373 research outputs found
Polyamines, their analogs, and transglutaminase effects on apical growth of the pollen tube
No full textPolyamines, their analogs, and transglutaminase effects on apical growth of the pollen tube
Stefano Del Duca1, Rosa Anna Iorio1, Iris Aloisi1 , Donatella Serafini-Fracassini1, Claudia Faleri 2, Vincenzo Tumiatti3, Anna Minarini3 and Giampiero Cai2
1 Dipartimento di Biologia, Università di Bologna, Via Irnerio 42, Bologna (Italy)
2 Dipartimento Scienze Ambientali, Università di Siena, via Mattioli 4, Siena (Italy)
3 Dipartimento di Scienze Farmaceutiche, Università di Bologna, via Belmeloro 6, Bologna (Italy).
e-mail: [email protected]
Sexual reproduction of flowering plants depends on delivery of the male gamete to the egg cell, which occurs through a polarized growth, located exclusively at the tip of the pollen tube, growing from the pollen grain, distinguished by very fast rates and extended lengths. Pollen germination is characterised by the continuous rebuilding of the cell wall and apical migration of the cytoplasm sustained by cytoskeleton re-organisation.
Polyamines (PAs) are essential for cell growth in animals and plants. Early evidence showed that PAs are metabolised and essential factors during pollen tube emergence (Bagni et al. 1981). We investigated the effect of natural and synthetic PAs to check the effect on the apical growth of the pollen tube. We observed that among the natural PAs, spermine inhibited the growth from 10 M onwards. Among the synthetic ones, BD 23, an aromatic derivative of Spm also showed similar effects. The morphology of the tubes showed loss of polarity and enlarged tip. The effects of PAs are related, at least in part to the inhibition of the ROS synthesis, that, at physiological concentration, support the apical growth.
As TGase mediates some of the effects of PAs by covalently binding them to proteins, the activity of this enzyme was examined and confirmed by detection of Ca2+-activated TGase activity (Del Duca et al. 1997) and by identification of actin and tubulin as substrates of purified pollen TGase (Del Duca et al. 2009). The enzyme was found in two distinct location: as a soluble and a cell wall associated form (Di Sandro et al. 2010). Fluorescently-labeled of TGase products were essentially present at the apex of pollen tubes, in a region close to the pollen grain and in the pollen grain (Iorio et al. 2008). While the presence and activity of cytoplasmic TGase is likely to be related to the regulation of processes possibly associated with the cytoskeleton activity, the extracellular TGase might provide strength to the pollen tube cell wall during tube migration through the style (Di Sandro et al. 2010).
Here, we investigate in detail the localization and distribution of TGase in growing pollen tubes of pear (Pyrus communis). We used specific antibodies that cross-react with TGase of pollen tubes to localize the enzyme in different membrane compartments and in the cell wall of pollen tubes. Use of specific inhibitors indicated that the delivery of extracellular TGase is dependent on both actin filaments and membrane dynamics. Analysis by bidimensional electrophoresis showed that distinct TGase isoforms are associated with different cell compartments. The membrane TGase is likely to be associated with both Golgi-derived structures and the plasma membrane. The distribution of cytoplasmic TGase is dependent on the cytoskeleton while a different TGase form is actively transported via a membrane/cytoskeleton-based transport system and is secreted in the cell wall of pollen tubes, suggesting a Golgi-based exocytosis.
Acknowledgements. This research has been supported by the RFO 2010.
1 Bagni, N., Adamo, P. and Serafini-Fracassini, D. (1981) RNA, proteins and polyamines during tube growth in germinating apple pollen. Plant Physiol. 68: 727–730.
2 Folk, J.E., Park, M.H., Chung, S.I., Schrode, J., Lester, E.P. and Cooper, H. (1980) Polyamines as physiological substrates for transglutaminases. J. Biol. Chem.: 255, 3695-3700.
