肉毒毒素及其检测方法研究进展

肉毒毒素是自然界中毒性极强的一类神经麻痹毒素,可引起人类和动物肉毒中毒。因其制备简单、毒性强,已被列为最具威胁的生物恐怖剂之一,同时也是重要的毒素战剂。其感染剂量极低,每个人都易感。肉毒中毒后,病情严重者一般2-3 d内即可能死亡。如采取正确及时的治疗,可使肉毒中毒死亡率降低,而快速检测方法的建立无疑是成功治疗的前提。本文就肉毒毒素及其检测方法做一综述。     

2000年以来有毒蘑菇研究新进展

误食毒蘑菇而中毒一直被认为是一个对人类健康造成威胁的全球性问题,也是我国食物中毒事件中导致死亡的最主要因素。对2000年以来在有毒蘑菇新种类、新毒素与新症状、有毒蘑菇鉴定及毒素检测新方法、有毒蘑菇中毒机理、毒素基因克隆、中毒治疗以及鹅膏肽类毒素治疗肿瘤等领域取得的新进展进行了综述,并对一些热点研究领域做了展望。     

赭曲毒素A的危害及其检测方法研究进展

从赭曲毒素的产生、毒性、危害,及其检测方法和防治等几个方面综述了赭曲毒素的研究进展,对防止赭曲毒素中毒及其检测方法提出了自己的观点。对赭曲毒素中毒的预防最重要,而预防前最重要的工作是做好对赭曲毒素的监督检测工作。ELISA方法是目前最有前景的检测方法,值得进一步研究。     

水环境中微囊藻毒素的生物降解

微囊藻毒素在水环境中的生物降解是决定其环境归趋和影响其毒性的重要因素。本文综述了水细菌、鱼类、水生植物、水生无脊椎动物、浮游动物等水生生物对微囊藻毒素生物降解方面的研究进展。目前报道的微囊藻毒素降解菌有鞘氨醇单胞菌、铜绿假单胞菌和青枯菌。鞘氨醇单胞菌和铜绿假单胞菌分别以微囊藻毒素酶和碱性蛋白酶降解毒素,青枯菌降解机理未明;而鱼类、水生植物、水生无脊椎动物、浮游动物等水生生物主要通过谷胱甘肽S-转移酶催化形成低毒性的微囊藻毒素-谷胱甘肽结合物进行转化。本文还对水环境微囊藻毒素的生物修复方式进行了初步的探讨。     

毒蘑菇中毒素的研究进展

误食毒蘑菇而中毒一直都威胁着人类的健康,每年国内外都有大量关于蘑菇中毒的报道。毒蘑菇中毒事件引起了越来越多研究者的关注,特别是对毒蘑菇中的毒素成分,中毒机制以及毒素应用等方面。本文根据毒蘑菇中毒的症状,从肝肾中毒,神经中毒,胃肠道中毒和其他中毒四个方面对已知中毒症状的毒蘑菇中所含的毒素以及毒素的活性进行阐述,并对毒蘑菇和毒素的应用进行展望。     

肉毒毒素检测方法研究进展

肉毒毒素是肉毒梭状芽胞杆菌在生长繁殖过程中产生的一种神经毒素,对人和动物具有强毒性和高致死性。因其制备简单、毒性强,已被列为最具威胁的生物恐怖剂之一,同时也是重要的毒素战剂。在世界范围内,肉毒中毒的案例时有发生,病情严重者一般2~3 d即可能死亡。如果得到正确及时的治疗,可使肉毒中毒死亡率降低,而快速检测方法的建立无疑是成功治疗的前提。我们简要介绍了近年来肉毒毒素的检测方法,包括小鼠生物试验法、免疫法、生物传感器法、荧光共振能量转移法和细胞学检测法,以及研究热点内切酶质谱法。     

