A correlation between BCL-2 modifying factor,p53 and livin gene expressions in cancer colon patients

Accumulating evidence has revealed that livin gene and BCL-2 modifying factor (BMF) gene are closely associated with the initiation and progression of colon carcinoma by activating or suppressing multiple malignant processes. Those genes that can detect colon - cancer are a promising approach for cancer screening and diagnosis. This study aimed to evaluate correlation between livin, BMF and p53 genes expression in colon cancer tissues of patients included in the study, and their relationship with clinicopathological features and survival outcome in those patients. In this study, 50 pathologically diagnosed early cancer colon patients included and their tissue biopsy with 50 matched adjacent normal tissue, and 50 adenoma tissue specimens were analyzed for livin gene and BMF gene expressions using real time PCR. The relationship of those genes expressions with clinicopathological features, tumor markers, Time to Progression and overall survival for those patients were correlated in cancer colon group. In this study, there was a significant a reciprocal relationship between over expression of livin gene and down regulation of BMF and p53 genes in colon cancer cells. Livin mRNA was significantly higher, while BMF and p53 mRNA were significantly lower in colorectal cancer tissue compared to benign and normal colon tissue specimens (P < 0.001), however, this finding was absent between colon adenomas and normal mucosa. There was a significant association between up regulation of livin and down regulation of BMF and p53 expressions with more aggressive tumor (advanced TNM stage), rapid progression with metastasis and decreased overall survival in cancer colon patients, hence these genes can serve as significant prognostic markers of poor outcome in colon cancer patients. This work highlights the role of livin, BMF and p53 genes in colorectal tumorigenesis and the applicability of using those genes as a diagnostic and prognostic markers in patients with colon carcinoma and as a good target for cancer colon treatment in the future.     

Biocides formulation of essential oils having antimicrobial activity

Essential oils of fennel, peppermint, caraway, eucalyptus, geranium and lemon were tested for their antimicrobial activities against some plant pathogenic micro-organisms (Fusarium oxysporum, Alternaria alternate, Penicilium italicum Penicilium digitatum and Botyritus cinerea). Essential oils of fennel, peppermint, caraway were selected as an active ingredient for the formulation of biocides due to their efficiency in controlling the tested micro-organisms. Successful emulsifiable concentrates (biocides) were prepared from these oils using different emulsifiers (Emulgator B.L.M. Tween20 and Tween80) and different fixed oils (sesame, olive, cotton and soybean oils). Physico-chemical properties of the formulated biocide (spontaneous emulsification, emulsion stability test, cold stability and heat stability tests as well as viscosity, surface tension and pH) were measured. The prepared biocides were ready to be tested for application in a future work as a safe pesticide against different pathogens.     

Metagenomic insights into strategies of carbon conservation and unusual sulfur biogeochemistry in a hypersaline Antarctic lake

Organic Lake is a shallow, marine-derived hypersaline lake in the Vestfold Hills, Antarctica that has the highest reported concentration of dimethylsulfide (DMS) in a natural body of water. To determine the composition and functional potential of the microbial community and learn about the unusual sulfur chemistry in Organic Lake, shotgun metagenomics was performed on size-fractionated samples collected along a depth profile. Eucaryal phytoflagellates were the main photosynthetic organisms. Bacteria were dominated by the globally distributed heterotrophic taxa Marinobacter, Roseovarius and Psychroflexus. The dominance of heterotrophic degradation, coupled with low fixation potential, indicates possible net carbon loss. However, abundant marker genes for aerobic anoxygenic phototrophy, sulfur oxidation, rhodopsins and CO oxidation were also linked to the dominant heterotrophic bacteria, and indicate the use of photo- and lithoheterotrophy as mechanisms for conserving organic carbon. Similarly, a high genetic potential for the recycling of nitrogen compounds likely functions to retain fixed nitrogen in the lake. Dimethylsulfoniopropionate (DMSP) lyase genes were abundant, indicating that DMSP is a significant carbon and energy source. Unlike marine environments, DMSP demethylases were less abundant, indicating that DMSP cleavage is the likely source of high DMS concentration. DMSP cleavage, carbon mixotrophy (photoheterotrophy and lithoheterotrophy) and nitrogen remineralization by dominant Organic Lake bacteria are potentially important adaptations to nutrient constraints. In particular, carbon mixotrophy relieves the extent of carbon oxidation for energy production, allowing more carbon to be used for biosynthetic processes. The study sheds light on how the microbial community has adapted to this unique Antarctic lake environment.     

