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Lampbrush Chromosomes

Lampbrush 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...

Lampbrush Chromosomes

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During meiosis, chromosomes occasionally separate improperly. This occurs due to failure of homologous chromosome separation during meiosis I or failed sister chromatid separation during meiosis II. In some species, notably plants, nondisjunction can result in an organism with an entire additional set of chromosomes, which is called polyploidy. In humans, nondisjunction can occur during male or female gametogenesis and the resulting gametes possess one too many or one too few chromosomes.

Nondisjunction

Nondisjunction

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate correctly and move to the opposite poles of the cells. This produces daughter cells with abnormal chromosome numbers. Nondisjunction is common during anaphase I or anaphase II of meiosis. Mutations in synaptonemal complex proteins that attach homologous chromosomes increase the chances of nondisjunction in anaphase I of meiosis I. In contrast, mutations in topoisomerases and condensins that hold...

Formation of Species

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Speciation describes the formation of one or more new species from one or sometimes multiple original species. The resulting species are discrete from the parent species, and barriers to reproduction will typically exist. There are two primary mechanisms, speciation with and without geographic isolation—allopatric and sympatric speciation, respectively.

Polytene Chromosomes

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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...

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Updated: Apr 8, 2026

Manipulation of Ploidy in Caenorhabditis elegans

Manipulation of Ploidy in Caenorhabditis elegans

Published on: March 15, 2018

Polyploidy in Amphibia.

Michael Schmid¹, Ben J Evans, James P Bogart

¹Department of Human Genetics, University of Würzburg, Würzburg, Germany.

Cytogenetic and Genome Research

|June 27, 2015

Summary

This summary is machine-generated.

This review covers amphibian polyploidy, detailing origins, mechanisms, and implications for sex chromosome evolution in anurans and urodels. It explores polyploid systems in various amphibian groups.

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Area of Science:

Amphibian genetics and evolution
Polyploidy research
Reproductive biology

Background:

Polyploidy, the state of having more than two sets of chromosomes, is a significant evolutionary force in eukaryotes.
Amphibians, particularly anurans (frogs and toads) and urodels (salamanders), exhibit diverse polyploid systems.
Understanding polyploidy in amphibians provides insights into genome evolution and speciation.

Purpose of the Study:

To review the current knowledge of extant genuine polyploid amphibian species.
To discuss the origins and mechanisms of polyploidization in amphibians.
To explore the evolutionary consequences of polyploidy, including its relationship with sex chromosome evolution.

Main Methods:

Literature review of existing studies on amphibian polyploidy.
Analysis of meiotic pairing configurations and diploidization processes in polyploid genomes.
Examination of hybridogenesis and polyploid systems in specific amphibian taxa.

Main Results:

Identification and summary of known extant genuine polyploid anuran and urodelan species.
Discussion of spontaneous and experimental amphibian polyploid origins.
Detailed description of polyploid systems in key amphibian groups.

Conclusions:

Polyploidy is a recurring phenomenon in amphibian evolution with diverse origins and mechanisms.
Polyploidization influences genome stability, reproductive strategies like hybridogenesis, and sex chromosome evolution.
Further research into amphibian polyploid systems can illuminate broader evolutionary processes.