Evolution of <Emphasis Type="Italic">Pleopsidium</Emphasis> (Lichenized Ascomycota) S943 Group I Introns and the Phylogeography of an Intron-Encoded Putative Homing Endonuclease

The sporadic distribution of nuclear group I introns among different fungal lineages can be explained by vertical inheritance of the introns followed by successive losses, or horizontal transfers from one lineage to another through intron homing or reverse splicing. Homing is mediated by an intron-encoded homing endonuclease (HE) and recent studies suggest that the introns and their associated HE gene (HEG) follow a recurrent cyclical model of invasion, degeneration, loss, and reinvasion. The purpose of this study was to compare this model to the evolution of HEGs found in the group I intron at position S943 of the nuclear ribosomal DNA of the lichen-forming fungus Pleopsidium. Forty-eight S943 introns were found in the 64 Pleopsidium samples from a worldwide screen, 22 of which contained a full-length HEG that encodes a putative 256-amino acid HE, and 2 contained HE pseudogenes. The HEGs are divided into two closely related types (as are the introns that encode them) that differ by 22.6% in their nucleotide sequences. The evolution of the Pleopsidium intron-HEG element shows strong evidence for a cyclical model of evolution. The intron was likely acquired twice in the genus and then transmitted via two or three interspecific horizontal transfers. Close geographical proximity plays an important role in intron-HEG horizontal transfer because most of these mobile elements were found in Europe. Once acquired in a lineage, the intron-HEG element was also vertically transmitted, and occasionally degenerated or was lost. [Reviewing Editor: Dr. Manyuan Long]     

Migration and spawning of female surubim (<Emphasis Type="Italic">Pseudoplatystoma corruscans</Emphasis>, Pimelodidae) in the São Francisco river,Brazil

Surubim, Pseudoplatystoma corruscans, is the most valuable commercial and recreational fish in the São Francisco River, but little is known about adult migration and spawning. Movements of 24 females (9.5–29.0 kg), which were radio-tagged just downstream of Três Marias Dam (TMD) at river kilometer 2,109 and at Pirapora Rapids (PR) 129 km downstream of TMD, suggest the following conceptual model of adult female migration and spawning. The tagged surubims used only 274 km of the main stem downstream of TMD and two tributaries, the Velhas and Abaeté rivers. Migration style was dualistic with non-migratory (resident) and migratory fish. Pre-spawning females swam at ground speeds of up to 31 km day^-1 in late September–December to pre-spawning staging sites located 0–11 km from the spawning ground. In the spawning season (November–March), pre-spawning females migrated back and forth from nearby pre-spawning staging sites to PR for short visits to spawn, mostly during floods. Multiple visits to the spawning site suggest surubim is a multiple spawner. Most post-spawning surubims left the spawning ground to forage elsewhere, but some stayed at the spawning site until the next spawning season. Post-spawning migrants swam up or downstream at ground speeds up to 29 km day^-1 during January–March. Construction of proposed dams in the main stem and tributaries downstream of TMD will greatly reduce surubim abundance by blocking migrations and changing the river into reservoirs that eliminate riverine spawning and non-spawning habitats, and possibly, cause extirpation of populations.     

Vitamin A and immune regulation: role of retinoic acid in gut-associated dendritic cell education, immune protection and tolerance

The vitamin A (VA) metabolite all-trans retinoic acid (RA) plays a key role in mucosal immune responses. RA is produced by gut-associated dendritic cells (DC) and is required for generating gut-tropic lymphocytes and IgA-antibody-secreting cells (IgA-ASC). Moreover, RA modulates Foxp3⁺ regulatory T cell (T_REG) and Th17 effector T cell differentiation. Thus, although RA could be used as an effective “mucosal adjuvant” in vaccines, it also appears to be required for establishing intestinal immune tolerance. Here we discuss the roles proposed for RA in shaping intestinal immune responses and tolerance at the gut mucosal interface. We also focus on recent data exploring the mechanisms by which gut-associated DC acquire RA-producing capacity.     

Role of olfaction and vision in homing behaviour of black rockfish Sebastes inermis

How fish find their original habitat and natal home remains an unsolved riddle of animal behaviour. Despite extensive efforts to study the homing behaviour of diadromous fish, relatively little attention has been paid to that of non-diadromous marine fish. Among these, most rockfish of the genus Sebastes exhibit homing ability and/or a strong fidelity to their habitats. However, how these rockfish detect the homeward direction has not been clarified. The goal of the present research was to investigate the sensory mechanisms involved in the homing behaviour of the black rockfish Sebastes inermis, using acoustic telemetry. Vision-blocked or olfactory-ablated rockfish were released in natural waters and their homing behaviours compared with those of intact or control individuals. Blind rockfish showed homing from both inside and outside their habitat. The time taken by blind fish to reach their home habitat was not significantly different from that of the control fish. In contrast, most olfactory-ablated fish did not successfully reach their original habitat. Our results indicate that black rockfish predominantly use the olfactory sense in their homing behaviour.     

Derivation and analysis of a system modeling the chemotactic movement of hematopoietic stem cells

It has been shown that hematopoietic stem cells migrate in vitro and in vivo following the gradient of a chemotactic factor produced by stroma cells. In this paper, a quantitative model for this process is presented. The model consists of chemotaxis equations coupled with an ordinary differential equation on the boundary of the domain and subjected to nonlinear boundary conditions. The existence and uniqueness of a local solution is proved and the model is simulated numerically. It turns out that for adequate parameter ranges, the qualitative behavior of the stem cells observed in the experiment is in good agreement with the numerical results. Our investigations represent a first step in the process of elucidating the mechanism underlying the homing of hematopoietic stem cells quantitatively.      

