The detection and attribution of extreme reductions in vegetation growth across the global land surface

Negative extreme anomalies in vegetation growth (NEGs) usually indicate severely impaired ecosystem services. These NEGs can result from diverse natural and anthropogenic causes, especially climate extremes (CEs). However, the relationship between NEGs and many types of CEs remains largely unknown at regional and global scales. Here, with satellite-derived vegetation index data and supporting tree-ring chronologies, we identify periods of NEGs from 1981 to 2015 across the global land surface. We find 70% of these NEGs are attributable to five types of CEs and their combinations, with compound CEs generally more detrimental than individual ones. More importantly, we find that dominant CEs for NEGs vary by biome and region. Specifically, cold and/or wet extremes dominate NEGs in temperate mountains and high latitudes, whereas soil drought and related compound extremes are primarily responsible for NEGs in wet tropical, arid and semi-arid regions. Key characteristics (e.g., the frequency, intensity and duration of CEs, and the vulnerability of vegetation) that determine the dominance of CEs are also region- and biome-dependent. For example, in the wet tropics, dominant individual CEs have both higher intensity and longer duration than non-dominant ones. However, in the dry tropics and some temperate regions, a longer CE duration is more important than higher intensity. Our work provides the first global accounting of the attribution of NEGs to diverse climatic extremes. Our analysis has important implications for developing climate-specific disaster prevention and mitigation plans among different regions of the globe in a changing climate.     

PocketOptimizer 2.0: A modular framework for computer-aided ligand-binding design

The ability to design customized proteins to perform specific tasks is of great interest. We are particularly interested in the design of sensitive and specific small molecule ligand-binding proteins for biotechnological or biomedical applications. Computational methods can narrow down the immense combinatorial space to find the best solution and thus provide starting points for experimental procedures. However, success rates strongly depend on accurate modeling and energetic evaluation. Not only intra- but also intermolecular interactions have to be considered. To address this problem, we developed PocketOptimizer, a modular computational protein design pipeline, that predicts mutations in the binding pockets of proteins to increase affinity for a specific ligand. Its modularity enables users to compare different combinations of force fields, rotamer libraries, and scoring functions. Here, we present a much-improved version––PocketOptimizer 2.0. We implemented a cleaner user interface, an extended architecture with more supported tools, such as force fields and scoring functions, a backbone-dependent rotamer library, as well as different improvements in the underlying algorithms. Version 2.0 was tested against a benchmark of design cases and assessed in comparison to the first version. Our results show how newly implemented features such as the new rotamer library can lead to improved prediction accuracy. Therefore, we believe that PocketOptimizer 2.0, with its many new and improved functionalities, provides a robust and versatile environment for the design of small molecule-binding pockets in proteins. It is widely applicable and extendible due to its modular framework. PocketOptimizer 2.0 can be downloaded at https://github.com/Hoecker-Lab/pocketoptimizer .     

Anti-predator defences of a web-building spider, Holocnemus pluchei (Araneae, Pholcidae)

Anti-predator defence behaviour of Holocnemus pluchei (Araneae, Pholcidae) was studied in the laboratory and the field. Bouncing, in which this web-building spider moves its body rapidly up and down while keeping its legs on the silk, was the most frequent response to disturbance. Less often, H. pluchei left the web when disturbed. Experiments were carried out to determine the types of stimuli that elicited bouncing and leaving the web: tactile stimulation (striking the spider with a brush) and air movement (blowing on the spider) elicited bouncing and leaving the web, but there was no evidence that chemical stimuli from potential predators were important. Tactile stimulation elicited stronger responses than air movement. There were no evident differences in how H. pluchei responded to tactile stimulation in the laboratory and the field.     

A PERSISTENT VIRUS INFECTION IN FELDMANNIA (PHAEOPHYCEAE)1

A virus infection is described within the unilocular sporangia of Feldmannia sp., a filamentous brown alga (Phaeophyceae). The alga is easily maintained in culture and vegetative growth is vigorous, but formation of icosahedral virions 150 nm in diameter completely displaces production of zoospores. The viruses, estimated at 1–5 × 10⁶ per sporangium, are eventually released by rupture of the sporangial wall. Deoxyribonucleic acid (DNA) isolated from the viruses can be readily digested with restriction endonucleases and consists of ca. 170 kbp of double-stranded DNA.     

