Download Hakim Baraki Sharyn Shelton BIOL-1615

Hakim Baraki
Sharyn Shelton
BIOL-1615-021
7/26/14
The sex of human being is determined by X or Y chromosomes, and specifically Y
determines the maleness of a human and XX determines the femaleness whereas honeybees are
determined by different method like diploid and haploid. Sex determinations in honeybees are
determined by the fertilization and non-fertilization of eggs. There numbers of chromosomes are
32 in diploid females and 16 in haploid males.
This method of sex determination was first discovered by a Catholic Priest named Johann
Dzierzon around 1845. He said that “a virgin queen who hasn’t taken a mating flight produces
only male progeny”. “This was more than 50 years before researchers discovered the sex
chromosomes”. (Gampe,Hasselmann,Schiott,Hause,Otte,Beye, 2009)
According to Gempe and his colleagues “the fertilized eggs have a haploid set of 16
chromosomes with fertilized eggs, in which 32 were identified”. Heterozygous are the females
and homozygous diploid are the males. For the development the gene product is necessary for
females. “They injected dsRNA into male and female embryos to repress copies of the new
genes and record gonad differentiation. Then they used gonad differentiation as an informative
indicator of sex determination as early development”.
“The primary signal of the honeybee is a switch gene that has two states, the active
female and the non-active male. They proposed that the induction of the female pathway through
gain of complementary sex determiner (csd) activity is due to the presence of two cds proteins
derived from different alleles”.
“Molecular studies show that the determination of heterozygous state relies on the
operation of two separate but closely linked genes”. They have run a test to differentiate
testicular tubules for developed spermatids, implying that the feminizer gene controls germ cell
differentiation.
They have used the “sex -specific mRNAs” as a phenotype to identify the interactions of
sex-regulatory genes. The male pathway is the default regulatory state that doesn’t require any
“sex-specifying” control.
In sex determination “a positive feedback would generate states throughout development
is by the finding of mosaic structures in feminizer repressed females that have male or female
characters, but not an intermediate phenotype. The mosaic intersexual phenotype is consistent
with a cell free sexual differentiation in the honeybee”. According to Gempe and his colleagues
analysis, feminizer has an additional function in maintaining sex throughout development. They
have found molecular evidence in the form of “feedback splicing loop”.
Researchers examined how the female state is established and reset to the default male
state in early “embryogenesis”. It is because the male development is only made in the absence
of feminizer activity. As a continuous activity of the positive “feedback loop” it would lock eggs
into the female determined state.
Researchers have collected diploid female eggs from eight queens inseminated with
semen and different sex allele. Male eggs were collected from two queens that were “brothersister crosses” and produced half female and half male generation.
In conclusion, “sexual differentiation is a fundamental process in the animal kingdom,
and different species have variety of mechanisms to generate the two sexes in the proper
proportions”. (Gampe,Hasselmann,Schiott,Hause,Otte,Beye, 2009)The sex of human being is
determined by X or Y chromosomes, and Y determines the maleness of a male human and XX
determines the femaleness of a female. In honeybees sex are determined by method of
fertilization and non-fertilization of eggs.
Work cited
Gampe,Hasselmann,Schiott,Hause,Otte,Beye, T. (2009, 10 20). Sex determination in
honeybees: Two separate mechanisms induce and maintain the female pathway.
Retrieved from www.plosbiology.org
Gempe,Beye, T. (2014, 7 26). Sex determination in honeybees.
Retrieved from http://www.nature.com/