Selective olfactory attention of a specialised predator to intraspecific chemical signals of its prey

Prey-specialised predators have evolved specific cognitive adaptations that increase their prey searching efficiency. In particular, when the prey is social, selection probably favours the use of prey intraspecific chemical signals by predatory arthropods. Using a specialised ant-eating zodariid spider, Zodarion rubidum, which is known to prey on several ant species and possesses capture and venom adaptations more effective on Formicinae ants, we tested its ability to recognise chemical cues produced by several ant species. Using an olfactometer, we tested the response of Z. rubidum towards air with chemical cues from six different ant species: Camponotus ligniperda, Lasius platythorax and Formica rufibarbis (all Formicinae); and Messor structor, Myrmica scabrinodis and Tetramorium caespitum (all Myrmicinae). Z. rubidum was attracted to air carrying chemical cues only from F. rufibarbis and L. platythorax. Then, we identified that the spiders were attracted to airborne cues coming from the F. rufibarbis gaster and Dufour's gland, in particular. Finally, we found that among several synthetic blends, the decyl acetate and undecane mixture produced significant attraction of spiders. These chemicals are produced only by three Formicine genera. Furthermore, we investigated the role of these chemical cues in the communication of F. rufibarbis and found that this blend reduces their movement. This study demonstrates the chemical cognitive capacity of Z. rubidum to locate its ant prey using chemical signals produced by the ants. The innate capacity of Z. rubidum to olfactory detect different ant species is narrow, as it includes only two ant genera, confirming trophic specialisation at lower than subfamily level. The olfactory cue detected by Zodarion spiders is probably a component of the recruitment or trail pheromone.     

Armoured spiderman: morphological and behavioural adaptations of a specialised araneophagous predator (Araneae: Palpimanidae)

In a predator–prey system where both intervenients come from the same taxon, one can expect a strong selection on behavioural and morphological traits involved in prey capture. For example, in specialised snake-eating snakes, the predator is unaffetced by the venom of the prey. We predicted that similar adaptations should have evolved in spider-eating (araneophagous) spiders. We investigated potential and actual prey of two Palpimanus spiders (P. gibbulus, P. orientalis) to support the prediction that these are araneophagous predators. Specific behavioural adaptations were investigated using a high-speed camera during staged encounters with prey, while morphological adaptations were investigated using electron microscopy. Both Palpimanus species captured a wide assortment of spider species from various guilds but also a few insect species. Analysis of the potential prey suggested that Palpimanus is a retreat-invading predator that actively searches for spiders that hide in a retreat. Behavioural capture adaptations include a slow, stealthy approach to the prey followed by a very fast attack. Morphological capture adaptations include scopulae on forelegs used in grabbing prey body parts, stout forelegs to hold the prey firmly, and an extremely thick cuticle all over the body preventing injury from a counter bite of the prey. Palpimanus overwhelmed prey that was more than 200% larger than itself. In trials with another araneophagous spider, Cyrba algerina (Salticidae), Palpimanus captured C. algerina in more than 90% of cases independent of the size ratio between the spiders. Evidence indicates that both Palpimanus species possesses remarkable adaptations that increase its efficiency in capturing spider prey.     

Development of a generalist predator,Podisus maculiventris,on glucosinolate sequestering and nonsequestering prey

Insect herbivores exhibit various strategies to counter the toxic effects of plant chemical defenses. These strategies include the detoxification, excretion, and sequestration of plant secondary metabolites. The latter strategy is often considered to provide an additional benefit in that it provides herbivores with protection against natural enemies such as predators. Profiles of sequestered chemicals are influenced by the food plants from which these chemicals are derived. We compared the effects of sequestration and nonsequestration of plant secondary metabolites in two specialist herbivores on the development of a generalist predator, Podisus maculiventris. Profiles of glucosinolates, secondary metabolites characteristic for the Brassicaceae, are known to differ considerably both inter- and intraspecifically. Throughout their immature (=nymphal) development, the predator was fed on larval stages of either sequestering (turnip sawfly, Athalia rosae) or nonsequestering (small cabbage white butterfly, Pieris rapae) prey that in turn had been feeding on plants originating from three wild cabbage (Brassica oleracea) populations that have previously been shown to differ in their glucosinolate profiles. We compared survival, development time, and adult body mass as parameters for bug performance. Our results show that sequestration of glucosinolates by A. rosae only marginally affected the development of P. maculiventris. The effects of plant population on predator performance were variable. We suggest that sequestration of glucosinolates by A. rosae functions not only as a defensive mechanism against some predators, but may also be an alternative way of harmlessly dealing with plant allelochemicals.     

