Teachers' personal network analysis reveals two types of pioneers in educational digitalization: Formal and informal intermediaries at schools

SELFIE is a tool of the European Commission designed to support schools in developing their digital capacity. Schools across Europe have used SELFIE as a diagnostic tool. However, participating schools expressed a need for external guidance in the implementation of digital education transformation, including the exchange of expertise and inspiring practices with other educational centers. In this research we explore what are the key factors in the creation of collaborative networks between teachers. As a case study, we focus on the first steps of building a network of schools to promote digital education in Cantabria (northern Spain). With the participation of 11 schools, we conducted 22 interviews and 2 focus groups to analyze the learning environments of the teaching staff, the personal collaboration networks in the professional field, and the factors perceived as relevant in the design of the digital action plan of each school. The results showed the existence of teachers in each school who were pioneers in the digitization process and who acted as intermediaries both with the public educational administration and with teachers from other schools. During the interviews with these pioneers, we evaluated their personal networks as well as the factors they deem significant for an effective digital transformation. The results were contrasted in a public forum in which 120 teachers participated. Based on these results, we discuss how the creation of a network of key actors could contribute in developing the digital capacity of schools in the region.Universidad de Sevilla 4392/022

Ultrasounds pretreatment of olive pomace to improve xylanase and cellulase production by solid-state fermentation

Abstract Olive mills generate a large amount of waste that can be revaluated. This work aim to improve the production lignocellulolytic enzymes by solid-state fermentation using ultrasounds pretreated olive mill wastes. The composition of olive mill wastes (crude and exhausted olive pomace) was compared and several physicochemical characteristics were significantly different. The use of both wastes in SSF was evaluated and a screening of fungi for xylanase and cellulase production was carried out. After screening, the use of exhausted olive pomace and A. niger led to the highest enzyme activities, so that they were used in the study of ultrasounds pre-treatment. The results showed that the sonication led to a 3-fold increase of xylanase activity and a decrease of cellulase activity. Moreover, the liquid fraction obtained from ultrasounds treatment was used to adjust the moisture of solid and a positive effect of xylanase (3.6-fold increase) and cellulase (1.2-fold increase) production was obtained.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684). This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462). José Manuel Salgado was supported by the grant SFRH/BPD/84440/2012 from Fundação para a Ciência e Tecnologia – FCT, Portugal

Integrated use of residues from olive mill and winery for lipase production by solid state fermentation with Aspergillus sp

Two phase olive mill waste (TPOMW) is presently the major waste produced by the olive mill industry. This waste has potential to be used as substrate for solid state fermentation (SSF) despite of its high concentration of phenolic compounds and low nitrogen content. In this work, it is demonstrated that mixtures of TPOMW with winery wastes support the production of lipase by Aspergillus spp. By agar plate screening, Aspergillus niger MUM 03.58, Aspergillus ibericus MUM 03.49 and Aspergillus uvarum MUM 08.01 were chosen for lipase production by SSF. Plackett-Burman experimental design was employed to evaluate the effect of substrate composition and time on lipase production. The highest amounts of lipase were produced by A. ibericus on a mixture of TPOMW, urea and exhausted grape mark (EGM). Urea was found to be the most influent factor for the lipase production. Further optimization of lipase production by A. ibericus using a full factorial design (32) conducted to optimal conditions of substrate composition (0.073 g urea/g and 25% of EGM) achieving 18.67 U/g of lipolytic activity.Jose Manuel Salgado is grateful for Postdoctoral fellowship (EX-2010-0402) of Education Ministry of Spanish Government. Luis Abrunhosa was supported by the grant SFRH/BPD/43922/2008 from Fundacao para a Ciencia e Tecnologia-FCT, Portugal. Authors thank Fundacao para a Ciencia e a Tecnologia (FCT) for financial support through the project FCT Pest-OE/EQB/LA0023/2011

