Plant flowering time is affected by endogenous and exogenous factors, but its variation patterns among different populations of a species has not been fully established. In this study, 27 Arabidopsis thaliana accessions were used to investigate the relationship between autonomous pathway gene methylation, gene expression and flowering time variation. DNA methylation analysis, RT-qPCR and transgenic verification showed that variation in the flowering time among the Arabidopsis populations ranged from 19 to 55 days and was significantly correlated with methylation of the coding regions of six upstream genes in the autonomous pathway, FLOWERING LOCUS VE (FVE), FLOWERING LOCUS Y (FY), FLOWERING LOCUS D (FLD), PEPPER (PEP), HISTONE DEACETYLASE 5 (HAD5) and Pre-mRNA Processing Protein 39-1 (PRP39-1), as well as their relative expression levels. The expression of FVE and FVE(CS) was modified separately through degenerate codon substitution of cytosine and led to earlier flowering of transgenic plants by 8 days and 25 days, respectively. An accurate determination of methylated sites in FVE and FVE(CS) among those transgenic plants and the recipient Col-0 verified the close relationship between the number of methylation sites, expression and flowering time. Our findings suggest that the methylation variation of these six key upstream transcription factors was associated with the gene expression level of the autonomous pathway and flowering time in Arabidopsis. The FVE(CS) and FVE genes in transgenic plants tended to be hypermethylated, which could be a protective mechanism for plants. However, modification of gene sequences through degenerate codon substitution to reduce cytosine can avoid hypermethylated transferred genes in transgenic plants. It may be possible to partially regulate the flowering of plants by modified trans-epigenetic technology.

Griseofulvin was considered an effective agent for cancer therapy in past decades. Although the negative effects of griseofulvin on microtubule stability are known, the exact target and mechanism of action in plants remain unclear. Here, we used trifluralin, a well-known herbicide targeting microtubules, as a reference and revealed the differences in root tip morphology, reactive oxygen species production (ROS), microtubule dynamics, and transcriptome analysis between Arabidopsis treated with griseofulvin and trifluralin to elucidate the mechanism of root growth inhibition by griseofulvin. Like trifluralin, griseofulvin inhibited root growth and caused significant swelling of the root tip due to cell death induced by ROS. However, the presence of griseofulvin and trifluralin caused cell swelling in the transition zone (TZ) and meristematic zone (MZ) of root tips, respectively. Further observations revealed that griseofulvin first destroyed cortical microtubules in the cells of the TZ and early elongation zone (EZ) and then gradually affected the cells of other zones. The first target of trifluralin is the microtubules in the root MZ cells. Transcriptome analysis showed that griseofulvin mainly affected the expression of microtubule-associated protein (MAP) genes rather than tubulin genes, whereas trifluralin significantly suppressed the expression of αβ-tubulin genes. Finally, it was proposed that griseofulvin could first reduce the expression of MAP genes, meanwhile increasing the expression of auxin and ethylene-related genes to disrupt microtubule alignment in root tip TZ and early EZ cells, induce dramatic ROS production, and cause severe cell death, eventually leading to cell swelling in the corresponding zones and inhibition of root growth.

CRISPR基因编辑技术逐渐成为一个强有力的分子技术,已越来越广泛地应用于科学研究和临床试验.在高校教学实践中,为了解决该实验原理复杂、操作难度大、周期长、成本高等问题,构建了CRISPR基因编辑仿真教学软件.该软件包括原理演示和实训操作2个模块.原理部分通过3D技术呈现出每个分子的结构,并以动画的形式演绎CRISPR-Cas9的分子机制.实训操作部分模拟了整个实验的操作过程,学生可以通过互动的形式在电脑上反复学习和操作.该交互式虚拟实验能激发学生的学习兴趣,显著提高实验教学质量.

