Divergent Selection and Primary Gene Flow Shape Incipient Speciation of a Riparian Tree on Hawaii Island

A long-standing goal of evolutionary biology is to understand the mechanisms underlying the formation of species. Of particular interest is whether or not speciation can occur in the presence of gene flow and without a period of physical isolation. Here, we investigated this process within Hawaiian Metrosideros, a hypervariable and highly dispersible woody species complex that dominates the Hawaiian Islands in continuous stands. Specifically, we investigated the origin of Metrosideros polymorpha var. newellii (newellii), a riparian ecotype endemic to Hawaii Island that is purportedly derived from the archipelago-wide M. polymorpha var. glaberrima (glaberrima). Disruptive selection across a sharp forestriparian ecotone contributes to the isolation of these varieties and is a likely driver of newellii’s origin. We examined genome-wide variation of 42 trees from Hawaii Island and older islands. Results revealed a split between glaberrima and newellii within the past 0.3–1.2 My. Admixture was extensive between lineages within Hawaii Island and between islands, but introgression from populations on older islands (i.e., secondary gene flow) did not appear to contribute to the emergence of newellii. In contrast, recurrent gene flow (i.e., primary gene flow) between glaberrima and newellii contributed to the formation of genomic islands of elevated absolute and relative divergence. These regions were enriched for genes with regulatory functions as well as for signals of positive selection, especially in newellii, consistent with divergent selection underlying their formation. In sum, our results support riparian newellii as a rare case of incipient ecological speciation with primary gene flow in trees

Varieties of the Highly Dispersible and Hypervariable Tree, Metrosideros Polymorpha, Differ in Response to Mechanical Stress and Light Across a Sharp Ecotone

Premise: The drivers of isolation between sympatric populations of long‐lived and highly dispersible conspecific plants are not well understood. In the Hawaiian Islands, the landscape‐dominant tree, Metrosideros polymorpha, displays extraordinary phenotypic differences among sympatric varieties despite high dispersibility of its pollen and seeds, thereby presenting a unique opportunity to investigate how disruptive selection alone can maintain incipient forms. Stenophyllous M. polymorpha var. newellii is a recently evolved tree endemic to the waterways of eastern Hawai\u27i Island that shows striking neutral genetic differentiation from its ancestor, wet‐forest M. polymorpha var. glaberrima, despite sympatry of these forms. We looked for evidence for, and drivers of, differential local adaptation of these varieties across the range of M. polymorpha var. newellii. Methods: For paired populations of these varieties, we compared seedling performance under contrasting light conditions and a strong water current characteristic of the riparian zone. We also conducted a reciprocal transplant experiment and contrasted adult leaf anatomy. Results: Results suggest that the riparian zone is harsh and that selection involving the mechanical stress of rushing water, and secondarily, light, led to significant reciprocal immigrant inviability in adjacent forest and riparian environments. The strongest adaptive divergence between varieties was seen in leaves and seedlings from the site with the sharpest ecotone, coincident with the strongest genetic isolation of M. polymorpha var. newellii observed previously. Conclusions: These findings suggest that disruptive selection across a sharp ecotone contributes to the maintenance of an incipient riparian ecotype from within a continuous population of a long‐lived and highly dispersible tree species

Isolation of Metrosideros (`Ohi`a) Taxa on O`ahu Increases with Elevation and Extreme Environments

Species radiations should be facilitated by short generation times and limited dispersal among discontinuous populations. Hawaii’s hyper-diverse, landscape-dominant tree, Metrosideros, is unique among the islands’ radiations for its massive populations that occur continuously over space and time within islands, its exceptional capacity for gene flow by both pollen and seed, and its extended life span (ca. \u3e650 years). Metrosideros shows the greatest phenotypic and microsatellite DNA diversity on O`ahu, where taxa occur in tight sympatry or parapatry in mesic and montane wet forest on 2 volcanoes. We document the nonrandom distributions of 12 taxa (including unnamed morphotypes) along elevation gradients, measure phenotypes of ~6-year-old common-garden plants of 8 taxa to verify heritability of phenotypes, and examine genotypes of 476 wild adults at 9 microsatellite loci to compare the strengths of isolation across taxa, volcanoes, and distance. All 8 taxa retained their diagnostic phenotypes in the common garden. Populations were isolated by taxon to a range of degrees (pairwise FST between taxa: 0.004–0.267), and there was no pattern of isolation by distance or by elevation; however, significant isolation between volcanoes was observed within monotypic species, suggesting limited gene flow between volcanoes. Among the infraspecific taxa of Metrosideros polymorpha, genetic diversity and isolation significantly decreased and increased, respectively, with elevation. Overall, 5 of the 6 most isolated taxa were associated with highest elevations or otherwise extreme environments. These findings suggest a principal role for selection in the origin and maintenance of the exceptional diversity that occurs within continuous Metrosideros stands on O`ahu

