Professor Emeritus, Prof. Dr. Dr. h.c. Niko Torelli

At the end of 2020, Prof. Dr. Dr. h.c. Nikolaj Torelli became a Professor Emeritus of the University of Ljubljana. The title of Professor Emeritus is awarded to retired Professors for their significant contributions to the operation, reputation, and development of the University of Ljubljana. We briefly introduce our new Professor Emeritus and his work

Seasonal dynamics of xyogenesis and phloiemogenesis in silver fir (Abies alba Mill.)

Preučili smo dinamiko nastajanja ksilemskega in floemskega letnega prirastnegaplašča oz. branike pri navadni jelki (Abies alba) v rastni sezoni 2003. Vzorce floema, kambija in ksilema smo vsak teden vzeli iz dveh navideznozdravih odraslih jelk. Raziskave s svetlobnim mikroskopom so pokazale, da se je na floemski strani začela diferenciacija enega do dveh slojev floemskih derivatov še pred začetkom kambijeve aktivnosti. Kambijeva delitvena aktivnost se je začela hkrati na ksilemski in floemski strani v začetku maja. Kambijeva aktivnost se je zaključila konec avgusta. Diferenciacija terminalnih traheid kasnega lesa je potekala do konca oktobra, floemskih celic pa do konca septembra. Število celic, nastalih na ksilemski strani, je bilo večje kot na floemski. Zdi se, da je bila po obodu drevesa širina ksilemske branike bolj variabilna od floemske.The dynamics of xylem and phloem growth ring formation in silver fir (Abies alba Mill.) was studied during the growing season 2003. Blocks of tissue, containing phloem, cambium and outer xylem, were taken weekly from two apparently healthy silver fir trees. According to the observations of transverse sections under light microscope, the cambial cell divisional activity began in early May on the phloem and xylem side simultaneously. Priorto this activity, differentiation of one or two layers of the phloem derivatives began to take place. Cambial activity ceased at the end of August.Differentiation of the terminal late wood tracheids adjacent to cambiumwas completed by the end of October and of the phloem cell by the end of September. Cell production on the xylem side of healthy firs was more intense and the variability in widths of the growth rings across the stem circumference was also greater compared to the phloem

Thin-layer chromatography of gallic acid, pyrocatehol, phloroglucinol, resorcinol and catechin

Preučevali smo primernost šestih različnih zmesi topil - razvijalcev za ločitev enostavnih fenolnih spojin, kot so galna kislina, pirokatehol, floroglucionol, resorcinol, in sorodno spojino katehin s pomočjo tankoplastne kromatografije. Kot najbolj primerna sistema topil za ločitev komponent na stacionarni fazi silikagela na aluminijasti foliji sta se izkazala kloroform -etilacetat - ocetna kislina (prostorninsko razmerje50 : 50 : 1) in toluen -acetonitril - mravljična kislina (prostorninsko razmerje70 : 30 : 1). Ločitev organskih spojin je bila učinkovitejša v sistemih topil, ki so imeli večji delež organskih topil. Spojine smo vizualizirali s pomočjo dveh reagentov, in sicer z železovim(III) kloridom in z vanilin-žveplovim reagentom.The suitability of six solvent systems for the thin-layer chromatographic separation of simple phenolic compounds such as gallic acid, pyrocatechol phloroglucinol, resorcinol and related compound catechin were investigated. The most appropriate developing solvent systems for the separation of these organic compounds were chloroform - ethyl acetate - acetic acid (50 : 50 : 1) and toluene -acetonitrile - formic acid (70 : 30 : 1). The best separation of the five organic compounds was achieved using solvents with higher organic content. Detection was carried out using ferric chloride reagent and vanillin-sulphuric reagent

