Cloning of the quail PIWI gene and characterization of PIWI binding to small RNAs.

The PIWI protein regulates gene expression at the epigenetic and post-transcriptional level with a variety of endogenous small non-coding RNAs. In poultry, the biological function of the PIWI protein and PIWI binding to small RNAs had not been determined. The present study cloned and analyzed the sequences of the PIWIL1 protein. We also characterized PIWIL1 binding to small RNAs from adult quail testis, where the PIWIL1 protein is specifically expressed. Small RNAs showed a strong peak at 24-27 nt in the testicular RNA library, mapped primarily to repeat sequences and were similar to rasiRNAs. MicroRNAs (miRNAs) were abundant in the ovarian RNA library at a peak of 22 nt

EjFAD8 Enhances the Low-Temperature Tolerance of Loquat by Desaturation of Sulfoquinovosyl Diacylglycerol (SQDG)

Loquat (Eriobotrya japonica Lindl.) is an evergreen fruit tree of Chinese origin, and its autumn–winter flowering and fruiting growth habit means that its fruit development is susceptible to low-temperature stress. In a previous study, the triploid loquat (B431 × GZ23) has been identified with high photosynthetic efficiency and strong resistance under low-temperature stress. Analysis of transcriptomic and lipidomic data revealed that the fatty acid desaturase gene EjFAD8 was closely associated with low temperatures. Phenotypic observations and measurements of physiological indicators in Arabidopsis showed that overexpressing-EjFAD8 transgenic plants were significantly more tolerant to low temperatures compared to the wild-type. Heterologous overexpression of EjFAD8 enhanced some lipid metabolism genes in Arabidopsis, and the unsaturation of lipids was increased, especially for SQDG (16:0/18:1; 16:0/18:3), thereby improving the cold tolerance of transgenic lines. The expression of ICE-CBF-COR genes were further analyzed so that the relationship between fatty acid desaturase and the ICE-CBF-COR pathway can be clarified. These results revealed the important role of EjFAD8 under low-temperature stress in triploid loquat, the increase expression of FAD8 in loquat under low temperatures lead to desaturation of fatty acids. On the one hand, overexpression of EjFAD8 in Arabidopsis increased the expression of ICE-CBF-COR genes in response to low temperatures. On the other hand, upregulation of EjFAD8 at low temperatures increased fatty acid desaturation of SQDG to maintain the stability of photosynthesis under low temperatures. This study not only indicates that the EjFAD8 gene plays an important role in loquat under low temperatures, but also provides a theoretical basis for future molecular breeding of loquat for cold resistance

The PIWIL1 protein.

<p>A: Complete amino acid sequence of PIWIL1; PAZ domain, red; PIWI domain, blue. B: A phylogenetic tree of the PIWIL1 protein generated using UPGMA.</p

Pre-miRNAs and mature miRNAs identified in three libraries.

<p>Pre-miRNAs and mature miRNAs identified in three libraries.</p

Properties of unannotated unique reads in the testis.

<p>A: Chromosomal distribution of exons (top), repeat sequences (middle) and unannotated unique reads (bottom). The number of bases in exons of Refseq genes and repeats are plotted as a percentage of overall chromosome length. The numbers of piRNAs are normalized to chromosome length and plotted. B: Density analysis of exons (red), repeat sequences (green) and unannotated unique reads (with the positive strand in blue and the negative strand in purple) along chromosome 16. The densities of exons and repeats were using a 50 kB window, scanning the genome in increments of 1000 bases. Unannotaed uniques densities were determined by calculating a moving average of reads in a 5 kB sliding window (100 base increments) along each chromosome. Only reads that map 1 to 5 times to the genome were used in density analysis.</p

<i>PIWIL1</i> is specifically expressed in the testis.

<p>A: Northern blot analysis of <i>PIWIL1</i> expression in adult tissues with <i>β-actin</i> as the loading control. B: Western blot analysis of adult tissues; H, heart; L, live; K, kidney; B, brain; T, testis; O, ovary; F, lung; XJ, pectoral muscle.</p