The majority of Cockayne syndrome (CS) patients carry a mutation in Cockayne Syndrome group B (CSB), a large nuclear protein implicated in DNA repair, transcription and chromatin remodeling. However, ...whether CSB may play a role in telomere metabolism has not yet been characterized. Here, we report that CSB physically interacts with TRF2, a duplex telomeric DNA binding protein essential for telomere protection. We find that CSB localizes at a small subset of human telomeres and that it is required for preventing the formation of telomere dysfunction-induced foci (TIF) in CS cells. We find that CS cells or CSB knockdown cells accumulate telomere doublets, the suppression of which requires CSB. We find that overexpression of CSB in CS cells promotes telomerase-dependent telomere lengthening, a phenotype that is associated with a decrease in the amount of telomere-bound TRF1, a negative mediator of telomere length maintenance. Furthermore, we show that CS cells or CSB knockdown cells exhibit misregulation of TERRA, a large non-coding telomere repeat-containing RNA important for telomere maintenance. Taken together, these results suggest that CSB is required for maintaining the homeostatic level of TERRA, telomere length and integrity. These results further imply that CS patients carrying CSB mutations may be defective in telomere maintenance.
Acoustic surveys of the distribution and abundance of freshwater zooplankton were conducted in Lake Giles, an oligotrophic freshwater lake. Volume backscatter data from a 710 kHz scientific ...echosounder were converted to high‐resolution spatial and temporal numerical density estimates of small zooplankton. Vertical net tows of a 153 μm mesh closing bongo net at multiple depth intervals provided both identification of the types and sizes (0.5–1.5 mm length) of crustacean zooplankton present in the lake as well as an independent measurement of zooplankton numerical density. Net and acoustic estimates of zooplankton abundance, biovolume, and distribution were very similar. The improved resolution of the high‐frequency acoustic sampling provides insight into several aspects of freshwater zooplankton ecology including: separation of migrating and non‐migrating zooplankton, high resolution measurements of in situ zooplankton biovolume, calculation of in situ vertical velocities of migrating zooplankton, and fine‐scale (sub‐meter) horizontal and vertical zooplankton distribution during daytime, nighttime, and vertical migration events. These methods allow for more detailed and accurate estimates of zooplankton distribution than traditional net sampling methods can provide, including determining the total abundance of organisms within a specific habitat. They also provide higher resolution data in both space and time of smaller zooplankton taxa than have been measured previously in freshwater ecosystems.
The relative importance of top-down vs. bottom-up control of phytoplankton biomass in aquatic ecosystems has been long debated and studied. However, few studies have considered the relative ...importance of top-down vs. bottom-up control on phytoplankton vertical distributions and characteristics of deep chlorophyll maxima (DCMs), and fewer still have investigated the importance of these drivers for multiple phytoplankton groups. We examined depth profiles of four phytoplankton spectral groups and a suite of top-down (zooplankton) and bottom-up (nutrients, temperature, and light) drivers from 51 north temperate lakes varying on gradients of size, trophic state, light availability, and thermal stratification. We used regression trees to identify the most important drivers of different vertical distribution metrics for each phytoplankton spectral group. The relative importance of top-down vs. bottom-up control varied across spectral groups and was related to the characteristics of the dominant taxa within each spectral group, as assessed by microscope counts. Zooplankton biomass was the most important driver of brown algae vertical distributions, likely because this group contained highly edible taxa (primarily chrysophytes), while thermal stratification predicted vertical distributions of buoyancy-regulating cyanobacteria. Our work highlights the importance of examining phytoplankton community composition to improve understanding of DCM characteristics and top-down vs. bottom-up control of phytoplankton in aquatic systems.
The vertical distribution of chlorophyll in stratified lakes and reservoirs frequently exhibits a maximum peak deep in the water column, referred to as the deep chlorophyll maximum (DCM). DCMs are ...ecologically important hot spots of primary production and nutrient cycling, and their location can determine vertical habitat gradients for primary consumers. Consequently, the drivers of DCM structure regulate many characteristics of aquatic food webs and biogeochemistry. Previous studies have identified light and thermal stratification as important drivers of summer DCM depth, but their relative importance across a broad range of lakes is not well resolved. We analyzed profiles of chlorophyll fluorescence, temperature, and light during summer stratification from 100 lakes in the Global Lake Ecological Observatory Network (GLEON) and quantified two characteristics of DCM structure: depth and thickness. While DCMs do form in oligotrophic lakes, we found that they can also form in eutrophic to dystrophic lakes. Using a random forest algorithm, we assessed the relative importance of variables associated with light attenuation vs. thermal stratification for predicting DCM structure in lakes that spanned broad gradients of morphometry and transparency. Our analyses revealed that light attenuation was a more important predictor of DCM depth than thermal stratification and that DCMs deepen with increasing lake clarity. DCM thickness was best predicted by lake size with larger lakes having thicker DCMs. Additionally, our analysis demonstrates that the relative importance of light and thermal stratification on DCM structure is not uniform across a diversity of lake types.
