Isolation of extremely halotolerant cocci from Antarctica

Abstract Five non-motile Gram-positive cocci were isolated from saline located in geothermal regions of the Antarctic continent. The organisms were extremely halotolerant growing between 0 and 4.2 M NaCl. On the basis of the results of phenotypic characterizations, lipid and quinone analyses, and the amino acid composition of the cell the isolates have been assigned to the genus Micrococcus .     

Urea transport by nitrogen-regulated tonoplast intrinsic proteins in Arabidopsis

Urea is the major nitrogen (N) form supplied as fertilizer in agricultural plant production and also an important N metabolite in plants. Because urea transport in plants is not well understood, the aim of the present study was to isolate urea transporter genes from the model plant Arabidopsis. Using heterologous complementation of a urea uptake-defective yeast (Saccharomyces cerevisiae) mutant allowed to isolate AtTIP1;1, AtTIP1;2, AtTIP2;1, and AtTIP4;1 from a cDNA library of Arabidopsis. These cDNAs encode channel-like tonoplast intrinsic proteins (TIPs) that belong to the superfamily of major intrinsic proteins (or aquaporins). All four genes conferred growth of a urea uptake-defective yeast mutant on 2 mm urea in a phloretin-sensitive and pH-independent manner. Uptake studies using 14C-labeled urea into AtTIP2;1-expressing Xenopus laevis oocytes demonstrated that AtTIP2;1 facilitated urea transport also in a pH-independent manner and with linear concentration dependency. Expression studies showed that AtTIP1;2, AtTIP2;1, and AtTIP4;1 genes were up-regulated during early germination and under N deficiency in roots but constitutively expressed in shoots. Subcellular localization of green fluorescent protein-fused AtTIPs indicated that AtTIP1;2, AtTIP2;1, and AtTIP4;1 were targeted mainly to the tonoplast and other endomembranes. Thus, in addition to their role as water channels, TIP transporters may play a role in equilibrating urea concentrations between different cellular compartments.     

Lycopene in association with alpha-tocopherol or tomato lipophilic extracts enhances acyl-platelet-activating factor biosynthesis in endothelial cells during oxidative stress

Lipophilic compounds contained in tomato can prevent cardiovascular diseases by modulating the atherogenic processes in vascular endothelium mediated by oxidized low-density lipoproteins (LDLs). We investigated the effects of lycopene on the metabolism of platelet-activating factor (PAF) and its much less biologically active acyl analog, acyl-PAF, known to prevent LDL oxidation. Lycopene, or lycopene in association with alpha-tocopherol, or whole tomato lipophilic extracts (containing more than 80% lycopene) were used in experiments in which endothelial cells (ECs) are known to synthesize PAF following H(2)O(2)-induced oxidative stress. The results indicated that in each case H(2)O(2)-stimulated PAF biosynthesis in ECs, which is catalyzed by acetyl-CoA acetyltransferase (AT), appeared strongly inhibited. However, acyl-PAF biosynthesis, which also occurs through the PAF-dependent transacetylase (TA), was significantly increased by lycopene only when it was in association with alpha-tocopherol or with the minor compounds present in the whole lipophilic tomato extract. These findings suggest that alpha-tocopherol or lipophilic compounds present in tomato juice potentiate the effects of lycopene on the modulation of PAF and acyl-PAF biosynthesis in ECs during oxidative stress.     

DNA metabarcoding quantifies the relative biomass of arthropod taxa in songbird diets: Validation with camera‐recorded diets

Ecological research is often hampered by the inability to quantify animal diets. Diet composition can be tracked through DNA metabarcoding of fecal samples, but whether (complex) diets can be quantitatively determined with metabarcoding is still debated and needs validation using free‐living animals. This study validates that DNA metabarcoding of feces can retrieve actual ingested taxa, and most importantly, that read numbers retrieved from sequencing can also be used to quantify the relative biomass of dietary taxa. Validation was done with the hole‐nesting insectivorous Pied Flycatcher whose diet was quantified using camera footage. Size‐adjusted counts of food items delivered to nestlings were used as a proxy for provided biomass of prey orders and families, and subsequently, nestling feces were assessed through DNA metabarcoding. To explore potential effects of digestion, gizzard and lower intestine samples of freshly collected birds were subjected to DNA metabarcoding. For metabarcoding with Cytochrome Oxidase subunit I (COI), we modified published invertebrate COI primers LCO1490 and HCO1777, which reduced host reads to 0.03%, and amplified Arachnida DNA without significant changing the recovery of other arthropod taxa. DNA metabarcoding retrieved all commonly camera‐recorded taxa. Overall, and in each replicate year (N = 3), the relative scaled biomass of prey taxa and COI read numbers correlated at R = .85 (95CI:0.68–0.94) at order level and at R = .75 (CI:0.67–0.82) at family level. Similarity in arthropod community composition between gizzard and intestines suggested limited digestive bias. This DNA metabarcoding validation demonstrates that quantitative analyses of arthropod diet is possible. We discuss the ecological applications for insectivorous birds.     

