Environmental regulation through trade: the case of shrimp

The implications of a potential ban on shrimp imports by the US from countries that do not utilize the Turtle Excluder Device on commercial shrimp nets is explored in this paper. A Linear Expenditure System (LES) was used to determine the own-price elasticities of demand for shrimp imports. The system of estimated equations was then solved for quantity levels under assumptions made about the trade restrictions, resulting in a set of prices for those import levels. These estimated prices were then used to estimate the compensating variation impact of the trade restrictions. Findings suggest that the environmental regulation would have a negative impact on US consumers, but the magnitude of that effect depends on assumptions made regarding the distribution of US imports after the trade restriction is imposed.     

A chromosome 21-specific cosmid cocktail for the detection of chromosome 21 aberrations in interphase nuclei

Fluorescent in situ hybridization (FISH) with a 21q11-specific probe (CB21c1) consisting of three non-overlapping cosmids has been applied to interphase amniocytes of pregnancies at increased risk for fetal aneuploidy (N = 78) and to interphase lymphocytes, cultured and uncultured, of patients referred for Down syndrome (N = 19 and 28, respectively). In the uncultured amniocytes, six chromosome aberrations were detected: three cases of trisomy 21, a triploidy, a de novo 46,XX,t(21q21q), and a mosaic 46,XY/47,XY,+dic(21)(q11)/48,XY,+dic(21)(q11), +del(21)(q11). In 15 cultured and 20 uncultured blood samples, FISH correctly diagnosed trisomy 21 (full or mosaic) at the interphase level, which was confirmed in all cases by subsequent karyotyping. Because of specific and strong signals in interphase nuclei, CB21c1 appears to be a useful tool for the rapid detection of chromosome 21 abnormalities.     

Valuation of cancer and microbial disease risk reductions in municipal drinking water: An analysis of risk context using multiple valuation methods

We examine the value of health risk reductions (microbial illnesses/deaths and bladder cancer illnesses/deaths) in the context of drinking water quality treatment by public systems. When we assume that combined mortality and morbidity risk reductions are equally spread in the future; our results suggest that microbial risk-reduction programs have higher value than cancer risk-reduction programs, but that mortality risk reduction values are not significantly different for cancer and microbials. However, when a 25-year cancer latency is accounted for and a 5% discount rate is used, the value of cancer mortality risk reductions exceeds the value for microbial risk reductions. We also address a number of methodological issues, including performance of alternative choice experiment estimation (CE) techniques, relationship of CE to contingent valuation results, and implications for incorporating morbidity and mortality endpoints in the same survey instrument.     

Nitrous oxide emissions from wastewater treatment and water reclamation plants in southern California

Nitrous oxide (N?O) is a long-lived and potent greenhouse gas produced during microbial nitrification and denitrification. In developed countries, centralized water reclamation plants often use these processes for N removal before effluent is used for irrigation or discharged to surface water, thus making this treatment a potentially large source of N?O in urban areas. In the arid but densely populated southwestern United States, water reclamation for irrigation is an important alternative to long-distance water importation. We measured N?O concentrations and fluxes from several wastewater treatment processes in urban southern California. We found that N removal during water reclamation may lead to in situ N?O emission rates that are three or more times greater than traditional treatment processes (C oxidation only). In the water reclamation plants tested, N?O production was a greater percentage of total N removed (1.2%) than traditional treatment processes (C oxidation only) (0.4%). We also measured stable isotope ratios (δN and δO) of emitted N?O and found distinct δN signatures of N?O from denitrification (0.0 ± 4.0 ‰) and nitrification reactors (-24.5 ± 2.2 ‰), respectively. These isotope data confirm that both nitrification and denitrification contribute to N?O emissions within the same treatment plant. Our estimates indicate that N?O emissions from biological N removal for water reclamation may be several orders of magnitude greater than N?O emissions from agricultural activities in highly urbanized southern California. Our results suggest that wastewater treatment that includes biological nitrogen removal can significantly increase urban N?O emissions.     

In vitro conservation and sustained production of breadfruit (Artocarpus altilis, Moraceae): modern technologies for a traditional tropical crop

Breadfruit (Artocarpus altilis, Moraceae) is a traditionally cultivated, high-energy, high-yield crop, but widespread use of the plant for food is limited by poor quality and poor storage properties of the fruit. A unique field genebank of breadfruit species and cultivars exists at the National Tropical Botanical Garden in the Hawaiian Islands and is an important global resource for conservation and sustainable use of breadfruit. However, this plant collection could be damaged by a random natural disaster such as a hurricane. We have developed a highly efficient in vitro plant propagation system to maintain, conserve, mass propagate, and distribute elite varieties of this important tree species. Mature axillary shoot buds were collected from three different cultivars of breadfruit and proliferated using a cytokinin-supplemented medium. The multiple shoots were maintained as stock cultures and repeatedly used to develop whole plants after root differentiation on a basal or an auxin-containing medium. The plantlets were successfully grown under greenhouse conditions and were reused to initiate additional shoot cultures for sustained production of plants. Flow cytometry was used to determine the nuclear deoxyribonucleic acid content and the ploidy status of the in vitro grown population. The efficacy of the micropropagation protocols developed in this study represents a significant advancement in the conservation and sustained mass propagation of breadfruit germplasm in a controlled environment free from contamination.