Common genetic pools between human populations

Summary A further inquiry on modern human origins, based on common genetic pool surveys of rigorously selected population samples and highly informative immunological polymorphisms, provides new evidence of an Occidental-Oriental population split as the origin of human gene pool divergencies. The most likely ancestral genetic profile is discussed in the context of the debate raised by preliminary DNA restriction fragment length polymorphism studies, which contradict the conclusions drawn from classical blood group analyses.     

Biological monitoring of environmental pollution and human exposure to some trace elements

The extent of environmental pollution and resulting human exposure to hazardous toxic chemicals in the environment is often difficult to assess. One of the possible alternative approaches to this problem is the use of the biological indicators to demonstrate environmental pollution. This approach appears to be particularly suitable for demonstrating exposure to potentially toxic trace elements. In addition to analyses of plant and animal specimens the element content of human hair as an indicator of exposures to arsenic, mercury, cadmium, lead, antimony, manganese, nickel and cobalt has been repeatedly confirmed as reliable, provided the analyses were carried out and evaluated on group diagnostic basis and were done in groups of individuals occupationally not exposed to these metals. Preferably groups of 10-year-old children are to be used when only environmental pollution is to be taken into account. Hair samples are incomparably easier to collect, transport and store than the alternative biological material such as blood and urine used commonly to demonstrate exposure to various toxic agents. Biological monitoring of environmental pollution cannot replace the standard procedures of measuring air, water and soil pollution; however, the technique appears to have the potential of being an effective tool search for the extent of environmental pollution and for delimitation of territorial boundaries of areas affected most by hazardous emissions containing potentially toxic trace elements.     

新型吡唑类化合物DL-1的硝化抑制效应初探

以国内外应用较为广泛的硝化抑制剂双氰胺（DCD）为参比对象,采用室内培养方法,对新型吡唑类化合物DL-1的硝化抑制效应进行初步探讨.结果表明,DL-1对土壤中铵的氧化过程具有显著的抑制效应,前3周的硝化抑制率可达70％以上,且硝化抑制能力在第14天至28天最强.与等量DCD相比,施用量为(NH₄)₂SO₄氮量1.0%的DL-1在14、21和28 d使土壤中的NO₃^--N含量分别下降 26.23%、33.27%和23.31%;与不加抑制剂的对照处理相比,土壤NO₃^--N含量则分别下降了71.12%、69.10%和55.14%.当DL-1用量为(NH₄)₂SO₄氮量的2。0%时,土壤的硝化作用受到了更强烈的抑制,到培养第90天试验结束,土壤中的NO₃^--N含量始终维持在较低水平.     

Activation analysis of human hair as a tool for environmental pollution monitoring

Recent development and uses of neutron activation techniques for human hair analyses are reviewed. The method of neutron activation analysis (NAA) appears to have the potential to be used as a tool for environmental pollution monitoring. Principally, two types of NAA procedure are in use nowadays for multielement analyses of human scalp hair. The more common of these is the method of instrumental neutron activation analysis (INAA), consisting of a single short-term (3-10 hours) exposure of hair to a beam of neutrons in a nuclear reactor, followed by two measurements of gamma-ray spectra at 2-3 days and 3-4 weeks after the end of irradiation. The following microelements can be commonly determined by this type of activation procedure: As, Au, Br, Cu, K, La, Na, Sb, Sm, Co, Cr, Cs, Fe, Hg, Rb, Sc, Se and Zn. The other of the two procedures involves the use of radiochemical separation techniques and is employed for quantitative determinations of elements that are not easily determined by INAA (Mo, Cd, Ni, etc.), or in cases where there is a need to achieve the lowest possible limits of analytical determination. The accuracy of NAA techniques is strongly dependent on the hair sampling and hair sample processing methods used. The analytical error of this method may vary within the range of 5-15%. Its applicability as a tool for monitoring the environmental pollution level is here demonstrated on an example of groups of individuals living in the areas differing by the degree of environmental pollution. The use of other biopsy materials, such as e.g. mammalian hair, for the purpose of environmental exposure monitoring is also considered in this review.     

