114 research outputs found
The role of Phytochelatin Synthase in the microalga Scenedesmus acutus M. (Sphaeropleales).
No full textThe role of Phytochelatin Synthase in the microalga Scenedesmus acutus M. (Sphaeropleales)
M. Ferrari, R. Cozza, M. Marieschi, R. Ruotolo, A. Torelli
Phytochelatins (PCs) are small cysteine-rich peptides that are not genetically encoded but are synthesized by Phytochelatin Synthase (PCS) in the presence of glutathione as substrate. The constitutive expression of PCS and the presence of homologues of the PCS gene(s) in plants growing in ecosystems geographically remote from metal-contaminated sites, as well as in representatives of various kingdoms of living organisms, suggest that PCS has a wide range of different functions (Clemens et al. 2009). However, the main function of PCs in plants is to immobilize, sequester, and detoxify metal ions (Shukla et al. 2013). The effect of metals on the activity of PCS can differ not only between species, but also between different isoforms of the enzyme within a species.
Although it is evident that chromium (Cr) ions can stimulate the formation of PCs in plants (Yu et al. 2018), there is no information on their presence in algae in response to Cr exposure.
In this study, two strains of the green alga Scenedesmus acutus with different Cr(VI) sensitivity, namely the wild type (wt) and the chromium-tolerant strain (Cr-t), were selected as a model algal species to increase the knowledge on the role of PCs in Cr responses in microalgae.
We previously reported the first evidence for a PCS gene (SaPCS) from the microalga S. acutus. More recently, we have also identified two SaPCS isoforms due to a putative alternative splicing.
To define the role of PCS in Cr detoxification, we analyzed the levels of SaPCS transcription, and the abundance of PCS by using RT-qPCR and Western blot, respectively, in both strains of S. acutus after 24h culture in standard and in Cr supplemented medium (1 and 2 mg Cr (VI)/l).
Given the relationship between sulfur (S) metabolism and Cr(VI) tolerance in S. acutus (Sardella et al. 2019), we also performed the same analyses in S-replete cells of both strains after medium renewal following S-starvation.
The results showed a different behavior between strains in the stress response. RT-qPCR analysis revealed an increase in SaPCS transcription after Cr(VI) stress and after medium renewal following S-starvation in wt cells. Instead, the Cr-t strain induced SaPCS transcription only under S-replete conditions.
Western blot analysis, performed with a polyclonal antibody raised against PCS of Arabidopsis thaliana, revealed an immunoreaction signal on two proteins with molecular weights of approximately 73 and 37 kDa. While the abundance of the 73 kDa protein did not change after the stresses studied in the two strains, the 37 kDa protein increased after S-starvation in both strains but in a significant manner only in wt.
Finally, a preliminary quantification of PC production was performed, through LC Mass analysis in the two strains in preculture with or without S and under 1 mg Cr(VI)/l, which showed no modulation of PC abundance in response to Cr(VI) stress and/or S deprivation. Nevertheless, the Cr-t strain maintained PCs level significantly higher than the wt at the end of S-starvation.
These observations suggest that PCS in S. acutus may not be involved in Cr(VI) detoxification, but may play a role in intracellular sulfur balance or in the cell homeostasis during stress.
The PC production in the other experimental conditions (i.e. exposures longer than those studied and different Cr(VI) concentrations) should be investigated to better clarify the role of the enzyme in Cr(VI) detoxification.
Letteratura citata
Shukla D., Tiwari M., Tripathi E.D., Nath P., Trivedi P.K. (2013). Synthetic phytochelatins complement a phytochelatin-deficient Arabidopsis mutant and enhance the accumulation of heavy metal(loid)s. Biochem Biophy Res Commun 434:664–669
Clemens S., Peršoh D. (2009). Multi-tasking phytochelatin synthases. Plant Sci., 177, 266–271.
Yu, X.Z., Ling, Q.L., Li, Y.H., Lin Y.J. (2018) mRNA Analysis of Genes Encoded with Phytochelatin Synthase (PCS) in Rice Seedlings Exposed to Chromium: The Role of Phytochelatins in Cr Detoxification. Bull Environ Contam Toxicol 101, 257–261.
Sardella A., Marieschi M., Mercatali I., Zanni C., Gorbi G., Torelli A. (2019). The relationship between sulfur metabolism and tolerance of hexavalent chromium in Scenedesmus acutus (Spheropleales): Role of ATP sulfurylase. Aquatic Toxicology, 216:105320.
AUTORI
Michele Ferrari ([email protected]), Radiana Cozza, Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci, 87036 Rende (CS).
Matteo Marieschi, Roberta Ruotolo, Anna Torelli, Department of Life Sciences, University of Parma, Parco Area delle Scienze 11/A, 43124 Parm
A Need For Change. Vienna, a Performative Beauty
No full textCities’ actual and future livability – including healthiness and life quality – depends on their preparedness to tackle climate change and biodiversity loss, crucial issues of the Anthropocene. Contemporary open spaces need design actions for new aesthetics capable of conveying values through architecture by combining spatial quality, environmental performance, and sociality.
