The budding yeast, Saccharomyces cerevisiae, is a prime organism for studying fundamental cellular processes, with the functions of many proteins important in the cell cycle and signaling networks found in human biology having first been discovered in yeast.
Now, scientists from New York University have now developed a sophisticated assay to track cell growth at very low nutrient concentrations. The assay uses time-lapse microscopy to monitor individual yeast cells undergoing a small number of divisions to form microcolonies.
The assay can measure the lag times and growth rates of as many as 80,000 individual microcolonies in a single 24-hour experiment, opening up a powerful new high-throughput tool to study the complex interplay between cell growth, division and metabolism under environmental conditions that are likely to be ecologically relevant but had previously been difficult to study in the laboratory.
The researchers studied growth rates and lag times in both lab strains and wild yeast by varying the amount of its prime carbon food source, glucose. They confirmed the prediction made over 60 years ago by Noble-prize-winning biologist Jacques Monod regarding changes in microbial growth rates with limited nutrients (the Monod equation). They also found significant differences among strains in both the average lag response (the amount of time it takes to transition from cell quiescence to restarting cell growth) and average growth rates in response to different environmental conditions.
In addition to average differences between strains and conditions, the powerful assay revealed metabolic differences among cells of the same strain in the same environment. Moreover, yeast strains differed in their variances in growth rate. According to the study's lead author, Naomi Ziv, "Heterogeneity among genetically identical cells in the same environment is a topic of increasing interest in biology and medicine. The different strain variances we see suggest that the extent of nongenetic heterogeneity is itself genetically determined."
Further investigations could pave the way to a more complete understanding of the genetics and metabolomics of cell growth in yeast and the underlying mechanisms relevant to other settings in which cells face challenging conditions, such as cancer progression and the evolution of drug resistance.
To access the full online article: http://mbe.oxfordjournals.org/content/early/2013/08/11/molbev.mst138.abstract
Media sources:David Gresham
Unlike genomic DNA, the mitochondrial genome is unique inherited only through the mother, is small in size, and has a high mutation rate. Researchers Longli Kang, Li Jin et al. have sequenced 76 Sherpa individuals' complete mitochondrial genomes living in Zhangmu Town, Tibet, and found two mutations that were specific to the Sherpa population. The authors suggest that variants for one recent mutation in particular that was introduced into the Sherpa population about 1,500 years ago, A4e3a, that may be an important adaptation for low oxygen environments, or hypoxic conditions. This mutation is found in an "entry enzyme" stage in the mitochondrial respiratory complex, which may explain the importance of the role of mitochondria in the Sherpa population's ability to adapt to the extreme Himalayan environment.
The authors also shed light on the demographic history of Sherpa population size over evolutionary time, showing a significant expansion from 3,000 to 23,000 around 50,000 years ago, followed by a very recent bottleneck in the past several hundred years that reduced the population from 10,000 to 2,400, matching known historical migration patterns.
Media source:Prof. Li Jin
Joe Caspermeyer | EurekAlert!
Zap! Graphene is bad news for bacteria
23.05.2017 | Rice University
Discovery of an alga's 'dictionary of genes' could lead to advances in biofuels, medicine
23.05.2017 | University of California - Los Angeles
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...
Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...
23.05.2017 | Event News
22.05.2017 | Event News
17.05.2017 | Event News
23.05.2017 | Physics and Astronomy
23.05.2017 | Life Sciences
23.05.2017 | Medical Engineering