Scaling relations between riparian vegetation and stream order in the Whitewater River network,Kansas, USA

Riparian communities have been well-studied along individual streams, but not within the context of networks of which streams are a part. To study networks, hydrologists use Horton–Strahler ordering to assign streams to discrete categories in which increasing numerical value (ω) reflects increasing size of the stream and complexity of the network. A key use of this classification method has been to demonstrate scaling relations between hydrogeomorphic variables and order. These relations now provide a foundation to determine how ecological processes are associated with the geometry and topology of river networks. We used geographic information systems (GIS) to map and measure the stream network and riparian vegetation of the Whitewater River basin of eastern Kansas, USA. With the resulting data, we tested if (1) riparian vegetation scaled with order, and (2) riparian vegetation at confluences of two streams differed from that found along constituent streams. Most characteristics of riparian vegetation scaled with order. In confluence zones, density and diversity of riparian vegetation generally were equivalent to that of the largest constituent stream. Scaling relations between riparian vegetation and order provide a framework to quantify the role of riparian vegetation in the water balance of stream networks and a tool to predict area and distribution of riparian vegetation from network topology.     

Settling of insecticide from dip wash mixed with dam water and zinc sulphate and used to control sheep lice (Bovicola ovis)

SUMMARY Insecticidal dipping fluid emulsions, mixed in vitro in dam water containing suspended clay particles and 1% w/v zinc sulphate, were analysed to determine rates of settling of diazinon, cyhalothrin and cypermethrin. Fifteen minutes after mixing, the concentration of the insecticides 5 cm below the surface had declined by 72.5%, 72.8% and 89.4%, respectively. On remixing, the concentration of insecticide in suspension was close to or greater than the initial concentration. In 2 trials, lice were eradicated from sheep showered with dip wash mixed in cloudy dam water to which 1% w/v of zinc sulphate was added. In 12 flock treatments in which 1000 to 2000 sheep were dipped with added zinc sulphate, the concentration of insecticide remained above the minimum lethal for susceptible strains of lice. However, lice were still present 6 months later in 8 of these flocks. When zinc sulphate is added to dip wash, agitation is needed to maintain the insecticide in suspension.     

Soil CO2 emissions in cropland with fodder maize (Zea mays L.) with and without riparian buffer strips of differing vegetation

Agroforestry Systems - Vegetated land areas play a significant role in determining the fate of carbon (C) in the global C cycle. Riparian buffer vegetation is primarily implemented for water...     

Brucella melitensis infection following military duty in Iraq

Brucellosis is a common zoonotic disease worldwide; however, few cases are reported in the US. Brucella melitensis infections are primarily acquired via consumption of high-risk foods or travel to endemic areas. We describe a case of B. melitensis infection in a Tennessee soldier following deployment in Iraq. Initial symptoms included knee and back pain. Culture of an aspirate of the left sacroiliac joint yielded B. melitensis. Genetic analysis indicated that this isolate came from the Middle East. Investigation of laboratory workers identified risky exposures and positive serology prompting post-exposure prophylaxis. Military personnel and other travellers should be advised to reduce risk regarding food consumption and animal contact in endemic areas. Additionally, medical providers should remain vigilant for non-endemic zoonoses among recent travellers.     

Rapid actin transport during cell protrusion

Transformed rat fibroblasts expressing two variants of green fluorescent protein, each fused to beta-actin, were used to study actin dynamics during cell protrusion. The recently developed FLAP (fluorescence localization after photobleaching) method permits the tracking of one fluorophore after localized photobleaching by using the other as a colocalized reference. Here, by visualizing the ratio of bleached to total molecules, we found that actin was delivered to protruding zones of the leading edge of the cell at speeds that exceeded 5 micrometers per second. Monte Carlo modeling confirmed that this flow cannot be explained by diffusion and may involve active transport.     

Bioaccumulation of gold in macrofungi and ectomycorrhizae from the vicinity of the Mokrsko gold deposit, Czech Republic

Samples of macrofungi collected in the vicinity of the Mokrsko gold deposit were analyzed for Au by INAA and ICP-MS. Ectomycorrhizal fungi yielded from 0.88 to 564 μg kg⁻¹ Au (dry weight) in 79 samples. Saprobic fungi (75 samples) from the same locations yielded significantly higher concentrations: 3-7739 μg kg⁻¹ Au (dry weight), with the highest contents in Lycoperdon perlatum. These are the highest recorded concentrations of Au in naturally-occurring fungi/vascular plants. Concentrations of Au in ectomycorrhizae were approximately 4-10 times higher than those in fine roots. It appears that saprobic fungi, namely several terrestrial saprobes of the genera Agaricus and Lycoperdon, are more efficient than ectomycorrhizal fungi at taking up Au, probably assisted by other microbiota and/or by a range of naturally-occurring compounds that have yet to be identified. The present data demonstrate that macrofungi are involved in the biogeochemical cycling of Au.