Influence of the rod photoresponse on light adaptation and circadian rhythmicity in the cone ERG

Purpose: In the mammalian retina, rod and cone pathways are fundamentally intertwined, with signals from both converging on cone bipolar cells to reach retinal ganglion cells. Psychophysical and electrophysiological data suggests that, as a consequence, rod signal transduction has a suppressive effect on the activity of cone pathways. It therefore might be assumed that the balance between rod and cone input to cone bipolar cells would be subject to dynamic regulation. There is evidence of light and time-of-day dependent alterations in this parameter. Here we set out to determine the extent to which such changes in rod-cone pathway convergence explain alterations in cone pathway function associated with light adaptation and circadian phase by recording cone electroretinograms (ERGs) in mice deficient in rod phototransduction. Methods: Cone-isolated ERGs elicited by bright flashes superimposed on a rod saturating background light were recorded from wild-type and rod transducin deficient (Gnat1−/−) mice. The process of light adaptation was observed by tracing changes in the ERG waveform over 20 min exposure to the background light in these genotypes, and circadian control by comparing responses at subjective midday and midnight. Results: The cone ERG b-wave exhibited significantly enhanced amplitude and reduced latency (implicit time) in Gnat1−/− mice under all conditions. Light adaptation was associated with a robust increase in b-wave amplitude in Gnat1−/− mice but, in contrast to wild types, almost no change in implicit time. Gnat1−/− mice retained circadian rhythms in the cone ERG with b-wave amplitudes larger and latencies reduced during the subjective day. Conclusions: Rod phototransduction has a strong suppressive effect on the cone ERG. Light adaptation in cone pathways relies in part on reductions in this effect, although mechanisms intrinsic to cone pathways also play an important role. Similarly, while changes in coupling between rod and cone pathways over the course of the day may contribute to circadian regulation of the cone pathway they are not sufficient to explain circadian rhythms in the wild-type cone ERG

Up-beat UK: a programme of research into the relationship between coronary heart disease and depression in primary care patients.

Coronary heart disease and depression are both common health problems and by 2020 will be the two leading causes of disability worldwide. Depression has been found to be more common in patients with coronary heart disease but the nature of this relationship is uncertain. In the United Kingdom general practitioners are now being remunerated for case-finding for depression in patients with coronary heart disease, however it is unclear how general practitioners should manage these patients. We aim to explore the relationship between coronary heart disease and depression in a primary care population and to develop an intervention for patients with coronary heart disease and depression

Export of Ice Sheet Meltwater from Upernavik Fjord, West Greenland

Author Posting. © American Meteorological Society, 2022. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 52(3), (2022): 363–382, https://doi.org/10.1175/jpo-d-21-0084.1.Meltwater from Greenland is an important freshwater source for the North Atlantic Ocean, released into the ocean at the head of fjords in the form of runoff, submarine melt, and icebergs. The meltwater release gives rise to complex in-fjord transformations that result in its dilution through mixing with other water masses. The transformed waters, which contain the meltwater, are exported from the fjords as a new water mass Glacially Modified Water (GMW). Here we use summer hydrographic data collected from 2013 to 2019 in Upernavik, a major glacial fjord in northwest Greenland, to describe the water masses that flow into the fjord from the shelf and the exported GMWs. Using an optimum multi-parameter technique across multiple years we then show that GMW is composed of 57.8% ± 8.1% Atlantic Water (AW), 41.0% ± 8.3% Polar Water (PW), 1.0% ± 0.1% subglacial discharge, and 0.2% ± 0.2% submarine meltwater. We show that the GMW fractional composition cannot be described by buoyant plume theory alone since it includes lateral mixing within the upper layers of the fjord not accounted for by buoyant plume dynamics. Consistent with its composition, we find that changes in GMW properties reflect changes in the AW and PW source waters. Using the obtained dilution ratios, this study suggests that the exchange across the fjord mouth during summer is on the order of 50 mSv (1 Sv ≡ 106 m3 s−1) (compared to a freshwater input of 0.5 mSv). This study provides a first-order parameterization for the exchange at the mouth of glacial fjords for large-scale ocean models.This work was partially supported by the Centre for Climate Dynamics (SKD) at the Bjerknes Centre for Climate Research. The authors thank NASA and the OMG consortium for making observational data freely available, and acknowledge M. Morlighem for good support in the early stages of this project. MM and LHS and would also like to thank Ø. Paasche, the ACER project, and the U.S. Norway Fulbright Foundation for the Norwegian Arctic Chair Grant 2019–20 that made the visit to Scripps Institution of Oceanography possible. FS acknowledges support from the DOE Office of Science Grant DE-SC0020073, Heising-Simons Foundation and from NSF and OCE-1756272. DAS acknowledges support from U.K. NERC Grants NE/P011365/1, NE/T011920/1, and NERC Independent Research Fellowship NE/T011920/1. MW was supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, California Institute of Technology, administered by the Universities Space Research Association under contract with NASA. CSA would like to acknowledge Geocenter Denmark for support to the project “Upernavik Glacier.

