Investigation of Reported Aflatoxin Production by Fungi Outside the Aspergillus flavus Group

A screening study of 121 fungus isolates, representing 29 species, for aflatoxin synthesis demonstrated this property only in Aspergillus flavus and A. parasiticus. Eight of the organisms found negative were isolates reported by other investigators to produce aflatoxin. Since similar negative reports have come from several other workers, it is concluded that only the A. flavus group of Aspergillus can presently be certified as sources of these toxins. Reasons for possible false-positive findings are discussed along with precautionary measures and differential analytical procedures useful in aflatoxin screening studies.     

超氧化物歧化酶模拟化合物的生物活性研究

根据天然超氧化物歧化酶(SOD)活性部位结构合成了含苯并咪唑的5种配体及其32种分别含Cu（Ⅱ）、Fe（Ⅲ）、Mn（Ⅱ）、Co（Ⅱ）的模拟化合物.经光谱、电化学测试证明这些化合物具有拟S3D活性,其50％抑制率浓度（IC50）为10-6～10-8mol·L-1,催化超氧离子自由基（O-·2）歧化的反应速率常数kq为106～108mol-1·L·s-1.同时观察到几种模拟化合物有抗肿瘤活性或增强水稻抗寒性.     

Unique and selective mitogenic effects of vanadate on SV40-transformed cells

Vanadate and insulin both function as unique complete mitogens for SV40-transformed 3T3T cells, designated CSV3-1, but not for nontransformed 3T3T cells. The mitogenic effects induced by vanadate and insulin in CSV3-1 cells are mediated by different signaling mechanisms. For example, vanadate does not stimulate the tyrosine phosphorylation of the insulin receptor -subunit nor the 170 kDa insulin receptor substrate-1. Instead, vanadate induces a marked increase in tyrosine phosphorylation of 55 and 64 kDa proteins that is not observed in insulin-stimulated CSV3-1 cells. Perhaps most interestingly, vanadate-induced mitogenesis is associated with the selective induction ofc-jun andjunB expression without significantly inducingc-fos orc-myc. Furthermore, treatment of CSV3-1 cells with genistein abolishes the effects of vanadate on protein tyrosine phosphorylation andc-jun induction. These and related data suggest that modulation of protein tyrosine phosphorylation andc-jun andjunB expression may serve the critical roles in mediating vanadate-induced mitogenesis in SV40-transformed cells.     

Influence of transition metals added during sporulation on heat resistance of Clostridium botulinum 113B spores.

Sporulation of Clostridium botulinum 113B in a complex medium supplemented with certain transition metals (Fe, Mn, Cu, or Zn) at 0.01 to 1.0 mM gave spores that were increased two to sevenfold in their contents of the added metals. The contents of calcium, magnesium, and other metals in the purified spores were relatively unchanged. Inclusion of sodium citrate (3 g/liter) in the medium enhanced metal accumulation and gave consistency in the transition metal contents of independent spore crops. In citrate-supplemented media, C. botulinum formed spores with very high contents of Zn (approximately 1% of the dry weight). Spores containing an increased content of Fe (0.1 to 0.2%) were more susceptible to thermal killing than were native spores or spores containing increased Zn or Mn. The spores formed with added Fe or Cu also appeared less able to repair heat-induced injuries than the spores with added Mn or Zn. Fe-increased spores appeared to germinate and outgrow at a higher frequency than did native and Mn-increased spores. This study shows that C. botulinum spores can be sensitized to increased thermal destruction by incorporation of Fe in the spores.     

Piwi-Interacting RNAs (piRNAs) Are Dysregulated in Renal Cell Carcinoma and Associated with Tumor Metastasis and Cancer-Specific Survival

Piwi-interacting RNAs (piRNAs) are a distinct group of small noncoding RNAs (sncRNAs) that silence transposable genetic elements to protect genome integrity. Because of their limited expression in gonads and sequence diversity, piRNAs remain the most mysterious class of small RNAs. Studies have shown piRNAs are present in somatic cells and dysregulated in gastric, breast and liver cancers. By deep sequencing 24 frozen benign kidney and clear cell renal cell carcinoma (ccRCC) specimens and using the publically available piRNA database, we found 26,991 piRNAs present in human kidney tissue. Among 920 piRNAs that had at least two copies in one specimen, 19 were differentially expressed in benign kidney and ccRCC tissues, and 46 were associated with metastasis. Among the metastasis-related piRNAs, we found three piRNAs (piR-32051, piR-39894 and piR-43607) to be derived from the same piRNA cluster at chromosome 17. We confirmed the three selected piRNAs not to be miRNAs or miRNA-like sncRNAs. We further validated the aberrant expression of the three piRNAs in a 68-case formalin-fixed and paraffin-embedded (FFPE) ccRCC tissue cohort and showed the up-regulation of the three piRNAs to be highly associated with ccRCC metastasis, late clinical stage and poor cancer-specific survival.     

