Class Notes (786,783)
Canada (482,282)
Anthropology (827)
Lecture

Anthro Notes

4 Pages
69 Views
Unlock Document

School
Western University
Department
Anthropology
Course
Anthropology 2235A/B
Professor
Eldon Molto
Semester
Fall

Description
Anthro Notes – Nov. 22/12 - Use of mtDNA in historical cases: For forensics, mtDNA has several advantages over nuclear DNA when using degraded tissues and shed hairs – 1. High copy number per cell = greater probability of getting DNA from degraded samples. 2. Maternal inheritance only (no recombination of gender lines as is found with nuclear DNA). 3. Higher but generally stable mutational rate (10x greater) found in the noncoding region, which is composed of hypervariable regions 1 and 2. Comparisons are made easy by comparing the CRS differences between exemplar and evidentiary samples. - The mitochondrial genome was fully sequenced in 1981 by Anderson. It has 16,569 bases. RCRC (revised Cambridge reference sequence) was verified by Andrews in 1999. HV1 and HV2 are the regions generally used in forensic cases. mtDNA has a high copy number. Nuclear DNA has 2 copies per cell. It is inherited from both parents and is unique to an individual. mtDNA has more than 1000 copies per cell. It is maternally inherited and is not unique to an individual. Maternal inheritance of mtDNA makes it easier to trace people over time among maternal relatives. Genealogical sleuthing is difficult. HV1 (16024-16365) and HV2 (73-340) are the regions used to distinguish between maternally related individuals. The high mutation rate is still stable over many generations (~30 generations). - Comparing two samples using mtDNA hypervariable regions relative to the CRS: The two samples have 5 mutational differences in the HV1 and HV2 regions relative to the CRS sequence. As well, all of the mutations are the same. They are likely from the same mtDNA maternal lineage (in this case they are siblings). In forensics, when a missing person is represented by bone and the suspected individual has a maternal relative, the results of the evidentiary sample and the relative are compared. If they match you cannot exclude this individual from being from that mtDNA lineage. - Determining the probability of a match: If samples match (share the same mtDNA polymorphisms) they are then compared to the FBI database. There are currently 4839 profiles in the database. If the profile you are testing is in the database, use “n” from the racial category in which it is found. If the profile is unique, use the total database and calculate the 95% confidence interval. You can also produce a match using Bayesian stats and likelihood ratios. - Problems with mtDNA analysis: mtDNA is very prone to contamination because of high copy number and PCR selectivity (this requires a clean lab facility). It has low probative value compared to STRs (usually 1/1000-2000 at the 95% confidence interval). - Contamination controls: There are stringent procedural controls to prevent modern contamination. Careful laboratory practices include experiments are carried out in a clean lab facility, protective clothing is worn, and sterilization of equipment and reagents occurs. Negative controls are used. Labs are dual-throughput and unidirectional. - Romanov story: On July 16, 1917 at the height of the Bolshevik revolution in Russia, Czar Nicholas II, Czarina Alexandra, four daughters (Olga, Maria, Tatyane, and Anastasia) and one son (Alexei) were executed by firing by their Bolshevik captors. There were four additional victims including the family physician Dr. Botkin. Six months later, Russian investigator Nicholas Sokolov recovered valuable evidence from a gravesite, but found no skeletons (he hypothesize that evidence was destroyed). In April 1989, Russian filmmaker Geli Ryabov announced that he knew where the Romanovs were buried. He and a geologist found the grave 10 years earlier and retrieved three skulls. In 1991, Boris Yelsin authorized the exhumation of a mass grave and 1000 bone fragments were assembled into five females and four males. Two of the deceased were missing (the bodies of Alexei and a female were allegedly burned). Russian scientists concluded that Tsarevich and Maria were missing. Dr. Maples, a forensic anthropologist from Florida, believed that the grand-duchess Anastasia was missing. In 1992, research began on DNA work at the FSS conducted by Dr. P Gill to solve the mystery using nDNA and mtDNA. Five individuals were clearly related and three were female siblings. A sample of mtDNA suspected to belong to Alexandra matched a sample provided by her grandnephew the Duke of Edinburgh. In 1994, the body of grand duke Georgij Romanov (28-year-old brother of Czar Nicholas who died of TB in 1899) was exhumed and sampled (part of the tibia and femur). - Anthropological analysis: William Maples, a forensic anthropologist from Florida, used skeletal evidence, dental records, and computer images of faces and claimed to have identified Czar Nicholas II, his wife Alexandra, three of their children, three servants, and the family doctor. There was some disagreement between Maples and the Russian scientists as to the identity of two of the other bodies. The Russians thought that the missing female was Maria, but Maples insisted it was Anastasia. - DNA analysis: In Sept. 1992, Pavel Ivanov carried samples to England to test them at Forensic Science Service lab (FFS). The FSS was also involved in the first voir dire in R. vs. Morin. DNA testing of several STR loci and amelogenin was done to test relationships among the nine individuals. mtDNA analysis was conducted to confirm that the family was indeed the Romanovs. The remains of Nicholas’ brother were sampled because of heteroplasmy. STR genotypes from the nine skeletons were grouped together. A postulated pedigree was created. The children have alleles that are inherited from their parents. The alleles from the excluded group included the three servants and the doctor. Sex testing identified four males and five females. The son Alexei and one daughter (Anastasia) were missing. This does conclusively identify them as the Romanovs. The Czar’s living nephew Tikhon Kulikovsky refused to cooperate and would not provide a sample to identify the Czar’s remains. Later, two other distant relatives Xenia C-Sfiri and the Duke of Fife agreed to help. Their mtDNA matched each other and it also matched the sample believed to be from Czar Nicholas II at seven mtDNA loci. At mtDNA locus 16169 there was heteroplasmy with the Czar’s sample (T/C). The living relatives had base T at this locus. This heteroplasmic problem necessitated exhuming the remains of Nicholas’ brother. When there is one base difference between an exemplar and an evidentiary sample, the result is deemed a weak match. In the case of heteroplasmy, the result is a stronger weak match. Heteroplasmy is where two distinct populations of mitochondria exist in the same individual. The rate of heteroplasmy was found to be 70%. The work was done at the armed forces DNA identification laboratory (AFDIL). Georgij Romanov’s mitotype matched Nicholas’ exactly, including the heteroplasmic site. This makes the RMP even stronger. This was conclusive evidence that the bodies found were the Romanovs. - The Romanovs and the Anna Anderson case: At the same time as the research was being conducted, a woman Anna Anderson claimed to be the missing Anastasia. Anna appeared in Russia in 1920 after WWI and was hospitalized after attempting to commit suicide. She claimed to have amnesia. Those caring for her noted how she resemble Anastasia (rumours about her survival were rife in post-war Europe). Anna Anderson married an American, moved to Virginia, and died in 1984. A supporter of the hypothesis that she was Anastasia was the grand-daughter of the Romanov’s doctor. She (Schweitzer) obtained a 20-year-old paraffin-imbedded tissue sample of Anna from a Charlottesville hospital, but it was not admissible. But there were also hair samples. Her mtDNA was compared with the Romanov data and it was an exclusion. The paraffin tissue was later analyzed and it matched the hair sample data. - Conclusion: Despite some recent challenges to the results, most scientists feel that the results are authentic. Research shows that nuclear DNA can be extracted from material less than 100 years old. But nuclear DNA is not ideal for showing family lineages because of biparental inheritance. This case shows the value of mtDNA for maternal lineage reconstruction in historic cases. Heteroplasmy can actually increase RMP bec
More Less

Related notes for Anthropology 2235A/B

Log In


OR

Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.

Submit