Validation of an innovative method,based on tilt sensing,for the assessment of activity and body position

Since there is less movement during sleep than during wake, the recording of body movements by actigraphy has been used to indirectly evaluate the sleep–wake cycle. In general, most actigraphic devices are placed on the wrist and their measures are based on acceleration detection. Here, we propose an alternative way of measuring actigraphy at the level of the arm for joint evaluation of activity and body position. This method analyzes the tilt of three axes, scoring activity as the cumulative change of degrees per minute with respect to the previous sampling, and measuring arm tilt for the body position inference. In this study, subjects (N?=?13) went about their daily routine for 7 days, kept daily sleep logs, wore three ambulatory monitoring devices and collected sequential saliva samples during evenings for the measurement of dim light melatonin onset (DLMO). These devices measured motor activity (arm activity, AA) and body position (P) using the tilt sensing of the arm, with acceleration (wrist acceleration, WA) and skin temperature at wrist level (WT). Cosinor, Fourier and non-parametric rhythmic analyses were performed for the different variables, and the results were compared by the ANOVA test. Linear correlations were also performed between actimetry methods (AA and WA) and WT. The AA and WA suitability for circadian phase prediction and for evaluating the sleep–wake cycle was assessed by comparison with the DLMO and sleep logs, respectively. All correlations between rhythmic parameters obtained from AA and WA were highly significant. Only parameters related to activity levels, such as mesor, RA (relative amplitude), VL5 and VM10 (value for the 5 and 10 consecutive hours of minimum and maximum activity, respectively) showed significant differences between AA and WA records. However, when a correlation analysis was performed on the phase markers acrophase, mid-time for the 10 consecutive hours of highest (M10) and mid-time for the five consecutive hours of lowest activity (L5) with DLMO, all of them showed a significant correlation for AA (R?=?0.607, p?=?0.028; R?=?0.582, p?=?0.037; R?=?0.620, p?=?0.031, respectively), while for WA, only acrophase did (R?=?0.621, p?=?0.031). Regarding sleep detection, WA showed higher specificity than AA (0.95?±?0.01 versus 0.86?±?0.02), while the agreement rate and sensitivity were higher for AA (0.76?±?0.02 versus 0.66?±?0.02 and 0.71?±?0.03 versus 0.53?±?0.03, respectively). Cohen’s kappa coefficient also presented the highest values for AA (0.49?±?0.04) and AP (0.64?±?0.04), followed by WT (0.45?±?0.06) and WA (0.37?±?0.04). The findings demonstrate that this alternative actigraphy method (AA), based on tilt sensing of the arm, can be used to reliably evaluate the activity and sleep–wake rhythm, since it presents a higher agreement rate and sensitivity for detecting sleep, at the same time allows the detection of body position and improves circadian phase assessment compared to the classical actigraphic method based on wrist acceleration.     

Bright Light Therapy for Winter Depression—Is Phase Advancing Beneficial?

Bright light is the recommended treatment for winter seasonal affective disorder (SAD). Previously we showed that the antidepressant effect of morning (but not evening) light was greater than placebo after 3 weeks of treatment. Here, we determined if the magnitude and direction of circadian rhythm phase shifts produced by the bright light in the previous study were related to the antidepressant effects. Twenty-six SAD patients from the original sample of 96 had their rectal temperature continuously monitored while they participated in a placebo-controlled parallel design conducted over six winters. After a baseline week, there were three treatments for 4 weeks—morning light, evening light, or morning placebo. Bright light was produced by light boxes (?6000 lux). Placebos were sham negative ion generators. All treatments were 1.5 h in duration. Depression ratings were made weekly by blind raters. Circadian phase shifts were determined from changes in the timing of the core body temperature minimum (Tmin). Morning light advanced and evening light delayed the Tmin by about 1 h. The placebo treatment did not alter circadian phase. As the sleep schedule was held constant, morning light increased and evening light decreased the Tmin to wake interval, or phase angle between circadian rhythms and sleep. Phase advance shifts and increases in the phase angle were only weakly associated with antidepressant response. However, there was an inverted U-shaped function showing that regardless of treatment assignment the greatest antidepressant effects occurred when the phase angle was about 3 h, and that patients who moved closer to this phase angle benefited more than those who moved farther from it. However 46% of our sample had a phase angle within 30 min of this 3 h interval at baseline. So it does not appear that an abnormal phase angle can entirely account for the etiology of SAD. A majority (75%) of the responders by strict joint criteria had a phase angle within this range after treatment, so it appears that obtaining the ideal phase relationship may account for some, but not all of the antidepressant response. In any case, regardless of the mechanism for the antidepressant effect of morning light, it can be enhanced when patients sleep at the ideal circadian phase and reduced when they sleep at a more abnormal circadian phase.     

