Luigi Ledda

Nuclear localization of Galectin-3 in transformed thyroid cells: a role in transcriptional regulation.

The differential proteomic approach (2D gel analysis coupled to MALDI-MS analysis) of nuclear proteins can provide an extremely useful tool to understand control of cell proliferation and differentiation. In order to identify possible markers of dedifferentiation between normal and cancerous thyroid cells, we used a differential proteomics approach by comparing nuclear extracts from the normal rat thyroid cell line FRTL-5 and the completely undifferentiated Ki-mol cell line, obtained by transformation with the Ki-ras oncogene. Galectin-3 (Gal-3) was identified as highly expressed, in the nuclear compartment, only in the transformed cell line. By using different human cancer cell lines, we showed that Gal-3 is maximally expressed in nuclei of papillary cancer cells. We focused on the functional relationship existing between Gal-3 and the thyroid-specific transcription factor TTF-1, whose expression is maintained in papillary cancer where it can contribute to the proliferating status. By using gel-retardation and transient tranfection assays, we demonstrate that Gal-3 upregulates the TTF-1 transcriptional activity. GST-pulldown experiments demonstrate the occurrence of interaction between Gal-3 and TTF-1 homeodomain. Since several lines of evidence suggest a role for Gal-3 in controlling proliferation and tumor progression in thyroid cancer, the stimulatory activity played by Gal-3 over TTF-1 would account for a possible molecular mechanism through which the galectin controls proliferation in thyroid cells.

A proteomic characterization of water buffalo milk fractions describing PTM of major species and the identification of minor components involved in nutrient delivery and defense against pathogens

Water buffalo has been studied in relation to the exclusive use of its milk for the manufacture of high‐quality dairy products. Buffalo milk presents physicochemical features different from that of other ruminant species, such as a higher content of fatty acids and proteins. We report here a detailed proteomic analysis of buffalo skim milk, whey and milk fat globule membrane fractions. Notwithstanding the poor information available on buffalo genome, identification of protein isoforms corresponding to 72 genes was achieved by a combined approach based on 2‐DE/MALDI‐TOF PMF and 1‐DE/μLC‐ESI‐IT‐MS‐MS. Major protein components, i.e. αSl‐, αS2‐, β‐, κ‐caseins, α‐lactalbumin and β‐lactoglobulin, were characterized for PTM, providing a scientific basis to coagulation/cheese making processes used in dairy productions. Minor proteins detected emphasized the multiple functions of milk, which besides affording nutrition to the newborn through its major components, also promotes development and digestive tract protection in the neonate, and ensures optimal mammary gland function in the mother. Defense against pathogens is guaranteed by an arsenal of antimicrobial/immunomodulatory proteins, which are directly released in milk or occur on the surface of secreted milk‐lipid droplets. Proteins associated with cell signaling or membrane/protein trafficking functions were also identified, providing putative insights into major secretory pathways in mammary epithelial cells.

Soil organic C variability and microbial functions in a Mediterranean agro-forest ecosystem

Five soils characterised by different agro-forest managements, typical of Mediterranean environment and with increasing human impact were chosen in Sardinia (Italy): two vineyards with different management systems, a rotation hay crop-pasture and a forest (Quercus suber L.). The study aimed to investigate the relationships between C storage and microbial functionality in soil under different managements. Pools of total organic C and microbial biomass C were determined, as well as the loss of organic C due to microbial respiration (basal and cumulative) and several microbial indices (metabolic, mineralization, and microbial quotient) as indicators of the microbial efficiency in the use of energy and the degree of substrate limitation for soil microbes. Enzymes were chosen on their relevance in the C (β-cellobiohydrolase, N-acetyl-β-glucosaminidase, β-glucosidase, α-glucosidase), N (leucine aminopeptidase), S (arylsulphatase) and P (acid phosphatase) cycling and were used as indicators of functional diversity in soil. Organic C pools and enzyme activities on average increased noticeably in soils with a lower human impact showing the highest values in forest and the lowest in the vineyards, following the trend of organic matter availability. The trend in functional diversity reflected the increase of microbial pool and organic C availability: the vineyards showed a lower Shannon’s diversity index, whilst pasture and forest sites reached the maximum levels of functional diversity. These soils showed an increase of microbial efficiency in the use of available resources and the decrease of substrate limitation for soil microbes.

