Studies on halotolerance in a moderately halophilic bacterium. Effect of betaine on salt resistance of the respiratory system

The role of betaine as a factor influencing the salt resistance of the respiratory system in resting cells of the moderately halophilic halotolerant bacterium Ba(1) was studied. Betaine accelerated succinate oxidation in cells obtained from low-salt medium, and stimulation of the respiratory rate was stronger the higher the sodium chloride concentration in the assay medium. The stimulatory effect also depended on the ratio of betaine concentration to the amount of bacteria present. Accumulation of labelled betaine by the bacterial cells was demonstrated; like the respiratory stimulation, it was favourably influenced by an increase in the sodium chloride concentration of the medium. In cells harvested from a high-salt medium and washed with 2.0m-sodium chloride, betaine caused no increase in the respiratory rate, nor was the already high salt resistance of the respiratory system further improved by the addition of betaine. When, however, these cells lost their salt resistance as a result of washing in the absence of sodium chloride, betaine was able to restore it to its original level. In contrast with respiration in low-salt-grown bacteria, that in high-salt-grown cells was not affected by betaine, even after they were washed in the absence of sodium chloride, when the sodium chloride concentration was optimum.     

Inhibition of pMAPK14 Overcomes Resistance to Sorafenib in Hepatoma Cells with Hepatitis B Virus

Hepatitis B virus (HBV) targets the liver and is a major driver for liver cancer. Clinical data suggest that HBV infection is associated with reduced response to treatment with the multi-kinase inhibitor sorafenib, the first available molecularly targeted anti-hepatocellular carcinoma (HCC) drug. Given that Raf is one of the major targets of sorafenib, we investigated the activation state of the Raf-Mek-Erk pathway in the presence of HBV and in response to sorafenib. Here we show that hepatoma cells with replicating HBV are less susceptible to sorafenib inhibitory effect as compared to cells in which HBV expression is suppressed. However, although HBV replication is associated with increased level of pErk, its blockade only modestly augments sorafenib effect. In contrast, the phosphorylated form of the pro-oncogenic Mitogen-Activated Protein Kinase 14 (pMAPK14), a protein kinase that was recently linked to sorafenib resistance, is induced in sorafenib-treated hepatoma cells in association with HBV X protein expression. Knocking down pMAPK14 results in augmentation of the therapeutic efficacy of sorafenib and largely alleviates resistance to sorafenib in the presence of HBV. Thus, this study suggests that HBV promotes HCC resistance to sorafenib. Combining pMAPK14 inhibitors with sorafenib may be beneficial in patients with HBV-associated HCC.     

Biodegradation of alkylpyridines by bacteria isolated from a polluted subsurface

Ten bacterial strains were isolated from alkylpyridine polluted sediments 7.6 m below the surface. These strains were able to degrade 11 different alkylpyridine isomers. Degradation rates depended on number and position of the alkyl group. Isomers with an alkyl group at position 3 were more resistant to microbial attack. Of the 10 strains, 6 isolates were selected for detailed study. These isolates mineralized the isomers to CO2, NH4+, and biomass. All strains were gram-negative rods with a strict aerobic metabolism. Characterization of physiological and biochemical properties revealed similarity between strains. Eeach strain however, had a limited substrate range which enabled it to degrade no more than 2 to 3 compounds of the 14 alkylpyridine isomers tested. Examination of the genetic variability among cultures with the randomly amplified polymorphic DNA technique revealed high levels of genomic DNA polymorphism. The highest similarity between 2 strains (0.653) was observed between 2-picoline and 3-picoline degrading cultures. The molecular basis of the differences in substrate specificity is under investigation.     

The founder mutations 185delAG and 5382insC in BRCA1 and 6174delT in BRCA2 appear in 60% of ovarian cancer and 30% of early-onset breast cancer patients among Ashkenazi women.

The mutations 185delAG, 188del11, and 5382insC in the BRCA1 gene and 6174delT in the BRCA2 gene were analyzed in 199 Ashkenazi and 44 non-Ashkenazi Jewish unrelated patients with breast and/or ovarian cancer. Of the Jewish Ashkenazi women with ovarian cancer, 62% (13/21) had one of the target mutations, as did 30% (13/43) of women with breast cancer alone diagnosed before the age 40 years and 10% (15/141) of those with breast cancer diagnosed after the age 40 years. Age at ovarian cancer diagnosis was not associated with carrier status. Of 99 Ashkenazi patients with no family history of breast and/or ovarian cancer, 10% carried one of the mutations; in two of them the mutation was proved to be paternally transmitted. One non-Ashkenazi Jewish ovarian cancer patient from Iraq carried the 185delAG mutation. Individual mutation frequencies among breast cancer Ashkenazi patients were 6.7% for 185delAG, 2.2% for 5382insC, and 4.5% for 6174delT, among ovarian cancer patients; 185delAG and 6174delT were about equally common (33% and 29%, respectively), but no ovarian cancer patient carried the 5382insC. More mutations responsible for inherited breast and ovarian cancer probably remain to be found in this population, since 79% of high-incidence breast cancer families and 35% of high-incidence breast/ovarian cancer families had none of the three known founder mutations.     