The city of Vienna is one of the European best practices with a long pioneering tradition in promoting holistic planning and project design actions capable of guiding design choices with a multidisciplinary approach.
Esterházy-Park is representative of this city’s capability; it is a public park with a long history and a complex inclusive pro-gramme of uses, located in Mariahilf –in the sixth district
Children Architectures. Spaces for discovering and caring inhabited by different and changing corporealities
No full textContemporary children’s architectures, like kindergartens, must be conceived on specific
requirements dictated by different and changing corporealities. Indeed, children have bodies
that are continuously changing due to the growth process; they are active users of architecture,
exploring space with their bodies, improving their autonomy and competencies, and needing
care and discreet protection. Moreover, these spaces host the co-presence of different bodies:
the children of various ages and the adults who form the school community inhabiting the
same spaces due to their different roles (educators, employees, parents, and so on). A bodycentred
approach to the architectural design of children architectures can lead to learning
environments based on updated pedagogical requirements, respecting the different needs and
measures of the various users.
A body-centred approach to architecture is necessary for children’s architecture because of the peculiarity of their fast-growing corporeality and peculiar capability to establish spatial relationships with the environments that they inhabit. The simultaneous presence of the adults in the same spaces implies dealing with different measures, scales and points of view. Although these spaces’ design is body-centred, digital media can provide helpful information to facilitate their livability and accessibility, especially in public spaces
Ethics of Engagement in Research Practices. Response-ability in Organization and Management
No full textThe book asks how it would work to do research in organization and management in ways which are not only accountable (responsible) but also responsive (response-able). In dialogue with the Routledge Focus on Women Writers in Organization Studies series, this book honours the work of the ‘founding mothers’ of care theory and research who have contributed to developing the concept of response-ability - the capacity to respond and render each other capable to respond - in particular, Joan Tronto, Donna Haraway, Vinciane Despret, and Karen Barad. The chapters in this book entwine theory and practice in exploring the concept of response-ability by interlacing the contributions of such scholars, rather than treating them separately, and bringing them into organization and management studies. The authors in this book call for changes to the ways that research happens in terms of the ethical sensibilities which emanate from ‘becoming-with-others’ not only within a project-oriented timeframe but in everyday academic practices. The book is an invitation to students, researchers, and practitioners to find ways of embodying response-ability while engaging with multiple others in generating knowledge
An Italian Study on Gender and Management in Science and IT
No full textThis study concerns the distribution of women and men in an Italian research Centre active in areas of Information Technologies (IT), Microsystems, and Physical Chemistry of Surfaces and Interfaces.Its purpose is: first, to verify if the involvement of women and men is different in physics-oriented and computer science-oriented departments; second, to identify reasons of differences in the distribution of women and men in same area departments that could be brought back to human resources management practices.Design/methodology/approach In the first analysis, sex-disaggregated data from 1990 to 2004 are considered with respect to contract level and duration, departments and women’s educational qualifications.The second analysis adopts a qualitative approach based on interviews to heads of two departments and follows Acker’s gendering organizational theory.FindingsThis first analysis points out that data do not give support for a different areas dichotomy, but rather for differences on the number of women employed between same area departments.The second analysis points out that these differences are partly explained by the combination of bottom up processes in the recruitment and the presence/absence of a core group of women.Research limitations/implications A further analysis on researchers’ educational path is necessary to support a deeper explanation on women/men distribution and eventually to confirm its roots in a cultural bias on the choice of professional studies and carriers.What is original/value of paperIt synthesizes a quantitative and a qualitative approach. The presentation of sex-disaggregated data and of managerial practices of gendering contributes to literature about women’s participation in Science, Engineering and Technology (SET)
Annibale è passato da qui. La (ri)produzione del passato tra archeologia e storia locale
No full textIl testo ripercorre le vicende bio-bibliografiche di un erudito locale alle prese con la ricostruzione archeologica a metà tra il mito e la storiografia
Introduction. Ethics of Engagement in Research Practices: Response-ability in Organization and Management
No full textThe chapter provides a cartographic reading of "response-ability' and honours the work of the ‘founding mothers’ of care theory and research who have contributed to developing this concept. We use the cartographic approach to elaborate on response-ability in academia by articulating some of the practices that enable responsiveness and attentiveness in management and organization studies (MOS). We then move across and beyondnacademia, where MOS researchers encapsulate response‐ability into worldmaking practices that shake the ‘ivory tower.’ We end this introduction by
navigating through the chapters to provide an overview of the book
Ultrastructural features, chromium content and methylation pattern in two strains of Scenedesmus acutus M. (Chlorophyceae) with different chromium sensitivity.