Sex differences in heritability of BMI: a comparative study of results from twin studies in eight countries.

Body mass index (BMI), a simple anthropometric measure, is the most frequently used measure of adiposity and has been instrumental in documenting the worldwide increase in the prevalence of obesity witnessed during the last decades. Although this increase in overweight and obesity is thought to be mainly due to environmental changes, i.e., sedentary lifestyles and high caloric diets, consistent evidence from twin studies demonstrates high heritability and the importance of genetic differences for normal variation in BMI. We analysed self-reported data on BMI from approximately 37,000 complete twin pairs (including opposite sex pairs) aged 20-29 and 30-39 from eight different twin registries participating in the GenomEUtwin project. Quantitative genetic analyses were conducted and sex differences were explored. Variation in BMI was greater for women than for men, and in both sexes was primarily explained by additive genetic variance in all countries. Sex differences in the variance components were consistently significant. Results from analyses of opposite sex pairs also showed evidence of sex-specific genetic effects suggesting there may be some differences between men and women in the genetic factors that influence variation in BMI. These results encourage the continued search for genes of importance to the body composition and the development of obesity. Furthermore, they suggest that strategies to identify predisposing genes may benefit from taking into account potential sex specific effects.     

Heritability of adult body height: a comparative study of twin cohorts in eight countries.

A major component of variation in body height is due to genetic differences, but environmental factors have a substantial contributory effect. In this study we aimed to analyse whether the genetic architecture of body height varies between affluent western societies. We analysed twin data from eight countries comprising 30,111 complete twin pairs by using the univariate genetic model of the Mx statistical package. Body height and zygosity were self-reported in seven populations and measured directly in one population. We found that there was substantial variation in mean body height between countries; body height was least in Italy (177 cm in men and 163 cm in women) and greatest in the Netherlands (184 cm and 171 cm, respectively). In men there was no corresponding variation in heritability of body height, heritability estimates ranging from 0.87 to 0.93 in populations under an additive genes/unique environment (AE) model. Among women the heritability estimates were generally lower than among men with greater variation between countries, ranging from 0.68 to 0.84 when an additive genes/shared environment/unique environment (ACE) model was used. In four populations where an AE model fit equally well or better, heritability ranged from 0.89 to 0.93. This difference between the sexes was mainly due to the effect of the shared environmental component of variance, which appears to be more important among women than among men in our study populations. Our results indicate that, in general, there are only minor differences in the genetic architecture of height between affluent Caucasian populations, especially among men.     

The role of the neurohormone melatonin as a buffer against macromolecular oxidative damage

This paper summarizes the recent findings which show that the neural hormone melatonin is a free radical scavenger and general antioxidant. When compared with other antioxidants melatonin seems to have greater efficacy in protecting against cellular oxidative stress. These findings illustrate that melatonin preserves macromolecules including DNA, protein and lipid from oxidative damage following the administration of the chemical carcinogen, safrole, after exposure to ionizing radiation, following glutathione depletion, and after administration of the free radical generating herbicide, paraquat. In vitro evidence shows that melatonin is a potent scavenger of the highly toxic hydroxyl radical and in vitro evidence suggests that melatonin is an important and powerful antioxidant. Considering its high lipophilicity and its non-toxic nature as well as its ability to readily cross the blood-brain barrier, the neurohormone melatonin may prove to be an effective and important molecule in the antioxidative defense system, especially in the central nervous system. Besides the ease with which melatonin enters the brain, neurons seem to accumulate readily this hormone.     

Active Site Mutations in Yeast Protein Disulfide Isomerase Cause Dithiothreitol Sensitivity and a Reduced Rate of Protein Folding in the Endoplasmic Reticulum

Aspects of protein disulfide isomerase (PDI) function have been studied in yeast in vivo. PDI contains two thioredoxin-like domains, a and a′, each of which contains an active-site CXXC motif. The relative importance of the two domains was analyzed by rendering each one inactive by mutation to SGAS. Such mutations had no significant effect on growth. The domains however, were not equivalent since the rate of folding of carboxypeptidase Y (CPY) in vivo was reduced by inactivation of the a domain but not the a′ domain. To investigate the relevance of PDI redox potential, the G and H positions of each CGHC active site were randomly mutagenized. The resulting mutant PDIs were ranked by their growth phenotype on medium containing increasing concentrations of DTT. The rate of CPY folding in the mutants showed the same ranking as the DTT sensitivity, suggesting that the oxidative power of PDI is an important factor in folding in vivo. Mutants with a PDI that cannot perform oxidation reactions on its own (CGHS) had a strongly reduced growth rate. The growth rates, however, did not correlate with CPY folding, suggesting that the protein(s) required for optimal growth are dependent on PDI for oxidation. pdi1-deleted strains overexpressing the yeast PDI homologue EUG1 are viable. Exchanging the wild-type Eug1p C(L/I)HS active site sequences for C(L/I)HC increased the growth rate significantly, however, further highlighting the importance of the oxidizing function for optimal growth.     

