Aeroecology meets aviation safety: early warning systems in Europe and the Middle East prevent collisions between birds and aircraft

The aerosphere is utilized by billions of birds, moving for different reasons and from short to great distances spanning tens of thousands of kilometres. The aerosphere, however, is also utilized by aviation which leads to increasing conflicts in and around airfields as well as en‐route. Collisions between birds and aircraft cost billions of euros annually and, in some cases, result in the loss of human lives. Simultaneously, aviation has diverse negative impacts on wildlife. During avian migration, due to the sheer numbers of birds in the air, the risk of bird strikes becomes particularly acute for low‐flying aircraft, especially during military training flights. Over the last few decades, air forces across Europe and the Middle East have been developing solutions that integrate ecological research and aviation policy to reduce mutual negative interactions between birds and aircraft. In this paper we 1) provide a brief overview of the systems currently used in military aviation to monitor bird migration movements in the aerosphere, 2) provide a brief overview of the impact of bird strikes on military low‐level operations, and 3) estimate the effectiveness of migration monitoring systems in bird strike avoidance. We compare systems from the Netherlands, Belgium, Germany, Poland and Israel, which are all areas that Palearctic migrants cross twice a year in huge numbers. We show that the en‐route bird strikes have decreased considerably in countries where avoidance systems have been implemented, and that consequently bird strikes are on average 45% less frequent in countries with implemented avoidance systems in place. We conclude by showing the roles of operational weather radar networks, forecast models and international and interdisciplinary collaboration to create safer skies for aviation and birds.     

Size matters in quantitative radar monitoring of animal migration: estimating monitored volume from wingbeat frequency

Quantitative radar studies are an important component of studying the movements of birds. Whether a bird, at a certain distance from the radar, is detected or not depends on its size. The volume monitored by the radar is therefore different for birds of different sizes. Consequently, an accurate quantification of bird movements recorded by small‐scale radar requires an accurate determination of the monitored volume for the objects in question, although this has tended to be ignored. Here, we demonstrate the importance of sensitivity settings for echo detection on the estimated movement intensities of birds of different sizes. The amount of energy reflected from a bird and detected by the radar receiver (echo power) depends not only on the bird's size and on the distance from the radar antenna, but also on the beam shape and the bird's position within this beam. We propose a method to estimate the size of a bird based on the wingbeat frequency, retrieved from the echo‐signal, independent of the absolute echo power. The estimated bird‐size allows calculation of size‐specific monitored volumes, allowing accurate quantification of movement intensities. We further investigate the importance of applying size‐specific monitored volumes to quantify avian movements instead of using echo counts. We also highlight the importance of accounting for size‐specific monitored volume of small scale radar systems, and the necessity of reporting technical information on radar parameters. Applying this framework will increase the quality and validity of quantitative radar monitoring.     

Importance of calcium for the binding of oviductal fluid proteins to the membranes of bovine spermatozoa

Our laboratory has recently shown that in vitro-cultured oviductal cells secrete sperm motility maintaining factor(s). Since the binding of oviductal proteins to spermatozoa (SPZ) has been demonstrated in many species, the motility factor was postulated to bind the membranes of SPZ. Therefore, the current study was performed to evaluate which proteins from in vivo oviductal secretions bind to sperm membranes, to characterize binding conditions, and to evaluate the effect of this binding on sperm survival. Bovine oviducts were dissected, and oviductal cells and fluid were collected by pressing the oviductal tube with a glass slide. This mixture was incubated in Tris-EDTA buffer at 37°C for 30 min, and the cells were washed twice by centrifugation. The supernatant containing oviductal fluid proteins (OFP) was reserved, filtered, frozen (for later motility tests), or lyophilized and labeled with ¹²⁵|. Frozen-thawed SPZ were incubated either immediately, following capacitation, ionophore-induced acrosome reaction, death by heating, or flagellar removal with labeled OFP for 30 min. The resulting pellet after three washes was dissolved in SDS and submitted to 10% SDS-PAGE. An autoradiogram showed that 72, 66, 39, 38, and 36 kDa proteins bind strongly to the five types of SPZ used, and that this binding is very specific, since unlabeled OFP inhibited binding while serum proteins did not. Furthermore, for 39, 38, and 36 kDa proteins, the presence of calcium in the incubation medium was essential for dose-dependent binding, whereas magnesium was not. Preincubation of SPZ for 30 min at 37°C with oviductal fluid, followed by one wash and 6 hr of incubation in control media, showed that the percentage of motile SPZ is significantly higher (52 ± 6%) compared with SPZ not preincubated with oviductal fluid (24 ± 6%: P < 0.01). In summary, a limited number of proteins from oviductal secretions bind to the surface of bovine SPZ only in the presence of calcium, and this binding appears to be important for subsequent sperm viability. © 1996 Wiley-Liss, Inc.     

DNA content analysis of insect cell lines by flow cytometry

The DNA content of insect cell lines (6 lepidoptera, 1 coleoptera and 1 diptera) was determined by flow cytometry. The DNA profiles of the 8 cell lines tested were different. They were characterized by the presence of several peaks (2 to 7) corresponding to different ploidy levels, by differences in the fluorescence intensity of each peak and by the proportion of cells in each peak. Two cell lines (Cf124 and BmN) were constituted of 2 distinct populations of cells. The DNA profiles of the cell lines were stable among the passages and during the length of time culture. This technique was demonstrated to be useful for the detection of mixed cell lines and nucleopolyhedrovirus cell infection, using Autographa californica MNPV. The flow cytometry gives interesting results on the cell cycle and the ploidy level; it appears as a good tool for insect cell lines characterization. This revised version was published online in July 2006 with corrections to the Cover Date.     