Strawberry cultivars vary in productivity, sugars and phytonutrient content when grown in a greenhouse during the winter

In many areas of the US, fresh locally grown berries are not available during the winter. With this in mind, a research study comprised of three experiments was conducted focused on cultivar selection for berry yield, number, sweetness and phytonutrient content. Using a capillary mat system with under bench heating within a double-layer polyethylene greenhouse, strawberries were grown in the Great Plains Region of the US during the winter. During experiment 1, 12 cultivars were grown; berries were weighed, counted and analyzed for sugars and phytonutrients. “Albion” plants produced a high number/mass of berries, had relatively high sugar content but a lower level of phytonutrients when compared to other cultivars. Sugar and phytonutrients concentrations overlapped across cultivars and thus, one cultivar could not be statistically singled out as best. As all cultivars flowered and fruited, two additional 8-month-long experiments were conducted. It took only 7 weeks from potting of dormant crowns for most cultivars to produce fruit. Certain cultivars fruited more successfully during certain months than others, but this was not associated with response time. For example,” “Albion”, “Chandler”, “Darselect”, “Evie-2” and “Seascape” plants consistently produced fruit October to early January while “AC Wendy”, “Cavendish”, “Honeoye” and “Strawberry Festival” plants mainly produced berries in March/April. Summed over experiment 2, “Albion”, “ Cavendish”, “Chandler”, “ Evie-2”, “Portola” and “Seascape” plants produced the greatest mass of berries. “AC Wendy” and “Darselect” berries contained some of the highest levels of sugars while berries from “Chandler”, “Darselect”, “Evie-2”, “Seascape” and “Strawberry Festival” had some of the highest phytonutrient values. In the third experiment, of the 8 selected cultivars, “Evie-2”, “Evie−2+” and “Portola” plants had the highest total yield and average berry mass/plant. “Seascape” and” Chandler” plants were second in total production. Glucose, fructose and sucrose levels varied across cultivars with “Chandler” and “Seascape” berries possessing the lowest level of total sugars. Phytonutrient values varied among cultivars with some having better flavonoids (“Seascape”), phenols (“Seascape” and “Chandler”) and ant oxidant capacity (“Seascape”, “Evie-2” and “Cavendish”). Measurement of soluble solids concentration varied by week among the cultivars with “Seascape”, “Seascape+”, and “Albion” berries possessing higher levels than other cultivars such as “Cavendish”. Overall, under these winter greenhouse conditions using capillary mat fertigation and an under-bench heat delivery system, strawberries were successfully produced for the off-season market

Interprofessional Team Collaboration for Routine and Emergent Mental Health Concerns Among Collegiate Student-Athletes: A Case Series from the Association for Athletic Training Education Research Network

Collegiate student-athletes experience an increasing number of mental health concerns. To help address these concerns and provide high-quality health care for student-athletes, institutions of higher education are being encouraged to create interprofessional health care teams that are specifically dedicated to managing mental health. We interviewed 3 interprofessional health care teams who collaborate to manage routine and emergency mental health conditions in collegiate student-athletes. Teams represented all 3 National Collegiate Athletics Association (NCAA) divisions and included athletic trainers, clinical psychologists, psychiatrists, dietitians and nutritionists, social workers, nurses, and physician assistants (associates). The interprofessional teams indicated that the existing NCAA recommendations helped to solidify members and roles of the mental health care team; however, they all believed their teams would benefit from more counselors and psychiatrists. Teams had different mechanisms for referral and accessing mental health resources on their campuses, which may make on-the-job training for new members of the team an organizational necessity

Adenine-induced chronic kidney disease induces a similar skeletal phenotype in male and female C57BL/6 mice with more severe deficits in cortical bone properties of male mice

Chronic kidney disease (CKD) causes bone loss, particularly in cortical bone, through formation of cortical pores which lead to skeletal fragility. Animal models of CKD have shown variability in the skeletal response to CKD between males and females suggesting sex may play a role in this variation. Our aim was to compare the impact of adenine-induced CKD on cortical parameters in skeletally mature male and female C57Bl/6 mice. After 10-weeks of adenine-induced CKD, both male and female adenine mice had high serum parathyroid hormone (PTH), high bone turnover, and cortical porosity compared to non-CKD controls. Both sexes had lower cortical thickness, but only male mice had lower cortical bone area. CKD imparted greater deficits in mechanical properties of male mice compared to female mice. These data demonstrate that both male and female mice develop high PTH/high bone turnover in response to adenine-induced CKD and that cortical bone phenotypes are slightly more severe in males, particularly in mechanical properties deficits

