木麻黄抗逆性研究进展

木麻黄(Casuarina equisetifolia)是热带、亚热带常绿乔木, 天然生长于滨海疏松沙土中, 为多用途速生树种。长期生长在恶劣的沿海气候和环境中使其具有较强的抗盐、抗风、耐瘠薄、抗涝能力。木麻黄已广泛种植于我国东南沿海, 主要用于防风固沙、盐碱地改良和干旱地区绿化等, 在防御沿海自然灾害、改善生态环境方面发挥了巨大作用。杂交和盐碱地露地育苗等技术使木麻黄的抗寒性 也得到了较大提高。本文就近年来木麻黄抗非生物胁迫的研究进行了综述, 旨在为合理开发和利用木麻黄资源提供参考依据。     

fNIRS Exhibits Weak Tuning to Hand Movement Direction

Functional near-infrared spectroscopy (fNIRS) has become an established tool to investigate brain function and is, due to its portability and resistance to electromagnetic noise, an interesting modality for brain-machine interfaces (BMIs). BMIs have been successfully realized using the decoding of movement kinematics from intra-cortical recordings in monkey and human. Recently, it has been shown that hemodynamic brain responses as measured by fMRI are modulated by the direction of hand movements. However, quantitative data on the decoding of movement direction from hemodynamic responses is still lacking and it remains unclear whether this can be achieved with fNIRS, which records signals at a lower spatial resolution but with the advantage of being portable. Here, we recorded brain activity with fNIRS above different cortical areas while subjects performed hand movements in two different directions. We found that hemodynamic signals in contralateral sensorimotor areas vary with the direction of movements, though only weakly. Using these signals, movement direction could be inferred on a single-trial basis with an accuracy of ∼65% on average across subjects. The temporal evolution of decoding accuracy resembled that of typical hemodynamic responses observed in motor experiments. Simultaneous recordings with a head tracking system showed that head movements, at least up to some extent, do not influence the decoding of fNIRS signals. Due to the low accuracy, fNIRS is not a viable alternative for BMIs utilizing decoding of movement direction. However, due to its relative resistance to head movements, it is promising for studies investigating brain activity during motor experiments.     

Metal resistance and accumulation in bacteria

Recent research on the ecology, physiology and genetics of metal resistance and accumulation in bacteria has significantly increased the basic understanding of microbiology in these areas. Research has clearly demonstrated the versatility of bacteria to cope with toxic metal ions. For example, certain strains of bacteria can efficiently efflux toxic ions such as cadmium, that normally exert an inhibitory effect on bacteria. Some bacteria such as Escherichia coli and Staphylococcus sp. can volatilize mercury via enzymatic transformations. It is also noteworthy that many of these resistance mechanisms are encoded on plasmids or transposons. By expanding the knowledge on metal-resistance and accumulation mechanisms in bacteria, it may be possible to utilize certain strains to recover precious metals such as gold and silver, or alternatively remove toxic metal ions from environments or products where their presence is undesirable.     

Genetic structure of the annual weed Senecio vulgaris in relation to habitat type and population size

Throughout the world, the highly selfing annual common groundsel, Senecio vulgaris (Asteraceae) is a common weed. Recently, it has also colonized ecological compensation areas in agro-ecosystems. We investigated the genetic structure of S. vulgaris using random amplified polymorphic DNA (RAPD) profiles of 80 plants from nine populations representing three habitat types in two regions in Switzerland. RAPD variation among regions (19.8%), among populations within regions (19.2%) and within populations (61.1%) was highly significant (ANOVA; P < 0.001). Gene flow estimated from the observed differentiation among populations (PhiST = 0.382) was low (assuming Wright's island model, Nem = 0.404). Genetic distances between pairs of populations were significantly correlated with geographical distances (Mantel test; r = 0.37, P < 0.03). Molecular variance obtained with AMOVA was lowest in the small populations in compensation areas (1.13), intermediate in vineyard populations (2.49), all located in northern Switzerland and highest in the larger vegetable field populations from western Switzerland (3.41; P < 0.05). Overall, there was a positive correlation of molecular variance and population size (P < 0.05), as expected under genetic drift. However, molecular variance was negatively correlated with population size among populations in ecological compensation areas, suggesting that selection was also important. We also applied triazine herbicide to leaves of three offspring of each of the 80 plants. Plants from populations of compensation areas showed higher mean levels and reduced variation in the resistance to triazine herbicide than plants from vineyards and vegetable fields. This suggests that compensation areas were colonized from adjacent corn fields, in which there has been selection for herbicide resistance. We discuss the implications of our results for the biological control of S. vulgaris.     