Pregled lipofilnih i hidrofilnih ekstraktivnih tvari u tkivima obične bukve

Common beech (Fagus sylvatica L.) is one of the most widespread and economically important tree species in Europe and, therefore, represents a potential source of high value added extractives. The aim of this paper was, therefore, to review the existing data regarding the composition of lipophilic and hydrophilic extractives of beech tissues, and the extraction systems and analytical techniques used for their examination. The lipophilic extractable fraction of beech is characterized mainly by saturated and unsaturated fatty acids, fatty alcohols and sterols while the hydrophilic extractives of beech consist of soluble sugars, i.e. monosaccharides, oligosaccharides, sugar alcohols and sugar acids, as well as of simple phenols and flavonoids. Chromatography has been recognized as the convenient and most frequently used technique for the chemical analysis of extractives. This overview showed that the information about the composition of low-molecular extractives of beech is satisfactory, but the data on oligomeric extractives are still fragmentary.Obična bukva (Fagus sylvatica L.) jedna je od najrasprostranjenijih i gospodarski najvažnijih vrsta drva u Europi i stoga je potencijalni izvor ekstraktivnih tvari visoke dodatne vrijednosti. Cilj rada bio je preispitati postojeće podatke koji se odnose na sastav lipofilnih i hidrofilnih ekstraktivnih tvari u tkivima bukve te sustave za ekstrakciju i analitičke tehnike koje se primjenjuju za njihovo istraživanje. Lipofilne frakcije koje se mogu ekstrahirati iz bukve uglavnom su zasićene i nezasićene masne kiseline, masni alkoholi i sterol, dok se hidrofilne ekstraktivne tvari iz bukve sastoje od topljivih šećera, tj. monosaharida, oligosaharida, šećernih alkohola i šećernih kiselina, kao i od jednostavnih fenola i flavonoida. Kromatografija je prepoznata kao prikladna i najčešće primjenjivana tehnika kemijske analize ekstraktivnih tvari. Ovaj je pregled pokazao da su podaci o sastavu niskomolekularnih ekstraktivnih tvari iz bukve zadovoljavajući, ali su podaci o oligomernim ekstraktivnim tvarima još uvijek fragmentarni

Deset let revije Radiology and oncology: nekaj bibliometrijskih izmer

Background. Bibliometrics and its methods are a useful set of tools for analysing a scientific journal\u27s relative position in the field. By measuring different quantitative data and comparing them with other journals in the field, certain decisions can be made as to the future of the journal. Objectives and methods. We thought as appropriate to take last ten years of Radiology and Oncology (1992-2001) and put that content to double scrutiny: first, by applying various guantitative measurements to the journal\u27s content to get a more objective picture of the whole and of its development in the past ten yearsthen by additionally comparing it to another international journal from the field and of similar orientation, Neoplasma, to illustrate ifdifferences and/or similarities between the two are in favour of or detriment to Radiology and Oncology. Results and conclusion. Results show thatRadiology and Oncology has been progressing in the right direction, but that extra efforts should be made by the editors and the editorial board to attract more articles per issue and to gradually increase the share of experimental articles to boost its impact in the field. Also, to improve its visibility, editors, reviewers and also authors that publish in Radiology and Oncology could consider citing the articles published in this journal, in the articles published elsewhere, when appropriate.Izhodišče. Bibliometrija s svojimi metodami predstavlja zelo koristen nabor orodij za analiziranje relativne pomembnosti strokovne revije znotraj njene stroke. S pomočjo kvantitativnih meritev vsebine in primerjavami s podobnimi revijami v stroki si tudi uredniki lahko pomagajo pri odločitvah glede nadaljnih usmeritev uredniške politike. Cilji in metode. Vzeli smo zadnjih deset letnikov (1992-2001) revije Radiology and Oncology in njeno celotno vsebino spustili skozi dvojno merjenje: s prvim merjenjem smo zasledovali cilj, da se s pomočjo raznih kvantitativnih bibliometričnih metod pridobi boljobjektivna slika o celotni reviji in njenem razvoju v zadnjih desetih letihnato pa smo s pomočjo primerjave s sorodno mednarodno revijo, Neoplasma, ugotovljali, če so razlike in/ali podobnosti med obema, obravnavanireviji v korist ali škodo. Rezultati in zaključek. Rezultati kažejo, da se je revija dobro razvila, toda potrebni bodo dodatni napori ožjega uredništva in aktivna pomoč uredniškega odbora, da privabijo več kvalitetnih dankov in s tem povečajo njihovo število na zvezek, ter da postopoma povečujejo delež eksperimentalnih člankov, kar, kot kažejo izkušnje,lahko zviša relativni vpliv revije v stroki. Revija bi si lahko tudi povečala ugled tako, da bi vsi avtorji, ki v njej objavljajo, svoje objave v Radiology and Onocology smiselno vključevali med citate v članke, ki jih objavljajo drugje

Response of cambium in Norway spruce (Picea abies) to heating and cooling of stem

