Production of resistant starch from taro (Colocasia esculenta L. Schott) corm and determination of its effects on health by in vitro methods

The aim of the study was the production of resistant starch from taro (Colocasia esculenta L. Schott) corm and determination of its effects on health by in vitro methods. Starch was isolated from taro corms with 98% purity, and 10.4±0.5% amylose content. By application of heating, autoclaving, enzymatic debranching, retrogradation, and drying processes to taro starch for two times, resistant starch (RS) content was increased 16 fold (35.1±1.9%, dry basis). The expected glycemic index (eGI) of taro starch and taro resistant starch was determined as 60.6±0.5 and 51.9±0.9, respectively and the decrease in the glycemic index of taro resistant starch was found as statistically significant (P<0.05). The in vitro binding of bile acids by taro starch and taro resistant starch relative to cholesterol decreasing drug cholestyramine were 5.2±0.2% and 7.6±1.7%, respectively.     

Synthesis and in vitro behavior of β-TCP zirconia/polymeric biocomposites for bio-applications

Novel biocomposites were fabricated by impregnating β-tricalcium phosphate (β-TCP)/zirconia particles into the polymers matrix. The composite materials were characterized using thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR) analyzes and Scanning Electron Microscopy (SEM). The results confirmed the conversion of hydroxyapatite (HA) to β-TCP at a sintering temperature of 1150 °C with or without zirconia powder. The in vitro behavior was assessed via measurement of calcium and phosphorus ions in SBF (simulated body fluid). FT-IR and SEM of the composites were performed pre and post immersion in SBF. The results prove that the bone like apatite layer formation was enhanced on the β-TCP-Z20/polymeric composite surface more than that on the β-TCP-Z10/polymeric composite. Therefore, the data confirmed that zirconia plays an important role in the enhancement of the apatite formation. The conclusions proved that the β-TCP-Z20/polymeric biocomposites, containing 20% of zirconia, are promising for bone remodeling applications.     

COX-2 polymorphisms − 765G→C and − 1195A→G and hepatocellular carcinoma risk

Cyclooxygenase-2 (COX-2) is overexpressed in hepatocellular carcinoma (HCC) and considered to play a role in hepatic carcinogenesis. Our aim was to examine the associations between polymorphisms in COX-2 − 765G→C and − 1195A→G and risk of HCC. We conducted a case–control study including 120 patients with HCC and 130 age- and gender-matched controls. Genotypes of the COX-2 polymorphisms − 765G→C and − 1195A→G were determined by polymerase chain reaction-based restriction fragment length polymorphism. No significant difference was observed in the genotype distribution of the − 765G→C polymorphism between patients and controls. The − 1195AA genotype was associated with an increased risk of developing HCC (OR, 2.5; 95%CI, 1.18–5.37). The A allele was present significantly more often in HCC patients (OR 1.5; 95%CI, 1.05–2.14). In conclusion, our results demonstrated that the − 1195AA genotype and A allele have an important role in HCC risk in Egyptian patients.     

Enzymatic Engineering of Polysialic Acid on Cells in Vitro and in Vivo Using a Purified Bacterial Polysialyltransferase

In vertebrates, polysialic acid (PSA) is typically added to the neural cell adhesion molecule (NCAM) in the Golgi by PST or STX polysialyltransferase. PSA promotes plasticity, and its enhanced expression by viral delivery of the PST or STX gene has been shown to promote cellular processes that are useful for repair of the injured adult nervous system. Here we demonstrate a new strategy for PSA induction on cells involving addition of a purified polysialyltransferase from Neisseria meningitidis (PST_Nm) to the extracellular environment. In the presence of its donor substrate (CMP-Neu5Ac), PST_Nm synthesized PSA directly on surfaces of various cell types in culture, including Chinese hamster ovary cells, chicken DF1 fibroblasts, primary rat Schwann cells, and mouse embryonic stem cells. Similarly, injection of PST_Nm and donor in vivo was able to produce PSA in different adult brain regions, including the cerebral cortex, striatum, and spinal cord. PSA synthesis by PST_Nm requires the presence of the donor CMP-Neu5Ac, and the product could be degraded by the PSA-specific endoneuraminidase-N. Although PST_Nm was able to add PSA to NCAM, most of its product was attached to other cell surface proteins. Nevertheless, the PST_Nm-induced PSA displayed the ability to attenuate cell adhesion, promote neurite outgrowth, and enhance cell migration as has been reported for endogenous PSA-NCAM. Polysialylation by PST_Nm occurred in vivo in less than 2.5 h, persisted in tissues, and then decreased within a few weeks. Together these characteristics suggest that a PST_Nm-based approach may provide a valuable alternative to PST gene therapy.     

