Somatic crossing over or mitotic crossing over
Look at the cat and observe the different coloured eyes and black & white fur!
Definition: Why do you want to read this Blog?
Mitotic crossing over is synonymous with somatic crossing over, occurring in body cells or vegetative cells in an organism during embryonic development or at any point during the lifetime of an individual. Compared to common sex cells or germline cells crossing over during meiosis, mitotic crossing over is a relatively rare event. This phenomenon arises during embryonic development and gives rise to ‘Mosaic individuals,’ whereas occurring in adults may lead to cancer. However, somatic crossing over can also bestow certain individuals with advantageous benefits.
Two types of cells with different colours in the pupil Patches on the legs
Exploring the Scope: Mosaicism and Its Link to Cancer!
Whatever the cells, the crossing results exchange of genetic material between homologous chromosomes during cell division. Unlike meiosis, mitosis is a common cell division process that produces two identical daughter cells with the same genetic information as the parent cell. While crossing over takes place in between those chromosomes produces two non-identical cells. If this happens during early embryonic development, leaves diversified cells formed after crossing over which progressively differentiated into different two types of tissues which is shown as “mosaicism” or “mosaic development”. When this somatic crossing-over occurs during the lifetime, the modified cells develop new tissue, unfortunately, sometimes may be cancerous. Reasons for somatic crossing over during embryonic development is unrevealed secret, whereas, the crossing over in adult may be induced by some mutagens (carcinogenic agents) such as Chemicals like ethidium bromide, formaldehyde, arsenic and many more), physical factors such as UV rays, X-rays etc., and sometimes the Biological factors of certain retroviruses like HIV.
Exchange of chromatid material in between chromatids;
This phenomenon occurs when the chromatids of two homologous chromosomes align closely during mitosis, and genetic material is exchanged between them. Mitotic crossing over can result in genetic variation between the daughter cells, contributing to genetic diversity among the various tissues in multicellular organisms.
History of Somatic Crossing over (Curt Stern, 1931)!
Somatic crossing over or mosaicism was observed in Drosophila melanogaster (common fruit fly) in 1931, by Curt Stern in the famous laboratory of Thomas Morgan. Heterozygosity (normal) to determine the characteristics of hair shape and brown body colour mutated as bristle (curly) hair and yellow body-coloured flies. These new characteristics appeared as patches on different regions of the fruitfly body, which were termed “Twin spots” (these two characteristics appear together in that new tissues). This was termed as “mosaic development”.
Cancer development?
Prolonged exposure of certain tissue to the mutagens leads to induce changes or damage to the DNA. During old age (ageing) the genetic material becomes weak and undergoes unwanted breakage. These two factors are responsible for the breakage and exchange of chromosomal segments referred to as “Somatic crossing over”.
“Not Everyone or Every Condition is Adversely Affected by this abnormal Somatic Crossing Over!”
It’s crucial to keep in mind that the risk of cancer associated with these substances is influenced by factors such as the level and duration of exposure, individual susceptibility, and the presence of other risk factors.
-
Here is a video with a comprehensive explanation for you to go through: Click here
Somatic crossing over too has some potential benefits!
- Genetic Diversity: Somatic crossing over contributes to genetic diversity within an individual’s body. This genetic diversity can be advantageous in the face of environmental challenges, as it increases the likelihood that some cells will possess beneficial mutations or combinations of alleles that enhance their survival and functioning.
- Cellular Adaptation: Somatic crossing over can lead to the generation of cells with new genetic characteristics, which may acquire adaptive responses, such as the immune system, this genetic variation can promote the production of specialized cells with improved capabilities to combat infections or respond to changing conditions, but that adaptation could not be transferred to next generation.
- Tissue Regeneration: In certain tissues, such as the skin and gastrointestinal lining, somatic crossing over may contribute to tissue regeneration and repair. The production of genetically diverse cells could facilitate tissue renewal and healing processes.
- Evolutionary Implications: In certain organisms of asexually reproducing organisms somatic crossing over might play a role in facilitating evolutionary adaptation by the “natural selection” at the somatic cell level. Although it is not a widespread phenomenon, somatic genetic variation could confer advantages in specific situations.
Wide research is still needed on this somatic crossing over!
Further research is needed to fully understand the extent and significance of somatic crossing over in different biological processes and its potential implications for health and disease. Currently, the understanding of somatic crossing over is an active area of research in genetics and cell biology