A significant carbon sink in temperate forests in Beijing: based on 20-year field measurements in three stands

Numerous efforts have been made to characterize forest carbon(C) cycles and stocks in various ecosystems. However, long-term observation on each component of the forest C cycle is still lacking. We measured C stocks and fluxes in three permanent temperate forest plots(birch, oak and pine forest) during 2011–2014, and calculated the changes of the components of the C cycle related to the measurements during 1992–1994 at Mt. Dongling, Beijing, China. Forest net primary production in birch, oak, and pine plots was 5.32, 4.53, and 6.73 Mg C ha?1 a?1, respectively. Corresponding net ecosystem production was 0.12, 0.43, and 3.53 Mg C ha?1 a?1. The C stocks and fluxes in 2011–2014 were significantly larger than those in 1992–1994 in which the biomass C densities in birch, oak, and pine plots increased from 50.0, 37.7, and 54.0 Mg C ha–1 in 1994 to 101.5, 77.3, and 110.9 Mg C ha?1 in 2014; soil organic C densities increased from 207.0, 239.1, and 231.7 Mg C ha?1 to 214.8, 241.7, and 238.4 Mg C ha?1; and soil heterotrophic respiration increased from 2.78, 3.49, and 1.81 Mg C ha?1 a?1 to 5.20, 4.10, and 3.20 Mg C ha?1 a?1. These results suggest that the mountainous temperate forest ecosystems in Beijing have served as a carbon sink in the last two decades. These observations of C stocks and fluxes provided field-based data for a long-term study of C cycling in temperate forest ecosystems.     

第12届国际生物奥林匹克竞赛(2001)理论试题(3)

(续 2 0 0 2年第 7期第 6 1页 )理论试题 A答案1.D　 2 .D　 3.B　 4 .D　 5 .C　 6 .C　 7.D　 8.A　 9.C10 .C　 11.A　 12 .D　 13.B　 14 .D　 15 .删除　 16 .D17.C　 18.B　 19.B　 2 0 .A　 2 1.A　 2 2 .D　 2 3.D2 4 .B　 2 5 .C　 2 6 .B　 2 7.D　 2 8.D　 2 9.A　 30 .D31.删除　 32 .D　 33.C　 34.B　 35 .D　 36 .C　 37.A38.删除　 39.删除　 4 0 .C　 4 1.A　 4 2 .D　 4 3.C4 4.C　 4 5 .D　 4 6 .A　 4 7.C　 4 8.C　 4 9.D　 5 0 .B5 1.删除　 5 2 .C　 5 3.A　 5 4.D　 5 5 .B　 5 6 .C　 5 7.A…     

Bioinformatic identification of genes encoding Clq-domaincontaining proteins in zebrafish

C1q is the first subcomponent of classical pathway in the complement system and a major link between innate and acquired immunities. The globular （gC1q） domain similar with C1q was also found in many non-complement C1q-domain-containing （C1qDC） proteins which have similar crystal structure to that of the multifunctional tumor necrosis factor （TNF） ligand family, and also have diverse functions. In this study, we identified a total of 52 independent gene sequences encoding C1q-domain-containing proteins through comprehensive searches of zebrafish genome, cDNA and EST databases. In comparison to 31 orthologous genes in human and different numbers in other species, a significant selective pressure was suggested during vertebrate evolution. Domain organization of C1q-domain-containing （C1qDC） proteins mainly includes a leading signal peptide, a collagen-like region of variable length, and a C-terminal C1q domain. There are 11 highly conserved residues within the C1q domain, among which 2 are invariant within the zebrafish gene set. A more extensive database searches also revealed homologous C1qDC proteins in other vertebrates, invertebrates and even bacterium, but no homologous sequences for encoding C1qDC proteins were found in many species that have a more recent evolutionary history with zebrafish. Therefore, further studies on C1q-domain-containing genes among different species will help us understand evolutionary mechanism of innate and acquired immunities.     

