Introduction to Drosophila melanogaster as a model system
Drososphila melanogaster is a very popular model organism to study the various disease like Cancer,
Parkinson ’s disease, Alzheimer’s, etc. in humans due to its 75 percent homology with disease
causing genes in humans. Drosophila is a favorable model due to its specific features like fecundity,
easy maintenance, short life cycle, very low comparative costs for propagation, screening, rapidity of
studies, powerful genetics and much more. Drosophila genes can easily be manipulated and their
phenotypic and behavioral effects can be observed.
Since most of the signaling pathways in Drosophila is conserved and due to the ability to easily
manipulate their genes, they are a useful model organism to study cancer biology. They can help in
the studies of various cancers like brain, blood, liver and thyroid cancers. In spite of some
limitations, because of the anatomical differences between flies and humans, Drosophila’s cancer
models can be used to understand basic cancer specific characters such as the competitiveness of
cancer stem cells (CSCs), the importance of tumor microenvironment, drug resistance and tumor-
associated vasculogenesis, which was recently found to be functionally conserved in fly’s cancer.
Additional cancer hallmarks such as genomic instability, resistance to cell death, cell metabolism
reprogramming, tumorpromoting inflammation and evasion from the immune system, have been
studied and extensively characterized in Drosophila.
Drosophila has a complex nervous system and conserved neurological function which allows it to be
an ideal model organism for the study of neurodegenerative diseases such as Alzheimer’s and
Parkinson’s, which are becoming more prevalent in today’s ageing population. Drosophila possesses
a complex nervous system of around 100,000 neurons which allows it to elicit complex neuronal
tasks, such as learning and memory, similar to that in humans. Potentially, human disease genes can
also be used to replace endogenous copies of their Drosophila orthologues, allowing expression of
the human disease gene under the control of endogenous enhancer/promoter elements of the fly.
References:
R Stephenson, NH Metcalfe, (2013), Drosophila melanogaster: a fly through its history and current
use, 43 (70–75)
Mirzoyan Z, Sollazzo M, Allocca M, Valenza A, Grifoni D, Bellosta P, (2019), Drosophila melanogaster:
A Model Organism to Study Cancer, 51
HYE Chan, NM Bonini, HYE Chan1 and NM Bonini, (2000), Drosophila models of human
neurodegenerative disease, 7 (1075-1080)
,PART I
2
, EXPERIMENT 1
Aim: Familiarization with stereomicroscope for observing Drosophila melanogaster
Requirements: Stereomicroscope, etherizer, ethanol, brush, petri plates, adult Drosophila
melanogaster.
Theory:
History of Stereomicroscope
Stereomicroscope is also known as a dissecting microscope. It was first designed by Cherudin
d’Orleams in 1677 by making a small microscope with two separate eyepieces and objective
lenses. Later in 1852, an inventor named Charles Wheatstone describe the principle of
stereoscopic visualization and published it with the title ‘On Some Remarkable, and Hitherto
Unobserved, Phenomena of Binocular Vision’. It was later advanced by John Leornld Riddell
who equally published it on the journal of Micrscopical Science as ‘On Binocular Microscope’.
The first true stereomicroscope was developed in the med-19th century by Francis Herbert
Wenham. His design of stereomicroscope include an achromatic prism to split the light beam.
The microscope design built by Wenham became known, but it suffered from artifacts
produced by single lens and did not actually produce a true stereoscopic effect.
In the early 1890’s, Horatio S. Greenough, an American instrument designer, introduced a
novel design and convinced Carl Zeiss Company of Jena to produce the microscope, but instead
of incorporating Greenough’s lens erecting system, Zeiss engineers designed inverting prisms
to produce an erect image. This stand withstood so long and still favourite for many specific
applications.
The first modern stereomicroscope was introduced in the United States by the American
Optical Company in 1957. The company named Cycloptic developed it for the first time, which
allowed observer to increase the magnification from 0.7x to 2.5x in five steps.
In 1959, Bausch and Lomb introduced stereomicroscope to compete with the Cycloptic, but
with a cutting-edge advance that is, continuously variable or zoom, magnification. It was the
first stereomicroscope without erecting prisms and was fashioned around the basic Greenough
design.
Stereomicroscope and its parts
Stereomicroscope is an optical microscope that is designed for low magnification observation
of a specimen. It uses the reflected light rays from the specimen surface instead of transmitted
light rays. It provides low power magnification as compared to compound microscopes. It
magnification power ranges from 5x to 80x. it produces a 3D image of the specimen rather than
a flat image. Dissecting or stereomicroscope contains two separate objective lens and eyepiece
lens which creates two separate optical paths for each eye. As a result, it creates a 3D image of
the specimen. Its magnification power is the product of magnification of eyepiece and objective
lens.
