Brood production and lineage discrimination in the red harvester ant (Pogonomyrmex barbatus)

In contrast to the system of caste determination in most social insects, reproductive caste determination in some populations of Pogonomyrmex barbatus has a genetic basis. Populations that exhibit genetic caste determination are segregated into two distinct, genetic lineages. Same-lineage matings result in female reproductives, while inter-lineage matings result in workers. To investigate whether founding P. barbatus queens lay eggs of reproductive genotype, and to determine the fate of those eggs, we genotyped eggs, larvae, and pupae produced by naturally inseminated, laboratory-raised queens. We show that founding dependent lineage queens do lay eggs of reproductive genotype, and that the proportion of reproductive genotypes decreases over the course of development from eggs to larvae to pupae. Because queens must mate with a male of each lineage to produce both workers and female reproductives, it would benefit queens to be able to distinguish males of the two lineages. Here we show that P. barbatus males from the two genetic lineages differ in their cuticular hydrocarbon profiles. Queens could use male cuticular hydrocarbons as cues to assess the lineage of males at the mating aggregation, and possibly keep mating until they have mated with males of both lineages.     

Development of the vertebrate central nervous system: formation of the neural tube

The developmental process of neurulation involves a series of coordinated morphological events, which result in conversion of the flat neural plate into the neural tube, the primordium of the entire central nervous system (CNS). Failure of neurulation results in neural tube defects (NTDs), severe abnormalities of the CNS, which are among the commonest of congenital malformations in humans. In order to gain insight into the embryological basis of NTDs, such as spina bifida and anencephaly, it is necessary to understand the morphogenetic processes and molecular mechanisms underlying neural tube closure. The mouse is the most extensively studied mammalian experimental model for studies of neurulation, while considerable insight into underlying developmental mechanisms has also arisen from studies in other model systems, particularly birds and amphibians. We describe the process of neural tube formation, discuss the cellular mechanisms involved and highlight recent findings that provide links between molecular signaling pathways and morphogenetic tissue movements. Copyright © 2009 John Wiley & Sons, Ltd.     

The Identification of Atmospheric Nitric Oxide by a Spectroscopic Scan

Lines of the 1-0 band of NO near 5.3 jum have been observed in spectra of approximately 500 m of ground-level air at Columbus, Ohio, on several occasions between October 1970 and January 1971. The estimated NO abundances lie between 0.0 and 0.08 ppm with uncertainties of ±0.01 ppm.     

Conservation‐Induced Wastewater Flow Reductions Improve Nitrogen Removal: Evidence from New York City1

Abstract: Water resources are under increasing pressure to meet potable supply needs while sustaining aquatic ecosystems and fisheries. Growing populations and enforcement of the Total Maximum Daily Load provisions of the Clean Water Act present public water and wastewater utilities with costly options to meet potable water demands and reduce pollutant discharges into receiving waters. This paper documents that New York City’s comprehensive water conservation program – designed to extend the city’s safe yield of potable water—has also resulted in reduced nitrogen discharges from the city’s water pollution control plants during a period of population increases. This paper demonstrates and quantifies the effects that wastewater inflow volume reductions have on increased nitrogen removal, controlling for plant process changes. Conservation programs have saved the city billions of dollars in delayed or avoided capital improvements to both water and wastewater treatment plants, and have enabled the city to meet interim effluent discharge standards.     

Effects of Metal Mining and Milling on Boundary Waters of Yellowstone National Park, USA

/ Aquatic resources in Soda Butte Creek within Yellowstone National Park, USA, continue to be threatened by heavy metals from historical mining and milling activities that occurred upstream of the park's boundary. This includes the residue of gold, silver, and copper ore mining and processing in the early 1900s near Cooke City, Montana, just downstream of the creek's headwaters. Toxicity tests, using surrogate test species, and analyses of metals in water, sediments, and macroinvertebrate tissue were conducted from 1993 to 1995. Chronic toxicity to test species was greater in the spring than the fall and metal concentrations were elevated in the spring with copper exceeding water quality criteria in 1995. Tests with amphipods using pore water and whole sediment from the creek and copper concentrations in the tissue of macroinvertebrates and fish also suggest that copper is the metal of concern in the watershed. In order to understand current conditions in Soda Butte Creek, heavy metals, especially copper, must be considered important factors in the aquatic and riparian ecosystems within and along the creek extending into Yellowstone National Park.KEY WORDS: Mining; Metals; Toxicity; Biomonitoring; Copper; Yellowstone National Park     

Effects of high-frequency light fluctuations on growth and photoacclimation of the red algaChondrus crispus

