The activation state of p38 mitogen-activated protein kinase determines the efficiency of ATP competition for pyridinylimidazole inhibitor binding

The serine/threonine kinase p38 is a ubiquitous, highly conserved, stress responsive, signal-transducing enzyme. It regulates the production of proinflammatory mediators and is the target of the cytokine synthesis inhibitory pyridinylimidazoles. We have expressed human p38 in Drosophila S2 cells and characterized preparations of mixed unphosphorylated/monophosphorylated (inactive) and homogeneously diphosphorylated (active) forms of the enzyme. We observed that only the active preparation of the enzyme has significant kinase activity when assayed using an ATF2-GST fusion protein as the substrate. We determined that the value of KM[ATP] in this reaction is 25 microM and that the pyridinylimidazole inhibitor of p38 kinase activity, SB203580, competes with ATP. We have found that a tritiated pyridinylimidazole, SB202190, has an equal affinity for both the active and inactive forms of the enzyme and that SB203580 competes with it equally well for binding to either form of the enzyme. However, ATP can compete with the tritiated inhibitor for binding to only the active form of the enzyme. Further, we demonstrate in vivo that at concentrations consistent with its IC50 as a cytokine inhibitor, SB203580 can inhibit stimulus-induced phosphorylation of p38 at the Thr-Gly-Tyr activation motif. Our observations suggest that pyridinylimidazoles may block the biological activity of p38 kinase by binding to the inactive form of p38 and reducing its rate of activation. Under these conditions, ATP would not effectively compete with the inhibitors in vivo.

Pyrroles and other heterocycles as inhibitors of p38 kinase

Investigation of furans, pyrroles and pyrazolones identified 3-pyridyl-2,5-diaryl-pyrroles as potent, orally bioavailable inhibitors of p38 kinase. 3-(4-pyridyl-2-(4-fluoro-phenyl)-5-(4-methylsulfinylphenyl)-pyrrol e (L-167307) reduces secondary paw swelling in the rat adjuvant arthritis model: ID50 = 7.4 mg/kg/b.i.d.

Substituted imidazoles as glucagon receptor antagonists

A modestly active, nonselective triarylimidazole lead was optimized for binding affinity with the human glucagon receptor. This led to the identification of a 2- and/or 4-alkyl or alkyloxy substituent on the imidazole C4-aryl group as a structural determinant for significant enhancement in binding with the glucagon receptor (e.g., 41, IC(50)=0.053 microM) and selectivity (>1000x) over p38MAP kinase in this class of compounds.

Polymorphism of the GHR gene in cattle and relationships with meat production and quality

Growth hormone (GH) exerts its effects on growth and metabolism by interacting with a specific receptor (GHR) on the surface of the target cells. Therefore, GHR has been suggested as candidate gene for traits related to meat production in cattle. The aim of the study was to analyse the polymorphism at position 257 in exon 10 of the GHR gene and investigate relationships with 14 in vivo traits and four meat characteristics in Piemontese animals. The biallelic polymorphism already described was detected using a new PCR procedure. The statistical analysis did not show significant gene substitution effects on growth, size and meat conformation traits. As for meat characteristics, a significant gene substitution of GHR(A) over GHR(G) was observed for drip losses at day 3, with the allele GHR(A) associated with higher values. A significant dominance effect was also observed for this trait. Further investigations in other breeds will be useful for better understanding information on the effect of this GHR polymorphism.

The effects of body mass on dung removal efficiency in dung beetles

Understanding of the role of body mass in structural-functional relationships is pressing, particularly because species losses often occur non-randomly with respect to body size. Our study examined the effects of dung beetle body mass on dung removal at two levels. First, we used the lab experiment to evaluate the efficiency of eight dung beetle species belonging to two functional groups (tunnelers, dwellers) on dung removal. Second, the same species employed in the lab were used in field mesocosms to examine the effects of the two functional groups on dung removal maintaining realistic differences in the total body mass between tunneler and dweller assemblages. Furthermore, the experimental assemblages contained one and four species within each functional group, so the effect of body mass heterogeneity was examined. We used a statistical approach (offset method) which took into account a priori constraints due to the study design allowing us to analyse the effect of larger species in mesocosm style experiments. Body size played a crucial role in dung removal: large beetles were more efficient than small ones and the percentage of removed dung increased with higher body mass heterogeneity. Tunnelers were more efficient than dwellers over both short and long time periods (one month and one year). Significant effects of dwellers were found only after one year. Moreover, our study showed that not including the body mass as an offset in the model resulted in sometimes different results, as the offset expresses dung removal independently of the body mass. This approach confirmed that body size is likely a pivotal factor controlling dung removal efficiency at multiple levels, from single species to overall dung beetle assemblages. Even though other specific traits should be examined, this study has begun to address the consequences of losing individuals with specific traits that are especially sensitive to perturbations.