Concurrent regional and global environmental changes are affecting freshwater ecosystems. Decadal-scale data on lake ecosystems that can describe processes affected by these changes are important as ...multiple stressors often interact to alter the trajectory of key ecological phenomena in complex ways. Due to the practical challenges associated with long-term data collections, the majority of existing long-term data sets focus on only a small number of lakes or few response variables. Here we present physical, chemical, and biological data from 28 lakes in the Adirondack Mountains of northern New York State. These data span the period from 1994-2012 and harmonize multiple open and as-yet unpublished data sources. The dataset creation is reproducible and transparent; R code and all original files used to create the dataset are provided in an appendix. This dataset will be useful for examining ecological change in lakes undergoing multiple stressors.
In recent decades, terrestrial dissolved organic matter (DOM) has increased in many northeastern North American and European lakes and is contributing to long-term browning. We used a long-term ...dataset (1988-2014) to study the consequences of browning-related decreased water transparency on dissolved oxygen dynamics in 2 small temperate lakes in Pennsylvania, USA, that differ in their dissolved organic carbon concentrations. The oligotrophic ("clearer") lake has low productivity and historically oxygenated deep waters. The mesotrophic-slightly dystrophic ("browner") lake also has relatively low productivity but historically anoxic deep waters. We examined whether browning coincided with changes in summer dissolved oxygen dynamics, with a focus on deep-water oxygen depletion. In the clearer lake, we found that minimum oxygen concentrations decreased by ∼4.4 mg L
−1
over the 27-year period, and these changes were strongly associated with both decreased water transparency and increased water column stability. We also found a shallowing of the maximum dissolved oxygen depth by ∼4.5 m and anoxic conditions established in more recent years. In the browner lake, the metrics we used did not detect any significant changes in dissolved oxygen, supporting the prediction that vertical temperature and oxygen patterns in clearer lakes may be more sensitive to increasing DOM than darker lakes. Anoxia is traditionally considered to be a consequence of anthropogenic nutrient loading and, more recently, a warming climate. We show that browning is another type of environmental change that may similarly result in anoxia in oligotrophic lakes.
Both preterm birth and increased screen time are known to be associated with an increase in risk of developmental and behavioral sequelae. The association between high screen time or a television or ...computer in the bedroom in early school age and adverse cognitive, executive function, language, and behavior outcomes of extremely preterm children (EPT) is not well understood.
To assess the association of high screen time with cognition, language, executive function, and behavior of EPT children aged 6 to 7 years; a second objective was to examine the association between high screen time and rates of structured physical activity and weight.
This cohort study was a secondary analysis from the Eunice Kennedy Shriver National Institute of Child Health and Human Development Surfactant Positive Airway Pressure and Pulse Oximetry Randomized Trial Neuroimaging and Neurodevelopmental Outcomes school-aged cohort and includes 414 EPT children born between February 1, 2005, and February 28, 2009, and evaluated in between 2012 and 2016 at ages 6 years 4 months to 7 years 2 months. The study was conducted from July 7, 2012, and August 15, 2016, and data were analyzed between December 10, 2018, and April 1, 2021.
Cohorts included children exposed to low (≤2 hours per day) vs high (>2 hours per day) amounts of screen time and by the presence (no vs yes) of a television/computer in the bedroom.
In addition to growth parameters, assessments included the Wechsler Intelligence Scale for Children-IV, the Behavior Rating Inventory of Executive Function, the Developmental Neuropsychological Assessment, the Conners 3rd Edition-Parent Short-Form, and the Social Communication Questionnaire.
Of the 414 children included in the analysis, 227 (55%) were boys; mean (SD) birth weight was 870.6 (191) g. A total of 238 children (57%) had high screen time and 266 (64%) had a television/computer in their bedroom. In multivariable linear regressions adjusted for center, male sex, gestational age, and social determinants of health, high screen time was independently associated with the following mean (SE) test score changes: lower full-scale IQ (-3.92 1.64; P = .02); an increase in association with deficits in executive functions, including metacognition (8.18 3.01; P = .007), global executive function (7.49 2.99; P = .01), inhibition (-0.79 0.38; P = .03), and Conners 3rd Edition-Parent Short-Form inattention (3.32 1.67; P = .047). A television/computer in the bedroom was associated with an increase in inhibition (-0.80 0.39; P = .04) and hyperactivity/impulsivity (3.50 1.75; P = .046) problems.
