Reproductive monopoly enforced by sterile police workers in a queenless ant

In societies of totipotent insects, dyadic dominance interactionsgenerate a hierarchy that often underlies an extreme reproductiveskew. Subordinates remain infertile but can maximize their indirectfitness benefits through collective power (worker policing):interference with challenging high-rankers can prevent an untimelyreplacement of the reproductive. However, police workers onlybenefit if they favor individuals with high fertility. In themonogynous queenless ant Streblognathus peetersi, we used behavioral,physiological, and chemical methods to show that police workershave the primary role in the selection of the reproductive,and that they probably use reliable information about fertilityencoded in the cuticular hydrocarbons to make their decision.We successfully decreased an alpha's fertility by using a hormonaltreatment (Pyriproxyfen, a juvenile hormone analogue), and shewas always removed from the hierarchy by police workers. Inthe preceding days, one of the high-rankers became aggressive,although her interactions were not directed at the treated alpha.All treated alphas (n = 10) remained aggressive but ended upimmobilized by low-ranking workers after a median time of 11.5days. By then, the challenging high ranker exhibited dominancebehaviors typical of the alpha rank. In parallel, the cuticularprofile of the treated alpha exhibited predictable and oppositemodifications to that of the challenger's. This is the firststudy that uncouples dominance and fertility in a social insect:it gives a better understanding of the crucial role of sterilehelpers in the control of reproductive skew in animal societies.     

Phytoremediation in the Tropics—The Effect of Crude Oil on the Growth of Tropical Plants

Phytoremediation is a nondestructive, cost-effective in-situ technology to clean up contaminated soils. In the case of contamination with petroleum hydrocarbons, plants enhance microbial degradation of the contaminant in the rhizosphere. The potential of this technology for the tropics should be high due to prevailing climatic conditions favoring plant growth and stimulating microbial activity. Investigations of the potential of tropical plants for phytoremediation, however, are scarce. The present work studied two grasses and six legumes from the eastern savannah of Venezuela on their reaction to crude oil contamination in soil. Results shall help to identify plants with a potential for phytoremediation and subsequent studies. Seedling emergence and biomass production were determined for plants growing in soil contaminated with 0%, 3%, and 5% heavy crude oil. Contamination had, in general, a tendential but not significant negative influence on seedling emergence. Dry matter production was reduced by only a few percent to up to 85%. Furthermore, in some legumes inhibition of nodulation was observed. The grass Brachiaria brizantha and the legumes Centrosema brasilianum and Calopogonium mucunoides are promising for phytoremediation because in contaminated soil they combined high seedling emergence with least affected biomass production. Since they are cultivated forage/soil cover species also in other regions of the tropics, their potential for phytoremediation of petroleum contaminated soils extends beyond Venezuela.     

Do PAHs Pose Unacceptable Ecological Risks to Terrestrial Receptors at Hazardous Waste Sites?

Polycyclic aromatic hydrocarbons (PAHs) are identified as Constituents of Potential Concern (CoPC) at many hazardous waste sites because of disposal, spills, leaking storage tanks, and incineration. The Superfund Public Information System (SPIS) RODs and CERCLIS Information database covering the period fiscal years 1996–1998 were queried for information on PAHs in soils. Forty-five sites were identified that had PAHs in soil. Predominantly, the sites were munitions facilities or military bases. Of the 45 sites, only two concluded that adverse ecological effects were occurring from PAHs. At both sites, the conclusions were based on Hazard Quotients (HQs) exceeding 1.0. For 29 sites, PAHs were characterized “as not posing an adverse effect” to plants or invertebrates. PAHs appeared not to pose an adverse effect at five other sites, but the information was equivocal. At another five sites, there “was too little information to evaluate possible PAH effects,” though PAHs did not figure in the remediation options. Empirical evidence indicates that wildlife exposures via food are mostly from foliar deposition, which tends to be low away from urban areas. To date, there is no evidence that PAHs in soils at hazardous waste sites result in adverse effects to plants, invertebrates, or wildlife.     

Phytoremediation in the Tropics—The Effect of Crude Oil on the Growth of Tropical Plants

Phytoremediation is a nondestructive, cost-effective in-situ technology to clean up contaminated soils. In the case of contamination with petroleum hydrocarbons, plants enhance microbial degradation of the contaminant in the rhizosphere. The potential of this technology for the tropics should be high due to prevailing climatic conditions favoring plant growth and stimulating microbial activity. Investigations of the potential of tropical plants for phytoremediation, however, are scarce. The present work studied two grasses and six legumes from the eastern savannah of Venezuela on their reaction to crude oil contamination in soil. Results shall help to identify plants with a potential for phytoremediation and subsequent studies. Seedling emergence and biomass production were determined for plants growing in soil contaminated with 0%, 3%, and 5% heavy crude oil. Contamination had, in general, a tendential but not significant negative influence on seedling emergence. Dry matter production was reduced by only a few percent to up to 85%. Furthermore, in some legumes inhibition of nodulation was observed. The grass Brachiaria brizantha and the legumes Centrosema brasilianum and Calopogonium mucunoides are promising for phytoremediation because in contaminated soil they combined high seedling emergence with least affected biomass production. Since they are cultivated forage/soil cover species also in other regions of the tropics, their potential for phytoremediation of petroleum contaminated soils extends beyond Venezuela.     

