A direct test of the effects of changing atmospheric pressure on the mating behavior of Drosophila melanogaster

Changes in weather can be catastrophic for small insects. As such, it would be highly adaptive for insects to be able to sense when a weather front is approaching and respond appropriately. While correlative and anecdotal evidence exists that flies behaviorally respond to changes in barometric pressure, which indicate variation in weather, a direct test has yet to be performed. Here, we subject multiple strains of Drosophila melanogaster to changes in barometric pressure within a hypobaric chamber and measure male courtship and female receptivity. Since this species has a long copulation duration, copulating when adverse weather is approaching could subject both males and females to potentially lethal conditions. As predicted, some flies reduced their mating activity when exposed to a change in pressure that indicated imminent adverse weather. Surprisingly, however, some flies instead increased their mating activity; the behavioral response depended upon the strain’s native population location and intra-population variation, demonstrating that there is genetic variation for the behavioral response. This indicates that flies are able to anticipate weather patterns and change their behavior depending on the barometric pressure they experience, but that the form of behavioral response varies both within and between populations.     

Boron neutron capture synovectomy (BNCS) as a potential therapy for rheumatoid arthritis: boron biodistribution study in a model of antigen-induced arthritis in rabbits

Boron neutron capture synovectomy (BNCS) is explored for the treatment of rheumatoid arthritis (RA). The aim of the present study was to perform boron biodistribution studies in a model of antigen-induced arthritis (AIA) in female New Zealand rabbits, with the boron carriers boronophenylalanine (BPA) and sodium decahydrodecaborate (GB-10) to assess the potential feasibility of BNCS for RA. Rabbits in chronic phase of AIA were used for biodistribution studies employing the following protocols: intra-articular (ia) (a) BPA-f 0.14 M (0.7 mg ¹⁰B), (b) GB-10 (5 mg ¹⁰B), (c) GB-10 (50 mg ¹⁰B) and intravenous (iv), (d) BPA-f 0.14 M (15.5 mg ¹⁰B/kg), (e) GB-10 (50 mg ¹⁰B/kg), and (f) BPA-f (15.5 mg ¹⁰B/kg) + GB-10 (50 mg ¹⁰B/kg). At different post-administration times (13–85 min for ia and 3 h for iv), samples of blood, pathological synovium (target tissue), cartilage, tendon, muscle, and skin were taken for boron measurement by inductively coupled plasma mass spectrometry. The intra-articular administration protocols at <40 min post-administration both for BPA-f and GB-10, and intravenous administration protocols for GB-10 and [GB-10 + BPA-f] exhibited therapeutically useful boron concentrations (>20 ppm) in the pathological synovium. Dosimetric estimations suggest that BNCS would be able to achieve a therapeutically useful dose in pathological synovium without exceeding the radiotolerance of normal tissues in the treatment volume, employing boron carriers approved for use in humans. Radiobiological in vivo studies will be necessary to determine the actual therapeutic efficacy of BNCS to treat RA in an experimental model.     

Superparasitism strategies by a native and an exotic parasitoid species attacking the Mexican fruit fly,Anastrepha ludens (Diptera: Tephritidae)

Superparasitism refers to the action of parasitoids ovipositing eggs in hosts that are already parasitized; this inevitably results in the elimination of supernumerary larvae in solitary parasitoids. Here, we investigated superparasitism performed by two species of solitary parasitoids on the larvae of Anastrepha ludens (Loew; Diptera: Tephritidae): a native species, Doryctobracon crawfordi (Viereck; Hymenoptera: Braconidae), and an exotic species, Diachasmimorpha tryoni (Cameron; Hymenoptera: Braconidae). Tests were conducted under laboratory conditions evaluating the behaviour of females acting alone (self-superparasitism) or in groups (conspecific superparasitism). Parasitism strategies were different between these two species. In D. crawfordi, the number of first instar larvae found in each dissected host pupa was never greater than two, regardless of the number of oviposition scars observed per pupa. In contrast, there was a positive correlation between the number of oviposition scars and the number of first instar larvae in D. tryoni. The survival and fecundity of D. crawfordi females emerging from pupae with one scar was higher than in females emerging from pupae with more scars. In D. tryoni, the number of oviposition scars did not show deleterious effects on life history traits and was positively correlated with the proportion of emerging females. An understanding of the superparasitism strategy adopted by parasitoid species could be of great interest to augmentative biological control programmes because the mass rearing of natural enemies could be negatively or positively affected by this condition.     

