Methylenetetrahydrofolate reductase C677T variant in Moroccan patients with inflammatory bowel disease

Background

The association of genetic polymorphisms related to metabolism of homocysteine and folate with inflammatory bowel disease has been evidenced. Several studies have identified genetic variants of MTHFR as significant susceptibility loci for Crohn's disease (CD) and ulcerative colitis (UC). The C677T genetic polymorphism in the MTHFR gene is found to be associated with a thermolabile variant enzyme that shows a reduced activity. Therefore, we investigated whether the C677T variant confers genetic susceptibility to CD or UC and evaluated the genotype–phenotype associations in the Moroccan population.

Methods

The present study included 96 inflammatory bowel disease patients (68 patients with CD and 28 with UC) and 182 healthy controls. DNA samples were genotyped for the MTHFR (C677T) mutation by the PCR-RFLP method. Statistical analyzes were performed using MedCalc software, Chi square test and Fisher test.

Results

The respective odds ratio for CD, UC and control group were, 1.55 (CI 95%: 0.53–4.53, P = 0.52); 0.50 (CI 95%: 0.06–4.15, P = 0.52) and 0.50 (CI 95%: 0.06–4.15, P = 0.52). Thus, no statistically significant association with the disease was observed in frequency of the TT variant in comparison to healthy controls. Stratification of IBD patients on the basis of CD or UC showed that individuals carrying at least one T allele are not protected against Crohn's disease. Furthermore, clinical features of the disease did not show any significant association.

Conclusion

In conclusion, the present study indicates that the genetic risk for IBD is not modulated by MTHFR C677T polymorphism in Moroccan population.     

Molecular characterization of major and minor rDNA repeats and genetic variability assessment in different species of mahseer found in North India

Relationship among the mahseer species (Family: Cyprinidae) has long been debated in fish systematics. Present study concentrates on the nature of the phylogenetic relationship among the five mahseer species using the sequence of major ribosomal DNA (45S rDNA). We have covered rDNA sequence of approximately 5.2 kb per individual, 26.0 kb per species and 130.0 kb as a whole. We also characterized the 45S and 5S rDNA regions with respect to their nucleotide composition. For phylogenetic analyses, nucleotide sequences were divided into four datasets. First and second datasets contained 18S rDNA and ITS1 sequence, whereas third and fourth datasets consisted of ITS2 and complete 18S-ITS1-5.8S-ITS2-28S, respectively. The NJ tree was constructed for all the datasets. The mahseer species under study formed a monophyletic group well separated from the outgroup species. Similarly, the individuals of Neolissochilus hexagonolepis form monophyletic group with Tor species, indicating Neolissochilus as a sister genus of Tor. The findings from the present study provide greater insights into taxonomic status of mahseer, and set the stage for future investigations dealing with phylo-geography, taxonomy, conservation and co-evolution within this interesting and important group of fish.     

Sulfation pattern of the fucose branch is important for the anticoagulant and antithrombotic activities of fucosylated chondroitin sulfates

Background

The aim is to compare the structures, anticoagulant and antithrombotic activities of two fucosylated chondroitin sulfates isolated from sea cucumbers Isostichopus badionotus (fCS-Ib) and Pearsonothuria graeffei (fCS-Pg), which were known to have different sulfation patterns on the fucose branches.

Methods

The structures of fCSs were identified using 2D NMR. Anticoagulant activities were measured by activated partial thromboplastin time (APTT) and thrombin time (TT), and inhibition of factors IIa, Xa and XIIa was assessed in vitro. Antithrombotic activity was determined ex vivo by measuring the length and weight of the thrombus generated.

Results

The two fCSs had identical chondroitin sulfate E backbones and similar fucose branches, but different sulfation patterns of the fucose branches. The fucose branch in fCS-Ib was mainly 2,4-O-sulfated whereas that in fCS-Pg was mainly 3,4-O-sulfated. In vitro assay indicated that fCS-Pg possessed much lower potency than fCS-Ib in prolonging APTT/TT and in inhibition of thrombin. However, they both exhibited similar inhibitory effects on factor X activation by intrinsic tenase complex, and on thrombus generation. Furthermore, both fCSs significantly activated factor XII, which has been proved to be associated with adverse clinical events associated with heparin contaminated by oversulfated chondroitin sulfate.

