Using Grazing to Manage Herbaceous Structure for a Heterogeneity-Dependent Bird

Grazing management recommendations often sacrifice the intrinsic heterogeneity of grasslands by prescribing uniform grazing distributions through smaller pastures, increased stocking densities, and reduced grazing periods. The lack of patch-burn grazing in semi-arid landscapes of the western Great Plains in North America requires alternative grazing management strategies to create and maintain heterogeneity of habitat structure (e.g., animal unit distribution, pasture configuration), but knowledge of their effects on grassland fauna is limited. The lesser prairie-chicken (Tympanuchus pallidicinctus), an imperiled, grassland-obligate, native to the southern Great Plains, is an excellent candidate for investigating effects of heterogeneity-based grazing management strategies because it requires diverse microhabitats among life-history stages in a semi-arid landscape. We evaluated influences of heterogeneity-based grazing management strategies on vegetation structure, habitat selection, and nest and adult survival of lesser prairie-chickens in western Kansas, USA. We captured and monitored 116 female lesser prairie-chickens marked with very high frequency (VHF) or global positioning system (GPS) transmitters and collected landscape-scale vegetation and grazing data during 2013–2015. Vegetation structure heterogeneity increased at stocking densities ≤0.26 animal units/ha, where use by nonbreeding female lesser prairie-chickens also increased. Probability of use for nonbreeding lesser prairie-chickens peaked at values of cattle forage use values near 37% and steadily decreased with use ≥40%. Probability of use was positively affected by increasing pasture area. A quadratic relationship existed between growing season deferment and probability of use. We found that 70% of nests were located in grazing units in which grazing pressure was <0.8 animal unit months/ha. Daily nest survival was negatively correlated with grazing pressure. We found no relationship between adult survival and grazing management strategies. Conservation in grasslands expressing flora community composition appropriate for lesser prairie-chickens can maintain appropriate habitat structure heterogeneity through the use of low to moderate stocking densities (<0.26 animal units/ha), greater pasture areas, and site-appropriate deferment periods. Alternative grazing management strategies (e.g., rest-rotation, season-long rest) may be appropriate in grasslands requiring greater heterogeneity or during intensive drought. Grazing management favoring habitat heterogeneity instead of uniform grazing distributions will likely be more conducive for preserving lesser prairie-chicken populations and grassland biodiversity. © 2021 The Wildlife Society.     

Culturable Diversity and Community Fatty Acid Profiling of Sulfate-Reducing Fluidized-Bed Reactors Treating Acidic,Metal-Containing Wastewater

Cultivable strains were identified from sulfate-reducing fluidized-bed reactors (FBR) treating acidic metal-containing wastewater. The FBR-communities were further characterized using culture-independent phenotypic markers, phospholipid fatty acid (PLFA) profiling. After morphological screening of 128 bacterial strains and partial sequencing of 55 strains, 17 distinct phylogenetic types were identified and characterized further. A total of 14 and 6 different bacterial strains were isolated from ethanol- and lactate-fed FBRs, respectively. Sequencing of the 16S rRNA gene showed that these strains were affiliated with members of the δ-Proteobacteria, Firmicutes and Bacteroidetes The strains were affiliated with members of the genera Desulfovibrio, Desulfotomaculum, Desulfobulbus, Desulfitobacterium, Clostridium, Caloramator, Oxobacter, and Bacteroides. Many of the strains were only distantly related to previously described species and, thus, may represent novel species or genera. A number of the strains were not detected in previously employed molecular analyses of the FBR communities, and the major component of each FBR as identified in the molecular analyses were not retrieved as cultures in this study. Most of the SRB, and two of the non-SRB utilized ethanol and lactate as a source of carbon and energy, but none of the isolates grew on acetate, an intermediate in the oxidation of ethanol and lactate. PLFA analysis revealed that the FBR community members contained large amounts of saturated fatty acids. Although the PLFA analysis showed some signatures consistent with sulfate-reducing communities, it did not show any substantial difference in the microbial communities between the reactors, an outcome that was quite contrary to the culture-independent phylogenetic analyses.     

Sequence-specific DNA-binding proteins which interact with (G + C)-rich sequences flanking the chicken c-myc gene

The interaction of nuclear sequence-specific DNA-binding proteins from definitive chicken erythrocytes, thymus and proliferating transformed erythroid precursor (HD3) cells with the 700-base-pair (700-bp) DNA 5'-flanking region of the chicken c-myc gene was investigated by in vitro footprint analysis. The major HD3 protein-binding activity binds to a site (site V) 200 bp upstream from the 'cap' site but, after further fractionation, a second distinct binding activity is detected to a site (site VIII) which contains both the 'CAAT' and 'SP1-binding' consensus sequences. Protein from thymus and erythrocyte cells which express c-myc at lower levels, bind to seven and eight sites respectively. In common with HD3 cell protein, they both bind to site VIII and, although binding to the sequence at site V is also detected, the footprint protection pattern is sufficiently different (site V') to suggest the involvement of different proteins in terminally differentiated and proliferating cells. The DNA-binding activities were partially fractionated by high-performance liquid chromatography gel filtration and include an erythrocyte-specific protein which binds to a c-myc gene poly(dG) homopolymer sequence similar to that found upstream of the chicken beta A-globin gene.     

