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Thermal waters near the city of Viterbo (Central Italy) are known to show high As contents (up to 600 µg/l). Travertine is precipitated by these waters, forming extended plateau. In this study, we determine the As content, speciation and bioaccessibility in soil and travertine samples collected near a recreational area highly frequented by local inhabitants and tourists to investigate the risk of As exposure through accidental ingestion of soil particles. (Pseudo)total contents in the studied soils range from 17 to 528 mg/kg, being higher in soil developed on a travertine substrate (197 ± 127 mg/kg) than on volcanic rocks (37 ± 13 mg/kg). In travertines, most As is bound to the carbonatic fraction, whereas in soil the semimetal is mostly associated with the oxide and residual fractions. Accordingly, bioaccessibility (defined here by the simplified bioaccessibility extraction test, SBET; Oomen et al., 2002.) is maximum (up to 139 mg/kg) for soil developed on a travertine substrate, indicating a control of calcite dissolution on As bioaccessibility. On the other hand, risk analysis suggests a moderate carcinogenic risk associated with accidental soil ingestion, while dermal contact is negligible. By contrast, ingestion of thermal water implies a higher carcinogenic and systemic health risk.

The terrestrial environment is an important contributor of microplastics (MPs) to the oceans. Urban streams, strictly interwoven in the city network and to the MPs’ terrestrial source, have a relevant impact on the MP budget of large rivers and, in turn, marine areas. We investigated the fluxes (items/day) of MPs and natural fibers of Mugnone Creek, a small stream crossing the highly urbanized landscape of Florence (Italy) and ending in the Arno River (and eventually to the Tyrrhenian Sea). Measurements were done in dry and wet seasons for two years (2019–2020); stream sediments were also collected in 2019. The highest loads of anthropogenic particles were observed in the 2019 wet season (109 items/day) at the creek outlet. The number of items in sediments increased from upstream (500 items/kg) to urban sites (1540 items/kg). Fibers were the dominant shape class; they were mostly cellulosic in composition. Among synthetic items, fragments of butadiene-styrene (SBR), indicative of tire wear, were observed. Domestic wastewater discharge and vehicular traffic are important sources of pollution for Mugnone Creek, especially during rain events. The study of small creeks is of pivotal importance to limit the availability of MPs in the environment.

The area between the Asco and Golo valleys in Central Corsica, France (latitudes 42°47′95″N to 42°37′96″N, longitudes from 9°11′82″E to 9°20′72″E) is a key-sector to investigate the stratigraphic and tectonic setting of Alpine Corsica. This sector includes (from the structurally lowest to the highest) the Hercynian Corsica, that represents the European continental margin not deeply involved in the convergence processes, and a stack of oceanic and continental units belonging to the Alpine Corsica, i.e. the domain strongly affected by the Alpine deformation and metamorphism in the Late Cretaceous-Paleogene. The 1:15,000 scale geological map illustrates the tectonic features of Alpine Corsica stack with a special focus to the Lower Units, the units derived from the European thinned continental margin involved in the Alpine convergence.

This paper reports the results of a joint project carried out by three regional environmental agencies of Italy to evaluate long-range mercury (Hg) transport from the abandoned Mt. Amiata Hg district in southern Tuscany (the third largest worldwide site for Hg production) to the fluvial ecosystems of the Paglia and Tiber rivers. Most of the work focused on stream sediments, surface waters and soils. A preliminary survey of Hg0 content in air was also conducted. Data obtained by public health authorities on Hg in vegetables and fish were also included. The highest Hg concentrations (up to thousands of μg/g Hg) were observed in stream sediments and soils directly impacted by Hg mine runoff. Although progressive Hg dilution was observed from north to south along the river, sediments and soils show anomalous Hg levels for over 200 km downstream of Mt. Amiata, testifying to an extreme case of long-range Hg contamination. A pervasive redistribution of Hg is observed in all sediment compartments. Presumably, the width of the impacted fluvial corridor corresponds to the entire alluvial plains of the rivers. The floodplains can be considered new sources for downstream Hg redistribution, especially during large flood events. On the other hand, results from water, air, and vegetable sampling indicate low potential for human exposure to Hg. The extent and distribution of the contamination make remediation not viable. Therefore, people and human activities must coexist with such an anomaly. On the technical side, the most urgent action to be taken is a better definition of the exact extent of the contaminated area. On the management side, it is necessary to identify which public institution(s) can best deal with such a widespread phenomenon. According to the precautionary principle, the impact of the contamination on human activities in the affected areas should be considered.

