Genetic legacy of tertiary climatic change: a case study of two freshwater loaches, Schistura fasciolata and Pseudogastromyzon myersi, in Hong Kong.

The high biodiversity and strong population structure of freshwater fauna has often been attributed to historical geological and climatic alterations. The impact of these historical changes on obligate freshwater species on a small geographical scale has not been well understood due to the lack of fine-scale comparative phylogeographic studies. Strong population structure has been reported in a goby and a caridean shrimp in Hong Kong, a small but highly developed city in South China, but the common drivers of population differentiation in freshwater fauna in this region remain unclear. This study examined the fine-scale phylogeographic patterns of two freshwater loaches, Schistura fasciolata and Pseudogastromyzon myersi in Hong Kong, using sequence data of mitochondrial control region and two nuclear markers (interphotoreceptor retinoid binding protein gene 2 and ribosomal protein S13 gene). Results show that they exhibit pronounced population structure as supported by high and significant ΦST. Phylogenetic analyses based on the control region reveal six and three distinct lineages in S. fasciolata and P. myersi, respectively. Phylogeographic structure of both species generally follows the paleodrainage pattern, though P. myersi shows a shallower structure on the Mainland, perhaps due to their higher mobility. Most of these lineages diverged during the Pliocene and Late Pleistocene, a period with marked sea-level fluctuations. In a broader context, this suggests that sea-level fluctuation played an important role in shaping even the fine-scale population structure of freshwater fish in South China, implying that the genetic diversity of this fauna may be higher than expected.

Genetic variation based on microsatellite analysis of the oriental river prawn, Macrobrachium nipponense from Qiandao Lake in China.

The oriental river prawn (Macrobrachium nipponense) is an important freshwater prawn species in China. We collected 236 oriental river prawns from four wild stocks from Qiandao Lake, Zhejiang, China, and used nine polymorphic microsatellite markers to investigate their genetic diversity and structure, to facilitate the development of a selective breeding program. We found 185 alleles at nine loci in this sample. The observed heterozygosity (H(O)) and expected heterozygosity (H(E)) ranged from 0.43 to 0.89 and 0.56 to 0.95, respectively. The four stocks of M. nipponense displayed high genetic diversity (14.33-15.89 alleles/locus, H(O) = 0.66-0.77 and H(E) = 0.78-0.88). Genetic diversity of the stock from Weiping town was lower than the stocks from the other locations. Mutation-drift equilibrium analysis showed no significant bottleneck effect. F-statistics among stocks ranged from 0.03 to 0.07, indicating a moderate level of differentiation. Based on genetic structure analysis, the 236 individuals from the four wild stocks could be divided into two potential populations. Overall, the 09CA, 09AY and 09JJ wild stocks had higher allelic and genetic diversity than the upstream 09WP stock. These three wild stocks could be used as founders for selective breeding.

Phylogeny of penaeoid shrimps (Decapoda: Penaeoidea) inferred from nuclear protein-coding genes.

Penaeoidea is a diverse group of economically important marine shrimps. Attention to the evolutionary history of the penaeoids has been raised since studies using mitochondrial DNA markers and sperm ultrastructure contradict classification of the penaeoid families based on morphology and hence challenge the long standing taxonomy of this superfamily. In this study, DNA sequences of two nuclear protein-coding genes, phosphoenolpyruvate carboxykinase and sodium-potassium ATPase alpha-subunit, were determined from 37 penaeoid genera to reconstruct the evolutionary relationships and to estimate divergence ages of the penaeoid shrimps. Phylogenetic analyses using maximum likelihood and Bayesian approaches strongly support the monophyly of Solenoceridae, Aristeidae and Benthesicymidae, but find Sicyoniidae nested within Penaeidae, making this family paraphyletic. Penaeoidea comprises two lineages: the former three families in one while the latter two in another. The diversification of these lineages may be related to bathymetry. The penaeid-like lineage diversified in the Triassic, earlier than the aristeid-like lineage with an origin in the Jurassic. Taxonomic revisions within Penaeoidea are also proposed for further investigation. Due to the paraphyly of Penaeidae and the high genetic divergence among the three penaeid tribes of Burkenroad [Burkenroad, M.D., 1983. Natural classification of Dendrobranchiata, with a key to recent genera. In: Schram, F.R. (Ed.), Crustacean Issues I. Crustacean Phylogeny. A.A. Balkema, Rotterdam, pp. 279-290], these tribes should be treated as having the same taxonomic rank as Sicyoniidae, while the family ranking of Benthesicymidae has to be re-considered owing to the low genetic divergence between the benthesicymids and the aristeids.

Phylogeny of Decapoda using two nuclear protein-coding genes: origin and evolution of the Reptantia.

The phylogeny of Decapoda is contentious and many hypotheses have been proposed based on morphological cladistic analyses. Recent molecular studies, however, yielded contrasting results despite their use of similar data (nuclear and mitochondrial rDNA). Here we present the first application of two nuclear protein-coding genes, phosphoenolpyruvate carboxykinase and sodium-potassium ATPase alpha-subunit, to reconstruct the phylogeny of major infraorders within Decapoda. A total of 64 species representing all infraorders of Pleocyemata were analyzed with five species from Dendrobranchiata as outgroups. Maximum likelihood and Bayesian inference reveal that the Reptantia and all but one infraorder are monophyletic. Thalassinidea, however, is polyphyletic. The nodal support for most of the infraordinal and inter-familial relationships is high. Stenopodidea and Caridea form a clade sister to Reptantia, which comprises two major clades. The first clade, consisting of Astacidea, Achelata, Polychelida and three thalassinidean families (Axiidae, Calocarididae and Eiconaxiidae), corresponds essentially to the old taxon suborder Macrura Reptantia. Polychelida nests within Macrura Reptantia instead of being the most basal reptant as suggested in previous studies. The high level of morphological and genetic divergence of Polychelida from Achelata and Astacidea justifies its infraorder status. The second major reptant clade consists of Anomura, Brachyura and two thalassindean families (Thalassinidae and Upogebiidae). Anomura and Brachyura form Meiura, with moderate support. Notably thalassinidean families are sister to both major reptant clades, suggesting that the stem lineage reptants were thalassinidean-like. Moreover, some families (e.g. Nephropidae, Diogenidae, Paguridae) are paraphyletic, warranting further studies to evaluate their status. The present study ably demonstrates the utility of nuclear protein-coding genes in phylogenetic inference in decapods. The topologies obtained are robust and the two molecular markers are informative across a wide range of taxonomic levels. We propose that nuclear protein-coding genes should constitute core markers for future phylogenetic studies of decapods, especially for higher systematics.

