Author: Darcia Schweitzer

Creating ART from 3D Printed Ovaries

Posted on by Darcia Schweitzer

It is remarkable to me how quickly in vitro fertilization has gone from an experimental, controversial and prohibitively expensive procedure to becoming a mainstream option for those struggling with fertility issues. What was unheard of in my parents’ generation is nothing extraordinary among my friends who are having children.

My personal observations are supported by the CDC, which reported that 1.6% of all infants born in the U.S. in 2015 were the result of assisted reproductive technology (ART). This is a 33% increase since 2006, which can be attributed to rapid advances and refinements of the various technologies available to those seeking reproductive assistance.

It challenges the mind to imagine what reproductive technologies might be widespread when my children and their friends are adults. When experts speculate about the future of human reproduction, there always seems to be a lot of focus on provocative scenarios that portend a dystopian future, such as designer babies. What gets lost are some of the more general scientific advances that are being applied to ART in fascinating ways.

While improvements in reproductive technologies serve many, one group that remains underserved are pediatric cancer patients. As a result of treatment, these patients are often faced with impaired ovarian function that can prevent puberty and result in infertility. In vitro fertilization and ovarian transplants are currently used, but do not provide lasting solutions for all individuals.

In response to this need, researchers are working to develop an organ replacement that can provide long-term hormone function and fertility for all patients.  A recent study in Nature Communications presented encouraging results in mice using bioprosthetic ovaries that may further revolutionize the field of ART.

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Knots: Friend or Foe?

Posted on by Darcia Schweitzer
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Knots affect our lives in perplexing ways. They can perform life-saving assistance, such as during rock climbing, or provide Sisyphean puzzles of entanglement. Often, knots seem to have the contrarian personality of an adolescent. They loosen and unwind when you want them to stay fastened, and inevitably form tangles of confounding complexity when you seek to avoid them. These puzzling characteristics of knots were brought to mind when I read two recent articles about the scientific investigation of knots.

Why Knots Fail

The explanation of how shoelaces come untied, published in Proceedings of the Royal Society A, was quite prevalent in the news cycle recently. After observing slow-motion video footage of the shoelaces of a runner on a treadmill, researchers were able to explain how motion affects knots and results in untied shoelaces.

First, they observed that the failure of a knot is not a gradual process, but happens abruptly over the course of only one or two strides. This is possible due to the surprising amount of force generated by the impact of one step, which this study calculated to be an average of 7 g—more than twice the g-force experienced by the Space Shuttle upon reentry into the Earth’s atmosphere.

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Making a Case for Basic Research Funding

Posted on by Darcia Schweitzer

The value of public funding for “basic” versus “applied” research has long been questioned. To address this debate, the authors of a recent report in Science performed a large-scale evaluation of the value of public investment in biomedical research. After analyzing the relationship between the U.S. National Institutes of Health (NIH) grants and private patents, they found that distinguishing research as basic or applied is not useful in determining the productivity of grant funding.

Genetic research at the laboratory

The $30 billion annual budget of the NIH makes it the largest source of life science funding in the world and provides a third of all US biomedical research and development. Although there has long been a strong argument for public investment in scientific research, attacks on the tangible benefits of this research persist. In particular, some opponents argue that “basic” research is too far removed from practical applications to be worthy of investment.

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So NASA Found Some New Exoplanets…Now What?

Posted on by Darcia Schweitzer
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You have probably heard a lot of excitement over NASA’s recent announcement about the discovery of seven earth-size planets found orbiting around the star TRAPPIST-1, which is part of the constellation Aquarius.

These exoplanets are notable because they exist within the habitable zone of the star (nicknamed Goldilocks planets because this area is not too hot and not too cold) and are probably rocky with the potential to contain water on their surface.

A lot of the enthusiasm revolves around the hope that one of these exoplanets might harbor extraterrestrial life or could be suitable for human inhabitants. Of course, many further observations must be made to determine if these scenarios are plausible, not to mention the huge advances in technology that would need to occur so we could actually verify the planetary conditions or send humans 40 light-years away.

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Familial Searching Solves Cold Cases—At What Cost?

Posted on by Darcia Schweitzer

A cold case that had stumped investigators for nearly 41 years was solved last month. The 1976 sexual assault and murder of Karen Klass, ex-wife of Righteous Brother’s singer Bill Medley, shocked her Hermosa Beach, CA community and captured the public interest. Failing to make any arrests for decades, detectives were able to use DNA evidence to eliminate suspects in 1999 but were unable to find a database match. In 2011, investigators decided to try a new technique called a familial search and, after a few attempts, successfully identified the perpetrator.

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Familial searching (FS) involves taking a DNA profile obtained from a crime scene and comparing it to profiles in CODIS and other databases to identify male relatives. The DNA profile of an immediate family member, such as a sibling, parent or child, can provide a match that generates new leads for law enforcement. Detectives can then collect additional evidence to narrow down that new pool of individuals to a single suspect.

Last May I wrote a blog featuring a Q & A about FS provided by Mr. Rockne Harmon, a respected member of the forensic community and passionate advocate for FS. Supporters, like Harmon, and opponents agree that this method of obtaining matches to DNA evidence has demonstrated scientific precision and successful outcomes, as in the Klass case. However, it is still considered controversial and most states have not implemented specific policies regarding the application of FS to criminal investigations. So why isn’t the use of FS more widespread?

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Did Dinosaurs Take Too Long to Hatch?

