Pollution of soil and vegetation in the Thriasian Plain,Greece

Summary The Thriasian Plain near Athens in Greece is a site of concentrated industrial development. Total concentrations of Pb, Cd and extractable SO₄ ^2– in surface soil samples collected from this area, were found to be, respectively, 2–7, 6–34 and 2–20 times higher than those in similar soil samples from parts of the country remote from industrial activity.Total concentrations of Pb, Cd, Zn, Cr and S in samples of olive leaves from the same area were found to be, respectively, 4–40, 3–10, 3–9, 2–6 and 17–21 times higher than those found in samples of olive leaves from rural sites. Leaves of cabbages growing in the area contained between 0.82 and 40 g/g (wet weight) of Pb.Addition of Cd, Ni and Cu to a calcareous potted soil at concentrations of 100, 200 and 200 ppm increased the concentrations of the metals in the needles of Aleppo pine (Pinus halepensis) seedlings to 4.5, 3.5 and 10 ppm, respectively, after 7 months growth in the nursey.     

Potential impact of viticulture expansion on habitat types in the Cape Floristic Region, South Africa

The wine industry in the Western Cape, South Africa has expanded over the past decade, particularly since the lifting of trade sanctions in 1992. Wine grapes are cultivated on fertile soils upon which threatened biodiversity habitat units of the Cape Floristic Region occur naturally. There is a concern as to whether further expansion of the wine industry, which would benefit the economy through increased foreign exchange, would encroach on the little remaining vegetation in vineyard-producing areas. Predictive land use modeling using logistic regression techniques was applied to determine suitable areas for vineyard cultivation according to climatic, topographic, and soil/geology variables. Of the most threatened habitats, 14849 hectares are particularly suitable for vineyards. Breede fynbos/renosterveld mosaic was the habitat most likely to be converted, and was considered 89.3% irreplaceable to current conservation goals. Also vulnerable are Ashton inland renosterveld and Boland coast renosterveld, the latter being 100% irreplaceable. Although the high rate in vine replanting suggests that the need for untransformed land will not be great immediately, an economic analysis showed that protection of these areas against future ploughing will be vital if targets of adequately representing each habitat in the Cape Floristic Region are to be met. Land use change modeling, especially if done in a spatially explicit and integrated manner with expert input, was shown to be an important technique for the extrapolation of historical patterns to understand the forces that shape landscapes, allowing for the assessment of management alternatives, and testing our understanding of key processes in land use changes that effect conservation planning.     

The beta-binomial model for host specificity among organisms in trophic interactions

In this paper, we present a new stochastic model where the host specificity among organisms in trophic interactions in a community, say parasite-host interactions, is estimated by a beta-binomial model. The expected proportion of the host species in a community that a given parasite species is utilizing is modeled as a realization from an inhomogeneous Poisson process, where the rate of this process is assumed to be proportional to a beta probability distribution. The observed number of host species utilized by the parasites is then binomially distributed with the number of trials equaling the number of different host species in the sample. When the degree of polyphagy is estimated by the parameters of the beta-binomial model, quantities like community host specificity and the expected total number of parasite species that will utilize the host species in the community can be predicted as functions of the number of host species available. The predictions can then be applied in analysis of, e.g., symbiotic interactions among organisms, local species richness, and community structure.     

The Robust Statistical Bases of the Coevolution Theory of Genetic Code Origin

A paper (Amirnovin R, J Mol Evol 44:473–476, 1997) seems to undermine the validity of the coevolution theory of genetic code origin by shedding doubt on the connection between the biosynthetic relationships between amino acids and the organization of the genetic code, at a time when the literature on the topic takes this for granted. However, as a few papers cite this paper as evidence against the coevolution theory, and to cast aside all doubt on the subject, we have decided to reanalyze the statistical bases on which this theory is founded. We come to the following conclusions: (1) the methods used in the above referred paper contain certain mistakes, and (2) the statistical foundations on which the coevolution theory is based are extremely robust. We have done this by critically appraising Amirnovin's paper and suggesting an alternative method based on the generation of random codes which, along with the method reported in the literature, allows us to evaluate the significance, in the genetic code, of different sets of amino acid pairs in biosynthetic relationships. In particular, by using this method and after building up a certain set of amino acid pairs reflecting the expectations of the coevolution theory, we show that the presence of this set in the genetic code would be obtained, purely by chance, with a probability of 6 × 10⁻⁵. This observation seems to provide particularly strong support to the coevolution theory. Received: 28 June 1999 / Accepted: 23 October 1999     

