The reaction of cytochromes c and c2 with the Rhodospirillum rubrum reaction center involves the heme crevice domain

In order to define the interaction domain on Rhodospirillum rubrum cytochrome c2 for the photosynthetic reaction center, positively charged lysine amino groups on cytochrome c2 were modified to form negatively charged carboxydinitrophenyl lysines. The reaction mixture was separated into six different fractions by ion exchange chromatography on carboxymethylcellulose and sulfopropyl-Sepharose. Peptide mapping studies indicated that fraction A consisted of a mixture of singly labeled derivatives modified at lysines 58, 81, and 109 on the back of cytochrome c2. Fractions C1, C2, C3, and C4 were found to be mixtures of singly labeled derivatives modified at lysines 9, 13, 75, 86, and 88 on the front of cytochrome c2 surrounding the heme crevice. The photooxidation of the carboxydinitrophenyl-cytochrome c2 derivatives by reaction centers purified from R. rubrum was measured following excitation with a laser pulse. The second-order rate constant of fraction A modified at backside lysines was found to be 2.3 X 10(7) M-1 s-1, nearly the same as that of native cytochrome c2, 2.6 X 10(7) M-1 s-1. However, the rate constants of fractions C1-C4 were found to be 6 to 12-fold smaller than that of native cytochrome c2. These results indicate that lysines surrounding the heme crevice of cytochrome c2 are involved in electrostatic interactions with carboxylate groups at the binding site of the reaction center. The reaction rates of horse heart cytochrome c derivatives modified at single lysine amino groups with trifluoroacetyl or trifluoromethylphenylcarbamoyl were also measured. Modification of lysines 8, 13, 25, 27, 72, 79, or 87 surrounding the heme crevice was found to significantly lower the rate of reaction, while modification of lysines in other regions had no effect. This indicates that the reaction of horse heart cytochrome c with the reaction center also involves the heme crevice domain.     

Linkage map of seven polymorphic markers on rat Chromosome 18

A genetic linkage map of seven polymorphic markers was created with F₂ intercross progeny of F344/N and LEW/N rats and assigned to rat Chromosome (Chr) 18. Five of the markers described were defined by simple sequence length polymorphisms (SSLPs) associated with five genes: transthyretin (TTR), trypsin inhibitor-like protein (TILP), 2 adrenergic receptor (ADRB2), olfactory neuron-specific G protein (OLF), and gap junction protein (GJA1). One marker was defined by a restriction fragment length polymorphism (RFLP) detected with a probe for the human colony stimulating factor 1 receptor (CSF1R) gene. The D18N1R locus was defined by an anonymous DNA fragment amplified by the randomly amplified polymorphic DNA (RAPD) technique with a single short primer. These seven DNA loci formed a single genetic linkage group 30.4 cM in length with the following order: TTR-6.8 cM-D18N1R-9.1 cM-TILP-4.3 cM-CSF1R-0 cM-ADRB2-10.2 cM-OLF-0 cM-GJA1. The five SSLP markers were highly polymorphic. In a total of 13 inbred rat strains analyzed (F344/ N, LEW/N, LOU/MN, WBB1/N, WBB2/N, MR/N, MNR/N, ACI/N, SHR/N, WKY/N, BN/SsN, BUF/N, and LER/N), three to six alleles were detected for each marker. Remarkable linkage conservation was detected between the region of rat Chr 18 mapped and a region of mouse Chr 18. However, genes associated with these markers have been mapped to three different human chromosomes (Chrs 5, 6, and 18). The markers described here should be useful for genetic mapping studies and genetic monitoring of inbred rat strains.     

Sub-Cellular Distribution of Zinc in Different Vegetative Organs and Their Contribution to Grains Zinc Accumulation in Rice Under Different Nitrogen and Zinc Supply

Journal of Plant Growth Regulation - Zinc is an important micronutrient for the growth and development of human body and plants. Proper use of nitrogen fertilizer and foliar application of Zn have...     

视黄酸和亚硒酸钠对肝癌细胞某些表型逆转的加和作用

 人肝癌细胞株SMMC-7721经1μmol/L视黄酸和或2.5μmol/L亚硒酸钠处理后,膜上纤维连接蛋白沉着量逐日上升,且较相应天数的对照组细胞增加,而甲胎蛋白分泌量和~3H-TdR参入率被明显抑制。视黄酸和亚硒酸钠同时处理的联合组作用强度接近于两者单独使用时作用强度的加和。对以上结果和视黄酸及亚硒酸钠使肝癌细胞接触抑制恢复及表型逆转的关系作了讨论。     