Cadmium (Cd) has the potential to be chronically toxic to humans through contaminated crop products. MicroRNAs (miRNAs) can move systemically in plants. To investigate the roles of long-distance moving xylem miRNAs in regulating maize response to Cd stress, three xylem sap small RNA (sRNA) libraries were constructed for high-throughput sequencing to identify potential mobile miRNAs in Cd-stressed maize seedlings and their putative targets in maize transcriptomes. In total, about 199 miRNAs (20–22 nucleotides) were identified in xylem sap from maize seedlings, including 97 newly discovered miRNAs and 102 known miRNAs. Among them, 10 miRNAs showed differential expression in xylem sap after 1 h of Cd treatment. Two miRNAs target prediction tools, psRNAtarget (reporting the inhibition pattern of cleavage) and DPMIND (discovering Plant MiRNA-Target Interaction with degradome evidence), were used in combination to identify, via bioinformatics, the targets of 199 significantly expressed miRNAs in maize xylem sap. The integrative results of these two bioinformatic tools suggested that 27 xylem sap miRNAs inhibit 34 genes through cleavage with degradome evidence. Moreover, nearly 300 other genes were also the potential miRNAs cleavable targets without available degradome data support, and the majority of them were enriched in abiotic stress response, cell signaling, transcription regulation, as well as metal handling. These approaches and results not only enhanced our understanding of the Cd-responsive long-distance transported miRNAs from the view of xylem sap, but also provided novel insights for predicting the molecular genetic mechanisms mediated by miRNAs.

The adverse effects of intake nitrite upon human health are well known. However, eating fruits and vegetables is one of the main pathways to absorb nitrite because of nitrogen assimilation in plants. This study demonstrated that during storage of tomato fruit, the production of endogenous hydrogen (H2) was decreased, in parallel with nitrite accumulation and the senescence rate. Furthermore, exogenously applied H2 could delay the decreased fruit H2 production and senescence, but importantly, nitrite accumulation was blocked. Consistently, the activities and transcripts of nitrate reductase (NR; catalyzing the synthesis of nitrite) and nitrite reductase (NiR; responsible for the reduction of nitrite to ammonium), were either inhibited or increased, respectively, by 0.585 mM H2. Decreased or increased nitrite synthesis was observed when tungstate (an inhibitor of NR) or 2,6-dichloroindophenol sodium salt (a putative inhibitor of H2 synthesis) were applied separately. Time-course analysis revealed that the decrease in vitamin C, a well-known nitrite scavenger, was blocked by H2. Overall, this study strongly revealed that nitrite accumulation during storage of tomato fruit was prevented by H2. This study describes potential applications for H2 in agriculture and food industry, especially in the preservation of fruit and vegetable products. Abbreviations: Ar, argon; DCPIP, 2,6-dichloroindophenol sodium salt; GC, gas chromatograph; H2, hydrogen gas; HPLC, high-performance liquid chromatography; HRW, hydrogen-rich water; N, Newton; N2, nitrogen; NO, nitric oxide; NiR, nitrite reductase; NO2−, sodium nitrite; NO3−, sodium nitrate; NR, nitrate reductase; ONOO−, peroxynitrite anion; qPCR, Real-time quantitative reverse transcription-PCR; RNS, reactive nitrogen species; ROS, reactive oxygen species.

Exogenous hydrogen-rich water (HRW) improves vase life and quality of cut flowers, but the effects of endogenous hydrogen gas (H-2) are not known. During the vase of cut lisianthus flowers, endogenous H-2 concentrations decreased and redox homeostasis was impaired. The supplementation with HRW containing 0.078 mmol L-1 H-2 blocked, but 2,6-dichlorophenolindophenol (DCPIP; a putative inhibitor of H-2 synthesis) increased, endogenous H-2 production. Senescence of cut flowers was delayed by H-2, but accelerated by DCPIP. Also, decreased vase life by DCPIP was blocked by H-2 administration. These beneficial roles of H-2 were associated with less lipid peroxidation, and the increased activities of superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, and catalase. Compared with DCPIP alone, the soluble protein, total chlorophyll, and proline contents were elevated when H-2 and DCPIP were added together. Overall, endogenous H-2 prolongs vase life of lisianthus cut flowers in part by maintaining redox homeostasis.

