Electron-microscopic and immunocytochemical analyses of Weibel-Palade bodies in the human umbilical vein during pregnancy

Summary The present study was done to elucidate the biological significance of the Weibel-Palade body of human umbilical vein endothelial cells. Quantitative determinations of these endothelial-specific granules throughout pregnancy revealed that their numbers and size per cell profile were maintained at low levels from 12 to 19 weeks of gestation; then both rapidly increased from 33 weeks to full term. This increase coincided with the development of the rough endoplasmic reticulum and an increase in the number of endothelial cell pinocytotic vesicles. Light-microscopic peroxidase anti-peroxidase and electron-microscopic protein A-gold techniques provided evidence that factor VIII-related antigen was localized in the Weibel-Palade bodies. Furthermore, in vitro treatment of incubated umbilical vein tissue with compound 48/80, a histamine releaser, induced degranulation of Weibel-Palade bodies from the endothelium. The present study indicates that Weibel-Palade bodies are storage sites of both histamine and factor VIII-related antigen and have an important role in the obliteration of this vessel.     

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Fort Greely, Alaska has an extensive complex of weapon training and testing areas located on lands withdrawn from the public domain under the Military Lands Withdrawal Act (PL106-65).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.     

A tail length modifier gene discovered in the Japanese wild mice (Mus musculus molossinus)

The presence of the t haplotypes in strains derived from the Japanese wild mice (Mus musculus molossinus) was investigated. Crosses between the T/+ heterozygous short tailed mice and five normal tailed molossinus strains (MOL-ANJ, MOA, MOL-NEM, MOM and Mns) produced no tailless mice, indicating that these strains possess no t haplotype. In contrast, tailless mice were produced by a cross between the T/+ heterozygotes and a MOL-NIS strain. Mating experiments showed that the tailless character was due to an interaction between the T gene and an autosomal recessive gene carried by the MOL-NIS strain that expresses the short tail character under the homozygous condition. We have tentatively named this gene brachyury-interacting tail length modifier (btm). It remains to be investigated whether the btm gene is located in the t complex region or in the other locus.     

Dissection of the role of macrophages in triggering T lymphocytes for interleukin 2 production by monoclonal antibody OKT3

Unfractionated human peripheral blood mononuclear cells produce a small amount of interleukin 2 (IL 2) by stimulation with a monoclonal anti-T3 antibody (OKT3) in vitro. The IL 2 production could be greatly augmented by the addition of a phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate (TPA). In the presence of TPA, the T cell enriched fraction deprived of macrophages did not produce IL 2, but the T cells pulse-incubated with OKT3 and reconstituted with macrophages efficiently produced IL 2 in subsequent culture in the presence of TPA as did T cells reconstituted with OKT3-pulse-incubated macrophages. The stimulating effect of OKT3 in the presence of macrophages was inhibited dose-dependently by the addition of immunoglobulins, particularly by mouse IgG2a which is the same isotype as that of the OKT3 antibody, showing that it inhibits by blocking the binding of OKT3 to Fc receptors on macrophages. The same extent of IL 2 production was induced in T cells when paraformaldehyde-fixed macrophages were substituted for intact macrophages. Remarkable IL 2 production was also induced by OKT3 when latex beads coated with rabbit anti-mouse IgG2a antibody and TPA were added to the culture. It was confirmed that the production induced by these stimulations was due to an increase of IL 2 mRNA. These results show that effective signals for IL 2 production are generated by efficient crosslinking of T3 molecules which results from multi-interaction of T3 molecules on the T cell membrane and anti-T3 antibody molecules on macrophage membrane or on the surface of the latex particle.     

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.