Thursday, July 22, 2010

Deoxyribonucleic Acid (DNA) Fingerprinting


ABSTRACT

DNA Fingerprinting technique, introduced by Prof. Alec Jeffrey's is widely used presently all over the globe especially for forensic purposes. All living things are composed of different cells and within the cells except red blood cells and few other minor types contain a chemical component called Nucleus. And within the nucleus of each cell is located a genetic material, referred as Deoxyribonucleic Acid (DNA). It is this genetic material which generates genetic pattern of an individual and has shown highly polymorphic among individuals.

INTRODUCTION

It was in 1944, Oswald Avery (1) described De-oxy-ribonucleic Acid (DNA) as the vehicle of generational transference of heritable unit. Later in 1985, Prof. Alec Jeffrey's, while studying myoglobin genes discovered that certain regions of DNA showed variations in the number of tandem repeats. These are known as, Variable Number of Tandem Repeats (VNTR) (2,3). These VNTR's are highly polymorphic and hence are utilized for the forensic purposes.

DNA fingerprinting technique is considered a powerful technique and is widely used all over the globe today. This technique helps in establishing the identity of an individual. It has proved a great help to the justice community. DNA being somatically stable and resistant to environmental degradation has made it a unique tool to be used in forensic medicine (4). Bomjen et al (5,6) has shown that DNA can be extracted from biological samples which were stored at various temperatures and for different of interval of time.

Before DNA test is performed on any biological sample, it is mandatory that the sample should be collected, preserved and transported in a proper format for further analysis so as to maintain the chain of custody and moreover to carry out the proper analysis .

COMMON BIOLOGICAL SAMPLES ENCOUNTERED:

  • Whole Fresh Blood
  • Blood Stain
  • Seminal Stain
  • Hard Tissues (Bones)
  • Soft Tissues (body organs)
  • Hair

METHODS OF COLLECTION:

· Whole blood Sample: Sterile needle should be used while withdrawing or collecting blood.

· Blood stain: Should be picked up preferably on sterile cotton gauge using sterile forceps and blade.

· Seminal stain: Should not be touched by hand especially the stain portion. Should be picked up with sterile forceps.

· Hard Tissues: Bones-- bones should be picked up using gloves, Kept at a place where there are no chances of environmental contamination. It should be allowed to dry completely.

· Soft Tissues: Body organs should be collected using forces and wearing gloves. It should be kept in a sterile container.

· Hair: Hair roots are preferred for the analysis. Hair roots should be picked up using sterile forceps.

PRESERVATION:

· Whole Blood: Blood should be collected in sterile container containing an anticoagulant. The mostly preferred is EDTA. It should be mixed properly but gently for some time. The container should be covered with parafilm to avoid slippage. Should be kept it at 40C or using ice during transportation till it reaches laboratory for analysis.

· Blood stain: Blood stain should be dried properly. In semi dry stain there, is a possibility of bacterial growth thus chances of having contamination. Drying should be avoided using electric fans. After complete drying it should be wrapped in a fresh blotting paper and packed in a Zip lock poly bag. No preservative is required. It can be transported at environmental temperature.

· Seminal stain: Likewise seminal stain should also be dried properly. In semi dry stain there, is a possibility of bacterial growth thus chances of having contamination. It should not be dried using electric fans. After drying it should be wrapped in a fresh blotting paper and packed in a Zip lock poly bag. No preservative is required. It can be transported at environmental temperature.

· Hard Tissue: No preservative is required. The hard tissues should be wrapped in the blotting paper and placed in a zip lock poly bag.

· Soft tissue: It should be placed at 40C or in Ice till it reaches laboratory for analysis.

· Hair: Hair roots should be placed in a blotting paper and then packed in a zip lock poly bag. It requires no preservative and can be transported at environmental temperature.

FORWARDING:

· After packing all these zip lock poly bags, they should be numbered and sealed. Each sample, even from the same case should be sealed separately. The seal has to be from the office of the forwarding authority. The covering letter should bear the signature of the forwarding authority and a copy of seal should be enclosed. Wherever photographs are to be attached, the forwarding authority or Doctor collecting blood sample should attest them. While collecting fresh blood, there should be the signatures of minimum two (2) witnesses.

· For forwarding other biological samples also, the signature of minimum two witnesses is required.

REPORTING:

Different labs have different protocols.

· There should be the covering letter, either from HOD or Head of the Institute mentioning the name of the person who has carried out the analysis. Also, it should be mentioned who should be called for disposing evidence in the court.

· The report should mention the exhibits examined with the number given by the forwarding authority or the one decoded by the laboratory

· In case of matching, report should indicate what are the points considered for it, by marking arrows.

· It should be evident that the bands in the child are those determined from each parent.

· Preferably, the molecular weight marker should be run along with DNA extracted from the biological samples.

· The name of the probe (s) or primers should be mentioned.

· The DNA sample of an unrelated individual should also be run along with the DNA samples extracted, pertaining to a particular case.

· A negative control should also be run so as to check the contamination or unspecified product.

