicken homolog of the murine Nramp1 gene was mapped to a linkage group located on Chromosome (Chr) 7q13, which includes three genes (CD28, NDUSF1, and EF1B) that have previously been mapped either to mouse Chr 1 or to human Chr 2q. Physical mapping by pulsed-field gel electrophoresis revealed that NRAMP1 is tightly linked to the villin gene and that the genomic organization (gene order and presence of CpG islands) of the chromosomal region carrying NRAMP1 is well conserved between the chicken and mammalian genomes. The regions on mouse Chr 1, human Chr 2q, and chicken Chr 7q that encompass NRAMP1 represent large conserved chromosomal segments between the mammalian and avian genomes. The chromosome mapping of the chicken NRAMP1 gene is a first step in determining its possible role in differential susceptibility to salmonellosis in this species.