Comparative characteristics of the composition and degree of sulfation of glycosaminoglycans in resting and actively proliferating tissues

A comparative study of the composition and degree of sulfation of glycosaminoglycans (GAG) in proteoglycans isolated from normal animal tissues and from actively proliferating embryonic, tumour and regenerating tissues was carried out. Significant differences in the ratios of various types of sulfated GAG were revealed. The relative content of chondroitin sulfate AC in actively proliferating tissues was considerably increased. It was found that all types of sulfated GAG in actively proliferating tissues, with the exception of regenerating tissue, are characterized by a lower degree of sulfation as compared to GAG from resting tissues. The experimental results are discussed in terms of the role of proteoglycans in the organization of extracellular matrix and in control of cell proliferation.     

STIM1 and STIM2 Proteins Differently Regulate Endogenous Store-operated Channels in HEK293 Cells

The endoplasmic reticulum calcium sensors stromal interaction molecules 1 and 2 (STIM1 and STIM2) are key modulators of store-operated calcium entry. Both these sensors play a major role in physiological functions in normal tissue and in pathology, but available data on native STIM2-regulated plasma membrane channels are scarce. Only a few studies have recorded STIM2-induced CRAC (calcium release-activated calcium) currents. On the other hand, many cell types display store-operated currents different from CRAC. The STIM1 protein regulates not only CRAC but also transient receptor potential canonical (TRPC) channels, but it has remained unclear whether STIM2 is capable of regulating store-operated non-CRAC channels. Here we present for the first time experimental evidence for the existence of endogenous non-CRAC STIM2-regulated channels. As shown in single-channel patch clamp experiments on HEK293 cells, selective activation of native STIM2 proteins or STIM2 overexpression results in store-operated activation of I_min channels, whereas STIM1 activation blocks this process. Changes in the ratio between active STIM2 and STIM1 proteins can switch the regulation of I_min channels between store-operated and store-independent modes. We have previously characterized electrophysiological properties of different Ca²⁺ influx channels coexisting in HEK293 cells. The results of this study show that STIM1 and STIM2 differ in the ability to activate these store-operated channels; I_min channels are regulated by STIM2, TRPC3-containing I_NS channels are induced by STIM1, and TRPC1-composed I_max channels are activated by both STIM1 and STIM2. These new data about cross-talk between STIM1 and STIM2 and their different roles in store-operated channel activation are indicative of an additional level in the regulation of store-operated calcium entry pathways.     

Store-operated calcium entry into SK-N-SH human neuroblastoma cells modeling huntington’s disease

Huntington’s disease (HD) is an autosomal dominant neurodegenerative disorder caused by expansion of polyglutamine at the N-terminus of the huntingtin protein. Striatal medium spiny neurons (MSN) are the primary targets of HD pathology. In our study, a cellular model of HD was based on the human neuroblastoma cells SK-N-SH transfected with plasmid for expression of the mutant huntingtin protein Htt138Q. Expression of Htt138Q increased store-dependent calcium entry into SK-N-SH cells. EVP4593 reversibly blocked the abnormal store-dependent response, probably generated by the channels incorporating TRPC1 ( transient receptor potential canonical 1) subunit.     

Toxicogenetic effects of azo- and arylmethane dyes

The haploid strain 15B-II4 of Saccharomyces cerevisiae was used to study in an acute experiment the toxic and mutagenic effects of arylmethane dyes Victory Blue (C.I. 44040), Methyl Violet (C.I. 42535), Brilliant Green (C.I. 42040) and cancerogenic aminoazo dye Chrysoidine (C.I. 11270). High biological activity of all the dyes tested was found, based on such toxic effects as cell killing and growth inhibition. Also, it was shown that the dyes could increase the frequency of appearance of nuclear point mutations and cytoplasmic mutations of respiratory deficiency.     

Onion yield as affected by plant density,nitrogen level and loss of leaf area

Onion (Allium cepa) is an important horticulture crop because of its value as a food with a long shelf life being a relatively non-perishable product. It is very helpful to understand the growth response of the seeded onion crop to conduct appropriate field practices in attaining the highest or optimum yields. A three year field experiment was conducted using a variety of onion Valcatorce INTA, in a randomized block design with five replicates. Treatments were two plant densities and three rates of N application. The bulb growth followed a classical sigmoid curve. During the rapid growing period, the crop had the greatest leaf area (LA) with at least six leaves per plant. Increasing plant density increased yield in kg/ha, but decreased bulb size. Defoliating 40 to 60% of the LA had a significant impact on bulb production only at early growth stages. Late in the growing period, the remaining LA was apparently large enough for producing sufficient amounts of metabolites to feed new leaves, increasing their photosynthesis efficiency for the benefit of bulb production.     

Pregnancy success of lactating Holstein cows after a single administration of a sustained-release formulation of recombinant bovine somatotropin

Background

Results regarding the use of bovine somatotropin for enhancing fertility in dairy cattle are variable. Here, the hypothesis was tested that a single injection of a sustained-release preparation of bovine somatotropin (bST) during the preovulatory period would improve pregnancy success of lactating dairy cows at first service.

Results

The first experiment was conducted in a temperate region of Mexico. Cows inseminated following natural estrus or timed artificial insemination were given a single injection of bST or a placebo injection at insemination (n = 100 cows per group). There was no significant difference between bST and control groups in the proportion of inseminated cows diagnosed pregnant (29 vs 31% pregnant). The second experiment was performed during heat stress in Florida. Cows were subjected to an ovulation synchronization regimen for first insemination. Cows treated with bST received a single injection at 3 days before insemination. Controls received no additional treatment. As expected, bST did not increase vaginal temperature. Treatment with bST did not significantly increase the proportion of inseminated cows diagnosed pregnant although it was numerically greater for the bST group (24.2% vs 17.8%, 124–132 cows per group). There was a tendency (p = 0.10) for a smaller percent of control cows to have high plasma progesterone concentrations (≥ 1 ng/ml) at Day 7 after insemination than for bST-treated cows (72.6 vs 81.1%). When only cows that were successfully synchronized were considered, the magnitude of the absolute difference in the percentage of inseminated cows that were diagnosed pregnant between bST and control cows was reduced (24.8 vs 22.4% pregnant for bST and control).

Conclusion

Results failed to indicate a beneficial effect of bST treatment on fertility of lactating dairy cows.