Comparison of the mitochondrial genomes of three geographical strains of Apis laboriosa indicates high genetic diversity in the black giant honeybee (Hymenoptera: Apidae).

Apis laboriosa is the largest honeybee that lives mainly on cliff faces, with strong migratory ability. In this study, we firstly sequenced and assembled two complete mitochondrial genomes of A. laboriosa isolated from two distant locations in China (Chongqing and Shangri-La regions). Combined with the published mitochondrial genome of A. laboriosa from Nepal, comparative genomic analyses were conducted to gain insight into the genetic diversity of giant honeybees from different geographical distributions. The mitochondrial genomes of A. laboriosa from Chongqing and Shangri-La regions were 15,579 and 15,683 bp in length, respectively, both larger than that from Nepal with the length of 15,510 bp. Three mitochondrial genomes all harbor 37 common genes and present the same AT bias and the frequency of codon usage. However, the fragments including COX1, SSUrRNA, LSUrRNA, and the AT-rich region of the mitochondrial genome from Shangri-La region demonstrate distinctive insertions and deletions compared to those from Chongqing and Nepal regions. Phylogenetic trees of mitochondrial genomes show that A. laboriosa from Chongqing is most closely related to that from Nepal, rather than to Shangri-La. Genetic distance between Shangri-La and Chongqing or Nepal was even larger than that between the various subspecies of Apis mellifera. Overall, these results unmark that A. laboriosa in different geographical distributions can exhibit high genetic diversity at the mitochondrial genomic level, and therein, A. laboriosa from Shangri-La may be the subspecies. All these studies will contribute to our understanding of the geographical distribution and genetic differentiation of black giant honeybee in Asian region.

Pathological analysis of silkworm infected by two microsporidia Nosema bombycis CQ1 and Vairimorpha necatrix BM.

Microsporidia Nosema bombycis CQ1 can be vertically transmitted in silkworm Bombyx mori but Vairimorpha necatrix BM cannot. Therefore, the pathological differences in silkworm infected with these two microsporidia required clarification. Here, we compared the virulence of N. bombycis CQ1 and V. necatrix BM against silkworm. The pathological characteristics in intestine, testis and ovary were surveyed using paraffin sections, scanning electron microscopy and transmission electron microscopy. Our data firstly showed that the virulence of V. necatrix BM was weaker than that of N. bombycis CQ1. Secondly, the typical symptom of V. necatrix BM infection is making xenomas, which are full of pathogens in different stages, at the posterior of intestine. However, no xenomas were formed surrounding intestines infected with N. bombycis CQ1. Thirdly, N. bombycis CQ1 can cluster spores near the trachea while infecting ovaries. It is worth noting that N. bombycis CQ1 infected epithelial cells and connective tissues of ovaries, while V. necatrix BM did not. Although silkworm ovaries can not be infected by V. necatrix BM in vivo, it can infect embryonic and ovarian cell lines in vitro. This study is the first report about comparing infection features of N. bombycis CQ1 and V. necatrix BM in silkworm tissues and it provided elaborate and visual information of pathological characteristics which can help to explain the different transmission strategies of these two microsporidia.

[Effects of traditional Tibetan drug Liu Tea on proliferation and chemotherapeutic sensitivity of drug-resistant human gastric cancer cell BGC823/5-FU].

To investigate the effects of Liu Tea extracts(LTE) on proliferation, apoptosis and drug sensitivity of drug-resistant gastric cancer cell BGC823/5-FU. MTT assay was used to analyze effect of LTE on cell growth and sensitivity chemotherapeutic drugs, and synergistic effect of the combination of LTE with 5-FU on BGC823/5-FU cells. Combination index (CI) was calculated by CompuSyn. Cell apoptosis was measured by flow cytometry (FCM). Protein expressions of P-gp, Bcl-2, Bax and Caspase-3 (17KD) were detected by Western blot at different concentrations of LTE in BGC823/5-FU cells (100, 200, 400 mg•L⁻¹). The results showed that LTE had an inhibitory effect on growth of BGC823/5-FU cell in a dose-time-dependent manner and significantly reduced IC50 of 5-FU, CDDP, PTX and ADM to BGC823/5-FU cells(P<0.05), indicating it could reverse tolerance of drug resistant cells to chemotherapeutic drugs, with reversion multiples of 2.35, 1.68, 1.96, 0.52. The combination of LTE with 5-FU had positive synergistic effect on the BGC-823 cell line. FCM assay suggested that LTE could induce BGC823/5-FU apoptosis. The apoptosis rate was up to 46.2% when the cells were treated with 800 mg•L⁻¹ LTE after 24 h(P<0.01). According to the protein detection results, with the increase in concentration of LTE, the protein expression of Bcl-2 was gradually decreased(P<0.01), the expression of Bax and Caspase-3 were extremely increased(P<0.01), with statistical significance in difference(P<0.01) but no difference in the expression of P-gp between experiment group and control group. LTE can inhibit the growth of drug-resistant human gastric cancer cell BGC823/5-FU and reverse its chemotherapeutic tolerance to some extent. Inhibition of antiapoptotic proteins, activation of proapoptotic proteins and induction of apoptosis of resistant cells may be its main mechanisms.