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Effects of some stable derivatives of butyrate used as feed additives on fish intestinal microbiota, histone modifications and the expression of genes related to epigenetic regulatory mechanisms and immune response.
No full textBacteria that inhabit the epithelium of the animals’ digestive tract provide the essential biochemical pathways for fermenting otherwise indigestible dietary fibers, leading to the production of short-chain fatty acids (SCFAs). Of the major SCFAs, butyrate has received particular attention due to its numerous positive effects on the health of the intestinal tract and peripheral tissues.
Butyrate plays a major role in enhancing epithelial cell proliferation and differentiation and in improving the intestinal absorptive function. It has also potential immunomodulatory and anti-inflammatory properties in the intestine and may prevent colorectal cancer in humans.
The mechanisms of action of butyrate are different; this four-carbon chain organic acid is a histone deacetylase inhibitor that play a predominant role in the epigenetic regulation of gene expression and cell function, therefore many of its mechanisms are related to its potent regulatory effect on gene expression.
During the first year of PhD, my research activity was related to the study of the effects of dietary sodium butyrate on histone modifications and the expression of genes involved in epigenetic regulatory mechanisms and immune response in European sea bass (Dicentrarchus Labrax) fed a plant-based diet.
Accordingly, the effects of butyrate used as a feed additive on fish epigenetics as well as its regulatory role in mucosal protection and immune homeostasis through impact on gene expression, were investigated.
To meet the aims, seven target genes related to inflammatory response and reinforcement of the epithelial defense barrier [tnfα (tumor necrosis factor alpha) il1β, (interleukin 1beta), il-6, il-8, il-10, and muc2 (mucin 2)] and five target genes related to epigenetic modifications [dicer1(doublestranded RNA-specific endoribonuclease), ehmt2 (euchromatic histone-lysine-N-methyltransferase 2), pcgf2 (polycomb group ring finger 2), hdac11 (histone deacetylase-11), and jarid2a (jumonji)] were analyzed in fish intestine and liver. We also investigated the effect of dietary butyrate supplementation on histone acetylation, by performing an immunoblotting analysis on liver core histone extracts. Results of the eight-week feeding trial showed no significant differences in weight gain or Specific Growth Rate (SGR) in sea bass that received 0.2% sodium butyrate supplementation in the diet in comparison to control fish that received a diet without Na-butyrate. Dietary butyrate led to a two-fold increase in the acetylation level of histone H4 at lysine 8, but showed no effect on the histone H3 at Lys9. Moreover, two different isoforms of histone H3 that might correspond to the H3.1 and H3.2 isoforms previously found in terrestrial animals were separated on the immunoblots. The expression of four (il1 β, il8, irf1, and tnfα) out of seven analyzed genes related to mucosal protection and inflammatory response was significantly different between the two analyzed tissues but only il10 showed differences in expression due to the interaction between tissue and butyrate treatment. In addition, butyrate caused significant changes in vivo in the expression of genes related to epigenetic regulatory mechanisms such as hdac11, ehmt2, and dicer1. Statistical analysis by two-way ANOVA for these genes showed not only significant differences due to the butyrate treatment, but also due to the interaction between tissue and treatment.
In the second year of my studies, I focused on a different fish species - gilthead sea bream (Sparus aurata), to investigate the effects of a specific combination of short- and medium-chain 1-monoglycerides on intestinal microbiome, gene expression, and fish growth performance.
In aquaculture research, one important aim of the gut microbiota studies is to provide a scientific basis for developing effective strategies to manipulate gut microbial communities through the diet, promoting fish health and improving productivity.
