In August 1961, at the International Congress of Biochemistry in Moscow, Nirenberg presented a paper to a small group of scientists, reporting the decoding of the first codon of the genetic code. Matthew Meselson, who was in the audience, spontaneously hugged Nirenberg at the end of the talk and then told Francis Crick about Nirenberg's result. Crick invited Nirenberg to repeat his performance the next day in a talk to a much larger audience. Speaking before the assembled congress of more than a thousand people, Nirenberg electrified the scientific community. He quickly received great scientific attention for these experiments. Within a few years, his research team had performed similar experiments and found that three-base repeats of adenosine (AAA) produced the amino acid lysine, and cytosine repeats (CCC) produced proline. The next breakthrough came when Philip Leder, a postdoctoral researcher in Nirenberg's lab, developed a method for determining the genetic code on pieces of tRNA (see "Nirenberg and Leder experiment"). This greatly sped up the assignment of three-base codons to amino acids so that 50 codons were identified in this way. Khorana's experiments confirmed these results and completed the genetic code translation.