Aggressive mimicry in photuris fireflies: signal repertoires by femmes fatales

Females of Photuris versicolor prey on males of other species by mimicking the flash responses of the prey's own females. They adjust their responses according to the male pattern, and attract males of four species with distinctively different flashed responses. The capabilities of the firefly brain are more complex than previously suspected. The mimicry is quite effective, and females seldom answered more than ten males without catching one.     

Optimized Frequency Measures for Monitoring Trends in Tallgrass Prairie

Prairies exhibit a bimodal frequency distribution of patch occupancy with a few dominant species accounting for most of the primary production and plant biomass and numerous other species occurring infrequently over time and space. Consequently, management interest is often focused on the abundance of common species, and on the persistence of less common species. We used spatially nested arrays of various sized plots to simultaneously measure species’ persistence and abundance at Tallgrass Prairie National Preserve, Kansas. Larger plots captured more species, with 127 species identified at the 10-m scale. Smaller plots, however, provided useful frequency data for measuring the abundance of common species. We defined a plot frame size that delivers a frequency in a 20–50% target range as the optimal plot size, and the frequency of a species sampled at its optimal plot size is termed the optimized frequency. Optimized frequency was estimated for 27 common species for the years 2002–2006. Of the nine perennial grasses in this group, five exhibited significant interannual variation within the 5-yr period. Bouteloua curtipendula exhibited a significant linear change over the 5-yr period, decreasing in frequency over time. From year to year, changes in optimized frequency among the 27 common species varied in both their trajectory (i.e., the average change), and amplitude (i.e., the average magnitude of change). Between 2005 and 2006, the average change in optimized frequency was -9.1%, the only year with an overall declining trajectory. The declining trajectory between 2005 and 2006 was significantly different from the increasing trajectories observed between 2002 and 2003 and between 2004 and 2005. No significant differences were observed in amplitude. We offer these techniques for aggregating information from multiple spatial scales to characterize the amplitude and trajectory of community-wide changes as tools to help scientists convey the results of multiscale research projects to land managers.     

Field Test of Digital Photography Biomass Estimation Technique in Tallgrass Prairie

Fuel loading information is important for prescribed fire planning, evaluating wildfire risk, and understanding fire effects in grassland. Yet fuel loads in grasslands often go unmeasured because of the time required to clip plots and process samples, as well as limited access or proximity to a drying oven. We tested the digital photography biomass estimation technique for measuring fuel load in grasslands in two national parks in the eastern Great Plains. The method consists of using percentage image obstruction, as determined by digital photography, to estimate vegetation biomass based on a linear transformation (i.e., regressing dry clipped weights against percent digital obstruction). We used the technique with some modification and measured digital obstruction at two sites at Wilson’s Creek National Battlefield, Missouri (WICR), and three sites at Tallgrass Prairie National Preserve, Kansas (TAPR). The method did not result in strong correlations at either of the two sites at WICR (Site 1: r²=0.02; Site 2: r²=0.32), but performed relatively well at TAPR (Site 1 [<1 yr since burn]: r²=0.82; Site 2 [2 yr since burn]: r²=0.57; Site 3 [1 yr since burn]: r²=0.88). Linear regressions for the three sites at TAPR did not differ in slope (P>0.05). In general, the denser the vegetation, the weaker the relationship between the vegetation biomass of clip plots and the percentage image obstruction of digital images. The digital photography technique may not be useful for estimating fuel loads in grasslands with relatively high biomass (>80 g · 0.1 m^?2) or digital image obstruction >50%. Large amounts of litter may also potentially reduce the accuracy of the technique.     

Book reviews

Water, Air, &; Soil Pollution -     

Quantification of saponins in aerial and subterranean tissues of Medicago truncatula

Triterpene saponins from aerial and subterranean organs of Medicago truncatula cv. Jemalong A-17 were qualitatively profiled and quantified using reverse-phase HPLC with on-line photodiode array detection and electrospray-ionization mass spectrometry (HPLC/PDA/ESI/MS). Absolute quantifications were performed for 3-O-beta-D-glucopyranosyl-medicagenic acid and soyasaponin 1 (3-O-[alpha-L-rhamnopyranosyl(1-->2)-beta-D-galactopyranosyl(1-->2)-beta-D-glucuronopyranoside] soyasapogenol B), whereas relative quantifications were determined for 29 other saponins in root, stem, leaf, seedpod, and seed. Roots contained the greatest total amount of saponins followed by leaf and seed, respectively. The quantitative data also reveal the differential accumulation of triterpene saponins in the various organs of M. truncatula. Specifically, relatively higher quantities of medicagenic acid conjugates accumulated in leaf and seed, whereas relatively higher levels of soysapogenol conjugates were observed in root. The differential accumulation of specific triterpene saponins is suggestive of spatially differentiated biosynthesis and/or biological function.     

