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Purpose: The Predicting Myopia Onset and progression (PreMO) risk indicator, developed using data generated from white children in the UK, incorporates age, spherical equivalent refraction (SER), axial length (AL) and parental myopia to stratify the likelihood of developing myopia. This study evaluated the PreMO's predictive accuracy using prospective datasets from independent samples of children in Hong Kong (HK) and an ethnically diverse cohort of children in the United Kingdom., Methods: Non-myopic children (SER > -0.50 D) aged 6-8 and 9-10 years were scored using the PreMO risk indicator framework, integrating baseline cycloplegic SER, AL and parental myopia data. Scores were assigned risk categories as follows: 0 = no risk, 1-3 = low risk, 4-6 = moderate risk and 7-9 = high risk. SER at ≥15 years of age was used to define refractive outcomes as 'myopic' or 'not myopic'. PreMO's predictive accuracy was analysed via Receiver Operator Characteristic curves, with Youden's J-Index identifying the optimal risk score threshold. Sensitivity, specificity and area under the curve were determined and compared with those of singular predictors, that is, SER < +0.75 D and AL ≥ 23.07 mm at 6-8 years., Results: In the cohort of children aged 6-8 years, a PreMO risk score ≥ 4 exhibited high sensitivity in predicting myopia onset in UK (0.97) and HK (0.94) children, with high specificity in UK (0.96) and moderate specificity in HK (0.64) children. In UK children aged 6-8 years, the PreMO outperformed singular predictors such as SER and AL. Among HK children aged 9-10 years, the PreMO score maintained high sensitivity (0.90) and moderate specificity (0.72)., Conclusions: A PreMO risk score ≥ 4 is a strong predictive indicator for future myopia onset, particularly in UK children. Despite high sensitivity in both UK and HK cohorts, specificity varied, indicating the need for contextual application of the tool, particularly in pre-myopic Asian children., (© 2024 The Author(s). Ophthalmic and Physiological Optics published by John Wiley & Sons Ltd on behalf of College of Optometrists.)

Purpose: Previous studies have demonstrated an association between melatonin status and both refractive error and axial length in young adult myopes. This study aimed to determine if this relationship extends to a younger adolescent cohort., Methods: Healthy children aged 12-15 years provided morning saliva samples before attending Ulster University (55°N) for cycloplegic autorefraction and axial length measures. Participants completed questionnaires describing recent sleep habits and physical activity. Salivary melatonin was quantified using high-performance liquid chromatography-tandem mass spectrometry. Data collection for all participants occurred over a 1-week period (April 2021)., Results: Seventy participants aged 14.3 (95% CI: 14.2-14.5) years were categorised by spherical equivalent refraction [SER] (range: -5.38DS to +1.88DS) into two groups; myopic SER ≤ -0.50DS ( n  = 22) or nonmyopic -0.50DS < SER ≤ +2.00DS ( n  = 48). Median morning salivary melatonin levels were 4.52 pg/ml (95% CI: 2.60-6.02) and 4.89 pg/ml (95% CI: 3.18-5.66) for myopic and nonmyopic subjects, respectively, and did not differ significantly between refractive groups ( P  = 0.91). Melatonin levels were not significantly correlated with SER, axial length, sleep, or activity scores (Spearman's rank, all P  > 0.39). Higher levels of physical activity were associated with higher sleep quality (Spearman's rank, ρ  = -0.28, P  = 0.02)., Conclusion: The present study found no significant relationship between morning salivary melatonin levels and refractive error or axial length in young adolescents. This contrasts with outcomes from a previous study of adults with comparable methodology, season of data collection, and geographical location. Prospective studies are needed to understand the discrepancies between adult and childhood findings and evaluate whether melatonin levels in childhood are indicative of an increased risk for future onset of myopia and/or faster axial growth trajectories and myopia progression in established myopes. Future work should opt for a comprehensive dim-light melatonin onset protocol to determine circadian phase., Competing Interests: The authors declare that there are no conflicts of interest regarding the publication of this paper., (Copyright © 2023 Jane M. Fulton et al.)

Increased anthropogenic nutrient loading has led to eutrophication of aquatic ecosystems, which is the major cause of harmful cyanobacteria blooms. Element stoichiometry of cyanobacteria bloom is subject to nutrient availabilities and may significantly contribute to primary production and biogeochemical cycling. Phycobilisome is the antenna of the photosynthetic pigment apparatus in cyanobacteria, which contains phycobilin pigments (PBPs) and linker proteins. This nitrogen (N)-rich protein complex has the potential to support growth as a N-storage site and may play a major role in the variability of cyanobacteria N stoichiometry. However, the regulation of PBPs during bloom formation remains unclear. We investigated the temporal variation of N allocation into PBPs and element stoichiometry for two ubiquitous cyanobacteria species, Microcystis aeruginosa and Dolichospermum flos-aquae , in a batch culture experiment with different initial N availabilities. Our results indicated that the N allocation into PBPs is species-dependent and tightly regulated by the availability of nutrients fueling population expansion. During the batch culture experiment, different nutrient uptake rates led to distinct stoichiometric imbalances of N and phosphorus (P), which substantially altered cyanobacteria C: N and C: P stoichiometry. Microcystis invested cellular N into PBPs and exhibited greater flexibility in C: N and C: P stoichiometry than D. flos-aquae . The dynamics of such N-rich macromolecules may help explain the N stoichiometry variation during a bloom and the interspecific difference between M. aeruginosa and D. flos-aquae . Our study provides a quantitative understanding of the elemental stoichiometry and the regulation of PBPs for non-diazotrophic and diazotrophic cyanobacteria blooms., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Wang, Wagner, Fulton and Scott.)