Soil bacterial community response to differences in agricultural management along with seasonal changes in a Mediterranean region

Land-use change is considered likely to be one of main drivers of biodiversity changes in grassland ecosystems. To gain insight into the impact of land use on the underlying soil bacterial communities, we aimed at determining the effects of agricultural management, along with seasonal variations, on soil bacterial community in a Mediterranean ecosystem where different land-use and plant cover types led to the creation of a soil and vegetation gradient. A set of soils subjected to different anthropogenic impact in a typical Mediterranean landscape, dominated by Quercus suber L., was examined in spring and autumn: a natural cork-oak forest, a pasture, a managed meadow, and two vineyards (ploughed and grass covered). Land uses affected the chemical and structural composition of the most stabilised fractions of soil organic matter and reduced soil C stocks and labile organic matter at both sampling season. A significant effect of land uses on bacterial community structure as well as an interaction effect between land uses and season was revealed by the EP index. Cluster analysis of culture-dependent DGGE patterns showed a different seasonal distribution of soil bacterial populations with subgroups associated to different land uses, in agreement with culture-independent T-RFLP results. Soils subjected to low human inputs (cork-oak forest and pasture) showed a more stable bacterial community than those with high human input (vineyards and managed meadow). Phylogenetic analysis revealed the predominance of Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes phyla with differences in class composition across the site, suggesting that the microbial composition changes in response to land uses. Taken altogether, our data suggest that soil bacterial communities were seasonally distinct and exhibited compositional shifts that tracked with changes in land use and soil management. These findings may contribute to future searches for bacterial bio-indicators of soil health and sustainable productivity.

An Integrated Assessment of the Impacts of Changing Climate Variability on Agricultural Productivity and Profitability in an Irrigated Mediterranean Catchment

Climate change is likely to have a profound effect on many agricultural variables, although the extent of its influence will vary over the course of the annual farm management cycle. Consequently, the effect of different and interconnected physical, technical and economic factors must be modeled in order to estimate the effects of climate change on agricultural productivity. Such modeling commonly makes use of indicators that summarize the among environmental factors that are considered when farmers plan their activities. This study uses net evapotranspiration (ETN), estimated using EPIC, as a proxy index for the physical factors considered by farmers when managing irrigation. Recent trends suggest that the probability distribution function of ETN may continue to change in the near future due to changes in the irrigation needs of crops. Also, water availability may continue to vary due to changes in the rainfall regime. The impacts of the uncertainties related to these changes on costs are evaluated using a Discrete Stochastic Programming model representing an irrigable Mediterranean area where limited water is supplied from a reservoir. In this context, adaptation to climate change can be best supported by improvements to the collective irrigation systems, rather than by measures aimed at individual farms such as those contained within the rural development policy.

Organic carbon pools and soil biological fertility are affected by land use intensity in Mediterranean ecosystems of Sardinia, Italy

Soil quality is mainly studied from the chemical and physical point of view, whereas soil biochemical and microbiological parameters are relatively more scarcely explored to assess the effect of management practices. This study aimed to evaluate soil organic carbon (SOC) and its pools; soil microbial activity parameters; and the Biological Fertility Index (BFI), in six land uses characteristics of the Mediterranean basin in north-eastern Sardinia. These land uses differed in management intensity and consisted of: tilled vineyard (TV), no tilled grassed vineyard (GV), former vineyards (FV), hay crop and pasture (HC and PA), cork oak forest (CO). Significant differences among ecosystems were found in most cases in (SOC), the related pools (total extractable carbon, humic and fulvic acids, not humified, not extractable), humification parameters (degree, rate and index of humification), and soil microbial activity (microbial carbon, respiration, metabolic quotient, and mineralization quotient). Pasture and cork oak forest showed in average a better soil quality for most biochemical and microbial parameters in comparison with the other ecosystems. The index of soil biological fertility (BFI) was higher under cork oak forest which is supposed to be the most sustainable ecosystem in the long term in this environment, able to maintain soil biological fertility and microbial diversity.