Fine tuning of TCR signaling by CD5

Current data indicate that CD5 functions as an inhibitor of TCR signal transduction. Consistent with this role, thymocyte selection in TCR transgenic/CD5(-/-) mice is altered in a manner suggestive of enhanced TCR signaling. However, the impact of CD5 deletion on thymocyte selection varies depending on the transgenic TCR analyzed, ranging from a slight to a marked shift from positive toward negative selection. An explanation for the variable effect of CD5 on selection is suggested by the observation that CD5 surface expression is regulated by TCR signal intensity during development and CD5 surface levels on mature thymocytes and T cells parallel the avidity of the positively selecting TCR/MHC/ligand interaction. In this study, we generated mice that overexpress CD5 during thymocyte development (CD5-tg), and then examined the effect of CD5 overexpression or CD5 deletion (CD5(-/-)) on selection of thymocytes that express the same TCR transgenes. The results demonstrate that the effect on thymocyte selection of altering CD5 expression depends on the avidity of the selecting interaction and, consequently, the level of basal (endogenous) CD5 surface expression. Substitution of endogenous CD5 with a transgene encoding a truncated form of the protein failed to rescue the CD5(-/-) phenotype, demonstrating that the cytoplasmic domain of CD5 is required for its inhibitory function. Together, these results indicate that inducible regulation of CD5 surface expression during thymocyte selection functions to fine tune the TCR signaling response.     

Glucose Modulates Respiratory Complex I Activity in Response to Acute Mitochondrial Dysfunction

Proper coordination between glycolysis and respiration is essential, yet the regulatory mechanisms involved in sensing respiratory chain defects and modifying mitochondrial functions accordingly are unclear. To investigate the nature of this regulation, we introduced respiratory bypass enzymes into cultured human (HEK293T) cells and studied mitochondrial responses to respiratory chain inhibition. In the absence of respiratory chain inhibitors, the expression of alternative respiratory enzymes did not detectably alter cell physiology or mitochondrial function. However, in permeabilized cells NDI1 (alternative NADH dehydrogenase) bypassed complex I inhibition, whereas alternative oxidase (AOX) bypassed complex III or IV inhibition. In contrast, in intact cells the effects of the AOX bypass were suppressed by growth on glucose, whereas those produced by NDI1 were unaffected. Moreover, NDI1 abolished the glucose suppression of AOX-driven respiration, implicating complex I as the target of this regulation. Rapid Complex I down-regulation was partly released upon prolonged respiratory inhibition, suggesting that it provides an “emergency shutdown” system to regulate metabolism in response to dysfunctions of the oxidative phosphorylation. This system was independent of HIF1, mitochondrial superoxide, or ATP synthase regulation. Our findings reveal a novel pathway for adaptation to mitochondrial dysfunction and could provide new opportunities for combatting diseases.     

Suppression of Mitochondrial DNA Instability of Autosomal Dominant Forms of Progressive External Ophthalmoplegia-Associated ANT1 Mutations in Podospora anserina

