Ecological properties of earthworm burrows in an organically managed grass-clover system

Earthworms have long been recognized for their soil engineering capacities. Since the creation of the ecosystem service concept the utilitarian perception of nature has gained a lot of attention and funding for research. Hence, we selected earthworms and their burrowing activities to enable an assessment of their influence on water movement and nutrient release. The study went on in autumn where earthworm population densities and their burrowing activities were quantified in plots of third year clover-grass crops differing in fertilisation and the manner of removing the biomass either by grazing or cutting. We found very high biomasses as expected for clover-grass about 200 g wet earthworm weight m-2. The common earthworm association typical to our region was: Aporrectodea tuberculata, Aporrectodea rosea, Aporrectodea longa and Lumbricus terrestris, i.e. two endogeic and two anecic species. We present our results on the burrow size distribution down the soil profile and link it to the species and species traits. The results are further put into perspective in our present research on macropores related to soil ecosystem services and pesticide leachin

Book Reviews

Book Review 1Book Title: Zoological Catalogue of Australia Vol. 34. Hemichordata, Tunicata, CephalochordataBook Authors: Editors A. Wells & W.W.K. Houston1998. CSIRO Publishing, Melbourne. 298pp.Book Review 2Book Title: Biodiversity dynamics and conservation: the freshwater fish of tropical AfricaBook Author: Christian Léveque 1997. ISBN 0 521 570336. Cambridge University Press, Cambridge.Book Review 3Book Title: Biology and ecology in southern African estuariesBook Author: Alan K. Whitfield Ichthyological Monographs of the J.L.B. Smith Institute of Ichthyology, No.2. 1998. ISBN 0-86810-333-0. Hardcover, 223 pp.Book Review 4Book Title: The Southern synthesis. Fauna of Australia Vol. 5Book Authors: P.L. Beesley, G.J.B. Ross & A. Wells 1998. CSIRO Publishing, Melbourne.Book Review 5Book Title: The Kingdon field guide to African mammalsBook Author: Jonathan Kingdon1997. Academic Press (locally available at Russell & Friedman. Box 73, Halfway House) 465pp. ISBN 0-12-408355-2.Book Review 6Book Title: Cooperative breeding in mammalsBook Authors: Edited by Nancy G. Solomon & Jeffrey A. FrenchCambridge University Press, Cambridge, UK. 1997. 390 pp. ISBN 0521 4591 3

Accurate Reconstruction of Cell and Particle Tracks from 3D Live Imaging Data

Spatial structures often constrain the 3D movement of cells or particles in vivo, yet this information is obscured when microscopy data are analyzed using standard approaches. Here, we present methods, called unwrapping and Riemannian manifold learning, for mapping particle-tracking data along unseen and irregularly curved surfaces onto appropriate 2D representations. This is conceptually similar to the problem of reconstructing accurate geography from conventional Mercator maps, but our methods do not require prior knowledge of the environments’ physical structure. Unwrapping and Riemannian manifold learning accurately recover the underlying 2D geometry from 3D imaging data without the need for fiducial marks. They outperform standard x-y projections, and unlike standard dimensionality reduction techniques, they also successfully detect both bias and persistence in cell migration modes. We demonstrate these features on simulated data and zebrafish and Drosophila in vivo immune cell trajectory datasets. Software packages that implement unwrapping and Riemannian manifold learning are provided

Plausibility functions and exact frequentist inference

In the frequentist program, inferential methods with exact control on error rates are a primary focus. The standard approach, however, is to rely on asymptotic approximations, which may not be suitable. This paper presents a general framework for the construction of exact frequentist procedures based on plausibility functions. It is shown that the plausibility function-based tests and confidence regions have the desired frequentist properties in finite samples---no large-sample justification needed. An extension of the proposed method is also given for problems involving nuisance parameters. Examples demonstrate that the plausibility function-based method is both exact and efficient in a wide variety of problems.Comment: 21 pages, 5 figures, 3 table

Spectroscopic Investigation of the Activation of a Chromium-Pyrrolyl Ethene Trimerization Catalyst

1-Hexene is an important α-olefin for polyethylene production and is produced from ethene. Recent developments in the α-olefin industry have led to the successful commercialization of ethene trimerization catalysts. An important industrially applied ethene trimerization system uses a mixture of chromium 2-ethylhexanoate, AlEt3, AlEt2Cl, and 2,5-dimethylpyrrole (DMP). Here, we have studied the activation of this system using catalytic and spectroscopic experiments (XAS, EPR, and UV–vis) under conditions employed in industry. First, chromium 2-ethylhexanoate was prepared and characterized to be [Cr3O­(RCO2)6(H2O)3]­Cl. Next, the activation of chromium 2-ethylhexanoate with AlEt3, AlEt2Cl, and DMP was studied, showing immediate reduction (<5 ms) of the trinuclear Cr­(III) carboxylate and formation of a neutral polynuclear Cr­(II) carboxylate complex. Over time, this Cr­(II) carboxylate complex is partially converted into a chloro-bridged dinuclear Cr­(II) pyrrolyl complex. In cyclohexane, small quantities of an unknown Cr­(I) complex (∼1% after 1 h) are observed, while in toluene, the quantity of Cr­(I) is much higher (∼23% after 1 h). This is due to the formation of cationic bis­(tolyl)­Cr­(I) complexes, which likely leads to the observed inferior performance using toluene as the reaction solvent. Catalytic studies allow us to exclude some of the observed Cr­(I) and Cr­(II) complexes as the active species in this catalytic system. Using this combination of techniques, we have been able to structurally characterize complexes of this selective Cr-catalyzed trimerization system under conditions which are employed in industry

