Amplitude of circadian rhythms becomes weaken in the north, but there is no cline in the period of rhythm in a beetle

Many species show rhythmicity in activity, from the timing of flowering in plants to that of foraging behavior in animals. The free-running periods and amplitude (sometimes called strength or power) of circadian rhythms are often used as indicators of biological clocks. Many reports have shown that these traits are highly geographically variable, and interestingly, they often show latitudinal or longitudinal clines. In many cases, the higher the latitude is, the longer the free-running circadian period (i.e., period of rhythm) in insects and plants. However, reports of positive correlations between latitude or longitude and circadian rhythm traits, including free-running periods, the power of the rhythm and locomotor activity, are limited to certain taxonomic groups. Therefore, we collected a cosmopolitan stored-product pest species, the red flour beetle Tribolium castaneum, in various parts of Japan and examined its rhythm traits, including the power and period of the rhythm, which were calculated from locomotor activity. The analysis revealed that the power was significantly lower for beetles collected in northern areas than southern areas in Japan. However, it is worth noting that the period of circadian rhythm did not show any clines; specifically, it did not vary among the sampling sites, despite the very large sample size (n = 1585). We discuss why these cline trends were observed in T. castaneum

Genetic variation and phenotypic plasticity in circadian rhythms in an armed beetle, Gnatocerus cornutus (Tenebrionidae)

Circadian rhythms, their free-running periods and the power of the rhythms are often used as indicators of biological clocks, and there is evidence that the free-running periods of circadian rhythms are not affected by environmental factors, such as temperature. However, there are few studies of environmental effects on the power of the rhythms, and it is not clear whether temperature compensation is universal. Additionally, genetic variation and phenotypic plasticity in biological clocks are important for understanding the evolution of biological rhythms, but genetic and plastic effects are rarely investigated. Here, we used 18 isofemale lines (genotypes) of Gnatocerus cornutus to assess rhythms of locomotor activity, while also testing for temperature effects. We found that total activity and the power of the circadian rhythm were affected by interactions between sex and genotype or between sex, genotype and temperature. The males tended to be more active and showed greater increases in activity, but this effect varied across both genotypes and temperatures. The period of activity varied only by genotype and was thus independent of temperature. The complicated genotype–sex–environment interactions we recorded stress the importance of investigating circadian activity in more integrated ways

Giant multiple caloric effects in charge transition ferrimagnet

磁場と圧力でマルチに冷却可能な酸化物新材料 --フェリ磁性電荷転移酸化物におけるマルチ熱量効果の実証--. 京都大学プレスリリース. 2021-06-22.Caloric effects of solids can provide us with innovative refrigeration systems more efficient and environment-friendly than the widely-used conventional vapor-compression cooling systems. Exploring novel caloric materials is challenging but critically important in developing future technologies. Here we discovered that the quadruple perovskite structure ferrimagnet BiCu₃Cr₄O₁₂ shows large multiple caloric effects at the first-order charge transition occurring around 190 K. Large latent heat and the corresponding isothermal entropy change, 28.2 J K⁻¹ kg⁻¹, can be utilized by applying both magnetic fields (a magnetocaloric effect) and pressure (a barocaloric effect). Adiabatic temperature changes reach 3.9 K for the 50 kOe magnetic field and 4.8 K for the 4.9 kbar pressure, and thus highly efficient thermal controls are achieved in multiple ways

Comparable benefits of land sparing and sharing indicated by bird responses to stand-level plantation intensity in Hokkaido, northern Japan

We examined potentially contrasting conservation benefits of land sparing (land-use specialization) and land sharing (multiple-use forestry) strategies in forested landscapes by investigating relationships between bird functional group densities and basal areas of coniferous trees (an index of plantation intensity) in Sakhalin fir (Abies sachalinensis) and Sakhalin spruce (Picea glehnii) plantations. Densities of most bird functional groups increased with decreasing plantation intensity in both plantation types. In many cases, linear models were best for descriptors of bird density-plantation intensity relationships, but statistical support of linear and nonlinear (quadratic) models was similar. This outcome indicates that ecological benefits of land sparing and land sharing are potentially comparable in the plantations we studied. In real landscapes, land-use decision making depends on a variety of factors other than biodiversity conservation (e.g., social and biophysical factors). Furthermore, niche theory also predicts that population densities could linearly respond to environmental gradients. When density-intensity relationships are linear, as in this study, land-sparing and land-sharing strategies provide similar benefits in terms of biodiversity conservation, and contrasting land-use strategies could be flexibly chosen to enhance the accommodation of biodiversity conservation to resource production

