Mitosis in meristem cells of onion root tips (Allium cepa L.)
School demonstration of mitotic figures of the dividing spindle. The collage shows all the key phases of the life cycle of mitotically dividing cells. So let's repeat: prophase...metaphase...anaphase...telophase...interphase...
Determination of karyotype by staining meristem cells of root tips (Solanum sp.)
Cytological examination is a common breeding technique used to detect deviations from the normal karyotype. Although today it is slowly being replaced by automatic cytometers for simplicity and speed of determination, it is still attractive for its low investment equipment, consumables and, of course, accuracy. The difficulty lies mainly in the need for skill and patience when collecting, storing and processing the material.
The figure below demonstrates the karyotype series within the genus Solanum.
a, c) 4n somatic hybrid of dihaploid S. tuberosum (2n) + S. bulbocastanum (2n) shows a total of 48 chromosomes. a) example of a top and side view of a metaphase plate, magnification 400x, stained with lactopropioorcein. c) magnification 1000x, stained with acetoorcein. b) dihaploid S. tuberosum (2n) - 24 chromosomes are visible in the cytoplasm, magnification 1000x, stained with acetocarmine. d) hexaploid S. bulbocastanum (6n) - due to the large number of chromosomes in the nucleus, the field of view is less clear and counting is thus more difficult, magnification 1000x, stained with acetoorcein. Chromosome shortening in all preparations was achieved by pretreatment in 0.3% colchicine.
