Isolation of the AccCDK8 gene of Apis cerana cerana and its functional analysis under pesticide and heavy metal stress.

Environmental pollution has gained negative attention in recent years. The pesticides and heavy metals are top list of environmental toxicants directly endangering the survival and development of Apis cerana cerana. Cyclin-dependent kinases (CDKs) are heteromeric serine/threonine kinases that participate in cell cycle regulation and have a vital role in pesticide and heavy metal stress in Apis cerana cerana. In this experiment, we filtered out CDK8 gene from Apis cerana cerana (AccCDK8) and investigated its functions of pesticide and heavy metals resistance. Sequence analysis indicated that AccCDK8 is highly homologous to multiple CDK8s and contains a highly conserved CDK active site sequence. Phylogenetic analysis showed that AmCDK8 and AccCDK8 were closely related evolutionarily in Apis mellifera. Transcriptome analysis revealed that AccCDK8 expression was differentially affected after exposure to pesticide and heavy metal stresses. This indicates that AccCDK8 has a significant role in the resistance of Apis cerana cerana to pesticide and heavy metal stresses. It has implications for studying the function of CDK in other insects in response to stress.

The role of AccCDK20 and AccCDKN1 from Apis cerana cerana in development and response to pesticide and heavy metal toxicity.

Apis cerana cerana is a native bee species in China and plays a key role in agricultural production and ecological balance. However, the growth and development of Apis cerana cerana has not been smooth, and pesticide and heavy metal stress are key factors that have forced a dramatic decline in population size. This study was performed with the objective of investigating the role of AccCDK20 and AccCDKN1 in honey bee resistance to pesticide and heavy metal stress. RT-qPCR analysis revealed that AccCDK20 transcript levels were highest in brown-eyed pupae and AccCDKN1 transcript levels were highest in 1-day-old worker bees. In different tissues and body parts of adult bees, AccCDK20 transcript levels were highest in the head, and AccCDKN1 transcript levels were highest in the thorax. It was further observed that environmental stress can affect the transcript levels of the AccCDK20 and AccCDKN1 genes. Silencing of the AccCDK20 and AccCDKN1 genes resulted in altered activities of antioxidant-related genes and antioxidant-related enzymes. AccCDK20 and AccCDKN1 transcript levels were upregulated under glyphosate stress, and silencing of the genes resulted in reduced resistance to glyphosate and greatly increased mortality in Apis cerana cerana. In addition, gene function was verified by in vitro repression assays. Overexpression of the AccCDK20 and AccCDKN1 proteins in E. coli cells increased the resistance to ROS damage induced by CHP. In conclusion, AccCDK20 and AccCDKN1 play an indispensable role in honey bee resistance to pesticide and heavy metal stress.

Eulerian-Eulerian Numerical Study of the Flue Gas Desulfurization Process in a Semidry Spouted Bed Reactor.

The Eulerian-Eulerian two-fluid model (TFM) in conjunction with kinetic theory of granular flows (KTGF) was used for analyzing water vaporization and the semidry flue gas desulfurization process in a two-dimensional powder-particle spouted bed (PPSB). In an environment with high-temperature gas, desulfurization slurry is wrapped on the surface of moving particles and evaporated, along with the application of the user defined function (UDF) method to accomplish water heat and mass transfer by considering evaporation in the simulation process. The simulation results revealed that the best mass- and heat-transfer effect of each phase can be found in the outer annulus and the near spout region, both of which are also the main areas where water vaporization occurs. The rate of desulfurization products decreases with the increase in inlet gas temperature as the water vaporization rate increases. The volume fraction of desulfurization reaction products decreases with the increase in inlet flue gas temperature. Compared with other working conditions, the highest desulfurization efficiency reaches 84% when the inlet flue gas temperature is 480 K. The change of the desulfurization product rate with the radial distance is the same under different superficial gas velocities, with the peak desulfurization efficiency appearing in the annulus. The optimal operating parameter for the desulfurization process is available in PPSB, and the desulfurization efficiency and gas handling capacity reach the best result when the superficial gas velocity equals 1.2 Ums.

CFD Simulation and Optimization of Mixing Behaviors in a Spouted Bed with a Longitudinal Vortex.

The radial mixing characteristics of gas and solid phases in a cylindrical spouted bed with a pair of longitudinal vortex generators (LVGs) are numerically studied by a two-fluid model. The influence of the distance between the centers of two spheres (L) and the shape of LVGs on hydrodynamics in a spouted bed are discussed. The results show that the value of the coefficient of variation (CV) of the particle concentration can be significantly reduced by the longitudinal vortex produced in spouted beds. The particle concentration near the spout decreases first and then increases with the increase of L. When the shape of LVGs is cylindrical, a maximum increase of 188 % for particle volume fraction is found near the spout region of the spouted bed. The strengthening effect on particles' velocity achieves the best in annulus of the spouted bed, and CV of the particle concentration in the spouted bed reaches its minimum value with a pair of cylindrical LVGs.