आण्विक जीवविज्ञान: खुली पहुंच

Siderophores are low molecular weight compounds with a strong affinity for iron. For instance, exochelin MS is a siderophore produced by M. smegmatis. In the present study, we have cloned exochelin MS biosynthesis genes of Mycobacterium smegmatis, namely, fxbA, fxbC and exiT in E. coli DH5α. These genes were amplified by PCR and cloned in plasmid vector pUC19. The clones harbouring the recombinant plasmids were isolated, purified and sequenced. The sequencing and the BLAST results using NCBI database confirmed the success of cloning fxbA, fxbC and exiT genes.

This study was carried out to determine genetic similarities in natural population of Drosophila melanogaster in savannah zone of Nigeria using microsatellite markers. A total of 184 D. melanogaster was collected using simple traps baited with banana and baker’s yeast from Northern Guinea (Kaduna), Sudan (Kano) and Sahel (Azare). A total of 40 D. melanogaster were genotyped using 7 sets of microsatellite markers, the bands in the electrophoregramme were analysed and scored using the image Lab™. The result was used to compute dendrogramme based on Nei’s genetic distance using MEGA 6. Result showed that studied population forms two (2) clusters at various degrees of similarities with Sudan savanna and Sahel Savanna forming a cluster at 0.21 then grouped with Northern Guinea Savanna to form the second (2^nd) cluster at 0.78 distances, suggesting that Northern Guinea Savanna and Sudan Savanna Drosophila melanogaster populations have a recent common ancestor.

GATA repeats are associated with sex differentiation in man, buffalo, mouse and even in plants such as papaya. Human X-chromosome region Xp22 that escapes inactivation is ten-fold enriched in GATA repeats suggesting a role in preventing heterochromatinization. The close proximity of GATA repeats to matrix-associated regions (MARs) indicates a role in chromatin organization and function. Chromosome-wise distribution and density of GATA repeats, neighboring genes and Matrix associated regions were analyzed in rice. (GATA)3 and higher repeats were distributed non-randomly with the highest frequency on chromosome 11. About 60% of the repeats were found in intergenic regions flanked by regulatory genes involved in stress response or transposable elements. The GATA associated MAR sequences in rice had at least one or more of the consensus sequence to which GATA factors bind. The genomic milieu around GATA repeats suggests that their genomic context may determine their role in chromatin organization and gene regulation.

Senescence is considered as a cellular defensive response evoked by diverse stimuli to combat tumor development and progression. An evolving body of knowledge indicates that tumor cells are capable of undergoing senescence when latent senescence pathways are reengaged. Given the apparent benefits associated with senescence induction as a therapy outcome, targeting of senescence triggering factors is being actively pursued. In this review, we briefly describe modes of senescence induction and discuss therapy approaches being undertaken for the development of prosenescence anti-cancer therapies.

Diabetes is one of the common metabolic diseases, mainly divided into two types, type 1 diabetes mellitus and type 2 diabetes mellitus. Insulin resistance is the main performance of type 2 diabetes mellitus which are relative to some gene mutation, genetics, obesity and so on. Protein-tyrosine phosphatase 1B (PTP1B) plays an important role as a negative regulator in insulin signaling pathways that are implicated in metabolic diseases such as obesity and type 2 diabetes. Many evidences from clinical and basic researches show that the high expression of PTP1B induces insulin resistance. It appears that PTP1B is an effective target for the treatment of type 2 diabetes mellitus. In this review, we briefly introduce composition of PTP1B and the role of PTP1B in insulin signaling of type 2 diabetes mellitus. We also summarized recent research progress of PTP1B inhibitors used in therapy of type 2 diabetes mellitus.

Aim and background: Vitamin D is known for its immune modulatory functions and its role in normal insulin secretion. Vitamin D acts via vitamin D receptor gene (VDR). The study was conducted to assess the relationship between Apa I and Taq I restriction site polymorphisms of vitamin D receptor gene and type1 diabetes in an Egyptian population.

Subjects and Methods: One hundred Egyptian participants (1-20 years old) of both sexes were recruited in this study. Fifty of them were type 1 diabetes patients and the other fifty were control non diabetic subjects. Apa I and Taq I variations were tested using Polymerase Chain Reaction and Restriction Fragment Length Polymorphism.

Results: Genetic analysis revealed that AA and Tt genotypes were predominant in the two study groups with higher frequency among patients group, whereas, aa and tt genotypes were predominant among controls (14% and 10%, respectively). Combined genotypes AATt, AAtt and aaTT were significantly more frequent in controls (P value of odds ratio 0.032, 0.033, 0.002, respectively). The haplotype AT was more frequent among diabetics (41%), whereas, haplotypes At and aT were more frequent in control group (39%, 29%, respectively). Linkage analysis of the two markers showed strong linkage disequilibrium between two markers (D’=1).

Conclusion: Apa I and Taq I VDR gene polymorphisms have an association with T1D and may predispose to the risk of T1D affection. While, genotypes AATt, AAtt and aaTT and haplotypes At and aT seem to have a possible protective effect against T1D.