![](https://webarchive.library.unt.edu/web/20090507224756im_/http://www.nsf.gov/images/x.gif)
Directorate for Biological
Sciences Dear Colleague Letters
![](https://webarchive.library.unt.edu/web/20090507224756im_/http://www.nsf.gov/images/greenline.jpg)
Basic Research to Enable Agricultural Development (BREAD)
Multi-scale Modeling (MSM)
Emerging Topics in Biogeochemical Cycles (ETBC)
Life in Transition (LiT)
Microbial Systems in the Biosphere (MSB)
![](https://webarchive.library.unt.edu/web/20090507224756im_/http://www.nsf.gov/images/x.gif) updated 3/31/09
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