Heterochromatin organization and chromosome mapping of rRNA genes and telomeric DNA sequences in the burbot Lota lota (Linnaeus, 1758) (Teleostei: Gadiformes: Lotidae)

Figures & data

Table 1. Restriction enzymes and chromosome digestion conditions.

Name	Recognition sequence	Final concentration (U μl^–1)	Optimal incubation time at 37 °C (h)
AluI	AG↓CT	0.3	1.0
DdeI	C↓TNAG	0.5	2.3
HinfI	G↓ANTC	1.5	4.5

Figure 1. Giemsa-stained karyotypes of the burbot, Lota lota after C-banding (a) and digestion with the restriction endonucleases DdeI (b), AluI (c) and HinfI (d); m: metacentric chromosomes, sm: submetacentric chromosomes, st-a: subtelo-acrocentric chromosomes. Scale bar = 10 μm.

Table 2. Chromosomal distribution of C-positive heterochromatin and regions resistant to restriction endonucleases in the burbot.

Banding technique	Location of C-positive bands and undigested chromatin on particular chromosomes
	entire p-arm	entire q-arm	pericentromeric	terminal
				p-arm	q-arm
C-banding	16	6, 7	1, 8, 9, 11, 16–20	8, 10, 11, 17	–
DdeI treatment	16	6, 7, 12, 19	1–11, 16–18, 20–24	–	–
AluI treatment	–	7, 16	3	–	–
HinfI treatment	–	7	1, 5, 6, 8–11, 13–22, 24	–	2–4

Figure 2. DAPI-stained karyotype of the burbot Lota lota. The bottom row shows the NOR-bearing chromosome pair (no. 19) after sequential DAPI/chromomycin A₃/silver nitrate staining. Scale bar = 10 μm.

Figure 3. FISH mapping of 28S (arrows) and 5S (arrowheads) rDNA clusters to metaphase chromosomes of the burbot Lota lota stained with DAPI. Scale bar = 10 μm.

Figure 4. FISH mapping of telomeric sequences to chromosomes of the burbot Lota lota stained with DAPI. Scale bar = 10 μm.