In this week’s PLoS Biology roundup, we feature research articles reporting new discoveries, ranging from sleep regulation to the role of heat shock proteins in disassembling the toxic protein aggregates that can feature in neurodegenerative disease, as well as a collection of articles on sustainable development that were published – together with an accompanying podcast – to coincide with the UN’s Rio +20 conference on this issue of global importance.
Regulating the brain’s wake up call
In an article published on June 19th, Peter McCormick and colleagues shed new light on the way in which our internal clock is hormonally regulated. All animals respond to cycles of light and dark with various patterns of sleeping, feeding, and other biological functions – so called circadian rhythms. The pineal gland in the brain is crucial for this response – it translates light signals received by the eye into signals that can be understood by the rest of the body, for example, the synthesis of the hormone melatonin, which is produced and released at night and which helps to regulate the body’s metabolic activity during sleep. González and colleagues now report that the synthesis and release of melatonin from the pineal gland is modulated by dopamine and adrenergic receptor complexes. Their findings reveal that when the neurotransmitter dopamine interacts with its receptors, it inhibits the effects of another neurotransmitter – the hormone norepinephrine – resulting in the decreased production and release of melatonin. Interestingly, the researchers found that these dopamine receptors only appear in the pineal gland towards the end of the night, leading them to conclude that the formation of these receptor complexes is an effective way to stop melatonin production when the day begins so as to ‘wake up’ the brain. As Janelle Weaver explains in an accompanying synopsis, these findings also advance our understanding of how the pineal gland is able to maintain precise control over the body’s internal clock.
Unfolding the role of heat shock proteins in amyloid disassembly
James Shorter and colleagues describe in their article how heat shock proteins, which are involved in the folding and unfolding of other proteins, work together to prevent the formation and regulate the disassembly of amyloid fibres, protein aggregates that are associated with numerous neurodegenerative disorders, such as Alzheimer’s and Parkinson’s disease. The authors began their study by defining how small heat-shock proteins synergize to regulate the assembly and disassembly of a beneficial prion in yeast. They then exploited this knowledge to discover an amyloid depolymerase machinery that is conserved from yeast to humans, which can disaggregate and disassemble these amyloid aggregates. How the discovery of this highly conserved amyloid-depolymerase system could impact the development of therapeutics for neurodegenerative disorders is also explored by this team.
Sustainability collection in PLoS Biology
Coinciding with the United Nation’s Rio+20 conference, PLoS Biology published three articles this week by leaders in ecology and conservation science, who raise important concerns about the physical limits on resource use that should be considered at the conference. In an Essay entitled, The Macroecology of Sustainability, Joseph Burger and colleagues discuss how global consumption rates of vital resources suggest that humans have surpassed the capacity of the Earth to sustain current levels (much less future trajectories) of growth in human population and economy. In a responding Perspective article, John Matthews and Frederick Boltz provide a more optimistic view with the argument that human ingenuity and adaptability may yet provide solutions that will allow human societies to overcome resource limitation and continue to grow. These opposing views are brought together in an Editorial by Georgina Mace, who concludes that while the viewpoints presented in the two articles differ in emphasis, the science behind both ought to be considered at Rio+20 this month. “Sustainability science needs much stronger connections with environmental sciences, including macroecology,” she argues.