Genetic Genealogy and DNA Help Solve 34-Year Old Murder Case

An article by The San Diego Union-Tribune discussed the murder of Diane Dahn, a woman who was 29 when she was brutally stabbed in 1988. She was left for dead in her apartment, and while investigators kept investigating the case for decades to come, it was not until recently with new genetic techniques that a suspect was able to be determined. 

Before genetic genealogy came into play for Dahn's case, DNA techniques were used as early as the 2000s. There were several pieces of DNA that were able to be used from Dahn's fingernails as well as a hair that was found in her hand, but when entered into the national databases, there were no matches. It was not until May of 2020 that genetics took over and really helped aid the investigation.

Genetic genealogy uses atDNA, also known as autosomal DNA in order to identify how closely related certain individuals are to each other. This type of DNA is inherited in all individuals and can be seen in both males and females. While the single nucleotide polymorphisms are harder to detect using forensic samples, technology is advanced enough to obtain information from small or degraded samples. The longer a segment is shared between two individuals, the more closely related they are. This helps establish family trees and helps piece together these kinds of cold cases.

Through the use of several genealogy websites, investigators were able to identify relatives of the suspect in order to find possible matches. These websites allowed law enforcement to see open DNA profiles in order to biologically look at the DNA and make certain matches for relatives. Family trees, or pedigrees, were created based on the matches found through the websites and 1,300 relatives and 9 pedigrees were able to be created based on the results of the unknown suspect. This led to finding the suspect's children, and when a paternity test was done, they found the suspect: Warren Robertson, a man who lived in the same apartment complex as Dahn, but had died in a fire in 1999.

Based on the success of this case, as well as 5 others San Diego have solved, genetic genealogy is on the rise and provides good results in order to help locate a suspect or provide more information based on DNA profiles found at a crime scene. I think while it is a tedious and difficult process, the success rate of genetic genealogy and the information being discovered is amazing and helps in the field of forensic science. Forensic biology is on the rise as DNA and its advancements provide helpful information. I believe these biological techniques are here to stay and aid in law enforcement investigations which is a win-win in terms of science and criminal justice.

Related articles:

Dead Convict Identified as Oregon Serial Killer From the 1980s

The Future of Genetic Genealogy

How Old is Smallpox Really?

     According to research by an international team of researchers Smallpox might have merged way later then we previously thought. Tissue samples were taken from a Lithuanian child mummy that us dated back to the 1600's. It was concluded that the cause of death was smallpox, but not exactly the strain we cause just a hundred years ago. Reconstructing the full RNA sequence of the smallpox virus strain and compared the results to more recent samples. With this information the team was able to make a time line of the smallpox virus and piece together information about the different strands. While looking at the timeline for the diseases the rate of mutations was also studied and their was found to be two major strand groups, and all related back to a simple common ancestor.  With the information uncovered about the common ancestor it was evaluated that smallpox must have not always been such an epidemic. If small pox had been an epidemic for the thousands of years that it has been around researchers would not have been able to find a common ancestor since it would have diverged tremendously over time. 

     This article is extremely fascinating because with a small sample from a mummy that is thousands of years old they were able to make a time line for small pox and better understand how the virus grew and mutated. With more data like this hopefully we can come to better understand how viruses are spreading so rapidly and diverging out of nowhere. With this knowledge we can better understand and develop more vaccines and save thousands of lives.  

For more information on the history of smallpox go to - https://www.cdc.gov/smallpox/history/history.html

Main article: http://blogs.discovermagazine.com/d-brief/2016/12/08/child-mummy-smallpox-timeline/#.WQfiYIn5601 

Possible Re-write of the Elephant Family Tree

For many years, scientists thought they had the elephant family tree mapped out. However, a recent discovery of an ancient elephant fossil forces scientists to rethink the family tree.

