Effects of glycyrrhizin, stevioside, and sucralose on the growth and metabolism of the omnipresent gut commensal Escherichia coli

The rise in popularity of non-caloric sweeteners (NCS) among obese and diabetic patients is due to their ability to provide a sweet taste without any caloric input. However, NCS consumption may be linked to metabolic disorders. The mechanisms behind these adverse effects are still unclear, which suggests that NCS may alter the metabolic activity of the gut ICLE microbiome, leading to enteric environmental perturbation and resulting in physiological anomalies in the host. This study investigates how Escherichia coli, a common gut microbe, reacts to three NCS, two of which come from nature (glycyrrhizin and stevioside) and one that is made artificially (sucralose). To assess the impact of these NCS, this study investigated the growth, gene expression, and metabolic pathways of E. coli under different sweetener loads. Compared to the untreated control, low amounts of glycyrrhizin made E. coli grow faster, while similar amounts of sucralose and stevioside had no or a less noticeable effect. At higher concentrations, these sweeteners slowed down or inhibited the growth of the bacteria. Thus, NCS may have dose-dependent impacts on gut microbes. After treatment with amounts that corresponded to the acceptable daily intake, the expression of key metabolic genes showed altered expression, which may potentially affect their metabolism. At different concentrations of the NCS, there were clear differences in the global metabolomic profile between the control and the different NCS treatments. Under in vitro conditions, glycyrrhizin and sucralose appeared to have a less divergent impact on E. coli growth, gene expression, and metabolism, which may suggest that these are relatively safer sugar substitutes for humans

Effects of glycyrrhizin, stevioside, and sucralose on the growth and metabolism of the omnipresent gut commensal Escherichia coli

The rise in popularity of non-caloric sweeteners (NCS) among obese and diabetic patients is due to their ability to provide a sweet taste without any caloric input. However, NCS consumption may be linked to metabolic disorders. The mechanisms behind these adverse effects are still unclear, which suggests that NCS may alter the metabolic activity of the gut ICLE microbiome, leading to enteric environmental perturbation and resulting in physiological anomalies in the host. This study investigates how Escherichia coli, a common gut microbe, reacts to three NCS, two of which come from nature (glycyrrhizin and stevioside) and one that is made artificially (sucralose). To assess the impact of these NCS, this study investigated the growth, gene expression, and metabolic pathways of E. coli under different sweetener loads. Compared to the untreated control, low amounts of glycyrrhizin made E. coli grow faster, while similar amounts of sucralose and stevioside had no or a less noticeable effect. At higher concentrations, these sweeteners slowed down or inhibited the growth of the bacteria. Thus, NCS may have dose-dependent impacts on gut microbes. After treatment with amounts that corresponded to the acceptable daily intake, the expression of key metabolic genes showed altered expression, which may potentially affect their metabolism. At different concentrations of the NCS, there were clear differences in the global metabolomic profile between the control and the different NCS treatments. Under in vitro conditions, glycyrrhizin and sucralose appeared to have a less divergent impact on E. coli growth, gene expression, and metabolism, which may suggest that these are relatively safer sugar substitutes for humans

Genetic diversity of native and introduced populations of the invasive house crow (Corvus splendens) in Asia and Africa

The common house crow (Corvus splendens) is one of the best known and most wide spread species of the family Corvidae. It is a successful invasive species able to exploit urban environments, well removed from its natural distribution. It is considered a pest as it attains high population densities, can cause serious economic losses and has many adverse effects on native fauna and flora, including predation, competitive displacement and disease transmission. Little genetic research on the house crow has been undertaken so we have only a limited understanding of its natural genetic population structure and invasion history. In this study, we employ microsatellite and mitochondrial DNA markers to assess genetic diversity, phylogeography and population structure of C. splendens within its native range represented by Sri Lanka and Bangladesh and introduced range represented by Malaysia, Singapore, Kenya and South Africa. We found high levels of genetic diversity in some of the invasive populations for which multiple invasions are proposed. The lowest genetic diversity was found for the intentionally introduced population in Selangor, Malaysia. Sri Lanka is a possible source population for Malaysia Selangor consistent with a documented introduction over 100 years ago, with port cities within the introduced range revealing possible presence of migrants from other unsampled locations. We demonstrate the power of the approach of using multiple molecular markers to untangle patterns of invasion, provide insights into population structure and phylogeographic relationships and illustrate how historical processes may have contributed to making this species such a successful invader

Investigation of the impact of nonsynonymous mutations on thyroid peroxidase dimer.

Congenital hypothyroidism is one of the most common preventable endocrine disorders associated with thyroid dysgenesis or dyshormonogenesis. Thyroid peroxidase (TPO) gene defect is mainly responsible for dyshormonogenesis; a defect in the thyroid hormone biosynthesis pathway. In Bangladesh, there is limited data regarding the genetic etiology of Congenital Hypothyroidism (CH). The present study investigates the impact of the detected mutations (p.Ala373Ser, and p.Thr725Pro) on the TPO dimer protein. We have performed sequential molecular docking of H2O2 and I- ligands with both monomers of TPO dimer to understand the iodination process in thyroid hormone biosynthesis. Understanding homodimer interactions at the atomic level is a critical challenge to elucidate their biological mechanisms of action. The docking results reveal that mutations in the dimer severely disrupt its catalytic interaction with essential ligands. Molecular dynamics simulation has been performed to validate the docking results, thus realizing the consequence of the mutation in the biological system's mimic. The dynamics results expose that mutations destabilize the TPO dimer protein. Finally, principal component analysis exhibits structural and energy profile discrepancies in wild-type and mutant dimers. The findings of this study highlight that the mutations in TPO protein can critically affect the dimer structure and loss of enzymatic activity is persistent. Other factors also might influence the hormone synthesis pathway, which is under investigation