肉毒毒素抑制剂的研究进展

肉毒毒素(BoNT)是目前已知的毒性最强的生物毒素,肉毒毒素中毒的抗毒素治疗只对未进入神经细胞的毒素有效,而对中毒时间较长、轻链已进入神经系统者无效。近10年来,随着肉毒毒素晶体结构的测定、中毒机理的深入研究,以及体外高通量评价模型的建立,对小分子肉毒毒素抑制剂的研究取得了显著进展。从肉毒毒素中毒机理、结构特征出发,简要综述了肉毒毒素抑制剂的研究进展。     

我国的毒鱼类

在现存的三万八千种脊椎动物中,鱼类约有二万种以上。我国幅员广大,河流交错,海岸线绵延曲折,鱼类资源极为丰富,约有二千余种,其中海洋鱼类约一千五百余种,淡水鱼类七百余种。其绝大部分可供食用,但有的种类其肌肉或内脏等含有毒素,误食后便会中毒,严重者危及生命。这些体有毒素的鱼类称为毒鱼类(Poisonous fishes)。毒鱼类对人民身体健康有一定的危害,每年因误食毒鱼而中毒的病例时有发生,现将     

微囊藻毒素对鱼类的毒性效应

湖泊富营养化导致的蓝藻水华已成为国内外普遍关注的环境问题,它所带来的主要危害之一是产生的藻毒素对鱼类的影响。在已发现的藻毒素中,微囊藻毒素(microcystins,MCs)的分布广、毒性大、危害严重,而备受关注。阐述了MCs对鱼类的影响。微囊藻毒素能干扰胚胎的发育,降低孵化率,增加畸形率,影响存活率,胚胎孵化受微囊藻毒素影响还具有剂量依赖效应;野外室内实验均表明鱼类暴露于微囊藻毒素后不仅可在肝脏中富集还可在肌肉、肠道等组织器官中快速积累;对鱼类进行组织病理检测发现MCs可导致肝脏、肾脏、心脏、脑、鳃等组织受损;MCs在鱼体中的解毒过程可能开始于由谷胱甘肽S-转移酶催化的还原型谷胱甘肽的结合反应;MCs还可影响鱼类的生长、行为和血清生化指标,此外,还具有一定的免疫毒性。MCs的转运机制和分子作用机制以及在食物链中传递过程中对人类造成的潜在影响可能成为今后研究重点。     

生物毒素检测方法及标准物质研究进展

生物毒素是一类重要的生物来源的活性物质,其生物毒性和活性使得其成为公共安全和药物研发关注的热点。基于质谱、生物传感器等的新型分析技术极大地提高了分析的灵敏度、特异性和准确度,在生物毒素检测中发挥着越来越重要的作用。生物毒素标准物质是保证生物毒素定量检测结果准确、可比和可溯源的重要物质基础,对其迫切的需求使得各国都在研发急需的生物毒素标准物质。现对近年生物毒素检测方法及标准物质的研究现状进行了综述。     

Dynamics of ciguatoxins from Gambierdiscus polynesiensis in the benthic herbivore Mugil cephalus: Trophic transfer implications

This study investigates ciguatoxin dynamics in mullet after controlled feeding of Gambierdiscus polynesiensis cells as a model to characterize the absorption, distribution, retention and accumulation of ciguatoxins into the second trophic level of southwestern Pacific coral reef ecosystems. Mullet (Mugil cephalus) were fed once every other day over a period of 16 days for nine toxic feedings, and ciguatoxin activity was assessed over time in blood and seven tissues using the Neuro2a assay. Within 3 h of feeding on G. polynesiensis cells, ciguatoxins attained maximal blood concentrations, indicating rapid absorption of toxins into the systemic circulation. The time course for distribution of the estimated total tissue burden of ciguatoxin closely followed the time course for blood toxin levels, indicating a rapid distribution of the ciguatoxins throughout the fish body. The large majority (95%) of the ciguatoxin ingested dose was eliminated from the examined fish tissues 24 h after a single toxic meal, indicating little retention potential for ciguatoxin. We found no evidence for ciguatoxin accumulation after nine repeated feedings spaced two days apart, indicating that mullet did not accumulate ciguatoxin. These results provide the first experimental evidence supporting the central tenet of Randall's food chain hypothesis that ciguatoxins enter the food chain by transfer from unicellular algae to herbivorous and detritus-feeding fish. We propose that a time-dependent transformation of oxopene ciguatoxins may be necessary for the concentration of ciguatoxin through higher trophic levels.     

