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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What Are Lichens?

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Lichen: Symbiotic association between algae and fungi.
Algae component also called as Phycobiont.
Fungi component also called as Mycobiont.
General features:
*Can grow in inhospitable and desicated environment ;prefer to grow in moist and shady places.
*Slow growing perennial.
*According to some scientist, they show Helotism(controlled parasitism).

Special structures in the thallus of lichens:
1)Breathing pores-Gaseous exchange in outer cortex.
2)Cyphole-Gaseous exchange in inner cortex.
3)Cephalodia-Absorption of moisture.Also helps in Nitrogen fixation.

Types of Lichens:
1)Crustose lichen- Shape is earth crust like,attached to substratum through rhizoids.
Example-Graphis,Dermatocarpon,Laconora.

2)Foliose lichen-Leaf like fleshy,attached to substratum through rhizoid hairs.
Example-Parmelia,Pelligera

3)Fruiticose lichen- Most advanced,branched ,possess fruiting bodies,attached to the substratum through attachmenr disc.
Example-Cladonia,Bryonia,Euernia,Usnea.
4)Squamulose-Composed small,often overlapping scales called squamules.They are like intermediate between crustose and foliose.They consist faltist units clustered together.


Reproduction in Lichens:
1)Fragmentation
2)Soredia formation(spore formation)
Soridiospores are formed inside Soridia or Sori 
3)Isidia formation(bud formation)
Isidia are specialised buds helps in propagation.This bud also helps in photosynthesis.
4)Sexual reproduction-sexe
a)Spermatogona     b) Carpogonia


Importance of Lichens:
*Air pollution indicator- Lichen cann't grow in SO2 polluted area,carry out phaeophitication of chlorophyll (degradation of chlorophyll).

*Pioneer of vegetation- Lichen helps in succession ,in soil formation by weathering of rocks example Usnea.

*Edible- 
Cladonia  rangifera   -  Raindeer moss
Cetraria   islandica     - Ireland  moss
Laconora                      -  Bread of heaven
Permalia                       -Rock flower

*Source of dyes and litmus -
Rocell (litmus)
Dryorchil (dye)

*Source of Medicine-
Usnic acid -obtained from Usnea,Evernia
Usnic acid used in ointments for wounds anf burns.

*Forest fire - by usnea,burn under high light intensity.

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Parthenogenesis

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