Detection of ARV-Resistant Mutants in HIV-1-Infected Individuals in a Context of Systematic Switching to an Association Based on Dolutegravir in Abidjan, Côte d’Ivoire

The emergence of antiretroviral resistance mutations represents a major threat to the achievement of national and global goals for the elimination of HIV-1 infection. The global strategy in 2019 in Cte d'Ivoire is a new national policy for the management of people living with HIV with the administration of dolutegravir (DTG)-based fixed-dose combination. The aim of our study was to evaluate HIV-1 resistance to antiretrovirals (ARVs) in infected adult subjects in Cte d’Ivoire in the context of a systematic switch to a DTG-based combination. Between February 2022 and October 2023, a cross-sectional survey with random sampling was conducted in 06 services caring for people living with HIV. A total of 139 participants were included in the study. Adults with a viral load ≥ 1000 copies/mL were tested for HIV-1 ARV resistance mutations. Molecular analyses were performed using protocol of ANRS-MIE (National Agency for Research on AIDS and emerging infectious diseases). The interpretation is performed by HIVGRAD (https://www.hiv-grade.de/cms/grade/). The frequencies of HIV-1 resistance to non-nucleotide reverse transcriptase inhibitors (NNRTIs), nucleotide reverse transcriptase inhibitors (NRTIs), integrase inhibitors (IINTs) and protease inhibitors (PIs) were 82%, 73%, 19% and 11% respectively. The main mutations observed in the different classes were K103N (45%), M184V (64%), E157Q (19%) and L10V/M46I/A71V/I54V (6%) respectively. This study reveals the emergence of resistance to DTG-based fixed-dose combinations, favored by high rates of resistance to NRTIs and NNRTIs. This finding underlines the need for enhanced viral load monitoring and HIV-1 genotyping tests to guide the choice of NRTIs for combination therapy. In addition, monitoring for mutations to second-generation NRTIs is essential, given the scale-up of DTG-based regimens currently underway in Cte d’Ivoire.

贵州地方稻种来拢小圆粒半矮秆突变体srd-1筛选及鉴定

以贵州地方稻种来拢突变体库中能稳定遗传的小圆粒半矮秆突变体srd-1为材料,对其半矮化和小圆粒性状分子机制进行研究。暗形态建成表明srd-1突变体矮化性状与BR无关。srd-1突变体表现对GA敏感,外源GA3对突变体幼苗第2叶鞘有促进生长作用,能诱导α-淀粉酶活性,可以使倾斜方向排列的细胞微管骨架恢复至野生型横向排列方向,表明srd-1突变体矮化性状与GA信号传导途径无关。GA合成途径中关键酶基因Os KS1和Os GA2ox1表达相对于野生型差异不显著,Os CPS、Os KO2、Os KAO、Os GA20ox2和Os GA3ox2基因表达下调,初步说明srd-1突变体的矮化性状可能是由活性GA生物合成降低所致。此外,小圆粒调控基因SRS1、SRS3和SRS5表达下调,表明srd-1突变体突变基因同时参与了籽粒大小和株高的调控,突变基因影响了活性GA的生物合成和小圆粒调控关键酶基因的表达,进而导致了矮化和小圆粒表型的产生。该研究为突变体突变基因的定位及利用研究提供了参考。

贵州地方稻种来拢小圆粒半矮秆突变体srd-1光合特性研究

以EMS诱变处理贵州地方稻种来拢,建立突变体库,并从中筛选1份能稳定遗传的小圆粒半矮秆突变体srd-1为材料,对其光合生理特性进行了研究。结果表明,srd-1突变体茎节数目减少,茎节和颖壳纵向上细胞长度缩短;生长发育后期光合速率减小较为缓慢,能维持较高的光合速率;在籽粒成熟期,由于叶绿素b含量的增加导致了叶绿素总量高于野生型,叶绿素a/b明显减小。

