Population structure and genetic diversity of Tamarix chinensis as revealed with microsatellite markers in two estuarine flats.

Background: Tamarix chinensis Lour. is a 3-6-meter-tall small tree with high salt- and alkali- tolerance and aggressive invasiveness, mainly distributed in the eastern part of China in warm-temperate and subtropical climate zones, yet there is little information available regarding genetic diversity and population structure. Methods: A total of 204 individuals of nine T. chinensis populations were investigated for genetic diversity and population structure using a set of 12 highly polymorphic microsatellite markers. Results: The total number of alleles detected was 162, the average number of effective allele was 4.607, the average polymorphism information content (PIC) value of the 12 loci was 0.685, and the mean observed heterozygosity (Ho) and the mean expected heterozygosity (He) was 0.653 and 0.711, respectively. Analysis of molecular variance (AMOVA) showed a 5.32% genetic variation among T. chinensis populations. Despite a low population differentiation, Bayesian clustering analysis, discriminant analysis of principal components (DAPC) and the unweighted pair group method with arithmetic mean (UPGMA) clearly identified three genetic clusters correlated to the populations' geographic origin: the northern populations including those from Yellow River Delta, the Fangshan (FS) population from Beijing, the Changyi (CY) population from Bohai Bay, the Huanjiabu (HHJ) population from Hangzhou Bay, and the remaining two populations from Hangzhou Bay. There was a significant relationship between the genetic distance and geographical distance of the paired populations. Gene flow (Nm) was 4.254 estimated from FST. Conclusion: T. chinensis possessed high genetic diversity comparable to tree species, and although the population differentiation is shallow, our results classified the sampled populations according to sampling localities, suggesting the different origins of the study populations.

Two-dimensional displacement (bending) sensor based on cascaded Fabry-Perot interferometers fabricated in a seven-core fiber.

We demonstrated a two-dimensional vector displacement (bending) sensor with high angular resolution based on Vernier effect generated by two cascaded Fabry-Perot interferometers (FPI) in a seven-core fiber (SCF). To form the FPI, plane-shaped refractive index modulations are fabricated as the reflection mirrors in the SCF using slit-beam shaping and femtosecond laser direct writing. Three pairs of cascaded FPIs are fabricated in the center core and the two non-diagonal edge cores of the SCF and applied to the vector displacement measurement. The proposed sensor exhibits high displacement sensitivity with significant direction dependence. The magnitude and direction of the fiber displacement can be obtained via monitoring the wavelength shifts. Moreover, the source fluctuations and the temperature cross-sensitivity can be referenced out by monitoring the bending-insensitive FPI of the center core.

Probing the Energetic Metabolism of Resting Cysts under Different Conditions from Molecular and Physiological Perspectives in the Harmful Algal Blooms-Forming Dinoflagellate Scrippsiella trochoidea.

Energetic metabolism is essential in maintaining the viability of all organisms. Resting cysts play important roles in the ecology of dinoflagellates, particularly for harmful algal blooms (HABs)-causative species. However, the energetic metabolism underlying the germination potency maintenance of resting cysts of dinoflagellate have been extremely scarce in studies from physiological and, particularly, molecular perspectives. Therefore, we used the cosmopolitan Scrippsiella trochoidea as a representative of HABs-forming and cyst-producing dinoflagellates in this work to obtain novel insights into the molecular mechanisms, regulating the energetic metabolism in dinoflagellate resting cysts, under different physical condition. As the starting step, we established a cDNA subtractive library via suppression subtractive hybridization (SSH) technology, from which we screened an incomplete sequence for the ß subunit of ATP synthase gene (ß-F1-ATPase), a key indicator for the status of cell's energetic metabolism. The full-length cDNA of ß-F1-ATPase gene from S.trochoidea (Stß-F1-ATPase) was then obtained via rapid amplification of cDNA ends (RACE) (Accession: MZ343333). Our real-time qPCR detections, in vegetative cells and resting cysts treated with different physical conditions, revealed that (1) the expression of Stß-F1-ATPase in resting cysts was generally much lower than that in vegetative cells, and (2) the Stß-F1-ATPase expressions in the resting cysts under darkness, lowered temperature, and anoxia, and during an extended duration of dormancy, were significantly lower than that in cysts under the condition normally used for culture-maintaining (a 12 h light:12 h dark cycle, 21 °C, aerobic, and newly harvested). Our detections of the viability (via Neutral Red staining) and cellular ATP content of resting cysts, at the conditions corresponding to the abovementioned treatments, showed that both the viability and ATP content decreased rapidly within 12 h and then maintained at low levels within the 4-day experimentation under all the three conditions applied (4 °C, darkness, and anoxia), which are well in accordance with the measurements of the transcription of Stß-F1-ATPase. These results demonstrated that the energy consumption of resting cysts reaches a low, but somehow stable, level within a short time period and is lower at low temperature, darkness, and anoxia than that at ambient temperature. Our work provides an important basis for explaining that resting cysts survive long-term darkness and low temperature in marine sediments from molecular and physiological levels.

