Analysis of alterations to the transcriptome of Loquat (Eriobotrya japonica Lindl.) under low temperature stress via de novo sequencing.

Loquat (Eriobotrya japonica Lindl.), which originates from the cooler hill regions of southwestern China, is a typical subtropical evergreen tree. Loquat is one of the most important economic crops in China, but the available genomic information is very limited. Here, we present the first deep transcriptomic analysis of loquat. De novo assembly generated 116,723 contigs and 64,814 unigenes using Illumina sequencing technology. A total of 45,739 unigenes were annotated by Nr, GO, and COG datasets. In addition, we analyzed the gene expression profiles of loquat fruit under low temperature stress and 4017 differential expressed genes were identified. We found that the unigenes involved in the brassinosteroid biosynthesis and phosphatidylinositol signaling systems were upregulated, indicating that they have an important role in the resistance of plants to low temperature. Our results provide an invaluable resource for identification of specific genes and proteins involved in loquat development and response to low temperatures.

IR spectroscopic determination of gel state miscibility in long-chain phosphatidylcholine mixtures.

We report on the gel-state microaggregation in binary mixtures of diacylphosphatidylcholines over temperatures ranging from -19 degrees C to near the gel-to-liquid crystal transition. Microaggregates with lateral dimensions in the range 1-100 chains were detected and measured with an isotope infrared method that relates the splitting or the shape of the methylene scissors band to aggregate size. Measurements were made on fully hydrated dispersions of diC18DPC/diC20HPC, diC18DPC/diC22HPC, and diC18DPC/diC24HPC at molar ratios of 4:1. Low levels of aggregation were determined with reference to the spectrum of the random mixture diC18DPC/diC18HPC. For diC18DPC/diC20HPC at -19 degrees C, which previous calorimetric measurements have indicated is a nearly ideal, we found about 4% of the minority component chains to be involved in aggregates. For diC18DPC/diC22HPC, the value increased to about 11%. DiC18DPC/diC24HPC was found to be highly fractionated, in agreement with the earlier studies. The unit subcell, which defines the type of acyl-chain packing, was determined for the components of the mixtures. The temperature behavior of the phases and the temperatures at which the minority component domains undergo dissolution were determined.

IR spectroscopic study of the structure and phase behavior of long-chain diacylphosphatidylcholines in the gel state.

Fully hydrated dispersions of simple linear saturated diacylphosphatidylcholines with even-numbered acyl chains of lengths from 18 to 24 carbons can exist in a low-temperature, highly ordered, orthorhombic phase (G(o)) that differs from the L beta phase (Gd) normally found for shorter chains. The temperature behavior of these dispersions has been studied by infrared spectroscopy. Chain packing in the G(o) phase was found to be nearly identical to that of the orthorhombic phase of crystalline n-alkanes. With increasing temperature, the G(o) phase undergoes a transition to Gd at approximately 45 degrees C below Tm. This transition occurs at a higher temperature and becomes sharper with increasing chain length. Chain packing in the Gd phase was found to be disordered in a way that can be expressed in terms of a distribution of subcell setting angles. The Gd phase converts to a phase (Gh) with hexagonal-like chain packing at temperatures below Tm. The results support and extend those of a recent x-ray diffraction study of the 24-carbon diacyclphosphatidylcholine gel.