Crude Oil Biodegradation by a Soil Indigenous Bacillus sp. Isolated from Lavan Island

The application of microorganisms for removing crude oil pollution from contaminated sites as a type of bioremediation has long been a matter of study in scientific communities. In this study, 35 morphologically different spore-forming Bacilli were isolated from an oil-contaminated soil in Lavan Island. The objective of this study was to investigate the oil-biodegrading ability of these indigenous bacilli. Therefore, their biosurfactant production, using Du Neuy ring, and the crude oil aliphatic and aromatic content alteration after bacterial treatment, respectively, using gas chromatography and high-performance liquid chromatography, were studied. An isolate with high endurance of a wide range of temperature and pH and optimized growth at 30°C and pH 6.8 that could reduce the surface tension from 60 to 40 mN/m and cause the most alteration in aliphatic and aromatic content of crude oil was selected. Using biochemical and molecular analyses of 16SrRNA, this suitable bacterium for oil biodegradation was characterized as Bacillus cereus sp. 4.     

Inactivation of SLIT2-ROBO1/2 pathway in premalignant lesions of uterine cervix: clinical and prognostic significances

The SLIT2-ROBO1/2 pathways control diverse biological processes, including growth regulation. To understand the role of SLIT2 and ROBO1/2 in cervical carcinogenesis, firstly their RNA expression profiles were screened in 21 primary uterine cervical carcinoma (CACX) samples and two CACX cell lines. Highly reduced expressions of these genes were evident. Concomitant alterations [deletion/methylation] of the genes were then analyzed in 23 cervical intraepithelial neoplasia (CIN) and 110 CACX samples. In CIN, SLIT2 was deleted in 22% samples compared to 9% for ROBO1 and none for ROBO2, whereas comparable methylation was observed for both SLIT2 (30%) and ROBO1 (22%) followed by ROBO2 (9%). In CACX, alteration of the genes were in the following order: Deletion:ROBO1 (48%) > SLIT2 (35%) > ROBO2 (33%), Methylation:SLIT2 (34%) > ROBO1 (29%) > ROBO2 (26%). Overall alterations of SLIT2 and/or ROBO1 (44%) and SLIT2 and/or ROBO2 (39%) were high in CIN followed by significant increase in stage I/II tumors, suggesting deregulation of these interactions in premalignant lesions and early invasive tumors. Immunohistochemical analysis of SLIT2 and ROBO1/2 in CACX also showed reduced expression concordant with molecular alterations. Alteration of all these genes predicted poor patient outcome. Multiparous (≥ 5) women with altered SLIT2 and ROBO1 along with advanced tumor stage (III/IV) and early sexual debut (<19 years) had worst prognosis. Our data suggests the importance of abrogation of SLIT2-ROBO1 and SLIT2-ROBO2 interactions in the initiation and progression of CACX and also for early diagnosis and prognosis of the disease.     

Motion and flexibility in human cytochrome p450 aromatase

The crystal structures of human placental aromatase in complex with the substrate androstenedione and exemestane have revealed an androgen-specific active site and the structural basis for higher order organization. However, X-ray structures do not provide accounts of movements due to short-range fluctuations, ligand binding and protein-protein association. In this work, we conduct normal mode analysis (NMA) revealing the intrinsic fluctuations of aromatase, deduce the internal modes in membrane-free and membrane-integrated monomers as well as the intermolecular modes in oligomers, and propose a quaternary organization for the endoplasmic reticulum (ER) membrane integration. Dynamics of the crystallographic oligomers from NMA is found to be in agreement with the isotropic thermal factors from the X-ray analysis. Calculations of the root mean square fluctuations of the C-alpha atoms from their equilibrium positions confirm that the rigid-core structure of aromatase is intrinsic regardless of the changes in steroid binding interactions, and that aromatase self-association does not deteriorate the rigidity of the catalytic cleft. Furthermore, NMA on membrane-integrated aromatase shows that the internal modes in all likelihood contribute to breathing of the active site access channel. The collective intermolecular hinge bending and twisting modes provide the flexibility in the quaternary association necessary for membrane integration of the aromatase oligomers. Taken together, fluctuations of the active site, the access channel, and the heme-proximal cavity, and a dynamic quaternary organization could all be essential components of the functional aromatase in its role as an ER membrane-embedded steroidogenic enzyme.     

