Identification, characterization and functional analysis of a chitin synthase gene in the brown citrus aphid, Toxoptera citricida (Hemiptera, Aphididae).

Chitin synthase (CHS) is a crucial enzyme involved in the final step of the insect chitin biosynthetic pathway. In this study, we cloned the full-length cDNA sequence of a chitin synthase gene (TCiCHS) from the brown citrus aphid, Toxoptera citricida, an important citrus pest and the main vector of citrus tristeza virus worldwide. TCiCHS was expressed during the entire lifecycle and in all insect tissues examined. Expression was highest in first-second-instar nymphs, nymph-adult transitions and in the abdomen (6.7-fold higher than head). Embryos had a higher expression level than the integument. Fourth-instar nymphs were exposed to 5 and 500 mg/l concentrations of the chitin synthesis inhibitor diflubenzuron (DFB) for 48 h and had the highest mortality at the 500 mg/l concentration. The mRNA expression levels of TCiCHS were significantly enhanced upon the exposure of nymphs to both low and high DFB concentrations. Silencing of TCiCHS occurred through plant-mediated double-stranded RNA (dsRNA) feeding. Most dsRNA-fed nymphs were unable to moult to the next stage, and the expression of TCiCHS decreased 48% compared with controls. These results demonstrate that TCiCHS plays an important role in nymph to adult development, is possibly help identify molecular targets for To. citricida control.

An analysis of the small RNA transcriptome of four developmental stages of the citrus red mite (Panonychus citri).

The citrus red mite (Panonychus citri) can feed on more than 112 plant species around the world. Endogenous small RNAs (sRNAs) have proved to be important components of gene regulation in many eukaryotes. Recently, many sRNAs have been shown to be involved in various biological processes, such as development in many animals, including insects; however, to date, no sRNAs have been reported in the citrus red mite. Using Illumina sequencing, several categories of sRNAs were identified, including 594 known microRNAs (miRNAs) grouped into 206 families and 31 novel miRNAs in the four developmental stages of citrus red mite. In addition, according to bioinformatics analysis and S-Poly(T) miRNA assays, the expression level of many miRNAs varied among the developmental stages. Furthermore, the prediction of miRNAs target genes and their functional annotation indicated that miRNAs are involved in the regulation of multiple pathways in the citrus red mite. As the first report of the sRNA world in citrus red mite, the present study furthers our understanding of the roles played by sRNAs in the development of citrus red mite and the data may help to develop methods of controlling the pests in the field.

[Leiomyosarcoma in the musculature of large vessel wall].

Leiomyosarcoma of the large arteries and veins is rare. In this paper, one case of primary leiomyosarcoma of the axillary vein is reported. The patient, a 66 year old man, was admitted because of a mass in the medial side of right upper arm for three years and increasingly growing. The tentative diagnosis was neurologic fibroma. A local resection was performed and the final diagnosis of leiomyosarcoma of the right axillary vein was established by pathology. So far, there are 86 cases reported in the foreign literature but only one in the Chinese literature. The neoplasm most frequently occurs in the large veins (68 cases) and approximately one half in the inferior vena cava (33/68). 18 neoplasms are originated from the large arteries and of them, 10 from the pulmonary arteries. Primary leiomyosarcoma in large veins is about four times as common as that in arteries. The primary sites in order of incidence: (1) inferior vena cava; (2) pulmonary artery; (3) other large veins and (4) other large arteries.