Life-cycle modification in open oceans accounts for genome variability in a cosmopolitan phytoplankton

Emiliania huxleyi is the most abundant calcifying plankton in modern oceans with substantial intraspecific genome variability and a biphasic life cycle involving sexual alternation between calcified 2N and flagellated 1N cells. We show that high genome content variability in Emiliania relates to erosion of 1N-specific genes and loss of the ability to form flagellated cells. Analysis of 185 E. huxleyi strains isolated from world oceans suggests that loss of flagella occurred independently in lineages inhabiting oligotrophic open oceans over short evolutionary timescales. This environmentally linked physiogenomic change suggests life cycling is not advantageous in very large/diluted populations experiencing low biotic pressure and low ecological variability. Gene loss did not appear to reflect pressure for genome streamlining in oligotrophic oceans as previously observed in picoplankton. Life-cycle modifications might be common in plankton and cause major functional variability to be hidden from traditional taxonomic or molecular markers.     

Conversion of xylose to ethanol by a novel phenol-tolerant strain of Enterobacteriaceae isolated from olive mill wastewater

A xylose-fermenting bacterium of the family Enterobacteriaceae was isolated from olive mill wastewater. It converted xylose to ethanol with a yield of 0.19 g ethanol g^–1 xylose. Although phenolic compounds normally inhibit pentose-utilizing microorganisms, this isolate was tolerant to phenol. Both the yield and the productivity of xylose fermentation decreased by 30% when phenol was added at a final concentration of 0.8 g phenol l^–1. Xylose (23 g l^–1) was totally fermented to ethanol (4.3 g l^–1) within 48 h in the absence of phenol; however, in the presence of 0.8 g phenol l^–1, only 3.3 g ethanol l^–1 was obtained from the same starting concentration of xylose after 70 h.     

Activation of Notch Signaling Is Required for Cholangiocarcinoma Progression and Is Enhanced by Inactivation of p53 In Vivo

Cholangiocacinoma (CC) is a cancer disease with rising incidence. Notch signaling has been shown to be deregulated in many cancers. However, the role of this signaling pathway in the carcinogenesis of CC is still not fully explored. In this study, we investigated the effects of Notch inhibition by γ-secretase inhibitor IX (GSI IX) in cultured human CC cell lines and we established a transgenic mouse model with liver specific expression of the intracellular domain of Notch (Notch-ICD) and inactivation of tumor suppressor p53. GSI IX treatment effectively impaired cell proliferation, migration, invasion, epithelial to mesenchymal transition and growth of softagar colonies. In vivo overexpression of Notch-ICD together with an inactivation of p53 significantly increased tumor burden and showed CC characteristics. Conclusion: Our study highlights the importance of Notch signaling in the tumorigenesis of CC and demonstrates that additional inactivation of p53 in vivo.     

RNF185 Is a Novel E3 Ligase of Endoplasmic Reticulum-associated Degradation (ERAD) That Targets Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)

In the endoplasmic reticulum (ER), misfolded or improperly assembled proteins are exported to the cytoplasm and degraded by the ubiquitin-proteasome pathway through a process called ER-associated degradation (ERAD). ER-associated E3 ligases, which coordinate substrate recognition, export, and proteasome targeting, are key components of ERAD. Cystic fibrosis transmembrane conductance regulator (CFTR) is one ERAD substrate targeted to co-translational degradation by the E3 ligase RNF5/RMA1. RNF185 is a RING domain-containing polypeptide homologous to RNF5. We show that RNF185 controls the stability of CFTR and of the CFTRΔF508 mutant in a RING- and proteasome-dependent manner but does not control that of other classical ERAD model substrates. Reciprocally, its silencing stabilizes CFTR proteins. Turnover analyses indicate that, as RNF5, RNF185 targets CFTR to co-translational degradation. Importantly, however, simultaneous depletion of RNF5 and RNF185 profoundly blocks CFTRΔF508 degradation not only during translation but also after synthesis is complete. Our data thus identify RNF185 and RNF5 as a novel E3 ligase module that is central to the control of CFTR degradation.