The inhibitory effect of boric acid on hypoxia-regulated tumour-associated carbonic anhydrase IX

Carbonic anhydrases (EC 4.2.1.1) catalyse the reversible hydration of CO₂ into bicarbonate and protons. As a hypoxia-sensitive and tumour-associated isoform, isoform CA IX, is significantly overexpressed in various malignancies, being a validated target for new anticancer/antimetastatic drugs. A multitude of studies has shown that CA IX inhibition decreases cancer cell proliferation and metastasis through pHe/pHi modulation and enhancement of ferroptosis among others. Numerous studies demonstrated increased efficacy of cytotoxic drugs combined with CA inhibitors (CAIs) in various cancer types. We tested the inhibitory effect of boric acid (BA), an inorganic Lewis acid, on CA IX as well as other isoforms (CA I, II, and XII). BA acted as a millimolar in vitro CAI, decreased proliferation of two cancer cell lines, although not strong correlations between the in vitro inhibition and in vivo effects were observed. The mechanism of antiproliferative action of BA should be investigated in more detail.     

Soil microbes alter plant fitness under competition and drought

Plants exist across varying biotic and abiotic environments, including variation in the composition of soil microbial communities. The ecological effects of soil microbes on plant communities are well known, whereas less is known about their importance for plant evolutionary processes. In particular, the net effects of soil microbes on plant fitness may vary across environmental contexts and among plant genotypes, setting the stage for microbially mediated plant evolution. Here, we assess the effects of soil microbes on plant fitness and natural selection on flowering time in different environments. We performed two experiments in which we grew Arabidopsis thaliana genotypes replicated in either live or sterilized soil microbial treatments, and across varying levels of either competition (isolation, intraspecific competition or interspecific competition) or watering (well‐watered or drought). We found large effects of competition and watering on plant fitness as well as the expression and natural selection of flowering time. Soil microbes increased average plant fitness under interspecific competition and drought and shaped the response of individual plant genotypes to drought. Finally, plant tolerance to either competition or drought was uncorrelated between soil microbial treatments suggesting that the plant traits favoured under environmental stress may depend on the presence of soil microbes. In summary, our experiments demonstrate that soil microbes can have large effects on plant fitness, which depend on both the environment and individual plant genotype. Future work in natural systems is needed for a complete understanding of the evolutionary importance of interactions between plants and soil microorganisms.     

Heliotherapy for Neonatal Hyperbilirubinemia in Southwest,Nigeria: A Baseline Pre-Intervention Study

Background

A novel filtered-sunlight phototherapy (FSPT) device has been demonstrated to be safe and efficacious for treating infants with neonatal jaundice in resource-constrained tropical settings. We set out to provide baseline data for evaluating the clinical impact of this device in a referral pediatric hospital.

Methods

We reviewed the medical records of infants admitted for neonatal hyperbilirubinemia in an inner-city Children’s Hospital in Lagos, between January 2012 and December 2014 to determine the pattern, treatment and outcomes during the pre-intervention period. Factors associated with adverse outcomes were identified through multivariable logistic regression.

Results

Of the 5,229 neonatal admissions over the period, a total of 1,153 (22.1%) were admitted for neonatal hyperbilirubinemia. Complete records for 1,118 infants were available for analysis. The incidence of acute bilirubin encephalopathy (ABE) and exchange transfusion (ET) were 17.0% (95% CI: 14.9%–19.3%) and 31.5% (95% CI: 28.8%–34.3%) respectively. A total of 61 (5.5%, 95% CI: 4.3%–6.9%) of the jaundiced infants died. Weight on admission, peak total serum bilirubin (TSB), sepsis and exposure to hemolytic products were predictive of ABE, while age on admission, peak TSB, ABO incompatibility and ABE were predictive of ET. Rhesus incompatibility, asphyxia, exposure to hemolytic substances and ABE were associated with elevated mortality risk, while ET was a protective factor. Lack of routine irradiance monitoring and steady energy supply were frequent challenges for conventional blue-light phototherapy.

