Comparative Analysis of Luisia (Aeridinae, Orchidaceae) Plastomes Shed Light on Plastomes Evolution and Barcodes Investigation.

Luisia, a genus of the subtribe Aeridinae of Orchidaceae, comprises ca. 40 species. Members of Luisia exhibit unique morphological characteristics and represent a valuable ornamental orchid genus. However, due to the scarcity of distinct morphological characters, species identification within this genus is ambiguous and controversial. In the present study, next-generation sequencing (NGS) methods were used to assemble the plastomes of five Luisia species and compare them with one publicly available Luisia plastid genome data. The plastomes of Luisia possessed a quadripartite structure, with sizes ranging from 146,243 bp to 147,430 bp. The plastomes of six Luisia species contained a total of 120 genes, comprising 74 protein-coding genes, 38 tRNA genes and eight rRNA genes. Notably, all ndh genes were pseudogenized or lost. An analysis of codon usage bias showed that leucine (Leu) exhibited the highest frequency, while cysteine (Cys) exhibited the lowest frequency. A total of 57 to 64 SSRs and 42 to 49 long repeats were identified. Five regions and five coding sequences were identified for DNA barcodes, based on the nucleotide diversity (Pi) analysis. The species of Luisia constituted a monophyletic group and were sister to Paraphalaenopsis with strong support. Our study deepens the understanding of species identification, plastome evolution and the phylogenetic positions of Luisia.

The function of tumor-derived exosomes.

Exosomes, especially the tumor-derived exosomes (TDEs), are extracellular vesicles released by many kinds of cells, which are involved in several biological and pathological processes. Their contents mainly include DNA, RNA and proteins. The message could be transmitted in neighboring or distant cells by secreting extracellular vesicles (EVs). Exosomes are a main intercellular communication regulator because they are involved and interact with intracellular signaling pathways. Exosomes can be detected in the tumor microenvironment, and there is growing evidence that TDEs are active in tumor growth, angiogenesis, invasion and metastasis, as well as immune responses and drug resistance. All of the functions mentioned above make it clear that exosomes have an important role in tumors. This review focuses on the origin and structure of TDEs and their important biological functions in the environment due to cell-to-cell intercellular communication.