The structure of the littoral: effects of waterlily density and perch predation on sediment and plant‐associated macroinvertebrate communities

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Genome-scale patterns in the loss of heterozygosity incidence in Saccharomyces cerevisiae

Former studies have established that loss of heterozygosity can be a key driver of sequence evolution in unicellular eukaryotes and tissues of metazoans. However, little is known about whether the distribution of loss of heterozygosity events is largely random or forms discernible patterns across genomes. To initiate our experiments, we introduced selectable markers to both arms of all chromosomes of the budding yeast. Subsequent extensive assays, repeated over several genetic backgrounds and environments, provided a wealth of information on the genetic and environmental determinants of loss of heterozygosity. Three findings stand out. First, the number of loss of heterozygosity events per unit time was more than 25 times higher for growing than starving cells. Second, loss of heterozygosity was most frequent when regions of homology around a recombination site were identical, about a half-% sequence divergence was sufficient to reduce its incidence. Finally, the density of loss of heterozygosity events was highly dependent on the genome’s physical architecture. It was several-fold higher on short chromosomal arms than on long ones. Comparably large differences were seen within a single arm where regions close to a centromere were visibly less affected than regions close, though usually not strictly adjacent, to a telomere. We suggest that the observed uneven distribution of loss of heterozygosity events could have been caused not only by an uneven density of initial DNA damages. Location-depended differences in the mode of DNA repair, or its effect on fitness, were likely to operate as well.     

Seasonal changes of the photosynthetic capacity of the Antarctic macroalga Adenocystis utricularis (Bory) Skottsberg

Summary Photosynthetic oxygen evolution from Antarctic macroalgaAdenocystis utricularis, collected from littoral zone of Admiralty Bay of King George Island (South Shetland), was measured under standard laboratory conditions during a 9-month study period. During autumn and winter the photosynthetic apparatus of the alga revealed an increased capacity to use low irradiance. This coincided with increasing concentrations of chlorophyll a+c. In parallel respiration rates measured at the average monthly water temperature were lower in winter than in summer.     

Psychological view of thyroid cancer and in hyperthyroid Graves' patients - comparative exploration

INTRODUCTION: The aim of study was the evaluation of association between psychometric factors in patients with thyroid cancer and in Graves' hyperthyroid patients. MATERIAL AND METHODS: We examined 50 patients with differentiated thyroid cancer, 42 females (84.75%), 8 males aged from 32 to 64 yr. (x +/- SD: 43 +/- 8.17 yr.) and 50 hyperthyroid patients, 45 (90%) females and 5 (10%) males corresponding aged. We used the following methods: the EAS Temperament Survey (EASD) in addition for adults, EPQ Eysenck Personality Questionnaire, Polish Abbreviated Form of the MMPI (DKO-74) and Beck's Depression Scale. We compared the scores of thyroid cancer patients and hyperthyroid patients. RESULTS: We have interpreted obtained results in both groups as similarly in: mild sense depression, high emotional control, high social dependence, ambiverssion, mild level of emotional mental balance. CONCLUSION: Results of our explorations appears great psychological similarity between differentiated thyroid patients and hyperthyroid patients.     

Exogenous abscisic acid increases stability of polysomes in embryos of triticale caryopses during germination

Some posttranslational processes that occur in embryos of germinating triticale caryopses treated with different concentrations of abscisic acid (ABA) were examined. ABA increased the ratio of cytoskeleton-bound polysomes in the total population of polysomes and depressed the share of free and membrane-bound polysomes. Using exogenous RNase, stability of the total polysomal population as well as each polysomal fraction was investigated. The total extractable polysomes isolated from embryonic tissues of germinating triticale caryopses treated with ABA were more stable than the polysomes isolated from the control sample caryopses. The contribution of the polysomes that were not digested by RNase was increased by higher concentrations of ABA applied during germination. At high concentrations of ABA (50, 100 μM), the quantitative contribution of polysomes in the total ribosomal fraction was almost 100% of the amount of polysomes before digestion and the modifications observed consisted mainly of the shift of the so-called heavy polysomes towards light polysomes, containing a few ribosomes. Within each polysomal population, cytoskeleton-bound polysomes (CBP and CMBP) were the most stable, which may imply that the bonds between polysomes and these protein filaments, created in all eukaryotic cells increased their stability. It is assumed that mRNAs are stabilised or destabilised by interaction of proteins with their various sequences. A plant hormone may depress or elevate the quantities of these proteins, thus regulating the stability of different mRNAs. The results confirm the multi-faceted mechanism of ABA-induced response, where one of the constituents is the effect of ABA on the stability of mRNAs molecules. The co-ordinated regulation of mRNAs synthesis and their stability provide plants with improved adaptability.     

