臭柏天然居群遗传多样性及演变历史分析

为了合理有效地保育天然臭柏(Juniperus sabina L.)种质资源,追溯和阐释其分布格局的历史成因,本文对我国内蒙古自治区、陕西省、甘肃省和青海省共10个天然臭柏居群388个个体的核糖体内转录间隔区(ITS)序列片段进行测序分析。结果显示:臭柏ITS序列总长度为1089 bp,共含有25个变异位点,定义32个单倍型,其中H4和H6单倍型为共有单倍型;分子变异分析(AMOVA)显示,臭柏居群变异主要来源于居群内,遗传变异为95.04%,而居群间遗传变异仅4.96%,居群间差异水平极显著(F ST=0.0496,P<0.001);Network单倍型网络分析表明,H4和H6为古老单倍型,其他单倍型是由他们衍生而来;遗传分化系数N ST(0.072)0.05)。推测臭柏起源于第三纪中新世(Miocene)中期约12.38 Mya,在第四纪冰期可能存在多个小型避难所。沙埋产生不定根的扩繁能力和较好的有性更新环境可能是沙地居群遗传多样性高于山地居群的决定性因素。     

DYNAMIC RESPONSE ANALYSIS. II.EVALUATION OF DYNAMIC RESPONSE ANALYSIS IN A SIMULATED NO-HARVEST CASE

A new method of stock assessment, dynamic response analysis, allows a qualitative assessment of stock status relative to its level of maximum net productivity to be carried out with minimal data. This paper evaluates the performance of dynamic response analysis on a simulated population under variable conditions with uncertain data. In the no-harvest case the data consist simply of a temporal sequence of relative population sizes. Dynamic response analysis is most sensitive to the number and precision of the population estimates and least sensitive to environmental variability and the intrinsic population growth rate. Significance levels must be chosen carefully, since some combinations of parameters and error levels result in an unacceptably low proportion of correct assessments. Dynamic response analysis can be a useful stock assessment technique for the management of marine mammals, but attention must be paid to the quantity and quality of the data.     

The conservation and tourism development of World Natural Heritage sites: The current situation and future prospects of research

The conservation and tourism development of World Heritage (WH) sites has always been a key and urgent scientific issue to be solved urgently by academia and industry all over the world. An increasing number of researchers and practitioners are paying attention to this issue. However, there is a lack of a comprehensive literature review on this topic. To fill this gap, this study conducts a systematic literature review (SLR) based on 179 related studies retrieved from the Web of Science (WoS) and Google Scholar (GS) databases. Focusing on the research question of the conservation and tourism development of World Natural Heritage (WNH) sites, we built an SLR framework to implement the review process. First, quantitative research was conducted to analyse the annual numbers, content and continents of the published literature. Second, we classified and summarized the main progress and achievements from theoretical research, technical methods, model construction, monitoring and evaluating, and application demonstration. Finally, in view of the current research situation of the conservation and tourism development of WNH sites, we proposed eight key scientific issues to be solved and several directions for future research.     

High risk water pollution hazards affecting Aveiro coastal lagoon (Portugal) – A habitat risk assessment using InVEST

Anthropogenic pressures put at jeopardy ecosystem services (ES) provided by natural habitats. Ecosystem Based Management (EBM) approaches can support policymakers dealing with physical, chemical, and biological stresses caused by high-risk water pollution (HRWP) and sudden-accidental pollution (SAP). The objective of this study is to evaluate how alarming HRWP pressures might become in fragile marine, coastal, estuarine, and freshwater socio-ecological systems (MCEF-SES) surrounded by heavily industrialized and urbanized areas. To this end a spatially explicit analysis, using the InVEST-Habitat Risk Assessment (InVEST-HRA) model in combination with expert judgement from researchers from various fields, is performed. An application is provided for the case of the Ria de Aveiro (RdA) coastal lagoon in Portugal. Results show high spatial variance of HRWP hazards across RdA, with one major multi-layer risk hotspot at the center of the research area and a second patch of multiple risk hotspots towards the North of RdA. Salines emerge as the most threatened habitat followed by Intertidal flats and Saltmarshes. The most significant water pollution risk sources contributing to Salines cumulative risk are Fossil fuel processing, storage and sale units, Industrial units, Aquaculture, and the Marinas. Industries involving dangerous substances in the region threaten primarily Watercourses. This study confirms the InVEST-HRA model in combination with expert judgement is a transparent and easily replicable approach to build ES-based knowledge about habitat risks threatening MCEF-SES in a Natura 2000 site heavily pressured by HRWP hazards. After further valuation analysis, pondering gains and losses from regional development and environmental protection, this knowledge can support the planning and management of coastal areas and the prioritization of pollution abatement interventions. In particular, by estimating the loss that HRWP causes in the value of ecosystem services, defining HRWP abatement policies, assessing the effectiveness, costs and benefits of those abatement policies and, ultimately, evaluating the results for the well-being of local communities through global efficiency analysis, cost-benefit analysis or cost-effectiveness analysis. Hence, it bridges the gap between an informed EBM and the development policies of fragile regions.     

