Recent Advances in DNA & Gene Sequences (Discontinued) - Volume 8, Issue 1, 2014
Volume 8, Issue 1, 2014
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Methods and Compositions for Amplification and Detection of microRNAs (miRNAs) and Noncoding RNAs (ncRNAs) Using the Signature Sequence Amplification Method (SSAM)
Authors: Stephen D. Ginsberg and Shaoli CheThe signature sequence amplification method (SSAM) described herein is an approach for amplifying noncoding RNA (ncRNA), microRNA (miRNA), and small polynucleotide sequences. A key point of the SSAM technology is the generation of signature sequences. The signature sequences include target sequences (miRNA, ncRNA, and/or any small polynucleotide sequence) flanked by two DNA fragments. Target sequences can be amplified through DNA synthesis, RNA synthesis, or the combination of DNA and RNA synthesis. The amplification of signature sequences provides an efficient and reproducible mechanism to determine the presence or absence of the target miRNAs/ncRNAs, to analyze the quantities of the miRNAs in biological samples, and for miRNA/ncRNA profiling.
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Conserved and Varied Dinucleotide Sequences in the Genomes of Three Aspergillus Species
More LessBoth guanine-cytosine content and nucleosome occupancy are higher in exons than in introns. In this study, the association between the frequencies of the dinucleotide sequences and the nucleosome occupancy of the exons and introns of the genes of Aspergillus fumigatus, Aspergillus nidulans, and Aspergillus oryzae was studied. The frequency of the dinucleotide sequences AA (TT), AT, and TA in the introns was more than that in the exons. In addition, the frequency of these sequences in the regions of the exons with low nucleosome occupancy was more than that in the regions with high nucleosome occupancy. On the other hand, the frequency of CC (GG), CG, and GC in the exons and in the regions of the exons with high nucleosome occupancy was higher than that in the introns and in the regions of low nucleosome occupancy, respectively. Interestingly, the frequency of the dinucleotide sequence AC (GT) was similar in the exons and introns of A. fumigatus. In A. nidulans, the frequency of AG (CT) and CA (TG) was similar in the regions of the exons with high and low nucleosome occupancy. In A. oryzae, the frequency of AG (CT) and GA (TC) was similar in the regions of the exons with high and low nucleosome occupancy. This study showed the conserved and varied dinucleotide sequences among the three species of Aspergillus.
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Discovery of Novel Antibiotic Resistance Genes Through Metagenomics
Authors: Marcos Lopez-Perez and Salvador MireteAntibiotic resistance (AR) represents a challenge for the treatment of infectious diseases. Traditionally, antibiotic resistance determinants have been retrieved from culturable bacteria which represent a minor fraction of the total microbial diversity found in natural environments such as soils. In this review, we summarize recent advances in the study of antibiotic resistance using two main culture-independent approaches: sequence-based metagenomics and functional metagenomics.
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Analysis of Simple Sequence Repeats in Mammalian Cell Cycle Genes
Authors: Seema Trivedi, Christopher Wills and David MetzgarSimple sequence repeats (SSRs), or microsatellites are hyper-mutable and can lead to disorders. Here we explore SSR distribution in cell cycle-associated genes [grouped into: checkpoint; regulation; replication, repair, and recombination (RRR); and transition] in humans and orthologues of eight mammals. Among the gene groups studied, transition genes have the highest SSR density. Trinucleotide repeats are not abundant and introns have higher repeat density than exons. Many repeats in human genes are conserved; however, CG motifs are conserved only in regulation genes. SSR variability in cell cycle genes represents a genetic Achilles’ heel, yet SSRs are common in all groups of genes. This tolerance many be due to i) positions in introns where they do not disrupt gene function, ii) essential roles in regulation, iii) specific value of adaptability, and/or iv) lack of negative selection pressure. Present study may be useful for further exploration of their medical relevance and potential functionality.