Rebel bodies and affects in movement : Imagining scenes for an indocile pedagogy

Aquest projecte de recerca es basa en l'experiència d'una etnografia performativa col·laborativa, que va tenir lloc en dos centres d'educació secundària de Barcelona durant el curs 2016-2017 en el context del projecte PI(E)CE, una iniciativa artística, social i educativa. Situat dins d'un marc que entrellaça les polítiques de l'emoció des d'una perspectiva feminista i postcolonial, les pedagogies de l'alliberament i de contacte, i els estudis de performance i performativitat, aquest projecte explora les possibilitats de resistència i transformació en escenes on els adolescents participants desafien els discursos tradicionals de gènere, la racialització i la sexualitat, produeixen contra-relats i, finalment, experimenten o negocien amb les seves identitats. Prenent el fil de les accions pedagògiques proposades a PI(E)CE i les creacions dels participants, la investigació es mou per les escenes que van il·luminar elements d'una pedagogia de resistència, agència i transformació. A través d'una etnografia performativa, que es nodreix de la fenomenologia queer i de l'afecte en / com a metodologia, es produeixen composicions d'escenes que tracen una trobada entre l'art i l'educació, i alhora, possibiliten la imaginació d'una pedagogia transformadora. Aquesta recerca impulsa la creació d'un marc per a una pedagogia indòcil -que inspirada en els elements de contacte, moviment i imaginació- elabora les interseccions entre l'emocionalitat i la identitat, la performance i la performativitat. Finalment, aquest projecte d'investigació desenreda la qüestió de les estratègies interpretatives proporcionades per la investigació qualitativa, a través de la tàctica de plugging-in. En aquesta direcció, l'emoció s'abraça no només com un element de la metodologia, sinó com un mètode en si mateix en un intent de mobilitzar els imaginaris alternatius de la recerca.Este proyecto de investigación se basa en la experiencia de una etnografía performativa colaborativa, que tuvo lugar en dos centros de enseñanza secundaria de Barcelona durante el año 2016-2017 en el contexto del proyecto PI(E)CE, una iniciativa artística, social y educativa. Situado dentro de un marco que entrelaza las políticas de la emoción desde una perspectiva feminista y postcolonial, las pedagogías de la liberación y del contacto, y los estudios de performance y performatividad, este proyecto explora las posibilidades de resistencia y transformación en escenas donde los adolescentes participantes desafían los discursos tradicionales de género, racialización y sexualidad, producen contrarelatos y, por último, experimentan o negocian con sus identidades. Tomando el hilo de las acciones pedagógicas propuestas en PI(E)CE y las creaciones de los participantes, la investigación se mueve por las escenas que iluminaron elementos de una pedagogía de resistencia, agencia y transformación. A través de una etnografía performativa, que se nutre de la fenomenología queer y del afecto en / como metodología, se producen composiciones de escenas que trazan un encuentro entre el arte y la educación, y a la vez, posibilitan la imaginación de una pedagogía transformadora. Esa búsqueda impulsa la creación de un marco para una pedagogía indócil -que bebiendo de los elementos de contacto, movimiento e imaginación- elabora las intersecciones entre la emocionalidad y la identidad, la performance y la performatividad. Por último, este proyecto de investigación desenreda la cuestión de las estrategias interpretativas proporcionadas por la investigación cualitativa, a través de la táctica de plugging-in. Hacia esta dirección, la emoción se abraza no sólo como un elemento de la metodología, sino como un método en si mismo en un intento de movilizar los imaginarios alternativos de investigación.This research project draws from the experience of a collaborative performance ethnography, that took place in two secondary schools in Barcelona during the year 2016-2017 within the context of project PI(E)CE, an artistic, social and educational initiative. Embedded within a framework, which entangles the politics of emotion from a feminist and post-colonial perspective, pedagogies of liberation and contact, and studies in performance and performativity, this project explores the possibilities of resistance and transformation in scenes where the participant adolescents challenge traditional discourses of gender, race and sexuality, produce counter-narratives, and, ultimately, experiment or negotiate with their identities. Taking the thread from the pedagogical actions proposed in PI(E)CE and the creations of the participants, the research navigates the scenes which illuminated elements of a pedagogy of resistance, agency and transformation. Through a performance ethnography, that nourishes from queer phenomenology and affect in / as methodology, it composes scenes which trace an encounter between art and education, as well as enable the imagination of a transformative pedagogy. This quest moves the creation of an imaginary for an indocile pedagogy -nurtured by the elements of contact, movement and imagination- which elaborates on the intersections between emotionality and identity, performance and performativity. Finally, this research project unravels a questioning of interpretational strategies provided in qualitative research through the tactic of plugging in. Towards this direction, emotion is embraced not only as an element of methodology, but as method itself in an attempt to also mobilize alternative research imaginaries