Parthenogenetic development of dwarf surf dam,Mulinia lateralis,oocytes treated with polar body suppressing agents

Summary

Parthenogenesis following oocyte activation has been observed in a number of marine invertebrates, but the fate of parthenogenesis in bivalve mollusc embryos is unclear. We used the dwarf surf clam, Mulinia lateralis, to examine parthenogenetic development of KC1-activated oocytes using the polar body suppressing agents caffeine and heat or cytochalasin B. Development was followed by epifluorescence microscopy and flow-cytometric analysis using the DNA-specific fluorochrome DAPI. All agents suppressed polar body formation to some degree, putatively increasing the ploidy level and retaining a meiotic centrosome in the zygote; but the zygotes failed to develop normally. Failure of the zygotes to develop suggests that the meiotic centrosome is incapable of participating in mitosis in bivalves.     

Optimal growth strategies under divergent predation pressure

The conditions leading to gigantism in nine‐spined sticklebacks Pungitius pungitius were analysed by modelling fish growth with the von Bertalanffy model searching for the optimal strategy when the model's growth constant and asymptotic fish size parameters are negatively related to each other. Predator‐related mortality was modelled through the increased risk of death during active foraging. The model was parameterized with empirical growth data of fish from four different populations and analysed for optimal growth strategy at different mortality levels. The growth constant and asymptotic fish size were negatively related in most populations. Optimal fish size, fitness and life span decreased with predator‐induced mortality. At low mortality, the fitness of pond populations was higher than that of sea populations. The differences disappeared at intermediate mortalities, and sea populations had slightly higher fitness at extremely high mortalities. In the scenario where all populations mature at the same age, the pond populations perform better at low mortalities and the sea populations at high mortalities. It is concluded that a trade‐off between growth constant and asymptotic fish size, together with different mortality rates, can explain a significant proportion of body size differentiation between populations. In the present case, it is a sufficient explanation of gigantism in pond P. pungitius.     

Three-Dimensional Structure of CAP-Gly Domain of Mammalian Dynactin Determined by Magic Angle Spinning NMR Spectroscopy: Conformational Plasticity and Interactions with End-Binding Protein EB1

Microtubules and their associated proteins play important roles in vesicle and organelle transport, cell motility and cell division. Perturbation of these processes by mutation typically gives rise to severe pathological conditions. In our efforts to obtain atomic information on microtubule-associated protein/microtubule interactions with the goal to understand mechanisms that might potentially assist in the development of treatments for these diseases, we have determined the three-dimensional structure of CAP-Gly (cytoskeleton-associated protein, glycine-rich) domain of mammalian dynactin by magic angle spinning NMR spectroscopy. We observe two conformations in the β2 strand encompassing residues T43-V44-A45, residues that are adjacent to the disease-associated mutation, G59S. Upon binding of CAP-Gly to microtubule plus-end tracking protein EB1, the CAP-Gly shifts to a single conformer. We find extensive chemical shift perturbations in several stretches of residues of CAP-Gly upon binding to EB1, from which we define accurately the CAP-Gly/EB1 binding interface. We also observe that the loop regions may exhibit unique flexibility, especially in the GKNDG motif, which participates in the microtubule binding. This study in conjunction with our previous reports suggests that conformational plasticity is an intrinsic property of CAP-Gly likely due to its unusually high loop content and may be required for its biological functions.     