ABSTRACT The degradation of the herbicide dicamba is initiated by demethylation to form 3,6-dichlorosalicylate (3,6-DCSA) in Rhizorhabdus dicambivorans Ndbn-20. In the present study, a 3,6-DCSA degradation-deficient mutant, Ndbn-20m, was screened. A cluster, dsmR1DABCEFGR2 , was lost in this mutant. The cluster consisted of nine genes, all of which were apparently induced by 3,6-DCSA. DsmA shared 30 to 36% identity with the monooxygenase components of reported three-component cytochrome P450 systems and formed a monophyletic branch in the phylogenetic tree. DsmB and DsmC were most closely related to the reported [2Fe-2S] ferredoxin and ferredoxin reductase, respectively. The disruption of dsmA in strain Ndbn-20 resulted in inactive 3,6-DCSA degradation. When dsmABC , but not dsmA alone, was introduced into mutant Ndbn-20m and Sphingobium quisquiliarum DC-2 (which is unable to degrade salicylate and its derivatives), they acquired the ability to hydroxylate 3,6-DCSA. Single-crystal X-ray diffraction demonstrated that the DsmABC-catalyzed hydroxylation occurred at the C-5 position of 3,6-DCSA, generating 3,6-dichlorogentisate (3,6-DCGA). In addition, DsmD shared 51% identity with GtdA (a gentisate and 3,6-DCGA 1,2-dioxygenase) from Sphingomonas sp. strain RW5. However, unlike GtdA, the purified DsmD catalyzed the cleavage of gentisate and 3-chlorogentisate but not 6-chlorogentisate or 3,6-DCGA in vitro . Based on the bioinformatic analysis and gene function studies, a possible catabolic pathway of dicamba in R. dicambivorans Ndbn-20 was proposed. IMPORTANCE Dicamba is widely used to control a variety of broadleaf weeds and is a promising target herbicide for the engineering of herbicide-resistant crops. The catabolism of dicamba has thus received increasing attention. Bacteria mineralize dicamba initially via demethylation, generating 3,6-dichlorosalicylate. However, the catabolism of 3,6-dichlorosalicylate remains unknown. In this study, we cloned a gene cluster, dsmR1DABCEFGR2 , involved in 3,6-dichlorosalicylate degradation from R. dicambivorans Ndbn-20, demonstrated that the cytochrome P450 monooxygenase system DsmABC was responsible for the 5-hydroxylation of 3,6-dichlorosalicylate, and proposed a dicamba catabolic pathway. This study provides a basis to elucidate the catabolism of dicamba and has benefits for the ecotoxicological study of dicamba. Furthermore, the hydroxylation of salicylate has been previously reported to be catalyzed by single-component flavoprotein or three-component Rieske non-heme iron oxygenase, whereas DsmABC was the only cytochrome P450 monooxygenase system hydroxylating salicylate and its methyl- or chloro-substituted derivatives.

Background: Osmotic stress is a major abiotic stress limiting crop production by affecting plant growth and development. Although previous reports discovered that methane (CH4) has a beneficial effect on osmotic stress, the corresponding downstream signal(s) is still elusive. Results: Polyethylene glycol (PEG) treatment progressively stimulated the production of CH4 in germinating mung bean seeds. Exogenous CH4 and sodium nitroprusside (SNP) not only triggered nitric oxide (NO) production in PEGstressed plants, but also alleviated the inhibition of seed germination. Meanwhile, amylase activity was activated, thus accelerating the formation of reducing sugar and total soluble sugar. Above responses could be impaired by NO scavenger(s), suggesting that CH4-induced stress tolerance was dependent on NO. Subsequent tests showed that CH4 could reestablish redox balance in a NO-dependent fashion. The addition of inhibitors of the nitrate reductase (NR) and NO synthase in mammalian (NOS), suggested that NR and NOS-like protein might be partially involved in CH4-alleviated seed germination inhibition. In vitro and scavenger tests showed that NO-mediated S-nitrosylation might be associated with above CH4 responses. Conclusions: Together, these results indicated an important role of endogenous NO in CH4-enhanced plant tolerance against osmotic stress, and NO-regulated redox homeostasis and S-nitrosylation might be involved in above CH4 action.

