The Food-entrainable Oscillator Is a Complex of Non-SCN Activity Bout Oscillators Uncoupled From the SCN Circadian Pacemaker

The food-entrainable oscillator, which underlies the prefeeding activity peak developed by restricted daily feeding (RF) in rodents, does not depend on the circadian pacemaker in the suprachiasmatic nucleus (SCN) or on the known clock genes. In the present study, to clarify the roles of SCN circadian pacemaker and nutrient conditions on the development of prefeeding activity peak, RF of 3-h daily feeding was imposed on four groups of adult male mice for 10 cycles at different circadian times, zeitgeber time (ZT)2, ZT8, ZT14, and ZT20, where ZT0 is the time of lights-on in LD12:12. Seven days after the termination of RF session with ad libitum feeding in between, total food deprivation (FD) for 72 h was imposed. Wheel-running activity and core body temperature were measured throughout the experiment. Immediately after the RF or FD session, the PER2::LUC rhythms were measured in the cultured SCN slices and peripheral tissues. Not only the buildup process and magnitude of the prefeeding activity peak, but also the percentages of nocturnal activity and hypothermia developed under RF were significantly different among the four groups, indicating the involvement of light entrained circadian pacemaker. The buildup of prefeeding activity peak was accomplished by either phase-advance or phase-delay shifts (or both) of activity bouts comprising a nocturnal band. Hypothermia under FD was less prominent in RF-exposed mice than in naïve counterparts, indicating that restricted feeding increases tolerance to caloric restriction as well as to the heat loss mechanism. RF phase-shifted the peripheral clocks but FD did not affect the clocks in any tissue examined. These findings are better understood by assuming multiple bout oscillators, which are located outside the SCN and directly drive activity bouts uncoupled from the circadian pacemaker by RF or hypothermia.

Obtaining Cellulose-Available Raw Materials by Pretreatment of Common Agro-Forestry Residues With Pleurotus spp.

The goals of the present study were to characterize the profile of ligninolytic enzymes in five Pleurotus species and determine their ability to delignify eight common agro-forestry residues. Generally, corn stalks were the optimal inducer of Mn-dependent peroxidase activity, but the activity peak was noted after wheat straw fermentation by P. eryngii (3066.92 U/L). P. florida was the best producer of versatile peroxidase, especially on wheat straw (3028.41 U/L), while apple sawdust induced the highest level of laccase activity in P. ostreatus (49601.82 U/L). Efficiency of the studied enzymes was expressed in terms of substrate dry matter loss, which was more substrate-than species-dependent. Reduction of substrate dry mass ranged between 24.83% in wheat straw and 8.83% in plum sawdust as a result of fermentation with P. florida and P. pulmonarius, respectively. The extent of delignification of the studied substrates was different, ranging from 51.97% after wheat straw fermentation by P. pulmonarius to 4.18% in grapevine sawdust fermented by P. ostreatus. P. pulmonarius was also characterized by the highest cellulose enrichment (6.54) and P. ostreatus by very low one (1.55). The tested biomass is a highly abundant but underutilized source of numerous value-added products, and a cocktail of ligninolytic enzymes of Pleurotus spp. could be useful for its environmentally and economically friendly transformation.

