A mechanobiological model to study upstream cell migration guided by tensotaxis

Biomechanics and Modeling in Mechanobiology - Cell migration is a process of crucial importance for the human body. It is responsible for important processes such as wound healing and tumor...     

The Peculiar Facets of Nitric Oxide as a Cellular Messenger: From Disease-Associated Signaling to the Regulation of Brain Bioenergetics and Neurovascular Coupling

In this review, we address the regulatory and toxic role of ^·NO along several pathways, from the gut to the brain. Initially, we address the role on ^·NO in the regulation of mitochondrial respiration with emphasis on the possible contribution to Parkinson’s disease via mechanisms that involve its interaction with a major dopamine metabolite, DOPAC. In parallel with initial discoveries of the inhibition of mitochondrial respiration by ^·NO, it became clear the potential for toxic ^·NO-mediated mechanisms involving the production of more reactive species and the post-translational modification of mitochondrial proteins. Accordingly, we have proposed a novel mechanism potentially leading to dopaminergic cell death, providing evidence that NO synergistically interact with DOPAC in promoting cell death via mechanisms that involve GSH depletion. The modulatory role of NO will be then briefly discussed as a master regulator on brain energy metabolism. The energy metabolism in the brain is central to the understanding of brain function and disease. The core role of ^·NO in the regulation of brain metabolism and vascular responses is further substantiated by discussing its role as a mediator of neurovascular coupling, the increase in local microvessels blood flow in response to spatially restricted increase of neuronal activity. The many facets of NO as intracellular and intercellular messenger, conveying information associated with its spatial and temporal concentration dynamics, involve not only the discussion of its reactions and potential targets on a defined biological environment but also the regulation of its synthesis by the family of nitric oxide synthases. More recently, a novel pathway, out of control of NOS, has been the subject of a great deal of controversy, the nitrate:nitrite:NO pathway, adding new perspectives to ^·NO biology. Thus, finally, this novel pathway will be addressed in connection with nitrate consumption in the diet and the beneficial effects of protein nitration by reactive nitrogen species.

     

Glucoraphasatin: Chemistry, occurrence, and biological properties

Glucoraphasatin is an atypical glucosinolate mainly found in Raphanus sativus roots and sprouts. This review focuses on the chemistry, the occurrence, and the biological properties of glucoraphasatin.     

The CR3 motif of Rrp44p is important for interaction with the core exosome and exosome function

The 10-subunit RNA exosome is involved in a large number of diverse RNA processing and degradation events in eukaryotes. These reactions are carried out by the single catalytic subunit, Rrp44p/Dis3p, which is composed of three parts that are conserved throughout eukaryotes. The exosome is named for the 3′ to 5′ exoribonuclease activity provided by a large C-terminal region of the Rrp44p subunit that resembles other exoribonucleases. Rrp44p also contains an endoribonuclease domain. Finally, the very N-terminus of Rrp44p contains three Cys residues (CR3 motif) that are conserved in many eukaryotes but have no known function. These three conserved Cys residues cluster with a previously unrecognized conserved His residue in what resembles a metal-ion-binding site. Genetic and biochemical data show that this CR3 motif affects both endo- and exonuclease activity in vivo and both the nuclear and cytoplasmic exosome, as well as the ability of Rrp44p to associate with the other exosome subunits. These data provide the first direct evidence that the exosome-Rrp44p interaction is functionally important and also provides a molecular explanation for the functional defects when the conserved Cys residues are mutated.     

Evidences for genetic differentiation within the highly endemic and endangered annual fish Austrolebias nigrofasciatus (Cyprinodontiformes: Rivulidae)

Samples of Austrolebias nigrofasciatus (n = 103), an endangered species of annual fish endemic to a small area of the Patos-Mirim lagoon system encompassing the São Gonçalo Channel lowlands, were collected from eight isolated temporary ponds, four located at the known distribution range of the species and four located along the Piratini River lowlands, where morphologically different individuals were found. In the laboratory, fragments of the mitochondrial cytochrome c oxidase I (coI), cytochrome b (cytb) and nuclear rhodopsin (rho) genes were amplified, purified and sequenced for 100, 99 and 58 of these individuals, respectively. Samples were further analysed using phylogenetic and phylogeographic methods to evaluate the patterns of genetic diversity and differentiation presented within and between populations, while assessing their evolutionary history, in order to guide the application of further conservation strategies. We found that the four new populations from the Piratini River lowlands encompass a different lineage of A. nigrofasciatus that diverged from that encountered in the São Gonçalo Channel at approximately 0.165 M years before present, during a population expansion and did not yet attain reciprocal monophyly. This divergence was associated with a glacial event that was preceded by an interglacial period putatively associated with the dispersal. Moreover, significant levels of genetic differentiation and a high number of exclusive haplotypes could be encountered even in micro-geographical scales, as in the comparisons between populations located within the same major lineage, indicating each of them may encompass independent management units. Conservation actions are certainly urgent, especially in the face of signs of a recent bottleneck.     

