60 research outputs found
Characterization of normal and "albino" phenotypes in Erythrina crista-galli
We present here a characterization of Erythrina crista-galli L. (syn: Erythrina lamifolia Jacq.) seedlings, obtained from a plant from the Botanical Garden of Pisa University. This plant produces seeds that, during germination, have shown two different seedling phenotypes: normal (NT, 75%) and "albino" types (AT, 25%). Albino seedlings survive only 8–9 weeks and their growth is dramatically reduced when compared with wild type seedlings. Biochemical investigations have shown that albino seedlings completely lack chlorophyll and carotenoids and also soluble sugar levels are lower than in the normal type. We have also conducted sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) experiments and silver staining analysis on different protein extracts from shoots and leaves of both phenotypes, and demonstrated strong differences in protein patterns. The almost total absence of putative small and large RuBisCo bands in albino seedlings should be emphasized. We have also microspectrophotometrica..
Karyological and molecular characterisation of subgenus Vicia (Fabaceae)
In the present report, we have analysed the subgenus Vicia by karyological and molecular approaches with the aim to clarify
the relationships among Vicia species included in this subgenus by previously evidenced morphological investigations.
Multivariate analysis using several karyomorphological parameters in addition to symmetry indices has allowed the
construction of a dendrogram of linkage distances very useful to compare and to include in a phylogenetic tree obtained by
internal transcribed spacer (ITS) rDNA sequences. Moreover, a separate analysis was performed combining our molecular
data on ITS sequences with those reported in the literature for the section Vicilla. Our analyses partly confirm the
monophyletic status of the various sections in which the subgenus Vicia has been divided, however questioning, in some
cases, the real need to maintain all the nine sections so far accepted and the placement of some individual species in the two
subgenera Vicia and Vicilla
A global lake and reservoir volume analysis using a surface water dataset and satellite altimetry
Lakes and reservoirs are crucial elements of the
hydrological and biochemical cycle and are a valuable resource for
hydropower, domestic and industrial water use, and irrigation. Although their
monitoring is crucial in times of increased pressure on water resources by
both climate change and human interventions, publically available datasets of
lake and reservoir levels and volumes are scarce. Within this study, a time
series of variation in lake and reservoir volume between 1984 and 2015 were
analysed for 137 lakes over all continents by combining the JRC Global
Surface Water (GSW) dataset and the satellite altimetry database DAHITI. The
GSW dataset is a highly accurate surface water dataset at 30 m resolution
compromising the whole L1T Landsat 5, 7 and 8 archive, which allowed for
detailed lake area calculations globally over a very long time period using
Google Earth Engine. Therefore, the estimates in water volume fluctuations
using the GSW dataset are expected to improve compared to current techniques
as they are not constrained by complex and computationally intensive
classification procedures. Lake areas and water levels were combined in a
regression to derive the hypsometry relationship (dh ∕ dA) for all
lakes. Nearly all lakes showed a linear regression, and 42 % of the lakes
showed a strong linear relationship with a R2 > 0.8, an
average R2 of 0.91 and a standard deviation of 0.05. For these lakes and
for lakes with a nearly constant lake area (coefficient of variation
< 0.008), volume variations were calculated. Lakes with a poor
linear relationship were not considered. Reasons for low R2 values were
found to be (1) a nearly constant lake area, (2) winter ice coverage and
(3) a predominant lack of data within the GSW dataset for those lakes. Lake
volume estimates were validated for 18 lakes in the US, Spain, Australia and
Africa using in situ volume time series, and gave an excellent Pearson
correlation coefficient of on average 0.97 with a standard deviation of
0.041, and a normalized RMSE of 7.42 %. These results show a high
potential for measuring lake volume dynamics using a pre-classified GSW
dataset, which easily allows the method to be scaled up to an extensive
global volumetric dataset. This dataset will not only provide a historical
lake and reservoir volume variation record, but will also help to improve our
understanding of the behaviour of lakes and reservoirs and their
representation in (large-scale) hydrological models.</p
Normative Autonomy and Normative Co-ordination: Declarative Power, Representation, and Mandate
