Reconnaissance of Oxygenic Denitrifiers in Agriculturally Impacted Soils

Row crop production in the agricultural Midwest pollutes waterways with nitrate, and exacerbates climate change through increased emissions of nitrous oxide and methane. Oxygenic denitrification processes in agricultural soils mitigate nitrate and nitrous oxide pollution by short-circuiting the canonical pathway to avoid nitrous oxide formation. Furthermore, many oxygenic denitrifiers employ a nitric oxide dismutase (nod) to create molecular oxygen that is used by methane monooxygenase to oxidize methane in otherwise anoxic soils. The direct investigation of nod genes that could facilitate oxygenic denitrification processes in agricultural sites is limited, with no prior studies investigating nod genes at tile drainage sites. Thus, we performed a reconnaissance of nod genes at variably saturated surface sites, and within a variably to fully saturated soil core in Iowa to expand the known distribution of oxygenic denitrifiers. We identified new nod gene sequences from agricultural soil and freshwater sediments in addition to identifying nitric oxide reductase (qNor) related sequences. Surface and variably saturated core samples displayed a nod to 16S rRNA gene relative abundance of 0.004% to 0.1% and fully saturated core samples had relative nod gene abundance of 1.2%. The relative abundance of the phylum Methylomirabilota increased from 0.6% and 1% in the variably saturated core samples to 3.8% and 5.3% in the fully saturated core samples. The more than 10-fold increase in relative nod abundance and almost 9-fold increase in relative Methylomirabilota abundance in fully saturated soils suggests that potential oxygenic denitrifiers play a greater nitrogen cycling role under these conditions. IMPORTANCE The direct investigation of nod genes in agricultural sites is limited, with no prior studies investigating nod genes at tile drains. An improved understanding of nod gene diversity and distribution is significant to the field of bioremediation and ecosystem services. The expansion of the nod gene database will advance oxygenic denitrification as a potential strategy for sustainable nitrate and nitrous oxide mitigation, specifically for agricultural sites.

Glycation and Serum Albumin Infiltration Contribute to the Structural Degeneration of Bioprosthetic Heart Valves

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Two novel and interacting mechanisms contributing to BHV SVD are reported: glycation and serum albumin infiltration.

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Glycation product formation and serum albumin deposition were observed in 45 clinical BHV explanted due to SVD as well as BHV tissue subcutaneously implanted in rats.

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In vitro exposure to glycation and serum albumin elicited collagen network misalignment similar to that seen in clinical and rat explant BHV tissue.

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Glycation was sufficient to impair BHV hydrodynamic function in ISO-5840-compliant pulse duplication testing and concomitant serum albumin infiltration exacerbated these effects.

Valvular heart diseases are associated with significant cardiovascular morbidity and mortality, and often require surgical and/or percutaneous repair or replacement. Valve replacement is limited to mechanical and biological prostheses, the latter of which circumvent the need for lifelong anticoagulation but are subject to structural valve degeneration (SVD) and failure. Although calcification is heavily studied, noncalcific SVD, which represent roughly 30% of BHV failures, is relatively underinvestigated. This original work establishes 2 novel and interacting mechanisms—glycation and serum albumin incorporation—that occur in clinical valves and are sufficient to induce hallmarks of structural degeneration as well as functional deterioration.

Age-related changes in the physical properties, cross-linking, and glycation of collagen from mouse tail tendon

Collagen is a structural protein whose internal cross-linking critically determines the properties and functions of connective tissue. Knowing how the cross-linking of collagen changes with age is key to understanding why the mechanical properties of tissues change over a lifetime. The current scientific consensus is that collagen cross-linking increases with age and that this increase leads to tendon stiffening. Here, we show that this view should be reconsidered. Using MS-based analyses, we demonstrated that during aging of healthy C57BL/6 mice, the overall levels of collagen cross-linking in tail tendon decreased with age. However, the levels of lysine glycation in collagen, which is not considered a cross-link, increased dramatically with age. We found that in 16-week-old diabetic db/db mice, glycation reaches levels similar to those observed in 98-week-old C57BL/6 mice, while the other cross-links typical of tendon collagen either decreased or remained the same as those observed in 20-week-old WT mice. These results, combined with findings from mechanical testing of tendons from these mice, indicate that overall collagen cross-linking in mouse tendon decreases with age. Our findings also reveal that lysine glycation appears to be an important factor that contributes to tendon stiffening with age and in diabetes.

