Potential Bark and Fruit Browsing as Revealed by Stereomicrowear Analysis of the Peculiar Clawed Herbivores Known as Chalicotheres (Perissodactyla,Chalicotherioidea)

This low magnification stereomicrowear study samples a broad range of chalicotheres (Perissodactyla, Chalicotherioidea), including basal chalicotheres and the two chalicotheriid subfamilies Schizotheriinae and Chalicotheriinae, primarily including species from North America and Europe, but also some from Asia. The schizotheriines Moropus, Tylocephalonyx, and Metaschizotherium and the chalicotheriines Anisodon and Chalicotherium are best represented. Paleodiets are interpreted via discriminant analysis, using comparison of microwear variables from fossil chalicothere teeth with those from a database of extant ungulates with known diets. The results suggest that all of the chalicotheres in the study were browsers, with no evidence of significant grass consumption. Basal chalicotheres, like basal equids, seem to have been standard fruit-dominated browsers. Stereomicrowear agrees with mesowear results by Schulz et al. (2007) and Schulz and Fahlke (2009) for Metaschizotherium bavaricum, Metaschizotherium fraasi, Anisodon grande, and Chalicotherium goldfussi in showing a highly abrasive aspect to the diet. In these species, hard food objects such as fibrous fruits, seeds, pits, and nuts may have abraded the teeth (based on high pit counts, the presence of large puncture pits, and many individuals with coarse to hypercoarse scratches). Anisodon grande and C. goldfussi, despite their relatively short, brachydont teeth, show the highest degree of abrasion within the studied sample. Moropus and Tylocephalonyx from North America show somewhat different but also abrasive microwear; in these taxa the resistant foods may have been twigs and bark (large pits common, but gouging more prevalent than puncture pits). A preliminary comparison of stereomicrowear on DP4, the deciduous upper fourth premolar, with that on molars suggests that juveniles consumed similar foods as adults but without the most abrasive elements. Some important methodological differences regarding the scoring of microwear features by different low-magnification microwear methodologies are discussed.     

Do edge responses cascade up or down a multi‐trophic food web?

Despite nearly 100?years of edge studies, there has been little effort to document how edge responses 'cascade' to impact multi-trophic food webs. We examined changes within two, four-tiered food webs located on opposite sides of a habitat edge. Based on a 'bottom-up' resource-based model, we predicted plant resources would decline near edges, causing similar declines in specialist herbivores and their associated predators, while a generalist predator was predicted to increase due to complementary resource use. As predicted, we found declines in both specialist herbivores and predators near edges, but, contrary to expectations, this was not driven by gradients in plant resources. Instead, the increase in generalist predators near edges offers one alternative explanation for the observed declines. Furthermore, our results suggest how recent advances in food web theory could improve resource-based edge models, and vice versa.     

Lack of the receptor for advanced glycation end-products attenuates E. coli pneumonia in mice

Background

The receptor for advanced glycation end-products (RAGE) has been suggested to modulate lung injury in models of acute pulmonary inflammation. To study this further, model systems utilizing wild type and RAGE knockout (KO) mice were used to determine the role of RAGE signaling in lipopolysaccharide (LPS) and E. coli induced acute pulmonary inflammation. The effect of intraperitoneal (i.p.) and intratracheal (i.t.) administration of mouse soluble RAGE on E. coli injury was also investigated.

Methodology/Principal Findings

C57BL/6 wild type and RAGE KO mice received an i.t. instillation of LPS, E. coli, or vehicle control. Some groups also received i.p. or i.t. administration of mouse soluble RAGE. After 24 hours, the role of RAGE expression on inflammation was assessed by comparing responses in wild type and RAGE KO. RAGE protein levels decreased in wild type lung homogenates after treatment with either LPS or bacteria. In addition, soluble RAGE and HMGB1 increased in the BALF after E. coli instillation. RAGE KO mice challenged with LPS had the same degree of inflammation as wild type mice. However, when challenged with E. coli, RAGE KO mice had significantly less inflammation when compared to wild type mice. Most cytokine levels were lower in the BALF of RAGE KO mice compared to wild type mice after E. coli injury, while only monocyte chemotactic protein-1, MCP-1, was lower after LPS challenge. Neither i.p. nor i.t. administration of mouse soluble RAGE attenuated the severity of E. coli injury in wild type mice.