Biodegradation of gasoline and BTEX in a microaerophilic biobarrier

Continuous bioremediation of gasoline-contaminatedwater in a packed-bed biobarrier system underoxygen-limited conditions is discussed. This studywas part of an extensive effort to develop analternative technology for the in situbioremediation of hydrocarbons where there is alimited supply of oxygen. Protruded stainless steelpieces and granulated peat moss were used as packingmaterial to support microbial growth in twobiobarriers. The inoculum was an enrichment culture ofan indigenous microbial population from a soil sample.The biobarriers' inlet gasoline concentrations and thelinear liquid velocities were similar to thosecommonly found at in situ conditions. Gasolineremoval efficiencies ranged from 94% to 99.9% in thestainless steel-packed biobarrier, and from 86.6% to99.6% in the peat moss-packed biobarrier. Effluentgasoline concentrations below 0.03 mg/l were obtainedat gasoline loading rates less than 27.5 mg/l.d in thestainless steel-packed biobarrier. The remainingfraction of gasoline in the effluent consisted mainlyof three aliphatic compounds and not the aromaticcompounds. Both biobarrier packings supported nearcomplete removal of the most soluble aromatichydrocarbons of gasoline (BTEX) under all theconditions examined. The consumption of sulfate andthe presence of sulfate-reducing microorganismssuggested the presence of anaerobic metabolism duringthe degradation of gasoline. Up to 92% gasoline wasremoved during the first 3 cm of the biobarriers'length.     

Pyridoxal 5'-phosphate inactivates DNA topoisomerase IB by modifying the lysine general acid

The present results demonstrate that pyridoxal, pyridoxal 5′-phosphate (PLP) and pyridoxal 5′-diphospho-5′-adenosine (PLP-AMP) inhibit Candida guilliermondii and human DNA topoisomerases I in forming an aldimine with the ε-amino group of an active site lysine. PLP acts as a competitive inhibitor of C.guilliermondii topoisomerase I (K_i = 40 μM) that blocks the cleavable complex formation. Chemical reduction of PLP-treated enzyme reveals incorporation of 1 mol of PLP per mol of protein. The limited trypsic proteolysis releases a 17 residue peptide bearing a lysine-bound PLP (KPPNTVIFDFLGK^*DSIR). Targeted lysine (K^*) in C.guilliermondii topoisomerase I corresponds to that found in topoisomerase I of Homo sapiens (K₅₃₂), Candida albicans (K₄₆₈), Saccharomyces cerevisiae (K₄₅₈) and Schizosaccharomyces pombe (K₅₀₅). In the human enzyme, K₅₃₂, belonging to the active site acts as a general acid catalyst and is therefore essential for activity. The spatial orientation of K₅₃₂–PLP within the active site was approached by molecular modeling using available crystallographic data. The PLP moiety was found at close proximity of several active residues. PLP could be involved in the cellular control of topoisomerases IB. It constitutes an efficient tool to explore topoisomerase IB dynamics during catalysis and is also a lead for new drugs that trap the lysine general acid.     

Catalytic and DNA-binding properties of the human Ogg1 DNA N-glycosylase/AP lyase: biochemical exploration of H270, Q315 and F319, three amino acids of the 8-oxoguanine-binding pocket

The human Ogg1 protein (hOgg1) is an antimutator DNA glycosylase/AP lyase that catalyzes the excision of 8-oxo-7,8-dihydroguanine (8-oxoG) and the incision of apurinic and apyrimidinic (AP) sites in DNA. In this study, we have investigated the functional role of H270, Q315 and F319, three amino acids that are located in the 8-oxoG-binding pocket of hOgg1. Wild-type and mutant hOgg1 proteins (H270A, H270R, H270L, Q315A and F319A) were purified to apparent homogeneity. The catalytic activities and the DNA-binding properties of the various hOgg1 mutants were compared to those of the wild-type. The results show that hOgg1 mutated at H270 (H270A and H270L) or F319 (F319A) exhibits greatly reduced (50- to 1000-fold) DNA glycosylase activity, whereas the AP lyase activity is only moderately affected (<4-fold). The affinity of the hOgg1 mutants (H270A, H270L and F319A) for 8-oxoG.C-containing DNA is also greatly reduced (>30-fold), whereas their affinity for THF.C-containing DNA is only moderately reduced (<7-fold). The results also show that hOgg1 mutated at Q315 (Q315A) exhibits catalytic and DNA-binding properties similar to those of the wild-type. Therefore, H270 and F319 are essential to form the functional 8-oxoG-binding pocket, whereas Q315 is less crucial. In contrast, H270, Q315 and F319 are not required for efficient binding of THF.C and cleavage of AP sites. Finally, hOgg1 mutant proteins with a substitution of H270A or F319A are members of a new type of hOgg1 that is deficient in DNA glycosylase but proficient in AP lyase.