Saturday, May 28, 2011

Dna Paternity Testing

In Part 1 of this article, we discuss some of the most common non-standard that is used to obtain DNA from an individual for DNA testing. In this article we look at the success rates of DNA extracted from different types of samples and how these may vary from sample to sample.

non-standard samples does not always guarantee that a DNA profile obtained. While for the buccal swabs can not get DNA, as in cases where the smear was not done properly or else mold grows swabs due to wet conditions of storage, general problems with these samples are usually less than 2%. Therefore, depending on the nature of the sample, not usually associated with a high probability, medium or low success in extracting DNA from each sample type (in some cases provides a percentage chance of success).

High (80%)For samples such as fresh blood stains or hairs with roots that, by a qualified DNA laboratory experience, is considered relatively simple DNA extraction. In such cases, provided that the sample was properly handled, both during collection and delivery to the laboratory, you can expect a high probability of success in extracting DNA.

Half (50% -60%): For samples such as cigarette butts, toothbrush or the success rate is influenced by a number of variables including face intensive use of light and / or storage conditions , etc. So the butt of a great smoked cigarettes at an ashtray at home is more likely to result in a successful DNA extraction lightly smoked a cigarette that has been lying in the street and exposed to atmospheric agents (rain, for example).

Under (20% - 30%) for samples such as teeth or bone, where DNA extraction is a process that consumes relatively difficult and time, these usually need to be managed by a highly specialized laboratory. In such cases, the person should consult with the first laboratory to check your level of experience, if they accept the sample and cost.

The above classification is however only a guideline, since as we have seen is not only the type of sample that is important, but also other variables that can influence, such as:

1. Poor storage conditions (for example, a damp environment, extreme heat, etc.)

2. Poor sample handling (possible contamination with DNA from other soil or touching the sample)

3. Not enough DNA present (eg heavily used toothbrush against used only once)

It is also important to note that the rate of success will depend largely on the ability of the laboratory performing the test. Not all laboratories that can perform DNA paternity testing with normal samples are able to obtain DNA from a wide variety of other media. The most difficult of the media (eg, teeth and bones), the greater the expertise and experience needed to increase the chance of a successful DNA extraction.

Finally, it is also important to note that non-standard samples, there is always the risk that the extraction will not work. So anyone considering the submission of the sample, especially where there may be a limited sample available (for example, a person has died) should take this into account. Selection of an experienced laboratory (possibly forensic specialist) will help minimize this risk.

Friday, May 20, 2011

RNA Interference

RNA interference (RNAi) or double-stranded RNA (dsRNA) is a system within living cells that help control which genes are active and how active they are. siRNAs were first discovered by David Baulcombe's group in Norwich, England, as part of post-transcriptional gene silencing (PTGS) in plants1 and subsequently independently identified in a wide variety of eukaryotic organisms. These dsRNAs are rapidly processed into short RNA duplexes of 21 to 28 nucleotides in length, which then guide the recognition and ultimately complement the division of single-stranded RNA, including messenger RNA or viral genomic / antigenomic RNA (Fig . 1). According to their source or function, naturally small RNA have been described: short interfering RNA (siRNA), repeat-associated short interfering RNA (siRNA rasiRNA o) and microRNA (miRNA). RNA interference has many biological functions - is a vital part of the immune response against viruses and also reduces the expression of genes through transcriptional silencing of genes upregulated or promoted by the activation of RNA. Finally, the artificial introduction of long dsRNA or siRNA has been adopted as a tool to inactivate gene expression in both cultured cells and in living organisms.

A biochemical understanding of RNAi pathway is essential to realize that dsRNAs less than 30 base pairs (bp) could be used to trigger an RNAi response in mammals. Tuschl and colleagues demonstrated that transfection of mammalian cells with short RNAs can induce sequence-specific RNAi pathway and therefore exceeded the barrier to the use of RNAi as a genetic tool mammals2. The impetus for using siRNAs and other small RNAs in mammalian cells also came from the long view that the receptor protein kinase (PKR) activation3 and similar responses have been triggered by short dsRNAs effectively. After initial reports, it took a very short period of time to siRNAs triggers to be adopted as a standard component of the toolbox of molecular biology. siRNAs can be introduced into mammalian cells using a variety of standard transfection methods. The intensity and duration of the silencing response is determined by several factors: a population basis, the silencing response is affected mainly by the overall efficiency of transfection, which can be addressed by optimizing the conditions. In each cell, silencing depends on the amount of siRNA that is delivered and the potential of each siRNA to suppress its target, or its power. Even a relatively powerless siRNA can silence its target, provided that sufficient amounts of siRNA were delivered. However, essentially "forcing" the system by providing large amounts of reagent can give rise to many undesirable effects.

Tuesday, May 17, 2011

Computer Forensics Introduction

When you hear of computer forensics, the first thing on the mind can be a researcher at the crime scene, pulling the plastic sheet out of a computer and inspection for signs of a struggle. In fact, no one ever spoke of forensic medicine in everyday life until they started making Primetime police scientifically accurate, so of course, simple word association in general, leads to forensic science is "something that cops do, right? "

Indeed, the science behind computer forensics is not really very different from forensic science from the crime scene. In either case, the team of forensic experts or looking for a trail of evidence. In any case, the researcher analyzes what has happened, determines how that happened and notes that this could be responsible.

The main difference is that while a researcher at the scene of a robbery or violent crime is looking for physical evidence, computer forensic investigator is looking for digital evidence.

Curiously, the physical evidence can often be misleading, confusing, ambiguous and difficult to meet without the help of witness statements, digital evidence tends to occur in a much more direct.

A computer that keeps track of almost everything has been done with it. For example, in addition to their browsing history, there is also the temporary Internet folder, which stores information from the web on your computer. For example an employee is watching news all day when they are supposed to be working. Even if they are smart enough to clear your browser history, temporary Internet files may still be the evidence that will win them a warning.

That's just a very simple example, of course. Computer forensics addresses everything from cybercrime to the misconduct of employees, such mundane tasks as finding out why your antivirus is not working.

The point is that everything you do on a computer that leaves a mark. Delete a file from your hard drive is not the same as removing all evidence that they exist. Like all the rooms in your house have any DNA evidence, be it a hair, saliva, or cutting toenails, no matter how good vacuum and shampoo your carpets, there is some evidence that this is your home. The same is true with computers. You can not do anything on a computer without a computer expert to be able to find exactly what you've been doing.

One issue that many find confusing in regard to computer forensics ... and legal, is it really?

This depends on the context. Here's everything you need to know if you are thinking of hiring a team of computer forensics, but not sure if you can:

If you suspect an employee of breaking company policy or even break the law with a computer that belongs to the company, you have the right to take a look at the computer that has been working at any time.

It gets a bit more difficult when an employee is working on your own computer. This is not a dead end, but can be a bit more complicated. Luckily, there always have to look at his computer for evidence of what they have done on your computer. In any case, go ahead and call your people forensics, and you should be able to advise you on how far you can collect the evidence they need to take action.

In fact, computer forensics is simply the art of finding a trail of evidence on computers, plain and simple. You never know when you will have such services, so it's a good idea to keep in mind if ever.