Archaeal ANaerobic MEthanotrophs (ANME) facilitate the anaerobic oxidation of methane (AOM), a process that is believed to proceed via the reversal of the methanogenesis pathway. Carbon isotopic composition studies indicate that ANME are metabolically diverse and able to assimilate metabolites including methane, methanol, acetate, and dissolved inorganic carbon (DIC). Our data support the interpretation that ANME in marine sediments at methane seeps assimilate both methane and DIC, and the carbon isotopic compositions of the tetrapyrrole coenzyme F430 and the membrane lipids archaeol and hydroxy-archaeol reflect their relative proportions of carbon from these substrates. Methane is assimilated via the methyl group of CH 3 -tetrahydromethanopterin (H 4 MPT) and DIC from carboxylation reactions that incorporate free intracellular DIC. F430 was enriched in 13 C (mean δ 13 C = -27‰ for Hydrate Ridge and -80‰ for the Santa Monica Basin) compared to the archaeal lipids (mean δ 13 C = -97‰ for Hydrate Ridge and -122‰ for the Santa Monica Basin). We propose that depending on the side of the tricarboxylic acid (TCA) cycle used to synthesize F430, its carbon was derived from 76% DIC and 24% methane via the reductive side or 57% DIC and 43% methane via the oxidative side. ANME lipids are predicted to contain 42% DIC and 58% methane, reflecting the amount of each assimilated into acetyl-CoA. With isotope models that include variable fractionation during biosynthesis for different carbon substrates, we show the estimated amounts of DIC and methane can result in carbon isotopic compositions of - 73‰ to - 77‰ for F430 and - 105‰ for archaeal lipids, values close to those for Santa Monica Basin. The F430 δ 13 C value for Hydrate Ridge was 13 C-enriched compared with the modeled value, suggesting there is divergence from the predicted two carbon source models., (© 2019 John Wiley & Sons Ltd.)

The carbon and nitrogen isotopic signatures of chloropigments and porphyrins from the sediments of redox-stratified lakes and marine basins reveal details of past biogeochemical nutrient cycling. Such interpretations are strengthened by modern calibration studies, and here, we report on the C and N isotopic composition of pigments and nutrients in the water column and surface sediment of redox-stratified Fayetteville Green Lake (FGL; New York). We also report δ 13 C and δ 15 N values for pyropheophytin a (Pphe a) and bacteriochlorophyll e (Bchl e) deposited in the Black Sea during its transition to a redox-stratified basin ca. 7.8 ka. We propose a model for evolving nutrient cycling in the Black Sea from 7.8 to 6.4 ka, informed by the new pigment data from FGL. The seasonal study of water column nutrients and pigments at FGL revealed population dynamics in surface and deep waters that were also captured in the sediments. Biomass was greatest near the chemocline, where cyanobacteria, purple sulfur bacteria (PSB), and green sulfur bacteria (GSB) had seasonally variable populations. Bulk organic matter in the surface sediment, however, was derived mainly from the oxygenated surface waters. Surface sediment pigment δ 13 C and δ 15 N values indicate intact chlorophyll a (Chl a) was derived from near the chemocline, but its degradation product pheophytin a (Phe a) was derived primarily from surface waters. Bacteriopheophytin a (Bphe a) and Bchl e in the sediments came from chemocline populations of PSB and GSB, respectively. The distinctive δ 13 C and δ 15 N values for Chl a, Phe a, and Bphe a in the surface sediment are inputs to an isotopic mixing model that shows their decomposition to a common porphyrin derivative can produce non-specific sedimentary isotope signatures. This model serves as a caveat for paleobiogeochemical interpretations in basins that had diverse populations near a shallow chemocline., (© 2018 John Wiley & Sons Ltd.)

Little Salt Spring (Sarasota County, FL, USA) is a sinkhole with groundwater vents at ~77 m depth. The entire water column experiences sulfidic (~50 μM) conditions seasonally, resulting in a system poised between oxic and sulfidic conditions. Red pinnacle mats occupy the sediment-water interface in the sunlit upper basin of the sinkhole, and yielded 16S rRNA gene clones affiliated with Cyanobacteria, Chlorobi, and sulfate-reducing clades of Deltaproteobacteria. Nine bacteriochlorophyll e homologues and isorenieratene indicate contributions from Chlorobi, and abundant chlorophyll a and pheophytin a are consistent with the presence of Cyanobacteria. The red pinnacle mat contains hopanoids, including 2-methyl structures that have been interpreted as biomarkers for Cyanobacteria. A single sequence of hpnP, the gene required for methylation of hopanoids at the C-2 position, was recovered in both DNA and cDNA libraries from the red pinnacle mat. The hpnP sequence was most closely related to cyanobacterial hpnP sequences, implying that Cyanobacteria are a source of 2-methyl hopanoids present in the mat. The mats are capable of light-dependent primary productivity as evidenced by 13 C-bicarbonate photoassimilation. We also observed 13 C-bicarbonate photoassimilation in the presence of DCMU, an inhibitor of electron transfer to Photosystem II. Our results indicate that the mats carry out light-driven primary production in the absence of oxygen production-a mechanism that may have delayed the oxygenation of the Earth's oceans and atmosphere during the Proterozoic Eon. Furthermore, our observations of the production of 2-methyl hopanoids by Cyanobacteria under conditions of low oxygen and low light are consistent with the recovery of these structures from ancient black shales as well as their paucity in modern marine environments., (© 2017 The Authors. Geobiology Published by John Wiley & Sons Ltd.)