Amino acid-specific ADP-ribosylation. Sensitivity to hydroxylamine of [cysteine(ADP-ribose)]protein and [arginine(ADP-ribose)]protein linkages

Hydroxylamine stability has been used to classify (ADP-ribose)protein bonds into sensitive and resistant linkages, with the former representing (ADP-ribose)glutamate, and the latter, (ADP-ribose)arginine. Recently, it was shown that cysteine also serves as an ADP-ribose acceptor. The hydroxylamine stability of [cysteine([32P]ADP-ribose)]protein and [arginine([32P] ADP-ribose)]protein bonds was compared. In transducin, pertussis toxin catalyzes the ADP-ribosylation of a cysteine residue, whereas choleragen (cholera toxin) modifies an arginine moiety. The (ADP-ribose)cysteine bond formed by pertussis toxin was more stable to hydroxylamine than was the (ADP-ribose)arginine bond formed by choleragen. The (ADP-ribose)cysteine bond apparently represents a third class of ADP-ribose bonds. Pertussis toxin ADP-ribosylates the inhibitory guanyl nucleotide-binding regulatory protein (Gi) of adenylate cyclase, whereas choleragen modifies the stimulatory guanyl nucleotide-binding regulatory protein (Gs). These (ADP-ribose)protein linkages are identical in stability to those formed in transducin by the two toxins, consistent with the probability that cysteine and arginine are modified in Gi and Gs, respectively. Bonds exhibiting differences in hydroxylamine-stability were found in membranes from various non-intoxicated mammalian cells following incubation with [32P]NAD, which may reflect the presence of endogenous NAD:protein-ADP-ribosyl-transferases.     

Continuous decisions

Humans and other animals evolved to make decisions that extend over time with continuous and ever-changing options. Nonetheless, the academic study of decision-making is mostly limited to the simple case of choice between two options. Here, we advocate that the study of choice should expand to include continuous decisions. Continuous decisions, by our definition, involve a continuum of possible responses and take place over an extended period of time during which the response is continuously subject to modification. In most continuous decisions, the range of options can fluctuate and is affected by recent responses, making consideration of reciprocal feedback between choices and the environment essential. The study of continuous decisions raises new questions, such as how abstract processes of valuation and comparison are co-implemented with action planning and execution, how we simulate the large number of possible futures our choices lead to, and how our brains employ hierarchical structure to make choices more efficiently. While microeconomic theory has proven invaluable for discrete decisions, we propose that engineering control theory may serve as a better foundation for continuous ones. And while the concept of value has proven foundational for discrete decisions, goal states and policies may prove more useful for continuous ones.This article is part of the theme issue ‘Existence and prevalence of economic behaviours among non-human primates’.     

Three-dimensional Biomimetic Technology: Novel Biorubber Creates Defined Micro- and Macro-scale Architectures in Collagen Hydrogels

Tissue scaffolds play a crucial role in the tissue regeneration process. The ideal scaffold must fulfill several requirements such as having proper composition, targeted modulus, and well-defined architectural features. Biomaterials that recapitulate the intrinsic architecture of in vivo tissue are vital for studying diseases as well as to facilitate the regeneration of lost and malformed soft tissue. A novel biofabrication technique was developed which combines state of the art imaging, three-dimensional (3D) printing, and selective enzymatic activity to create a new generation of biomaterials for research and clinical application. The developed material, Bovine Serum Albumin rubber, is reaction injected into a mold that upholds specific geometrical features. This sacrificial material allows the adequate transfer of architectural features to a natural scaffold material. The prototype consists of a 3D collagen scaffold with 4 and 3 mm channels that represent a branched architecture. This paper emphasizes the use of this biofabrication technique for the generation of natural constructs. This protocol utilizes a computer-aided software (CAD) to manufacture a solid mold which will be reaction injected with BSA rubber followed by the enzymatic digestion of the rubber, leaving its architectural features within the scaffold material.     

Molecular evolution of the period gene in Drosophila athabasca

We measured nucleotide variability within and between the three semispecies of the Drosophila athabasca complex, at the period (per) gene by using a polymerase chain reaction-based four-cutter restriction- enzyme analysis. The levels of polymorphism varied considerably between the three semispecies. Our results for per, combined with previous data for X-linked allozymes, suggest that the X chromosome in the western- northern semispecies is less variable than expected under an equilibrium-neutral model. Both the pattern of divergence between the semispecies and a cladistic clustering of per haplotypes support the previously hypothesized grouping of eastern A and eastern B as the two most recently diverged semispecies. A 21-bp in-frame segment in the region of per which shares sequence similarity with the neuronal development gene single minded is deleted in all eastern A and eastern B flies examined but is present in all of the western-northern flies and all other published per sequences. Despite these hints that there may be significant differences at the per gene between the semispecies, especially the western-northern group versus the two eastern groups, there is no compelling evidence that per is involved in the mating song differences between the semispecies.      

Diversification across an altitudinal gradient in the Tiny Greenbul (Phyllastrephus debilis) from the Eastern Arc Mountains of Africa

Background  

The Eastern Arc Mountains of Africa have become one of the focal systems with which to explore the patterns and mechanisms of diversification among montane species and populations. One unresolved question is the extent to which populations inhabiting montane forest interact with those of adjacent lowland forest abutting the coast of eastern Africa. The Tiny Greenbul (Phyllastephus debilis) represents the only described bird species within the Eastern Arc/coastal forest mosaic, which is polytypic across an altitudinal gradient: the subspecies albigula (green head) is distributed in the montane Usambara and Nguru Mountains whereas the subspecies rabai (grey head) is found in Tanzanian lowland and foothill forest. Using a combination of morphological and genetic data, we aim to establish if the pattern of morphological differentiation in the Tiny Greenbul (Phyllastrephus debilis) is the result of disruptive selection along an altitudinal gradient or a consequence of secondary contact following population expansion of two differentiated lineages.     

