CD8 positive T cells express IL-17 in patients with chronic obstructive pulmonary disease

Background

Chronic obstructive pulmonary disease (COPD) is a progressive and irreversible chronic inflammatory disease of the lung. The nature of the immune reaction in COPD raises the possibility that IL-17 and related cytokines may contribute to this disorder. This study analyzed the expression of IL-17A and IL-17F as well as the phenotype of cells producing them in bronchial biopsies from COPD patients.

Methods

Bronchoscopic biopsies of the airway were obtained from 16 COPD subjects (GOLD stage 1-4) and 15 control subjects. Paraffin sections were used for the investigation of IL-17A and IL-17F expression in the airways by immunohistochemistry, and frozen sections were used for the immunofluorescence double staining of IL-17A or IL-17F paired with CD4 or CD8. In order to confirm the expression of IL-17A and IL-17F at the mRNA level, a quantitative RT-PCR was performed on the total mRNA extracted from entire section or CD8 positive cells selected by laser capture microdissection.

Results

IL-17F immunoreactivity was significantly higher in the bronchial biopsies of COPD patients compared to control subjects (P < 0.0001). In the submucosa, the absolute number of both IL-17A and IL-17F positive cells was higher in COPD patients (P < 0.0001). After adjusting for the total number of cells in the submucosa, we still found that more cells were positive for both IL-17A (P < 0.0001) and IL-17F (P < 0.0001) in COPD patients compared to controls. The mRNA expression of IL-17A and IL-17F in airways of COPD patients was confirmed by RT-PCR. The expression of IL-17A and IL-17F was co-localized with not only CD4 but also CD8, which was further confirmed by RT-PCR on laser capture microdissection selected CD8 positive cells.

Conclusion

These findings support the notion that Th17 cytokines could play important roles in the pathogenesis of COPD, raising the possibility of using this mechanism as the basis for novel therapeutic approaches.     

重组人IL-17A和IL-17F的制备方法及活性测定

人IL-17A和IL-17F具有很高的同源性,在炎症性疾病、自身免疫性疾病和肿瘤中都发挥着重要的作用,是当前研究的热点.应用原核表达系统在大肠杆菌BL21(DE3)中高效表达了人IL-17A和IL-17F;经培养条件的优化,未发现可溶性目的蛋白的表达,免疫印记分析显示,重组蛋白位于包涵体中;对包涵体进行洗涤、凝胶过滤层析纯化和柱上复性,获得重折叠的可溶性蛋白;随后用SDS-PAGE对蛋白样品进行了纯度分析、采用免疫印记和质谱的方法鉴定蛋白产物成分、用ME3T3-E1和RAW264.7两个细胞株对IL-17A、IL-17F的生物学活性进行测定.结果显示,柱上复性的方法制备的谊重组蛋白具有较高的纯度和活性.建立的重组人IL-17A和IL-17F的制备方法可为相关研究中细胞因子的大量应用提供参考.     

The in vivo metabolism of 7 beta, 17-dimethyltestosterone-6,7-3H.

7 beta, 17-Dimethyltestosterone (17 beta-hydroxy-7 beta, 17-dimethyl-4-androsten-3-one) (I) was given to three subjects in oral doses of 400 mg per day for ten days. The initial dose contained the steroid tritiated in the 6 and 7 positions. Plasma levels and urinary excretion patterns were followed in all three subjects. Isolations were done on the urine, plasma, and stools of one patient. From the urine 7 beta, 17-dimethyl- 5 alpha-androstane-3 beta,17 beta-diol (VI) was isolated from the nonhydrolyzed fractions. Unchanged (I), 7 beta,17-dimethyl-5 beta-androstane-3 alpha,17 beta-diol (III) and 7 beta, 17-dimethyl-5 beta-androstane-3 beta,17 beta-diol (IV) were isolated from the nonhydrolyzed and enzyme-hydrolyzed fractions. 7 beta,17-dimethyl-5 alpha-androstane-3 alpha,17 beta-diol (V) was isolated from the enzymatic fractions. From the stools were isolated unchanged (I), (III), (IV), (V), and (VI). Unchanged (I) and its 5 alpha-dihydro derivative (17 beta-hydroxy-7 beta,17-dimethyl-5 alpha-androstan-3-one) (II) were identified in the plasma. The total recovery of radioactivity in the one patient on whom the isolations were done was 57%; 40% from the urine and 17% from the stools.     

