Regulation of sex-specific feeding behavior in fiddler crabs: physiological properties of chemoreceptor neurons in claws and legs of males and females

This study examined properties of chemoreceptor neurons in the claws and legs of the fiddler crabs Uca pugilator and U. pugnax. The primary goal was to establish the neural basis of previously observed greater female sensitivity to feeding stimulants, and secondarily to compare physiological properties of chemoreceptor neurons in these semi-terrestrial crustaceans with those of fully aquatic forms. Sensitivity of chemoreceptor neurons in claws and legs is sex-specific; individual neurons of females respond to lower stimulus concentrations than male chemoreceptor neurons, and equivalent concentrations elicit greater spiking in female vs male chemoreceptor neurons. Thus, the population of chemoreceptor neurons in females expresses lower thresholds and greater average sensitivity than in males. Greater sensitivity of claw neurons explains observations indicating that females continue to feed at food levels too low to stimulate males. Sensitivity differences in leg neurons of males vs females have no clear behavioral correlate, but suggest that females can orient to more dilute stimuli than males. Chemoreceptor neurons of fiddler crabs have low sensitivities and slow rates of adaptation compared to other crustaceans. Also, neurons in claws adapt less slowly than neurons in legs, which may reflect subtle differences in the chemical stimulus environment experienced by claws vs legs.     

Multiple excitatory receptor types on individual olfactory neurons: implications for coding of mixtures in the spiny lobster

The aim of our paper was to investigate whether single olfactory receptor neurons (ORNs) of the spiny lobster Panulirus argus functionally express more than one type of receptor, examine the consequences of this on coding of mixtures, and compare principles of odorant mixture coding by spiny lobsters with that by the channel catfish, which has been studied extensively using the same experimental and analytical procedures (Caprio et al. 1989; Kang and Caprio 1991). We examined responses of individual taurine-sensitive ORNs to binary mixtures of excitatory compounds, either competitive agonists (taurine, β-alanine, hypotaurine) or non-competitive agonists (taurine, l-glutamate, ammonium chloride, adenosine-5′-monophosphate). Responses to mixtures were compared to two indices: mixture discrimination index (MDI) and independent component index (ICI). Binary mixtures of competitive agonists had MDI values close to 1.0, as expected for competitors. Mixtures of non-competitive agonists had ICI values averaging 0.83, indicating the effects of the components are not independent. We conclude that individual olfactory cells of spiny lobsters can express more than one type of receptor mediating excitation, one of which typically has a much higher density or affinity, and that spiny lobster and catfish olfactory cells encode mixtures of two excitatory agonists using similar rules. Accepted: 20 December 1996     

Respect for outsiders? respect for the law? the moral evaluation of high scale issues by US immigration officers

High-scale morality is the study of moral ideas and sentiments deployed in relations that encompass multiple, geographically or socially distant populaces. The envisioning of distant people, their attributed moral personhood, the evaluation of their perceived behaviour, and the rectification of wrongs through the use of powerful organizations are key topics in high-scale morality. High-scale morality differs from existing anthropological approaches that emphasize local ethnography or contrastive moral ideas; it addresses the moralization of issues like world hunger, the drug trade, or international migration. The officers of the US Immigration and Naturalization Service understand and evaluate legal and illegal immigrants, as well as directly enacting moral rectification for the US polity. As they resolve moral dilemmas on their job, they utilize pervasive models for moral thought and action in capitalist, individualist, stratified, and bureaucratized societies. The article finishes by considering directions in which anthropology can contribute to understanding the moral dimension of global issues.     

One-step refolding and purification of disulfide-containing proteins with a C-terminal MESNA thioester

Background  

Expression systems based on self-cleavable intein domains allow the generation of recombinant proteins with a C-terminal thioester. This uniquely reactive C-terminus can be used in native chemical ligation reactions to introduce synthetic groups or to immobilize proteins on surfaces and nanoparticles. Unfortunately, common refolding procedures for recombinant proteins that contain disulfide bonds do not preserve the thioester functionality and therefore novel refolding procedures need to be developed.     

Double-Stranded RNA Analog Poly(I:C) Inhibits Human Immunodeficiency Virus Amplification in Dendritic Cells via Type I Interferon-Mediated Activation of APOBEC3G

Human immunodeficiency virus (HIV) is taken up by and replicates in immature dendritic cells (imDCs), which can then transfer virus to T cells, amplifying the infection. Strategies known to boost DC function were tested for their ability to overcome this exploitation when added after HIV exposure. Poly(I:C), but not single-stranded RNA (ssRNA) or a standard DC maturation cocktail, elicited type I interferon (IFN) and interleukin-12 (IL-12) p70 production and the appearance of unique small (15- to 20-kDa) fragments of APOBEC3G (A3G) and impeded HIV_Bal replication in imDCs when added up to 60 h after virus exposure. Comparable effects were mediated by recombinant alpha/beta IFN (IFN-α/β). Neutralizing the anti-IFN-α/β receptor reversed poly(I:C)-induced inhibition of HIV replication and blocked the appearance of the small A3G proteins. The poly(I:C)-induced appearance of small A3G proteins was not accompanied by significant differences in A3G mRNA or A3G monomer expression. Small interfering RNA (siRNA) knockdown of A3G could not be used to reverse the poly(I:C)-induced protective effect, since siRNAs nonspecifically activated the DCs, inducing the appearance of the small A3G proteins and inhibiting HIV infection. Notably, the appearance of small A3G proteins coincided with the shift of high-molecular-mass inactive A3G complexes to the low-molecular-mass (LMM) active A3G complexes. The unique immune stimulation by poly(I:C) with its antiviral effects on imDCs marked by the expression of IFN-α/β and active LMM A3G renders poly(I:C) a promising novel strategy to combat early HIV infection in vivo.