3 Del Duc..
Resources of the territory and social support as protective factors of teachers burnout
No full textThis study is part of a broader research which refers to systematic projects of educational intervention realised in marginal backgrounds of the city of Naples. The objective of the research is to explore the complexity of the phenomenon of malaise in schools in order to improve the offer of the interventions that the Association MdS plans with our department. The research is composed of a qualitative part still underway (interviews to teachers, observations in scholastic contexts, observations of meetings of reflexivity) and by a quantitative part on which we will focus in this paper.
The hypothesis is that the malaise of the teachers can be read in terms of burn-out by widening the perspective and inserting school in a system of micro and macro-contexts. That is why the aim was to investigate the joined impact on the burn-out phenomenon of factors of protection both contextual and relational: in particular, the perception that the teachers have of the resources of the territory and the perception of the social support available in and outside their school.
270 teachers of the region Campania have been contacted; 35.6% of them teach in middle school, 64.4% in high school. They are predominantly female (74.7%) and are mostly between 41 and 60 years old (74.3%); 87.7% of them have been tenured teachers for 14.3 years (DS = 10.0), while 12.3% of them have been temporary employees for 7.10 years (DS = 5.89). Moreover, 89.7% carry out curricular activities, while 10.3% are special needs teaching assistants.
The study used a self-report questionnaire composed of a form for socio-demographic data collection (gender, age, years of tenured teaching, years of temporary job, kind of school etc.) and other tools, briefly illustrated below: The Maslach Burnout Inventory (Maslach and Jackson, 1986; Taddei, 1988), teachers version; The Scale of Perception of Resources of the Territory (Petrillo and Donizzetti, 2008); The Social Support Questionnaire (Doudin, Cuchord, 2009; Albanese et. Al, 2010)
Analisi dell’allergenicità di polline di Citrus clementina e valutazione della cross-reattività con polline di graminacee
No full textAnalisi dell’allergenicità di polline di Citrus clementina e valutazione della cross-reattività con polline di graminacee
Rosa Anna Iorioa, Elisabetta Calamellib, Chiara Pulab, Giampaolo Riccib, Donatella Serafini-Fracassinia and Stefano Del Ducaa*
aDepartment of Biology E. S., University of Bologna, via Irnerio 42, 40126, Bologna, Italy. [email protected]
bDepartment of Pediatric Allergology of the Women's, Children's and Adolescents' Health Department of the Gozzadini Children's Hospital Sant'Orsola-Malpighi, University of Bologna, via Massarenti 11, 40138, Bologna, Italy.
Il consumo regolare di frutta e verdura è incoraggiato poiché alla base di una dieta giornaliera sana e in grado di migliorare la salute e prevenire o ridurre l'incidenza di varie malattie; sfortunatamente, circa 1/5 della popolazione dei paesi Occidentali soffre di allergie alimentari.
L’allergia agli agrumi non è molto frequente come altre allergie alimentari e polliniche (www.foodallergyitalia.org), ma quando presente, spesso è associata a pollinosi grazie ad un fenomeno di cross-reattività, per cui i pollini sarebbero la causa di una sensibilizzazione per via respiratoria che potrebbe predisporre all’allergia verso alimenti che contengono proteine omologhe a quelle sensibilizzanti polliniche. Circa il 10% dei bambini con allergia alimentare mostra sintomi dopo l’ingestione di arance, mentre circa il 17% di pazienti adulti italiani soffre di sindrome orale allergica (SOA) dopo l’ingestione di frutta e verdura. E’ stata documentata l’associazione, in oltre il 90% dei casi, tra sensibilizzazione IgE mediata in pazienti con sintomatologia clinica dopo ingestione di arance e positività dello skin prick test (SPT) per graminacee ed olivo. In questo lavoro i due allergeni maggiori delle arance, Cit s 1 (Germin-like Protein, GLP) e Cit s 2 (profilina), sono risultati correlati alla presenza di sensibilizzazione rispettivamente per il polline di olivo e cipresso (Cit s 1) e per il polline di platano (Cit s 2).