3
, Parts of a stereomicroscope
4
Drososphila melanogaster is a very popular model organism to study the various disease like Cancer,
Parkinson ’s disease, Alzheimer’s, etc. in humans due to its 75 percent homology with disease
causing genes in humans. Drosophila is a favorable model due to its specific features like fecundity,
easy maintenance, short life cycle, very low comparative costs for propagation, screening, rapidity of
studies, powerful genetics and much more. Drosophila genes can easily be manipulated and their
phenotypic and behavioral effects can be observed.
Since most of the signaling pathways in Drosophila is conserved and due to the ability to easily
manipulate their genes, they are a useful model organism to study cancer biology. They can help in
the studies of various cancers like brain, blood, liver and thyroid cancers. In spite of some
limitations, because of the anatomical differences between flies and humans, Drosophila’s cancer
models can be used to understand basic cancer specific characters such as the competitiveness of
cancer stem cells (CSCs), the importance of tumor microenvironment, drug resistance and tumor-
associated vasculogenesis, which was recently found to be functionally conserved in fly’s cancer.
Additional cancer hallmarks such as genomic instability, resistance to cell death, cell metabolism
reprogramming, tumorpromoting inflammation and evasion from the immune system, have been
studied and extensively characterized in Drosophila.
Drosophila has a complex nervous system and conserved neurological function which allows it to be
an ideal model organism for the study of neurodegenerative diseases such as Alzheimer’s and
Parkinson’s, which are becoming more prevalent in today’s ageing population. Drosophila possesses
a complex nervous system of around 100,000 neurons which allows it to elicit complex neuronal
tasks, such as learning and memory, similar to that in humans. Potentially, human disease genes can
also be used to replace endogenous copies of their Drosophila orthologues, allowing expression of
the human disease gene under the control of endogenous enhancer/promoter elements of the fly.
References:
R Stephenson, NH Metcalfe, (2013), Drosophila melanogaster: a fly through its history and current
use, 43 (70–75)
Mirzoyan Z, Sollazzo M, Allocca M, Valenza A, Grifoni D, Bellosta P, (2019), Drosophila melanogaster:
A Model Organism to Study Cancer, 51
HYE Chan, NM Bonini, HYE Chan1 and NM Bonini, (2000), Drosophila models of human
neurodegenerative disease, 7 (1075-1080)
,PART I
2
, EXPERIMENT 1
Aim: Familiarization with stereomicroscope for observing Drosophila melanogaster
Requirements: Stereomicroscope, etherizer, ethanol, brush, petri plates, adult Drosophila
melanogaster.
Theory:
History of Stereomicroscope
Stereomicroscope is also known as a dissecting microscope. It was first designed by Cherudin
d’Orleams in 1677 by making a small microscope with two separate eyepieces and objective
lenses. Later in 1852, an inventor named Charles Wheatstone describe the principle of
stereoscopic visualization and published it with the title ‘On Some Remarkable, and Hitherto
Unobserved, Phenomena of Binocular Vision’. It was later advanced by John Leornld Riddell
who equally published it on the journal of Micrscopical Science as ‘On Binocular Microscope’.
The first true stereomicroscope was developed in the med-19th century by Francis Herbert
Wenham. His design of stereomicroscope include an achromatic prism to split the light beam.
The microscope design built by Wenham became known, but it suffered from artifacts
produced by single lens and did not actually produce a true stereoscopic effect.
In the early 1890’s, Horatio S. Greenough, an American instrument designer, introduced a
novel design and convinced Carl Zeiss Company of Jena to produce the microscope, but instead
of incorporating Greenough’s lens erecting system, Zeiss engineers designed inverting prisms
to produce an erect image. This stand withstood so long and still favourite for many specific
applications.
The first modern stereomicroscope was introduced in the United States by the American
Optical Company in 1957. The company named Cycloptic developed it for the first time, which
allowed observer to increase the magnification from 0.7x to 2.5x in five steps.
In 1959, Bausch and Lomb introduced stereomicroscope to compete with the Cycloptic, but
with a cutting-edge advance that is, continuously variable or zoom, magnification. It was the
first stereomicroscope without erecting prisms and was fashioned around the basic Greenough
design.
Stereomicroscope and its parts
Stereomicroscope is an optical microscope that is designed for low magnification observation
of a specimen. It uses the reflected light rays from the specimen surface instead of transmitted
light rays. It provides low power magnification as compared to compound microscopes. It
magnification power ranges from 5x to 80x. it produces a 3D image of the specimen rather than
a flat image. Dissecting or stereomicroscope contains two separate objective lens and eyepiece
lens which creates two separate optical paths for each eye. As a result, it creates a 3D image of
the specimen. Its magnification power is the product of magnification of eyepiece and objective
lens.
3
, Parts of a stereomicroscope
4