Effects of novel 17alpha-hydroxylase/C17, 20-lyase (P450 17, CYP 17) inhibitors on androgen biosynthesis in vitro and in vivo

Aiming at the development of new drugs for the treatment of prostate cancer, the effects of steroidal compounds and one non-steroidal substance on androgen biosynthesis were evaluated in vitro and in vivo. Sa 40 [17-(5-pyrimidyl)androsta-5,16-diene-3beta-ol], its 3-acetyl derivate Sa 41 and BW 19 [3,4-dihydro-2-(4-imidazolylmethyl)-6-methoxy-1-methyl-naphthalene] are compounds from our group, which have been developed as inhibitors of CYP 17 (17alpha-hydroxylase-C17, 20-lyase, the key enzyme in androgen biosynthesis). They have been compared with CB 7598 [abiraterone: 17-(3-pyridyl)androsta-5,16-diene-3beta-ol], its 3-acetyl compound CB 7630 and ketoconazole, compounds which already have been used clinically. The most potent compound toward human CYP 17 (testicular microsomes) was Sa 40 (IC(50) value of 24 nM), followed by Sa 41, CB 7598, BW 19, CB 7630 and ketoconazole. Sa 40 shows a type II difference spectrum and a non-competitive type of inhibition (K(i) value of 16 nM). No recovery of enzyme activity was observed after preincubation of CYP 17 with Sa 40 and subsequent charcoal treatment. In Escherichia coli cells coexpressing human CYP 17 and NADPH-P450 reductase, Sa 40 was more active than CB 7598 and BW 19, whereas the acetyl compounds were not active. The latter three compounds were equally active towards rat CYP 17. Male Sprague-Dawley (SD) rats were administered daily for 14 days BW 19 and the acetyl derivatives Sa 41 and CB 7630 as prodrugs (0.1 mmol/kg intraperitoneally). The test compounds strongly reduced plasma testosterone concentration, as well as prostate and seminal vesicles weights. They showed moderate inhibitory effects on the weights of levator ani, bulbocavernosus and testes, whereas they led to an increase in adrenal and pituitary weights. The only exception was BW 19 which did not change pituitary weights. Based on its superiority on the human enzyme, it was concluded that Sa 40 in its 3beta-acetate form (Sa 41) could be a promising candidate for clinical evaluation.     

Quantification of the neuromuscular blocking agent rocuronium and its putative metabolite 17-desacetylrocuronium in heparinized plasma by capillary gas chromatography using a nitrogen sensitive detector

We have developed a sensitive and specific capillary GC (cGC) assay for the quantification of the quarternary aminosteroidal compound rocuronium (roc), a neuromuscular blocking agent, and its putative metabolite 17-desacetylrocuronium (17OH-roc), using 3-desacetylvecuronium (3OH-vec) as an internal standard (I.S.). This novel method has been applied to a pharmacokinetic study with roc, monitoring sixty patients who were classified according to four different body mass index (BMI) groups. The isolation of these drugs from plasma was carried out using a dichloromethane liquid-liquid extraction after ion-pairing of the positively charged ammonium compounds with iodide. To achieve thermal stability, tert.-butyldimethylsilyl-ethers were formed at the 3OH- and 17OH-steroidal positions by reaction with N-methyl-N-(tert.-butyldimethylsilyl)-trifluoroacetamide at 70°C overnight. An automated cGC system fitted with a nitrogen sensitive detector with a specially prepared glass phase bead and a computer controlled data handling system was used to analyze and quantify the compounds, which were separated on a DB1 capillary column with helium as the carrier gas and a temperature program ranging from 120 to 300°C. The method is linear for 50-6400 ng/ml for roc and 80-6400 ng/ml for 17OH-roc. The detection limits were 10 ng/ml for roc and 50 ng/ml for 17OH-roc. The lower limit of quantification was 50 ng/ml for roc and 80 ng/ml for 17OH-roc. Intra-assay coefficients of variation (C.V.s) were 10% and 15% and the inter-assay C.V.s 8-18% and 16-21% for roc and 17OH-roc, respectively.     