Cold stress is a major abiotic factor plants face during their life cycle. Although plants often exhibit phenotypic variation in cold tolerance, the underlying mechanism remains poorly understood. In the present study, the 50% lethal temperature (LT50) values of 37 Arabidopsis thaliana accessions at latitudes from 15° to 58° ranged from -13.2°C to -4.9°C and were closely correlated with the cold climates of the collection sites. According to a methylation analysis of all C-repeat (CRT)-binding factor (CBF) pathway genes, the coding and promoter regions of AtICE1, a regulator of CBF genes, exhibited the greatest variability in methylation levels among the accessions and included 5-122 methylated cytosine residues. In contrast, unmethylated or only slightly methylated genes in the CBF pathway showed little variation among the accessions. According to a gene expression analysis of four selected A. thaliana populations with distinct methylation patterns, except for the down-regulated gene AtCBF2, the expression levels of all members of the CBF pathway were negatively correlated with AtICE1 gene methylation levels. Treatment of the four A. thaliana populations with the DNA methylation inhibitory reagent 5-azacytidine resulted in a 30.0-78.3% enhancement of freezing tolerance and decreases in LT50 values of approximately 1.9-3.6°C. Similar effects were observed in drm2 mutants, including 30.0-48.3% increases in freezing tolerance and decreases in LT50 values of approximately 0.7-3.4°C. Thus, the AtICE1 methylation-regulated transcription of CBF pathway genes is responsible for the phenotypic variation in the freezing tolerance observed in A. thaliana.

Background: Metal tolerance is often an integrative result of metal uptake and distribution, which are fine-tuned by a network of signaling cascades and metal transporters. Thus, with the goal of advancing the molecular understanding of such metal homeostatic mechanisms, comparative RNAseq-based transcriptome analysis was conducted to dissect differentially expressed genes (DEGs) in maize roots exposed to cadmium (Cd) stress. Results: To unveil conserved Cd-responsive genes in cereal plants, the obtained 5166 maize DEGs were compared with 2567 Cd-regulated orthologs in rice roots, and this comparison generated 880 universal Cd-responsive orthologs groups composed of 1074 maize DEGs and 981 rice counterparts. More importantly, most of the orthologous DEGs showed coordinated expression pattern between Cd-treated maize and rice, and these include one large orthologs group of pleiotropic drug resistance (PDR)-type ABC transporters, two clusters of amino acid transporters, and 3 blocks of multidrug and toxic compound extrusion (MATE) efflux family transporters, and 3 clusters of heavy metal-associated domain (HMAD) isoprenylated plant proteins (HIPPs), as well as all 4 groups of zinc/iron regulated transporter protein (ZIPs). Additionally, several blocks of tandem maize paralogs, such as germin-like proteins (GLPs), phenylalanine ammonia-lyases (PALs) and several enzymes involved in JA biosynthesis, displayed consistent co-expression pattern under Cd stress. Out of the 1074 maize DEGs, approximately 30 maize Cd-responsive genes such as ZmHIPP27, stress-responsive NAC transcription factor (ZmSNAC1) and 9-cis-epoxycarotenoid dioxygenase (NCED, vp14) were also common stress-responsive genes reported to be uniformly regulated by multiple abiotic stresses. Moreover, the aforementioned three promising Cd-upregulated genes with rice counterparts were identified to be novel Cd-responsive genes in maize. Meanwhile, one maize glutamate decarboxylase (ZmGAD1) with Cd co-modulated rice ortholog was selected for further analysis of Cd tolerance via heterologous expression, and the results suggest that ZmGAD1 can confer Cd tolerance in yeast and tobacco leaves. Conclusions: These novel findings revealed the conserved function of Cd-responsive orthologs and paralogs, which would be valuable for elucidating the genetic basis of the plant response to Cd stress and unraveling Cd tolerance genes.

