中国拥有数目庞大、种类繁多的动植物,也有很多珍贵、濒危生物,这些更是异常宝贵的科学资源。DNA条形码技术的出现可以更好的帮助鉴别这些物种,了解其分支来源,甚至可以预知其进化方向。笔者简述了DNA条形码的技术原理与操作步骤及这项技术的产生与发展情况;简要列出了DNA条形码发展过程中的重要进步与研究相对集中的物种;概述了DNA条形码的应用途径及目前DNA条形码研究中存在的主要问题、矛盾、研究思路与发展方向,并对其发展前景做出展望。

国际生命条形码计划—DNA Barcoding

Over the past decade, a significant increase in the circulation of infectious agents was observed. With the spread and emergence of epizootics, zoonoses, and epidemics, the risks of pandemics became more and more critical. Human and animal health has also been threatened by antimicrobial resistance, environmental pollution, and the development of multifactorial and chronic diseases. This highlighted the increasing globalization of health risks and the importance of the human-animal-ecosystem interface in the evolution and emergence of pathogens. A better knowledge of causes and consequences of certain human activities, lifestyles, and behaviors in ecosystems is crucial for a rigorous interpretation of disease dynamics and to drive public policies. As a global good, health security must be understood on a global scale and from a global and crosscutting perspective, integrating human health, animal health, plant health, ecosystems health, and biodiversity. In this study, we discuss how crucial it is to consider ecological, evolutionary, and environmental sciences in understanding the emergence and re-emergence of infectious diseases and in facing the challenges of antimicrobial resistance. We also discuss the application of the "One Health" concept to non-communicable chronic diseases linked to exposure to multiple stresses, including toxic stress, and new lifestyles. Finally, we draw up a list of barriers that need removing and the ambitions that we must nurture for the effective application of the "One Health" concept. We conclude that the success of this One Health concept now requires breaking down the interdisciplinary barriers that still separate human and veterinary medicine from ecological, evolutionary, and environmental sciences. The development of integrative approaches should be promoted by linking the study of factors underlying stress responses to their consequences on ecosystem functioning and evolution. This knowledge is required for the development of novel control strategies inspired by environmental mechanisms leading to desired equilibrium and dynamics in healthy ecosystems and must provide in the near future a framework for more integrated operational initiatives.

/pdf/the-one-health-concept-10-years-old-and-a-long-road-ahead-3cw8v0vm79.pdf

The one health concept: 10 years old and a long road ahead

Mass mortality of amphibians has occurred globally since at least the early 1990s from viral pathogens that are members of the genus Ranavirus, family Iridoviridae. The pathogen infects multiple amphibian hosts, larval and adult cohorts, and may persist in herpetofaunal and oste- ichthyan reservoirs. Environmental persistence of ranavirus virions outside a host may be several weeks or longer in aquatic systems. Transmission occurs by indirect and direct routes, and includes exposure to contaminated water or soil, casual or direct contact with infected individuals, and inges- tion of infected tissue during predation, cannibalism, or necrophagy. Some gross lesions include swelling of the limbs or body, erythema, swollen friable livers, and hemorrhage. Susceptible amphi- bians usually die from chronic cell death in multiple organs, which can occur within a few days fol- lowing infection or may take several weeks. Amphibian species differ in their susceptibility to rana- viruses, which may be related to their co-evolutionary history with the pathogen. The occurrence of recent widespread amphibian population die-offs from ranaviruses may be an interaction of sup- pressed and naive host immunity, anthropogenic stressors, and novel strain introduction. This review summarizes the ecological research on amphibian ranaviruses, discusses possible drivers of emer- gence and conservation strategies, and presents ideas for future research directions. We also discuss common pathological signs of ranaviral disease, methods for diagnostic evaluation, and ranavirus surveillance methods. Inasmuch as ranaviral disease is listed as a notifiable disease by the World Organization for Animal Health and is a threat to amphibian survival, we recommend that biosecu- rity precautions are implemented by nations to reduce the likelihood of transporting ranavirus virions among populations. Biosecurity precautions include disinfecting footwear and equipment that comes in contact with surface water inhabited by amphibians and testing commercially shipped amphibians for the pathogen. We also encourage natural resource organizations to establish routine surveillance programs for ranaviruses in wild amphibian populations.

