Affiliation in Four Echimyid Rodent Species based on Intrasexual Dyadic Encounters: Evolutionary Implications

In this work we explored the evolution of sociality in cursorial echimyids by comparing affiliation among three species of Trinomys and one species of Thrichomys. We captured specimens of Trinomys yonenagae, Trinomys albispinus minor, and Thrichomys apereoides in areas of the Brazilian semiarid Caatinga, and Trinomys iheringi denigratus in one area of Atlantic Forest. For each species, we recorded 12 intra‐sexual dyadic encounters in a neutral arena (six between males and six between females) in order to test the hypothesis that species and sex influence level of affiliation. This response variable was assessed based on an affiliation index, calculated as the proportion of the total number of affiliative behaviors to the total number of social behaviors exhibited by the dyad during each encounter. Hypothesis test was performed by means of a parametric two‐way anova . The test was able to detect significant differences only among species, not among sexes. Trinomys yonenagae was the most affiliative species, while T. apereoides and T. albispinus minor were the most agonistic ones. Trinomys iheringi denigratus showed an intermediate pattern. We suggest, based on out‐group comparison, that affiliation in Trinomys increased in the lineage containing T. iheringi denigratus and T. yonenagae and that higher affiliation in the last species can be adaptive to the life in the desert‐like habitat where it lives.     

Genomic instability and aging-like phenotype in the absence of mammalian SIRT6

The Sir2 histone deacetylase functions as a chromatin silencer to regulate recombination, genomic stability, and aging in budding yeast. Seven mammalian Sir2 homologs have been identified (SIRT1-SIRT7), and it has been speculated that some may have similar functions to Sir2. Here, we demonstrate that SIRT6 is a nuclear, chromatin-associated protein that promotes resistance to DNA damage and suppresses genomic instability in mouse cells, in association with a role in base excision repair (BER). SIRT6-deficient mice are small and at 2-3 weeks of age develop abnormalities that include profound lymphopenia, loss of subcutaneous fat, lordokyphosis, and severe metabolic defects, eventually dying at about 4 weeks. We conclude that one function of SIRT6 is to promote normal DNA repair, and that SIRT6 loss leads to abnormalities in mice that overlap with aging-associated degenerative processes.     

Plasmodium berghei: effect of protease inhibitors during gametogenesis and early zygote development

Plasmodium berghei: The effect of five protease inhibitors, TPCK, TLCK, PMSF, leupeptin, and 1,10-phenanthroline on in vitro gametogenesis and early zygote development of P. berghei was investigated. PMSF and leupeptin showed no effect. Cysteine/serine protease inhibitors TPCK/TLCK at concentrations of 75 and 100 microM were effective on inhibiting exflagellation center formation, and this effect was reversible with the addition of l-cysteine. Exflagellation center formation was most effectively blocked by 1,10-phenanthroline (1mM), and exflagellation center numbers were restored by the addition of Zn(2+). A reduction of ookinete production was observed when TPCK/TLCK (100 microM) was added at 2h after gametogenesis, but no effect was observed with 1,10-phenanthroline (1mM). Our results suggest that proteolysis is important in both gametocyte activation and sexual development of P. berghei.     

Characterization of excretory/secretory endopeptidase and metallo-aminopeptidases from Taenia crassiceps metacestodes

Cysticercosis is caused by Taenia spp. metacestodes, which must survive in the host tissues to complete their life cycle. Their survival depends on their control of host immune responses. Because many parasites use proteases to modulate host responses, we examined culture media from Taenia crassiceps metacestodes for protease activity using peptide substrates. We identified prominent aminopeptidase activity at neutral pH, which was inhibited by chelating agents and partially inhibited by the aminopeptidase inhibitor, bestatin. Endopeptidase substrates were optimally cleaved at slightly acidic pH and endopeptidase activity was inhibited by cysteine protease inhibitors. Gel filtration FPLC and subsequent visualization by silver staining revealed a metallo-aminopeptidase of molecular weight 21 kDa and cysteine proteases of Mr 70 and 64 kDA. Recombinant IL-2 was digested when incubated with parasite culture supernatants, but not with control media. IL-2 degradation was completely inhibited by 1,10 phenanthroline and partially inhibited by bestatin, suggesting that a metallo-aminopeptidase was responsible. Incubation of human IgG with culture supernatants resulted in complete degradation of IgG, which was blocked by cysteine protease inhibitors. These observations demonstrate that Taenia spp. metacestodes secrete a number of proteolytic enzymes, which may target molecules from the host immune system and assist in evasion of the host immune response.     

Light activation of the isomerization and deprotonation of the protonated Schiff base retinal

We perform an ab initio analysis of the photoisomerization of the protonated Schiff base of retinal (PSB-retinal) from 11-cis to 11-trans rotating the C10-C11=C12-C13 dihedral angle from 0° (cis) to -180° (trans). We find that the retinal molecule shows the lowest rotational barrier (0.22 eV) when its charge state is zero as compared to the barrier for the protonated molecule which is ∼0.89 eV. We conclude that rotation most likely takes place in the excited state of the deprotonated retinal. The addition of a proton creates a much larger barrier implying a switching behavior of retinal that might be useful for several applications in molecular electronics. All conformations of the retinal compound absorb in the green region with small shifts following the dihedral angle rotation; however, the Schiff base of retinal (SB-retinal) at trans-conformation absorbs in the violet region. The rotation of the dihedral angle around the C11=C12 π-bond affects the absorption energy of the retinal and the binding energy of the SB-retinal with the proton at the N-Schiff; the binding energy is slightly lower at the trans-SB-retinal than at other conformations of the retinal.     

