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Abstract Fish dietary niche is a core focus, and it reflects the diversity of resources, habitats, or environments occupied by a species. However, whether geographic segregation among different populations triggers dietary diversification and concomitant fish niche shift remains unknown. In the present study, we selected the Black Amur bream (Megalobrama terminalis) is a migratory fish species that plays an important role in the material transfer and energy cycling of river ecosystems, inhabiting southern China drainage with multiple geographic populations. Here, we utilized the combined analyses of 18S rDNA high‐throughput sequencing in fish gut contents and fatty acid (FA) in muscle tissues to evaluate potential spatial patterns of habitat and resource use for M. terminalis in three rivers of southern China. Our results showed that prey items of the Xijiang (XR) population (Pearl River) exhibited the highest species diversity and richness among the three geographic populations. Moreover, diet composition of M. terminalis was affected by spatial differences associated with geographic segregation. Analyses of FA biomarkers indicated that the highest levels of C16:0, C18:3n‐3, and C18:2n‐6c were found in Wanquan (WS) population (Wanquan River). The XR population exhibited a distinct FA profile characterized by higher amounts of arachidonic acid (ARA) and docosahexaenoic acid (DHA). The Moyang (MY) population (Moyang River) acted as the linkage between WS and XR populations and consisted of middle levels of saturated FAs (SFAs) and polyunsaturated FAs (PUFAs). The XR population displayed a greater FA niche width compared with WS population. Furthermore, we observed a close positive relationship between the niche width and α‐diversity indices of dietary resources for FA proflies. Our study provides valued information to develop different conservation strategies among different populations and improve fisheries management for M. terminalis and other endemic species in local rivers.

Abstract When manually polishing blades, skilled workers can quickly machine a blade by observing the characteristics of the polishing sparks. To help workers better recognize spark images, we used an industrial charge-coupled device (CCD) camera to capture the spark images. Firstly, the spark image region detected by yolo5, then segment from the background. Secondly, the target region was further segmented and refined in a fully connected conditional random field (CRF), from which the complete spark image obtained. Experimental results showed that this method could quickly and accurately segment whole spark image. The test results showed that this method was better than other image segmentation algorithms. Our method could better segment irregular image, improve recognition and segmentation efficiency of spark image, achieve automatic image segmentation, and replace human observation.

Abstract Excitons in monolayer semiconductors, benefitting from their large binding energies, hold great potential towards excitonic circuits bridging nano-electronics and photonics. However, achieving room-temperature ultrafast on-chip electrical modulation of excitonic distribution and flow in monolayer semiconductors is nontrivial. Here, utilizing lateral bias, we report high-speed electrical modulation of the excitonic distribution in a monolayer semiconductor junction at room temperature. The alternating charge trapping/detrapping at the two monolayer/electrode interfaces induces a non-uniform carrier distribution, leading to controlled in-plane spatial variations of excitonic populations, and mimicking a bias-driven excitonic flow. This modulation increases with the bias amplitude and eventually saturates, relating to the energetic distribution of trap density of states. The switching time of the modulation is down to 5 ns, enabling high-speed excitonic devices. Our findings reveal the trap-assisted exciton engineering in monolayer semiconductors and offer great opportunities for future two-dimensional excitonic devices and circuits.

Chinese mitten crab (Eriocheir sinensis) belongs to Decapoda, Grapsidae and Eriocheir. It is also known as river crab and hairy crab and is widely distributed in the coastal waters of China and has important economic benefits. Salinity is the key environmental factor affecting the mating and spawning of E. sinensis. Presently, reports on the effects of salinity on crabs focus on osmotic pressure regulation, nutritional and energy metabolism, molting, and sexual precocity. However, the effects of salinity on the related hormones in the hemolymph before and after mating and spawning of E. sinensis have not been reported. Relevant steroid hormones include progesterone, 17α-dihydroxyprogesterone, 20β-dihydroxyprogesterone, and 17α-20β-dihydroxyprogesterone (DHP) and most effectively induce maturation of salmon and trout eggs, which has been confirmed in a variety of fish. Early studies have shown that the ovulation activity of fish is closely related to the level of gonadotropin (GTH) in the blood. The gonadotropin releasing hormone receptor (GnRHR) in E. sinensis indicate that the ovarian maturation and reproductive regulation in crustaceans are regulated by some gonadotropins, such as methylfarnesol and ecdysone. PGE, PGF, and prostacyclin (PGI2) can promote ovulation in a variety of fish and crustaceans. Like vertebrates, steroids are important hormones that affect the ovarian development of shrimp and crab, such as estradiol (E2), testosterone (T), and progesterone. Steroids can impact gonadal development and play a very important role in ovarian development and vitellogenesis. However, these hormones are restricted by a variety of environmental factors, such as temperature, light, salinity, and so on. In order to investigate the effect of salinity on hemolymph related hormones during mating and spawning of E. sinensis, the spawning salinity was set at 0, 2, 4, 6 and mating salinity set at 3, 6, 9, 12, 15, 18, 21. Five samples were collected from specimens in each salinity to analyze the contents of DHP, GTH, PG, E2, and testosterone in the hemolymph of female E. sinensis before and after mating and spawning under different mating and spawning salinities. The components were detected by ELISA at the wavelength of 450 nm using the kit double antibody sandwich method. Results revealed: (1) in fresh water, female crabs displayed no mating behavior. When the salinity was lower than 6, female crabs only mated without spawning. (2) There were no significant changes in PG, E2, or testosterone in the hemolymph of female crabs after mating in low salinity (2–6), and there was no significant difference between crabs at different salinities after mating (P > 0.05). (3) The contents of DHP, PG, E2, and testosterone in the hemolymph of female crabs initially decreased and then increased with salinity before spawning. After spawning, DHP, PG, and E2 in hemolymph initially increased and then decreased with increased salinity. When the salinity was 18, DHP, PG, E2, and testosterone in the hemolymph of the female crab after spawning decreased to the lowest level, and there was a significant difference between the before and after spawning results (P < 0.05). (4) At 6 salinity, the contents of DHP, PG, E2, and testosterone in the hemolymph of female crabs before spawning were the highest and the contents of DHP and PG decreased after spawning, while the contents of E2 and testosterone increased. However, there was only significant variation in the DHP from before spawning to after spawning (P < 0.05), and there was no significant difference in the other indexes (P > 0.05). The content of testosterone in the hemolymph initially decreased and then increased before and after spawning. This comprehensive study showed that salinity effects the five hormones in the hemolymph of female E. sinensis during the reproductive and breeding stage. Among them, the five hormones do not change significantly during the mating process of E. sinensis. DHP, GTH, and PG are involved in the oviposition of E. sinensis. The analyses of the changes in the related hormones in the hemolymph of female E. sinensis before and after mating and spawning at different salinities have identified changes in the neutral hormones. These results provide details on the reproductive regulation mechanism of E. sinensis and provided basic reference data for researching the reproductive biology of E. sinensis.

