Curtailment and acoustic deterrents reduce bat mortality at wind farms

The impacts of wind energy on bat populations is a growing concern because wind turbine blades can strike and kill bats, and wind turbine development is increasing. We tested the effectiveness of 2 management actions at 2 wind-energy facilities for reducing bat fatalities: curtailing turbine operation when wind speeds were <5.0 m/second and combining curtailment with an acoustic bat deterrent developed by NRG Systems. We measured the effectiveness of the management actions using differences in counts of bat carcasses quantified by daily and twice-per-week standardized carcass searches of cleared plots below turbines, and field trials that estimated searcher efficiency and carcass persistence. We studied turbines located at 2 adjacent wind-energy facilities in northeast Illinois, USA, during fall migration (1 Aug–15 Oct) in 2018. We estimated the effectiveness of each management action using a generalized linear mixed-effects model with several covariates. Curtailment alone reduced overall bat mortality by 42.5% but did not reduce silver-haired bat (Lasionycteris noctivagans) mortality. Overall bat fatality rates were 66.9% lower at curtailed turbines with acoustic deterrents compared to turbines that operated at manufacturer cut-in speed. Curtailment and the deterrent reduced bat mortality to varying degrees between species, ranging from 58.1% for eastern red bats (Lasiurus borealis) to 94.4 for big brown bats (Eptesicus fuscus). Hoary (Lasiurus cinereus) and silver-haired bat mortality was reduced by 71.4% and 71.6%, respectively. Our study lacked a deterrent-only treatment group because of the expense of acoustic deterrents. We estimated the additional reduction in mortality with concurrent deployment of the acoustic deterrent and curtailment under the assumption that curtailment and the acoustic deterrent would have reduced mortality by the same percentage at adjacent wind-energy facilities. Acoustic deterrents resulted in 31.6%, 17.4%, and 66.7% additional reductions of bat mortality compared to curtailment alone for eastern red bat, hoary bat, and silver-haired bat, respectively. The effectiveness of acoustic deterrents for reducing bat mortality at turbines with rotor-swept area diameters >110 m is unknown because high frequency sound attenuates quickly, which reduces coverage of rotor-swept areas. Management actions should consider species differences in the ability of curtailment and deterrents to reduce bat mortality and increase energy production.     

An inner membrane enzyme in Salmonella and Escherichia coli that transfers 4-amino-4-deoxy-L-arabinose to lipid A: induction on polymyxin-resistant mutants and role of a novel lipid-linked donor

Attachment of the cationic sugar 4-amino-4-deoxy-l-arabinose (l-Ara4N) to lipid A is required for the maintenance of polymyxin resistance in Escherichia coli and Salmonella typhimurium. The enzymes that synthesize l-Ara4N and transfer it to lipid A have not been identified. We now report an inner membrane enzyme, expressed in polymyxin-resistant mutants, that adds one or two l-Ara4N moieties to lipid A or its immediate precursors. No soluble factors are required. A gene located near minute 51 on the S. typhimurium and E. coli chromosomes (previously termed orf5, pmrK, or yfbI) encodes the l-Ara4N transferase. The enzyme, renamed ArnT, consists of 548 amino acid residues in S. typhimurium with 12 possible membrane-spanning regions. ArnT displays distant similarity to yeast protein mannosyltransferases. ArnT adds two l-Ara4N units to lipid A precursors containing a Kdo disaccharide. However, as shown by mass spectrometry and NMR spectroscopy, it transfers only a single l-Ara4N residue to the 1-phosphate moiety of lipid IV(A), a precursor lacking Kdo. Proteins with full-length sequence similarity to ArnT are present in genomes of other bacteria thought to synthesize l-Ara4N-modified lipid A, including Pseudomonas aeruginosa and Yersinia pestis. As shown in the following article (Trent, M. S., Ribeiro, A. A., Doerrler, W. T., Lin, S., Cotter, R. J., and Raetz, C. R. H. (2001) J. Biol. Chem. 276, 43132-43144), ArnT utilizes the novel lipid undecaprenyl phosphate-alpha-l-Ara4N as its sugar donor, suggesting that l-Ara4N transfer to lipid A occurs on the periplasmic side of the inner membrane.     

Accumulation of a polyisoprene-linked amino sugar in polymyxin-resistant Salmonella typhimurium and Escherichia coli: structural characterization and transfer to lipid A in the periplasm