Coexistence of three mephitids in Tehuacán-Cuicatlán Biosphere Reserve, México

Three species of mephitids coexist in the Tehuacán-Cuicatlán biosphere reserve (TCBR) and belong to a guild of mammalian carnivores that feed mainly on invertebrates. To infer the interspecific interactions that allow coexistence, we aimed to compare activity patterns and abundance of hog-nosed skunk (Conepatus leuconotus), hooded skunk (Mephitis macroura), and southern spotted skunk (Spilogale angustifrons) in a tropical dry forest with ecological integrity. We analyzed activity patterns and overlap, and compared the relative abundance index (IAR) of mephitids, between rainy and dry seasons and among species, and used 235 records for C. leuconotus, 39 for M. macroura, and 42 for S. angustifrons from 15 camera-trap stations in Mount Tepetroja, Puebla, from May 1st, 2013 to April 30th, 2020. The three mephitids were active mainly during the nocturnal period, although C. leuconotus showed a unimodal pattern with activity peak around midnight, M. macroura had a bimodal pattern with activity peaks during the crepuscular hours at sunset and sunrise, and S. angustifrons had a unimodal pattern with activity peak around 2:00 a.m. Mean activity of C. leuconotus (µ±SE = 00:42 ± 00:12 h) and M. macroura (01:02 ± 00:33 h) were similar (P = 0.32), and differed from the mean activity of S. angustifrons (01:49 ± 00:23 h, P = 0.02). C. leuconotus had the highest IAR (2.53 to 7.90) and differed from M. macroura (0.44 to 1.21) and S. angustifrons (0.83 to 0.96) in both seasons (P < 0.01). C. leuconotus and M. macroura showed higher IAR during the rainy season, in contrast with S. angustifrons that had no differences in IAR between seasons. The mephitids presented temporal segregation and variability in seasonal abundance as coexistence mechanisms. S. angustifrons showed the most restricted circadian activity and avoided the other two mephitids’ activity peaks. C. leuconotus was the most abundant species; thus, we inferred that the hog-nosed skunk determined the dynamics of intraguild interactions among mephitids in the tropical dry forest in the TCBR.

31 Physical Activity, Muscle Strength and Quantity: Preliminary Findings From the Mass_Lifecourse Cohort

Introduction We established the MASS_Lifecourse study to investigate changes in skeletal muscle between ages 45–85. Reduced physical activity (PA) is a key factor linked to the development of sarcopenia. Our aim was the describe the amount and patterns of PA and sedentary behaviour (SB), and relationships with muscle strength and quantity, among MASS_Lifecourse participants. Method Participants wore a triaxial accelerometer on their dominant wrist for seven days. Recordings were analysed to calculate time in moderate-vigorous PA (MVPA) with time not in MVPA classified as SB based on wrist position. Muscle strength was measured with a Jamar grip dynamometer and the 5 chair-stand test. Muscle quantity was assessed using appendicular lean muscle mass from dual-energy X-ray absorptiometry. Physical performance was assessed by gait speed. Results 68 participants (31 male) aged 47–84 (mean 65) participated in the present study. Median daily MVPA was 19.1 (IQR 7.1, 36.6) minutes and was lower with age. The mean sedentary time per day was 767.1 minutes per day and increased with age. The pattern of MVPA across the day changed with age: the oldest group (75–84 years) achieved a lower morning activity peak followed by an earlier decline whilst the younger groups were more consistently active throughout the day. Participants were more active than population reference data from the Active Lives Survey. Time spent in MVPA was positively associated with muscle strength and physical performance, whereas SB was negatively associated. Muscle quantity was not associated with PA or SB. Conclusions Participants in the MASS_Lifecourse study are more active than the general population but still show age-related declines in physical activity and strength. Future work in the cohort aims to elucidate mechanisms underlying the age-related loss of muscle strength and quantity.

Effects of Different Infra-Red Irradiations on the Survival of Granary Weevil Sitophilus granarius: Bioefficacy and Sustainability

Sitophilus granarius (L.) is an important pest of stored grain worldwide. In recent years, sustainable methods against it have received attention as grain stock protective means. Our aim was to obtain information about the efficacy of infrared irradiation (IR) against S. granarius in laboratory conditions. The change in adult-activity and median lethal dose (LD50) triggered by IR in S. granarius was examined. The insecticidal efficacy in the infested grains was also analyzed at 12, 24, 48, and 72h following exposure to IR (250W), and the progeny-production was assessed 45 days upon the treatment. Based on our findings, total mortality ensued in a grain stock of 50 g at 412 s and a for 100 g grain at 256 s. A significant increase in S. granarius mortality could be observed in the higher grain weight regime, which can be accounted for by the higher heat-absorbance of objects with higher weight. The activity of pests immediately after the beginning of IR increased and subsequently became moderated. The observation of activity-peak brought about by irradiation contribute to the optimization of chemical intervention. This treatment could provide an effective and sustainable technique in integrated pest management.

