Contacts between mammalian mitochondrial translational initiation factor 3 and ribosomal proteins in the small subunit

Mammalian mitochondrial translational initiation factor 3 (IF3(mt)) binds to the small subunit of the ribosome displacing the large subunit during the initiation of protein biosynthesis. About half of the proteins in mitochondrial ribosomes have homologs in bacteria while the remainder are unique to the mitochondrion. To obtain information on the ribosomal proteins located near the IF3(mt) binding site, cross-linking studies were carried out followed by identification of the cross-linked proteins by mass spectrometry. IF3(mt) cross-links to mammalian mitochondrial homologs of the bacterial ribosomal proteins S5, S9, S10, and S18-2 and to unique mitochondrial ribosomal proteins MRPS29, MRPS32, MRPS36 and PTCD3 (Pet309) which has now been identified as a small subunit ribosomal protein. IF3(mt) has extensions on both the N- and C-termini compared to the bacterial factors. Cross-linking of a truncated derivative lacking these extensions gives the same hits as the full length IF3(mt) except that no cross-links were observed to MRPS36. IF3 consists of two domains separated by a flexible linker. Cross-linking of the isolated N- and C-domains was observed to a range of ribosomal proteins particularly with the C-domain carrying the linker which showed significant cross-linking to several ribosomal proteins not found in prokaryotes.     

Changes in gravity rapidly alter the magnitude and direction of a cellular calcium current

In single-celled spores of the fern Ceratopteris richardii, gravity directs polarity of development and induces a directional, trans-cellular calcium (Ca²⁺) current. To clarify how gravity polarizes this electrophysiological process, we measured the kinetics of the cellular response to changes in the gravity vector, which we initially estimated using the self-referencing calcium microsensor. In order to generate more precise and detailed data, we developed a silicon microfabricated sensor array which facilitated a lab-on-a-chip approach to simultaneously measure calcium currents from multiple cells in real time. These experiments revealed that the direction of the gravity-dependent polar calcium current is reversed in less than 25 s when the cells are inverted, and that changes in the magnitude of the calcium current parallel rapidly changing g-forces during parabolic flight on the NASA C-9 aircraft. The data also revealed a hysteresis in the response of cells in the transition from 2g to micro-g in comparison to cells in the micro-g to 2-g transition, a result consistent with a role for mechanosensitive ion channels in the gravity response. The calcium current is suppressed by either nifedipine (calcium-channel blocker) or eosin yellow (plasma membrane calcium pump inhibitor). Nifedipine disrupts gravity-directed cell polarity, but not spore germination. These results indicate that gravity perception in single plant cells may be mediated by mechanosensitive calcium channels, an idea consistent with some previously proposed models of plant gravity perception.     

Structural and metabolic correlation for Bacillus megaterium ACBT03 in response to colchicine biotransformation

This study aims to evaluate the effects of colchicine on metabolic and structural changes in Bacillus megaterium ACBT03, enduring colchicine bioconversion. Electron microscopy examination of cells adapted to different concentrations of colchicine for its bioconversion to pharmacologically active 3-demethylated colchicine, endowed changes in cell shape, decreased cell wall and plasma membrane thickness. In line with microscopic studies, lipid and membrane protein contents were drastically reduced in bacterial cells adapted to higher concentrations of colchicine and resulting into decrease in cell membrane thickness. More numbers of polyhydroxybutyrate (PHB) rich inclusion bodies were found inside the colchicine adapted cells and presence of higher amount of PHB, a carbon source for generation of redox potential, indicates that it might be responsible for activation of P450 BM-3 enzyme and plays significant role in colchicine demethylation. The presence of dense ribosome like bodies in colchicine adapted cells showed higher biosynthesis of P450 BM-3. Reduction in cell wall and cell membrane thickness, presence of more inclusion bodies and ribosome like masses in colchicine adapted cells were some of the key interlinked phenomena responsible for colchicine bioconversion. This is the first study which reports that colchicine demethylation process severely affects the structural and metabolic functions of the bacteria.     

Association of mutation and hypermethylation of p21 gene with susceptibility to breast cancer: a study from north India

p21 gene located at chromosome 6p21.2 is a possible tumour suppressor gene involved in the pathogenesis of breast cancer. Both genetic and epigenetic alterations in p21 have been implicated in breast carcinoma. In the present study, our main aim was to study the impact of these two kinds of alterations of p21 gene in Indian female breast cancer patients. A total of 150 female breast cancer patients of north India were screened by PCR-SSCP followed by direct sequencing and methylation specific PCR. Mutational screening of p21 gene revealed significant amount of mutations [32.66 % (49/150)] in exon 2, whereas p21 promoter was found hypermethylated in 42 of 150 (28 %) breast cancer patients in our population. The intriguing feature of the study was the G>T transition (GAG>TAG) at codon 107 and the A>C transition (AGC>CGC) at codon 146 possibly rendering p21 completely ineffective in its anti- proliferative activity. Our results suggest a significant association between the mutational and hypermethylation profile of p21 gene. Therefore, we show for the first time that the significant association of p21 mutation and hypermethylation leads to the complete inactivation of p21 gene in Indian female breast cancer patients. Complete silencing of the p21 gene seems to be the result not only of genetic alterations but also of epigenetic modification.     