Calibration of BAS-TR image plate response to high energy (3-300 MeV) carbon ions

The paper presents the calibration of Fuji BAS-TR image plate (IP) response to high energy carbon ions of different charge states by employing an intense laser-driven ion source, which allowed access to carbon energies up to 270 MeV. The calibration method consists of employing a Thomson parabola spectrometer to separate and spectrally resolve different ion species, and a slotted CR-39 solid state detector overlayed onto an image plate for an absolute calibration of the IP signal. An empirical response function was obtained which can be reasonably extrapolated to higher ion energies. The experimental data also show that the IP response is independent of ion charge states.

Bright subcycle extreme ultraviolet bursts from a single dense relativistic electron sheet

Double-foil targets separated by a low density plasma and irradiated by a petawatt-class laser are shown to be a copious source of coherent broadband radiation. Simulations show that a dense sheet of relativistic electrons is formed during the interaction of the laser with the tenuous plasma between the two foils. The coherent motion of the electron sheet as it transits the second foil results in strong broadband emission in the extreme ultraviolet, consistent with our experimental observations.

Modified Thomson spectrometer design for high energy, multi-species ion sources

A modification to the standard Thomson parabola spectrometer is discussed, which is designed to measure high energy (tens of MeV/nucleon), broad bandwidth spectra of multi-species ions accelerated by intense laser plasma interactions. It is proposed to implement a pair of extended, trapezoidal shaped electric plates, which will not only resolve ion traces at high energies, but will also retain the lower energy part of the spectrum. While a longer (along the axis of the undeflected ion beam direction) electric plate design provides effective charge state separation at the high energy end of the spectrum, the proposed new trapezoidal shape will enable the low energy ions to reach the detector, which would have been clipped or blocked by simply extending the rectangular plates to enhance the electrostatic deflection.

Performance and bunk attendance of cattle fed steam-rolled or ground corn supplemented with laidlomycin and chlortetracycline or monensin and tylosin

British cross steer calves (n = 240; 332 ± 23 kg) in 16 pens were fed ground (G) or steam-rolled (SR) corn-based finishing diets medicated with 12 mg kg-1 laidlomycin propionate and 42.2 mg kg-1 chlortetracycline hydrochloride (LC) or with 30.4 mg kg-1 monensin sodium and 10.5 mg kg-1 tylosin phosphate (MT) in a 2 × 2 factorial experiment. Individual bunk attendance was monitored using radio frequency identification in one pen per diet. Finishing diets were fed for 125 d following a 27-d adaptation from 65 to 91% concentrate diet. In the first 56 d and overall, daily dry matter intake (DMI) was greater (P < 0.05) with LC than with MT (8.8 vs. 8.3 kg), but did not differ (P = 0.97) between G and SR diets. There was a trend (P = 0.11) towards greater ADG for cattle fed LC than those fed MT (1.54 vs. 1.47 kg d-1), but gain:feed was similar (0.169; P = 0.80) between antibiotic supplements. Processing method did not (P = 0.29) affect rate of gain, but SR tended (P = 0.06) to improve gain:feed compared with G (0.171 vs. 0.165). Steers fed LC spent more (P < 0.001) time at the bunk than those fed MT (125 vs. 120 min d-1). On G diets, cattle fed LC made fewer daily visits (9.3 vs. 9.5 visits d-1; P = 0.03), but spent more time at the bunk (135.9 vs. 124.0 min d-1; P < 0.001) resulting in greater duration per meal (15.4 vs. 13.7 min meal-1; P < 0.001). These cattle also had the greatest deviation in daily duration at the bunk (37.3 vs. 33.7 min; P < 0.001). The prevalence of liver abscesses was 13.2% with LC and 6.5% with MT (P = 0.09). However, the prevalence of severely abscessed livers (2.9%) was unaffected (P = 0.45) by treatment. The prevalence of foot rot was greater (P = 0.02) for cattle fed MT (7.5%) than for cattle fed LC (0.8%). Compared with feeding MT, feeding LC may enhance ADG, possibly due to greater DMI. Key words: Beef, chlortetracycline, corn processing, laidlomycin, monensin, tylosin

