Is boldness a resource-holding potential trait? Fighting prowess and changes in startle response in the sea anemone,Actinia equina

Contest theory predicts the evolution of a stable mixture of different strategies for fighting. Here, we investigate the possibility that stable between-individual differences in startle-response durations influence fighting ability or 'resource-holding potential' (RHP) in the beadlet sea anemone, Actinia equina. Both winners and losers showed significant repeatability of pre-fight startle-response durations but mean pre-fight startle-response durations were greater for eventual losers than for eventual winners, indicating that RHP varies with boldness. In particular, individuals with short startle responses inflicted more attacks on their opponent. Both repeatability and mean-level responses were changed by the experience of fighting, and these changes varied with outcome. In losers, repeatability was disrupted to a greater extent and the mean startle-response durations were subject to a greater increase than in winners. Thus, following a fight, this behavioural correlate of RHP behaves in a way similar to post-fight changes in physiological status, which can also vary between winners and losers. Understanding the links between aggression and boldness therefore has the potential to enhance our understanding of both the evolution of animal personality and the 'winner and loser effects' of post-fight changes in RHP.     

β-Alanine Biosynthesis in Methanocaldococcus jannaschii

One efficient approach to assigning function to unannotated genes is to establish the enzymes that are missing in known biosynthetic pathways. One group of such pathways is those involved in coenzyme biosynthesis. In the case of the methanogenic archaeon Methanocaldococcus jannaschii as well as most methanogens, none of the expected enzymes for the biosynthesis of the β-alanine and pantoic acid moieties required for coenzyme A are annotated. To identify the gene(s) for β-alanine biosynthesis, we have established the pathway for the formation of β-alanine in this organism after experimentally eliminating other known and proposed pathways to β-alanine from malonate semialdehyde, l-alanine, spermine, dihydrouracil, and acryloyl-coenzyme A (CoA). Our data showed that the decarboxylation of aspartate was the only source of β-alanine in cell extracts of M. jannaschii. Unlike other prokaryotes where the enzyme producing β-alanine from l-aspartate is a pyruvoyl-containing l-aspartate decarboxylase (PanD), the enzyme in M. jannaschii is a pyridoxal phosphate (PLP)-dependent l-aspartate decarboxylase encoded by MJ0050, the same enzyme that was found to decarboxylate tyrosine for methanofuran biosynthesis. A K_m of ∼0.80 mM for l-aspartate with a specific activity of 0.09 μmol min⁻¹ mg⁻¹ at 70°C for the decarboxylation of l-aspartate was measured for the recombinant enzyme. The MJ0050 gene was also demonstrated to complement the Escherichia coli panD deletion mutant cells, in which panD encoding aspartate decarboxylase in E. coli had been knocked out, thus confirming the function of this gene in vivo.     

Effects of high irradiances on photosynthesis,growth and crassulacean acid metabolism in the epiphyteKalanchoö uniflora

Summary Kalancho? uniflora was grown in the glasshouse with and without shading. Chlorophyll content, area/FW ratio and specific leaf area were higher in leaves of shaded as compared to unshaded plants. Light saturation curves and continuous gas exchange measurements showed that the apparent quantum yield and the light-saturated photosynthetic rate were higher in shaded plants. Shaded plants had lower “mesophyll resistances” than unshaded plants, indicating that the different photosynthetic capacities reflected different contents of ribulose biphosphate carboxylase-oxygenase. Highlight treatment of plants grown in the shade resulted in a decreased photosynthetic efficiency, showing that these plants were sensitive to photoinhibition. However, dry matter production was higher in unshaded than in shaded plants. Obviously the difference in irradiance between the two growth regimes did more than offset the differences in photosynthetic efficiency. Applying additional nutrients did not alter the effects of high PFDs. The results are discussed in respect to photosynthetic performence and plant distribution in the epiphytic habitat.     

