Sex chromosome loss, micronuclei, sister chromatid exchange and aging: a study including 16 centenarians

In the present study we analysed the possible effect of age, sex and smoking on the mean values of micronucleus (MN) and sister chromatid exchange (SCE) frequencies on peripheral blood obtained from 38 subjects ranging in age from 16 to 63 years and 16 centenarians. The mean number of binucleated cells with micronuclei varied in function of age and sex (as demonstrated by the analysis of covariance (F=13.13; P<0.001), particularly evident was the increment observed in women with increasing age (interaction age/sex: F=5.53; P<0.05). Smoking habits had no effects on MN frequency (F=0.36; P>0.05). Sex (F=4.18; P<0.05) and smoking habits (F=14.64; P<0.001) influenced significantly SCE per cell frequencies, but age had no effects on them (F=2.45; P>0.05).The age-associated increase of sex chromosome loss was studied using fluorescence in situ hybridisation (FISH) on interphase nuclei.The loss of Y signals was observed in 10% of interphase cells from the centenarians males, that is six times more often than in the younger control men (1.6%). The frequency of X signal loss (1.7%) in young women was similar to that observed in male controls of the same age but the incidence of the X chromosome aneuploidy in centenarian females was appreciably higher (22%) than that found for the Y chromosome in males. These results were correlated with the data on MN formation and a positive correlation between the percentage of aneuploid cells (FISH) and MN values was observed (r=0.50; P<0.05).     

A Psychological Exploration of Engagement in Geek Culture

Geek culture is a subculture of enthusiasts that is traditionally associated with obscure media (Japanese animation, science fiction, video games, etc.). However, geek culture is becoming increasingly mainstream; for example, in the past year alone, Dragon*Con, a major Geek convention in Atlanta, Georgia, attracted an attendance of over 57,000 members. The present article uses an individual differences approach to examine three theoretical accounts of geek culture. Seven studies (N = 2354) develop the Geek Culture Engagement Scale (GCES) to quantify geek engagement and assess its relationships to theoretically relevant personality and individual differences variables. These studies present evidence that individuals may engage in geek culture in order to maintain narcissistic self-views (the great fantasy migration hypothesis), to fulfill belongingness needs (the belongingness hypothesis), and to satisfy needs for creative expression (the need for engagement hypothesis). Geek engagement is found to be associated with elevated grandiose narcissism, extraversion, openness to experience, depression, and subjective well-being across multiple samples. These data lay the groundwork for further exploration of geek culture as well as provide a foundation for examining other forms of subculture participation.     

Transglutaminase-catalyzed modifications of SV-IV, a major protein secreted from the rat seminal vesicle epithelium

One of the major proteins secreted from the rat seminal vesicle epithelium, namely SV-IV, was shown to act in vitro as acyl donor and acceptor substrate for transglutaminase from both guinea pig liver and rat anterior prostate secretory fluid. Electrophoretic and chromatographic experiments indicated that the enzyme catalyzed the formation of multiple modified forms of SV-IV. In the absence of small Mr amines, transglutaminase was able to produce at least six different molecular forms of the protein, half of which possessed an Mr higher than that of native SV-IV. These findings suggested that a variable number of intermolecular, and perhaps intramolecular, crosslinks were formed between one or both glutamine residues and one or more lysine residues occurring in the SV-IV polypeptide chain. In addition, at least three modified forms of the protein were produced by transglutaminase in the presence of high concentrations of spermidine, thus indicating the formation of different (gamma-glutamyl)polyamine derivatives of SV-IV. Rabbit uteroglobin and rat anterior prostate secretory protein(s) were also shown to be able to covalently bind spermidine in the presence of the enzyme. The possible biological significance of transglutaminase-mediated modifications of SV-IV, as well as of other proteins occurring in the mammal seminal fluid, are discussed.     

The plant activation of m-phenylenediamine by Tradescantia clone 03 and clone 4430 cells in liquid suspension culture

In this study, we expanded the use of the genus Tradescantia to investigate the plant activation of promutagens and further refine the methodology of the plant cell/microbe coincubation assay. Liquid suspension cell cultures of Tradescantia clone 03 and Tradescantia clone 4430 were used to activate the promutagen m-phenylenediamine into a mutagenic compound which was detected by Salmonella typhimurium strain TA98 in the plant cell/microbe coincubation assay. Optimum treatment parameters were established for both plant cell lines. Optimum was defined as the lowest concentration or shortest time period that provided consistently positive results and high rates of revertants. Preliminary experiments with both cell lines defined 2.5 mumoles m-phenylenediamine per plate as the optimum concentration to be used in the determination of the optimal coincubation period and the optimal concentration of plant cells. These experiments also determined the optimal physiological stage at which both clones should be used in the coincubation assay. Differences were found in the optimal of coincubation (1h for clone 03, 2 h for clone 4430) and growth stage (mid-log for clone 03, mid- to late-log for clone 4430). Similar activation responses were seen for both clones when the concentration of plant cells (mg/ml) was varied. Under optimized conditions, clone 03 cells demonstrated an approximately 10% higher activation response than clone 4430.     

The Pyrexia transient receptor potential channel mediates circadian clock synchronization to low temperature cycles in Drosophila melanogaster

Circadian clocks are endogenous approximately 24 h oscillators that temporally regulate many physiological and behavioural processes. In order to be beneficial for the organism, these clocks must be synchronized with the environmental cycles on a daily basis. Both light : dark and the concomitant daily temperature cycles (TCs) function as Zeitgeber (‘time giver’) and efficiently entrain circadian clocks. The temperature receptors mediating this synchronization have not been identified. Transient receptor potential (TRP) channels function as thermo-receptors in animals, and here we show that the Pyrexia (Pyx) TRP channel mediates temperature synchronization in Drosophila melanogaster. Pyx is expressed in peripheral sensory organs (chordotonal organs), which previously have been implicated in temperature synchronization. Flies deficient for Pyx function fail to synchronize their behaviour to TCs in the lower range (16–20°C), and this deficit can be partially rescued by introducing a wild-type copy of the pyx gene. Synchronization to higher TCs is not affected, demonstrating a specific role for Pyx at lower temperatures. In addition, pyx mutants speed up their clock after being exposed to TCs. Our results identify the first TRP channel involved in temperature synchronization of circadian clocks.     

Betacyanins as phenol antioxidants. Chemistry and mechanistic aspects of the lipoperoxyl radical-scavenging activity in solution and liposomes

Reaction kinetics of betanin and its aglycone betanidin towards peroxyl radicals generated from the azo-initiated oxidation of methyl linoleate in methanol and of a heterogeneous aqueous/soybean phosphatidylcholine liposomal system were studied by monitoring formation of linoleic acid hydroperoxides and consumption of the pigments. Betanin was a weak retarder in methanol and an effective chain breaking antioxidant in the liposomal model, indicating that kinetic solvent effects and partition in lipid bilayers may affect its activity. Betanidin behaved as a chain terminating antioxidant in both models. Kinetic parameters characterizing peroxyl radical-scavenging activity showed that betanidin was more effective than betanin, in terms of both radical-scavenging rate constant and stoichiometric factor, with effectiveness of the same order as vitamin E under comparable conditions. Products identified by spectrophotometric and HPLC techniques indicated reaction of the glucose-substituted monophenol and ortho-diphenol moieties of betanin and betanidin, respectively, and suggested mechanisms of the antioxidant activity. Either betanin or betanidin incorporated in liposomes with α-tocopherol had additive effects, supporting partition of the pigments in the bilayer and lipoperoxyl radical reduction.