Abstract Variation in pigmentation is common in marine invertebrates, although few studies have shown the existence of genetic differentiation of chromatic forms in these organisms. We studied the genetic structure of a colonial ascidian with populations of different colour morphs in the northwestern Mediterranean. A fragment of the c oxidase subunit 1 (COI) mitochondrial gene was sequenced in seven populations of Pseudodistoma crucigaster belonging to three different colour morphs (orange, yellow and grey). Maximum likelihood analyses showed two well‐supported clades separating the orange morph from the yellow‐grey morphotypes. Genetic divergence between these clades was 2.12%, and γ ST values between populations of the two clades were high (average 0.936), pointing to genetic isolation. Nested clade and coalescence analyses suggest that a past fragmentation event may explain the phylogeographical origin of these two clades. Non‐neutral mtDNA evolution is observed in our data when comparing the two clades, showing a significant excess of nonsynonymous polymorphism within the yellow–grey morphotype using the McDonald–Kreitman test, which is interpreted as further support of reproductive isolation. We conclude that the two clades might represent separate species. We compare the population genetic differentiation found with that estimated for other colonial and solitary ascidian species, and relate it to larval dispersal capabilities and other life‐history traits.
Theory concerning the evolution of sex and recombination and mutation load relies on information on rates and distributions of effects of deleterious mutations. Direct information on the genomic mutation rate in Drosophila implies that an accumulation of mildly deleterious mutations reduces viability of populations by at least 1% per generation. We carried out an experiment to measure the deleterious mutation rate in Caenorhabditis elegans , in which independent sublines were maintained with one hermaphrodite parent per generation, conditions that minimize the opportunity for natural selection and lead to random fixation of deleterious mutations. After 60 generations of mutation accumulation, negligible changes in mean reproductive output and lifespan occurred, but the genetic variance increased at rates typical for life history traits in other species. The estimated deleterious mutation rate per haploid genome for fitness, U , was 0.0026, a figure two orders of magnitude smaller than previously measured for viability in Drosophila .
Multiple component rhythmometry, a method that fits a model consisting of several significant cosine functions, was used to describe the nonsinusoidal seasonal pattern in the incidence of some common enterobacteria. Awareness of this predictable patterns may be important in the prevention, diagnosis and treatment of bacteriological infections.
The use of ambulatory lood pressure (BP) monitoring (ABPM) has provided a method of BP assessment that compensates for some of the limitations of office values. The most common approach is still to rely for diagnosis on the daily mean of a 24-hour profile [O'Brien & Staessen. Blood Pressure 1995;4:266-282]. With the objective to assess the reproducibility of BP between 2 consecutive days of ABPM, we studied 310 mild-to-moderate hypertensive patients (125 men), 54.9±0.7 (X±SE) years of age, who underwent ABPM at 20-minute intervals during the day and at 30-minute intervals during the night for 48 consecutive hours with an ambulatory Spacelabs 90207 device. Daily, diurnal and nocturnal mean values computed for each patient according to individual resting hours determined by diary and wrist actigraphy were compared between consecutive days of ABPM by paired t-test. Results indicate a highly statistically significant (P<0.001) reduction during the second day of ABPM as compared to the first in the diurnal (during daily activity) mean of SBP and DBP (2.28 and 1.70 mmHg, respectively), but not for HR (P=0.697). The nocturnal means of BP were, however, similar between both days of sampling (differences of -0.59 and 0.06 mmHg for SBP and DBP; P>0 612). As a consequence of the decrease in the BP during activity but not during nocturnal resting hours, there is a 7% increase (from 49 to 56%) of non-dippers when this classification is obtained on the basis of data sampled during the second day of ABPM as compared to the first. ABPM during two consecutive days reveals statistically significant differences in diurnal but not nocturnal BP that could reflect a novelty effect in the use of the device. These results indicate that an unique 24-hour profile of ABPM may be insufficient for a proper diagnosis of hypertension, evaluation of treatment efficacy, and identification of dipping status in relation to target organ damage.
