The role of HLA-G in immunity and hematopoiesis

The non-classical HLA class I molecule HLA-G was initially shown to play a major role in feto–maternal tolerance. Since this discovery, it has been established that HLA-G is a tolerogenic molecule which participates to the control of the immune response. In this review, we summarize the recent advances on (1) the multiple structures of HLA-G, which are closely associated with their role in the inhibition of NK cell cytotoxicity, (2) the factors that regulate the expression of HLA-G and its receptors, (3) the mechanism of action of HLA-G at the immunological synapse and through trogocytosis, and (4) the generation of suppressive cells through HLA-G. Moreover, we also review recent findings on the non-immunological functions of HLA-G in erythropoiesis and angiogenesis.     

Using short-term surveys and mark–recapture to estimate diversity and population size of orchid bees in forest formations of the Brazilian savanna

Studies on the diversity and population dynamics of euglossine bees in forest formations of the Brazilian savanna can be notably informative considering that most species are forest-dependent. The current study aimed to estimate the diversity and population size of euglossine bees using short-term surveys and the mark–recapture method. We also compared short-term surveys with monthly surveys over a 1-year period (long-term surveys) to assess the species diversity. The study occurred in seven forest formations of the Brazilian savanna. We collected 14 species and marked 375 males but recaptured only 23 (6.1%). The population size of Euglossa bees ranged from 111.1 ± 34.4 to 1384.5 ± 384.6 males. The diversity indices achieved through the short-term surveys were similar to or higher than those obtained from long-term studies. The low recapture rate of euglossine males seems to be the result of their long-distance dispersal capacity. We also proposed that short-term surveys be viewed as a favourable alternative to long-term studies on diversity estimation and that euglossine bees can occur in small populations in some forest formations studied.     

Feulgen-DNA amounts and karyotype lengths of three planarian species of the genusDugesia

Summary Genome sizes of the planariansD. lugubris (2n=8),D. polychroa (2n=8) andD. benazzii (2n=16) were evaluated on metaphase plates by measuring both the Feulgen-DNA contents and the karyotype lengths. In the three species, genome sizes are significantly different; this finding rules out the possibility of a karyotype evolution through simple chromosome rearrangements betweenD. lugubris andD. polychroa. A different Feulgen-DNA content per unit length of karyotype in the three species studied was also found, which suggests that DNA could be differently packed along metaphase chromosomes.     

Bone marrow-derived mesenchymal cells and MMP13 contribute to experimental choroidal neovascularization

In this study, we evaluate the potential involvement of collagenase-3 (MMP13), a matrix metalloproteinase (MMP) family member, in the exudative form of age-related macular degeneration characterized by a neovascularisation into the choroid. RT-PCR analysis revealed that human neovascular membranes issued from patients with AMD expressed high levels of Mmp13. The contribution of MMP13 in choroidal neovascularization (CNV) formation was explored by using a murine model of laser-induced CNV and applying it to wild-type mice (WT) and Mmp13-deficient mice (Mmp13 ^?/? mice). Angiogenic and inflammatory reactions were explored by immunohistochemistry. The implication of bone marrow (BM)-derived cells was determined by BM engraftment into irradiated mice and by injecting mesenchymal stem cells (MSC) isolated from WT BM. The deficiency of Mmp13 impaired CNV formation which was fully restored by WT BM engraftment and partially rescued by several injections of WT MSC. The present study sheds light on a novel function of MMP13 during BM-dependent choroidal vascularization and provides evidence for a role for MSC in the pathogenesis of CNV.     

Tegmina-size variation in a Neotropical cricket with implications on spectral song properties

This study evaluates the relationship between shape and size of tegmen, harp, mirror, and spectral range of calling song frequency of a Neotropical cricket subpopulation (Lerneca inalata beripocone. In addition, we compare intraspecific morphological divergence and calling song properties between individuals from different sites of the Pantanal of Poconé, Mato Grosso, Brazil. Regression analysis showed that the dominant and maximum calling song frequencies were negatively correlated with tegmen size, i.e. frequencies are either lower or higher depending on the corresponding size variation in resonance structures of the forewings. Canonical variable analysis demonstrated marked intraspecific differences in morphometric characters between localities of a L. inalata subpopulation c. 35 km apart (SESC-Pantanal Advanced Research Base and Pouso Alegre Farm, Mato Grosso, Brazil). Lerneca inalata beripocone at SESC had larger forewings than conspecifics from Pouso Alegre Farm. These morphological variations of wing properties related to reproductive behaviours were interpreted as fitness parameters, likely shaped by restricted gene flow during temporal habitat isolation episodes. Such isolation patterns occur in the Pantanal wetlands for several months during the annual hydrological cycle.     

Superactive mutants of thromboxane prostanoid receptor: functional and computational analysis of an active form alternative to constitutively active mutants

In class A GPCRs the E/DRY motif is critical for receptor activation and function. According to experimental and computational data, R3.50 forms a double salt bridge with the adjacent E/D3.49 and E/D6.30 in helix 6, constraining the receptor in an inactive state. The disruption of this network of interactions facilitates conformational transitions that generate a signal or constitutive activity. Here we demonstrate that non-conservative substitution of either E129^(3.49) or E240^(6.30) of thromboxane prostanoid receptor (TP) resulted in mutants characterized by agonist-induced more efficient signaling properties, regardless of the G protein coupling. Results of computational modeling suggested a more effective interaction between G_q and the agonist-bound forms of the TP mutants, compared to the wild type. Yet, none of the mutants examined revealed any increase in basal activity, precluding their classification as constitutively active mutants. Here, we propose that these alternative active conformations might be identified as superactive mutants or SAM.     

Translating tissue-engineered tracheal replacement from bench to bedside

There are a variety of airway diseases with different clinical settings, which may extend from a surgical approach to total organ replacement. Tissue engineering involves modifying cells or tissues in order to repair, regenerate, or replace tissue in the body and seems to be a promising approach for airway replacement. The successful implantation of stem-cell-based tissue-engineered trachea in a young woman with end-stage post-tuberculosis left main bronchus collapse serves as a prototype for the airway tissue-engineered-based approach. The trachea indeed could represent a perfect model system to investigate the translational aspects of tissue engineering, largely due to its low-oxygen needs. This review highlights the anatomy of the airways, the various disease conditions that cause damage to the airways, elaborates on the essential components of the tissue-engineering approach, and discusses the success of the revolutionary trachea transplantation approach.