西藏南部洛扎地区中生代遗迹化石及其环境意义

详细描述了西藏南部洛扎地区中生代地层中所含的遗迹化石Arenicolitessp .,Beaconitesantarcticus,Chondritessp .A ,C .sp .B ,C .sp .C ,C .sp .D ,?Cruzianasemiplicata ,Palaeophycustubularis,Phycodescircina tum ,Protovirgulariadichotoma ,Skolithosverticalis,Teichichnusrectus和Unaritessuleki计 1 0遗迹属 1 3遗迹种 。     

中胚叶叉头-1在骨成形蛋白-2诱导肌胚细胞C2C12转化成骨细胞过程中的作用

为了研究中胚叶叉头-1(MFH-1)基因在骨骼形成和细胞分化中的作用,利用基因重组、杂交瘤技术制作MFH-1单克隆抗体, 利用蛋白质印迹和RNA印迹分析观察了骨成形蛋白-2 (BMP-2)诱导小鼠肌胚细胞C2C12表达MFH-1、产生碱性磷酸酶和骨钙蛋白.小鼠肌胚细胞C2C12低水平地表达内源性MFH-1蛋白以及导入小鼠MFH-1 cDNA的人膀胱癌细胞HTB9也表达小鼠MFH-1蛋白,这种蛋白质定位于细胞核中.用BMP-2处理后, MFH-1蛋白和mRNA在C2C12细胞中的表达显著地增加.用反义MFH-1序列转染小鼠肌胚细胞C2C12可降低内源性MFH-1水平, BMP-2不能诱导导入反义MFH-1序列的肌胚细胞C2C12产生MFH-1蛋白,也不能诱导碱性磷酸酶(ALP)活性和骨钙蛋白量的增加.结果表明, BMP-2诱导的MFH-1蛋白在调节肌胚细胞C2C12向成骨细胞分化方面起关键作用.     

锦鸡儿属植物14个种类的核型

报道了锦鸡儿属Caragana 14种的核型,体细胞中期染色体的核型分别为：（1）柠条Caragana korshinskii Kom.2n=16=19m 7sm;(2)印度锦鸡儿C.gerardiana Royle 2n=16=12m 4sm;(3）锦鸡儿C.sinica(Buc‘hoz)Rehd。2n=24=15m 9sm;(4)狭叶锦鸡儿C.stenophylla Pojark 2n=32=21m 10sm 1st;(5)短脚锦鸡儿C.brachypoda Pojark.2n=16=8m 5sm 3st;(6)云南锦鸡儿C.franchetiana Kom.2n=16=13m 2sm 1st;(7)甘蒙锦鸡儿C.opulens Kom.2n=16 1b=8m 7sm 1st 1B;(8)刺叶锦鸡儿C.acanthopylla Pojark.2n=16=12m 4sm;(9)红花锦鸡儿C.rosea Maxim.2n=16=10m 6sm;(10)扁刺锦鸡儿C.boisi Schneid.2n=16=11m 4sm 1st;(11)二色锦鸡儿C.bicolor Kom.2n=16 1b=10m 6sm 1B;（12）川西锦鸡儿C.erinacea Kom.2n=16=12m 3sm 1st;（13）粗刺锦鸡儿C.crassispina Marq.2n=16=10m 6sm;(14)树锦鸡儿C.arborescens Lam.2n=16 1b=10m 6sm 1b.其中短脚锦鸡儿、云南锦鸡儿、红花锦鸡儿、扁刺锦鸡儿、二色锦鸡儿、粗刺锦鸡儿的核型为首次报道。     

泛素C末端水解酶L1的生理和病理学意义

泛素C末端水解酶L1(ubiquitin carboxy-terminal hydrolases L1)属于泛素C末端水解酶家族成员,但是泛素C末端水解酶L1酶活性非常特异,不仅具有泛素C末端水解酶活性,而且具有泛素C末端聚合酶的活性.因此,泛素C末端水解酶L1,不仅在泛素化蛋白降解途径中起到关键的作用,也在其他的泛素信号途径,如在K63-多聚泛素信号途径中起重要的作用.由于泛素C末端水解酶L1特异的蛋白酶活性,也赋予了泛素C末端水解酶L1多种生物学功能,在神经发育发生、精子发生、卵子发生和受精等方面有着重要的作用.泛素C末端水解酶L1突变也与帕金森症等神经元退化疾病紧密相关.泛素C末端水解酶L1在甲状腺、肺等多种组织的超表达,也与该组织的癌症发生有着密切的联系.     