Currently, there is an increasing research interest towards the use of organic acids in commercial aqua-feeds, due to several beneficial effects they have on growth performance and intestinal tract’s health of farmed fish. Among organic acids, monoglycerides of short-chain fatty acids (SCFAs) and medium-chain fatty acids (MCFAs) have attracted particular research attention also for their bacteriostatic and bactericidal properties. Accordingly, the present study aimed to evaluate the potential beneficial effects of SCFA and MCFA monoglycerides, used as a feed additive, on fish growth performance, and intestinal microbiota composition. For this purpose, a specific combination of short- and medium-chain 1-monoglycerides (SILOhealth 108Z) was tested in 600 juvenile gilthead sea bream (Sparus aurata) of 60 g mean initial weight that were fed for 90 days with plant-based diets. Two isoproteic and isolipidic diets were formulated. The control fish group received a plantbased diet, whereas the other group received the same control feed, but supplemented with 0.5% of SILOhealth 108Z. The Illumina MiSeq platform for high-throughput amplicon sequencing of 16S rRNA gene and QIIME pipeline were used to analyse and characterize the whole microbiome associated with both thefeeds and S. aurata intestine. The number of reads taxonomically classified according to the Greengenes database was 394,611. We identified 259 OTUs at 97% identity in sea bream fecal samples; 90 OTUs constituted the core gut microbiota. Firmicutes, Proteobacteria and Actinobacteria represented the dominant phyla in both experimental groups. Among them, relative abundances of Firmicutes and Proteobacteria were positively and negatively affected by dietary SCFA monoglycerides supplementation, respectively. In summary, our findings clearly indicated that SILOhealth 108Z positively modulated the fish intestinal microbiota by increasing the number of beneficial lactic acid bacteria, namely, Lactobacillus, and reducing Gammaproteobacteria, which include several potential pathogenic bacteria. The specific composition of 1-monoglycerides of short and medium-chain fatty acids contained in SILOhealth 108Z could thus have a great potential as a feed additive in aquaculture
Physical and chemical aspects of the interaction of molecules with external surface and structural cavities of nanomaterials.
No full textThe research work carried out during this PhD project has been aimed to the investigation of molecular surface events relevant for the catalytic formation, in mild conditions, of amide/peptide bonds from non-activated reagents adsorbed on nanomaterials. The formation of C-N bonds is among the topics of high interest in modern research in chemistry, addressing issues ranging from fine to prebiotic chemistry. The implementation of this project required the selection of both catalyst and reactants. As for the nanomaterials, the criteria of choice were simplicity, availability and low cost for possible future applications and, on the other hand, reasonable representativeness of minerals possibly present on the early Earth, and active as catalyst towards adsorbed organic molecules. On this basis the following nanoparticles of silica and titania are selected as well as a zeolite of the ZSM-10 type, with a MOZ framework. This latter material was intended as a porous host for future studies of the high pressure induced oligomerization of amino acids. This part of the work belongs to a very recent project, and then the work carried out in this respect in this PhD thesis is focused on the synthesis of zeolite particles with proper framework features. The choice of reactants was driven, on one hand, on the suitability to be studied in depth by both experimental methods and theoretical modelling, and on the other hand, by the possibility to adsorb them on surfaces of nanomaterials from the vapour phase, i.e. in highly controlled conditions. Thus, the simplest carboxylic acid, HCOOH was selected, as well as two simple primary amines (methylamine and 1-pentanamine). One of the surface reaction investigated was the oligomerization of amino acids on the nanomaterials and for this glycine, alanine, histidine, serine were selected because of the possibility to adsorb them on catalyst via a chemical vapour deposition method. In summary, in Chapter One, the study targeting the elucidation of the mechanism of the amide bond formation between non-activated carboxylic acids and amines at the surface of amorphous silica is reported. The results prepare the ground to address the occurrence of this reaction and of the oligomerization of amino acids (glycine and alanine) at the surface of α-quartz sub-micrometric particles (Chapter Two). The study of the C-N bond formation at the surface of titania nanoparticles is the object of Chapters Three to Five. In particular, Chapter Three is devoted to the investigation the structural requirements of sites expose at the surface of titania nanoparticles in order they can act as catalytic sites towards amino acid oligomerization. In Chapter Four, insights on basic aspects of the interaction of formic acid and methylamine with the 101 anatase titania surface are presented. The possibility to prepare Ser-His dipeptides starting from non-activated amino acids by using titania nanoparticle as catalyst and the possible hydrolytic activity of the obtained peptides is the object of Chapter Five. Finally, in Chapter Six, challenges, successes and problems still to be solved for and effective synthesis of large ZSM-10 particles, required for multitechniques investigations, including single crystal X-ray diffraction
Clinico-pathologic, histophenotypic, molecular and prognostic characterization of small bowel carcinomas associated with celiac disease or Chron’s disease.
