1,531 research outputs found
«A volte siamo due pietre che fanno scintille»
No full textQuesta nota prende le mosse dal lavoro di René Roussillon sul tema della simbolizzazione primaria. L’autore si interroga sui modi in cui l’oggetto può assumere una funzione simbolizzante e si focalizza su una situazione specifica: quella in cui l’oggetto-analista si assenta emotivamente dal paziente, se ne accorge e inizia a rappresentare dentro di sé la propria assenza per l’altro. Secondo questa prospettiva lo sviluppo dell’attività simbolica sarebbe favorito dall’introiezione di questa funzione rappresentativa dell’oggetto.This note is based on the work of René Roussillon on the theme of primary symbolisation. The author questions the ways in which the object can assume a symbolizing function and focuses on a specific situation: the one in which the analyst-object is emotionally absent from the patient, realizes it and begins to represent within himself his own absence for the other. According to this pro-perspective, the development of symbolic activity would be favoured by the introjection of this rap-representative function of the object
A combined microscopy approach to study plant-phytoplasma interaction using Arabidopsis thaliana.
No full textPhytoplasmas, obligate parasites of plants and phloem-feeding insects, belong to Mollicutes (Lee et al., 2004) and are associated with several hundreds of diseases affecting over one thousand plant species, including many economically important crops (Marcone, 2014). There is no effective curative strategy available so far, so the sole ways to limit the infection outbreaks are the use of insecticides and the removal of symptomatic plants (Bertaccini et al., 2014).
Even if not all infections are necessarily deleterious, symptoms in infected plants suggest heavy disorders of phloem functions and growth-regulator balancing (Lee et al., 2000). Upon their discovery (Doi et al., 1967), the study of phytoplasmas has been hindered by the extreme difficulty to culture them in vitro, due to their lack of fundamental metabolic pathways (Bai et al., 2006). Moreover, the study in natural plant hosts is often limited by environmental conditions, long plant life cycle and poor knowledge of host-plant biology. Therefore, in the last decade some authors suggested to use Arabidopsis thaliana as model plant for studying phytoplasma-plant interactions. This choice was supported by the correspondence between the macroscopic symptoms developed in infected A. thaliana and those observed in natural host plants (Bressan and Purcell, 2005; Hoshi et al., 2009; Cettul and Firrao, 2011; MacLean et al., 2011). Nevertheless, morphological and ultrastructural modifications occurring in infected A. thaliana tissues have never been described in detail.
In this work, we adopted a combined microscopy approach to verify if this plant is a reliable model for the study of phytoplasma-plant interactions at microscopical level.
Using DAPI and fluorescence microscopy (FM), phytoplasma presence and localization were demonstrated in every infected plant. Transmission electron microscopy (TEM) observations confirmed phytoplasma massive presence into the sieve elements (SEs) (Figure 1). Phytoplasma appeared well preserved, with typical pleomorphic shape, free-floating and dividing in the lumen or adhered to SE membrane, probably connecting to the host (Marcone et al., 2014; Buxa et al., 2015). Phytoplasmas also established relationships with sieve element reticulum (SER). Pathogen presence, probably linked to nutrient uptake (Celli et al., 2015; Musetti et al., 2016), caused SER hyperproliferation, as observed in many other plant-phytoplasma interaction (Rudzinska-Langwald and Kaminska, 2001; Buxa et al., 2015) (Figure 1). Pathogen spread was documented by the passage through sieve pores.
As remarked above, phytoplasma presence affected host plant development (Lee et al., 2000). In infected A. thaliana plants, light microscopy (LM) evidenced a profound disturbance in phloem morphology at histological level, mainly consisting in collapse, necrosis and hyperplasia of the phloem components. The relationship between necrosis and hyperplasia could be explained as a plant response to the impaired phloem functionality (Oshima et al., 2001) or due to pathogen effectors (Bai et al., 2009; Sugio et al., 2011).