Bio-indicators in the monitoring of environmental pollution

Summary Surveying the chemical pollution status of a given area is increasingly becoming the task of biological indicators, ie animal and plant organisms capable of providing us with the necessary data. For example, in the wake of certain contaminations, they may increase or decrease in number, vary population proportions in relation to given traits, become vectors of certain toxic molecules or heavy metals, or accumulate them in their bodies or in their «products». The advantage of bioindicators over chemical or physical detectors is their ability to supply extensive — both spatially and temporally —rather than limited and instantaneous data, thus making such information more representative. In many instances the bioindicator takes samples for us-a service that is undoubtedly valuable even though it must be linked to a sound knowledge of the organism's ethogram and biology so as to arrive at a scientifically legitimate interpretation of the data provided.     

Phenotypic, maximum genetic, and special environmental variability in prehistoric human populations

The phenotypic variance (V(P)) may be divided into the genetic variance (V(G)), the general environmental variance (V(Eg)), and the special environmental variance (V(Es)). The latter is estimated through repeatability calculation (b). This value is considered the upper limit of heritability and represents maximum genetic variance proportion (V(Gm) = V(G) + V(Eg)) in relation to V(P) (b = (V(G) + V(Eg))/V(P)). This process allows an improved determination of biological relationships among groups from estimators maximizing the genetic information of quantitative characters. Two hundred and thirty-seven individuals inhabiting the northern coast of Chile for 4,000 years were taken as a sample. Measurement was made of six metric characters at both sides of the cranium. Special environmental values (es) were obtained by regression. The difference between these values and the phenotypic values (p) consists in the genetic values plus the general environmental values (g + eg). A mean b value of 0.83 indicated that V(Es) represents 17% of V(P). The results showed: 1) high stability of the maximum genetic variance in time and space, 2) high correlation between the biological relationships model, the phenotypic model, and the maximum genetic model, and 3) random distribution of the nongenetic variation, as expected from the quantitative genetics theory. These results support the use of phenotypic data for the interpretation of the evolution history of prehistoric populations.     

On-line and in situ biosensors for monitoring environmental pollution

Efficient tools for on-line and in situ monitoring of environmental pollutants are required to provide early warning systems. In addition, such tools can contribute important information on the progress of various remediation treatments. One of the recently developed monitoring technologies involves the use of whole-cell biosensors. Such biosensors could be constructed to detect general toxicity or specific toxicity caused by one or more pollutants. Currently, a large spectrum of microbial biosensors have been developed that enable the monitoring of pollutants by measuring light, fluorescence, color or electric current. Electrochemical monitoring is of special interest for in situ measurements as it can be performed using simple, compact and mobile equipment and is easily adaptable for on-line measurements. Here we survey the potential application of electrochemical biosensors in monitoring of general toxicity as well as hydrocarbons and heavy metals.     

Environmental pollution affects genetic diversity in wild bird populations

Many common environmental pollutants, together with nuclear radiation, are recognized as genotoxic. There is, however, very little information on pollution-related genetic effects on free-living animal populations, especially in terrestrial ecosystems. We investigated whether genetic diversity in two small insectivorous passerines, the great tit (Parus major) and the pied flycatcher (Ficedula hypoleuca), was changed near point sources of heavy metals (two copper smelters) or radioactive isotopes (nuclear material reprocessing plant). We measured concentration of heavy metals and nucleotide diversity in mitochondrial DNA in feather samples taken from nestlings in multiple polluted areas and at control sites. In both species, heavy metal concentrations - especially of arsenic - were increased in feathers collected at smelter sites. The P. major population living near a smelter showed significantly higher nucleotide diversity than a control population in an unpolluted site, suggesting increased mutation rates in a polluted environment. On the contrary, F. hypoleuca showed reduced nucleotide diversity at both smelter sites but increased nucleotide diversity near the source of radioactivity. Our results show that heavy metal pollution and low level nuclear radiation affect the nucleotide diversity in two free-living insectivorous passerines. We suggest that the different response in these two species may be due to their different ability to handle toxic compounds in the body.     

Genetic ecological monitoring in human populations: heterozygosity, mtDNA haplotype variation, and genetic load

Yu. P. Altukhov suggested that heterozygosity is an indicator of the state of the gene pool. The idea and a linked concept of genetic ecological monitoring were applied to a new dataset on mtDNA variation in East European ethnic groups. Haplotype diversity (an analog of the average heterozygosity) was shown to gradually decrease northwards. Since a similar trend is known for population density, interlinked changes were assumed for a set of parameters, which were ordered to form a causative chain: latitude increases, land productivity decreases, population density decreases, effective population size decreases, isolation of subpopulations increases, genetic drift increases, and mtDNA haplotype diversity decreases. An increase in genetic drift increases the random inbreeding rate and, consequently, the genetic load. This was confirmed by a significant correlation observed between the incidence of autosomal recessive hereditary diseases and mtDNA haplotype diversity. Based on the findings, mtDNA was assumed to provide an informative genetic system for genetic ecological monitoring; e.g., analyzing the ecology-driven changes in the gene pool.     

