ORCID Profile
0000-0003-2141-4707
Current Organisations
University of Sheffield
,
University of California, Irvine
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Publisher: American Astronomical Society
Date: 03-08-2023
Abstract: TOI-1899 b is a rare exoplanet, a temperate warm Jupiter orbiting an M dwarf, first discovered by Cañas et al. (2020) from a TESS single-transit event. Using new radial velocities (RVs) from the precision RV spectrographs HPF and NEID, along with additional TESS photometry and ground-based transit follow-up, we are able to derive a much more precise orbital period of P = 29.090312 − 0.000035 + 0.000036 days, along with a radius of R p = 0.99 ± 0.03 R J . We have also improved the constraints on planet mass, M p = 0.67 ± 0.04 M J , and eccentricity, which is consistent with a circular orbit at 2 σ ( e = 0.044 − 0.027 + 0.029 ). TOI-1899 b occupies a unique region of parameter space as the coolest known ( T eq ≈ 380 K) Jovian-sized transiting planet around an M dwarf we show that it has great potential to provide clues regarding the formation and migration mechanisms of these rare gas giants through transmission spectroscopy with JWST, as well as studies of tidal evolution.
Publisher: Wiley
Date: 06-2002
DOI: 10.1046/J.1365-313X.2002.01320.X
Abstract: A number of important cellular events in animals and yeast are regulated by protein degradation, and it is becoming apparent that such regulated proteolysis is involved in many facets of plant physiology and development. We have investigated the role of protein degradation by proteasomes in plants using NtPSA1, a tobacco gene that is predominantly expressed in young developing tobacco tissues and has extensive homology to yeast and human alpha-type proteasome subunit genes. The NtPSA1 cDNA was used to complement a lethal mutation of the yeast PRC1 alpha subunit gene indicating that NtPSA1 encodes a functional proteasome subunit, and transient expression of an NtPSA1::GUS protein fusion in onion cells confirmed that the nuclear localisation signal that is present in the NtPSA1 peptide sequence is active in plant cells. Plants transformed with an antisense NtPSA1 gene had reduced levels of NtPSA1 mRNA and exhibited reduced apical dominance. In addition, these low NtPSA1 plants displayed several morphological defects associated with auxin resistance such as reduced stamen length, and showed increased tolerance to high concentrations of auxin. These results support a role for nuclear localised proteasomes in floral development and auxin responses.
Publisher: Springer Science and Business Media LLC
Date: 27-06-2019
DOI: 10.1038/S41467-019-10826-5
Abstract: The formation of stomata and leaf mesophyll airspace must be coordinated to establish an efficient and robust network that facilitates gas exchange for photosynthesis, however the mechanism by which this coordinated development occurs remains unclear. Here, we combine microCT and gas exchange analyses with measures of stomatal size and patterning in a range of wild, domesticated and transgenic lines of wheat and Arabidopsis to show that mesophyll airspace formation is linked to stomatal function in both monocots and eudicots. Our results support the hypothesis that gas flux via stomatal pores influences the degree and spatial patterning of mesophyll airspace formation, and indicate that this relationship has been selected for during the evolution of modern wheat. We propose that the coordination of stomata and mesophyll airspace pattern underpins water use efficiency in crops, providing a target for future improvement.
Publisher: Cold Spring Harbor Laboratory
Date: 21-08-2023
DOI: 10.1101/2023.08.21.554086
Abstract: The phytohormone salicylic acid (SA) is an important molecular signal that mediates pathogen defence mechanisms, including triggering Arabidopsis immune responses to the hemi-biotroph Pseudomonas syringae pv. tomato ( Pst ). SA induces the expression of a myriad of defence genes via its receptor and transcriptional regulator NONEXPRESSER OF PR GENES 1 (NPR1). Here, we used chlorophyll fluorescence imaging of F v /F m , to detect damage to photosystem II before Pst -induced disease symptoms were visible. We observed that the pathogen only induced damage, and subsequent cell death, in mature leaves while developing leaves in the center of the rosette appeared to be protected. However, in the npr1-1 mutant, Pst -infected mature leaves were able to systemically transmit a signal that caused damage to the photosynthetic machinery in uninfected young leaves. Reductions in F v /F m could also be induced systemically in developing npr1-1 leaves by high levels of SA in mature leaves, and rescued by SA biosynthesis deficiency in npr1-1sid2-2 mutants. Together, these results indicate that, in addition to its well-known role as a positive regulator of SA responses, NPR1 also acts to suppress SA-dependent immune responses and thereby protects developing leaves from autoimmune damage.
Publisher: Elsevier BV
Date: 04-2018
Location: United Kingdom of Great Britain and Northern Ireland
Location: United States of America
No related grants have been discovered for Stephen Rolfe.