Abstract: The invention provides methods for making a gene library from trace amounts of DNA derived from a plurality of species of organisms comprising obtaining trace amounts of cDNA, gDNA, or genomic DNA fragments from a plurality of species of organisms, amplifying the DNA so obtained, and ligating the DNA to a DNA vector to generate a library of constructs in which genes are contained in the DNA. The invention also provides methods for screening clones having DNA recovered from trace amounts of DNA derived from a plurality of species of uncultivated organisms. The invention also provides methods for identifying and enriching for a polynucleotide encoding an activity of interest.

Abstract: The invention is directed to polypeptides having a fluorescent activity, e.g., an auto-fluorescent activity, polynucleotides encoding the polypeptides, and methods for making and using these polynucleotides and polypeptides. The polypeptides of the invention can be used as noninvasive fluorescent markers in living cells and intact organs and animals. The polypeptides of the invention can be used as, e.g., in vivo markers/tracers of gene expression and protein localization, activity indicators, fluorescent resonance energy transfer (FRET) markers, cell lineage markers/tracers, reporters of gene expression and as markers/tracers in protein-protein interactions.