Aspects of the Trophic Ecology of an Invertivorous Snake Community

Understanding the significance of trophic links has been of interest to ecologists for decades, likely because food web studies have the potential to reveal a considerable amount of information in the fields of ecosystem and community ecology. Despite the intrinsic benefits that come from elucidating food web structures, doing so is often problematic because of the complex and dynamic nature of ecological communities. The dietary ecology of small-bodied invertivorous snakes remains relatively understudied compared to other snake species. Many of these species are abundant throughout their range, making them ideal organisms for studying community-level questions. I employed a combination of stable isotope analyses as well as gut and fecal material analyses to quantify the trophic niche width of five species of invertivorous snakes (genera: Coluber, Diadophis, Opheodrys, and Storeria) occurring in central Illinois. I investigated seasonal differences in capture rates and quantified morphometric and isotopic differences among species. I used Bayesian mixing models to determine the potential sources of C13 and N15 in scale, red blood cell, and plasma tissue samples. The stable isotope data, supported by the gut and fecal analyses, revealed differences in the levels of dietary specialization within the community. High levels of trophic niche overlap were detected, however, indicating that snake dietary preferences are more likely a product of taxonomic affinity and species specific life-history, rather than interspecific competition. Further studies that involve a combination of techniques can provide a more comprehensive understanding of dietary ecology within snake communities

Aspects of the Trophic Ecology of an Invertivorous Snake Community

Understanding the significance of trophic links has been of interest to ecologists for decades, likely because food web studies have the potential to reveal a considerable amount of information in the fields of ecosystem and community ecology. Despite the intrinsic benefits that come from elucidating food web structures, doing so is often problematic because of the complex and dynamic nature of ecological communities. The dietary ecology of small-bodied invertivorous snakes remains relatively understudied compared to other snake species. Many of these species are abundant throughout their range, making them ideal organisms for studying community-level questions. I employed a combination of stable isotope analyses as well as gut and fecal material analyses to quantify the trophic niche width of five species of invertivorous snakes (genera: Coluber, Diadophis, Opheodrys, and Storeria) occurring in central Illinois. I investigated seasonal differences in capture rates and quantified morphometric and isotopic differences among species. I used Bayesian mixing models to determine the potential sources of C13 and N15 in scale, red blood cell, and plasma tissue samples. The stable isotope data, supported by the gut and fecal analyses, revealed differences in the levels of dietary specialization within the community. High levels of trophic niche overlap were detected, however, indicating that snake dietary preferences are more likely a product of taxonomic affinity and species specific life-history, rather than interspecific competition. Further studies that involve a combination of techniques can provide a more comprehensive understanding of dietary ecology within snake communities

“You don’t see them on the streets of your town”: challenges and strategies for serving unstably housed veterans in rural areas

Research on policy and programmatic responses to homelessness has focused largely on urban areas, with comparatively little attention paid to the rural context. We conducted qualitative interviews with a nationwide sample of rural-serving agencies receiving grants through the U.S. Department of Veterans Affairs’ Supportive Services for Veteran Families program to better understand the housing needs, available services, needed resources, and challenges in serving homeless and unstably housed veterans in rural areas. Respondents discussed key challenges—identifying unstably housed veterans, providing services within the rural resource context, and leveraging effective collaboration—and strategies to address these challenges. Unmet needs identified included emergency and subsidized long-term housing options, transportation resources, flexible financial resources, and additional funding to support the intensive work required in rural areas. Our findings identify promising programmatic innovations and highlight the need for policy remedies that are responsive to the unique challenges of addressing homelessness and housing instability in rural areas.Accepted manuscrip

Pathways into homelessness among post 9/11 era veterans

This article may not exactly replicate the final version published in the APA journal. It is not the copy of record.Despite the scale of veteran homelessness and government–community initiatives to end homelessness among veterans, few studies have featured individual veteran accounts of experiencing homelessness. Here we track veterans’ trajectories from military service to homelessness through qualitative, semistructured interviews with 17 post-9/11-era veterans. Our objective was to examine how veterans become homeless—including the role of military and postmilitary experiences—and how they negotiate and attempt to resolve episodes of homelessness. We identify and report results in 5 key thematic areas: transitioning from military service to civilian life, relationships and employment, mental and behavioral health, lifetime poverty and adverse events, and use of veteran-specific services. We found that veterans predominantly see their homelessness as rooted in nonmilitary, situational factors such as unemployment and the breakup of relationships, despite very tangible ties between homelessness and combat sequelae that manifest themselves in clinical diagnoses such as posttraumatic stress disorder. Furthermore, although assistance provided by the U.S. Department of Veterans Affairs (VA) and community-based organizations offer a powerful means for getting veterans rehoused, veterans also recount numerous difficulties in accessing and obtaining VA services and assistance. Based on this, we offer specific recommendations for more systematic and efficient measures to help engage veterans with VA services that can prevent or attenuate their homelessness

