No abstract

A significant correlation was detected between the deregulation of specific types of miRNAs, such as miR-519a, miR-153 and miR-485-5p, and clinical variables as well as histological subtypes in ovarian cancers. Hence, these miRNAs may perform functions as diagnostic or prognostic biomarkers.

The primary wall of higher plants consists of a rigid cellulose-xyloglucan network that is embedded in and interacts with a pectin network. Rhamnogalacturonan II (RG-II) 4 is a structurally complex pectic polysaccharide found in primary walls of angiosperms and gymnosperms. RG-II is composed of at least 12 different glycosyl residues linked together by more than 20 different glycosidic linkages, but despite this complexity, the glycosylresidue composition of RG-II is remarkably conserved among species (1, 2). RG-II exists predominantly as a dimer that is covalently cross-linked by a borate diester. Borate cross-linking of RG-II additionally results in crosslinking of the two homogalacturonan chains upon which the RG-II molecules are constructed (2). These processes of cross-linking are thought to result in a stable three-dimensional pectin network.Although little is known about how the structural complexity of RG-II contributes to its biological function, evidence suggests that the structural integrity of the RG-II molecule is essential for normal borate cross-link formation. The mur1 mutant is dwarfed and has brittle stems (3), and these defects are caused by a mutation in GMD2 encoding a GDP-mannose 4,6-dehydratase, an enzyme required for the biosynthesis of L-fucose (4). RG-II synthesized by the mur1 mutant completely lacks L-Fuc residues, and only ϳ50% of the RG-II is cross-linked by borate (5). Interestingly, the mur2 mutant, which is defective in a xyloglucan-specific fucosyltransferase, synthesizes xyloglucan that contains little L-Fuc but grows normally (6), indicating that xyloglucan fucosylation is not critical for plant growth regulation and wall strength. Taken together, these results suggest that the dwarfed phenotype of mur1 plants is caused by reduced cross-linking of RG-II due to lack of L-fucose residues. Supporting this, an exogenous supply of borate rescues the growth defect of the mur1 mutant (5). The nolac-H18 tobacco callus mutant shows reduced cell adhesion and defective shoot development, which is caused by altered RG-II structure (7). The RG-II of the mutant lacks the ␣-L-Galp-(1 3 2)-␤-D-GlcpA-(1 3 portion of side chain A. Only ϳ50% of the RG-II in the mutant walls is present as a dimer compared with Ͼ95% dimer formation in wild-type walls. Expression of NpGUT1 encoding a putative glucuronosyltransferase in the mutant rescues the mutant phenotype, including restoration of borate crosslinking to normal levels (7). These results suggest that the ␣-L-Galp-(1 3 2)-␤-D-GlcpA-(1 3 portion of side chain A is required for normal borate cross-linking. Finally, the bor1 mutant has a defective efflux type transporter that mediates borate transfer (8). The wild-type and bor1 RG-II have similar glycosyl residue compositions, but ϳ60% of RG-II in bor1 cell walls is present as the monomer (9). Borate treatment rescues the dwarfism and the extent of RG-II cross-linking of the bor1 mutant.

No abstract