Proučili smo vpliv eksperimentalnega ogrevanja in hlajenja dela debla navadne smreke (Picea abies) na kambijevo aktivnost in celično diferenciacijo. Poskusasta potekala 30 dniogrevanje od 29.3.2004 do 3.5.2004, hlajenje pa od14.6.2004 do 20.7.2004. Vzorce floema, kambija in ksilema smo iz dreves odvzeli vsakih 10 dni, pripravili prečne prereze tkiv in preparate opazovali ssvetlobnim mikroskopom. Lokalno ogrevanje je po 10 dneh induciralo delitveno aktivnost kambija na floemsko stran, po 20 dneh pa tudi na ksilemsko. Po 30 dneh je pri ogrevanem vzorcu nastalo do 15 celic ranega lesa. V tem času se jeredna delitvena aktivnost kambija pri kontrolnem drevesu šele začela. Odziv kambija na hlajenje debla je bil manj izrazit. Anatomskih razlik med kontrolnim in hlajenim vzorcem po 10 in 20 dneh ni bilo. Po 30 dneh je pri hlajenem vzorcu začel nastajati kasni les, pri kontrolnem drevesu pa šele prehodni rani-kasni les. S poskusom smo demonstrirali, da je mogoče pri smrekiz umetnim ogrevanjem in hlajenjem debla vplivati na ksilo- in floemogenezo.The effect of experimental heating and cooling in a part of the stem of Norwayspruce (Picea abies) on cambial activity and cell differentiation was studied. Experiments were performed for 30 daysheating from 29 March 2004 until 3 May 2004 and cooling from 14 June, 2004 until 20 July 2004. Samples ofphloem, cambium and xylem were taken from trees every 10 days, transverse sections of tissue were prepared and observed under light microscope. After 10days, localized heating reactivated cambial cell division on the phloem sideand after 20 days on the xylem side as well. After 30 days up to 15 early wood cells were formed in the heat-treated sample. Regular cambial activity inthe control tree only started after 30 days. Cambial response to the coolingof the stem was less conspicuous. No anatomical differences were detected between the control and cool-treated samples after 10 and 20 days. After 30 days, late wood already started to form in the cool-treated sample and only transition early-late wood in the control tree. Our experiments demonstrated that it is possible to influence xylo- and phloemogenesis in Norway spruce by experimental heating and cooling of the stem

Needle trace method

Metoda preučevanja sledi iglic terminalnega poganjka, ali krajše metoda sledi iglic (ang.: needle trace method), retrospektivno beleži starost iglice v trenutku, ko odpade, ter preučuje vpliv okoljskih in biotskih dejavnikov na številne izpeljane podatke, ki temeljijo na ugotovljeni življenjski dobi iglice. Z izvedbo metode pridobimo podatke o dolžini višinskih prirastkov ter številu sledi iglic v posameznih branikah vseh višinskih prirastkov. Z izračunanimi kazalniki je mogoče oceniti fizično stanje krošnje preučevanega drevesa. Metoda je bila razvita na Finskem na rdečem boru (Pinus sylvestris L.), kmalu pa uporabljena tudi na drugih iglavcih. Uporablja se na področju dendrokronologije, gozdne ekologije, patologije in entomologije. V članku avtorji predstavljajo osnovno morfologijo sledi iglic, osnovno idejo metode in njeno uporabnost v okoljskih študijah ter izpeljane kazalnike, kot so relativno število sledi iglic ter zadrževanje, izguba, odmet, starost, dolgoživost, gostota, letni prirast števila in zaloga iglic

Anatomy of reaction zones in beech (Fagus sylvatica L.)

Pri bukvi (Fagus sylvatica L.) smo raziskovali mejne kompartmentalizacijske plasti izvotljenih ter razkrajajočih se debelnih sredic. Mejne plasti pri vsehpreiskanih drevesih anatomsko ustrezajo reakcijskim conam in ne bariernim conam kot jih predpostavlja model CODIT. V osrednjem delu reakcijske cone so bile traheje intenzivno okludirane z gumoznimi snovmi in suberiziranimi tilami. Lumni trakovnega in aksialnega parenhima, vlaknastih traheid in vse pikenjske odprtine so bili zapolnjeni z netopnimi depoziti. Za notranji del reakcijskih con je značilen razkroj celičnih sten in depozitov, suberizirane strukture pa so ostale nespremenjene. Pri reakcijskih conah, ki mejijo neposredno na duplino, je ta del manjkal, na površini reakcijske cone v duplini so vidna trosišča gliv. Povečana količina škroba v parenhimskih celicah in različne razvojne faze til v zunanjem delu reakcijske cone kažejo na aktivne kompartmentalizacijske procese. Aktivna obrambna in pasivna zaščitna funkcija reakcijskih con v živem drevesu sta podrobneje analizirani.Compartmentalization boundary layers surrounding hollow and decaying stem cores were investigated in beech (Fagus sylvatica L.). In all investigated trees, boundary layers corresponded anatomically to the reaction zones and notto the barrier zones as proposed by the CODIT model. In the central part ofreaction zones, vessels were heavily occluded with deposits of gums and suberised tyloses, whereas the lumina of ray and axial parenchyma, fibre tracheids and all pit apertures were filed with insoluble deposits. The inner part of reaction zones exhibited decay of cell walls and deposits, leaving suberized structures intact. This part was absent in the reaction zones bordering directly on the hollow, although fungal fruit bodies were present onthe surface of the reaction zone. Increased amount of starch grains and different growing stages of tyloses in the outer part of reaction zones indicated active compartmentalization processes. The paper discusses in detailthe active defensive and passive protective function of reaction zones in the living trees