What parameter is crucial for determining the efficiency of GFP during transgene expression?

Fluorescence intensity is a key parameter in assessing the efficiency of Green Fluorescent Protein (GFP) during transgene expression because it directly correlates with the amount of GFP being produced and its functional activity within a cell. When the GFP gene is successfully expressed, the resulting protein fluoresces, and the intensity of this fluorescence can be quantitatively measured using techniques such as fluorescence microscopy or spectrophotometry. A higher fluorescence intensity indicates a greater expression of the transgene, reflecting both the successful translation of the RNA into protein and its subsequent folding into the correct three-dimensional structure necessary for functioning.

In contrast, while the size of the GFP gene can provide insights into cloning and expression construct design, it does not directly measure the efficiency of the expression in terms of protein output. The color of the organism can indicate the presence of GFP but is not a reliable measure of expression efficiency. Lastly, thermal stability of the protein can impact its functionality and longevity but does not directly correlate to the efficiency of transgene expression as measured by fluorescence. Thus, fluorescence intensity serves as the most direct and informative parameter for evaluating transgene expression efficiency in GFP studies.