Transmission of ice-nucleating active bacteria from a prey reduces cold hardiness of a predator (Araneae: Theridiidae)

The influence of ice-nucleating active (INA) bacteria on cold hardiness of the house spider, Achaearanea tepidariorum, was determined by measuring the supercooling point (SCP) of hatchlings given either INA-bacteria-fed or bacteria-free prey (Drosophila melanogaster). Spiders that had eaten INA-bacteria-fed flies showed higher SCPs than those fed on bacteria-free flies. Through feeding, INA bacteria in the prey reduce the cold hardiness of spiders. This fact should be taken into account before using INA agents as a means of pest management.     

Visual prey detection by near-infrared cues in a fish

Many animal species are able to perceive light wavelengths beyond those visible to humans. While numerous species are additionally sensitive to short wavelengths (UV), long wavelengths such as the near-infrared spectrum (NIR) are supposed to be unsuitable for visual perception. Here, we experimentally show that under exclusive NIR illumination, the cichlid fish Pelvicachromis taeniatus displays a clear foraging response towards NIR reflecting prey. Additional control experiments without prey indicate that the observed behavior is not a mere response to the NIR environment. These results give first evidence for NIR visual sensitivity in a functional context and thus challenge the current view about NIR perception.     

Field evidence for non-host predator avoidance in a manipulated amphipod

Manipulative parasites are known to alter the spatial distribution of their intermediate hosts in a way that enables trophic transmission to definitive hosts. However, field data on the ecological implications of such changes are lacking. In particular, little is known about the spatial coexistence between infected prey and dead-end predators after a parasite-induced habitat shift. Here, we used an Amphipoda (Gammarus roeseli)–Acanthocephala (Polymorphus minutus) association to investigate how infection with a manipulative parasite affects the predation risk by non-hosts within the invertebrate community. First, we collected invertebrates by sampling various natural habitats and calculated the distribution amplitude of amphipods according to their infection status. Infection with P. minutus significantly reduced the habitat breadth in G. roeseli, parasitised individuals being mainly found in floating materials whereas uninfected ones were widespread throughout the sampled habitats. Second, to test if these changes also affect the risk for P. minutus to be ingested by non-hosts, we estimated the predation risk experienced by G. roeseli within the macro-invertebrate community. The habitat overlap between potential invertebrate predators and G. roeseli showed that the spatial probability of encounter was lower for P. minutus-infected amphipods than for uninfected conspecifics. For the first time, to our knowledge, a study used ecological tools to bring field evidence for the spatial avoidance of dead-end predators in a manipulated amphipod.     

Removal and desorption of chromium in synthetic effluent by a mixed culture in a bioreactor with a magnetic field

Two chromium removal experiments were performed in bioreactors with and without a magnetic field under the same conditions.The release of the chromium present in the biomass was tested in two experiments one with the initial pH of the medium and one with pH 4.0.The objective was to remove Cr(Ⅵ) and total Cr from the effluent,this was carried out by placing biological treatments of synthetic effluent contaminated with 100 mg/L of Cr(Ⅵ) in a bioreactor with neodymium magnets that applied a magneti...     

石墨炉原子吸收光谱法测定海水中的三丁基锡

本文采用石墨炉原子吸收光谱法（ＧＦＡＡＳ）测定海水甲苯抽提液中的三丁基锡。文中考察了１４种基体改进剂对灵敏度的影响，选出了能显著提高测定灵敏度的Ｃａ－Ｃｒ基体改进剂，以０．５／０．１ｍｇ／ｍｌ的浓度比例对８个实样进行了测定，其相对标准偏差（ＲＳＤ）为３％，其特征浓度为７ｐｇ，回收率在８８％￣１０４％之间，成功地应用于近海沉积物对三丁基锡吸附规律的研究。     

Anencephaly in a fetus with osteogenesis imperfecta: Early diagnosis by transvaginal sonography

Early prenatal diagnosis of osteogenesis imperfecta at 14 weeks' gestation by transvaginal sonography is reported. An anencephalic fetus was found at autopsy, although on sonographic examination complete brain tissue had been observed. A possible explanation for these findings and theories on the pathogenesis of anencephaly are discussed.     