Blocking of the PD-1/PD-L1 interaction by a novel cyclic peptide inhibitor for cancer immunotherapy

The interaction of PD-1/PD-L1 allows tumor cells to escape from immune surveillance. Clinical success of the antibody drugs has proven that blockade of PD-1/PD-L1 pathway is a promising strategy for cancer immunotherapy. Here, we developed a cyclic peptide C8 by using Ph.D.-C7 C phage display technology. C8 showed high binding affinity with h PD-1 and could effectively interfere the interaction of PD-1/PD-L1. Furthermore, C8 could stimulate CD8+T cell activation in human peripheral blood mononuclear cells(PBMCs). We also observed that C8 could suppress tumor growth in CT26 and B16-OVA, as well as anti-PD-1 antibody resistant B16 mouse model. CD8+T cells infiltration significantly increased in tumor microenvironment, and IFN-γ secretion by CD8+T cells in draining lymph nodes also increased. Simultaneously, we exploited T cells depletion models and confirmed that C8 exerted anti-tumor effects via activating CD8+T cells dependent manner. The interaction model of C8 with h PD-1 was simulated and confirmed by alanine scanning. In conclusion, C8 shows anti-tumor capability by blockade of PD-1/PD-L1 interaction, and C8 may provide an alternative candidate for cancer immunotherapy.     

中国启东肝癌高发区肝癌中AKR1C2基因异常表达及其在肝癌发生中作用(英)

已在许多肿瘤中发现AKR1C2基因的异常表达.为研究启东肝癌中AKR1C2基因异常表达的意义及其在肝癌发生中作用.通过制备兔抗人AKR1C2多克隆抗体、免疫组化、蛋白质印迹、RT-PCR、RNA印迹、原位杂交、cDNA表达芯片、免疫共沉淀、体内外致瘤试验等方法,对68例启东肝癌标本、8例正常肝组织、QGY7703启东肝癌细胞株中AKR1C2表达及作用进行分析.并研究了AKR1C2蛋白、mRNA表达与肝癌临床病理特征,侵袭性间关系.研究表明正常及癌旁肝组织中AKR1C2蛋白为膜染色,偶见弱的细胞浆染色. 95.3%肝癌显示胞浆或核染的累积型.癌及癌旁肝组织中标记指数（LI）分别为61.4±27.8, 10.2±8.7(P＜0.01).较高的LI与HCC侵袭性密切相关.蛋白质印迹显示癌组织中AKR1C2表达升高.RT-PCR显示,肝癌中AKR1C2表达指数（EI）高于癌旁及正常组织,而且存在序列差异.RNA印迹显示91.2%为上调表达.原位杂交显示肝癌细胞胞浆中染色强于癌旁及正常肝.AKR1C2过表达与肝癌转移潜能有关.AKR1C2过表达刺激QGY7703细胞中DNA合成与阻止细胞凋亡.转染AKR1C2基因的QGY7703细胞在软琼脂上集落形成能力增强,并能促进QGY7703在裸鼠体内肿瘤形成能力.cDNA表达芯片显示转染AKR1C2后导致QGY7703细胞中一些基因表达改变.AKR1C2介导NF-κB阻止抗-Fas对QGY7703的抑制作用,并且在细胞内AKR1C2能与Cdk4结合,产生免疫共沉淀.AKR1C2的异常表达在启东肝癌的发生、发展及转移中可能起重要作用.     

Truncated human LMP-1 triggers differentiation of C2C12 cells to an osteoblastic phenotype in vitro

LIM mineralization protein-1 （LMP-1） is a novel intracellular osteoinductive protein that has been shown to induce bone formation both in vitro and in viva. LMP-1 contains an N-terminal PDZ domain and three C-terminal LIM domains. In this study, we investigated whether a truncated form of human LMP-1 （hLMP-1 [t]）, lacking the three C-terminal LIM domains, triggers the differentiation of pluripotent myoblastic C2C12 cells to the osteoblast lineage. C2C12 cells were transiently transduced with AdS-hLMP-1 （t）-green fluorescent protein or viral vector control. The expression of hLMP-1 （t） RNA and the truncated protein were examined. The results showed that hLMP-1 （t） blocked myotube formation in C2C12 cultures and significantly enhanced the alkaline phosphatase （ALP） activity. In addition, the expressions of ALP, osteocalcin, and bone morphogenetic protein （BMP）-2 and BMP-7 genes were also increased. The induction of these key osteogenic markers suggests that hLMP- 1 （t） can trigger the pluripotent myoblastic C2C12 cells to differentiate into osteoblastic lineage, thus extending our previous observation that LMP-1 and LMP-1 （t） enhances the osteoblastic phenotype in cultures of cells already committed to the osteoblastic lineage. Therefore, C2C12 cells are an appropriate model system for the examination of LMP-1 induction of the osteoblastic phenotype and the study of mechanisms of LMP-1 action.     

