Extensive, large-scale pervasive cementation in the form of cement bodies within fluvial strata has rarely been documented although fluvial strata commonly act as important hydrocarbon reservoirs, as ...well as groundwater aquifers. Here, we present outcrop, petrographic and geochemical data for pervasive ferroan dolomite cement bodies up to 250 m in size from Upper Cretaceous Desert Member and Castlegate Sandstone fluvial strata exposed in the Book Cliffs in Utah. These cement bodies are present with coastal plain fluvial strata within both the Desert and Castlegate lowstand sandstones and are most abundant in the thin, distal fluvial strata. Cement bodies are almost entirely absent in updip, thicker, fluvial strata. Petrographic observations suggest a predominantly early diagenetic timing to the mildly ferroan dolomite, with a component of later burial origin. δ
13C values for the cement (+4.8 to −5.7‰ V-PDB) suggest a marine-derived source for the earliest phase with a burial organic matter source for later cement. δ
18O data (−6.3 to −11.8‰ V-PDB) suggest precipitation from freshwater dominated fluids. It is proposed here that dolomite was derived from leaching of detrital dolomite under lowstand coals and cementation took place in coastal aquifers experiencing mixed meteoric-marine fluids as a result of base-level fluctuations. This data presented here shows that large cement bodies can be an important component within fluvial sandstones with a potentially significant impact upon both reservoir quality and fluid flow within reservoirs, especially at the marine-non-marine interface.
► Upper Cretaceous fluvial strata exposed in the Book Cliffs, Utah. Studied here. ► Dolomite cement bodies up to 250 m in size abundant in distal fluvial strata. ► Petrographic observations indicate an early diagenetic origin. ► Mixed meteoric-marine coastal aquifer resulted from base-level shifts. ► Carbonate cementation potentially has significant impact upon reservoir quality.
Distributions of foliar nutrients across forest canopies can give insight into their plant functional diversity and improve our understanding of biogeochemical cycling. We used airborne remote ...sensing and partial least squares regression to quantify canopy foliar nitrogen (foliar N) across ~164 km² of wet lowland tropical forest in the Osa Peninsula, Costa Rica. We determined the relative influence of climate and topography on the observed patterns of foliar N using a gradient boosting model technique. At a local scale, where climate and substrate were constant, we explored the influence of slope position on foliar N by quantifying foliar N on remnant terraces, their adjacent slopes, and knife-edged ridges. In addition, we climbed and sampled 540 trees and analyzed foliar N in order to quantify the role of species identity (phylogeny) and environmental factors in predicting foliar N. Observed foliar N heterogeneity reflected environmental factors working at multiple spatial scales. Across the larger landscape, elevation and precipitation had the highest relative influence on predicting foliar N (30% and 24%), followed by soils (15%), site exposure (9%), compound topographic index (8%), substrate (6%), and landscape dissection (6%). Phylogeny explained ~75% of the variation in the field collected foliar N data, suggesting that phylogeny largely underpins the response to the environmental factors. Taken together, these data suggest that a large fraction of the variance in foliar N across the landscape is proximately driven by species composition, though ultimately this is likely a response to abiotic factors such as climate and topography. Future work should focus on the mechanisms and feedbacks involved, and how shifts in climate may translate to changes in forest function.
