Luis Fernando García

Human spleen contains different subsets of dendritic cells and regulatory T lymphocytes

Most knowledge about dendritic cells (DCs) and regulatory T cells in humans has been gathered from circulating cells but little is known about their frequency and distribution in lymphoid organs. This report shows the frequency, phenotype and location of DCs and regulatory T cells in deceased organ donors spleens. As determined by flow cytometry, conventional/myeloid DCs (cDCs) CD11chighHLA‐DR+CD123−/low were 2·3u2003±u20030·9% and LIN‐ HLA‐DR+CD11chigh 2·1u2003±u20030·3% of total spleen cells. Mature CD11chighHLA‐DR+CD83+ were 1·5u2003±u20030·8% and 1·0u2003±u20031·6% immature CD11chighHLA‐DR+CD83‐ cDC. There were 0·3u2003±u20030·3% plasmacytoid DCs (pDC) CD11c−/lowHLA‐DR+CD123high and 0·3u2003±u20030·1% LIN‐HLA‐DR+CD123high. Cells expressing cDCs markers, BDCA‐1 and BDCA‐3, and pDCs markers BDCA‐2 and BDCA‐4 were observed in higher frequencies than DCs with other phenotypes evaluated. CD11c+, CD123+ and CD83+ cells were located in subcapsular zone, T cells areas and B‐cell follicles. CD4+CD25high Tregs were 0·2u2003±u20030·2% and CD8+CD28‐ comprised 11·5u2003±u20038·1% of spleen lymphocytes. FOXP3+ cells were found in T‐ and B‐cell areas. The improvement in cell separation, manipulation and expansion techniques, will facilitate the manipulation of donor spleen cells as a part of protocols for induction and maintenance of allograft tolerance or treatment of autoimmune diseases.

Construction and Characterization of a Nonproliferative El Tor Cholera Vaccine Candidate Derived from Strain 638

ABSTRACT In recent clinical assays, our cholera vaccine candidate strain,Vibrio cholerae 638 El Tor Ogawa, was well tolerated and immunogenic in Cuban volunteers. In this work we describe the construction of 638T, a thymidine auxotrophic version of improved environmental biosafety. In so doing, the thyAgene from V. cholerae was cloned, sequenced, mutated in vitro, and used to replace the wild-type allele. Except for its dependence on thymidine for growth in minimal medium, 638T is essentially indistinguishable from 638 in the rate of growth and morphology in complete medium. The two strains showed equivalent phenotypes with regard to motility, expression of the celAmarker, colonization capacity in the infant mouse cholera model, and immunogenicity in the adult rabbit cholera model. However, the ability of this new strain to survive environmental starvation was limited with respect to that of 638. Taken together, these results suggest that this live, attenuated, but nonproliferative strain is a new, promising cholera vaccine candidate.

Local trophic specialisation in a cosmopolitan spider (Araneae).

Trophic specialisation can be observed in species with long-term constant exploitation of a certain prey in all populations or in a population of a species with short-term exploitation of a certain prey. While in the former case the species would evolve stereotyped or specialised trophic adaptations, the trophic traits of the latter should be versatile or generalised. Here, we studied the predatory behavioural adaptations of a presumed myrmecophagous spider, Oecobius navus. We chose two distinct populations, one in Portugal and the other in Uruguay. We analysed the actual prey of both populations and found that the Portuguese population feeds mainly on dipterans, while the Uruguayan population feeds mainly on ants. Indeed, dipterans and springtails in Portugal, and ants in Uruguay were the most abundant potential prey. In laboratory trials O. navus spiders recognised and captured a wide variety of prey. The capture efficiency of the Portuguese population measured as components of the handling time was higher for flies than for ants, while that of the Uruguayan population was higher for ants. We found phenotypic plasticity in behavioural traits that lead to increased capture efficiency with respect to the locally abundant prey, but it remains to be determined whether the traits of the two populations are genetically fixed. We conclude that O. navus is a euryphagous generalist predator which shows local specialisation on the locally abundant prey.

Intragraft cytokine expression in heart transplants with mild or no histological rejection

The study of pro‐inflammatory cytokines produced in situ in heart allografts may help to understand the mechanisms of rejection and open new possibilities to control graft rejection. u2028Methods: A total of 23 endomyocardial biopsies obtained from 16 transplanted patients treated with triple‐drug therapy (azathioprine, prednisone, and cyclosporine) were studied. mRNA expression for tumor necrosis factor (TNF)‐α, interleukin (IL)‐1β, IL‐6, IL‐10, IL‐12, IL‐15, transforming growth factor (TGF)‐β, and β‐actin was determined by reverse transcription polymerase chain reaction (RT‐PCR) and Southern blotting. Semiquantitative analysis was done by establishing the ratio between densitometric integrated value of each cytokine with the β‐actin and correlated with the histopathologic findings. u2028Results: Three groups of biopsies were determined according to the International Society for Heart and Lung Transplantation criteria: grade 0 (control group, n=12), grade 1A (sub‐clinical rejection, n=6) and ‘quilty effect’ (n=5). An increased expression of mRNA for TNF‐α and IL‐6 (p=0.0091 and 0.0075, respectively) was found associated with rejection grade 1A episodes, mRNA for IL‐1β was nonspecifically expressed in all the study groups, while IL‐10 mRNA was not detected in any of the biopsies studied. mRNA for IL‐12 and IL‐15 was not associated with rejection. Interestingly, TGF‐β was not detected in any of the biopsies with the ‘quilty pattern’. u2028Conclusion: The association of TNF‐α and IL‐6 mRNA in situ expression with mild histologically probed rejection episodes may be used in the monitoring of heart transplants.

