Host,Pathogen, and Environmental Characteristics Predict White-Nose Syndrome Mortality in Captive Little Brown Myotis (Myotis lucifugus)

An estimated 5.7 million or more bats died in North America between 2006 and 2012 due to infection with the fungus Pseudogymnoascus destructans (Pd) that causes white-nose syndrome (WNS) during hibernation. The behavioral and physiological changes associated with hibernation leave bats vulnerable to WNS, but the persistence of bats within the contaminated regions of North America suggests that survival might vary predictably among individuals or in relation to environmental conditions. To investigate variables influencing WNS mortality, we conducted a captive study of 147 little brown myotis (Myotis lucifugus) inoculated with 0, 500, 5 000, 50 000, or 500 000 Pd conidia and hibernated for five months at either 4 or 10°C. We found that female bats were significantly more likely to survive hibernation, as were bats hibernated at 4°C, and bats with greater body condition at the start of hibernation. Although all bats inoculated with Pd exhibited shorter torpor bouts compared to controls, a characteristic of WNS, only bats inoculated with 500 conidia had significantly lower survival odds compared to controls. These data show that host and environmental characteristics are significant predictors of WNS mortality, and that exposure to up to 500 conidia is sufficient to cause a fatal infection. These results also illustrate a need to quantify dynamics of Pd exposure in free-ranging bats, as dynamics of WNS produced in captive studies inoculating bats with several hundred thousand conidia may differ from those in the wild.     

Isolation and identification of siderophores produced by cyanobacteria

Cyanobacteria are one of the most successful and oldest forms of life that are present on Earth. They are prokaryotic photoautotrophic microorganisms that colonize so diverse environments as soil, seawater, and freshwater, but also stones, plants, or extreme habitats such as snow and ice as well as hot springs. This diversity in the type of environment they live in requires a successful adaptation to completely different conditions. For this reason, cyanobacteria form a wide range of different secondary metabolites. In particular, the cyanobacteria living in both freshwater and sea produce many metabolites that have biological activity. In this review, we focus on metabolites called siderophores, which are low molecular weight chemical compounds specifically binding iron ions. They have a relatively low molecular weight and are produced by bacteria and also by fungi. The main role of siderophores is to obtain iron from the environment and to create a soluble complex available to microbial cells. Siderophores play an important role in microbial ecology; for example, in agriculture they support the growth of many plants and increase their production by increasing the availability of Fe in plants. The aim of this review is to demonstrate the modern use of physico-chemical methods for the detection of siderophores in cyanobacteria and the use of these methods for the detection and characterization of the siderophore-producing microorganisms. Using high-performance liquid chromatography-mass spectrometry (LC-MS), it is possible not only to discover new chemical structures but also to identify potential interactions between microorganisms. Based on tandem mass spectrometry (MS/MS) analyses, previous siderophore knowledge can be used to interpret MS/MS data to examine both known and new siderophores.     

RP-HPLC/MS-APCI analysis of odd-chain TAGs from Rhodococcus erythropolis including some regioisomers

We used reversed phase liquid chromatography–atmospheric pressure chemical ionization mass spectrometry (RP-HPLC/MS-APCI) for direct analysis of triacylglycerols (TAGs) from four different cultivations of Rhodococcus erythropolis CCM 2595. This technique enabled us to identify and quantify the specific molecular species of TAGs directly from lipid extracts of the bacterium, including the determination of their basic characteristics such as retention time and mass spectra. A total of 17 TAGs having at least one odd-numbered-chain FA (fatty acid) were found. This is the first time when odd-chain TAGs, predominantly with pentadecanoic, margaric, and margaroleic acids, were identified. Multiple linear regression analyses were used for predicting retention times of molecular species, predominantly of odd-chain TAGs. Cultivations on two different substrates at two different temperatures (20 and 30 °C) showed that only temperature had any effect on the content of TAGs. In cultivations with succinate as a carbon source the content of these TAGs increased by half (i.e., from 23.5 to 34.2%) when the cultivation temperature was lowered from 30 to 20 °C. The content of the PoPoMo, PoMoO and PPoMo (see Table 1) TAGs containing the odd-numbered-chain margaroleic acid rose from 0.0 to 7.1% while in cultivation on phenol as a carbon source the lowering of cultivation temperature caused an increase of these TAGs from 0.5 to 6.7%.     

