Altered plastid levels and potential for improved fruit nutrient content by downregulation of the tomato DDB1-interacting protein CUL4

Fruits are a major source of nutrition in human diets, providing carbohydrates, fiber, vitamins and phytonutrients. Carotenoids are a principal class of compounds found in many fruits, providing nutritional benefits both as precursors to essential vitamins and as antioxidants. Molecular characterization revealed that the tomato high pigment mutant genes ( hp1 and hp2 ) encode UV-DAMAGED DNA BINDING PROTEIN-1 (DDB1) and DE-ETIOLATED-1 (DET1) homologs, respectively, and both are essential components of the recently identified CUL4-based E3 ligase complex. Here we have isolated a tomato CUL4 homolog and performed yeast two-hybrid assays to suggest possible association of tomato DDB1 with CUL4 and DET1. Real-time RT-PCR analysis indicated that both HP1 and CUL4 are expressed constitutively. Abscisic acid is implicated in plastid division control and its application substantially enhances HP1/DDB1 mRNA accumulation. Transformation of constructs expressing CUL4–YFP and DDB1–YFP fusion proteins driven by the CaMV 35S promoter reveals that both CUL4 and DDB1 are targeted to tomato plastids and nuclei simultaneously. Using fruit-specific promoters combined with RNAi technology, we show that downregulated DDB1 expression in transgenic fruits results in a significant increase in the number of plastids and corresponding enhanced pigment accumulation. CUL4-RNAi repression lines provide insight regarding CUL4 function during tomato development, and reveal that this tomato cullin is important in the regulation of plastid number and pigmentation, which in turn have a direct impact on fruit nutrient quality.     

CD14 mediates the innate immune responses to arthritopathogenic peptidoglycan-polysaccharide complexes of Gram-positive bacterial cell walls

Bacterial infections play an important role in the multifactorial etiology of rheumatoid arthritis. The arthropathic properties of Gram-positive bacteria have been associated with peptidoglycan-polysaccharide complexes (PG-PS), which are major structural components of bacterial cell walls. There is little agreement as to the identity of cellular receptors that mediate innate immune responses to PG-PS. A glycosylphosphatidylinositol-linked cell surface protein, CD14, the lipopolysaccharide receptor, has been proposed as a PG-PS receptor, but contradictory data have been reported. Here, we examined the inflammatory and pathogenic responses to PG-PS in CD14 knockout mice in order to examine the role for CD14 in PG-PS-induced signaling. We found that PG-PS-induced responses in vitro, including transient increase in intracellular calcium, activation of nuclear factor-kappaB, and secretion of the cytokines tumor necrosis factor-alpha and interleukin-6, were all strongly inhibited in CD14 knockout macrophages. In vivo, the incidence and severity of PG-PS induced acute polyarthritis were significantly reduced in CD14 knockout mice as compared with their wild-type counterparts. Consistent with these findings, CD14 knockout mice had significantly inhibited inflammatory cell infiltration and synovial hyperplasia, and reduced expression of inflammatory cytokines in PG-PS arthritic joints. These results support an essential role for CD14 in the innate immune responses to PG-PS and indicate an important role for CD14 in PG-PS induced arthropathy.     

Prevention of hepatic ischemia-reperfusion injury by green tea extract

These experiments were designed to determine whether green tea extract (GTE), which contains polyphenolic free radical scavengers, prevents ischemia-reperfusion injury to the liver. Rats were fed a powdered diet containing 0-0.3% GTE starting 5 days before hepatic warm ischemia and reperfusion. Free radicals in bile were trapped with the spin-trapping reagent alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) and measured using electron spin resonance spectroscopy. Hepatic ischemia-reperfusion increased transaminase release and caused pathological changes including focal necrosis and hepatic leukocyte infiltration in the liver. Transaminase release was diminished by over 85% and pathological changes were almost totally blocked by 0.1% dietary GTE. Ischemia-reperfusion increased 4-POBN/radical adducts in bile nearly twofold, an effect largely blocked by GTE. Epicatechin, one of the major green tea polyphenols, gave similar protection as GTE. In addition, hepatic ischemia-reperfusion activated NF-kappa B and increased TNF-alpha mRNA and protein expression. These effects were all blocked by GTE. Taken together, these results demonstrate that GTE scavenges free radicals in the liver after ischemiareoxygenation, thus preventing formation of toxic cytokines. Therefore, GTE could prove to be effective in decreasing hepatic injury in disease states where ischemia-reperfusion occurs.     

红龙利离体培养的植株再生研究(简报)

PLANTREGENERATIONFROMINFITROCULTUREOFPHLLODENDRONERUBESCENSZhangPeng;HuangXiangli;XuXinlan;LingDinghou(SouthChinaInstituteofBotany.AcademiaSinica,Guangzhou510650)(SortthChinaBotanicalGarden,AcademiaSinica.Guangzhou510520)红龙利是华南地区新引进的名贵热带观叶植物,属天南星科,喜林芋属。其株体茎攀援,茎叶呈紫红色,叶片正面具光泽,为适于室内栽培的优良观叶花卉。红龙利采用常规分株繁殖,因此存在繁殖速度慢、系数低等问题。植物组织培养技术在促进园艺植物事业的发展上取得了引…     

对虾—罗非鱼—缢蛏封闭式综合养殖的水质研究

研究了对虾,罗非鱼和缢蛏封闭式综合养殖的环境状况,结果表明,混养各组环境状态总体要优于单养组,实验期间混养组DO的波动幅度略小于单养组,最低值则高于单养组;各混养组COD值和水层细菌数量相互差异不显著,但各混养组均显著低于单养组（t-检验,α＜0．05）,混养围隔水体有机质含量明显低于单养;混养各围隔组中浮游生物生物量,Chl.a均低于且,滤食性动物对浮游生物的压制作用明显,在底泥中,混养组N,P的积累量比单养组低39．76％和51．26％,混养组细胞总数则比单养组低7．63％,本研究表明,封闭式综合养殖可以大大减少注入近海的养殖污水的排放量,从而降低对近海水质的污染。     

外源一氧化氮提高一年生黑麦草抗冷性机制

用不同浓度的一氧化氮(NO)供体硝普纳(sodiumnitroprusside,SNP)处理低温胁迫下1年生黑麦草幼苗,探讨外源NO对提高黑麦草幼苗抗冷性的作用。结果表明外源NO能减缓低温胁迫下黑麦草幼苗质膜相对透性的增加,促进脯氨酸(Pro)的积累,提高超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)保护酶活性,其中POD酶活性的提高尤为显著。恢复生长时,经SNP处理的幼苗膜透性、脯氨酸和保护酶活性恢复较快,其中0.5mmol/LSNP处理的效果最为明显,0.2、1.0mmol/LSNP处理的效果次之。