Specific CD8+ T cell responses correlate with control of simian immunodeficiency virus replication in Mauritian cynomolgus macaques

Specific major histocompatibility complex (MHC) class I alleles are associated with an increased frequency of spontaneous control of human and simian immunodeficiency viruses (HIV and SIV). The mechanism of control is thought to involve MHC class I-restricted CD8(+) T cells, but it is not clear whether particular CD8(+) T cell responses or a broad repertoire of epitope-specific CD8(+) T cell populations (termed T cell breadth) are principally responsible for mediating immunologic control. To test the hypothesis that heterozygous macaques control SIV replication as a function of superior T cell breadth, we infected MHC-homozygous and MHC-heterozygous cynomolgus macaques with the pathogenic virus SIVmac239. As measured by a gamma interferon enzyme-linked immunosorbent spot assay (IFN-γ ELISPOT) using blood, T cell breadth did not differ significantly between homozygotes and heterozygotes. Surprisingly, macaques that controlled SIV replication, regardless of their MHC zygosity, shared durable T cell responses against similar regions of Nef. While the limited genetic variability in these animals prevents us from making generalizations about the importance of Nef-specific T cell responses in controlling HIV, these results suggest that the T cell-mediated control of virus replication that we observed is more likely the consequence of targeting specificity rather than T cell breadth.     

Mechanisms for progenitor cell-mediated repair for ischemic heart injury

Recent studies have shown that treatments involving injection of stem cells into animals with damaged cardiac tissue result in improved cardiac functionality. Clinical trials have reported conflicting results concerning the recellularization of post-infarct collagen scars. No clear mechanism has so far emerged to fully explain how injected stem cells, specifically the commonly used mesenchymal stem cells (MSC) and endothelial precursor cells (EPC), help heal a damaged heart. Clearly, these injected stem cells must survive and thrive in the hypoxic environment that results after injury for any significant repair to occur. Here we discuss how ischemic preconditioning may lead to increased tolerance of stem cells to these harsh conditions and increase their survival and clinical potential after injection. As injected cells must reach the site in numbers large enough for repair to be functionally significant, homing mechanisms involved in stem cell migration are also discussed. We review the mechanisms of action stem cells may employ once they arrive at their target destination. These possible mechanisms include that the injected stem cells (1) secrete growth factors, (2) differentiate into cardiomyocytes to recellularize damaged tissue and strengthen the post-infarct scar, (3) transdifferentiate the host cells into cardiomyocytes, and (4) induce neovascularization. Finally, we discuss that tissue engineering may provide a standardized platform technology to produce clinically applicable stem cell products with these desired mechanistic capacities.     

Reproductive trade-off of the copepod Acartia tonsa in a hypersaline estuary of the Southwestern Atlantic. Temporal variations in the morphology of eggs

The purpose of the present work was to study the seasonal variations in egg production, morphology and hatching success in the cryptic species Acartia tonsa, taking into account variations in female size, population abundance and environmental factors in a turbid and hypersaline estuary. Sampling was performed during the austral warm (18–23°C and 32–36 salinity) and cold seasons (5–7°C; 32–38) in Bahía Blanca Estuary (BBE), Argentina, during 2007 and 2009. Field-collected females were incubated in the laboratory simulating in situ environmental conditions, and specimens from fixed samples were measured using optical and scanning electronic microscopy. Acartia tonsa’s marked seasonality in its reproductive traits was found to ensure its permanence in the water column all over the year. During the warm season, small-sized females were observed to invest their energy in the production of subitaneous eggs with high hatching success and smooth appearance (12.95?±?2.38 eggs f^?1 day^?1 and specific egg production rate (SEP) of 16.57%C f^?1 day^?1). During the cold season, females invested C in body mass as well as in the production of resting eggs of three different morphotypes (6.56?±?3.2 eggs f^?1 day^?1 and SEP of 7.37%C f^?1 day^?1). Although these morphotypes were found to show differences in surface ornamentation, they exhibited the same delayed hatching behaviour. The eggs with shorter spines were found to integrate the resting egg bank in BBE. Our findings confirming a delayed egg hatching behaviour and a great tolerance to low temperatures and high salinities in the A. tonsa population in BBE suggest that this possible strain is a valuable phenotype for aquaculture.     

Anatomical,physiological, and biochemical traits involved in the UV-B radiation response in highbush blueberry

The effects of a long-term simulated spring-summer UV-B daily course on some anatomical, physiological, and biochemical features were studied in new and old leaves of blueberry (Vaccinium corymbosum L.) cultivars Legacy, Brigitta, and Bluegold. The results show that under UV-B exposure, leaf thickness increased in Bluegold due to an increased intercellular cavities. By contrast, Brigitta maintained its leaf thickness. The net photosynthetic rate was not significantly affected by the UV-B radiation in any of the cultivars; however, Brigitta presented a better photosystem II performance, since this cultivar had more efficient photochemistry under the UV-B radiation. In addition, Brigitta also maintained enhanced total phenol and total anthocyanin content compared to the other cultivars. In conclusion, Brigitta was more resistant to the UV-B radiation than the other two cultivars.     