Diversity of β-Globin Mutations in Israeli Ethnic Groups Reflects Recent Historic Events

We characterized nearly 500 β-thalassemia genes from the Israeli population representing a variety of ethnic subgroups. We found 28 different mutations in the β-globin gene, including three mutations (β^S, β^C, and β^O-Arab) causing hemoglobinopathies. Marked genetic heterogeneity was observed in both the Arab (20 mutations) and Jewish (17 mutations) populations. On the other hand, two ethnic isolates—Druze and Samaritans—had a single mutation each. Fifteen of the β-thalassemia alleles are Mediterranean in type, 5 originated in Kurdistan, 2 are of Indian origin, and 2 sporadic alleles came from Europe. Only one mutant allele—nonsense codon 37—appears to be indigenous to Israel. While human habitation in Israel dates back to early prehistory, the present-day spectrum of β-globin mutations can be largely explained by migration events that occurred in the past millennium.     

PA-I and PA-II lectin interactions with the ABO(H) and P blood group glycosphingolipid antigens may contribute to the broad spectrum adherence ofPseudomonas aeruginosa to human tissues in secondary infections

Pseudomonas aeruginosa may cause serious infections in most human tissues/organs. Its adherence to them is mediated by a battery of adhesins including the PA-I and PA-II lectins, which are produced in this bacterium in high quantities. PA-I binds to thed-galactose of the erythrocyte glycosphingolipids exhibiting highest affinities for B and P^k (followed by P₁) antigens, while PA-II preferentially binds to thel-fucose of H, A and B antigens. IntactP. aeruginosa cells also exhibit a clear P^k and P₁ over p preference. Such affinities for the most common human ABH and P system antigens may underlie the widespread tissue infectivity and pathogenicity of this bacterium.     

The “acid growth effect” and geotropism

Summary The curvature developed by segments of sunflower hypocotyl exposed to gravitational stimulus was enhanced in buffer solutions between pH 3.4 and 4.0 in the absence of added auxin. This effect was observed both when the segments were submerged during the stimulus and when they floated near the surface of the solution. 5–10 min in a horizontal position was sufficient to induce subsequent curvature.Straight growth of the segments was also promoted in buffers of this pH range.The acid effect on curvature was insensitive to KAsO₂, HgCl₂ and cycloheximide, inhibitors which drastically reduced auxin-induced curvature. Furthermore, acid buffer, but not auxin, restored the ability of segments taken from etiolated and starved plants to respond to gravity. These results suggest that the polarisation following gravistimulus may not be resticted to the asymmetric distribution of auxin and auxin co-factors but may involve a general physiological asymmetry.     

Non-random chromosomal aberrations in a complex leukaemic clone of a Bloom's syndrome patient

Summary Bloom's syndrome is one of the congenital disorders known to have increased frequency of acute leukaemia. The complex cytogenetic findings in the leukaemic cells of a 39-year-old male with Bloom's syndrome are described. These included a translocation t(7;17), missing 7q and 17p, a reciprocal translocation t(4;22); del 3q, del 8q22, del 20q, missing 12 and missing Y. In the same patient a missing Y had been noted 10 years previously in 15% of his peripheral blood lymphocytes.     

Molecular imaging of cell death in vivo by a novel small molecule probe

Apoptosis has a role in many medical disorders, therefore assessment of apoptosis in vivo can be highly useful for diagnosis, follow-up and evaluation of treatment efficacy. ApoSense is a novel technology, comprising low molecular-weight probes, specifically designed for imaging of cell death in vivo. In the current study we present targeting and imaging of cell death both in vitro and in vivo, utilizing NST-732, a member of the ApoSense family, comprising a fluorophore and a fluorine atom, for both fluorescent and future positron emission tomography (PET) studies using an ¹⁸F label, respectively. In vitro, NST-732 manifested selective and rapid accumulation within various cell types undergoing apoptosis. Its uptake was blocked by caspase inhibition, and occurred from the early stages of the apoptotic process, in parallel to binding of Annexin-V, caspase activation and alterations in mitochondrial membrane potential. In vivo, NST-732 manifested selective uptake into cells undergoing cell-death in several clinically-relevant models in rodents: (i) Cell-death induced in lymphoma by irradiation; (ii) Renal ischemia/reperfusion; (iii) Cerebral stroke. Uptake of NST-732 was well-correlated with histopathological assessment of cell-death. NST-732 therefore represents a novel class of small-molecule detectors of apoptosis, with potential useful applications in imaging of the cell death process both in vitro and in vivo. Revital Aloya and Anat Shirvan are equal contribution to the paper