Needles in a haystack: screening and healthcare system evidence for homelessness

Effectiveness of screening for homelessness in a large healthcare system was evaluated in terms of successfully referring and connecting patients with appropriate prevention or intervention services. Screening and healthcare services data from nearly 6 million U.S. military veterans were analyzed. Veterans either screened positive for current or risk of housing instability, or negative for both. Current living situation was used to validate results of screening. Administrative evidence for homelessness-related services was significantly higher among positive-screen veterans who accepted a referral for services compared to those who declined. Screening for current or risk of homelessness led to earlier identification, which led to earlier and more extensive service engagement

Cytoplasmic Capes Are Nuclear Envelope Intrusions That Are Enriched in Endosomal Proteins and Depend upon βH-Spectrin and Annexin B9

It is increasingly recognized that non-erythroid spectrins have roles remote from the plasma membrane, notably in endomembrane trafficking. The large spectrin isoform, βH, partners with Annexin B9 to modulate endosomal processing of internalized proteins. This modulation is focused on the early endosome through multivesicular body steps of endocytic processing and loss of either protein appears to cause a traffic jam before removal of ubiquitin at the multivesicular body. We previously reported that βH/Annexin B9 influenced EGF receptor signaling. While investigating this effect we noticed that mSptiz, the membrane bound precursor of the secreted EGF receptor ligand sSpitz, is located in striking intrusions of the nuclear membrane. Here we characterize these structures and identify them as ‘cytoplasmic capes’, which were previously identified in old ultrastructural studies and probably coincide with recently recognized sites of non-nuclear-pore RNA export. We show that cytoplasmic capes contain multiple endosomal markers and that their existence is dependent upon βH and Annexin B9. Diminution of these structures does not lead to a change in mSpitz processing. These results extend the endosomal influence of βH and its partner Annexin B9 to this unusual compartment at the nuclear envelope

Relationship between water and aragonite barium concentrations in aquaria reared juvenile corals

This paper is not subject to U.S. copyright. The definitive version was published in Geochimica et Cosmochimica Acta 209 (2017): 123-134, doi:10.1016/j.gca.2017.04.006.Coral barium to calcium (Ba/Ca) ratios have been used to reconstruct records of upwelling, river and groundwater discharge, and sediment and dust input to the coastal ocean. However, this proxy has not yet been explicitly tested to determine if Ba inclusion in the coral skeleton is directly proportional to seawater Ba concentration and to further determine how additional factors such as temperature and calcification rate control coral Ba/Ca ratios. We measured the inclusion of Ba within aquaria reared juvenile corals (Favia fragum) at three temperatures (∼27.7, 24.6 and 22.5 °C) and three seawater Ba concentrations (73, 230 and 450 nmol kg−1). Coral polyps were settled on tiles conditioned with encrusting coralline algae, which complicated chemical analysis of the coral skeletal material grown during the aquaria experiments. We utilized Sr/Ca ratios of encrusting coralline algae (as low as 3.4 mmol mol−1) to correct coral Ba/Ca for this contamination, which was determined to be 26 ± 11% using a two end member mixing model. Notably, there was a large range in Ba/Ca across all treatments, however, we found that Ba inclusion was linear across the full concentration range. The temperature sensitivity of the distribution coefficient is within the range of previously reported values. Finally, calcification rate, which displayed large variability, was not correlated to the distribution coefficient. The observed temperature dependence predicts a change in coral Ba/Ca ratios of 1.1 μmol mol−1 from 20 to 28 °C for typical coastal ocean Ba concentrations of 50 nmol kg−1. Given the linear uptake of Ba by corals observed in this study, coral proxy records that demonstrate peaks of 10–25 μmol mol−1 would require coastal seawater Ba of between 60 and 145 nmol kg−1. Further validation of the coral Ba/Ca proxy requires evaluation of changes in seawater chemistry associated with the environmental perturbation recorded by the coral as well as verification of these results for Porites species, which are widely used in paleo reconstructions.M.E.G. was supported by a NDSEG graduate fellowship. Funding for this research came from the NSF Chemical Oceanography program (OCE-0751525) and the Coastal Ocean Institute, the Ocean and Climate Change Institute and the Ocean Ventures Fund at Woods Hole Oceanographic Institution