Comparison of Winter Strawberry Production in a Commercial Heated High Tunnel versus a University Greenhouse

For the past 4 years, the University of Nebraska strawberry team has worked to develop low cost, sustainable methods for farmers and growers to produce strawberries in a double polyethylene greenhouse during the winter. This past year, this growing system was adapted to become a commercial grower’s heated high tunnel for the winter/spring of 2013-14. The idea was to scale up to a farm-size demonstration and compare it to the university greenhouse production system with a goal to expand marketing opportunities for strawberries into the winter season

Shared Mycobacterium avium Genotypes Observed among Unlinked Clinical and Environmental Isolates

Our understanding of the sources of Mycobacterium avium infection is partially based on genotypic matching of pathogen isolates from cases and environmental sources. These approaches assume that genotypic identity is rare in isolates from unlinked cases or sources. To test this assumption, a high-resolution PCR-based genotyping approach, large-sequence polymorphism (LSP)-mycobacterial interspersed repetitive unit–variable-number tandem repeat (MIRU-VNTR), was selected and used to analyze clinical and environmental isolates of M. avium from geographically diverse sources. Among 127 clinical isolates from seven locations in North America, South America, and Europe, 42 genotypes were observed. Among 12 of these genotypes, matches were seen in isolates from apparently unlinked patients in two or more geographic locations. Six of the 12 were also observed in environmental isolates. A subset of these isolates was further analyzed by alternative strain genotyping methods, pulsed-field gel electrophoresis and MIRU-VNTR, which confirmed the existence of geographically dispersed strain genotypes. These results suggest that caution should be exercised in interpreting high-resolution genotypic matches as evidence for an acquisition event

Activation-induced cytidine deaminase localizes to G-quadruplex motifs at mutation hotspots in lymphoma.

Diffuse large B-cell lymphoma (DLBCL) is a molecularly heterogeneous group of malignancies with frequent genetic abnormalities. G-quadruplex (G4) DNA structures may facilitate this genomic instability through association with activation-induced cytidine deaminase (AID), an antibody diversification enzyme implicated in mutation of oncogenes in B-cell lymphomas. Chromatin immunoprecipitation sequencing analyses in this study revealed that AID hotspots in both activated B cells and lymphoma cells in vitro were highly enriched for G4 elements. A representative set of these targeted sequences was validated for characteristic, stable G4 structure formation including previously unknown G4s in lymphoma-associated genes, CBFA2T3, SPIB, BCL6, HLA-DRB5 and MEF2C, along with the established BCL2 and MYC structures. Frequent genome-wide G4 formation was also detected for the first time in DLBCL patient-derived tissues using BG4, a structure-specific G4 antibody. Tumors with greater staining were more likely to have concurrent BCL2 and MYC oncogene amplification and BCL2 mutations. Ninety-seven percent of the BCL2 mutations occurred within G4 sites that overlapped with AID binding. G4 localization at sites of mutation, and within aggressive DLBCL tumors harboring amplified BCL2 and MYC, supports a role for G4 structures in events that lead to a loss of genomic integrity, a critical step in B-cell lymphomagenesis

The Effect of Single Versus Group μCT on the Detection of Trabecular and Cortical Disease Phenotypes in Mouse Bones

Micro‐computed tomography is a critical assessment tool for bone‐related preclinical research, especially in murine models. To expedite the scanning process, researchers often image multiple bones simultaneously; however, it is unknown if this impacts scan quality and alters the ability to detect differences between experimental groups. The purpose of this study was to assess the effect of multibone scanning on detecting disease‐induced changes in bone microarchitecture and mineral density by group scanning two murine models with known skeletal defects: the Col1a2 G610C/+ model of osteogenesis imperfecta and an adenine‐induced model of chronic kidney disease. Adult male femurs were scanned individually and in random groups of three and eight in a Bruker Skyscan 1172 and 1176, respectively, then assessed for standard trabecular and cortical bone measures. Although scanning methodology altered raw values, with trabecular microarchitecture values more affected than cortical properties, a disease phenotype was still detectable in both group and solo scans. However, tissue mineral density in both trabecular and cortical bone was significantly impacted by group versus solo scanning. Researchers may be able to use small groupings in a single μCT scan to expedite preclinical analyses when the overall bone phenotype is large to decrease costs and increase speed of discoveries; however the details of scanning (single or group) should always be reported