Ciguatera: neurophysiologic and histoenzymologic studies of several fractions of ciguatoxic extracts]

Two fractions of ciguatoxic extracts were isolated by chromatography. The first showed anticholinesterasic properties, while the other acted directly on the muscular fibre. These findings were histoenzymologically confirmed. Controls with non-toxic extracts of fishes from the coral benthos reinforce the theory of the ecological origins of ciguatoxins.     

Novel species interactions and environmental conditions reduce foraging competency at the temperate range edge of a range-extending coral reef fish

Poleward range extensions of coral reef species can reshuffle temperate communities by generating competitive interactions that did not exist previously. However, novel environmental conditions and locally adapted native temperate species may slow tropical invasions by reducing the ability of invaders to access local resources (e.g. food and shelter). We test this hypothesis on wild marine fish in a climate warming hotspot using a field experiment encompassing artificial prey release. We evaluated seven behaviours associated with foraging and aggressive interactions in a common range-extending coral reef fish (Abudefduf vaigiensis) and a co-shoaling temperate fish (Microcanthus strigatus) along a latitudinal temperature gradient (730 km) in SE Australia. We found that the coral reef fish had reduced foraging performance (i.e. slower prey perception, slower prey inspection, decreased prey intake, increased distance to prey) in their novel temperate range than in their subtropical range. Furthermore, higher abundance of temperate fishes was associated with increased retreat behaviour by coral reef fish (i.e. withdrawal from foraging on released prey), independent of latitude. Where their ranges overlapped, temperate fish showed higher foraging and aggression than coral reef fish. Our findings suggest that lower foraging performance of tropical fish at their leading range edge is driven by the combined effect of environmental factors (e.g. lower seawater temperature and/or unfamiliarity with novel conditions in their extended temperate ranges) and biological factors (e.g. increased abundance and larger body sizes of local temperate fishes). Whilst a future increase in ocean warming is expected to alleviate current foraging limitations in coral reef fishes at leading range edges, under current warming native temperate fishes at their trailing edges appear able to slow the range extension of coral reef fishes into temperate ecosystems by limiting their access to resources.

     

Interactions between coral restoration and fish assemblages: implications for reef management

Corals create complex reef structures that provide both habitat and food for many fish species. Because of numerous natural and anthropogenic threats, many coral reefs are currently being degraded, endangering the fish assemblages they support. Coral reef restoration, an active ecological management tool, may help reverse some of the current trends in reef degradation through the transplantation of stony corals. Although restoration techniques have been extensively reviewed in relation to coral survival, our understanding of the effects of adding live coral cover and complexity on fishes is in its infancy with a lack of scientifically validated research. This study reviews the limited data on reef restoration and fish assemblages, and complements this with the more extensive understanding of complex interactions between natural reefs and fishes and how this might inform restoration efforts. It also discusses which key fish species or functional groups may promote, facilitate or inhibit restoration efforts and, in turn, how restoration efforts can be optimised to enhance coral fish assemblages. By highlighting critical knowledge gaps in relation to fishes and restoration interactions, the study aims to stimulate research into the role of reef fishes in restoration projects. A greater understanding of the functional roles of reef fishes would also help inform whether restoration projects can return fish assemblages to their natural compositions or whether alternative species compositions develop, and over what timeframe. Although alleviation of local and global reef stressors remains a priority, reef restoration is an important tool; an increased understanding of the interactions between replanted corals and the fishes they support is critical for ensuring its success for people and nature.     