利用反义RNA技术分析春化相关基因VER17在冬小麦花发育过程中的功能

为了研究小麦春化相关基因VER17的功能,应用反义RNA技术,将VER17基因的反义片段构建到载体pBI121上,通过花粉管通道法获取转基因小麦.对T0代转基因植株GUS染色以及PCR等分子鉴定,得到14株含反义VERJ7基因片段的阳性转基因植株.对T0代和T1代的表型观察结果显示,VER17反义转基因植株开花时间延迟,并且穗的顶部和基部小花出现明显的退化.表明春化相关基因VER17在小麦发育过程中可能起到促进植物开花以及穗顶端和基部花发育的作用,减少小花退化,同时对雄蕊的发育也有影响.     

Potential role of myeloid cell/eosinophil-derived IL-17 in LPS-induced endotoxin shock

IL-17RA is a shared receptor subunit for several cytokines of the IL-17 family, including IL-17A, IL-17C, IL-17E (also called IL-25) and IL-17F. It has been shown that mice deficient in IL-17RA are more susceptible to sepsis than wild-type mice, suggesting that IL-17RA is important for host defense against sepsis. However, it is unclear which ligands for IL-17RA, such as IL-17A, IL-17C, IL-17E/IL-25 and/or IL-17F, are involved in the pathogenesis of sepsis. Therefore, we examined IL-17A, IL-17E/IL-25 and IL-17F for possible involvement in LPS-induced endotoxin shock. IL-17A-deficient mice, but not IL-25- or IL-17F-deficient mice, were resistant to LPS-induced endotoxin shock, as compared with wild-type mice. Nevertheless, studies using IL-6-deficient, IL-21Rα-deficient and Rag-2-deficient mice, revealed that neither IL-6 and IL-21, both of which are important for Th17 cell differentiation, nor Th17 cells were essential for the development of LPS-induced endotoxin shock, suggesting that IL-17A-producing cells other than Th17 cells were important in the setting. In this connection, IL-17A was produced by macrophages, DCs and eosinophils after LPS injection. Taken together, these findings indicate that IL-17A, but not IL-17F or IL-25, is crucial for LPS-induced endotoxin shock. In addition, macrophages, DCs and eosinophils, but not Th17 cells or γδ T cells, may be sources of IL-17A during LPS-induced endotoxin shock.     

利用混合样本池法对鸡显性白羽基因PMEL17突变位点的检测

显性白羽基因座是影响鸡羽色形成的重要基因座位之一, 该基因座上的显性等位基因I 会抑制黑色素合成, 从而使携带该基因的个体全身羽毛呈现白色。目前已确认鸡显性白羽基因座编码PMEL17蛋白: 是一种黑素细胞特异性蛋白, 在黑素细胞的分化与成熟中起到重要作用, 并证明PMEL17基因的突变与显性白羽的形成有关。文章利用混合样本池建立了一种低成本、高效率, 并能在大规模群体中检测PMEL17基因突变的方法, 称为PCR产物混合样本池法。该方法的基本步骤如下: 首先, 提取个体基因组DNA, 并设计相关引物对每一个体单独进行PCR扩增; 其次, 将PCR产物等比例混合, 10个样品混在一个池中; 然后, 将PCR产物混合池样品于非变性聚丙烯酰胺凝胶上进行电泳; 最后, 待电泳结束后进行银染, 根据凝胶上所显条带判定是否存在突变体。此外, 文章还将这种方法与传统基因组DNA混合样本池法进行了比较试验, 并利用该方法对试验鸡群显性白羽基因PMEL17突变进行检测, 证实该方法具有较高准确度。     

IL-23/IL-17轴在脓毒症中的表达及意义

目的:探讨IL-23/IL-17轴在脓毒症患者中的表达及意义.方法:符合诊断标准的脓毒症患者40例,以28天预后为终点,将患者分为存活组(n=21)和病死组(n=19),分析各组病人的急性生理和慢性健康评分(APACHE)Ⅱ和序贯器官衰竭估计(SOFA)评分,同时在入ICU第1天采取外周静脉血做IL-23和IL-17检测,并对病死率和IL-23、IL-17、APACHEⅡ、SOFA做相关性分析.结果:与存活组比较,病死组患者拥有较高的APACHEⅡ和SOFA评分(P<0.01),且外周血的IL-23和IL-17蛋白含量均明显升高(P<0.05).APACHEⅡ和SOFA评分、IL-17和IL-23含量与28天预后有明显的相关性(P<0.05).结论:脓毒症Th17细胞分泌的IL-23/IL-17增加,加重患者病情,在脓毒症发病机制中可能扮演重要角色.     

