There has been great interest in the prospects of using single-nucleotide polymorphisms (SNPs) in the search for complex disease genes, and several initiatives devoted to the identification and mapping of SNPs throughout the human genome are currently underway. However, actual data investigating the use of SNPs for identification of complex disease genes are scarce. To begin to look at issues surrounding the use of SNPs in complex disease studies, we have initiated a collaborative SNP mapping study around APOE, the well-established susceptibility gene for late-onset Alzheimer disease (AD). Sixty SNPs in a 1.5-Mb region surrounding APOE were genotyped in samples of unrelated cases of AD, in controls, and in families with AD. Standard tests were conducted to look for association of SNP alleles with AD, in cases and controls. We also used family-based association analyses, including recently developed methods to look for haplotype association. Evidence of association (P=.05) was identified for 7 of 13 SNPs, including the APOE-4 polymorphism, spanning 40 kb on either side of APOE. As expected, very strong evidence for association with AD was seen for the APOE-4 polymorphism, as well as for two other SNPs that lie <16 kb from APOE. Haplotype analysis using family data increased significance over that seen in single-locus tests for some of the markers, and, for these data, improved localization of the gene. Our results demonstrate that associations can be detected at SNPs near a complex disease gene. We found that a high density of markers will be necessary in order to have a good chance of including SNPs with detectable levels of allelic association with the disease mutation, and statistical analysis based on haplotypes can provide additional information with respect to tests of significance and fine localization of complex disease genes.
Glyphosate is a non-selective broad-spectrum herbicide that inhibits 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). This is a key enzyme in the aromatic amino acid biosynthesis pathway of microorganisms and plants. The manipulation of bacterial EPSPS gene in order to reduce its affinity for glyphosate, followed by its transfer to plants is one of the most effective approaches for the production of glyphosate-tolerant plants. In this study, we chose to focus on amino acid residues glycine96 and alanine183 of the E. coli (k12) EPSPS enzyme. These two amino acids are important residues for glyphosate binding. We used site directed mutagenesis (SDM) to induce point mutations in the E. coli EPSPS gene, in order to convert glycine96 to alanine (Gly96Ala) and alanine183 to threonine (Ala183Thr). After confirming the mutation by sequencing, the altered EPSPS gene was transferred to rapeseed (Brassica napus L.) via Agrobacterium-mediated transformation. The transformed explants were screened in shoot induction medium containing 25 mg L-1 kanamycin. Glyphosate tolerance was assayed in putative transgenic plants. Statistical analysis of data showed that there was a significant difference between the transgenic and control plants. It was observed that transgenic plants were resistant to glyphosate at a concentration of 10 mM whereas the non-transformed control plants were unable to survive 1 mM glyphosate. The presence and copy numbers of the transgene were confirmed with PCR and Southern blotting analysis, respectively.
Due to the prominent role of the liver in the body and detoxification, its functionality can be affected in an irreversible manner by diseases. This phenomenon renders the liver to stop working, leading to morbidity and mortality. Therefore, liver transplantation is the only way to tackle this issue. In order to compensate for the lack of adequate healthy liver tissue for transplantation, therapeutic approaches such as hepatocyte transplantation have been proposed as an alternative. Recognizing the fact that mesenchymal stem cells are adult stem cells with the capacity to differentiate into several cell types, different methods have been invented to produce hepatocyte-like cells from mesenchymal stem cells. They can be divided into three main categories, such as addition of cytokines and growth factors, genetic modifications, and adjustment of microenvironment as well as physical parameters. In this review, we attempted to introduce diverse efficient methods for differentiating mesenchymal stem cells and their capability for transformation into hepatocyte-like cells.
The results of this study showed the intracellular occurrence of H. pylori in yeast. This endosymbiotic relationship might explain the persistence of H. pylori in the oral cavity, the consequence of which could be reinoculation of the stomach by the bacterium and spread of infection among human populations.
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