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09049cam a2200481 i 4500 |
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NSK01000215771 |
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HR-ZaNSK |
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20221125083411.0 |
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980527s1996 ci a m 000 0 hrv |
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|9 (HR-ZaNSK)215997
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|9 (HR-ZaNSK)980527002
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|a (HR-ZaNSK)000215771
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|a hrv
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|a ci
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|a 581.174.085
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1 |
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|a Muraja, Jasmina
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|a Studij pretvorbe plastida u kontroliranim uvjetima :
|b doktorska disertacija /
|c Jasmina Muraja.
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| 260 |
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|a Zagreb :
|b J. Muraja,
|c 1996
|e ([s. l. :
|f s. n. ])
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| 300 |
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|a 99 listova :
|b ilustr. djelomice u bojama, table, graf. prikazi ;
|c 30 cm.
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| 500 |
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|a Doktor prirodnih znanosti - biologija
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| 500 |
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|a Mentor: Mercedes Wrischer
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|a Sveučilište u Zagrebu, Prirodoslovno-matematički fakultet, Zagreb, 1996
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|a Bibliografija: str. 87-99
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|a Summary
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|a Sažetak: Istražen je proces pretvorbe amiloplasta i leukoplasta u koroplaste pod utjecajem svjetlosti. Korišrteni su mikro gomolji krumpira (Salanum tuberosum L. var. Istra) uzgojeni in vitro, kao i diskovi odraslih gomolja krumpira iste vrste. Istražen je također utjecaj herbicida amitrola i norflurazona na proces ozelenjavanja, tj. pretvorbe plastida u odraslom gomolju i mikrogomolju krumpira. Pretvorba amiloplasta i leukoplasta u kloroplaste u mikrogomolju krumpira započinje nakon 12 sati izlaganja svjetlosti. Naime , u svjetlosnom mikroskopu uočena je primarna fluorescecncija klorofila već nakon 12 sati osvjetljavanja. Ona se javlja najprije u aminoplastima uz rubove škrobnih zrna. Istodobno uočavaju se i mali kloroplasti čiji se broj s vremenom povećava.
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|a Kloroplasti ispočetka nastaju pretvorbom leukoplasta, a kasnije i diobom kloroamiloplasta i leukoplsta. U neosvjetljavanom tkivu mikrogomolja metodom tekućinske kromatografije visoke učinkovitosti, kao i spektrofotometirjskim mjerenjem utvrđen je nizak sadržaj luteina i violaksantina, dok drugi pigmenti nisu detektirani. Izlaganjem svjetlosti već nakon 12 sati uočava se prisutnost klorofila a i b, a nakon 28 sati javlja se i [beta]-karoten. Tijekom daljnjeg ozelenjavanja kontinuirano rastu koncentracije svih pigmenata. Nasuprot tome značajan porast sadržaja pigmenata u odraslom gomolju krimpira utvrđen je tek nakon četiri dana izlaganja svjetlosti. Tijekom pretvorbe amiloplsta i leukoplasta u kloroplaste dolazi do znatnih promjena u sastavu membranskih proteina.
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|a Razdvajanjem proteina SDS-elektroforezom na poliakrilamidnom gelu nakon tri dana osvjetljavanja u materijalu je uočena pojava LHCII proteina i polipeptida od 32 kDa, vjerojatno D1 proteina fotosustava II. Detaljna analiza enzim-imunološkom reakcijom na LHCII protein utvrdila je njegovu prisutnost već nakon 12 sati pokusa. Tijekom ozelenjavanja koncentracija ovog proteina se kontinuirano povećava. Istom metodom potvrđeno je da u odraslom gomolju dolazi do pojave LHCII proteina tek nakon četiri dana osvjetljavanja. Ultrastrukturna istraživanja pretvorbe amiloplsta i leukoplsta u kloroplaste pokazala su da tijekom ozelenjavanja mikrogomolja dolazi do izgradnje tilakoidnog sustava. U plstidima se najprije javljaju pojedinačni tilakoidi koji se zatim slijepljuju u granu.
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|a Nakon tri dana storma amiloplasta se povećeva, napose u području novonastalih tilakoida. Istodobno uočavaju se i tipični kloroplasti. Pojedinačni tilakoidi u kloro-aminoplastima pokazuju početke fotosintetske aktivnosti (pozitivna DAB reakcija) već nakon 12 sati osvjetljavanja. Postupno se razvijaju kloro-amiloplasti i kloroplasti s fotosintetski aktivnim tilakoidnim sustavom. Analiza ribosomske RNA pokazala je u neosvjetljavanom tkivu odraslog gomolja nizak sadržaj ukupne rRNA, dok kloroplstne molekule od 16S i 23S nisu detektirane. Pretvorbom amiloplasta u kloro-amiloplaste i kloroplaste dolazi do poratsa u sadržsju ukupne rRNA, a nakon 28 sati uočene su i plastidne molekule (16S i 23S). Ovaj nalaz je u skladu s elektronsko-mikroskopskim istraživanjima.