A genetic affinity analysis of human populations

Genetic affinity of human populations based on allele frequency data was studied from two viewpoints. (1) The effect of the number of polymorphic loci on the reconstruction of a phylogenetic tree of human populations was empirically investigated. Genetic affinity trees were constructed based on data for 1–12 polymorphic loci, by using the neighbor-joining method. Geographical clustering of populations gradually appeared when the number of loci was increased. A new classification and terminology of higher order human population clusters is proposed based on these and other studies. (2) A new method of estimating the absolute divergence time of two populations is proposed, which is based on a diffusion equation that describes random genetic drift.     

Relationship between Hp1S and Hp2 gene frequencies among human populations

In this work, we present new data on the Hp1alpha- and Hp2alpha-chains polymorphism in different populations. We confirm the singularity of the geographical distribution of the Hp2 alleles in our samples. The analysis of the results shows that a significant correlation exists in the population between the Hp1S and Hp2 gene frequencies. An additional Hp1alpha-chain variant is described in a Pyrenean sample.     

Bayesian analysis of genetic differentiation between populations

We introduce a Bayesian method for estimating hidden population substructure using multilocus molecular markers and geographical information provided by the sampling design. The joint posterior distribution of the substructure and allele frequencies of the respective populations is available in an analytical form when the number of populations is small, whereas an approximation based on a Markov chain Monte Carlo simulation approach can be obtained for a moderate or large number of populations. Using the joint posterior distribution, posteriors can also be derived for any evolutionary population parameters, such as the traditional fixation indices. A major advantage compared to most earlier methods is that the number of populations is treated here as an unknown parameter. What is traditionally considered as two genetically distinct populations, either recently founded or connected by considerable gene flow, is here considered as one panmictic population with a certain probability based on marker data and prior information. Analyses of previously published data on the Moroccan argan tree (Argania spinosa) and of simulated data sets suggest that our method is capable of estimating a population substructure, while not artificially enforcing a substructure when it does not exist. The software (BAPS) used for the computations is freely available from http://www.rni.helsinki.fi/~mjs.     

Cytogenetic monitoring of farm animals under conditions of environmental pollution.

Cytogenetic examinations were carried out in 13 cattle farms, two herds of horses, one stag farm and 13 pig farms in areas with different levels of environmental contamination. The frequency of aberrant cells per 100 mitoses was 3.67 +/- 1.89 in pigs (n = 260) and 4.16 +/- 2.4 in herbivores (n = 497). This is a significant difference (p < 0.01). Ten times higher frequencies of chromatid exchanges were found in pigs. The examined herds were classified into three groups by the level of environmental contamination (satisfactory, impaired and severely impaired environment). Significant differences in aberrant cell counts were recorded between the groups of herbivorous animals. Significant differences in pigs were recorded only between herds in satisfactory and severely impaired environments. Significantly higher frequencies of aberrant cells were found in farms of herbivorous animals in the industrial area of Pardubice compared with findings in the South Moravian agricultural area (4.7% and 3.1% respectively). The effect of local contamination sources on farm environment was also investigated. A cattle farm located in the vicinity of a large chemical plant was examined five times at 6-month intervals. An autumn examination revealed significantly higher frequencies of aberrant cells compared with the spring examination.     

Genetically engineered microbial biosensors for in situ monitoring of environmental pollution

Microbial biosensors are compact, portable, cost effective, and simple to use, making them seem eminently suitable for the in situ monitoring of environmental pollution. One promising approach for such applications is the fusion of reporter genes with regulatory genes that are dose-dependently responsive to the target chemicals or physiological signals. Their biosensor capabilities, such as target range and sensitivity, could be improved by modification of regulatory genes. Recent uses of such genetically engineered microbial biosensors include the development of portable biosensor kits and high-throughput cell arrays on chips, optic fibers, or other platforms for on-site and on-line monitoring of environmental pollution. This mini-review discusses recent advances in microbial biosensors and their future prospects, with a focus on the development and application of genetically modified microbial biosensors for in situ environmental monitoring.