Variability in Contamination by Heavy Metals: Sampling Implications

The choice of a sampling design forassessing soil contamination is a key issue. The leveland spatial pattern of contaminants needs to be takeninto account by those buying, selling or developingsuch land. This paper evaluates sampling design andsize in order to provide satisfactory and efficientestimates of contamination levels. Geostatisticalmethods are used to quantify the spatial dependence ofheavy metals. Semivariance is calculated forlog-transformed data to minimise the effects ofextreme outliers. Several models at different samplingstages are presented for characterising spatialpattern of heavy metals at the investigated site.Variogram models are calculated for a range of samplesizes. The results are assessed by a jack-knifingtechnique and then used for block kriging. The overallconclusion is that a sample size of 50 to 60 isoptimal for characterising variability incontamination levels at an old industrial site of 6.25 ha.     

Diagnostics of the peach root-knot nematode,Meloidogyne floridensis using multiplex real-time PCR

European Journal of Plant Pathology - The peach root-knot nematode, Meloidogyne floridensis is an emerging pest of peach and other crops that is currently known to occur only in California,...     

Deliberate and unintentional introduction of invasive weeds: A case study of the alien flora of Ukraine

Summary Based on the analysis of invasions of alien plants in Ukraine, the impact of non-native plant species upon the native flora and adverse consequences of their spread are assessed. A case study gives examples of the role of alien plants in fragmentation of populations of native species; contamination of genetic resources of rare and endangered native species, formation of new ecotypes and hybridization with native taxa, disruption of the structure of natural plant communities as a result of introduction of alien species and formation of specific plant communities with domination of aliens. Arguments are provided against uncontrolled casual introductions and subsequent escape from cultivation as a result of ill-judged deliberate introduction of plants for ornamental, agricultural, technical, forestry, and other uses without any preliminary assessment of their invasion potential in the region concerned. Invasions of alien plants promote dramatic changes in the taxonomic, geographical, and ecological patterns of local floras, disruptions in the phytosociological spectrum, spectra of biomorphs, deterioration of zonal peculiarities of the flora, and finally lead to the decline of the vegetation productivity. A list of highly invasive plant species threatening forest, steppe, and submediterranean zones of East Europe is provided.     

Molecular Diagnostics, Taxonomy, and Phylogeny of the Stem Nematode Ditylenchus dipsaci Species Complex Based on the Sequences of the Internal Transcribed Spacer-rDNA

ABSTRACT The stem nematode Ditylenchus dipsaci is of great economic importance worldwide as a parasite of agricultural crops and horticultural plants. The internal transcribed spacer (ITS) of rDNA from 23 populations of the D. dipsaci complex from various host plants were amplified and sequenced. Seven previously studied populations were also included in the study. The phylogenetic analysis of the full ITS and ITS2 sequence alignments using minimum evolution, maximum parsimony, and Bayesian inference under the complex model of DNA evolution revealed trees with two main clades: (i) D. dipsaci sensu stricto with diploid chromosome numbers and comprising most isolates from agricultural, ornamental, and several wild plants, and (ii) Ditylenchus spp. with polyploid chromosome numbers, reproductively isolated from diploid populations, and subdivided into six subclades ("giant race" from Vicia faba, Ditylenchus species parasitizing various Asteraceae, and a Ditylenchus sp. from Plantago maritima). Using the energy minimization approach and comparative sequence analysis, it has been found that the secondary structure of ditylenchid ITS2 is organized in three main domains. The importance of knowledge on the RNA structure for phylogenetic analysis is discussed. Conventional polymerase chain reaction (PCR) and real-time PCR with SYBR green dye I with a species specific primer have been developed for detection and quantification of D. dipsaci sensu stricto Validation tests revealed a rather high correlation between real numbers of fourth-stage juveniles of the stem nematodes in a sample and expected numbers detected by real-time PCR. Problems of accuracy of quantification are discussed.     