The Anopheles culicifacies complex and control of malaria

Of the 50 or so species and varieties of anopheline mosquito in India, about 20 are implicated as vectors of human malaria. Of these, perhaps the most important and widespread is Anopheles culicifacies s.l. For the first 10 years of widespread DDT spraying, An. culicifacies remained susceptible to this insecticide - indeed, some thought it lacked resistance genes altogether. By 1960 however, resistance to DDT was apparent. DDT is a cheap insecticide, and its use is still favoured for mosquito control wherever it remains effective. But by the end of the late 1970s it appeared that DDT resistance in An. culicifacies (and other species) was a major barrier to effective vector control in several areas - particularly in parts of the northwestern states. Yet in other areas DDT still seemed to be effective. There was also increasing evidence from other studies suggesting differences in An. culicifacies found in different areas - particularly differences in seasonal prevalence and man-biting activity. We now know - as Sarala Subbarao discusses here - that An. culicifacies s.l. represents a complex of at least four sibling species. But in this case, one of the most important findings is that DDT resistance is mainly associated with species B which proves to be a very poor vector of malaria. Such findings, made possible by careful cytogenetic studies, have very important consequences for malaria epidemiology and control policies.     

Dieldrin-resistant cabbage root fly in England

The existence of dieldrin resistance in Erioischia brassicae has been investigated in the main areas in England and Wales where brassicas are grown for human consumption. Dieldrin-susceptible and dieldrin-resistant flies were collected and bred as separate strains in the laboratory. In toxicity tests adult flies were treated with topically applied doses of insecticide in microdrops of cellosolve, and larvae were dipped in solutions of insecticide in 70% acetone and 30% water. Adults of the laboratory resistant strain showed a high level of resistance to dieldrin and aldrin and a lower level of resistance to γ-BHC. There was no cross-resistance with chlorfenvinphos or diazinon. Larvae of the resistant strain were shown to be resistant to dieldrin. Dieldrin resistance has been found in four areas in southern England, but not in a fifth major area, and resistant flies did not increase as rapidly in some areas as others. Sufficient migration of flies appeared to take place to produce similar percentages of resistant flies over areas of several square miles, but considerable differences were found in fly populations about 10 miles apart. It is suggested that the speed of development of insecticide resistance is affected by the proportion of brassica crops which are treated in an area, the amounts of insecticide applied to individual crops, and hence the insecticidal pressure applied to the E. brassicae population.     

海口市江东新区30年来海岸带城市扩展与生态格局演变

基于GIS和RS技术,在最小累积阻力MCR模型基础上引入不同源地等级的相对阻力因子构建城市扩展生态阻力面UEER模型,并结合水文分析Hydrology模型利用多时相的研究方法对海口市江东新区五个时期(1988年、2001年、2009年、2017年和2019年)的建设用地扩展格局进行动态模拟分析,从生态安全的视角探讨海口市江东新区海岸带城市扩展与生态格局演变趋势。研究结果表明：(1)2018年前研究区重点建设区表现出“摊大饼”式蔓延格局,但在研究时域内重点建设区的面积从49.48 km~2增加到61.57 km~2,建设用地总体上是逐渐集聚的,表现出以重要交通枢纽、现有居民区和商业区为中心向外扩展的趋势。(2)城市扩展是沿着建设用地适宜扩展路径进行的,因受制于生态隔离带并不与相邻建设用地直接相连,由“适宜扩展路径”引导建设用地优化开发,避免建设用地盲目的向外扩展。另外,生态隔离带有逐渐向建设用地渗入,打破了建设用地适宜性区域集中连片的扩展态势。(3)东寨港自然保护区的存在,使得江东新区东海岸以东寨港红树林自然保护区为中心形成的片状区域是生态安全核心区域,虽在相关政策的支持下,研究区的生态...     