Burning the candle at both ends: Intraretinal signaling of intrinsically photosensitive retinal ganglion cells

Intrinsically photosensitive retinal ganglion cells (ipRGCs) are photoreceptors located in the ganglion cell layer. They project to brain regions involved in predominately non-image-forming functions including entrainment of circadian rhythms, control of the pupil light reflex, and modulation of mood and behavior. In addition to possessing intrinsic photosensitivity via the photopigment melanopsin, these cells receive inputs originating in rods and cones. While most research in the last two decades has focused on the downstream influence of ipRGC signaling, recent studies have shown that ipRGCs also act retrogradely within the retina itself as intraretinal signaling neurons. In this article, we review studies examining intraretinal and, in addition, intraocular signaling pathways of ipRGCs. Through these pathways, ipRGCs regulate inner and outer retinal circuitry through both chemical and electrical synapses, modulate the outputs of ganglion cells (both ipRGCs and non-ipRGCs), and influence arrangement of the correct retinal circuitry and vasculature during development. These data suggest that ipRGC function plays a significant role in the processing of image-forming vision at its earliest stage, positioning these photoreceptors to exert a vital role in perceptual vision. This research will have important implications for lighting design to optimize the best chromatic lighting environments for humans, both in adults and potentially even during fetal and postnatal development. Further studies into these unique ipRGC signaling pathways could also lead to a better understanding of the development of ocular dysfunctions such as myopia

Iodine status during pregnancy in India and related neonatal and infant outcomes

Objective: To document iodine status in Indian pregnancies, associations with maternal diet and demographics, and offspring developmental measures. Design: Longitudinal study following mothers through pregnancy and offspring up to 24 months. Setting: Rural health-care centre (Vadu) and urban antenatal clinic (Pune) in the Maharashtra region of India. Subjects: Pregnant mothers at 17 (n 132) and 34 weeks’ (n 151) gestation and their infants from birth to the age of 24 months. Results: Median urinary iodine concentration (UIC) was 203 and 211 μg/l at 17 and 34 weeks of pregnancy, respectively (range 26–800 μg/l). Using the UIC distribution adjusted for within-person variation, extreme UIC quartiles were compared for predictors and outcomes. There was no correlation between UIC at 17 and 34 weeks, but 24 % of those with UIC in the lowest quartile at 17 weeks had UIC in the same lowest quartile at 34 weeks. Maternal educational, socio-economic status and milk products consumption (frequency) were different between the lowest and highest quartile of UIC at 34 weeks. Selected offspring developmental outcomes differed between the lowest and highest UIC quartiles (abdominal circumference at 24 months, subscapular and triceps skinfolds at 12 and 24 months). However, UIC was only a weak predictor of subscapular skinfold at 12 months and of triceps skinfold at 24 months. Conclusions: Median UIC in this pregnant population suggested adequate dietary provision at both gestational stages studied. Occasional high results found in spot samples may indicate intermittent consumption of iodine-rich foods. Maternal UIC had limited influence on offspring developmental outcomes

‘Novice Teachers’ Views of an Introductory Workshop about Teaching in the Biosciences.

Seven regional networking events, aimed at supporting and developing ‘early stage’ novice university bioscience teachers were held across the UK. These workshops allowed 230 participants to reflect on teaching styles, learn about Higher Education Academy resources and discuss strategies to deal with a range of teaching situations. Post-event feedback was sought, and the results are presented in this paper. Feedback on the events was overwhelmingly positive, highlighting the need for such events to support the development of new teachers in higher education. Institutional training varies and these opportunities for sharing experiences, asking questions, networking and reflection on teaching practice were highly regarded. Most participants felt more confident about their teaching and believed that students were more directly engaged in their teaching after attending the events. Recommendations for support of this category of teacher include provision of discipline-specific events, opportunity for local area networking and support for the development of reflective practice in teaching and learning

Field evaluation of a novel trap baited with carbon dioxide produced by yeast for the collection of female aedes aegypti mosquitoes in Mexico

Abstract. A trap made from low-cost materials and using an attractant of a yeast mixture producing carbon dioxide was designed and evaluated to collect adult Aedes aegypti (L.) mosquitoes. The Trap Mosquito Box prototype was tested against the “standards” BG-Sentinel traps and CDC backpack aspirator in the field. The mean numbers of mosquitoes (± standard deviation) caught by the three different collection methods were: Trap Mosquito Box 2.42 (± 3.08), BG-Sentinel trap 2.86 (± 3.71), and backpack aspirator 0.59 (± 0.90). Statistical tests showed the Trap Mosquito Box and BG-Sentinel trap were equally effective in collecting A. aegypti and both methods were significantly different than the backpack aspirator. Emission of carbon dioxide produced by the yeast mixture was greatest during the first hours after incubation in a laboratory and captured the most mosquitoes in the Trap Mosquito Box. Production of carbon dioxide [Y = -631.24 + 941.26 (log x)] and the rate of mosquitoes captured per time period [Y = 20.29 + 23.50 (log x)] were best explained by logarithmic regressions. Advantages and disadvantages of the Trap Mosquito Box for mosquito surveillance are discussed

UPBEAT-UK::a programme of research into the relationship between coronary heart disease and depression in primary care patients

Many people with coronary heart disease (CHD) are depressed and research on people who have had a heart attack found that depression increases the chance of further heart attacks. The UPBEAT-UK team conducted research with people on general practitioner CHD registers in 33 south London practices to: examine any link between CHD, depression and worse future heart disease; and develop case\ud management by practice nurses for people with CHD and depression. We followed 803 people with CHD for up to 3 years, assessing them for depression, chest pain and\ud worsening of heart disease, and also measured care costs. We asked patients, GPs and nurses how people with CHD and depression should be treated. From this, we developed care designed for each person called ‘personalised care’ (PC). We tested it in 41 people (while 40 people received their usual care from GPs)\ud with chest pain and depression, to assess how acceptable it is, whether or not it helps and what the costs would be. PC was acceptable to people, and those who received it reported less chest pain 6 and 12 months later. Costs were lower following PC but the difference was not statistically significant. Just under half of those with CHD had chest pain. Depression was frequent, but anxiety was more\ud common and increased the chances of both heart attacks and death. We conclude that further research is needed to understand the links between anxiety, chest pain and heart\ud disease, and to further develop our promising findings that PC can be helpful in reducing chest pain in\ud general practice