Relationships between the endangered Pustertaler-Sprinzen and three related European cattle breeds as analysed with 20 microsatellite loci

We estimated the genetic relationships between the endangered German Pustertaler-Sprinzen cattle breed and the Pinzgauer, Vosges and Simmental breeds--decided upon after consultation of the available historical literature. Within-breed diversity of the four breeds was also assessed. Twenty microsatellite markers were amplified in 27-50 unrelated individuals from populations of each breed. Within-breed variation was estimated from average heterozygosity values and mean number of alleles. Breed relationships were evaluated by genetic distance and a neighbour-joining tree was calculated from these estimates. Bootstrap resampling of loci tested the robustness of the tree topology obtained. A tree was also constructed from distance matrices using individual animals as operational taxonomic units. From both the average heterozygosity values and mean number of alleles calculated, the Pustertaler breed appears to be no more genetically impoverished than the other breeds analysed. The breed tree showed an 85% support for the Pustertaler-Pinzgauer grouping, and this result is echoed in the genetic distance values and allele-sharing individual tree.     

植被与侵蚀控制:坡面生态工程基本原理探索

在与近地面大气和与表层至浅层土壤的相互作用中,植被表现出相应的水文－机械效应,形成一定的抗蚀护坡工程性状,坡面生态工程把这些植被性状和土壤结合起来,用于斜坡的保护工程,在过去几十年中,随着对植被－土壤相互作用及其侵蚀控制意义认识的深化,使坡面生态工程应用得到迅速发展,成为生态环境建设和工程坡面保护的重要手段,这个生态学途径的一个重要内容是“土壤－植被系统”的概念,以及由此推导出的系统生物学和工程学     

Sterol 14 alpha-demethylase, an abundant and essential mixed-function oxidase

Sterol 14alpha-demethylase (CYP51) is the most widely distributed of all members of the cytochrome P450 gene superfamily and the only CYP family found in both prokaryotes and eukaryotes. It is well known as a drug target for microbial pathogenic infections. Studies of CYP51 gene regulation have been carried out primarily in animals because its regulation is similar to those of other genes involved in the cholesterol biosynthetic pathway. The function of CYP51 has been studied widely throughout biology including in animals, plants, yeast/fungi, protozoa, and bacteria. The structure has been determined by X-ray crystallography for the soluble prokaryotic form of CYP51 from Mycobacterium tuberculosis. Together these studies provide the most detailed understanding of any single cytochrome P450 and this minireview summarizes this information.     

Predicting decay and ground vegetation development in <Emphasis Type="Italic">Picea abies</Emphasis> snag stands

In a Picea abies (L.) Karst. (Norway spruce) mountain forest on the Gandberg site in the northern Swiss Alps, trees were killed by bark beetles in 1992–1997. A combination of field studies and dynamic modelling was used to project snag decay and future ground vegetation succession in these steep, unharvested stands. In permanent plots, ground vegetation cover and natural tree regeneration have been monitored annually since 1994. To obtain additional information on the abundance of snags, logs, boulders and other microsite types in these stands, the relative frequency of the microsite types was quantified along four strip transects on the montane and subalpine elevational levels. A dynamic model of snag decay and ground vegetation development was constructed (modified matrix model approach). Based on field data and literature values, the model was parameterised and initialised separately for the montane and the subalpine level. For model validation, microsite types were quantified in 2001 with the line-intercept method on both elevational levels. Starting from the conditions in the stands before the bark beetle attacks, it was possible to project short-term succession and to accurately simulate the decay and ground vegetation patterns eight years after tree die-back. Long-term simulations suggest that on the montane level, raspberries (Rubus idaeus L.) will be replaced by Picea abies, while on the subalpine level ferns will dominate for a long time.