Circadian clock neurons maintain phase control over daily behavioral activity patterns under diverse environmental conditions

Proper timing of rhythmic locomotor behavior is the consequence of integrating environmental conditions and internal time within the circadian clock. The 150 clock neurons in the Drosophila melanogaster brain are organized in various clusters, controlling different aspects of the daily activity rhythms. For example, during regular 12 hr light : 12 hr dark cycles at constant temperature (LD), so called Morning (M) neurons control the activity peak in the morning, while Evening (E-) neurons regulate the activity increase at the end of the day. During the remaining times of day and night, flies are inactive, giving rise to the crepuscular behavior observed in LD. Here, we investigate if the same neuronal groups also control behavioral activity under very different environmental conditions of constant light and temperature cycles (LLTC). While the morning activity is completely absent in LLTC, a single pronounced activity peak occurs at the end of the thermophase. We show that the same E-neurons operating in LD, also regulate the evening peak in LLTC. Interestingly, neuronal activity of E-neurons is inversely correlated with behavioral activity, suggesting an inhibitory action on locomotion. Surprisingly, the E-cells responsible for synchronization to temperature cycles belong to the clock neurons containing the circadian photoreceptor Cryptochrome, previously suggested to be more important for synchronization to LD. Our results therefore support a more deterministic function of the different clock neuronal subgroups, independent of specific environmental conditions.Significance statementMaster circadian clocks in the brains of mammals and fruit fly are composed of neurons expressing varying types of neuropeptides and transmitters. This diversity along with anatomical differences indicate diverse functions of different clock neurons. In Drosophila, so-called Morning (M) and Evening (E) neurons control locomotor activity at the respective time of day during normal day/night (LD) cycles. Recent reports point to a certain degree of plasticity with regard to circadian clock neuron function, depending on specific environmental conditions. Here we show that one neuronal group, the E-neurons, instead behave as if hard-wired to their output targets. Surprisingly they direct activity to occur during the evening both under LD conditions, as well as during temperature cycles in constant light.

Temperature, rainfall, and moonlight intensity effects on activity of tropical insectivorous bats

The extrinsic factors that most influence animal activity are weather and light conditions, which can be assessed at hourly, monthly, and even lunar-cycle timescales. We evaluated the responses of tropical aerial-insectivorous bats to temperature, rainfall, and moonlight intensity within and among nights. Temperature positively affected the activity of two species (Cormura brevirostris and Saccopteryx bilineata). Moonlight reduced Myotis riparius activity and increased the activity of Pteronotus rubiginosus and S. leptura. Rainfall can promote an irregular activity peak during the night compared to nights without rainfall, but the bats in our study were not active for a longer time after a rainfall event. Our findings indicate that moonlight and temperature are the variables with the highest impact on the activity of tropical insectivorous bat species and that some species are sensitive to small variations in rainfall among and within nights.

A model for the regulation of the timing of cell division by the circadian clock in the cyanobacterium Synechococcus elongatus

1SummaryCells of the cyanobacterium Synechococcus elongatus possess a circadian clock in the form of three core clock proteins (the Kai proteins) whose concentrations and phosphorylation states oscillate with daily periodicity under constant conditions [1]. The circadian clock regulates the cell cycle such that the timing of cell divisions is biased towards certain times during the circadian period [2, 3, 4, 5], but the mechanism underlying how the clock regulates division timing remains unclear. Here, we propose a mechanism in which a protein limiting for division accumulates at a rate proportional to cell volume growth and modulated by the clock. This “modulated rates” model, in which the clock signal is integrated over time to affect division timing, differs fundamentally from the previously proposed “gating” concept, in which the clock is assumed to suppress divisions during a specific time window [2, 3]. We found that while both models can capture the single-cell statistics of division timing in S. elongatus, only the modulated rates model robustly places divisions away from darkness during changes in the environment. Moreover, within the framework of the modulated rates model, existing experiments on S. elongatus are consistent with the simple mechanism that division timing is regulated by the accumulation of a division limiting protein in phase with genes whose activity peak at dusk.