The inhibitor protein of the F1F0-ATP synthase is associated to the external surface of endothelial cells

The ATPase inhibitor protein (IP) of mitochondria was detected in the plasma membrane of living endothelial cells by flow cytometry, competition assays, and confocal microscopy of cells exposed to IP antibodies. The plasma membranes of endothelial cells also possess beta-subunits of the mitochondrial ATPase. Plasma membranes have the capacity to bind exogenous IP. TNF-alpha decreases the level of beta-subunits and increases the amount of IP, indicating that the ratio of IP to beta-subunit exhibits significant variations. Therefore, it is probable that the function of IP in the plasma membrane of endothelial cells is not limited to regulation of catalysis.     

Bcl-2 changes conformation to inhibit Bax oligomerization

Bcl-2 inhibits apoptosis by regulating the release of cytochrome c and other proteins from mitochondria. Oligomerization of Bax promotes cell death by permeabilizing the outer mitochondrial membrane. In transfected cells and isolated mitochondria, Bcl-2, but not the inactive point mutants Bcl-2-G145A and Bcl-2-V159D, undergoes a conformation change in the mitochondrial membrane in response to apoptotic agonists such as tBid and Bax. A mutant Bcl-2 with two cysteines introduced at positions predicted to result in a disulfide bond that would inhibit the mobility of alpha5-alpha6 helices (Bcl-2-S105C/E152C) was only active in a reducing environment. Thus, Bcl-2 must change the conformation to inhibit tBid-induced oligomerization of integral membrane Bax monomers and small oligomers. The conformationally changed Bcl-2 sequesters the integral membrane form of Bax. If Bax is in excess, apoptosis resumes as Bcl-2 is consumed by the conformational change and in complexes with Bax. Thus, Bcl-2 functions as an inhibitor of mitochondrial permeabilization by changing conformation in the mitochondrial membrane to bind membrane-inserted Bax monomers and prevent productive oligomerization of Bax.     

Lipids and DNA oxidation in Staphylococcus aureus as a consequence of oxidative stress generated by ciprofloxacin

Ciprofloxacin induced an increment of reactive oxygen species in sensitive strains of Staphylococcus aureus leading to oxidative stress detected by chemiluminescence while resistant strains did not suffer such stress. Oxidation of lipids was performed by employing thiobarbituric acid reaction to detect the formation of the amplified intermediate between reactive species oxygen and cytoplasmic macromolecules, namely malondialdehyde (MDA). The sensitive strain presented higher peroxidation of lipids than the resistant strain. The oxidative consequence for DNA was investigated by means of bacteria incubation with ciprofloxacin and posterior extraction of DNA, which was studied by high performance liquid chromatography (HPLC). Sensitive S. aureus ATCC 29213 showed an increase of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) respect controls without antibiotic; there was evident increase of the ratio between 8-oxodG and deoxyguanosine (dG) as a consequence of oxidation of dG to 8-oxodG considered the major DNA marker of oxidative stress. The resistant strain showed low oxidation of DNA and the analysis of 8-oxodG/dG ratio indicated lesser formation of 8-oxodG than S. aureus ATCC 29213.     

Do carbon-based defences reduce foliar damage? Habitat-related effects on tree seedling performance in a temperate rainforest of Chiloé Island, Chile

