Effects of environmental pollution on microsatellite DNA diversity in wood mouse (Apodemus sylvaticus) populations

Ten microsatellite DNA loci were surveyed to investigate the effects of heavy metal pollution on the genetic diversity and population genetic structure of seven wood mouse (Apodemus sylvaticus) populations along a heavy metal pollution gradient away from a nonferrous smelter in the south of Antwerp (Flanders, Belgium). Analysis of soil heavy metal concentrations showed that soil Ag, As, Cd, Cu, and Pb decreased with increasing distance from the smelter. Genetic analyses revealed high levels of genetic variation in all populations, but populations from the most polluted sites in the gradient did not differ from those of less-polluted sites in terms of mean observed and expected heterozygosity level and mean allelic richness. No correlation was found between measures of genetic diversity and the degree of heavy metal pollution. However, an analysis of molecular variance and a neighbor-joining tree suggested a contamination-related pattern of genetic structuring between the most polluted and less polluted sites. Pairwise F(ST) values indicated that populations were significantly genetically differentiated, and assignment tests and direct estimates of recent migration rates suggested restricted gene flow among populations. Additionally, genetic differentiation increased significantly with geographical distance, which is consistent with an isolation-by-distance model. We conclude that, at least for our microsatellite DNA markers, genetic diversity in the studied wood mouse populations is not affected greatly by the heavy metal pollution.     

Metal (Cu, Zn, Fe, Pb) concentrations in human placentas

The concentrations of some metals (Cu, Zn, Fe, Pb) in human placentas at term in two populations living in polluted (Krakow, n = 10) and non-polluted (Bieszczady, n = 13) areas were investigated by means of graphite furnace--or flame atomic absorption spectrometry (GF-AAS or F-AAS). The concentrations of Cu, Fe and Pb were higher in Krakow vs. Bieszczady, while Zn concentration was lower, but these differences were not significant. The following results were obtained for the whole studied group: Cu 1.17 +/- 0.25 microg/g w.w., Zn 8.44 +/- 2.10 microg/g w.w., Fe 115.0 +/- 31.9 microg/g w.w., Pb 51.6 +/- 18.0 ng/g w.w. The inverse accumulation of Zn and Pb is in accord with previous observations. In the whole group of placenta specimens the statistically significant correlation was also found between concentrations of Cu and Pb. The correlations between metal concentrations and placental or maternal features were the strongest for lead.     

Pollution-induced community tolerance and functional redundancy in a decomposer food web in metal-stressed soil

Pollution may lead to the development of pollution-induced community tolerance (PICT) in a stressed community. We studied the presence of PICT in soil food webs using soil microcosms. Soil microcosms containing soil invertebrates and microbes were collected from polluted and unpolluted areas and exposed to a range of soil zinc concentrations. A pine seedling was planted in each microcosm to measure the effects of the origin of the community and Zn pollution on above-ground plant production. The effects of the treatments on nutrient content in the soil were also measured. The diversity of soil microarthropods and the soil's mineral nutrient content were low at the Zn-polluted site. We did not observe an increasing Zn tolerance among the soil organisms in the polluted soil. However, low population growth rates of soil invertebrates from the polluted site may indicate the deleterious effects on fitness of long-lasting pollution. In the soil from the nonpolluted site, Zn additions caused changes in the invertebrate food web structure. These changes were explained by the good physiological condition of the animals and their insensitivity to Zn. The fact that the food web structure in soil from the polluted site did not change can be used as a rough indicator of PICT. Structural stability is presumed by the lack of Zn-sensitive species at this site and the inability of populations to acclimate by altering their growth or reproduction patterns in response to changing soil conditions. Although microbial-based soil decomposer systems may have a high functional redundancy, our results indicate that metal stress at the polluted site exceeds the tolerance limits of the system. As a consequence, ecosystem function at this site is endangered. This study also shows that the evolution of metal tolerance by soil decomposer organisms may not be a common reaction to soil pollution, although changes of population and community structure indicated severe metal stress on organisms.     

