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Updated: May 12, 2026
09:07
Fluorescence In Situ Hybridization on DNA Halo Preparations to Reveal Whole Chromosomes, Telomeres and Gene Loci
Published on: March 4, 2021
Genome biology: the sleek and oh-so chic Oxytricha nanochromosomes
Scott A Horrell1, Douglas L Chalker
1Biology Department, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA.
Current Biology : CB
|April 13, 2013
Abstract:
The somatic nucleus of Oxytricha trifallax contains over 15,000 different chromosomes, most containing a single gene. Analysis of this 50 Mb genome uncovers novel regulatory strategies and adaptive potential when gene copy number and allelic frequency are no longer constrained by genetic linkage.
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01:51Lampbrush Chromosomes
In 1882, Flemming observed lampbrush chromosomes (LBC) in salamander eggs. Later in 1892, Rückert observed LBCs in shark egg cells and coined the term "lampbrush chromosomes" because they looked like brushes used to clean kerosene lamps.
LBCs are made up of two pairs of conjugating homologous chromatids. Each chromatid consists of alternatively positioned regions of condensed-inactive chromatin and loosely placed-active side loops, which can be contracted and extended. The loops resemble the...
LBCs are made up of two pairs of conjugating homologous chromatids. Each chromatid consists of alternatively positioned regions of condensed-inactive chromatin and loosely placed-active side loops, which can be contracted and extended. The loops resemble the...
01:51Lampbrush Chromosomes
In 1882, Flemming observed lampbrush chromosomes (LBC) in salamander eggs. Later in 1892, Rückert observed LBCs in shark egg cells and coined the term "lampbrush chromosomes" because they looked like brushes used to clean kerosene lamps.
LBCs are made up of two pairs of conjugating homologous chromatids. Each chromatid consists of alternatively positioned regions of condensed-inactive chromatin and loosely placed-active side loops, which can be contracted and extended. The loops resemble the...
LBCs are made up of two pairs of conjugating homologous chromatids. Each chromatid consists of alternatively positioned regions of condensed-inactive chromatin and loosely placed-active side loops, which can be contracted and extended. The loops resemble the...
02:04Polytene Chromosomes
Polytene chromosomes are giant interphase chromosomes with several DNA strands placed side by side. They were discovered in the year 1881 by Balbiani in salivary glands, intestine, muscles, malpighian tubules, and hypoderm of larvae Chironomus plumosus. Hence, these are also called "Salivary gland chromosomes." These are found in insects of the order Diptera and Collembola; in certain organs of mammals; and synergids, antipodes of flowering plants. Polytene chromosomes are also regularly...
02:04Polytene Chromosomes
Polytene chromosomes are giant interphase chromosomes with several DNA strands placed side by side. They were discovered in the year 1881 by Balbiani in salivary glands, intestine, muscles, malpighian tubules, and hypoderm of larvae Chironomus plumosus. Hence, these are also called "Salivary gland chromosomes." These are found in insects of the order Diptera and Collembola; in certain organs of mammals; and synergids, antipodes of flowering plants. Polytene chromosomes are also regularly...
01:17Karyotyping
Overview
02:21Chromatin Packaging
Each human somatic cell contains 6 billion base-pairs of DNA. Each base-pair is 0.34 nm long, which means that each diploid cell contains a staggering 2 meters of DNA. How is such a long DNA strand packed inside a nucleus measuring only 10 - 20 microns in diameter?
The chromatin
In combination with specialized DNA binding protein called Histones, the DNA double helix forms a compact DNA: protein complex called chromatin. The chromatin itself is further compacted into higher-order structures.
The chromatin
In combination with specialized DNA binding protein called Histones, the DNA double helix forms a compact DNA: protein complex called chromatin. The chromatin itself is further compacted into higher-order structures.