盐胁迫诱导雨生红球藻合成虾青素的机理

为研究盐胁迫诱导雨生红球藻合成虾青素的机理,分析了在添加氯化钠(HS)和未添加氯化钠(CK)的培养液中,细胞内氮和碳代谢的变化。结果表明:HS中硝酸还原酶(NR)和1,5-二磷酸核酮糖羧化酶(Rub isco)活性迅速下降。虾青素在第4天开始合成时,二者分别降至初始值或最高值的46.5%和25.7%。相比之下,在对照(CK)中,NR和Rub isco活性仍然很高,仅下降了26.1%和25.6%,细胞内没有虾青素积累。上述数据表明盐胁迫条件下NR活性被抑制,细胞内氮源供应不足(氮饥饿)并进一步抑制了Rub isco的合成,导致CO2固定量减少(碳饥饿)。为了生存,藻细胞开始合成虾青素。     

碳和氮代谢被抑制诱导雨生红球藻细胞内虾青素的合成

为研究雨生红球藻(Haematococcus pluvialis)合成虾青素的机理,文中分析了不同诱导条件下藻细胞内氮和碳代谢的变化。结果表明:强光照(HL)、添加乙酸钠(AA)、缺氮(NF)和缺磷(PF)都直接或间接地影响了雨生红球藻细胞内1,5-二磷酸核酮糖羧化酶(Rub isco)和硝酸还原酶(NR)的活性,导致2种酶的活性大幅度下降。只有当Rub isco和NR的活性降到非常低的水平时,藻细胞才开始合成虾青素。与此相反,对照(CK)中这2种酶的活性一直较高,但细胞内没有虾青素积累。由于Rub isco和NR是雨生红球藻碳代谢和氮代谢的关键酶,因此碳和氮代谢被抑制是诱导雨生红球藻合成虾青素的原因。     

强光照对雨生红球藻合成虾青素的影响

在不同的光照强度下研究了雨生红球藻细胞内虾青素的合成与初级代谢的关系.在强光(HL)和中等强度(ML)的光照条件下,雨生红球藻细胞内1,5-二磷酸核酮糖羧化酶 (Rubisco)和硝酸还原酶(NR)的活性第1天大幅度提高,2天后又迅速下降.与此同时,硝酸盐浓度也快速降低.当虾青素在第4天(HL)和第6天(ML)开始合成时, HL中Rubisco和NR活性以及NO3-浓度分别下降了75.5%,71.5% 和96.2%,而ML中则下降了76.5%,74.7% 和94.3%.相比之下,在低光照(LL)条件下,实验结束时三个指标仅下降了25.9%,29.8% 和56.8%,细胞中没有虾青素积累.结果表明强光提高了Rubisco 和 NR活性,导致硝酸盐浓度迅速降低而最终又抑制了这两种酶的活性,造成雨生红球藻光合作用效率下降即"碳饥饿".在此状态下,为了生存,细胞内合成虾青素的相关基因被激活,藻细胞开始合成并积累虾青素.     

红发夫酵母细胞内蛋白质、脂肪酸与虾青素合成关系的研究

为研究红发夫酵母细胞内虾青素合成与蛋白质和脂肪酸代谢之间的关系,实验测定了发酵过程中蛋白质、脂肪酸和虾青素含量的变化。实验结果表明:红发夫酵母细胞内蛋白质的含量在整个发酵周期内变化非常显著,在0～16h(延滞期)和58～76h(指数生长后期)上升,而在16～58h(指数期)和76～124h(稳定期后期)下降。脂肪酸的含量变化趋势与蛋白质的基本相似,但是在稳定期表现出先快速上升然后迅速下降的变化特征。相比之下,虾青素含量的变化规律与蛋白质和脂肪酸相反。上述变化规律表明红发夫酵母细胞内虾青素的合成与蛋白质和脂肪酸的代谢密切相关。在延滞期和稳定前期蛋白质和脂肪酸的快速合成会减少流向虾青素合成方向的碳通量,使虾青素含量减少;而在稳定期后期底物耗尽出现碳饥饿时,蛋白质和脂肪酸的降解又为虾青素的进一步合成提供了碳骨架,提高了虾青素的含量。     

雨生红球藻的新繁殖方式及其藻蓝蛋白的合成

雨生红球藻(Haematococcus pluvialis)是一种能够合成强抗氧化剂-虾青素的单细胞绿藻,然而由于其生长速率缓慢,制约了虾青素产量的提高。在对雨生红球藻细胞周期的研究中,首次发现了雨生红球藻在高温和低光照条件下的一种特殊繁殖方式,该繁殖方式比已知的营养繁殖和无性繁殖速度快。繁殖过程中厚壁孢子萌发产生大量的小细胞,并且这些小细胞中含有以前在绿藻中从未发现的捕光色素蛋白—藻蓝蛋白(最大吸收波长λmax=621 nm,最大荧光发射波长λmFax=643 nm)。这一发现对于提高天然虾青素的产量和藻蓝蛋白的生产以及藻类的进化有着重要的意义。     

