The Evolution of MHC Diversity by Segmental Duplication and Transposition of Retroelements

Sequence analysis of a 237 kb genomic fragment from the central region of the MHC has revealed that the HLA-B and HLA-C genes are contained within duplicated segments peri-B (53 kb) and peri-C (48 kb), respectively, and separated by an intervening sequence (IF) of 30 kb. The peri-B and peri-C segments share at least 90% sequence homology except when interrupted by insertions/deletions including Alu, L1, an endogenous retrovirus, and pseudogenes. The sequences of peri-B, IF, and peri-C were searched for the presence of Alu elements to use as markers of evolution, chromosomal rearrangements, and polymorphism. Of 29 Alu elements, 14 were identified in peri-B, 11 in peri-C, and 4 in IF. The Alu elements in peri-B and peri-C clustered phylogenetically into two clades which were classified as ``preduplication' and ``postduplication' clades. Four Alu J elements that are shared by peri-B and peri-C and are flanked by homologous sequences in their paralogous locations, respectively, clustered into a ``preduplication' clade. By contrast, the majority of Alu elements, which are unique to either peri-B or peri-C, clustered into a postduplication clade together with the Alu consensus subfamily members ranging from platyrrhine-specific (Spqxcg) to catarrhine-specific Alu sequences (Y). The insertion of platyrrhine-specific Alu elements in postduplication locations of peri-B and peri-C implies that these two segments are the products of a duplication which occurred in primates prior to the divergence of the New World primate from the human lineage (35–44 mya). Examination of the paralogous Alu integration sites revealed that 9 of 14 postduplication Alu sequences have produced microsatellites of different length and sequence within the Alu 3′-poly A tail. The present analysis supports the hypothesis that HLA-B and HLA-C genes are products of an extended segmental duplication between 44 and 81 million years ago (mya), and that subsequent diversification of both genomic segments occurred because of the mobility and mutation of retroelements such as Alu repeats. Received: 21 May 1997 / Accepted: 9 July 1997     

Tumour-infiltrating lymphocytes mediate lysis of autologous squamous cell carcinomas of the head and neck

Tumour-infiltrating lymphocytes (TIL) and tumours from six patients with squamous cell carcinomas of the head and neck (SCCHN) were investigated. The six tumours all expressed major histocompatibility complex (MHC) class I antigens both in vivo and as tumor cell lines grown in vitro. In addition, the cancer cells either overexpressed the tumour-suppressor gene product p53 or harboured human papilloma virus 16/18 (HPV). The TIL were expanded in vitro in the presence of interleukin-2, immobilised anti-CD3 mAb and soluble anti-CD28 mAb. Expanded TIL cultures contained both CD4+and CD8+T cells, but generally contained few CD56+CD3-cells of the natural killer (NK) phenotype. CD8+T cells dominated the individual TIL cultures from five of the six patients and showed significant autologous tumour cell lysis. In TIL cultures derived from four of these tumour-reactive TIL cultures, killing could be partially blocked by an anti-MHC class I mAb. TIL cultures reacting with autologous tumour cells also showed strong TCR/CD3-redirected cytotoxicity when assayed against hybridoma cells expressing anti-TCR/CD3 mAb as well as natural-killer(NK)-like activity. A number of TIL cultures devoid of autologous tumour cell lysis were capable of lysing the natural-killer(NK)-sensitive K562 cell line suggesting that the SCCHN cells themselves are resistant to NK-like lysis. In conclusion, TIL cultures from head and neck carcinomas contain T cells which, upon expansion in vitro, can lyse autologous tumour cells in a MHC-class-I-restricted fashion. Thus, the results of the present study document that carcinomas of the head and neck in some patients are infiltrated by cytotoxic T cell precursors potentially capable of rejecting the autologous tumour.     

羊角天麻中的两个新倍半萜

羊角天麻中的两个新倍半萜刘绍华,程菊英（广西植物研究所,桂林５４１００６）吴大刚（中国科学院昆明植物研究所植物化学开放实验室,昆明６５０２０４）关键词羊角天麻;倍半萜;羊角天麻素Ⅰ;羊角天麻素ⅡＴＷＯＮＥＷＳＥＳＱＵＩＴＥＲＰＥＮＥＳＦＲＯＭＤＯＢＩ...     