Myocardial oxidative stress, osteogenic phenotype, and energy metabolism are differentially involved in the initiation and early progression of δ-sarcoglycan-null cardiomyopathy

Dilated cardiomyopathy (DCM) is a common cause of heart failure, and identification of early pathogenic events occurring prior to the onset of cardiac dysfunction is of mechanistic, diagnostic, and therapeutic importance. The work characterized early biochemical pathogenesis in TO2 strain hamsters lacking delta-sarcoglycan. Although the TO2 hamster heart exhibits normal function at 1 month of age (presymptomatic stage), elevated levels of myeloperoxidase, monocyte chemotactic protein-1, malondialdehyde, osteopontin, and alkaline phosphatase were evident, indicating the presence of inflammation, oxidative stress, and osteogenic phenotype. These changes were localized primarily to the myocardium. Derangement in energy metabolism was identified at the symptomatic stage (4 month), and is marked by attenuated activity and expression of pyruvate dehydrogenase E1 subunit, which catalyzes the rate-limiting step in aerobic glucose metabolism. Thus, this study illustrates differential involvement of oxidative stress, osteogenic phenotype, and glucose metabolism in the initiation and early progression of delta-sarcoglycan-null DCM.     

Energetic metabolism,stress, and immunity—development of population physiology

This review shows that the interpenetration of population ecology and animal physiology positively affects the both scientific directions that are important fields of modern zoology. Due to progress in the development of telemetry and non-invasive methods to assess the animal state, as well as of moleculargenetic methods that permit to distinguish the markers reflecting the individual history of an individual, the possibilities of studying responses of an organism to environmental impacts have been greatly expanded. The combined use of traditional ecological and modern physiological, immunological, and molecular-genetic methods promotes to reveal mechanisms responsible for the stable existence of population in the dynamic environment. In addition, the analysis of the contribution of physiological and immunological processes to the formation of adaptations on the population level is a requirement to understand their adaptive importance, which is not always evident when considering a problem at the organism-centric level.     

Poly-β-hydroxybutyrate biosynthesis and the regulation of glucose metabolism in Azotobacter beijerinckii

Azotobacter beijerinckii possesses the enzymes of both the Entner-Doudoroff and the oxidative pentose phosphate cycle pathways of glucose catabolism and both pathways are subject to feedback inhibition by products of glucose oxidation. The allosteric glucose 6-phosphate dehydrogenase utilizes both NADP(+) and NAD(+) as electron acceptors and is inhibited by ATP, ADP, NADH and NADPH. 6-Phosphogluconate dehydrogenase (NADP-specific) is unaffected by adenosine nucleotides but is strongly inhibited by NADH and NADPH. The formation of pyruvate and glyceraldehyde 3-phosphate from 6-phosphogluconate by the action of the Entner-Doudoroff enzymes is inhibited by ATP, citrate, isocitrate and cis-aconitate. Glyceraldehyde 3-phosphate dehydrogenase is unaffected by adenosine and nicotinamide nucleotides but the enzyme is non-specific with respect to NADP and NAD. Citrate synthase is strongly inhibited by NADH and the inhibition is reversed by the addition of AMP. Isocitrate dehydrogenase, a highly active NADP-specific enzyme, is inhibited by NADPH, NADH, ATP and by high concentrations of NADP(+). These findings are discussed in relation to the massive synthesis of poly-beta-hydroxybutyrate that occurs under certain nutritional conditions. We propose that synthesis of this reserve material, to the extent of 70% of the dry weight of the organism, serves as an electron and carbon ;sink' when conditions prevail that would otherwise inhibit nitrogen fixation and growth.     

Luxury in freshwater and stress at sea? The foraging of the Common Tern Sterna hirundo

We compared the foraging strategies of Common Terns Sterna hirundo in freshwater (Lake Jeziorsko, Brzeg, Poland) and marine environments (Minsener Oldeoog, German Wadden Sea). Body mass changes, nest relief and duration and number of feeding trips per day were studied by automatically weighing the adults, using electronic balances under the nests. At the freshwater site, adults were lighter both before and after feeding and gained less mass during a trip. in the Wadden Sea, single feeding trips lasted longer than at the freshwater site and the terns made fewer trips per day. To achieve the same mass gain per day as in birds in freshwater, trips at sea had to be longer and food intake per trip was higher. The daily duration of absence for feeding and the daily mass gain were about the same in both areas. The limnetic feeders finished foraging earlier in the evening than the terns foraging at sea. These differences are consistent with the hypothesis that limnetic prey availability was consistent, whereas the tides limited the availability of marine prey. In consequence, foraging over freshwater presents several advantages, such as higher colony attendance, better mate coordination and better parental care.     