Chemical-physical characterization of polyhydroxyalkanoates recovered by means of a simplified method from cultures of <Emphasis Type="Italic">Halomonas campaniensis</Emphasis>

In this study we suggest a simplified and effective method to directly recover polyhydroxyalkanoates (PHAs) from humid biomass of Halomonas campaniensis with no pre-treatment steps. Sodium dodecyl sulphate (SDS) was directly added to dispersed biomass of cultured micro-organism (w/w ratio: 1) in distilled water followed by shaking, heat treatment, and washing steps. The purity of the recovered PHAs synthesized by H. campaniensis was over 95%, regardless of the cell concentrations and the best yield was 12% (w/w) of the cell wet weight when the micro-organism was cultivated in a glucose-based medium or a glucose/propionate-based medium. MS spectroscopy and ¹H, ¹³C-NMR analysis were used to chemically characterize the PHAs; their thermal characteristics were obtained using a differential scanning calorimeter and the average viscosity molecular weight was assessed through specific viscosity measurements. Due to its ease and velocity, our simplified method is suitable for the detection and recovery of PHAs from humid biomasses with high yield and purity. The method, which is quick and at low environmental impact, is very valuable for the simultaneous testing of cultures grown with different inducers for PHAs having particular chemical/physical characteristics.     

Biosorption of Heavy Metals (Cd2+, Cu2+, Co2+, and Mn2+) by Thermophilic Bacteria,Geobacillus thermantarcticus and Anoxybacillus amylolyticus: Equilibrium and Kinetic Studies

ABSTRACT

Two strains of thermophilic bacteria, Geobacillus thermantarcticus and Anoxybacillus amylolyticus, were employed to investigate the biosorption of heavy metals including Cd²⁺, Cu²⁺, Co²⁺, and Mn²⁺ ions. The effects of different biosorption parameters such as pH (2.0–10.0), initial metal concentrations (10.0–300.0 mg L^?1), amount of biomass (0.25–10 g L^?1), temperature (30–80°C), and contact time (15–120 min) were investigated. Concentrations of metal ions were determined by using an inductively coupled plasma optical emission spectrometry (ICP-OES). Optimum pHs for Cd²⁺, Cu²⁺, Co²⁺, and Mn²⁺ biosorption by Geobacillus thermantarcticus were found to be 4.0, 4.0, 5.0, and 6.0, respectively. For Anoxybacillus amylolyticus, the optimum pHs for Cd²⁺, Cu²⁺, Co²⁺, and Mn²⁺ biosorption were found to be 5.0, 4.0, 5.0, and 6.0, respectively. The Cd²⁺, Cu²⁺, Co²⁺, and Mn²⁺ removals at 50 mg L^?1 in 60 min by 50 mg dried cells of Geobacillus thermantarcticus were 85.4%, 46.3%, 43.6%, and 65.1%, respectively, whereas 74.1%, 39.8%, 35.1%, and 36.6%, respectively, for Anoxybacillus amylolyticus. The optimum temperatures for heavy metal biosorption were near the optimum growth temperatures for both strains. Scatchard plot analysis was employed to obtain more compact information about the interaction between metal ions and biosorbents. The plot results were further studied to determine if they fit Langmuir and Freundlich models.     

A halophilic thermotolerant Bacillus isolated from a marine hot spring able to produce a new exopolysaccharide

A halophilic, thermotolerant Bacillus strain (B3-15), isolated from water of a shallow, marine hot spring at Vulcano Island (Eolian Islands, Italy), produced an exocellular polysaccharide at 165 mg l^–1. It grew on kerosene as sole carbon source and was resistant to Cd²⁺, Zn²⁺, As²⁺ and Hg²⁺. From 16S rDNA analysis, strain B3-15 was related to B. licheniformis. The exopolysaccharide was a tetrasaccharide repeating unit essentially constituted by sugars having a manno-pyranosidic configuration.     

Mutual Mate Choice for Colorful Traits in King Penguins

While studies of mate choice based on male color pattern are ubiquitous, studies of mate choice based on ornamental color traits in sexually monomorphic species are less common. We conducted manipulative field experiments on two color ornaments of king penguins (Aptenodytes patagonicus), the size of auricular patches of orange feathers and degree of UV reflectance from beak spots, to determine how the degree of ornamentation influenced pairing rate. In a reduction of auricular patch size, females paired significantly more quickly than males in both control and experimental samples. When this bias was taken into account statistically, pairing of individuals with reduced auricular patches was significantly delayed. We also reduced, but did not eliminate, UV reflectance from beak spots by applying a UV filter; no sex difference in pairing rate was evident in this experiment. Treated birds paired significantly more slowly than untreated control individuals, taking more than a week longer to pair on average than their unmanipulated counterparts, a result that was significant for males and approached significance for females. Our results may indicate mutual mate choice via UV reflectance of the beak spot. Given that this is a species where breeding is extremely slow and considerable investment by both males and females is required for successful reproduction, our results support the hypothesis that in such species, sexual selection might act on the same ornament in both sexes.     

Cd, Cu, Ni, Mn and Zn resistance and bioaccumulation by thermophilic bacteria, Geobacillus toebii subsp. decanicus and Geobacillus thermoleovorans subsp. stromboliensis

Bioaccumulation and heavy metal resistance of Cd²⁺, Cu²⁺, Ni²⁺, Zn²⁺ and Mn²⁺ ions by thermophilic Geobacillus toebii subsp. decanicus and Geobacillus thermoleovorans subsp. stromboliensis were investigated. The metal resistance from the most resistant to the most sensitive was found as Mn > Ni > Cu > Zn > Cd for both Geobacillus thermoleovorans subsp. stromboliensis and Geobacillus toebii subsp. decanicus. It was determined that the highest metal bioaccumulation was performed by Geobacillus toebii subsp. decanicus for Zn (36,496 μg/g dry weight cell), and the lowest metal bioaccumulation was performed by Geobacillus toebii subsp. decanicus for Ni (660.3 μg/g dry weight cell). Moreover, the dead cells were found to biosorbe more metal in their membranes compared to the live cells. In the presence of 7.32 mg/l Cd concentration, the levels of Cd absorbed in live and dead cell membranes were found as 17.44 and 46.2 mg/g membrane, respectively.