Spindle-F Is the Central Mediator of Ik2 Kinase-Dependent Dendrite Pruning in Drosophila Sensory Neurons.

During development, certain Drosophila sensory neurons undergo dendrite pruning that selectively eliminates their dendrites but leaves the axons intact. How these neurons regulate pruning activity in the dendrites remains unknown. Here, we identify a coiled-coil protein Spindle-F (Spn-F) that is required for dendrite pruning in Drosophila sensory neurons. Spn-F acts downstream of IKK-related kinase Ik2 in the same pathway for dendrite pruning. Spn-F exhibits a punctate pattern in larval neurons, whereas these Spn-F puncta become redistributed in pupal neurons, a step that is essential for dendrite pruning. The redistribution of Spn-F from puncta in pupal neurons requires the phosphorylation of Spn-F by Ik2 kinase to decrease Spn-F self-association, and depends on the function of microtubule motor dynein complex. Spn-F is a key component to link Ik2 kinase to dynein motor complex, and the formation of Ik2/Spn-F/dynein complex is critical for Spn-F redistribution and for dendrite pruning. Our findings reveal a novel regulatory mechanism for dendrite pruning achieved by temporal activation of Ik2 kinase and dynein-mediated redistribution of Ik2/Spn-F complex in neurons.

[Study on bio-contact oxidation A/O process of Guanting Reservior water under low temperature].

The results of the experiments showed that biological contact A/O process could run steadily under low temperature and had better removal effect for ammonia nitrogen and had some removal effect for COD and TN from water of Guanting Reservoir. When the temperature dropped greatly, removal ratio of ammonia nitrogen dropped evidently, but gradually rose and remained at high removal level at last. Under the conditions of the experiment that the temperature was 0-5 degrees C and influent ammonia nitrogen was about 10 mg/L, ammonia nitrogen removal rate remained more than 95% at last. The change of temperature had no evident influence on removal effect of COD. And the conclusion could be got by microscope that under the temperature at 0-5 degrees C the microorganism in the biofilm still had a good activity.