PURPOSE. Mitochondrial function and the presence of somatic mitochondrial DNA (mtDNA) defects were investigated in extraocular muscles (EOMs) collected from individuals covering a wide age range, to ...document the changes seen with normal aging. METHODS. Cytochrome c oxidase (COX) and succinate dehydrogenase (SDH) histochemistry was performed on 46 EOM samples to determine the level of COX deficiency in serial cryostat muscle sections (mean age, 42.6 years; range, 3.0-96.0 years). Competitive three-primer and real-time PCR were performed on single-fiber lysates to detect and quantify mtDNA deletions. Whole-genome mitochondrial sequencing was also performed to evaluate the contribution of mtDNA point mutations to the overall mutational load. RESULTS. COX-negative fibers were seen in EOMs beginning in the third decade of life, and there was a significant age-related increase: <30 years, 0.05% (n = 17); 30 to 60 years, 1.94% (n = 13); and >60 years, 3.34% (n = 16, P = 0.0001). Higher levels of COX deficiency were also present in EOM than in skeletal muscle in all three age groups (P < 0.0001). Most of the COX-negative fibers harbored high levels (>70%) of mtDNA deletions (206/284, 72.54%) and the mean deletion level was 66.64% (SD 36.45%). The mutational yield from whole mitochondrial genome sequencing was relatively low (1/19, 5.3%), with only a single mtDNA point mutation identified among COX-negative fibers with low deletion levels < or =70%. CONCLUSIONS. The results show an exponential increase in COX deficiency in EOMs beginning in early adulthood, which suggests an accelerated aging process compared with other postmitotic tissues.
Isolated Complex I deficiency is the most common paediatric mitochondrial disease presentation, associated with poor prognosis and high mortality. Complex I comprises 44 structural subunits with at ...least 10 ancillary proteins; mutations in 29 of these have so far been associated with mitochondrial disease but there are limited genotype-phenotype correlations to guide clinicians to the correct genetic diagnosis.
Patients were analysed by whole-exome sequencing, targeted capture or candidate gene sequencing. Clinical phenotyping of affected individuals was performed.
We identified a cohort of 10 patients from 8 families (7 families are of unrelated Irish ancestry) all of whom have short stature (<9th centile) and similar facial features including a prominent forehead, smooth philtrum and deep-set eyes associated with a recurrent homozygous c.64T>C, p.Trp22Arg NDUFB3 variant. Two sibs presented with primary short stature without obvious metabolic dysfunction. Analysis of skeletal muscle from three patients confirmed a defect in Complex I assembly.
Our report highlights that the long-term prognosis related to the p.Trp22Arg NDUFB3 mutation can be good, even for some patients presenting in acute metabolic crisis with evidence of an isolated Complex I deficiency in muscle. Recognition of the distinctive facial features-particularly when associated with markers of mitochondrial dysfunction and/or Irish ancestry-should suggest screening for the p.Trp22Arg NDUFB3 mutation to establish a genetic diagnosis, circumventing the requirement of muscle biopsy to direct genetic investigations.
Tropical rainforests are reservoirs of terrestrial carbon and biodiversity. Large and often emergent trees store disproportionately large amounts of aboveground carbon and greatly influence the ...structure and functioning of tropical rainforests. Despite their importance, controls on the abundance and distribution of emergent trees are largely unknown across tropical landscapes. Conventional field approaches are limited in their ability to characterize patterns in emergent trees across vast landscapes with varying environmental conditions and floristic composition. Here, we used a high‐resolution light detection and ranging (LiDAR) sensor aboard the Carnegie Airborne Observatory Airborne Taxonomic Mapping System (CAO‐AToMS) to examine the abundance and distribution of tall emergent tree crowns (ETC) relative to surrounding tree crowns (STC) across the Osa Peninsula, a geologically and topographically diverse region of Costa Rica. The abundance of ETC was clearly influenced by fine‐scale topographic variation, with distribution patterns that held across a variety of geologic substrates. Specifically, the density of ETC was much greater on lower slopes and in valleys, compared to upper slopes and ridges. Furthermore, using the CAO high‐fidelity imaging spectrometer, ETC had a different spectral signature than that of STC. Most notably, ETC had lower remotely sensed foliar nitrogen than STC, which was verified with an independent field survey of canopy leaf chemistry. The underlying mechanisms to explain the topographic‐dependence of ETCs and linkages to canopy N are unknown, and remain an important area of research.
Background
The Frontal Sinus Masterclass (FSMC) is an effective method for teaching frontal sinus anatomy. A third party developed new software using the same 3-dimensional building block concept. ...The authors sought to determine whether the use of the software for the educational module yielded similar results to the original FSMC, which used wooden blocks.
