[Preparation and the biological effect of fusion protein GLP-1-exendin-4/ IgG4(Fc) fusion protein as long acting GLP-1 receptor agonist].

GLP-1 has a variety of anti-diabetic effects. However, native GLP-1 is not suitable for treatment of diabetes due to its short half-life (t½, 2-5 min). Exendin-4 is a polypeptide isolated from lizard saliva, which can bind to GLP-1 receptor, produce physiological effects similar to GLP-1, t½ up to 2.5 h, therefore, we developed a long-lasting GLP-1 receptor agonists and GLP-1-exendin-4 fusion IgG4 Fc [GLP-1-exendin-4/ IgG4(Fc)]. We constructed the eukaryotic expression vector of human GLP-1-exendin-4/IgG4(Fc)-pOptiVEC- TOPO by gene recombination technique and expressed the fusion protein human GLP-1-IgG4 (Fc) in CHO/DG44 cells. The fusion protein stimulated the INS-1 cells secretion of insulin, GLP-1, exendin-4 and fusion protein in CD1 mice pharmacokinetic experiments, as well as GLP-1, exendin-4 and fusion protein did anti-diabetic effect on streptozotocin induced mice. Results demonstrated that the GLP-1-exendin-4/IgG4(Fc) positive CHO/DG44 clones were chosen and the media from these positive clones. Western blotting showed that one protein band was found to match well with the predicted relative molecular mass of human GLP-1-exendin-4/IgG4(Fc). Insulin RIA showed that GLP-1-exendin-4/IgG4(Fc) dose-dependently stimulated insulin secretion from INS-1 cells. Pharmacokinetic studies in CD1 mice showed that with intraperitoneal injection (ip), the fusion protein peaked at 30 min in circulation and maintained a plateau for 200 h. Natural biological half-life of exendin-4 was (1.39 ± 0.28) h, GLP-1 in vivo t½ 4 min, indicating that fusion protein has long-lasting effects on the modulation of glucose homeostasis. GLP-1-exendin-4/IgG4(Fc) was found to be effective in reducing the incidence of diabetes in multiple-low-dose streptozotocin-induced diabetes in mice, longer duration of the biological activity of the fusion protein. The biological activity was significantly higher than that of GLP-1 and exendin-4. GLP-1-exendin-4/IgG4(Fc) has good anti-diabetic activity. It can be used as a long-acting GLP-1 agonists.

[Spatial distribution pattern and time series dynamics of Panonychus ulmi Koch in an apple orchard of Liaoning Province, Northeast China].

Panonychus ulmi Koch is one of the important pest insects of apple production in China. To clarify the spatiotemporal dynamics of P. ulmi on the apple tree crowns in an apple orchard of Liaoning, Northeast China, an investigation with random sampling was conducted on the pest mite number at each direction and each layer of the crowns in the whole growth season from May to November 2007. The spatial distribution pattern and time series dynamics of P. ulmi were analyzed by calculating the indices of aggregation and using the parameters of Iwao model. In the early and mid growth periods of apple tree, P. ulmi within whole crown fitted negative binomial distribution, presented an aggregated pattern, and its fundamental component was the group composed of several individuals that attracted each other. The aggregation intensity showed a negative fluctuation with population density, namely, high population density but low patchiness density, and low population density but high patchiness density, and there existed definite differences at different crown directions and layers, i. e., the patchiness density was the highest in south direction and the lowest in west direction, and was higher in mid and lower layers than in upper layer, and in inner layer than in outer layer.