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Risk and Protective Effects of the Complexin-2 Gene and Gene-Environment Interactions in Schizophrenia
Authors: Roksana Zakharyan, Sofi Atshemyan and Anna BoyajyanSchizophrenia (SCZ) is a multifactorial chronic and disabling mental disease. The specific genetic variants contributing to disease complex phenotype are largely unknown. Growing amount of evidence suggested that aberrant synaptic connectivity contributes to SCZ pathogenesis. From this point of view, complexin-2, a presynaptic regulatory protein, represents here a special interest, since it has been recently shown that genetic variants of the CPLX2 gene may affect current cognitive performance in patients with SCZ. A specific objective of this study was to evaluate if tagging single nucleotide polymorphisms (rs3892909, rs1366116) of gene encoding complexin-2 protein (CPLX2) linked to SCZ and to examine their relationships with complexin-2 blood levels. DNA samples of 260 patients with SCZ and 260 sex- and agematched healthy controls were genotyped for the selected polymorphisms by application of polymerase chain reaction with sequence-specific primers, and concentration of complexin-2 in the blood plasma was determined using the enzymelinked immunosorbent assay. All study subjects were unrelated Armenians. According to the obtained results, in the patients group both the frequency distribution and carriage rate of the CPLX2 rs1366116*T minor allele were higher than in controls. On the contrary, the frequency distribution and carriage rate of the CPLX2 rs3892909*T minor allele in control group were higher than in patients. This data suggested that the presence of the CPLX2 rs1366116*T allele increases susceptibility to SCZ, whereas the rs3892909*T allele of the CPLX2 decreases the risk of SCZ. Furthermore, we found that CPLX2 rs1366116*T heterozygosity is associated with earlier disease onset. No difference between complexin-2 plasma levels in patients and controls and no significant interaction between complexin-2 plasma levels and CPLX2 genotypes in both groups were observed. In summary, we concluded that the CPLX2 rs1366116*T variant represents a risk factor of SCZ, and that, at the same time, the CPLX2 rs3892909*T variant is protective against SCZ.
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Effect of DNA Microenvironment on Photosensitized Reaction of Watersoluble Cationic Porphyrins
Authors: Kazutaka Hirakawa and Shuku NakajimaEndogenous and exogenous photosensitizers induce DNA damage, leading to carcinogenesis. Further, DNA is an important target biomacromolecule of photodynamic therapy (PDT) for cancer. Since the solar-induced DNA damage and PDT reaction occur in a complex biological environment, the interaction between biomolecule and photosensitizer is important. In this study, we examined the effect of a DNA microenvironment on the photosensitized reaction by watersoluble porphyrin derivatives, tetrakis(N-methyl-p-pyridinio)porphyrin (H2TMPyP) and its zinc complex (ZnTMPyP). In the presence of a sufficient concentration of DNA, H2TMPyP mainly intercalates to calf thymus DNA, whereas ZnTMPyP binds into a DNA groove. An electrostatic interaction with DNA raises the redox potential of the binding porphyrins. This effect suppressed the photoinduced electron transfer from an electron donor to the DNA-binding porphyrins, whereas the electron transfer from the porphyrins to the electron acceptor was enhanced. In the case of hydrophobic electron acceptors, static complexes with porphyrins were formed, making rapid electron transfer possible. Since the interaction with DNA cleaved this complex, the electron transfer rate was decreased in the presence of DNA. The microenvironment of a DNA strand may assist or inhibit its oxidative damage by photoinduced electron transfer through an electrostatic interaction with binding photosensitizers and the steric effect.
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Recent Patents on Microbial Proteases for the Dairy Industry
This paper reviews the general characteristics of exo and endopeptidases of microbial origin currently used in the milk industry. It also includes recent patents developed either to potentiate the enzymatic activity or to improve the resulting milk derivatives. The main application of these proteases is in the cheese-making industry. Although this industry preferentially uses animal rennets, and in particular genetically engineered chymosins, it also utilizes milk coagulants of microbial origin. Enzymes derived from Rhizomucor miehei, Rhizomucor pusillus and Cryphonectria parasitica are currently used to replace the conventional milk-clotting enzymes. In addition, the dairy industry uses microbial endo and exoproteases for relatively new applications, such as debittering and flavor generation in cheese, accelerated cheese ripening, manufacture of protein hydrolysates with improved functional properties, and production of enzyme-modified cheeses. Lactic acid bacteria play an essential role in these processes, hence these bacteria and the proteases they produce are currently being investigated by the dairy industry and are the subject of many of their patent applications.
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