Although hydrogen (H-2) and nitric oxide (NO) are respectively suggested to enhance plant tolerance against osmotic stress, the corresponding causal link is still elusive. In this report, the application of hydrogen-rich water (HRW) strengthened the production of NO in PEG-stressed alfalfa seedling roots, followed by the obvious alleviation of seedling growth inhibition. Comparatively, significant but weaker responses in phenotypes were observed in the plants supplemented with nitrogen-rich water, indicating that the role of HRW was H-2-related. The application of tungstate, an inhibitor of the NO synthetic enzyme nitrate reductase (NR), showed the similar blocking response in the phenotype, suggesting that NR might be the major source of NO involved in above H-2 actions. Proline synthesis was stimulated by H-2 and NO, both of which were supported by the increased Delta(1)-pyrroline-5-carboxylate synthetase (P5CS) activities, the decreased proline dehydrogenase (ProDH) activities, and corresponding transcripts. The addition of H-2 and NO could increase antioxidant defence in stressed plants, confirmed by the histochemical staining for reactive oxygen species (ROS) production and lipid peroxidation, representative antioxidant enzyme activities, and transcripts. Thus, redox balance was reestablished. When NO scavenger was applied, NO and proline syntheses, redox balance, and thereafter osmotic tolerance induced by H-2, were severely impaired. Additionally, H-2-triggered S-nitrosylation was obviously inhibited by the removal of endogenous NO level. Together, above results discovered the involvement of NO-induced proline and redox balance in H-2-triggered osmotic tolerance.

WRKY transcription factors act as positive regulators in abiotic stress responses by activation of the cellular antioxidant systems. However, there are few reports on the response of WRKY genes to cadmium (Cd) stress. In this study, the role of maize ZmWRKY4 in regulating antioxidant enzymes in Cd stress was investigated. The results indicated that Cd induced up-regulation of the expression and the activities of ZmWRKY4 and superoxide dismutase (SOD) and ascorbate peroxidase (APX). Transient expression and RNA interference (RNAi) silencing of ZmWRKY4 in maize mesophyll protoplasts further revealed that ZmWRKY4 was required for the abscisic acid (ABA)-induced increase in expression and activity of SOD and APX. Overexpression of ZmWRKY4 in protoplasts upregulated the expression and the activities of antioxidant enzymes, whereas ABA induced increases in the expression and the activities of antioxidant enzymes were blocked by the RNAi silencing of ZmWRKY4. Bioinformatic analysis indicated that ZmSOD4 and ZmcAPX both harbored two W-boxes, binding motif for WRKY transcription factors, in their promoter region. Intriguingly, ZmWRKY4 belongs to group I WRKYs with two WRKY domains. Moreover, the synchronized expression patterns indicate that ZmWRKY4 might play a critical role in either regulating the ZmSOD4 and ZmcAPX expression or cooperating with them in response to stress and phytohormone.