Carbon-based secondary compounds (CBSCs), such as phenols or tannins, have been considered as one of the most important and general chemical barriers of woody plants against a diverse array of herbivores. Herbivory has been described as a critical factor affecting the growth and survival of newly established tree seedlings or juveniles then, the presence of secondary metabolites as defences against herbivores should be a primary strategy to reduce foliar damage. We examined whether light-induced changes in leaf phenolic chemistry affected insect herbivory on seedlings of two rainforest tree species, Drimys winteri (Winteraceae) and Gevuina avellana (Proteaceae). Seedlings of both species were planted under closed canopy and in a canopy gap within a large remnant forest patch. Half of the seedlings in each habitat were disinfected with a wide-spectrum systemic insecticide and the other half were used as controls. Seedling growth, survival, and foliar damage (estimated by an herbivory index) due to insect herbivores were monitored over a period of 16 months (December 2001–April 2003). The total leaf content of phenols and condensed tannins were assessed in seedlings from both habitats. As expected, access to light induced a greater production of CBSCs in seedlings of both tree species, but these compounds did not seem to play a significant defensive role, as seedlings grown in gaps suffered greater leaf damage than those planted in forest interior. In addition, in both habitats, seedlings without insecticide treatment suffered a greater foliar damage than those with insecticide, especially 16 months after the beginning of the experiment. Canopy openness and herbivory had positive and negative effects, respectively, on seedling growth and survival in both tree species. In conclusion, despite the higher levels of defence in tree-fall gap, the higher densities of herbivore override this and lead to higher damage levels.     

Cupriavidus alkaliphilus sp. nov., a new species associated with agricultural plants that grow in alkaline soils

A group of 20 bacterial strains was isolated from the rhizosphere of different agricultural plants growing in alkaline soils in the northeast of Mexico. The phylogenetic analysis of the 16S rRNA gene sequence from four strains showed that this novel group belonged to the Cupriavidus genus, with C. taiwanensis (～98.9%) and C. necator (～98.8%) as the closest species. However, DNA-DNA reassociation values were less than 20%. The novel group did not fix nitrogen and lacked nifH and nodA genes, unlike C. taiwanensis. Whole-cell protein patterns were highly similar among the 20 strains but different from the closest Cupriavidus species. BOX-PCR patterns were distinct among the 20 strains but also differed from other Cupriavidus type species. The major cellular fatty acids from strains ASC-732(T) and SLV-2362 were C(16:0), C(18:1) ω7c/12t/9t and C(16:1) ω7c and/or C(15:0) iso 2OH. The major polar lipids consisted of phosphatidylglycerol, cardiolipin, phosphatidylethanolamine, 2-hydroxylated-phosphatidylethanolamine and an unknown aminolipid. The DNA G+C content of strain ASC-732(T) was 66.8mol%. All 20 strains grew in the presence of 5-10mgmL(-1) arsenic, 1mgmL(-1) zinc, and 0.1mgmL(-1) copper. Consequently, the group of strains was considered to represent a novel species for which the name Cupriavidus alkaliphilus sp. nov. is proposed. The type strain is ASC-732(T) (=LMG 26294(T)=CIP 110330(T)).     

Association study of interleukin-4 polymorphisms with paranoid schizophrenia in the Polish population: a critical approach

Changes in immunological system are one of dysfunctions reported in schizophrenia. Some changes based on an imbalance between Th1 and Th2 cytokines results from cytokine gene polymorphisms. Interleukin-4 gene (IL4) is considered as a potential candidate gene in schizophrenia association studies. The aim of the current case-control study was to examine whether the -590C/T (rs2243250) and -33C/T (rs2070874) IL4 gene polymorphisms are implicated in paranoid schizophrenia development in the Polish population. Genotyping of polymorphisms was performed by using PCR-RFLP technique. The genotypes and alleles distribution of both SNPs were analysed in patients (n = 182) and healthy individuals constituted the control group (n = 215). The connection between some clinical variables and studied polymorphisms has been examined as well. We did not revealed any association between the -590C/T and -33C/T polymorphisms and paranoid schizophrenia. In case of both SNPs the homozygous TT genotype was extremely rare. Both polymorphic sites of the IL4 gene were found to be in a very strong linkage disequilibrium. However we did not identify a haplotype predispose to paranoid schizophrenia. No associations were also observed between the clinical course and psychopathology of the disease and the genotypes of both analysed polymorphisms. Our results suggest that the polymorphisms -590C/T in IL4 gene promoter region and -33C/T in the 5'-UTR are not involved in the pathophysiology of paranoid schizophrenia in Polish residents.