MAJOR CLADES OF THE ANGIOSPERMS

Abstract— Our knowledge of fundamental angiosperm interrelationships is still very incomplete. The absence of a narrowly circumscribed gymnosperm outgroup, ideally the sister group, makes character evaluation, necessary for a cladistic analysis, difficult. According to current views the superorder Magnoliiflorae with a number of other groups, for example the monocotyledons, may represent a complex of families near the base of the angiosperms. Interrelationships of groups within the monocotyledons are much better understood than those between groups within the dicotyledons. A cladogram of monocotyledon orders based on earlier work by R. Dahlgren, H. T. Clifford, and F. N. Rasmussen is presented. A data matrix for a sample of the angiosperms with 61 characters for 49 taxa, mostly magnoliifloran and related families, is presented. The characters are polarized mainly according to the current view that the primitive angiosperm morphotype is a woody dicotyledon with strobiloid flowers. As an alternative the matrix is adjusted following W. C. Burger's conjecture that the primitive angiosperm was a herbaceous monocotyledon with trimerous flowers. Both matrices were run in a computerized parsimony analysis, resulting in numerous equally parsimonious solutions. This result is illustrative of the great homoplasy in the available character information, and also of how little actually is known about fundamental angiosperm interrelationships or phylogeny.     

<Emphasis Type="Italic">Trachydiscus minutus</Emphasis>, a new biotechnological source of eicosapentaenoic acid

The yellow-green alga Trachydiscus minutus (class Xanthophyta) was cultivated in a standard medium and in media without sulfur and nitrogen. Its yield after a 16-d cultivation reached 13 g dry mass per 1 L medium. The content of oligoenoic (‘polyenoic’) fatty acid (PUFA), i.e. eicosapentaenoic (EPA), was in excess of 35 % of total fatty acids; the productivity was thus 88 mg/L per d. This result makes the alga a very prospective organism that may serve as a new biotechnological source of single cell oil.     

Effects of pH and calcium ion on self-association properties of two dimeric phospholipases A2

The monomer-dimer equilibria of the dimeric phospholipases A2 from Crotalus atrox and Agkistrodon piscivorus piscivorus venoms were examined chromatographically as a function of pH and in the presence versus absence of the essential cofactor, calcium ion. At neutral pH without calcium, the subunits of both enzymes reequilibrated sufficiently slowly that dimer and monomer were separated by size exclusion chromatography. At pH 4.2 and lower, the dimers underwent rapid dissociation and reassociation, eluting as single broad peaks whose position as a function of applied protein concentration could be analyzed to determine association constants using an algorithm that estimates these values based on elution positions. Lowering the pH from 7.0 to 4.2 increased the self-association constant of the C. atrox enzyme by 1 order of magnitude and that of the A. p. piscivorus dimer by a factor of 3. Calcium ion, an essential cofactor of phospholipase A2, converted the kinetic behavior of the dimers at neutral pH from slow to virtually instantaneous on the time scale of the chromatography runs, 40 min. Calcium ion also altered the thermodynamic stability of the enzymes; the association constant of A. p. piscivorus phospholipase A2 in neutral pH buffer was reduced by approximately 2 orders of magnitude, whereas that of C. atrox was increased by a factor of 6. The structural basis for the disparate effects of calcium ion on these two acidic, dimeric venom phospholipases A2 is uncertain. This study illustrates the importance of calcium ion and pH on the solution behavior of the dimeric members of this class of enzymes.     

Rubidium transport in X-irradiated human erythrocytes

Outflow of 86Rb, a radioactive analogue of potassium, from human erythrocytes X-irradiated in vitro was studied with the following results. (1) The 86Rb level in the supernatants of irradiated and control cell suspensions reflected mainly 86Rb outflow and much less its active re-uptake. (2) The effect of irradiation on 86Rb outflow was more pronounced at a low temperature (4 degrees C) than at 37 degrees C; the lowest dose of X-radiation exhibiting a significant effect on 86Rb outflow at 4 degrees C was 2.5 Gy. (3) K/Rb exchange did not seem to play an appreciable role in radiation-induced 86Rb outflow. (4) Calcium and its accumulation in irradiated cells was not found to be the cause of the effect of radiation on 86Rb outflow. (5) The effect of radiation on 86Rb outflow was higher in low Na medium but it was not inhibited by bumetanide. Rb/Na counter- or co-transport do not therefore seem to be involved in radiation-induced Rb+ outflow.     

Protective role of mitochondrial superoxide dismutase against high osmolarity,heat and metalloid stress in<Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

Superoxide dismutases, both cytosolic Cu, Zn-SOD encoded by SOD1 and mitochondrial Mn-SOD encoded by SOD2, serve Saccharomyces cerevisiae cells for defense against the superoxide radical but the phenotypes of sod1A and sod2delta mutant strains are different. Compared with the parent strain and the sod1delta mutant, the sod2delta mutant shows a much more severe growth defect at elevated salt concentrations, which is partially rescued by 2 mmol/L glutathione. The growth of all three strains is reduced at 37 degrees C, the sod2delta showing the highest sensitivity, especially when cultured in air. Addition of 1 mmol/L glutathione to the medium restores aerobic growth of the sod1delta mutant but has only a minor effect on the growth of the sod2delta strain at 37 degrees C. The sod2delta strain is also sensitive to AsIIl and AsV and its sensitivity is much more pronounced under aerobic conditions. These results suggest that, unlike the Sodlp protein, whose major role is oxidative stress defense, Sod2p also plays a role in protecting S. cerevisiae cells against other stresses--high osmolarity, heat and metalloid stress.