Bringing Science to Life with HudsonAlpha
HudsonAlpha Institute for Biotechnology
The Biotechnology Discoveries and Applications guidebook provides an overview of the recent advances in genetics and biotechnology for teachers and students. Released annually by the HudsonAlpha Institute for Biotechnology in Huntsville, Alabama, the guidebook presents new findings in jargon-free, student-friendly language.
The following 3 excerpts are from the 2014–2015 edition, showcasing both the enthusiasm and the challenge of research in genetics and biotechnology.
This excerpt discusses scientific advances in genetics.
How do chromosomes condense before mitosis?
The classic model of chromatin folding is replaced with a two-phase process
During the cell cycle, chromosomes switch between two levels of condensation. Interphase chromosomes are loosely packaged and distributed across a relatively large area inside the nucleus. Different cell types organize DNA into characteristic spatial patterns, with large loops connecting genes and distant regulatory sequences and positioning needed genes into transcriptionally active conformations. In contrast, cells preparing to divide contain tightly condensed, transcriptionally silent chromosomes.
Various folding models have been suggested to explain how interphase DNA is compressed into metaphase chromosomes. A classic image in biology textbooks shows DNA coiling in a hierarchical manner to form thicker and thicker chromatin fibers. An alternate model suggests the DNA forms looping structures that attach to a protein backbone. To date, experimental results have been unable to confirm or refute either model.
Using a combination of three-dimensional modeling, advanced computer simulation, and next-generation sequencing, researchers are unraveling the process of chromosome assembly. Building on a decade of analysis, scientists are finding the data inconsistent with the classical model of hierarchical DNA coiling. Instead, mitotic chromosomes are assembled in a two-phase process. First, the organizational scaffolds from interphase are disassembled and replaced by irregularly sized chromatin loops of 80,000–120,000 base pairs. These loops appear to form randomly along the chromosome and radiate outwards from a central DNA: protein scaffold. The second phase compresses the backbone of the loop scaffold, similar to squeezing a spring to flatten it. The DNA is condensed into a tightly folded package. Unlike the cell-specific organization found during interphase, the packaging of DNA prior to mitosis appears to be universal across all cell types.
Following mitosis, the chromosomes revert to their cell-specific spatial organization. The mechanisms that direct disassembly and reassembly of the interphase chromosomes are unknown. As most DNA binding proteins disassociate from the chromosome during mitosis, what is left behind to guide reassembly? The authors suggest histone tags, DNA methylation, or the few protein complexes that remain on DNA during mitosis may be responsible for this “cell-specific memory.”
Naumova N. et al, “Organization of the mitotic chromosome,” Science (2013) 342:948–53 doi:10.1126/science.1236083.
This excerpt focuses on the microbiome of money.
New findings: Don’t put your money where your mouth is
Researchers in New York City recently set out to examine the microbiome of money, specifically, the bacteria living on U.S. one dollar bills. Analyses were carried out during February and July of 2013, allowing a comparison between winter and summer months. DNA from the bacteria was extracted, sequenced, and analyzed for 80 circulating bills.
Scientists identified more than 3,000 different types of bacteria, about half of which are naturally found living in and on humans. Most were harmless, with the exception of antibiotic resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA). There was a seasonal effect as well, with winter months having a higher concentration of pneumonia microbes present. Overall, the study findings suggest that money can transmit illness.
The amount of bacteria found on money is perhaps to be expected. Cash carried in a back-pocket wallet or a purse held close to the body provides a warm space for microbes to thrive. This is another reminder of the ever-present nature of bacteria and nothing to overreact about. Still, it’s probably best to avoid licking your fingers while counting out cash.
Douiey, Caren. Professor’s study finds microbes on dollars. Washington Square News April 29, 2014. Accessed at http://www.nyunews.com/2014/04/29/dirty-2/ on September 15, 2014.
Science snapshot: Dog domestication
Recent research into dog domestication compared the genomes of grey wolves, African basenji, Australian dingo and a Boxer to see which lineage gave rise to domestic dogs. The results suggest that both modern dogs and modern wolves arose from a species of wolf that is now extinct. Similar conclusions came from a mitochondrial DNA analysis of modern wolves and dogs plus the fossilized remains of ancient dogs. In a departure from previous studies, these findings suggest dog domestication arose before the widespread use of human agriculture.
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You can also hear Dr. Neil Lamb, our Vice President for Educational Outreach, bring stories from the 2015–2016 guidebook to life at his 2015 NABT session “Top 10: Genetics and Biotechnology Discoveries 2015.”