我国大豆种子中球蛋白2S组分的分离纯化及部分性质的研究

根据大豆种子球蛋白和清蛋白溶解性不同的原理,分离出我国红丰3号大豆种子球蛋白2S粗制剂,再用SephadexG-100柱层析对其进行纯化。纯化后的球蛋白表现SDS-聚丙烯酰胺凝胶电泳非均一性。对这样纯化过的2s球蛋白进行DEAE-纤维素离子交换柱层析分离,用0.1—0.5mol/L pH7.6磷酸盐缓冲液进行线性梯度洗脱,得到四个洗脱峰,每个峰都获得了PAGE单一条带。四个组分分别命名为SⅡP_1,SⅡP_2,SⅡP_3和SⅡP_4。然后对这四种蛋白质的某些性质进行了研究,结果表明四者的分子量按以上顺序分别为22800,21500,19200和17800。所含残基数分别为191,179,163和147个。SⅡP_1,SⅡP_2和SⅡP_3三者的沉降系数(S_(20),w)分别为2.1S,1.9S和1.8S。N-末端分析表明这四种蛋白质的N-末端均为天门冬氨酸.还发现SⅡP_2具有能抑制α-胰凝乳蛋白酶的活性。本实验所提纯的这个抑制剂的一个ATEE(N-乙酰-L-酪氨酸乙酯)单位为0.4μg抑制剂蛋白(仅指对α-chymotrypsin发生作用)。α-chymotrypsin与此抑制剂相互作用时的摩尔数比初步判断为E/I=2/1。     

Patterns of nucleotide substitutions inferred from the phylogenies of the class I major histocompatibility complex genes

Summary Patterns of nucleotide substitutions in human major histocompatibility complex (MHC) class I genes were estimated by using phylogenetic trees of DNA sequences. The pattern is defined as a set of 12 parameters, each of which represents the relative frequency of substitutions from a particular nucleotide to another. The pattern at the antigen recognition sites (ARS) in functional MHC genes was remarkably different from that at the remaining coding region (non-ARS). In particular, the proportion of transitions among all the nucleotide substitutions (P _s) was extremely low at the third codon positions of ARS. In the HLA-A genes, P _s at the third codon positions was only 6% in ARS, whereas it was 69% in non-ARS. In HLA-B, the corresponding values were 30% in ARS and 80% in non-ARS, respectively. On the other hand, P _s in a class I pseudogene (HLA-H) was 57%, which was in good agreement with P _s in other pseudogenes. Because pseudogenes are selectively neutral, the pattern in pseudogenes is regarded as the pattern of spontaneous substitution mutations. In general, the pattern in functional genes that are subject to selective forces deviates from the pattern in pseudogenes. At the third codon positions in coding regions, transitions scarcely cause amino acid replacements, whereas about half of transversions do cause replacements. Accordingly, P _s at the third codon positions decreases if amino acid replacements are accelerated by natural selection but increases if amino acids are conserved by functional constraint. Our observations imply that the ARS region is subject to natural selection favoring amino acid replacements, whereas the non-ARS region is subject to functional constraint. Offprint requests to: T. Gojobori     

Restriction fragment length polymorphism analysis of major histocompatibility complex class II genes from inbred chicken lines

Summary. High molecular weight DNA was extracted from sperm from chickens of 14 inbred lines. The DNA was digested with each of four restriction enzymes ( Pvu II, Hind III, Bg /II, and Bam HI), electrophoresed for 18 or 45h, blotted onto nitrocellulose, and hybridized to a chicken major histocompatibility complex (MHC, B complex) class II β-chain probe (β2-exon specific). Restriction fragment length polymorphisms (RFLPs) were found with each of the restriction enzymes used. Birds with the same B haplotype always showed the same RFLP pattern; however, some birds of different B halotypes also shared the same RFLP pattern. To test for the Mendelian inheritance of the RFLP patterns, the F2 progeny of an informative cross were analysed. The RFLP patterns corresponded with the serologically determined B haplotypes of the F2 birds, thereby showing the Mendelian inheritance of the polymorphic bands.     

