Neil3 and NEIL1 DNA Glycosylases Remove Oxidative Damages from Quadruplex DNA and Exhibit Preferences for Lesions in the Telomeric Sequence Context

The telomeric DNA of vertebrates consists of d(TTAGGG)_n tandem repeats, which can form quadruplex DNA structures in vitro and likely in vivo. Despite the fact that the G-rich telomeric DNA is susceptible to oxidation, few biochemical studies of base excision repair in telomeric DNA and quadruplex structures have been done. Here, we show that telomeric DNA containing thymine glycol (Tg), 8-oxo-7,8-dihydroguanine (8-oxoG), guanidinohydantoin (Gh), or spiroiminodihydantoin (Sp) can form quadruplex DNA structures in vitro. We have tested the base excision activities of five mammalian DNA glycosylases (NEIL1, NEIL2, mNeil3, NTH1, and OGG1) on these lesion-containing quadruplex substrates and found that only mNeil3 had excision activity on Tg in quadruplex DNA and that the glycosylase exhibited a strong preference for Tg in the telomeric sequence context. Although Sp and Gh in quadruplex DNA were good substrates for mNeil3 and NEIL1, none of the glycosylases had activity on quadruplex DNA containing 8-oxoG. In addition, NEIL1 but not mNeil3 showed enhanced glycosylase activity on Gh in the telomeric sequence context. These data suggest that one role for Neil3 and NEIL1 is to repair DNA base damages in telomeres in vivo and that Neil3 and Neil1 may function in quadruplex-mediated cellular events, such as gene regulation via removal of damaged bases from quadruplex DNA.     

Soluble CXCL16 promotes TNF‐α‐induced apoptosis in DLBCL via the AMAD10‐NF‐κB regulatory feedback loop

We had previously identified that the co‐expression of transmembrane CXCL16 (TM‐CXCL16) and its receptor CXCR6 is an independent risk factor for poor survival in patients with diffuse large B‐cell lymphoma (DLBCL). However, the impact of the soluble form of CXCL16 (sCXCL16) on the pathogenesis of DLBCL remains unknown. In the present study, the synergistic effect of sCXCL16 and tumor necrosis factor α (TNF‐α) on apoptosis in DLBCL cell lines (OCI‐LY8 and OCI‐LY10) was investigated in vitro. sCXCL16 reinforced TNF‐α‐mediated inhibition of DLBCL cell proliferation, as determined by the cell counting kit‐8 assay. The results of annexin V staining showed that sCXCL16 enhanced TNF‐α‐induced apoptosis in OCI‐LY8 and OCI‐LY10 cells through a death receptor‐caspase signaling pathway. The results of gene microarray suggested a significant upregulation of differentially expressed genes in the TNF signaling pathway. sCXCL16 increased the concentration of extracellular TNF‐α by binding to CXCR6 to activate the nuclear factor‐κB (NF‐κB) signaling pathway. TNF‐α also induced the secretion of sCXCL16 by increasing the expression of ADAM10, which is known to cleave TM‐CXCL16 to yield sCXCL16. Moreover, bioinformatics analysis revealed that elevated TNF‐α and ADAM10 expression levels in tumor tissues predicted better survival in patients with DLBCL. Thus, our study suggests that sCXCL16 enhances TNF‐α‐induced apoptosis of DLBCL cells, which may involve a positive feedback loop consisting of TNF‐α, ADAM10, sCXCL16, and members of the NF‐κB pathway. sCXCL16 and TNF‐α may be used as prognostic markers in the clinic, and their combinational use is a promising approach in the context of DLBCL therapy.     

A Water-absorbent Mat Incorporating β-cyclodextrin/eugenol Inclusion Complex for Preservation of Cold Fresh Mutton

To extend the shelf life of cold fresh mutton, the water-absorbent antibacterial mat was developed. This mat was composed of polylactic acid-β-cyclodextrin/eugenol (PLA-β-CD/EUG) fiber membrane, super absorbent polymer (SAP) and filter paper, in which the fiber membrane was developed by the electrospinning technique. The β-CD/EUG inclusion complexes were shown to form successfully by scanning electron microscope (SEM), fourier transform infrared spectroscopy (FTIR), water contact angle (WCA) analysis. The release experiment indicated that the PLA-β-CD/EUG fiber membranes had a slow-release effect, especially in the fatty food simulant. The water-absorbent antibacterial mats can restrain the growth of six spoilage bacteria. The mats were evaluated for the preservation of cold fresh mutton. The results revealed that it displayed prolongation of shelf life upon 8 days during the mutton at 4 °C storage period. The water-absorbent antibacterial mat can slowly release natural antibacterial agents and absorb water to achieve preservation, suggesting a potential application in meat products.

