Physiological aspects of the production and conversion of DMSP in marine algae and higher plants

Dimethylsulphoniopropionate (DMSP) is a compound produced in several classes of algae and higher plants that live in the marine environment. Considering its generally high intracellular concentrations, DMSP has a function in the osmotic protection of algal cells. Due to the relatively slow adaptation of its intracellular concentrations upon salinity shifts, DMSP should, however, not be considered as an osmoticum in the strict sense of being responsible for osmotic balance, but rather as a constitutive compatible solute. Besides salinity, other factors also appear to affect cellular DMSP quotas, but the exact regulatory mechanisms are still unclear. In this review, a brief discussion is given of the three pathways of DMSP biosynthesis that are currently distinguished. This is followed by an overview of the factors that affect DMSP biosynthesis (light, salinity, temperature and nitrogen limitation) in relation to its physiological functions. A new hypothesis is presented in which DMSP production is described as an overflow mechanism for excess reduced compounds and for energy excess. Finally, the possible functionality of the enzymatic cleavage of DMSP is discussed in the context of an overflow mechanism.     

Genome Sequence of a Marine Carotenoid Producing Yeast Rhodotorula mucilaginosa CYJ03

Carotenoids are valuable pigments that have been widely used in food,pharmaceutical,animal breeding and cosmetics industries.Due to the increasing demand for carotenoids of natural origin,the trend for production of carotenoids by red yeast has become popular.Strain Rhodotorula mucilaginosa CYJ03 was isolated from northern Yellow Sea of China for its carotenoid producing potential.It was found that the whole genome of CYJ03 was 19.03 Mb in size and contained 6301 protein-coding genes including a gene cluster for the carotenoids biosynthesis.The genome sequence would be valuable for exploring the potential biological properties of CYJ03,as well as for facilitating the molecular genetic analysis and the manipulation of carotenoids accumulation in this strain,and for the development of it as an engineered host for carotenoid production.     

蓝藻膦酸酯代谢及其生态意义研究进展

膦酸酯是新近发现的一类生物可利用磷,其广泛存在于水生生态系统,是水体有机磷库的重要组成,构成水体磷氧化还原循环的关键环节。随着研究的深入,越来越多的蓝藻藻株被证实参与膦酸酯的生物利用与合成,有助于阐明其适应低磷环境的机制,促进了对蓝藻磷策略与水体磷循环的全面理解,具有重要的生态学意义。与此同时,蓝藻对膦酸酯的利用性状,使得膦酸酯作为环境污染物与蓝藻磷源的双重作用开始显现,这会对水体浮游生物竞争格局的研究产生深远影响;而蓝藻的甲基膦酸代谢也被认为是水体好氧甲烷发生的来源之一。本文回顾了蓝藻膦酸酯利用与合成的研究历史,对目前蓝藻膦酸酯代谢过程生态风险与生态意义的研究进展进行了梳理,并对这一领域未来发展趋势进行了评述。     

红藻中红藻糖苷的研究进展

红藻糖苷是红藻中主要的光合作用同化产物。近年来发现,红藻中红藻糖苷的生理作用与蔗糖在高等植物中的作用类似,它们不仅是红藻中主要的小分子糖类物质,还在调控红藻中的渗透压等方面发挥着重要作用。红藻糖苷在细胞中的合成和代谢受到各因素的影响,其含量和结构也受到环境因素和来源地及红藻种类的影响。本文总结了近年来红藻中红藻糖苷的相关研究成果,分别对红藻糖苷的构型、生物合成、代谢、影响因素及生理作用等进行了阐述,从而为全面认识红藻糖苷在红藻中的生理作用提供参考。     

栅藻全转录组测序与类胡萝卜素合成途径相关基因分析

栅藻(Desmodesmus sp.)是一种能产生重要次生代谢产物类胡萝卜素的海洋绿藻,为了深入了解栅藻类胡萝卜素代谢途径及关键酶基因,本研究通过Illumina高通量测序平台对栅藻进行转录组测序.利用Trinity软件对转录组数据进行从头组装,共获得37 634个Unigenes,经过与Nt、Nr、Swiss、Prot、KEGG、COG、GO数据库比对,共有23 235个Unigenes获得注释.GO分类中(level 2)注释最多的分别是代谢过程(metabolic process),细胞组分(cell part)和催化活性(catalytic activity),与KEGG数据库比对发现14 123个Unigenes与128条代谢途径相对应.根据组装和注释的转录组结果,鉴定了栅藻中与类胡萝卜素生物合成途径相关的基因,构建了栅藻类胡萝卜素代谢途径,获得的栅藻转录组数据有利于进一步研究类胡萝卜素代谢途径中相关基因的功能及调控.     