Bioremediation of Hexachlorocyclohexane-Contaminated Soil by the New <Emphasis Type="Italic">Rhodococcus wratislaviensis</Emphasis> Strain Ch628

Currently, there are large areas of soils contaminated with hexachlorocyclohexane (HCH) isomers which are included in the group of persistent organic pollutants. For the bioremediation of such soils, a new HCH-degrading Rhodococcus wratislaviensis strain Ch628 was isolated from long-term organochlorine contaminated soils. The strain Ch628 was able to degrade 32.3% γ-hexachlorocyclohexane (γ-HCH/lindane), 25.2% hexachlorobenzene, and 100% chlorobenzene in resting cell conditions. The strain Ch628 was bioaugmented in chronically HCH-contaminated soil. The results showed that the bioaugmentation of contaminated soil with the strain Ch628 led to HCH degradation. In the bioaugmented system, the efficiency of HCH removal at the initial concentration of about 238.7 ± 4.9 mg kg^?1 soil was 44.8%, while the system with indigenous microflora (without R. wratislaviensis strain Ch628) and the system with abiotic control removed 33.3 and 16.4% of this compound during the same period, respectively. Strain Ch628 could effectively degrade α-, β-, and γ-isomers of HCH (77.1, 100, and 100%, respectively) and heptachlorocyclohexane (69.9%) in the model soil systems. Moreover, the bioaugmentation with the strain Ch628 led to degradation of tri-, tetra-, and penta-chlorobenzenes, which are of HCH degradation metabolites. For the first time, it was found that the bioaugmentation with the bacterial strain Rhodococcus wratislaviensis Сh628 led to a significant reduction of the toxicity of the HCH-contaminated soil for the test organisms, such as Chlorella vulgaris Beijer and Daphnia magna Straus.     

Molecular characterisation and diagnostics of some Longidorus species (Nematoda: Longidoridae) from Russia and other countries using rRNA genes

The needle nematodes of the genus Longidorus can cause diseases of various crops and trees, and are comprised of more than 150 valid species. Eleven valid and six unidentified species of the genus Longidorus collected in different regions of Russia, two states of USA, Germany, New Zealand and Ukraine were molecularly characterized using analysis of the partial 18S rRNA and the D2–D3 expansion segments of the 28S rRNA gene sequences. Fifty-four partial 28S rRNA and fifteen partial 18S rRNA gene sequences were obtained for the present study. Using molecular criteria, we confirmed the morphological identification and distinguished between the following species: L. aetnaeus, L. africanus, L. andalusicus, L. artemisiae, L. caespiticola, L. distinctus, L. elongatus, L. euonymus, L. intermedius, L. leptocephalus and L. lignosus. Two longidorid populations from Russia and four from California were not identified to a species level. We obtained the full length D2–D3 of 28S rRNA gene sequence from several freshly-collected L. artemisiae samples. We confirmed the identity of the D2 region of 28S rRNA gene sequence with a short D2 of 28S rRNA gene fragment sequence previously obtained from formalin-fixed nematodes embedded in the L. artemisiae paratype slides. Longidorus lignosus was molecularly characterized and L. aetnaeus was reported from Russia for the first time. PCR-D2-D3-RFLP diagnostic profiles generated by five restriction enzymes: AluI, HinfI, Bsp143I, Tru1I and RsaI are presented for sixteen Longidorus species.     

Identification of the Beet Cyst Nematode Heterodera schachtii by PCR

PCR-RFLPs of ITS-rDNA and PCR with species-specific primers were developed for identification of cysts and juveniles of the beet cyst nematode Heterodera schachtii. Restrictions of PCR product by MvaI or ScrFI distinguish H. schachtii, H. betae, H. trifolii and H. medicaginis. RFLP profiles with eight restriction enzymes for these four nematode species are presented. Based on Internal Transcribed Spacer sequences of populations from several Schachtii group species, a specific primer for H. schachtii was designed, permitting amplification of the target sequence from juveniles and cysts of the beet cyst nematode. A duplex PCR protocol tested with a wide range of nematode samples is described.     

Characterization of Longidorus helveticus (Nematoda: Longidoridae) from the Czech Republic

Longidorus helveticus was found at two out of 285 sampling sites for the first time in the Czech Republic. Females, males and juvenile stages were analyzed morphologically and morphometrically. The morphological identification of samples was verified by polymerase chain reaction using a species specific primer. Four markers of ribosomal DNA (18S, ITS1, ITS2, D2-D3 expansion segments of 28S rRNA) and two markers of mitochondrial DNA (cox1 and nad4) were sequenced and analyzed and compared with published gene sequences of other populations of L. helveticus. The partial mitochondrial cytochrome c-oxidase subunit 1 gene and partial nicotinamide dehydrogenase subunits 4 gene showed relatively high genetic variation within the species compared with ribosomal DNA markers.