生物质生物预处理研究进展与展望

木质纤维素生物质分布广、产量大、可再生,用于制备生物基能源、生物基材料和生物基化学品。木质纤维素生物质组成复杂,包含纤维素、半纤维素和木质素等,木质素与半纤维素通过共价键、氢键交联形成独特的“包裹结构”,纤维素含有复杂的分子内与分子间氢键,上述因素制约着其资源化利用。生物预处理以其独特优越性成为生物质研究的重要方面。系统阐述了生物预处理过程中木质素降解和基团修饰对纤维素酶解的影响,纤维素含量及结晶区变化,半纤维素五碳糖利用,微观物理结构的改变。进一步提出了以生物预处理为核心的组合预处理、基于不同功能的多酶协同催化体系、木质纤维素组分分级利用和新型高效细菌预处理工艺是生物预处理未来发展的重要趋势。     

植物木质素合成调控与生物质能源利用

植物木质素生物合成调控研究已在造纸树种与饲草品质的改良中取得了许多进展。随着对木质纤维原料乙醇发酵研究的兴起,植物木质素合成调控再次成为研究热点。该文总结了目前生物质能源利用的现状,同时针对木质素在木质纤维乙醇发酵中的限制作用,综述了近年来植物木质素合成调控的研究进展,提出了今后的研究方向和内容,并展望了木质素合成调控在木质纤维乙醇发酵中的应用。     

植物木质素合成调控与生物质能源利用

植物木质素生物合成调控研究已在造纸树种与饲草品质的改良中取得了许多进展。随着对木质纤维原料乙醇发酵研究的兴起, 植物木质素合成调控再次成为研究热点。该文总结了目前生物质能源利用的现状, 同时针对木质素在木质纤维乙醇发酵中的限制作用, 综述了近年来植物木质素合成调控的研究进展, 提出了今后的研究方向和内容, 并展望了木质素合成调控在木质纤维乙醇发酵中的应用。     

2025年印度尼西亚将利用生物质替代一次性能源的5％

2008年8月24日,日本和光大学的Bambang Rudyanto教授在东京广尾的JICA地球广场举行的研讨会上发表了题为”印度尼西亚的生物燃料状况：从石油到生物燃料的转换”的演讲。印度尼西亚政府最近开始致力于生物燃料的开发,并设定了到2025年将生物燃料在一次性能源中所占的比重提高到5％的具体目标,以棕榈油为中心的开发项目正在逐步确立。     

昆虫对环境低氧的适应:生理和分子机制研究进展

氧是机体进行新陈代谢和维持生存的必要因素。低氧环境在自然界普遍存在,也是许多重大疾病(如癌症)发生过程中基本的病理生理特征。生物包括昆虫在其生存和发育过程中经常面对低氧的挑战,它们发展出了各自的适应策略以求得生存和繁荣壮大。昆虫对于低氧环境适应包括在气管系统通气量、气体交换模式、体型大小和发育时间等生理机制上的改变。为揭示昆虫低氧适应机制,研究人员针对不同昆虫采用了来自人工选择或者自然选择的品系(种群),使用了基因芯片表达和转录组测序、基因组重测序技术和基因操作等技术。基于这些方法研究发现,在分子机制方面,昆虫可以通过抑制能量代谢、提高氧气利用率来适应低氧环境;还可以通过胰岛素通路、低氧诱导因子(HIF)信号通路等来调节自身代谢活动从而适应环境低氧;除此之外,昆虫的气管系统可以在基因调控下通过代偿性生理和形态变化来适应低氧环境。昆虫低氧适应机制的研究为探求昆虫数亿年进化过程中体形改变、物种形成、种群动态等提供提供新的视野,也增进对动物应对低氧或缺氧机理的深入理解,特别是为研究人类重大疾病的发生提供重要启示。     

Dry mass–length relationships for benthic insects: a review with new data from Catamaran Brook, New Brunswick, Canada

1.___We summarized previously published mass–length relationships for aquatic insects, and determined the relationship between dry body mass and body length for eight genera and seven families of benthic insects from Catamaran Brook, New Brunswick, Canada.
2.___A power function was the most commonly used model in the earlier studies and best described the observed mass–length relationship for taxa from Catamaran Brook.
3.___Predicted mass at length was highly variable (coefficient of variation_≥ 25%) among models developed in different studies for the same family group. This variability presumably resulted from both variation in the methods used to construct the models, and in the natural spatio-temporal and taxonomic variation in mass at length, although the relative contributions of these two sources cannot be determined from existing data.
4.___Several recommendations are made for the development and application of mass–length equations in future studies.     

