Individual Journal Week 11

Terms

• Batch-culture: A large-scale closed system culture in which cells are grown in a fixed volume of nutrient culture medium under specific environmental conditions (e.g. nutrient type, temperature, pressure, aeration, etc.) up to a certain density in a tank or airlift fermentor, harvested and processed as a batch, especially before all nutrients are used up. [1]
• Catabolite: product of catabolism, the breakdown of complex molecules into simpler ones. [2]
• Gene Regulatory Protein: Any protein that interacts with dna sequences of a gene and controls its transcription. [3]
• Up-regulation:process that increases ligand/receptor interactions due to an increase in the number of available receptors. [4]
• Down-regluation: the process that decreases ligand and receptor interactions or reduces the responsiveness of a cell to a stimulus following first exposure.This is often accompanied by an initial decrease in affinity of receptors for the agent and a subsequent reduction in the number of available receptors expressed on the surface which can result from internalisation of the ligand:receptor complex or from decreased expression of the receptor. [5]
• Motif: The smallest group of atoms in a polymer that, when under the influence of a rotation-translation operator, will assemble the rest of the atoms in the chain. [6]
• Desaturase: Any of several enzymes that putdouble bonds into the hydrocarbon areasof fatty acids. [7]
• Biogenesis: The process in which life forms arise from similar life forms. [8]
• Trehalose: a crystalline disaccharide C12H22O11 that is found in various organisms (as fungi and insects), is about half as sweet as sucrose, and is sometimes used as a sweetener in commercially prepared foods [9]
• Transcriptome: the complement of mature messenger RNAs produced in a given cell in a given moment of its life. [10]

Outline

Introduction

• The study observes the effects of suboptimal temperatures on transcriptional regulation in yeast.
• Transcriptional responses were observed at temperatures 12C and 30C.
• Lower temperatures, typically result in the slower cellular processes: growth phase, respiration, lipid composition of membranes, and trehalose content.
• Time scale of exposure to cold-shock relevant:

1. • Sudden exposure => adaptation
   • Prolonged exposure=> acclimation
   • Long term exposure => evolutionary adaptation

• Two distinct phases during cold-shock response

1. First 12 hours, early cold shock (ECS)
2. After first 12 hours, Late cold response (LCR)

• TPS1 and TPS2, commonly observed trehalose-biosynthetic transcriptional induction genes- observed in cold and heat shock conditions
• Genes involved in cold-shock response typically involved in other stress response
• Growth rate an important factor on transcription
• Research seeks to control specific growth rate and other culture conditions, through use of chemostat, in order to establish steady-state and, thus, investigate transcription regulation influenced by suboptimal temperatures