Conclusions

Severe hyperbilirubinemia is associated with high rates of ABE and ET in this setting, and remains a significant contributor to neonatal admissions and mortality. To be impactful, FSPT, complemented with improved diagnostic facilities, should effectively curtail jaundice-related adverse outcomes in this and comparable settings.     

Isolation and characterization of a new osmotolerant, non-virulent Klebsiella pneumoniae strain SAP for biosynthesis of succinic acid

In the present study, isolation of anaerobic bacteria from 24 different eco-niches was carried out. A total number of 300 bacterial isolates, including 230 obligate and 70 facultative anaerobes were obtained using anaerobic techniques. All the isolates were initially screened for succinic acid production by Fluorescein test and TLC method. During screening, 10 isolates found to produce succinic acid were further examined by HPLC and then finally confirmed for succinic acid by LC-MS analysis. Amongst 10 isolates, isolate SAP, a facultative anaerobe isolated from buffalo rumen fluid, showed maximum yield of 2.1 g/l of succinic acid from 10 g of glucose in 24 hr under anaerobic condition. This isolate was identified as Klebsiella pneumoniae strain SAP by 16S rDNA sequence and signature sequence analysis. Mouse lethality test for the strain SAP showed LD50 value of 3.3 x 10(8) CFU/ml, which shows non-virulent nature of the strain. This strain may become a candidate strain for succinic acid production because of its osmotolerant nature and higher succinate:acetate ratio.     

Iraqi propolis increases degradation of IL-1β and NLRC4 by autophagy following Pseudomonas aeruginosa infection

Autophagy is a cellular process for maintaining cellular homeostasis. This process can be induced by different factors, such as immune stimuli and pathogen-associated molecules. Autophagy has an important role in the control of IL-1β secretion by macrophages and other cell types. In present study, we describe a novel role for Iraqi propolis affecting autophagy in controlling the secretion of IL-1β in bone-marrow macrophages (BMDMs). After infection with Pseudomonas aeruginosa in the presence of propolis, the degradation of IL-1β was induced, and the activity of inflammasome was reduced. Iraqi propolis-induced autophagy in in vitro and in vivo models decreased the levels of IL-1β and caspase-1. Results indicated that IL-1β pathway production is regulated by autophagy via two different novel mechanisms, namely, regulation of the activation of NLRC4 inflammasome and IL-1β targeting for lysosomal degradation.     

Structural Characterization of a Gcn5-Related N-Acetyltransferase from Staphylococcus aureus

The Gcn5-related N-acetyltransferases (GNATs) are ubiquitously expressed in nature and perform a diverse range of cellular functions through the acetylation of small molecules and protein substrates. Using activated acetyl coenzyme A as a common acetyl donor, GNATs catalyse the transfer of an acetyl group to acceptor molecules including aminoglycoside antibiotics, glucosamine-6-phosphate, histones, serotonin and spermidine. There is often only very limited sequence conservation between members of the GNAT superfamily, in part, reflecting their capacity to bind a diverse array of substrates. In contrast, the secondary and tertiary structures are highly conserved, but then at the quaternary level there is further diversity, with GNATs shown to exist in monomeric, dimeric, or tetrameric states. Here we describe the X-ray crystallographic structure of a GNAT enzyme from Staphyloccocus aureus with only low sequence identity to previously solved GNAT proteins. It contains many of the classical GNAT motifs, but lacks other hallmarks of the GNAT fold including the classic β-bulge splayed at the β-sheet interface. The protein is likely to be a dimer in solution based on analysis of the asymmetric unit within the crystal structure, homology with related GNAT family members, and size exclusion chromatography. The study provides the first high resolution structure of this enzyme, providing a strong platform for substrate and cofactor modelling, and structural/functional comparisons within this diverse enzyme superfamily.     