SPARC downregulation attenuates the profibrogenic response of hepatic stellate cells induced by TGF-β1 and PDGF

Liver fibrosis is an active process that involves changes in cell-cell and cell-extracellular matrix (ECM) interaction. Secreted protein, acidic and rich in cysteine (SPARC) is an ECM protein with many biological functions that is overexpressed in cirrhotic livers and upregulated in activated hepatic stellate cells (aHSCs). We have recently shown that SPARC downregulation ameliorates liver fibrosis in vivo. To uncover the cellular mechanisms involved, we have specifically knocked down SPARC in two aHSC lines [the CFSC-2G (rat) and the LX-2 (human)] and in primary cultured rat aHSCs. Transient downregulation of SPARC in hepatic stellate cells (HSCs) did not affect their proliferation and had only minor effects on apoptosis. However, SPARC knockdown increased HSC adhesion to fibronectin and significantly decreased their migration toward PDFG-BB and TGF-β(1). Interestingly, TGF-β(1) secretion by HSCs was reduced following SPARC small interfering RNA (siRNA) treatment, and preincubation with TGF-β(1) restored the migratory capacity of SPARC siRNA-treated cells through mechanisms partially independent from TGF-β(1)-mediated induction of SPARC expression; thus SPARC knockdown seems to exert its effects on HSCs partially through modulation of TGF-β(1) expression levels. Importantly, collagen-I mRNA expression was reduced in SPARC siRNA-transfected HSCs. Consistent with previous results, SPARC knockdown in aHSCs was associated with altered F-actin expression patterns and deregulation of key ECM and cell adhesion molecules, i.e., downregulation of N-cadherin and upregulation of E-cadherin. Our data together suggest that the upregulation of SPARC previously reported for aHSCs partially mediates profibrogenic activities of TGF-β(1) and PDGF-BB and identify SPARC as a potential therapeutic target for liver fibrosis.     

A biomechanical analysis on the impact of episiotomy during childbirth

Episiotomy is still a controversy issue among physicians, despite the enormous growth of clinical research. Therefore, the potential of numerical modeling of anatomical structures to simulate biomechanical processes was exploited to realize quantitatively the real effects of the episiotomy and its consequences on the pelvic floor muscle. As such, a numerical model was used composed of pelvic floor muscles, a surface delimiting the anterior region, and a fetus body. A normal vaginal delivery without and with different episiotomies was simulated with the fetus in vertex presentation and occipitoanterior position. According to our numerical results, a mediolateral episiotomy has a protective effect, reducing the stress on the muscles, and the force required to delivery successfully up to 52.2 %. The intervention also has benefits on muscle injury, reducing the damage to a small zone. This study demonstrates the feasibility of using a computational modeling approach to study parturition, namely the capability to isolate and evaluate the mechanical significance of a single feature. It must, however, be taken into account that the numerical model does not assess problems that may occur as blood loss, infections and others, so it is necessary to examine whether the benefits of an intervention outweigh the risks.     

Salt lakes of La Mancha (Central Spain): A hot spot for tiger beetle (Carabidae,Cicindelinae) species diversity

The tiger beetle assemblage of the wetlands of La Mancha (central Spain) comprises nine species: Calomera littoralis littoralis, Cephalota maura maura, Cephalota circumdata imperialis, Cephalota dulcinea, Cicindela campestris campestris, Cicindela maroccana, Cylindera paludosa, Lophyra flexuosa flexuosa, and Myriochila melancholica melancholica. This assemblage represents the largest concentration of tiger beetles in a single 1º latitude / longitude square in Europe. General patterns of spatial and temporal segregation among species are discussed based on observations of 1462 specimens registered during an observation period of one year, from April to August. The different species of Cicindelini appear to be distributed over space and time, with little overlapping among them. Three sets of species replace each other phenologically as the season goes on. Most of the species occupy drying or dried salt lakes and salt marshes, with sparse vegetation cover. Spatial segregation is marked in terms of substrate and vegetation use. Calomera littoralis and Myriochila melancholica have been observed mainly on wet soils; Cephalota circumdata on dry open saline flats; Cephalota dulcinea and Cylindera paludosa in granulated substrates with typical halophytic vegetation; Cephalota maura is often present in man-modified areas. Cephalota circumdata and Cephalota dulcinea are included as species of special interest in the list of protected species in Castilla–La Mancha. Conservation problems for the Cicindelini assemblage arise from agricultural activities and inadequate use of sport vehicles. Attempts at restoring the original habitat, supressing old semi-industrial structures, may affect the spatial heterogeneity of the lakes, and have an effect on Cicindelinae diversity.