Effect of VIRP1 Protein on Nuclear Import of Citrus Exocortis Viroid (CEVd)

Before replicating, Pospiviroidae viroids must move into the plant nucleus. However, the mechanisms of viroid nuclear import are not entirely understood. To study the nuclear import of viroids, we established a nuclear import assay system using onion cell strips and observed the import of Alexa Fluor-594-labeled citrus exocortis viroid (CEVd). To identify the plant factors involved in the nuclear import of viroids, we cloned the Viroid RNA-binding Protein 1 (VIRP1) gene from a tomato cultivar, Seokwang, and heterologously expressed and purified the VIRP1 protein. The newly prepared VIRP1 protein had alterations of amino acid residues at two points (H52R, A277G) compared with a reference VIRP1 protein (AJ249595). VIRP1 specifically bound to CEVd and promoted its nuclear import. However, it is still uncertain whether VIRP1 is the only factor required for the nuclear import of CEVd because CEVd entered the plant nuclei without VIRP1 in our assay system. The cause of the observed nuclear accumulation of CEVd in the absence of VIRP1 needs to be further clarified.

Preparation and Mechanical Properties of Short Antheraea pernyi Silk Fiber Reinforced Onion Composite

To protect resource and environment, recently, the effective recycling of waste natural resources has been paid increased attention by many countries. In this study, the waste onion was used as the matrix material, and the Antheraea pernyi (A. pernyi) silk was used as the reinforcement fiber. The silk/onion composite paper with different fiber content was developed by papermaking technology. The morphological observation and tensile property tests were done. The consequence indicated that the onion had definite matrix property. Onion cell is also looked as a natural nanocomposite reinforced with cellulose microfibrils. The produced onion paper had a tensile strenght of 29.31 MPa and elongation of 1.14%. The A. pernyi silk fiber originated from waste silk quilt had the good reinforcing property for onion matrix, and the tensile property of onion-based composite with different silk fiber content was investigated. The tensile strength of this green-composite were improved remarkably to 46.2 MPa with increasing 31.75 wt% fiber content. The tensile property of this composite can be futher improved by changing the length of silk fiber and coating additives on the composite surface.