Pathogens as a factor limiting the spread of cannibalism in tiger salamanders

Summary Intraspecific predation is taxonomically widespread, but few species routinely prey on conspecifics. This is surprising as conspecifics could be a valuable resource for animals limited by food. A potential cost of cannibalism that has been largely unexplored is that it may enhance the risk of acquiring debilitating pathogens or toxins from conspecifics. We examined how pathogens affect variation in the incidence of cannibalism in tiger salamander larvae (Ambystoma tigrinum nebulosum), which occur as two environmentally-induced morphs, typicals and cannibals. Salamanders from one population were more likely than those in another to develop into cannibals, even when reared under identical conditions. Variation in the propensity to become a cannibal may be caused by variation in pathogen density. In the population with cannibals at low frequency, bacterial blooms in late summer correlated with massive die-offs of salamanders. The frequency of cannibals correlated significantly negatively with bacterial density in ten different natural lakes. In the laboratory, cannibals exposed to a diseased conspecific always preyed on the sick animal. As a result, cannibals wre more likely to acquire and die from disease than were typicals that were similarly exposed, or cannibals that were exposed to healthy conspecifics. Since conspecifics often share lethal pathogens, enhanced risk of disease may explain why cannibalism is generally infrequent. Pathogens may constrain not only the tendency to be behaviorally cannibalistic, but also the propensity to develop specialized cannibal morphologies.     

Low MHC DRB class II diversity in the mountain goat: past bottlenecks and possible role of pathogens and parasites

Major histocompatibility complex (MHC) genes are the most polymorphic in vertebrates and code for molecules playing a central role in pathogen resistance. We studied levels of MHC DRB class II diversity in a long-term study population of mountain goats (Oreamnos americanus) at Caw Ridge, Alberta, and two other populations from British Columbia, Canada. Only two alleles were found among the three populations sampled. The Caw Ridge population was fixed for one of the two MHC DRB alleles, but this lack of variation did not appear to have affected it negatively because the population doubled over two decades and had no history of any apparent infectious diseases. Past population bottlenecks during Pleistocene glaciations are thought to have been the main factor contributing to the low levels of MHC diversity in mountain goats, a hypothesis supported by our previous work reporting low polymorphism at neutral loci. Additionally, the limited MHC variability in mountain goats may be related to its northern distribution as we found that allelic diversity at MHC DRB class II in wild ungulates decreases with increasing latitude, possibly as a result of low parasite diversity at high latitudes. The low MHC variation in mountain goats and other northern ungulates such as muskoxen (Ovibos moschatus) may expose these species to population outbreaks that could be generated by introduced pathogens or northward shifts in the distribution of pathogens with global climate warming.     

Salt tolerant Methylobacterium mesophilicum showed viable colonization abilities in the plant rhizosphere

The source of infection has always been considered as an important factor in epidemiology and mostly linked to environmental source such as surface water, soil, plants and also animals. The activity of the opportunistic pathogens associated with plant root, their adaptation and survival under hostile environmental condition is poorly understood. In this study the salt tolerance ability of Methylobacterium mesophilicum and its colonization in the root and shoot of plants under severe drought and salt stress conditions were investigated. The colonization of plant by M. mesophilicum was investigated in a gnotobiotic sand system, and their survival in pots with saline soil. Bacterial strain was found to colonize rhizosphere of cucumber, tomato and paprika grown under normal and salt stress condition and reached up to 6.4 × 10⁴ and 2.6 × 10⁴ CFU/g root. The strain was resistant to Gentamicin, Ampicillin, Amoxicillin plus Clavulanic acid, Cefotaxime, neomycin, penicillin and was also tolerant to salinity stress (up to 6% NaCl). These abilities play important roles in enabling persistent colonization of the plant surface by M. mesophilicum strains. In conclusion, this study provides background information on the behaviour of opportunistic pathogen M. mesophilicum on plants and their survival in harsh environmental conditions.     

320例腹泻患者病原菌分离及流行病学分析

目的了解广州市2009年至2010年肠道门诊就诊的细菌性腹泻患者病原谱的分布情况,为制定针对重点人群肠道传染病防治策略提供依据。方法收集2009年5月至2010年5月暨南大学附属第一医院腹泻患者的粪便标本,使用卡-布运送培养基,增菌培养后,采用生化反应和氧化酶试验进行菌株鉴定,并用梅里埃API生化板条进行验证,用病原菌诊断血清进行细菌分型。结果从320份粪便标本中分离到38株菌株,其中沙门菌15株,产毒大肠埃希菌12株,致病大肠埃希菌6株,志贺菌2株,出血性大肠埃希菌、霍乱弧菌、气单胞菌各1株。0—20岁年龄段高发,以1岁以内婴幼儿为主;7—10月为发病高峰期。结论来该院肠道门诊就诊的细菌性腹泻患者,其病原体以沙门菌为主,其次为产毒大肠埃希菌。因此．广州地区细菌件腹泻的预防．廊右针对件的面向雷占人群和重占病厢莴．     

Bioaerosols associated with animal production operations

Air emissions from animal housing and manure management operations include a complex mixture of biological, microbial, and inorganic particulates along with odorous volatile compounds. This report highlights the state of current issues, technical knowledge, and remaining challenges to be addressed in evaluating the impacts of airborne microorganisms, dusts, and odorants on animals and workers at animal production facilities and nearby communities. Reports documenting bioaerosol measurements illustrate some of the technical issues related to sample collection, analysis, as well as dispersion and transport to off-farm locations. Approaches to analysis, mitigation and modeling transport are discussed in the context of the risk reduction and management of airborne spread of bioaerosols from animal operations. The need for standardization and validation of bioaerosol collection and analytical techniques for indoor as well as outdoor animal agriculture settings is critical to evaluation of health effects from modern animal production systems that are increasingly situated near communities.     