Increased Antibody Affinity Confers Broad In Vitro Protection against Escape Mutants of Severe Acute Respiratory Syndrome Coronavirus

Even though the effect of antibody affinity on neutralization potency is well documented, surprisingly, its impact on neutralization breadth and escape has not been systematically determined. Here, random mutagenesis and DNA shuffling of the single-chain variable fragment of the neutralizing antibody 80R followed by bacterial display screening using anchored periplasmic expression (APEx) were used to generate a number of higher-affinity variants of the severe acute respiratory syndrome coronavirus (SARS-CoV)-neutralizing antibody 80R with equilibrium dissociation constants (KD) as low as 37 pM, a >270-fold improvement relative to that of the parental 80R single-chain variable fragment (scFv). As expected, antigen affinity was shown to correlate directly with neutralization potency toward the icUrbani strain of SARS-CoV. Additionally, the highest-affinity antibody fragment displayed 10-fold-increased broad neutralization in vitro and completely protected against several SARS-CoV strains containing substitutions associated with antibody escape. Importantly, higher affinity also led to the suppression of viral escape mutants in vitro. Escape from the highest-affinity variant required reduced selective pressure and multiple substitutions in the binding epitope. Collectively, these results support the hypothesis that engineered antibodies with picomolar dissociation constants for a neutralizing epitope can confer escape-resistant protection

ERK/MAPK Signaling Drives Overexpression of the Rac-GEF, PREX1, in BRAF- and NRAS-Mutant Melanoma

Recently we identified that PREX1 overexpression is critical for metastatic but not tumorigenic growth in a mouse model of NRAS-driven melanoma. In addition, a PREX1 gene signature correlated with and was dependent on ERK mitogen-activated protein kinase (MAPK) activation in human melanoma cell lines. In the current study, the underlying mechanism of PREX1 overexpression in human melanoma was assessed. PREX1 protein levels were increased in melanoma tumor tissues and cell lines compared with benign nevi and normal melanocytes, respectively. Suppression of PREX1 by siRNA impaired invasion but not proliferation in vitro. PREX1-dependent invasion was attributable to PREX1-mediated activation of the small GTPase RAC1 but not the related small GTPase CDC42. Pharmacologic inhibition of ERK signaling reduced PREX1 gene transcription and additionally regulated PREX1 protein stability. This ERK-dependent upregulation of PREX1 in melanoma, due to both increased gene transcription and protein stability, contrasts with the mechanisms identified in breast and prostate cancers, where PREX1 overexpression was driven by gene amplification and HDAC-mediated gene transcription, respectively. Thus, although PREX1 expression is aberrantly upregulated and regulates RAC1 activity and invasion in these three different tumor types, the mechanisms of its upregulation are distinct and context-dependent

MTX-cIBR Conjugate for Targeting Methotrexate to Leukocytes: Conjugate Stability and in vivo Efficacy in Suppressing Rheumatoid Arthritis

Methotrexate (MTX) has been used to treat rheumatoid arthritis at low doses and leukemia at high doses; however, this drug can produce severe side effects. Our hypothesis is that MTX side effects can be attenuated by directing the drug to the target cells (i.e., leukocytes) using cIBR peptide. To test this hypothesis, MTX was conjugated to the N-terminus of cIBR peptide to give MTX-cIBR conjugate. MTX-cIBR (5.0 mg/kg) suppressed joint arthritis in adjuvant arthritis rats and prevented periarticular inflammation and bone resorption of the limb joints. In vitro, the toxicity of MTX-cIBR peptide against Molt-3 T cells was inhibited by anti-LFA-1 antibody and cIBR peptide in a concentration-dependent manner, suggesting that the uptake of MTX-cIBR was partially mediated by LFA-1. Chemical stability studies indicated that MTX-cIBR was most stable at pH 6.0. The MTX portion of MTX-cIBR was unstable under acidic conditions whereas the cIBR portion was unstable under basic conditions. In biological media, MTX-cIBR had short half-lives in rat plasma (44 min) and homogenized rat heart tissue (38 min). This low plasma stability may contribute to the low in vivo efficacy of MTX-cIBR; therefore, there is a need to design a more stable conjugate to improve the in vivo efficacy