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Based on the scanning electron microscope (SEM) observations, it is confirmed that the nacre is composed of aragonite crystals and organic matrix with interlaced arrangement, showing ordered "brick-mortar" structure. The dynamic analysis of preferential orientation of aragonite crystals in the nacre from the abalone (Haliotis diverscolor supertexta) with different shell ages is systematically investigated using X-ray diffraction (XRD) and high resolution transmission electron microscope (HRTEM). Experiments reveal that, in the nacre from the juvenile mollusk shell, there exist three kinds of orientations of aragonite crystals: (113), (002) and (012). However, along with the growing of the mollusk shell, the intensity of (012) and (113) becomes weak, and the (002) becomes the preferred crystal orientation of aragonite in the nacre from the adult mollusk shell, which means that the c axis of aragonite crystals is perpendicular to the nacreous layers. The results obtained show that the nacre possesses a highly ordered structure at the micrometer/nanometer multiscale levels. [ABSTRACT FROM AUTHOR]

Mosquitoes transmit many harmful diseases that seriously threaten public health. The mosquito's olfactory system is of great significance for host selection. Inotropic receptors (IRs) and olfactory receptors (ORs) have been demonstrated to be capable of odorant molecular recognition. Analyzing the molecular principles of mosquito olfaction facilitates the development of prevention and therapy techniques. Advances in the understanding of IRs have been seriously inadequate compared to those of ORs. Here, we provide evidence that 35 Anopheles sinensis IR (AsIR) genes are expressed, 7 of which are in the antennae and 2 have expression levels that are upregulated with a blood meal. A homologous analysis of the sequences showed that AsIRs are a subfamily of ionotropic glutamate receptors (iGLURs). This is the first that time IRs have been identified in Anopheles sinensis in vitro. The ultrastructure of the antennae supports the theory that diverse sensilla are distributed in the antennae. The results here may facilitate the revelation of the regulation mechanism in AsIRs, which could mitigate the transmission of diseases by mosquitoes. [ABSTRACT FROM AUTHOR]