Strategies for the production of cell wall‐deconstructing enzymes in lignocellulosic biomass and their utilization for biofuel production

Microbial cell wall‐deconstructing enzymes are widely used in the food, wine, pulp and paper, textile, and detergent industries and will be heavily utilized by cellulosic biorefineries in the production of fuels and chemicals. Due to their ability to use freely available solar energy, genetically engineered bioenergy crops provide an attractive alternative to microbial bioreactors for the production of cell wall‐deconstructing enzymes. This review article summarizes the efforts made within the last decade on the production of cell wall‐deconstructing enzymes in planta for use in the deconstruction of lignocellulosic biomass. A number of strategies have been employed to increase enzyme yields and limit negative impacts on plant growth and development including targeting heterologous enzymes into specific subcellular compartments using signal peptides, using tissue‐specific or inducible promoters to limit the expression of enzymes to certain portions of the plant or certain times, and fusion of amplification sequences upstream of the coding region to enhance expression. We also summarize methods that have been used to access and maintain activity of plant‐generated enzymes when used in conjunction with thermochemical pretreatments for the production of lignocellulosic biofuels.     

Benthic insects and fish of the Doubs River system: typological traits and the development of a species continuum in a theoretically extrapolated watercourse

Using the distribution patterns of benthic insects (198 species) and fishes ( 29 species) from 11 tributaries and the main channel of the Doubs River drainage basin (French Jura), the authors have tried to establish whether there is an organization of species into discrete, identifiable communities. Principal Component Analysis (PCA) was used to identify whether a continuum existed, and also used to select 50 least-disturbed sites, which were used to define a theoretical watercourse. The density classes of each species were projected on this longitudinal gradient and each species response was characterised by two typological traits: its typological preferendum (tp) and its typological amplitude (ta),thus creating a synthesis of ecological characteristics. In the typological index given in the appendix, the 210 species which form a biological templet are listed in alphabetical order with their tp and ta values. These typological species traits are useful contributions to a database for running waters biomonitoring.     

In vivo electroporation: a new frontier for gene delivery and embryology

One of the key techniques in developmental biology is introducing transgenes into tissues and analyzing their subsequent effects on morphogenesis and organogenesis. In mammals, the transgenic approach is a way to misexpress foreign genes in various tissues and organs. However, targeting expression to certain tissues is totally dependent on the availability of specific promoters. Hence, it is not an easy task to control transgene expression temporally and spatially during embryogenesis. Further, if the transgene is toxic, embryonic development can be disrupted, resulting in premature death before the desired stages of development. As alternative systems, Xenopus and zebrafish are used frequently. In these vertebrate models, overexpression of genes can be carried out by injecting synthetic RNAs into eggs. However, genetic techniques in these systems are limited only to early development, prohibiting the precise analysis of gene effects on organogenesis in later stages. In contrast, the chick embryo has long served as a powerful and useful model system, holding a unique position in the field of developmental biology. Although trials of transgenic chicks have never been successful, easy accessibility to the developing embryo through a window opened in an eggshell enables performance of a variety of techniques, such as time-lapse cinephotomatography, microsurgical manipulations (including chick/quail chimeras), transplantation of cells and tissues, New's in vitro culture, etc. (Bortier et al., 1996; Douarin et al., 1996; Selleck, 1996). In addition to these experimental advantages, retrovirus-mediated gene delivery, and recently, adenovirus-mediated misexpression have been employed routinely in chick embryos (Leber et al., 1996; Morgan and Fekete, 1996).     

Deme formation in scale insects: a test with the pinyon needle scale and a review of other evidence

ABSTRACT. 1. Deme formation is the transformation of a generalist population into one which is adapted to its local conditions. This adaptation has been inferred from many things but should be inferred from higher survival or fecundity of scale insects on their natal tree compared to that of immigrant scales on the same tree.
2. Transfers of the scale insect Matsucoccus acalyptus Herbert within and between infested host trees ( Pinus monophylla (Torr. & Frem.) resulted in significant differences in scale survivorship among recipient trees. Survival on individual trees was correlated across years, indicating stable differences in tree susceptibility to scale.
3. A significant natal tree colonized tree interaction was observed for late stage scale survival in one experiment but the interaction was not caused by superior survivorship of scales transferred back to the natal tree. Hence, we found no evidence of deme formation in M.acalyptus.
4. Previous studies have concluded that deme formation occurs in the black pineleaf scale based on a significant natal tree by colonized tree interaction in scale survival. We question this conclusion because the experimental design employed did not include transfers back onto the natal tree. Other indirect evidence for deme formation in scale insects is critically discussed.     

