Glycans from Fasciola hepatica Modulate the Host Immune Response and TLR-Induced Maturation of Dendritic Cells

Helminths express various carbohydrate-containing glycoconjugates on their surface, and they release glycan-rich excretion/secretion products that can be very important in their life cycles, infection and pathology. Recent evidence suggests that parasite glycoconjugates could play a role in the evasion of the immune response, leading to a modified Th2-polarized immune response that favors parasite survival in the host. Nevertheless, there is limited information about the nature or function of glycans produced by the trematode Fasciola hepatica, the causative agent of fasciolosis. In this paper, we investigate whether glycosylated molecules from F. hepatica participate in the modulation of host immunity. We also focus on dendritic cells, since they are an important target of immune-modulation by helminths, affecting their activity or function. Our results indicate that glycans from F. hepatica promote the production of IL-4 and IL-10, suppressing IFNγ production. During infection, this parasite is able to induce a semi-mature phenotype of DCs expressing low levels of MHCII and secrete IL-10. Furthermore, we show that parasite glycoconjugates mediate the modulation of LPS-induced maturation of DCs since their oxidation restores the capacity of LPS-treated DCs to secrete high levels of the pro-inflammatory cytokines IL-6 and IL-12/23p40 and low levels of the anti-inflammatory cytokine IL-10. Inhibition assays using carbohydrates suggest that the immune-modulation is mediated, at least in part, by the recognition of a mannose specific-CLR that signals by recruiting the phosphatase Php2. The results presented here contribute to the understanding of the role of parasite glycosylated molecules in the modulation of the host immunity and might be useful in the design of vaccines against fasciolosis.     

Twilight activity patterns and angling vulnerability of yellowmouth barracuda (Sphyraena viridensis Cuvier, 1829), a range-expanding thermophilic fish

Among the thermophilic fishes that have become established in the north-western Mediterranean as a consequence of sea warming, the yellowmouth barracuda (Sphyraena viridensis Cuvier, 1829) appears to be one of the most successful and abundant in the coastal rocky environment, having increasingly become the object of recreational and commercial exploitation in the study area. Lure-fishing sessions were carried out from May 2016 to November 2018 in the Catalan Sea (NE Spain) at dawn and dusk, with the aim of providing new insight into the behavioural, spatial and feeding ecology and vulnerability to angling of this poorly known species. Generalized mixed-effects linear models showed that S. viridensis is a crepuscular inshore dweller, whose vulnerability to angling is significantly influenced by solar and lunar light intensities, being highest in the pre-spawn and spawning periods. Asymmetries between dawn and dusk activity patterns were detected, evidently related to a drop in aggressiveness at dusk following the spawning period. The simple study design adopted may be applied to other contexts, aiming to the recognition of several levels of fish vulnerability to angling.     

Influence of the solvent on the conformational-dependent properties of random-coil polypeptides. I. The mean-square of the end-to-end distance and of the dipole moment

Conformational energies for the N-acetyl-N'-methylamides of the 20 natural amino acids were calculated, including the solvent effects, as functions of the angles phi and psi for rotation of the main chain and for six positions chi 1 of the C alpha-C beta bond in the side chain (fixed values for chi 2, chi 3, ...). The computed energies were used to evaluate the mean-square end-to-end distance and mean-square dipole moment of homopolypeptides of the 20 natural amino acids. Ten proteins and three enzymes of current interest were also studied. Slight differences in both properties are found on taking the effects of solvent into consideration. Comparison with other computational and experimental results is made.     

Anatomy of the antennal dorsal organ in female of Neodryinus typhlocybae (Hymenoptera: Dryinidae): A peculiar sensory structure possibly involved in perception of host vibration

Neodryinus typhlocybae (Hymenoptera: Dryinidae) is a natural enemy of the planthopper Metcalfa pruinosa, which was introduced from North America into Europe and has become established in various regions as a pest species. Vibrational signals play a crucial role in the communication of M. pruinosa, which appears to be exploited by N. typhlocybae. Scanning and transmission electron microscopy have shown that the antennae of N. typhlocybae females have peculiar and complex sensory structures: deep longitudinal grooves that house long sensilla trichodea, termed here “Antennal Dorsal Organs.” Such structures were not present on male antennae. These sensilla extend for the length of the grooves, without contact with the groove cuticle. Their hair shaft is empty and aporous, and inserted into a specialized socket, underneath which there is a cuticular ampulla‐like chamber. Each sensillum is associated with two sensory neurons: one terminates at the proximal end of the dendritic sheath; the other continues into the sensillum sinus and is enclosed in the dendritic sheath. This second sensory neuron then enters the ampulla‐like chamber through the circular opening, and then terminates with a conspicuous tubular body at the shaft base. The possible involvement of this peculiar structure in the context of host recognition mechanism is discussed. J. Morphol. 277:128–137, 2016. © 2015 Wiley Periodicals, Inc.     

Ruthenium red inhibits mitochondrial Na+ and K+ uniports induced by magnesium removal.

Removal of bound magnesium from the outer surface of the inner mitochondrial membrane opens up a Na+ and Li+ selective electrophoretic uniport pathway whereas simultaneous depletion of intramitochondrial magnesium induces an electrogenic K+ flux as well. In order to clarify the nature of these cation movements we tested the effect of ruthenium red, a potent and specific inhibitor of the mitochondrial Ca2+ uniporter on different Na+ and K+ uniport-associated phenomena. Ruthenium red efficiently inhibited mitochondrial swelling and depolarization induced by either EDTA in a NaCl-based medium (Na+ uniport) or by EDTA plus A23187 in a KCl-based medium (K+ uniport). For both cation uniports half-maximal inhibition was attained at a ruthenium red concentration as low as 40 nM. Complete inhibition was found above 200 nM. Neither the Na+/H+ nor the K+/H+ exchange was affected by ruthenium red. In light of these observations the possibility is raised that the electrogenic Na+ and K+ fluxes provoked by magnesium reduction or depletion may be mediated through the Ca2+ uniporter. It is suggested that intactness of the mitochondrial magnesium pools is necessary for maintaining the Ca2+ selectivity of the Ca2+ uniporter, and alterations of the membrane-associated magnesium content would make this transport route available also for monovalent cations.