Genotoxicity of heated cooking oil vapors.

Epidemiological studies of lung cancer in Chinese women indicated that factors other than cigarette smoking are related to lung cancer risk. A case-control study suggested that indoor air pollution, particularly from cooking oil emissions, may be involved. Condensates of volatile emissions from rapeseed and soybean cooking oils were prepared and found to be genotoxic in short-term tests including the Salmonella mutation assay, SV50 forward-mutation assay, and sister-chromatid exchange assay, as well as the micronucleus assay in mouse bone marrow. In contrast, condensates from rapeseed oil with butylated hydroxyanisole or hydrogenated rapeseed oil were not mutagenic, implicating oxidation products as the cause for mutagenicity. Peanut oil and lard condensates were not mutagenic in any assay. The association of exposure to Chinese rapeseed cooking-oil emissions and lung-cancer risk may be related to the mutagenic component of these condensates.     

Agrin induces phosphorylation of the nicotinic acetylcholine receptor.

Agrin causes acetylcholine receptors (AChRs) on chick myotubes in culture to aggregate, forming specializations that resemble the postsynaptic apparatus at the vertebrate skeletal neuromuscular junction. Here we report that treating chick myotubes with agrin caused an increase in phosphorylation of the AChR beta, gamma, and delta subunits. H-7, a potent inhibitor of several protein serine kinases, blocked agrin-induced phosphorylation of the gamma and delta subunits, but did not prevent either agrin-induced AChR aggregation or phosphorylation of the beta subunit. Experiments with anti-phosphotyrosine antibodies demonstrated that agrin caused an increase in tyrosine phosphorylation of the beta subunit that began within 30 min of adding agrin to the myotube cultures, reached a plateau by 3 hr, and was blocked by treatments known to block agrin-induced AChR aggregation. Anti-phosphotyrosine antibodies labeled agrin-induced specializations as they do the postsynaptic apparatus. These results suggest that agrin-induced tyrosine phosphorylation of the beta subunit may play a role in regulating AChR distribution.     

Oleosin KD 18 on the surface of oil bodies in maize. Genomic and cDNA sequences and the deduced protein structure

Oleosins are newly discovered, abundant, and small Mr hydrophobic proteins localized on the surface of oil bodies in diverse seeds. So far, most of the studies have been on the general characteristics of the proteins, and only one protein (maize KD 16) has been studied using a cDNA clone containing an incomplete coding sequence. Here, we report the sequences of a genomic clone and a cDNA clone of a new maize oleosin (KD 18). There is no intron in the gene. The 5'-flanking region contains potential regulatory elements including RY repeats, CACA consensus, and CATC boxes, which are presumably involved in the specific expression of the proteins in maturing seeds. The deduced amino acid sequence was analyzed for secondary structures. We suggest that KD 18 of 187-amino acid residues contains three major structural domains: a largely hydrophilic domain at the N terminus, a hydrophobic hairpin alpha-helical domain at the center, and an amphipathic alpha-helix domain at the C terminus. These structural domains are very similar to those of oleosin KD 16. However, the KD 18 and KD 16 amino acid sequences as well as nucleotide sequences are highly similar only at the central domain (72 and 71%, respectively). The similarities are highest at the loop region of the alpha-helical hairpin. These results suggest that KD 18 and KD 16 are isoforms, encoded by genes derived from a common ancestor gene. We propose that the hairpin domain acts as an indispensible internal signal for intracellular trafficking of oleosins during protein synthesis as well as an anchor for oleosins on the oil bodies. The other two domains can undergo relatively massive amino acid substitutions without impairing the structure/function of the oleosins or have evolved to generate oleosins having different functions.     

ABC转运蛋白及其在合成生物学中的应用

ABC转运蛋白(ATP-binding cassette transporter,ABC transporter)作为一种超大膜转运蛋白家族,在大多数生物体中发挥着重要作用。文中从结构特征、转运机制以及生理功能等方面论述了ABC转运蛋白的研究进展,进而着重综述了近些年来ABC转运蛋白在合成生物学领域中的应用,并为今后进一步的研究提出了展望,希望为扩展其应用提供指导。     

Reconstruction of Surface Porous PEEK Decorated with Strontium-doped Calcium Phosphate Coatings for Enhancing Osteogenic Activity

The aim of this study was to reconstruct surface porous structure with hundreds of micrometers and then bio-mineralize Sr-doped Calcium Phosphate(Sr-doped CaP)o...     

