"Não é o DNA, estúpido!"

A pergunta de um leitor no Art of Trolling:

"O que no DNA de um gato doméstico impede que ele cresça até o tamanho de um grande felino?"

E a resposta de outro leitor:

"Não está no DNA do Felis catus. Está no fato de que o DNA alinha suas partes por meio de uma fosfatase que existe no rato. E, ao comê-lo, é isso o que mantém o gato pequeno."

Mark Johnson, o autor da resposta, mostrou ainda - em detalhes - como a coisa se processa:

>refNM_053473.1 Rattus norvegicus protein phosphatase 1, regulatory (inhibitor) subunit 9A (Ppp1r9a), mRNA
gbU72994.1RNU72994 Rattus norvegicus neurabin mRNA,

complete cds Length=3850
GENE ID: 84685 Ppp1r9a protein phosphatase 1, regulatory (inhibitor) subunit
9A [Rattus norvegicus] (Over 10 PubMed links)
Sort alignments for this subject sequence by:
E value Score Percent identity
Query start position Subject start position
Score = 80.5 bits (43), Expect = 1e-11
Identities = 48/50 (96%), Gaps = 2/50 (4%)
Strand=Plus/Minus
Query 640 GTAGTTGCTGTTCTCAGCCTTCCCAGGAGTGATGGCACCTGG-GCACTCA 688
Sbjct 912 GTAGTTGCTGTTCTCAGCCTTCCCAGGAGTGATGGCACCTGGAG-ACTCA 864
Score = 78.7 bits (42), Expect = 5e-11
Identities = 42/42 (100%), Gaps = 0/42 (0%)
Strand=Plus/Minus
Query 799 TTCTCTCAAACATCTTTCGAGTCTCTGTGAACTTAGCATACG 840
Sbjct 673 TTCTCTCAAACATCTTTCGAGTCTCTGTGAACTTAGCATACG 632
Score = 78.7 bits (42), Expect = 5e-11
Identities = 42/42 (100%), Gaps = 0/42 (0%)
Strand=Plus/Minus
Query 759 CCTCTCCCGCTTTCTCTTTCTTTGGGGAATGGCGATTATTTT 800
Sbjct 733 CCTCTCCCGCTTTCTCTTTCTTTGGGGAATGGCGATTATTTT 692
Score = 78.7 bits (42), Expect = 5e-11
Identities = 44/45 (97%), Gaps = 0/45 (0%)
Strand=Plus/Minus
Query 720 CAAGGAATCACTGCTGCCTCTATTGGACTTGGAGCCACCCCTCTC 764
Sbjct 792 CAAGGAATCACTGCTGCCTCTATTGGACTTGGAGCCACCCCACTC 748
Score = 78.7 bits (42), Expect = 5e-11
Identities = 42/42 (100%), Gaps = 0/42 (0%)
Strand=Plus/Minus
Query 599 AGGTATCCAGATTGGTTACGGTAACAGATGGTAAGTTCAGGG 640
Sbjct 973 AGGTATCCAGATTGGTTACGGTAACAGATGGTAAGTTCAGGG 932
Score = 78.7 bits (42), Expect = 5e-11
Identities = 42/42 (100%), Gaps = 0/42 (0%)
Strand=Plus/Minus
Query 559 CTGTGTCGGTAGCTTGTTTGTTTGAAGAAGGCCTTGAATTAG 600
Sbjct 1033 CTGTGTCGGTAGCTTGTTTGTTTGAAGAAGGCCTTGAATTAG 992
Score = 75.0 bits (40), Expect = 7e-10
Identities = 40/40 (100%), Gaps = 0/40 (0%)
Strand=Plus/Minus
Query 681 GGCACTCAGTTGGCTCACAGTTGGAGAGACAGCCTCCGTC 720
Sbjct 849 GGCACTCAGTTGGCTCACAGTTGGAGAGACAGCCTCCGTC 810
Score = 65.8 bits (35), Expect = 4e-07
Identities = 35/35 (100%), Gaps = 0/35 (0%)
Strand=Plus/Minus
Query 526 ACCTTTCTGAGCCACTTCCGGTACTGGCACAGCCT 560
Sbjct 1086 ACCTTTCTGAGCCACTTCCGGTACTGGCACAGCCT 1052