No full textNon-familial small bowel carcinomas are relatively rare and have a poor prognosis. Celiac disease and Crohn’s disease are predisposing conditions for small bowel carcinoma development. In this study, small bowel carcinomas associated with celiac disease (n=26), small bowel carcinomas associated with Crohn’s disease (n=25) and sporadic small bowel carcinomas (n=25) were systematically compared. We found that in patients undergoing surgery for small bowel carcinomas the underlying immune-mediated disorder represents a stage-independent prognostic factor. Despite their common origin in a chronically inflamed mucosa, celiac disease-associated and Crohn’s disease-associated small bowel carcinomas differ substantially in tumor cell phenotype, tumor-infiltrating lymphocyte density, microsatellite instability status, Wnt pathway activation, as well as mucosal precursor lesions. Moreover, Epstein-Barr virus-positive carcinomas may occur in the ileum of Crohn’s disease patients and are characterised by increased tumor-infiltrating lymphocytes, either with lymphoepithelioma-like or with a more conventional glandular histology
Vocazione polifunzionale del sequestro penale e problematica valutazione del fumus commissi delicti.
No full textThe matter of the research deals with the elements of fact and law which allow garnishments and other forms of attachment in the Italian criminal procedure. Particularly, it refers to the fumus commissi delicti element, applied due to the purpose and the rights involved in the specific measure ordered by the Court.
The dissertation starts with a chronological analysis (Criminal Procedure Code of 1930) in order to make clear how the actual forms of seizure and confiscating originate in the Italian criminal procedure. They are rather distinguishable, according to their aim, in seizure for evidentiary purposes (Criminal Procedure Code, Article 253), conservative seizure (Criminal Procedure Code, Articles 316 et seq.) and preventive seizure (Criminal Procedure Code, Articles 321 et seq.).
All the measures of attachment affect the fundamental rights, as the private propriety and the economic freedom (Constitution, Articles 41 and 42) and the freedom of expression (Constitution, Article 21). The legislative power shall find a balance between the protection of Constitutional rights and the necessity of ensuring the protective and evidentiary purposes of a measure limiting rights.
The analysis focuses on the peculiarity of the fumus, the most important element in balancing fundamental rights with the purposes of criminal procedure. In case of seizure for evidentiary purposes, the fumus determines whether a criminal offence may figuratively exist, since the prior necessity is to perpetuate secure evidence.
In case of preventive seizure, as the jurisprudence of the Supreme Court of Cassation appoints, the mere verification of the fumus is not enough.
The attachment has the same enforcement of the personal coercive measures, since it affects the fundamental rights, in order to prevent the deterioration in the consequences of a crime or the commission of any further criminal offence.The peculiarity of the fumus shall be meant not in an inquiry view, but in the sense of the “serious evidence of a crime”, granting an effective control upon the Public Prosecutor’s suit and the exercise of the rights of defence
Functional characterization of iron transporters Nramp1 and Nramp2 from Dictyostelium discoideum: a model of cellular iron homeostasis.
No full textBackground: Iron is an element necessary for all the organisms; its role in essential metabolism and cellular processes is fundamental for life. Studies on iron homeostasis, regulation and transport could be also done with a simplified model of professional phagocyte and pathogen host, Dyctiostelium discoideum (Dd).
Aim: Characterize the different metal transport specificity and regulation of the two iron transporters of Dd, ddNramp1 and ddNramp2.
Methods: Electrophysiological experiments with Two Electrode Voltage Clamp, X. laevis oocytes smoothies (XLOs) and immunolocalization experiments were performed to characterize these two divalent metal transporters and started with the synthesis of the two chimeric protein c-Nramp1 and c-Nramp2.
Results: We demonstrated that c-Nramp1 is a sodium independent transporter with specificity for divalent transition metals, as mammal orthologs of SLC11 family, with maximal inward currents at acidic pH and a high affinity for substrate. We also detected a peculiar sodium leak current, mainly at neutral pH, that suggest the presence of a strong interaction in the binding site.
We found that c-Nramp2 is electroneutral and transports divalent metal ions at all pH. Site directed mutagenesis on TMD6 restore the electrogenicity with small inward currents; XLOs analysis confirmed the electrophysiological results, these mutants are more functional than wild type c-Nramp2.
