A multiple watershed field test of hydrogeomorphic functional assessment of headwater streams—Variability in field measurements between independent teams

Ephemeral and intermittent headwater streams are under increasing pressure from disturbance and development. Rapid, repeatable assessment techniques are needed in order to gauge the condition of these stream systems. Several attributes of these headwater streams constrain the use of the most widely used macroinvertebrate or water quality stream assessment techniques. The hydrogeomorphic (HGM) functional assessment is a reference-based alternative technique. To evaluate this alternative, repeated assessments were conducted in eight high-gradient headwaters in West Virginia by four independent teams. Across-site and measurement variance among teams was assessed using a coefficient of variation (CV, expressed as percent). A variability of >50% CV, which suggests less repeatable results, occurred in only 13.8% of measurements, primarily associated with 2 of the 9 variables examined (snag density and substrate size). Between site measurement variance was the greatest at more highly disturbed sample locations, particularly with regard to the large woody debris, tree species richness, and channel bank erosion variables. Variables with the lowest CV were tree diameter, detrital cover, canopy cover, and channel embeddedness. Based on these results, measurements included when applying HGM approach to these streams should focus on direct measurements or directed estimates that yield a large response range across a spectrum of sites while maintaining consistent repeatability among different teams, with special attention paid to their use in highly disturbed sites.     

Staphylococcus aureus cell wall structure and dynamics during host-pathogen interaction

Peptidoglycan is the major structural component of the Staphylococcus aureus cell wall, in which it maintains cellular integrity, is the interface with the host, and its synthesis is targeted by some of the most crucial antibiotics developed. Despite this importance, and the wealth of data from in vitro studies, we do not understand the structure and dynamics of peptidoglycan during infection. In this study we have developed methods to harvest bacteria from an active infection in order to purify cell walls for biochemical analysis ex vivo. Isolated ex vivo bacterial cells are smaller than those actively growing in vitro, with thickened cell walls and reduced peptidoglycan crosslinking, similar to that of stationary phase cells. These features suggested a role for specific peptidoglycan homeostatic mechanisms in disease. As S. aureus missing penicillin binding protein 4 (PBP4) has reduced peptidoglycan crosslinking in vitro its role during infection was established. Loss of PBP4 resulted in an increased recovery of S. aureus from the livers of infected mice, which coincided with enhanced fitness within murine and human macrophages. Thicker cell walls correlate with reduced activity of peptidoglycan hydrolases. S. aureus has a family of 4 putative glucosaminidases, that are collectively crucial for growth. Loss of the major enzyme SagB, led to attenuation during murine infection and reduced survival in human macrophages. However, loss of the other three enzymes Atl, SagA and ScaH resulted in clustering dependent attenuation, in a zebrafish embryo, but not a murine, model of infection. A combination of pbp4 and sagB deficiencies resulted in a restoration of parental virulence. Our results, demonstrate the importance of appropriate cell wall structure and dynamics during pathogenesis, providing new insight to the mechanisms of disease.     

The Importance of Mentorship and Interest Group Involvement for the Orthopedic Surgery Applicant

BackgroundMentorship in medical education is important for students’ professional development career planning. Orthopedic Surgery Interest Groups (OSIG) exist as formal organizations and serve as a conduit for undergraduate mentorship, though the role of mentorship via OSIGs within orthopedic medicine has not been thoroughly evaluated. Similarly, OSIGs within institutions are not standardized nor well defined. We sought to answer: (1) What offerings does OSIG provide for students interested in orthopaedic surgery? (2) How does OSIG involvement impact the orthopaedic surgery residency applicant? (3) Does OSIG involvement increase match rates for orthopaedic surgery residency applicants?MethodsAn online survey was distributed to faculty advisors at all allopathic US medical schools with available contact information. Results were analyzed using SPSS.ResultsOf the 28 respondent organizations, the majority (53.6%) have between 1-25 student members. On average, OSIGS offer 3.64 + 1.59 (mode = 4) executive positions. The most important initiative for OSIG groups was clinical/surgical shadowing, followed by faculty mentorship, and guidance for the residency application. OSIG involvement does impact the applicant, as all faculty mentors believed this to be an important component of the residency application. Leadership positions within OSIG was not perceived as being equally important. OSIG involvement did increase match rates; the match rate for all students at the schools surveyed (n=17) was 81.21% while the match rate for students within OSIG (n=17) was 82.39% (p<0.05). Of all students who applied to orthopedic surgery residency programs, 98.9% were members of OSIG, and of all students who successfully matched into orthopedic surgery residency programs in the 2019-2020 cycle, 100% (p<0.05) of students (n=17) were involved in OSIG.ConclusionThis study indicates the importance of involvement in OSIG as a conduit for clinical exposure and mentorship throughout medical education, and is especially relevant for applicants given the impact of the COVID-19 pandemic on the residency application process. Data suggests that participation in an OSIG is a valuable experience for the medical student interested in orthopedics and that students involved in OSIGs are more likely to match into orthopedic residency programs. Level of Evidence: V     

