Post on 23-Jan-2017
transcript
Dream comes trueWith
Genetic Engineering
Prepare by : Sumaiah Alghamdi- Norah Alhoshani
Nora alkahtani -Hind alsubaieSubmitted to :
Dr. Zinab qurni
Content • Introdiction• Example of genetic engineering
application• Reengineering a transmembrane protein • Gentically modified insect• Egg engineering• References
What is the latest fashion?
1 -Fluorescent dresses Yumi Katsura
1-Fluorescent dresses ..cont • The researchers inserted
glowing proteins, borrowed from corals and jellyfish, into the silkworm genome near the gene for the silk protein fibroin. They then raised more than 20,000 transgenic silkworms, which expressed fibroin proteins with the fluorescent molecules attached, and collected their colorful cocoons.
1-Fluorescent dresses ..cont
2-Silkworms produce artificial spider silk
• A research has succeeded in producing transgenic silkworms using piggyBac capable of spinning artificial spider silks.
• PiggyBac is a piece of DNA known as a transposon that can insert itself into the genetic machinery of a cell.
• The genetically engineered silk protein produced by the transgenic silkworms has markedly improved elasticity and strength approaching that of native spider silk.
2-Silkworms produce artificial spider silk
3 -Fluorescent fish • Researchers in Hong Kong have developed a fish that
glows in the presence of estrogen-like chemicals called estrogenic endocrine disruptors
• Scientists inserted a green fluorescent protein gene into the genome of the medaka fish and positioned it next to a gene that senses estrogen
4-Stronger dogs• Scientists in China say they are the
first to use gene editing to produce customized dogs. They created a beagle with double the amount of muscle mass by deleting a gene called myostatin.
• The dogs have “more muscles and are expected to have stronger running ability, which is good for hunting, police (military) applications,”
5 -Blue rose • researchers in Suntory’s Institute for Plant Science
using advanced technology to reduce the levels of red/purple color and isolating the blue pigment gene from pansy and hybridizing to that of a rose, could this tinge of blue be created.
• The transgenic carnation and rose also contain selectable marker genes for herbicide resistance in carnation and antibiotic resistanc in rose.
6 -Invisibility cloaks• Researchers using arrays of minuscule 'elements' that bend, scatter,
transmit or otherwise shape electromagnetic radiation in ways that no natural material can. And many metamaterials researchers are trying to make cloaking a reality, can used for military
6 -Invisibility cloaks
Reengineering a
transmembrane protein
Gentically modified
insect
Egg engineerin
g
Reengineering a transmembrane protein to treat muscular
dystrophy using exon skipping
Introduction to Muscular dystrophy
Normal Dystrophin gene
Main areas of muscle weakness in different types of dystrophy
Dystrophin Glycoprotein Complex (DGC)
• Dystrophin and its associated proteins localize to the muscle plasma membrane, acting as a linker between cell “skeleton” to connective tissue in muscle fibers.
• Mutations that disrupt the dystrophin glycoprotein complex (DGC) cause muscular dystrophy.
Sarcoglycan sub complex
• The sarcoglycan sub complex within the DGC is composed of 4 single-pass transmembrane subunits: α-, β-, γ-, and δ-sarcoglycan.
• Recessive loss-of-function mutations in
genes encoding α-, β-, γ-, and δ- sarcoglycan cause the limb girdle muscular dystrophies (LGMD) type 2D, 2E, 2C, and 2F, respectively.
limb girdle muscular dystrophies (LGMD)
• The sarcoglycan complex is localized at the muscle membrane, and loss-of-function mutations in mice and humans result in the absence of plasma membrane–associated staining.
• LGMD 2C patients have mutations in SGCG, the gene encoding γ-sarcoglycan.
Exon skipping • Is a type of gene therapy by
using which blocks translation using antisense oligonucleotide.
• is a strategy in which an antisense oligo-nucleotide is used to coax cells into skipping an exon (region of genetic instructions), splice together remaining exons and produce a functional protein.
SGCG, Mini_ Gamma
Mini-Gamma’s capacity to substitute for full-length γ-sarcoglyca.
Mini_ Gamma rescues Drosophila muscular dystrophy
• Full-length murine γ-sarcoglycan (mGSG) localized to the sarcolemma when expressed in Sgcd840 muscle ,indicating that the mGSG normally translocates in Drosophila muscle.
Mini_ Gamma rescues Drosophila muscular dystrophy
• Expression of murine MiniGamma showed the same distinct plasma membrane localization when expressed in Sgcd840 flies.
• Expression of MiniGamma in Sgcd840 hearts also showed plasma membrane–associated staining in the thin-walled heart tube structure.