Impaired acylcarnitine profile in transfusion-dependent beta-thalassemia major patients in Bangladesh

Patients with beta-thalassemia major (BTM) suffer from fatigue, poor physical fitness, muscle weakness, lethargy, and cardiac complications which are related to an energy crisis. Carnitine and acylcarnitine derivatives play important roles in fatty acid oxidation, and deregulation of carnitine and acylcarnitine metabolism may lead to an energy crisis. The present study aimed to investigate carnitine and acylcarnitine metabolites to gain an insight into the pathophysiology of BTM. Dried blood spots of 45 patients with BTM and 96 age-matched healthy controls were analyzed for free carnitine and 24 acylcarnitines by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Although medium chain acylcarnitine levels were similar in the patients with BTM and healthy controls, free carnitine, short chain acylcarnitines, long chain acylcarnitines, and total acylcarnitine levels were significantly lower in patients with BTM than in the healthy controls (P < 0.05). Moreover, an impaired fatty acid oxidation rate was observed in the patients with BTM, as manifested by decreased fatty acid oxidation indicator ratios, namely C2/C0 and (C2 + C3)/C0. Furthermore, an increase in the C0/(C16 + C18) ratio indicated reduced carnitine palmitoyltransferase-1 (CPT-1) activity in the patients with BTM compared with that in the healthy controls. Thus, a low level of free carnitine and acylcarnitines together with impaired CPT-1 activity contribute to energy crisis-related complications in the patients with BTM. Keywords: Beta-thalassemia major, Carnitine-acylcarnitine levels, Impairment in fatty acid oxidation, Carnitine Palmitoyltransferase-1 activit

High resolution melting curve analysis enables rapid and reliable detection of G6PD variants in heterozygous females

Abstract Background Like glucose-6-phosphate dehydrogenase (G6PD) deficient hemizygous males and homozygous females, heterozygous females could also manifest hemolytic crisis, neonatal hyperbilirubinemia or kernicterus upon exposure to oxidative stress induced by certain foods such as fava beans, drugs or infections. Although hemizygous males and homozygous females are easily detected by conventional G6PD enzyme assay method, the heterozygous state could be missed by the conventional methods as the mosaic population of both normal and deficient RBCs circulates in the blood. Thus the present study aimed to apply high resolution melting (HRM) curve analysis approach to see whether HRM could be used as a supplemental approach to increase the chance of detection of G6PD heterozygosity. Results Sixty-three clinically suspected females were evaluated for G6PD status using both enzyme assay and HRM analysis. Four out of sixty-three participants came out as G6PD deficient by the enzyme assay method, whereas HRM approach could identify nine participants with G6PD variants, one homozygous and eight heterozygous. Although only three out of eight heterozygous samples had G6PD enzyme deficiency, the HRM-based heterozygous G6PD variants detection for the rest of the samples with normal G6PD enzyme activities could have significance because their newborns might fall victim to serious consequences under certain oxidative stress. Conclusions In addition to the G6PD enzyme assay, HRM curve analysis could be useful as a supplemental approach for detection of G6PD heterozygosity

High resolution melting curve analysis targeting the HBB gene mutational hot-spot offers a reliable screening approach for all common as well as most of the rare beta-globin gene mutations in Bangladesh

Abstract Background Bangladesh lies in the global thalassemia belt, which has a defined mutational hot-spot in the beta-globin gene. The high carrier frequencies of beta-thalassemia trait and hemoglobin E-trait in Bangladesh necessitate a reliable DNA-based carrier screening approach that could supplement the use of hematological and electrophoretic indices to overcome the barriers of carrier screening. With this view in mind, the study aimed to establish a high resolution melting (HRM) curve-based rapid and reliable mutation screening method targeting the mutational hot-spot of South Asian and Southeast Asian countries that encompasses exon-1 (c.1 - c.92), intron-1 (c.92 + 1 - c.92 + 130) and a portion of exon-2 (c.93 - c.217) of the HBB gene which harbors more than 95% of mutant alleles responsible for beta-thalassemia in Bangladesh. Results Our HRM approach could successfully differentiate ten beta-globin gene mutations, namely c.79G > A, c.92 + 5G > C, c.126_129delCTTT, c.27_28insG, c.46delT, c.47G > A, c.92G > C, c.92 + 130G > C, c.126delC and c.135delC in heterozygous states from the wild type alleles, implying the significance of the approach for carrier screening as the first three of these mutations account for ~85% of total mutant alleles in Bangladesh. Moreover, different combinations of compound heterozygous mutations were found to generate melt curves that were distinct from the wild type alleles and from one another. Based on the findings, sixteen reference samples were run in parallel to 41 unknown specimens to perform direct genotyping of the beta-thalassemia specimens using HRM. The HRM-based genotyping of the unknown specimens showed 100% consistency with the sequencing result. Conclusions Targeting the mutational hot-spot, the HRM approach could be successfully applied for screening of beta-thalassemia carriers in Bangladesh as well as in other countries of South Asia and Southeast Asia. The approach could be a useful supplement of hematological and electrophortic indices in order to avoid false positive and false negative results