Detection of ciguatoxins: advantages and drawbacks of different biological methods

Ciguatera is a seafood intoxication that results from ingestion of reef fish contaminated with ciguatoxins at levels orally toxic for humans. Precursors of those toxins, gambiertoxins, are produced by benthic dinoflagellates (genus Gambierdiscus), and then accumulated and biotransformed by herbivorous and carnivorous fishes into ciguatoxins, more toxic for humans. In the absence of specific treatment, that disease remains a health problem with otherwise adverse socio-economic impacts. Thus a cost-effective means of detecting ciguatoxins in fish has long been searched for. Many assays have been developed, including in vivo, in vitro, chemical or immunochemical approaches. This review focuses on some biological methods, from the well-standardised mouse assay to the specific radio-labelled ligand binding assay that is performed on rat brain synaptosomes. In addition to the mouse, the chick and the mongoose were still recently used, in particular for preliminary tests before ciguatoxin extraction from fish, since assays in these animals can directly assay the whole flesh. In contrast, various other in vivo methods, such as the kitten, mosquito and diptera larvae assays, were abandoned despite their interesting results. Finally, the mouse neuroblastoma and rat brain synaptosome assays, carried out in vitro as alternative approaches to animal-using assays, are highly sensitive and much more specific than the in vivo methods to detect ciguatoxins.     

Importance of live coral habitat for reef fishes

Live corals are the key habitat forming organisms on coral reefs, contributing to both biological and physical structure. Understanding the importance of corals for reef fishes is, however, restricted to a few key families of fishes, whereas it is likely that a vast number of fish species will be adversely affected by the loss of live corals. This study used data from published literature together with independent field based surveys to quantify the range of reef fish species that use live coral habitats. A total of 320 species from 39 families use live coral habitats, accounting for approximately 8 % of all reef fishes. Many of the fishes reported to use live corals are from the families Pomacentridae (68 spp.) and Gobiidae (44 spp.) and most (66 %) are either planktivores or omnivores. 126 species of fish associate with corals as juveniles, although many of these fishes have no apparent affiliation with coral as adults, suggesting an ontogenetic shift in coral reliance. Collectively, reef fishes have been reported to use at least 93 species of coral, mainly from the genus Acropora and Porities and associate predominantly with branching growth forms. Some fish associate with a single coral species, whilst others can be found on more than 20 different species of coral indicating there is considerable variation in habitat specialisation among coral associated fish species. The large number of fishes that rely on coral highlights that habitat degradation and coral loss will have significant consequences for biodiversity and productivity of reef fish assemblages.     

Human activities as a driver of spatial variation in the trophic structure of fish communities on Pacific coral reefs

Anthropogenic activities such as land‐use change, pollution and fishing impact the trophic structure of coral reef fishes, which can influence ecosystem health and function. Although these impacts may be ubiquitous, they are not consistent across the tropical Pacific Ocean. Using an extensive database of fish biomass sampled using underwater visual transects on coral reefs, we modelled the impact of human activities on food webs at Pacific‐wide and regional (1,000s–10,000s km) scales. We found significantly lower biomass of sharks and carnivores, where there were higher densities of human populations (hereafter referred to as human activity); however, these patterns were not spatially consistent as there were significant differences in the trophic structures of fishes among biogeographic regions. Additionally, we found significant changes in the benthic structure of reef environments, notably a decline in coral cover where there was more human activity. Direct human impacts were the strongest in the upper part of the food web, where we found that in a majority of the Pacific, the biomass of reef sharks and carnivores were significantly and negatively associated with human activity. Finally, although human‐induced stressors varied in strength and significance throughout the coral reef food web across the Pacific, socioeconomic variables explained more variation in reef fish trophic structure than habitat variables in a majority of the biogeographic regions. Notably, economic development (measured as GDP per capita) did not guarantee healthy reef ecosystems (high coral cover and greater fish biomass). Our results indicate that human activities are significantly shaping patterns of trophic structure of reef fishes in a spatially nonuniform manner across the Pacific Ocean, by altering processes that organize communities in both “top‐down” (fishing of predators) and “bottom‐up” (degradation of benthic communities) contexts.     