Spinal muscular atrophy (SMA) is a neuromuscular disorder and one of the most common genetic causes of infant mortality. The disease is characterized by a selective degeneration of lower spinal cord motor neurons, which leads to progressive muscle atrophy and death. SMA is caused by mutations of the survival of motor neuron gene, Smn1, which is ubiquitously expressed. Although the genetic bases of SMA have been extensively studied, it is still unknown how the absence of Smn1 induces the selective degeneration of motor neurons, and which are the molecular mechanisms that underlie the disease. This contributes to the lack of an effective treatment being developed. Unbiased chemical screens can be performed in vivo using small animal model organisms, and contribute to identify potential therapeutic compounds as well as elucidate the molecular basis of the disease. In C.elegans two SMA models have been developed by classical genetic approaches: the smn-1(ok355) null mutant (Briese et al., Hum. Mol. Gen. 2009), in which the loss of smn-1 produces pleiotropic phenotypes and lethality, and the smn-1(cb131) hypomorphic mutant (Sleigh et al., Hum. Mol. Gen. 2010), which displays similar but milder defects. However no morphological alteration in the nervous system and no variations in the number of motor neurons have been detected in these genetic mutants. The hypomorphic mutant has been used to screen a chemical library and has led to the identification of some compounds capable of improving at least one of the disease phenotypes of the model. In order to find molecules with a protective role against the neurodegeneration caused by smn-1 loss, we took advantage of a genetic model developed in our laboratory, which is based on neuron-specific RNAi of smn-1 (Esposito et al., Gene 2007). Transgenic strains in which smn-1 is knocked down specifically in the GABAergic motor neurons present an age-dependent neurodegeneration, which results in altered backward movement and in neuronal cell death. Importantly, these animals are viable and fertile allowing us to overcome the lethality problem related to the other C.elegans SMA model carrying smn-1 loss of function. We initially tested on this model a panel of chemical compounds that were selected based on their known function. We have confirmed that valproic acid, a compound successfully used also in mice SMA models (Seo et al., Biochim. Biophys. Acta, 2013), can partially prevent neuronal death in C. elegans. Then, we found that the Ca2+-chelating agent EGTA has a protective function on neurodegeneration, suggesting that Ca2+ plays a role in smn-1-induced GABAergic cell death. Moreover, we have tested the effects of natural compounds and have obtained interesting results with juices of broccoli sprouts, which are currently under characterization. Finally, we are setting up the conditions to carry out an automated screen of a chemical library, consisting of 1280 FDA-approved compounds.

Plants have evolved sophisticated mechanisms to sense the presence of other plants growing nearby and adjust their growth rate accordingly. The early perception of neighbor proximity depends on the detection of light quality changes. Within a vegetation community, the ratio of red (R) to far-red (FR) light is lowered by the absorption of R light by photosynthetic pigments. This light quality change is perceived through phytochrome (phyB, phyD and phyE in Arabidopsis) as a signal of the proximity of neighbors, and induces a suite of developmental responses (termed the shade avoidance response). In Arabidopsis shade avoidance is regulated by a balance of positive (PIF) and negative (HFR1/SICS1) regulators of gene expression which ensures a fast reshaping of the plant body towards an environment optimal for growth while at the same time avoiding an exaggerated reaction to low R/FR. Persistency of a low R/FR signal enhances the activity of phyA and, in turn, of HY5, a master regulator of seedling de-etiolation. Several hormones, such as gibberellins and brassinosteroids have been implicated in shade-induced elongation. However, a compelling amount of evidence indicates that low R/FR-induced changes in auxin homeostasis and auxin transport are central in the shade avoidance response. This chapter describes the recent advances in understanding how auxin coordinates plant growth in a low R/FR light environment.