Water polluted with glyphosate formulations: effectiveness of a decontamination process using <Emphasis Type="Italic">Chlorella vulgaris</Emphasis> growing as bioindicator

The environmental pollution caused by pesticides is considered a major problem worldwide. Glyphosate is one of the herbicides most widely used, and its use has increased sharply in the last years. In this work, the toxicity of four commercial glyphosate formulations (Eskoba^®, Panzer Gold^®, Roundup Ultramax^® and Sulfosato Touchdown^®) was assessed by determining the median effective concentration at 96 h (96 h-EC₅₀) using the microalga Chlorella vulgaris as the biological model. Although the formulations tested are moderately to slightly toxic to C. vulgaris according to the World Health Organization’s toxicity categories for aquatic and terrestrial organisms, this research shows that the four formulations are toxic, with Eskoba^® the least toxic and Roundup Ultramax^® the most toxic one. A UV/H₂O₂ remediation process for the detoxification of the samples was tested also. Its effectiveness was evaluated using a C. vulgaris growth inhibition test. Growth inhibition of C. vulgaris did not reach 18.2 %, indicating the efficacy of the UV/H₂O₂ remediation process to reduce glyphosate toxicity. In some of the samples tested within the first 48 h of the assay, C. vulgaris growth was even increased. The results of the present work suggest that the selected species was a good indicator to determine the toxicity level of glyphosate formulations and shows the relevance of the ecotoxicological tests to evaluate a physicochemical remediation process.     

The phosphorylation of p25/TPPP by LIM kinase 1 inhibits its ability to assemble microtubules

LIM kinase 1 (LIMK1) is a key regulator of actin dynamics as it phosphorylates and inactivates cofilin, an actin-depolymerizing factor. LIMK1 activity is also required for microtubule disassembly in endothelial cells. A search for LIMK1-interacting proteins identified p25alpha, a phosphoprotein that promotes tubulin polymerization. We found that p25 is phosphorylated by LIMK1 on serine residues in vitro and in cells. Immunoblotting analysis revealed that p25 is not a brain specific protein as previously reported, but is expressed in all mouse tissues. Immunofluorescence analysis demonstrated that endogenous p25 is co-localized with microtubules and is also found in the nucleus. Down-regulation of p25 by siRNA decreased microtubule levels while its overexpression in stable NIH-3T3 cell lines increased cell size and levels of stable tubulin. Bacterially expressed unphosphorylated p25 promotes microtubule assembly in vitro; however, when phosphorylated in cells, p25 lost its ability to assemble microtubule. Our results represent a surprising connection between the tubulin and the actin cytoskeleton mediated by LIMK1. We propose that the LIMK1 phosphorylation of p25 blocks p25 activity, thus promoting microtubule disassembly.     

The Effects of Nitroxyl (HNO) on Soluble Guanylate Cyclase Activity: INTERACTIONS AT FERROUS HEME AND CYSTEINE THIOLS

It has been previously proposed that nitric oxide (NO) is the only biologically relevant nitrogen oxide capable of activating the enzyme soluble guanylate cyclase (sGC). However, recent reports implicate HNO as another possible activator of sGC. Herein, we examine the affect of HNO donors on the activity of purified bovine lung sGC and find that, indeed, HNO is capable of activating this enzyme. Like NO, HNO activation appears to occur via interaction with the regulatory ferrous heme on sGC. Somewhat unexpectedly, HNO does not activate the ferric form of the enzyme. Finally, HNO-mediated cysteine thiol modification appears to also affect enzyme activity leading to inhibition. Thus, sGC activity can be regulated by HNO via interactions at both the regulatory heme and cysteine thiols.Nitric oxide (NO)² is the most studied of the endogenously generated nitrogen oxides and is well known to mediate many aspects of cardiovascular function including the regulation of vascular tone and platelet aggregation (for example, see Ref. 1). These responses are in large part due to the interaction of NO with its most established endogenous receptor, soluble guanylate cyclase (sGC) (2). This 150-kDa heterodimeric heme protein catalyzes the production of the second messenger molecule cyclic guanosine monophosphate (cGMP) from guanosine triphosphate (GTP) (3). The basal activity of sGC is enhanced several hundred fold upon binding of NO to the single regulatory heme site. This stimulation of activity is a result of a conformational change induced by cleavage of the proximal histidine heme ligand upon formation of the ferrous nitrosyl complex, which is preferentially pentacoordinate (4). In addition to heme site regulation of sGC, there are numerous reports indicating that oxidation of cysteine thiol residues on this protein can also alter/regulate both the basal activity and the degree of NO-mediated activation (5–10).Recently, the one-electron reduced and protonated congener of NO, nitroxyl (HNO) has received significant interest as a cardiovascular agent whose actions are independent of NO formation (11). For example, a study by Ellis and co-workers (12) suggests that HNO is a vital component of endothelium-derived relaxing factor along with NO in rat aorta. HNO is also able to mediate murine aorta vasorelaxation even in the presence of NO scavengers (13). Furthermore, the vasodilation produced by HNO was inhibited by the sGC heme site inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]-quinoxalin-1-one implicating sGC activation in this HNO-mediated effect. In addition to its effects on large conduit vessels like the aorta, HNO also dilates rat small mesenteric resistance-like arteries through sGC-dependent and voltage-dependent K⁺ channel-dependent mechanisms (14). Nitroxyl (derived from the HNO-donor Angeli''s salt) is also a potent dilator of feline pulmonary vasculature equal to that of the NO donors SPER/NO, DETA/NO, and SULFI/NO (15). Most recently, HNO was found to be a potent dilator of rat coronary arteries through an sGC-mediated mechanism (16). The evidence presented in these studies suggests that HNO is able to modulate cGMP levels through an interaction with sGC, an idea in conflict with a previous report showing that NO is the only nitrogen oxide capable of directly activating sGC (17).HNO forms a stable adduct with the ferrous heme of deoxymyoglobin (18, 19) providing precedence for a possible interaction between HNO and sGC that is akin to the interaction of NO with ferrous sGC. In light of all the reports indicating possible HNO-mediated activation of sGC, an examination of the direct interaction of HNO with purified sGC was carried out to evaluate the possibility that HNO may be capable of directly interacting with sGC to elicit activation. Moreover, due to the previously reported thiol redox regulation of sGC (see above) and the known thiophilicity of HNO (20), we also examined the effects of HNO-mediated thiol modification on enzyme activity.