Prenatal diagnosis using deletion studies in Duchenne muscular dystrophy

Accurate carrier testing and prenatal diagnosis in Duchenne muscular dystrophy (DMD) families is facilitated when an Xp21 deletion is found to be segregating within a family. We discuss the results of the DNA testing in two families, one in which DNA from affected males was available for study and the other in which no DNA from an affected male was available. Factors complicating the counselling of DMD deletion families are outlined.     

Alfalfa rapidly remediates excess inorganic nitrogen at a fertilizer spill site

By 19%, standard remediation techniques had significantly reduced the concentration of nitrate nitrogen (NO3- -N) in local ground water at the site of a 1989 anhydrous ammonia spill, but NO3- -N concentrations in portions of the site still exceeded the public drinking water standard. Our objective was to determine whether local soil and ground water quality could be improved with alfalfa (Medicago sativa L.). A 3-yr study was conducted in replicated plots (24 by 30 m) located hydrologically upgradient of the ground water under the spill site. Three alfalfa entries ['Agate', Ineffective Agate (a non-N2-fixing elite germplasm similar to Agate), and MWNC-4 (an experimental germplasm)] were seeded in the spring of 1996. Corn (Zea mays L.) or wheat (Triticum aestivum L.) was seeded adjacent to the alfalfa each year. Crops were irrigated with N-containing ground water to meet water demand. During the 3-yr period, about 540 kg of inorganic N was removed from the aquifer through irrigation of 4.9 million L water. Cumulative N removal from the site over 3 yr was 972 kg N ha(-1) in Ineffective Agate alfalfa hay, compared with 287 kg N ha(-1) for the annual cereal grain. Soil solution NO3- concentrations were reduced to low and stable levels by alfalfa, but were more variable under the annual crops. Ground water quality improved, as evidenced by irrigation water N concentration. We do not know how much N was removed by the N2-fixing alfalfas, but it appears that either fixing or non-N2-fixing alfalfa will effectively remove inorganic N from N-affected sites.     

LABORATORY EXPERIMENTS AS AN AID TO LAKE RESTORATION DECISIONMAKING1

ABSTRACT: The choice of a lake rehabilitation technique can be assisted by laboratory experiments concerned with the composition and properties of the sediments. This work on Sawgrass Lake, Pinellas County, Florida, provides an example of the type of laboratory information that can be useful towards making decisions regarding the most effective restorative techniques. Experiments include chemical analysis of sediment (water content, organic content, pesticides, nutrients), rate of sediment compaction and rehydration at ambient conditions, and the effect of treatment with alum and other chemicals.     

Climatic and genetic controls of yields of switchgrass, a model bioenergy species

The U.S. Renewable Fuel Standard calls for 136 billion liters of renewable fuels production by 2022. Switchgrass (Panicum virgatum L.) has emerged as a leading candidate to be developed as a bioenergy feedstock. To reach biofuel production goals in a sustainable manner, more information is needed to characterize potential production rates of switchgrass. We used switchgrass yield data and general additive models (GAMs) to model lowland and upland switchgrass yield as nonlinear functions of climate and environmental variables. We used the GAMs and a 39-year climate dataset to assess the spatio-temporal variability in switchgrass yield due to climate variables alone. Variables associated with fertilizer application, genetics, precipitation, and management practices were the most important for explaining variability in switchgrass yield. The relationship of switchgrass yield with climate variables was different for upland than lowland cultivars. The spatio-temporal analysis showed that considerable variability in switchgrass yields can occur due to climate variables alone. The highest switchgrass yields with the lowest variability occurred primarily in the Corn Belt region, suggesting that prime cropland regions are the best suited for a constant and high switchgrass biomass yield. Given that much lignocellulosic feedstock production will likely occur in regions with less suitable climates for agriculture, interannual variability in yields should be expected and incorporated into operational planning.     