Do reproductive tactics vary with habitat heterogeneity in the intertidal sea anemone Actinia tenebrosa?

Cnidarians display a diverse range of reproductive tactics including sexual and asexual modes of reproduction. Although few studies have looked for intraspecific variation in reproductive tactics, flexible expression of such life-history traits may be favoured in species that occupy a range of habitats. We tested this in the sea anemone Actinia tenebrosa by comparing cycles of reproductive activity and the mode of production of brooded larvae in local populations occupying boulder fields and stable rock platforms. We determined the mode of production of broods from eight rock platforms (separated by up to 1600 km) and two boulder shores on the south east coast of Australia using a combination of allozyme data and four newly characterised microsatellite markers.

We determined seasonal patterns of brooding and gonad development by monthly dissection of 15–30 adults from each of two boulder fields and two stable platforms. Previous genetic studies have shown that populations of A. tenebrosa on rock platforms can be highly clonal, whereas anemones on more heterogeneous boulder habitats display levels of genotypic diversity similar to that expected for sexual reproduction. We genotyped a total of 221 juveniles from 37 brooding adults including 11 broods and 80 juveniles from boulder shores. We did not detect any evidence of sexual production of broods. All brooded juveniles displayed identical multi-locus genotypes to their brood parent irrespective of habitat of origin or location, including 28 broods (200 juveniles) that were heterozygous at one or more locus. Similarly, we found that temporal patterns of gonad formation and brooding were consistent across habitats and locations. We detected 346 mature males, 234 non-reproductive or immature individuals, and no mature females within a total of 580 dissected individuals. These data suggest that the reproductive tactics of A. tenebrosa are essentially fixed and that variation in the genotypic diversity of populations may reflect variation in factors such as the input of sexually derived planktonically dispersed recruits or post-settlement processes. However, the apparent lack of females paradoxically implies that sexual reproduction, and hence recruitment, must be rare or no longer possible within some populations, and highlights the need for long-term studies of these populations.     

Nitric oxide-induced salt stress tolerance in plants: ROS metabolism,signaling, and molecular interactions

Nitric oxide (NO), a non-charged, small, gaseous free-radical, is a signaling molecule in all plant cells. Several studies have proposed multifarious physiological roles for NO, from seed germination to plant maturation and senescence. Nitric oxide is thought to act as an antioxidant, quenching ROS during oxidative stress and reducing lipid peroxidation. NO also mediates photosynthesis and stomatal conductance and regulates programmed cell death, thus providing tolerance to abiotic stress. In mitochondria, NO participates in the electron transport pathway. Nitric oxide synthase and nitrate reductase are the key enzymes involved in NO-biosynthesis in aerobic plants, but non-enzymatic pathways have been reported as well. Nitric oxide can interact with a broad range of molecules, leading to the modification of protein activity, GSH biosynthesis, S-nitrosylation, peroxynitrite formation, proline accumulation, etc., to sustain stress tolerance. In addition to these interactions, NO interacts with fatty acids to form nitro-fatty acids as signals for antioxidant defense. Polyamines and NO interact positively to increase polyamine content and activity. A large number of genes are reprogrammed by NO; among these genes, proline metabolism genes are upregulated. Exogenous NO application is also shown to be involved in salinity tolerance and/or resistance via growth promotion, reversing oxidative damage and maintaining ion homeostasis. This review highlights NO-mediated salinity-stress tolerance in plants, including NO biosynthesis, regulation, and signaling. Nitric oxide-mediated ROS metabolism, antioxidant defense, and gene expression and the interactions of NO with other bioactive molecules are also discussed. We conclude the review with a discussion of unsolved issues and suggestions for future research.     