Measure Drosophila heart function
• Optical Coherence Tomography (OCT) was used to measure heart tube dimension during both contraction and relaxation.
• Sgcd840 flies had dilated heart tubes with significantly increased end systolic dimension (ESD) compared with WT
• Expression of Mini-Gamma in the heart tube was sufficient to restore ESD to WT dimensions.
Drosophila activity monitor
Gentically modified insect
Introduction
Insect responsible for economic and social harm worldwide through the transmission of disease to humans and animals, and damage to crops.
Their genetic modification has been proposed as a new way of controlling insect pests.
However, regulatory guidelines governing the use of such technology have not yet been fully developed.
Current Insect Control Strategies
•Indoor spraying.•Use of insecticide-treated bed nets
Insecticides
•Is the sterile insect technique in which laboratory-reared male insects
• Removal of breeding sites around human habitations.
Alternative Control Strategies
Genetic Modification of Insects
• Genetically modified (GM) insects are produced by inserting new genes into their DNA.
• Many genes have been identified that can alter the behaviour and biology of insects.
• When these genes are inserted into an insects genome they are called transgenes, by injecting DNA containing the desired genes into the eggs of insects.
Researchers use a wide variety of transgenes, derived from a variety of
organisms, to modify insects:Marker genes are used to make the insects fluoresce, these allowresearchers to distinguish them from the unmodified variety, whichis important for monitoring them in the environment.Lethal genes cause the insect to die, or make it unable toreproduce .
Refractory genes confer resistance to a particular pathogenrendering the insect unable to transmit the disease any longer.
Potential Control Strategies: Scientists have proposed two distinct strategies involving the
release of GM insects.
1. Population suppression: is a method in which insects are engineered to ensure that when they mate with wild individuals no viable offspring are produced or producing progeny that died before they can transmit disease.
2. Population replacement: strategies involve permanently replacing wild populations of insects with GM varieties( anti-pathogen gene) that have been altered to render them less able to transmit disease..
Paratransgenesis insect
Paratransgenesis was first conceived by Frank Richards (1996)
Paratransgenesis is a technique that attempts to eliminate a pathogen from vector populations through transgenesis of a symbiont of the vector. The goal of this technique is to control vector-borne diseases.
Engineer Triatominae express proteins such as Cecropin A that are toxic to T. cruzi or that block the transmission of T. cruzi.
INSECTS GENES CHARACTER MODIFIED
1. Anopheles SM 1 Disease causing ability destroyed
2. Culex Defensin Disease spreading ability is lost
3. Silkworm Spider flagelliform silk
Enhances quality of silk protein
4. Wolbachia Attacin and Cecopin
Infective capacity is lost
5. Xylella S 1 Disease causing capacity is absent
Introduced transgenes in insect
How GM mosquito
work
How GM mosquito
work
How GM mosquito
work
Conclusion
The Potential Benefits of GM Insect StrategiesThey would target only a single insect pest
species, leaving beneficial insects unharmed.GM insects could reduce the need for
insecticides and any associated toxic residues in the environment.
When used in disease control programmes GM insects would protect everyone in the area.
Egg engineering
EGG ENGINEERS
In a technical tour de force, Japanese researchers created eggs and sperm in the laboratory. Now, scientists have to
determine how to use those cells safely and ethically
Introduction
• Ince last October, molecular biologist Katsuhiko Hayashi has received around a dozen e‑mails from couples, most of them middle-aged, who are desperate for one thing: a baby. One menopausal woman from England offered to come to his laboratory at Kyoto University in Japan in the hope that he could help her to conceive a child.
• The requests started trickling in after Hayashi published the results of an experiment that he had assumed would be of interest mostly to developmental biologists. Starting with the skin cells of mice in vitro, he created primordial germ cells (PGCs), which can develop into both sperm and eggs. To prove that these laboratory-grown versions were truly similar to naturally occurring PGCs, he used them to create eggs, then used those eggs to create live mice. He calls the live births a mere ‘side effect’ of the research, but that bench experiment became much more, because it raised the prospect of creating fertilizable eggs from the skin cells of infertile women. And it also suggested that men’s skin cells could be used to create eggs, and that sperm could be generated from women’s cells.
BACK TO THE BEGINNING
• In the mouse, germ cells emerge just after the first week of embryonic development, as a group of around 40 PGCs2. This little cluster goes on to form the tens of thousands of eggs that female mice have at birth, and the millions of sperm cells that males produce every day, and it will pass on the mouse’s entire genetic heritage. Saitou wanted to understand what signals direct these cells throughout their development.