云南松形态和叶片碳氮磷化学计量及其海拔变化特征

云南松(Pinus yunnanensis Franch.)是我国西南地区特有的物种,在当地的经济、生态和水土保持功能方面占有重要地位。本研究以云南东北部不同海拔的云南松天然次生林为对象,测定了成年植株的胸径、株高、叶片长度、干重、比叶长及叶片碳、氮、磷含量,分析了不同海拔下叶片碳氮磷化学计量特征。结果表明:随海拔升高,胸径、株高、叶P含量和叶C∶N呈现"中间高,两头低"的趋势,而叶C∶P和N∶P呈现的趋势与叶P和叶C∶N的相反;云南松叶片单束松针长、比叶长、叶C、N随海拔升高呈明显降低的趋势,而单束松针重呈增加的趋势;各海拔的N∶P值(平均值为5.82±0.10)均小于14,且与植株胸径、株高呈显著负相关;该地区云南松对海拔具有较强的适应性,植株生长主要受N元素的营养限制,该结果支持生长速率假说。本研究揭示了云南松化学计量特征的空间格局变化规律,为云南松林的经营管理提供科学依据。     

不同预后脓毒症患者血清降钙素原、C反应蛋白与凝血功能指标和APACHE Ⅱ评分的关系分析

目的:探讨不同预后脓毒症患者血清降钙素原(PCT)、C反应蛋白(CRP)与凝血功能指标和急性生理和慢性健康状况评分系统Ⅱ(APACHEⅡ)评分的关系。方法:回顾性分析2015年1月至2019年1月期间深圳市第二人民医院重症医学科收治的160例脓毒症患者(脓毒症组)与在深圳市第二人民医院接受住院治疗的160例非脓毒症患者(非脓毒症组)的临床资料,根据脓毒症组患者住院28d后的预后情况分为存活组118例和死亡组42例,比较脓毒症组和非脓毒症组以及死亡组和存活组患者血清PCT和CRP水平、APACHE II评分以及凝血功能指标,采用Pearson相关性回归分析脓毒症患者血清降钙素原和CRP水平与APACHEⅡ评分以及凝血功能指标相关性。结果:与非脓毒症组相比,脓毒症组的血清PCT和CRP水平以及APACHEⅡ评分明显升高,凝血酶原时间(PT)和部分凝血活酶时间(APTT)明显延长(均P<0.05)。与存活组相比,死亡组的血清PCT和CRP水平以及APACHEⅡ评分明显升高,而PT和APTT均明显延长(均P<0.05)。Pearson相关性回归分析结果显示,血清PCT和CRP水平与APACHEⅡ评分、PT及APTT均呈正相关(均P<0.05)。结论:脓毒症患者血清PCT和CRP水平异常升高,APACHEⅡ评分及凝血功能指标均与血清PCT和CRP水平呈正相关,检测血清PCT和CRP水平有助于评估脓毒症患者的预后。     

缬沙坦氢氯噻嗪对高血压合并心力衰竭患者Ang Ⅱ、NT-ProBNP及CTGF的作用分析

目的:探讨缬沙坦氢氯噻嗪对高血压合并心力衰竭患者血管紧张素Ⅱ(Ang Ⅱ)、氨基末端脑钠尿肽前体(NT-ProBNP)及结缔组织生长因子(CTGF)的作用。方法:选择2016年3月到2019年3月我院收治的高血压合并心力衰竭患者113例进行研究,以随机数表法分为观察组(n=57)和对照组(n=56)。对照组给予贝那普利治疗,观察组在对照组的基础上采用缬沙坦氢氯噻嗪治疗。比较两组患者的临床疗效、Ang Ⅱ、NT-ProBNP及CTGF、左心室射血分数(LVEF)、左心室收缩末期内径(LVESd)、左心室舒张末期内径(LVEDd)、收缩压(SBP)、舒张压(DBP)水平变化情况及并发症发生情况。结果:治疗后,两组总有效率分别为92.98%、73.21%,差异显著;治疗前,两组Ang Ⅱ、NT-ProBNP及CTGF水平无显著差异(P>0.05);治疗后,两组Ang Ⅱ、NT-ProBNP及CTGF水平均显著改善,且观察组均低于对照组(P<0.05);治疗前,两组心功能水平无显著差异(P>0.05);治疗后,两组心功能水平均显著改善,且观察组LVEF高于对照组,LVESd、LVEDd低于对照组(P<0.05);治疗前,两组血压水平无显著差异(P>0.05);治疗后,两组血压水平均显著改善,且观察组SBP、DBP水平显著低于对照组,差异显著(P<0.05);两组并发症总发生率分别为7.02%、10.71%,差异无显著差异(P>0.05)。结论:在高血压合并心力衰竭患者中应用缬沙坦氢氯噻嗪辅助治疗效果显著,可有效改善患者心功能、Ang Ⅱ、NT-ProBNP及CTGF水平。