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Interphase Nuclear Structure and Heterochromatin in Two Species of Corchorus and Their F1 Hybrid

Dr. M A Samad
Chief Scientific Officer
Plant Breeding Division, Bangladesh Institute of Nuclear Agriculture, BAU Campus, Mymensingh-2202

G. Kabir
Professor
Department of Botany, Rajshahi University, Bangladesh

A S Islam
Professor
Department of Botany, Dhaka Univsrsity, Bangladesh

Abstract/ Executive Summary:

Structural organization of the interphase nuclei has been a subject of the interest for cytologists for a long time (Lafontaine 1974). From previous studies of interphase nucleus by light, phase contrast, fluorescence and electron microscopy it was thought to be a resting nucleus. These studies have revealed several interesting features of the interphase nuclei, such as non-random arrangement of chromosomes, somatic association and specific orientation of chromosomes for maintenance of telophasic configurations (Patankar and Ranjekar 1984). Chromosome banding techniques found suitable for visualization of heterochromatin have been applied to study interphase nuclei. These studies were so far confined mainly to monocotyledons. Among dicotyledons, interphase nuclear structure has been studied in Anemone (Marks and Schweitzer 1974). Joshi and Ranjekar (1982) have described interphase nuclear structure in other diocotyledons using the HCI-Giemsa technique. The present experiment was designed to obtain crucial information of interphase nuclear structure in two Corchorus species and their hybrid employing to different staining techniques and also to know the role of nuclear DNA content in structural organization of interphase nuclei.

Keywords: Interphase nuclear structure, F1 Hybrid, Corchorus species

Location: Cytology labrotory, Department of Botany, Rajshahi University, Bangladesh

Start Date:

End Date:

Program Area: Variety and Species

Commodity: Jute

Objectives:

To obtain crucial information of interphase nuclear structure in two Corchorus species and their hybrid employing to different staining techniques and also to know the role of nuclear DNA content in structural organization of interphase nuclei.

Methodology:

In order to study the interphase nuclear structure and heterochromatin both the parents (Corchorus olitorius var. O-4 and C. capsularis var. D-154) and their F₁ hybrid seeds were allowed to germinate in moist filter paper in petri dishes at room temperature 30⁰C. 1-2 cm long root tips were fixed in 1:3 aceto-alcohol for 4 8hr. After fixation the root tips were transferred to 70% alcohol and kept in a refrigerator till used. Root tips were individually taken out in a slide and cut into two semgents: (a) 1.5 mm long meristematic region and (b) about 5 mm long differentiated region. They were squashed in a drop of 45% acetic acid after maceration for 10mm in IN HCI at room temperature and macerated tissue was covered with a cover glass. The cover glass was detached by inverting the slide in a tray containing ethanol. After the cover glass was separated, the slide was air dried for 2 hr. Air-dried slides, one set containing meristematic and the other differentiated cells, were processed using HCI-Giemsa method of Joshi and Ranjekar (1980) and BSG (Barium hydroside saline Giemsa) method of Summer (1972). To determine the nuclear structure, 50 nuclei from each preparation of both meristematic and differentiated region were examined under the microscope. From each nucleus the number of chromocentres (dark position) was counted as chromocentres corresponding to heterochromatin (Nagl and Fusenig 1979). The percentage of heterochromatin values was obtained by determining the area of the nucleus and of chromocentres by planimetry. The heterochromatin values were expressed as percent nuclear area. Deoxyribonucleic acid (DNA) isolation from seed samples was done following the combined procedures of Malik and Singh (1980) and Ogur and Rosen (1970).

Source of Information: Journal, Cytologia 57:21-25, 1992

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Heterochromatin values yielded by HCI-Giemsa technique were slightly higher than those yielded by BSG treatment. The percentage of heterochromatin in F₁ was found to be closer to the male parent.

Knowledge Management: Journal