Methods of gene transfer in plants

The successful development of the transgenic plants has made it possible to produce some of the most costly recombinant proteins and industrial enzymes at much lower costs and at much larger scale. In order to develop the transgenic plants, it is very important to transfer the gene of interest into the plant cells and successfully express it. In the following paragraphs we’ll look at the various techniques employed to transfer the gene of interest into the plants.

Vector-mediated or indirect gene transfer 

In this method the gene of interest is transferred using a vector which is usually a disarmed pathogen which contains the necessary tools required to transfer the gene in the plant cells.

The most widely used vector for gene transfer is Agrobacterium tumefaciens. This is a bacterium which is responsible for causing the crown gall disease in the plants. In order to use it for transferring the gene of interest, the Ti plasmid of the bacterium is modified by cloning the gene of interest in the T-DNA region and removing the sequence responsible for pathogenicity. Upon successful modification of the plasmid, it is introduced in the bacterium and upon infection on the plant; it inserts the gene of interest into the plant genome.

In addition to the vector mediated gene transfer method, there are various vector-less methods of gene transfer which are also termed as direct gene transfer methods.

Chemical mediated gene transfer

Chemicals like polyethylene glycol (PEG) induce the plant protoplasts to uptake the foreign DNA and incorporate it into its genome. Calcium phosphate is also used to introduce the DNA into the cultured cells.

Microinjection

This technique is used to introduce the DNA in the large sized cells such as oocytes and the early embryonic cells. The DNA is introduced inside the cell using fine tipped (0.5-1.0 micrometre diameter) needle.

Advertisements

Genes Find Their Partners Without Match-Makers

Identical segments of DNA bind together automatically without any help of other molecules, a new research finds.

Genes are segments of DNA which carry the encoded genetic information of our body. Every gene encodes a specific character or function in living beings. But, genes require regular repair due to damages.

During one of these processes of repair, named homologous recombination, a damaged gene is replaced with the same gene of an extra copy of DNA. Genetic disorders arise due to errors caused to due to replacement of genes by wrong ones. One such example is Progeria which causes rapid aging.

Recombination proteins help in copying and replacement of genes during homologous recombination process, which also aids in reproduction and evolution as it involves genes of each parent to get combined and shuffled.

A research at the Imperial College London and National Institutes of Health experimentally reveals that DNA molecules having same genetic codes pair up together without any outside help and guidance in spite of existence of 20,000 genes in human DNA and the complex network of DNA strands bundled up together into chromosomes.

The experiments proved that if two small identical DNA strands are randomly mixed up in a solution then they would independently group together with the sections of DNA similar to them.

The joint result of Harvard and Imperial study presents the proof for joining together of long identical DNA segments within the same molecule. Truly, DNA will never stop surprising us!

Looking older than your age? Genes might be a problem.

According to the journal Current Biology, people who carried a specific gene looked 2 years older than who did not carried the gene. This new study is the first time scientifically explain why some people look older than the other people in the same age, according to Manfred Kayser, a professor of forensic molecular genetics at MC University Medical Center Rotterdam.

The researchers studied nearly 2,700 older Dutch adults. In the research, the researchers showed the picture of each participants to the “judges” and asked them to estimate the ages of the people in the photos. The researchers also observed about the 8 million variations of the participants’ DNA. According to the study, it was found out that one gene variation is specifically related to people’s appearance, even though other factors such as wrinkles, skin color, gender, sun damages were included in the consideration.

In previous studies, researcher thought that the gene, MC1R, which affects the melanin synthesis, pale skin, and red hair, is closely related to the appearance of people. However, by this new study, researchers confirmed that the previous studies are wrong and a specific gene variation effects the people’s appearance.

One possibility is that this gene might affect inflammation and DNA damage repairs of our body, which eventually decides how old people look. The researchers noted, however, this gene is only a one possible factor for our appearance and there are many other factors that influences how old we look.

 

reference

http://www.livescience.com/54589-youthful-glow-is-in-genes.html

New blood test can prevent overprescription of antibiotics.

When doctors diagnose an infected patient, it is hard to determine whether the patient needs antibiotics or not, because to viral infections, different from common cold or the flu, antibiotics are not effective. Also, overprescription of antibiotics to patient can cause antibiotics-resistant infections, which are very difficult for doctors to handle, according to the study published in the journal Science Translational Medicine.

However, it is sometimes difficult for doctors to determine whether viruses or bacteria are making a patient sick, because symptoms that the patients have might be similar even though the cause of the infections are different. In this new test discovered by researchers from Stanford University, doctors can now easily determine whether an infection is viral or bacterial within few hours.