La valutazione clinica ha previsto l’identificazione ed il reclutamento di pazienti allergici /sensibilizzati agli agrumi in una popolazione di soggetti con pollinosi (allergia respiratoria) tramite l’anamnesi di allergia alimentare, SPT con estratti commerciali per agrumi e pollini potenzialmente cross-reagenti, nonché Prick by Prick test (PPT) con frutti maturi (polpa). Il siero di alcuni dei pazienti reclutati è stato utilizzato in prove ELISA ed in western blotting dimostrando di avere anticorpi specifici per alcune proteine del polline di Citrus clementina, che in funzione del peso molecolare si potrebbe ipotizzare essere Cit s 1 e Cit s 3 (non-specific Lipid Transfer Protein, nsLTP).
Lo studio della reattività crociata con i pollini si è focalizzato sull’analisi dell’espressione dei geni Cit s ben caratterizzati in frutto anche in polline di Citrus c., in modo da valutarne il potenziale allergenico e la cross-reattività con polline di graminacee, in particolare polline di Triticum aestivum. La ricerca di agenti sensibilizzanti in polline è continuata con i) la valutazione dell’espressione di due isoforme della fosfolipasi secretoria (PLAα, PLAβ), enzimi chiave nella sintesi degli eicosanoidi pro-infiammatori; ii) la valutazione dell’attività dell’enzima transglutaminasi (TGasi), che modificando post-traduzionalmente la fosfolipasi ne aumenterebbe l’attività; iii) la capacità dei pollini di produrre specie reattive dell’ossigeno (ROS).
E’ quindi ragionevole approfondire la ricerca di questi fattori importante nella patogenesi delle allergie respiratorie in pollini in grado di suscitare sensibilizzazione e cross-allergie agli agrumi
Immature cells of sprout apices of Helianthus tuberosus express different forms of transglutaminases homologous to human transglutaminases
No full textImmature cells of sprout apices of Helianthus tuberosus express different forms of transglutaminases homologous to human transglutaminases
Simone Beninati1, Rosa Anna Iorio2, Gianluca Tasco2, Donatella Serafini-Fracassini2, Rita Casadio2 and Stefano Del Duca2
1Department of Biology, II University of Roma "Tor Vergata",via della Ricerca Scientifica, 00173, Roma, Italy. 2Department of Biology E. S., University of Bologna, via Irnerio 42, 40126, Bologna, Italy. e-mail: [email protected]
Immature cells of etiolated apices growing from germinating sprouts of tubers of Helianthus tuberosus (H. t.) showed Ca2+-dependent TGase (TGase, EC 2.3.2.13) activity with fibronectin as substrate, dimethylcasein being substrate only at high Ca2+-concentrations. In three fractions of the 100,000g supernatant of extracted apices eluted at increased NaCl concentrations through a DEAE-cellulose column, three main transglutaminase bands of around 85, 75 and 58 kDa apparent molecular weight were immuno-identified by anti-TGase K type I and rat prostate gland TGase 4. These fractions catalysed the polyamine conjugation at the carboxamide group of N-benzyloxycarbonyl-L-leucine-bound -glutaminyl-residues. The amino acid composition of these TGase protein bands were compared to those of several sequenced TGases of different origin. The composition of the H.t. enzyme with a molecular range of 85 kDa showed a difference of about 2.5% with the average composition of four mammalian TGases 2 and a 3D model was built adopting TGase 2 as template. The H. t. band of 75 kDa showed a difference of about 0.3% with the average composition of three mammalian inactive EPB42, whereas this plant enzyme is active as demonstrated by the formation of glutamyl-derivatives when incubated with lebelled PAs. The 58 kDa form shared a low similarity with the human TGases 2, included their proteolytic fragments, and those of the Arabidopsis recombinant one (24-28 % difference), and even more with that of Streptoverticillium (41 % difference) and of the two maize sequences of similar molecular mass (51-52 % difference), which however are very dissimilar from all other known TGases.
