褐环黏盖牛肝菌异柠檬酸裂解酶和苹果酸合酶活性的研究

为了探明褐环黏盖牛肝菌的草酸代谢途径,研究了pH值、反应温度对褐环黏盖牛肝菌异柠檬酸裂解酶（ICL）和苹果酸合酶（MS）的活性的影响。结果表明,酶促反应褐环黏盖牛肝菌ICL最适pH值为5.6,其最大活性为4.37 U/g FW;MS的最适pH值为7.0,其最大活性为3.57 U/g FW; ICL最适反应温度为30℃, MS最适反应温度为35℃; K+, Na+, Mg2+三种金属离子中, Mg2+对ICL活性具有明显的激活作用,而Na+对MS的活性具有明显的激活作用。     

番茄果实成熟相关基因SlPEL和SlAPL的表达特性

分析27个代表番茄不同发育阶段和生物反应的组织特异性、含有152 635个独立EST数据库的数码表达,发现果胶裂解酶基因 (pectate lyase, SlPEL) 和番茄AP2 Like (SlAPL)的转录受果实成熟的调节。以授粉后不同发育时期的番茄(品种为美味樱桃)果实为试材, 用半定量PCR和荧光实时定量PCR分析SlPEL的表达模式,结果表明,授粉后12 d,其表达水平明显上升;授粉后16~18 d,达到第一个小高峰;28 d到最高峰;从28 d到完全成熟逐步下降到第一个小高峰的水平。SlAPL的表达模式与SlPEL类似,但其表达启动的时期迟于SlPEL。从授粉后25 d,SlAPL转录启动;授粉后28~32 d,其转录水平上升到第一个小高峰;39 d达到最高峰,以后到完全成熟略有下降。该研究也印证利用EST的数据库进行基因数码表达分析的可行性。     

阴沟肠杆菌的Hy3AL和hycA部分基因克隆及序列分析

为了克隆氢化酶3大亚基（HyA3L）和甲酸氢酶抑制因子（hycA）,研究其在阴沟肠杆菌产氢代谢中的作用和机制,笔者利用CODEHOP设计阴沟肠杆菌NRRL B-414 HyA3L和hycA简并引物,选用引物HyA3J和HycAJ扩增基因组DNA,分别得到约1500、150 bp的PCR产物,该产物连接pMD18-T载体,并克隆转化至E.coli DH5α感受态细胞中,经筛选后测序。推导的HyA3J扩增产物氨基酸序列与Enterobacter sp. 638的HyA3L蛋白一致性最高达到99%,仅有3个氨基酸的差异,表明其为阴沟肠杆菌的HyA3L;推导的HycAJ扩增产物氨基酸序列与Enterobacter cloacae subsp. cloacae ATCC 13047的HycA蛋白一致性最高达到92%,仅有4个氨基酸的差异,表明其为阴沟肠杆菌的hycA。通过以上分析可得出,采用CODEHOP程序设计的简并引物可信性强,阳性率高。阴沟肠杆菌NRRL B-414的氢化酶3大亚基和甲酸氢酶抑制因子部分基因的成功克隆,为通过代谢工程手段敲除氢化酶3大亚基和甲酸氢酶抑制因子的基因全长克隆奠定基础,不但增加了这2个基因的资源,也可为其基因敲除等代谢工程研究提供科学依据和工作基础。     

Phenylalanine ammonia‐lyase activity and ortho‐diphenolic content with regard to boron nutrition in sunflower leaves.

Homogenates were prepared from the leaves of hydroponically cultivated sunflower (Helianthus annuus, L.) under deficient, normal and toxic B conditions and the phenylalanine ammonia‐lyase activity together with the ortho‐diphenolic and micronutrient content were measured every week from one month to flowering

The restoration of enzymatic activity on the exogenous addition of borate “in vivo”; was also studied.

Both B toxicity and deficiency resulted in increased phenylalanine ammonia‐lyase activity in the homogenates

The toxicity effect was early and sustained and the deficiency effect late and transitory. “In vitro”; borate addition to the reaction mixture did not significantly change the phenylalanine‐ammonia‐lyase activity in the homogenates.

There was no statistical correlation between the phenylalanine‐ammonia‐lyase activity and any micronutrient content in leaves.

A high accumulation of ortho‐diphenolics appeared in B‐deficient leaves only after 28 days of differential culture and may be responsible for the drop in phenylalanine‐ammonia‐lyase activity noted at this time.     