Purification and characterization of cytoplasmic 14C-arginine rich basic proteins of Ehrlich ascites tumor cells

Summary Arginine rich basic proteins from cytoplasm of Ehrlich ascites tumor cells have been separated and partially characterized. All proteins show a cationic character with the following isoelectric points: 8.45, 8.60, 8.70, 8.90, and possess various amount of arginine. The protein of the highest molecular weight (75000) has the greatest amount of arginine (18.1%), specific radioactivity (19760 cpm/mg, min) and isoelectric point (8.9). The significance of those proteins in the cytoplasm of tumor cells has been discussed briefly.     

Immunospecificity of nuclear antigens in chicken erythroid cells

Summary Specific antisera were produced against chicken reticulocyte dehistonized chromatin. The antisera reacts strongly with chicken reticulocyte chromatin, but only marginally with chicken erythrocyte chromatin. There is no reticulocyte antigen detected in chicken liver. Reticulocyte maturation is accompanied by a gradual decrease in the chromatin immunological activity and template capacity. The reduction of immunological activity is due to the change of chromatin conformation during erythrocyte maturation. Dehistonization and sonication of erythrocyte chromatin raises the erythrocyte chromatin immunological activity to levels similar to those of reticulocyte chromatin. The erythrocyte nuclear antigens are class specific, not being found in frog erythroid cell or murine Friend leukemia cell chromatins.     

Neuronal Autophagy: Self-eating or Self-cannibalism in Alzheimer’s Disease

Autophagy is a major intracellular degeneration pathway involved in the elimination and recycling of damaged organelles and long-lived proteins by lysosomes. Many of the pathological factors, which trigger neurodegenerative diseases, can perturb the autophagy activity, which is associated with misfolded protein aggregates accumulation in these disorders. Alzheimer’s disease, the first neurodegenerative disorder between dementias, is characterized by two aggregating proteins, β-amyloid peptide (plaques) and τ-protein (tangles). In Alzheimer’s disease autophagosomes dynamically form along neurites within neuronal cells and in synapses but effective clearance of these structures needs retrograde transportation towards the neuronal soma where there is a major concentration of lysosomes. Maturation of autophago-lysosomes and their retrograde trafficking are perturbed in Alzheimer’s disease, which causes a massive concentration of autophagy elements along degenerating neurites. Transportation system is disturbed along defected microtubules in Alzheimer’s disease brains. τ-protein has been found to control the stability of microtubules, however, phosphorylation of τ-protein or an increase in the total level of τ-protein can cause dysfunction of neuronal cells microtubules. Current evidence has shown that autophagy is developing in Alzheimer’s disease brains because of ineffective degradation of autophagosomes, which hold amyloid precursor protein-rich organelles and secretases important for β-amyloid peptides generation from amyloid precursor. The combination of raised autophagy induction and abnormal clearance of β-amyloid peptide-generating autophagic vacuoles creates circumstances helpful for β-amyloid peptide aggregation and accumulation in Alzheimer’s disease. However, the key role of autophagy in Alzheimer’s disease development is still under consideration today. One point of view suggests that abnormal autophagy induction causes a concentration of autophagic vacuoles rich in amyloid precursor protein, β-amyloid peptide and the elements crucial for its formation, whereas other hypothesis points to marred autophagic clearance or even decrease in autophagic effectiveness playing a role in maturation of Alzheimer’s disease. In this review we present the recent evidence linking autophagy to Alzheimer’s disease and the role of autophagic regulation in the development of full-blown Alzheimer’s disease.