Conclusions: Our findings on ddNramp1 contributed with novel insights on the mechanism of action of the mammalian ortholog, whereas similar studies on ddNramp2 suggested a role of the homologous proteins in protists, and helped to clarify the possible function of the contractile vacuole in divalent metal homeostasis
Endometrial carcinomas with mismatch repair deficiency: immunophenotypical and molecular characterization.
No full textThis project was focused on the molecular and immunophenotypical characterization of a series of 80 gynecological cancers (GC, 64 endometrial, 12 ovarian, 4 endocervical) from patients who referred to the Cancer Genetic Counseling of Varese Hospital. We investigated the immunohistochemical (IHC) expression of MMR proteins, the microsatellite (MSI) profile of GC. We observed that the IHC analysis identified more cases with MMR deficit respect to the MSI analysis, in particular we identified a subgroup of cases with a borderline MSI profile. In order to improve MSI test, we tested four additional MSI target loci (RPL22, SRPR, MBD6 and NRIP) by setting up the MSI test in our series, these analysis revealed RPL22 and SRPR as informative loci in borderline cases and provided MSI evaluation criteria. We also analyzed MLH1 promoter methylation profile in MLH1 IHC negative samples to distinguish the sporadic MLH1 negative samples to LS cases. We set up the IHC analysis of ARID1A protein. We observed ARID1A protein loss in LS cancers, respect to sporadic cancer. Finally, we investigated the mutational landscape of 16 genes involved in endometrial cancer by targeted exome sequencing in 35 endometrial cancers. The genes most frequently mutated were ARID1A, ARID2, PTEN. The MSI cases show a higher mutational rate respect to MSS samples
LA cura degli interessi dei centri storici. Il centro storico come sistema complesso e come bene comune.
No full textHistoric centers are characterized by a high degree of complexity. In the first part of the thesis, an overview of basic knowledge of the regulatory system is given to the reader, by mapping the norms involving the historical centers.
To further emphasize the fact that the historic center involves extremely varied interests, many different aspects are analyzed, for example the effects of gentrification, the problem of soil consumption, restructuring incentives, the norms regarding the circulation and parking in historic centers, antipollution measures, in addition to the great theme of the delicate relationship between a site's vitality and the trade protection in historic centers.
The second part of the thesis has a constructive and innovative approach. The aim is to induce the reader to look at the historical center from a new perspective, exploiting multidisciplinary concepts. It is required a new methodological approach for this topic, that is to describe the historical center as a complex adaptive system and as a Commons, trying to find a new model for the management of historical centers.
In the concluding part of the elaboration is carried out an empirical research of the administrative techniques of management of the historical centers, the research concerns the level of the Italian municipal administrations, in this context a great emphasis is devoted to the important model of the UNESCO Site Management Plans.
The UNESCO site reference rules are explained and later the Italian experience is analyzed, special attention is given to the Management Plans of Historic Centers UNESCO sites of the Municipalities of Florence and Siena. Based on these considerations, more general conclusions are taken. For more details, refer to the full text of the PhD thesis
Clinical application of fluorescence guided surgery
No full textThe term fluorescence guided surgery (FGS) describes a medical technology based on real-time imaging intended to help and guide the surgeon during his operating practice.
In last years many innovations in surgical technique and minimally invasive technologies with laparoscopic, endoscopic and robotic techniques, has greatly improved surgical practice. Nevertheless, despite these constant advances, surgery still relies primarily on the surgeon's vision and on white-light reflectance.
The emerging field of fluorescent surgical imaging promises to be a powerful enhancement to improve surgical guidance.
Among all cromophores and fluorophores that could work as probes in medical imaging techniques, Near-infrared (NIR) fluorescence imaging with Indocyanine green (ICG) is emerging as major contributions to intraoperative surgical decisions and many different applications have already been described in literature.
ICG is a dye used in medicine since the mid-1950s for a variety of diagnostic applications in cardiology, ophthalmology and to test the hepatic clearance; however, its fluorescent properties have only recently been applied to new minimally invasive surgical instrumentations. ICG has some peculiar features that promote its widespread use: it is virtually harmless, due to lowest rate of adverse effects reported and to very high toxic dose for human body, and it is not expensive.