Expression of CD13/aminopeptidase N in precursor B-cell leukemia: role in growth regulation of B cells

Expression of cell surface CD13 in acute B-cell leukemia (ALL-B) is often viewed, as an aberrant expression of a myeloid lineage marker. Here, we attempted to study the stage specific expression of CD13 on ALL-B blasts and understand its role in leukemogenesis as pertaining to stage of B-cell ontogeny. A total of 355 cases of different hematological malignancies were diagnosed by immunophenotyping. Among 68 cases of early B-cell ALL, 22 cases with distinct immunophenotype was identified as immature B-cell ALL. Blasts from these ALL-B patients demonstrated prominent expression of CD10, CD19, CD22, but neither cytoplasmic nor surface IgM receptors. This strongly indicates leukemogenesis at an early stage of B-cell development. We also identified, the existence of a subpopulation of cells with remarkably similar phenotype in non-leukemic marrow from healthy subjects (expressing CD10, CD19, CD22, CD24, Tdt together with the co-expression of CD13). This sub-population of B cells concomitantly expressing CD13 appeared to be a highly proliferating group. By blocking their cell surface CD13 in leukemic blasts with monoclonal antibody we were able to inhibit their proliferation. We hypothesized that neoplastic transformation at this stage may be facilitated by CD13. CD13 may thus be an important target for novel molecular therapy of early stage acute B-cell leukemia.     

Early development of intracellular calcium cycling defects in intact hearts of spontaneously hypertensive rats

Defects in excitation-contraction coupling have been reported in failing hearts, but little is known about the relationship between these defects and the development of heart failure (HF). We compared the early changes in intracellular Ca(2+) cycling to those that underlie overt pump dysfunction and arrhythmogenesis found later in HF. Laser-scanning confocal microscopy was used to measure Ca(2+) transients in myocytes of intact hearts in Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs) at different ages. Early compensatory mechanisms include a positive inotropic effect in SHRs at 7.5-9 mo compared with 6 mo. Ca(2+) transient duration increased at 9 mo in SHRs, indicating changes in Ca(2+) reuptake during decompensation. Cell-to-cell variability in Ca(2+) transient duration increased at 7.5 mo, decreased at 9 mo, and increased again at 22 mo (overt HF), indicating extensive intercellular variability in Ca(2+) transient kinetics during disease progression. Vulnerability to intercellular concordant Ca(2+) alternans increased at 9-22 mo in SHRs and was mirrored by a slowing in Ca(2+) transient restitution, suggesting that repolarization alternans and the resulting repolarization gradients might promote reentrant arrhythmias early in disease development. Intercellular discordant and subcellular Ca(2+) alternans increased as early as 7.5 mo in SHRs and may also promote arrhythmias during the compensated phase. The incidence of spontaneous and triggered Ca(2+) waves was increased in SHRs at all ages, suggesting a higher likelihood of triggered arrhythmias in SHRs compared with WKY rats well before HF develops. Thus serious and progressive defects in Ca(2+) cycling develop in SHRs long before symptoms of HF occur. Defective Ca(2+) cycling develops early and affects a small number of myocytes, and this number grows with age and causes the transition from asymptomatic to overt HF. These defects may also underlie the progressive susceptibility to Ca(2+) alternans and Ca(2+) wave activity, thus increasing the propensity for arrhythmogenesis in HF.     

Controlled Comparison of Tetracycline and Furazolidone in Cholera

A controlled comparison of furazolidone and tetracycline in the treatment of cholera indicates that, in either dosage used, furazolidone reduced total stool volume by 50% and duration of diarrhoea by 40%. These results are comparable to those achieved with tetracycline, which was given in presently recommended dosage. Both furazolidone and tetracycline significantly reduced the rate of stool output within 18 to 24 hours of starting antibiotic treatment. Furazolidone was significantly less effective than tetracycline in rapidly and consistently terminating vibrio excretion. One convalescent carrier of cholera vibrios was identified among control patients; none was identified among patients treated with either tetracycline or furazolidone. All Vibrio cholerae strains tested were sensitive to tetracycline and furazolidone, but larger concentrations of the latter were required to achieve inhibition of growth. It is concluded that tetracycline remains the antibiotic of choice in cholera but that furazolidone would be a useful adjunct to cholera therapy when tetracycline is unobtainable or if strains of V. cholerae with clinically significant resistance to tetracycline should be encountered.     