Adaptation to soil pollution by cadmium excretion in natural populations of Orchesella cincta (L.) (Collembola)

Population differentiation in Orchesella cincta (L.) (Collembola) populations, from various heavy metal contaminated sites, was studied by comparing cadmium excretion efficiency in first generation (F₁) laboratory individuals. Animals from sites with high metal concentrations in the litter and with a long history of contamination showed significantly higher excretion efficiencies than animals from low pollution, or reference sites. Differences found in the F₁ laboratory animals suggest evidence for genetic differences between the populations.Beneficial and detrimental effects of cadmium excretion were studied in relation to body growth and cadmium concentrations. In chronically exposed animals from an unpolluted site, no physiological acclimation was observed. Excretion efficiency was negatively correlated with body concentrations of cadmium. No detrimental effects were found.Whole-body equilibrium concentrations of cadmium and lead were similar in F₁ animals from the reference site and polluted sites. Significant differences in excretion efficiencies imply that the distribution of toxic metals over body compartments differs, tolerant populations having a higher proportion deposited in the gut. Body concentrations of zinc were consistently higher in animals from the polluted site, during both cadmium and zinc exposure. No detrimental effects of increased cadmium excretion on body concentrations of zinc were observed. Population comparisons of cadmium excretion efficiency data and growth reduction in F₁ laboratory animals showed that both parameters were inversely related. Cadmium and lead contamination were not the sole factors determining tolerance differentiation.     

Fading out of the trophic cascade at the base of the microbial food web caused by changes in the grazing community in mesocosm experiments

Biomanipulation of consumer populations can have strong top-down impacts on the composition and biomass of lower trophic levels. In this paper, we assess how changes in crustaceans?? biomass influence classical grazing and the microbial food web in an oligo-mesohumic, low-pH lake (Mazurian Lake District, Poland). Removal of mesozooplankton from the experimental mesocosms created a gradient of crustacean biomass resulting in the biomass increase of rotifers, phytoplankton and protozooplankton, while autotrophic eukaryotic picoplankton (eu-APP) and bacteria were not affected. The strongest modifications concerned the rotifer biomass and phytoplankton community structure. Our results imply that the trophic cascade generated in the experiment did not extend to bacteria and eu-APP.     

Effects of heavy metals on riverine benthic macroinvertebrate assemblages with reference to potential food availability for drift-feeding fishes

We examined the influence of heavy metal pollution from an abandoned mine on benthic macroinvertebrates, at population and community levels, and the potential amount of food available for drift-feeding fish in northern Japanese streams. We studied multiple polluted and unpolluted sites with similar longitudinal positions to avoid problems caused by upstream-downstream comparisons. The ranges of zinc, copper, cadmium, and lead concentrations among the study sites were 5 to 812 microg/L, less than 0.12 to 5.2 microg/L, less than 0.0026 to 4.9 microg/L, and 0.1 to 18.6 microg/L, respectively. The abundance of several populations and community metrics showed a significant negative response to heavy metal pollution. Mayfly diversity and abundance was relatively sensitive to heavy metal pollution. In addition, the biomass of groups of macroinvertebrate taxa that are highly available for salmonids were significantly reduced at metal-polluted sites; this decrease in the most highly available group was noticeable (99% at the heavily polluted upper sites and 69% at the moderately polluted lower sites in spring). These results suggest that we should consider the indirect effect of pollution on food availability for the conservation of fish populations that depend on drifting macroinvertebrates.     