中国启东肝癌高发区肝癌中AKR1C2基因异常表达及其在肝癌发生中作用(英文)

已在许多肿瘤中发现AKR1C2基因的异常表达 .为研究启东肝癌中AKR1C2基因异常表达的意义及其在肝癌发生中作用 .通过制备兔抗人AKR1C2多克隆抗体、免疫组化、蛋白质印迹、RT PCR、RNA印迹、原位杂交、cDNA表达芯片、免疫共沉淀、体内外致瘤试验等方法 ,对 68例启东肝癌标本、 8例正常肝组织、QGY 770 3启东肝癌细胞株中AKR1C2表达及作用进行分析 .并研究了AKR 1C2蛋白、mRNA表达与肝癌临床病理特征 ,侵袭性间关系 .研究表明正常及癌旁肝组织中AKR1C2蛋白为膜染色 ,偶见弱的细胞浆染色 .95 3 %肝癌显示胞浆或核染的累积型 .癌及癌旁肝组织中标记指数(LI)分别为 61 4± 2 7 8,10 2± 8 7(P <0 . 0 1) .较高的LI与HCC侵袭性密切相关 .蛋白质印迹显示癌组织中AKR1C2表达升高 .RT PCR显示 ,肝癌中AKR1C2表达指数 (EI)高于癌旁及正常组织 ,而且存在序列差异 .RNA印迹显示 91 2 %为上调表达 .原位杂交显示肝癌细胞胞浆中染色强于癌旁及正常肝 .AKR1C2过表达与肝癌转移潜能有关 .AKR1C2过表达刺激QGY770 3细胞中DNA合成与阻止细胞凋亡 .转染AKR1C2基因的QGY770 3细胞在软琼脂上集落形成能力增强 ,并能促进QGY770 3在裸鼠体内肿瘤形成能力 .cDNA表达芯片显示转染AKR1C2后导致QGY770 3细胞中一些基因表达改变 .AKR     

老年和青年大鼠大脑皮质脂肪酸组成及含量的对比分析

大脑功能与脑内脂肪酸成分密切相关,分析研究老年时脑脂肪酸组成及含量有助于阐明不同类型脂肪酸在老年认知能力降低过程中的作用.采用Y型电迷宫测试老年组(22月龄)和青年组(3月龄)大鼠的学习记忆能力,表明老年组大鼠的学习记忆能力显著下降.用气相色谱的方法分析大鼠大脑皮质脂肪酸的组成及含量,显示老年组和青年组大脑皮质均含有16种脂肪酸.以C23:0为内标对各种脂肪酸进行了定量,老年组总脂肪酸含量比青年组降低约15%,各脂肪酸中含量下降的脂肪酸有长链饱和脂肪酸(C14:0、C16:0、C18:0)及多不饱和脂肪酸(C18:3、C20:4、C22:4、C22:6),含量升高的脂肪酸有单不饱和脂肪酸C20:1、C24:1.用峰面积归一法计算了各脂肪酸的相对含量,老年组相对含量下降的脂肪酸有C18:0、C20:4、C22:6,相对含量升高的有极长链饱和脂肪酸(C20:0、C24:0)及单不饱和脂肪酸(C16:1、C18:1、C20:1、C22:1、C24:1).相关性分析显示,大鼠学习能力与脑皮质C22:6、C22:4、C20:4水平呈正相关,与C20:1、C24:1水平呈负相关.上述结果为阐明不同脂肪酸在老年大脑认知功能障碍中的作用提供了实验依据。     