Energy-minimized structures and MO levels of catalysts related to [RuO(hpsd)(bpy)] that competently hydroxylate benzene (hpsd(2-)=(2-hydroxyphenyl)salicyldiminato)

Two series of complexes with formal oxidation state assignments of {Ru^V(O²⁻)} have been examined by molecular mechanics and molecular orbital methods at the level of PM3 calculations in order to assess the origin of differences in the activity of these complexes in the conversion of benzene to phenol by oxygen transfer. The first series includes complexes of general formula [RuO(hpsd)(XY)]ⁿ⁺ with hpsd²⁻ (also known in the literature as amp²⁻)=(2-hydroxyphenyl)salicyldiminato; XY=bpy(2,2^′-bipyridine) and other py-X, wherein the second pyridyl group of bpy is changed to X=-CH₂N(CH₃)₂ (stronger σ-donor X), -CH₂P(CH₃)₂ (better π-acceptor X), -CO₂ ⁻ (weak π-donor X), -CH₂S⁻ (strong π-donor X), and -CH₂C(CH₃)₂ ⁻ (very strong σ-donor X).A second series of complexes, [RuO(TDL)(bpy)]ⁿ⁺ was also studied with TDL=(tridentate ligand) of the parent hpsd²⁻ (or amp²⁻); cpsd²⁻=(N-(2-carboxyphenyl)salicylaldiminato); cppc⁻=(N-2-carboxyphenylpyridine-2-carboxaldiminato); and hppc⁻=(2-hydroxyphenyl)2-pyridylcarboxaldiminato (or app⁻). Experimentally, the activity order based upon the percentage yields of oxygenated products for [RuO(TDL)(bpy)]ⁿ⁺ is as follows for TDL’s=hpsd²⁻ (91%) > cppc⁻ (87%) > cpsd²⁻ (84%) > hppc⁻ (80%). The rates approach toward saturation in reactivity as a function of the fractional positive charge on the apical O center: cppc⁻ (0.233) > hpsd²⁻ (0.166) > cpsd²⁻ (0.105) > hppc⁻ (0.041). The reactivity order follows chelate ring strain influences of the TDL, with 5,6-membered chelate rings; hpsd²⁻ and cppc⁻ > 6,6; cpsd²⁻ > 5,5; hppc⁻.It was determined that the general structures of these complexes are best described as pentagonal pyramidal (rather than pseudo-octahedral) with the RuO unit apical, the three donors of hpsd²⁻, cpsd²⁻, cppc⁻ or hppc⁻, and the two donors of XY ligands adopting a waffled arrangement around the Ru center as the remaining donors of the pentagonal set. The donor most trans to the apical RuO is approximately at 140°, rather than 180°. Ligands such as hpsd²⁻ (amp²⁻) are not retained in a single planar array, but rather with one of the aromatic donors turned upward to shield the approach of the RuO unit from one side. The ligand series [RuO(hpsd)(XY)]⁺ averages angles between adjacent atoms of the pentagonal set of 75.4° instead of a theoretical 72.0°; angles between the apical RuO and adjacent donors average 111° but with wide deviations (±30°) depending upon the donors of the TDL.Small changes in the donor atom positions, and in the capability of the “trans” donor’s σ-donor strength, and whether it is a π-acceptor or a π-donor, modulate the degree of mixing of ligand orbitals and the LUMO/SOMO energy gap which influences reactivity. The presence of a π-acceptor ligand provides the most destabilization of Ru-O π bonding, and this appears to be the best way to increase the activity of these catalysts toward oxidation of C₆H₆ to C₆H₅OH. Also, implicated in the activity of the catalysts is the need for two non-innocent phenolate donors that raise the energy of orbitals on the apical O atom. This increases the oxenoid character of the terminal O, and makes the insertion into a C-H bond more favored.