Olive mill waste management by microbial fermentation

The problems in olive oil three-phase system waste disposal have recently led recently to the application of a new methodology: the two-phase olive oil extraction system. This new technique results in the production of olive oil and a byproduct, which is the mixture of solid and liquid waste. The goal of this study was to use the byproduct of the two-phase olive oil extraction, the so-called “alpeorujo”, as a substrate for microbial growth and subsequently to result in a more friendly and useful byproduct released at the environment. Samples that were collected from a very well - known waste treatment company were chemically analysed. The phenol (2,7 %) as well as the sugar (2,3 %) content allow for the growth of various microorganisms on this waste. The microorganisms were isolated and identified according to classical microbiological methods in combination with molecular techniques. The results of this study have shown that the bacteria population is mainly characterised by Pseudomonas, Agrobacterium, Xanthomonas and Bacillus (10⁴ - 10⁷ cfu/g waste), while yeasts isolated belong to the genera Saccharomyces and Candida (10⁴ - 10⁶ cfu/g waste). Specific bacterial strains were isolated at 60°C (Aeromonas, Bacillus, Corynebacterium), while others (Lactobacillus, Bifidobacterium, Gemmela) grew under anaerobic conditions. Selected strains of bacteria and yeasts were used as inocula in microcosm systems experiments using apeorujo as a substrate. Bacteria were unable to grow under the specific microcosm system conditions, but there was a 4-fold increase in yeast population. The results of the chemical analysis showed a significant reduction in the phenolic content leading in a less toxic byproduct released to the environment. From all the strains that have been isolated from alpeorujo, the strain that has been selected for further study was Paecilomyces variotii, not only because it has been proven capable of increasing the protein content in some preliminary experiments, but also because it has had already been reported in the past for its excellent ability to grow in a variety of highly-polluted industrial effluents, such as molasses, wood hydrolysates and spent sulfite liquor. The physiological studies of the specific fungus is the first necessary step for the optimisation of the fermentation parameters. In order to study the growth and the metabolic activity of the microorganism, the solid state system that has been developed in our lab (Microbiology lab., University of Athens) was connected to a Gas analyser to have the possibility of continuous analysis of gaseous effluent. Thus the CO₂ production and the O₂ consumption were on-line measured. The solid state fermentor is designed to allow temperature regulation by submersion of the column in a water bath, precise regulation of air flux. Two different kinds of alpeorujo wastes have been used as substrates in the solid state fermentation experiments: fresh alpeorujo (no further treatment) and dried (has been dried at high temperature) as well as two different temperatures (30°C and 35°C). First results have shown that both waste kinds can be used as substrates, while protein content was increased by 20% in the final product. Finally, when diluted sugar beet molasse was used as an enrichment factor, the production of microbial protein was higher and the protein content of the final product had been optimised by 46%. Because Paecilomyces variotii is a biotechnologically interesting strain and it has been used to detoxify various wastes (Romantschuk & Lehtomaki, 1978, Silva et al., 1995), it has been considered crucial to broaden its study