Assessing landscape resistance to roe deer dispersal using fuzzy set theory and multicriteria analysis: a case study in Central Spain

The central Iberian Peninsula has one of the highest densities of roe deer populations in Spain. A new motorway is planned to pass through the middle of the distribution of roe deer, thus making it necessary to conduct a connectivity analysis. A map of resistance to roe deer dispersal movements was obtained based on the literature and expert judgment. Three factors were selected: land use (defined by the ability to hide movements, food source, and degree of naturalness), landforms, and influence due to proximity to elements that increase (such as roads and urban areas) or decrease (water resources and proximity to optimal habitat patches) resistance at the local level. Different combinations of factors derived using the analytical hierarchy and fuzzy logic processes were analysed and compared with the real distribution of the species. More realistic resistance (cost) values were obtained for gamma values close to 0.9. This highlights the greater predominance of the fuzzy sum over the fuzzy product in modelling the cost surface. Better results were obtained in scenarios where the predominant factors were either land use and landforms or land use and proximity to human-modified areas. This indicates that roe deer will readily range far from their optimal patches if the land use provides partial cover. These movements appear to be conditioned by steep terrain. Our case study offers a good example of building a cost resistance matrix to help locate areas where the expansion of the species may be curbed or encouraged.     

Monitoring western corn rootworm (Coleoptera: Chrysomelidae) susceptibility to carbaryl and cucurbitacin baits in the areawide management pilot program

Areawide pest management involves the uniform application of a pest control strategy over wide geographic areas. Therefore, these programs are likely to impose intense selective pressures, and the risk for resistance development among pest species for which areawide management programs are implemented is likely to be high. Pilot studies for areawide management of western corn rootworm, Diabrotica virgifera virgifera LeConte, were conducted from 1996 to 2002 at four different sites across the Corn Belt. This program used cucurbitacin baits to deliver high doses of a traditional neurotoxic insecticide (carbaryl) to individual insects while reducing the overall rate of insecticide use. Because of the concern and potential for resistance evolution, annual assessments of susceptibility to the active ingredient carbaryl were conducted both within the managed area as well as from untreated control areas. Significantly reduced susceptibility to carbaryl based on survival at a diagnostic concentration was detected in three of the four management sites (Kansas, Iowa, and Illinois/Indiana), whereas susceptibility of beetles collected outside the managed areas remained unchanged. Additionally, significantly reduced responsiveness to cucurbitacin baits was observed in beetles collected from the managed area relative to the control area at the same three sites. These results suggest strongly that areawide management has the potential to select for resistance and that a strategy for managing resistance and reducing selective pressure should be proactively implemented.     

Current approaches to malaria chemotherapy and prophylaxis

Malaria continues to be one of the most serious and widespread parasitic diseases, still occurring in over 100 countries despite concentrated efforts to eradicate it from many regions. Sixty-one countries now report their malaria cases to the WHO, and the latest analysis of these figures' shows little improvement in the overall problem during the last 15 years. Some countries, notably India and China, continue to report downward trends, but the problem continues to deteriorate in rural areas where intense economic development is taking place, particularly in Asia and the Americas. In 1984, 5.3 million cases of malaria were reported to the WHO. This is believed to represent but a small fraction of the total number because, for example, 38 of the tropical African countries do not report their malaria cases. Estimates based on the degree of malaria endemicity suggest a total incidence o f around 100 million cases annually. Chloroquine-resistant falciporum malaria has been confirmed in more than 40 countries, often showing cross-resistance to other drugs, and attempts to combat resistance using combination drugs have led to disturbing reports of side-effects as well as multidrug resistance. Vector control is also impaired in many areas due to insecticide resistance. Faced with these problems, we asked Dr Walther Wernsdorfer, head of the WHO Malaria Action Programme, what is the current WHO philosophy of malaria chemotherapy and prophylaxis?     

