Deciphering Gods Language

8/13/2019 Deciphering Gods Language

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Guided By :Dr. Vishwa Prakash Shetty

Dr. Aparna Dave

Dr. Manpreet Arora

Dr. Bhuvnesh Yadav


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Forensic is derived from the Latin word forum,which means court of law. Odontology

literally implies the study of teeth.

Forensic odontology, therefore, has been

defined by the Fdration DentaireInternational (FDI) as that branch of dentistrywhich, in the interest of justice, deals with theproper handling and examination of dental

evidence, and with the proper evaluation andpresentation of dental findings.


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Mass disasters


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Why dentists

Deceased individuals requiring identification

who sustained significant facial trauma

precludes visual identification

BECAUSE

Soft tissues does not resist the ravages of time

and environment.


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The resistance nature of dental tissues to

environmental assaults, such as incineration,

immersion, trauma, mutilation and

decomposition make teeth represent an

excellent source of DNA material. When

conventional dental identification methods

fail, this biological material can provide thenecessary link to prove identity through DNA

profiling.


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SAMPLE COLLECTION

DNA evidence collection must be performedcarefully.

-avoid contaminating the area where DNA might

be present by not touching it with your barehands, or sneezing and coughing over theevidence.

-use clean latex gloves for collecting each item of

evidence. Gloves should be changed betweenhandling of different items of evidence.

-each item must be packed separately.


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-samples should be packed in paper envelopes

or paper bags after drying.

-all types of stains must be thoroughly air

dried prior to sealing the package.

-stains on immovable surfaces such as table or

floor may be transferred with sterile cotton

swabs and distilled water.


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TECHNIQUES EMPLOYED FOR

OBTAINING DENTAL DNA

Crush entire tooth.

Conventional endodontic access.

Horizontal section of tooth with partialextirpation of coronal and radicular half of

tooth.

Horizontal section of tooth with aggressive

pulpectomy and crushing of radicular half of

tooth.


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The yield of DNA per gram of tooth powder is

approx 18.4 g.


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SALIVA

The objective of using saliva as a source is to

analyze DNA from desquamated epithelial

cells.

Salivary deposits left behind as a result of

bites can also be a potential source of DNA of

a suspect.


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A reliable method for saliva sampling from

bite-mark sites in skin is the double swabbing

techniques.


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The swabs are completely air dried and

transferred to micro centrifuge tubes.


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Saliva may also be isolated from various

sources in the crime scene, for example,

postage stamps and envelopes, glasses,

cigarettes, straws, food and chewing gum,toothbrushes and dental floss, and dental

impressions.


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Dried saliva may be difficult to detect, for

confirmation

Amylase assay

Fluorescent spectroscopy

laser


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The saliva thus collected can be dabbed onto

specialized cards.

The FTA cards (Flinders Technology Associates)

are chemically treated filter papers designed

for the collection and room temperature

storage of biologic samples for molecular

analyses.


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Blood

Blood stains are also obtained using a swab an

dabbed on to the FTA paper.


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Reference Samples

from suspects or convicted felons and

family reference samples are used in missing

persons investigations, paternity testing and

mass disaster victim identifications.

Buccal cell collection


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Storage

Most biological evidence is best preserved

when stored dry and cold.

Inside the laboratory, DNA samples are either

stored in a refrigerator at 4C or a freezer at -

20C. For long periods of time, extracted DNA

samples may even be stored at -70C.


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DNA Amplification

The polymerase chain reaction (PCR) is a

biochemical technology in molecular biology

to amplify a single or a few copies of a piece of

DNA across several orders of magnitude,generating thousands to millions of copies of a

particular DNA sequence.

Developed in 1983 by Kary Mullis.


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The final DNA concentration should be in the

range of 0.05-0.125ng/L, so that it will be

added to the PCR reaction in a volume of 10

L.


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PCR Thermocycler


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Polymerase Chain Reaction

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Gel electrophoresis

The different sized fragments are separated by a process

called gel electrophoresis

The separation takes place in a sheet of a firm but

jelly-like substance (a gel)

Samples of the DNA extracts are placed in shallow

cavities (wells) cut into one end of the gel

A voltage is applied to opposite ends of the gel

DNA has a negative charge and moves slowly towardsthe positive end

The shorter fragments travel through the gel faster than the

longer fragmentsGel electrophoresis

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Appearance of separated fragments on gel

These bands will

contain the shorter

DNA fragments

These bands willcontain the longer

DNA fragments

starting positions Appearance of bands

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Prof. E. Wood Prof. E.J.Wood

V S S S S DNA profiles 16


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V S S1 S2 S3

V Victim

S Sample from crime scene

S1 Suspect 1

S2 Suspect 2

S3 Suspect 3

More than 20 fragmentsfrom Suspect 1 match those

taken from the crime scene

DNA profiles 16


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Genetic Analyser


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E i i i


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Estimating size


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Paternity test 19


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position ofrestriction

fragment

part of DNA strand

mother father

Child will receive one copy of the restriction fragment from the

mother and one from the father. It could be any one of these

combinations

child

Paternity test 19

20


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Starting position of sample

1 2 3 4

Genetic fingerprint of

1 mother

2 child

3 possible father A

4 possible fatherB

There is a match between one ofthe childs restriction fragments

and one of the mothers.

There is also a match between the

childs other fragment and one from

possible father A.

Neither of the childs restriction

fragments match those of possible

father B

Paternity test

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Whenever dental professionals are required or

requested to provide such samples,

knowledge of sampling and storage for the

optimization of the DNA analysis procedurecan greatly enhance the efficiency of the

investigation. The dental expert needs to be

aware of relevant legal and ethical issues andoperate within the ambit of the law.


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ss

Thank you

THANK YOU

Deciphering Gods Language

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