Conclusions/Significance

Lack of RAGE in the lung does not protect against LPS induced acute pulmonary inflammation, but attenuates injury following live E. coli challenge. These findings suggest that RAGE mediates responses to E. coli-associated pathogen-associated molecular pattern molecules other than LPS or other bacterial specific signaling responses. Soluble RAGE treatment had no effect on inflammation.     

Pannexin channels are not gap junction hemichannels

Pannexins, a class of membrane channels, bear significant sequence homology with the invertebrate gap junction proteins, innexins and more distant similarities in their membrane topologies and pharmacological sensitivities with the gap junction proteins, connexins. However, the functional role for the pannexin oligomers, or pannexons, is different from connexin oligomers, the connexons. Many pannexin publications have used the term "hemichannels" to describe pannexin oligomers while others use the term "channels" instead. This has led to confusion within the literature about the function of pannexins that promotes the idea that pannexons serve as gap junction hemichannels and thus have an assembly and functional state as gap junctional intercellular channels. Here we present the case that unlike the connexin gap junction intercellular channels, so far, pannexin oligomers have repeatedly been shown to be channels that are functional in single membranes, but not as intercellular channel in appositional membranes. Hence, they should be referred to as channels and not hemichannels. Thus, we advocate that in the absence of firm evidence that pannexins form gap junctions, the use of the term "hemichannel" be discontinued within the pannexin literature.     

Multiple insulin degrading enzyme variants alter in vitro reporter gene expression

The insulin degrading enzyme (IDE) variant, v311 (rs6583817), is associated with increased post-mortem cerebellar IDE mRNA, decreased plasma β-amyloid (Aβ), decreased risk for Alzheimer''s disease (AD) and increased reporter gene expression, suggesting that it is a functional variant driving increased IDE expression. To identify other functional IDE variants, we have tested v685, rs11187061 (associated with decreased cerebellar IDE mRNA) and variants on H6, the haplotype tagged by v311 (v10; rs4646958, v315; rs7895832, v687; rs17107734 and v154; rs4646957), for altered in vitro reporter gene expression. The reporter gene expression levels associated with the second most common haplotype (H2) successfully replicated the post-mortem findings in hepatocytoma (0.89 fold-change, p = 0.04) but not neuroblastoma cells. Successful in vitro replication was achieved for H6 in neuroblastoma cells when the sequence was cloned 5′ to the promoter (1.18 fold-change, p = 0.006) and 3′ to the reporter gene (1.29 fold change, p = 0.003), an effect contributed to by four variants (v10, v315, v154 and v311). Since IDE mediates Aβ degradation, variants that regulate IDE expression could represent good therapeutic targets for AD.     

Do Lions Panthera leo Actively Select Prey or Do Prey Preferences Simply Reflect Chance Responses via Evolutionary Adaptations to Optimal Foraging?

Research on coursing predators has revealed that actions throughout the predatory behavioral sequence (using encounter rate, hunting rate, and kill rate as proxy measures of decisions) drive observed prey preferences. We tested whether similar actions drive the observed prey preferences of a stalking predator, the African lion Panthera leo. We conducted two 96 hour, continuous follows of lions in Addo Elephant National Park seasonally from December 2003 until November 2005 (16 follows), and compared prey encounter rate with prey abundance, hunt rate with prey encounter rate, and kill rate with prey hunt rate for the major prey species in Addo using Jacobs' electivity index. We found that lions encountered preferred prey species far more frequently than expected based on their abundance, and they hunted these species more frequently than expected based on this higher encounter rate. Lions responded variably to non-preferred and avoided prey species throughout the predatory sequence, although they hunted avoided prey far less frequently than expected based on the number of encounters of them. We conclude that actions of lions throughout the predatory behavioural sequence, but particularly early on, drive the prey preferences that have been documented for this species. Once a hunt is initiated, evolutionary adaptations to the predator-prey interactions drive hunting success.     