湖北地区部分医院肠球菌耐药性监测及相关因素分析

目的：了解湖北地区2000年度肠球菌的分离情况及耐药状况,并对抗感染用药进行探索,指导临床合理用药。方法：对湖北地区15所三甲医院各类临床标本中的538株肠球菌采用API细菌鉴定系统或Vitek全自动细菌鉴定系统进行分离鉴定,用纸片扩散法进行药敏试验,并以WHO细菌耐药监测网提供的WHONET4软件分析系统对试验数据进行分析处理。结果：本试验共分离肠球菌13个种别538株,其中大多数是粪肠球菌408株,占75.8%,屎肠球菌54株,占10.0%;坚忍肠球菌24株,占4.46%;鸟肠球菌10株,占1.86%。酪黄肠球菌6株,占1.11%;母鸡肠球菌6株,占1.11%等。本研究结果表明肠球菌的主要感染部位为泌尿道31.4%和各种分泌物31.0%。同时从药敏结果可见屎肠球菌和坚忍肠球菌对大多数抗生素的耐药性高于粪肠球基本国策 ;并发现糖肽类抗生素耐药菌株比例尚不高;庆大霉素呈高水平耐药球菌株比例则较高;对青霉素和氨卞西林耐药,本研究结果亦有反映,并且鸟肠球菌的耐药性高于粪肠球菌近三倍。结论：本年度分离的肠球菌占全年总分离菌的第六位,说明我国目前由肠球菌引起的感染所占比例不高,但仍应引起临床的高度重视,并进行动态的监测。加强对肠球菌特别是VRR耐药性的监测是非常必要的,泌尿道肠球菌感染的抗生素中呋喃妥因的耐药率较四环素和喹诺酮类药物为低,故仍不失为治疗该类泌感的首选药物,菌株差别与地区有关,由于肠球菌属中的不同种对抗生素的敏感性不同。因此种的鉴定是对该地区医院感染暴发流行,选择治疗方案的重要工具。     

Ecological suitability evaluation for mountainous area development based on conceptual model of landscape structure,function, and dynamics

Minimizing the ecological impact of land development is a fundamental principle of sustainable development. Ecological suitability assessment is the key to realizing sustainability and is also significant for optimizing spatial patterns of territorial development. Especially in mountainous areas where the ecosystem is both vulnerable and important, quantitative evaluation of ecological suitability for land development is particularly important and urgent given current development strategy of urban construction in mountainous areas in China. Taking Dali Bai Autonomous Prefecture, a representative urban construction zone in a mountainous area in Yunnan Province, China, as a study area, and based on the fundamental theory of structural and functional dynamics from landscape ecology, this study has explored the integrated ecological resistance (IER) conceptual model and constructed an index system with aspects of ecological elements, ecological importance, and ecological resilience. The results showed that: (1) the ecological suitability level was higher in the north than in the south and higher in the east than in the west, as well as higher in the Bazi region than in mountainous areas. Dali City, Binchuan County, and Xiangyun County had large ecological suitable zones for development and construction. Foci of ecological resistance having strong ecological constraints were mainly concentrated in Heqing County and in various other places; (2) by combining the integrated ecological resistance and arable land distributions, the study area was zoned into five regions: prior development zone, moderate development zone, potential development zone, restricted development zone, and forbidden development zone. Moderate, potential, and restricted development zones occupied most of the area, accounting for 28.89%, 24.69%, and 21.40%, respectively, whereas prior development zones accounted for only 8.91%; (3) based on the areal proportions of ecological suitability zoning, the 12 counties of Dali Prefecture can be grouped into three categories: prior areas for conservation, comprehensive development areas, and prior areas for development. Xiangyun County and Binchuan County should be regarded as key areas of Dali Prefecture for urban construction in mountainous areas. This research has explored an ecological suitability evaluation system from the perspective of landscape ecology and made fully understanding of ecological suitability factors in the study area, which provided a good reference to ecological suitability evaluation for mountainous area development in the worldwide.     

