Silent Spring - the lost call

The "silence" in Rachel Carson's Silent Spring1 alludes to the demise of bird populations through reproductive problems and death resulting from exposure to the pesticides of that time, many of which are endocrine active. Endocrine disrupting chemicals (EDCs) are compounds which may interfere with the endocrine system, producing effects that may disrupt the physiologic function of hormones. Early research on EDC exposure in humans and wildlife has focused mainly on reproductive effects of estrogenic chemicals, however recent studies have revealed that effects of estrogenic as well as non-estrogen active chemicals are often more far reaching than the reproductive system, and even mild exposures experienced early in development may have detrimental effects that are maintained throughout adulthood. Here we show trenbolone acetate, an androgen active environmental contaminant used as a growth promoter for cattle, to cause a literal silence in Japanese quail (Coturnix japonica) chicks following a one time embryonic exposure. Vocalizations were not merely lessened; this is the first study to demonstrate an environmental contaminant to cause a complete abolishment of the ability to vocalize. Since many reasons for vocalization in birds are directly linked to survival of the individual and species, the potential for detrimental population effects is a grave possibility for many avian species that may encounter androgen active chemicals in the environment. Many androgen active EDCs are persistent and ubiquitous in distribution, thereforechances for exposure to these chemicals in birds may be high. We hope that powerful, yet subtle effects like the ones presented here will encourage further research with EDCs to expand beyond the traditional focus of reproductive effects of estrogenic chemicals

Flavor altering excitations of composite fermions

Past theoretical studies have considered excitations of a given flavor of composite fermions across composite-fermion quasi-Landau levels. We show that in general there exists a ladder of flavor changing excitations in which composite fermions shed none, some, or all of their vortices. The lowest energy excitations are obtained when the composite fermions do not change their flavor, whereas in the highest energy excitations they are stripped of all of their vortices, emerging as electrons in the final state. The results are relevant to the intriguing experimental discovery of Hirjibehedin {\em et al.} (cond-mat/0306152) of coexisting excitation modes of composite fermions of different flavor in the filling factor range $1/3>\nu\geq 1/5$.Comment: 5 pages, 4 figure

The joint US/UK 1990 epoch world magnetic model

A detailed summary of the data used, analyses performed, modeling techniques employed, and results obtained in the course of the 1990 Epoch World Magnetic Modeling effort are given. Also, use and limitations of the GEOMAG algorithm are presented. Charts and tables related to the 1990 World Magnetic Model (WMM-90) for the Earth's main field and secular variation in Mercator and polar stereographic projections are presented along with useful tables of several magnetic field components and their secular variation on a 5-degree worldwide grid

Crowding-induced hybridization of single DNA hairpins

It is clear that a crowded environment influences the structure, dynamics, and interactions of biological molecules, but the complexity of this phenomenon demands the development of new experimental and theoretical approaches. Here we use two complementary single-molecule FRET techniques to show that the kinetics of DNA base pairing and unpairing, which are fundamental to both the biological role of DNA and its technological applications, are strongly modulated by a crowded environment. We directly observed single DNA hairpins, which are excellent model systems for studying hybridization, either freely diffusing in solution or immobilized on a surface under crowding conditions. The hairpins followed two-state folding dynamics with a closing rate increasing by 4-fold and the opening rate decreasing 2-fold, for only modest concentrations of crowder [10% (w/w) polyethylene glycol (PEG)]. These experiments serve both to unambiguously highlight the impact of a crowded environment on a fundamental biological process, DNA base pairing, and to illustrate the benefits of single-molecule approaches to probing the structure and dynamics of complex biomolecular systems

CMV-Specific CD8 T Cell Differentiation and Localization: Implications for Adoptive Therapies.

Human cytomegalovirus (HCMV) is a ubiquitous virus that causes chronic infection and, thus, is one of the most common infectious complications of immune suppression. Adoptive transfer of HCMV-specific T cells has emerged as an effective method to reduce the risk for HCMV infection and/or reactivation by restoring immunity in transplant recipients. However, the CMV-specific CD8(+) T cell response is comprised of a heterogenous mixture of subsets with distinct functions and localization, and it is not clear if current adoptive immunotherapy protocols can reconstitute the full spectrum of CD8(+) T cell immunity. The aim of this review is to briefly summarize the role of these T cell subsets in CMV immunity and to describe how current adoptive immunotherapy practices might affect their reconstitution in patients. The bulk of the CMV-specific CD8(+) T cell population is made up of terminally differentiated effector T cells with immediate effector function and a short life span. Self-renewing memory T cells within the CMV-specific population retain the capacity to expand and differentiate upon challenge and are important for the long-term persistence of the CD8(+) T cell response. Finally, mucosal organs, which are frequent sites of CMV reactivation, are primarily inhabited by tissue-resident memory T cells, which do not recirculate. Future work on adoptive transfer strategies may need to focus on striking a balance between the formation of these subsets to ensure the development of long lasting and protective immune responses that can access the organs affected by CMV disease

Effects of contaminants of emerging concern on Megaselia scalaris (Lowe, Diptera: Phoridae) and its microbial community.

Drought, rising temperatures, and expanding human populations are increasing water demands. Many countries are extending potable water supplies by irrigating crops with wastewater. Unfortunately, wastewater contains biologically active, long-lived pharmaceuticals, even after treatment. Run-off from farms and wastewater treatment plant overflows contribute high concentrations of pharmaceuticals to the environment. This study assessed the effects of common pharmaceuticals on a cosmopolitan saprophagous insect, Megaselia scalaris (Diptera: Phoridae). Larvae were reared on artificial diets spiked with contaminants of emerging concern (CECs) at environmentally relevant concentrations. Female flies showed no oviposition preference for treated or untreated diets. Larvae exposed to caffeine in diets showed increased mortality, and larvae fed antibiotics and hormones showed signs of slowed development, especially in females. The normal sex ratio observed in M. scalaris from control diets was affected by exposure to caffeine and pharmaceutical mixture treatments. There was an overall effect of treatment on the flies' microbial communities; notably, caffeine fed insects displayed higher microbial variability. Eight bacterial families accounted for approximately 95% of the total microbes in diet and insects. Our results suggest that CECs at environmentally relevant concentrations can affect the biology and microbial communities of an insect of ecological and medical importance

Banning Commercial Foresting: What are the Costs?

The Philippines' forest cover has suffered from massive denudation through the years due to uncontrolled and indiscriminate commercial logging. Because of this, calls for a total logging ban had been raised in various fora, including in the legislature where bills that consider the possibility of a ban are being studied. However, the possible economic costs of such ban as espoused in some studies has delayed the passage of these bills. This Policy Notes provides some economic costing based on computations that may help in firming up decisions regarding the proposed ban.forestry sector, environmental issues, environmental management