冰核细菌及冰核基因的应用研究进展

引起水由液态变为固态的物质称为冰核或成核剂。冰核种类繁多,目前已发现4属23种或变种的细菌、4属11种或变种的真菌和1种病毒,它们都具成冰活性。细菌冰核是一类蛋白质,也称冰蛋白,由细菌冰核基因编码。作为生物冰核领域的研究重点,冰核细菌的研究已涉及到促冻杀虫、防霜冻、植物病害等多个领域;同时冰核细菌已成功地应用于人工降雪、制冷和高敏检测等方面,具有广阔的应用前景。主要对冰核细菌的应用研究现状和发展进行综述。     

浙江省网蛾科昆虫简记

网蛾科Thyrididac昆虫是林区习见的一类害虫,本报道产于浙江的26种,其中笔采得15种,2种为中国新记录。8种为浙江省新记录,并首次报道了它们的发生期和11种网蛾的新寄主及寄生于6种网蛾的14种天敌昆虫。     

Epidermal growth factor improves intestinal morphology by stimulating proliferation and differentiation of enterocytes and mTOR signaling pathway in weaning piglets

Epidermal growth factor(EGF) has been shown to improve piglet intestinal morphology and epithelial recovery. In an attempt to further understand the mechanisms behind these improvements, this study tested the hypothesis that dietary EGF may affect intestinal morphology by stimulating the proliferation and differentiation of enterocytes in weaning piglets. In piglets receiving200 μg kg–1 EGF, crypt depth and villus height increased(P0.05). Adding 400 μg kg–1 EGF increased villus height-to-crypt depth ratio(P0.05), but reduced crypt depth(P0.05). Dietary supplementation with 200 μg kg–1 EGF significantly increased the number of Ki67-positive cells(P0.01) and tended to increase the mRNA level of proliferating cell nuclear antigen(P0.10).However, this supplementation decreased the expression level of intestinal fatty acid-binding protein(P0.05). Piglets fed with400 μg kg–1 EGF had an increased mRNA level of intestinal alkaline phosphatase(P0.05). The phosphorylation of m TOR(mammalian target of rapamycin) was observed in the 200 μg kg–1 EGF group. These results suggest that dietary supplementation with a low level of EGF improved piglet intestinal morphology through stimulating the proliferation and differentiation of enterocytes, and the mTOR signaling pathway may partly be involved in this process.     

Interaction of cyproheptadine hydrochloride with human serum albumin using spectroscopy and molecular modeling methods

The interaction between cyproheptadine hydrochloride (CYP) and human serum albumin (HSA) was investigated by fluorescence spectroscopy, UV–vis absorption spectroscopy, Fourier transform infrared spectroscopy (FT‐IR) and molecular modeling at a physiological pH (7.40). Fluorescence of HSA was quenched remarkably by CYP and the quenching mechanism was considered as static quenching since it formed a complex. The association constants K_a and number of binding sites n were calculated at different temperatures. According to Förster's theory of non‐radiation energy transfer, the distance r between donor (human serum albumin) and acceptor (cyproheptadine hydrochloride) was obtained. The effect of common ions on the binding constant was also investigated. The effect of CYP on the conformation of HSA was analyzed using FT‐IR, synchronous fluorescence spectroscopy and 3D fluorescence spectra. The thermodynamic parameters ΔH and ΔS were calculated to be ?14.37 kJ mol^?1 and 38.03 J mol^?1 K^?1, respectively, which suggested that hydrophobic forces played a major role in stabilizing the HSA‐CYP complex. In addition, examination of molecular modeling indicated that CYP could bind to site I of HSA and that hydrophobic interaction was the major acting force, which was in agreement with binding mode studies. Copyright © 2012 John Wiley & Sons, Ltd.     

Combined multispectroscopic and molecular docking investigation on the interaction between strictosamide and human serum albumin

The interaction between strictosamide (STM) and human serum albumin (HSA) was investigated by fluorescence spectroscopy, synchronous fluorescence spectroscopy, three‐dimensional fluorescence spectroscopy, ultraviolet‐visible absorption spectroscopy, circular dichroism spectroscopy and molecular modeling under physiological pH 7.4. STM effectively quenched the intrinsic fluorescence of HSA via static quenching. The binding site number n and apparent binding constant K_a were determined at different temperatures by fluorescence quenching. The thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS) for the reaction were calculated as ?3.01 kJ/mol and 77.75 J/mol per K, respectively, which suggested that the hydrophobic force played major roles in stabilizing the HSA–STM complex. The distance r between donor and acceptor was obtained to be 4.10 nm according to Förster's theory. After the addition of STM, the synchronous fluorescence and three‐dimensional fluorescence spectral results showed that the hydrophobicity of amino acid residues increased and the circular dichroism spectral results showed that the α‐helix content of HSA decreased (from 61.48% to 57.73%). These revealed that the microenvironment and conformation of HSA were changed in the binding reaction. Furthermore, the study of molecular modeling indicated that STM could bind to site I of HSA and the hydrophobic interaction was the major acting force, which was in agreement with the binding mode study. Copyright © 2013 John Wiley & Sons, Ltd.