/pdf/ecology-and-pathology-of-amphibian-ranaviruses-1vff5asd5a.pdf

Ecology and pathology of amphibian ranaviruses.

Ranaviruses are capable of infecting amphibians from at least 14 families and over 70 individual species. Ranaviruses infect multiple cell types, often culminating in organ necrosis and massive hemorrhaging. Subclinical infections have been documented, although their role in ranavirus persistence and emergence remains unclear. Water is an effective transmission medium for ranaviruses, and survival outside the host may be for significant duration. In aquatic communities, amphibians, reptiles and fish may serve as reservoirs. Controlled studies have shown that susceptibility to ranavirus infection and disease varies among amphibian species and developmental stages, and likely is impacted by host-pathogen coevolution, as well as, exogenous environmental factors. Field studies have demonstrated that the likelihood of epizootics is increased in areas of cattle grazing, where aquatic vegetation is sparse and water quality is poor. Translocation of infected amphibians through commercial trade (e.g., food, fish bait, pet industry) contributes to the spread of ranaviruses. Such introductions may be of particular concern, as several studies report that ranaviruses isolated from ranaculture, aquaculture, and bait facilities have greater virulence (i.e., ability to cause disease) than wild-type isolates. Future investigations should focus on the genetic basis for pathogen virulence and host susceptibility, ecological and anthropogenic mechanisms contributing to emergence, and vaccine development for use in captive populations and species reintroduction programs.

/pdf/ecopathology-of-ranaviruses-infecting-amphibians-515rn2t41q.pdf

Ecopathology of ranaviruses infecting amphibians.

In a fast changing world with growing concerns about biodiversity loss and an increasing number of animal and human diseases emerging from wildlife, the need for effective wildlife health investigations including both surveillance and research is now widely recognized. However, procedures applicable to and knowledge acquired from studies related to domestic animal and human health can be on partly extrapolated to wildlife. This article identifies requirements and challenges inherent in wildlife health investigations, reviews important definitions and novel health investigation methods, and proposes tools and strategies for effective wildlife health surveillance programs. Impediments to wildlife health investigations are largely related to zoological, behavioral and ecological characteristics of wildlife populations and to limited access to investigation materials. These concerns should not be viewed as insurmountable but it is imperative that they are considered in study design, data analysis and result interpretation. It is particularly crucial to remember that health surveillance does not begin in the laboratory but in the fields. In this context, participatory approaches and mutual respect are essential. Furthermore, interdisciplinarity and open minds are necessary because a wide range of tools and knowledge from different fields need to be integrated in wildlife health surveillance and research. The identification of factors contributing to disease emergence requires the comparison of health and ecological data over time and among geographical regions. Finally, there is a need for the development and validation of diagnostic tests for wildlife species and for data on free-ranging population densities. Training of health professionals in wildlife diseases should also be improved. Overall, the article particularly emphasizes five needs of wildlife health investigations: communication and collaboration; use of synergies and triangulation approaches; investments for the long term; systematic collection of metadata; and harmonization of definitions and methods.

/pdf/wildlife-health-investigations-needs-challenges-and-2zvvc78nvz.pdf

Wildlife health investigations: needs, challenges and recommendations.

Environmental change has negatively affected most biological systems on our planet and is becoming of increasing concern for the well-being and survival of many species. At an organism level, effects encompass not only endocrine disruptions, sex-ratio changes and decreased reproductive parameters, but also include teratogenic and genotoxic effects, immunosuppression and other immune-system impairments that can lead directly to disease or increase the risk of acquiring disease. Living organisms will strive to maintain health by recognizing and resolving abnormal situations, such as the presence of invading microorganisms or harmful peptides, abnormal cell replication and deleterious mutations. However, fast-paced environmental changes may pose additional pressure on immunocompetence and health maintenance, which may seriously impact population viability and persistence. Here, we outline the importance of a functional immune system for survival and examine the effects that exposure to a rapidly changing environment might exert on immunocompetence. We then address the various levels at which anthropogenic environmental change might affect wildlife health and identify potential deficits in reproductive parameters that might arise owing to new immune challenges in the context of a rapidly changing environment. Throughout the paper, a series of examples and case studies are used to illustrate the impact of environmental change on wildlife health.