Naturally occurring virulence-attenuated isolates of Listeria monocytogenes capable of inducing long term protection against infection by virulent strains of homologous and heterologous serotypes

Abstract Experimental infections of mice with strains of Listeria spp. isolated from contaminated food sources allowed discrimination of strains into those either exhibiting high, attenuated or low virulence. Compared to the highly virulent L. monocytogenes strain EGD, an attenuated strain such as L99 persisted for shorter times (5 versus 10 days) in the infected host. Using a tissue culture cell model of infection, we found that, although strain L99 was capable of accumulatinn actin like its virulent counterpart following invasion, it was unable to generate the polarized actin tails required for intracellular and cell-to-cell movement. Immunoblot analysis using specific antiserum to the ActA polypeptide, a molecule that is necessary for movement of the bacterium within the eucaryotic cell, indicated that a slightly truncated form of this polypeptide was produced in the L99 strain. Despite its reduced virulence, the attenuated strain L99 was just as effective in generating protection in immune mice as the highly virulent strains, albeit with a 1000-fold higher infective dose. Based on the results obtained from this study, we suggest that one of the mechanisms accounting for widespread resistance in humans to infection by Listeria may be due to asymptomatic infections by naturally occurring strains attenuated for virulence.     

Interactions between Cylindrocarpon destructans and ectomycorrhizas of Picea abies with Laccaria laccata and Paxillus involutes

Summary In paired cultures with two mycorrhizal fungi, the root pathogen Cylindrocarpon destructans (Zinsm.) Scholten had an inhibitional effect on mycelial growth of Laccaria laccata (Scop, ex Fr.) Bk. & Br. but was inhibited itself by Paxillus involutes (Batsch.) Fr. A similar pathogen-symbiont interaction scheme was observed in triaxenic cultures with Picea abies Karst. seedlings but only in the vicinity of the mycorrhizal root tips. Both mycorrhizas similarly increased the endogenous plant resistance against the infection of C. destructans. This suggests that direct pathogen-symbiont interactions are an important factor for population dynamics in the mycorrhizo sphere. Moreover, endogenous plant resistance constitutes one of the key factors for an effective defence against pathogenic fungi.     

The mycelial cell wall of Penicillium charlesii G. Smith NRRL 1887

Mycelial cell wall preparations of Penicillium charlesii G. Smith have been shown to have a total neutral carbohydrate content of 69%. Glucosamine which comprises 12% of the wall is present principally as chitin. Lipids comprise 37.5% of the wall while polypeptides comprise 19.5%. No galactofuranose units are present in the wall of this organism which is known to produce an extracellular β-1,5-galactofuranose containing polymer.     

Protection of Rhizobium by bentonite clay against predation by flagellates in liquid cultures

Abstract Bentonite clay strongly hampered the activity of the flagellate Bodo soltans in liquid culture, and thereby improved the survival of Rhizobium . A possible coating of bacteria and/or flagellates did not seem to play a part in protecting rhizobia from flagellates. Bentonite did not release any substances toxic to B. saltans during the incubation period. It is suggested that, in liquid cultures, bentonite clay increases the minimum level to which rhizobia can be predated upon, thereby giving rise to the presence of higher rhizobial cell concentrations at the end of the incubation period.