白榆-刺槐混交林叶片养分与光合生理特性

通过田间试验,测定了不同生长时期白榆、刺槐纯林及其不同比例混交林[白榆∶刺槐分别为1∶1(1B1C)、1∶2(1B2C)和2∶1(2B1C)]植物叶片的N、P含量、叶绿素(Chl)含量、光合气体交换参数和叶绿素荧光参数的变化.结果表明:5—9月,2种纯林和3种混交林植物叶片N、P含量均呈减小趋势,到植物生长末期,1B2C混交林中刺槐叶片的N含量和白榆叶片的P含量均较其纯林有明显提高;3种混交林中,白榆叶片的叶绿素含量明显高于刺槐,且1B2C混交的白榆叶片Chl值在7月达到最大;3种混交林刺槐和白榆的光合速率(Pn)均大于其纯林,1B2C混交的刺槐叶片Pn在7月达到18.54μmol.m-2.s-1;不同比例混交林刺槐叶片的蒸腾速率和气孔导度均较其纯林有明显改善,为1B2C1B1C2B1C.至9月,3种混交林中白榆叶片的PSII电子传递量子效率明显大于纯林;2种纯林与3种混交林叶片光化学淬灭系数差异较小,而纯林的非光化学淬灭系数显著高于1B2C混交林.白榆-刺槐混交林可以显著提高植物叶片的养分含量和光合作用能力,其最优混交比例为1B2C.     

热带假丝酵母ctpxa1基因缺失菌的构建及对长链二元酸积累的影响

Pxa1p为酿酒酵母Saccharomyces cerevisiae过氧化物酶体上的膜蛋白,与Pxa2p组成二聚体,参与转运长链脂肪酸进入过氧化物酶体过程。热带假丝酵母能够发酵烷烃和脂肪酸生产长链二元酸,而过氧化物酶体中发生的β-氧化会消耗产生的长链二元酸造成产率降低。本研究以热带假丝酵母Candida tropicalis 1798为宿主菌,通过基于PCR片段的同源单交换法,快速构建ctpxa1基因敲除菌株C.tropicalis 1798-pxa1。利用半定量RT-PCR技术,检测ctpxa1基因在C.tropicalis 1798、C.tropicalis 1798-pxa1的表达量,灰度值比值为2.03,表明ctpxa1在C.tropicalis 1798-pxa1中的表达被弱化。经144 h发酵,C.tropicalis 1798-pxa1比C.tropicalis 1798的十二碳二元酸产量明显提升,其产出浓度为10.3 g/L,比野生型菌株C.tropicalis 1798提高了94.3%。     

湖南红果树一新变种

索溪峪红果树新变种图1 Stranvaesia davidiana Dcne. var. suoxiyuensis C. J. Qi et C. L. Peng, var. nov. Frutex 0.2—1m altus, trunco 1—3cm diam,; cortex griseo-brunneus. Ramuli     

Genetic Differentiation of the Forest Crested Lizards,Calotes emma alticristatus Schmidt, 1925 and C. emma emma Gray, 1845(Squamata: Agamidae) Relating to Climate Zones in Thailand

In Thailand, the forest crested lizard, Calotes emma consists of two subspecies, C. emma alticristatus Schmidt, 1925 and C. emma emma Gray, 1845. This study was performed to determine the genetic diversity and differentiation of C. emma from 16 different localities throughout Thailand. A total of 116 samples were analyzed using the mitochondrial cytochrome c oxidase subunit 1(CO1). Of these, 65 and 51 of C. e. alticristatus and C. e. emma were classified into 23(N1 – N23) and 21(S1 – S21) haplotypes, respectively. There was no shared haplotype between subspecies or between different populations within each subspecies. These haplotypes were classified into four(north-A to north-D) and three(south-A to south-C) haplogroups of C. e. alticristatus and C. e. emma, respectively. Phylogenetic analyses retrieved four lineages(classified as I to IV). Lineages I and II contained the four haplogroups of C. e. alticristatus,whereas lineage III and IV contained three haplogroups of C. e. emma. These two subspecies live separately in different climate zones, i.e. C. e. alticristatus is found in an equatorial winter dry climate, whereas C. e. emma inhabits areas with an equatorial monsoonal climate.     