云南地方稻种持久抗瘟性的研究

1996～1999年,在不同纬度、不同海拔和不同稻作生态类型的重病区设立5个持久抗性稻瘟病鉴定圃.试验材料为云南的74份地方稻种资源,其中粳稻56份,籼稻18份(含野生稻3份).通过多个抗性组分进行了系统研究,初步表明大白谷(粳、墨江县)、毫弄早(籼、勐海县)、毫玉浪(籼、勐海县)、疣粒野生稻(野、西双版纳自治州)等具有持久抗瘟性能;其中疣粒野生稻高抗细菌性条斑病,对白叶枯病抗性为0级,接近免疫,中抗稻瘟病.通过对品种多抗性组分分析和品种抗性系统聚类分析,提出在不同生态类型时、空动态的病叶片上的产孢量和病斑表型可作为简易、快速鉴定持久抗瘟性指标.     

A four-year surveillance program for detection of Plasmodium falciparum chloroquine resistance in Honduras

Countries could use the monitoring of drug resistance in malaria parasites as an effective early warning system to develop the timely response mechanisms that are required to avert the further spread of malaria. Drug resistance surveillance is essential in areas where no drug resistance has been reported, especially if neighbouring countries have previously reported resistance. Here, we present the results of a four-year surveillance program based on the sequencing of the pfcrt gene of Plasmodium falciparum populations from endemic areas of Honduras. All isolates were susceptible to chloroquine, as revealed by the pfcrt “CVMNK” genotype in codons 72-76.     

Analysis of gene inheritance and expression in hybrids between transgenic sugar beet and wild beets

Reciprocal gene exchange between cultivated sugar beet and wild beets in seed production areas is probably the reason for the occurence of weed beets in sugar beet production fields. Therefore, when releasing transgenic sugar beet plants into the environment, gene transfer to wild beets ( Beta vulgaris ssp. maritima ) has to be considered. In this study the transfer of BNYVV- (beet necrotic yellow vein virus) resistance and herbicide-tolerance genes from two transgenic sugar beet lines that were released in field experiments in 1993 and 1994 in Germany to different wild beet accessions was investigated. In order to evaluate the consequences of outcrossing, manual pollinations of emasculated wild beet plants with homozygous transgenic sugar beet plants were performed. In the resulting hybrids the transgenes were stably inherited according to Mendelian law. Gene expression in leaves and roots of the hybrids was in the same range as in the original transgenic sugar beet plants. Moreover, it was found that in one of the wild beet accessions, transfer and expression of the BNYVV resistance gene did considerably increase the level of virus resistance.     

Triclabendazole: new skills to unravel an old(ish) enigma

Triclabendazole was introduced in the early 1980s for the treatment of Fasciola hepatica infections in livestock. Due to its high activity against immature flukes, it has become established as the principal anti-fluke drug on the market. More recently, triclabendazole has been used to treat human cases of fascioliasis and is now the drug of choice for this infection, too. Resistance to triclabendazole was first reported in 1995 in a field population in Australia and, since that time, resistant populations have been identified in several countries in Europe. Parallel to the spread of resistance has been a sharp increase in the prevalence of fascioliasis, which has been attributed largely to climate changes. Consequently, farmers are faced with an alarming scenario, as none of the other fasciolicides on the market possess such high activity against the damaging immature stages of fluke. The main aim of this review is to assess current understanding of the mechanism of action of triclabendazole against the fluke and the mechanism by which the fluke has become resistant to it. The use of triclabendazole against animal and human infections is summarized and suggestions are given on ways to deal with resistance. Gaps in the knowledge of various aspects of its use are highlighted and this may serve to open up future research areas.     

Environmental risk assessment of releases of transgenic plants containing virus-derived inserts

Sequences derived from the genomes of plant viruses are being used to provide virus resistance in transgenic crop plants. Although the environmental hazards associated with the release of such plants have been discussed widely, it has not been possible to reach generally acceptable conclusions about their safety. A case-by-case approach to the risk assessment of real examples is recommended as a means of building up confidence and of indicating areas of uncertainty. A logical framework for risk assessment is suggested, a key feature of which is identification of the viruses in the release environment that may infect the transgenic plants. Each of these is considered in relation to each of the three main classes of hazard (transcapsidation, recombination and synergism), and the risk associated with each event is analysed.     

