Genetic diversity of the traditional Chinese medicinal plant Ypsilandra thibetica (Melanthiaceae): Applications for conservation

Twelve microsatellite markers were developed to determine the genetic diversity and genetic structure of Ypsilandra thibetica, represented by a total of 90 individuals from six natural populations. All twelve microsatellite loci were polymorphic, and the results indicated that a high genetic diversity was present within populations (mean R_S = 4.996; mean H_E = 0.615), with high levels of genetic structure (mean F_ST = 0.165; mean F_IS = 0.692) among populations. This pattern is likely attributable to consanguineous mating, and this hypothesis is supported by a low relatedness coefficient. Our study suggested that environment factors might restrict gene flow among populations. In addition, physical distances between populations were not related to genetic distances, implying that ancestral populations might have been distributed over a wider area. These results suggest that Y. thibetica should be a high priority for conservation managers.     

An autonomous CMOS hysteretic sensor for the detection of desorption-free DNA hybridization

This paper describes a sensor for label-free, fully electrical detection of DNA hybridization based on capacitive changes in the electrode-electrolyte interface. The sensor measures capacitive changes in real time according to a charging-discharging principle that is limited by the hysteresis window. In addition, a novel autonomous searching technique, which exclusively monitors desorption-free hybridized electrodes among electrode arrays, enhances the performance of the sensor compared with conventional capacitive measurement. The sensor system achieves a detection range of 80 dB. The integrated circuit sensor is fabricated with a 0.35 μm CMOS process. The proposed sensor offers rapid, robust and inexpensive measurement of capacitance with highly integrated detection circuitry. It also facilitates quantitative evaluations of molecular densities on a chip with distinctive impedance variations by monitoring desorption-free hybridized electrodes. Our electrical biosensor has great potential for use with bio analytical tools and point-of-care diagnosis.     

Phylogeny and evolution of bracts and bracteoles in Tacca (Dioscoreaceae)

Most species in the genus Tacca (Dioscoreaceae) feature green to black purple, conspicuous inflorescence involucral bracts with variable shapes, motile filiform appendages (bracteoles), and diverse types of inflorescence morphology. To infer the evolution of these inflorescence traits, we reconstructed the molecular phylogeny of the genus, using DNA sequences from one nuclear, one mitochondrial, and three plastid loci (Internal Transcribed Spacer (ITS), atpA, rbcL, trnL-F, and trnH-psbA). Involucres and bracteoles characters were mapped onto the phylogeny to analyze the sequence of inflorescence trait evolution. In all analyses, species with showy involucres and bracteoles formed the most derived clade, while ancestral Tacca had small and plain involucres and short bracteoles, namely less conspicuous inflorescence structures. Two of the species with the most elaborate inflorescence morphologies (T. chantrieri in southeast China and T. integrifolia in Tibet), are predominantly self-pollinated, indicating that these conspicuous floral displays have other functions rather than pollinator attraction. We hypothesize that the motile bracteoles and involucres may facilitate selfing; display photosynthesis in the dim understory, and protect flowers from herbivory.     

Cellular and molecular remodelling of a host cell for vertical transmission of bacterial symbionts

Various insects require intracellular bacteria that are restricted to specialized cells (bacteriocytes) and are transmitted vertically via the female ovary, but the transmission mechanisms are obscure. We hypothesized that, in the whitefly Bemisia tabaci, where intact bacteriocytes (and not isolated bacteria) are transferred to oocytes, the transmission mechanism would be evident as cellular and molecular differences between the nymph (pre-adult) and adult bacteriocytes. We demonstrate dramatic remodelling of bacteriocytes at the developmental transition from nymph to adulthood. This transition involves the loss of cell–cell adhesion, high division rates to constant cell size and onset of cell mobility, enabling the bacteriocytes to crawl to the ovaries. These changes are accompanied by cytoskeleton reorganization and changes in gene expression: genes functioning in cell–cell adhesion display reduced expression and genes involved in cell division, cell motility and endocytosis/exocytosis have elevated expression in adult bacteriocytes, relative to nymph bacteriocytes. This study demonstrates, for the first time, how developmentally orchestrated remodelling of gene expression and correlated changes in cell behaviour underpin the capacity of bacteriocytes to mediate the vertical transmission and persistence of the symbiotic bacteria on which the insect host depends.     

Isolation and characterization of 13 microsatellite loci from Incarvillea mairei (Bignoniaceae), an endemic species to the Himalaya-Hengduan mountains region

Incarvillea mairei (H. Léveillé) Grierson (Bignoniaceae) is an endemic species to the Himalaya-Hengduan Mountains region. Here, we developed 13 microsatellite markers from I. mairei using a modified biotin-streptavidin capture method. Number of alleles per locus (NA) ranged from 3 to 7 with an average of 4.615. The observed (H _O) and expected (H _E) heterozygosities were from 0.050 to 0.800 and from 0.249 to 0.815, respectively. Additionally, among the 13 identified microsatellite markers, 12 of them were successfully amplified in other three congeneric species, and most of them showed polymorphic. Obtained evidences suggest that these markers provide a useful tool for further study of the population genetic structure and the breeding system in this species or/and infra-generic species.     

云南蜂腰兰的快速繁殖和离体保存

1植物名称云南蜂腰兰（Bulleyia yunnanensisSchltr）。2材料类别新鲜种子和干冷保存种子（-20℃、空气湿度15%条件下130 d,然后转入10℃、湿度为37%条件下保存3、5、21个月）,试管苗的小芽和假鳞茎切段。3培养条件种子萌发培养基：（1）花宝1号（美国Haponex公司产品,N：P：K=7：6：19）3 g·L-（-1）＋NAA 0.5mg·L-（-1）（单位下同）＋活性炭500,