Dyes from a twenty-first century perspective

In June 2008, the Biological Stain Commission sponsored A Seminar on Dyes and Staining the purpose of which was twofold: first, to show that very useful information applicable to biomedical dyes and staining is available from unrelated disciplines and second, to summarize modern thinking on how dyes, solvents, and tissues interact to produce selective staining. In this introduction to the papers from the symposium, we acknowledge that biomedical dye research has declined as newer technologies have gained importance. We should point out, however, that dyes and staining still are vitally important. Moreover, needs abound for innovative studies concerned with dye analysis, synthesis, and mode of action. Concepts and tools from unrelated fields hold promise for significant breakthroughs in many areas of interest.     

Novel application of reversed-phase UPLC-oaTOF-MS for lipid analysis in complex biological mixtures: a new tool for lipidomics

Ultra-Performance LC (UPLC) utilizing sub-2-mum porous stationary phase particles operating with high linear velocities at pressures >9000 psi was coupled with orthogonal acceleration time-of-flight (oaTOF) mass spectrometry and successfully employed for the rapid separation of lipids from complex matrices. The UPLC system produced information-rich chromatograms with typical measured peak widths of 3 s at peak base, generating peak capacities in excess of 200 in 10 min. Further UPLC coupled with MSE technology provided parent and fragment mass information of lipids in one chromatographic run, thus, providing an attractive alternative to current LC methods for targeted lipid analysis as well as lipidomic studies.     

Influence of DNA synthesis inhibition on the coordinate expression of core human histone genes during S phase

Core histone mRNA metabolism has been examined in S phase HeLa cells recovering from DNA synthesis inhibition by 1 mM hydroxyurea. Using cloned human histone genes as probes for histone mRNA quantitation, the response to and recovery from DNA synthesis inhibition is shown to depend on the position of the cell with respect to the initiation of DNA replication. The incorporation of 3H-uridine into multiple histone mRNAs in recovering cells does not exceed preinhibition levels, and as this incorporation is maximal in early S phase, the synthesis of core histone mRNA is apparently related to the ordered replication of the genome. The total histone mRNA present in interrupted S phase cells after recovery is not significantly different from that present in control cells, and a temporal and functional coupling between histone mRNA levels and the relative rate of DNA synthesis is maintained in perturbed cells.     

Induction of minisatellite mutations in the mouse germline by low-dose chronic exposure to gamma-radiation and fission neutrons

Germline mutation induction at mouse minisatellite loci by paternal low-dose (0.125-1 Gy) exposure to chronic (1.66 x 10(-4) Gy min(-1)) low-linear energy transfer (low-LET) gamma-irradiation and high-LET fission neutrons (0.003 Gy min(-1)) was studied at pre-meiotic stages of spermatogenesis. Both types of radiation produced linear dose-response curves for mutation of the paternal allele. In contrast to previous results using higher doses, the pattern of induction of minisatellite mutation after chronic gamma-irradiation was similar to acute (0.5 Gy min(-1)) exposure to X-rays, indicating that the elevated mutation rate was independent of the ability of the cell to repair damage induced immediately or over a period of up to 100 h. Chronic exposure to fission neutrons was more effective than acute or chronic low-LET exposure (relative biological effectiveness, RBE=3.36). The data also provide strong support for the previous conclusion that increases in minisatellite mutation rate are not caused by radiation-induced DNA damage at minisatellite loci themselves, but rather from damage induced by ionising radiation elsewhere in the genome/cell.     

Burkholderia cenocepacia disrupts host cell actin cytoskeleton by inactivating Rac and Cdc42

Burkholderia cenocepacia, a member of the Burkholderia cepacia complex, is an opportunistic pathogen that causes devastating infections in patients with cystic fibrosis. The ability of B. cenocepacia to survive within host cells could contribute significantly to its virulence in immunocompromised patients. In this study, we explored the mechanisms that enable B. cenocepacia to survive inside macrophages. We found that B. cenocepacia disrupts the actin cytoskeleton of infected macrophages, drastically altering their morphology. Submembranous actin undergoes depolymerization, leading to cell retraction. The bacteria perturb actin architecture by inactivating Rho family GTPases, particularly Rac1 and Cdc42. GTPase inactivation follows internalization of viable B. cenocepacia and compromises phagocyte function: macropinocytosis and phagocytosis are markedly inhibited, likely impairing the microbicidal and antigen‐presenting capability of infected macrophages. The type VI secretion system is essential for the bacteria to elicit these changes. This is the first report demonstrating inactivation of Rho family GTPases by a member of the B. cepacia complex.