Polymyxin-resistant mutants of Escherichia coli and Salmonella typhimurium accumulate a novel minor lipid that can donate 4-amino-4-deoxy-l-arabinose units (l-Ara4N) to lipid A. We now report the purification of this lipid from a pss(-) pmrA(C) mutant of E. coli and assign its structure as undecaprenyl phosphate-alpha-l-Ara4N. Approximately 0.2 mg of homogeneous material was isolated from an 8-liter culture by solvent extraction, followed by chromatography on DEAE-cellulose, C18 reverse phase resin, and silicic acid. Matrix-assisted laser desorption ionization/time of flight mass spectrometry in the negative mode yielded a single species [M - H](-) at m/z 977.5, consistent with undecaprenyl phosphate-alpha-l-Ara4N (M(r) = 978.41). (31)P NMR spectroscopy showed a single phosphorus atom at -0.44 ppm characteristic of a phosphodiester linkage. Selective inverse decoupling difference spectroscopy demonstrated that the undecaprenyl phosphate group is attached to the anomeric carbon of the l-Ara4N unit. One- and two-dimensional (1)H NMR studies confirmed the presence of a polyisoprene chain and a sugar moiety with chemical shifts and coupling constants expected for an equatorially substituted arabinopyranoside. Heteronuclear multiple-quantum coherence spectroscopy analysis demonstrated that a nitrogen atom is attached to C-4 of the sugar residue. The purified donor supports in vitro conversion of lipid IV(A) to lipid II(A), which is substituted with a single l-Ara4N moiety. The identification of undecaprenyl phosphate-alpha-l-Ara4N implies that l-Ara4N transfer to lipid A occurs in the periplasm of polymyxin-resistant strains, and establishes a new enzymatic pathway by which Gram-negative bacteria acquire antibiotic resistance.     

Relative sensitivities of repair-deficient mammalian cells for clonogenic survival after alpha-particle irradiation

The clonogenic survival of cells of the radiation-sensitive hamster cell lines irs1, irs2, irs3 and xrs5, representing different DNA repair pathways, was compared to that of their parent lines after alpha-particle irradiation. Measurements of nuclear area were made to calculate the probability of surviving a single alpha-particle traversal, the average number of lethal lesions per track and per unit dose, along with the "intrinsic radiosensitivity" of these cells, allowing for the potential of multiple lethal lesions per traversal. For all cell lines studied, alpha particles were found to be more biologically effective per unit absorbed dose than X rays at inducing cell inactivation. The repair-deficient cells showed an enhanced sensitivity to alpha particles compared to their parent line, but the degree of enhancement was less than for X rays. The reduction in additional sensitivity for alpha-particle irradiation was shown not to be due predominantly to differences in cell geometry limiting the probability of a cell nucleus being traversed. The results suggest that both the nonhomologous end-joining pathway and to a lesser extent the homologous recombination repair pathway play a role in successful repair of alpha-particle-induced damage, although a large proportion of damage is not repaired by either pathway.     

Ribosomal proteins Rps0 and Rps21 of Saccharomyces cerevisiae have overlapping functions in the maturation of the 3' end of 18S rRNA

The Rps0 proteins of Saccharomyces cerevisiae are components of the 40S ribosomal subunit required for maturation of the 3′ end of 18S rRNA. Drosophila and human homologs of the Rps0 proteins physically interact with Rps21 proteins, and decreased expression of both proteins in Drosophila impairs control of cellular proliferation in hematopoietic organs during larval development. Here, we characterize the yeast RPS21A/B genes and show that strains where both genes are disrupted are not viable. Relative to the wild type, cells with disrupted RPS21A or RPS21B genes exhibit a reduction in growth rate, a decrease in free 40S subunits, an increase in the amount of free 60S subunits, and a decrease in polysome size. Ribosomal RNA processing studies reveal RPS21 and RPS0 mutants have virtually identical processing defects. The pattern of processing defects observed in RPS0 and RPS21 mutants is not a general characteristic of strains with suboptimal levels of small subunit ribosomal proteins, since disruption of the RPS18A or RPS18B genes results in related but distinct processing defects. Together, these data link the Rps0 and Rps21 proteins together functionally in promoting maturation of the 3′ end of 18S rRNA and formation of active 40S ribosomal subunits.     

Meningeal worm is a long-lived parasitic nematode in white-tailed deer

A natural infection of the meningeal worm, Parelaphostrongylus tenuis, persisted for at least 3.7 yr in a white-tailed deer (Odocoileus virginianus). The deer was 5-7 yr old and was shedding dorsal-spined nematode larvae at the time of quarantine. Larvae were extracted from all fecal samples collected up to 730 days post-quarantine (dpq) and thereafter only at 862 dpq and at necropsy (1,350 dpq). Live adults of P. tenuis, one male and one female, were recovered from the cranium at necropsy. Parelaphostrongylus tenuis infections are long lived and latent periods may be extended. Our findings reaffirm the need for reliable antemortem diagnosis to identify non-patent P. tenuis infections to prevent inadvertent introduction of infected animals to non-endemic areas.     

A ubiquitously expressed human hexacoordinate hemoglobin

We have identified a new human hemoglobin that we call histoglobin because it is expressed in a wide array of tissues. Histoglobin shares less than 30% identity with the other human hemoglobins, and the gene contains an intron in an unprecedented location. Spectroscopic and kinetic experiments with recombinant human histoglobin indicate that it is a hexacoordinate hemoglobin with significantly different ligand binding characteristics than the other human hexacoordinate hemoglobin, neuroglobin. In contrast to the very high oxygen affinities displayed by most hexacoordinate hemoglobins, the biophysical characteristics of histoglobin indicate that it could facilitate oxygen transport. The discovery of histoglobin demonstrates that humans, like plants, differentially express multiple hexacoordinate hemoglobins.