Researchers describe gene that makes large tomatoes
When humans first began cultivating wild tomatoes in the Andean mountain regions of Ecuador and Northern Peru, they continually selected plants that produced larger fruits. Now, thousands of years later, tomatoes on the market can weigh 1,000 times more than the fruits of their ancestors.
Studying the genes that regulate growth in tomatoes allows scientists to better understand how to increase the size of this fruit without negatively impacting disease resistance and flavor. In a new study, researchers investigated a gene in tomatoes named Cell Size Regulator, or CSR. This gene boosts fruit weight by increasing the size of the individual cells in the fleshy part of the tomato.
The researchers found that compared to wild tomatoes, domesticated varieties carry a mutation in the CSR genes that shortens the resulting protein in tomato cells, and that truncation likely affects its role in regulating cell differentiation and maturation in the fruit and vascular tissues. The new study expands on previous research that had identified the location of CSR as only a small genetic contributor to tomato weight. Now with cloning of the gene, the finding that most cultivated tomatoes carry the shortened version of the CSR gene suggests that humans selected this genetic variation extensively, and that it was critical to the full domestication of tomato from its cherry tomato ancestors.
Tuberculosis drug may work better than others in its class
Tuberculosis infects millions of people every year. Treatment of the disease requires at least six months of treatment with multiple drugs. In a new study published by PLOS Computational Biology researchers are trying to figure out which of these drugs are the most effective, because existing data from clinical trials and animal studies have been unable to determine which is best.
In the study, they used a computer model to test three fluoroquinolones – a class of drug commonly used in Tuberculous treatment – to see which, if any, would outperform each other. The computer model simulated the effects of the three drugs on granulomas – clusters of host cells and bacteria that develop in the lungs of tuberculosis patients.
When the researchers performed a side-by-side comparison of fluoroquinolones in identical infections, moxifloxacin (MOXI) appeared to be superior to both levofloxacin (LEVO) and gatifloxacin (GATI) because it killed bacteria in granulomas more quickly. MOXI also performed better when the simulated patients missed doses. LEVO killed bacteria more quickly than GATI. However, all three drugs were unable to kill bacteria at the very center of the granulomas.
Citation: Mu Q, Huang Z, Chakrabarti M, Illa-Berenguer E, Liu X, Wang Y, et al. (2017) Fruit weight is controlled by Cell Size Regulator encoding a novel protein that is expressed in maturing tomato fruits. PLoS Genet 13(8): e1006930.
Citation: Pienaar E, Sarathy J, Prideaux B, Dietzold J, Dartois V, Kirschner DE, et al. (2017) Comparing efficacies of moxifloxacin, levofloxacin and gatifloxacin in tuberculosis granulomas using a multi-scale systems pharmacology approach. PLoS Comput Biol 13(8): e1005650.
Image Credit: Alexis Ramos and Esther van der Knaap, University of Georgia Athens GA 30602