What we know now is that there are three species of modern elephants:
1. The Asian Elephant (Alphas maximus)
2. The African Elephant- forest dwellers (Loxodonta cyclotis)
3. The African Elephant- Savannah (Loxodonta africana)

Straight Tusked Elephant (Paleoxodon antiquus)

We also know that scientists believed the ancient predecessor, the Straight Tusked elephant (Paleoxodon antiquus) was the closest relative to the Asian elephant. But new research shows that the predecessor is actually more closely related to the African forest elephants. Even more new research of the mammoth genome reveals that mammoths and elephant species were known to interbreed in the past. This means the elephant family tree will need to be minimally altered.

What we know about the Straight Tusked elephant:
The Straight tusked elephant lived in European forests until 100,000 years ago.
Straight tusked elephants and mammoth species have interbred.
Straight tusked elephants have interbred with Asian elephants.
Straight tusked elephants represent the oldest whole genomes from a warm environment.


The greatest fascination about the elephant genome is that the Straight tusked elephant genome wasn't just sequenced, it was sequenced in such high quality, that each letter was sequenced on average
15 times, leaving many scientists in complete awe.

For more about the interbreeding of the mammoth and elephant: http://www.iflscience.com/plants-and-animals/scientists-successfully-insert-woolly-mammoth-dna-elephant-genome/

 

The Genes of Craft Beer:Creating the First Genetic Family Tree for Brewing Yeasts

 

 

For those of us over the age of 21, drinking craft beers is a fun way to spend a Friday night whilst trying a wide variety of flavor profiles.  Craft beers have become increasingly popular and with a palatable treasure-trove of flavors from bold and spicy to fruity and crisp, it seems the flavor combinations are endless.  How do the brewers create such an array of flavors? Well, after thousands of years of domestication, brewing yeasts are extremely diverse.  These microorganisms ferment the mixture of grain, hops, and water into beer.

Two research teams from White Labs and a Belgian genetics laboratory are creating the first genetic family tree for brewing yeasts.  An avid brewer and microbiologist from White Labs, Troels Prahl, was interviewed about the project to compare genetic data from yeasts with brewing data from more than 2,000 batches of beer for The New York Times. The laboratories have sequenced the DNA of more than 240 strains of brewing yeasts.  This information will be used to compare how closely yeasts are related, how the yeasts evolved over time, and how it translates to taste. The founder of White Labs, Chris White said, "Yeasts make over 500 flavor and aroma compounds." However, even though brewing yeast is one of the most studied organisms in cell biology, "how the genes translate to brewing properties is still poorly understood."  

Researchers at the Belgian lab, which was a joint venture of the Flanders Institute for Biotechnology and the University of Leuven, Belgium, have plans to use this information to select for different properties in the variety of yeasts and breed them to create new strains.  Dr. Verstrepen said, "In a few years we might be drinking beers that are far different and more interesting than those that currently exist."

Craft brewers currently have limited options for creating new yeast strains.  If the breeding strains are combined it usually results in a brew that is unusable.  This occurs because the yeasts are highly specialized and although they serve the same purpose they have too much genetic variation to be bred together without genetic modification.  Currently there are hundreds of genetically modified varieties of yeasts but because of the negative stigma surrounding GMO's most brewers will not use them.

  The data from the genomic project may allow researchers to breed new yeasts without having to genetically modify the organisms by utilizing computers and robotics because the genes that the brewer wants can be selected for by knowing what genes to track.  This could allow a researcher to mate two different yeast strains thousands of times until the desired combination of genetic characteristics is reached by chance.  Microbiologist Chris E. Baugh, who is not involved in the project states,“So let’s say there’s a yeast that produces an amazing fruity aroma in beer, but can’t ferment past 3 percent alcohol," this technique, "could then breed it with a more alcohol-tolerant strain.”

The creation of craft beers has been an art and a science for thousands of years.  It's exciting that the scientific community is taking a greater interest in this field.  This industry is becoming a booming business financially and I think its time for the scientific community to profit from the success.  I can only imagine how this project will contribute to the wide array of flavors in the future.  I know I am excited to try the multitude of brews possible!