Yield and nitrogen fixation potential from white lupine grown in rainfed Mediterranean environments

There is renewed interest in white lupine (Lupinus albus L.), which is appreciated for its high protein content, full range of essential amino acids and as N source to rainfed cropping systems. Unfortunately, information on its N2 fixation ability is limited. This study aimed to: (i) quantify the N2 fixation ability of white lupine crop at the plot field scale in three different environments of Sardinia (Italy) under Mediterranean climate; (ii) determine the allocation of the plant-fixed N into different organs; and (iii) establish the relationship between fixed N and DM within plant organs. In a 2-year experiment, N2 fixation was estimated using the 15N isotopic dilution method. The productive performances and ability of white lupine to fix N2 widely differed in the three environments; peak values exceeded 300 kg ha−1 of fixed N. There were significant differences in the quantity of fixed N found in each plant organ at physiological maturity with 5, 20, 19 and 57 % of fixed N partitioned to roots, shoots, pod valves and grain, respectively. After grain harvesting, the net N balance ranged from negative values to 160 kg N ha−1. The relationship between fixed N and DM yield indicated 60, 34, 8 and 6 kg of fixed N per t of grain, pod valves, shoots and root, respectively, showing that fixed N preferentially accumulated in seeds at physiological maturity. Due to its high potential for N2 fixation and N benefit, white lupine represents a valuable crop option under rainfed Mediterranean conditions.

Climate change adaptation and water saving by innovative irrigation management applied on open field globe artichoke

The setting up of innovative irrigation water management might contribute to the mitigation of negative issues related to climate change. Our hypothesis was that globe artichoke irrigated with a traditionally drip system could be converted to an innovative water management system based on precision irrigation techniques and on evaporative cooling application in order to improve crop physiological status with positive impacts on earliness, total heads yield and water saving. Over two experiments carried out at plot- and field-scale, two irrigation management systems, differing in type and application time, were compared: (i) conventional, and (ii) canopy-cooling. Plant physiological status at a weekly sampling interval and the head atrophy incidence (as the ratio of the total primary heads collected) were monitored. We also recorded and determined heads production, and yield components. In both experiments, throughout the application period of evaporative cooling (three months), canopy-cooling showed the lowest value of leaf temperature and the highest photosynthesis values compared with the conventional one (+3 °C and -30%, respectively). The physiological advantage gained by the crop with evaporative cooling has led to a higher production both in terms of total yield (+30%), and in terms of harvested first order heads that from an economic viewpoint are the most profitable for farmers. At farm-scale, the canopy-cooling treatment resulted in a higher earliness (35 days) and water productivity (+36%) compared with conventional one. Our findings show that by combining evaporative cooling practice with precision irrigation technique the heads yield can be optimized also leading to a relevant water saving (-34%). Moreover, the study proved that canopy-cooling set up might be a winning strategy in order to mitigate climatic changes and heat stress conditions.

Energy and environmental performances of hybrid photovoltaic irrigation systems in Mediterranean intensive and super-intensive olive orchards