A pilot study of the cognitive and psychological correlates of chronic ciguatera poisoning

Ciguatera fish poisoning is the most frequently reported seafood-toxin illness in the world, caused by the consumption of coral reef fishes contaminated with a group of natural toxins produced by minute phytoplankton (dinoflagellates). These toxins are potent and cause both acute and chronic neurologic disease in humans.Although ciguatera fish poisoning is associated with established neurotoxins in animal models, and with known peripheral nervous system effects in humans, this pilot study was the first to explore possible central nervous system effects associated with chronic ciguatera poisoning in humans. In a matched cohort design, 12 cases and 12 their age and gender matched friend controls underwent a battery of neuropsychological tests. The results indicated that although their scores on objective neuropsychological tests did not differ significantly from matched controls, persons with ciguatera reported a higher degree of toxicity-related symptomatology and endorsed significantly more depressive symptomatology than controls. Future research should explore larger numbers of persons with both acute and chronic ciguatera, with and without mannitol treatment.     

Coral and Fish Biocoenosis: Ecological Cells Gradually Maturing in Complexity, Species Composition and Energy Turnover

Long-term observations on coral units and their coral fishes, as well as observations on the growth of colonies of marked corals in the Gulf of Aqaba (Red Sea), have revealed the relationship between coral dimension and complexity and the ecomorphology and sociobiology of the inhabiting fishes. In this study, coral fishes are identified as species that, following the planktonic interval, settle and remain in a selected coral or its immediate vicinity. Parallel with growth of the refuge, the number of fishes in such a coral–fish association (=ecological cell) increases to a certain asymptote, forming a stable symbiotic entity of fish species, specific in composition and biomass. The initial cell begins with 4–5-year-old branching corals that harbors 3–4 cryptic species of gobies (Paragobiodon and Gobiodon species). This is followed by several stages of coral growth and increase in fish species and biomass, especially of pomacentrids, anthiases, pseudochromids and blennies. The water column or functional space from which the fishes harvest plankton, their main food source, starts at around a 0.2m³ column in the young colonies, and ends with a water column of around 500m³ in the mature ecological cells of large coral knolls. At the mature stage, large cells harbor up to 100 diurnal and nocturnal species of fish, permanently using this refuge and forming an integrated collective. The territorial limits of the piscivorous groupers (Cephalopholis species) generally establish the dimensions of these ecological cells. Preliminary data on standard energy metabolism of the fishes for mature ecological cells reveal that 800kg food is required each year to maintain this biomass. The biological composition and stability of fish populations of such ecological cells will depend on the biological and physical stability of the host coral population.     

Habitat choice,recruitment and the response of coral reef fishes to coral degradation

The global degradation of coral reefs is having profound effects on the structure and species richness of associated reef fish assemblages. Historically, variation in the composition of fish communities has largely been attributed to factors affecting settlement of reef fish larvae. However, the mechanisms that determine how fish settlers respond to different stages of coral stress and the extent of coral loss on fish settlement are poorly understood. Here, we examined the effects of habitat degradation on fish settlement using a two-stage experimental approach. First, we employed laboratory choice experiments to test how settlers responded to early and terminal stages of coral degradation. We then quantified the settlement response of the whole reef fish assemblage in a field perturbation experiment. The laboratory choice experiments tested how juveniles from nine common Indo-Pacific fishes chose among live colonies, partially degraded colonies, and dead colonies with recent algal growth. Many species did not distinguish between live and partially degraded colonies, suggesting settlement patterns are resilient to the early stages of declining coral health. Several species preferred live or degraded corals, and none preferred to associate with dead, algal-covered colonies. In the field experiment, fish recruitment to coral colonies was monitored before and after the introduction of a coral predator (the crown-of-thorns starfish) and compared with undisturbed control colonies. Starfish reduced live coral cover by 95–100%, causing persistent negative effects on the recruitment of coral-associated fishes. Rapid reductions in new recruit abundance, greater numbers of unoccupied colonies and a shift in the recruit community structure from one dominated by coral-associated fishes before degradation to one predominantly composed of algal-associated fish species were observed. Our results suggest that while resistant to coral stress, coral death alters the process of replenishment of coral reef fish communities.