Characterization ofSolanum tuberosum simple sequence repeats and application to potato culiwar identification

With the continued introduction of new potato cultivars, accurate identification is becoming difficult but is essential for maintaining cultivar integrity and Plant Breeders’ Rights. Hypervariable DNA sequences, referred to as simple sequence repeats (SSRs) or microsatellites, have been reported to be an excellent source of genetic markers. To determine the abundance, distribution, and composition of SSRs withinSolanium tuberosum, 252 sequences were searched for tetranucleotide and smaller SSRs with a minimum length of 20 nucleotides and a maximum discrepancy of two nucleotides. In total, 40 unique SSRs were observed in the 252S. tuberosum sequences examined and occurred at a frequency of one SSR every 8.1 kb. To assess the ability of site-specific amplified SSRs to identify potato cultivars, a simple (TCAC)_m and compound (TCAC)_m ? (CTT)_n SSR 5’ to the starch synthase gene and a compound (C)_p ? (CT)_q ? (AT)_r ? (G)_s SSR 5’ to the sequence encoding mature proteinase inhibitor I, were examined and shown to produce unique DNA profiles for 73 of 95 tetraploid cultivars. In total, 24 alleles were observed at these loci and the accurately sized amplified DNA products can be used to establish a database for cultivar identification. Site-specific amplified alleles were somatically stable and have been conserved in clonal variants of Russet Burbank independently maintained for almost seven decades, a characteristic essential for cultivar identification. As genetic markers, the abundant, informative, and easily examined site-specific amplified alleles of SSRs are ideal for quickly and accurately determining cultivar identity of S.tuberosum ssp.tuberosum.     

Rhabdochona longleyi sp. n. (Nematoda: Rhabdochonidae) from blind catfishes, Trogloglanis pattersoni and Satan eurystomus (Ictaluridae) from the subterranean waters of Texas

A new nematode species, Rhabdochona longleyi sp. n. is described from the intestine of two species of blind catfishes, Trogloglanis pattersoni Eigenmann (type host) and Satan eurystomus Hubbs et Bailey (both fam. Ictaluridae, Siluriformes) from the subterranean waters (artesian wells penetrating San Antonio pool of Edwards Aquifer) of Texas, USA. It is characterized largely by the presence of only six anterior teeth in the prostom, simple deirids, by the shape and length of spicules (0.42 to 0.50 mm and 0.093-0.102 mm), shape of the tail tip (rounded), and by filamented eggs. R. longleyi probably adapted to the environment of the aquifer by utilizing available troglobitic crustaceans instead of aquatic insects as an intermediate host.     

BSE in the Netherlands: an update

Up to 2006, there have been 82 cases of BSE in cattle born in the Netherlands. This article reviews the current situation regarding BSE in the Netherlands and summarizes the clinical symptoms of the disease. Data from the Netherlands show that a passive surveillance system, by which farmers and veterinarians have to report suspect clinical cases, has a low sensitivity. The epidemiology of, and risk factors for, BSE are discussed. All the Dutch cases of BSE can be attributed to cross-contamination of feed with meat-and-bone meal. On the basis of information about the epidemic and the cases reported to date, it is anticipated that the number of cases of BSE will continue to decline in the Netherlands and Europe. The European Commission has presented a road map that describes how the European BSE policy can be changed in the short and long term if the current favourable trend in BSE cases continues. It is time for a new phase in the management of BSE but with continued protection of the public's health and eradication of BSE.     

In UV‐B Irradiated Rice High Levels of Mn Limits Chloroplasts Injury Triggered by Oxidative Stress

The molecular mechanism to control the oxidative burst exerted by Mn accumulation in rice (Oryza sativa L.) plants, grown in hydroponics containing 0.5, 2 and 8 mg l^–1 Mn and irradiated with a total biological effective UV‐B irradiation of 20.825 kJ m^?2, was investigated in the chloroplasts at the 15th and 21st days after germination. In both experimental periods, Mn accumulation kinetics in the leaves and in the chloroplast lamellae displayed overall increases. Coupled to higher membrane selectivity, superoxide production and acyl lipids peroxidation in the thylakoids decreased, prompting upper rates of the Hill and Mehler reactions. Connected to UV‐B irradiation, higher accumulated Mn in thylakoids was found to be chelated in a 36.5 kDa protein, with Mn/protein ratio of about 1 and high content of Gln, Asp, Glu, Leu and Gly, being its EPR spectrum characteristic of high‐spin Mn(II), in a S = 5/2 ground state. As this protein exhibited enzymatic catalysis of superoxide dismutation, it was concluded that, under UV‐B irradiation, the high internal tolerance of Oryza sativa L. to Mn during the vegetative growth also triggers the synthesis of a manganese protein that mimics superoxide dismutase functioning, therefore furnishing an additional intimate protection against oxidative stress.     

The multiple land degradation effects caused by land-use intensification in tropical steeplands: A catchment study from northern Thailand

The strongly incised mountain landscape of northern Thailand has changed dramatically during the last few decades due to increased population pressure, agricultural commercialization, limitation to use old fallows and reforestation of upper catchments. The traditional shifting cultivation with fallow periods of 7 years and longer was gradually replaced by 1 to 4 year fallow periods. As a result, in high population areas the landscape became dominated by fields planted to rainfed upland crops, wetland rice terraces, fallow vegetation, and patches of secondary forest. This new land-use system seems to have triggered new land degradation processes that are easy to observe when travelling through this landscape.     

Soil successions and their connection with heterogeneity of podsolic soils

Modern ideas regarding soil successions and heterogeneity of podsolic soils in the conditions of various biogeocenoses are considered. Functional interdependence between the given natural phenomena is shown. Within the frameworks of macrosuccession, there are adduced examples of soil successions of various genesis and scale. The analysis of such soil successions allows estimating simultaneously the spatiotemporal components of heterogeneity of soils. Windfall soil complexes are a good illustration of soil succession shown at various levels of the organization of a soil body.