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Lampbrush chromosome. Lampbrush chromosome are a special form of chromosome found in the growing oocytes (immature eggs) of most animals, except mammals. They were first described by Walther Flemming and Ruckert in 1882. [1] Lampbrush chromosomes of tailed and tailless amphibians, birds and insects are described best of all.
These regions of chromatin that have not been transcribed are located at the ends of the loops that were formed by the sister chromatids of a lampbrush chromosome. [2] Each chromomere can have up to several pairs of loops from lampbrush chromosomes originating from it, as well as micro-loops that cannot be detected with a light microscope. [6]
Lampbrush chromosome from the cell nucleus of an ovarial egg from Triton sp., a salamander. Harold Garnet Callan FRS FRSE (15 March 1917, in Maidenhead – 3 November 1993), [1] known as Mick Callan, was an English zoologist and cytologist. [2] He is especially remembered for his work on Lampbrush chromosomes.
An oocyte (/ ˈ oʊ ə s aɪ t /, oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction.In other words, it is an immature ovum, or egg cell.An oocyte is produced in a female fetus in the ovary during female gametogenesis.
These intensive RNA biosynthese are mirrored in the structure of the chromosomes, which decondense and form lateral loops giving them a lampbrush appearance (see Lampbrush chromosome). Oocyte maturation is the following phase of oocyte development. It occurs at sexual maturity when hormones stimulate the oocyte to complete meiotic division I.
A well known balanced lethal system is the one fixed in the genus Triturus (containing the crested and the marbled newts). [4] Each of the homologous chromosomes of pair 1 (1A and 1B) has a different recessive deleterious allele on a non-recombining section of the chromosome. [2]
Micropia is the name of a family of LTR retrotransposons widespread in the genomes of fruitflies of the genus Drosophila. [1] [2] Micropia retrotransposons in some species of Drosophila express a male germline-specific and meiotic-specific antisense transcript complementary to the reverse transcriptase (RT) and ribonuclease A (RNaseA) genes of the proviral retrotransposon. [3]
Chromosomes display a banded pattern when treated with some stains. Bands are alternating light and dark stripes that appear along the lengths of chromosomes. Unique banding patterns are used to identify chromosomes and to diagnose chromosomal aberrations, including chromosome breakage, loss, duplication, translocation or inverted segments.