Functional Toll-like receptor 4 expressed in lactotrophs mediates LPS-induced proliferation in experimental pituitary hyperplasia

Toll like receptor 4 (TLR4) has been characterized for its ability to recognize bacterial endotoxin lipopolysaccharide (LPS). Considering that infections or inflammatory processes might contribute to the progression of pituitary tumors, we analyzed the TLR4 functional role by evaluating the LPS effect on lactotroph proliferation in primary cultures from experimental pituitary tumors, and examined the involvement of PI3K-Akt and NF-κB activation in this effect. In addition, the role of 17β-estradiol as a possible modulator of LPS-induced PRL cell proliferation was further investigated. In estrogen-induced hyperplasic pituitaries, LPS triggered lactotroph cell proliferation. However, endotoxin failed to increase the number of lactotrophs taking up BrdU in normal pituitaries. Moreover, incubation with anti-TLR4 antibody significantly reduced LPS-induced lactotroph proliferation, suggesting a functional role of this receptor. As a sign of TLR4 activation, an LPS challenge increased IL-6 release in normal and tumoral cells. By flow cytometry, TLR4 baseline expression was revealed at the plasma membrane of tumoral lactotrophs, without changes noted in the percentage of double PRL/TLR4 positive cells after LPS stimulus. Increases in TLR4 intracellular expression were detected as well as rises in CD14, p-Akt and NF-κB after an LPS challenge, as assessed by western blotting. The TLR4/PRL and PRL/NF-κB co-localization was also corroborated by immunofluorescence and the involvement of PI3K/Akt signaling in lactotroph proliferation and IL-6 release was revealed through the PI3K inhibitor Ly-294002. In addition, 17β-estradiol attenuated the LPS-evoked increase in tumoral lactotroph proliferation and IL-6 release. Collectively these results demonstrate the presence of functional TLR4 in lactotrophs from estrogen-induced hyperplasic pituitaries, which responded to the proliferative stimulation and IL-6 release induced by LPS through TLR4/CD14, with a contribution of the PI3K-Akt and NF-κB signaling pathways.     

In Silico Modeling of Shear-Stress-Induced Nitric Oxide Production in Endothelial Cells through Systems Biology

Nitric oxide (NO) produced by vascular endothelial cells is a potent vasodilator and an antiinflammatory mediator. Regulating production of endothelial-derived NO is a complex undertaking, involving multiple signaling and genetic pathways that are activated by diverse humoral and biomechanical stimuli. To gain a thorough understanding of the rich diversity of responses observed experimentally, it is necessary to account for an ensemble of these pathways acting simultaneously. In this article, we have assembled four quantitative molecular pathways previously proposed for shear-stress-induced NO production. In these pathways, endothelial NO synthase is activated 1), via calcium release, 2), via phosphorylation reactions, and 3), via enhanced protein expression. To these activation pathways, we have added a fourth, a pathway describing actual NO production from endothelial NO synthase and its various protein partners. These pathways were combined and simulated using CytoSolve, a computational environment for combining independent pathway calculations. The integrated model is able to describe the experimentally observed change in NO production with time after the application of fluid shear stress. This model can also be used to predict the specific effects on the system after interventional pharmacological or genetic changes. Importantly, this model reflects the up-to-date understanding of the NO system, providing a platform upon which information can be aggregated in an additive way.     

Multilamellar bodies linked to two active plasmalemma regions in the pollen grains of Sarcocapnos pulcherrima

The presence of visible multilamellar bodies in the cytoplasm of pollen grains of at least seven species of the family Papaveraceae has led us to study the behaviour of these bodies during pollen-grain ontogeny and in growing pollen tubes of Sarcocapnos pulcherrima C. Morales & R. Garcia germinated in vitro. Our transmission-electron-microscope (TEM) studies in pollen grains show that the multilamellar bodies may be classified as: 1) small, isolated and placed in the region of apertures in the cytoplasm; and 2) large, in clusters and in contact with the active plasmalemma apertures only when tubules are being formed in the apertural intine. Similar types of multilamellar bodies to those observed in the pollen apertures can be seen near the apex of the growing pollen tube (small and isolated) and in contact with the apex plasmalemma (large and clustered). Our results support the hypothesis that the multilamellar bodies are functionally linked to moments when the cytoplasmic membrane is very active. We have also linked the multilamellar bodies to Golgi vesicles as they both react positively to acid-phosphatase (AP) staining and also to the plasmalemma by the thiocarbohydrazide-silver proteinate-staining (TCH-Sp) electron-contrasting technique.     

Deforestation and Reforestation of Latin America and the Caribbean (2001–2010)

Forest cover change directly affects biodiversity, the global carbon budget, and ecosystem function. Within Latin American and the Caribbean region (LAC), many studies have documented extensive deforestation, but there are also many local studies reporting forest recovery. These contrasting dynamics have been largely attributed to demographic and socio‐economic change. For example, local population change due to migration can stimulate forest recovery, while the increasing global demand for food can drive agriculture expansion. However, as no analysis has simultaneously evaluated deforestation and reforestation from the municipal to continental scale, we lack a comprehensive assessment of the spatial distribution of these processes. We overcame this limitation by producing wall‐to‐wall, annual maps of change in woody vegetation and other land‐cover classes between 2001 and 2010 for each of the 16,050 municipalities in LAC, and we used nonparametric Random Forest regression analyses to determine which environmental or population variables best explained the variation in woody vegetation change. Woody vegetation change was dominated by deforestation (?541,835 km²), particularly in the moist forest, dry forest, and savannas/shrublands biomes in South America. Extensive areas also recovered woody vegetation (+362,430 km²), particularly in regions too dry or too steep for modern agriculture. Deforestation in moist forests tended to occur in lowland areas with low population density, but woody cover change was not related to municipality‐scale population change. These results emphasize the importance of quantitating deforestation and reforestation at multiple spatial scales and linking these changes with global drivers such as the global demand for food.     