Ontogenetic shifts in phenotype–environment associations in Nile perch,Lates niloticus (Perciformes: Latidae) from Lake Nabugabo,Uganda

Habitat‐associated trait divergence may vary across ontogeny if there are strong size‐related shifts in selection pressures. We quantified patterns of phenotypic divergence in Nile perch (Lates niloticus) from ecologically distinct wetland edge and forest edge habitats in Lake Nabugabo, Uganda, and we compared patterns of divergence across three size classes to determine whether trends are consistent through Nile perch ontogeny. We predicted that inter‐habitat variation in biotic (e.g. vegetation structure) and abiotic (e.g. dissolved oxygen concentration) variables may create divergent selective regimes. We compared body morphology using geometric morphometrics and found substantial differences between habitats, although not all trends were consistent across size classes. The most striking aspects of divergence in small Nile perch were in mouth orientation, head size, and development of the caudal region. Medium‐sized Nile perch also showed differences in mouth orientation. Differences in large individuals were related to eye size and orientation, as well as caudal length. The observed patterns of divergence are consistent with functional morphological predictions for fish across divergent trophic regimes, high and low predation environments, and complex and simple habitats. Although this suggests adaptive divergence, the source of phenotypic variation is unknown and may reflect phenotypic plasticity and/or genetic differences. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 449–465.     

Long-term calorie restriction has minimal impact on brain metabolite and fatty acid profiles in aged rats on a Western-style diet

The effect of long-term calorie restriction (CR) on metabolites, fatty acid profiles and energy substrate transporter expression in the brain was assessed in aged rats. Three groups of male Sprague–Dawley rats were studied: (i) a 2 month old ad libitum-fed (2AL group), (ii) a 19 month old ad libitum-fed (19AL group), and (iii) a 19 month old group subjected to 40% CR from the age of 7.5 to 19 months (19CR group). The diet contained high sucrose and low n-3 polyunsaturated fatty acids (PUFA) so as to imitate a Western-style diet. High resolution magic angle spinning-¹H NMR showed an effect of aging on brain cortex metabolites compared to 2AL rats, the largest differences being for myo-inositol (+251% and +181%), lactate (+203% and +188%), β-hydroxybutyrate (+176% and +618%) and choline (+148% and +120%), in 19AL and 19 CR rats, respectively. However, brain metabolites did not differ between the 19AL and 19CR groups. Cortex fatty acid profiles showed that n-3 PUFA were 35–47% lower but monounsaturated fatty acids were 40–52% higher in 19AL and 19CR rats compared to 2AL rats. Brain microvessel glucose transporter (GLUT1) was 68% higher in 19AL rats than in 2AL rats, while the monocarboxylate transporter, MCT1, was 61% lower in 19CR rats compared to 19AL rats. We conclude that on a high-sucrose, low n-3 PUFA diet, the brain of aged AL rats had higher metabolites and microvessel GLUT1 expression compared to 2AL rats. However, long-term CR in aged rats did not markedly change brain metabolite or fatty acid profile, but did reduce brain microvessel MCT1 expression.     

Overwintering strategy of endoparasitoids in Chilo suppressalis: a perspective from the cold hardiness of a host

Although parasitoids ultimately kill their host, koinobiont parasitoids must protect not only themselves but also their hosts against extreme environments. In this study, the parasitism rate of Chilo suppressalis Walker (Lepidoptera: Pyralidae) was investigated, and the average body weights, supercooling points, and concentrations of glycerol (acting as a cryoprotectant) in the hemolymph were compared between parasitized and non‐parasitized larvae. Five species of koinobiont endoparasitoids parasitized the overwintering C. suppressalis larvae and the total parasitism rate was 47.6% (n = 1 537). Average body weight of parasitized larvae was significantly lower than that of non‐parasitized larvae, and the parasitism rate of the lighter group (20–30 mg) was highest. The supercooling point of parasitized C. suppressalis larvae (?15.7 ± 0.3 °C) was significantly lower than that of the non‐parasitized larvae (?14.3 ± 0.2 °C). In addition, supercooling points were not correlated with body weights between parasitized and non‐parasitized larvae, indicating that cold hardiness of parasitized larvae was enhanced by endoparasitoids. Furthermore, the concentration of glycerol in the hemolymph was significantly higher in parasitized larvae (205.0 ± 7.1 μmol ml^?1) than in non‐parasitized larvae (169.8 ± 14.4 μmol ml^?1), which suggests that the mechanism that decreases the supercooling point of parasitized larvae was associated with glycerol. All these results indicated that the cold hardiness of parasitized C. suppressalis larvae was enhanced by their endoparasitoids, which benefitted overwintering endoparasitoids.