陕西食源性沙门氏菌耐药及相关基因

【目的】研究食源性沙门氏菌对常用抗生素的药敏性及相关耐药基因,更好的了解耐药性的产生和传播途径,确保食品安全。【方法】使用the Clinical and Laboratory Standards Institute推荐的琼脂稀释法测定沙门氏菌的药敏性,PCR和基因序列测定方法确定耐药沙门氏菌中整合子及其携带的耐药基因、与头孢菌素抗性相关的基因、沙门氏菌基因岛及与氟喹诺酮类抗生素耐药相关的基因突变。【结果】359株沙门氏菌中,67%的菌株对磺胺甲恶唑产生抗性,对甲氧苄啶/磺胺甲恶唑、四环素、卡那霉素、萘啶酮酸、氨苄西林、阿莫西林/克拉维酸、链霉素、氯霉素和庆大霉素、环丙沙星、头孢曲松、头孢西丁和头孢哌酮的耐药率分别为58%、56%、37%、35%、33%、32%、29%、26%、21%、16%、9%和8%。284株耐药菌中,79%的菌株可抗至少1种抗生素,25.9%可抗10种以上抗生素,2.5%可抗14种抗生素。耐药的Ⅰ类整合子以1.4kb最为常见,携带的耐药基因有aadA1、aadA2、aadA5、tetR、blaPSE-1、blaDHA-1、blaVEB-1、dhfrⅠ、dhfrⅤ、dhfrⅦ和dhfr17等。62株耐头孢曲松和/或头孢哌酮的沙门氏菌中,blaTEM和blaCMY-2基因的检出率分别为51.6%和56.5%。13.6%的沙门氏菌中检出了沙门氏菌基因岛。35株耐氟喹诺酮类抗生素的沙门氏菌的gyrA、parC和parE基因中共检出68个点突变,gyrA基因中常见突变为Ser83Phe、Ser83Tyr、Asp87Gly和Asp87Asn,parC基因中为Ser80Arg。parE基因中检出了Lys441Ile、Lys428Gln、Asp494Asn、Lys428Gln和Gly442Ser突变,这些点突变均为首次在食源性沙门氏菌中检出。【结论】陕西食源性沙门氏菌耐药状况严重,整合子、沙门氏菌基因岛和β-内酰胺酶编码基因的存在及解旋酶和拓扑异构酶基因突变是导致沙门氏菌耐药的重要机制。     

A 3.1-kb genomic fragment of Bacillus subtilis encodes the protein inhibiting growth of Xanthomonas oryzae pv. oryzae

AIMS: To clone genes of Bacillus subtilis encoding peptides that inhibit the growth of Xanthomonas orzae pv. oryzae (Xoo). METHODS AND RESULTS: A 3.1-kb DNA fragment from B. subtilis SO113 encoding peptides that inhibit the growth of Xoo (anti-Xoo, showing an inhibition zone) was isolated from a plasmid library of B. subtilis 6 GM15. Sequence analysis revealed that it contained three complete open reading frames (ORFs): ybcO, ybcS and a novel ORF designated ybcPQ. Deleting the last 96 bp of ybcS from the plasmid eliminated the anti-Xoo activity, suggesting that ybcS is required for producing the anti-Xoo activity. However, no anti-Xoo activity could be detected for the plasmid with ybcS alone. Further analysis showed that ybcO, at least, was also required to obtain the anti-Xoo activity. CONCLUSIONS: A fragment of B. subtilis has been cloned that expresses an anti-Xoo activity that requires ybcS and ybcO. SIGNIFICANCE AND IMPACT OF THE STUDY: These genes could be useful for the genetic engineering of resistance to rice bacterial diseases and for the design of new anti-Xoo biocontrol agents.     

单细胞RNA测序技术在病毒研究中的应用

单细胞RNA测序(single-cell RNA sequencing, scRNA-seq)技术已经成为不同领域中研究细胞异质性的有效工具。在病毒研究领域中,利用该技术分析病毒和细胞的转录组,可以在单细胞水平上检测病毒感染的动态变化,了解病毒与细胞间复杂的相互作用。本文简述了scRNA-seq技术,着重介绍病毒感染宿主细胞后scRNA-seq研究的最新进展,同时也描述了细胞周期、基因表达、细胞状态等细胞异质性对病毒感染过程的影响,以及病毒变异对其本身感染过程的影响。此外,本文还分析了scRNA-seq在研究病毒–宿主互作动态变化方面具有的独特优势,及其在病毒研究领域中广阔的应用前景,为揭示病毒的感染与致病机制、抗病毒靶标的开发等提供参考。     

Diversity and structure of the archaeal community in the leachate of a full-scale recirculating landfill as examined by direct 16S rRNA gene sequence retrieval

The diversity and structure of the archaeal community in the effluent leachate from a full-scale recirculating landfill was characterized by direct 16S rRNA gene (16S rDNA) retrieval. Total-community DNA was extracted from the microbial assemblages in the landfill leachate, and archaeal 16S rDNAs were amplified with a universally conserved primer and an Archaea-specific primer. The amplification product was then used to construct a 16S rDNA clone library, and 70 randomly selected archaeal clones in the library were grouped by restriction fragment length polymorphism (RFLP) analysis. Sequencing and phylogenetic analysis of representatives from each unique RFLP type showed that the archaeal library was dominated by methanogen-like rDNAs. Represented in the kingdom of Euryarchaeota were phylotypes highly similar to the methanogenic genera Methanoculleus, Methanosarcina, Methanocorpusculum, Methanospirillum and Methanogenium, where the clone distribution was 48, 11, 3, 1 and 1, respectively. No sequences related to known Methanosaeta spp. were retrieved. Four rDNA clones were not affiliated with the known methanogenic Archaea, but instead, they were clustered with the uncultured archaeal sequences recently recovered from anaerobic habitats. Two chimeric sequences were identified among the clones analyzed.