Dunaliella salina - Overview

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                 Dunaliella salina Dunaliella salina is a unicellular microalgae belong to division Chlorophyta . It is found in salinity environments such as salted brines, salt evaporation ponds, and hypersaline lakes  .It is able to tolerate varying NaCl concentrations, ranging from 0.2% to approximately 35% . Thus, Dunaliella salina is a hyper-halotolerant organism found in high densities in saline lakes.  The ability to tolerate high salt concentrations is advantageous, since competition is minimal in high salt concentration areas.  How D.salina   tolerate high salt concentration? D. salina has adapted to survive in high salinity environments by accumulating glycerol to balance osmotic pressure. Note :  D. salina is also adapted to solar radiation using β-carotene to protect against ionizing energy.                 Red Colour of Salt Brines  Dunaliella salina...
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Types of Twins- Identical and Non-Identical

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                           Twins

  • Twins occur when two babies are born to one mother after a single pregnancy.

                  Types of Twins

Two types:
1).  Monozygotic/Identical
2). Dizygotic/Fraternal/Non-Identical


             Monozygotic twins

  •  They're identical . They formed when one zygote, created with just one egg and one sperm, splits into two new eggs, resulting in two embryos rather than one. Each embryo then develops into a separate foetus.

                 Dizygotic twins

  • They occur when two separate eggs are fertilized by two separate sperm.
  • Dizygotic twins are the result of hyperovulation, the release of multiple eggs in a single cycle. 

Note:. 
  • Dizygotic twins share only 50% of the same genes, whereas identical twins share 100%, which explains why fraternal twins usually don't look nearly as alike as identical ones do. 


Twins from different father's?


  • Superfecundation describes a situation in which each of the eggs are fertilized by sperm from different men, leading them to have different biological fathers (making the twins half-siblings). The appropriate term to describe this situation is heteropaternal superfecundation.

Research : There is little research on the prevalence of heteropaternal superfecundation in the general population, but some researchers found that in a parentage test database of 39,000 records, 2.4% of dizygotic twins whose parents were involved in paternity suits were a result of heteropaternal superfecundation.


  • Case Reported: In New Jersey, a mother of twins underwent paternity testing when applying for public assistance. After the test showed that her partner was only the father of one of her twins, she admitted that she had had sex with another man within the same week that her twins were conceived.Other case is reported in Texas.


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