Gardnerella vaginalis Vaginolysin (VLY)-Derived MAP8 Peptide (VLY-MAP8) Induced the Production of Egg Yolk IgY Antibodies that Inhibit Erythrocytes Lysis

International Journal of Peptide Research and Therapeutics - Gardnerella vaginalis produces vaginolysin (VLY), a cholesterol-dependent cytolysin, responsible of the cellular lysis and epithelial...     

The Role of Historical Barriers in the Diversification Processes in Open Vegetation Formations during the Miocene/Pliocene Using an Ancient Rodent Lineage as a Model

The Neotropics harbors a high diversity of species and several hypotheses have been proposed to account for this pattern. However, while species of forested domains are frequently studied, less is known of species from open vegetation formations occupying, altogether, a larger area than the Amazon Forest. Here we evaluate the role of historical barriers and the riverine hypothesis in the speciation patterns of small mammals by analyzing an ancient rodent lineage (Thrichomys, Hystricomorpha). Phylogenetic and biogeographic analyses were carried out with mitochondrial and nuclear DNA markers to analyze the evolutionary relationships between Thrichomys lineages occurring in dry domains along both banks of the Rio São Francisco. This river is one of the longest of South America whose course and water flow have been modified by inland tectonic activities and climate changes. Molecular data showed a higher number of lineages than previously described. The T. inermis species complex with 2n = 26, FN = 48 was observed in both banks of the river showing a paraphyletic arrangement, suggesting that river crossing had occurred, from east to west. A similar pattern was also observed for the T. apereoides complex. Thrichomys speciation occurred in Late Miocene when the river followed a different course. The current geographic distribution of Thrichomys species and their phylogenetic relationships suggested the existence of frequent past connections between both banks in the middle section of the Rio São Francisco. The extensive palaeodune region found in this area has been identified as a centre of endemism of several vertebrate species and is likely to be a center of Thrichomys diversification.     

Biomechanical analysis of the anterior cervical fusion

This paper presents a biomechanical analysis of the cervical C5-C6 functional spine unit before and after the anterior cervical discectomy and fusion. The aim of this work is to study the influence of the medical procedure and its instrumentation on range of motion and stress distribution. First, a three-dimensional finite element model of the lower cervical spine is obtained from computed tomography images using a pipeline of image processing, geometric modelling and mesh generation software. Then, a finite element study of parameters' influence on motion and a stress analysis at physiological and different post-operative scenarios were made for the basic movements of the cervical spine. It was confirmed that the results were very sensitive to intervertebral disc properties. The insertion of an anterior cervical plate influenced the stress distribution at the vertebral level as well as in the bone graft. Additionally, stress values in the graft decreased when it is used together with a cage.     

Ecomorphological analysis as a complementary tool to detect changes in fish communities following major perturbations in two South African estuarine systems

Ecomorphological changes as a result of natural perturbations in estuarine fish communities were investigated in two South African estuaries (Swartvlei and East Kleinemonde), both before and after the loss of aquatic macrophyte beds in these systems. The fish communities were analysed using an ecomorphological diversity index (EMI) and the results compared to a traditional index, the Shannon-Wiener diversity index. The EMI revealed that the major changes in fish community composition recorded in both estuaries were associated with quantitative variations at the species level. Both estuaries essentially lost their macrophyte beds and ended up with the same type of bottom habitat (bare sediment). In both cases the fish morphological variability decreased immediately after aquatic macrophyte loss and then increased to end above the initial value. The ecomorphological analysis appeared to be sensitive to major ecological disturbances that occurred during the study period and this was confirmed by the morphospace configuration. The results indicate that the ecomorphology of the fish community responds to habitat changes and that this change corresponds to alterations in the representation of the different feeding types. These findings therefore contribute to the measurement of morphological changes in estuarine fish assemblages as a result of habitat changes within the ecosystem and we propose that ecomorphological analyses add another dimension to the information provided by existing diversity indices in studying changing fish communities.     

Habitat association and seasonality in a mosaic and bimodal hybrid zone between Chorthippus brunneus and C. jacobsi (Orthoptera: Acrididae)

Understanding why some hybrid zones are bimodal and others unimodal can aid in identifying barriers to gene exchange following secondary contact. The hybrid zone between the grasshoppers Chorthippus brunneus and C. jacobsi contains a mix of allopatric parental populations and inter-mingled bimodal and unimodal sympatric populations, and provides an ideal system to examine the roles of local selection and gene flow between populations in maintaining bimodality. However, it is first necessary to confirm, over a larger spatial scale, previously identified associations between population composition and season and habitat. Here we use cline-fitting of one morphological and one song trait along two valley transects, and intervening mountains, to confirm previously identified habitat associations (mountain versus valley) and seasonal changes in population composition. As expected from previous findings of studies on a smaller spatial scale, C. jacobsi dominated mountain habitats and mixed populations dominated valleys, and C. brunneus became more prevalent in August. Controlling for habitat and incorporating into the analysis seasonal changes in cline parameters and the standard errors of parental trait values revealed wider clines than previous studies (best estimates of 6.4 to 24.5 km in our study versus 2.8 to 4.7 km in previous studies) and increased percentage of trait variance explained (52.7% and 61.5% for transects 1 and 2 respectively, versus 17.6%). Revealing such strong and consistent patterns within a complex hybrid zone will allow more focused examination of the causes of variation in bimodality in mixed populations, in particular the roles of local selection versus habitat heterogeneity and gene flow between differentiated populations.     

The spermatogonial stem cell niche in the collared peccary (Tayassu tajacu)

In the seminiferous epithelium, spermatogonial stem cells (SSCs) are located in a particular environment called the "niche" that is controlled by the basement membrane, key testis somatic cells, and factors originating from the vascular network. However, the role of Leydig cells (LCs) as a niche component is not yet clearly elucidated. Recent studies showed that peccaries (Tayassu tajacu) present a peculiar LC cytoarchitecture in which these cells are located around the seminiferous tubule lobes, making the peccary a unique model for investigating the SSC niche. This peculiarity allowed us to subdivide the seminiferous tubule cross-sections in three different testis parenchyma regions (tubule-tubule, tubule-interstitium, and tubule-LC contact). Our aims were to characterize the different spermatogonial cell types and to determine the location and/or distribution of the SSCs along the seminiferous tubules. Compared to differentiating spermatogonia, undifferentiated spermatogonia (A(und)) presented a noticeably higher nuclear volume (P < 0.05), allowing an accurate evaluation of their distribution. Immunostaining analysis demonstrated that approximately 93% of A(und) were GDNF receptor alpha 1 positive (GFRA1(+)), and these cells were preferentially located adjacent to the interstitial compartment without LCs (P < 0.05). The expression of colony-stimulating factor 1 was observed in LCs and peritubular myoid cells (PMCs), whereas its receptor was present in LCs and in GFRA1(+) A(und). Taken together, our findings strongly suggest that LCs, different from PMCs, might play a minor role in the SSC niche and physiology and that these steroidogenic cells are probably involved in the differentiation of A(und) toward type A(1) spermatogonia.