Cytochrome P450c17α 5′-untranslated region *T/C polymorphism in endometriosis

Estrogen plays a role in the pathogenesis of endometriosis. The CYP17 gene codes for the cytochrome P450c17α enzyme that is involved in the estrogen biosynthesis. We aimed to investigate if CYP17 polymorphism could be used as marker to predict the susceptibility of endometriosis. Women were divided into two groups: (1) severe endometriosis (n=119); (2) non-endometriosis groups (n=128). A 169-bp fragment encompassing the T/C polymorphic site in 5′-untranslated promoter region (5′-UTR) of the CYP17 was amplified by the polymerase chain reaction, treated with restriction enzyme MspA1I, and electrophoresis. The polymorphism was divided into restriction-enzyme indigestible (T homozygote), T/C heterozygote, and digestible (C homozygote). Genotypes and allelic frequencies for this polymorphism in both groups were compared. We observed a higher but non-significant percentage of T homozygote in the endometriosis women compared with the non-endometriosis women. Proportions of T homozygote/heterozygote/C homozygote for CYP17 in both groups were: (1) 26.1/46.2/27.7% and (2) 17.2/45.3/37.5% (p-value=0.131). T allele was related with higher susceptibility of endometriosis. T and C allele frequencies in both groups were: (1) 49.2/50.8%; (2) 39.8/60.2% (p-value=0.046). Despite the CYP17* T allele appearing to be asscoiatd with a trend of increased risk of endometriosis, CYP17 5′-UTR gene polymorphism might not be a useful marker for prediction of endometriosis susceptibility.     

Adequacy of saliva 17-hydroxyprogesterone determination using various collection methods

Steroids determination in saliva offers several advantages. The collection of saliva is a noninvasive, less stressful technique than blood withdrawal and reflects the circulating unbound fractions. The suitability of saliva for 17-hydroxyprogesterone and cortisol determinations has been documented in healthy subjects as well as in diseases like Congenital Adrenal Hyperplasia and Cushing syndrome. The aim of the study was to compare the influence of different collection methods on the results of 17-hydroxyprogesterone measurement in saliva collected by different ways, using commercially available RIAs developed for plasma. 17-hydroxyprogesterone was determined in 64 healthy adult volunteers (30 males, 34 females) in serum (Group SE) and in saliva collected before meals at 8-10 p.m. by directly spitting into a plastic tube (Group SP), using a cotton swab (Group SA) and using a polyester swab Salivette (Group SB). We used a commercially available direct radioimmunoassay without separation technique. The 17-hydroxyprogesterone mean values (ng/ml) were 1.16+/-1.3 (Group SE), 0.056+/-0.046 (Group SP), 0.089+/-0.048 (Group SA) and 0.058+/-0.049 (Group SB). The detection limit was 0.010 ng/ml. The correlations between the values in serum (Group SE) and in saliva were: r=0.77, p<0.05 (Group SP); r=0.62, p<0.05 (Group SA); r=0.70, p<0.05 (Group SB). The saliva values corresponding to the serum cut-off point of 3 ng/ml upper limit of normal values were in ng/ml 0.13 (Group SP), 0.16 (Group SA) and 0.11 (Group SB). In conclusion, 17-hydroxyprogesterone determinations in saliva using commercially available RIAs primarily developed for serum, is a reliable and easy to perform procedure. The three different methods of saliva collection showed 17-hydroxyprogesterone concentrations to have good agreement.     

The prevalence of Th17 cells in patients with gastric cancer

Th17 cells have emerged as an important mediator in inflammatory and autoimmune diseases. However, recent studies suggest a potential impact of Th17 cells on tumor. The current study was designed to investigate the possible involvement of Th17 cells in gastric cancer. Compared with healthy volunteers, patients with gastric cancer had a higher proportion of Th17 cells in peripheral blood. Notably, the increased prevalence of Th17 cells was associated with clinical stage. In addition, increased populations of Th17 cells were present in tumor-draining lymph nodes with advanced disease. Furthermore, the mRNA expression levels of Th17-related factors (IL-17, IL-23p19, and RORC) in tumor tissues and the serum concentrations of IL-17 and IL-23 cytokines were significantly increased in patients with advanced gastric cancer. The results indicate that Th17 cells may contribute to gastric cancer pathogenesis.     