Fingerprint ..Personal Identity By Fingerprints


Development of Fingerprint

Fingerprint ridges are formed during the third to fourth month of foetal development and their formation completed by the sixth months The ridges, thus, formed during the foetal period do not change their course or alignment throughout the life of an individual, until destroyed by decomposition of skin, after death.

ANATOMY OF FINGER SKIN


The skin consists of two main layers: the outer skin or epidermis, and the inner or true skin, known the dermis. The epidermis is constantly being worn away and replaced by new skin generated by the upper layer of the dermis - a papillary layer (stratum mucous) which is the source of the ridges known as 'papillary ridges'.
The sweat glands, located in the dermis, discharge sweat at the skin surface through sweat pores found at the top of the ridges.

ARCH


These are characterized by a slight elevation in the ridges which enter on one side of the fingerprint pattern and exit on the opposite side.
The arches are of two subtypes- Plain Arch and Tented Arch. In this no delta formation occurs.

PLAIN ARCH

In the plain arch that there is no delta and no significant core. Because there is no delta this pattern, by default, has to be an arch. If you study the image and look at the overall pattern you notice that the pattern area tends to just flow through the print with no significant changes. This makes it a plain arch pattern.


TENTED ARCH


The tented arch pattern consists of at least one up thrusting ridge, which tends to bisect superior ridges at right angles, more or less. The tented arch does make a significant change and does not have the same "easy" flow that the plain arch does. The technical definition is that a tented arch has a "significant up thrust" where a plain arch does not.

LOOP


Loops constitute between 60 and 70 per cent of the patterns encountered. In a loop pattern, one or more of the ridges enters on either side of the impression, recurves, touches or crosses the line of the glass running from the delta to the core, and terminates or tends to terminate on or in the direction of the side where the ridge or ridges entered. There is one delta. On the right you will see a loop pattern. You will notice that it has one delta (shown in the blue box) and a core (shown in the red box). By definition the existence of a core and one delta makes this pattern a loop. Loops are classified not only by the fact that they have one delta and one core but also by something called a ridge count. Loops are two kinds, 'radial' and 'ulnar', named after the radius and ulna, the two bones in the forearm. The radius joins the hand on the same side as the thumb, and the ulna on the same side as the little finger.

ULNAR LOOP

In order to distinguish between ulnar and radial loops you must: 1) Know from which hand the loop pattern comes from and; 2) place your hand palm side down over top of the impression and determine if the recurving ridges originate from the little finger side or the thumb side. If the ridges flow in from the little finger side this would be an 'ulnar' loop.

RADIAL LOOP


If the ridges flow in from the thumb side this would be a 'radial' loop.
Now, if you were to place your right hand up to the screen and make the same comparison you would find that the pattern area now tends to come in and go out towards your thumb. It so happens that the radial bone in your arm is on your thumb side so now this loop would be considered a radial loop

WHORL


The whorl pattern consists of one or more free
recurving ridges and two points of delta. When the line of the fingerprint disc is placed on the two points of delta, it will bisect at least one of the ridges belonging to the core group. Between 25 and 35 per cent of the patterns encountered consist of whorls. In a whorl, some of the ridges make a turn through at least one circuit. Any fingerprint pattern which contains 2 or more delta's will be a whorl pattern. In the scheme of classification you can make the assumption that if a pattern contains no delta's then it is an arch, if it contains one (and only one) delta it will be a loop and if it contains 2 or more it will always be a whorl.

PLAIN WHORL


The technical definition of a plain whorl is a whorl which consists of one or more ridges which make or tend to make a complete circuit, with two deltas’, between which an imaginary line is drawn and at least one recurving within the inner pattern area is cut or touched.

Sunday, July 11, 2010

She Is


Now a days i have a problem
I cant stay alone
Everywhere i find her
I think i need to befriend dis company of hers

She walks with me, eats with me, talks with me n fights with me
She never leaves me even for a moment
A shadow disappears when its dark, but she always remains with me all d time
I think i need to get habituated with dis habit

How has she changed me
How did she made dis heart to beat for her
How did she made her place so important
How had she changed me so much

U r in drops of d due
U r in d tear drops
U r d directions of d world
U r d city with the heart
U r d best news
U r d smile on my face
U r d empty place of my heart

I walk in the skies
I try to raise all are time when u fall
I imagine n wish
I feel the fear of being lost
I neither feel like sleeping nor do i feel like waking
I am on my way finding myself
I might be silly, but serious enough to tell that u r my world n my everything

Friend


Today I found a friend,
Who knew everything I felt.
She knew my every weakness,
And the problems I've been dealt.

She understood my wonders,
And listened to my dreams.
She listened to how I felt about life and love,
And knew what it all means.

Not once did she interrupt me,
Or tell me I was wrong.
She understood what I was going through,
And promised she'd stay long

I reached out to this friend
To show her that i care
To pull her close and let her know
How much I need her in my heart
I always wanted to look into her eyes n speak

I went to hold her hand
To pull her a bit nearer
To tell she means to me a lot
To tell she is my precious
When i came to her
I realized that this perfect friend I found
Was nothing but my mirror
My image
Myself
Me in as form of another.