Fourfold paralogy regions on human HOX-bearing chromosomes: Role of ancient segmental duplications in the evolution of vertebrate genome

BackgroundSusumu Ohno’s idea that modern vertebrates are degenerate polyploids (concept referred as 2R hypothesis) has been the subject of intense debate for past four decades. It was proposed that intra-genomic synteny regions (paralogons) in human genome are remains of ancient polyploidization events that occurred early in the vertebrate history. The quadruplicated paralogon centered on human HOX clusters is taken as evidence that human HOX-bearing chromosomes were structured by two rounds of whole genome duplication (WGD) events.ResultsEvolutionary history of human HOX-bearing chromosomes (chromosomes 2/7/12/17) was evaluated by the phylogenetic analysis of multigene families with triplicated or quadruplicated distribution on these chromosomes. Topology comparison approach categorized the members of 44 families into four distinct co-duplicated groups. Distinct gene families belonging to a particular co-duplicated group, exhibit similar evolutionary history and hence have duplicated simultaneously, whereas genes of two distinct co-duplicated groups do not share their evolutionary history and have not duplicated in concert with each other.ConclusionThe recovery of co-duplicated groups suggests that “ancient segmental duplications and rearrangements” is the most rational model of evolutionary events that have generated the triplicated and quadruplicated paralogy regions seen on the human HOX-bearing chromosomes.     

The phage P.E1 isolated from hospital sewage reduces the growth of Escherichia coli

This study involves partial characterisation of a lytic bacteriophage P.E₁ against a multi drug-resistant clinical isolate of Escherichia coli, isolated from hospital sewage supply. The phage P.E₁ has showed a narrow host range suitable for its use in phage therapy. Phage showed lytic activity up to 70°C and at alkaline conditions, but at higher acidic conditions its activity decreased. Latent period and burst size of P.E₁ estimated from single-step growth curve was 40 min and 185 plaque-forming units per cell, respectively. The phage P.E₁ reduced the growth of host bacteria during the initial 12?h of infection; however, the host bacteria developed resistance afterwards. During the 24-hour observation period, the bacteriophage could still reduce the growth of its host bacteria evident by lower optical density in the phage-treated samples compared with control. The phage genome was double-stranded DNA and larger than 12?kb in size. Further manipulations of genome and proteins may help to unveil the unique aspects of this phage, to use it in phage therapy against E. coli.     

A theoretical elucidation of bilirubin interaction with HSA's lysines: first electrostatic binding site in IIA subdomain

The electrostatic interaction of amino acid lysines 190, 195 and 199 of human serum albumin (HSA) with bilirubin have been investigated using molecular dynamic simulations, QM and QM/MM minimization methods. In this study two methodological approaches have been employed. In the first approach X-ray structure and the structure obtained from the molecular dynamic simulation of subdomain IIA of HSA in vacuum have been utilized. Interactions have been evaluated with the segment 186-200 of the cited subdomain. Calculations on the X-ray structure of above segment indicate an effective interaction of the lysine 195 with bilirubin, although that of the lysine 190 is also found considerable in this structure. Performing simulation in vacuum, it has been revealed that except for the lysine 195, the other two lysine residues (190 and 199) could not be considered as centers of interaction. Such finding, which is in accord with experimental data, lends support to the procedure employed in this study. NBO analyses suggest that tasks to achieve a structure indicating bilirubin interaction with the lysine 195 from the 186-200 segment extracted from X-ray structure, results in a structure that lacks any electrostatic interaction. In fact, it has been found that the stability of the latter species can be attributed to the H-bonding interaction of the glutamate 188 with both bilirubin and the lysine 195. Further NBO analysis on the structure of the same species, while achieved after molecular dynamic simulation on subdomain IIA in vacuum has revealed that a favorable electrostatic interaction between the lysine 195 and bilirubin has occurred. Besides, H-bonding interaction of the glutamate 188 with bilirubin has been evident in the same species. For the second approach, presence of water molecules and ions has been considered to simulate condensed medium. Applying docking, conformational sampling, and QM/MM minimization steps in sequence, a structure has been achieved which presents a specific interaction between epsilon-NH3(+) group of the lysine 195 residue and the lactam oxygen atom of bilirubin. NBO analyses suggest that above electrostatic interaction is combined with hydrogen bonding interaction between same two groups. Moreover, a hydrogen bond between oxygen atom of bilirubin's acetate group and alpha-NH group of lysine 195 has been observed. Molecular orbital calculations have been presented which support the NBO analyses.