HCF243 encodes a chloroplast-localized protein involved in the D1 protein stability of the arabidopsis photosystem II complex

Numerous auxiliary nuclear factors have been identified to be involved in the dynamics of the photosystem II (PSII) complex. In this study, we characterized the high chlorophyll fluorescence243 (hcf243) mutant of Arabidopsis (Arabidopsis thaliana), which shows higher chlorophyll fluorescence and is severely deficient in the accumulation of PSII supercomplexes compared with the wild type. The amount of core subunits was greatly decreased, while the outer antenna subunits and other subunits were hardly affected in hcf243. In vivo protein-labeling experiments indicated that the synthesis rate of both D1 and D2 proteins decreased severely in hcf243, whereas no change was found in the rate of other plastid-encoded proteins. Furthermore, the degradation rate of the PSII core subunit D1 protein is higher in hcf243 than in the wild type, and the assembly of PSII is retarded significantly in the hcf243 mutant. HCF243, a nuclear gene, encodes a chloroplast protein that interacts with the D1 protein. HCF243 homologs were identified in angiosperms with one or two copies but were not found in lower plants and prokaryotes. These results suggest that HCF243, which arose after the origin of the higher plants, may act as a cofactor to maintain the stability of D1 protein and to promote the subsequent assembly of the PSII complex.     

Public education improves farmers knowledge and management of invasive alien species

Research into the human dimensions of invasive alien species (IAS) management has received great attention to date. However, little is known about how public education influences stakeholders knowledge and management of IAS. Using key informant interviews and household questionnaires, we explored the role of public education in farmers knowledge and management of invasive Mikania micrantha in the China-Myanmar Border Region (China). We found ten common educational approaches that farmers were familiar with and/or adopted, and a high level of knowledge and management among farmers. We also found that public educational approaches helped to improve farmers knowledge and management, with some differences due to socio-demographic factors. We conclude that promotional materials and training workshops work better than personal experience, and that training workshops perform best. These results suggest that improving the design and implementation of public education could contribute to effective communication among stakeholders and long-term management of IAS. Our findings provide important insights for adopting public education programs in IAS management.

     

不同仙草种源间遗传关系的ISSR分析

采用ISSR分子标记技术对不同种源的20份仙草进行聚类分析。从40条ISSR引物中筛选出18条扩增条带清晰且重复性好的引物,共扩增出114条带,其中多态性条带53条,多态性比率为46.5%。采用NTSYS-pc软件对20份样品进行聚类分析。结果表明,供试20份仙草资源间的遗传相似系数介于0.37～0.96之间,聚类可将其分成3个大类群,其中一类全部为福建、广东和台湾等国内产区的栽培种源,一类为野生种源,另一类包括引自印度尼西亚种源及其与广东朝阳仙草的杂交后代。聚类结果表明仙草种源间的遗传差异与地理分布关系不密切而与形态差异有一定联系。     

The K domain mediates heterodimerization of the Arabidopsis floral organ identity proteins,APETALA3 and PISTILLATA

MADS genes in plants encode key developmental regulators of vegetative and reproductive development. The majority of well-characterized plant MADS proteins contain two conserved domains, the DNA-binding MADS domain and the K domain. The K domain is predicted to form three amphipathic alpha-helices referred to as K1, K2, and K3. In this report, we define amino acids and subdomains important for heterodimerization between the two Arabidopsis floral organ identity MADS proteins APETALA3 (AP3) and PISTILLATA (PI). Analysis of mutants defective in dimerization demonstrates that K1, K2 and the region between K1 and K2 are critical for the strength of AP3/PI dimerization. The majority of the critical amino acids are hydrophobic indicating that the K domain mediates AP3/PI interaction primarily through hydrophobic interactions. Specially, K1 of AP3 and PI resembles a leucine zipper motif. Most mutants defective in AP3/PI heterodimerization in yeast exhibit partial floral organ identity function in transgenic Arabidopsis. Our results also indicate that the motif containing Asn-98 and specific charged residues in K1 (Glu-97 in PI and Arg-102 in AP3) are important for both the strength and specificity of AP3/PI heterodimer formation.     

Hydroxyl radical scavenging activity of beta-N-oxalyl-L-alpha, beta-diaminopropionic acid.

Exogenous hydroxyl radical treatments increased the levels of beta-N-oxalyl-L-alpha, beta-diaminopropionic acid (ODAP) in grass pea seedlings. Lipid peroxidation initiated by hydroxyl radicals can be alleviated when grass pea seedlings were pretreated with exogenous ODAP, suggesting that ODAP might act as an hydroxyl radical scavenger in vivo. Competing with salicylate for hydroxyl radicals in the hydroxyl radical generating/detecting system, ODAP's in vitro hydroxyl radicals scavenging activity was assessed to confirm this result, and the role of ODAP as an effective hydroxyl radical scavenger is discussed.     

柯萨奇B3病毒对心肌细胞离子通道电流的影响

目的 :探讨柯萨奇B3病毒 (coxsackievirusB3,CVB3)对大鼠心肌细胞离子通道的影响 ,以了解病毒感染导致细胞电生理活动异常的机理。方法 :酶消化法获得单个心肌细胞后利用膜片钳全细胞电流记录技术观察CVB3对L型钙通道电流、钠通道电流、外向钾电流和内向整流性钾电流的影响。结果 :CVB3感染使L型钙通道电流、外向钾电流增加 ,内向整流性钾电流减小 ,对钠通道电流无明显影响。结论 :CVB3对L型钙通道电流、外向钾电流和内向整流性钾电流的影响可能是病毒感染后细胞损伤和产生异常电活动的原因。