Structure–function relationships in ShKT domain peptides: ShKT-Ts1 from the sea anemone Telmatactis stephensoni

Diverse structural scaffolds have been described in peptides from sea anemones, with the ShKT domain being a common scaffold first identified in ShK toxin from Stichodactyla helianthus. ShK is a potent blocker of voltage-gated potassium channels (K_V1.x), and an analog, ShK-186 (dalazatide), has completed Phase 1 clinical trials in plaque psoriasis. The ShKT domain has been found in numerous other species, but only a tiny fraction of ShKT domains has been characterized functionally. Despite adopting the canonical ShK fold, some ShKT peptides from sea anemones inhibit K_V1.x, while others do not. Mutagenesis studies have shown that a Lys–Tyr (KY) dyad plays a key role in K_V1.x blockade, although a cationic residue followed by a hydrophobic residue may also suffice. Nevertheless, ShKT peptides displaying an ShK-like fold and containing a KY dyad do not necessarily block potassium channels, so additional criteria are needed to determine whether new ShKT peptides might show activity against potassium channels. In this study, we used a combination of NMR and molecular dynamics (MD) simulations to assess the potential activity of a new ShKT peptide. We determined the structure of ShKT-Ts1, from the sea anemone Telmatactis stephensoni, examined its tissue localization, and investigated its activity against a range of ion channels. As ShKT-Ts1 showed no activity against K_V1.x channels, we used MD simulations to investigate whether solvent exposure of the dyad residues may be informative in rationalizing and potentially predicting the ability of ShKT peptides to block K_V1.x channels. We show that either a buried dyad that does not become exposed during MD simulations, or a partially exposed dyad that becomes buried during MD simulations, correlates with weak or absent activity against K_V1.x channels. Therefore, structure determination coupled with MD simulations, may be used to predict whether new sequences belonging to the ShKT family may act as potassium channel blockers.     

Effects of wild-type and α-tocopherol-enriched transgenic Brassica juncea on the components of xenobiotic metabolism, antioxidant status, and oxidative stress in the liver of mice

Alpha (α)-tocopherol is the most biologically active and preferentially retained form of vitamin E in the human body and is known for its antioxidant and gene regulatory functions. Its increased intake is implicated in protection against diseases that involve an oxidative stress component. We have evaluated the chemopreventive potential of a diet supplemented with natural α-tocopherol-enriched transgenic (TR) Brassica juncea seeds. The modulation of phase I and phase II xenobiotic metabolism and of antioxidative enzymes was compared in the livers of mice fed on a control diet or on a diet supplemented with 2, 4, and 6 % (w/w) of wild-type (WT) or TR seeds. A dose-dependent increase in the specific activities of these enzymes was observed in those animals fed on diet supplemented with TR seeds. In comparison, an increase in the specific activities of antioxidative enzymes was substantial only at higher doses of WT seeds. Consequently, oxidative stress measured in terms of lipid peroxidation and lactate dehydrogenase activity was found to be lower in the case of mice fed with the supplemented diet. However, the chemopreventive potential of TR seeds was more pronounced than that of WT seeds. This study demonstrates the feasibility of fortifying diets with natural α-tocopherol for chemopreventive benefits by means of transgenic manipulation of a commonly used oilseed crop.     

Biotin attenuation of oxidative stress,mitochondrial dysfunction,lipid metabolism alteration and 7β-hydroxycholesterol-induced cell death in 158N murine oligodendrocytes