Template-free synthesis of hierarchical hollow NiSx microspheres for supercapacitor.

Hierarchical nickel sulfide (NiSx) hollow microspheres can be successfully synthesized with a template-free method using α-Ni(OH)2 microspheres as a precursor by calcination and sulfidation. The intermediate Ni hollow spheres, formed at different calcination temperatures (300°C and 400°C) under H2/N2 atmosphere, can be easily transformed into NiSx with similar morphology and mixed phases of Ni3S2 and NiS during the followed sulfidation process. The formation processes for the hollow structure of NiSx are also discussed in this work. Particularly, the NiSx prepared from Ni intermediate spheres at 300°C show a high specific capacity of 153.6mAhg-1 at 0.5Ag-1 at high mass loading due to its small crystal size, hierarchically porous structure and high electrical conductivity. A hybrid capacitor was assembled by using it as positive electrode and activated carbon as negative electrode to examine their practical applications in a full-cell configuration. The hybrid capacitor exhibited excellent comprehensive performances in 1.6V. The hybrid capacitor also showed good cycling stability, with 81.25% of the initial specific capacitance after 1000 cycles at 2Ag-1. Above results indicate the great potential of the NiSx hollow spheres as a promising electrode material for supercapacitor applications.

Hybrid nanomaterial of α-Co(OH)2 nanosheets and few-layer graphene as an enhanced electrode material for supercapacitors.

Supercapacitor with metal hydroxide nanosheets as electrode can have high capacitance. However, the cycling stability and high rate capacity is low due to the low electrical conductivity. Here, the exfoliated α-Co(OH)2 nanosheets with high capacitance has been assembled on few-layer graphene with high electric conductivity by a facile yet effective and scalable solution method. Exfoliated hydrotalcite-like α-Co(OH)2 nanosheets and few-layer graphene suspensions were prepared by a simple ultrasonication in formamide and N-methyl-2-pyrrolidone, respectively. Subsequently, a hybrid was made by self-assembly of α-Co(OH)2 and few-layer graphene when the two dispersions were mixed at room temperature. The hybrid material provided a high specific capacitance of 567.1F/g at 1A/g, while a better rate capability and better stability were achieved compared to that mad of pristine and single exfoliated α-Co(OH)2. When the hybrid nanocomposite was used as a positive electrode and activated carbon was applied as negative electrode to assembly an asymmetric capacitor, an energy density of 21.2Wh/kg at a power density of 0.41kW/kg within a potential of 1.65V was delivered. The high electrochemical performance and facile solution-based synthesis method suggested that the hybrid of exfoliated α-Co(OH)2/few-layer graphene could be a potential electrode material for electrochemical capacitor.

Perching and takeoff of a robotic insect on overhangs using switchable electrostatic adhesion.

For aerial robots, maintaining a high vantage point for an extended time is crucial in many applications. However, available on-board power and mechanical fatigue constrain their flight time, especially for smaller, battery-powered aircraft. Perching on elevated structures is a biologically inspired approach to overcome these limitations. Previous perching robots have required specific material properties for the landing sites, such as surface asperities for spines, or ferromagnetism. We describe a switchable electroadhesive that enables controlled perching and detachment on nearly any material while requiring approximately three orders of magnitude less power than required to sustain flight. These electroadhesives are designed, characterized, and used to demonstrate a flying robotic insect able to robustly perch on a wide range of materials, including glass, wood, and a natural leaf.

IgE isotype switch and IgE production are enhanced in IL-21-deficient but not IFN-gamma-deficient mice in a Th2-biased response.

IgE plays a critical role in the pathogenesis of allergy and asthma. Therefore, suppression of IgE production would provide therapeutic benefits to patients suffering from these diseases. We have reported that the production of IgE is regulated differently in the spleen vs. the draining lymph nodes (LN). IgE isotype switch and IgE producing B cell expansion occur in the draining LN after antigen (Ag) immunization, but do not happen in the spleen. In addition, a population of pre-existing IgE+ cells is observed in the spleen of normal or sham immunized mice, but is not present in the draining LN. To further understand the regulation of IgE production in different lymphoid organs, and the potential inhibitory factors of IgE isotype switch in the spleen, the involvement of IL-21 and IFN-gamma in regulating IgE production was investigated by using the IL-21 and the IFN-gamma deficient mice. We found that in the absence of IL-21 IgE isotype switch and IgE+ cell clonal expansion were dramatically enhanced in the spleen and IgE isotype switch was partially increased in the draining LN. In addition, IgE production of the pre-existing CD19-CD5+B220(low) IgE+ cells in the spleen was also increased in the absence of IL-21 under physiological conditions. In contrast, using the IFN-gamma deficient mice, we did not observe a negative impact of IFN-gamma on either IgE isotype switch or IgE production. Our data suggest that IL-21 appears to be a critical cytokine to keep low IgE levels under physiological and pathological conditions.