By comparison to known plant TGases, these novel TGases are hypothesized to be constitutive and discussed in relation to their possible roles in immature cells of the sprout apices. These data also confirm that in plants there are multiple active forms of TGases in the same organ and that plant and animal enzymes probably are similar also structurally and not only, as already known, for their catalytic activity
Analisi comparativa degli allergeni e degli enzimi coinvolti in reazioni allergiche in polline di diverse cultivars di Malus domestica
No full textAnalisi comparativa degli allergeni e degli enzimi coinvolti in reazioni allergiche in polline di diverse cultivars di Malus domestica
Rosa Anna Iorioa, Roberta Parisb, Giulia Pagliaranib, Stefano Tartarinib, Giampaolo Riccic, Donatella Serafini-Fracassinia and Stefano Del Ducaa*
aDepartment of BiGeA, University of Bologna, via Irnerio 42, 40126, Bologna, Italy. [email protected]
b Department of Fruit Tree and Woody Plant Sciences, University of Bologna, Viale Fanin 46, Bologna 40127, Italy
cDepartment of Medical Science of the Gozzadini Children's Hospital Sant'Orsola-Malpighi, University of Bologna, via Massarenti 11, 40138, Bologna, Italy.
L'allergia alla mela è un problema frequente per un numero crescente di cittadini europei: è uno dei frutti che più comunemente causa problemi di sensibilizzazione allergica, esistono diverse cultivars con livelli variabili di allergenicità (la cui sintomatologia clinica è nota) e la sua coltivazione copre un ruolo importante nell’agricoltura europea, specialmente in quella italiana. Per quanto riguarda l’allergia al polline di melo esistono pochi riferimenti in letteratura probabilmente perché, non essendo un polline anemofilo ma entomofilo, è presente in minore quantità in atmosfera e quindi anche se allergenico è difficilmente responsabile di allergie respiratorie; si sono comunque osservati casi frequenti tra gli agricoltori che stanno a contatto con colture arboree.
Un fenomeno diffuso è la cosiddetta sindrome betulla-frutta-verdura, dove i pazienti sensibilizzati all'allergene maggiore di polline di betulla Bet v 1, cross-reagiscono con proteine omologhe presenti in frutta e verdura, come la mela. Generalmente, i sintomi sono limitati alla cavità orale, la cosiddetta sindrome orale allergica (SOA).
L'allergenicità alla mela è un fenomeno complesso a causa del numero elevato di determinanti genetici e fattori ambientali, ma sono stati pubblicati alcuni studi sulla caratterizzazione genetica e genomica degli allergeni. Nel genoma del melo sono state identificate quattro classi principali di allergeni, chiamate Mal d 1, 2, 3 e 4, organizzate in famiglie multigeniche contenenti diverse isoforme differenzialmente espresse nella frutta. Ad oggi, solo poche varietà di mele sono riconosciute per caratteristiche di ipoallergenicità.
Lo scopo del nostro lavoro è stato quello di caratterizzare e confrontare l’allergenicità del polline di diverse cultivars di Malus domestica, molto diffuse nella regione del mediterraneo - Gala, Florina, Golden Delicious, Durello - in modo da poterle classificare in funzione del grado di allergenicità (iperallergeniche, mediamente allergeniche o ipoallergeniche).
Lo studio di espressione genica è stato condotto sulle seguenti proteine: PR10-like protein (Mal d 1), thaumatin-like protein (TLP, Mal d 2), non specific lipid transfer proteins (nsLTP, Mal d 3) e profilina (Mal d 4); inoltre è stato valutato anche il profilo di espressione di enzimi quali fosfolipasi A2 (PLA2) e transglutaminasi (TGase), coinvolti nella reazione allergica. Per ogni famiglia genica sono state analizzate diverse isoforme grazie all’impiego di coppie di primer specifici disegnati per ogni sottofamiglia e scelti in accordo con il loro profilo di espressione genetica nel frutto della mela.