Conclusion

The 2,4-O-sulfated fucose branch is the key structural factor of fCSs for prolonged APTT/TT and inhibition of thrombin, whereas the inhibitory effect of fCSs on factor X, XII activation and thrombus generation was attributed to the overall structure of fCS polysaccharide.

General importance

Both fCSs have well defined structures and can be readily quality-controlled, and therefore may be potential alternatives for heparin as anticoagulant and antithrombotic drugs.     

Crystal structure of the human carboxypeptidase N (kininase I) catalytic domain

Human carboxypeptidase N (CPN), a member of the CPN/E subfamily of "regulatory" metallo-carboxypeptidases, is an extracellular glycoprotein synthesized in the liver and secreted into the blood, where it controls the activity of vasoactive peptide hormones, growth factors and cytokines by specifically removing C-terminal basic residues. Normally, CPN circulates in blood plasma as a hetero-tetramer consisting of two 83 kDa (CPN2) domains each flanked by a 48 to 55 kDa catalytic (CPN1) domain. We have prepared and crystallized the recombinant C-terminally truncated catalytic domain of human CPN1, and have determined and refined its 2.1 A crystal structure. The structural analysis reveals that CPN1 has a pear-like shape, consisting of a 319 residue N-terminal catalytic domain and an abutting, cylindrically shaped 79 residue C-terminal beta-sandwich transthyretin (TT) domain, more resembling CPD-2 than CPM. Like these other CPN/E members, two surface loops surrounding the active-site groove restrict access to the catalytic center, offering an explanation for why some larger protein carboxypeptidase inhibitors do not inhibit CPN. Modeling of the Pro-Phe-Arg C-terminal end of the natural substrate bradykinin into the active site shows that the S1' pocket of CPN1 might better accommodate P1'-Lys than Arg residues, in agreement with CPN's preference for cleaving off C-terminal Lys residues. Three Thr residues at the distal TT edge of CPN1 are O-linked to N-acetyl glucosamine sugars; equivalent sites in the membrane-anchored CPM are occupied by basic residues probably involved in membrane interaction. In tetrameric CPN, each CPN1 subunit might interact with the central leucine-rich repeat tandem of the cognate CPN2 subunit via a unique hydrophobic surface patch wrapping around the catalytic domain-TT interface, exposing the two active centers.     

AG490对甲状腺髓样癌TT细胞放射敏感性的影响

为了研究AG490对甲状腺髓样癌TT细胞放射敏感性,本研究选择甲状腺髓样癌TT细胞作为研究对象,并采用不同浓度AG490 (0, 25μmol/L, 50μmol/L, 100μmol/L)处理细胞,利用MTT法、流式细胞术和克隆形成实验分别对细胞增殖、凋亡及放射敏感性进行检测,并采用Western blotting法检测各组JAK2、p-STAT3、Bcl-2、Bax蛋白表达。结果表明,与A组相比,B、C、D组的抑制增殖作用增强,呈浓度和时间依赖性;随着AG490药物浓度的增加凋亡率逐渐增加;与A组相比,C组细胞存活分数显著降低;JAK2、p-STAT3和Bcl-2的蛋白表达量随着药物浓度的升高而逐渐降低,Bax蛋白表达量随着药物浓度的升高而逐渐增加。AG490对甲状腺髓样癌TT细胞增殖有抑制作用,可促进细胞凋亡,提高放射敏感性。     

Digesta passage and fiber digestibility in captive white-faced sakis (Pithecia pithecia)

Wild white-faced sakis (Pithecia pithecia) ingest primarily seeds that provide a diet that is lipid-rich and moderately high in dietary fiber. Although little anatomical information is available on sakis, evidence from other vertebrate seed predators suggests that such a diet is correlated with adaptations in gut morphology or physiology. Milton [1984] reported a 20 hr transit time (TT=transit time or time of first appearance in feces) of a particulate marker for a single monk saki (Pithecia monachus). This suggests that TT for Pithecia sakis may be four to five times longer than what has been reported for soft-fruit-eating platyrrhines, such as Ateles and Cebus. During a captive study, we calculated an average TT of 14.7+/-0.4 hr (n=5 trials started in the evening) for a chromic oxide (Cr(2)O(3)) marker that follows liquid digesta and TTs of 14.5 hr (trial started the previous evening) and 23.0 hr (trial started the previous morning) for two trials using particulate markers. Mean retention time (MRT) for the liquid marker ranged from 15.3 hr to 37.7 hr in four trials that lasted longer than 90 hr. Marker recovery was incomplete for the particulate markers in these trials, and thus MRT could only be determined for the liquid phase marker. Three 5-day trials on a low-fiber, blended diet revealed high fiber fraction digestibilities (neutral detergent fiber (NDF)=77.4% and acid detergent fiber (ADF)=74.4%). Data collected for this study and nutritional data from wild sakis suggest that pitheciin seed predators may have a potential for fiber digestibility that is intermediate between ripe-pulp frugivores and folivores.     