The success of competitive interactions between plants determines the chance of survival of individuals and eventually of whole plant species. Shade-tolerant plants have adapted their photosynthesis to function optimally under low light conditions. These plants are therefore capable of long-term survival under a canopy shade. In contrast, shade-avoiding plants adapt their growth to perceive maximum sunlight and therefore rapidly dominate gaps in a canopy. Daylight contains roughly equal proportions of red (R) and far-red (FR) light, but within vegetation that ratio is lowered as a result of R absorption by photosynthetic pigments. This light quality change is perceived through the phytochrome system as an unambiguous signal of the proximity of neighbours resulting in the shade avoidance response. This adaptive reaction is achieved by a set of responses including enhanced internode and petiole extension growth, increased apical dominance, retarded leaf development, and an acceleration of flowering. Genomic and genetic analyses by a number of laboratories including ours have identified several low R/FR regulated genes and key regulators involved in the shade avoidance response. However, very little is known about the cascade of events triggered by low R/FR that give rise to full activation of the response and eventually lead to adaptation to an unfavourable light environment. By combining genome-wide experimental and computational analyses in wild type and genetically altered plants exposed to low R/FR light for different times, we identified novel regulatory circuits controlling plant adaptation to canopy shade.

In the last decades several genes that regulate abiotic stress response were identified in the model plant Arabidopsis. The completion of the Arabidopsis genome sequence in 2000, and the development of molecular high throughput 'omics' platforms that allow the processing of several samples has speed up the simultaneous functional characterization of genes that regulate the abiotic stress tolerance in plants. The fundamental molecular mechanisms that underlie the plant abiotic responses are quite conserved among plant species therefore the knowledge gained in the model plant Arabidopsis can be exploited to improve stress tolerance in crop plants. Many examples demonstrate that ectopic expression of key genes involved in the stress response can induce stress tolerance in different crops demonstrating the potential of the translational approaches. Nevertheless the generation of crops that have improved tolerance in field conditions is still a challenge. However the omics approach in crop species can certainly contribute in the understanding of the interplay between response pathways to different abiotic stresses, condition that is found in typical open fields.

A plant growing in the field has the unique ability to sense the presence of other plants growing nearby and adjust its growth rate accordingly. The early perception of neighbour proximity depends on the detection of light quality changes. Within a vegetation community, the ratio of red (R) to far-red (FR) light is lowered by the absorption of R light by photosynthetic pigments. This light quality change is perceived through the phytochrome system as an unambiguous signal of the proximity of neighbours, and induces a suite of developmental responses (termed the shade avoidance response) that, when successful, result in the overgrowth of those neighbours. The shade avoidance response is a strategy of major adaptive significance to plants in natural communities. However, since elongation is often achieved at the expense of leaf and root growth, and, in the long term, low R/FR exposure leads to early flowering with a reduced seed set, shade avoidance can significantly impact yield in high-density crop plantings. Work performed by several laboratories, including ours, identified several key transcription factor genes that underpin shade avoidance and uncovered complex molecular interactions between low R/FR light and hormone signalling pathways. Among hormones, auxin seems to have a central role in several aspects of shade avoidance response. Many lines of evidence connect this hormone to the rapid elongation response provoked by light quality changes. Furthermore, our recent work establishes that auxin plays a pivotal role in leaf and root responses to low R/FR as well, suggesting that this hormone may act as a coordinator of plant growth responses to environmental light quality changes. Shade avoidance is a highly dynamic response. If the plant succeeds in the attempt to overgrow its neighbours and the photosynthetic organs perceive daylight again, the shade avoidance response is rapidly reverted through phytochrome photoconversion. On the other hand, persistent low R/FR signalling triggers mechanisms that prevent an exaggerated reaction when the plant is unsuccessful in escaping canopy shade. HFR1/SICS1, a bHLH transcription factor, plays a central role in the attenuation of virtually all plant responses to canopy shade. Our recent data demonstrate that HFR1/SICS1 functions in the phyB signal transduction pathway, and acts in concert with other transcription factors modulated through phyA in the adaptation of the plant to low R/FR environments.

