Small population of the largest water strider after the late Pleistocene and the implications for its conservation.

Climate oscillation and its synergistic impacts on habitat fragmentation have been identified as threatening the survival of some extant species. However, the mechanisms by which semi-aquatic insects impacted by such events remain poorly understood. Herein, we studied the largest water strider in the world, Gigantometra gigas, to explore the effect of these two factors on its evolutionary history. The sequences of mitogenomic and nrDNA cluster were utilized to reconstruct phylogenetic relationship among G. gigas populations and its demographic history. Mitochondrial genes were separately reconstructed topologies of that populations and detected remarkable differences. We found that G. gigas populations conform to the isolation-by-distance model, and decline occurred at about 120 ka, which was probably influenced by the climate change during the late Pleistocene and eventually maintained a small effective population size (Ne) around 85,717. The populations in Guangdong Province of China are worthy of note in that they exhibit low genetic diversity, a small Ne around 18,899 individuals, and occupy an area with little suitable future habitat for G. gigas. This work recommends that conservation efforts are implemented to ensure the long-term survival of small G. gigas populations, and notes that further evaluation of their extinction risk under the impacts of human activities is required.

A mitochondrial genome of Micronectidae and implications for its phylogenetic position.

The mitochondrial genome (mitogenome) has been extensively used to better understand the phylogenetic relationships within the heteropteran infraorder Nepomorpha (Hemiptera), but no mitogenome in Micronectidae has been sequenced to date. Here we describe the first complete mitogenome of Micronecta sahlbergii (Jakovlev, 1881). The mitogenome is 15,005 bp in size, containing 13 typical PCGs, 22 tRNAs, two rRNAs and a control region (CR). All genes are arranged in the same gene order as the most other known heteropteran mitogenome. The phylogenetic relationships based on mitogenomes using Bayesian inference and Maximum likelihood methods showed that Micronecta sahlbergii was sister to Sigara septemlineata, suggesting that Micronecta sahlbergii belongs to Corixoidea. Corixoidea was basal within Nepomorpha. The PCG12 and PCG12RT matrices of BI and ML analyses yielded the consistent topology, respectively. Whereas there was no consistent conclusions in PCG123 and PCG123RT matrices. Saturation tests showed that PCG12 and PCG12RT were free of saturation in evaluation of transition and transversion substitution, while PCG123 and PCG123RT exhibited a plateau revealing saturation of transition suggesting that the third codon positions of PCGs were not suitable for addressing relationships at the superfamily level in Nepomorpha. So our results supported the phylogenetic analysis of PCG12 and PCG12RT in Nepomorpha.

Flavones and Lignans from the Stems of Wikstroemia scytophylla Diels.

BACKGROUND: The genus Wikstroemia has about 70 species, but only a limited number of species have been studied chemically. Wikstroemia indica has long been used as a traditional crude drug in China. However, there is no report about the bioactivity of Wikstroemia scytophylla. OBJECTIVE: This paper reports the chemical investigation and biological evaluation of the W. scytophylla. MATERIALS AND METHODS: The EtOAc extraction of W. scytophylla was isolated using chromatographic methods, and the compounds were analyzed by spectroscopic methods. The in vitro antitumor activities against five human cancer cell lines were performed according to the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. RESULTS: The chemical investigation of the stems of W. scytophylla resulted in the isolation of 12 compounds mainly including one biflavone (1), five flavones (2-6) compounds, and six lignans (7-12), in which compound 8 was a new natural product. Compounds 1 and 7-12 were evaluated for their antitumor activities while these compounds showed weak cytotoxicity with the half maximal inhibitory (IC50) values more than 40 µM. CONCLUSION: All of these compounds were isolated from this plant for the first time, and compounds 2-12 were first reported from genus Wikstroemia, in which compound 8 was a new natural product. Compounds 1 and 7-12 exhibited weak antitumor activities (IC50>40 µM). The chemotaxonomic significance of all the isolations was summarized. SUMMARY: The chemical investigation of the stems of W. scytophylla resulted in the isolation of 12 compoundsThe 12 compounds including six lignans (7-12), in which compound 8 was a new natural productThe isolated compounds 1 and 7-12 were evaluated for their antitumor activitiesThe chemotaxonomic significance of all the isolations was summarized. Abbreviations used: MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; IC50: Half maximal inhibitory; HL-60: Human leukemia cell line; SMMC-7721: Human hepatocellular carcinoma cell line; A549: Human lung tumor cell line; MCF-7: Human breast cancer cell line; SW480: Human colon cancer cell line; MS: Mass spectrometry; NMR: Nuclear Magnetic Resonance.

A new phenolic glycoside from Lindera nacusua.

The present study was designed to investigate the chemical constituents of Lindera nacusua and their antitumor activities. A new phenolic glycoside, namely 1-O-3-hydroxyphenyl-5-methoxyphenol-(6'-O-vanilloyl)-ß-d-glucopyranoside (1), together with five known phenolic glycosides (2-6), two anthraquinones (7, 8) and two γ-butanolides (9, 10), was isolated, and its structure was elucidated by spectroscopic and chemical methods. Compounds 1-10 were screened for their in vitro cytotoxicities against HL-60, SMMC-7721, A549, MCF-3 and SW480 cell lines by the MTS method. Compounds 9 and 10 showed moderate cytotoxicities with IC50 values ranging from 17.40 to 35.21 µM.