Response of greater sage-grouse to sagebrush reduction treatments in Wyoming big sagebrush

Vegetation treatments have been widely implemented in efforts to enhance conditions for wildlife populations. Yet the effectiveness of such efforts often lack rigorous evaluations to determine whether these practices are effective for targeted species. This is particularly important when manipulating wildlife habitats in ecosystems that are faced with multiple stressors. The sagebrush (Artemisia spp.) ecosystem has been altered extensively over the last century leading to declines of many associated species. Wyoming big sagebrush (A. tridentata wyomingensis) is the most widely distributed subspecies, providing important habitats for sagebrush-obligate and associated wildlife. Sagebrush often has been treated with chemicals, mechanical treatments, and prescribed burning to increase herbaceous forage species released from competition with sagebrush overstory. Despite many studies documenting negative effects of sagebrush control on greater sage-grouse (Centrocercus urophasianus) habitat, treatments are still proposed as a means of improving habitat for sage-grouse and other sagebrush-dependent species. Furthermore, most studies have focused on vegetation response and none have rigorously evaluated the direct influence of these treatments on sage-grouse. We initiated a 9-year (2011–2019) experimental study in central Wyoming, USA, to better understand how greater sage-grouse respond to sagebrush reduction treatments in Wyoming big sagebrush communities. We evaluated the influence of 2 common sagebrush treatments on greater sage-grouse demography and resource selection. We implemented mowing and tebuthiuron application in winter and spring 2014 and evaluated the pre- (2011–2013) and post-treatment (2014–2019) responses of sage-grouse relative to these management actions. We evaluated responses to treatments using demographic and behavioral data collected from 620 radio-marked female greater sage-grouse. Our specific objectives were to evaluate how treatments influenced 1) sage-grouse reproductive success and female survival; 2) sage-grouse nesting, brood-rearing, and female resource selection; 3) vegetation responses; and 4) forbs and invertebrates. Our results generally suggested neutral demographic responses and slight avoidance by greater sage-grouse in response to Wyoming big sagebrush treated by mowing and tebuthiuron. Neither mowing nor tebuthiuron treatments influenced nest survival, brood survival, or female survival. Selection for nest and brood-rearing sites did not differ before and after treatments. Females selected habitats near treatments before and after they were implemented; however, the strength of selection was lower after treatments compared with pre-treatment periods, which may be explained by a lack of response in vegetation and invertebrates following treatments. Perennial grass cover and height varied temporally yet did not vary systematically between treatment and control plots. Forb cover and species richness varied annually but not in relation to either treatment type. Perennial grass cover and height, forb cover, and forb species richness did not increase within mowed or tebuthiuron-treated areas that received 2 or 6 years of grazing rest compared with areas that received no grazing rest. Finally, forb and invertebrate dry mass did not differ between treated plots and control plots at mowing or tebuthiuron sites in any years following treatments. Results from our study add to a large body of evidence that sage-grouse using Wyoming big sagebrush vegetation communities do not respond positively to sagebrush manipulation treatments. Management practices that focus on the maintenance of large, undisturbed tracts of sagebrush will best facilitate the persistence of sage-grouse populations and other species reliant on the sagebrush steppe.     

Cloning and analysis of the mating type genes from Cochliobolus heterostrophus

Cochliobolus heterostrophus, a heterothallic Ascomycete, has a single mating type locus with two alternate forms called MAT-1 and MAT-2. MAT-1 was cloned by complementing a MAT-2 strain using a cosmid library from a MAT-1 strain and screening for a homothallic transformant. The cosmid recovered from this transformant was able to re-transform a MAT-2 strain to homothallism and MAT identity was proven by restriction fragment length polymorphism and conventional genetic mapping. All homothallic transformants could mate with either MAT-1 or MAT-2 strains, although the number of ascospores produced by self matings or crosses to MAT-2 strains was low. Progeny of selfed homothallic transformants were themselves homothallic. MAT-2 was cloned by probing a cosmid library from a MAT-2 strain with a fragment of insert DNA from the MAT-1 cosmid. A 1.5 kb subclone of either MAT-containing cosmid was sufficient to confer mating function in transformants. Examination of the DNA sequence of these subclones revealed that MAT-1 and MAT-2 contain 1297 by and 1171 bp, respectively, of completely dissimilar DNA flanked by DNA common to both mating types. Putative introns were found (one in each MAT gene) which, when spliced out, would yield open reading frames (ORFs) that occupied approximately 90% of the dissimilar DNA sequences. Translation of the MAT-1 ORF revealed similarity to the Neurospora crassa MATA, Podospora anserina mat?, and Saccharomyces cerevisiae MATα1 proteins; translation of the MAT-2 ORF revealed similarity to the N. crassa MATa, P. anserina mat+, and Schizosaccharomyces pombe mat-Mc proteins. These gene products are all proven or proposed DNA binding proteins. Those with similarity to MAT-2 are members of the high mobility group.     

