All posts by Ashley Chang

Viral Evolution

By Mubasher Ahmed, Genetics ‘15

Viral evolution is an emerging field in biology that has great implications for human health. T7 is a phage virus, meaning it infects bacteria, and is a powerful model system in evolutionary virology. In a recent experiment, a team of biologists sought to understand the degree to which genetic elements engineered into the T7 phage genome affected the phage’s rate of propagation. In this context, the genetic elements are sequences of DNA that are inserted between genes that allow for researchers to manipulate gene regulatory networks. This allows biologists to probe how phenotypes change when gene-gene interactions are perturbed.  Previous studies had shown that such genomic elements led to decreased fitness for the virus, but these investigators hoped to better understand how exactly such a system would evolve in laboratory conditions.

To address their questions, the scientists grew both T7 viruses with and without design elements in each of two conditions. One condition was in a nutritious broth that used one intestinal bacterium as a host, and the other in a glucose sugar medium that had a different host bacterium. Both T7 strains were allowed to grow for 700-1000 generations in the glucose media and 100 generations in the broth media. Limitless bacteria were provided for the phages in order to encourage growth, and the researchers hypothesized that their experiment would allow enough time for the maladapted viruses to slough off deleterious design elements through evolutionary adaptation. Continue reading Viral Evolution

Lab Engineered Cartilage used in Nose Reconstruction

By Ashley Chang, Genetics ’15

Researchers at the University of Basel in Switzerland have successfully used lab-engineered cartilage for nose reconstruction. This study was conducted on five patients between ages 76 and 88 who had significant nasal damage after skin cancer surgery. One year after the replacement, all of them note significant improvement in the ability to breathe as well as cosmetic appeal, and no patients had significant side effects. This is a groundbreaking study as it opens of the possibility of engineered cartilage replacement in other areas, such as the knee, and of tissue-engineering as a whole. Continue reading Lab Engineered Cartilage used in Nose Reconstruction

Fecundity Decrease in Drosophila simulans in the absence of Wolbachia

By: Jack Taylor, Biochemistry and Molecular Biology ’15

Sponsor: Michael Turelli, Ph.D.

Ecology and Evolution

Many species of arthropods host Wolbachia, maternally transmitted bacteria that often influence host reproduction. This manipulation of host reproduction has contributed to Wolbachia becoming a normally-present infection of many Drosophila simulans. The Y36 isofemale line, a population of Drosophila simulans created from a single female collected in 2010 in Yolo County, produces flies which have an unusual phenotype when reciprocally crossed with uninfected simulans populations denoted U. The cross between Y36 male and U female produces female offspring with significantly lower fecundity than the reciprocal cross (Y36 female with U male). It is possible that this effect is a result of a paternal defect gene that is masked by the Wolbachia infection. Ten separate sublines were created from the Y36 isofemale line. The goal of my experiment was to determine whether this phenotype is still present among each of the ten sublines and if there is any variation in the phenotype among the sublines. Analysis of the data indicates that the qualitative effect of the phenotype has been preserved across the sublines but suggests that there is quantitative variation amongst them.

Climate Engineering: Worth the Risk?

By Ashley Chang, Genetics ’15

Researchers at the GEOMAR Helmhotltz Centre for Ocean Research Kiel are studying the long-term effects of “climate engineering” methods that could help to preserve the climate and protect from rising temperatures. This winter every part of the world except the eastern United States reported record breaking high temperatures. Although political agreements have been made to reducing greenhouse gas emissions, the effects may be too slow as levels of CO2 and other greenhouse gases continue to rise. This is especially important as populous countries, such as China and India, become increasingly industrialized and consequentially raise their greenhouse gas emissions. Continue reading Climate Engineering: Worth the Risk?

Genome-Wide Association Identifies Genes Linked to Autism

By Ashley Chang, Genetics ’15

Biostatisticians led by Knut Wittkowski at Rockefeller University Hospital have employed new methods of genome-wide association studies to identify genes that they believe to be associated with autism. The researchers compared genomes of patients with varying degrees of autism to healthy patients and were able to identify genetic variations that seem to be linked to the pathology of neural development in young children. The technique used to identify these genes is unique. Rather than traditional genome association, which searches for single nucleotide polymorphisms (SNPs), this new method looks for combinations of several SNPs that are common in patients with a disease. Wittkowski also compared this new autism profile to patients with childhood epilepsy and found mutations in similar genes that control axonal guidance and calcium signaling. Both of these are important in the developing brain to ensure that the correct connections are made. Continue reading Genome-Wide Association Identifies Genes Linked to Autism