No full textUltrastructural features, chromium content and in situ immunodetection of the 5-methylcytosine following Cr (VI) treatment in two strains of Scenedesmus acutus M. (Chlorophyceae) with different chromium sensitivity
No full textTwo strains of the unicellular green alga Scenedesmus acutus (F.J.F. Meyen) with different sensitivity to chromium (VI) were compared to evaluate their ultrastructural morphology in chromium-free and -supplemented medium with a sub-lethal concentration of Cr(VI) for 72 hours. The ultrastructural alteration in different cytological compartments indicated that Cr(VI) induced earlier and stronger alterations in the wild type (wt) compared with the chromium-tolerant strain (Cr-t). After Cr treatments, ICPMS (Inductively Coupled Plasma Mass Spectrometry) showed a higher Cr accumulation in the wild type than in the Cr-tolerant strain, suggesting a more efficient chromium-exclusion mechanism in the latter. The Cr treatment induced an increase in the nuclear area and a rearrangement in the eu-heterochromatic fraction, suggesting that chromatin remodelling could be at the basis of differential gene expression and metal tolerance. To gain additional information on the remodelling of the nuclear chromatin, we analysed DNA methylation by immunolocalization of 5-methyl-cytosine, before and after Cr exposure. Significant differences in the quantification of the immunolabelling of DNA cytosine-rich zones between the two strains were observed. These data suggest that an epigenetic mechanism could be at the basis of the Cr tolerance in S. acutus, as supported by previous data reporting that the acquired tolerance was inherited and maintained through the progeny
A putative metallothionein from the microalga Scenedesmus acutus (Chlorophiceae).
No full textMicroalgae are predominantly aquatic organisms that must be able to discriminate between essential and non-essential heavy metal ions. In addition, they must maintain non-toxic concentrations of these ions inside their cells. In this way, two principal mechanisms have been identified, one which prevents the indiscriminate entrance of heavy metal ions into the cell (i.e., exclusion) and the other which prevents bioavailability of these toxic ions once inside the cell (i.e., the formation of complexes). The molecules responsible for the first mechanism are extra-cellular polymers, mainly carbohydrates; those responsible for the second are essentially the two type metal-chelating peptides: enzymatically synthesized phytochelatins (PCs- class III metallothioneins -MtIII), and gene-encoded metallothioneins (MTs) (1).
MTs are low molecular weight, cysteine-rich metal chelators with an ability to bind heavy metal ions through metal-thiolate bonds. In addition, the thiol(ate)s in MTs can act as powerful antioxidants, and hence MTs may have roles in protection against oxidative stress (2). Mts are widely distributed in animals, plants, fungi as well as cyanobacteria. Plant MTs (pMTs) are considerably longer than their animal counterparts owing to the exclusive presence of a 30-50 residue-long, Cys-devoid region, between the N- and C-terminal Cys-rich domains (four to eight Cys each). Specifically, the distribution of the Cys residues and the length of the spacer region have been used to further classify plant MTs into four subtypes (3, 4).
Currently, pMTs have been extensively identified as a multigenic family in angiosperms (A. thaliana as a model) (3), in gymnosperms (5) and in macroalgae (Fucus) (6), constituting family 15 of the global MTs Kägi classification (7). To date, no evidences of genes encoding Mts in microalgae are reported, although the induction of cadmium-binding MT-like protein has been found in the unicellular algae Chlamidomonas sorokiniana (8) and Chlamidomonas vulgaris (9).
In this work we reported the first evidence of a Mts gene from the microalga Scenedesmus acutus. In the case of the heavy metal tolerance of S. acutus, previous data report the implication of reduced glutathione (GSH) and Phytochelatins-MtIII as the molecular mechanism underlying the Cd tolerance (10).
By RT-PCR amplification approach using degenerate primers, we amplified a full length cDNA of 280 bp sharing high identity with plant metallothioneins. The deduced protein consisted of 91 residues (mol wt of 9,2kDa) which contains 8 Cys residues arranged in CXC and CXXC motifs and showing a high identity homology (89%-98%) with other type2 Mts of the Silene genus. Despite this, the primary structures of Scenedesmus acutus MTs ( named ScaMT) shows some differences with the canonical pMts type 2 which relate it to an archetypal Type 2 sequences from other pMTs members. So, the evidence that ScaMT sequences shows similarity to Types 2 is a phylogenetically important finding and supports both the existence of a common ancestral metallothionein and its diversification at a point after the evolution of Chlorophyta and Streptophyta lineage. Work is in progress in order to define the genomic feature of ScaMT gene and its functional role (response to different heavy metals and/or stress condition). The results will also elucidate the different implications of the two type of heavy metal binding peptides (enzyme and encoding synthesized) in S. acutus in order to better understand the metal tolerance and/or the bioaccumulation mechanisms in this microalga. These molecular mechanism would be potential engineerized to improve the algal phytoremediation performance.
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