At ultrastructural level, as previously observed in other phytoplasma hosts (Musetti et al., 2000; 2013; Kaminska et al., 2001; Santi et al., 2013), phloem components showed plasmolysis or were collapsed or necrotized. Even in vital SEs, abnormalities of cell membrane profile and cell wall thickness were visible. TEM observations showed two typical plant responses to phytoplasma infection: phloem-protein agglutination and callose deposition at the sieve plates, which limited sieve-pore diameter (Figure 1). These phenomena have been interpreted as a plant reaction to physically limit pathogen spread (Lherminier et al., 2003; Gamalero et al., 2010; Luna et al., 2011; Musetti et al., 2010; 2013).
Phloem functionality experiments using CFDA and confocal laser scanner microscopy (CLSM) suggested that sieve-pore obstruction leads to phloem impairment (Figure 2 A, C). This phenomenon is also associated to the accumulation of photo-assimilates, visible as chloroplast starch deposits under LM and TEM (Figure 2 B, D), as previously reported in other host plants (Maust et al., 2003; Junqueira et al., 2004; Musetti et al., 2013).
This study proved that phloem tissue of infected A. thaliana presented the main morphological and ultrastructural response to phytoplasma infection as reported in natural hosts. Moreover, analyses carried on A. thaliana were not affected by troubles linked to low phytoplasma titre and uneven distribution, typical of woody plants. Therefore, we can state that A. thaliana revealed a reliable model plant for phytoplasma-plant interactions, concerning both macroscopic symptoms and morphological and ultrastructural changes
I nomi propri dell'educazione. Illusione, illuminazione e luminosità della ratio pedagogica
No full textChasca andina Musetti & Johnson, new species
No full textChasca andina Musetti & Johnson, new species urn:lsid:zoobank.org:act:EF0EB 399 -FF 7 D- 43 CF-A 451 -E 6471 F 2 A 229 C urn:lsid:biosci.ohio-state.edu:osuc_concepts: 276541 Figures 4–9; Morphbank 10 http://www.morphbank.net/?id= 579899 Description. Body length of female: 6.6–8.7 mm (n= 8). Body length of male: 5.0– 6.8 mm (n= 21). Fore wing length of male: 3.9–4.8 mm (n= 17). Body color of female: head, mesosoma light brown to reddish brown, metasoma brown. Sculpture of female vertex: irregularly punctate (Fig. 5). Frontoclypeal suture of female: deeply impressed. Ventral margin of clypeus: weakly, evenly convex. Tyloid of male antenna: indicated by longer, suberect seta near base of antennomere. Sculpture of female pronotum: irregularly rugulose. Length of notaulus: percurrent (Fig. 5). Posterior separation of notauli: closely approximated, separated by distance subequal to width of notaulus (Fig. 5). Shape of mesoscutellar pit: semicircular. Sculpture of female mesopleural depression: irregularly rugulose punctate (Fig. 6). Length of female fore wing: minute, not surpassing posterior margin of mesoscutellum (Figs. 4–6). Length of female hind wing: minute, not surpassing posterior margin of metanotum. Diagnosis. Chasca andina may be distinguished in the female sex by the extremely reduced wings, the reddish color of the head and mesosoma, and the coarse sculpture of the vertex and pronotum. Males may be distinguished from C. gravis by the absence of raised tyloids on antennomeres 4–7. Etymology. The epithet andina is an adjective referring to the Andes Mountains. Link to Distribution Map. [http://hol.osu.edu/map-full.html?id= 276541] Material Examined. Holotype, female: CHILE: Bío-Bío Reg., Concepción Prov., Hualpén Commune, road to Ramuntcho (Ramuncho), 12.IV. 1980, T. Cekalovic, OSUC 18632 (deposited in CNCI). Paratypes: CHILE: 6 females, 22 males, 1 unknown, OSUC 116692 (AEIC); OSUC 117657, 117659– 117666 (ANIC); OSUC 18622, 18633 (CNCI); OSUC 117241–117255 (FSCA); OSUC 19232–19233 (MCZC). Other material: CHILE: 1 male, OSUC 117658 (ANIC). Comments. This species is known so far only from a small region of approximately 350 km (north to south) in central Chile. It is sympatric here with the more widespread Chilean species Monomachus porteri Brèthes. In contrast to C. gravis, several females have been collected. These vary some 25 % in overall size, suggesting either variation in host species, host size, or the possibility that the parasitoid may at least sometimes be gregarious. The specimen with the identifier OSUC 117658 is broken (head and mesosoma lost) and is therefore not designated as a paratype.Published as part of Johnson, Norman F. & Musetti, Luciana, 2012, Genera of the parasitoid wasp family Monomachidae (Hymenoptera: Diaprioidea), pp. 31-41 in Zootaxa 3188 on pages 36-37, DOI: 10.5281/zenodo.21104