茶树新品系‘福黄1号’白茶的特征香气成分及其在加工过程中的动态变化

为了研究高氨基酸白化突变新品系‘福黄1号’白茶的特征香气成分及其在加工过程中的动态变化,以‘福黄1号’为材料,变异来源‘福安大白茶’为对照,采用顶空固相微萃取-气相色谱-质谱联用技术对萎凋0、12、24、36、48 h和成品茶样品的香气成分及其相对含量进行鉴定与分析。结果表明:实验样品共鉴定出560种挥发性代谢物,其中萜类、杂环化合物、酯类、烃类等是以‘福黄1号’和‘福安大白茶’为鲜叶原料制成白茶的主要呈香物质。萎凋过程中,两个品种白茶的挥发性代谢物总含量逐渐上升,在萎凋48 h的时候达到最大值。相对气味活度值分析结果表明,萜品油烯、柠檬醛、1-辛烯-3-酮、大马士酮是‘福黄1号’和‘福安大白茶’的关键香气成分,水杨酸甲酯和苯甲醛是‘福黄1号’白茶的关键香气成分。1-辛烯-3-酮和柠檬醛在萎凋前期大量累积而后减少,萜品油烯、苯甲醛、水杨酸甲酯和大马士酮在萎凋过程中持续累积。萜品油烯、柠檬醛、1-辛烯-3-酮、大马士酮对‘福黄1号’和‘福安大白茶’形成花果香和甜香具有重要作用。1-辛烯-3-酮、水杨酸甲酯和苯甲醛是‘福黄1号’白茶清鲜香气形成的关键原因。本研究有助于全面了解新品系‘福黄1号’制成白茶的香气特征,为以白化茶树品种为原料制成的特色白茶产品研发提供科学依据。

Feasibility of herpes simplex virus type 1 mutants labeled with radionuclides for tumor treatment

For over one hundred years, viruses have been recognized as capable of killing tumor cells. At present, people are still researching and constructing more suitable oncolytic viruses for treating different malignant tumors. Although extensive studies have demonstrated that herpes simplex virus type 1 (HSV-1) is the most potential oncolytic virus, therapies based on herpes simplex virus type 1 vectors still arouse bio-safety and risk management issues. Researchers have therefore introduced the new idea of treating cancer with HSV-1 mutants labeled with radionuclides, combining radionuclide and oncolytic virus therapies. This overview briefly summarizes the status and mechanisms by which oncolytic viruses kill tumor cells, discusses the application of HSV-1 and HSV-1 derived vectors for tumor therapy, and demonstrates the feasibility and prospect of HSV-1 mutants labeled with radionuclides for treating tumors.

Autophagic induction of amyotrophic lateral sclerosislinked Cu/Zn superoxide dismutase 1 G93A mutant in NSC34 cells

Previous studies have confirmed that the beclin 1 complex plays a key role in the initial stage of autophagy and deregulated autophagy might involve in amyotrophic lateral sclerosis. However, the mechanism underlying altered autophagy associated with the beclin 1 complex remains un- clear. In this study, we transfected the Cu/Zn superoxide dismutase 1 G93A mutant protein into the motor neuron-like cell line NSC34 cultured in vitro. Western blotting and co-immunopre- cipitation showed that the Cu/Zn superoxide dismutase 1 G93A mutant enhanced the turnover of autophagic marker microtubule-associated protein light chain 3II （LC3Ⅱ） and stimulated the conversion of EGFP-LC3Ⅰ to EGFP-LC3Ⅱ, but had little influence on the binding capacity of the autophagy modulators ATG14L, rubicon, UVRAG, and hVps34 to beclin 1 during auto- phagosome formation. These results suggest that the amyotrophic lateral sclerosis-linked Cu/Zn superoxide dismutase I G93A mutant can upregulate autophagic activity in NSC34 cells, but that this does not markedly affect beclin 1 complex components.

Identification and Genetic Analysis of a Novel Allelic Variation of Brittle-1 with Endosperm Mutant in Maize

Endosperm mutants are critical to the studies on both starch synthesis and metabolism and genetic improvement of starch quality in maize.In the present study,a novel maize endosperm mutant A0178 of natural variation was used as the experimental material and identified and then characterized.Through phenotypic identification,genetic analysis,main ingredients measurement and embryo rescue,development of genetic mapping population from A0178,the endosperm mutant gene was located.The results showed that the mutant exhibited extremely low germination ability as attributed to the inhibited embryo development,and amounts of sugars were accumulated in the mutant seeds and more sugars content was detected at 23 days after pollination(DAP)in A0178 than B73.Employing genetic linkage analysis,the mutant trait was mapped in the bin 5.04 on chromosome 5.Sequence analysis showed that two sites of base transversion and insertion presented in the protein coding region and non-coding region of the mutant brittle-1(bt1),the adenylate translocator encoding gene involved in the starch synthesis.The single base insertion in the coding region cause frameshift mutation,early termination and lose of function of Brittle-1(BT1).All results suggested that bt1 is a novel allelic gene and the causal gene of this endosperm mutant,providing insights on the mechanism of endosperm formation in maize.