Response of in vitro obtained oil palm and interspecific OxG hybrids to inoculation with Phytophthora palmivora

Bud rot (BR) disease caused by Phytophthora palmivora is the most devastating disease in oil palm cultivation in America. Oil palms that survived BR epidemics were found in areas highly devastated by the disease; these palms were introduced into Cenipalma's in vitro micropropagation (cloning programme). A severity scale was developed for in vitro palms from five ortets inoculated with two different P. palmivora isolates. Then, eight ortets of Elaeis guineensis and two ortets of the OxG interspecific hybrid were evaluated in two inoculation trials under chamber growth conditions. The clone performance response was consistent with that reported in the field for the corresponding ortets, and two contrasting ortets, one susceptible (ortet 57) and one resistant (ortet 34) were identified. We monitored and compared defence responses to P. palmivora in the contrasting ortets. An increase in reactive oxygen species (ROS) production after inoculation with the pathogen was observed, with higher accumulation of H₂O₂ in the resistant plants. Catalase (CAT) activity in resistant plants increased after inoculation with the pathogen from 24 hr post‐infection (hpi) and remained high during the observation time. In the susceptible ortets, there was a significant increase on catalase activity only at 48 hpi. Peroxidase (POS) activity increased in clones from both susceptible and resistant ortets, but the increase was much greater in the susceptible ones. Phenylalanine ammonia lyase activity increased in response to inoculation, and these increases were greater in clones of the susceptible ortet than in clones of the resistant ortet.     

杨树溃疡病菌三菌系及诱导物对寄主两种酶活性的影响

测定了杨树溃疡病菌（Ｄｏｔｈｉｏｒｅｌａｇｒｅｇａｒｉａ）三菌系直接感染及三菌系代谢产物、菌丝体提取物等两类诱导物诱导毛白杨（Ｐｏｐｕｌｕｓｔｏｍｅｎｔｏｓａ）愈伤组织过氧化物酶和苯丙氨酸解氨酶的活性。结果表明,两个不同生理型的杨树溃疡病菌对寄主过氧化物酶活性的诱导作用差异较大,但对苯丙氨酸解氨酸活性诱导作用的大小与不同生理型之间没有必然联系     

水杨酸对黄芪愈伤组织代谢产物中几种E活性的影响

目的探讨水杨酸对黄芪愈伤组织代谢产物中几种E活性的影响.方法通过添加不同浓度的水杨酸（SA）处理黄芪愈伤组织,并从提取物中检测几种酶活性的变化.结果黄芪愈伤组织代谢产物中的过氧化物酶（POD）、过氧化氢酶（CAT）、多酚氧化酶（PPO）和苯丙氨解氨酶（PAL）的活性均随水杨酸（SA）体积质量和培养时间的改变而改变,随着SA浓度的增加可提高PAL,POD及PPO的活性,但抑制CAT的活性.结论 SA体积质量在0.01 mg/L时抑制CAT活性最明显;SA体积质量在0.1 mg/L和1 mg/L时POD和PPO活性最高,并且均在36 h出现最高峰.     

新疆棉花品种次生代谢酶活性与诱导抗蚜性的关系

为了明确不同棉花品种次生代谢酶活性与诱导抗蚜性的关系,研究了不同类型棉花品种在棉蚜为害胁迫下,苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)和多酚氧化酶(PPO)活性的变化及其对抗蚜性的影响。结果表明,未受蚜害时不同品种同一酶活性存在显著差异;受蚜害诱导后,抗蚜品种和感蚜品种3种酶活性均有不同程度的上升,抗蚜品种酶活性显著高于感蚜品种,诱导抗蚜性的强弱在不同品种间差异显著。     

氟对茶叶品质成分代谢的的影响

通过盆栽试验研究氟了对茶树新梢生长和品质成分含量的影响。适量增加土壤氟水平能提高新梢产量,但在高氟水平下新梢产量明显下降。茶多酚、咖啡碱及儿茶素(EGCG等)的含量随土壤氟水平的增加而逐渐降低,高氟水平下新梢的游离氨基酸含量也显著下降,苯丙氨酸解氨酶(PAL)、谷氨酸合成酶(GOGAT)的活性也随土壤和茶树氟浓度的增加而下降,说明氟可能抑制茶树儿茶素的合成代谢和氮素代谢。上述结果表明,氟对茶树生长和品质成分的影响与氟水平有关,虽然低浓度氟对茶树生长有一定的促进作用,但高浓度氟抑制茶树生长和茶多酚、氨基酸等品质成分的代谢。     

New Benzoxazine Secondary Metabolites from an Arctic Actinomycete

Two new secondary metabolites, arcticoside (1) and C-1027 chromophore-V (2), were isolated along with C-1027 chromophore-III and fijiolides A and B (3–5) from a culture of an Arctic marine actinomycete Streptomyces strain. The chemical structures of 1 and 2 were elucidated through NMR, mass, UV, and IR spectroscopy. The hexose moieties in 1 were determined to be d-glucose from a combination of acid hydrolysis, derivatization, and gas chromatographic analyses. Arcticoside (1) and C-1027 chromophore-V (2), which have a benzoxazine ring, inhibited Candida albicans isocitrate lyase. Chromophore-V (2) exhibited significant cytotoxicity against breast carcinoma MDA-MB231 cells and colorectal carcinoma cells (line HCT-116), with IC₅₀ values of 0.9 and 2.7 μM, respectively.