Saturday, October 2, 2010

Designer Babies

Thanks to our knowledge in genetics and medical technology’s always improving, doctors are now able to screen the in-vitro patients, soon to be children for genetic defects and diseases. The women can now choose specific traits for their children such as blood type, athleticism and capability to fight of diseases. This is all possible because of our understanding and ability to do genetic mapping. The main screening process used is preimplantation genetic diagnosis (PGD), and this detects genetic and natural diseases just by looking at a few of the embryo’s cells. These trouble spots in the DNA sequence are then suppressed or interrupted or fixed to stop any genetical defects or diseased occurring

There are many positives about this and also some negatives. It is positive because of all the diseases that will be stopped before they can start in the children prolonging their lives and making them healthier. The more negative side to this science is that people are screening and choosing specific phenotypes and traits and making “designer babies”. This has caused a lot of ethical problems with this developing research.

Wednesday, June 2, 2010

Genes important to sleep discovered

Sleep is a behaviour that is common in all animals but the reason to how lack of sleep can affect the animal’s condition requires further investigation. A study was done to look more closely at this behaviour from sleep and activity patterns of 40 different lines of 3,500 of wild Drosophila melanogaster (fruit flies) at the genetic level as it may contribute to the understanding of human sleep. Fruit flies normally sleep 12 hours a day. The researchers found out that the fruit flies were homozygous but the lines were different and each one of these flies were placed in a small glass tube which were connected to a machine that monitored the activity of the flies every minute using infrared sensors. The study found that in male flies, the duration of sleep was longer than female flies on average. Also, males slept more during the day and were more active when awake than females. Almost 1700 genes were identified in the study and some were not known to have an effect on the variability of sleep in fruit flies before this study was conducted. Some genes that were thought to have an effect on sleep duration were verified by separate mutations in those important genes and effects on sleep duration were observed. They also found mutants that survived on little to no sleep - one to two hours a day or none at all. The sleepless flies had a mutation of a particular gene and they have named Sleepless. “They believe the Sleepless gene encodes a protein that affects whether potassium ion channels in the brain stay open or closed. When the channels are open, the brain is connected and working – the fly is awake. When closed, the channel shuts down and the fly sleeps. The insomniac fruit flies had less of the Sleepless-produced protein.” Groups of genes that affect sleep were identified in the study and now there is a greater understanding of how genes relate to sleep.
Sleep is regulated by two processes known as circadian and homeostatic. Circadian regulation affects the timing of sleep, and the homeostatic mechanism affects the need for sleep. The Sleepless gene affects the homeostatic mechanism.
Sleep is not just for humans ,it has been observed in everything from flies to dogs to people, indicating that it's essential to life. Insufficient and poor-quality sleep is an increasing problem in industrialized nations. In the U.S. alone, about 70 million people suffer from chronic sleep problems, which reduce workplace productivity, affect quality of life and can even be lethal. Therefore, we should do further investigation to have a better understanding of how genes relate to sleep.
By 42282570

Tuesday, June 1, 2010

Evolution: the Raw Power of Jumping Genes

Researchers at the University of Pennsylvania School of Medicine have discovered that a kind of gene labelled "jumping genes" within a genome has extensive variations in different individuals, as found through gene mapping of these jumping gene locations. From this finding, the researchers have postulated that these jumping genes may be a driving factor in our genetic diversity. This is highlighted by the results of the study, which showed that out of the 1139 genome sites observed, approximately 285 sites would be different for any two individuals. The reason for these variations were found to be due to the jumping genes, which are essentially DNA sequences that may "jump" from one location in a cell's genome and "land" in another location within the same cell's genome.

While previously the significance of these genes influence on genetic diversity was underestimated, this study proves these genes result in large variation in genome sites and that jumping genes could thus be described as the raw force behind genetic evolution.

Also known as transposons, jumping genes can influence an organism in many ways, as even subtle changes in an organisms genome can result in distinctly different phenotypes. Every individual would have these jumping genes, which may jump and insert genetic material into new locations. This could thus result in negative effects on cell structure (like genetic diseases and cancer), creation of new genes, or decreasing the expression of genes near the jumping genes' landing site. All factors would increase the diversity of an organisms' genome.

Tuesday, May 25, 2010

DNA Sequence Itself Influences Mutation Rate

In a report published online in Genome Research, researchers have identified intrinsic properties of DNA that influence mutation rate, shedding light on mechanisms involved in genome maintenance and potentially disease.

Some DNA mutations are subject to natural selection, either conferring a biological advantage that is selected for, or a negative effect that is selected against. Mutations not under selection are said to be neutral, and the rate at which neutral mutations accumulate is reflective of the true DNA mutation rate.

Interestingly, the neutral mutation rate can vary significantly between different regions of chromosomes. Sequence high in pairs of the bases C and G (CpGs) where the C's are chemically modified, have been positively correlated with mutation rate.

Walser and Furano compared the CpG content and DNA changes in inactive L1 retrotransposons shared by humans and chimpanzees.
The researchers had previously noted that the older L1s have a lower CpG content than the younger sequences as expected, but here they observed two particularly striking features: "The overall mutation rate in the older fossil sequences dropped dramatically," said Furano, indicating a certain CpG content threshold is required to affect the non-CpG mutation rate. "And most provocatively, the types of mutations changed significantly."

This means that CpGs are not only promoting mutations, but they are also influencing how the non-CpG sequences around them are being mutated, an extension of what the authors call the "CpG effect." These findings strongly support the hypothesis that the co-variation of CpG content and non-CpG mutation rate is a property of the DNA sequence itself, and not a result of the chromosomal location.

"Intriguingly, the CpG effect revealed by our studies mimics the altered mutational state that has been demonstrated for certain cancers," Furano noted.


Raymond Ng (42161040)

Sunday, May 23, 2010

Closing on to the answer to the cause and cure of Huntington's

The use of fruit flies are helping scientists and doctors to slowly uncover the secrets revolving around huntington's disease (the cure and cause of it). They have been testing fruit fly genes too see whether there were any formation of plaque-like protein aggregates within their cells. They have discovered a small group of genes (more than 70% same for humans) which play a role in regulating the formation of these aggregates. Also they discovered that these aggregates formed in different tissues, such as those in the brain and cells. These were similar to those formed in humans.

Thus, fruit flies have allowed for scientists to find the genes which control the formation of plaque-like protein aggregates. Thus this is allowing scientists to move closer towards finding the answer to how the formations are regulated which will lead to the formation of a drug to prevent and treat these diseases. Overall proving that the fly genome is a significant factor in current and possible future discoveries, such as those of medicine for brain disease


Paul Kim (42344281)