中华蜜蜂气味结合蛋白AcerOBP14的表达及配体结合特性分析

【目的】气味结合蛋白(odorant binding proteins, OBPs)在昆虫寄主定位、产卵地选择等行为中发挥着重要作用,明确中华蜜蜂Apis cerana cerana AcerOBP14与配体的结合特性有助于阐明中华蜜蜂嗅觉识别的分子机制。【方法】通过qRT-PCR测定OBP14在20日龄中华蜜蜂成年工蜂、20日龄中华蜜蜂成年雄蜂、中华蜜蜂采粉蜂和意大利蜜蜂Apis mellifera ligustica采粉蜂触角中的表达量。构建原核表达载体pET28a/AcerOBP14,表达并分离纯化重组蛋白AcerOBP14。利用荧光竞争结合实验检测AcerOBP14与37 种气味配体化合物的结合特性。【结果】qRT-PCR分析发现, OBP14在中华蜜蜂采粉蜂触角中的表达量极显著高于20日龄中华蜜蜂成年工蜂和雄蜂以及意大利蜜蜂采粉蜂中的。荧光竞争结合实验表明,AcerOBP14与蜂王信息素、告警信息素、那氏信息素及多种植物挥发物都具有结合能力,其中与β 罗勒烯的结合能力最强,解离常数 Ki=0.297 μmol/L。【结论】AcerOBP14的配体结合谱较宽,暗示其可能参与了中华蜜蜂的多种生理行为反应,且在中华蜜蜂的采粉行为中发挥着重要作用。     

Comparative Transcriptomic Analysis of Storage Roots in Cassava During Postharvest Physiological Deterioration

Plant Molecular Biology Reporter - Cassava is an important starchy and food crop; however, the commercial value of cassava is seriously constrained by postharvest physiological deterioration (PPD)....     

Inhibiting roles of FOXA2 in liver cancer cell migration and invasion by transcriptionally suppressing microRNA-103a-3p and activating the GREM2/LATS2/YAP axis

Cytotechnology - Forkhead box A2 (FOXA2) has emerged as a tumor inhibitor in several human malignancies. This work focused on the effect of FOXA2 on liver cancer (LC) cell invasion and migration...     

Mice with dysfunctional TGF-β signaling develop altered intestinal microbiome and colorectal cancer resistant to 5FU

Emerging data show a rise in colorectal cancer (CRC) incidence in young men and women that is often chemoresistant. One potential risk factor is an alteration in the microbiome. Here, we investigated the role of TGF-β signaling on the intestinal microbiome and the efficacy of chemotherapy for CRC induced by azoxymethane and dextran sodium sulfate in mice. We used two genotypes of TGF-β-signaling-deficient mice (Smad4^+/? and Smad4^+/?Sptbn1^+/?), which developed CRC with similar phenotypes and had similar alterations in the intestinal microbiome. Using these mice, we evaluated the intestinal microbiome and determined the effect of dysfunctional TGF-β signaling on the response to the chemotherapeutic agent 5-Fluoro-uracil (5FU) after induction of CRC. Using shotgun metagenomic sequencing, we determined gut microbiota composition in mice with CRC and found reduced amounts of beneficial species of Bacteroides and Parabacteroides in the mutants compared to the wild-type (WT) mice. Furthermore, the mutant mice with CRC were resistant to 5FU. Whereas the abundances of E. boltae, B.dorei, Lachnoclostridium sp., and Mordavella sp. were significantly reduced in mice with CRC, these species only recovered to basal amounts after 5FU treatment in WT mice, suggesting that the alterations in the intestinal microbiome resulting from compromised TGF-β signaling impaired the response to 5FU. These findings could have implications for inhibiting the TGF-β pathway in the treatment of CRC or other cancers.     