In this chapter, the authors address the main properties derived from the multifunctionality of the nanocomposites and presents potential applications in the fields of catalysis and sensing. They focuses on hybrid nanocomposites consisting of a single metal nanoparticle core and a thermoresponsive polymer shell. The authors restrict themselves to shells made of poly-N-isopropylacrylamide (pNIPAM), since this is the standard microgel model system and it has been used in most of the work related to this particular type of nanocomposites. They provide an overview of the different synthetic approaches, with an emphasis on the effect of the obtained structure on the main properties that are characteristic of these materials. The authors also address different applications, as well as future perspectives. An initial protocol was developed that involved the polymerization of styrene and divinylbenzene at the surface of the metal particles prior to introducing them in the pNIPAM polymerization medium.
Due to the exponential increase in energy consumption and CO 2 emissions, new sustainable energy sources have emerged, and hydrogen (H 2 ) is one of them. Despite all the advantages, H 2 has high flammability, so constant monitoring is essential. Two optical techniques were numerically studied and compared with the goal of H 2 sensing: surface plasmon polaritons (SPP) and Tamm plasmon polaritons (TPP). The H 2 -sensitive material used was palladium (Pd) in both techniques. The SPP structure was found to have more sensitivity to H 2 than TPP, 23 and 5nm/4vol% H 2 , respectively. However, the latter has lower FWHM, with the minimum of the band showing reflectivity near 0%. In addition, TPP also uses more costeffective materials and can be interrogated at normal incidence with depolarized light. The potential of using each of these optical techniques for H 2 sensing was demonstrated.
Several studies have shown statistically significant circadian rhythms in thromboxane and prostacyclin production, circulating platelets, platelet aggregation, clotting and fibrinolytic inhibitors, circulating angiotensin II, angiotensin sensitivity, and the inhibition of platelet aggregation produced by aspirin (ASA). Moreover, ASA exhibits a faster drug-disappearance rate when administered during the morning as compared to the evening. Despite this evidence, previous studies on the potential influence of ASA on blood pressure (BP) have not taken into consideration the chronopharmacological effects of nonsteroidal antiinflammatory drugs. This pilot study investigates the effects of ASA on BP in untreated hypertensive patients who received ASA at different times of the day according to their rest-activity cycle. We studied 78 patients with mild hypertension (36 men), 43.5±11.4 (mean±SD) years of age, divided in 3 groups: non-pharmacological hygienic-dietary recommendations (HDR); HDR and ASA (100 mg/day) on awakening; or HDR and ASA before bedtime. BP and heart rate (HR) were measured every 20 minutes during the day (07:00 to 23:00 hours) and every 30 minutes at night for 48 consecutive hours before and after 3 months of intervention. The circadian pattern of BP in each group was established by population multiple-component analysis [Fernandez & Hermida. Chronobiol Int. 1998;15:191-204]. After 3 months of non-pharmacological intervention, there was a small and non-significant reduction of BP (1.2 mm Hg for systolic BP, 1.4 mm Hg for diastolic BP; P=0.264). There was no effect of ASA on BP when given on awakening (P=0.211). A BP reduction was, however, highly significant when ASA was given before bedtime (decrease of 7.6 and 6.1 mm Hg in systolic and diastolic BP, respectively; P<0.001). There was no significant change in HR in any group. Results indicate a statistically significant administration-time dependent effect of low-dose ASA on BP in untreated patients with mild hypertension. In any trial of ASA effects, inquiries about the time when subjects took the drug are indicated and may account for discrepancies in the literature. Moreover, the influence of ASA on BP demonstrated here indicates the need to identify and control for ASA effects in patients using this drug before or during their participation in antihypertension medication trials. DGES, PM98-0106; PGICT00-PXI-32205PN; University of Vigo.