Effect of sub-therapeutic antibiotics and auction exposure on health, performance, and feeding behavior of weaned calves

Calves sourced directly from a ranch were heavier initially (273 vs. 258; P = 0.01) than calves from the same ranch but processed through an auction barn. For calves fed 6 g head-1 d-1 chlortetracycline from days 5 to 9, feeding an additional 350 mg head-1 d-1 of chlortetracycline and sulfamethazine from days 1 to 28 improved gain/feed (P = 0 .03), but only for the first 28 d of the 84-d trial. Frequency of bunk visits were altered by calf source and antibiotic treatment. Key words: Antibiotics, auction, calves, feedlot receiving programs

Effect of feed delivery fluctuations and feeding time on ruminal acidosis, growth performance, and feeding behavior of feedlot cattle1,2

Research was conducted to determine whether fluctuations in the amount of feed delivered and timing of feeding affect ruminal pH and growth of feedlot cattle. In Exp. 1, the effects of constant (C) vs. fluctuating (F) daily feed delivery on ruminal pH were assessed in a crossover experiment (two 28-d periods) involving six mature, ruminally cannulated steers. The diet consisted of 86.8% barley grain, 4.9% supplement, and 8.3% barley silage (DM basis) and was offered ad libitum for 2 wk to estimate DMI by individual steers. Steers in group C were offered a constant amount of feed daily equal to their predetermined DMI, whereas steers in group F were offered 10% more or less than their predetermined DMI on a rotating 3-d schedule. Ruminal pH of each steer was measured continuously via an indwelling electrode placed in the rumen during the last 6 d of each period. Mean pH tended to be lower (0.10 units) for F than C (5.63 vs. 5.73; P = 0.15), and ruminal pH of steers in group F tended to remain below 5.8 (P = 0.03) or 5.5 (P = 0.14) for greater proportions of the day than steers in group C. Inconsistent delivery of feed lowered ruminal pH, suggesting increased risk of subclinical acidosis. In Exp. 2, a 2 x 2 factorial was used to study the effects of pattern (C vs. F) and feeding time (morning [0900] vs. evening [2100]) on the feeding behavior and performance of 234 (310 +/- 23 kg) Charolais x Hereford beef steers during backgrounding and finishing phases over 209 d. One pen per treatment was equipped with a radio frequency identification (GrowSafe Systems Ltd., Airdrie, Canada) system that monitored bunk attendance by each steer throughout the trial. Pattern of feed delivery did not affect (P = 0.16) DMI (7.36 kg/d), ADG (1.23 kg/d), G:F (0.17), or time spent at the bunk (141 min/d), nor were pattern of feed delivery x time of feeding interactions observed (P = 0.18). Late feeding increased (P < 0.05) daily DMI (7.48 vs. 7.26 kg), ADG (1.28 vs. 1.00 kg/d), and G:F (0.21 vs. 0.15). These studies indicate that the risk of subclinical acidosis was increased with fluctuating delivery of feed, but the greater risk of acidosis did not impair growth performance by feedlot cattle. Consequently, daily intake fluctuations of 10% DMI or less that do not alter overall intake by feedlot cattle are unlikely to have any negative consequences on growth performance.

Histomorphometric age assessment of the Boxgrove 1 tibial diaphysis

Histomorphometric analysis of a medial midshaft chip from the Middle Pleistocene (ca. 500 ka BP) hominid tibia from Boxgrove, U.K. provides a modal age-at-death estimate at the end of the fourth decade of life. This makes Boxgrove 1 one of the older known and systematically aged Middle Pleistocene hominid specimens, and it reinforces the pattern of an underrepresentation of older adults observed in Middle and Late Pleistocene archaic Homo samples.