Estimation of Multimedia Inorganic Arsenic Intake in the U.S. Population

Arsenic is widely distributed in the environment by natural and human means. The potential for adverse health effects from inorganic arsenic depends on the level and route of exposure. To estimate potential health risks of inorganic arsenic, the apportionment of exposure among sources of inorganic arsenic is critical. In this study, daily inorganic arsenic intake of U.S. adults from food, water, and soil ingestion and from airborne particle inhalation was estimated. To account for variations in exposure across the U.S., a Monte Carlo approach was taken using simulations for 100,000 individuals representing the age, gender, and county of residence of the U.S. population based on census data. Our analysis found that food is the greatest source of inorganic arsenic intake and that drinking water is the next highest contributor. Inhalation of airborne arsenic-containing particles and ingestion of arsenic-containing soils were negligible contributors. The exposure is best represented by the ranges of inorganic arsenic intake (at the 10^th and 90^th percentiles), which were 1.8 to 11.4 µg/day for males and 1.3 to 9.4 µg/day for females. Regional differences in inorganic arsenic exposure were due mostly to consumption of drinking water containing differing inorganic arsenic content rather than to food preferences.     

Homology of the genital sclerites of Megaloptera (Insecta: Neuropterida) and their phylogenetic relevance

The genitalia of Megaloptera are crucial for taxonomic identification and represent a significant component of characters for phylogenetic interpretation of this order. However, several complex genital structures, especially those related to segments 9 and 11 in Megaloptera, have yet to be subjected to a comprehensive survey of homology. The terminology for genital sclerites has been variously and even incorrectly used by different authors, a fact which could lead to much confusion about character evolution. In this paper, we first present a comprehensive morphological comparison of the sclerites of male and female genital segments in 23 megalopteran genera representing all major lineages of Corydalinae, Chauliodinae and Sialidae. Accordingly, we then provide new interpretations on the homology of the genital sclerites which often appear to be considerably different among Megaloptera. Based on our new and revised homology assessments, we conclude that: (i) the small to medium‐sized sclerite beneath the ectoprocts in males of Sialidae represents the fused gonocoxites 11; (ii) the male gonocoxites 11 in Corydalidae are largely reduced and are sometimes retained as a small sclerite beneath the anus; (iii) the predominant sternite‐like sclerite of the female abdominal segment 8 represents the fused gonocoxites 8; and (iv) a pair of sclerites amalgamated with the lateral arms of male gonocoxites 10 in Chauliodinae is the gonocoxites 9. Furthermore, based on our genital homology assessments, we reconstruct an intergeneric phylogeny including all genera of Megaloptera using genital characters in a parsimonious analysis to test their phylogenetic relevance. The phylogeny herein recovered is largely congruent with the results from several previous studies, thus underlying the significant phylogenetic relevance of the megalopteran genital sclerites. The present work provides new insights into the evolution of insect genitalia.     

Risk Assessment as a Decision-Making Tool for Treatment of Emissions at a New Aluminum Smelter in Iceland: 1. Background and Introduction

Protection of human health and ecosystems is gaining importance in corporate decision- making regarding industrial development. During the design phase for an aluminum smelter in East Iceland, it became necessary to determine whether a wet scrubber system should be installed to reduce sulfur dioxide emissions. Predictive risk assessment was used to determine whether there would be a consequential difference in the level of risk to human and ecological receptors from constituents in air emissions from the aluminum smelter, either with or without wet scrubbers. Benchmark exposure concentrations were established for avian, mammalian, and plant receptors and were compared to air modeling predictions to develop risk estimates. Benchmark concentrations were derived using plant uptake models for fluoride and polycyclic aromatic hydrocarbons (PAHs), and food-web modeling for birds and mammals. Exposure models were developed for all receptors, and population-level effects were modeled for plant, bird, and mammal receptors. Results indicated that exposures under both scenarios are lower than risk thresholds, and overall risk was lower for a smelter without wet scrubbers. Thus, although mass loading of sulfur dioxide (and other constituents) would be reduced using wet scrubbers, the corresponding risk to ecological receptors would actually be higher because of higher exposure-point concentrations in air.     

What shapes local density? The importance of migration rates and local growth for density‐patch size relationships in two Cionus weevils

1. The relative effect of migration and local growth on the spatio‐temporal density‐distribution of two co‐existing herbivorous weevils, Cionus scrophulariae L. and C. tuberculosus Scop., in 32 host plant Scrophularia nodosa L. patches of varying sizes was investigated. 2. Predictions of the temporal development of the slope in the density‐patch size relationships were derived from a basic population model with scale‐dependent migration rates. The model indicated that the slopes in the density‐patch size relationships during the early season should be reflected by the net scaling of immigration and emigration rates, whereas the slopes during the later season should increase as a result of local growth. 3. Emigration rates of the weevils were estimated in a field experiment, were the weevils coexisted in space and time. These results were then combined with a previous estimate of immigration rates in order to determine the net scaling of migration rates. 4. The emigration rate differed between species, caused by different movement rates in small patches, which could explain differences in the general slope of the density‐patch size relationships of the weevils in the natural figwort patches throughout the summer. The slopes in the relationships in the early season were largely predicted by the net scaling of migration rates. The slope also increased in the later season for C. tuberculosus, whereas the slope decreased for C. scrophulariae. 5. It was concluded that the understanding of both inter‐ and intra‐specific variations in density‐patch size relationships of insect herbivores can be improved using population models incorporating scale‐dependent migration and local growth.