Underlying causes of habitat-associated differences in size of age-0 walleye pollock (Theragra chalcogramma) in the Gulf of Alaska

Age-0 walleye pollock (Theragra chalcogramma) caught in September in the Gulf of Alaska display habitat-associated differences in standard length (SL). Age-0 fish collected in the region around Sutwik Island and 375?km farther downstream near the Shumagin Islands most likely originate from the Shelikof Strait spawning aggregation. However, age-0 fish resulting from the same spawning aggregation differ in mean size up to 20?mm between areas by September. We examined the otoliths of the larval and age-0 stages of walleye pollock from these two areas in 2000 and 2001 to determine whether growth rate, hatch date, and/or temperature influenced fish size. Circulation models were used to determine whether transport of larvae from an upstream spawning group into the study areas could have occurred. Mean in situ temperature during sampling periods was not defined as a significant factor in altering growth rates. Overlapping hatch date distributions of the larval and age-0 fish in the Shumagin Island area confirmed that the fish were from the Shelikof Strait spawning group. Comparison of hatch date distributions in the upstream Sutwik Island area revealed larger/older larvae from an upstream spawning group mixed with larvae from the Shelikof Strait spawning group. Our results suggest that the offset of 20?mm SL between the groups of age-0 pollock was the result of a combination of enhanced survivorship of early-hatched larvae in the Sutwik area and the introduction and retention of the progeny of another spawning group originating upstream of Shelikof Strait.     

An ecological framework for contextualizing carnivore–livestock conflict

Carnivore predation on livestock is a complex management and policy challenge, yet it is also intrinsically an ecological interaction between predators and prey. Human–wildlife interactions occur in socioecological systems in which human and environmental processes are closely linked. However, underlying human–wildlife conflict and key to unpacking its complexity are concrete and identifiable ecological mechanisms that lead to predation events. To better understand how ecological theory accords with interactions between wild predators and domestic prey, we developed a framework to describe ecological drivers of predation on livestock. We based this framework on foundational ecological theory and current research on interactions between predators and domestic prey. We used this framework to examine ecological mechanisms (e.g., density-mediated effects, behaviorally mediated effects, and optimal foraging theory) through which specific management interventions operate, and we analyzed the ecological determinants of failure and success of management interventions in 3 case studies: snow leopards (Panthera uncia), wolves (Canis lupus), and cougars (Puma concolor). The varied, context-dependent successes and failures of the management interventions in these case studies demonstrated the utility of using an ecological framework to ground research and management of carnivore–livestock conflict. Mitigation of human–wildlife conflict appears to require an understanding of how fundamental ecological theories work within domestic predator–prey systems.     

Investigating the affinities and persistence of VX nerve agent in environmental matrices

Laboratory experiments were conducted to determine environmental variables that affect the affinities and persistence of the nerve agent O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate (VX) at dilute concentrations in environmental matrices. Quantitative analyses of VX and its degradation products were performed using LC-MS. Batch hydrolysis experiments demonstrated an increasing hydrolysis rate as pH increased, as shown in previous studies, but also indicated that dissolved aqueous constituents can cause significant differences in the absolute hydrolysis rate. Adsorption isotherms from batch aqueous experiments revealed that VX has a high affinity for hydrophobic organics, a moderate affinity for montmorillonite clay, and a very low affinity for an iron-oxyhydroxide soil mineral, goethite. The adsorption on goethite was increased with the presence of dissolved organic matter in solution. VX degraded rapidly when dried onto goethite, when specific adsorption was forced. No enhanced degradation occurred with goethite in small amounts of water. These results suggest that aqueous conditions have important controls on VX adsorption and degradation in the environment and a more mechanistic understanding of these controls is needed in order to enable accurate predictions of its long-term fate and persistence.     

