Evolution of germline segregation processes in animal development

Gaku Kumano1

  • 1Asamushi Research Center for Marine Biology, Graduate School of Life Science, Tohoku University, 9 Sakamoto, Asamushi, Aomori, 039-3501, Japan.

Related Concept Videos

Law of Segregation01:49

Law of Segregation

When crossing pea plants, Mendel noticed that one of the parental traits would sometimes disappear in the first generation of offspring, called the F1 generation, and could reappear in the next generation (F2). He concluded that one of the traits must be dominant over the other, thereby causing masking of one trait in the F1 generation. When he crossed the F1 plants, he found that 75% of the offspring in the F2 generation had the dominant phenotype, while 25% had the recessive phenotype.
80.3K
Nondisjunction01:21

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...
5.9K
Meiosis II02:02

Meiosis II

Meiosis II entails cell division and segregation of the sister chromatids, resulting in the production of four unique haploid gametes. The steps for meiosis II are similar to mitosis, except that meiosis II occurs in haploid cells, whereas mitosis occurs in diploid cells.
The timing and cell division patterns of meiosis differ between males and females. In male meiosis, the centrosomes are part of the formation of the meiotic spindle. However, in oocytes, including that of humans, Drosophila,...
51.9K
Chromosomal Theory of Inheritance01:39

Chromosomal Theory of Inheritance

In 1866, Gregor Mendel published the results of his pea plant breeding experiments, providing evidence for predictable patterns in the inheritance of physical characteristics. The significance of his findings was not immediately recognized. In fact, the existence of genes was unknown at the time. Mendel referred to hereditary units as “factors.”
61.6K
Exon Recombination02:32

Exon Recombination

The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new gene formation. It is observed across vertebrates, invertebrates, and in some plants such as potatoes and sunflowers. During exon recombination, exons from the same or different genes recombine and produce new exon-intron combinations, which might evolve into new genes. 
Exon shuffling follows “splice frame rules.” Each exon...
4.3K
Meiosis I03:09

Meiosis I

Meiosis is the division of a diploid cell into haploid cells forming sperm and eggs in animals through differentiation. Meiosis I is the first stage of meiosis, where the genetic recombination of homologous chromosomes and the reduction of the ploidy level by half occurs.
Prophase I is the most extended and complex step of meiosis I characterized by synapsis, chromosome pairing, and recombination of the homologous chromosomes. This process is facilitated by a proteinaceous structure called the...
46.8K