Oncogenic potential of IDH1R132C mutant incholangiocarcinoma development in mice

AIM: To investigate whether IDH1R132 C mutant in combination with loss of p53 and activated Notch signaling promotes intrahepatic cholangiocarcinoma(ICC) development.METHODS: We applied hydrodynamic injection and sleeping beauty mediated somatic integration to induce loss of p53(via sh P53), activation of Notch [via intracellular domain of Notch1(NICD)] and/or overexpression of IDH1R132 C mutant together with the sleeping beauty transposase into the mouse liver. Specifically, we co-expressed sh P53 and NICD(sh P53/NICD, n = 4), sh P53 and IDH1R132C(sh P53/IDH1R132 C, n = 3), NICD and IDH1R132C(NICD/IDH1R132 C, n = 4), as well as NICD, sh P53 and IDH1R132C(NICD/sh P53/IDH1R132 C, n = 9) in mice. Mice were monitored for liver tumor development and euthanized at various time points. Liver histology was analyzed by hematoxylin and eosin staining. Molecular features of NICD/sh P53/IDH1R132 C ICC tumor cells were characterized by Myc tag, Flag tag, Ki-67, p-Erk and p-AKT immunohistochemical staining. Desmoplastic reaction in tumor tissues was studied by Picro-Sirius red staining.RESULTS: We found that co-expression of sh P53/NICD, sh P53/IDH1R132 C or NICD/IDH1R132 C did not lead to liver tumor formation. In striking contrast, coexpression of NICD/sh P53/IDH1R132 C resulted in ICC development in mice(P < 0.01). The tumors could be identified as early as 12 wk post hydrodynamic injection. Tumors rapidly progressed, and by 18 wk post hydrodynamic injection, multiple cystic lesions could be identified on the liver surface. NICD/sh P53/IDH1R132 C liver tumors shared multiple histological features of human ICCs, including hyperplasia of irregular glands. Importantly, all tumor cells were positive for the biliary epithelial cell marker cytokeratin 19. Extensive collagen fibers could be visualized in tumor tissues using Sirus red staining, duplicating the desmoplastic reaction observed in human ICC. Tumors were highly proliferative and expressed ectopically injected genes. Together these studies supported that NICD/sh P53/IDH1R132 C liver tumors were indeed ICCs. Finally, no p-AKT or p-ERK positive staining was observed, suggesting that NICD/sh P53/IDH1R132 C driven ICC development was independent of AKT/m TOR and Ras/MAPK signaling cascades. CONCLUSION: We have generated a simple, nongermline murine ICC model with activated Notch, loss of p53 and IDH1R132 C mutant. The study supported the oncogenic potential of IDH1R132 C.

Study on Screening of TaGA2ox1 Mutants in Wheat by Ion Beam Irradiation

As a kind of mutagen, ion beam irradiation can create abundant biological mutations. A population of about 2000 lines was generated by irradiating dry wheat seeds of XiaoYan 81 with low-energy nitrogen ion beams. The traits of the plant, such as height, spike type, fertility, stem color and awn length, were investigated. The mutation rate in terms of the plant height in M2 was 2.9%. Eighteen deletion mutants of TaGA2ox1 were obtained. Associate analysis showed that TaGA2ox1 was closely related to the plant height. Most of the TaGA2ox1-deleted mutants were higher than the control, suggesting that the biological function of TaGA2ox1 is similar to its homologues in other plants. These results demonstrate that ion beam irradiation is an efficient tool in the construction of a mutant library for wheat.