Developmental changes of serum steroids produced by cytochrome P450c17 in rat

Serum levels of 17-hydroxypregnenolone, dehydroepiandrosterone, 17-hydroxyprogesterone, and androstenedione were measured during the postnatal development of rats 1-14 weeks of age. A significant decrease in the serum levels of these steroids with increasing age was observed, using multiple regression analysis: 17-hydroxypregnenolone (beta= -1.56, S.E.= 0.25, P < 0.00001), dehydroepiandrosterone (beta= -0.43, S.E.= 0.07, P < 0.00001), 17-hydroxyprogesterone (beta= -2.51, S.E.= 0.45, P < 0.00001), and androstenedione (beta= -1.63, S.E.= 0.33, P < 0.00001). A sex-related difference was not found. The observed decline in the serum levels of the steroids was directly proportional to the previously reported decrease in mRNA expression and enzyme activity of cytochrome P450c17 in the rat liver. Yet, despite this decrease to undetectable levels in liver after 7-8 weeks, significant amounts of 17-hydroxypregnenolone, 17-hydroxyprogesterone, dehydroepiandrosterone, and androstenedione were still observed in the rat serum. This may partly be due to the mRNA expression of cytochrome P450c17 in tissues other than the liver, such as the testis and/or duodenum, after 4 weeks of age. Serum levels of pregnenolone, progesterone, and corticosterone in the developing rats were also examined.     

Interleukin-17 as an effector molecule of innate and acquired immunity against infections

Interleukin (IL)-17 is a proinflammatory cytokine which induces differentiation and migration of neutrophils through induction of cytokines and chemokines including granulocyte-colony stimulating factor and CXCL8/IL-8. IL-17-producing CD4(+) T cells (Th17) have pivotal role in pathogenesis of autoimmune diseases. IL-17 is also involved in protective immunity against various infections. IL-17 has important role in induction of neutrophil-mediated protective immune response against extracellular bacterial or fungal pathogens such as Klebsiella pneumoniae and Candida albicans. Importance of IL-17 in protection against intracellular pathogens including Mycobacterium has also been reported. Interestingly, not only CD4(+) T cells but atypical CD4(-)CD8(-) T cells expressing T cell receptor (TCR) gammadelta produce IL-17, and IL-17 producing cells participate in both innate and acquired immune response to infections. Furthermore, neutrophil induction may not be the only mechanism of IL-17-mediated protective immunity. IL-17 seems to participate in host defense through regulation of cell-mediated immunity or induction of antimicrobial peptides such as beta-defensins. In this review, we summarize recent progress on the role of IL-17 in immune response against infections, and discuss possible application of IL-17 in prevention and treatment of infectious diseases.     

Androgenic and estrogenic 17beta-hydroxysteroid dehydrogenase/17-ketosteroid reductase in human ovarian epithelial tumors: evidence for the type 1, 2 and 5 isoforms

17β-Hydroxysteroid dehydrogenase/17-ketosteroid reductases (17HSD/KSR) play a key role in regulating steroid receptor occupancy in normal tissues and tumors. Although 17HSD/KSR activity has been detected in ovarian epithelial tumors, our understanding of which isoforms are present and their potential for steroid metabolism is limited. In this investigation, 17HSD/KSR activity from a series of ovarian epithelial tumors was assayed in cytosol and microsomes under conditions which differentiate between isoforms. Inhibition studies were used to further characterize the steroid specificities of isoforms in the two subcellular fractions. Activity varied widely between tumors of the same histopathologic classification. The highest levels of activity were observed in mucinous tumors. Michaelis constants, maximum velocities, estradiol-17β/testosterone (E₂/T) activity ratios and inhibition patterns were consistent with a predominance of microsomal 17HSD/KSR2 and cytosolic 17HSD/KSR5, isoforms reactive with both E₂ and T, with evidence of estrogenic 17HSD/KSR1 in cytosol from some samples. In tumors where activity and mRNA expression were both characterized, Northern blots, PCR and sequence analysis indicated 17HSD/KSR5 was the predominant isoform. The presence of 17HSD/KSR5, which also has both 3-HSD/KSR and 20HSD/KSR activity, and 17HSD/KSR2 which also has 20-HSD activity, could influence not only estrogen and androgen binding but progesterone receptor occupancy, as well, in receptor-containing tumors.     