     

Hermetia illucens L. larvae–associated intestinal microbes reduce the transmission risk of zoonotic pathogens in pig manure

Black soldier fly (BSF) larvae are considered a promising biological reactor to convert organic waste and reduce the impact of zoonotic pathogens on the environment. We analysed the effects of BSF larvae on Staphylococcus aureus and Salmonella spp. populations in pig manure (PM), which showed that BSF larvae can significantly reduce the counts of the associated S. aureus and Salmonella spp. Then, using a sterile BSF larval system, we validated the function of BSF larval intestinal microbiota in vivo to suppress pathogens, and lastly, we isolated eight bacterial strains from the BSF larval gut that inhibit S. aureus. Results indicated that functional microbes are essential for BSF larvae to antagonise S. aureus. Moreover, the analysis results of the relationship between the intestinal microbiota and S. aureus and Salmonella spp. showed that Myroides, Tissierella, Oblitimonas, Paenalcalignes, Terrisporobacter, Clostridium, Fastidiosipila, Pseudomonas, Ignatzschineria, Savagea, Moheibacter and Sphingobacterium were negatively correlated with S. aureus and Salmonella. Overall, these results suggested that the potential ability of BSF larvae to inhibit S. aureus and Salmonella spp. present in PM is accomplished primarily by gut-associated microorganisms.     

Role of Tomato Lipoxygenase D in Wound-Induced Jasmonate Biosynthesis and Plant Immunity to Insect Herbivores

In response to insect attack and mechanical wounding, plants activate the expression of genes involved in various defense-related processes. A fascinating feature of these inducible defenses is their occurrence both locally at the wounding site and systemically in undamaged leaves throughout the plant. Wound-inducible proteinase inhibitors (PIs) in tomato (Solanum lycopersicum) provide an attractive model to understand the signal transduction events leading from localized injury to the systemic expression of defense-related genes. Among the identified intercellular molecules in regulating systemic wound response of tomato are the peptide signal systemin and the oxylipin signal jasmonic acid (JA). The systemin/JA signaling pathway provides a unique opportunity to investigate, in a single experimental system, the mechanism by which peptide and oxylipin signals interact to coordinate plant systemic immunity. Here we describe the characterization of the tomato suppressor of prosystemin-mediated responses8 (spr8) mutant, which was isolated as a suppressor of (pro)systemin-mediated signaling. spr8 plants exhibit a series of JA-dependent immune deficiencies, including the inability to express wound-responsive genes, abnormal development of glandular trichomes, and severely compromised resistance to cotton bollworm (Helicoverpa armigera) and Botrytis cinerea. Map-based cloning studies demonstrate that the spr8 mutant phenotype results from a point mutation in the catalytic domain of TomLoxD, a chloroplast-localized lipoxygenase involved in JA biosynthesis. We present evidence that overexpression of TomLoxD leads to elevated wound-induced JA biosynthesis, increased expression of wound-responsive genes and, therefore, enhanced resistance to insect herbivory attack and necrotrophic pathogen infection. These results indicate that TomLoxD is involved in wound-induced JA biosynthesis and highlight the application potential of this gene for crop protection against insects and pathogens.     

不同叶色矢竹叶绿体结构和光系统特性差异

以矢竹(Pseudosasa japonica)、花叶矢竹(P. japonica f. akebonosuji)和曙筋矢竹(P. japonica f. akebono)为研究对象, 借助叶绿体超微结构和荧光动力学曲线的变化揭示不同叶色矢竹的光系统活性及光合特性差异。结果表明: 3个竹种的光合色素含量差异明显, 除花叶矢竹条纹叶白色部分叶绿体内无完整类囊体片层结构外, 花叶矢竹绿条纹和曙筋矢竹的基粒数明显少于矢竹, 叶绿体发育成熟度不一致; OJIP曲线及参数表明, 花叶矢竹条纹绿叶和曙筋矢竹光系统II (PSII)反应中心开放降低程度低于矢竹, 捕获能量用于电子传递的份额变小, PSII活性变弱; 而曙筋矢竹叶片P700至初级电子受体(Q_A)的电子传递链氧化还原平衡偏向于还原侧, 推测其光系统I (PSI)反应中心P700至PSII Q_A电子传递链受损。因此, PSII活性变化导致叶绿体发育不成熟, 可能是引起矢竹类叶色差异的直接原因。     

不同生境濒危植物龙棕种群结构及其动态特征

【目的】分析不同生境下龙棕种群结构及动态特征,探究其主要影响因素,为该区龙棕种群的保护、恢复和更新提供基础的理论依据。【方法】通过对楚雄州大尖山自然保护区内3种不同生境(阔叶林、针阔混交林、灌丛)龙棕种群调查,编制龙棕种群的静态生命表和绘制其存活曲线和生存分析函数曲线,并利用时间序列模型对种群的数量动态做出相应的预测,以深入了解不同生境下龙棕种群结构及动态特征。【结果】(1)在3种生境中龙棕种群均处于衰退状态,对外界干扰较为灵敏,存活曲线呈现Deevey-Ⅲ型,龙棕个体在幼苗阶段出现大量死亡。(2)3种不同生境下龙棕种群都分布不均,呈聚集分布,说明龙棕种子传播以母株为中心扩散。【结论】从种群密度大小上来看,阔叶林中的龙棕种群密度最大,其次是针阔混交林,最小的是灌丛。结合对种群年龄结构的研究,进一步证明水分条件较好的阔叶林和针阔混交林更有利于龙棕种群的生存。