Trafficking of the myrosinase‐associated protein GLL23 requires NUC/MVP1/GOLD36/ERMO3 and the p24 protein CYB

Proteins detrimental to endoplasmic reticulum (ER) morphology need to be efficiently exported. Here, we identify two mechanisms that control trafficking of Arabidopsis thalianaGLL23, a 43 kDa GDSL‐like lipase implicated in glucosinolate metabolism through its association with the β‐glucosidase myrosinase. Using immunofluorescence, we identified two mutants that showed aberrant accumulation of GLL23: large perinuclear ER aggregates in the nuclear cage (nuc) mutant; and small compartments contiguous with the peripheral ER in the cytoplasmic bodies (cyb) mutant. Live imaging of fluorescently tagged GLL23 confirmed its presence in the nuc and cyb compartments, but lack of fluorescent signals in the wild‐type plants suggested that GLL23 is normally post‐translationally modified for ER export. NUC encodes the MVP1/GOLD36/ERMO3 myrosinase‐associated protein, previously shown to have vacuolar distribution. CYB is an ER and Golgi‐localized p24 type I membrane protein component of coat protein complex (COP) vesicles, animal and yeast homologues of which are known to be involved in selective cargo sorting for ER–Golgi export. Without NUC, GLL23 accumulates in the ER this situation suggests that NUC is in fact active in the ER. Without CYB, both GLL23 and NUC were found to accumulate in cyb compartments, consistent with a role for NUC in GLL23 processing and indicated that GLL23 is the likely sorting target of the CYB p24 protein.     

Patterns of selection on Plasmodium falciparum erythrocyte‐binding antigens after the colonization of the New World

Pathogens, which have recently colonized a new host species or new populations of the same host, are interesting models for understanding how populations may evolve in response to novel environments. During its colonization of South America from Africa, Plasmodium falciparum, the main agent of malaria, has been exposed to new conditions in distinctive new human populations (Amerindian and populations of mixed origins) that likely exerted new selective pressures on the parasite's genome. Among the genes that might have experienced strong selective pressures in response to these environmental changes, the eba genes (erythrocyte‐binding antigens genes), which are involved in the invasion of the human red blood cells, constitute good candidates. In this study, we analysed, in South America, the polymorphism of three eba genes (eba‐140, eba‐175, eba‐181) and compared it to the polymorphism observed in African populations. The aim was to determine whether these genes faced selective pressures in South America distinct from what they experienced in Africa. Patterns of genetic variability of these genes were compared to the patterns observed at two housekeeping genes (adsl and serca) and 272 SNPs to separate adaptive effects from demographic effects. We show that, conversely to Africa, eba‐140 seemed to be under stronger diversifying selection in South America than eba‐175. In contrast, eba‐181 did not show any sign of departure from neutrality. These changes in the patterns of selection on the eba genes could be the consequence of changes in the host immune response, the host receptor polymorphisms and/or the ability of the parasite to silence or express differentially its invasion proteins.     

Mechanisms of drift-feeding behavior in juvenile Chinook salmon and the role of inedible debris in a clear-water Alaskan stream

Drift-feeding fish are challenged to discriminate between prey and similar-sized particles of debris, which are ubiquitous even in clear-water streams. Spending time and energy pursuing debris mistaken as prey could affect fish growth and the fitness potential of different foraging strategies. Our goal was to determine the extent to which debris influences drift-feeding fish in clear water under low-flow conditions when the distracting effect of debris should be at a minimum. We used high-definition video to measure the reactions of drift-feeding juvenile Chinook salmon (Oncorhynchus tshawytscha) to natural debris and prey in situ in the Chena River, Alaska. Among all potential food items fish pursued, 52 % were captured and quickly expelled from the mouth, 39 % were visually inspected but not captured, and only 9 % were ingested. Foraging attempt rate was only moderately correlated with ingestion rate (Kendall’s τ?=?0.55), raising concerns about the common use of foraging attempts as a presumed index of foraging success. The total time fish spent handling debris increased linearly with foraging attempt rate and ranged between 4 and 25 % of total foraging time among observed groups. Our results help motivate a revised theoretical view of drift feeding that emphasizes prey detection and discrimination, incorporating ideas from signal detection theory and the study of visual attention in cognitive ecology. We discuss how these ideas could lead to better explanations and predictions of the spatial behavior, prey selection, and energy intake of drift-feeding fish.