Reddy's research group discovered the existence of circadian clocks in human red blood cells in 2011. This was a seminal finding for the field because before this study it was not thought that mammals could have a circadian clock without DNA, RNA production, or protein production. Thus, the red cell oscillations might be considered a type of biochemical or chemical oscillation, over a long time scale. Sir Christopher Dobson lauded the findings, and commented that this was akin to well established short period oscillations that occur in chemical systems. Other researchers in the circadian rhythms field called the work "exceptional" in post-publication peer review on Faculty of 1000. In collaboration with Andrew Millar's group in Edinburgh, Reddy's group also showed the existence of 24-hour oscillations that do not require RNA production in marine algae. This was also a major finding in the field, and was admired by multiple experts in the clocks field. Therefore, his group discovered circadian rhythms without the formation of new RNA in higher organisms for the first time. In 2012, Reddy's group showed that redox circadian oscillations are pervasive across evolutionary time, from bacteria to humans, using a new molecular window into the clock – peroxiredoxin proteins. Nobel laureate Michael Rosbash stated that "A more recent challenge to the PER-CLK transcription-centric animal model is the proposed role of metabolism and specifically peroxiredoxin hyperoxidation in circadian rhythms. A set of crucial experiments shows that these rhythms are independent of transcriptional rhythms in human red blood cells as well as in fly and mouse systems. Importantly, key aspects of the red blood cell experiments were independently replicated. As mammalian red blood cells lack nuclei and therefore transcription, aspects of this very important hypothesis are likely to be correct." In 2018, Reddy's team has shown the intimate links between core glucose metabolism and circadian transcriptional oscillations, as well as non-canonical circadian rhythms in clock-less fruit fly cells. These are, again, seen as landmark findings in the field, and substantiate the notion that we still do not have a complete understanding of molecular circadian rhythms in a range of organisms as yet.
Controversy
In December 2019, Reddy was suspended from medical practice for nine months by the Medical Practitioners Tribunal after receiving full-time salaries from two universities. University College London became aware in December 2016 that Reddy was receiving two salaries, and contacted the University of Cambridge. During their investigation, Reddy claimed that he noticed the salary issue in February 2016, five months after starting at UCL. He claimed that he thought the extra money was a salary "overlap", but also stated that he believed that the two universities were "sharing his salary". However, he also used £50,000 of the overpayment in order to make a mortgage payment, which the Medical Practitioners Tribunal cited as evidence that his statements were inconsistent, and that he was "financially aware" of the situation. The MPT investigated the case and suspended him for misconduct. According to the tribunal, he has since shown remorse and repaid the money. He remains suspended from practising medicine in the United Kingdom.
