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This is a summary of major ion concentrations for stream water samples collected at the outflow of the Saddle stream, near Saddle grid point 007 on Niwot Ridge. 

This is a summary of major ion concentrations for stream water samples collected at the outflow of the Saddle stream, near Saddle grid point 007 on Niwot Ridge. 

As part of its long-term climate data core collection, the Niwot Ridge LTER has collected daily precipitation at the Saddle site since 1981. The Saddle station is located at 3525 m.a.s.l. and is an important point location to capture local, ambient meteorological conditions for many biological and environmental datasets collected nearby. The location of the Saddle station has also presented challenges to its operation. Freezing temperatures, snow deposition from strong winds following storms, and exposure to lightning are some elements that have disrupted instrument functionality, affected data quality, and made access for research staff difficult over time, especially in winter months. Here we present a quality-controlled, gap-filled, daily precipitation time series corrected for blowing snow overcatch at the Saddle station. Methods follow those used to gap-fill long-term daily precipitation at the Niwot Ridge LTER D1 and C1 stations so there is consistency among core collection daily precipitation datasets. Metadata for this data package centralizes the most complete station history for Saddle precipitation and includes notes to data users on aspects and limitations of the dataset to consider when using these data in scientific analyses. Because of unresolved data quality concerns with winter precipitation the first several years of the record, gap-filled data for winter months (October–May) 1981-10-01 through 1987-05-30 are removed. 

Precipitation data have been collected at the C1 climate station (3022 m asl) almost continuously from 1952 to the present. C1 is on locally level terrain on the southeastern flank of Niwot Ridge, 9.7 km east of the Continental Divide. Surrounding vegetation is closed-canopy subalpine conifer forest. Through 1964, precipitation was recorded using an unshielded U.S. Weather Bureau standard totalizing gauge, with observations manually recorded on an approximately weekly basis. The gauge was located in an open area with sparse tree cover adjacent to the forest proper. Starting in late 1961, daily precipitation has been recorded using a Belfort Universal weighing-bucket gauge with chart recorder in an 8-m diameter clearing in the forest; the forest provides natural shielding for the gauge. The two records were assessed for an impact of this station change on record homogeneity and merged (see Methods). Missing daily data were infilled and multiday records were parsed to dailies (see Methods). 

Precipitation data have been collected at the D1 climate station (3739 m asl) almost continuously from 1952 to the present. D1 is on a narrow, exposed ridge on the westernmost part of Niwot Ridge, 2.6 km east of and ca. 200 m lower in elevation than the Continental Divide. Surrounding vegetation is low-stature alpine tundra. Through 1969, precipitation was recorded using an unshielded U.S. Weather Bureau standard totalizing gauge, with observations manually recorded on an approximately weekly basis. Starting in 1965, daily precipitation has been recorded using a Belford weighing-bucket gauge with chart recorder and with an Alter-type shield encircled by a Wyoming-snow fence. Overlap in the two records was used to adjust the totalizing gauge record so that it could be merged with the weighing-bucket gauge record (see Methods). Missing daily data were infilled and multiday records were parsed to dailies (see Methods). 

Daily minimum and maximum surface air temperature data have been collected at the C1 climate station (3022 m asl) almost continuously from 1952 to the present. C1 is on locally level terrain on the southeastern flank of Niwot Ridge, 9.7 km east of the Continental Divide. Surrounding vegetation is generally closed-canopy subalpine conifer forest. Temperature minima and maxima were measured with a chart-recording hygrothermograph housed in a Stevenson screen located in an open, sparsely treed area adjacent to the forest proper. Hygrothermograph records were calibrated at the time of chart changes against liquid-in-glass thermometers. Processing included quality checks and infilling of missing daily data (see Methods). 

Daily minimum and maximum surface air temperature data have been collected at the D1 climate station (3739 m asl) almost continuously from 1952 to the present. D1 is on a narrow, exposed ridge on the westernmost part of Niwot Ridge, 2.6 km east of and ca. 200 m lower in elevation than the Continental Divide. Surrounding vegetation is low-stature alpine tundra. Temperature minima and maxima were measured with a chart-recording hygrothermograph housed in a Stevenson screen. Hygrothermograph records were calibrated at the time of chart changes against liquid-in-glass thermometers. Processing included quality checks and infilling of missing daily data (see Methods). 

Bacteriophage T4 gene 32 protein (gp32) is a single-stranded DNA (ssDNA) binding protein essential for DNA replication. gp32 forms stable protein filaments on ssDNA through cooperative interactions between its core and N-terminal domain. gp32′s C-terminal domain (CTD) is believed to primarily help coordinate DNA replication via direct interactions with constituents of the replisome. However, the exact mechanisms of these interactions are not known, and it is unclear how tightly-bound gp32 filaments are readily displaced from ssDNA as required for genomic processing. Here, we utilized truncated gp32 variants to demonstrate a key role of the CTD in regulating gp32 dissociation. Using optical tweezers, we probed the binding and dissociation dynamics of CTD-truncated gp32, *I, to an 8.1 knt ssDNA molecule and compared these measurements with those for full-length gp32. The *I-ssDNA helical filament becomes progressively unwound with increased protein concentration but remains significantly more stable than that of full-length, wild-type gp32. Protein oversaturation, concomitant with filament unwinding, facilitates rapid dissociation of full-length gp32 from across the entire ssDNA segment. In contrast, *I primarily unbinds slowly from only the ends of the cooperative clusters, regardless of the protein density and degree of DNA unwinding. Our results suggest that the CTD may constrain the relative twist angle of proteins within the ssDNA filament such that upon critical unwinding the cooperative interprotein interactions largely vanish, facilitating prompt removal of gp32. We propose a model of CTD-mediated gp32 displacement via internal restructuring of its filament, providing a mechanism for rapid ssDNA clearing during genomic processing. 

ABSTRACT Subsurface sediment transport in tile‐drained landscapes occurs through macropores; however, little is known regarding how heterogeneous preferential flows influence fluxes. We performed laboratory rainfall simulations on 10 intact core lysimeters from a tile‐drained field in Indiana, USA to study the impacts of surface and subsurface erosion on sediment leachate in heterogeneous preferential flow paths. Seven rainfall simulations were conducted to assess the impact of rainfall intensity on the leachate of surface eroded sediments (three events), and the impact of antecedent conditions on subsurface eroded sediments (four events). Cumulative sediment yield, linear mixed effects modelling, and hysteresis analyses were performed for all events. Results were presented in a series of four case studies. Results showed that surface sediment leachate concentration and yield were tightly linked to the filtration capacity of lysimeters, with more than 2/3rd of sediment originating from a single lysimeter, despite similar flow leachate volumes from each. Rainfall intensity significantly impacted the transport of surface eroded sediment at the highest intensity. Subsurface sediment erosion from undisturbed macropores was low compared to surface soils, but we found contrasting controls on sediment concentrations at low and high antecedent moistures that were equally important to sediment leachate yields. Disturbed macropores produced comparable sediment yields to surface erosion and behaved similarly to soil pipes in terms of erosion mechanics. Hysteresis results generally highlighted contrasting results for surface and subsurface sources but suggest that the prominence of slow flow, low‐concentration leachate sources can alter the interpretation of results in field‐scale applications. Our findings underscore an array of processes and pathways for sediment transport in the shallow vadose zone, and results will be useful for evaluating new model formulations.