Expression and Subcellular Localization of Recombinant SDF-1 and Its Mutant Intrakine in Transfected COS-7 Cells

Objective:This paper is to explore a method of transferring human SDF-1 and its mutant SDF-154 intrakine gene into COS-7 cells for determining their expression and subcelluar localization of the fusion protein.This could offer feasibility for inhibiting the metastasis of malignant tumors by phonotypic knockout for blocking functional expression of receptor on the cell-surface.Methods:Amplify the target gene with PCR from the constructed plasimid SDF-WT-Gly×4-DecPET-30a(+) with a C-terminal retention signal fragment KDEL. After the pcDNA3.1 SDF-1KDEL,pcDNA3.1 SDF-154KDEL,pEGFPSDF-1KDEL and pEGFPSDF-154KDEL eukaryotic expression vectors were constructed and the DNA sequence was accurate,they were transferred into COS-7 cells with liposome . The exogenous expressions were observed, fusion protein SDF-1His and SDF-154His were confirmed by Western blot,and the SDF-1EGFP and SDF-154EGFP were determined by Laser Scanning Confocal Microscopy. Results:Four expression vectors were constructed successfully, the fusion protein SDF-1 KDELHis and SDF-1 54 KDELHis expressed in COS-7 cells.Subcelluar localization analysis showed that SDF-1KDELEGFP and SDF-154KDELEGFP were located mainly in endoplasmic reticulum.Conclusion:Four expression vectors pcDNA3.1 SDF-1KDEL, pcDNA3.1SDF-154KDEL, pEGFPSDF-1KDEL and pEGFPSDF-154KDEL were constructed successfully, which could express in eukaryotic cell and locate mainly in the endoplasmic reticulum .

水稻黄化早抽穗突变体hz1的基因鉴定及功能分析

【目的】水稻的抽穗期对水稻地域适应性及水稻产量至关重要,对水稻抽穗期基因进行鉴定及功能分析,可以为水稻育种提供优异的基因资源。【方法】通过BSA-seq方法对一个黄化早抽穗突变体hz1(huangzao1)进行基因定位克隆及连锁分析;利用RT-qPCR技术分析目的基因HZ1的表达谱,并用水稻原生质体瞬时转化查明HZ1的亚细胞定位;对突变体的抽穗期、叶绿素含量、过氧化氢含量等生理指标进行测定,详细分析其表型变化。【结果】田间表型观察发现hz1表现早抽穗,长日照(long-day,LD)及短日照(short-day,SD)条件下hz1的抽穗期相同,分别比野生型(wild type,WT)早抽穗43 d和26 d,表明hz1是一个光周期不敏感的突变体。同时hz1表现黄化表型,相比WT,叶绿素含量下降。遗传分析表明hz1由隐性单基因控制,F2混池高通量测序将目的基因定位于水稻第6染色体上17.8 Mb区间内,分析发现该区间内一个T-DNA插入位点LOC_Os06g40080与hz1目标性状完全连锁,LOC_Os06g40080为已知的SE5基因,编码血红素加氧酶1(heme oxygenase 1,HO1)。HZ1/SE5在叶片中高表达,在LD及SD条件下具有昼夜节律性表达。亚细胞定位发现HZ1/SE5蛋白定位于叶绿体中。表达调控分析表明HZ1/SE5主要通过调控水稻成花素Hd3a和RFT1的表达来调控水稻的抽穗期;并通过调控叶绿素合成途径相关基因的表达水平影响水稻叶绿素水平变化。【结论】黄化早抽穗突变体hz1由于血红素加氧酶编码基因SE5突变导致其对光周期不敏感,HZ1/SE5基因通过调控水稻成花素基因及叶绿素合成途径相关基因的表达而影响水稻的抽穗期及叶片的黄化。

Screening proteins that interact with mutant superoxide dismutase 1 from familial amyotrophic lateral sclerosis using a yeast two-hybrid system

The present study screened a human fetal brain cDNA library to find the proteins that interact with mutant superoxide dismutase 1 （SOD1） using a yeast two-hybrid system. Using BLAST software, 15 real proteins which interacted with mutant SOD1 were obtained, including 8 known proteins （protein tyrosine-phosphatase non-receptor type 2, TBCl D4, protein kinase family, splicing factor, arginine/serine-rich 2, SRC protein tyrosine kinase Fyn, β-sarcoglycan; glycine receptor a2, microtubule associated protein/microtubule affinity-regulating kinase 1, ferritin H chain）, and 7 unknown proteins. Results demonstrated interaction of mutant SOD1 with microtubule associated protein/microtubule affinity-regulating kinase 1 and β-sarcoglycan.

