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We analyzed the supply and demand for tilapia in China while assessing the future developmental trends. China has become the world’s largest producer, exporter, and consumer of tilapia. China entered a period of rapid aquaculture development in the 1990s, and the tilapia supply has increased yearly. Tilapia products are mainly supplied to the international market, especially the US. The global market for the Chinese tilapia has grown dramatically, but a downward trend occurred in 2019–2020. The Chinese domestic market demand is relatively stable, and even the COVID-19 epidemic did not significantly impact the supply and demand of tilapia. Internationally, it is expected that the demand for tilapia will decline considerably in the near future. However, this decline could be alleviated after the impact of the COVID-19 epidemic passes and increasing demand will resume. The increased supply of Chinese tilapia might slow down or even decrease due to market uncertainty, the increasing constraints on natural resources, and the Chinese government’s requirements for high-quality aquaculture environments.

Quorum sensing (QS) is a microbial cell–cell communication mechanism and plays an important role in bacterial infections. QS-mediated bacterial infections can be blocked through quorum quenching (QQ), which hampers signal accumulation, recognition, and communication. The pathogenicity of numerous bacteria, including Xanthomonas campestris pv. campestris (Xcc), is regulated by diffusible signal factor (DSF), a well-known fatty acid signaling molecule of QS. Cupriavidus pinatubonensis HN-2 could substantially attenuate the infection of XCC through QQ by degrading DSF. The QQ mechanism in strain HN-2, on the other hand, is yet to be known. To understand the molecular mechanism of QQ in strain HN-2, we used whole-genome sequencing and comparative genomics studies. We discovered that the fadT gene encodes acyl-CoA dehydrogenase as a novel QQ enzyme. The results of site-directed mutagenesis demonstrated the requirement of fadT gene for DSF degradation in strain HN-2. Purified FadT exhibited high enzymatic activity and outstanding stability over a broad pH and temperature range with maximal activity at pH 7.0 and 35 °C. No cofactors were required for FadT enzyme activity. The enzyme showed a strong ability to degrade DSF. Furthermore, the expression of fadT in Xcc results in a significant reduction in the pathogenicity in host plants, such as Chinese cabbage, radish, and pakchoi. Taken together, our results identified a novel DSF-degrading enzyme, FadT, in C. pinatubonensis HN-2, which suggests its potential use in the biological control of DSF-mediated pathogens.

The development of marine water quality criteria (WQC) in China has been insufficient because data on the toxicity of pollutants for marine organisms based on the species sensitivity distribution (SSD) method are lacking. The Chinese aquatic environmental quality standards, including those for seawater, were derived from the developed countries. Therefore, establishing Chinese marine WQC is crucial for identifying the sensitivity of marine species in China and will improve their protection from threats. Mercury (Hg) is one of the primary pollutants commonly exceeding Chinese seawater quality standards. Several countries have developed their marine WQC for inorganic Hg in the past decades, but no study has been conducted in China. In this study, 45 acute toxicity and 14 chronic toxicity data of inorganic Hg on the marine species which inhabit in China were obtained mainly from the ECOTOX database, the CNKI, and the Google Scholar. The acute and chronic hazardous concentrations for 5% of the species (HC5) were calculated based on the best-fit distribution model Sweibull. The criteria for maximum and continuous concentrations of 1.30 and 0.66 μg/L, respectively, for inorganic Hg to protect marine organisms in China were derived by halving the HC5 values. The criteria were comparable to those of the United States, Australia, and the European Union countries, indicating the general applicability of WQCs developed based on the classical SSD method using different species groups. This study may provide valuable information for assessing marine ecological risk in China.

The diffusible signal factor (DSF) is a fatty acid signal molecule and is widely conserved in various Gram-negative bacteria. DSF is involved in the regulation of pathogenic virulence in many bacterial pathogens, including Xanthomonas campestris pv. campestris (Xcc). Quorum quenching (QQ) is a potential approach for preventing and controlling DSF-mediated bacterial infections by the degradation of the DSF signal. Acinetobacter lactucae strain QL-1 possesses a superb DSF degradation ability and effectively attenuates Xcc virulence through QQ. However, the QQ mechanisms in strain QL-1 are still unknown. In the present study, whole-genome sequencing and comparative genomics analysis were conducted to identify the molecular mechanisms of QQ in strain QL-1. We found that the fadY gene of QL-1 is an ortholog of XccrpfB, a known DSF degradation gene, suggesting that strain QL-1 is capable of inactivating DSF by QQ enzymes. The results of site-directed mutagenesis indicated that fadY is required for strain QL-1 to degrade DSF. The determination of FadY activity in vitro revealed that the fatty acyl-CoA synthetase FadY had remarkable catalytic activity. Furthermore, the expression of fadY in transformed Xcc strain XC1 was investigated and shown to significantly attenuate bacterial pathogenicity on host plants, such as Chinese cabbage and radish. This is the first report demonstrating a DSF degradation enzyme from A. lactucae. Taken together, these findings shed light on the QQ mechanisms of A. lactucae strain QL-1, and provide useful enzymes and related genes for the biocontrol of infectious diseases caused by DSF-dependent bacterial pathogens.