Persistence of an infectious disease in a subdivided population

The transmission dynamics of a communicable disease in a subdivided population where the spread among groups follows the proportionate mixing model while the within-group transmission can correspond to preferred mixing, proportionate mixing among subgroups, or mixing between social and nonsocial subgroups, is analyzed. It is shown that the threshold condition for the disease to persist is that either (i) the disease can persist within at least one group through intragroup contacts, or--if (i) does not hold--(ii) the intergroup transmission is sufficiently high. The among-group transmission is computed as an average where each subgroup's reproductive number is weighted according to its intragroup activity level squared and the total number of cases that one infectious individual will cause through intragroup contacts. The model thus allows for a study of the relative importance of communitywide disease transmission and of disease transmission within geographically or socially separate groups.     

Extrachromosomal plasmid-like DNA in the obligate parasitic fungus Erysiphe graminis f. sp. hordei

Summary The obligate parasitic fungus, Erysiphe graminis f. sp. hordei, was found to harbour plasmid-like extrachromosomal DNA. A 1.35-kb fragment of this 9kb plasmid was cloned into the pUC12 vector. No homology was detected to nuclear or mitochondrial DNA. As only about half of the 27 isolates examined contained plasmid-like DNA, this appears to be inessential for fungal survival. The plasmid is frequent in European isolates and is found in both newly collected isolates and in isolates kept under laboratory conditions for many years. No correlation between presence of plasmid and specific avirulence/virulence genes was found. The plasmid appear to be located in the mitochondria.     

The cytoplasmic and transmembrane domains of secretor type α1,2fucosyltransferase confer atypical cellular localisation

Carbohydrate structures influence many aspects of cell biology. Manipulating the glycosyltransferase enzymes, that sequentially add carbohydrate moieties to proteins and lipids as they pass through the Golgi and secretory pathway, can alter these carbohydrate epitopes. We previously demonstrated that the eight amino acid cytoplasmic tail of α1,2fucosyltransferase (FT) contained a sequence for Golgi localisation. In this study, we examined the localisation of the closely related secretor type α1,2fucosyltransferase (Sec) which has a smaller, yet apparently unrelated, five amino acid cytoplasmic tail. In contrast to the Golgi localisation of FT, Sec displayed atypical cytoplasmic vesicular‐like staining. However, replacing just the five amino acid tail of Sec with FT was sufficient to relocalise the enzyme to a perinuclear region with Golgi‐like staining. The biological significance of this relocalisation was this chimaeric enzyme was more effective than FT at competing for N‐Acetyl‐lactosamine and thus was superior in reducing expression of the Galα(1,3)Gal xenoepitope. Copyright © 2009 John Wiley & Sons, Ltd.     

Anatomical and chemical characteristics of the seed coat of <i>Medicago sativa</i> L. (alfalfa) cv. Baralfa 85 seeds and their association with seed dormancy

Seeds of alfalfa (Medicago sativa L.) can exhibit seedcoat imposed dormancy, which produces hard seeds within a seed lot. These seeds do not germinate because they do not imbibe water due to a barrier to water entry in the seed coat. The aim of this work was to analyze the anatomical and chemical characteristics of the testa of alfalfa seeds with respect to water permeability levels. The anatomy of seeds of the cv. Baralfa 85 was studied and structural substances, polyphenols, tannins and cutin present in the testa of seeds of different water permeability levels were determined. The anatomical characteristics of the seed coat and the proportions of components were found to determine the permeability level of the seed coat, an aspect that is associated with the physical seed dormancy level. Anatomically, increased thickness of the testa was associated with a lower permeability level. The difference may be attributed to the variation in cuticle thickness, length of macrosclereids and thickness of the cell wall, and presence and development of osteosclereids. From the physiological and chemical points of view, the mechanism of physical dormancy of the testa is explained by a greater amount of components that repel water and cement the cell wall, such as polyphenols, lignins, condensed tannins, pectic substances, and a lower proportion of cellulose and hemicellulose.     

Spectroscopic evidence for the existence of an obligate pre-fibrillar oligomer during glucagon fibrillation

The 29-residue peptide hormone glucagon has been used as a model system for the study of amyloid-like fibrils. Atomic force microscopy (AFM) studies have detected putative oligomeric species during this lag phase, but this has not been confirmed by any spectroscopic technique. Here we use an attached pyrene group to detect association (excimer formation) between individual glucagon molecules. Our data show that excimer formation precedes fibrillation both at different pHs and with sulfate, and support our original proposal that glucagon fibril formation is preceded by oligomer formation. We suggest that pyrene-labelling may be a useful way to monitor oligomer formation during protein fibrillation.