Fish Chromosomes

Angel Amores amores at OREGON.UOREGON.EDU
Sat Jun 10 00:49:42 EST 1995

>I wish to hear some informations on fish molecular cytogenetics. As you may
>know, fish chromosomes do not clearly show its banding pattern. By 1988, I
>can not see the clear data on fish chromosome banding pattern. Only we could
>see C-, NOR-banding patterns in a few species. We know that one of the
>reason derive from the direct method for chromosome preparation. So, some
>scientists try to prepare clear chromosomes through primary cell culture.
>Now we need to develop how to make the clear banding pattern including
>high-resolution chromosme banding. The modern banding techniques could help
>to understand the assignment of some genes on the chromosomes. Thus, this
>could promote our understandings about the relationship between the
>confirmation of gene locus by RAPD and the real locus. If somebody know the
>reproducible banding techniques, please let me know it.

If you plan to do chromosome mapping, I would recomend you to use the
replication banding technique. It's the only banding technique in fish
which allow unequivocal identification of every chromosome.
The main advantage of using tissue cultures is to obtain a higher number of
metaphases and of higher quality.
However, both the cell culture and the replication banding conditions are
quite variable between different fish species. For high size fish, I would
recomend you lymphocyte cultures, for medium size fish use lymphocyte or
cultures and for small fish, use fin cultures or embryo cultures if
available. In my experience, fibroblast cultures (from fin or embryos) grow
much better using embryo extract in the medium. I've been using embryo
extract from medaka, zebrafish, trout or seabream and all of them work fine
in all different marine and freshwater species (althogh zebrafish seems to
grow better with zf embryo extract).
The replication banding conditions are variable for different species. As
the basis of the technique is the incorporation of 5-bromodeoxyuridine
(BrdU) during half of the synthesis, the incubation time is quite variable
(from 12 to 3 hours) depending on the cell cycle lengh of your fish.

Here are some references.

general interest
*Chromosoma (1988) 96: 178-183; *Chromosoma (1988) 97: 101-114

papers with G-banding
Can. J. Zool. (1991) 69: 2826-2830; Cytologia (1991) 56: 199-208; Cytologia
(1992) 57: 443-453; Cytologia (1993) 58: 211-215

papers with replication banding
*Cytogenet. Cell Genet. 47:80-83 (1988); Cytogenet. Cell Genet. 48: 117-120
(1988); *Chromosoma (1991) 100: 524-531; Hereditas (1994) 121: 255-265

Molecular cytogenetics papers (mainly with ribosomal gene clusters and
satellite sequences)
*Cytogenet. Cell Genet.(1993) 63: 128-130; *Cytogenet. Cell Genet. (1993)
67: 31-36 (1993); *Chromosome Research (1993)  1: 63-67; *Chromosome
Research (1993) 1: 77-86
there is also a interesting paper (*past year in Chromosome) dealing with
the chromosome mapping of the Histone cluster in salmonids.

The ones with "*" are the most recomended to start with.

Hope this helps.

Angel Amores
Institute of Neuroscience
University of Oregon
Amores at

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