The optimum dietary methionine requirement of juvenile humpback grouper (Cromileptes altivelis): effects on growth,micromorphology, protein and lipid metabolism

An 8-week feeding trial was conducted to evaluate optimum dietary methionine (Met) requirement of juvenile humpback grouper (Cromileptes altivelis) and the influence of dietary methionine (Met) supplementations on growth, gut micromorphology, protein and lipid metabolism. Seven isoproteic (48.91%) and isolipidic diets (10%) were made to contain 0.70, 0.88, 1.04, 1.27 1.46, 1.61 and 1.76% of dry matter Met levels. Results showed that lower survival, weight gain (WG%), protein efficiency ratio (PER), protein productive value (PPV) but higher daily feed intake (DFI) and feed conversion ratio (FCR) were observed in the Met deficient groups (0.70 and 0.88%). Optimum dietary Met requirement for humpback grouper was found to be 1.07% through the straight-broken line analysis of WG% against Met. Fish fed Met deficient diets (0.70, 0.88%) exhibited lower mRNA levels of growth hormone (GH), growth hormone receptor (GHR), insulin-like growth factor-I (IGF-1), target of rapamycin (TOR) as well as S6 kinase 1 (S6K1) than other dietary groups. Whereas, expression of genes related to general control nonderepressible (GCN2) kinase i.e., GCN2 and C/EBPβ enhancer-binding protein β was upregulated in fish fed low Met diets (P < 0.05). The mRNA expression of hepatic fatty acid synthase (FAS) and sterol regulatory element-binding protein-1 (SREBP-1) were higher in fish fed 0.70 and 0.88% dietary Met group and the lipolytic genes, hepatic peroxisome proliferator-activated receptor α (PPARα) and carnitine palmitoyl transferase-1 (CPT-1) showed an opposite variation tendency as FAS or SREBP1. Generally, the optimum Met requirement for humpback grouper was predicted to be 1.07% of dry matter.

     

CCR-NB-LRR proteins MdRNL2 and MdRNL6 interact physically to confer broad-spectrum fungal resistance in apple (Malus × domestica)

Apple leaf spot, a disease caused by Alternaria alternata f. sp. mali and other fungal species, leads to severe defoliation and results in tremendous losses to the apple (Malus × domestica) industry in China. We previously identified three RPW8, nucleotide-binding, and leucine-rich repeat domain CC_R-NB-LRR proteins (RNLs), named MdRNL1, MdRNL2, and MdRNL3, that contribute to Alternaria leaf spot (ALT1) resistance in apple. However, the role of NB-LRR proteins in resistance to fungal diseases in apple remains poorly understood. We therefore used MdRNL1/2/3 as baits to screen ALT1-inoculated leaves for interacting proteins and identified only MdRNL6 (another RNL) as an interactor of MdRNL2. Protein interaction assays demonstrated that MdRNL2 and MdRNL6 interact through their NB-ARC domains. Transient expression assays in apple indicated that complexes containing both MdRNL2 and MdRNL6 are necessary for resistance to Alternaria leaf spot. Intriguingly, the same complexes were also required to confer resistance to Glomerella leaf spot and Marssonina leaf spot in transient expression assays. Furthermore, stable transgenic apple plants with suppressed expression of MdRNL6 showed hypersensitivity to Alternaria leaf spot, Glomerella leaf spot, and Marssonina leaf spot; these effects were similar to the effects of suppressing MdRNL2 expression in transgenic apple plantlets. The identification of these novel broad-spectrum fungal resistance genes will facilitate breeding for fungal disease resistance in apple.     

Divergent DNA methylation contributes to duplicated gene evolution and chilling response in tea plants

The tea plant (Camellia sinensis) is a thermophilic cash crop and contains a highly duplicated and repeat-rich genome. It is still unclear how DNA methylation regulates the evolution of duplicated genes and chilling stress in tea plants. We therefore generated a single-base-resolution DNA methylation map of tea plants under chilling stress. We found that, compared with other plants, the tea plant genome is highly methylated in all three sequence contexts, including CG, CHG and CHH (where H = A, T, or C), which is further proven to be correlated with its repeat content and genome size. We show that DNA methylation in the gene body negatively regulates the gene expression of tea plants, whereas non-CG methylation in the flanking region enables a positive regulation of gene expression. We demonstrate that transposable element-mediated methylation dynamics significantly drives the expression divergence of duplicated genes in tea plants. The DNA methylation and expression divergence of duplicated genes in the tea plant increases with evolutionary age and selective pressure. Moreover, we detect thousands of differentially methylated genes, some of which are functionally associated with chilling stress. We also experimentally reveal that DNA methyltransferase genes of tea plants are significantly downregulated, whereas demethylase genes are upregulated at the initial stage of chilling stress, which is in line with the significant loss of DNA methylation of three well-known cold-responsive genes at their promoter and gene body regions. Overall, our findings underscore the importance of DNA methylation regulation and offer new insights into duplicated gene evolution and chilling tolerance in tea plants.