Emmatyrnauer Week 12

Definitions

Ambient temperature affects gene regulation
Has led to the evolution of biochemical and physiological properties
Known cellular activities in response to:
- heat shock: heat shock proteins expressed more
- cold shock: decreased permeability of cell membrane, decreased protein synthesis and folding, and decreased enzymatic activity
Currently there aren't any studies that examine the effects of cold shock below 10 deg C on gene expression in yeast
Interested in this because preservation of organisms often occurs at less than 10 deg C (i.e. 4 deg C)
This study exposed yeast to temperature of 4 deg C and examines changes in gene expression using cDNA microarray
- Cluster analysis performed
  - Results include gene expression between 6 and 48 hours after 4C cold shock differs from culture kept at 35C or 4C. After cold shock, expression of certain genes was induced (e.g. energy preservation genes, phospholipid synthesis genes, and cell rescue genes)
Now the question is what are the cellular responses of yeast which have already adapted to/able to survive at 4C

Strain and growth conditions
- Saccharomyces cerevisia grown in YPD medium at 25C in a shaker.
- One group was left until growth reached late log phase--control group
- Other group removed once growth reached mid log phase and transferred to 0C.
  - Upon reaching 4C, yeast was flash frozen and stored at -80C
RNA was extracted and poly A mRNA was purified
Probe prepared and labeled
Microarray hybridized and scanned
Hierarchal cluster analysis performed with GeneSpring

Figure 1 is a graph representing the growth of the yeast cells at 25C and following exposure to 4C. Growth was monitored over a 60 hour period and cold exposure occurred at 20 hours. Growth occurred at a faster rate in the control group (which was left at 25C at mid log growth) compared to the group that was cooled and stored at 4C. However growth of the control group leveled out at around 30 hours.
Table 1 represents changes in expression of 20 genes which demonstrated greater that two-fold up-regulation and 20 genes which demonstrated less that 0.5-fold down regulation at 6, 12, 24, and 48 hours. In general, genes that were involved in cell rescue, defense, virulence, energy and metabolism were up-regulated, whereas genes responsible for protein synthesis, binding functions/co-factor requirements, activity regulation, and fate were down-regulated.
Figure 2 is an image of the heierarchical cluster analysis between 6 and 48 hours following 4C exposure, culture at 4C, and culture at 35C
Table 2
Table 3
Table 4
Table 5

I worked with my group project partner Katie during class and over text to work on the presentation
I worked with Katie, Zach, and Blair, to construct the our group page.
While I worked with the people noted above, this individual journal entry was completed by me and not copied from another source.

Emmatyrnauer (talk) 22:23, 19 November 2017 (PST)

LMU BioDB 2017. (2017). Week 12. Retrieved November 19, 2017, from https://xmlpipedb.cs.lmu.edu/biodb/fall2017/index.php/Week_12
Homma, T., Iwahashi, H., & Komatsu, Y. (2003). Yeast gene expression during growth at low temperature. Cryobiology, 46(3), 230-237. Retrieved November 19, 2017 from http://sq4ya5rf2q.search.serialssolutions.com/?V=1.0&sid=PubMed:LinkOut&pmid=12818212