Promotion of the cycling of diet-enhancing nutrients by african grazers

Experiments in Serengeti National Park, Tanzania, provide direct evidence that large, free-ranging mammalian grazers accelerate nutrient cycling in a natural ecosystem in a way that enhances their own carrying capacity. Both nitrogen and sodium were at considerably higher plant-available levels in soils of highly grazed sites than in soils of nearby areas where animal density is sparse. Fencing that uncoupled grazers and soils indicated that the animals promote nitrogen availability on soils of inherently similar fertility and select sites of higher sodium availability as well as enhancing that availability.     

The Importance of Having Zinc During In Vitro Maturation of Cattle Cumulus–Oocyte Complex: Role of Cumulus Cells

The aim of this study was to investigate the influence of zinc (Zn) on the health of cumulus–oocyte complex (COC) during in vitro maturation (IVM). Experiments were designed to evaluate the effect of Zn added to IVM medium on: DNA integrity, apoptosis, cumulus expansion and superoxide dismutase (SOD) activity of cumulus cells (CC). Also, role of CC on Zn transport during IVM was evaluated on oocyte developmental capacity. DNA damage and early apoptosis were higher in CC matured with 0 μg/ml Zn compared with 0.7, 1.1 and 1.5 μg/ml Zn (p < 0.05). Cumulus expansion did not show differences in COC matured with or without Zn supplementation (p > 0.05). Superoxide dismutase activity was higher in COC matured with 1.5 μg/ml Zn than with 0 μg/ml Zn (p < 0.05). Cleavage and blastocyst rates were recorded after IVM in three maturation systems: intact COCs, denuded oocytes with cumulus cells monolayer (DO + CC) and denuded oocytes (DO). Cleavage rates were similar when COC, DO + CC or DO were matured with 1.5 μg/ml Zn compared with control group (p > 0.05). Blastocyst rates were significantly higher in COC than in DO + CC and DO with the addition of 1.5 μg/ml Zn during IVM (p < 0.01). Blastocyst quality was enhanced in COC and DO + CC compared with DO when Zn was added to IVM medium (p < 0.001). The results of this study indicate that Zn supplementation to IVM medium (i) decreased DNA damage and apoptosis in CC; (ii) increased SOD activity in CC; (iii) did not modify cumulus expansion and cleavage rates after in vitro fertilization; (iv) improved subsequent embryo development up to blastocyst stage; and (v) enhanced blastocyst quality when CC were present either in intact COC or in coculture during IVM.     

Digital Preservation and Access of Agricultural Materials

Historians and researchers depend on institutions to preserve the records and documents of the past. As the land-grant institution, Colorado State University (CSU) joined in a national, multi-phase National-Endowment-for-the-Humanities-supported grant project to identify and preserve significant materials documenting the history of the agricultural and rural life of the state. This article outlines the history of the grant project, details the challenges and successes of the digitization phase at Colorado State University Libraries, provides usage statistics, and offers a basis for emulation by other institutions by providing an example of a successful preservation and digitization project at a large public university.     

Large-scale molecular dynamics simulations of dislocation intersection in copper

The results of massively parallel three-dimensional molecular dynamics simulations of the perpendicular intersection of extended dislocations in copper are reported. The intersection process, which involves three of the four possible 111 glide planes in the face-centered cubic lattice, begins with junction formation, followed by unzipping, partial dislocation bowing, cutting, and, finally, unit jog formation. The investigation provides insights into this complex atomistic process, which is currently not accessible to experimental investigation.     

Constructing a nitrogen fertilizer recommendation system using a dynamic model: what do farmers want?

Abstract. An effective fertilizer recommendation system requires information on seasonal, soil-related and cultural variations in soil mineral nitrogen (N) and nutrient requirements of the crop. This can be provided by dynamic N turnover models, such as listed by Plentinger & Penning De Vries (1996). In this paper, we describe a survey of farmer opinion designed to ascertain what farmers want from such a decision support system. Over 100 farmers were surveyed. Surveyed farmers requested that default values be available for all model inputs. Inputs should be entered both by windows-based menu (for clarity) and tabular format (for speed), have user-selected units, and be fully supported by context-sensitive help. The system should have a hierarchical structure allowing access to fixed parameters, and be compatible with commonly used farm recording packages. Recommendations should be provided both for the field (single and optional application rates), and in tabular format across the whole farm. Simulations should be easily rerun using more recent crop and weather data. Turnover processes underlying recommendations should be illustrated by flow diagrams of flux between pools, pie charts of fertilizer fate, bar charts of movement down the soil profile and graphical plots of changes in N status against time.     

Assessment of organoleptic postmortem inspection techniques for bovine offal

Objective To evaluate organoleptic postmortem inspection techniques for bovine livers and kidneys.
Study design At Australian export abattoirs, bovine liver and kidneys are assessed and graded by qualified meat inspectors during normal operations. Over a 12-month period at a large abattoir in eastern Australia during 1997 and 1998, a sample of these organs was reassessed independently using a range of pathological and microbiological methods. Agreement between routine inspection and independent assessment was evaluated using methods of inter-rater agreement.
Results A total of 944 livers and 1374 kidneys were included in the study. All of these organs had been classified during routine inspection. The authors examined 363 livers and 329 kidneys both grossly and histologically, including 36 livers and 14 kidneys that were also subjected to microbiological examination. All other organs were only examined grossly. There was only a moderate level of agreement between the routine and independent assessment methods. For livers, the percentage agreement was 80.2%, McNemar's test of symmetry 55.2 (3 degrees of freedom, P < 0.001) and kappa 0.63. For kidneys, the percentage agreement was 67.8%, McNemar's test of symmetry 9.9 (1df, P = 0.002) and kappa 0.35.
Conclusions The results reinforce concerns from a number of authors about organoleptic postmortem inspection. Risk assessment methodologies offer the opportunity to modify inspection techniques in a manner that is most relevant to current public health concerns.     

Atmospheric pressure ionization LC-MS-MS determination of urushiol congeners

This paper describes atmospheric pressure ionization (API) LC-MS-MS determination of urushiols, 3-n-alkenyl- and -alkyl-substituted catechols responsible for poison oak dermatitis. Urushiol was isolated from Western poison oak according to the method of Elsohly et al. (1) (J. Nat. Prod. 1982, 45, 532-538)-the purified preparation contained C(17)- and C(15)-substituted urushiols with zero, one, two, and three double bonds as determined from GC-MS analysis of trimethylsilyl derivatives. Urushiol mixtures were separated on a C(18) reversed phase HPLC column with a methanol-water gradient with urushiols eluting in 100% methanol. Atmospheric pressure chemical ionization (APCI) produced primarily [M - H](-) and MH(+) molecule ions. Electrospray ionization (ESI) yielded [M - H](-) and adduct ions including [M + Cl](-). Daughter ions of [M - H](-) included quinoid radical anions ([M - H - H(2)](-) and m/z 122(-)) and a benzofuran phenate (m/z 135(-)). A suite of hydrocarbon fragments were produced by collision-induced dissociation of MH(+) directly or via an intermediate [MH - H(2)O](+) daughter ion. Six urushiol congeners, one not previously reported in poison oak, were determined by negative ion API-LC-MS-MS with detection limits of approximately 8 pg/microL (ESI) and approximately 800 pg/microL (APCI). API-LC-MS-MS was used to determine urushiol in surface wipes, air samples, and plant materials.