Abstract Cell adhesion molecule (CAM) is an umbrella term for several families of molecules, including the cadherin family, integrin family, selectin family, immunoglobulin superfamily, and some currently unclassified adhesion molecules. Extracellular vesicles (EVs) are important information mediators in cell-to-cell communication. Recent evidence has confirmed that CAMs transported by EVs interact with recipient cells to influence EV distribution in vivo and regulate multiple cellular processes. This review focuses on the loading of CAMs onto EVs, the roles of CAMs in regulating EV distribution, and the known and possible mechanisms of these actions. Moreover, herein, we summarize the impacts of CAMs transported by EVs to the tumour microenvironment (TME) on the malignant behaviour of tumour cells (proliferation, metastasis, immune escape, and so on). In addition, from the standpoint of clinical applications, the significance and challenges of using of EV-CAMs in the diagnosis and therapy of tumours are discussed. Finally, considering recent advances in the understanding of EV-CAMs, we outline significant challenges in this field that require urgent attention to advance research and promote the clinical applications of EV-CAMs. Video Abstract

To understand the fish community structure characteristics and changes in Poyang Lake after the Yangtze River fishing ban in 2021, seven sampling stations were established, namely in Hukou, Lushan, Duchang, Yongxiu, Nanjishan, Ruihong, and Poyang, for fishery resource surveys between 2020 and 2021. The results showed that 93 fish species were identified, belonging to 11 orders, 20 families, and 61 genera, which was an increase of 4.5% from before the fishing ban. Of these, 52 Cyprinidae species were identified, comprising the highest proportion (55.91%). Four invasive alien species (hybrid sturgeon, Cirrhina mrigala, Piaractus brachypomus, and Mugil cephalus) were identified, and the number of alien species in Poyang Lake was higher than before the fishing ban. Carnivorous and mid-lower-level fish showed a significant increase, accounting for 47.31% and 38.71% of the total species, respectively. Compared with the Yangtze River before the fishing ban, the body length and body weight of the main economic fish in Poyang Lake increased by 6.10–61.26% and by 15.14–291.57%, respectively. In terms of age structure, the proportion of major economically important fish aged 1 or 2 years decreased significantly, while the proportion of older fish increased substantially. There was little difference in the diversity of fish communities at different stations in Poyang Lake. In terms of biodiversity, the Shannon–Wiener index ranged from 2.158 to 2.909, with Poyang having the highest value and Nanjishan the lowest. Margalef’s index ranged from 4.265 to 6.459, with Lushan having the highest value and Nanjishan the lowest. Pielou’s index ranged from 0.617 to 0.822, with Duchang having the highest value and Nanjishan the lowest. Hence, the Yangtze river fishing ban has played an important and positive role in the restoration of fishery resources in Poyang Lake. However, long-term tracking and monitoring are needed to provide information to comprehensively evaluate the ecological impact of the Poyang Lake fishing ban.

The short message function of the BeiDou satellite system, due to its strong concurrent processing capabilities, can quickly and accurately send information to the target location in emergency situations. However, because of data redundancy and limitations on message length, a single piece of information often requires multiple transmissions through BeiDou short messages to be completed, resulting in limited transmission capacity. To improve the transmission capacity of information, it is necessary to compress the information during transmission using BeiDou’s short message communication function for maritime safety information. This paper proposes a Byte Encoding-enhanced Prediction by Partial Matching, variant D (BPPMd) algorithm that is particularly suitable for transmitting maritime safety information. Combined with a maritime safety information encoding algorithm (ME), it further improves compression efficiency, optimizes byte space, reduces information redundancy, and ensures the accuracy of the information. In this study, we constructed a maritime safety information dataset that includes three categories of information: meteorological warnings, navigation warnings, and disaster warnings. Experimental results show that the proposed algorithm is particularly suitable for compressing the maritime safety information dataset and outperforms other benchmark algorithms. Therefore, this study indicates that the proposed lossless compression method can be a feasible and effective solution for BeiDou short message communication.