军队干部病房与普通病房患者下呼吸道感染病原菌对比分析

目的调查干部病房与普通病房患者下呼吸道感染病原菌的分布状况,为临床经验用药治疗提供参考。方法采用回顾性方法对2009年5月至2010年2月解放军第44医院干部病房与普通病房下呼吸道感染住院患者送检痰培养结果进行统计分析。结果两个病区下呼吸道感染病原菌均以G-杆菌为主,干部病房G-杆菌所占比例低于普通病房,而真菌、耐甲氧西林金黄色葡萄球菌及产超广谱β-内酰胺酶细菌检出率高于普通病区。结论干部病房与普通病房患者下呼吸道感染病原菌存在差异,干部病房患者感染病原菌多以多重耐药菌株为主,临床应根据药敏结果使用抗菌药物。     

Baseline criteria and the evolution of hosts and parasites: D0, R0 and competition for resources between strains

Our understanding of the evolution of diseases has been greatly aided by the use of baseline criteria. Here we examine the theoretical and biological relationships of the well known baseline criteria for the evolution of disease (R0) and the recently introduced corresponding criterion for the evolution of resistance in hosts (D0). We show that there is a formal theoretical equivalence between the two criteria and discuss the characteristics of seperability that determine whether the criteria define the course of evolution. These theoretical determinants correspond biologically to whether strains compete for resources or not. We discuss the biological application of the criteria and argue that D0 may be less widely applicable than R0, but does determine the evolution of resistance in populations with fixed carrying capacities.     

Cultivation Optimization of Insect-Pathogenic Fungi PaecUomyces lilacinus HY-4 to Soil-pest Adoretus tenuimaculatus

ABSTRACT A new insect pathogenic fungi, Paecilomyces licacinus HY-4 that was isolated from soil sample, showed biological activity to Chestnut Brown Chafer, pest of golf course. The culture condition for the fungi P. lilacinus HY-4 was optimized through statistical approach for the mass production. According th the bioassay on the pest, the insecticidal activity reached up to 30%, and positive factor for the production of the fungi was zeolite with 97.5% of significance.     

Antimicrobial activity of chemically and biologically synthesized silver nanoparticles against some fish pathogens

Pathogens isolated from fish appear to possess considerable antimicrobial resistance and represent a problem for the economy and public health. Natural antimicrobial substitutes to traditional antibiotics represent an essential tool in the fight against antibiotic resistance. Nanotechnology has shown considerable potential in different research fields, and the antimicrobial properties of silver nanoparticles are known. Silver has been used for medical purposes since ancient times because of its bactericidal properties, and the highly reactive surfaces of silver nanoparticles (AgNPs) indicate that they might have a function in antimicrobial applications. This work aimed to study the antimicrobial properties of biologically produced AgNPs from Origanum vulgare leaves compared to chemically produced AgNPs. Both types were characterized by UV–vis spectrophotometry, TEM, and dynamic light scattering and tested against three bacterial strains (Streptococcus agalactiae, and Aeromonas hydrophila, both isolated from Nile tilapia and Vibrio alginolyticus, isolated from sea bass) and three fungal strains (Aspergillus flavus, Fusarium moniliforme, and Candida albicans, all isolated from Nile tilapia). Disk diffusion test and evaluation of ultrastructure changes of tested microorganisms treated with AgNPs by transmission electron microscopy were performed. Moreover, the hemolytic properties of AgNPs were studied on chicken and goat red blood cells. The results obtained declare that the green biological production of silver nanoparticles is safer and more effective than the chemical one; moreover, AgNPs have interesting dose-dependent antimicrobial properties, with better results for biologically produced ones; their effectiveness against tested bacterial and fungal strains opens the way to their use to limit fish diseases, increase economy and improve human health.     

Oligo-chip based detection of tick-borne bacteria

We have developed an oligonucleotide-chip based assay for detection of 16S ribosomal PCR products from tick-borne bacteria. This chip contains 14 specific probes, which target variable regions of 16S rDNA of tick-borne bacteria including Borrellia spp., Rickettsia spp., Anaplasma spp., Coxiella burnetii and Francisella tularensis. The specificity of these probes was tested by hybridization of the chip with fluorescently labeled PCR products amplified from the genomic DNA of selected tick-borne bacteria. The assay was also tested for detection of tick-borne bacteria in single ticks.