High-frequency fluctuations due to wavefocusing are prominent characteristics of light in shallow marine environments. Effects of high-frequency (0.01 to 1 Hz) fluctuating light on growth rates of the red algaChondrus crispus Stackh., collected from Crane Neck Point, New York, USA, during July 1988, were determined by comparing plants grown under fluctuating and constant light regimes with similar daily irradiances. At high daily irradiance, growth rates were higher under fluctuating light than under constant light. Fluctuating light effects were frequency-dependent; growth was enhanced by fluctuations at 0.1 and 1 Hz, but not by fluctuations at 0.01 Hz. At low daily irradiance, growth rates were not affected by fluctuating light at any frequency tested. Enhancement of growth was not due to effects of high-frequency light fluctuations on photoacclimation responses ofC. crispus. Plants grown under fluctuating light at high daily irradiance actually exhibited lower photosynthetic capacity and efficiency (determined under constant light) than plants grown under constant light. These differences were attributable to variation in the density of Photosystem II reaction centers, which was low in plants grown under fluctuating light. Maximum turnover rate of whole-chain electron transport and activity of ribulose-1,5-bisphosphate carboxylase were affected by total daily irradiance, but not by high-frequency light fluctuations. Enhancement of growth under fluctuating light was partly attributable to reduced rates of dark respiration compared to rates of plants grown under constant light. The results also provided indirect evidence that high-frequency light fluctuations may enhance instantaneous photosynthetic rates. This effect could increase daily carbon gain and, therefore, stimulate growth ofC. crispus under high-frequency light fluctuations.     

Biodegradation of starch-poly(β-hydroxybutyrate-co-valerate) composites in municipal activated sludge

Injection-molded composites were prepared by blending PHBV⁵ with native cornstarch (30% and 50%) and with cornstarch precoated with PEO as a binding agent. These composites were evaluated for their biodegradability in municipal activated sludge by measuring changes in their physical and chemical properties over a period of 35 days. All composites lost weight, ranging from 45 to 78% within 35 days. Interestingly, the extent and rate of weight loss were quite similar in PHBV composites with no starch, with 30% starch, and with 50% starch. Weight loss was slowest in PHBV blends prepared with PEO-coated starch. For all samples, the weight loss was accompanied by a rapid deterioration in tensile strength and percentage elongation. The deterioration of these mechanical properties exhibited a relative rate of PHBV>starch-PHBV>PEO-coated starch-PHBV. Changes in starch/PHBV composition after biodegradation were quantified by FTIR spectroscopy. Increasing the starch content resulted in more extensive starch degradation, while the PHBV content in the blends became less susceptible to hydrolytic enzymes.The mention of firms names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over firms or similar products not mentioned. All programs and services of the U.S. Department of Agriculture are offered on a nondiscriminatory basis without regard to race, color, national origin, religion, sex, marital status, or handicap.     

Lead in New York City community garden chicken eggs: influential factors and health implications

Raising chickens for eggs in urban areas is becoming increasingly common. Urban chickens may be exposed to lead, a common urban soil contaminant. We measured lead concentrations in chicken eggs from New York City (NYC) community gardens and collected information on factors that might affect those concentrations. Lead was detected between 10 and 167 μg/kg in 48 % of NYC eggs. Measures of lead in eggs from a henhouse were significantly associated (p < 0.005) with lead concentrations in soil. The association between soil and egg lead has been evaluated only once before, by a study of a rural region in Belgium. In our study, the apparent lead soil-to-egg transfer efficiency was considerably lower than that found in Belgium, suggesting that there may be important geographic differences in this transfer. We developed models that suggested that, for sites like ours, lead concentrations in >50 % of eggs from a henhouse would exceed store-bought egg concentrations (<7–13 μg/kg; 3 % above detection limit) at soil lead concentrations >120 mg/kg and that the concentration in one of six eggs from a henhouse would exceed a 100 μg/kg guidance value at soil lead concentrations >410 mg/kg. Our models also suggested that the availability of dietary calcium supplements was another influential factor that reduced egg lead concentrations. Estimates of health risk from consuming eggs with the lead concentrations we measured generally were not significant. However, soil lead concentrations in this study were <600 mg/kg, and considerably higher concentrations are not uncommon. Efforts to reduce lead transfer to chicken eggs and associated exposure are recommended for urban chicken keepers.     

Biodegradation of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by a Tropical Marine Bacterium, Pseudoalteromonas sp. NRRL B-30083

Pseudoalteromonas sp. NRRL B-30083 was isolated as the predominant PHBV-degrading organism from a tropical marine environment. In complex medium, the isolate grew well at temperatures between 23°C and 33°C, with an optimal doubling time of about 30 min. NaCl was required at concentrations between 0.2 N and 0.8 N. Optimal pH levels for growth were between pH 6.5 and pH 8.5. Liquid cultures grew modestly on PHBV as a sole carbon source under optimal conditions, although PHBV depolymerase activity was not detected.