Over the last decades, traditional olive production has been converted to intensive and super-intensive cultivation systems, characterized by high plant density and irrigation. Although this conversion improves product quality and quantity, it requires a larger amount of energy input. The new contributions in this paper are, first, an analysis of the energy and environmental performance of two commercial-scale high peak-power hybrid photovoltaic irrigation systems (HPVIS) installed at intensive and super-intensive Mediterranean olive orchards; second, an analysis of PV hybrid solutions, comparing PV hybridization with the electric power grid and with diesel generators; and finally, a comparison of the environmental benefits of HPVIS with conventional power sources. Energy and environmental performances were assessed through energy and carbon payback times (EPBT and CPBT). The results show EPBT of 1.98 and 4.58 years and CPBT of 1.86 and 9.16 years for HPVIS in Morocco and Portugal, respectively. Moreover, the HPVIS were able to achieve low emission rates, corresponding to 48 and 103 g CO2e per kWh generated. The EPBT and CPBT obtained in this study were directly linked with the irrigation schedules of the olive orchards; therefore, weather conditions and irrigation management may modify the energy and environmental performances of HPVIS. The consumption of grid electricity and diesel fuel, before and after the implementation of HPVIS, was also analyzed. The results obtained show fossil energy savings of 67% for the Moroccan farm and 41% for the Portuguese installation. These savings suggest that the energy produced by HPVIS in olive orchards will avoid the emissions of a large amount of greenhouse gas and the exploitation of natural resources associated with fossil fuel production.

Organic Carbon and Ecosystem Services in Agricultural Soils of the Mediterranean Basin

Soil organic carbon (SOC), the major component of soil organic matter (SOM), is extremely important in all soil processes. Organic material in the soil is essentially derived from plant and animal residues, synthesized by microbes and decomposed under the influence of temperature, moisture and soil conditions. The problem of soil organic carbon depletion is of particular concern in the Mediterranean basin, with mild or moderately cold humid winters and warm dry summers, since high temperatures and reduced soil moisture conditions accelerate decomposition processes. This depletion is often in combination with non-conservative agronomic practices such as deep tillage and the low inputs of organic matter to soils, as well as other soil degradation processes, e.g. soil erosion by water. Typically, soils developed in the Mediterranean basin exhibit a high spatial variability of soil properties, are prone to drought, have low water holding capacity, and are shallow particularly on slopes or stony on the soil surface. They are also relatively fragile, and vulnerable to different human activities arising from changes in land cover and land use such as deforestation, urban development and deep soil tillage, and as a result of unsustainable agricultural and forestry practices. In this situation many ecosystem services (ES) are severely threatened. Here we describe the main ecosystems services including provisional, regulating, aesthetic and supporting services, with a focus on the provision of services from soil carbon and crop sustainable management in the Mediterranean basin, including the threats derived from soil erosion and floods. We highlight the specific measures for a sustainable cropland management that can decrease soil organic carbon (SOC) losses, increase the external organic matter (OM) input, and how to efficiently combine both. We reviewed different measures adopting external organic input addition to soil, conservation agriculture by no-tillage, residues retention, cover crops, organic farming compared to conventional agriculture and sustainable crop management by irrigation. In arable cropping systems, we reported an increase in C sequestration rate ranging from 1.3 to 5.3 Mg C ha−1 yr−1 with the addition of organic external inputs, and equal to 0.27 Mg C ha−1 yr−1 with the adoption of cover crops. No tillage and reduced tillage can increase C sequestration rate by 0.44 and 0.32 Mg C ha−1 yr−1 respectively. The adoption of combined management practices, where organic matter inputs and conservation tillage practices are simultaneously applied, increase C sequestration rate by 1.11 Mg C ha−1 yr−1. Organic farming management increase C sequestration rate by 0.97 Mg C ha−1 yr−1 as average, ranging from 0.62 to 1.32 Mg C ha−1 yr−1 with compost application and manure combined with cover crops respectively. Organic farming is also effective in increasing soil organic carbon stocks by about 70% compared with conventional management, and depending on soil type in permanent crops such as olive groves. Regulated deficit irrigation in summer crops is able to decrease CO2 emissions by about 10%, and consequently soil organic carbon losses without any negative effect on crop yields such as tomato. Soil erosion by water in permanent crops can be decreased by more than 70% with the use of cover crops, and by more than 40% with the adoption of temporary ditches on sloping soils in arable crops.