Adjustment of the Sleep-Wake Cycle to Small (1-2h) Changes in Schedule

Changes of schedules larger than 3 h, such as jet lag and shift work, require an adjustment period of several days to resynchronize the sleep-wake cycle and several weeks to resynchronize other circadian rhythms to the new schedule. Initial studies on adaptation to small changes of schedule (1-2 h) found that the sleep-wake cycle adapts to the new schedule in less than 48 h, and such modifications are generally not studied because they may be confounded by a potential masking effect. This article summarizes the few published studies on Daylight Saving Time (DST) and sleep during weekends, two examples of small changes in schedule. There are individual differences in adaptation to daylight saving time, while some persons adjust immediately; other persons require more than 2 weeks. During weekends, people tend to go to bed and wake up later, and to extend their sleep. Delay and extension of sleep depend on factors such as shift of work during weekdays and chronotype (morningness-eveningness). Both DST and sleep during weekends offer the opportunity to study adaptation of the sleep-wake cycle in recurrent, social conditions. Studying these phenomena is also relevant to some socioeconomic issues, like the reportedincrease of traffic accidents and complaints from the population during daylight saving time; or the possible decrease in productivity and absenteeism during the 'Blue Monday'.     

Circadian and homeostatic modulation of the attentional blink

An important property of attention is the limitation to process new information after responding to a stimulus. This property of attention can be evaluated by the Attentional Blink (AB), a phenomenon that consists of a failure to detect the second of two targets when the interval between them is 200–500 ms. The aim of the present work is to determine the possible existence of time awake (homeostatic changes) and time of day (circadian rhythm) variations in the AB. Eighteen undergraduate students, 11 men and 7 women, age = 18.06 ± 1.16 years, participated voluntarily in this research. They were recorded in a constant routine protocol during 29 h, in which rectal temperature was recorded every minute, while subjective sleepiness and responses to a Rapid Serial Visual Presentation (RSVP) task, to measure the AB, were recorded every hour. Homeostatic and circadian variations in all parameters of the RSVP task were observed, including changes in the capacity to process a new stimulus (Target 1 accuracy), a second stimulus occurring in a short interval after the first (Target 2 accuracy at lag 2, 200 ms) and to process another successive independent stimulus (Target 2 accuracy at lag 8, 800 ms). The acrophase of these parameters occurred with a phase delay of 2 h compared to the circadian rhythm of rectal temperature. The AB magnitude, an index of the AB, showed a decline with time awake, but no variations with time of day. In conclusion, there are homeostatic and circadian variations in the capacity to process any incoming information, especially in tasks with brief duration stimuli presented at a high frequency.     

Target-assembled ExciProbes: Application to DNA Detection at the Level of PCR Product and Plasmid DNA

Abstract

Recently, we introduced a novel exciplex-based approach for detection of nucleic acids using a model DNA-mounted exciplex system, consisting of two 8-mer ExciProbes hybridized to a complementary 16-mer DNA target. We now show, for the first time, that this approach can be used to detect DNA at the level of PCR product and plasmid, when the target sequence (5′-GCCAAACACAGAATCG-3′) was embedded in long DNA molecules (PCR products and ～3 Kbp plasmid). A remarkably stringent demand is made of the solvent conditions for this exciplex emission to occur, viz., emission is optimal for DNA at 80% tri-fluoroethanol, even in the plasmid situations, raising the question of the molecular structural basis of this system. We show that a perfectly matched plasmid target can be differentiated from target containing single nucleotide substitutions; hence, ExciProbes could be applied to SNP analysis. The effect of counter cations (Na⁺, K⁺, and Mg²⁺) and PCR additives on exciplex emission has been also examined.     

Identification of circadian rhythms in cognitive inhibition and flexibility using a Stroop task

The objective of this study was to identify circadian rhythms in cognitive inhibition and flexibility using a Stroop task. Eight undergraduate student volunteers (age = 17.75 ± 0.46 years; 7 females), participated in this study. Participants were recorded in a constant routine protocol for 29 h. Body temperature was recorded every minute, and every 100 min participants completed scales of sleepiness and tiredness and responded to a Stroop task with shifting criteria. This task includes a chart with 48 colors printed with incongruent names. A random half of the words had a point on the left. Participants were instructed to do four actions: (i) read all the words; (ii) name the color in which each word was printed; (iii) read the words marked with a point and name the colors of the unmarked words; and (iv) name the colors of the words marked with a point and read the unmarked words. The time and errors in naming the colors were considered inhibition indices, while performance time and errors upon shifting criteria were considered flexibility indices. Circadian variations were found in inhibition (color-naming) and flexibility (shifting criteria). These cognitive processes also showed decay with time on task. In conclusion, there were circadian variations in two components of executive functions: inhibition and flexibility, modulated by sustained attention (time on task). These results may explain the difficulties experienced at night in problem-solving that requires adjustment of behavior in accordance with environmental demands.

     

Prognostic Value of Serum Iron,Ferritin, and Transferrin in Chronic Alcoholic Liver Disease

Biological Trace Element Research - Ethanol increases iron absorption. Therefore, increased amount of iron reaches the liver, and exerts pro-oxidant effects and stimulates ferritin synthesis and...     

First record of Buenia massutii Kovačić, Ordines, & Schliewen, 2017 in the Atlantic Ocean based on molecular and morphological evidences

The recently described Mediterranean goby species, Buenia massutii, was found at the deep shelf in the Gulf of Cádiz (north-eastern Atlantic Ocean). The identification of the specimen was performed using morphological analysis and molecular techniques; including the sequencing of the mitochondrial genes Cytochrome c Oxidase I (DNA barcode) and Cytochrome b. The sequences for Cytochrome b is presented for the first time for B. massutii. The limited migration capability and behaviour of small benthic gobies, the short lifespan of Buenia species, and the oceanographic characteristics of the Strait of Gibraltar suggest the existence of an independent Atlantic population of B. massutii.