Methods
The study was performed at a sinus course for residents. A precourse test assessed the ability to decipher frontal sinus anatomy prior to the course. Computed tomography (CT) scans of the sinuses were evaluated in triplanar view, and participants attempted to reconstruct the anatomy using the new software. Subsequently, the course instructor explained the anatomy and showed a short corresponding surgical video of the frontal sinusotomy. Cases progressed in anatomical difficulty and inflammatory load. A postcourse test determined knowledge after the course.
Results
In sum, 50 residents completed the pre- and postcourse tests. Overall scores increased from 60.5% to 65.2% (P = .004). Subanalysis also demonstrated improved ability to locate the frontal drainage pathway from 32.5% to 46% (P = .011) and label the frontal recess cell structures from 64% to 67.6% (P = .045).
Conclusion
There is minimal literature on proven methods for teaching frontal sinus anatomy. Objectively, participants of the modified FSMC simulation training using new software improved their ability to recognize cells of the frontal recess on CT scans. They especially exhibited better localization of the frontal sinus drainage pathway. Subjectively, participants reported benefit from the course and felt they would be better surgeons.
PURPOSE. Chronic progressive external ophthalmoplegia (CPEO) is a prominent, and often the only, presentation among patients with mitochondrial diseases. The mechanisms underlying the preferential ...involvement of extraocular muscles (EOMs) in CPEO were explored in a comprehensive histologic and molecular genetic study, to define the extent of mitochondrial dysfunction in EOMs compared with that in skeletal muscle from the same patient. METHODS. A well-characterized cohort of 13 CPEO patients harboring a variety of primary and secondary mitochondrial (mt)DNA defects was studied. Mitochondrial enzyme function was determined in EOM and quadriceps muscle sections with cytochrome c oxidase (COX)/succinate dehydrogenase (SDH) histochemistry, and the mutation load in single muscle fibers was quantified by real-time PCR and PCR-RFLP assays. RESULTS. CPEO patients with mtDNA deletions had more COX-deficient fibers in EOM (41.6%) than in skeletal muscle (13.7%, P > 0.0001), and single-fiber analysis revealed a lower mutational threshold for COX deficiency in EOM. Patients with mtDNA point mutations had a less severe ocular phenotype, and there was no significant difference in the absolute level of COX deficiency or mutational threshold between these two muscle groups. CONCLUSIONS. The more pronounced mitochondrial biochemical defect and lower mutational threshold in EOM compared with skeletal muscle fibers provide an explanation of the selective muscle involvement in CPEO. The data also suggest that tissue-specific mechanisms are involved in the clonal expansion and expression of secondary mtDNA deletions in CPEO patients with nuclear genetic defects.
Integrated carbon budgets of terrestrial and aquatic ecosystems indicate that particulate organic carbon (POC) plays an important role in the transport, storage, and turnover of carbon during its ...transit from land to sea. However, little is known about the rates at which POC in suspension is metabolized during downstream transport. We address this deficiency by improving existing respiration methods and models to assess the biological lability of POC suspended in a headwater stream. Our method involves concentration of stream particles by tangential flow filtration, extended incubations (35‐40 d) using conditions to ensure particle suspension and prevent particle aggregation, correction for the simultaneous respiration of dissolved organic carbon, and conversion from oxygen measurements into carbon with a respiratory oxidation ratio (OR) of 1.30 O2:C. We include analysis of the choice of OR. The POC turnover times estimated with the improved methods in this study are ~10 days. These respiration rates are among the highest reported for either suspended or benthic POC in streams and suggest that suspended POC is mineralized closer to its point of origin than was previously assumed. During incubation, keeping POC in suspension can increase respiration rates as much as 2‐fold compared with allowing particles to settle and physical inhibition of POC aggregation can increase rates by 1.2‐fold compared with allowing POC to aggregate. Methods that explicitly incorporate suspension and discourage aggregation of POC and longer incubation times during respiration measurements will generate data that improve our understanding of the dynamic role of POC in aquatic ecosystems.
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