Analysis of the dynamics of adaptation to transgenic corn and crop rotation by western corn rootworm (Coleoptera: Chrysomelidae) using a daily time-step model

Western corn rootworm, Diabrotica virgifera virgifera LeConte, has overcome crop rotation in several areas of the north central United States. The effectiveness of crop rotation for management of corn rootworm has begun to fail in many areas of the midwestern United States, thus new management strategies need to be developed to control rotation-resistant populations. Transgenic corn, Zea mays L., effective against western corn rootworm, may be the most effective new technology for control of this pest in areas with or without populations adapted to crop rotation. We expanded a simulation model of the population dynamics and genetics of the western corn rootworm for a landscape of corn; soybean, Glycine max (L.); and other crops to study the simultaneous development of resistance to both crop rotation and transgenic corn. Results indicate that planting transgenic corn to first-year cornfields is a robust strategy to prevent resistance to both crop rotation and transgenic corn in areas where rotation-resistant populations are currently a problem or may be a problem in the future. In these areas, planting transgenic corn only in continuous cornfields is not an effective strategy to prevent resistance to either trait. In areas without rotation-resistant populations, gene expression of the allele for resistance to transgenic corn, R, is the most important factor affecting the evolution of resistance. If R is recessive, resistance can be delayed longer than 15 yr. If R is dominant, resistance may be difficult to prevent. In a sensitivity analysis, results indicate that density dependence, rotational level in the landscape, and initial allele frequency are the three most important factors affecting the results.     

Incipient Resistance of Helicoverpa punctigera to the Cry2Ab Bt Toxin in Bollgard II? Cotton

Combinations of dissimilar insecticidal proteins (“pyramids”) within transgenic plants are predicted to delay the evolution of pest resistance for significantly longer than crops expressing a single transgene. Field-evolved resistance to Bacillus thuringiensis (Bt) transgenic crops has been reported for first generation, single-toxin varieties and the Cry1 class of proteins. Our five year data set shows a significant exponential increase in the frequency of alleles conferring Cry2Ab resistance in Australian field populations of Helicoverpa punctigera since the adoption of a second generation, two-toxin Bt cotton expressing this insecticidal protein. Furthermore, the frequency of cry2Ab resistance alleles in populations from cropping areas is 8-fold higher than that found for populations from non-cropping regions. This report of field evolved resistance to a protein in a dual-toxin Bt-crop has precisely fulfilled the intended function of monitoring for resistance; namely, to provide an early warning of increases in frequencies that may lead to potential failures of the transgenic technology. Furthermore, it demonstrates that pyramids are not ‘bullet proof’ and that rapid evolution to Bt toxins in the Cry2 class is possible.     

Do well-connected landscapes promote road-related mortality?

Cost surface (CS) models have emerged as a useful tool to examine the interactions between landscapes patterns and wildlife at large-scale extents. This approach is particularly relevant to guide conservation planning for species that show vulnerability to road networks in human-dominated landscapes. In this study, we measured the functional connectivity of the landscape in southern Portugal and examined how it may be related to stone marten road mortality risk. We addressed three questions: (1) How different levels of landscape connectivity influence stone marten occurrence in montado patches? (2) Is there any relation between montado patches connectivity and stone marten road mortality risk? (3) If so, which road-related features might be responsible for the species’ high road mortality? We developed a series of connectivity models using CS scenarios with different resistance values given to each vegetation cover type to reflect different resistance to species movement. Our models showed that the likelihood of occurrence of stone marten decreased with distance to source areas, meaning continuous montado. Open areas and riparian areas within open area matrices entailed increased costs. We found higher stone marten mortality on roads in well-connected areas. Road sinuosity was an important factor influencing the mortality in those areas. This result challenges the way that connectivity and its relation to mortality has been generally regarded. Clearly, landscape connectivity and road-related mortality are not independent.