In this paper we provide a formal analysis of the idea of normative co-ordination. We argue that this idea is based on the assumption that agents can achieve flexible co-ordination by conferring normative positions to other agents. These positions include duties, permissions, and powers. In particular, we explain the idea of declarative power, which consists in the capacity of the power-holder of creating normative positions, involving other agents, simply by "proclaiming" such positions. In addition, we account also for the concepts of representation, namely the representative's capacity of acting in the name of his principal, and of mandate, which is the mandatee's duty to act as the mandator has requested. Finally, we show how the framework can be applied to represent the contract-net protocol. Some brief remarks on future research and applications conclude this contribution
Evidence of Simultaneous Circulation of West Nile and Usutu Viruses in Mosquitoes Sampled in Emilia-Romagna Region (Italy) in 2009
BACKGROUND: In recent years human diseases due to mosquito-borne viruses were increasingly reported in Emilia-Romagna region (Italy), from the chikungunya virus in 2007 to the West Nile virus (WNV) in 2008. An extensive entomological survey was performed in 2009 to establish the presence and distribution of mosquito arboviruses in this region, with particular reference to flaviviruses. METHODOLOGY/PRINCIPAL FINDINGS: From May 6 to October 31, a total of 190,516 mosquitoes were sampled in georeferenced stations, grouped in 1,789 pools according date of collection, location, and species, and analyzed by reverse transcription polymerase chain reaction (RT-PCR) to detect the presence of RNA belong to Flavivirus genus. WNV was detected in 27 mosquito pools, producing sequences similar to those of birds and human strains obtained in 2008 outbreak, pointed out the probable virus overwintering. Isolation of WNV was achieved from one of these pools. Moreover 56 pools of mosquitoes tested positive for Usutu virus (USUV). Most PCR positive pools consisted of Culex pipiens, which also was the most analyzed mosquito species (81.4% of specimens); interestingly, USUV RNA was also found in two Aedes albopictus mosquito pools. Simultaneous circulation of WNV and USUV in the survey area was highlighted by occurrence of 8 mosquito WNV- and USUV-positive pools and by the overlaying of the viruses "hot spots", obtained by kernel density estimation (KDE) analysis. Land use of sampled stations pointed out a higher proportion of WNV-positive Cx. pipiens pool in rural environments respect the provenience of total sampled pool, while the USUV-positive pools were uniformly captured in the different environments. CONCLUSIONS/SIGNIFICANCE: Obtained data highlighting the possible role of Cx. pipiens mosquito as the main vector for WNV and USUV in Northern Italy, and the possible involvement of Ae. albopictus mosquito in USUV cycle. The described mosquito-based surveillance could constitute the foundation for a public health alert system targeting mosquito borne arboviruses
Arterially Perfused Neurosphere-Derived Cells Distribute Outside the Ischemic Core in a Model of Transient Focal Ischemia and Reperfusion In Vitro
BACKGROUND: Treatment with neural stem cells represents a potential strategy to improve functional recovery of post-ischemic cerebral injury. The potential benefit of such treatment in acute phases of human ischemic stroke depends on the therapeutic viability of a systemic vascular delivery route. In spite of the large number of reports on the beneficial effects of intracerebral stem cells injection in experimental stroke, very few studies demonstrated the effectiveness of the systemic intravenous delivery approach. METODOLOGY/PRINCIPAL FINDINGS: We utilized a novel in vitro model of transient focal ischemia to analyze the brain distribution of neurosphere-derived cells (NCs) in the early 3 hours that follow transient occlusion of the medial cerebral artery (MCA). NCs obtained from newborn C57/BL6 mice are immature cells with self-renewal properties that could differentiate into neurons, astrocytes and oligodendrocytes. MCA occlusion for 30 minutes in the in vitro isolated guinea pig brain preparation was followed by arterial perfusion with 1x10(6) NCs charged with a green fluorescent dye, either immediately or 60 minutes after reperfusion onset. Changes in extracellular pH and K(+) concentration during and after MCAO were measured through ion-sensitive electrodes. CONCLUSION/SIGNIFICANCE: It is demonstrated that NCs injected through the vascular system do not accumulate in the ischemic core and preferentially distribute in non-ischemic areas, identified by combined electrophysiological and morphological techniques. Direct measurements of extracellular brain ions during and after MCA occlusion suggest that anoxia-induced tissue changes, such as extracellular acidosis, may prevent NCs from entering the ischemic area in our in vitro model of transitory focal ischemia and reperfusion suggesting a role played by the surrounding microenviroment in driving NCs outside the ischemic core. These findings strongly suggest that the potential beneficial effect of NCs in experimental focal brain ischemia is not strictly dependent on their homing into the ischemic region, but rather through a bystander mechanism possibly mediated by the release of neuroprotective factors in the peri-infarct region
