Sampling for Explosives-Residues at Fort Greely,Alaska

Fort Greely, Alaska has an extensive complex of weapon training and testing areas located on lands withdrawn from the public domain under the Military Lands Withdrawal Act (PL106-65). The Army has pledged to implement a program to identify possible munitions contamination. Because of the large size (344,165,000 m²) of the high hazard impact areas, characterization of these constituents will be difficult. We used an authoritative sampling design to find locations most likely to contain explosives-residues on three impact areas. We focused our sampling on surface soils and collected multi-increment and discrete samples at locations of known firing events and from areas on the range that had craters, pieces of munitions, targets, or a designation as a firing point. In the two impact areas used primarily by the Army, RDX was the most frequently detected explosive. In the impact area that was also used by the Air Force, TNT was the most frequently detected explosive. Where detected, the explosives concentrations generally were low (<0.05 mg/kg) except in soils near low-order detonations, where the explosive-filler was in contact with the soil surface. These low-order detonations potentially can serve as localized sources for groundwater contamination if positioned in recharge areas.     

Use of Metabolic Inhibitors to Estimate Protozooplankton Grazing and Bacterial Production in a Monomictic Eutrophic Lake with an Anaerobic Hypolimnion

Inhibitors of eucaryotes (cycloheximide and amphotericin B) and procaryotes (penicillin and chloramphenicol) were used to estimate bacterivory and bacterial production in a eutrophic lake. Bacterial production appeared to be slightly greater than protozoan grazing in the aerobic waters of Lake Oglethorpe. Use of penicillin and cycloheximide yielded inconsistent results in anaerobic water and in aerobic water when bacterial production was low. Production measured by inhibiting eucaryotes with cycloheximide did not always agree with [³H]thymidine estimates or differential filtration methods. Laboratory experiments showed that several common freshwater protozoans continued to swim and ingest bacterium-size latex beads in the presence of the eucaryote inhibitor. Penicillin also affected grazing rates of some ciliates. We recommend that caution and a corroborating method be used when estimating ecologically important parameters with specific inhibitors.     

Drought mildly reduces plant dominance in a temperate prairie ecosystem across years

1. Shifts in dominance and species reordering can occur in response to global change. However, it is not clear how altered precipitation and disturbance regimes interact to affect species composition and dominance.
2. We explored community‐level diversity and compositional similarity responses, both across and within years, to a manipulated precipitation gradient and annual clipping in a mixed‐grass prairie in Oklahoma, USA. We imposed seven precipitation treatments (five water exclusion levels [?20%, ?40%, ?60%, ?80%, and ?100%], water addition [+50%], and control [0% change in precipitation]) year‐round from 2016 to 2018 using fixed interception shelters. These treatments were crossed with annual clipping to mimic hay harvest.
3. We found that community‐level responses were influenced by precipitation across time. For instance, plant evenness was enhanced by extreme drought treatments, while plant richness was marginally promoted under increased precipitation.
4. Clipping promoted species gain resulting in greater richness within each experimental year. Across years, clipping effects further reduced the precipitation effects on community‐level responses (richness and evenness) at both extreme drought and added precipitation treatments.
5. Synthesis: Our results highlight the importance of studying interactive drivers of change both within versus across time. For instance, clipping attenuated community‐level responses to a gradient in precipitation, suggesting that management could buffer community‐level responses to drought. However, precipitation effects were mild and likely to accentuate over time to produce further community change.

     

Antigen presentation by the BCL1 murine B cell line: in vitro stimulation by LPS

We examined the antigen-presenting capacity of BCL1 tumor cells, which are capable of differentiating in vitro with respect to immunoglobulin synthesis/secretion under the influence of LPS. In vivo passaged BCL1 cells depleted of host cell contamination either by positive selection employing panning with anti-lambda reagents, or by elimination of latex-ingesting adherent cells, are capable of MHC-restricted antigen presentation to a GAT-immune T cell line. The BCL1 cells act as antigen-presenting cells when freshly explanted, but gradual loss of this function occurs, and cells cultured for 3.5 days cannot present antigen unless LPS is included during the culture period. BCL1 cells are equivalently Ia+ after the culture period with or without LPS stimulation. Other B cell lines capable of antigen presentation appear to express this trait constitutively, and the in vivo passaged BCL1 line is therefore unique among B cell lines in having antigen-presenting cell function that can be modulated. The data suggest that freshly explanted or LPS-cultured BCL1 cells are heterogeneous with respect to antigen-presenting capacity, and the basis for this heterogeneity is being sought. BCL1 offers an opportunity to study requirements for antigen presentation by B cells.     

Evidence that the nigrotegmental GABAergic projection mediates stereotypy induced by apomorphine and intranigral muscimol

The substantia nigra plays a pivotal role in the relay of output from the striatum. One neural pathway from substantia nigra projects GABAergic fibers to the caudal mesencephalic tegmentum, terminating in the vicinity of the pedunculopontine nucleus (PPN). To evaluate the functional importance of this projection in the mediation of stereotyped behaviors of striatal and nigral origin, we microinjected low doses of the GABA agonist, muscimol, bilaterally into the vicinity of the PPN. This muscimol treatment resulted in a total blockade of all stereotyped behaviors normally elicited by systemic apomorphine or by intranigral muscimol. Blockade was not observed in animals microinjected with muscimol into the dorsal reticular formation, 1 mm above the level of the PPN. Our results indicate that the nigrotegmental projection may play a crucial role in the expression of stereotyped and dyskinetic behaviors of basal ganglia origin.     

Separation of metabolically radiolabeled O-methylmannitols and O-methylfucitol by reverse-phase high-performance liquid chromatography: applications to animal cell oligosaccharide structural analysis

Reverse-phase high-performance liquid chromatography was utilized to separate efficiently and rapidly a standard mixture of various radiolabeled O-methylated mannitols and O-methylfucitol commonly encountered when vertebrate asparagine-linked oligosaccharides are subjected to permethylation, hydrolysis, and reduction with NaBH4. The following reduced, radioactive O-methylhexitols were resolved: 2,4-, 3,4-, and 3,6-di-O-methylmannitols; 3,4,6-tri-O-methylmannitol, 2,3,4-tri-O-methylfucitol, and 2,3,4,6-tetra-O-methylmannitol. To demonstrate the utility of this separation method in the analysis of metabolically radiolabeled asparagine-linked oligosaccharides, mouse lymphoma BW 5147 cells were metabolically radiolabeled with [2-3H]mannose and their glycopeptides prepared by Pronase digestion and fractionated by serial chromatography on immobilized lectins. Each fraction was subjected to methylation and hydrolysis, the released monosaccharides were reduced, and the radioactive O-methylhexitols were separated by reverse-phase HPLC. The relative amounts of the O-methylhexitols in each glycopeptide fraction analyzed were similar to those values determined by a combination of other separation systems.