BackgroundPlant viruses in agricultural crops are of great concern worldwide, and over 75% of them are transmitted from infected to healthy plants by insect vectors. Tomato yellow leaf curl virus (TYLCV) is a begomovirus, which is the largest and most economically important group of plant viruses, transmitted by the whitefly Bemisia tabaci. The circulation of TYLCV in the insect involves complex insect-virus interactions, whereas the molecular mechanisms of these interactions remain ambiguous. The insect gut as a barrier for viral entry and dissemination is thought to regulate the vector specificity. However, due to its tiny size, information for the responses of whitefly gut to virus infection is limited.MethodsWe investigated the transcriptional response of the gut of B. tabaci Middle East-Asia Minor 1 species to TYLCV infection using Illumina sequencing.ResultsA total of 5207 differentially expressed genes (DEGs) between viruliferous and non-viruliferous whitefly guts were identified. Enrichment analyses showed that cargo receptor and ATP-binding cassette (ABC) transporters were enriched in DEGs, and might help the virus to cross gut barrier. TYLCV could perturb cell cycle and DNA repair as a possible result of its replication in the whitefly. Our data also demonstrated that TYLCV can activate whitefly defense responses, such as antimicrobial peptides. Meanwhile, a number of genes involved in intracellular signaling were activated by TYLCV infection.ConclusionsOur results reveal the complex insect-virus relationship in whitefly gut and provide substantial molecular information for the role of insect midguts in virus transmission.Electronic supplementary materialThe online version of this article (10.1186/s12985-018-0926-6) contains supplementary material, which is available to authorized users.

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Begomoviruses are transmitted by whiteflies in a persistent manner, but factors responsible for the variation of virus transmission by different species are poorly understood. We examined ingestion of papaya leaf curl China virus (PaLCuCNV) and tomato yellow leaf curl virus (TYLCV) by two species of the Bemisia tabaci complex, MEAM1 and MED, and then quantified the virion concentrations in different organs/tissues in each species. We found that PaLCuCNV penetrated the midgut wall of MED less efficiently than MEAM1, resulting in lower efficiency of PalCuCNV transmission by MED than that by MEAM1, while TYLCV penetrated the midgut wall of both species and was transmitted by them at similar levels of efficiency. Virus coat protein determined the virus capacity to cross the midgut wall of a given whitefly species. These data indicate that the level of midgut penetration determines virus acquisition and transmission by whiteflies in the first instance.

Tidal flats and salt marshes connect the land and the ocean by mediating the exchange of water, sediments, and nutrients within coastal landscapes (FitzGerald & Hughes, 2019;Mitsch & Gosselink, 2000;Zedler & Kercher, 2005). Salt marshes are typically covered by halophytic vegetation. They occupy elevations higher than mean sea level (MSL) and are periodically inundated by the tide (Allen, 2000;Friedrichs & Perry, 2001). Conversely, tidal flats lie below mean sea level and hence, are intermittently exposed during low tides (Zhou et al., 2016). They do not host halophytic vegetation, but can be covered by microbial biofilms or colonized by sea grasses, which contribute to stabilize the sediment bed (Chen et al., 2017;Yallop et al., 1994).Depending on the rate of relative sea level rise (RSLR) and sediment availability, tidal flats can evolve into salt marshes and vice versa (Fagherazzi et al., 2006;Marani et al., 2007;Zhou et al., 2016). As the elevation of the intertidal platform increases within the tidal frame, flow conditions become suitable for the settlement of vegetation seeds. The bare surface of tidal flats is thus progressively encroached by vegetation patches, and eventually a salt marsh forms, as a result of the interaction of physical and biological processes (Bouma et al., 2014;Hu et al., 2015). On the contrary, a salt marsh can experience a transition into a tidal

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Flood and ebb currents provide different contributions to the initiation and evolution of tidal channel networks, generating diverse network structures and channel cross-sections. In order to separate the effects of these contributions, a physical model of a sloping tidal-flat basin was set up in the laboratory. Depending on the degree of tidal asymmetry imposed offshore, either flood or ebb currents can be enhanced. The experimental results show that the ebb current has a higher capability to initiate and shape tidal networks than the flood current. Headward erosion is mainly induced by the ebb flow. The slightly inclined flat surface tends to reduce the energy of the flood current and to enhance the ebb current, thus prolonging the duration of morphodynamic activity as well as sediment motion. Overall, flood-dominated tides favour the formation of small-scale channel branches in the upper basin zone, while long lasting ebb-dominated tides result in more complex, wider and deeper tidal networks.

Due to the strong intermittency of micro-resources, the poor grid-tied power quality, and the high generation-demand sensitivity in micro-grids, research into the control methods of micro-grid systems has always been a notable issue in the field of micro-grids. The inverter is the core control equipment at the primary control level of the micro-grid, and the key factors affecting its output performance can be divided into three categories: control methods, hardware configuration, and control parameter design. Taking the classical active and reactive power (P-Q) control structure and the three-phase, two-stage inverter topology model as an example, this paper designs a parameter for offline tuning, and an online self-tuning optimization method for an inverter control system based on the fruit fly optimization algorithm (FOA). By simulating and comparing the inverter controllers with non-optimized parameters in the same object and environment, the designed parameter tuning method is verified. Specifically, it improves the dynamic response speed of the inverter controller, reduces the steady-state error and oscillation, and enhances the dynamic response performance of the controller. communications will seriously influence the control performance of the entire system [14]. In the field of control science, tuning and optimization of the controller parameters are often carried out to improve the performance of a complicated PI-based control system [15]. However, in the process of parameter tuning, the control objects of different parameters vary in their damping coefficients, which leads to different overshoots, oscillations, durations of rise, and durations of adjustment [16]. Therefore, it is of great significance to explore the application of parameter tuning methods of PI controllers in improving the performance of the underlying control system of a micro-grid [17]. Research on PI controller parameter tuning can be divided into two major categories: offline tuning [18,19] and online tuning [20,21]. In Al-Saedi's work [22], online optimization tuning is conducted for PI controller parameters of micro-grid inverters by the particle swarm optimization algorithm (PSO) and error performance index methods. However, as the update calculation process of an individual particle is relatively complex, the overall calculation time is long, which makes it more suitable for offline tuning [23,24]. Compared with PSO, the fruit fly optimization algorithm (FOA) [25] requires less in terms of the calculation process and a simpler structure, with the advantage of shorter calculation time for parameter tuning. Research works [26][27][28] have discussed the feasibility of optimizing PI controller parameter tuning in an industrial process by using FOA, and they have provided guidance for this paper. Appl. Sci. 2019, 9, 1327 2 of 24 control network communications will seriously influence the control performance of the entire system [14]. In the field of control science, tuning and optimization of the controller parameters are often carr...

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