HSV-1突变株M6感染人支气管上皮细胞后对巨噬细胞介导的免疫反应的影响

目的探究1型单纯疱疹病毒(herpes simplex virus type 1,HSV-1)突变株M6感染人支气管上皮细胞(16HBE细胞)后对巨噬细胞介导的免疫反应的影响。方法用HSV-1感染16HBE细胞分析培养液中细胞因子的变化;将巨噬细胞与被HSV-1毒株感染的16HBE细胞的上清液共培养并通过尾静脉回输至小鼠体内,分别在第1、3、7、28、56、90天对小鼠淋巴结细胞因子表达水平、脾脏T细胞比例变化、小鼠中和抗体表达水平以及特异性T细胞反应进行检测。结果16HBE细胞被HSV-1突变株感染后,上清液中募集和激活巨噬细胞相关的细胞因子均较高水平表达但略低于野毒株组;尾静脉回输实验后,突变株组小鼠淋巴结炎症因子、趋化因子和T细胞的比例随时间发生了不同的变化,并引起了弱于野毒株组的体液免疫和强于野毒株组的特异性T细胞免疫反应,且仅极少数与野毒株组具有显著性差异(P<0.05)。结论16HBE细胞被HSV-1突变株M6感染后能够释放募集和激活巨噬细胞的细胞因子,使巨噬细胞携带HSV-1突变株的特异性活化信息,激活了宿主的免疫系统,诱导了宿主的体液免疫和细胞免疫。

蜂毒肽Protopolybia-MPⅢ及其优化突变体对HSV-1病毒复制周期不同阶段的抑制活性研究

目的:研究蜂毒肽Protopolybia-MPⅢ及其优化突变体MPⅢ-3/4/7/10/14在体外对Ⅰ型单纯疱疹病毒(HSV-1)复制周期不同阶段的抑制活性。方法:通过qPCR技术和多肽分阶段孵育平台,检测蜂毒肽Protopoly⁃bia-MPⅢ及5个优化突变体在Vero细胞内对HSV-1感染的预防作用,以及其对HSV-1复制周期不同阶段的影响。结果:Protopolybia-MPⅢ多肽突变体MPⅢ-4/10/14预处理Vero细胞后去除上清,能限制HSV-1感染。进一步通过多肽抗病毒作用阶段分析实验,发现野生型多肽Protopolybia-MPⅢ主要作用于HSV-1复制周期的吸附阶段,而MPⅢ-3/14主要作用于病毒复制周期的进入/融合以及进入后阶段,MPⅢ-4/7主要作用于病毒复制周期的吸附以及进入/融合阶段,MPⅢ-10主要作用于病毒复制周期的吸附以及进入后阶段。结论:本工作明确了蜂毒肽Protopolybia-MPⅢ及其突变体MPⅢ-3/4/7/10/14对HSV-1复制周期不同阶段的抑制活性,初步阐明了Protopolybia-MPⅢ多肽优化突变体抗病毒活性提高的原因,为胡蜂抗病毒多肽的分子设计和药用研究奠定基础。

低级别胶质瘤异柠檬酸脱氢酶-1基因分型与磁共振表观弥散系数、血管内皮生长因子表达的关系

目的探讨低级别胶质瘤病人异柠檬酸脱氢酶-1(IDH-1)基因分型与磁共振表观弥散系数(ADC)、血管内皮生长因子(VEGF)表达的关系。方法纳入新疆医科大学附属肿瘤医院2021年6月至2023年5月收治的低级别脑胶质瘤病人52例开展回顾性研究,病人术前均接受磁共振弥散加权成像检查,经手术病理与WHO中枢神经系统肿瘤分级标准证实为低级别脑胶质瘤,根据IDH-1分型结果分成突变型组29例、野生型组23例。比较两组最小ADC值(ADC_(min))、平均ADC值(ADC_(mean))、最小相对ADC值(rADC_(min))、平均相对ADC值(rADC_(mean))。绘制受试者操作特征曲线(ROC曲线)分析ADC值对IDH-1分型的鉴别价值。分析病人IDH-1分型与VEGF表达的关系,比较不同VEGF表达病人的ADC值。结果突变型组ADC_(min)、ADC_(mean)、rADC_(min)、rADC_(mean)较野生型组增高(P<0.05)。ADC_(min)、ADC_(mean)、rADC_(min)、rADC_(mean)鉴别IDH-1分型的曲线下面积(AUC)分别为0.77(灵敏度75.86%,特异度73.91%)、0.79(灵敏度82.76%,特异度78.26%)、0.76(灵敏度79.31%,特异度78.26%)、0.77(灵敏度79.31%,特异度82.61%)。突变型组VEGF阳性率为13.79%,低于野生型组的47.83%(P<0.05)。VEGF阴性/弱阳性组ADC_(min)、ADC_(mean)、rADC_(min)、rADC_(mean)高于阳性组(P<0.05)。结论低级别脑胶质瘤IDH-1突变者的ADC_(min)、ADC_(mean)、rADC_(min)、rADC_(mean)相对高,ADC参数对其IDH-1分型具有鉴别价值,且IDH-1分型与VEGF表达相关。