湖南会同杉木人工林生态系统碳素密度

利用定位观测数据 ,对杉木人工林生态系统的碳素密度进行了探讨。结果表明 :不同年龄的杉木枝、叶中碳素密度的季节变化规律均表现为冬季 >秋季 >夏季 >春季。叶的碳素密度平均为 0 .5 0 4 4 g C· g- 1 ,变异系数 2 .0 8% ,枝的碳素密度平均为0 .4 4 79g C· g- 1 ,变异系数为 2 .2 5 %。不同层次的叶碳素密度的变化范围在 0 .4 6 12 g C· g- 1 ～ 0 .5 5 2 4 g C· g- 1 之间 ,平均值的大小排列顺序为 :上层叶 >中层叶 >下层叶。不同层次枝条的碳素密度在 0 .3917g C·g- 1～ 0 .4 96 5 g C· g- 1之间 ,平均值的大小次序为 :中层枝 >上层枝 >下层枝。 10年生杉木各器官的碳素密度变化范围为 0 .4 5 2 9g C·g- 1～ 0 .4 972 g C·g- 1 ,11年生的为 0 .4 5 80 g C· g- 1 ～ 0 .5 0 2 2 g C· g- 1 ,14年生的为 0 .4 5 80 g C· g- 1 ～ 0 .5 0 93g C· g- 1 之间 ,变异系数范围为 1.6 8%～ 8.4 4 %。不同器官的碳素密度按高低排列基本上为树叶 >树皮 >树根 >树干 >树枝 >球果。随着杉木林年龄的增长 ,林下植被各组分、死地被物的碳素密度变化规律不明显。同一林分中各层次植物的碳素密度高低排列顺序为 :乔木层 >灌木层 >草本层。 10年生和 14年生杉木林土壤各层的碳素密度随土壤深度的增加而逐渐下     

黄瓜花叶病毒CB7株系引起心叶烟坏死反应与RNA2相关

采用RT-PCR获得黄瓜花叶病毒CMV-CB7株系全长基因组cDNA,经克隆测序发现该CMV的RNA1、2和3分别为3356nt、3045nt和2218nt(序列登录号为:EF216866、DQ785470和EF216867).CMV-CB7基因组cDNA克隆体外转录RNA接种心叶烟引起坏死症状,而CMV-Fny则产生典型花叶.由CMV-CB7和CMV-Fny基因组RNA相互交换而构建6个假重组型病毒(C1C2F3、C1F2C3、F1C2C3、F1F2C3、F1C2F3和C1F2C3)活性分析表明:CMV-CB7基因组RNA2决定其在寄主上的症状反应.嵌合型RNA2(RNA2F5C3和RNA2C3F5)的寄主侵染活性测定表明:2b基因或RNA23′端非编码序列决定CMV-CB7在心叶烟坏死症状.RNA印迹分析结果显示:CMV-CB7和CMV-FnyF5C3引起寄主坏死与基因组RNA积累没有直接关系.     

福建省吸血蠓种的分类研究

1.作者等1957—1958年在福建省三个市,七个县进行吸血蠓种的采集,共采到2属13种和1亚种;其中C.fukienensis为新种、C.peregrinus ssp.lungchiensis为新亚种、C.riethi为国内的新记录。 2.本文对C. fukienensis n. sp.和 C.peregrinus lungchiensis n. ssp.的形态作了描述,同时编成了十四个吸血蠓种的检索表。     

Preparation of Monoclonal Antibodies against Human Ventricular Myosin Light Chain 1 （HVMLC1） for Functional Studies

Using purified recombinant human ventricular myosin light chain 1 (HVMLC 1) as the antigen,three monoclonal antibodies,designated C8,C9 and B 12,were prepared.Immunoblot experiments demonstratedthat all monoclonal antibodies could react with the ventricular myosin light chain 1 isolated from differentsources,such as human,rat or pig.It was also demonstrated that C8 was directed against the NN part of theN-fragment (amino acid 1-40) of HVMLC1,and both C9 and B12 against the C-fragment (amino acid 99-195).The affinity constants of C8,C9 and B12 were 3.20×10~8,8.60×10~7 and 1.77×10~8 M~(-1),respectively,determined by non-competitive ELISA.The isotype of B12 was determined as lgG2a,whereas the isotype ofboth C8 and C9 were IgG1.In the presence of C9 or B12,the actin-activated Mg~(2 )ATPase activity of myosinwas greatly inhibited,but there was almost no effect on the Mg~(2 )ATPase activity for C8.B12 and C9 alsoinhibited the superprecipitation of porcine cardiac native actomyosin (myosin B) and reconstituted actomyosin,but C8 did not.The results indicate that all three monoclonal antibodies could bind the intact myosin molecule,but B12 and C9 might more easily react with epitopes located in the C-fragment of HVMLC1.The inhibitoryeffects of B 12 and C9 on ATPase activity and superprecipitation assays show that light chain 1,particularlythe C-fragment domain,is involved in the modulation of the actin-activated Mg~(2 )ATPase activity of myosinand,as a consequence,plays an essential role in the interaction of actin and myosin.