Chasca Johnson & Musetti
No full textChasca Johnson & Musetti, new genus urn:lsid:zoobank.org:act:0DD 25 D 3 C- 48 C 2-40 BC-A 599 - 2 DC 850 EE0AB 7 urn:lsid:biosci.ohio-state.edu:osuc_concepts: 276540 Figures 4–15 Type species: Chasca andina Johnson & Musetti, n.sp. Description. Female. Length: 6.6–8.7 mm. Head in frontal view quadrate; head width across gena subequal to width across compound eyes; frons moderately convex; antennal insertions raised, forming modest raised ledge between eyes, divided medially by depressed area; inner margins of eyes weakly diverging ventrally; malar area posterior to malar sulcus mostly smooth, with few setigerous punctures, anterior to sulcus punctate; malar sulcus well-defined; apical margin of clypeus without teeth or lobes, longest medially; ocelli in small medial triangle, OOL> POL; vertex sculpture variable; occipital carina complete, reaching hypostomal carina ventrally; hypostoma narrow, weakly sclerotized; antenna flagelliform, 15 -merous, inserted far above clypeus; flagellomeres covered with short bristles, longer fine hairs sparsely distributed; A 2 short, length approximately 2 times width, A 3–15 elongate, uniform in width; mandible relatively narrow, longer than wide, bidentate apically, teeth broadly acute; distignath weakly convex, not swollen basally; basal margin of distignath not expanded; basignath small, broadly fusiform. Mesosoma: pronotal sculpture variable, produced anteriorly into distinct neck, transition between neck and collar marked by transverse carina; mesoscutum smooth, sparsely setose; notaulus present, arcuate, smooth; parapsidal furrow present; axilla smooth, sparsely setose, separated from disc of mesoscutellum by crenate furrow; mesoscutellar pit variable in shape, not crenulate anteriorly; central disk of scutellum quadrate, slightly longer than wide, posterior margin with single transverse row of subapical punctures; mesoscutellum largely smooth, with few scattered punctures; metascutellum (dorsellum) bulging, subquadrate; metapostnotum with pair of rounded posterior projections; mesopleuron punctate anteriorly, setose anteriorly and ventrally, with wide, smooth, nearly glabrous area adjacent to mesopleural sulcus; mesepisternal groove indicated by foveate line; scrobal groove indicated by transverse foveate line; mespisternum finely punctate, setose, protuberant ventrally; discrimen indicated by deep foveate longitudinal line of inflection, widened posteriorly to form small fusiform pit anterior to mid coxae, margin of pit strongly produced into fingerlike projections; metapleuron distinctly separated from propodeum by line of foveae, densely setose, coarsely sculptured; propodeum elongate, bulging dorsally, coarsely sculptured, setose throughout, with weak median longitudinal carina in anterior half; anterior margin of propodeum with pair of teeth opposite metapostnotal projections; fore and hind wings strongly reduced, brachypterous or micropterous; tibial spur formula 1-2 - 2; hind tibia without distinct scar at position of subgenual organ, distinctly, though weakly expanded in distal two-thirds; all tarsi 5 -segmented, basitarsus longest tarsomere on all legs; pretarsal claws simple. Metasoma: petiole moderately long (in comparison with many species of Monomachus), robust, weakly to moderately bowed; segment 2 subequal in length to segment 3, only slightly widened apically; segments 2–5 as wide as high, not strongly compressed laterally; terga, sterna strongly sclerotized, loosely connected, lateral margins of terga surrounding