Co-administration of Selenium with Inorganic Mercury Alters the Disposition of Mercuric Ions in Rats

Biological Trace Element Research - Mercury (Hg) is a common environmental toxicant to which humans are exposed regularly through occupational and dietary means. Although selenium supplementation...     

Development of a multi-assay approach for monitoring coral diversity using eDNA metabarcoding

Coral Reefs - Cumulative anthropogenic pressures have triggered a global decline in the health of marine ecosystems, and coral reefs, in particular, are in crisis. With climate and...     

First observations of intersex development in paddlefish Polyodon spathula

This study reports the first cases of intersex (abnormal development of both male and female reproductive tissues in a gonad) paddlefish Polyodon spathula, an Acipenseriform species of large rivers in the central U.S. and in aquaculture worldwide. Despite a large, multi-decadal data set in Oklahoma, Montana, and North Dakota, intersex development was not observed until 2019, when two individuals were harvested from the Grand Lake/Neosho River stock in Oklahoma. This suggests that intersex development in mid-water, zooplanktivorous paddlefish is rarer than in bottom-dwelling sturgeons for which intersex development is regularly observed. Although contaminants are implicated in causing intersex development in other Acipenseriformes, more investigation is needed.     

Green light drives photosynthesis in mosses

Temperate forests are characterised by variable light quality (i.e. spectral composition of light) at or near the forest floor. These understory environments have a high concentration of green light, as red and blue light are preferentially absorbed by upper canopy leaves. Understory species may be well-adapted for using green light to drive photosynthesis. Angiosperms have been shown to use green light for photosynthesis, but this ability has not been demonstrated in shade-dwelling bryophytes. In this study, net photosynthetic rate (P_N) of three temperate understory species of moss (Dichodontium pellucidum (Hedw.) Schimp., Leucobryum albidum (Brid. ex P.Beauv) Lindb. and Amblystegium serpens (Hedw.) Schimp.) was measured under green, red?+?blue, and red?+?blue?+?green light to assess green light use efficiency. All three species were capable of photosynthesising beyond their respiratory demands using solely green light, with higher green light use efficiency measured in plants collected from areas with greater canopy cover, suggesting growth in a green light concentrated environment increases green light use efficiency. Each species was also collected from sites differing in their degree of canopy cover and grown under three light treatments (high light, low light, and green light). Photosynthetic efficiency (chlorophyll fluorescence), tissue nitrogen and carbon isotope concentrations were assessed after a short growth period. Growth conditions had little effect on leaf chemistry and monochromatic green light did not significantly degrade photosynthetic efficiency. This study provides the first evidence to date of positive net ‘green light photosynthesis’ in mosses.     

Phylogenetics of Stelis and closely related genera (Orchidaceae: Pleurothallidinae)

Stelis, one of the largest genera within Pleurothallidinae, was recently recircumscribed to include a few hundred more species, most of which had previously been assigned to Pleurothallis. Here, a new phylogenetic analysis of Stelis and closely related genera based on DNA sequences from nuclear ITS and chloroplast matK, based on a much larger sample, is presented; it includes more than 100 species assigned to Stelis and covers all proposed groupings within the genus, many of which have not previously been represented. Clades are proposed to enable easier discussion of groups of closely related species; each clade is characterized morphologically, ecologically, and geographically to explain the evidence found in the molecular analysis. Discussion of the evolutionary trends of character states found in the genus in its broad sense is given. The current taxonomy of the group is given and the possible taxonomical implications of the findings presented here are discussed.     

Home range and habitat selection of northern bobwhite coveys in an agricultural landscape

Northern bobwhites thrive in fine-grained landscapes with a diversity of early succession woodland, grassland, and agriculture-associated habitat types. Bobwhite conservation has proved challenging in the increasingly coarse-grained Midwestern landscape as simplified agricultural cropping systems are implemented at larger spatial scales. Regardless, managing agricultural landscapes on private lands is the primary opportunity to restore bobwhite populations in the Midwestern United States. Although bobwhite habitat requirements are well understood, habitat selection in contemporary Midwestern landscapes is not well understood, especially on private lands where populations are declining. We used compositional analysis to investigate second- (study area) and third- (home range) order habitat selection by radiomarked bobwhite coveys on 4 private land study areas in southwestern Ohio. Mean covey home range size was 26.1 ± 2.2 ha (n = 48). Although home ranges were established in areas with more grassland cover, bobwhites most strongly selected early succession woody habitat (e.g., fencerows and ditches) at all scales, and selection for grassland diminished between the study area and home range scales. Grassland selection varied among sites and was strongest on sites with more row crop area. Woodlots were avoided at the study area scale, but were selected within home ranges. Grassland cover, like that provided by contemporary conservation programs, is an essential component of bobwhite habitat in the Midwest, but our results suggest more emphasis should be placed on early succession woody cover. Woody cover associated with fencerows, ditches, and woodlots adjacent to food sources and breeding habitat will likely improve non-breeding season survival, which is an influential vital rate in northern populations. © 2012 The Wildlife Society.     

Site-Directed Mutations in the Lanthipeptide Mutacin 1140

The oral bacterium Streptococcus mutans, strain JH1140, produces the antibiotic mutacin 1140. Mutacin 1140 belongs to a group of antibiotics called lanthipeptides. More specifically, mutacin 1140 is related to the epidermin type A(I) lanthipeptides. Mutagenesis experiments of this group of lanthipeptides have been primarily restricted to the posttranslationally modified meso-lanthionine and 3-methyllanthionine residues. Site-directed mutagenesis of the core peptide of mutacin 1140 was performed using the suicide vector pVA891. Substitutions of the N-terminal residue, the charged residue in the hinge region, and residues in ring A and intertwined rings C and D were investigated. A truncation and insertion of residues in ring A and intertwined rings C and D were also performed to determine whether or not they would alter the antimicrobial activity of the producing strain. Bioassays revealed that five of 14 mutants studied had improved antimicrobial activity against the indicator strain Micrococcus luteus ATCC 10240. MICs against Streptococcus mutans UA159, Streptococcus pneumoniae ATCC 27336, Staphylococcus aureus ATCC 25923, Clostridium difficile UK1, and Micrococcus luteus ATCC 10240 were determined for three mutacin 1140 variants that had the most significant increases in bioactivity in the M. luteus bioassay. This mutagenesis study of the epidermin group of lanthipeptides shows that antimicrobial activity can be significantly improved.