Low-dose IL-2 induces cytokine cascade, eosinophilia, and a transient Th2 shift in melanoma patients

Purpose: To assess changes in serum cytokine levels in patients treated concomitantly with or without systemic low-dose IL-2. Vaccination targeted CTL responses to peptide antigens, and IL-2 was coadministered to expand activated CTL. Paradoxically, CTL responses were diminished in patients after 2 weeks of IL-2. We hypothesized that changes in the cytokine milieu may have contributed to this result. Experimental design: Serum samples were studied from 37 patients enrolled in two clinical trials of a melanoma peptide vaccine administered with or without low-dose IL-2 therapy. Twenty-two patients enrolled in the MEL36 trial received six weekly vaccinations with the four-peptide mixture and were randomized to receive subcutaneous IL-2 (3×10⁶ IU/m²/day) daily for 6 weeks beginning either at week 1 (upfront group) or at week 4 (delayed group) of vaccine therapy. Fifteen patients on the MEL39 trial were treated with the same vaccine without concurrent IL-2 administration. Results: Circulating levels of IL-5 peaked 1 week after starting IL-2, followed 2 weeks later by a marked eosinophilia, correlating in magnitude with peak IL-5 serum levels. Levels of IFN, GM-CSF, IL-4, IL-10, and IL-12 had no observed relationship to IL-2 administration. At the time of the IL-5 serum peak, PBL responses to mitogen suggested a transient shift to Th2-dominance. Conclusions: Low-dose IL-2 appears to have induced a transient Th2-dominant secondary cytokine cascade at the time of vaccination, for which eosinophilia is a surrogate marker. For future vaccine therapies targeting cytotoxic T-cell responses, delaying IL-2 until after initiation of immune responses may be more effective.William Chad Cragun and Galina V. Yamshchikov contributed equally to this paper.     

Cardiovascular actions of rattlesnake bradykinin ([Val1,Thr6]bradykinin) in the anesthetized South American rattlesnake Crotalus durissus terrificus

Incubation of heat-denatured plasma from the rattlesnake Crotalus atrox with trypsin generated a bradykinin (BK) that contained two amino acid substitutions (Arg1 --> Val and Ser6 --> Thr) compared with mammalian BK. Bolus intra-arterial injections of synthetic rattlesnake BK (0.01-10 nmol/kg) into the anesthetized rattlesnake, Crotalus durissus terrificus, produced a pronounced and concentration-dependent increase in systemic vascular conductance (Gsys). This caused a fall in systemic arterial blood pressure (Psys) and an increase in blood flow. Heart rate and stroke volume also increased. This primary response was followed by a significant rise in Psys and pronounced tachycardia (secondary response). Pretreatment with N(G)-nitro-L-arginine methyl ester reduced the NK-induced systemic vasodilatation, indicating that the effect is mediated through increased NO synthesis. The tachycardia associated with the late primary and secondary response to BK was abolished with propranolol and the systemic vasodilatation produced in the primary phase was also significantly attenuated by pretreatment, indicating that the responses are caused, at least in part, by release of cathecholamines and subsequent stimulation of beta-adrenergic receptors. In contrast, the pulmonary circulation was relatively unresponsive to BK.     

Molecular mechanism of hTid-1, the human homolog of Drosophila tumor suppressor l(2)Tid, in the regulation of NF-kappaB activity and suppression of tumor growth

hTid-1, a human homolog of the Drosophila tumor suppressor l(2)Tid and a novel DnaJ protein, regulates the activity of nuclear factor kappaB (NF-kappaB), but its mechanism is not established. We report here that hTid-1 strongly associated with the cytoplasmic protein complex of NF-kappaB-IkappaB through direct interaction with IkappaBalpha/beta and the IKKalpha/beta subunits of the IkappaB kinase complex. These interactions resulted in suppression of the IKK activity in a J-domain-dependent fashion and led to the cytoplasmic retention and enhanced stability of IkappaB. Overexpression of hTid-1 by using recombinant baculovirus or adenovirus led to inhibition of cell proliferation and induction of apoptosis of human osteosarcoma cells regardless of the p53 expression status. Adherent cultured cells transduced with Ad.hTid-1 detached from the dish surface. Morphological changes consistent with apoptosis and cell death were evident 48 h after Ad.EGFP-hTid-1 transduction. In contrast, cells transduced with Ad.EGFP or Ad.EGFP-hTd-1DeltaN100, a mutant that has the N-terminal J domain deletion and that lost suppressive activity on IKK, continued to proliferate. Similar data were obtained with A375 human melanoma cells. Ad.EGFP or Ad.EGFP-hTd-1DeltaN100 ex vivo-transduced A375 cells injected subcutaneously into nude mice produced growing tumors, whereas Ad.EGFP-hTid-1-transduced cells did not. Collectively, the data suggest that hTid-1 represses the activity of NF-kappaB through physical and functional interactions with the IKK complex and IkappaB and, in doing so, it modulates cell growth and death.