Diffusible signal factor (DSF) represents a family of widely conserved quorum sensing (QS) signals involved in the regulation of virulence factor production in many Gram-negative bacterial pathogens. Quorum quenching, which disrupts QS either by degradation of QS signals or interference of signal generation or perception, is a promising strategy for prevention and control of QS-mediated bacterial infections. In this study, a novel DSF-degrading strain, HN-2, was isolated from contaminated soil and identified as Cupriavidus sp. The isolate exhibited superior DSF degradation activity and completely degraded 2 mmol&middot, L&ndash, 1 of DSF within 24 h. Analysis of the degradation products of DSF by gas chromatography&ndash, mass spectrometry led to the identification of trans-2-decenoic acid methyl ester as the main intermediate product, suggesting that DSF could be degraded by oxidation and hydroxylation. Moreover, this study presents for the first time, evidence that Cupriavidus sp. can reduce the black rot disease caused by Xanthomonas campestris pv. campestris (Xcc). Application of the HN-2 strain as a biocontrol agent could substantially reduce the disease severity. These findings reveal the biochemical basis of a highly efficient DSF-degrading bacterial isolate and present a useful agent for controlling infectious diseases caused by DSF-dependent bacterial pathogens.

Concentrations of the heavy metals As, Cd, Cu, Hg, Pb, and Zn in various tissues of five marine fish species and one crab species collected from the middle coast of Zhejiang Province of China were investigated in this study. The results indicated considerable variation in heavy metal concentrations in different tissues and species. Elevated concentrations of most heavy metals were identified in fish gills and crab gills and hepatopancreas, with some differences by heavy metal type. In addition, carnivorous and benthivorous fish species generally contained relatively high concentrations of heavy metals due to feeding habits and habitats. Geographical variations of heavy metal concentrations in muscle may be attributable to species-dependent differences and terrigenous contamination. The potential health risk assessment suggested that exposure doses of most heavy metals were safe for human consumption, with the exception of As.

Diffusible signal factor (DSF) is a type of cis unsaturated fatty acid, with a chemical structure of 11-methyl-2-dodecylene acid. DSF is widely conserved in a variety of Gram-negative bacterial pathogens and is involved in the regulation of pathogenic virulence. Quorum quenching (QQ) is a promising strategy for preventing and controlling quorum sensing (QS)-mediated bacterial infections by interfering with the QS system of pathogens. In this study, a novel DSF-degrading bacterium, Burkholderia anthina strain HN-8, was isolated and characterized for its degradation ability and potential biocontrol of black rot disease caused by Xanthomonas campestris pv. campestris (Xcc). The HN-8 strain exhibited superb DSF degradation activity and completely degraded 2 mM DSF within 48 h. In addition, we present the first evidence of bacterium having a metabolic pathway for the complete degradation and metabolism of DSF. Analysis of DSF metabolic products by gas chromatography&ndash, mass spectrometry led to the identification of dodecanal as the main intermediate product, revealing that DSF could be degraded via oxidation&ndash, reduction. Furthermore, application of strain HN-8 as a potent biocontrol agent was able to significantly reduce the severity of black rot disease in radishes and Chinese cabbage. Taken together, these results shed light on the QQ mechanisms of DSF, and they provide useful information showing the potential for the biocontrol of infectious diseases caused by DSF-dependent bacterial pathogens.

Bioremediation technologies have strong potential use in the less costly and more environmentally friendly removal of highly toxic hexavalent-chromium (Cr(VI)) compared with physicochemical technologies. Several Cr(VI)-reducing bacteria have been isolated; however, there are few studies on Cr(VI)-resistant and Cr(VI)-reducing actinomycetes. In this study, Cr(VI)-reducing actinomycetes were screened from estuarine, marine, and terrestrial samples on the basis of Cr(VI)-resistant and Cr(VI)-reducing ability. Of the 80 Streptomyces-like strains isolated, 20 strains were found to be resistant to 50 mg/l of Cr(VI). In addition, two strains isolated from the estuarine sediment of Tokyo Bay were found to be resistant to a concentration of 150 mg/l of Cr(VI). Furthermore, one Cr(VI)-reducing strain was found to remove 60 mg/l of Cr(VI) within 1 week and was identified as Streptomyces thermocarboxydus based on 16S rRNA gene analysis. The comparative evaluation with the type strain S. thermocarboxydus NBRC 16323 showed that our isolated strain had higher ability to grow at 27 °C and reduce Cr(VI) at a NaCl concentration of 6.0 % at 27 °C compared with the type strain NBRC 16323. These results indicate that our isolated strain have a potential ability to remove Cr(VI) from contaminated, highly saline sources without heating.

