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Microalgae are the largest CO 2 fixer and O 2 producer on the earth and occupy an increasingly important position in human life and production. Various environmental factors have a significant impact on the growth and metabolism of microalgae. As global warming intensifies, heat stress has become a crucial factor affecting the microalgae industry. However, till now, it has not been clear how microalgae sensed the temperature stress, transmitted stress signals and adjusted in intracellular metabolic pathways. In this study, the growth of microalgae Auxenochlorella protothecoides UTEX2341 was inhibited at 32 °C, but the single cell dry weight increased. The cell component analyses showed that both the carbohydrate and total protein content decreased significantly, while the lipid content increased by 158%. Meanwhile, the intracellular Ca2+ concentration increased continuously, with a maximum increase of 1.65 times. According to the transcriptome analyses, the up-regulation of Ca2+ influx channel protein mid1-complementing activity 1 (MCA1) gene and the down-regulation of efflux channel protein cation exchanger 1(CAX) and autoinhibited Ca2+-ATPase 1 (ACA1) genes in cytoplasmic membrane jointly facilitated the increase of Ca2+ in the cytoplasm. Coexpression network analysis indicated that the fluctuation of Ca2+ in the cytoplasm could activate the expression of transcription factors MYB3 and AP2-4 through calmodulin (CAM) and calcium-dependent protein kinase (CDPK), and then regulate glycerol-3-phosphate acyltransferases (GPAT) at the beginning of TAG synthesis and diacylglycerol acyltransferase (DGAT)/phospholipid: diacylglycerol acyltransferase (PDAT) in the last step of TAG synthesis. Furthermore, the addition of Ca2+ specific chelator BAPTA-AM inhibited the expression of GPAT , which was consistent with the decrease in microalgae lipid content. The results proved that Ca2+ participated in the regulation of microalgae TAG synthesis under heat stress, which provided a new view for the understanding of the microalgae lipid accumulation mechanism. [Display omitted] • Heat stress was transmitted to microalgae through Ca2+. • MCA1 channel protein was the valve of Ca2+ influx under heat stress. • Ca2+ influx was the internal cause of the TAG accumulation increase. [ABSTRACT FROM AUTHOR]

Most widely studied Structural Health Monitoring methods need baseline data from the undamaged state and a high number of sensors attached to the structure, which makes these methods difficult to be applied in real structures for on-line monitoring. In order to deal with that, the NOde DISplacement (NODIS) method is proposed by considering the structural damage indicator. The idea of the present work is to develop a baseline-free damage location and quantification method based on the node displacement of structural mode shapes. The damage location procedure is developed by combining the nodes from different mode shapes and the damage quantification is achieved by the proposed Transfer-Function-based Damage Indicator (TFDI). The advantages of this method are: (1) baseline-free, in terms of the comparison with a reference signal is not needed, (2) only a relatively small number of sensors is required for real-time damage location and (3) with the proposed TFDI, the damage detection result can be quantified. In the present paper, the baseline-free damage location algorithm is proposed and validated on a steel beam with an analytical model, a numerical model and experiments. In addition, the influence of temperature, the additional weight of the sensor and the error in sensor location on the NODIS method are studied. After that, the TFDI is developed and improved for the experiment. Finally, the method is applied to a supporting structure of a sailplane under complex boundary condition and different environmental temperatures. [ABSTRACT FROM AUTHOR]

Temperature is a crucial factor affecting microalgae CO 2 capture and utilization. However, an in-depth understanding of how microalgae respond to temperature stress is still unclear. In particular, the regulation mechanism under opposite temperature (heat and cold) stress had not yet been reported. In this study, the physicochemical properties and transcription level of related genes of microalgae Auxenochlorella protothecoides UTEX 2341 under heat and cold stress were investigated. Heat stress (Hs) caused a drastic increase of reactive oxygen species (ROS) in UTEX 2341. As key elements responded to Hs, superoxide dismutase (SOD) enzyme increased by 150%, 70%, and 30% in activity, and nitric oxide (NO) grew by 409.6%, 212.5%, and 990.4% in content compared with the control at 48 h, 96 h, 168 h. Under cold stress (Cs), ROS increased in the early stage and decreased in the later stage. As key factors responded to Cs, proline (Pro) increased respectively by 285%, 383%, and 81% in content, and heat shock transcriptional factor HSFA1d increased respectively by 161%, 71%, and 204% in transcript level compared with the control at 48 h, 96 h, 168 h. Furthermore, the transcript level of antioxidant enzymes or antioxidant coding genes was consistent with the changing trend of enzymes activity or antioxidant content. Notably, both glutathione (GSH) and heat shock protein 97 (hsp 97) were up-regulated in response to Hs and Cs. In conclusion, GSH and hsp 97 were the core elements of UTEX 2341 in response to both Hs and Cs. SOD and NO were the key elements that responded to Hs, while proline and HSFA1d were the key elements that responded to Cs. This study provided a basis for the understanding of the response mechanism of microalgae under temperature stress and the improvement of the microalgae tolerance to temperature stress. • Glutathione and hsp 97 were the core factors in algae responded to temperature stress. • Proline and HSFA1d were the key factors in algae responded to cold stress. • SOD and NO were the key factors in algae responded to heat stress. • A suggested working model of microalgae for cold/heat-resistance was constructed. [ABSTRACT FROM AUTHOR]

In recent years, yak milk has received widespread attention due to its high nutrition, green and pollution-free characteristics, but the source of yak milk flavor is still unclear. In this study, fresh yak manure collected from Lhasa, Nagqu, Qamdo, Yushu, and Qinghai Lake were sequenced by 16S rRNA gene high-throughput sequencing technology. The correlation between intestinal microbiota and yak milk quality combined with the local environmental factors was evaluated for the first time. The enterotype of yaks from Lhasa, Nagqu, and Qinghai Lake was classified as enterotype of norank_f_Oscillospirales_UCG-010 and Rikenellaceae_ RC9_gut_group , and the enterotype of yaks from Qamdo and Yushu was classified as enterotype of Oscillospiraceae UCG-005. Procrustes analysis showed that there was a close relationship between yak milk composition and intestinal microbiota. Metabolic pathway analysis found that different genera and key enzymes of methane and short-chain fatty acid metabolic pathways differed in their responses to environmental factors. Based on the above analysis, a model about environmental factors, intestinal bacteria and the flavor of yak milk was developed. The results provided a reference for the study of flavor substances in yak milk and a new direction for the improvement of dairy products and their derivatives. • The yak gut microbial diversity of southeastern Tibet-Qinghai Plateau is studied. • The yak is divided into Enterotype 1 and Enterotype 2 according to its gut microbes. • Stable enterotype is the basis for the function of different genera in the gut. • Yak milk flavor is closely related to gut microbes and local environmental factors. • A model based on enterotype to influence the flavor of yak milk is constructed. [ABSTRACT FROM AUTHOR]