Biomedical subjects

Xiaojian Xu

Publications and source records attributed to Xiaojian Xu.

3 recordsLinked to original sources

PubMed2006

pat-4/ILK and unc-112/Mig-2 are required for gonad function in Caenorhabditis elegans.

Tissue morphogenesis requires proper interaction between cells and the extracellular matrix (ECM), which is mediated by alphabeta heterodimeric receptor integrin. In Caenorhabditis elegans, integrin signaling is essential for formation of gonad. Here, we probe the role of several integrin-associated molecules in ovulation and cell migration. Function of pat-4/integrin-linked kinase (ILK) and unc-112/Mig-2 was examined using RNA-mediated interference (RNAi). Depletion of these messages caused oocyte accumulation in the proximal gonad and distal tip cells (DTC) migration defects. It was further determined that failed ovulation was due to defective contraction and dilation of somatic gonad structures, including spermatheca and gonad sheath. Actin cytoskeleton in the proximal gonad of RNAi animals appeared disorganized, indicating that RNAi of pat-4 or unc-112 inhibited the overall assembly of actin cytoskeleton in somatic gonad. Taken together, our analysis confirms the role of integrin and integrin-associated proteins in gonad function.

Actin Cytoskeleton↗

PubMed2005

Linking integrin to IP(3) signaling is important for ovulation in Caenorhabditis elegans.

Signals from germ and myoepithelial sheath cells initiate ovulation in Caenorhabditis elegans. The coordinated dilation and contraction of spermatheca lead to subsequent fertilization of oocyte. Either the dominant negative mutant pat-3 beta integrin or disruption of talin expression block ovulation. Talin loss-of-function uncovers roles in cell contractility and migration in C. elegans. Role of beta pat-3 integrins in development and function of Caenorhabditis elegans muscles and gonads, suggesting that the interaction between the cell and the extracellular matrix (ECM) is also important for ovulation. Here, we report that integrin plays an essential role in fertility via IP(3) signaling. Sterility caused by RNAi of pat-3 and ECM molecules was suppressed by increased IP(3) signaling. Our data suggest that the cell-ECM interaction controls ovulation via IP(3) signaling.

Animals↗

PubMed2005

Enhanced resolution in Sar/ISAR imaging using iterative sidelobe apodization.

Resolution enhancement techniques in radar imaging have attracted considerable interest in recent years. In this work, we develop an iterative sidelobe apodization technique and investigate its applications to synthetic aperture radar (SAR) and inverse SAR (ISAR) image processing. A modified noninteger Nyquist spatially variant apodization (SVA) formulation is proposed, which is applicable to direct iterative image sidelobe apodization without using computationally intensive upsampling interpolation. A refined iterative sidelobe apodization procedure is then developed for image-resolution enhancement. Examples using this technique demonstrate enhanced image resolution in various applications, including airborne SAR imaging, image processing for three-dimensional interferometric ISAR imaging, and foliage-penetration ultrawideband SAR image processing.

Algorithms↗