on a molecular level. Firstly, through mutagenesis, a specific mutated strain has been selected, which can be used for further experiments. Besides this, two genomic libraries of the wild type have been constructed. In order to check if the two libraries are representative of the fungal genome, we made an effort to locate conservative genes, such as atcnA and argB in the two libraries. Mutated strains of A.nidulans lacking the specific genes have been transformed with the two genomic libraries in order to isolate strains that contain the two genes. Finally, the last step of this work comprises of the optimisation of the existing method for A.nidulans transformation. We systematically investigated the efficiency of A.nidulans transformation using protoplasts prepared from different stages of conidiospore germination and young mycelium. Using standard integrative plasmids, increased transformation yields were obtained with protoplasts isolated from a specific stage coincident with germ tube emergence. This increase ranged, on the average, from two- to eight-fold depending on the different plasmids used. Transformation efficiencies with a replicative plasmid were similar to those obtained using previously described methods. This method is significantly easier and faster than other current methods and it could offer a good alternative approach with strains where mycelium is either recalcitrant to protoplastation or protoplasts from mycelium are inefficiently transformed.Τα προβλήματα διάθεσης των αποβλήτων του τριφασικού συστήματος οδήγησαν τα τελευταία χρόνια σε μια νέα μεθοδολογία παραγωγής ελαιόλαδου: το διφασικό σύστημα. Κατά τη χρησιμοποίηση της νέας αυτής τεχνολογίας παράγονται μόνο δύο φάσεις: το ελαιόλαδο και τα παραπροϊόντα, τα οποία είναι μίγμα του ελαιοπυρήνα και των υγρών αποβλήτων. Στο διδακτορικό αυτό έγινε προσπάθεια αξιοποίησης του αποβλήτου που προέρχεται από διφασικά συστήματα παραγωγής ελαιολάδου (ελαιόπουλπα) μέσω μικροβιακών ζυμώσεων. Από μεγάλη εταιρεία διαχείρισης αποβλήτων ελαιουργείου ελήφθησαν δείγματα αποβλήτου προερχόμενα από διαφορετικά στάδια της διαδικασίας παραγωγής ελαιολάδου, τα οποία αναλύθηκαν ως προς τη χημική τους σύσταση. Η σχετικά χαμηλή περιεκτικότητα ταννινών στο απόβλητο (2,7%) καθώς και η επαρκής ποσότητα σακχάρων (2,3%) επιτρέπουν την ανάπτυξη πληθώρας μικροοργανισμών. Στο συγκεκριμένο απόβλητο έγινε ταυτοποίηση του μικροβιακού πληθυσμού μέσω των κλασικών μεθόδων μικροβιολογίας. Τα αποτελέσματα της μελέτης έδειξαν ότι τα βακτήρια ανήκαν κυρίως στα γένη Pseudomonas, Agrobacterium, Xanthomonas και Bacillus σε σχετικά μεγάλους πληθυσμούς (10⁴ - 10⁷ cfu/g αποβλήτου), ενώ τα στελέχη των ζυμών στα γένη Saccharomyces και Candida τα οποία απαντούσαν σε μικρότερη συχνότητα (10⁴ - 10⁶ cfu/g αποβλήτου). Μελέτες φυσιολογίας στο εργαστήριο έδειξαν ότι μερικά από τα απομονωθέντα βακτηριακά στελέχη είχαν την ικανότητα ανάπτυξης σε υψηλές θερμοκρασίες, όπως εκείνη των 60°C (Aeromonas, Bacillus, Corynebacterium) καθώς και υπό αναερόβιες συνθήκες (Lactobacillus, Bifidobacterium, Gemmela). Επιλεγμένα στελέχη των απομονωθέντων βακτηρίων και ζυμών χρησιμοποιήθηκαν ως εμβόλια σε συστήματα μικρόκοσμου έχοντας ως υπόστρωμα απόβλητο ελαιόπουλπας. Ενώ τα βακτήρια αδυνατούσαν να αναπτυχθούν στις δοσμένες συνθήκες, ο πληθυσμός των ζυμών αυξήθηκε κατά 4 λογαριθμικές μονάδες με αποτέλεσμα την αλλαγή της χημικής σύστασης του αποβλήτου. Το προϊόν της ζύμωσης ήταν αρκετά πιο φιλικό προς το περιβάλλον σε σχέση με το αρχικό απόβλητο, τόσο λόγω της φρουτώδους οσμής, μετά το τέλος της ζύμωσης, όσο και της μείωσης της ποσότητας των φαινολών κατά 42 - 58%. Επειδή όμως δε σημειώθηκε αύξηση του πρωτεϊνικού περιεχομένου σ’ αυτή τη σειρά