This test works by looking at the activity of our body’s immune system, which responds differently as the type of disease changes. To be specific, there are 7 genes that are responsible for giving certain molecules to our immune system to use it as a response to an infection. The level of producing those molecules, which can be measured in blood, differs depending on the type of infection, and the test can easily determine whether an infection is viral or bacterial just by measuring the level in blood.

By using this new test, doctors will be able to prevent antibiotics-resistant infections from occurring and give more accurate diagnosis to infected patients, which will lead to more successful treatment. However, the test needs to be faster and more accurate before it can be used in hospitals and clinic center, the researchers wrote.

 

Reference

http://www.livescience.com/55302-blood-test-viral-bacterial-infection.html

Genetically Modified Mice and Detect Land Mines and Decode Human Olfactory System

A breed of super-sniffer mice has been created by researchers at Hunter College (City University) New York. The mice have a heightened ability to recognize a specific odor. They can further be tuned to different sensitivity levels of smell using human or mouse odor receptors. They can be used to detect land mines and also for novel disease sensors.

It is a transgenic approach to modify the mouse genome and would also help researchers study human odor receptors. It is still not clearly understood how the olfactory system wires itself. Our noses are equipped with the combination of sensory neurons each consisting of a chemical sensor known as a receptor that is responsible for detecting odor. A receptor is selected by a neuron which is the case for humans as well as mice.

Lead investigator Paul Feinstein dabbled with mouse genome. He introduced a DNA for odor receptor transgenically by injecting it directly into the nucleus of a fertilized egg cell. He also added a string of DNA to the sequence to see the alteration of probability for the gene to be chosen. After a few attempts, he discovered a string when copied four times, worked.

To everyone’s surprise, a human receptor gene was inserted into mice successfully which helped to understand human odor coding. The team also found that mice had better sense of smell and were able to avoid unpleasant odor. These tests confirmed that the receptors were present in greater numbers in mice.

Scientists are Using Tiny Mirrors to Capture the Most Detailed 3D Images of Cell Structures Ever

While we are looking at the cells through the microscope, they only appear in the 2D shape but they do come in all 3D sizes and shapes. Clearly, a 2D image is sufficient for the basic study but if you wish to go deeper, you won’t get sufficient amount of thins to study from. With the help and collaboration of international researchers, it has been looked upon now on the ways that can overcome this problem by creation a 3D view of the cells. Such a technology will allow the scientists to gather much more information about cells.

With this tech, It has been clearly observed that a single cell is nearly 10 micrometers and inside it, there’s a nuclear core which is 5 micrometers. Below nuclear, there are tiny holes, called as ‘nuclear pore complex’ that are the gate that regulates the messenger bio-molecules, but distances between one-50th and one-20th of a micrometer. The new technology, entitled as MEANS (mirror-enhanced, axial-narrowing, super-resolution) microscopy, goes by obtaining thicknesses of the cell at various focal points, providing the researchers the capability to see the differences in layers of the cell. The method works by building cells on custom-made, small mirrors. The method works by building cells on custom-made, small mirrors. A glass coverslip is placed on top of the cells, then further, adding the mirror in place of a usual slide in a wide-field or confocal microscope.

Terminator Technology

With the increasing utilization of the genetically modified products, the probability of an exchange of the recombinant genes into the wild is a genuine matter of concern for the researchers. To address this issue, the terminator technology was anticipated as an answer by different biotech organizations. Be that as it may, this innovation has been under examination for quite a while and is still not considered as an answer for the issue.

The terminator technology includes the genetic adjustment of the plants, keeping in mind the end goal to render the sterile seeds amid the harvest. This is an inducible molecular mechanism, i.e. the gene responsible for the sterility of seeds can be turned on or off from outside by giving the suitable chemicals from outside.

The biotech organizations were projecting the terminator technology as a “biosafety” answer for keeping the spread of modified genes in the nature. As per them, if any of the modified genes get exchanged to related wild plant through cross pollination, the seeds delivered as a consequence of this will be sterile in this way avoiding further spreading of the modified gene.

However, the scientists who studied the genetic seed sterilization models, discarded the technique saying that terminator technology is not effective enough to ensure 100% sterility in all the seeds, thus there will always be a risk of contamination in the nature. Further, this strategy was seen as a technique to increase greatest benefit by the organizations by stopping the farmers from sparing the seeds and utilizing them once more.