Preparation of lampbrush chromosomes dissected from avian and reptilian growing oocytes

Lampbrush chromosomes represent transcriptionally active chromosomes that exist during the extended diplotene phase in the growing ovarian eggs of many vertebrate animals, except therian mammals. They are excellent for studying chromosome structure and aspects of RNA transcription. Because of their giant size they allow a great increase in the resolution for physical gene mapping. Lampbrush chromosomes have no connection with the nuclear envelope, and can be manually dissected from living oocyte nuclei. Here we present the complete protocol for lampbrush chromosome microsurgical isolation from avian and reptilian germinal vesicles. These chromosome preparations can be further used for fluorescence in situ hybridization (FISH) and immunostaining.The research was carried out under project 15-04-05684 financed by Russian Basic Research Foundation. V. V. was supported by a grant from the Saint Petersburg State University (1.42.961.2016)