Altitudinal variation in age and body size in Yunnan pond frog (Pelophylax pleuraden)

Large-scale systematic patterns of body size are a basic concern of evolutionary biology. Identifying body size variation along altitudinal gradients may help us to understand the evolution of life history of animals. In this study, we investigated altitudinal variation in body size, age and growth rate in Chinese endemic frog, Pelophylax pleuraden. Data sampled from five populations covering an altitudinal span of 1413 to 1935 m in Sichuan province revealed that body size from five populations did not co-vary with altitudes, not following Bergmann's rule. Average adult SVL differed significantly among populations in males, but not in females. For both sexes, average adult age differed significantly among populations. Post-metamorphic growth rate did not co-vary with altitude, and females grew faster than males in all populations. When controlling the effect of age, body size did not differ among populations in both sexes, suggesting that age did not affect variation in body size among populations. For females, there may be other factors, such as the allocation of energy between growth and reproduction, that eliminated the effect of age on body size. To our minds, the major reason of body size variation among populations in male frogs may be related to individual longevity. Our findings also suggest that factors other than age and growth rate may contribute to size differences among populations.     

Genetic variation and differentiation of Gekko gecko from different populations based on mitochondrial cytochrome b gene sequences and karyotypes

Black-spotted and red-spotted tokay geckos are distributed in different regions and have significant differences in morphological appearance, but have been regarded as the same species, Gekko gecko, in taxonomy. To determine whether black-spotted and red-spotted tokay geckos are genetically differentiated, we sequenced the entire mitochondrial cytochrome b gene (1147 bp) from 110 individuals of Gekko gecko collected in 11 areas including Guangxi China, Yunnan China, Vietnam, and Laos. In addition, we performed karyotypic analyses of black-spotted tokay geckos from Guangxi China and red-spotted tokay geckos from Laos. These phylogenetic analyses showed that black-spotted and red-spotted tokay geckos are divided into two branches in molecular phylogenetic trees. The average genetic distances are as follows: 0.12-0.47% among six haplotypes in the black-spotted tokay gecko group, 0.12-1.66% among five haplotypes in the red-spotted tokay gecko group, and 8.76-9.18% between the black-spotted and red-spotted tokay geckos, respectively. The karyotypic analyses showed that the karyotype formula is 2n = 38 = 8m + 2sm + 2st + 26t in red-spotted tokay geckos from Laos compared with 2n = 38 = 8m + 2sm + 28t in black-spotted tokay geckos from Guangxi China. The differences in these two kinds of karyotypes were detected on the 15th chromosome. The clear differences in genetic levels between black-spotted and red-spotted tokay geckos suggest a significant level of genetic differentiation between the two.     

The complete mitochondrial genome of Gomphocerus tibetanus Uvarov, 1935 (Orthoptera: Acrididae: Gomphocerinae)

The complete nucleotide sequence of the mitochondrial genome (mitogenome) of Gomphocerus tibetanus Uvarov, 1935 (Orthoptera: Acrididae: Gomphocerinae) was determined. It is 15,571 bp in length and contains 74.8% A + T. All Gomphocerus tibetanus protein-coding sequences start with a typical ATN codon. The usual termination codons (TAA and TAG) were found from 13 PCGs except COI and COII which took incomplete codon T as termination codons. All tRNA genes could be folded into the typical cloverleaf secondary structure, except tRNA^Ser(AGN) lacking of dihydrouridine (D) arm. The sizes of the large and small ribosomal RNA genes are 1313 and 822 bp, respectively. The A + T content of the A + T-rich region is 82.3%. A preliminary analysis on characteristics of Gomphocerinae mitogenome was made by comparision among three Gomphocerinae mitogenomes and Locusta migratoria.     

Identification and characterization of γ-aminobutyric acid uptake system GabPCg (NCgl0464) in Corynebacterium glutamicum

Corynebacterium glutamicum is widely used for industrial production of various amino acids and vitamins, and there is growing interest in engineering this bacterium for more commercial bioproducts such as γ-aminobutyric acid (GABA). In this study, a C. glutamicum GABA-specific transporter (GabP(Cg)) encoded by ncgl0464 was identified and characterized. GabP(Cg) plays a major role in GABA uptake and is essential to C. glutamicum growing on GABA. GABA uptake by GabP(Cg) was weakly competed by l-Asn and l-Gln and stimulated by sodium ion (Na(+)). The K(m) and V(max) values were determined to be 41.1 ± 4.5 μM and 36.8 ± 2.6 nmol min(-1) (mg dry weight [DW])(-1), respectively, at pH 6.5 and 34.2 ± 1.1 μM and 67.3 ± 1.0 nmol min(-1) (mg DW)(-1), respectively, at pH 7.5. GabP(Cg) has 29% amino acid sequence identity to a previously and functionally identified aromatic amino acid transporter (TyrP) of Escherichia coli but low identities to the currently known GABA transporters (17% and 15% to E. coli GabP and Bacillus subtilis GabP, respectively). The mutant RES167 Δncgl0464/pGXKZ9 with the GabP(Cg) deletion showed 12.5% higher productivity of GABA than RES167/pGXKZ9. It is concluded that GabP(Cg) represents a new type of GABA transporter and is potentially important for engineering GABA-producing C. glutamicum strains.     

