Development of drosophila

Development of drosophila

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  Development in Drosophila By KAUSHALKUMAR SAHU Assistant Professor (Ad Hoc) Department of Biotechnology Govt. Digvijay Autonomous P. G. College Raj-Nandgaon ( C. G. )
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  •Introduction •About Drosophila •Genome ofDrosophila •Life cycle •Differentiation •Development of Drosophila * Embryonic development * Dorsal -ventral and * Anterior posterior development * Body segmentation * Homeotic gene •Conclusion •Reference
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  r All multicellular organismsbegin their life cycle as single cells from which their various tissues and organs develop through differentiation. All life forms undergo metamorphic changes in form, shape or substance [ typically one thinks of tadpoles turning into frogs and insect larvae turning into pupae and then into butterflies, flies , moths etc]
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  Drosophila melanogaster isa fruit fly a little insect about 3mm Long which accumulates around spoiled fruits its is also one of The most valuable of organisms in biological research , Particularly in genetics and developmental biology. Drosophila Has been used as a model organism for research for almost A century and today several thousand scientists are working on Many different aspects of fruit fly . Drosophila has four pairs of chromosomes the x/y sex Chromosomes and autosomes 2,3 and 4. the size of genome Is about 165 million bases and contains estimated 14,000 genes. Thus development can be define as the formation of different Types of tissues , organs , cells . About Drosophila Genome of Drosophila
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  The drosophila lifeCycle consist of number of Stages: Embryogenesis,3 larval Instar,prepupal,pupal & adult stage.
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  * In multicellularorganisms , different body parts like kidney , liver , heart ,stomach, brain etc. differ each other in structure and function. • They occupy specific position in all the individuals of species . • This development in the different individuals lies in the fact that the sequence of regulatory events is identical in all the individuals of a species . • In the oocytes some mRNA is already present whose protein product is responsible for the further development and differentiation of embryo. • Egg fertilization initiates intense protein synthesis very rapid DNA replication and cell division. Differentiation
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  Development is regulatedby many genes which act in Predetermined and order. Drosophila development are Classified into three groups :- • Maternal genes are expressed during oogenesis and are responsible for the formation of gradients in the egg. 2. Zygotic genes/segmentation genes are expressed after fertilization and determine the number and polarity of segment. 3. Homeotic genes govern the identity of a segment. • Development begins before fertilization of the egg. • Development continues after fertilizations with Development in Drosophila Embryonic development
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  Specific pattern ofgene expression in the various stages Of embryonic development. 3. Early embryogenesis occur very rapidly without cell growth. the large egg initially contains two haploid nuclei- the male and female pronuclei. 4. They then fuse to produce the diploid nucleus of zygote, which in turn divides about 9 times to yield a large single cell called a synctium containing about 512 nuclei. 5. The nuclei migrate to the surface of the egg and undergo four additional divisions. 6. Cell membrane then form around each nuclei to produce the blastula containing about 4000 cells.
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  1. In drosophiladifferentiation of embryo along the dorsal- ventral axis depends on the action of the transcription factor encoded by the dorsal gene. 2. This protein is synthesized maternally and stored in the cytoplasm of the egg. 3. At the time of blastoderm formation the dorsal protein enters the nuclei on the ventral side of the embryo. 4. On the opposite side of the embryo where the dorsal protein is excluded from the nuclei twist and snail are repressed and consequently these cells differentiate into embryonic epidermis. 5 The entrance of the dorsal transcription factor into ventral nuclei and its exclusion from the dorsal nuclei therefore initiate differentiate along the dorsal- ventral axis Development of Dorso -Ventral axis
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  1.The anterior-posterior axisin drosophila is created by the synthesis of transcription factor encoded by the hunchback and caudal gene. 2. These two genes are transcribed in the nurse cell of the maternal jerm line. 3.The maternal transcripts of the hunchback and caudal genes are then carried unto the oocyte where they become uniformly distributed in the cytoplasma. 4.The hunchback RNA is translated only in the anterior part and the caudal RNA is translated only in the posterior part. 5.This differential translated produces concentration gradients of the proteins encoded by these two genes; hunchback protein is concentrated in the anterior part of the embryo and caudal protein is concentrated in the posterior part. Development of Anterior-Posterior axis
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  1. In manyinvertebrates the body consist of adjoining units called segment. 2. The formation of anterior-posterior axis are generated by the action of maternal genes. 3. In the next step development is the formation of discrete regions that are determined go give rise to different body parts. 4. Segmentation mutants identify the zygotic genes. 5. The segmentation genes are expressed after fertilization and product forms transverse bands that differentiate individual regions on the anterior-posterior axis. 6.These two protein then function to activate transcription of those gene whose product are involved in the differentiation of the embryo along its anterior-posterior axis. Body Segmentation
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  These genes actduring embryogenesis and control the identity of a segment and they do not change the number of polarity or size of segments . The homeotic genes ensure the unique differentiation of each segment. Mutation in these genes cause cells of one compartment to develop the phenotype of a different compartment. Homeotic genes
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  All multicellular organismbegin their life cycle as Single cells from which they develop through Differentiation. Drosophila is so popular & it was mostly used in genetics,developmental biology,etc.
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  Reference Book Author 1.Science ofbiology 2.Cell & Cell biology 3.WWW.britanica. online.com 4.WWW.author stream.com Purves et al Gray S.Stein & Arthur B.Pardee