利用雨生红球藻生产虾青素的小试研究

以BG11为基本培养基,小试研究了环境因子的调控对雨生红球藻(Haematoccus pluvialis,FACHB-712)生长和虾青素积累的影响。通过单因子实验改变营养方式、pH值、温度、光照时间和光照强度,测定藻液光密度和虾青素含量等指标。结果表明:添加1g/L葡萄糖作为碳源可明显提高藻种生物量;pH=8.0左右,22～27℃,高光强(200μmol·m-2·s-1)连续光照(24h)的生长条件最适合雨生红球藻游动细胞的增殖,可以作为大规模培养雨生红球藻生产虾青素的实验依据。     

细胞生长、葡萄糖代谢及副产物重新利用对法夫酵母虾青素合成的影响分析

以两株产虾青素法夫酵母菌株为研究对象,分别在不同摇床转速、初始葡萄糖浓度、乙醇的存在与否等培养条件下,考察葡萄糖浓度、添加乙醇及溶氧状况对法夫酵母细胞生长、代谢副产物产生的影响及其与虾青素合成之间的关系,进一步阐明法夫酵母虾青素合成的机理。实验结果表明:法夫酵母JMU-VDL668菌株的生长速率、葡萄糖代谢速率和乙醇积累量均高于法夫酵母JMU-MVP14菌株,但前者的虾青素合成速率却远低于后者;当发酵液中的葡萄糖含量降低时,酵母细胞对糖代谢副产物进行二次利用,导致有利于虾青素合成的情况出现,虾青素产量得到进一步提高;在初始培养基中添加1 g?L?1乙醇能够在一定程度上促进虾青素的合成。     

通过氮浓度调节塔玛亚历山大藻毒素产量的初步研究

初步研究了培养基中氮浓度及补加氮对塔玛亚历山大藻毒素产量的影响. 低氮(88.2 mmol/L)条件下藻细胞具有较高的比生长速率(0.60 d-1),是高氮(882 mmol/L)下的约1.2倍. 低氮下在藻细胞对数生长的末期(第10天)补加氮(至高氮水平)导致塔玛亚历山大藻的最大细胞密度(48.5′103 mL-1)明显增加,分别是低氮(6.28′103 mL-1)和高氮(21′103 mL-1)下的7.7和2.3倍;最大单位细胞毒素含量(1.26 pg/cell)和产量(43.51 mg/L)分别是低氮(1.09 pg/cell和6.49 mg/L)和高氮(0.88 pg/cell和13.18 mg/L)下的1.2, 1.4倍和6.7, 3.3倍. 结果显示,在培养基中低水平氮、磷条件下塔玛亚历山大藻细胞的毒素合成增加,其中特别是磷限制条件下,藻细胞的毒素含量增加更为显著. 通过低氮下补加氮源以维持培养基中的低氮水平,可以显著促进塔玛亚历山大藻细胞的毒素产量.     

从雨生红球藻藻泥中选择性提取虾青素

以雨生红球藻湿藻泥为原料,研究了不同有机溶剂对胞内油脂和虾青素选择性提取分离的影响,通过酸解破壁提高虾青素和油脂的提取效率。结果表明,连续乙醇提取可对胞内色素和油脂有效分级提取,先提取出极性组分(叶绿素和极性脂),再提取中性组分(类胡萝卜素和中性脂)。中等极性溶剂或溶剂体系对类胡萝卜素的选择性和提取率较好;乙醇/乙酸乙酯混合溶剂提取类胡萝卜素的总得率(干重)达25.31 mg/g,提取率为69.35%。对雨生红球藻湿细胞进行酸解破壁处理有助于提高虾青素和油脂的提取率。在最优酸解破壁条件(盐酸浓度1 mol/L,温度60℃,时间60 min)下,含水80%的雨生红球藻藻泥的油脂总得率(干重)达418 mg/g,总脂提取率达97%。     

营养元素对三角褐指藻生长和脂类积累的影响

研究了不同营养元素(氮、磷、硅、铁)在不同培养浓度条件下,对三角褐指藻生长以及细胞脂类积累的影响作用。结果显示:藻细胞生长随氮含量的增加而增加,但超过一定浓度后作用不明显,最适合三角褐指藻生长的氮含量为 1.76 mmol/L。缺氮和低氮(0.22~0.44 mmol/L)培养能够明显提高藻细胞脂类含量。缺磷培养能有效促进藻株脂类积累,但是藻细胞生长受到明显抑制。缺硅导致藻细胞的生长减缓,但是对藻细胞的油脂积累影响不显著。在缺铁和高铁(0.048 mmol/L)条件下,藻的总脂含量均高于正常的培养条件。实验证明通过两步培养的方法,先在营养充足的培养基中进行藻细胞生长,然后将藻细胞转移到海水中培养,可以明显提高藻细胞的油脂含量。最终本实验确定海水为诱导三角褐指藻脂类积累的最佳诱导培养基。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。