Human-induced changes in US biogenic volatile organic compound emissions: evidence from long-term forest inventory data

Volatile organic compounds (VOCs) emitted by woody vegetation influence global climate forcing and the formation of tropospheric ozone. We use data from over 250 000 re‐surveyed forest plots in the eastern US to estimate emission rates for the two most important biogenic VOCs (isoprene and monoterpenes) in the 1980s and 1990s, and then compare these estimates to give a decadal change in emission rate. Over much of the region, particularly the southeast, we estimate that there were large changes in biogenic VOC emissions: half of the grid cells (1°× 1°) had decadal changes in emission rate outside the range ?2.3% to +16.8% for isoprene, and outside the range 0.2–17.1% for monoterpenes. For an average grid cell the estimated decadal change in heatwave biogenic VOC emissions (usually an increase) was three times greater than the decadal change in heatwave anthropogenic VOC emissions (usually a decrease, caused by legislation). Leaf‐area increases in forests, caused by anthropogenic disturbance, were the most important process increasing biogenic VOC emissions. However, in the southeast, which had the largest estimated changes, there were substantial effects of ecological succession (which decreased monoterpene emissions and had location‐specific effects on isoprene emissions), harvesting (which decreased monoterpene emissions and increased isoprene emissions) and plantation management (which increased isoprene emissions, and decreased monoterpene emissions in some states but increased monoterpene emissions in others). In any given region, changes in a very few tree species caused most of the changes in emissions: the rapid changes in the southeast were caused almost entirely by increases in sweetgum (Liquidambar styraciflua) and a few pine species. Therefore, in these regions, a more detailed ecological understanding of just a few species could greatly improve our understanding of the relationship between natural ecological processes, forest management, and biogenic VOC emissions.     

Distinctive hydrocarbons of the black dump fly, Hydrotaea aenescens (Diptera: Muscidae).

Hydrotaea aenescens (Wiedemann), the black dump fly, is a potential biological control agent originally from the western hemisphere, now found in many parts of the Palearctic region except for the United Kingdom, where it cannot be imported for any reason. A complication of classical biological control is the problem of strain identification, as one must be able to somehow mark or follow a particular strain that has been introduced into the field or is contemplated for release. Gas chromatographic analysis of the surface hydrocarbons of pooled and individual dump fly adults resulted in reproducible hydrocarbon patterns that differentiated widely distributed strains of H. aenescens and showed similarities between strains that were related. Sexual dimorphism was observed in the surface hydrocarbons. Conspecific similarities included identities of the hydrocarbons found in colony material collected worldwide, with differences being found in the quantities of compounds present.     

秸秆降解放线菌GC的筛选及其应用基础研究

运用循环流化技术,从土壤样品中筛选出1株具有单独降解秸秆能力的菌株GC,考察了该菌的生长特性及产纤维素酶和木质素酶能力,验证了该菌对小麦秸秆的处理效果。结果表明,该菌为放线菌的左式链霉菌(Streptomyces drozdowiczii);可在LB等基础培养基中快速繁殖;纤维素内切酶活和滤纸酶活分别可达67.57 U/mL和19.69 U/mL,并且具备木质素降解能力;该菌单独处理小麦秸秆20 d的秸秆失重率为11.52%;处理产物含多种石油烃、有机醇和植物甾醇等,表明该菌在秸秆等农业面源污染物的资源化利用方面具有良好的开发应用前景。     

Isoprenoids of Bacillus acidocaldarius

-The isoprenoids of Bacillus acidocaldarius, a notably acidophilic thermophilic organism, were investigated. Besides normal bacterial isoprenoids such as menaquinone and polyprenols, which latter were resolved in a-cis and a-trans fractions, and some minor components (a-tertiary-prenols and the corresponding anhydroderivatives), not fully characterized, and probably ‘natural’ artefacts, we have isolated and characterized squalene and pentacyclic triterpene hydrocarbons belonging to the hopane class, which must be accounted as unusual. Radioactivity from mevalonate-[2-¹⁴C] is incorporated into hopene-b (the major triterpene component), thus establishing the origin of cyclized squalene derivatives in B. acidocaldarius as a result of de novo synthesis.     

Highly Efficient and Stable Perovskite Solar Cells Using a Dopant‐Free Inexpensive Small Molecule as the Hole‐Transporting Material

The hole transporting layer (HTL) plays an important role in realizing efficient and stable perovskite solar cells (PSCs). In spite of intensive research efforts toward the development of HTL materials, low‐cost, dopant‐free hole transporting materials that lead to efficient and stable PSCs remain elusive. Herein, a simple polycyclic heteroaromatic hydrocarbon‐based small molecule, 2,5,9,12‐tetra(tert‐butyl)diacenaphtho[1,2‐b:1′,2′‐d]thiophenen, as an efficient HTL material in PSCs is presented. This molecule is easy to synthesize and inexpensive. It is hydrophobic and exhibits excellent film‐forming properties on perovskites. It has unusually high hole mobility and a desirable highest occupied molecular orbital energy level, making it an ideal HTL material. PSCs fabricated using both the n‐i‐p planar and mesoscopic architectures with this compound as the HTL show efficiencies as high as 15.59% and 18.17%, respectively, with minimal hysteresis and high long term stability under ambient conditions.