Chapter 13 Post

Hello everyone! Long time no blog! This week's chapter is titled Gene Regulation. It focuses on regulation of transcription in bacteria, regulation of transcription in eukaryotes, and regulation of RNA processing and translation in eukaryotes.


This article from PubMed is about lac operon induction in Escherichia coli, a systematic comparison of IPTG and TMG induction and influence of the transacetylase LacA. The most frequently used expression systems in bacteria are based on the Escherichia coli lac promoter. Moreover, lac operon elements are used today in systems and synthetic biology. In a handful of cases the inducers IPTG or TMG are used. Here the author reported a comparison of lac promoter induction by TMG and IPTG which focuses on the aspects inducer uptake, population heterogeneity and a potential influence of the transacetylase, LacA. They provided induction curves in E. coli LJ110 and in isogenic lacY and lacA mutant strains and they showed that both inducers are substrates of the lactose permease at low inducer concentrations but can also enter cells independently of lactose permease if present at higher concentrations. Using a gfp reporter strain they compared TMG and IPTG induction at a single cell level and showed that bimodal induction with IPTG occurred at approximately ten-fold lower concentrations than with TMG. In addition, they observed that lac operon induction is influenced by the transacetylase, LacA. By comparing two Plac-gfp reporter strains with and without a lacA deletion they could show that in the lacA(+) strain the fluorescence level decreased after few hours while the fluorescence further increased in the lacA(-) strain. The results showed that through the activity of LacA the IPTG concentration can be reduced below an inducing threshold concentration, an influence that should be considered if low inducer amounts are used.


This article, titled, Clock Genes Might Control the Sleep We Need, focuses on Clock genes, which are long known to regulate our circadian rhythms, and also give clues to what makes sleep so persistent. Sleep is the one thing we can’t cheat. We lose it in our busy lives but yet our brains, surprisingly keep score – and force payback as soon as we lie down. And if it’s big, we sleep in, sometimes missing important activities. A clue has emerged from new research published in BioMed Central Neuroscience. Researchers have found that the expression of genes called “clock genes” are highly correlated with the need for sleep. It’s shown that clock genes regulate our 24-hour circadian rhythm – but researchers say these genes also appear to control the persistence of sleep. Researchers studied some mice that need a lot of sleep and those who need little sleep. They found that for mice the expression of clock genes increased the longer an animal stayed awake, and decreased when the animal was in recovery sleep.

The video above talks about the lac operon. It's a good animation about the process. As I was researching videos on YouTube, I was questioning the validity and trustworthiness of some videos. I ended choosing this one partly because it came from a textbook. Also, the animations are good and the information is detailed and clear. I like that the text is displayed at the side because reading information, in addition to hearing it, helps me learn better. I would suggest watching this video.