A comparative study of rural clinics in remote islands and inland areas

The social and professional isolation of physicians remains an important issue in rural areas. However, few studies have investigated the involvement of geographic factors in the isolation. This study investigates rural public clinics in inland and remote island locations and attempts to objectively compare the isolation of these physicians. A mailed questionnaire was sent to rural clinics where graduate physicians from Jichi Medical School were working in 1994 and 1995. Among the 198 clinics with one or more full-time physicians, 185 (93 percent) responded to the inquiry. Geographic and demographic factors of the communities were compared between 43 clinics located in remote islands and the other 142 rural inland clinics. Rural clinics in remote islands have smaller subject populations, fewer part-time physicians, a longer journey to the nearest city, and a longer distance and travel time to the base hospital than rural inland clinics. Physicians in remote island clinics had less medical training and are more isolated than other physicians. More than half of the clinic physicians in remote islands have no regular training schedule, in contrast to less than a quarter of the inland clinic physicians. Almost all clinics (97.7%) in remote islands do not have a part-time physician, whereas about 20 percent of the rural inland clinics do. Physicians in remote island clinics are more socially and professionally isolated than those in inland clinics. Strategies to reduce these problems should be given priority in rural health policy and measures tailored to rural clinics in remote islands.     

Susceptibility of a Carabid Beetle, <Emphasis Type="Italic">Pterostichus oblongopunctatus</Emphasis> Fab., from a Gradient of Heavy Metal Pollution to Additional Stressors

Insects inhabiting contaminated areas show increased susceptibility to other stressors, the purpose of this study was to investigate whether this phenomenon had a genetic basis. We investigated changes in susceptibility to food deprivation and insecticide (dimethoate) treatment of the ground beetle Pterostichus oblongopunctatus originating from four populations situated along a metal pollution gradient. To determine whether the increased susceptibility to additional stressors found in field-exposed animals from chronically metal-polluted sites had a genetic basis, our research was conducted on the second generation of laboratory-reared animals. There was no difference in susceptibility to the additional stressors indicating that the differences between populations observed in earlier studies do not have a genetic basis.     

Population dynamics of Anopheles nuneztovari in Colombia

Anopheles nuneztovari is an important Colombian malaria vector widespread on both sides of the Andean Mountains, presenting morphological, behavioral and genetic heterogeneity throughout the country. The aim of this study was to evaluate whether the population structure and distribution of An. nuneztovari in Colombia are associated with ecological and physical barriers present in a heterogeneous landscape. Further, differences in behavior were addressed. A total of 5392 specimens of An. nuneztovari were collected. Mitochondrial and nuclear marker analyses detected subdivision among the northwest-west, northeast and east populations. For both markers, isolation by distance (~ 53%) and isolation by resistance (> 30%) were determinants of population genetic differentiation. This suggests that physical barriers, geographical distance and ecological differences on both sides of the Andean Mountains promoted the genetic differentiation and population subdivision of An. nuneztovari in Colombia. This species showed the highest biting activity after 20:00 h; indoor and outdoor preferences were found in all localities. These results indicated that the most effective interventions for controlling vector populations on both sides of the Andes need to be region-specific.     

不同种类食品中镉含量水平及污染评价

目的：通过简单随机抽样，探讨了L市区各菜市场和大型超市不同种类食品中Cd的污染程度。方法：采用重金属单因子污染指数法对其不同种类食品中Cd的污染程度进行评价。结果：不同种类的食品中，Cd的单项污染指数值大小顺序为：食用菌类（1．35）〉薯类（0．97）〉蛋类（0．86）〉茄果类蔬菜（0．82）〉鱼类（0．81）〉禽畜肝脏（0．78）〉块茎类蔬菜（0．77）〉瓜菜类蔬菜（0．76）〉禽畜肉类（0．73）〉禽畜肾脏（0．63）〉叶菜类蔬菜（0．55）〉大豆（0．43）〉大米（0．42）〉水果类（0．22），可知食用菌类已经受到Cd的污染。结论：部分食品受到Cd的污染。     

Distribution of Cd and Zn Levels in Soils and Acacia xanthophloea Benth. from Lake Nakuru National Park Kenya

Cadmium and zinc from anthropogenic sources in Lake Nakuru were investigated. High metal levels (mg/kg) in soils (Cd ≤ 16.3 and Zn ≤ 280) and Acacia xanthophloea (Cd ≤ 32 and Zn ≤ 310) were observed at polluted sites. Significant variations in metal values were evaluated using ANOVA (F test) and student’s t test at p < 0.05 and metal correlations studied. High levels of metals in soils and unhealthy/dying Acacia were obtained at polluted sites. Significant positive correlation was obtained between Cd and Zn in soils and plants. Acacia sp are effective biomonitor of environmental quality in areas subjected to pollution.     