In addition FGS appears to have a great potential to become a standard in everyday clinical practice due to the multiple different possible applications and the ease of employ.
Our group started working on this technology since few years ago, cooperating with one of surgical imaging leading company on the market in developping new applications and tehcnical improvements.
As ICG, once injected, is excreted through the bile, it simply allows to outline the biliary tree anatomy by visualization under NIR light. This application find its ultimate use during laparoscopic cholecystectomy (LC).
LC is one of the most common procedure in general surgery worldwide (750.000 cases are performed every year in the United States); the most temible surgical complication of LC is biliary duct injuries (BDI), that could lead to severe consequences in terms of morbidity and mortality of patients. Several studies have already reported that the the primary cause of BDI is misinterpretation of biliary anatomy (71%-97% of all cases), in some cases influenced by lack of tactile feedback and anatomic variations. FGS with ICG can be used effectively in LC to visualize the biliary system and avoid injuries; to date in literature several authors published case reports or small data series on this methodic, nevertheless larger randomized controlled studies are needed to confirm and validate the potential role of this technology as gold standard for LC.
Another extremely interesting field of employment of ICG fluorescent guided surgery is intraoperative angiography; ICG injected into the bloodstream and excited by NIR light can give information about study vascular anatomy and parenchimal perfusion in various clinical situations.
Our group, at the beginning of our experience with ICG FGS, tested several possible “angiographic” applications (clarify vascular anatomy for dissection in delicate procedures or solid organ perfusion for transplants) but we decided to focus our studies on the assessment of bowel microperfusion before anastomosis creation.
Anastomotic leak (AL) is a frequent and serious complication in gastrointestinal resective surgery and adequate bowel perfusion has been stressed as one of the key elements for suture healing. Currently, there is no widespread method to assess and quantify the perfusion of gastrointestinal anastomoses intra- operatively, besides the subjective evaluation by the surgeon.
Real time intraoperative ICG fluorescent angiography (FA) is a feasible technique and a promising tool for everyday surgical practice. Nevertheless randomized controlled trials are needed to standardize technique and determine if ICG-FA might have positive impact on the AL rate in gastrointestinal anastomoses
Smooth path planning with Pythagorean-hodoghraph spline curves geometric design and motion control
No full textThis thesis addresses two significative problems regarding autonomous systems, namely path and trajectory planning. Path planning deals with finding a suitable path from a start to a goal position by exploiting a given representation of the environment. Trajectory planning schemes govern the motion along the path by generating appropriate reference (path) points.
We propose a two-step approach for the construction of planar smooth collision-free navigation paths. Obstacle avoidance techniques that rely on classical data structures are initially considered for the identification of piecewise linear paths that do not intersect with the obstacles of a given scenario.
In the second step of the scheme we rely on spline interpolation algorithms with tension parameters to provide a smooth planar control strategy. In particular, we consider Pythagorean–hodograph (PH) curves, since they provide an exact computation of fundamental geometric quantities. The vertices of the previously produced piecewise linear paths are interpolated by using a G1 or G2 interpolation scheme with tension based on PH splines. In both cases, a strategy based on the asymptotic analysis of the interpolation scheme is developed in order to get an automatic selection of the tension parameters.
To completely describe the motion along the path we present a configurable trajectory planning strategy for the offline definition of time-dependent C2 piece-wise quintic feedrates. When PH spline curves are considered, the corresponding accurate and efficient CNC interpolator algorithms can be exploited
Monitoring and analysis of the impacts of climate change on plant biodiversity and terrestrial ecosystems in alpine and polar environment.
No full textHigh altitude and latitude environments are among those areas of the Planet that are experiencing the most significant changes of the climatic conditions due to the recent global change. Terrestrial ecosystems in these regions are extremely sensitive to climate, and for this reason, well suited for the comprehension, evaluation and monitoring of their responses, and their modelling under different climate change scenarios.