Evidence for fine-scale habitat specialisation in an invasive weed

Aims As an exotic species colonises a new continent, it must overcome enormous environmental variation in its introduced range. Local adaptation of introduced species has frequently been observed at the continent scale, particularly in response to latitudinal climatic variation. However, significant environmental heterogeneity can also exist at the landscape scale. A small number of studies have provided evidence that introduced species may also be capable of phenotypic and genetic differentiation at much smaller spatial scales. For example, previously we found US agricultural and non-agricultural populations of Sorghum halepense (Johnsongrass) to be phenotypically and genetically distinct. In this study, we investigated whether this phenotypic differentiation of agricultural and non-agricultural populations of S. halepense is the result of fine-scale local specialisation.Methods We surveyed a nationally collected S. halepense germplasm panel and also collected neighbouring agricultural and non-agricultural sub-populations of S. halepense at four sites throughout Western Virginia, USA, raising seedlings in common conditions mimicking both agricultural and non-agricultural habitats.Important findings At the national scale, we found evidence of habitat differentiation but not specialisation. However, at the local scale, we found evidence of specialisation in two of the four local populations to non-agricultural habitat, but no evidence of specialisation to agricultural habitat. These results show that local specialisation is a possible, but not guaranteed consequence of kilometre-scale habitat heterogeneity in invasive species. This finding contributes to a growing awareness of the importance of fine-scale local adaptation in the ecology and management of introduced and weedy species.     

Coloboma Hyperactive Mutant Mice Exhibit Regional and Transmitter-Specific Deficits in Neurotransmission

Abstract: The mouse mutant coloboma ( Cm /+), which exhibits profound spontaneous hyperactivity and bears a deletion mutation on chromosome 2, including the gene encoding synaptosomal protein SNAP-25, has been proposed to model aspects of attention-deficit hyperactivity disorder. Increasing evidence suggests a crucial role for SNAP-25 in the release of both classical neurotransmitters and neuropeptides. In the present study, we compared the release of specific neurotransmitters in vitro from synaptosomes and slices of selected brain regions from Cm /+ mice with that of +/+ mice. The release of dopamine (DA) and serotonin (5-HT) from striatum, and of arginine vasopressin and corticotropin-releasing factor from hypothalamus and amygdala is calcium-dependent. Glutamate release from and content in cortical synaptosomes of Cm /+ mice are greatly reduced, which might contribute to the learning deficits in these mutants. In dorsal striatum of Cm /+ mutants, but not ventral striatum, KCI-induced release of DA is completely blocked and that of 5-HT is significantly attenuated, suggesting that striatal DA and 5-HT deficiencies may be involved in hyperactivity. Further, although acetylcholine failed to induce hypothalamic corticotropin-releasing factor release from Cm /+ slices, restraint stress increased plasma corticosterone levels in Cm /+ mice to a significantly higher level than in +/+ mice, suggesting an important role for arginine vasopressin in hypothalamic-pituitary-adrenal axis activation. These results suggest that reduced SNAP-25 expression may contribute to a region-specific and neurotransmitter-specific deficiency in neurotransmitter release.     

Molecular characterization of two ammonium transporters from the ectomycorrhizal fungus Hebeloma cylindrosporum

Heterologous expression of the yeast triple Mep mutant has enabled the first molecular characterization of AMT/MEP family members in an ectomycorrhizal fungus. External hyphae, which play a key role in nitrogen nutrition of trees, are considered as the absorbing structure of the ectomycorrhizal symbiosis and therefore molecular studies on ammonium transport in hyphae are urgently needed. The kinetic properties of AMT2 and AMT3 from Hebeloma cylindrosporum were studied in Saccharomyces cerevisiae. Expression of HcAmts in the yeast triple Mep mutant restored ammonium retention within cells. The HcAmts did not complement the ammonium sensing defect phenotype of Mep2Delta cells during pseudohyphal differentiation. Northern blot analysis in H. cylindrosporum showed that the HcAMTs were up-regulated upon nitrogen deprivation and down-regulated by ammonium.     

Efficacy of mating disruption compared with chemical insecticides for controlling Tuta absoluta (Lepidoptera: Gelechiidae) in Kuwait

Applied Entomology and Zoology - The efficacy of mating disruption with Isonet®-T at the rate of 30, 45 or 60&nbsp;g a.i. ha –1 of sex pheromone to control Tuta absoluta (Meyrick)...     

A novel application of entropy analysis for assessing changes in movement variability during cumulative tackles in young elite rugby league players

The aim of this study was to identify between-position (forwards vs. backs) differences in movement variability in cumulative tackle events training during both attacking and defensive roles. Eleven elite adolescent male rugby league players volunteered to participate in this study (mean ± SD, age; 18.5 ± 0.5 years, height; 179.5 ± 5.0 cm, body mass; 88.3 ± 13.0 kg). Participants performed a drill encompassing four blocks of six tackling (i.e. tackling an opponent) and six tackled (i.e. being tackled by an opponent while carrying a ball) events (i.e. 48 total tackles) while wearing a micro-technological inertial measurement unit (WIMU, Realtrack Systems, Spain). The acceleration data were used to calculate sample entropy (SampEn) to analyse the movement variability during tackles performance. In tackling actions SampEn showed significant between-position differences in block 1 (p = 0.0001) and block 2 (p = 0.0003). Significant between-block differences were observed in backs (block 1 vs 3, p = 0,0021; and block 1 vs 4, p = 0,0001) but not in forwards. When being tackled, SampEn showed significant between-position differences in block 1 (p = 0.0007) and block 3 (p = 0.0118). Significant between-block differences were only observed for backs in block 1 vs 4 (p = 0,0025). Movement variability shows a progressive reduction with cumulative tackle events, especially in backs and when in the defensive role (tackling). Forwards present lower movement variability values in all blocks, particularly in the first block, both in the attacking and defensive role. Entropy measures can be used by practitioners as an alternative tool to analyse the temporal structure of variability of tackle actions and quantify the load of these actions according to playing position.