Antarctic hairgrass expansion in the South Shetland archipelago and Antarctic Peninsula revisited

Populations of both native higher Antarctic plants, Deschampsia antarctica and Colobanthus quitensis, increased during the last decades. However, for D. antarctica, previous population studies on the South Shetland Islands and the Antarctic Peninsula have been too sporadic, patchy, and methodologically different to allow general conclusions. Our aim was to compare sites with D. antarctica along a north–south latitudinal transect with an integral census method to assess the possible impact of climatic change on grass population dynamics. During two summer seasons (2009–2010), plant populations were censed on Fildes and Coppermine Peninsula and several localities on the west coast of the Antarctic Peninsula. Largest plant populations were found on Fildes Peninsula with vegetation cover (VC) of 44–46%. Six out of eleven stands of D. antarctica on Coppermine Peninsula were new records, with increasing plant number and VC (0.1–22%). In the Antarctic Peninsula, contrarily to our expectation, only at Forbes Point, D. antarctica VC was relatively high (ca. 2%) and a new stand of C. quitensis was found. At three previously reported sites, plants had disappeared. Our monitoring confirms that northern D. antarctica populations are expanding, but that this expansion is not continuous along the Antarctic Peninsula and inconsistent with the gradient of relative temperature increase in north–south direction. We suggest that other abiotic and biotic factors are influencing the colonization and expansion of vascular plants in this particular ecosystem.     

Large-scale plantlets conversion from cotyledonary somatic embryos of Kalopanax septemlobus tree using bioreactor cultures

A suitable bioreactor system for large scale embryo-to-plantlets conversion of Kalopanax septemlobus was established. In temporary immersion with net (TIN) bioreactor, 85% of embryos successfully produced plantlets whereas in continuous immersion with net (CIN) bioreactor, only conversion rate of 29.3% was obtained. Embryos cultured in TIN bioreactor produced more vigorous plantlets in terms of fresh weight, height, root length, roots and leaves quantity. In CIN bioreactor, Kalopanax plantlets showed high malondialdehyde (MDA) content and increased activities of reactive oxygen species (ROS)-processing enzymes, such as ascorbate peroxidase (APX) and glutathione reductase (GR) indicating the occurrence of oxidative stress. However, superoxide dismutase (SOD) and catalase (CAT) showed similar activities in plantlets grown in different bioreactors. Kalopanax plantlets grown in both TIN and CIN bioreactors were harvested and transferred to greenhouse for their acclimatization. Plantlets grown in CIN bioreactor exhibited low survival rate (75.8%) compared to those grown in TIN bioreactor (100%). MDA content decreased with progression of acclimatization indicating a decrease in oxidative stress. However, MDA level in CIN derived plantlets was higher than TIN derived plantlets. In TIN derived plantlets, an increase in SOD and GR activities were observed after 1 week and thereafter decreased. CAT activity decreased while APX activity started to increase after 1 week of acclimatization. The results indicated that Kalopanax plantlets were able to overcome oxidative stress mainly through SOD activity. However, levels of antioxidant enzyme activities were higher in CIN derived plantlets than TIN derived plantlets. Kalopanax plantlets obtained from TIN bioreactor performed better during the acclimatization phase and showed higher survival rate than material obtained on CIN bioreactor or conventional culture systems.     

Molecular identification of AFLP fragments associated with elytra color variation of the Asian ladybird beetle,Harmonia axyridis (Coleoptera: Coccinellidae)

The Asian ladybird beetle, Harmonia axyridis shows polymorphism in elytra color patterns. However, it is uncertain whether these color patterns are regulated by genetic factors. This investigation used amplified fragment length polymorphism (AFLP) analysis to determine any genetic causes of the variability of color patterns. Using four individuals of each group, AFLP analysis produced 37 polymorphic bands. Among several polymorphic bands, six AFLP markers were associated with elytra color patterns after further analysis using six additional individuals of each group. These polymorphic sites were sequenced but did not match DNA sequence data deposited in GenBank. Based on the color-associated AFLP markers, SCAR primers were designed for PCR amplification of genomic DNA. These primers (SCAR 12 and SCAR 44) were used to analyze color-associated loci and/or alleles of H. axyridis DNA. SCAR 12 primers designed from a Spectabilis type-specific fragment (AFLP 12) amplified a specific band of 530 bp in four Spectabilis individuals, but not in the insects with other color patterns.     

Studies on the mobilization of a maize transposable family,Ac/Ds, in pepper using In Vivo transient assay system

A maize transposable family, Ac/Ds, has been successfully utilized as a mutagenizing agent not only in monocot but also in dicot. In order to develop insertional mutagenesis system in pepper, the mobility of Ac/Ds has been examined. In this study, the excision of the elements was monitored via transient assay system with protoplasts. Two different systems were developed and compared; one- and two-elements systems. In a one-element system, Ac alone was introduced into cells. As a two-element system, Ac and Ds were cloned into a single vector and were expressed in protoplasts. Our data showed that both Ac and Ds elements were highly mobile in pepper cells. This is the first report suggesting that Ac/Ds mediated gene tagging system could be successfully operated in pepper.     