Genotoxicity in wood mice (Apodemus sylvaticus) along a pollution gradient: exposure-, age-, and gender-related effects

We investigated the effects of environmental pollution on genetic damage in wood mice (Apodemus sylvaticus) by means of the comet assay, with special attention to the role of age and gender as potential confounding variables. The present study was carried out at four sites along a pollution gradient in the vicinity of Antwerp (Belgium), with a nonferrous smelter as the main pollution source. We measured the concentration of heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Pb, and Zn) in mouse liver and kidney and the concentration of organochlorine compounds (polychlorinated biphenyls and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene) in mouse muscle tissue to assess individual exposure. Cadmium exposure was very high at the sites closest to the smelter, and exposure to this metal decreased with increasing distance from the smelter. Exposure to the other pollutants was low to moderate at the different sites. Genetic damage was higher in mice from populations in the vicinity of the nonferrous smelter compared with that in the control populations. A significant increase in genetic damage with age was observed at the most polluted sites, but not at the control sites. Genetic damage was higher in male mice than in female mice at the most polluted site, but not at the other areas. Yet, no obvious relationship was found between individual pollutant levels and individual genetic damage levels. We conclude that the comet assay can be used to compare genotoxicity at the population level if the confounding variables of gender and age are taken into account. However, its use for individual health risk assessment remains questionable.     

Human impact on genetic diversity of Toxoplasma gondii: Example of the anthropized environment from French Guiana

In French Guiana, severe cases of toxoplasmosis in immunocompetent patients are associated with atypical strains of Toxoplasma gondii linked to a wild neotropical rainforest cycle and a higher genetic diversity than usually observed for T. gondii isolates from anthropized environment. This raises the question of the impact of anthropization of the natural environment, on genetic diversity and on the population structure of T. gondii. However, few data are available on strains circulating in the anthropized areas from French Guiana. Seropositive animals originating mainly from anthropized sub-urban areas and punctually from wild environment in French Guiana were analyzed for T. gondii isolation and genotyping. Thirty-three strains were obtained by bioassay in mice and compared with 18 previously reported isolates chiefly originating from the Amazon rainforest. The genotyping analysis performed with 15 microsatellite markers located on 12 different chromosomes revealed a lower genetic diversity in the anthropized environment. Results were analyzed in terms of population structure by clustering methods, Neighbor-joining trees reconstruction based on genetic distances, F_ST, Mantel's tests and linkage disequilibrium. They clearly showed a genetic differentiation between strains associated to the anthropized environment and those associated to the wild, but with some inbreeding between them. The majority of strains from the anthropized environment were clustered into additional lineages of T. gondii that are common in the Caribbean. In conclusion the two environmental populations “wild” and “anthropized” were genetically well differentiated. The anthropization of the environment seems to be accompanied with a decreased diversity of T. gondii associated with a greater structure of the populations. We detected potential interpenetration and genetic exchanges between these two environmental populations. As a higher pathogenicity in human of “wild” genotypes has been described, the interpenetration of both environments leads to hybridization between strains that may be at risk for human health.     

Evidence of hepatotoxicity in the sand lizard Acanthodactylus scutellatus from Kuwait's Greater Al-Burgan oil field