The shade avoidance response is a strategy of major adaptive significance to plants in natural communities. It is highly widespread in the angiosperms, and depends on the ability of the plant to perceive the presence of neighbors. Within vegetation, the ratio of red to far-red (R/FR) is lowered by the absorption of R light by photosynthetic pigments. This light quality change is perceived through the phytochrome system as an unambiguous signal of the proximity of neighbors. Upon sensing a low R/FR ratio, a shade-avoiding plant reacts very rapidly and enhances elongation growth even before it is directly shaded. If the plant succeeds in the attempt to overgrow its neighbors and the photosynthetic organs perceive daylight again, the shade avoidance response is rapidly reverted through phytochrome photoconversion. Consistent with the rapidity of plant response to low R/FR and its reversibility upon perception of high R/FR, changes in gene expression are rapid and reversible. The transcript level of the Arabidopsis HD-Zip ATHB2 and bHLH PIL1 transcription factor genes, functionally implicated in shade avoidance response, increases within a few minutes of low R/FR exposure. Significantly, ATHB2 and PIL1 transcript levels fall very rapidly after transfer from low to high R/FR. Low R/FR also provokes a rapid induction of the Arabidopsis HFR1/SICS1 gene, a negative controller of the shade avoidance response, ensuring that an exaggerated reaction does not occur when the plant is unsuccessful in escaping canopy shade. In this unfavorable environmental condition, HFR1/SICS1 is likely to play a fundamental role in the acclimation of the plant, and by delaying flowering, to ensure a better seed production needed for long term survival. Recent work revealed that the same low R/FR signal that induces hypocotyl elongation also triggers a rapid arrest of leaf primordium growth ensuring that plant resources are redirected into extension growth. The growth arrest induced by low R/FR depends on auxin-induced cytokinin breakdown in incipient vein cells of developing primordia, thus demonstrating the existence of a previously unrecognized regulatory circuit underlying plant response to canopy shade.

The Arabidopsis homeobox gene ATHB-2 is tightly regulated by light signals, and is thought to direct morphological changes during shade avoidance responses. To understand how ATHB-2 mediates light signals in plant morphogenesis, we investigated its transcriptional network. We constructed a gene encoding a chimeric transcription factor (HD-Zip-2-V-G) that is expected to activate target genes of ATHB-2 in a glucocorticoid-dependent manner. In transgenic Arabidopsis plants expressing HD-Zip-2-V-G, glucocorticoid treatment activates the ATHB-2 gene itself, independent of de novo protein synthesis. An in vitro DNase I-footprinting experiment showed that recombinant ATHB-2 protein specifically bound to an ATHB-2 promoter region. These complementary results indicate that ATHB-2 recognizes its own promoter. Consistent with the fact that ATHB-2 itself has been shown to act as a repressor, expression of the endogenous ATHB-2 gene was repressed in transgenic plants overexpressing an ATHB-2 transgene. Moreover, target-gene analysis using the HD-Zip-2-V-G suggested that ATHB-2 recognizes other HD-Zip II subfamily genes. We conclude that ATHB-2 has a negative autoregulatory loop and may be involved in a complicated transcriptional network involving paralogous genes, as in the case with animal homeobox genes.