Because of my responsibilities at Reasons to Believe, I spend a lot of time reading scientific magazines and journals. While I can make my way quickly through most of the articles, sometimes it takes me hours—even days—to read and process a single item published in a scientific journal, including those that are just a few pages long. And it’s not just the article length that determines my reading speed. The subject matter and organization of the piece make a difference, too.
Similar constraints confront the cell’s machinery when it reads, copies, and processes the information housed in genes. The rate of transcription1 depends on gene length. Longer genes take more time to transcribe than shorter ones. But researchers from Portugal have just discovered that genes’ content and organization also influence their transcription rate.2
This new insight provides researchers with a better understanding of how gene expression occurs in the early stages of embryo development. It also highlights the elegant design and exquisite molecular logic of biological systems—a feature that reflects the work of a Mind.
Researchers Study the Need for Rapid Gene Transcription
The team from Portugal was studying the early stages of fruit fly embryonic development, at which point the embryonic cells divide rapidly (in a highly specialized form of cell division known as syncytial nuclear division). Rapidly dividing cells require the quick transcription of genes. If transcription does not happen fast enough, critical proteins won’t be available to support essential activities as the cell prepares to divide. As it turns out, during this stage of development, the most highly expressed genes tend to be smaller in size. They also lack introns.
Introns are noncoding regions within genes. After messenger RNA is produced, the introns are excised and the remaining RNA fragments are spliced together. The splicing process takes time—time that rapidly dividing cells don’t have.
The research team from Portugal discovered that 70 percent of the genes expressed during the early stages of embryonic development lack introns. Interestingly, only 20 percent of the genes, overall, in the fruit fly genome are intronless. So, clearly the size and structure of essential genes for the early stages of embryonic development have been optimized so they can be transcribed in a timely manner.
The researchers performed additional experiments to confirm this conclusion. In one study, they produced fruit flies with mutations to the genes for the cellular machinery that removes introns. They discovered that these mutations had no effect on the early stages of fruit fly embryogenesis (because most of the essential genes are intronless), but had devastating consequences later on in development when genes with introns are expressed at high levels.
They also incorporated a complex multi-intron gene into the fruit fly genome and rigged the gene so it would be expressed during the early stages of embryogenesis. The cells of the early-stage embryo couldn’t properly splice out the introns when this gene was transcribed.
The researchers think they have uncovered an important feature of early gene expression in embryogenesis. They also have exposed a relationship between gene structure and size and the rate of transcription that most likely applies to all rapidly dividing cells, not just those of fruit fly embryos.
Elegant Gene Architecture Reflects a Creator’s Hand
The optimization of gene size and architecture is just one more example of the superior molecular logic that undergirds biochemical systems. As a graduate student I recognized the elegance, sophistication, and cleverness of life’s chemical systems—and that realization played a role in convincing me a Creator must be responsible for life. (See “Biochemistry and the Bible: Collaborators in Design.”) Over the last three decades, as we’ve learned more about the structural design and operation of biochemical systems, the brilliance of life’s molecular logic shines even brighter. Because of this, I am more convinced than ever that life’s origin is the work of a Creator.
The Portugal research team attributes the optimal gene size and structure to evolutionary processes, which they believe shaped the genes over time for efficient transcription. Ironically, the team’s own experiments with genetically engineered and mutant embryos undermine their explanation.
For example, the experiments demonstrated that the early embryo’s rapidly dividing cells couldn’t effectively transcribe and process genes with several introns. If intron-laden genes happen to be essential for the early stage embryo, the embryonic cells won’t be able to divide, or at least, divide correctly, resulting in the death of the embryo. (A rule of thumb, disruptions to embryogenesis are much more catastrophic the earlier they occur in development.) Thus, the embryo will never develop into a reproductively mature individual, precluding evolutionary processes from shaping gene size and structure. To put it another way, the optimal gene size and architecture must be in place from the beginning for proper embryogenesis.
As we learn more and more about the structure and function of biochemical systems, the need to read between the lines lessens. The writing is on the wall: the elegant designs found throughout the biological realm evince the work of a Creator. It’s time to turn the page on the evolutionary paradigm.
- During transcription, the cell’s machinery reads and copies the information found in genes to produce messenger RNA molecules. These molecules, in turn, make their way to the ribosome, where they direct the production of proteins.
- Leonardo Gastón Guilgur et al., “Requirement for Highly Efficient Pre-mRNA Splicing during Drosophila Early Embryonic Development,” eLife (April 22, 2014): DOI: 10.7554/eLife.02181.