The critical role played by endotoxin-induced liver autophagy in the maintenance of lipid metabolism during sepsis

Macroautophagy/autophagy is a central mechanism by which cells maintain integrity and homeostasis, and endotoxin-induced autophagy plays important roles in innate immunity. Although TLR4 stimulation mediated by lipopolysaccharide (LPS) also upregulates autophagy in hepatocytes and liver, its physiological role remains elusive. The objective of this study was to determine the role of LPS-induced autophagy in the regulation of liver lipid metabolism. LPS treatment (5 mg/kg) increased autophagy, as detected by LC3 conversion and transmission electron microscopy (TEM) analysis in C57BL6 mouse livers. AC2F hepatocytes also showed increased autophagic flux after LPS treatment (1 μg/ml). To investigate the role of LPS-induced autophagy further, liver lipid metabolism changes in LPS-treated mice and fasted controls were compared. Interestingly, LPS-treated mice showed less lipid accumulation in liver than fasted mice despite increased fatty acid uptake and lipid synthesis-associated genes. In vitro analysis using AC2F hepatocytes demonstrated LPS-induced autophagy influenced the degradation of lipid droplets. Inhibition of LPS-induced autophagy using bafilomycin A₁ or Atg7 knockdown significantly increased lipid accumulation in AC2F hepatocytes. In addition, pretreatment with chloroquine aggravated LPS-induced lipid accumulation and inflammation in C57BL6 mouse livers. The physiological importance of autophagy was verified in LPS-treated young and aged rats. Autophagic response was diminished in LPS-treated aged rats and lipid metabolism was impaired during sepsis, indicating autophagy response is important for regulating lipid metabolism after endotoxin challenge. Our findings demonstrate endotoxin-induced autophagy is important for the regulation of lipid metabolism, and suggest that autophagy helps maintain lipid metabolism homeostasis during sepsis.     

Acetazolamide Inhibits the Level of Tyrosinase and Melanin: An Enzyme Kinetic,In Vitro,In Vivo,and In Silico Studies

Melanin is the major factor that determines skin color and protects from ultraviolet radiation. In present study we evaluated the anti‐melanogenesis effect of acetazolamide (ACZ) using four different approaches: enzyme kinetic, in vitro, in vivo and in silico. ACZ demonstrated significant inhibitory activity (IC₅₀ 7.895 ± 0.24 μm ) against tyrosinase as compared to the standard drug kojic acid (IC₅₀ 16.84 ± 0.64 μm ) and kinetic analyses showed that ACZ is a non‐competitive inhibitor without cytotoxic effect. In in vitro experiments, A375 human melanoma cells were treated with 20 or 40 μm of ACZ with or without 50 μm of l ‐DOPA. Western blot results showed that ACZ significantly (P < 0.05) decreased the expression level of tyrosinase at 40 μm . Zebrafish embryos were treated with 10, 20 or 40 μm of ACZ and of positive control kojic acid. At 72 h of treatment with ACZ and kojic acid, ACZ significantly (P < 0.001) decreased the embryos pigmentation to 40.8% of untreated embryos at the dose of 40 μm of ACZ while kojic acid decreased only 25.0% of pigmentation at the same dose of kojic acid. In silico docking were performed against tyrosinase using PyRx tool. Docking studies suggested that His244, Asn260 and His85 are the major interacting residues in the binding site of the protein. In conclusion, our results suggest that ACZ is a good candidate for the inhibition of melanin and it could be used as a lead for developing the drugs for hyperpigmentary disorders and skin whitening.     

Evaluation of microbial globin promoters for oxygen-limited processes using <Emphasis Type="Italic">Escherichia coli</Emphasis>

Oxygen-responsive promoters can be useful for synthetic biology applications, however, information on their characteristics is still limited. Here, we characterized a group of heterologous microaerobic globin promoters in Escherichia coli. Globin promoters from Bacillus subtilis, Campylobacter jejuni, Deinococcus radiodurans, Streptomyces coelicolor, Salmonella typhi and Vitreoscilla stercoraria were used to express the FMN-binding fluorescent protein (FbFP), which is a non-oxygen dependent marker. FbFP fluorescence was monitored online in cultures at maximum oxygen transfer capacities (OTR_max) of 7 and 11 mmol L^?1 h^?1. Different FbFP fluorescence intensities were observed and the OTR_max affected the induction level and specific fluorescence emission rate (the product of the specific fluorescence intensity multiplied by the specific growth rate) of all promoters. The promoter from S. typhi displayed the highest fluorescence emission yields (the quotient of the fluorescence intensity divided by the scattered light intensity at every time-point) and rate, and together with the promoters from D. radiodurans and S. coelicolor, the highest induction ratios. These results show the potential of diverse heterologous globin promoters for oxygen-limited processes using E. coli.