When using erlenmeyer shake flasks for the fermentation production of CHO suspension cells, the passage stability of the cell line needs to be done, so we will have several questions when the cells are passaged. Today, I will briefly answer these questions with you.
1. How many generations are appropriate for the passage stability experiment?
It depends on the future production cycle. For example, what is the time from the start of the recovery of cells to the completion of a batch of production, and the stability should be at least greater than this time. For the reliability of the production project, it is recommended to double the stability time of the production cycle, so that a change trend of the expression level of the cell line can be seen. The cell line will show a downward trend with the passage of time.
2. To test the expression stability of the target protein, how long should each passage of cells be cultured for sampling? Does each generation of cells have to be fed and cultured for half a month before testing?
It is not necessary to do this every generation. It is enough to do a few articles to see the trend of stable expression (but you can't do two or three articles so that you can't see the trend).
3. To test the genetic stability of cells, how long does it take to extract DNA for each generation of cell culture?
This can be done in the same cycle as the second point feeding culture.
4. Is there a detailed protocl for the passage stability experiment that you can refer to?
Stability mainly focuses on whether the expression level of the cell line is stable, whether the protein activity is stable and the cell genetic stability. These are meant to show that you are stable in production later on.
5. If you use erlenmeyer shake flasks, then you don't need to build a bank, and you can directly inoculate it into a shake flask to start fedbatch culture?
Even if erlenmeyer shake flask is used, it is necessary to build a library, and the stability evaluation is the MCB and WCB library, not simply evaluating the cell line.
The FAI climbed 5.9 percent year-on-year in the first 11 months of 2018, quickening from the 5.7-percent growth in Jan-Oct, the National Bureau of Statistics (NBS) said Friday in an online statement.
The key indicator of investment, dubbed a major growth driver, hit the bottom in August and has since started to rebound steadily.
In the face of emerging economic challenges home and abroad, China has stepped up efforts to stabilize investment, in particular rolling out measures to motivate private investors and channel funds into infrastructure.
Friday's data showed private investment, accounting for more than 60 percent of the total FAI, expanded by a brisk 8.7 percent.
NBS spokesperson Mao Shengyong said funds into weak economic links registered rapid increases as investment in environmental protection and agriculture jumped 42 percent and 12.5 percent respectively, much faster than the average.
In breakdown, investment in high-tech and equipment manufacturing remained vigorous with 16.1-percent and 11.6-percent increases respectively in the first 11 months. Infrastructure investment gained 3.7 percent, staying flat. Investment in property development rose 9.7 percent, also unchanged.