Background: The migration of cadmium (Cd) from contaminated soil to rice is a cause for concern. However, the molecular mechanism underlying the response of rice roots to various Cd stresses remains to be clarified from the viewpoint of the co-expression network at a system-wide scale. Results: We employed a comparative RNAseq-based approach to identify early Cd-responsive differentially expressed genes (DEGs) in rice 'Nipponbare' seedling roots after 1 h of high-Cd treatment. A multiplicity of the identified 1772 DEGs were implicated in hormone signaling and transcriptional regulation, particularly NACs and WRKYs were all upregulated under Cd stress. All of the 6 Cd-upregulated ABC transporters were pleiotropic drug resistance proteins (PDRs), whereas all of the 6 ZRT/IRT-like proteins (ZIPs) were consistently downregulated by Cd treatment. To further confirm our results of this early transcriptomic response to Cd exposure, we then conducted weighted gene co-expression network analysis (WGCNA) to re-analyze our RNAseq data in combination with other 11 previously published RNAseq datasets for rice roots exposed to diverse concentrations of Cd for extended treatment periods. This integrative approach identified 271 transcripts as universal Cd-regulated DEGs that are key components of the Cd treatment coupled co-expression module. A global view of the 164 transcripts with annotated functions in pathway networks revealed several Cd-upregulated key functional genes, including transporter ABCG36/OsPDR9, 12-oxo-phytodienoic acid reductases (OPRs) for JA synthesis, and ZIM domain proteins JAZs in JA signaling, as well as OsWRKY10, NAC, and ZFP transcription factors. More importantly, 104 of these, including ABCG36/OsPDR9, OsNAC3, as well as several orthologs in group metalloendoproteinase, plastocyanin-like domain containing proteins and pectin methylesterase inhibitor, may respond specifically to various Cd pressures, after subtracting the 60 general stress-responsive genes reported to be commonly upregulated following multiple stresses. Conclusion: An integrative approach was implemented to identify DEGs and co-expression network modules in response to various Cd pressures, and 104 of the 164 annotatable universal Cd-responsive DEGs may specifically respond to various Cd pressures. These results provide insight into the universal molecular mechanisms beneath the Cd response in rice roots, and suggest many promising targets for improving the rice acclimation process against Cd toxicity.

Metabolism of molecular hydrogen (H2) in bacteria and algae has been widely studied, and it has attracted increasing attention in the context of animals and plants. However, the role of endogenous H2 in lateral root (LR) formation is still unclear. Here, our results showed that H2-induced lateral root formation is a universal event. Naphthalene-1-acetic acid (NAA; the auxin analog) was able to trigger endogenous H2 production in tomato seedlings, and a contrasting response was observed in the presence of N-1-naphthyphthalamic acid (NPA), an auxin transport inhibitor. NPA-triggered the inhibition of H2 production and thereafter lateral root development was rescued by exogenously applied H2. Detection of endogenous nitric oxide (NO) by the specific probe 4-amino-5-methylamino-2′,7′-difluorofluorescein diacetate (DAF-FM DA) and electron paramagnetic resonance (EPR) analyses revealed that the NO level was increased in both NAA- and H2-treated tomato seedlings. Furthermore, NO production and thereafter LR formation induced by auxin and H2 were prevented by 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO; a specific scavenger of NO) and the inhibitor of nitrate reductase (NR; an important NO synthetic enzyme). Molecular evidence confirmed that some representative NO-targeted cell cycle regulatory genes were also induced by H2, but was impaired by the removal of endogenous NO. Genetic evidence suggested that in the presence of H2, Arabidopsis mutants nia2 (in particular) and nia1 (two nitrate reductases (NR)-defective mutants) exhibited defects in lateral root length. Together, these results demonstrated that auxin-induced H2 production was associated with lateral root formation, at least partially via a NR-dependent NO synthesis.

植物学虚拟实验平台结合了虚拟显微镜系统、植物识别系统、植物学数字课程和虚拟仿真实验4个功能模块,系统地整合了植物组织解剖、植物类群分类两部分实验教学资源.平台首次将虚拟仿真教学资源应用于植物组织结构观察和植物分类识别鉴定的实验教学,各教学资源既相互独立、自成一体,又能贯穿植物学实验技术的整个过程,可根据实验要求进行灵活组合,以满足学生个性化学习方式的需求.通过该平台的应用,不仅扩充了教学信息容量,提升了教学效率,同时也有利于教学资源的管理和利用,推动了植物学实验教学模式的改革和创新.从植物学实验教学中的实际应用出发,具体探讨了虚拟实验平台的构建思路,实现模式及应用效果.