水稻半矮秆基因iga-1的鉴定及精细定位

在前期通过空间诱变获得半矮秆隐性突变基因iga-1的基础上,进一步对iga-1进行鉴定。农艺性状调查表明携带iga-1的矮秆株系CHA-2、CHA-2N与原种特籼占13相比存在明显变异。节间长度测量显示CHA-2、CHA-2N节间比例正常,属dn型。外源GA3处理、内源GA3测定和α-淀粉酶活性检测揭示iga-1与GA3调控无关。利用CHA-2与粳稻品种02428杂交获得的F2群体将iga-1定位在水稻第5染色体两个InDel标记DL18和DL19间32.01kb的物理距离内。该区域有5个阅读框架,其中包括赤霉素信号传导调控基因D1。序列分析表明CHA-2、CHA-2N和特籼占13在D1位点上基因组序列不存在差异,推测D1并非iga-1的候选基因。比较水稻第5染色体上其他矮秆基因发现iga-1可能与半矮秆基因sd-7来自同一位点。

羊种布鲁氏菌Rev.1疫苗株VirB12基因缺失株的构建及鉴定

为获得毒力较弱且能够区分疫苗免疫与自然感染的羊种布鲁氏菌候选疫苗株,本研究构建羊种布鲁氏菌Rev.1疫苗株VirB12基因缺失突变株。分别扩增Rev.1疫苗株VirB12基因上下游同源臂序列以及卡那霉素抗性基因,采用融合PCR方法将3个基因片段连接构建突变盒,连接至pMD19-T载体,电转化入布鲁氏菌Rev.1感受态细胞筛选阳性克隆,获得Rev.1-ΔVirB12突变株。Rev.1-ΔVirB12连续传代15代未发生回复突变。羊种布鲁氏菌疫苗株Rev.1-ΔVirB12的构建为羊种布鲁氏菌疫苗研制奠定了基础。

假单胞菌XN-1硝基苯降解性质粒的提取及研究

假单胞菌XN 1对有机污染物硝基苯具有降解性 ,并且对氨苄青霉素具有抗性。检测和提取了假单胞菌XN 1细胞内的质粒 ,得到了一个约 2 2kb大小的质粒pXN 1。质粒消除实验证实这个质粒与硝基苯降解性有关 ,而与抗生素抗性无关。XN 1和其自发突变株XN 1 2和XN 1 3特性的差异和质粒检测的差异之间存在对应关系 ,并且得到了一个比 pXN 1小几个kb的衍生质粒 pXN 1 3。

荧光假单胞菌M18的rpoS基因克隆及其功能分析

从荧光假单胞菌 (Pseudomonasfluorescentsp .)M1 8基因组中克隆了RNA聚合酶的稳定期σs 因子编码基因rpoS ,推测其氨基酸序列与铜绿假单胞菌、荧光假单胞菌和恶臭假单胞菌的同源性分别为 99 1 %、87 35 %和87 8%。利用体外定点插入突变和同源重组技术 ,构建了M1 8的rpoS突变株M1 8R- 。对突变株M1 8R- 合成抗生素吩嗪 1 羧酸 (PCA)和藤黄绿菌素 (Plt)的动力学分析结果表明 ,在KB或PPM培养基中 ,突变株合成PCA的能力比野生型分别提高了 2 5或 5 78倍 ,但Plt的积累量不受影响。与野生型相比 ,突变株对碳源饥饿的耐性下降。同时 ,在碳源饥饿条件下对过氧化氢、乙醇和和氯化钠等环境胁迫的交叉保护性减小 。