Occurrence of Salmonella spp. in flies and foodstuff from pork butcheries in Kampala, Uganda

Food-borne diseases such as salmonellosis are a major cause of human gastroenteritis worldwide, especially in the developing world due to poor sanitary conditions. Flies feed on food and breed in feces and other organic material. As such they are known vectors of Salmonella spp. Given that pork consumption in Uganda is rapidly increasing while good food safety practices remain absent, this study aims to assess the occurrence of Salmonella spp. in pork butcheries as a contribution to improve hygiene. Seventy-seven pork butcheries out of 179 mapped in a previous survey in Kampala were randomly selected. From June–October 2014, samples of house flies, foodstuff and equipment were collected from all butcheries. Cultural isolation of Salmonella spp. was performed according to ISO 6579:2002. Among 693 samples, 64 (9%) tested positive for Salmonella enteritidis. Among the positives, 32% were samples of raw pork (25), 25% flies’ midguts (19), less than 9% water (7), tomatoes (6), cabbage (4), onions (2) and one case on roasted pork1, respectively. Positive flies coincided with contaminated foodstuff in 29% of the butcheries. All 154 samples from either butchers’ hands or their equipment were negative for Salmonella spp. The prevalence of S. enteritidis, especially on raw pork and in flies, illustrates the need for improving food safety in pork butcheries. Further research is required clarifying the gaps; especially the role of flies as microbiological carriers. In this context investigations are ongoing to identify Salmonella serotypes and their antimicrobial drug-resistance situation. However, these findings merit increased attention and can be used to improve knowledge, attitudes and practices amongst butchers. The research was carried out with the financial support of the Federal Ministry for Economic Cooperation and Development (BMZ), Germany, and the CGIAR Research Program on Agriculture for Nutrition and Health, led by the International Food Policy Research Institute, through the Safe Food, Fair Food project at ILRI. Martin Heilmann got a scholarship from the German Academic Exchange Service (DAAD)

Antimicrobial resistance of Salmonella enterica in pork and vegetable servings at pork joints in Kampala, Uganda

The aim of this study was to investigate the prevalence and antimicrobial resistance of Salmonella enterica subsp. enterica serovars including the presence of shared plasmids in pork and related fresh vegetables served in pork joints in Kampala, Uganda. Pork butcheries in three of the five administrative divisions of Kampala were included for the survey. Samples included raw pork, roasted pork, water, onions, tomatoes, cabbage, butcher’s hands (swabs), utensils (swabs) and fly midgut extracts. A total of 693 samples were collected from 77 pork butcheries from June- October 2014. Overall 53.2% pork joints had samples positive for Salmonella enterica subsp. enterica serovars. Isolation rates ranged from 31.2% (24/77) for raw pork, 1.3% (1/77) for roasted pork, 7.8% (6/77) for tomatoes, 2.6% (2/77) for onions, 5.2% (4/77) for cabbage, 9.1% (7/77) in water, and 22.1% (17/77) from fly midguts. Swab samples taken from utensil and butcher’s hands swabs were found negative (Heilmann et al., 2015). In the isolates obtained, resistance towards 22 antibiotics was tested. Resistances were found towards 11 out of the 22 antibiotics tested. High resistances were found to Cephazolin (97%), Cefotixime (93%), Gentamicin (88%), and Ceftazidime (86%). Intermediate resistance was found to Ciprofloxacin (59%) and Amoxicillin-Clavulanic acid (57.6%). Most isolates (85%) were susceptible to Levofloxacin, Ofloxacin, Sulfamethoxazole and Trimethoprim. Identification of plasmids by PCR-based replicon typing was performed recognizing FIA,FIB,FIC,HI1,HI2,I1- 1ᵞ,L/M,N,P,W,T,A/C,K,B/O,X,Y,F and FIIA. Six incompatibility groups were identified: FIA, W, FIC, FIB, P, Y with more than one incompatibility group existing among different isolates. A high resistance rate among Salmonella strains was found while the total number of incompatibility groups detected was with approximation 2.4. Thus, even though the total number of plasmids per strain is low, resistance rates detected remain high. The high resistance rates are probably resulting from intensified food animal production driving a greater use of antibiotics, which is a crucial aspect of public health concern

Experimental Control and Characterization of Autophagy in Drosophila

Insects such as the fruit fly Drosophila melanogaster, which fundamentally reorganize their body plan during metamorphosis, make extensive use of autophagy for their normal development and physiology. In the fruit fly, the hepatic/adipose organ known as the fat body accumulates nutrient stores during the larval feeding stage. Upon entering metamorphosis, as well as in response to starvation, these nutrients are mobilized through a massive induction of autophagy, providing support to other tissues and organs during periods of nutrient deprivation. High levels of autophagy are also observed in larval tissues destined for elimination, such as the salivary glands and larval gut. Drosophila is emerging as an important system for studying the functions and regulation of autophagy in an in vivo setting. In this chapter we describe reagents and methods for monitoring autophagy in Drosophila, focusing on the larval fat body. We also describe methods for experimentally activating and inhibiting autophagy in this system and discuss the potential for genetic analysis in Drosophila to identify novel genes involved in autophagy

Constraints on the Charged Higgs Sector from the Tevatron Collider Data on Top Quark Decay

The top quark data in the lepton plus $\tau$ channel offers a viable probe for the charged Higgs boson signal. We analyse the recent Tevatron collider data in this channel to obtain a significant limit on the $H^\pm$ mass in the large $\tan\beta$ region.Comment: 8 pages, LaTeX file; 2 figures included (PS files