Katharine E. Hubbard

The Arabidopsis circadian clock incorporates a cADPR-based feedback loop

Transcriptional feedback loops are a feature of circadian clocks in both animals and plants. We show that the plant circadian clock also incorporates the cytosolic signaling molecule cyclic adenosine diphosphate ribose (cADPR). cADPR modulates the circadian oscillators transcriptional feedback loops and drives circadian oscillations of Ca2+ release. The effects of antagonists of cADPR signaling, manipulation of cADPR synthesis, and mathematical simulation of the interaction of cADPR with the circadian clock indicate that cADPR forms a feedback loop within the plant circadian clock.

How plants tell the time

Plants, like all eukaryotes and most prokaryotes, have evolved sophisticated mechanisms for anticipating predictable environmental changes that arise due to the rotation of the Earth on its axis. These mechanisms are collectively termed the circadian clock. Many aspects of plant physiology, metabolism and development are under circadian control and a large proportion of the transcriptome exhibits circadian regulation. In the present review, we describe the advances in determining the molecular nature of the circadian oscillator and propose an architecture of several interlocking negative-feedback loops. The adaptive advantages of circadian control, with particular reference to the regulation of metabolism, are also considered. We review the evidence for the presence of multiple circadian oscillator types located in within individual cells and in different tissues.

Correct biological timing in Arabidopsis requires multiple light-signaling pathways

Circadian oscillators provide rhythmic temporal cues for a range of biological processes in plants and animals, enabling anticipation of the day/night cycle and enhancing fitness-associated traits. We have used engineering models to understand the control principles of a plant’s response to seasonal variation. We show that the seasonal changes in the timing of circadian outputs require light regulation via feed-forward loops, combining rapid light-signaling pathways with entrained circadian oscillators. Linear time-invariant models of circadian rhythms were computed for 3,503 circadian-regulated genes and for the concentration of cytosolic-free calcium to quantify the magnitude and timing of regulation by circadian oscillators and light-signaling pathways. Bioinformatic and experimental analysis show that rapid light-induced regulation of circadian outputs is associated with seasonal rephasing of the output rhythm. We identify that external coincidence is required for rephasing of multiple output rhythms, and is therefore important in general phase control in addition to specific photoperiod-dependent processes such as flowering and hypocotyl elongation. Our findings uncover a fundamental design principle of circadian regulation, and identify the importance of rapid light-signaling pathways in temporal control.

Circadian Rhythms in Stomata: Physiological and Molecular Aspects

Stomata are the major route of gas exchange between the atmosphere and the leaf interior. The size of the stomatal pore is controlled by the movements of the stomatal guard cells. The guard cells close the stomatal pore to conserve water during stress. In more favourable conditions, the stomatal movements optimise CO2 uptake whilst minimising water loss. The movements of stomata are controlled by an extensive network of signalling pathways responding to diverse stimuli. One of the regulators of stomata is the circadian clock. We discuss the physiological mechanisms by which the clock might regulate stomatal movements and the benefits that circadian regulation of stomatal behaviour could confer to the plant.

Circadian Rhythms: FLOWERING LOCUS T Extends Opening Hours

Plants are more sensitive to light in the day than at night due to the circadian clock. The protein that acts downstream from the clock to modulate blue light signalling in stomata comes as a surprise; it is FT, which is thought to be the long-distance regulator of flowering.

Circadian oscillations of cytosolic free calcium regulate the Arabidopsis circadian clock

In the last decade, the view of circadian oscillators has expanded from transcriptional feedback to incorporate post-transcriptional, post-translational, metabolic processes and ionic signalling. In plants and animals, there are circadian oscillations in the concentration of cytosolic free Ca2+ ([Ca2+]cyt), though their purpose has not been fully characterized. We investigated whether circadian oscillations of [Ca2+]cyt regulate the circadian oscillator of Arabidopsis thaliana. We report that in Arabidopsis, [Ca2+]cyt circadian oscillations can regulate circadian clock function through the Ca2+-dependent action of CALMODULIN-LIKE24 (CML24). Genetic analyses demonstrate a linkage between CML24 and the circadian oscillator, through pathways involving the circadian oscillator gene TIMING OF CAB2 EXPRESSION1 (TOC1).The circadian clock involves daily variations in transcription of a set of core genes. Here, the authors show that oscillations in free calcium concentration, read by calmodulin-like proteins, regulate the clock and are part of this complex mechanism.

Perceptions of scientific research literature and strategies for reading papers depend on academic career stage

Reading primary research literature is an essential skill for all scientists and students on science degree programmes, however little is known about how researchers at different career stages interact with and interpret scientific papers. To explore this, we conducted a survey of 260 undergraduate students and researchers in Biological Sciences at a research intensive UK university. Responses to Likert scale questions demonstrated increases in confidence and skill with reading the literature between individuals at each career stage, including between postdoctoral researchers and faculty academics. The survey indicated that individuals at different career stages valued different sections of scientific papers, and skill in reading the results section develops slowly over the course of an academic career. Inexperienced readers found the methods and results sections of research papers the most difficult to read, and undervalued the importance of the results section and critical interpretation of data. These data highlight a need for structured support with reading scientific literature at multiple career stages, and for senior academics to be aware that junior colleagues may prioritise their reading differently. We propose a model for the development of literature processing skills, and consider the need for training strategies to help inexperienced readers engage with primary literature, and therefore develop important skills that underpin scientific careers. We also encourage researchers to be mindful of language used when writing papers, and to be more inclusive of diverse audiences when disseminating their work.

The Student Thesis Conference as a model for authentic and inclusive student research dissemination

ABSTRACT Engaging in a final year project is required in most undergraduate degree programmes. However, the student research experience often differs from the academic experience due to a lack of opportunities for research dissemination. We present the Student Thesis Conference as an innovative research dissemination model used in Sports Science degrees at the University of Hull. The 500 delegate conference is embedded throughout the programme; first year students attend as delegates, second years present their dissertation proposals as posters and final year students give oral presentations of their research findings. We determine that the conference engages students of all abilities, and students see the conference primarily in terms of improving communication skills. We show that the conference increases student confidence in presentation skills, demonstrating the impact of communication to larger audiences. The conference is an inclusive and authentic model of undergraduate research dissemination, and could be widely adopted throughout the sector.

Rhythms of Life

Summary This teaching tool explores circadian rhythms in plants. The topic is presented as a series of concepts illustrated by examples, including the architecture of circadian clocks and the connections between the oscillator and circadian-regulated processes such as metabolism and flowering. The Teaching Tool introduces some of the techniques used to investigate circadian biology and explores how understanding circadian rhythms could lead to crop improvement.

Challenges and opportunities for early-career Teaching-Focussed academics in the biosciences

Twenty-seven percent of academics in UK Higher Education (HE) are in Teaching-Focussed positions, making major contributions to undergraduate programmes in an era of high student expectations when it comes to teaching quality. However, institutional support for Teaching-Focussed academics is often limited, both in terms of peer networking and opportunities for career development. As four early-career stage Teaching-Focussed academics working in a variety of institutions, we explore what motivated our choices to make teaching our primary academic activity, and the challenges that we have faced in doing so. In addition to highlighting the need for universities to fully recognise the achievements of teaching staff, we discuss the role that the various biosciences learned societies have in supporting Teaching-Focussed academics. We identify that there is a need for the learned societies to come together and pool their expertise in this area. The fragmented nature of the Teaching-Focussed academic community means that clear sources of national support are needed in order to best enable the next generation of bioscience educators to reach their full potential.