Mitochondrial dysfunction and oxidative stress are involved in neurodegenerative diseases associated with an enhancement of lipid peroxidation products such as 7β-hydroxycholesterol (7β-OHC). It is, therefore, important to study the ability of 7β-OHC to trigger mitochondrial defects, oxidative stress, metabolic dysfunctions and cell death, which are hallmarks of neurodegeneration, and to identify cytoprotective molecules. The effects of biotin were evaluated on 158N murine oligodendrocytes, which are myelin synthesizing cells, exposed to 7β-OHC (50?µM) with or without biotin (10 and 100?nM) or α-tocopherol (positive control of cytoprotection). The effects of biotin on 7β-OHC activities were determined using different criteria: cell adhesion; plasma membrane integrity; redox status. The impact on mitochondria was characterized by the measurement of transmembrane mitochondrial potential (ΔΨm), reactive oxygen species (ROS) overproduction, mitochondrial mass, quantification of cardiolipins and organic acids. Sterols and fatty acids were also quantified. Cell death (apoptosis, autophagy) was characterized by the enumeration of apoptotic cells, caspase-3 activation, identification of autophagic vesicles, and activation of LC3-I into LC3-II. Biotin attenuates 7β-OHC-induced cytotoxicity: loss of cell adhesion was reduced; antioxidant activities were normalized. ROS overproduction, protein and lipid oxidation products were decreased. Biotin partially restores mitochondrial functions: attenuation of the loss of ΔΨm; reduced levels of mitochondrial O₂^?? overproduction; normalization of cardiolipins and organic acid levels. Biotin also normalizes cholesterol and fatty acid synthesis, and prevents apoptosis and autophagy (oxiapoptophagy). Our data support that biotin, which prevents oligodendrocytes damages, could be useful in the treatment of neurodegeneration and demyelination.     

Similar effects ofβ-alanine and taurine in cholesterol metabolism

β-Alanine, though producing a deficiency of taurine in the tissues, had a similar effect on cholesterol metabolism as taurine. Both caused increased activity of hepatic hydroxymethylglutaryl coenzyme A reductase and increased incorporation of 1, 2 of [¹⁴C]-acetate into liver cholesterol. Both caused increased concentration of biliary cholesterol and bile acids. There was increased activity of lipoprotein lipase in heart, but decreased activity in the adipose tissue in both cases. Release of lipoproteins into circulation was decreased in both cases.     

Phospholipids in the nucleus—metabolism and possible functions

Most of the phospholipids in the nuclear envelope are contained in the double nuclear membrane, and this has an active lipid metabolism consistent with its origins as a component of the endoplasmic reticular system. However, even after removal of the nuclear membrane with detergents, some phospholipids, mostly of unknown location and function, remain. Amongst these are all of the components of what appears to be a nuclear polyphosphoinositide signalling system, distinct from the well-established inositide pathway found in the plasma membrane. The consequences for nuclear function of the activation of these two inositide pathways are discussed, with a detailed consideration of proposed intranuclear functions for protein kinase C, and the maintenance of nuclear Ca²⁺ homoeostasis.     

Assessment of changes in physiological and biochemical traits in four pistachio rootstocks under drought,salinity and drought + salinity stresses

In this study, 7-month-old UCB-1, Badami, Ghazvini and Kale-Ghouchi pistachio rootstocks were exposed to control, drought, salinity and drought + salinity environments for 60 d. Total chlorophyll and total carotenoid contents decreased in all cultivars under drought, salinity and drought + salinity stresses. Under drought and salinity stresses, alone or in combination, Na⁺ and Cl⁻ ions increased in all four pistachio rootstocks, while K⁺ ion decreased only in Ghazvini and Kaleh-Ghouchi cultivars. The enzyme activities of ascorbate peroxidase, polyphenol oxidase, catalase and guaiacol peroxidase increased in all cultivars when subjected to all three stresses with the exception of the ascorbate peroxidase activity in Kale-Ghouchi cultivar during drought stress. Oxidative stress parameters including electrolyte leakage, malondialdehyde, other aldehydes and hydrogen peroxide increased under all three stress conditions in all genotypes. The content of proline, total free amino acids and total soluble carbohydrates were enhanced under drought, salinity and drought + salinity stresses, whereas the protein content decreased in all pistachio rootstocks. In all evaluated traits, except for the K⁺ ion content and APX activity, the highest impacts was seen for drought + salinity > salinity > drought stresses, respectively. For the first time, we have proven that K⁺ ion content has a positive correlation with the ascorbate peroxidase, polyphenol oxidase, catalase and guaiacol peroxidase enzymes activities under drought + salinity stress. Finally, based on the bi-plot and cluster analyses, we have selected the UCB-1 > Badami > Ghazvini > Kale-Ghouchi cultivars as the most tolerant pistachio rootstocks under drought + salinity stress, respectively.