Inhibition of telomerase in canine cancer cells following telomestatin treatment

Telomere shortening in normal somatic cells has been proposed as a major barrier to unlimited cellular proliferation. Telomerase is an enzyme capable of maintaining telomere length, and thus bypassing this barrier. In human beings, telomerase activity is restricted to cancer cells and cells of stem or germ cell lineages. Dogs represent a potentially useful clinical model for the development of telomerase‐based therapies because telomerase activity is also restricted to cancer cells and stem cells in this species. We examined the ability of telomestatin to inhibit telomerase activity in telomerase‐positive D17 and CMT7 canine cancer cell lines. At a concentration of 2 μM, telomestatin treatment resulted in a decrease in telomerase activity, telomere shortening, growth inhibition and apoptosis in telomerase‐positive cancer cells. These effects were not seen in telomerase‐negative skin fibroblasts or negative controls. These results confirm that telomestatin specifically inhibits telomerase activity in canine cancer cells and strengthens the usefulness of dogs as a model for testing telomerase‐based therapies.     

Development of comparable agro‐climatic zones for the international exchange of data on the efficacy and crop safety of plant protection products1

Data on the efficacy and crop safety of plant protection products can be used for registration purposes in other countries, provided crop growth conditions are comparable. This article identifies the main conditions which are relevant in this respect, with particular emphasis on climatic conditions. Comparison of several systems of agro‐climatic classification developed for the EPPO region, particularly the climate diagrams of Walter & Lieth, the climate classification system of Köppen & Geiger, the agro‐climatic areas of Thran & Broekhuizen and natural vegetation maps, has led to a division of the EPPO region (Europe, Mediterranean area, Middle East) into four agro‐climatic zones (Mediterranean, Maritime, North‐east, Central) within which conditions can be considered comparable.     

Morphological characterization of the IVIA persimmon (Diospyros kaki Thunb.) germplasm collection by multivariate analysis

Diospyros kaki Thunb. originated in Eastern Asia, as evidenced of its culture in China as early as several centuries B.C. In the seventh century, persimmon was introduced to Japan and later, in the fourteenth century to Korea. There is no information about persimmon culture in Europe until the seventeenth century, with the spread over the world occurring in the eighteenth century. The genus Diospyros contains more than 400 species, with levels of ploidy ranging from diploid (2n = 2x = 30) up to nonaploid (2n = 9x = 135). The primary economic crop species is Diospyros kaki Thunb., which is mainly hexaploid (2n = 6x = 90) and includes hundreds of cultivars. Although a relatively recent introduction in Europe, the species has adapted well, and the genetic diversity have been expanded with culture and selection for the past 200 years in the Mediterranean basin. These locally adapted cultivars were evaluated with cultivars from Asian origin in a germplasm collection established at IVIA in Valencia, Spain. In this paper 27 cultivars from the IVIA collection were studied by multivariate analysis, and 37 variables were analyzed using a Principal Components Analysis and cluster analysis following the method UPGMA. Studies on correlations and significance among variables identified the most relevant ones, and thus provided information for a future core collection.     

The molecular basis of the sparse fur mouse mutation

The ornithine transcarbamylase-deficient sparse fur mouse is an excellent model to study the most common human urea cycle disorder. The mutation has been well characterized by both biochemical and enzymological methods, but its exact nature has not been revealed. A single base substitution in the complementary DNA for ornithine transcarbamylase from the sparse fur mouse has been identified by means of a combination of two recently described techniques for rapid mutational analysis. This strategy is simpler than conventional complementary DNA library construction, screening, and sequencing, which has often been used to find a new mutation. The ornithine transcarbamylase gene in the sparse fur mouse contains a C to A transversion that alters a histidine residue to an asparagine residue at amino acid 117.     

Participation of specific PKC isozymes in the inhibitory effect of ET-1 on progesterone accumulation in cells isolated from early- and mid-phase corpora lutea

Expression of PKC alpha, beta I, beta II, epsilon and micro has been demonstrated in the whole bovine CL with PKC epsilon being differentially expressed as a function of development. In experiment 1 we have investigated the amount of mRNA encoding PKC epsilon at different stages of luteal development (days 1, 4, 10 and 17). In experiment 2, the cellular source of luteal PKC isozymes was determined. Enriched steroidogenic (SC) and endothelial (EC) cells from day-10 CL were used to examine this question by Western blot analysis and immuno-histochemistry. In experiment 3, Western blot analysis was used to examine the ability of ET-1 to activate luteal PKC isozymes in day-10 CL. In experiment 4, the role of luteal PKC isozymes in the ET-1 mediated inhibition of P(4) accumulation in steroidogenic cell cultures from day-4 and day-10 CL was examined. Abundance of PKC epsilon mRNA gradually increased from day-1 to -10 with no further increase on day-17. In experiment 2, PKC epsilon was exclusively detected in SC (LLC and SLC). In contrast, PKC alpha, beta I and beta II were detected in both SC and EC, with EC expressing higher amounts of PKC isozymes. In day-10 CL, ET-1 induced cellular redistribution of PKC alpha, beta I, epsilon but not beta II. Inhibitors specific for conventional PKC isozymes as well as PKC epsilon were able to negate the inhibitory effects of ET-1 on P4 accumulation in the day 10 CL. In the day-4 CL, the inhibitory effect of ET-1 might be mediated via conventional PKC. Thus, an exclusive presence of PKC epsilon in luteal steroidogenic cells, its higher expression along with the ability of ET-1 to stimulate its activation in day-10 CL strongly suggests that this PKC isoform may play an important regulatory role in decreasing P(4) during luteal regression. Inhibition of P(4) by ET-1 in the early CL may be mediated via conventional PKC isozymes.