Dynamics of the T cell response to Mycobacterium tuberculosis DosR and Rpf antigens in a Colombian population of household contacts of recently diagnosed pulmonary tuberculosis patients.

Immune response to DosR and Rpf antigens from Mycobacterium tuberculosis (Mtb) seems to be important for latency maintenance. Little is known about the dynamics of the immune response to these antigens in an endemic community. Thus, the IFNγ response and cytokine production in response to PPD, Esat6-Cfp10 (E6-C10), DosR and Rpf antigens in healthy HHC of tuberculosis (TB) patients over a 12 (T12) months period (short-term, stLTBI) was investigated. This response was compared with a group of LTBI, who have remained healthy for 5-7 years (long-term, ltLTBI). According to the IFNγ response, two groups of HHCs were identified in stLTBI in response to E6-C10. At T12, E6-C10(+) HHCs displayed a decrease in the IFNγ levels and a generalized decrease in cytokines production. The E6-C10(-) HHC showed an increase in the IFNγ response and cytokine levels. In stLTBI, the responses to E6-C10, DosR, and Rpf may be interpreted as a protective immune response controlling Mtb infection and may be leading to a state of latent infection. Comparing the response of stLTBI and ltLTBI, we observed significant changes in the proportions of CD45RO(+)CD27(+) T cells to specific DosR and Rpf, which may indicate a persistent immune response to Mtb antigens in ltLTBI.

A new species of Piaroa (Schizomida: Hubbardiidae) from Venezuela, with taxonomic notes on the genus

A new species belonging to the schizomid genus Piaroa Villarreal, Giupponi and Tourinho, 2008 is described from north-western Venezuela. A complementary description of Piaroa guipongai Villarreal and Garcia, 2012 is provided including SEM pictures of relevant structures of both sexes. A key for males of Piaroa and Colombiazomus Armas and Delgado-Santa, 2012 is included. The presence of Dm3 setae on Hubbardiidae is discussed.

Trophic Niches and Trophic Adaptations of Prey-Specialized Spiders from the Neotropics: A Guide

Spiders are the most diversified group of terrestrial predators. They employ a wide variety of feeding strategies, and exploit several prey types, from invertebrates up to small vertebrates. Many studies on the trophic ecology of spiders have focused on generalist and euryphagous species. Thus, our knowledge of prey specialist (and stenophagous) species is very limited despite the high number of endemic species occurring in the Neotropics, many of which are most probably specialized. In this chapter, we provide a guide on how to study the trophic niches of spiders in order to encourage other researchers to investigate prey-specialized species. At the beginning, we define the term trophic niche and identify its dimensions (prey type, size, and availability). We critically outline methodological approaches on how to study it. A narrow trophic niche is paralleled by the evolution of specific cognitive, behavioural, metabolic, morphological, and venomic adaptations used in prey capture. We provide an overview of these adaptations and focus on approaches to reveal them. On the basis of an extensive bibliographic review, we summarize the current state-of-the-art with respect to knowledge on the trophic ecology of Neotropical spiders, with particular emphasis on specialists. Finally, we provide recommendations for future research.

Diet composition and prey selectivity by the spider Oecobius concinnus (Araneae: Oecobiidae) from Colombia

Abstract The feeding ecology of most Oecobius species is poorly understood; nevertheless, the limited literature available suggests that obligate myrmecophagy is common in this genus. Recent evidence suggests that some species might do not share this trait, but could be locally specialized predators. We describe the diet and prey selectivity of the spider Oecobius concinnus (Simon 1893), a common pantropical species. Samplings of actual and potential prey for this species were made in the city of Ibagué, Colombia. Ants were the dominant prey. Other prey included in its diet were dipterans. These results suggest that O. concinnus is not an obligate myrmecophagous spider. Nevertheless, further studies will evaluate other aspects of the biology of this species to reveal its trophic strategy.

Comparison of the capture efficiency, prey processing, and nutrient extraction in a generalist and a specialist spider predator

Predators are traditionally classified as generalists and specialists based on the presence of adaptations that increase efficiency of prey capture and consumption and selection of particular prey types. Nevertheless, empirical evidence comparing foraging efficiency between generalist and specialist carnivores is scarce. We compared the prey-capture and feeding efficiency in a generalist and a specialist (araneophagous) spider predator. By using two related species, the generalist Harpactea rubicunda (Dysderidae) and the specialist Nops cf. variabilis (Caponiidae), we evaluated their fundamental trophic niche by studying the acceptance of different prey. Then, we compared their predatory behavior, efficiency in capturing prey of varying sizes, feeding efficiency, and nutrient extraction. Nops accepted only spiders as prey, while Harpactea accepted all offered prey, confirming that Nops is stenophagous, while Harpactea is euryphagous. Further, Nops displayed more specialized (stereotyped) capture behavior than Harpactea, suggesting that Nops is a specialist, while Harpactea is a generalist. The specialist immobilized prey faster, overcame much larger prey, and gained more mass (due to feeding on larger prey) than the generalist. Both the specialist and the generalist spider extracted more proteins than lipids, but the extraction of macronutrients in the specialist was achieved mainly by consuming the prosoma of the focal prey. We show that the specialist has more efficient foraging strategy than the generalist.

A NEW RECORD OF A SOCIAL SPIDER, ANELOSIMUS LORENZO FOWLER AND LEVI, 1979 (ARANEAE, THERIDIIDAE), FROM A TEMPERATE ZONE (URUGUAY)

Se registra Anelosimus lorenzo para Uruguay, constituyendo el hallazgo mas austral de la especie. El presente registro confirma la inusual presencia de una arana social para una zona de clima templado. Con este nuevo reporte, el numero de especies de Anelosimus conocidas para este pais se eleva a tres.