Metabolic engineering of plant cells for biotransformation of hesperedin into neohesperidin, a substrate for production of the low-calorie sweetener and flavor enhancer NHDC

Neohesperidin dihydrochalcone (NHDC) is a seminatural, safe, low-calorie sweetener, bitterness blocker, and flavor enhancer with unique properties and applications for the food, beverage, pharmaceutical, and animal feed industries. Current production is limited by the availability of the substrate neohesperidin, a flavonoid that accumulates to significant levels only in the inedible bitter citrus species. We propose a process to convert hesperidin, a tasteless flavonoid extracted from orange peels that are abundant byproducts of the vast orange juice industry, into neohesperidin using metabolic engineering and biotransformation via three steps: (i) extraction of hesperidin from orange peels, (ii) hydrolysis of sugar moieties, and (iii) biotransformation of hesperidin hydrolysis products into neohesperidin. We overcame the current technological bottleneck in biotransformation of hesperidin hydrolysis products into neohesperidin using metabolically engineered plant cell cultures expressing a recombinant flavanone-7-O-glucoside-2-O-rhamnosyltransferase. A small-scale production experiment established the feasibility of the proposed process.     

Restoring the capacity of spent mushroom compost to treat coal mine drainage by reducing the inflow rate: A microcosm experiment

Four volumes of spent mushroom compost were exposed to synthetic coal mine drainage (pH 3.5, 48 mg L^?1 Fe, 22 mg L^?1 Mn) under oxidizing conditions (Eh 300 to 400 mV) at a relatively high rate of flow. After 15 days, the compost lost its ability to elevate pH, to lower the redox potential, to lower outlet iron concentrations, and to lower manganese concentrations, with larger volumes retaining more Fe and H⁺, but less Mn. Estimated retention maxima per liter of spent mushroom compost were 281 μeq H⁺, 5.56 g Fe, and 0.15 g Mn. These values are similar to those reported elsewhere for peat. The ‘saturated’ compost was then mixed and exposed to mine water in order to eliminate ‘dead zones’ in the compost. Subsequently, the compost was re-exposed to synthetic mine water (pH 4.0, 60 mg L^?1 Fe, O mg L^?1 Mn) under a much lower flow rate and less oxidizing regime for a period of 114 days. Under the low flow regime, iron was first exported from the compost as reducing conditions were established, and then retained on a stable basis. In addition, Eh was lowered and pH was elevated by the compost. On a net basis, the capacity of the compost to retain iron was increased and apparently stable under the decreased flow conditions.     

Prevalence of anthelmintic resistance on sheep farms in New Zealand

AIM: To establish the prevalence of anthelmintic resistance in parasitic nematodes on sheep farms in New Zealand.

METHODS: A cross-sectional prevalence study was conducted, using a standardised faecal nematode egg count (FEC) reduction (FECR) test (FECRT) for ivermectin, at a full (0.2 mg/kg) and half (0.1 mg/kg) dose rate, and albendazole, levamisole and albendazole-levamisole in combination, on 60 lambs (n=10 per group) on farms selected from throughout New Zealand. Farms that conformed with selection criteria were chosen at random (n=80) or with a history of suspected resistance to macrocy- clic lactone (ML) anthelmintics (n=32). Resistance to an an- thelmintic was inferred when there was <95% reduction in FEC 7-10 days after treatment. Larval cultures were performed for all control groups and for treated groups for which resistance was evident.

RESULTS: Of the farms randomly selected, 36% showed ≥95% FECR for all anthelmintics tested; resistance to ivermectin at 0.1 and 0.2 mg/kg liveweight was evident on 36% and 25% of these farms, respectively. Resistance to both ivermectin (0.2 mg/kg) and levamisole was evident on 8/80 (10%) farms, to ivermectin and albendazole on 10/80 (13%) farms, and to iver- mectin, levamisole and albendazole on 6/80 (8%) farms. The prevalence of resistance to a half dose of ivermectin tended to be more prevalent on farms with a history of suspected ML resistance (p=0.06). Resistance to albendazole was seen across all the main parasite genera, and to levamisole in Nematodirus, Ostertagia (= Teladorsagia) and Trichostrongylus species. Resistance to ivermectin was dominated by Ostertagia spp, although Cooperia, Nematodirus and Trichostrongylus species were also implicated.

CONCLUSION: Anthelmintic resistance in parasitic nema-todes of sheep is common in New Zealand. Not only was resistance to albendazole and levamisole common, but resistance to the ML, ivermectin, was at a higher prevalence than expected. Sheep farmers and advisors in New Zealand need to re-evaluate the way they manage parasites, and more research is urgently needed if the steady decline in anthelmintic susceptibility is to be halted.