Gli studi biochimici tramite Western blots con anticorpi diretti contro gli allergeni e gli enzimi coinvolti nella reazione infiammatoria ed i saggi ELISA-modificati con l’uso di siero di pazienti allergici al frutto hanno fornito elementi interessanti sulla ricerca di agenti sensibilizzanti in polline.
Questi dati sono in linea con quelli pubblicati sulla classificazione dei frutti, dove Gol¬den e Gala sono riportati come iperallergenici; un dato innovativo è invece la ca¬ratterizzazione del potenziale allergenico di Florina, iperallergenica, e di Durel¬lo, ipoallergenico, su cui i dati bibliografici sono scarsi anche per il frutto.
Proseguendo questa strada sperimentale e con approfondimenti ulteriori si potrebbe essere in grado di produrre alimenti a bassa allergenicità le cui caratteristiche dichiarate darebbero un valore aggiunto all’alimento
Cultural Routes between East and West: a network for cooperation between Mediterranean cities
No full textAbstractRegions bordering the Mediterranean Sea form an area where more than geographical proximity strong cultural links are found, an area that, despite the specificities of individual countries, has important features of community life, which enable a convenient strategic opportunity for a large-scale policy. In this context, cultural heritage may play a role of social and territorial cohesion, thus representing a key factor for the sustainable development of communities and regions. The paper examines the meaning and the essence of Cultural Routes, focusing on the strategy for their conservation and enhancement in relation to their specific characteristics and peculiarities. Criteria for their fruition and management are also evaluated.The challenge is to enrich and develop knowledge of Cultural Routes between East and West and to create a cooperation network among Mediterranean cities for the integrated conservation of the cultural and environmental heritage they share
Geografia umana. Cultura, società, spazio
No full textFouberg/Murphy: Human Geography: People, Place, and Culture, 12th Edition, teaches students to appreciate the diversity of people, places, and cultures, and understand the role people play in shaping our world. The goals of this edition are to provide geographic context to global, regional, national, and local issues and to teach students to think geographically and critically about these issues. Human Geography features beautifully designed maps, dozens of vibrant photographs taken by the author team, and author and guest field notes that help students see how geographers read cultural landscapes and use fieldwork to understand places.
Fouberg’s Human Geography, 12th Edition, now integrates Threshold Concepts to help students develop their ability to think geographically. Once they learn and apply one of these concepts in the context of a given place, students integrate it into their thinking and can draw from it as they learn new material and explore other places
Distribution of Transglutaminase in Pear Pollen Tubes in Relation to Cytoskeleton and Membrane Dynamics
No full textTransglutaminases (TGases) are ubiquitous enzymes that take part in a variety of cellular functions. In the pollen tube, cytoplasmic TGases are likely to be involved in the incorporation of primary amines at selected peptide-bound glutamine residues of cytosolic proteins (including actin and tubulin), while cell wall-associated TGases are believed to regulate pollen tube growth. Using immunological probes, we identified TGases associated with different subcellular compartments (cytosol, membranes, and cell walls). Binding of cytosolic TGase to actin filaments was shown to be Ca2+-dependent. The membrane TGase is likely associated with both Golgi-derived structures and the plasma membrane, suggesting a Golgi-based exocytotic delivery of TGase. Association of TGase with the plasma membrane was also confirmed by immunogold transmission electron microscopy. Immunolocalization of TGase indicated that the enzyme was present in the growing region of pollen tubes, and that the enzyme co-localizes with cell wall markers. Bidimensional electrophoresis indicated that different TGase isoforms were present in distinct subcellular compartments, suggesting either different roles or different regulatory mechanisms of enzyme activity. The application of specific inhibitors showed that the distribution of TGase in different subcellular compartments was regulated by both membrane dynamics and cytoskeleton integrity, suggesting that delivery of TGase to the cell wall requires the transport of membranes along cytoskeleton filaments. Taken together, these data indicate that a cytoplasmic TGase interacts with the cytoskeleton, while a different TGase isoform, probably delivered via a membrane/cytoskeleton-based transport system, is secreted in the cell wall of pear pollen tubes where it might play a role in the regulation of apical growth
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