πειραμάτων, προχωρήσαμε στην αξιοποίηση του συγκεκριμένου αποβλήτου εμβολιάζοντας το απόβλητο ελαιόπουλπας με το ενδογενές μυκητιακό στέλεχος Paecilomyces variotii. Προηγήθηκε εκτενής μελέτη της μορφολογίας και της φυσιολογίας του στελέχους, για τον προσδιορισμό των καλύτερων συνθηκών ανάπτυξης του μικροοργανισμού. Για τη διεξαγωγή αυτών των πειραμάτων εγκαταστάθηκε στο εργαστήριο μικροβιολογίας σύστημα στερεού ζυμωτήρα. Το σύστημα αυτό αποτελείται από 16 κολώνες ζύμωσης και είναι σχεδιασμένο έτσι ώστε να επιτρέπει τη ρύθμιση της θερμοκρασίας με βύθιση της κολώνας σε υδατόλουτρο, την ακριβή ρύθμιση του αερισμού και τη δυνατότητα ελέγχου των αερίων που παράγονται κατά τη διάρκεια της ζύμωσης. Η εκτίμηση της μεταβολικής δραστηριότητας του μικροοργανισμού έγινε εκτιμώντας το παραγόμενο CO₂ με τη βοήθεια αέριου χρωματογράφου συνδεδεμένου με το στερεό ζυμωτήρα. Στα πειράματα στερεών ζυμώσεων χρησιμοποιήθηκαν ως υποστρώματα δύο είδη ελαιόπουλπας: νωπή (δεν έχει υποστεί καμία επεξεργασία) και ξηρή (έχει ξηραθεί προηγουμένως) καθώς και διαφορετικές θερμοκρασίες επώασης (30°C και 35°C). Τα πρώτα αποτελέσματα έδειξαν ότι τόσο η νωπή όσο και η ξηρή ελαιόπουλπα μπορούν να χρησιμοποιηθούν ως υποστρώματα και το τελικό ζυμωμένο προϊόν έχει αυξημένο πρωτεϊνικό περιεχόμενο κατά 20%. Στη συνέχεια χρησιμοποιήθηκε αραιωμένο διάλυμα μελάσσας ως παράγοντας εμπλουτισμού της ελαιόπουλπας βελτιστοποιώντας την παραγωγή μικροβιακής πρωτεΐνης και αυξάνοντας το πρωτεϊνικό περιεχόμενο του τελικού προϊόντος κατά 46%. Δεδομένων των παραπάνω αποτελεσμάτων και έχοντας υπόψη ότι ο Paecilomyces variotii είναι ένας ενδιαφέρον βιοτεχνολογικά μικροοργανισμός και στελέχη του έχουν χρησιμοποιηθεί για την αποτοξικοποίηση διαφόρων αποβλήτων (Romantschuk & Lehtomaki, 1978, Silva και συν., 1995) θεωρήθηκε σημαντική η περαιτέρω μελέτη του στελέχους σε μοριακό επίπεδο. Στην παρούσα διατριβή, έγινε προσπάθεια ανάπτυξης πρωτοκόλλων μοριακού χειρισμού του στελέχους Paecilomyces variotii που απομονώθηκε από απόβλητο ελαιουργείου. Για το σκοπό αυτό, πραγματοποιήθηκαν τα εξής βήματα: α) Μέσω της διαδικασίας της μεταλλαξογένεσης απομονώθηκε ένα μεταλλαγμένο στέλεχος με νέες ιδιότητες, του οποίου η μορφολογία και η φυσιολογία μελετήθηκαν εκτενώς και το οποίο μπορεί να χρησιμοποιηθεί μελλοντικά σε πειράματα μετασχηματισμού, β) Δημιουργήθηκαν 2 γονιδιωματικές βιβλιοθήκες του στελέχους Paecilomyces variotii. Προκειμένου να ελεγχθεί η πληρότητα των ανωτέρω γονιδιωματικών βιβλιοθηκών, δηλαδή αν περιείχαν όσο το δυνατό πιο αντιπροσωπευτικό δείγμα του γονιδιώματος του συγκεκριμένου στελέχους, εντοπίστηκαν συντηρημένα γονίδια και έγινε προσπάθεια εισαγωγής των αντίστοιχων γονιδίων argB και actin της γονιδιωματικής βιβλιοθήκης του Paecilomyces variotii σε άλλα μεταλλαγμένα στελέχη μυκήτων όπως του Aspergillus nidulans που παρουσιάζουν έλλειψη των φυσιολογικών γονιδίων. Στο πλαίσιο αυτό έγινε ένα τελευταίο βήμα που ήταν η βελτιστοποίηση της μεθόδου μετασχηματισμού πρωτοπλαστών με σκοπό τη δυνατότητα υποκλωνοποίησης γονιδίων. Η νέα μέθοδος αφορά την απομόνωση πρωτοπλαστών από σπόρια του μύκητα Aspergillus nidulans καθώς και πειράματα σύγκρισης της συγκεκριμένης μεθόδου με την ήδη υπάρχουσα, που αφορά απομόνωση πρωτοπλαστών από μυκήλιο του μύκητα. Είναι γνωστό ότι ο A. nidulans χρησιμοποιείται ως πρότυπο σύστημα για την ανάπτυξη ή βελτίωση πρωτοκόλλων μετασχηματισμού που θα μπορούσαν να εφαρμοστούν σε μύκητες που παρουσιάζουν βιοτεχνολογικό ενδιαφέρον. Η βελτίωση των συχνοτήτων μετασχηματισμού μέσω της νέας μεθόδου δίνει τη δυνατότητα λήψης μετασχηματισμένων κυττάρων ακόμα και σε θεωρητικά δύσκολες περιπτώσεις, όπως εκείνες των μυκήτων των οποίων ο μετασχηματισμός είναι χαμηλής απόδοσης ή δεν έχει περιγράφει