Salt tolerance of Hibiscus hamabo seedlings: a candidate halophyte for reclamation areas

In order to evaluate the salinity tolerance of Hibiscus hamabo Siebold & Zuccarini (Malvaceae), a candidate halophyte for reclamation areas, we analyze the effects of NaCl concentration, ranging from 0 to 500?mM, on the morphological, photosynthetic and chlorophyll fluorescent traits of this species. The optimal concentration for the germination of H. hamabo was 25?mM NaCl, and the optimal concentration for the survival and growth of H. hamabo ranged from 5 to 10?mM NaCl. Growth traits of H. hamabo at 25?mM, including the plant height, canopy diameter, number of leaves and width of the largest leaf, showed no statistical differences from the control. Net photosynthetic rate, stomatal conduction, light utilization efficiency, water utilization efficiency, maximal photosynthetic rate, light saturation point and chlorophyll content were the highest at 7.5?mM NaCl. F _v/F _m and F _v/F ₀ at 5 and 7.5?mM were significantly higher than the others, while F ₀ was significantly lower. F _m and F _v at NaCl concentrations ranging from 2.5 to 10?mM were significantly higher than the others. Pearson correlation analysis showed that the chlorophyll content, maximal photosynthetic rate and light saturation point were significantly positively correlated with the number of leaves, while F ₀ was significantly negatively correlated with the width of the largest leaf. Light compensation point was significantly negatively correlated with plant height, leaf number, width of the largest leaf and canopy diameter, and might be a good indicator for the salt tolerance of H. hamabo.     

Dissolution and regeneration of collagen fibers using ionic liquid

Native skin collagen fibers were successfully dissolved in the ionic liquid, 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), and regenerated in different precipitators. The observation by polarized optical microscopy showed that the crystal structure of collagen fibers had been destroyed by [BMIM]Cl during the heating. Temperature-dependent FTIR was applied to detect the structural change of collagen/[BMIM]Cl during dissolving. The structure of regenerated collagen was characterized by FTIR and XRD. It showed that the triple helical structure of collagen had been partly destroyed during the dissolution and regeneration. The film forming ability and the thermostability of the regenerated collagen was highly dependent on the precipitating treatment. The possible mechanisms of dissolving of collagen in [BMIM]Cl and the regeneration in the precipitators have been proposed. The collagen/cellulose composite with different forms (film, fiber, gel) can be successfully prepared by using [BMIM]Cl as medium.     

The contribution of side chains to antitumor activity of a polysaccharide from Codonopsis pilosula

In order to assess the potential contribution of the side chains of a polysaccharide (CPPW1) from the roots of Codonopsis pilosula to the biological activities, we chose CPPW1 and its backbone (CPPW1B) as the research targets to compare them with their antitumor and immunomodulatory activity. The results demonstrated CPPW1 could significantly inhibit the tumor growth of H22-bearing mice and simulate lymphocyte proliferation. Meanwhile the phagocytic capability of macrophages and NO production were also enhanced. However, CPPW1B could only inhibit the tumor weight and did not work to immune system at all. Additionally, both CPPW1 and CPPW1B had no toxicity in vivo. Taken together with all data, we found the sugar side chains attached to the backbone of CPPW1 played a pivotal role in fighting against tumor and activating immune system.     

Solution blowing of submicron-scale cellulose fibers

Solution blowing is an innovative process for spinning micro-/nano-fibers from polymer solutions using high-velocity gas flow as fiber forming driving force. Submicron-scale cellulose fibers were successfully solution blown by two improvement measures. First, cellulose solution was directly blown to fibers of 260-1900nm in diameter by raising the air temperature along the spinning line which was proved to accelerate the evaporation of solvent and fiber forming. Second, coaxial solution blowing technique was established with cellulose solution and polyethylene oxide (PEO) solution used as core and shell liquids, respectively. The core-shell structures of the fibers were examined by SEM and TEM. Cellulose fibers with diameter between 160nm and 960nm were further obtained after removing PEO shell. X-ray diffraction studies showed that the two kinds of submicron-scale cellulose fibers are mostly amorphous.     

Mosquito cell line C6/36 shows resistance to Cyt1Aa6

This study aimed to investigate the resistance mechanism of C6/36 cells to Cyt1Aa6 protein under selection pressure. Receptor binding properties of Cyt1Aa6 toward sensitive and resistant C6/36 cells were investigated. More sensitive cells were detected with goat-anti-rabbit-FITC-labeled antibody, and the quantity of in vitro activated Cyt1Aa6 toxin bound to resistant cells was greatly reduced. Ligand western blot assays showed that disappearance of the 26 kDa protein and weakness of the positive bands of 68 kDa from resistant cells might lead to the resistance of C6/36 cells to Cyt1Aa6 toxin. The resistance of C6/36 cells was detected under selection in vitro-activated Cytl1Aa6 toxin. Receptor binding demonstrated that reduced Cyt1Aa6 bound to resistant cells, which might be closely related to the disappearance and weakness of some proteins. The results presented here are the first to demonstrate that Cyt1Aa protein, a uniquely characteristic toxin, induced resistance at the cellular level. It might be attributed to the change of receptors.