Dosage compensation ∧ sex determination in drosophila

1. SACHIN DAS
ZOOSPHERE
7797462253

2. *Dosage compensation is the process , where the
total gene expression from single x in one sex is
made equal to total gene expression from the two x
chromosomes in the other sex . This can be
achieved either by up regulating the single x
chromosomes in one sex or down regulating the two
x chromosomes in the other or by a combination of
these mechanisms.
*Failure to achieve this compensation often lethal.
*General organization of sex determination and sex
differentiation genes in drosophila melanogaster has
been represented as follows-

3. X/A
RATI
O
SIS sxl
Sis-
a
Sis-
b
da
sn
f
Tra,
tra-2
Sxl
active
protei
n
Msl
set
Ix, dsx
Terminator
element
Primary
signal
Master
regulator
genes
Target
gene
Intermediate
regulator
genes
Terminal
regulator
genes

4. Msl-set
Ix, dsx
* mle, msl -1,2,3(four autosomal genes)
* Female splicing in xx flies and
female development progressed
.
* Repressed male development.
*Default splicing in xy flies
permits male developments ,‘ix’
gene inactive. Repress female
development.
* Male development progress.

5. X/A
RATI
O
sxl tra tra-2 dsx
HIGH
LOW
ON
OFF
ON
OF
F
DSX M
DSX
F

6. FEMAL
E
MALE
MSL-
2MSL-
2
SXL
PROTEIN
NO SXL
PROTEIN
BLOCKING
NO MSL -2 PROTEIN MSL -2
PROTEIN