Unsupervised Speech Enhancement Based on Multichannel NMF-Informed Beamforming for Noise-Robust Automatic Speech Recognition

This paper describes multichannel speech enhancement for improving automatic speech recognition (ASR) in noisy environments. Recently, the minimum variance distortionless response (MVDR) beamforming has widely been used because it works well if the steering vector of speech and the spatial covariance matrix (SCM) of noise are given. To estimating such spatial information, conventional studies take a supervised approach that classifies each time-frequency (TF) bin into noise or speech by training a deep neural network (DNN). The performance of ASR, however, is degraded in an unknown noisy environment. To solve this problem, we take an unsupervised approach that decomposes each TF bin into the sum of speech and noise by using multichannel nonnegative matrix factorization (MNMF). This enables us to accurately estimate the SCMs of speech and noise not from observed noisy mixtures but from separated speech and noise components. In this paper, we propose online MVDR beamforming by effectively initializing and incrementally updating the parameters of MNMF. Another main contribution is to comprehensively investigate the performances of ASR obtained by various types of spatial filters, i.e., time-invariant and variant versions of MVDR beamformers and those of rank-1 and full-rank multichannel Wiener filters, in combination with MNMF. The experimental results showed that the proposed method outperformed the state-of-the-art DNN-based beamforming method in unknown environments that did not match training data

Artificial selections for death-feigning behavior in beetles show correlated responses in amplitude of circadian rhythms, but the period of the rhythm does not

One of the most important survival strategies of organisms is to avoid predators. Studying one of such strategies, namely, death-feigning behavior, has recently become more common. The success or failure of this antipredator strategy will be affected by the circadian rhythms of both prey and predator because death feigning sometimes has a diurnal rhythm. However, few studies have analyzed the effects of differences in circadian rhythms on predator-avoidance behavior at the genetic level. Recently, the relationship between genes relating to circadian rhythm and death-feigning behavior, an antipredator behavior, has been established at the molecular level. Therefore, in this study, we compared three circadian rhythm-related traits, the free-running period of rhythms, amplitude of circadian rhythms, and total activity of strains of three Tribolium species that were artificially selected for the death-feigning duration: short (S-strains) and long (L-strains) durations. As a result, the amplitude of circadian rhythms and total activity were significantly different between S- and L-strains, but there was no difference in the free-running periods of the rhythm between the strains in T. castaneum, T. confusum, and T. freemani. Although the relationship between death-feigning behavior and activity has been reported for all three species, a genetic relationship between the duration of death feigning and the amplitude of circadian rhythms has been newly found in the present study. It is important to investigate the relationship between antipredator strategies and circadian rhythms at the molecular level in the future

Hypoxia imaging agent 64Cu-ATSM visualizes cancer stem cell-rich regions within tumors

Objectives: 64Cu-diacetyl-bis (N4-methylthiosemicarbazone) (64Cu-ATSM) is a PET imaging agent targeting tumor hypoxia. It is known that tumor hypoxia assessed by Cu-ATSM is associated with tumor malignant behavior, such as resistance to therapy and metastasis ability. Recent studies demonstrated that the tumor characteristics of therapeutic resistance and metastasis ability would be attributed to so-called cancer stem cells. Based on these understandings, we hypothesized that tumor hypoxic regions visualized by 64Cu-ATSM would contain higher proportions of cancer stem cells than other tumor regions. In this study, we examined distribution of cancer stem cells within tumors and compared it with accumulations of 64Cu-ATSM and 18FDG. \nMethods: Double-tracer autoradiography and immunohistchemistry was performed with mouse colon carcinoma (Colon-26) tumor-bearing mice. In autoradiography, mixture of 74 MBq of 18FDG and 0.37 MBq of 64Cu-ATSM was i.v. injected. CD133 was used as a cancer stem cell marker, which reflected typical characteristics of cancer stem cells in Colon-26 cells. \nResults: Percentage of CD133+ cells was high in order of 64Cu-ATSM high uptake regions >64Cu-ATSM middle uptake regions > 64Cu-ATSM low uptake regions > 18FDG high uptake regions within Colon-26 tumors. The density of CD133+ cells was 11-fold higher in 64Cu-ATSM high uptake regions than in 18FDG high uptake regions. \nConclusions: 64Cu-ATSM accumulating hypoxic regions matched CD133+ cell-rich regions within Colon-26 tumors. Our findings suggested that 64Cu-ATSM is a potential imaging agent for cancer stem cell-rich regions within tumors.2009 SNM Annual Meetin