This paper studies a Non-convex State-dependent Linear Quadratic Regulator (NSLQR) problem, in which the control penalty weighting matrix [Formula: see text] in the performance index is state-dependent. A necessary and sufficient condition for the optimal solution is established with a rigorous proof by Euler-Lagrange Equation. It is found that the optimal solution of the NSLQR problem can be obtained by solving a Pseudo-Differential-Riccati-Equation (PDRE) simultaneously with the closed-loop system equation. A Comparison Theorem for the PDRE is given to facilitate solution methods for the PDRE. A linear time-variant system is employed as an example in simulation to verify the proposed optimal solution. As a non-trivial application, a goal pursuit process in psychology is modeled as a NSLQR problem and two typical goal pursuit behaviors found in human and animals are reproduced using different control weighting [Formula: see text]. It is found that these two behaviors save control energy and cause less stress over Conventional Control Behavior typified by the LQR control with a constant control weighting [Formula: see text], in situations where only the goal discrepancy at the terminal time is of concern, such as in Marathon races and target hitting missions.

A biopsychically inspired integrated cognitive control system architecture for autonomous agents is proposed in this paper, whose hardware is modeled after the biological Central Nervous System (CNS) of human's, and algorithms are modeled after human psychological processes. The pain-driven system architecture and motivated learning algorithms allow the agent to set goals autonomously so as not only to survive but also thrive in uncertain or unknown environment and they endow the agent with the ability of improvisation, innovation and imagination. Familiar concepts in control engineering will be reexamined in the context of human cognition and psychological behaviors. The control law for decision making derived from psychological process is exemplified with case studies of three psychological behaviors by the method of Linear Quadratic Regulator (LQR) with a state-dependent quadratic loss function. This paper is mainly an inquiry outside of the box of conventional control paradigms; therefore it provides more questions than answers.

The current state-of-the-art machine intelligence cannot meet the challenges of uncertainty, complexity, time urgency and rapidly changing nature of the dynamic environment in many demanding aerospace applications, such as autonomous extraterrestrial exploration. A biopsychically inspired cognitive system is proposed based on the biological Central Nervous System architecture. The main cognitive units, Decision Making and Planning, Motivation & Learning and Long-term Memory are explained in detail. The algorithms derived from the Central Nervous System and former works on motivated learning are shown for motivation, memory, attention switching, decision making, and planning together with obtained simulation results. The proposed cognitive system can be used for intelligent agents for autonomous scientific exploration, as well as in agriculture, rescue and military applications or as a basis for cooperative groups.

This article designs a cooperative mission management system (CMMS) architecture for a multi-agent team using the integrated method, which units the control center subsystem for the team mission assignment and the onboard management subsystem for the sole autonomous management in an effective way. The proposed “distributed architecture under the distributed center-control” distributes the control center subsystem on the ground station and the leading agent, whereas the onboard management subsystem on team members, assigning the system workload among the ground station and the agents logically. In this way, this architecture ensures the team's flexibility and the system's reliability. The designed onboard management subsystem, based on the concept of “operating system,” offers high level of autonomy and separates the specific dynamic characteristics of agents from the users by the way of hierarchism control so that the system can be used generally for a heterogeneous group of agents. The system's modularization makes the system easier for function expansion and upgrading in the near future. The system is simulated on the test bed consisting of the Labview and the C language. And the results show that the designed system can satisfy the requirements of a multi-agent team cooperative mission management fully.

Efflux of water from plant roots has implications for nutrient uptake in dry soil, the effectiveness of collection of water from deep in the soil, water parasitism among plants, and the ability of roots to resume water uptake after exposure to dry soil. We measured the minimum soil water potential required for reverse flow in sorghum [Sorghum bicolor (L.) Moench], the diurnal time-course of the efflux, and differences between sorghum genotypes in reverse flow. A splitroot system was used in which near-surface roots were subjected to drying and deeper roots were in free water. Efflux of water to the dry soil could first be detected at a soil water potential of about -0.55 MPa, or across a soil water potential gradient of 0.55 MPa, a smaller value than previously reported to induce reverse flow [...]

This article discussed an algorithm for the Micromouse Competition, which is an international event in the field of artificial intelligence and is held by the International Institute of Electrical and Electronics Engineering (IEEE) every year. The discussion proposed “dead-end exclusion algorithm” to exclude one-line dead-end and “osmosis algorithm” to exclude dead-zone of any shape. The two improved algorithms were demonstrated in practical testing and competition. The key idea of the improved algorithms was to exclude dead-zone which did not contain the shortest path basing the obtained information. In this article, “osmosis idea” was used in maze algorithm for the first time, which realized the judgment and exclusion of the dead-zone effectively. Compared with classical algorithms, these improved algorithms had better temporal and spatial optimization result.

In order to overcome the shortage that RTEMS lacks effective software fault-tolerant mechanism, this paper proposes an approach to add a task fault-tolerant module into application service layer. Based on the task scheduling algorithm of RTEMS, the proposed approach achieves fault-tolerant function by arranging the rescheduling time of fault tasks, which can recover the tasks from transient faults and degrade the system when permanent faults happen. The validity of this proposed approach applied to RTEMS is verified in Markov analyzing theoretically and case study.

The article described the real-time measuring and control subsystem (MCS) of a certain actuation system briefly first. According to the structure and the specific developing requirements for the subsystem, the article gave the software design thinking based on Labview and 1553B communication standard. The article then introduced the design guidelines, software structures and design details specifically. By the actuation system application, the software was proved to satisfy the application requirements fully.