De-esterified homogalacturonan enrichment of the cell wall region adjoining the preprophase cortical cytoplasmic zone in some protodermal cell types of three land plants

The distribution of highly de-esterified homogalacturonans (HGs) in dividing protodermal cells of the monocotyledon Zea mays, the dicotyledon Vigna sinensis, and the fern Asplenium nidus was investigated in order to examine whether the cell wall region adjoining the preprophase band (PPB) is locally diversified. Application of immunofluorescence revealed that de-esterified HGs were accumulated selectively in the cell wall adjacent to the PPB in: (a) symmetrically dividing cells of stomatal rows of Z. mays, (b) the asymmetrically dividing protodermal cells of Z. mays, (c) the symmetrically dividing guard cell mother cells (GMCs) of Z. mays and V. sinensis, and (d) the symmetrically dividing protodermal cells of A. nidus. A common feature of the above cell types is that the cell division plane is defined by extrinsic cues. The presented data suggest that the PPB cortical zone-plasmalemma and the adjacent cell wall region function in a coordinated fashion in the determination/accomplishment of the cell division plane, behaving as a continuum. The de-esterified HGs, among other possible functions, might be involved in the perception and the transduction of the extrinsic cues determining cell division plane in the examined cells. © 2019 by the authors. Licensee MDPI, Basel, Switzerland

Spatio-temporal diversification of the cell wall matrix materials in the developing stomatal complexes of Zea mays

Main conclusion: The matrix cell wall materials, in developingZea maysstomatal complexes are asymmetrically distributed, a phenomenon appearing related to the local cell wall expansion and deformation, the establishment of cell polarity, and determination of the cell division plane. In cells of developing Zea mays stomatal complexes, definite cell wall regions expand determinately and become locally deformed. This differential cell wall behavior is obvious in the guard cell mother cells (GMCs) and the subsidiary cell mother cells (SMCs) that locally protrude towards the adjacent GMCs. The latter, emitting a morphogenetic stimulus, induce polarization/asymmetrical division in SMCs. Examination of immunolabeled specimens revealed that homogalacturonans (HGAs) with a high degree of de-esterification (2F4- and JIM5-HGA epitopes) and arabinogalactan proteins are selectively distributed in the extending and deformed cell wall regions, while their margins are enriched with rhamnogalacturonans (RGAs) containing highly branched arabinans (LM6-RGA epitope). In SMCs, the local cell wall matrix differentiation constitutes the first structural event, indicating the establishment of cell polarity. Moreover, in the premitotic GMCs and SMCs, non-esterified HGAs (2F4-HGA epitope) are preferentially localized in the cell wall areas outlining the cytoplasm where the preprophase band is formed. In these areas, the forthcoming cell plate fuses with the parent cell walls. These data suggest that the described heterogeneity in matrix cell wall materials is probably involved in: (a) local cell wall expansion and deformation, (b) the transduction of the inductive GMC stimulus, and (c) the determination of the division plane in GMCs and SMCs. © 2016, Springer-Verlag Berlin Heidelberg