Pesticidal and pest repellency activities of a plant derived triterpenoid 2α,3β,21β,23,28-penta hydroxyl 12-oleanene against Tribolium castaneum

Background

Tribolium castaneum (Herbst) is a major pest of stored grain-based products, and cause severe damage to cereal grains throughout the world. The present investigation was aimed to determine the pesticidal and pest repellent activities of 2α,3β,21β,23,28-penta hydroxyl 12-oleanene against T. castaneum. The compound 2α,3β,21β,23,28-penta hydroxyl 12-oleanene is a triterpenoid which was isolated from the roots of Laportea crenulata Gaud. Surface film technique was used for pesticidal screening, whereas, pest repellency property of the triterpenoid was determined by filter paper disc method.

Results

At 24 hours of exposure duration, significant mortality records (80% and 86%) were observed at doses 0.88 and 1.77 mg/cm². No significant change in mortality records was observed when duration of exposure was increased up to 48 hours. The triterpenoid showed significant repellency activity at doses 0.47 and 0.94 mg/cm².

Conclusion

These data suggest that the triterpenoid 2α,3β,21β,23,28-penta hydroxyl 12-oleanene possess both pesticidal and pest repellency activities against T. castaneum and can be used in controlling the pest of grain-based products.

Electronic supplementary material

The online version of this article (doi:10.1186/0717-6287-47-68) contains supplementary material, which is available to authorized users.     

Study of rust resistance genes in wheat germplasm with DNA markers

Wheat is a vital dietary component for human health and widely consumed in the world. Wheat rusts are dangerous pathogens and contribute serious threat to its production. In present study, PCR-Based DNA Markers were employed to check the rust resistance genes among 20 wheat genotypes and 22 markers were amplified. NTSYS-pc 2.2 was used to calculate genetic diversity and Nei and Li''s coefficients ranged from 0.55 to 0.95. Cluster analysis was obtained using UPGMA (Unweighted Pair Group Method of Arithmetic Average) algorithm. Maximum no. of genes (23) was amplified from TW-760010 genotype whereas minimum no of genes (14) were amplified from TW-76005 genotype. The data gained from present study open up new ways to produce new varieties by breeding rust resistant germplasm to avoid the economic and food loss and varieties with improved characteristics.     

No Correlation between TIMP2 -418 G>C Polymorphism and Increased Risk of Cancer: Evidence from a Meta-Analysis

Aim

Tissue inhibitor of metalloproteinase (TIMP2) is involved in the regulation of matrix metalloproteinase 2 (MMP2) and shown to implicate in cancer development and progression. The results from the published studies based on the association between TIMP2 -418 G>C polymorphism and cancer risk are inconsistent. In this meta-analysis, we aimed to evaluate the potential association between TIMP2 -418 G>C polymorphism and cancer risk.

Methodology

We searched PubMed (Medline) and EMBASE web databases to cover all studies based on relationship of TIMP2 -418 G>C polymorphism and risk of cancer until October 2013. The meta-analysis was performed for selected case-control studies and pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated for all genetic models.

Results

A total of 2225 cancer cases and 2532 controls were included from ten eligible case-control studies. Results from overall pooled analysis suggested no evidence of significant risk between TIMP2 -418 G>C polymorphism and cancer risk in any of the genetic models, such as, allele (C vs. G: OR = 1.293, 95% CI = 0.882 to 1.894, p = 0.188), homozygous (CC vs. GG: OR = 0.940, 95% CI = 0.434 to 2.039, p = 0.876), heterozygous (GC vs. GG: OR = 1.397, 95% CI = 0.888 to 2.198, p = 0.148), dominant (CC+GC vs. GG: OR = 1.387, 95% CI = 0.880 to 2.187, p = 0.159) and recessive (CC vs. GG+GC: OR = 0.901, 95% CI = 0.442 to 1.838, p = 0.774) models. No evidence of publication bias was detected during the analysis.

Conclusions

The present meta-analysis suggests that the TIMP2 -418 G>C polymorphism may not be involved in predisposing risk factor for cancer in overall population. However, future larger studies with group of populations are needed to analyze the possible correlation.