Sequence Structure of Hidden 10.4-base Repeat in the Nucleosomes of C. elegans

Abstract

By measuring prevailing distances between YY, YR, RR, and RY dinucleotides in the large database of the nucleosome DNA fragments from C. elegans, the consensus sequence structure of the nucleosome DNA repeat of C. elegans was reconstructed: (YYYYYRRRRR)_n. An actual period was estimated to be 10.4 bases. The pattern is fully consistent with the nucleosome DNA patterns of other eukaryotes, as established earlier, and, thus, the YYYYYRRRRR repeat can be considered as consensus nucleosome DNA sequence repeat across eukaryotic species. Similar distance analysis for [A, T] dinucleotides suggested the related pattern (TTTYTARAAA)_n where the TT and AA dinucleotides display rather out of phase behavior, contrary to the “AA or TT” in-phase periodicity, considered in some publications. A weak 5-base periodicity in the distribution of TA dinucleotides was detected.     

福氏2a痢疾杆菌O—特异性多糖与破伤风类毒素结合疫苗的制备及其免疫学特性

通过己二酸二肼（ADH）将福氏2a痢疾杆菌脂多糖（LPS）经酸水解脱毒纯化后得到的O－SP和破伤风类毒素（TT）蛋白共价结合,制备了福氏2a痢疾杆菌结合物。以2.5μg多糖或含2.5μg多糖的结合物经皮下注射免疫NIH品系雌性小鼠,同时以25μg多糖或含25μg多糖的结合物经耳缘静脉注射家兔。用ELISA方法分别检测小鼠和家兔血清中抗脂多糖抗体水平及抗TT水平,并用豚鼠血清补体介导进行了体外杀菌实验。结果显示：用本实验方法提取的多糖,合成的多糖衍生物,多糖－蛋白结合物都具有福氏2a痢疾杆菌O－抗原特异性,其化学组成及结构特异性和国外文献报道基本一致。单独用多糖免疫小鼠和家兔未能诱导LPS抗体,而结合物免疫小鼠和家兔的血清诱导出了较高的抗LPS IgG抗体及抗TT抗体,并有较强的体外杀菌活性。产生的抗体存在着免疫记忆性,可以产生再次免疫应答加强反应。     

Crystal structure of the conserved protein TT1542 from Thermus thermophilus HB8

The TT1542 protein from Thermus thermophilus HB8 is annotated as a conserved hypothetical protein, and belongs to the DUF158 family in the Pfam database. A BLAST search revealed that homologs of TT1542 are present in a wide range of organisms. The TT1542 homologs in eukaryotes, PIG-L in mammals, and GPI12 in yeast and protozoa, have N-acetylglucosaminylphosphatidylinositol (GlcNAc-PI) de-N-acetylase activity. Although most of the homologs in prokaryotes are hypothetical and have no known function, Rv1082 and Rv1170 from Mycobacterium tuberculosis are enzymes involved in the mycothiol detoxification pathway. Here we report the crystal structure of the TT1542 protein at 2.0 A resolution, which represents the first structure for this superfamily of proteins. The structure of the TT1542 monomer consists of a twisted beta-sheet composed of six parallel beta-strands and one antiparallel beta-strand (with the strand order 3-2-1-4-5-7-6) sandwiched between six alpha-helices. The N-terminal five beta-strands and four alpha-helices form an incomplete Rossmann fold-like structure. The structure shares some similarity to the sugar-processing enzymes with Rossmann fold-like domains, especially those of the GPGTF (glycogen phosphorylase/glycosyl transferase) superfamily, and also to the NAD(P)-binding Rossmann fold domains. TT1542 is a homohexamer in the crystal and in solution, the six monomers forming a cylindrical structure. Putative active sites are suggested by the structure and conserved amino acid residues.