Genomics of fish IL-17 ligand and receptors: a review

Interleukin-17 (IL-17) is a cytokine family composed of six ligands (A–F). Especially, the IL-17A and IL-17F are best characterized cytokines of IL-17 family cytokine. These are produced by Th17 cells and induce the expression of many mediators of inflammation properties. In addition, the five member of IL-17 receptor family (RA-RE) have been identified in mammals. Although the research on fish IL-17 is a little to date, this review discusses some of the recent advances in research on IL-17 ligand and receptor genes in fish. IL-17 family member was chosen from the fish genome database, and its structure and phylogeny is analyzed in detail. Moreover, invertebrate IL-17 genes are also discussed, and the isolation and current status of fish IL-17 receptor genes are summarized. Comparative genomic analysis of the IL-17 family among mammals, teleost and invertebrates provided new insights. Novel IL-17 ligand (IL-17N) was identified from teleost, moreover it was suggested that IL-17N may be a teleost specific ligand by synteny and phylogenetic analysis. On the other hand, IL-17 receptors are well conserved between mammal and teleost, the five member of IL-17 receptor family: IL-17RA-RE were found on the teleost genome. In addition, the IL-17RA gene was duplicated in tandem on the stickleback and medaka genome. Knowledge about the IL-17 ligand/receptor in fish is very limited. Therefore this review will hopefully encourage future studies of IL-17 in fish.     

白介素17受体

白介素17受体是1995年发现的,与任何已知的受体家族不具同源性,可能属于一类新型的尚未鉴定的受体家族.已有的研究表明可溶性小鼠白介素17受体（smIL-17R）不仅能抑制T细胞的活化,而且在已建立的移植模型中,有抑制异种抗原应答的作用.     

A novel heterodimeric cytokine consisting of IL-17 and IL-17F regulates inflammatory responses

CD4＋ helper T （TH） cells play crucial roles in immune responses. Recently a novel subset of TH cells, termed THIL-17, TH 17 or inflammatory TH （THi）, has been identified as critical mediators of tissue inflammation. These cells produce IL-17 （also called IL-17A） and IL-17F, two most homologous cytokines sharing similar regulations. Here we report that when overexpressed in 293T cells, IL-17 and IL-17F form not only homodimers but also heterodimers, which we name as IL-17A/F. Fully differentiated mouse THi cells also naturally secrete IL-17A/F as well as IL-17 and IL-17F homodimeric cytokines. Recombinant IL-17A/F protein exhibits intermediate levels of potency in inducing IL-6 and KC （CXCL 1） as compared to homodimeric cytokines. IL-17A/F regulation of IL-6 and KC expression is dependent on IL-17RA and TRAF6. Thus, IL-17A/F cytokine represents another mechanism whereby T cells regulate inflammatory responses and may serve as a novel target for treating various immune-mediated diseases.     

试论用17荧光雌酮测定雌激素受体和生化法的关系

本文对采用细胞化学法测定乳腺癌内雌激素受体[ER]所用的荧光配体17-FE是否也是与ER上结合位点相结合的问题进行了探讨。在测定17-FE对[~3H]E_2与兔子宫上清液内ER结合的影响后,指出:17-FE对[~3H]E_2与ER的结合具有抑制作用,且其抑制作用随着17-FE浓度的提高而加大。在一系列不同浓度[~3H]E_2下测定其与ER的特异结合,同时测定加入不同浓度17-FE后的特异结合量,以Lineweaver-Burk和Scate-bard法分别作图。分析结果均显示为竞争性抑制曲线,可见17-FE和[~3H]E_2一样是与兔子宫上清液内ER上的结合位点相结合的。因此采用细胞化学法测定ER时,17-FE是一理想的配体。     

逆转座子Tos17的激活与水稻白叶枯病成株抗性的关系

为了研究水稻白叶枯病成株抗性是否与逆转子激活有关,运用SSAP (sequence-specific amplification polymorphism) 对成株抗性品种苗期和成株期接种白叶枯病原菌、清水接种及健康植株的基因组进行了逆转座子扫描。在筛选的约2000个逆转座子基因片段中,9个受苗期生长发育诱导激活,两个受成株期生长发育诱导激活,苗期和成株期各有3个受病原菌诱导激活。苗期生长发育诱导激活产生的逆转座子数目高于成株期,而病原菌诱导产生的逆转座子数目与成株期相当,表明水稻白叶枯病成株抗性可能与生长发育诱导的逆转座子激活相关。