• Over the past decade, he has laboriously identified several genes including Stella, Blimp1 and Prdm14 that, when expressed in certain combinations and at certain times, play a crucial part in PGC development 3–5. Using these genes as markers, he was able to
BACK TO THE BEGINNING
select PGCs from among other cells and study what happens to them. In 2009, from experiments at the RIKEN Center for Developmental Biology in Kobe, Japan, he found that when culture conditions are right, adding a single ingredient bone morphogenetic protein 4 (Bmp4) with precise timing is enough to convert embryonic cells to PGCs2. To test this principle, he added high concentrations of Bmp4 to embryonic cells. Almost all of them turned into PGCs2. He and other scientists had expected the process to be more complicated.
Hayashi way
• Hayashi tried to use epiblast cells Saitou’s starting point but instead of using extracted cells as Saitou did, he tried to culture them as a stable cell line that could produce PGCs. That did not work. Hayashi then drew on other research showing that one key regulatory molecule (activin A) and a growth factor (basic fibroblast growth factor) could convert cultured early embryonic stem cells into cells akin to epiblasts. That sparked the idea of using these two factors to induce embryonic stem cells to differentiate into epiblasts , and then to apply Saitou’s previous formula to push these cells to become PGCs. The approach was successful.
• To prove that these artificial PGCs were faithful copies, however, they had to be shown to develop into viable sperm and eggs.
Cont.. The process by which this happens is complicated and ill
understood, so the team left the job to nature Hayashi inserted the PGCs into the testes of mice that were incapable of producing their own sperm, and waited to see whether the cells would develop6. Saitou thought that it would work, but fretted. “It seemed like a 50/50 chance, But, on the third or fourth mouse, they found testes with thick, dark seminiferous tubules, stuffed with sperm. The team injected these sperm into eggs and inserted the embryos into female mice. The result was fertile males and females
Cont..• They repeated the experiment with induced pluripotent
stem (iPS) cells mature cells that have been reprogrammed to an embryo-like state. Again, the sperm were used to produce pups, proving that they were functional — a rare accomplishment in the field of stem-cell differentiation, where scientists often argue over whether the cells that they create are truly what they seem to be. “This is one of the few examples in the entire field of pluripotent-stem-cell research where a fully functional cell type has been unequivocally generated starting from a pluripotent stem cell in a dish,” says Clark.
Cont..
They expected eggs to be more complex, but last year, Hayashi made PGCs in vitro with cells from a mouse with normal colouring and then transferred them into the ovaries of an albino mouse. The resulting eggs were
fertilized in vitro and implanted into a surrogate .
CLINICAL RELEVANCE Saitou and Hayashi have found that the offspring generated by their technique usually seem to be healthy and fertile, but the PGCs themselves are often not completely ‘normal’. For example, the PGCs can produce eggs that are fragile, misshapen and sometimes dislodged from the complex of cells that supports them1. When fertilized, the eggs often divide into cells with three sets of chromosomes rather than the normal two, and the rate at which the artificial PGCs successfully produce offspring is only one-third of the rate for normal in vitro fertilization (IVF).
CLINICAL RELEVANCE
But the most formidable challenge will be repeating the mouse PGC work in humans. The group has already started tweaking human iPS cells using the same genes that Saitou pinpointed as being important in mouse germ cell development, but both Saitou and Hayashi know that human signalling networks are different from those in mice. Moreover, whereas Saitou had ‘countless’ numbers of live mouse embryos to dissect, the team has no access to human embryos. Instead, the researchers receive 20 monkey embryos per week from a nearby primate facility .
Yi Zhang, who studies epigenetics at Harvard Medical School in Boston, Massachusetts, and who has been using Saitou’s method, has also found that in vitro PGCs do not erase their previous epigenetic programming as well as naturally occurring PGCs. “We have to be aware
that these are PGC-like cells and not PGCsPGCs”,
...Thanks
References
• http://phys.org/news/2010-09-scientists-genetically-silkworms-artificial-spider.html#nRlv
• http://www.the-scientist.com/?articles.view/articleNo/30670/title/Fluorescent-fish-find-pollution/
• http://onlinelibrary.wiley.com/doi/10.1002/adfm.201300365/full• http://www.technologyreview.com/news/542616/first-gene-edited-dogs-reported-in-c
hina/• http://www.nature.com/news/exotic-optics-metamaterial-world-1.13516• http://www.jci.org/articles/view/82768•http://www.nature.com/news/stem-cells-egg-engineers-1.13582• file:///C:/Users/SAMSUNG/Downloads/postpn360-gm-insects.pdf• http://www.jbiol.com/content/8/4/40/figure/F2?highres=y • http://www.mdpi.com/1422-0067/10/12/5350• https://www.systembio.com/downloads/Manual_PiggyBac_Web.pdf