Browsing by Author "Animasaun, D.A., Oyedeji, S., Adedibu, P.A. & Abegunde, I.F."

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    Comparative assessment of different pretreatment chemicals and fixatives duration on mitotic spread of Allium cepa (L.) root cells.
    (Science Focus. Published by Faculty of Science, Ladoke Akintola University of Technology, Ogbomoso, Nigeria., 2018) Animasaun, D.A., Oyedeji, S., Adedibu, P.A. & Abegunde, I.F.
    The study compared two pretreatment liquid substances (ice water and paradichlorobenzene), duration of pretreatment, and fixatives on the root mitosis of Allium cepa to determine the efficiency of the pretreatment and fixatives duration for good and visible mitotic chromosome spreads. A. cepa bulbs were grown on sterile water to initiate root formation. Root tips (<0.5 cm) were harvested and pretreated with either Cold Ice Water (CIW) or 0.1% Paradichlorobenzene (PDCB) for 3 and 6 hours. The pretreated root tips were fixed in 1:3 Glacia Acetic Alcohol (GAA) or Propionic Acid Alcohol (PAA) for 24 hours, hydrolyzed with 5-NHCl at room temperature for eight minutes, and then stained with aceto-orcein. The slides were viewed under an Olympus microscope and photomicrographs of the spread taken. Pretreatment with PDCB for 6 hr and fixed in GAA resulted in better chromosome spread and visibility. Likewise, 6 hr pretreatment with CIW, fixed in PAA produced higher quality chromosome spreads than 3 hr pretreatment. Meanwhile, the use of PAA had greater efficiency than GAA in terms of slide qualities as all stages of the division were clearly observed. The use of cold ice water as pretreatment for 6 hr coupled with 24 hr fixation in 1:3 Propanoic acid-alcohol produced best spread, had clear and most visible effects on the chromosome of A. cepa. The study concluded that even though the two pre-treatment substances inhibited the spindle fibre formation during mitosis and arrested the chromosomes at metaphase, the pretreatment chemicals including the fixatives elicited a differential contraction of the chromosomes. Therefore, pretreatment of root tips with cold ice water coupled with fixation in propanoic acid-alcohol may be developed into protocol for obtaining good and high quality chromosome spread during cytological studies