Callose: a multifunctional (1,3)-beta-d-glucan involved in morphogenesis and function of angiosperm stomata

Background Although the cellulose microfibril organization in guard cell (GC) walls play a crucial role in the mechanism of the stomatal function, recent work showed that matrix cell wall materials are also involved. Especially in the kidney-shaped stomata of the fern Asplenium nidus, callose actively participates in the mechanism of opening and closure of the stomatal pore. Scope The present review briefly presents and discusses recent findings concerning the distribution and role of callose in the kidney-shaped stomata of the dicotyledon Vigna sinensis as well as in the dumbbell-shaped stomata of the monocotyledon Zea mays. Conclusion The discussed data support that, in both categories of angiosperm stomata, callose is implicated in the mechanism of stomatal pore formation and stomata function by locally affecting the mechanical properties of the GC cell walls

Diversity of streptomycetes among specific Greek terrestrial ecosystems

The diversity of streptomycetes isolated from different Greek terrestrial ecosystems using phenotypic identification, and the relationship between the number of species and the number of isolates as a diversity index, was studied. A total of 344 Streptomyces strains have been isolated and identified from diverse sites in the Greek territory, such as heavily disturbed agricultural areas and preserved forest areas, and from specific rhizosphere ecosystems. According to phenotypic identification, these strains belonged to 19 different cluster groups with a Willcox probability > 0.8. Streptomyces cyaneus, Strep. albidoflavus, Strep. diastaticus and Strep. exfoliatus were the most common cluster groups isolated from at least six different habitats. On the other hand, there were cluster groups that appeared in only one or two habitats, such as Strep. griseoflavus, Strep. rimosus, Streptoverticillium blastmyceticum, Nocardia mediterranea and Strep. fulvissimus. The diversity indices among the different cluster groups of each sampling area indicated that the different habitats can be sub-divided into two main groups: rhizosphere habitats and non-rhizosphere habitats, showing that the rhizosphere is one of the most important factors which determines the population structure of a specific soil area

Actin filament-organized local cortical endoplasmic reticulum aggregations in developing stomatal complexes of grasses

Endoplasmic reticulum (ER) immunolabeling in developing stomatal complexes and in the intervening cells of the stomatal rows (ICSRs) of Zea mays revealed that the cortical-ER forms distinct aggregations lining locally expanding wall regions. The polarized subsidiary cell mother cells (SMCs), displayed a cortical-ER-patch lining the wall region shared with the inducing guard cell mother cell (GMC), which disorganized during mitosis. In dividing SMCs, ER persisted in the preprophase band region and was unequally distributed in the mitotic spindle poles. The subsidiary cells (SCs) formed initially an ER-patch lining the common wall with the GMC or the young guard cells and afterwards an ER-ring in the junction of the SC wall with the neighboring ones. Distinct ER aggregations lined the ICSR wall regions shared with the SCs. The cortical-ER aggregations in stomatal cells of Z. mays were co-localized with actin filament (AF) arrays but both were absent from the respective cells of Triticum turgidum, which follow a different morphogenetic pattern. Experimental evidence showed that the interphase ER aggregations are organized by the respective AF arrays, while the mitotic ER aggregations by microtubules. These results revealed that AF and ER demarcated "cortical cytoplasmic domains" are activated below the locally expanding stomatal cell wall regions, probably via a mechanosensing mechanism triggered by the locally stressed plasmalemma/cell wall continuum. The probable role(s) of the local ER aggregations are discussed. © 2010 Springer-Verlag