Techniques for the detection of pathogenic Cryptococcus species in wood decay substrata and the evaluation of viability in stored samples

In this study, we evaluated several techniques for the detection of the yeast form of Cryptococcus in decaying wood and measured the viability of these fungi in environmental samples stored in the laboratory. Samples were collected from a tree known to be positive for Cryptococcus and were each inoculated on 10 Niger seed agar (NSA) plates. The conventional technique (CT) yielded a greater number of positive samples and indicated a higher fungal density [in colony forming units per gram of wood (CFU.g^-1) ] compared to the humid swab technique (ST). However, the difference in positive and false negative results between the CT-ST was not significant. The threshold of detection for the CT was 0.05.10³ CFU.g^-1, while the threshold for the ST was greater than 0.1.10³ CFU^-1. No colonies were recovered using the dry swab technique. We also determined the viability of Cryptococcus in wood samples stored for 45 days at 25ºC using the CT and ST and found that samples not only continued to yield a positive response, but also exhibited an increase in CFU.g^-1, suggesting that Cryptococcus is able to grow in stored environmental samples. The ST.1, in which samples collected with swabs were immediately plated on NSA medium, was more efficient and less laborious than either the CT or ST and required approximately 10 min to perform; however, additional studies are needed to validate this technique.     

Liver Accumulation of Plasmodium chabaudi-Infected Red Blood Cells and Modulation of Regulatory T Cell and Dendritic Cell Responses

It is postulated that accumulation of malaria-infected Red Blood Cells (iRBCs) in the liver could be a parasitic escape mechanism against full destruction by the host immune system. Therefore, we evaluated the in vivo mechanism of this accumulation and its potential immunological consequences. A massive liver accumulation of P. c. chabaudi AS-iRBCs (Pc-iRBCs) was observed by intravital microscopy along with an over expression of ICAM-1 on day 7 of the infection, as measured by qRT-PCR. Phenotypic changes were also observed in regulatory T cells (Tregs) and dendritic cells (DCs) that were isolated from infected livers, which indicate a functional role for Tregs in the regulation of the liver inflammatory immune response. In fact, the suppressive function of liver-Tregs was in vitro tested, which demonstrated the capacity of these cells to suppress naive T cell activation to the same extent as that observed for spleen-Tregs. On the other hand, it is already known that CD4+ T cells isolated from spleens of protozoan parasite-infected mice are refractory to proliferate in vivo. In our experiments, we observed a similar lack of in vitro proliferative capacity in liver CD4+ T cells that were isolated on day 7 of infection. It is also known that nitric oxide and IL-10 are partially involved in acute phase immunosuppression; we found high expression levels of IL-10 and iNOS mRNA in day 7-infected livers, which indicates a possible role for these molecules in the observed immune suppression. Taken together, these results indicate that malaria parasite accumulation within the liver could be an escape mechanism to avoid sterile immunity sponsored by a tolerogenic environment.     

Adipose Tissue-Derived Stem Cells Reduce Acute and Chronic Kidney Damage in Mice

Acute and chronic kidney injuries (AKI and CKI) constitute syndromes responsible for a large part of renal failures, and are today still associated with high mortality rates. Given the lack of more effective therapies, there has been intense focus on the use stem cells for organ protective and regenerative effects. Mesenchymal stem cells (MSCs) have shown great potential in the treatment of various diseases of immune character, although there is still debate on its mechanism of action. Thus, for a greater understanding of the role of MSCs, we evaluated the effect of adipose tissue-derived stem cells (AdSCs) in an experimental model of nephrotoxicity induced by folic acid (FA) in FVB mice. AdSC-treated animals displayed kidney functional improvement 24h after therapy, represented by reduced serum urea after FA. These data correlated with cell cycle regulation and immune response modulation via reduced chemokine expression and reduced neutrophil infiltrate. Long-term analyses, 4 weeks after FA, indicated that AdSC treatment reduced kidney fibrosis and chronic inflammation. These were demonstrated by reduced interstitial collagen deposition and tissue chemokine and cytokine expression. Thus, we concluded that AdSC treatment played a protective role in the framework of nephrotoxic injury via modulation of inflammation and cell cycle regulation, resulting in reduced kidney damage and functional improvement, inhibiting organ fibrosis and providing long-term immune regulation.