Maintenance and expression of mitochondrial DNA (mtDNA) are essential for the cell and the organism. In humans, several mutations in the adenine nucleotide translocase gene ANT1 are associated with multiple mtDNA deletions and autosomal dominant forms of progressive external ophthalmoplegia (adPEO). The mechanisms underlying the mtDNA instability are still obscure. A current hypothesis proposes that these pathogenic mutations primarily uncouple the mitochondrial inner membrane, which secondarily causes mtDNA instability. Here we show that the three adPEO-associated mutations equivalent to A114P, L98P, and V289M introduced into the Podospora anserina ANT1 ortholog dominantly cause severe growth defects, decreased reactive oxygen species production (ROS), decreased mitochondrial inner membrane potential (Δψ), and accumulation of large-scale mtDNA deletions leading to premature death. Interestingly, we show that, at least for the adPEO-type M106P and A121P mutant alleles, the associated mtDNA instability cannot be attributed only to a reduced membrane potential or to an increased ROS level since it can be suppressed without restoration of the Δψ or modification of the ROS production. Suppression of mtDNA instability due to the M106P and A121P mutations was obtained by an allele of the rmp1 gene involved in nucleo-mitochondrial cross- talk and also by an allele of the AS1 gene encoding a cytosolic ribosomal protein. In contrast, the mtDNA instability caused by the S296M mutation was not suppressed by these alleles.THE maintenance and expression of mitochondrial DNA (mtDNA) depend on many nuclear-encoded gene products. Recent studies have shown that defects in this maintenance can have devastating consequences for the cell and the organism. In humans, these defects are an important cause of neurological diseases including autosomal dominant (or recessive) progressive external ophthalmoplegia (adPEO) (Chinnery 2003; Copeland 2008). These disorders are characterized by multiple large-scale deletions of mtDNA. Three different genes that can cause PEO with multiple mtDNA deletions have been identified: the mtDNA polymerase (POLG), the heart/muscle isoform of the adenine nucleotide translocator (ANT1), and the mitochondrial DNA helicase, Twinkle.The adenine nucleotide translocator (ANT), also known as the ADP/ATP mitochondrial translocator, is the most abundant protein in the inner mitochondrial membrane (Riccio et al. 1975; Nury et al. 2006; Klingenberg 2008). It exports ATP produced by mitochondrial oxidative phosphorylation toward the cytosol to meet the energy requirements of the cell; in exchange, it transports ADP into the mitochondrial matrix to fuel the conversion of ADP to ATP by the F₁F_O-ATP synthase. In humans, four isoforms of the ANT protein exist, and they are differently expressed in a tissue-specific manner (Stepien et al. 1992; Palmieri 2004; Dolce et al. 2005). The human ANT1 isoform is predominantly expressed in skeletal and cardiac muscle, and specific ANT1 mutations are associated with adPEO characterized by mtDNA instability (Kaukonen et al. 1999, 2000; Napoli et al. 2001; Komaki et al. 2002; Siciliano et al. 2003). In mice, Ant1 knockout induces mitochondrial myopathy (Graham et al. 1997), increased H₂O₂ production, and mtDNA damage and inhibits oxidative phosphorylation (Esposito et al. 1999). Some of these mutations were introduced in the AAC2 gene of Saccharomyces cerevisiae that encodes the major ADP/ATP mitochondrial translocator isoform in this organism. Numerous and sometimes contradictory effects have been reported depending in particular on the yeast laboratory strains examined (Kaukonen et al. 2000; Chen 2002, 2004; Fontanesi et al. 2004; Palmieri et al. 2005; Wang et al. 2008b).In an attempt to better understand how these mutations affect mitochondrial DNA stability and their functional consequences on mitochondrial metabolism, we decided to introduce them in the unique ADP/ATP translocator gene of Podospora anserina, PaAnt. Like S. cerevisiae, the filamentous fungus P. anserina is an excellent system for genetic and molecular analyses. In contrast to S. cerevisiae, it is a strict multicellular aerobe that can display heteroplasmic states in which intact and rearranged mitochondrial genomes coexist. In this organism, life span is a reflection of mtDNA stability, and death is always associated with large mtDNA rearrangements. “Natural death” or aging is accompanied by large-scale reorganizations of the mtDNA whereas a nuclear-controlled premature death syndrome is accompanied by the accumulation of site-specific mtDNA deletions (Belcour et al. 1999; Silar et al. 2001 for reviews). P. anserina therefore occupies an interesting position among model systems for studying the cellular consequences of mutations in the ADP/ATP translocase gene.We show here that the mutations M106P, A121P, and S296M, equivalent to the L98P, A114P (familial), and V289M (sporadic) human mutations, severely impair the vegetative and sexual development of the fungus and are responsible for decreased ROS production and for decreased inner membrane potential (Δψ). The severity of the phenotypes differs according to the mutation. The three mutations show mtDNA instability, which leads to premature death. All these mutated traits are dominant. Interestingly, the mtDNA instability associated with the M106P and A121P mutations depends on the rmp1 gene. This gene exists under two naturally occurring alleles, rmp1-1 and rmp1-2, which control mtDNA integrity in some genetic contexts (Belcour et al. 1991; Contamine et al. 1996, 2004). When associated with the rmp1-1 allele, the M106P and A121P mutations lead to rapid mtDNA instability whereas, in the presence of the rmp1-2 allele, mtDNA instability is suppressed, and life span is considerably increased. Surprisingly, suppression is not accompanied by a restoration of the Δψ or a modification in the ROS level, demonstrating that these parameters are not sufficient to explain the M106P and A121P mtDNA instability. Mitochondrial DNA instability due to the M106P and A121P mutations is also suppressed by a mutation in the AS1 gene encoding a ribosomal protein. The suppressor effects are not observed for the S296M mutation.     

Germination of <i>Eryngium regnellii</i>: a major species for ecological restoration of plant-pollinator interactions in the Southern Pampas (Buenos Aires,Argentina)

Eryngium regnellii Malme belongs to the largest genera in the Apiaceae family, with 250 species worldwide and 65 represented in South America. It is a herbaceous species typical of hill plant communities, which, along with remnant grassland patches, are the most relevant natural habitats for the maintenance of diversity in the Southern Pampas. Eryngium regnellii is key to the maintenance of pollination mutualisms, being a generalist (displaying a diverse assemblage of pollinators) and ubiquitous species (present in all studied sierras). However, fragmentation of the Pampean landscape due to agricultural intensification has led to the loss of natural environments. Therefore, the reintroduction of E. regnellii in strategic places would facilitate the occurrence of wild pollinators, while favoring pollination services in the agroecosystem. The germination requirements of E. regnellii were studied because a better knowledge of the reproductive biology of this species would provide information relevant to its reproduction and reintroduction into degraded areas. Germination percentages and mean time to germination were evaluated, using one control and two pre-germination treatments: chemical scarification with sulfuric acid, and mechanical scarification with sand paper. Chemical scarified seeds did not germinate. Mechanically scarified and control seed groups showed no significant differences either in germination percentages (49% and 59% respectively) or in mean germination time (13 and 14 days, respectively). Results indicate that E. regnellii shows no physical dormancy, and does not require specific pre-germination treatments for germination under the studied laboratory conditions. The high germination capacity of E. regnellii, along with its ecological attributes, make it a potential species for restoring plant-pollinator interactions in the fragmented landscapes of the Southern Pampas.