The purpose of this study was to investigate the impact of oil pollution in a desert location (the Greater Al-Burgan oil fields, an area damaged in the Gulf War in 1991) in Kuwait on the hepatotoxicity of the Sand lizard Acanthodactylus scutellatus (A. scutellatus). Twenty lizards (10 of each sex) from each polluted and each control sites were collected. Livers were removed from dissected animals and ready for fixation by Bouin's solution and formal-saline. Twenty sections (10 from males and 10 from females) from each tar mat (polluted) and control sites were prepared and examined for cell diameter and nuclear measurements using Cell Analysis Systems. The cytology of hepatocytes showed normal appearance in samples from the control sites. Dead cells were abundant in the sections of lizard livers from the tar mat sites and occurred in notably greater numbers than the sections of livers of animals from the control sites. Examinations of the data confirm that the cell and nuclear diameters in liver samples of males collected from polluted sites were generally greater than those of corresponding females. The liver sections obtained from animals in the tar mat site had greater cellular diameters than counterparts from control sites. Females from the polluted sites were also affected by oil pollution by having larger hepatocyte diameters and their nuclei were also affected, being larger than female nuclei from the control sites. The most remarkable feature observed in hepatocytes of lizards collected from the tar mat sites were swelling of hepatocytes, ballooning degeneration of hepatic cytoplasm and cell death. This study confirmed that the prolonged exposure to oil pollution may result in increased accumulation of contaminants and may cause severe liver pathology in a range of wild organisms such as A. scutellatus.     

Alternative Measures of Spatial Distribution and Availability of Health Facilities for the Delivery of Emergency Obstetric Services in Island Communities

International guidelines and recommendations for availability and spatial distribution of emergency obstetric care services do not adequately address the challenges of providing emergency health services in island communities. The isolation and small population sizes that are typical of islands and remote populations limit the applicability of international guidelines in such communities. Universal access to emergency obstetric care services, when pregnant women encounter complications, is one of the three key strategies for reducing maternal and newborn mortality; the other two being family planning and skilled care during labor. The performance of selected lifesaving clinical interventions (signal functions) over a 3-month period is commonly used to assess and assign performance categories to health facilities but island communities might not have a large enough population to generate demand for all the signal functions over a 3-month period. Similarly, availability and spatial distribution recommendations are typically based on the size of catchment populations, but the populations of island communities tend to be sparsely distributed. With illustrations from six South Pacific Island states, we argue that the recommendation for availability of health facilities, that there should be at least five emergency obstetric care facilities (including at least one comprehensive facility) for every 500,000 population, and the recommendation for equitable distribution of health facilities, that all subnational areas meet the availability recommendation, can be substituted with a focus on access to blood transfusion and obstetric surgical care within 2 hours for all pregnant residents of islands. Island communities could replace the performance of signal functions over a 3-month period with a demonstrated capacity to perform signal functions if the need arises.     

First epidemiological data on pathogenic leptospires isolated on the Azorean islands

Insectivores (Erinaceus europaeus) and rodents (Rattus rattus, R. norvegicus and Mus musculus) from different islands of the Azores Archipelago were found to carry three distinct Leptospira interrogans (s.l.) serovars (copenhageni, icterohaemorrhagiae and ballum) which have never been previously investigated there. The house mouse and the black rat were the major Leptospira reservoirs showing isolation rates ranging from 0% for both species (in Graciosa) to 88% and 33%, respectively (in São Miguel). This study also showed that the majority of the animals with positive kidney cultures exhibited specific agglutinins against the isolated strains of Leptospira. The observed isolation rates in the different islands, with a very interesting island variation in prevalence, suggest that small mammals, serving as sylvatic reservoirs of pathogenic leptospires, may represent an important risk to the health of humans and livestock, particularly in the islands of Terceira and São Miguel.     

Metal Kinetics and Respiration Rates in F1 Generation of Carabid Beetles (Pterostichus oblongopunctatus F.) Originating From Metal-Contaminated and Reference Areas

We investigated resistance to metals in carabid beetles inhabiting metal-polluted and reference areas. Chronic multigeneration exposure to toxic metal concentrations may potentially result in adaptation through decreased metal uptake rate and/or increased excretion rate. The cost of resistance to pollution could be associated with increased metabolic rate. To test these predictions, laboratory cultured F₁-generation beetles originating from metal-polluted and reference sites were exposed to food contaminated with zinc and/or cadmium for 10 weeks. After that, uncontaminated food was offered to the animals for another 3 weeks. During the experiment, internal concentrations of Cd and Zn were measured as were respiration rates of the animals. The results obtained show no significant differences in metal accumulation and excretion patterns or respiration rates between the populations. This may suggest that adaptation has not occurred in the beetles chronically exposed to toxic metal concentrations. The possible explanations for the lack of differences between the populations are discussed.     