Neurosphere-Derived Cells Exert a Neuroprotective Action by Changing the Ischemic Microenvironment
BACKGROUND: Neurosphere-derived cells (NC), containing neural stem cells, various progenitors and more differentiated cells, were obtained from newborn C57/BL6 mice and infused in a murine model of focal ischemia with reperfusion to investigate if: 1) they decreased ischemic injury and restored brain function; 2) they induced changes in the environment in which they are infused; 3) changes in brain environment consequent to transient ischemia were relevant for NC action. METHODOLOGY/PRINCIPAL FINDINGS: NC were infused intracerebroventricularly 4 h or 7 d after 30 min middle cerebral artery occlusion. In ischemic mice receiving cells at 4 h, impairment of open field performance was significantly improved and neuronal loss significantly reduced 7–14 d after ischemia compared to controls and to ischemic mice receiving cells at 7 d. Infusion of murine foetal fibroblast in the same experimental conditions was not effective. Assessment of infused cell distribution revealed that they migrated from the ventricle to the parenchyma, progressively decreased in number but they were observable up to 14 d. In mice receiving NC at 7 d and in sham-operated mice, few cells could be observed only at 24 h, indicating that the survival of these cells in brain tissue relates to the ischemic environment. The mRNA expression of trophic factors such as Insulin Growth Factor-1, Vascular Endothelial Growth Factor-A, Transforming Growth Factor-β1, Brain Derived Neurotrophic Factor and Stromal Derived Factor−1α, as well as microglia/macrophage activation, increased 24 h after NC infusion in ischemic mice treated at 4 h compared to sham-operated and to mice receiving cells at 7 d. CONCLUSIONS/SIGNIFICANCE: NC reduce functional impairment and neuronal damage after ischemia/reperfusion injury. Several lines of evidence indicate that the reciprocal interaction between NC and the ischemic environment is crucial for NC protective actions. Based on these results we propose that a bystander control of the ischemic environment may be the mechanism used by NC to rapidly restore acutely injured brain function
Contourite depositional system after the exit of a strait: Case study from the late Miocene South Rifian Corridor, Morocco
Idealized facies of bottom current deposits (contourites) have been established for fine-grained contourite drifts in modern deep-marine sedimentary environments. Their equivalent facies in the ancient record however are only scarcely recognized due to the weathered nature of most fine-grained deposits in outcrop. Facies related to the erosional elements (i.e. contourite channels) of contourite depositional systems have not yet been properly established and related deposits in outcrop appear non-existent. To better understand the sedimentary facies and facies sequences of contourites, the upper Miocene contourite depositional systems of the South Rifian Corridor (Morocco) is investigated. This contourite depositional system formed by the dense palaeo-Mediterranean Outflow Water. Foraminifera assemblages were used for age-constraints (7.51 to 7.35 Ma) and to determine the continental slope depositional domains. Nine sedimentary facies have been recognized based on lithology, grain-size, sedimentary structures and biogenic structures. These facies were subsequently grouped into five facies associations related to the main interpreted depositional processes (hemipelagic settling, contour currents and gravity flows). The vertical sedimentary facies succession records the tectonically induced, southward migration of the contourite depositional systems and the intermittent behaviour of the palaeo-Mediterranean Outflow Water, which is mainly driven by precession and millennial-scale climate variations. Tides substantially modulated the palaeo-Mediterranean Outflow Water on a sub-annual scale. This work shows exceptional examples of muddy and sandy contourite deposits in outcrop by which a facies distribution model from the proximal continental slope, the contourite channel to its adjacent contourite drift, is proposed. This model serves as a reference for contourite recognition both in modern environments and the ancient record. Furthermore, by establishing the hydrodynamics of overflow behaviour a framework is provided that improves process-based interpretation of deep-water bottom current deposits
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