Origin of the Y Chromosome

By Marisa Sanchez, Molecular and Cellular Biology ‘15

The genomes of male and female mammals differ by one chromosome. The Y chromosome is only present in males, and is responsible for initiating the physiological and morphological differences between the sexes. This has not always been the case though; at one point, the X and Y were identical, and over time the Y chromosome began to differentiate from the X chromosome and shrink in size. The Y chromosome today only has 20 genes, whereas the X chromosome has over 1,000 genes. Continue reading Origin of the Y Chromosome

“No Ecosystem is an Island”

By Daniel Friedman, Genetics ’14

For years, ecologists have modeled the biodiversity of natural forests as if they were oceanic islands, adrift in an unlivable sea of humanity. However, research published in April in Nature by C. Mendenhall et al. suggest that this is not the most accurate or predictive way to think about these pockets of nature. By comparing bat diversity on countrysides and oceanic islands, they find that fragmented land ecosystems behave markedly different than their oceanic counterparts. They find that forest “islands” maintain species at higher overall levels of biodiversity than ocean islands, and also gain/lose species in unique patterns. This has relevance to humanity’s actions to support biodiversity on land, and suggests the need for new models, metrics, and strategies of conservation.

Mendenhall, C., Karp, D., Meyer, C., Hadly, E., Daily, G., “Predicting biodiversity change and averting collapse in agricultural landscapes”, Nature, 2014.

Image from Abu Shawka, 2009. Creative Commons.

Green Tea Can Improve Your Memory

By Marisa Sanchez, Molecular and Cellular Biology ’15

Green tea has been said to have several health benefits including helping prevent certain types of cancer and inflammation. In a new study done by Dr. Beglinger and Dr. Borgwardt at the University of Basel in Switzerland, they have found that green tea extract enhances cognitive functions, particularly the working memory because green tea extract increases the brain’s effective connectivity, the causal influence that one part of the brain exerts on another part. Continue reading Green Tea Can Improve Your Memory

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

Grass-fed or grain-fed?

By Jenny Cade, Biochemistry & Molecular Biology ’15

Eating grass-fed beef and pasture-raised chicken is the eco-friendly thing to do–right? Maybe not, according to a recent paper published in the Proceedings in the National Academy of Science. The study proposes that intensifying livestock production by transitioning from pure grazing to mixed systems–where animals are fed high-energy food like grains–could reduce livestock greenhouse gas emissions by 23% by 2030. Currently, livestock account for 14.5% of all anthropogenic greenhouse gas emissions, so such a reduction would be significant.

In contrast, a comment piece that appeared in Nature last month calls for increasing grazing to make livestock systems more sustainable. Of eight strategies that the authors outline to reduce the environmental and economic costs of raising livestock, “Feed animals less human food” is number one.

Continue reading Grass-fed or grain-fed?

“The Eukaryotic Ribosome”

This is a submission from UC Davis CBS Professor Sean Burgess. It comes from a future publication that relates the human quest to visualize the inner workings of the cell, molecular biology, with the quest to visualize the interior of the mind, art.

The Eukaryotic Ribosome

The basic mechanism of ribosome­based protein synthesis is conserved among all domains of life. The ribosome comes in two parts. The small subunit  interacts with the mRNA and decodes the interaction with the aminoacyl tRNAs. The large subunit contains the active site of peptidyl transferase. The two subunits together
form three pockets for three forms of tRNA. The A site is where the aminoacyl tRNA binds, the P site holds that peptidyl tRNA when the A­site is occupied. The E site contains the deacylated tRNA following peptidyl transferase. The ribosome is a huge conglomeration of RNA and proteins. The RNA appears to do all the heavy lifting for the main catalytic event of protein synthesis.  So what came first, the protein or the ribosome?
Obtaining the crystal structure of the ribosome was a tour de force effort. The Nobel Prize for solving its structure was awarded in 2009.

Top: Willi Baumeister: Mortaruru with Red Overhead (1953), The Art Book,

Phaidon Press Limited, 1994.
Bottom: The 60S (PDB: 305H) and 40S (PDB: 1S1H) subunits of the eukaryotic ribosome. Ben­Shem et al. (2010) Science, 330 (6008): 1203­1209. The image was generated by S.M.B. using MacPymol using coordinates from the Protein Databank (http://helixweb.nih.gov/cgi­bin/pdb).  MacPyMOL is product of
Schrodinger, LLC. Copyright (C) 2009­2010.

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.

Stop Looking for the Drug. Look at the Genes – Bulletproof Anti-doping Test

By Isra Uz-Zaman, Genetics ’14

Cheating in sports in not a new phenomenon. In the modern era, numerous athletes participate in blood doping by injecting erythropoietin (EPO) into their blood to increase the amount of red blood cells and thus improve their athletic performance. EPO is a protein hormone produced by the kidney which stimulates the production of red blood cells when released into the bloodstream. Increased red blood production increases the amount of oxygen available in the body and boosts an athlete’s performance. Yannis Pitsiladis, a psychologist in Scotland, is at the forefront of developing anti-doping testing based on the genetic fingerprint left by drugs. Conventionally researches developed tests to find the drug, but Pitsiladis has taken another approach. He is developing a new generation of tests that will gather evidence from the doper’s own body.

Continue reading Stop Looking for the Drug. Look at the Genes – Bulletproof Anti-doping Test

New Method Increases Supply of Embryonic Stem Cells

By: Varsha Prasad, Genetics ’15

A study to employ a new method of generating human embryonic stem cells without destroying any human embryos is currently being conducted by an international research team led by Karl Tryggvason, Professor Medical Chemistry at Karolinska Institutet and a Professor at Duke-NUS Graduate Medical School in Singapore.

The researchers developed a method in which embryonic stem cells can be obtained from a single cell of an eight-cell embryo, which can then be refrozen and placed in the woman’s uterus.  This prevents the need to destroy human embryos in the process.  The idea is that the embryo can survive a single cell removal. Continue reading New Method Increases Supply of Embryonic Stem Cells

An undergraduate life sciences journal at UC Davis