鲁西南地面水化学指标与微量元素含量研究

目的：探讨鲁西南地区地面水水质化学指标和微量元素含量，为防治污染和水资源开发利用提供科学依据。方法：采集微山湖、东平湖和尼山水库水样，按GB5750—85《生活饮用水标准检验法》和GB／T8538—1995《饮用天然矿泉水检验方法》进行水质分析。金属元素测定用石墨炉原子吸收光谱法。结果：鲁西南地区地面水中氯化物、硫酸盐、总硬度、溶解性总固体含量较高，水质盐化问题突出。尼山水库水质明显优于东平湖和微山湖；离城市近的地面水体污染重，化合物和微量元素含量多，部分指标含量明显高于地下水。结论：鲁西南地区地面水中化学指标和微量元素含量升高可能与地质环境和人为环境污染有关。     

Metal-induced shifts in benthic macroinvertebrate community composition in Andean high altitude streams

High altitude creates unique challenging conditions to biota that limit the diversity of benthic communities. Because environmental pollution may add further stress to life at high altitude, the present study explored the effect of metal pollution on the macroinvertebrate community composition in Andean streams between 3,500 to 4,500 meters above sea level (masl) during wet and dry seasons. At polluted sites, showing a high conductivity and a low pH, metal concentrations (e.g., Al, 13.07 mg/L; As, 3.49 mg/L; Mn, 19.65 mg/L; Pb, 0.876 mg/L; Zn, 16.08 mg/L) ranged from 8-fold up to 3,500-fold higher than at reference sites. The cumulative criterion unit allowed quantifying the potential toxicity of metal mixtures at the contaminated sites. Principal component analysis of physical chemical variables showed that reference sites were more likely to be structured by transparency, water discharge, and current velocity, while polluted sites appeared to be determined by metals and conductivity. Canonical correspondence analysis indicated a strong influence of highly correlated metals in structuring invertebrate communities, which were dominated by dipterans, coleopterans, collembolans, and mites at polluted sites. At reference sites crustaceans, ephemeropterans, plecopterans, and trichopterans were the most representative taxa. We concluded that severe metal pollution induced changes in macroinvertebrate community composition in high-altitude Andean streams, with a replacement of sensitive taxa by more tolerant taxa. Yet relatively species-rich communities persisted under harsh conditions.     

High genetic diversity of Giardia duodenalis assemblage E in Chinese dairy cattle

Giardia duodenalis is a common protozoan parasite that can infect humans and animals. Although previous studies demonstrated that the assemblage E of G. duodenalis is prevalent in cattle, studies on its genetic diversity were mostly based on single loci and very few involved multilocus analysis. To better understand the genetic variability and structure of G. duodenalis assemblage E in Chinese dairy cattle, 651 multilocus sequences derived from nine provinces (Gansu, Guangdong, Henan, Jiangsu, Ningxia, Shaanxi, Shanghai, Sichuan and Xinjiang) of China were analyzed in this study. Results showed that a total of 220 haplotypes were identified in the G. duodenalis assemblage E, with a high haplotype diversity (Hd = 0.97225) and low nucleotide diversity (π = 0.00259). The genetic differentiation index (FST) and gene flow (Nm) results indicated low degree of genetic differentiation, implying frequent genetic communication. Combined with the analysis of molecular variance (AMOVA), genetic variation within populations (81.7%) was higher than that among populations (18.3%), indicating low degree of genetic differentiation between populations. Such low rates of gene differentiation supported no significant correlations with geographical divisions. Moreover, both negative Tajima's D and Fu's FS values of neutrality tests and unimodal curve of mismatch distribution analyses indicated that G. duodenalis assemblage E population in Chinese dairy cattle had experienced demographic expansion. Overall, these findings contribute to an improved understanding of the population genetics and evolutionary biology of G. duodenalis assemblage E and assist in its control in cattle.