Trophic interactions of the endangered Southern river otter (Lontra provocax) in a Chilean Ramsar wetland inferred from prey sampling, fecal analysis, and stable isotopes

Non-invasive methodological approaches are highly recommended and commonly used to study the feeding ecology of elusive and threatened mammals. In this study, we use multiple lines of evidence to assess the feeding strategies of the endangered Southern river otter, by determining seasonal prey availability (electrofishing), analysis of undigested prey remains (spraints), and the use of stable isotopes (δ¹⁵N and δ¹³C) in otter spraints (n?=?262) and prey in a wetland ecosystem of southern Chile (39°49′S, 73°15′W). Fecal and isotopic analyses suggest that the otter diet is restricted to a few prey items, particularly the less-mobile, bottom-living, and larger prey such as crayfish (Samastacus spinifrons, 86.11 %) and crabs (Aegla spp., 32.45 %), supplemented opportunistically by cyprinids (Cyprinus carpio, 9.55 %) and catfish (Diplomystes camposensis, 5.66 %). The results suggest that the river otter is highly specialized in bottom foraging. Isotopic signatures of food sources and feces revealed a mid-upper trophic position for the Southern river otter, with either higher or lower δ¹⁵N values than their potential prey items. δ¹³C values for river otters were less enriched than their potential food resources. We suggest that due to their narrow trophic niche and possible dependence on only a few food items, this species may be highly vulnerable to the reduction in its prey populations. Finally, maintaining the ecological interactions between Southern river otters and their prey is considered a central priority for the survival of this endangered carnivore mammal.     

不同背景气体下非平衡等离子体去除NO实验

设计了一套高压电源和柱-筒反应器装置,在不同的背景气体下进行了介质阻挡放电脱硝的实验研究,主要探讨了放电电压、含氧量、停留时间和功率对NO去除率的影响.结果表明:不同背景气体下,放电电压在一定的范围内(氩气:5～7kV;氮气:9～11kV)对NO脱除率有较大影响;氧气的加入对不同背景气体下的脱硝率都有影响,对氩气背景下的NO去除率影响最大;停留时间的增加有利于NO的去除,当停留时间增加到某一个值(7s)后,NO的去除率变化逐渐平缓;达到相同的去除率,氩气背景下的功率远远小于氮气背景,功率的增加有利于NO的去除;合理选择背景气体有利于NO去除率的提高和能耗的降低.     

限制分配模型预测黑麦草吸收PAHs

采用水培体系检验了限制分配模型预测黑麦草同时吸收苊、芴、菲和芘4种多环芳烃(PAHs)的准确性.结果表明,限制分配模型能够较好地预测黑麦草吸收积累PAHs的程度.但由于该模型仅考虑根部传输,忽略了叶面吸收,导致模型对茎叶中PAHs含量预测的准确性较差.根系和茎叶的预测误差(预测值与实测值之差除以实测值的百分数)分别小于57.4%和98.5%.若考虑叶面吸收对模型预测的影响,则能显著降低茎叶中4种PAHs的预测误差.由于叶面吸收的影响随PAHs脂溶性升高而增大,预测误差降低程度为芘>菲>芴>苊,其中芘的最大预测误差由98.5%下降至69.4%.     

Nafion修饰电极计时电位溶出法测定水中硝基苯的研究

以Ｎａｆｉｏｎ修饰电极时电位溶出法测定水中硝基苯。讨论了测定条件及富集和电极反应机理。方法的线性范围为２．０－３１μｍｏｌ／ｌ。最低检出浓度为０．９８μｍｏｌ／ｌ；８次平行测定的相对标准偏差为３．４％：回收率为９４．８％－９５．８％。     

Prenatal diagnosis in a family with mitochondrial acetoacetyl-coenzyme a thiolase deficiency with the use of the polymerase chain reaction followed by the heteroduplex detection method

Mitochondrial acetoacetyl-coenzyme A (CoA) thiolase deficiency is an organic aciduria which affects isoleucine and ketone body catabolism. GK16 (the index patient) was affected with this disorder and previous studies had revealed that GK16 was a compound heterozygote with IVS8(+1) gt to tt and A301P mutations. In a subsequent pregnancy, prenatal diagnosis was performed and the fetus's amniocytes were analysed by the polymerase chain reaction (PCR) followed by the heteroduplex detection method on a Mutation Detection Enhancement gel. The fetus was identified as a carrier of the IVS8(+1) mutation. We confirmed the diagnosis by immunoblot analysis of extracted amniocytes and gene analysis with blood filter paper after delivery. This is the first report of prenatal diagnosis of this disorder at the gene level.