Acutely administered melatonin reduces oxidative damage in lung and brain induced by hyperbaric oxygen

Pablos, Marta I., Russel J. Reiter, Jin-Ing Chuang, GenaroG. Ortiz, Juan M. Guerrero, Ewa Sewerynek, Maria T. Agapito, DanielaMelchiorri, Richard Lawrence, and Susan M. Deneke. Acutely administered melatonin reduces oxidative damage in lung and brain induced by hyperbaric oxygen. J. Appl.Physiol. 83(2): 354-358, 1997.Hyperbaric oxygenexposure rapidly induces lipid peroxidation and cellular damage in avariety of organs. In this study, we demonstrate that the exposure ofrats to 4 atmospheres of 100% oxygen for 90 min is associated withincreased levels of lipid peroxidation products [malonaldehyde(MDA) and 4-hydroxyalkenals (4-HDA)] and withchanges in the activities of two antioxidative enzymes[glutathione peroxidase (GPX) and glutathione reductase (GR)], as well as in the glutathione status in the lungs and in the brain. Products of lipid peroxidation increased after hyperbaric hyperoxia, both GPX and GR activities were decreased, and levels oftotal glutathione (reduced+oxidized) and glutathione disulfide (oxidized glutathione) increased in both lung and brain areas (cerebralcortex, hippocampus, hypothalamus, striatum, and cerebellum) but not inliver. When animals were injected with melatonin (10 mg/kg) immediatelybefore the 90-min hyperbaric oxygen exposure, all measurements ofoxidative damage were prevented and were similar to those in untreatedcontrol animals. Melatonin's actions may be related to a variety ofmechanisms, some of which remain to be identified, including itsability to directly scavenge free radicals and its induction ofantioxidative enzymes via specific melatonin receptors.

     

Melatonin administration prevents lipopolysaccharide-induced oxidative damage in phenobarbital-treated animals

The protective effect of melatonin on lipopolysaccharide (LPS)-induced oxidative damage in phenobarbital-treated rats was measured using the following parameters: changes in total glutathione (tGSH) concentration, levels of oxidized glutathione (GSSG), the activity of the antioxidant enzyme glutathione peroxidase (GSH-PX) in both brain and liver, and the content of cytochrome P450 reductase in liver. Melatonin was injected intraperitoneally (ip, 4mg/kg BW) every hour for 4 h after LPS administration; control animals received 4 injections of diluent. LPS was given (ip, 4 mg/kg) 6 h before the animals were killed. Prior to the LPS injection, animals were pretreated with phenobarbital (PB), a stimulator of cytochrome P450 reductase, at a dose 80 mg/kg BW ip for 3 consecutive days. One group of animals received LPS together with N^w-nitro-L-arginine methyl ester (L-NAME), a blocker of nitric oxide synthase (NOS) (for 4 days given in drinking water at a concentration of 50 mM). In liver, PB, in all groups, increased significantly both the concentration of tGSH and the activity of GSH-PX. When the animals were injected with LPS the levels of tGSH and GSSG were significantly higher compared with other groups while melatonin and L-NAME significantly enhanced tGSH when compared with that in the LPS-treated rats. Melatonin alone reduced GSSG levels and enhanced the activity of GSH-PX in LPS-treated animals. Additionally, LPS diminished the content of cytochrome P450 reductase with this effect being largely prevented by L-NAME administration. Melatonin did not change the content of P450 either in PB- or LPS-treated animals. In brain, melatonin and L-NAME increased both tGSH levels and the activity of GSH-PX in LPS-treated animals. The results suggest that melatonin protects against LPS-induced oxidative toxicity in PB-treated animals in both liver and brain, and the findings are consistent with previously published observations related to the antioxidant activity of the pineal hormone.