Introduction of functional chimeric E/L-selectin by RNA electroporation to target dendritic cells from blood to lymph nodes

Background

Inefficient migration of dendritic cells (DC) to regional lymph nodes (LN) upon intracutaneous injection is a major obstacle for effective DC vaccination. Intravenous vaccination is unfavorable, because DC cannot migrate directly from the blood into LN.

Methods

To enable human monocyte-derived (mo)DC to enter LN directly from the blood, we manipulated them by RNA electroporation to express a human chimeric E/L-selectin (CD62E/CD62L) protein, which binds to peripheral node addressin expressed on high endothelial venules.

Results

Transfection efficiency exceeded 95%, and high E/L-selectin surface expression was detected for >48 h. E/L-selectin RNA-transfected DC displayed an identical mature DC phenotype as mock-transfected DC. Furthermore, E/L-selectin-transfected DC maintained their normal CCR7-mediated migration capacity, and their ability to prime and expand functional cytotoxic T cells recognizing MelanA. Most importantly, E/L-selectin-RNA-transfected DC gained the capability to attach to and roll on sialyl-Lewis^X in vitro.

Outlook

The presented strategy can be readily translated into the clinic, as it involves no stable genetic manipulation or viral transformation, and allows targeting of a large number of LN.     

Modified mesenchymal stem cells in cancer therapy: A smart weapon requiring upgrades for wider clinical applications

Mesenchymal stem stromal cells(MSC)are characterized by the intriguing capacity to home toward cancer cells after systemic administration.Thus,MSC can be harnessed as targeted delivery vehicles of cytotoxic agents against tumors.In cancer patients,MSC based advanced cellular therapies were shown to be safe but their clinical efficacy was limited.Indeed,the amount of systemically infused MSC actually homing to human cancer masses is insufficient to reduce tumor growth.Moreover,induction of an unequivocal anticancer cytotoxic phenotype in expanded MSC is necessary to achieve significant therapeutic efficacy.Ex vivo cell modifications are,thus,required to improve anti-cancer properties of MSC.MSC based cellular therapy products must be handled in compliance with good manufacturing practice(GMP)guidelines.In the present review we include MSCimproving manipulation approaches that,even though actually tested at preclinical level,could be compatible with GMP guidelines.In particular,we describe possible approaches to improve MSC homing on cancer,including genetic engineering,membrane modification and cytokine priming.Similarly,we discuss appropriate modalities aimed at inducing a marked cytotoxic phenotype in expanded MSC by direct chemotherapeutic drug loading or by genetic methods.In conclusion,we suggest that,to configure MSC as a powerful weapon against cancer,combinations of clinical grade compatible modification protocols that are currently selected,should be introduced in the final product.Highly standardized cancer clinical trials are required to test the efficacy of ameliorated MSC based cell therapies.     

Orientation flights of solitary wasps (Cerceris; Sphecidae; Hymenoptera)

Bees and wasps are known to use a visual representation of the nest environment to guide the final approach to their nest. It is also known that they acquire this representation during an orientation flight performed on departure.A detailed film analysis shows that orientation flights in solitary wasps of the genus Cerceris consist of a systematic behavioural sequence: after lift-off from the nest entrance, wasps fly in ever increasing arcs around the nest. They fly along these arcs obliquely to their long axis and turn so that the nest entrance is held in the left or right visual field at retinal positions between 30° and 70° from the midline. Horizontal distance from the nest and height above ground increase throughout an orientation flight so that the nest is kept at retinal elevations between 45° and 60° below the horizon. The wasps' rate of turning is constant at between 100°/s and 200°/s independent of their distance from the nest and their ground velocity increases with distance. The consequence of this is that throughout the flight wasps circle at a constant angular velocity around the nest.Orientation flights are strongly influenced by landmark lay-out. Wasps adjust their flight-path and their orientation in a way that allows them to fixate the nest entrance and to hold the closest landmark in their frontal visual field.The orientation flight generates a specific topography of motion parallax across the visual field. This could be used by wasps to acquire a series of snapshots that all contain the nest position, to acquire snapshots of close landmarks only (distance filtering), to exclude shadow contours from their visual representation (figure-ground discrimination) or to gain information on the distance of landmarks relative to the nest.     

Exogenous dendritic cell homing to draining lymph nodes can be boosted by mast cell degranulation

Dendritic cells (DCs), as potent antigen presenting cells, are increasingly used for immunotherapeutic approaches, predominantly in oncology. Low efficiency of injected Ag-pulsed DC homing to draining lymph nodes (DLNs) is one of the factors that affect the efficacy of therapy. As Langerhans cell emigration was enhanced after skin mast cell degranulation, we investigated the effect of local mast cell activation on exogenous bone marrow-derived DCs (BM-DCs) homing to DLNs. Product of activated MC/9 mast cells enhanced chemotaxis of BM-DCs to CCL21 in vitro. Intradermal injection of compound 48/80 (c48/80) induced local skin mast cell obvious degranulation and boosted exogenous BM-DC homing to DLNs. Both Ag-specific lymphocyte proliferation and TH1/TH2 cytokine production increased after HBsAg-pulsed BM-DC was injected into c48/80 pretreated mice. These results suggest that transferred DC homing to DLNs promoted by local mast cell degranulation may have potential application to improve DC-based immunotherapy.