This thesis focuses on the impacts of climate change on terrestrial ecosystems of alpine (Foscagno valley, central Italian Alps) and Polar (both Continental Antarctica and Maritime Antarctica) tundra habitats. European Alps and Maritime Antarctica are two of the three areas of the world where have been recorded the greatest air temperature warming in the last 50 years, whereas simultaneously in Continental Antarctica, air temperature was almost stable. Due to different trends of climate and anthropogenic pressures around the world, contemporary global change is characterized by a large spatial variability that makes the planning of adaptation and mitigation strategies particularly complicate. Peculiar habitats have been protected by international, European and national programs (the Foscagno valley belongs to the Nature 2000 network, while the Antarctica ecosystems are protected under the Antarctic treaty and specially protected areas). However, analyzing the dynamics of terrestrial ecosystems in regions that are facing different climate change scenarios, as well as biological and anthropogenic constrains, could improve the knowledge of the dynamics of terrestrial ecosystems, that could be used for modelling future scenarios and to implement the adaptation plans for such protected areas.
The identification of conservation actions and monitoring plans is thus the priority for such threatened environments, to ensure a correct management of the biodiversity and of the ecosystem services that they can provide.
The alpine site is the Foscagno Valley, a high altitude site (>2500 m a.s.l.) located in the central Italian Alps, where since 2007 a field-based project of snow, ground surface temperature and plant phenology monitoring started. This PhD is part of this project, that since summer 2015 was implemented with manipulation experiments on two typical alpine vegetation communities (snowbed and grassland) to simulate potential future climate change related impacts on plant phenology and growth, including increase of nutrient availability (simulated by additions of urea, ammonium sulfate, NPK respectively), water availability (once or twice per week additions of water), lack of reproductive stages (flowers removal).
The primary aim of this PhD was to investigate alpine plant phenology and its relationships with climate change. We monitored phenology of 21 plants typical of alpine environments and representative of different growth forms types. In particular, we hypothesized that: a) the vegetative development (shoot appearance and leaf emergence) is regulated by snow melt timing, while the other phenological stages (i.e. flowering, seed development and ripening, and leaf senescence) are regulated mostly by photoperiod, which should indicate a conservative and adaptive strategy of alpine plants; b) plant phenology shows different plasticity depending on the growth form types and also on the phenological stage; c) extreme events can overwhelm the effect of photoperiod, and can lead to carry over effects in the phenological cycle and plant growth.
Our data indicated that the main predictor of the vegetative development stages was the snow melt, while the photoperiod was the best predictor of phenological stages from flowering peak up to leaf senescence. Therefore, the photoperiodic control on alpine plant phenology should be considered for the evaluation and modelling of the impacts of climate change in alpine region, not only concerning the reproductive stages, but also for the leaf senescence. This constitute a novelty concerning literature data about phenology of alpine plants (which have been always related to snow and/or temperature as triggering factors) because provides new insights on the capability of alpine plants to profit of potential future autumn warming.
Alpine plant phenology showed thus a strong conservative strategy, which differed among growth forms, according to our hypothesis. Over all the investigated phenological stages graminoids were the most plastic and responsive growth form and their higher adaptation capability could help to explain why this growth form is expanding more than forbs in alpine and Polar tundra habitats.
Extreme events showed impact on plant phenology, with differences among growth forms and phenological stage. In particular, we found the leaf senescence of herbaceous species to be highly sensitive to the combination of drought and heat, which led to an advance of almost one month in the season, while deciduous shrubs were not or less sensitive. Moreover, an extreme leaf senescence showed carry over effects on the next season growth rate.
Our results indicate also a statistically significant increase of the height of evergreen shrubs on the period 2010-2016, which was in agreement with the observed range expansion of shrubs in the Alps.
Relating to the long-term ground surface temperature (GST) monitoring, 13 temperature data loggers were installed in the Foscagno valley, under different surface types conditions, covering the most widespread growth forms of the area. In particular, we hypothesized that: a) GST was strongly influenced by the soil coverage types and snow cover, b) although the actual climatic conditions are less favorable, some vegetated soils could lead a ground cooling until to permafrost condition; c) the shrubland expansion could drive to an energetic disequilibrium of soils with thus positive feedbacks on the carbon cycle.
