Role of MicroRNA 1207-5P and Its Host Gene,the Long Non-Coding RNA Pvt1, as Mediators of Extracellular Matrix Accumulation in the Kidney: Implications for Diabetic Nephropathy

Diabetic nephropathy is the most common cause of chronic kidney failure and end-stage renal disease in the Western World. One of the major characteristics of this disease is the excessive accumulation of extracellular matrix (ECM) in the kidney glomeruli. While both environmental and genetic determinants are recognized for their role in the development of diabetic nephropathy, epigenetic factors, such as DNA methylation, long non-coding RNAs, and microRNAs, have also recently been found to underlie some of the biological mechanisms, including ECM accumulation, leading to the disease. We previously found that a long non-coding RNA, the plasmacytoma variant translocation 1 (PVT1), increases plasminogen activator inhibitor 1 (PAI-1) and transforming growth factor beta 1 (TGF-β1) in mesangial cells, the two main contributors to ECM accumulation in the glomeruli under hyperglycemic conditions, as well as fibronectin 1 (FN1), a major ECM component. Here, we report that miR-1207-5p, a PVT1-derived microRNA, is abundantly expressed in kidney cells, and is upregulated by glucose and TGF-β1. We also found that like PVT1, miR-1207-5p increases expression of TGF-β1, PAI-1, and FN1 but in a manner that is independent of its host gene. In addition, regulation of miR-1207-5p expression by glucose and TGFβ1 is independent of PVT1. These results provide evidence supporting important roles for miR-1207-5p and its host gene in the complex pathogenesis of diabetic nephropathy.     

Artichoke Leaf Morphology and Surface Features in Different Micropropagation Stages

Artichoke (Cynara scolymus L.) leaf size and shape, glandular and covering trichomes, stomatal density, stomata shape, pore area and epicuticular waxes during micropropagation stages were studied by scanning electron microscopy (SEM) and morphometric analysis with the aim to improve the survival rate after transfer to greenhouse conditions. Leaves from in vitro shoots at the proliferation stage showed a spatular shape, ring-shaped stomata, a large number of glandular trichomes and juvenile covering hairs, but failed to show any epicuticular waxes. Leaves from in vitro plants at the root elongation stage showed a lanceolated elliptic shape with a serrated border, elliptical stomata, decreased pore area percentage, stomatal density, and mature covering trichomes. One week after transfer to ex vitro conditions, epicuticular waxes appeared on the leaf surface and stomata and pore area were smaller as compared to in vitro plants. Artichoke acclimatization may be improved by hormonal stimulation of root development, since useful morphological changes on leaves occurred during root elongation.     

Phytolith assemblages in grasses native to central Argentina

BACKGROUND AND AIMS: Phytolith reference collections are a prerequisite for accurate interpretation of soil phytolith assemblages aimed at reconstructing past vegetation. In this study a phytolith reference collection has been developed for several grasses native to central Argentina: Poa ligularis, Piptochaetium napostaense, Stipa clarazii, Stipa tenuis, Stipa tenuissima, Stipa eriostachya, Stipa ambigua, Stipa brachychaeta, Pappophorum subbulbosum, Digitaria californica, Bothriochloa edwardsiana and Aristida subulata. METHODS: For each species, phytoliths present in the leaf blades were classified into 47 morphotypes, and their relative frequency determined by observing 300-400 phytoliths per sample (n = 5). Data were analyzed by complete linkage cluster analysis, using the Morisita Index as measure of association. KEY RESULTS: The results showed differentiation among phytolith assemblages at species level or at plant functional type level. Cluster analysis separated C3 from C4 species and palatable from non-palatable species. CONCLUSIONS: This study highlights the possibility of reconstructing past vegetation in central Argentina grasslands through the analysis of soil phytolith assemblages.     

Plant community resilience in the face of fire: experimental evidence from a semi‐arid shrubland

The ability of communities or ecosystems to recover their structure and function after a disturbance is known as resilience. According to different views, resilience can be influenced by the resource‐use strategies of the plant functional types that dominate the community or by the existence of functional redundancy within plant functional types. We investigated how the dominance of different plant functional types and species affected the resilience of a mountain shrubland after an intense fire. We took advantage from a pre‐existing long‐term removal experiment in which either whole plant functional types (deciduous shrubs, graminoids, perennial forbs and annual forbs) or the dominant species within each plant functional type were removed for 10 years. We sampled species and plant functional types cover during the first growing season after the fire. First, to test whether functional redundancy increased resilience, we analyzed the existence of functional compensation inside plant functional types. Second, to test whether the dominance of plant functional types with different resource‐use strategies affected recovery, we compared resilience at the levels of species, plant functional types and total cover, estimated on the basis of a change index and multivariate Euclidean distances. No compensation was observed in any of the plant functional types. At the level of species, we found that the assemblages dominated by conservative resource‐use strategies were the ones showing higher resilience. This was due to the high recovery of the dominant species of shrubs plant functional type. The opposite (lowest recovery of conservative resource‐use strategies) was found at the plant functional type and total cover‐levels. Our study did not support the hypothesis of resilience by functional redundancy. Instead, regeneration by buried meristems from the pre‐fire stage appeared to be the factor that most influenced recovery. Resource‐use strategies explained resilience of vegetation cover, but not of floristic composition. Regeneration traits, rather than vegetative traits or mechanism of functional compensation, appeared as the most relevant to explain the response of this system after fire.     

Leaf anatomy of <Emphasis Type="Italic">Cynara scolymus</Emphasis> L. in successive micropropagation stages

Summary Leaf structure along the successive stages of Early French artichoke Cynara scolymus L. micropropagation was characterized using light and transmission electron microscopy. The mesophyll presents disorganized spongy and palisade parenchyma with large intercellular spaces and a few small chloroplasts in the leaves of plants cultured in vitro. In addition, both epidermal surfaces of such leaves invariably show a cell wall of the same thickness with a very thin cuticle and open stomata. In the root differentiation stage in vitro, structural changes take place in the leaves that are favorable for survival in the acclimatization stage: conspicuous cuticle, greater cell wall thickness, functional stomata, better mesophyll organization, developed vascular bundles, and the presence of sclerenchymatous tissue are observed. These features found in later in vitro stages are maintained in the following ex vitro stages, some becoming more evident. Our results demonstrate that the structural changes required to ensure appropriate acclimatization of micropropagated artichoke plants begin at the root differentiation stage, which can reduce in vivo acclimatization time and achieve greater survival of transferred plants.     

Liquidity Spillover in International Stock Markets through Distinct Time Scales

This paper identifies liquidity spillovers through different time scales based on a wavelet multiscaling method. We decompose daily data from U.S., British, Brazilian and Hong Kong stock markets indices in order to calculate the scale correlation between their illiquidities. The sample is divided in order to consider non-crisis, sub-prime crisis and Eurozone crisis. We find that there are changes in correlations of distinct scales and different periods. Association in finest scales is smaller than in coarse scales. There is a rise on associations in periods of crisis. In frequencies, there is predominance for significant distinctions involving the coarsest scale, while for crises periods there is predominance for distinctions on the finest scale.