/pdf/effects-of-environmental-change-on-wildlife-health-1l2a12g2xg.pdf

Effects of environmental change on wildlife health

Ranaviruses are globally distributed pathogens in amphibian, fish, and reptile communities that appear to be emerging. Cases of ranavirus infection or disease have been confirmed in at least 105 amphibian species (18 families), 41 fish species (22 families), and 29 reptile species (12 families). Ranaviruses have been documented on all continents except Antarctica, and are frequently associated with mass die-offs. Host susceptibility differs among species, with some species harboring subclinical infections and likely serving as reservoirs for the virus, and other highly susceptible species amplifying the virus. Currently, there are six recognized species of ranavirus, and all are not equally pathogenic among hosts. Frog virus 3 (FV3) is the type species of the genus Ranavirus, and appears to be the most globally distributed species infecting ectothermic taxonomic across three vertebrate classes. International commerce involving subclinically infected ectothermic vertebrates undoubtedly has contributed to the global distribution and emergence of ranaviruses. Herein, we describe the global distributed species infecting ectothermic vertebrates across three taxonomic classes.

/pdf/distribution-and-host-range-of-ranaviruses-av943xh124.pdf

Distribution and Host Range of Ranaviruses

Emerging infectious diseases are a significant threat to global biodiversity. While historically overlooked, a group of iridoviruses in the genus Ranavirus has been responsible for die-offs in captive and wild amphibian, reptile and fish populations around the globe over the past two decades. In order to share contemporary information on ranaviruses and identify critical research directions, the First International Symposium on Ranaviruses was held in July 2011 in Minneapolis, MN, USA. Twenty-three scientists and veterinarians from nine countries examined the ecology and evolution of ranavirus–host interactions, potential reservoirs, transmission dynamics, as well as immunological and histopathological responses to infection. In addition, speakers discussed possible mechanisms for die-offs, and conservation strategies to control outbreaks.

/pdf/ranavirus-past-present-and-future-2bmicvht7w.pdf

Ranavirus: past, present and future

Frog virus 3 (FV3) and FV3-like viruses, are members of the genus Ranavirus (family Iridoviridae), and they have been associated with infectious diseases that may be contributing to amphibian population declines. We examined the mode of transmission of an FV3-like virus, and potential hosts and reservoirs of the virus in a local amphibian community. Using the polymerase chain reaction to detect infected animals, we found an FV3-like virus in south-central Ontario, Canada, amphibian communities, where it infects sympatric amphibian species, including ranid and hylid tadpoles (Rana sylvatica, Hyla versicolor, and Pseudacris spp.), larval salamanders (Ambystoma spp.), and adult eastern-spotted newts (Notophthalmus viridescens). The high prevalence of FV3-like infections in caudate larvae suggests that salamanders are likely to be both hosts and reservoirs. In laboratory FV3 challenges of R. sylvatica, the rate of infection was dependent on the amount of virus to which the animals were exposed. In addition, although vertical transmission was suspected, horizontal transmission through exposure to infected pond water is the most likely route of infection in tadpoles. Based on our observations, a simple model of FV3/FV3-like virus transmission postulates that, in aquatic amphibian communities, transmission of the virus occurs between anuran and urodele species, with ambystomatid salamanders the most likely reservoir for the ranavirus in our study.

Frog virus 3-like infections in aquatic amphibian communities.

Disease threats to amphibians in Europe are generally poorly understood. The effects that disease can have on amphibian populations can range from minimal to local extirpation. Currently, two infectious agents are emerging as disease threats to European amphibian populations: Batracbochytrium dendrobatidis (Bd), which is the causative agent of amphibian chytridiomycosis, and ranavirus(es). Both pathogens are listed by the World Organization for Anima) Health (OIE). The incidence of other infectious diseases, such as amphibiocystidium, might also be increasing. In this review, we discuss known and potential disease threats to European amphibians, including their current and potential impact on amphibian populations, and factors driving their emergence and spread. We provide recommendations on how to proceed with investigations into cases where disease is thought to be involved in mortality or decline. We also stress that a multidisciplinary approach to these investigations is required.

Amanda L. J. Duffus

Papers

Effects of environmental change on wildlife health

Distribution and Host Range of Ranaviruses

Ranavirus: past, present and future

Frog virus 3-like infections in aquatic amphibian communities.

Major disease threats to European amphibians