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|a Naime, u amiloplastima neosvjetljavanog gomolja krumpira nema ribosoma, a vrlo malo ih ima u citoplazmi. Tijekom ozelenjavanja raste broj ribosoma, kako u citoplazmi tako i u plastidima. Istražen je utjecaj tzv. "bleaching" herbicida amitrola i norflurazona na proces ozelejnjavanja tj. pretvorbu amiloplasta i leukoplasta u kloroplaste. Amitrol nije imao značajan utjecaj na proces pretvorbe plastida. Nakon četiri dana osvjetljavanja u mikrogomoljima je uočen porast koncentracije svih pigmenata. Nakon sedam dana izlaganja svjetlosti utvrđena je i prisutnost LHCII proteina. Norflurazon je imao snažan inhibitorni utjecaj na proces pretvorbe plastida. Ultrastrukturna istraživanja pokazala su da su plastidi zakočeni u razvoju i da sadrže brojne plastoglobule. Koncentracije svih pigmenata ostaju vrlo niske i nakon sedam dana pokusa.
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|a U tom materijalu nije utvrđena ni prisutnost LHCII proteina antena fotosustava II.
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|a Summary: Amyloplast-to-chloroplast and leucoplast-to-chloroplast transformations under defined light conditions were studied in microtubers and full-grown tubers of the potato (Solanum tuberosum L. var. Istra). The influence of the bleaching herbicides amitrole and norflurazon on the greeing process was studied as well. After a mere 12 hours of illumination, the characteristic fluorescence of chlorophyll was detectable by light microscopy. Such fluorescence was first visible around starch grains, in amyloplsat entering the transitional stage of chloro-amyloplasts. In addition, a distinct set of smaller chloroplasts was observed, which appear to originate by direct transformation of leucoplast, or from the daughter plastids derived from dividing chloro-amylopasts and (or) leucoplasts.
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|a The fast induction of choloplast pigments in illuminated microtubers was confirmed by HPLC and spectrophotometric analysis. While only trace amounts of lutein and violaxantine were found in dark-grown material, chlorophylls a and b were clearly detectable after 12 hours, and [bheta]-cariten after 28 hours of light exposure. The levels of those pigments continued to increase until the 7th day of illumination. For full-grown tubers, in contrast, four days of light exposure were required to produce significant pigment accumulation. Changes in protein pattern during plastid transformation were studied by SDS-polyacrylamide gel electrophoresis.
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|a In microtubers, the LHCII membrane protein and a 32kDa polypeptide (prsumably D1), proteins which are components of the photosynthetic appartus, were clearly dtectable by conventional methods of protein staining, on the third day of light exposure. With Western Blot analysis, which is more sensitive, the LCHII protein was detected as early as after 12 hours after the onset of illumination. The latter methods also showed the appearance of LHCII protein in full-grown tubers, after four days of light exposure. The ultrastructural changes in greening amyloplasts and leucoplasts were monitored by electron microscopy, focusing on the formation of thylakoids and on their aggregation into grana.
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| 520 |
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|a The various stages of chloro-amyloplasts could thus be clearly distinguished from the small, typical chloroplasts discussed above, which appear after three days of illumination. Cytochemical data (photooxidation of DAB) confirmed that the newly formed thylakoid system was photosynthetically active. In microtubers kept in the dark, the total RNA level was so low that it was not possible to detect the 16S and 23S molecules of shloroplasts rRNA. This changed dramatically in the course of plastid transformation. The appearance of the molecules (16S and 23S) of chloroplast rRNA was detectable after 28 hours of illumination. Simultaneous ultrastructural changes were observed by electron microscopy.
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| 520 |
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|a While ribosomes were sparse in the cytoplasm, and not clearly visible in amyloplasts, of dark-grown material, they became abundant in both compartments during greening process. The bleaching herbicides amitrole and norflurazon affected the greeing process as follows. Amitrol delayed plastid transformation. Under its influence, four days were requered for a significant increase in pigment content of illuminated microtubers, and seven days for the appearance of detectable leves of the LHCII protein. Norflurazon, in contrast, strongly inhibited the greeing process. The electron microscope showed damaged plastids with numerous plastoglobules. Also, pigment levels remained extremly low, and the LHCII protein of photosystem II antena complex could not be detected.
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| 650 |
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|a Plastidi
|x Ultrastruktura
|2 nskps
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| 700 |
1 |
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|a Wrischer, Mercedes
|4 cns
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| 981 |
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|p CRO
|r HRB1996
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| 998 |
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|n DCD/97
|c sbno9808
|c ikal9811
|c dkrp9904
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| 852 |
4 |
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|j DCD-ZG-61/98
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| 876 |
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|e DCD
|a 61/1998
|
| 886 |
0 |
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|2 unimarc
|b 08786nam0 2200409 450
|