Seagrass and algal beds as nursery habitats for tiger prawns (Penaeus semisulcatus and P. esculentus) in a tropical Australian estuary

We evaluated the importance of seagrass and algae to two species of tiger prawns (Penaeus semisulcatus and P. esculentus) by detailed sampling at four sites (two seagrass, two algae) in the Embley River estuary, and through sampling 26 sites in 7 adjacent estuaries at one time of year. Samples of tiger prawns were collected in the Embley River estuary with a small beam trawl at night every 2 wk from September to May for 2 yr (1990 to 1992). The two seagrass sites, which were 11 and 13 km from the river mouth, showed less seasonal variation in salinity than the two algal sites, which were 15 and 20 km from the river mouth. The algal beds at the two upstream sites almost disappeared during the wet season, but the biomass of seagrass did not change significantly between the wet and dry seasons. The grooved tiger prawn (P. semisulcatus), the main species at all sites, comprised 88% of the total tiger prawn catch over the two years. They were found at all sites during the pre-wet season, but after the onset of the wet season, they disappeared along with the algae, from the upstream sites. The brown tiger prawn (P. esculentus) was found almost exclusively (97% of the total catch) on the seagrass sites downstream. In the study of several estuaries, juvenile P. semisulcatus were caught at all 26 sites, and P. esculentus were caught in much smaller numbers, at 16 sites. Approximately equal numbers of P. semisulcatus were caught in seagrass and algal beds in the pre-wet season. Very few individuals >10 mm carapace length of either species, were caught. The results from this study highlight the importance of algal beds during the pre-wet season as nursery areas for one species of tiger prawn (P. semisulcatus).     

Effects of bridge construction on songbirds and small mammals at Blennerhassett Island, Ohio River, USA

Construction of man-made objects such as roads and bridges may have impacts on wildlife depending on species or location. We investigated songbirds and small mammals along the Ohio River, WV, USA at a new bridge both before and after construction and at a bridge crossing that was present throughout the study. Comparisons were made at each site over three time periods (1985–1987 [Phase I] and 1998–2000 [Phase II] [pre-construction], 2007–2009 [Phase III] [post-construction]) and at three distances (0, 100, 300 m) from the bridge or proposed bridge location. Overall, 70 songbirds and 10 small mammals were detected during the study. Cliff swallows (Petrochelidon pyrrhonota) and rock pigeons (Columba livia) showed high affinity for bridges (P?<?0.05). Combined small mammal abundances increased between Phases I and II (P?<?0.05), but did not differ between Phases II and III (P?>?0.05). Species richness and diversity for songbirds and small mammals did not differ before and after bridge construction (P?>?0.05). We found that most species sampled did not respond to the bridge crossing, and believe that the bridge is not causing any measurable negative density impacts to the species we investigated. The new bridge does provide habitat for exotic rock pigeons that are adjusted to man-made structures for nesting.     

RHODAMINE WT DYE LOSSES IN A MOUNTAIN STREAM ENVIRONMENT1

ABSTRACT: A significant fraction of rhodamine WT dye was lost during a short term multitracer injection experiment in a mountain stream environment. The conservative anion chloride and the sorbing cation lithium were concurrently injected. In-stream rhodamine WT concentrations were as low as 45 percent of that expected, based on chloride data. Concentration data were available from shallow‘wells’dug near the stream course and from a seep of suspected return flow. Both rhodamine WT dye and lithium were nonconservative with respect to the conservative chloride, with rhodamine WT dye closely following the behavior of the sorbing lithium. Nonsorption and sorption mechanisms for rhodamine WT loss in a mountain stream were evaluated in laboratory experiments. Experiments evaluating nonsorption losses indicated minimal losses by such mechanisms. Laboratory experiments using sand and gravel size streambed sediments show an appreciable capacity for rhodamine WT sorption. The detection of tracers in the shallow wells and seep indicates interaction between the stream and the flow in the surrounding subsurface, intergravel water, system. The injected tracers had ample opportunity for intimate contact with materials shown in the laboratory experiments to be potentially sorptive. It is suggested that in the study stream system, interaction with streambed gravel was a significant mechanism for the attenuation of rhodamine WT dye (relative to chloride).