3,000 km and 1,500-year presence of Aureococcus anophagefferens reveals indigenous origin of brown tides in China.

The nonmotile, spherical, picoplanktonic (2-µm-sized) pelagophyte Aureococcus anophagefferens has caused numerous harmful blooms ("brown tides") across global marine ecosystems. Blooms have developed along the east coast of the USA since 1985, a limited number of times in South Africa around 1997, and frequently in China since 2009. As a consequence, the harmful blooms have caused massive losses in aquaculture and coastal ecosystems, particularly mortalities in cultured shellfish. Therefore, whether A. anophagefferens was recently introduced to China via natural/artificial transport of resting stage cells or has been an indigenous species has become a question of profound ecological significance and broad interest, which motivated our extensive investigation on the geographic and historical presence of this species in the seas of China. We applied a combined approach of extensive PCR-based detection and sequencing, germination experiments and monoclonal antibody staining of germlings to samples of surface sediment and sediment core (dated via combined isotopic measurements) collected from all four seas of China, and searched the supplementary data set of a recent Science publication. We discovered that A. anophagefferens does have a resting stage in the sediment, but it also has a wide geographic distribution both in China (covering a range of ~30° in latitude, ~15.7° in longitude and 2.5-3,456 m in water depth; temperate to tropical and coastal to open oceans) and in almost all oceans of the world and a historical presence of >1,500 years in the Bohai Sea, China. The work revealed that A. anophagefferens is not a recently introduced, but an indigenous species in China and has in fact a globally cosmopolitan distribution.

Effects of ZnO nanoparticles on the toxicity of cadmium to duckweed Lemna minor.

Release of nanoparticles into the aquatic environment will inevitably influence the behavior and toxicities of other existing pollutants. In the present study, 10 mg/L of nano-ZnO (diameter 20-30 nm) was used to evaluate its impacts on cadmium (Cd) toxicity on duckweed Lemna minor based on IC50 values and four biological parameters including percent inhibition of growth rate (Ir), ratio of chlorophyll/pheophytin (D665/D665a), antioxidant enzymes, and H+-ATPase. Results of the 96-h IC50 values of Cd with or without nano-ZnO indicate no additional toxicological effects of nano-ZnO to plants. Further examinations using two Cd concentrations (0.1 and 1 mg/L) showed that nano-ZnO did not influence the inhibitory effect of 0.1 mg/L Cd, but significantly (P < 0.05) reduced the stress of 1 mg/L Cd to the duckweed. The index D665/D665a reflected that the toxic effect of 1 mg/L Cd was significantly (P < 0.05) suppressed by nano-ZnO. H+-ATPase was also sensitive to reveal the protective effects of nano-ZnO on the duckweed under Cd exposure. However, the responses of the antioxidant enzymes SOD and CAT failed to reflect the effects of nano-ZnO on Cd toxicity. Hysteretic addition of nano-ZnO for 24 h showed that the protective effects of nano-ZnO were weakened. Our results suggest that the adsorption of Cd to nano-ZnO may result in lower Cd uptake by L. minor, thus reducing its toxicity.