sterna; ovipositor apparently minute, not visible externally; cercus platelike. Male. Very similar to typical Monomachus; length of body 5.0– 7.5 mm; fore wing length 3.9–5.8 mm; antenna 14 -merous; fore wing with radial cell open apically (Fig. 9); base of m-cu srongly displaced basad of bifurcation of Cu 1 b; cercus digitiform. Etymology. The generic name refers to Chasca, the Incan goddess of dawn and dusk. The grammatical gender of the name should be considered as feminine. Diagnosis. Females of Chasca are immediately distinguishable from all Monomachus by their shortened wings. Males are separable from most Monomachus by the open radial cell in the fore wing. This character is shared with M. paulus, a species from Argentina. Chasca may be distinguished from this species by the rounded to sinuate ventral margin of the clypeus that lacks the small submedial teeth of M. paulus; the subequal, rounded to acute pair of mandibular teeth; and the small fusiform basignath. These differences may be summarized as follows:Published as part of Johnson, Norman F. & Musetti, Luciana, 2012, Genera of the parasitoid wasp family Monomachidae (Hymenoptera: Diaprioidea), pp. 31-41 in Zootaxa 3188 on pages 34-36, DOI: 10.5281/zenodo.21104
Note psicopedagogiche sulla condizione di “persona” dell’insegnante. Problemi di quotidianità scolastica tratti da un ricordo di Freud
No full textNell'articolo si prendono in esame alcuni passi di Psicologia del ginnasiale di Freud, letti alla luce dell'attuale dibattito sulla Pedagogia della persona. Lungo questo intreccio si giunge via via a richiamare l'attenzione su una condizione di ordine generale: se è vero che la formazione può darsi solo all'interno di una relazione implicante, allora l'insegnante è vincolato (e questo a prescindere da elementi volontaristici) a oltrepassare il suo ruolo istituito in ogni atto della sua prassi. Anche la persona dell'insegnante, intesa qui sia come presupposto dell'educazione che in termini dinamici e interattivi, merita allora attenzione e cura per una nuova paideia
Phytoplasmas: An Introduction
No full textPhytoplasmas are among the most recently discovered plant pathogens. They are wall-less prokaryotes
restricted to phloem tissue, associated with diseases affecting several hundred plant species. The impact of
phytoplasma diseases on agriculture is impressive and, at the present day, no effective curative strategy has
been developed. The availability of rapid and sensitive techniques for phytoplasma detection as well as the
possibility to study their relationship with the host plants is a prerequisite for the management of
phytoplasma-associated diseases
The Internet Is Not a Tool: Reappraising the Model for Internet-Addiction Disorder Based on the Constraints and Opportunities of the Digital Environment
No full textThe extent of digital information in every sphere of people’s lives has caused the integration of the
Internet into the cognitive tasks people performing their daily routines, leading to the consideration
of the Internet as part of an extended concept of cognition (Smart et al., 2017). The concept of
the Internet as a tool to connect to a virtual reality that is separate from the real world is no
longer current, so a new concept of the Internet that takes its environmental features into account
is needed. This concept is in line with Floridi’s (2014) idea of an infosphere that shapes people’s
reality. The conceptualization of the Internet as an environment rather than as a tool leads to the
reformulation of IAD theory. If the Internet is not just a tool to be utilized, the theoretical model of
IAD cannot be based on behavior connected to its overuse, misuse, or abuse.
Musetti and Corsano The Internet as a Social Environment
Based on this opinion, we present arguments in favor of
reconsidering the Internet as an environment rather than as
a tool. In the following section, we explore the Internet’s role
in cognitive ecology, as well as the inadequacy of treating the
Internet as a tool and thus of the current Internet-addiction
model
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