Posted on by Darcia Schweitzer

A different approach to dinosaur embryology has revealed another layer to our understanding of the demise of dinosaurs and rise of mammals as a result of the end-Cretaceous mass extinction event. In a 2017 Proceedings of the National Academy of Sciences paper, a group of researchers led by Gregory Erickson hypothesized that dinosaur eggs may have growth lines present on embryonic teeth that could be used to determine incubation times.

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Not much is understood about dinosaur embryology, aside from what is known about birds. This is in part because fossils of dinosaur eggs, especially those containing embryonic skeletons, are among the rarest in the world. Despite this difficulty, using these fossils to refine estimated incubation times of dinosaur embryos can shed light on their development, life history and evolution.

Historically, paleontologists have assumed that dinosaur incubation periods were rapid based on their extant counterparts, birds. Considered living dinosaurs, birds are a logical surrogate from which to extrapolate dinosaur incubation times. It is important to note that embryonic incubation in birds is different from other living relatives of dinosaurs, modern reptiles. While reptile embryos develop slowly, birds differ by laying fewer, larger eggs with rapid incubation.

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Shining Light on a Superbug: Clostridium difficile

Posted on by Darcia Schweitzer

Antibiotic-resistant bacteria and their potential to cause epidemics with no viable treatment options have been in the news a lot. These “superbugs,” which have acquired genes giving them resistance to common and so-called “last resort” antibiotics, are a huge concern as effective treatment options dwindle. Less attention has been given to an infection that is not just impervious to antibiotics, but is actually enabled by them.

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Clostridium difficile Infection (CDI) is one of the most common healthcare-associated infections and a significant global healthcare problem. Clostridium difficile (C. diff), a Gram-positive anaerobic bacterium, is the source of the infection. C. diff spores are very resilient to environmental stressors, such as pH, temperature and even antibiotics, and can be found pretty much everywhere around us, including on most of the food we eat. Ingesting the spores does not usually lead to infection inside the body without also being exposed to antibiotics.

Individuals taking antibiotics are 7-10 times more likely to acquire a CDI. Antibiotics disrupt the normal flora of the intestine, allowing C. diff to compete for resources and flourish. Once exposed to the anaerobic conditions of the human gut, these spores germinate into active cells that embed into the tissue lining the colon. The bacteria are then able to produce the toxins that can cause disease and result in severe damage, or even death.

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A Crash Course in CRISPR

Posted on by Darcia Schweitzer

CRISPR is a hot topic right now, and rightly so—it is revolutionizing research that relies on editing genes. But what exactly is CRISPR? How does it work? Why is everyone so interested in using it? Today’s blog is a beginner’s guide on how CRISPR works with an overview of some new applications of this technology for those familiar with CRISPR.

Introduction to CRISPR/Cas9

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Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) were discovered in 1987, but it took 30 years before scientists identified their function. CRISPRs are a special kind of repeating DNA sequence that bacteria have as part of their “immune” system against invading nucleic acids from viruses and other bacteria. Over time, the genetic material from these invaders can be incorporated into the bacterial genome as a CRISPR and used to target specific sequences found in foreign genomes.

CRISPRs are part of a system within a bacterium that requires a nuclease (e.g. Cas9), a single guide RNA (sgRNA) and a tracrRNA. The tracrRNA recruits Cas9, while sgRNA binds to Cas9 and guides it to the corresponding DNA sequence of the invading genome. Cas9 then cuts the DNA, creating a double-stranded break that disables its function. Bacteria use a Protospacer Adjacent Motif, or PAM, sequence near the target sequence to distinguish between self and non-self and protect their own DNA.

While this system is an effective method of protection for bacteria, CRISPR/Cas9 has been manipulated in order to perform gene editing in a lab (click here for a video about CRISPR). First, the tracrRNA and sgRNA are combined into a single molecule. Then the sequence of the guide portion of this RNA is changed to match the target sequence. Using this engineered sgRNA along with Cas9 will result in a double-stranded break (DSB) in the target DNA sequence, provided the target sequence is adjacent to a compatible PAM sequence.

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Familial DNA Searching for Criminal Forensics: Q&A

Posted on by Darcia Schweitzer

When DNA evidence is collected at a crime scene, submitting the sample for a search within a DNA database does not always identify a profile match. There is a way to extend that search and generate leads, called familial searching (FS). FS is used to identify close biological relatives of an unidentified DNA profile obtained as evidence. The basic premise is that DNA profiles of immediate family members, such as siblings, parents, or children, are likely to have more alleles in common than unrelated individuals. These familial profile matches can generate new investigative leads for law enforcement.

Currently, a few states are using FS under their state database laws, although none explicitly permit FS. Many agencies have yet to adopt policies related to FS, even though it has been found to be as effective as CODIS for identifying sources of evidence. The absence of clear ethical guidelines and policy regarding how to properly utilize FS prevents many local and state jurisdictions from adopting this investigational tool.

In order to address concerns and existing policies related to FS and to guide policy decisions by agencies implementing FS, the National Institute of Justice (NIJ) issued the report Familial DNA Searching: Current Approaches in January 2015. The goal of the report was to provide information to policy makers, law enforcement officials, forensic laboratory practitioners, and legal professionals about how FS is being applied within the criminal justice realm.

Mr. Rock Harmon, former prosecutor
Mr. Rockne Harmon, former prosecutor

Answers to the following questions about FS were provided by Mr. Rockne Harmon, a retired former prosecutor and member of the team that produced the report for the National Institute of Justice.

What is familial DNA searching?

Familial searching (FS) is an additional search of a DNA profile in a law enforcement DNA database that is conducted after a routine search fails to identify any profile matches. The FS process attempts to provide investigative leads to agencies engaged in the pursuit of justice by identifying a close biological relative of the source of the unknown forensic profile obtained from crime scene evidence.

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