Effect of cytokinins on shoot apical meristem in Nicotiana tabacum

Cytokinins are involved in plant cell proliferation leading to plant growth and morphogenesis. The size, activity and maintenance of the shoot apical meristem (SAM) are defined by a balanced rate of mitotic cell divisions and functional cell differentiation that are controlled by cytokinins. In order to investigate the effect of exogenous cytokinin on SAM, morpho-anatomical changes in the shoot apices of tobacco treated with benzyladenine (BA) were compared to those of untreated control plants

In vitro zygotic embryo culture of Pinus peuce Gris.: Optimization of culture conditions affecting germination and early seedling growth

This study reports a protocol for the germination and early seedling growth of Pinus peuce Gris. using zygotic embryo culture. In order to overcome seed dormancy and optimize organogenesis, the effect of nutritional, plant growth regulatory and physical factors on in vitro germination and growth of isolated mature zygotic embryos of P. peuce were investigated

Bench-to-bedside review: Neonatal sepsis - redox processes in pathogenesis

The present review is aimed at elucidating the neonatal 'sepsis redox cycle' - the cascade of inflammatory and redox events involved in the pathogenesis of sepsis in neonates. While adult and neonatal sepses share some common features, there are some substantial differences: higher mortality rates occur in adult sepsis and worse long-term effects are evident in neonatal sepsis survivors. Such epidemiological data may be explained by the lower ability of IL6 and IL8 to activate NF-kappa B-regulated transcription in neonatal sepsis in comparison to TNF-alpha, which is involved in the mechanisms of adult sepsis. The activation of NF-kappa B in neonatal sepsis is further promoted by hydrogen peroxide and results in mitochondrial dysfunction and energy failure as septic neonates experience decreased O-2 consumption as well as lower heat production and body temperature in comparison to healthy peers. In neonates, specific organs that are still under development are vulnerable to sepsis-provoked stress, which may lead to brain, lung, and heart injury, as well as vision and hearing impairments. In the light of the processes integrated here, it is clear that therapeutic approaches should also target specific steps in the neonatal 'sepsis redox cycle' in addition to the current therapeutic approach that is mainly focused on pathogen eradication

In vitro zygotic embryo culture of Pinus peuce Gris.: Optimization of culture conditions affecting germination and early seedling growth

This study reports a protocol for the germination and early seedling growth of Pinus peuce Gris. using zygotic embryo culture. In order to overcome seed dormancy and optimize organogenesis, the effect of nutritional, plant growth regulatory and physical factors on in vitro germination and growth of isolated mature zygotic embryos of P. peuce were investigated.Projekat ministarstva br.17301

Induction of somatic embryogenesis in Pinus heldreichii culture

The potential for somatic embryogenesis in zygotic embryo and megagametophyte cultures of Pinus heldreichii was examined. Somatic embryogenesis was initiated from megagametophytes containing immature zygotic embryos at early stages of development. An induction frequency of up to 6.7% was obtained on Gresshoff and Doy medium in the presence of 2 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.5 mg/l benzyladenine (BA). Formation and further proliferation of embryogenic tissue were achieved upon transfer of explants to a medium with reduced levels of growth regulators. Somatic embryos are being cultured for further development. .U kulturi izolovanih zigotskih embriona i ovula munike (Pinus heldreichii) ispitivan je efekat hranljive podloge i regulatora rastenja na indukciju somatske embriogeneze. Somatska embriogeneza je indukovana u kulturi ovula koje su sadržavale embrione na ranom stupnju razvića. Najviša frekvencija indukcije od 6.7% postignuta je kada su ovule 5 dana gajene na Gresshoff i Doy (GD) hranljivoj podlozi u prisustvu 2,4-D 2 mg/l i BA 0.5 mg/l, a zatim prenete na GD podlogu u kojoj je koncentracija regulatora rastenja bila 5 puta niža. U cilju dugotrajnog održavanja u kulturi, embriogeno tkivo je izolovano i gajeno na GD podlozi sa 2,4-D 0.2 mg/l i BA 0.05 mg/l. Mikroskopskom analizom je utvrđeno da se tkivo sastoji od brojnih embriona na ranim stupnjevima razvića. Za klonalnu propagaciju ove značajne endemoreliktne četinarske vrste u kulturi in vitro, neophodna su dalja istraživanja sa ciljem povećanja frekvencije indukcije somatske embriogeneze, kao i frekvencije sazrevanja embriona. .nul

Effect of development stage of Pinus heldreichii megagametophytes on the induction of embryogenic tissue

The potential of somatic embryogenesis induction was examined by in vitro growing of isolated ovules of Pinus heldreichii (Christ.) on nutrient media. The induction of embryogenic tissue was stimulated by Gresshoff and Doy (GD) medium with nitrogen compounds reduced to one half and with 0.5 mg/l BA and 2.0 mg/l 2.4-D. Still, the most important factor in this process was the development stage of embryos in the ovule. An induction frequency of 10% was obtained on the ovules in which embryos were in the pre-cotyledonary stage. When the dominant embryo in the ovule was in the cotyledonary stage, the induction frequency was lower or absent. Proliferation of embryogenic tissue was achieved on the media with reduced concentration of growth regulators, and the initial stages of embryo maturation were obtained on the media with ABA and 5% sucrose.Izolovane ovule Pinus heldreichii (Christ.) gajene su in vitro na hranljivim podlogama radi ispitivanja mogućnosti indukcije somatske embriogeneze. Hranljiva podloga Gresshoff and Doy (GD) sa azotnim jedinjenjima, smanjenim na polovinu i BA 0.5 mg/L i 2.4-D 2.0 mg/L, stimulisala je indukciju embriogenog tkiva. Ipak, najvažniji faktor u ovom procesu bio je stadijum razvića embriona u ovuli. Frekvencija indukcije od 10% dobijena je na ovulama u kojima su embrioni bili u prekotiledonarnom stadijumu razvića. Kada je dominantni embrion u ovuli bio u kotiledonarnom stadijumu razvića, frekvencija indukcije bila je manja ili je nije ni bilo. Proliferacija embriogenog tkiva dobijena je na podlogama sa smanjenom koncentracijom regulatora rastenja, a početni stadijumi sazrevanja embriona na podlogama sa ABA i 5% saharoze.Projekat ministarstva br. 143026