借助虚拟仿真技术构建的虚实结合的虚拟仿真实验,是提高学生实践动手能力的有力补充和有效途径.本文通过对微生物学实验教学现状的分析,探讨南京农业大学微生物学虚拟仿真实验教学模式建设的意义,重点阐述建设思路、建设方案及教学特点.该仿真实验教学体系主要从基础微生物学和应用微生物学两大模块进行构建,同时将本校的污水生物处理技术、食用菌资源调查与利用等科研成果转化为教学资源,以丰富实验教学内容.

如何利用基因组、转录组以及代谢组学等海量信息确定基因功能,并阐述其调控机制是生命科学研究领域的核心内容之一.本研究利用种群间数量性状遗传变异与相应基因表达量差异之间的关联性,尝试一种功能基因筛选的快速方法,首先利用已经发表的拟南芥(Arabidopsis thaliana)生物信息数据,运用线性相关模型,根据拟南芥种群遗传变异导致的叶片表皮毛数量性状差异和对应种群基因表达量差异的相关性,筛选与表皮毛性状功能相关的基因,从33 554个基因中共筛选到1 747个相关基因,其中负相关基因195个,正相关基因1 552个.对筛选基因集合进行基因本体(Gene Ontology,GO)富集分析,结果表明,筛选到的基因主要富集于植物防御、先天免疫、胁迫反应、茉莉酸刺激应答、机械损伤反应和芥子油苷代谢等生物功能,特别筛选到和表皮毛发育及其防御代谢物分泌有关的基因,如诱导叶片表皮毛分化起始的MYB结构域蛋白基因MYB23,对叶片表皮毛发育具有重要影响的缺陷表皮毛因子1 (distorted trichomes 1,DIS1),参与吲哚芥子油苷合成的细胞色素P450家族蛋白基因(cytochrome P450 family 81 subfamily F polypeptide 2,CYP81F2)和MYB51.将本研究筛选基因功能富集结果与前人对表皮毛的功能研究成果做对比,证明了本研究中所用方法的可行性.因此,在与数量性状有关目的基因筛选的研究中,此方法可以作为参考,对于其他物种的数量性状研究也具有借鉴意义.

Based on the actual application in the biological field practice,Nanjing Agricultural University Virtual Simulation Experimental Teaching Center led to construct the virtual simulation training system in Tianmu Mountain biological field practice.This paper discusses the idea of constructing virtual experiment platform,implementation mode and application effect.This system makes full use of modern information technology,organic integrate simulation technology with experimental teaching,and gets the breakthrough of the weak points of traditional filed practice.Through the application of the platform,it can not only expand the capacity of teaching information,improve teaching efficiency,but also promote the reform and innovation of biological field practice teaching mode.

从虚拟仿真实验教学资源整合与构建的角度，论述了南京农业大学农业生物学国家级虚拟仿真实验教学中心在植物学、动物学、动植物野外实习和现代生物技术等领域实验教学信息化建设过程中取得的初步成果，分析了虚拟仿真实验教学平台在生物学实验教学中发挥的独特优势，也提出了教学资源信息化建设和管理中存在的一些亟待解决的问题。

Multi-drug resistance (MDR) cancer is an intractable problem. Over-expression of drug efflux transporters such as ABCB1, ABCC1 and ABCG2 contributes to it, by which they pump drugs out of cells, and result in the decrease in the efficacy of chemotherapy. To reverse the cancer MDR, we used 3-methyladenine (3-MA) treatment on taxol or doxorubicin stressed MDR cell lines A2780DX5 and SGC7091R and xeno-tumor implanted mice. The results indicate that ABCB1, ABCC1 and ABCG2 were depressed, and the PI3K-AKT-mTOR pathway was blocked. Moreover, using FITC-labeled taxol as the indicator, we observed that the drug accumulation was enhanced in MDR cells and more cells were killed after 3-MA administration. Thus suggesting that 3-MA can reverse cancer MDR via depressing agent-efflux transporters.