Population Composition and Ectoparasite Prevalence on Bats (Sturnira ludovici; Phyllostomidae) in Forest Fragments and Coffee Plantations of Central Veracruz,Mexico

Studies comparing the abundance of frugivorous bats in shade‐coffee plantations and forest fragments report contradictory results, and have not taken into account the landscape context in which coffee plantations are immersed. Variables of population composition such as abundance, sex proportion, and reproductive condition, together with biological tags (i.e., bat fly prevalence), can provide information about spatiotemporal dynamics of habitats used by bats. In the central part of Veracruz, Mexico, we compared population variables and ectoparasite prevalence of the highland yellow‐shouldered bat (Sturnira ludovici) in two landscapes, one dominated by shade‐coffee plantations and another by forest fragments. Comparing these attributes between these two landscapes will increase our knowledge about the role of this agro‐ecosystem in the conservation of this species, which is an important seed disperser of cloud forest vegetation. Total abundance and proportion of females was greater in forest fragments than in coffee plantations, whereas the percentage of reproductive females and bat fly prevalence was similar between landscapes. Our results show that landscapes with forest fragments harbor the greatest abundance of S. ludovici, but shade‐coffee plantations also are utilized by S. ludovici and likely adjacent forest remnants provide enough food resources for this species and other frugivores. Moreover, this study provides more evidence documenting the importance of preserving the last cloud forest fragments in the central region of Veracruz, Mexico, and suggests that using shade‐coffee plantations to connect forest fragments may be an effective way of maintaining populations of S. ludovici and likely other volant frugivores.     

Bacterial community composition of anthropogenic biochar and Amazonian anthrosols assessed by 16S rRNA gene 454 pyrosequencing

Biochar (BC) is a common minor constituent of soils and is usually derived from the burning of wood materials. In the case of Amazonian dark earth (ADE) soils, the increased amount of this material is believed to be due to anthropogenic action by ancient indigenous populations. In this study, we use 16S rRNA gene pyrosequencing to assess the bacterial diversity observed in the BC found in ADEs as well as in the dark earth itself and the adjacent Acrisol. Samples were taken from two sites, one cultivated with manioc and one with secondary forest cover. Analyses revealed that the community structure found in each sample had unique features. At a coarse phylogenetic resolution, the most abundant phyla in all sequence libraries were Actinobacteria, Acidobacteria, Verrucomicrobia and Proteobacteria that were present in similar relative abundance across all samples. However, the class composition varied between them highlighting the difference between the Acrisol and the remaining samples. This result was also corroborated by the comparison of the OTU composition (at 97 % identity). Also, soil coverage has shown an effect over the community structure observed in all samples. This pattern was found to be significant through unweighted UniFrac as well as P tests. These results indicate that, although the ADEs are found in patches within the Acrisols, the contrasting characteristics found between them led to the development of significantly different communities.     

Protective role of salicylic acid applied before cold stress on antioxidative system and protein patterns in barley apoplast

This study was carried out to better understand the role of salicylic acid (SA) applied before cold stress in the cold tolerance mechanism. Two barley (Hordeum vulgare) cultivars, cold-sensitive (Akhisar) and cold-tolerant (Tokak), were used and 0.1 mM SA was applied to 7-d-old barley seedlings growing under control conditions (20/18 °C). The seedlings were transferred to cold chamber (7/5 °C) at the age 14, 21, and 28 d. After three days, the leaves were harvested to determine the activities of apoplastic antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX) and ice nucleation activity and electrophoretic patterns of apoplastic proteins. Cold treatment decreased the activities of all enzymes in cold-sensitive cultivar, however, it increased CAT and POX activities in cold-tolerant cultivar. Exogenous SA increased enzyme activities in both cultivars. Ice nucleation activity increased by cold treatment, especially in 17-d-old seedlings in both cultivars. In addition, SA treatment increased ice nucleation activity in all examined samplings in both cultivars. SA treatment caused accumulation or de novo synthesis of some apoplastic proteins. The results of the present study show that exogenous SA can improve cold tolerance by regulating the activities of apoplastic antioxidative enzymes, ice nucleation activity, and the patterns of apoplastic proteins.     

E. coli outbreak in a neonate intensive care unit in a general hospital in Mexico City

Nosocomial infections are a major cause of morbidity and mortality among neonates admitted to neonatal intensive care units (NICUs). The aim of this paper was to describe an outbreak of Escherichia coli among infants admitted to the NICU of the General Hospital “Dr. Manuel Gea Gonzalez” in May of 2008. The isolated E. coli strains were identified using standard biochemical methods. The susceptibilities of these strains were analysed by determining their minimal inhibitory concentrations. Following this, their molecular relationships to each other were assessed by pulsed field gel electrophoresis (PFGE) analysis and corroborated by serology. Twelve E. coli strains were isolated from blood, urine, or indwelling catheter samples from five cases of preterm infants within a 3-day period. Patients were admitted to the NICU of the general hospital and, during the outbreak, developed sepsis caused by E. coli. For four of the patients, the average age was 23 days, while one patient was a 3-month-old infant. Prior to sepsis, the infants had received assisted ventilation and hyperalimentation through a central venous catheter. Two profiles were observed by PFGE; profile A was identified as the outbreak’s cause and an outcome of cross-infection, while profile B showed genetic differences but serologically it was identified as part of the same serotype. We conclude that E. coli colonised the patients through horizontal transmission. A focal source of the microorganism in this outbreak was not identified, but cross-transmission through handling was the most probable route.