Fossil insects and ecosystem dynamics in wetlands: implications for biodiversity and conservation

We review the uses of fossil insects, particularly Coleoptera (beetles) and Chironomidae (non-biting midges) from ancient deposits to inform the study of wetland ecosystems and their ecological and restoration processes. In particular, we focus on two contrasting ecosystems, drawing upon research undertaken by us on British raised mire peats and shallow lake systems, one an essentially terrestrial ecosystem, the other aquatic, but in which wetland insects play an important and integral part. The study of raised mire peats suggests that faunal stability is a characteristic of these wetland systems, over what appear to be extensive periods of time (up to several millennia), whilst studies of shallow lake ecosystems over recent timescales indicates that faunal instability appears to be more common, usually driven by increasing eutrophication. Drawing upon a series of fossil Coleoptera records spanning several thousand years from Hatfield Moors, south Yorkshire, we reconstruct in some detail the mire’s ontogeny and fluctuations in site hydrology and vegetation cover, illustrating the intimate association between substrate, topography and peat development. A comparison between fossil and modern beetle populations indicates that the faunal characteristics of this mire and its adjacent neighbour, Thorne Moors, become established during the early phases of peat development, including its rare endemics, and that the faunal biodiversity on the sites today is dictated by complex site histories. The over-riding characteristic of these faunas is of stability over several thousand years, which has important implications for the restoration of degraded sites, especially those where refugial areas are limited. In contrast, analyses of fossil Chironomidae from shallow lakes allow researchers to track changes in limnological status and while attempts have been made to reconstruct changes in nutrient levels quantitatively, the chironomids respond indirectly to such changes, typically mediated through complex ecosystem dynamics such as changes in fish and/or macrophyte communities. These changes are illustrated via historic chironomid stratigraphies and diversity indices from a range of shallow lakes located across Britain: Slapton Ley, Frensham Great Pond, Fleet Pond, Kyre Pool and Barnes Loch. These sites have shown varying degrees of eutrophication over recent timescales which tends to be associated with a decline in chironomid diversity. While complex functional processes exist within these ecosystems, our evidence suggests that one of the key drivers in the loss of shallow lake chironomid diversity appears to be the loss of aquatic macrophytes. Overall, while chironomids do show a clear response to altered nutrient regimes, multi-proxy reconstructions are recommended for a clear interpretation of past change. We conclude that if we are to have a better understanding of biota at the ecosystem level we need to know more of the complex interactions between different insect groups as well as with other animal and plant communities. A palaeoecological approach is thus crucial in order to assess the role of insect groups in ecosystem processes, both in the recent past and over long time scales, and is essential for wetland managers and conservation organisations involved in long term management and restoration of wetland systems     

Host shifts and signal divergence: mating signals covary with host use in a complex of specialized plant‐feeding insects

A combination of divergent natural and sexual selection is a powerful cause of speciation. This conjunction of evolutionary forces may often occur when divergence is initiated by ecological differences between populations because local adaptation to new resources can lead to changes in sexual selection. The hypothesis that differences in resource use contribute to the evolution of reproductive isolation by altering the nature of sexual selection predicts that: (1) differences in sexual traits, such as signals and preferences, are an important source of reproductive isolation between species using different resources; (2) there are identifiable sources of selection on sexual traits that differ between species using different resources; and (3) signals vary between populations using different resources to a larger extent than between populations using the same resource at different localities. Testing these predictions requires a group of closely‐related species or populations that specialize on different resources and for which the traits involved in mate choice are known. The Enchenopa binotata species complex of treehoppers (Hemiptera: Membracidae) are host plant specialists in which speciation is associated with shifts to novel host plants. Mating in this complex is preceded by an exchange of vibrational signals transmitted through host plant stems, and the signal traits important for mate choice have been identified. In the E. binotata complex, previous work has supported the first two predictions: (1) signal differences between species are important in mate recognition and (2) host shifts can alter both the trait values favoured by sexual selection and the evolutionary response to that selection. In the present study, we tested the last prediction by conducting a large‐scale study of mating signal variation within and between the 11 species in the complex. We find that differences in host use are strongly associated with differences in signal traits important for mate recognition. This result supports the hypothesis that hosts shifts have led to speciation in this group in part through their influence on divergence in mate communication systems. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 60–72.     

Use of macroalgae for marine biomass production and CO2 remediation: a review

Biomass production from macroalgae has been viewed as important mainly because of the need for pollution abatement. Environmental considerations will increasingly determine product and process acceptability and drive the next generation of economic opportunity. Some countries, including Japan, are actively promoting "green" technologies that will be in demand worldwide in the coming decades. Should an international agreement on CO₂-reduction be ratified, its effective use for energy production would be of high priority. This report shows that macroalgae have great potential for biomass production and CO₂ bioremediation. Macroalgae have high productivity, as great or greater than the most productive land plants, and do not compete with terrestrial crops for farm land. The review focuses on recent data on productivity, photosynthesis, nutrient dynamics, optimization and economics. Biomass from macroalgae promises to provide environmentally and economically feasible alternatives to fossil fuels. Nevertheless, the techniques and technologies for growing macroalgae on a large-scale and for converting feedstocks to energy carriers must be more fully developed.