姜提取物生物合成纳米银及其对水产病原菌抑菌性的研究

With the development of aquaculture, there is an urgent demand for an alternative antibacterial agent to reduce the drug resistance and environmental pollution caused by the abuse of antibiotics. Recently, silver nanoparticles(Ag NPs) have been viewed as a novel type of antimicrobial agents due to their unique advantages. In this study,Ag NPs were biosynthesized with the ginger rhizomes extract. The biosynthesized Ag NPs were characterised by UV–visible spectroscopy, transmission electron microscopy, X-ray diffraction and fourier transform infrared spectroscopy. Furthermore, the antimicrobial activities of the Ag NPs were fully analyzed against six typical aquatic pathogens. The results indicated that the components in ginger extract could function as the chemical reductant to synthesize Ag NPs. Moreover, compared with the Ag NPs synthesized by chemical methods, the biosynthesized Ag NPs were smaller, and had higher stability and antibacterial activity. Therefore, the biosynthesized Ag NPs using ginger extract may have prospective applications in aquaculture.     

利用多功能裂合酶CpcE/F合成非天然重组藻胆蛋白

藻胆蛋白裂合酶是催化藻胆色素与脱辅基藻胆蛋白亚基共价连接的裂合酶,在藻胆蛋白的生物合成途径中发挥着重要作用。本实验以藻蓝蛋白裂合酶Cpc E/F为研究对象,采用基因工程组合表达技术,构建了pCDFDuet-apcA-cpcE/F-hox1-pebS、pCDFDuet-pecA-cpcE/F-hox1-pebS等重组质粒,并导入大肠杆菌中,在IPTG的诱导下,成功表达得到两种非天然藻胆蛋白ApcA-PEB和PecA-PEB,这表明Cpc E/F不仅可以催化藻蓝胆素和脱辅基藻蓝蛋白的结合,还可以催化藻红胆素(PEB)与别藻蓝蛋白α-亚基(ApcA)和藻红蓝蛋白α-亚基(PecA)的结合,因此是一种多功能的裂合酶。根据重组产物的光谱特征峰分析发现,ApcA-PEB和PecA-PEB作为两种非天然存在的重组藻胆蛋白,具有与对应天然藻胆蛋白有着相近的特征吸收光谱和荧光发射峰,但同时具有明显的波长偏移并伴有色素异化现象,其光谱学性质主要由其所携带的色素基团决定。另外,荧光寿命衰减分析发现,不同脱辅基蛋白对于重组藻胆蛋白的光谱稳定性具有重要的影响。     

类胡萝卜素合成酶基因及海洋微藻合成类胡萝卜素的研究进展

类胡萝卜素在生物体内起着十分重要的作用,C5化合物异戊烯基焦磷酸IPP及其异构体二甲丙烯焦磷酸DMPP是所有类胡萝卜素合成的前体,过去一直认为异戊烯基焦磷酸IPP是通过传统的甲羟戊酸途径(mevalonic acid pathway)合成的,而新的研究发现在微生物、绿藻及高等植物中还存在着另一条IPP合成途径.该文综述了类胡萝卜素生物合成的主要途径及重要的酶编码基因,并简要介绍了海洋微藻合成类胡萝卜素的研究现状.     

海洋中麻痹性贝类毒素的合成转化及其影响因素研究进展

麻痹性贝类毒素(paralytic shellfish toxins,PSTs)是由某些甲藻产生的一种高毒性神经毒素,在海洋环境中分布广、危害大,可对水产养殖和人类健康造成重大危害;PSTs毒素的毒性大小随种类和结构的不同有较大差异。迄今,国内外学者针对PSTs的来源分布、迁移转化、生物合成及其影响因素等开展了大量的调查研究,但目前对于藻细胞产毒的生物合成途径、遗传学特征及其环境调控机理等研究仍处于起步阶段。PSTs的生物合成过程不仅与藻细胞自身生长阶段有关,还会受到光照、温度、营养盐等多种环境因素的影响,环境条件的改变会引起藻细胞毒素组成和含量发生不同程度的变化。近年来,研究人员应用基因组学和蛋白质组学技术,发现了产生PSTs的典型甲藻——亚历山大藻(Alexandrium)细胞内与PSTs毒素生物合成相关的某些基因或蛋白质,对我们更清晰地了解亚历山大藻产生PSTs毒素的机制具有重要意义。本文综合以往的研究报道,对亚历山大藻中PSTs的生物合成与转化及其主要影响因素进行了总结,以期为产毒有害藻华的防治提供科学依据。