Adventitious bud induction in pinus heldreichii christ: Seedling explant culture

By using tissue culture methods multiple shoot regeneration was achieved from seedling expiants of Pinus heldreichii in the presence of 1 mg/1 benzyladenine. The age of seedlings was found to be important for bud induction and shoot elongation. Histological events associated with bud primordium formation were also examined.Regeneracija izdanaka u kulturi klijanaca Pinus hrldreichii postignta je u prisustvu l mg/1 benziladenina, korišćenjem metode kulture tkiva. Nađeno je da starost eksplantata utiče na proces indukcije i razvića adventivnih pupoljaka. Razviće adventivnih pupoljaka je histološki analizirano.nul

Factors influencing germination and growth of isolated embryos of Pinus heldreichii

The effects of nutritional, hormonal, and physical factors on the germination and growth of isolated mature zygotic embryos of Pinus heldreichii were studied under in vitro conditions. The optimum medium for embryo germination and adequate conversion into seedlings was basal Gresshoff and Doy (1GD) medium. All tested carbohydrates at the applied concentrations stimulated embryo growth, but only 3% sucrose increased embryo germination compared to the control, while maltose had an inhibitory effect. Among the applied plant growth regulators, only gibberelic acid (GA3) had a few benefits on the development of isolated embryos into plantlets, while the others had a negative effect. Embryos cultured on an agar-solidified medium grew better and the germination percentage was higher than in a liquid medium. Light treatment did not affect embryo germination, but generally stimulated seedling growth.U kulturi in vitro ispitivan je efekat nutritivnih, hormonalnih i fizičkih faktora na klijanje i rastenje izolovanih zigotskih embriona munike (Pinus heldrechii). Većina izolovanih embriona munike klijala je već tokom prve nedelje nakon prenošenja na hranljivu podlogu. Mada embrioni mogu da klijaju i na podlozi bez soli, vitamina i ugljenih hidrata, najveći procenat klijanja i najbolje morfološke karakteristike klijanaca postignute su na bazalnoj Gresshoff & Doy podlozi (1GD) sa 3% saharozom. Od ispitivanih regulatora rastenja samo je giberelna kiselina (GA3) pozitivno delovala na razviće embriona, dok su auksini i citokinini inhibirali njihovo dalje razviće. U odnosu na embrione koji su rasli u tečnoj podlozi, embrioni sa čvrste agarne podloge, klijali su u većem procentu i dalje se pravilno razvijali. Mada generalno stimulišu rastenje klijanaca, svetlosni tretmani nisu imali efekat na klijanje embriona. Dobijeni rezultati pokazuju da se in vitro sistem može koristiti za brzu i sinhronu produkciju zdravih klijanaca elitnih genotipova koji se odlikuju niskom produkcijom semena.Projekat ministarstva br. 14302

Effect of cytokinins on shoot apical meristem in Nicotiana tabacum

Cytokinins are involved in plant cell proliferation leading to plant growth and morphogenesis. The size, activity and maintenance of the shoot apical meristem (SAM) are defined by a balanced rate of mitotic cell divisions and functional cell differentiation that are controlled by cytokinins. In order to investigate the effect of exogenous cytokinin on SAM, morpho-anatomical changes in the shoot apices of tobacco treated with benzyladenine (BA) were compared to those of untreated control plants.Projekat ministarstva br. 17301

Morphology, distribution, and histochemistry of trichomes of Thymus lykae Degen & Jav. (Lamiaceae)

Micromorphology, distribution, and histochemistry of the trichomes of Thymus lykae were studied using scanning electron microscopy (SEM)and confocal laser scanning electron microscopy (CLSM). The leaves, stem, and calyx bear numerous glandular and non-glandular trichomes. Two types of glandular trichomes are identified - peltate and capitate. Results of histochemical tests showed positive reactions to polysaccharides, proteins, and lipids. Yellow autofluorescence of secreted material was noticed in peltate and capitate trichomes. Strong reddish-yellow autofluorescence of the lipophilic and hydrophilic secreted material was observed with CLSM.Mikromorfologija, distribucija i histohemijska analiza trihoma kod vrste Thymus lykae urađena je korišćenjem skening elektronskog mikroskopa i konfokalnog laserskog skening mikroskopa. Nežlezdane, negranate i dva tipa žlezdanih trihoma - peltatne i kapitatne opisane suuovom radu. Brojne nežlezdane i žlezdane trihome nalazile suse kako na listovima (i na licu i na naličju)tako i na stablu i na čašici. Rezultati histohemijskih istraživanja pokazala supozitivne reakcije na polisaharide, lipide i proteine. Sekretorni produkti unutar peltatnih trihoma imali sujako žutu autofluorescenciju, dok je u kapitatnim trihomama zapažena slabija autofluorescencija. Korišćenjem CLSM uočena je jarko crveno-žuta autofluorescencija lipofilnih i hidrofilnih sekretornih materija u žlezdanim trihomama.Projekat ministarstva br. 14304