基于扎根理论的社区参与国家公园建设与管理的机制研究

大量研究表明自然保护地周边社区居民对保护地的态度是影响社区参与保护,实现保护地管理目标的主要因素,由此建立了"认知-态度-参与"的行为逻辑。中国国家公园体制建设希望进一步推进社区与保护地的关系,全面提升自然保护管理效率,也建立在对这一行为逻辑的认同之上。为验证社区认知与行为的关系,并为促进不同利益相关者参与国家公园建设与管理提供科学支持,研究试图分析武夷山国家公园体制试点区社区居民的国家公园的"认知-态度-参与"的行为逻辑以揭示社区参与国家公园建设与管理的深层机制。与一般研究不同在于,本研究是针对正在建设中的国家公园,使得本地利益相关方的态度有机会影响国家公园建设进程。为获得社区"认知-态度-参与"核心观念,探索社区参与的过程和方式,提出促进社区参与的方法,研究采用扎根理论这一质性研究方法,基于对本地利益相关者采用半结构化开放问题的深度访谈,归纳出概念与范畴,形成社区参与国家公园建设与管理的理论。研究首先形成45个概念与13个范畴,通过范式模型研究发现,稳定资源使用权利、引导社区参与决策、保障社区发展权利、创新社区产业模式、提高个体适应能力、降低政策风险影响等六个主范畴能够解释社区居民对国家公园的认知-态度-参与这一行为逻辑。通过归纳主范畴,研究进一步提炼出社区参与国家公园建设与管理的理论核心在于社区自然资源管理的自主性、创新性与适应性,其内在机制在于社区参与是一个自主性提高的动态过程,需要通过保障社区生计资源禀赋来实现长期的价值转化,最终使其成为社会-生态系统适应性治理的组成部分。在理论阐释基础上,研究提出从改善社区认知、提升社区参与角度推进国家公园建设的路径。研究也指出,所提出的社区参与机制理论能够提炼量化指标评价社区参与,追踪武夷山国家公园体制试点进程。     

中国三江源国家公园与韩国智异山国家公园的对比研究

自1967年智异山被认定为韩国首个国家公园以来,韩国以国家公园为主体的自然保护地体系建设已历经50余年。这期间韩国在国家公园的建设中积累了大量经验,十分值得我国借鉴。选取我国首个国家公园体制试点——三江源国家公园和韩国首个国家公园——智异山国家公园为研究对象,对二者的管理现状进行了定性分析,并运用基于最优实践的国家公园管理能力评价方法对二者的管理能力进行了定量评价。研究表明:三江源国家公园的管理能力综合得分低于智异山国家公园,在体制建设、保障机制、资源环境管理、社区管理和科普教育五个方面均与智异山国家公园存在一定差距;智异山国家公园在资源本底调查、法制建设、多方参与、环境教育和游憩管理方面的管理能力十分突出,为三江源国家公园管理能力的提升提供了有益借鉴;三江源国家公园在生态补偿和制度约束方面具有比较优势,但在自然资源权属、资源本底调查、社区组织建设和游憩管理方面则亟待提升。在此基础上,针对三江源国家公园建设提出了强化科研支撑、健全多方参与制度、推进全民福利共享三项建议,针对我国国家公园体制建设提出了制定《国家公园法》、设置自然保护地顶层规划两项建议,以期促进三江源国家公园管理能力提升、推动我国国家公园体制建设。     

基于Meta分析的土壤呼吸对降水改变的非对称响应

气候变暖已经引起全球降水格局改变。土壤呼吸作为陆地生态系统向大气释放CO₂最大的碳库,对降水变化的响应将进一步影响碳循环,从而对全球气候变化产生反馈。尽管以往已有大量关于土壤呼吸与降水变化关系的相关研究,但存在较大争议。因此,亟待进一步深入探究土壤呼吸对降水改变的响应。基于此,研究Meta分析方法,整合了来自Web of Science 英文数据库和中国知网文献数据库(CNKI)的284篇已发表的论文和367组数据,进而分析全球中低纬度地区土壤呼吸对降水改变的响应。研究结果表明,土壤呼吸对降水改变的响应呈现出非对称特征,降水量增加能够提高16.7%的土壤呼吸,而降水量减少则会抑制17.88%的土壤呼吸。研究还发现,不同生态系统和气候区域的土壤呼吸对降水改变的响应存在较大差别。其中,降水量增加能够提高草地生态系统22%的土壤呼吸,比森林生态系统土壤呼吸高出12%;而降水量减少则会削弱草地生态系统28%的土壤呼吸,这要比森林生态系统土壤呼吸还高16%。与湿润地区相比,降水量的增加对干旱地区土壤呼吸的促进作用更加明显。而降水量的减少对干旱地区和湿润地区土壤呼吸的影响均无显著差异。此外,本研究也证实了土壤呼吸对不同降水强度和年限的响应也存在差异。在不同降水强度上,无论增加降水还是减少降水,重度增减雨的土壤呼吸均改变最大,即:重度增减雨(＞75%)＞中度增减雨(25% -75%) ＞轻度增减雨(＜25%);在不同降水年限上,长期增雨对土壤呼吸的促进作用尤为突出,但长期减雨对土壤呼吸影响无显著差异。研究结果可为未来气候情景下陆地生态系统土壤呼吸变化的准确预测以及模型模拟和改进提供重要的科学依据和理论基础。     

Full-Length Transcriptome Sequencing Combined with RNA-Seq to Analyze Genes Related to Terpenoid Biosynthesis in Cinnamomum burmannii

Cinnamomum burmannii is a cinnamomum plant rich in natural D-borneol. Natural D-borneol is a bicycle monoterpenoid compound widely used in the food, pharmaceutical, and cosmetic industries. Therefore, analyzing the biosynthesis mechanism of natural D-borneol in C. burmannii at the molecular level is helpful for directional breeding in the future and further development and utilization of C. burmannii and its related gene resources. In our study, 76 genes related to terpene metabolism were analyzed through third-generation sequencing and second-generation sequencing. Of these genes, 57 were associated with the synthesis of the terpenoid skeleton, and 19 belonged to terpenoid synthase, including four monoterpenoid synthases, seven sesquiterpenoid synthases, and eight diterpenoid synthases. Two genes in diterpenoid synthase were differentially expressed in high D-borneol and low D-borneol plants. It was speculated that these two genes might be related to D-borneol synthesis. How these two genes participate in the synthesis of D-borneol needs further study.