The findings of this study suggest that high screen time contributes to adverse cognitive, executive function, and behavior outcomes at ages 6 to 7 years in children born at less than 28 weeks. These findings support the need for clinicians to have heightened awareness of the risks for EPT children and discuss both the benefits and risks of screen time with families.
To identify rates of overweight (body mass index BMI ≥85th percentile) and obesity (BMI ≥95th percentile) at 6-7 years of age and associated risk factors among extremely preterm infants born at <28 ...weeks of gestation.
Anthropometrics, blood pressure, and active and sedentary activity levels were prospectively assessed. Three groups were compared, those with a BMI ≥85th percentile (overweight or obese for age, height, and sex) and ≥95th percentile (obese) vs <85th percentile. Multiple regression analyses estimated the relative risks of BMI ≥85th percentile and ≥95th percentile associated with perinatal and early childhood factors.
Of 388 children, 22% had a BMI of ≥85th percentile and 10% were obese. Children with obesity and overweight compared with normal weight children had higher body fat (subscapular skinfold and triceps skinfold >85th percentile), central fat (waist circumference >90th percentile), spent more time in sedentary activity (20.5 vs 18.2 vs 16.7 hours/week), and had either systolic and/or diastolic hypertension (24% vs 26% vs 14%), respectively. Postdischarge weight gain velocities from 36 weeks postmenstrual age to 18 months, and 18 months to 6-7 years were independently associated with a BMI of ≥85th percentile, whereas weight gain velocity from 18 months to 6-7 years was associated with obesity.
One in 5 former extremely preterm infants is overweight or obese and has central obesity at early school age. Postdischarge weight gain velocities were associated with overweight and obesity. These findings suggest the obesity epidemic is spreading to the most extremely preterm infants.
ClinicalTrials.gov: NCT00063063 and NCT0000.
The use of high-frequency sensors on profiling buoys to investigate physical, chemical, and biological processes in lakes is increasing rapidly. Profiling buoys with automated winches and sensors ...that collect high-frequency chlorophyll fluorescence (ChlF) profiles in 11 lakes in the Global Lake Ecological Observatory Network (GLEON) allowed the study of the vertical and temporal distribution of ChlF, including the formation of subsurface chlorophyll maxima (SSCM). The effectiveness of 3 methods for sampling phytoplankton distributions in lakes, including (1) manual profiles, (2) single-depth buoys, and (3) profiling buoys were assessed. High frequency ChlF surface data and profiles were compared to predictions from the Plankton Ecology Group (PEG) model. The depth-integrated ChlF dynamics measured by the profiling buoy data revealed a greater complexity that neither conventional sampling nor the generalized PEG model captured. Conventional sampling techniques would have missed the SSCM in 7 of 11 study lakes. Although surface-only ChlF data underestimated average water column ChlF, at times by nearly 2-fold in 4 of the lakes, overall there was a remarkable similarity between surface and mean water column data. Contrary to the PEG model's proposed negligible role for physical control of phytoplankton during the growing season, thermal structure and light availability were closely associated with ChlF seasonal depth distribution. Thus, an extension of the PEG model is proposed, with a new conceptual framework that explicitly includes physical metrics to better predict SSCM formation in lakes and highlight when profiling buoys are especially informative.
Phosphorus (P) is often a limiting nutrient in freshwater ecosystems, and understanding P dynamics in lakes is critical for eutrophication management. Pelagic P regeneration can support a large ...fraction of primary production in stratified freshwaters. Various techniques have been used to quantify pelagic P regeneration including (1) P mass balance supply- demand, (2) regression using total P as a predictor, and, more recently, (3) whole-lake metabolism calculated from highfrequency dissolved oxygen (DO) data. To our knowledge no study comparing these methods in multiple lakes has been performed. To compare these 3 approaches, we investigated 3 Global Lake Ecological Observatory Network (GLEON) lakes that differ in productivity: Acton, a Midwestern USA hypereutrophic reservoir; and 2 Northeastern USA glacial lakes, oligotrophic Giles and mesotrophic/dystrophic Lacawac. In Acton, we used all 3 methods, but for Giles and Lacawac we used only the total P regression and metabolism techniques. Our results show the best agreement among methods in the mesotrophic lake, whereas the metabolism approach underestimated regeneration in the oligotrophic lake and overestimated regeneration in the hypereutrophic reservoir compared with other methods. P regeneration rates for the hypereutrophic reservoir were the most sensitive to the metabolism-based input parameters. Our study illustrates a novel use of high-frequency DO data, which are commonly collected on many GLEON buoys, to understand lake nutrient dynamics.
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