Our data confirmed that the snow cover duration was the main driver of the mean annual ground surface temperature, while the beginning of snow cover deeper than 80 cm influenced the freezing state of the soils during winter, and the timing of snow melt was related to the thawing degree days of the snow free period. Vegetated soils (shrublands and grasslands surface types) were warmer compared to bare ground, except for pioneer species (i.e. Cerastium uniflorum), that involved a cooling on soils leading to permafrost condition. Therefore, future changes in vegetation cover can lead to different soil thermal regimes and different spatial distribution of temperatures in alpine terrains. Potentially, the expansion of pioneer species could be related to longer persistence of permafrost conditions; on the contrary, if the shrublands expansion that we are facing in the Alps will continue in the future, soil temperatures will be warmer, which imply positive feedbacks to the carbon cycle.
The main purpose of the manipulation experiments started at the Foscagno Valley in 2015 was to investigate the responses of phenology and plant growth under different simulations of climate change. As many phenophases exhibited a strong photoperiodic control, we aimed to assess and quantify the eventual effects of the different manipulation treatments and identify the most responsive phenophases and communities types. Concerning the quantitative development, we hypothesized that: a) the vegetative development (shoot length, leaf length, maximum plant height) would be influenced by manipulations, with nutrients exerting the higher impacts, compared to flower removal and water addition (since terrestrial ecosystems are N and P limited); b) the above ground biomass (ABG) would be strongly influenced by the addition of nutrients, more than flowers removal or water addition.
Our data showed that manipulation experiments (in particular nutrient additions) involved strong impacts on plant phenology and growth, lengthening (with xNPK) or shortening (with ammonium sulfate) the duration of flowering and leaf senescence, and enhancing the vegetative quantitative phenology of alpine plants (with xNPK). One of the most important findings is that the photoperiodic limitation observed at the long-term phenology monitoring, could be overcome under future climate changes, with potentially consequences on niche competition within communities.
Above all the manipulation we found a strong N and P limitation, in particular concerning the vegetative development, which thus will imply strong consequences also on the carbon budget. Also the flower removal exerted visible effects especially on the quantitative growth, highlighting differences among the vegetation communities, with higher capability for snowbeds species to remobilize nutrients than grasslands species.
Another feedback of the manipulations experiments concerned the occurrence of carry over effects on the quantitative growth of the first shooting stage at the beginning of the season, provided by the enhanced nutrient availability from the previous year.
While in the alpine tundra vascular plants are dominant, in high latitude ecosystems, cryptogams (mosses and lichens) are the major components of terrestrial ecosystems. In particular, in Antarctica only few long-term data are available on the responses of mosses and lichens to climate change.
Comparable to Alps, the Maritime Antarctica is one of the regions of the planet recording the most rapid air warming, and Signy Island (South Orkney Islands) has been identified as a suitable context for the monitoring of biological changes. Here we analyzed the contemporary abundance and distribution of moss banks on the entire island, assessing their ecological requirements, and providing thus a baseline for future monitoring.
Thanks to the availability of previous field-based studies on the spatial distribution of moss banks carried out in the 1960s and 1970s, we assessed long-term and large-scale moss responses to climate change underlying the related ecological processes.
Differently to Alps and Maritime Antarctica, Continental Antarctica in the last 50 years showed a stable air temperature trend. This region is the last pristine environment on Earth, which provides a unique opportunity to assess the natural dynamics and responses to climate. In Victoria Land, in 2002 started a long-term monitoring project of the climate, permafrost and vegetation, of which we present here the results after 10 years of monitoring. Concerning this activity, we aim to: a) identify the patterns of spatial and temporal active layer variability; b) analyze the changes of the associated vegetation; c) identify the climatic forcing of active layer and vegetation changes.
In the Antarctic summer 2014/2015, we installed over a latitudinal gradient (73-77°S) in Victoria Land, some manipulation experiments (additions of snow, water, urea, ammonium sulfate, NPK, guano respectively) coupled with the manipulation of snow accumulation, soil temperature and precipitation (installing respectively snow fences, open top chambers and snow shield) for the simulation of potential future climate change impacts. We thus briefly evaluated the effects on soil temperatures after the first year of the experiments, providing thus the start point for future further monitoring.
Among all the experiments, we found that the snow cover exerted the largest effect on the GST, thus highlighting its main role in regulating soil temperatures, which effects overcome the influence of air temperature, leading also to changes of soil moisture and water regim