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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HLA genes ,hla

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                 HLA 

HLA (Human  Leucocyte antigens ) were first discovered on Leucocytes.Out of the various genes for histocompatibility antigens,most of the transplantation genes are located on a portion of chromosome 6. These are called MHC(Major Histocompatibility complex) or HLA complex.The recipient immune system can recognise the Histocompatibility antigens on the donor organ and accordingly accept or reject it.

                 Haplotype

The array of HLA alleles on a homologue of chromosome 6 is known as haplotype.An individual inherits only one HLA haplotype from each parent.
* Only identical twins can have identical haplotype.
*  The best HLA matching can be observed within the same family .              

                 Tissue typing

The procedure carried out to match HLA proteins  of donor and recepient is called tissue typing.
*This is done before tissue grafting.

                    MHC antigen types

Present on cell membrane.Two types:

1) MHC-1 : present on almost all cells except RBC. 

2)MHC-11: present only on APCs(Antigen Presenting Cells) ;Macrophages,B-cells ,Dendritic cells.



For organ transplantation/Tissue grafting requires:
1)Blood group matching
2)pre and post operative steroid therapy
3) MHC matching (tissue typing)

Ques-   MHC -11 is present on:
 (A)Macrophage
(B) B -lymphocytes
(C)Dendritic cells
(D) All of these

Ans-. D

Ques-.   Tissue matching is required in which of the following:
(A) Homograft
(B) Autograft
(C) Allograft
(D) Both A and C

Ans - D
Homograft/Allograft- Tissue grafting in between the genetically dissimilar individual of the same species.(Intra species graft)

Autograft - Transplantation of tissue from one body part to another body part of an individual (most successful)

Isograft  -  Transplantation of tissue in between the individual of same genetic constitution. Example- Identical twins/monozygotic twins.

Hetero/Xenograft -  Tissue grafting in between organism of different species.

Ques-. MHC-1  is absent in 
(A) RBC
(B)  WBC
(C)  Liver cells
(D)  platelets

Ans - A

Ques-  HLA genes are majorily present on :
(A) Chromosome 9
(B)  Chromosome 6
(C). Chromosome 12
(D). Chromosome 15

Ans-.  A

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