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In wireless sensor networks, uniform cluster formation and optimal routing paths finding are always the two most important factors for clustering routing protocols to minimize the network energy consumption and balance the network load. In this paper, an improved genetic algorithm based annulus-sector clustering routing protocol called GACRP is proposed. In GACRP, the circular network is divided into sectors with the same size for each annulus, whose number is determined by calculating the minimum energy consumption of each annulus. Each annulus-sector forms a cluster and the best node in this annulus-sector is selected as cluster head. Moreover, an improved genetic algorithm with a novel fitness function considering energy and load balance is presented to find the optimal routing path for each CH, and an adaptive round time is calculated for maintaining the clusters. Simulation results show that GACRP can significantly improve the network energy efficiency and prolong the network lifetime as well as mitigate the hot spot problem.

H9N2 subtype avian influenza virus poses a constant threat to the poultry industry and the control of the disease leans upon the use of effective vaccines. As an alternative to the conventional chicken embryonated eggs, animal cell culture could overcome the limitations of egg supplies and upgrade the manufacturing of avian influenza vaccines for poultry. Development of serum-free suspension cell culture could allow even higher virus productivity, where a suspension cell line with good growth and production performance is required. In this work, an adherent MDCK cell line was adapted to suspension growth to cell concentration up to 12 × 106 cells/mL in a serum-free medium in batch cultures. Subsequently, the influenza virus propagation in this MDCK cell line was evaluated and was improved with the medium exchange at time of infection as well as optimization of infection conditions in terms of MOI and cell concentration for infection. Furthermore, various feed strategies were tested in the infection phase for improved virus titer and a maximum hemagglutinin titer of 13 log2 (HAU/50 μL) was obtained using the 1:2 medium dilution strategy. Evaluation of MDCK cell growth and H9N2 virus propagation in the bioreactors with optimized operating conditions showed comparable cell performance and virus yield compared to shake flasks, with a high cell-specific virus yield above 14000 virions/cell. With the purified H9N2 virus harvested from the bioreactor, the MDCK cell-derived vaccine was able to induce high titers of neutralizing antibodies in chickens. Overall, the results demonstrate the promising application of the highly efficient MDCK cell-based production platform for the avian influenza vaccine manufacturing.

Background Seed germination and seedling establishment are two of the most critical phases in plant development. However, the molecular mechanisms underlying the effect of phosphorus on seed germination and post-germinated growth of oilseed rape are unclear so far. Here, we report the role of BnPHT1;4 in seed germination and early seedling development of Brassica napus. Results Our results show that BnPHT1;4 is preferentially expressed in cotyledons of early developing seedlings. Overexpression of BnPHT1;4 in oilseed rape promoted seed germination and seedling growth. Expression levels of the genes related to ABA and GA biosynthesis and signaling were significantly altered in BnPHT1;4 transgenic seedlings. Consequently, active GA level was up-regulated, whereas ABA content was down-regulated in BnPHT1;4 transgenic seedlings. Furthermore, exogenous GA could promote seed germination of wild type, while exogenous ABA could partially recover the advanced-germination phenotype of BnPHT1;4 transgenic seeds. Total phosphorus content in cotyledons of the transgenic seedlings was decreased more rapidly than that in wild type when Pi was supplied or deficient, and Pi contents in shoots and roots of the BnPHT1;4 transgenic plants were higher than those in wild type under high and low Pi conditions. Conclusions Our data suggest that the high-affinity transporter BnPHT1;4 is involved in phosphorus acquisition and mobilization for facilitating seed germination and seedling growth of Brassica napus by modulating ABA and GA biosynthesis. Electronic supplementary material The online version of this article (10.1186/s12870-019-1765-3) contains supplementary material, which is available to authorized users.