Greenhouse gas emissions from dung pats vary with dung beetle species and with assemblage composition

Cattle farming is a major source of greenhouse gases (GHGs). Recent research suggests that GHG fluxes from dung pats could be affected by biotic interactions involving dung beetles. Whether and how these effects vary among beetle species and with assemblage composition is yet to be established. To examine the link between GHGs and different dung beetle species assemblages, we used a closed chamber system to measure fluxes of carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) from cattle dung pats. Targeting a total of four dung beetle species (a pat-dwelling species, a roller of dung balls, a large and a small tunnelling species), we ran six experimental treatments (four monospecific and two mixed) and two controls (one with dung but without beetles, and one with neither dung nor beetles). In this setting, the overall presence of beetles significantly affected the gas fluxes, but different species contributed unequally to GHG emissions. When compared to the control with dung, we detected an overall reduction in the total cumulative CO₂ flux from all treatments with beetles and a reduction in N₂O flux from the treatments with the three most abundant dung beetle species. These reductions can be seen as beneficial ecosystem services. Nonetheless, we also observed a disservice provided by the large tunneler, Copris lunaris, which significantly increased the CH₄ flux–an effect potentially traceable to the species’ nesting strategy involving the construction of large brood balls. When fluxes were summed into CO₂-equivalents across individual GHG compounds, dung with beetles proved to emit less GHGs than did beetle-free dung, with the mix of the three most abundant species providing the highest reduction (-32%). As the mix of multiple species proved the most effective in reducing CO₂-equivalents, the conservation of diverse assemblages of dung beetles emerges as a priority in agro-pastoral ecosystems.

Allometric relationships and character evolution in Onthophagus taurus (Coleoptera: Scarabaeidae)

Allometric relationships in primary sexual traits (male and female genitalia), secondary sexual traits (male horns and female carinae), and non-sex-related traits (external body traits, epipharynx traits) were studied in the dung beetle Onthophagus taurus. Model II regressions of log-transformed data were used to quantify relationships, with pronotum width as regressor and indicator of overall body size. Slopes (allometric values) for the different trait categories were significantly different, with secondary sexual traits showing the highest values (higher than 1.0), followed by external body traits (slightly lower than 1.00) and epipharynx traits (around 0.2). Primary sexual traits and body size were mostly uncorrelated and genital sizes were virtually constant. Allometries of secondary sexual traits were quite different in the two sexes: the relationship between male horn length and pronotum width was approximately sigmoidal, while that between female carina length and pronotum width was linear. External body traits had significantly higher allometric values in females than in males. Our results suggest that traits in the different categories are under different kinds of selection. Genital allometries can be explained on the basis of sexual selection by cryptic female choice or by the lock-and-key hypothesis. Among secondary sexual characters, male horn morphology seems to be mostly "environmentally" determined and sexual selection would affect only a component of the developmental mechanism of horn expression. External body characters are likely under natural selection, even though a few traits could be sex-related. Finally, in both sexes, internal epipharynx traits seem to be subject to the same selective pressure, probably because males and females use the same feeding niche. The constancy of genital sizes in O. taurus suggests that in developmental processes, more is invested in primary sexual traits (to produce genitalia of the proper size) than in secondary sexual or body traits. Males receiving low quantities of food may incur costs associated with a small horn or small body size, but do not incur costs associated with small genitalia. Females probably share the same developmental pattern.

Alpine bird distributions along elevation gradients: the consistency of climate and habitat effects across geographic regions

Many species have shown recent shifts in their distributions in response to climate change. Patterns in species occurrence or abundance along altitudinal gradients often serve as the basis for detecting such changes and assessing future sensitivity. Quantifying the distribution of species along altitudinal gradients acts as a fundamental basis for future studies on environmental change impacts, but in order for models of altitudinal distribution to have wide applicability, it is necessary to know the extent to which altitudinal trends in occurrence are consistent across geographically separated areas. This was assessed by fitting models of bird species occurrence across altitudinal gradients in relation to habitat and climate variables in two geographically separated alpine regions, Piedmont and Trentino. The ten species studied showed non-random altitudinal distributions which in most cases were consistent across regions in terms of pattern. Trends in relation to altitude and differences between regions could be explained mostly by habitat or a combination of habitat and climate variables. Variation partitioning showed that most variation explained by the models was attributable to habitat, or habitat and climate together, rather than climate alone or geographic region. The shape and position of the altitudinal distribution curve is important as it can be related to vulnerability where the available space is limited, i.e. where mountains are not of sufficient altitude for expansion. This study therefore suggests that incorporating habitat and climate variables should be sufficient to construct models with high transferability for many alpine species.

Identifying key conservation threats to Alpine birds through expert knowledge

Alpine biodiversity is subject to a range of increasing threats, but the scarcity of data for many taxa means that it is difficult to assess the level and likely future impact of a given threat. Expert opinion can be a useful tool to address knowledge gaps in the absence of adequate data. Experts with experience in Alpine ecology were approached to rank threat levels for 69 Alpine bird species over the next 50 years for the whole European Alps in relation to ten categories: land abandonment, climate change, renewable energy, fire, forestry practices, grazing practices, hunting, leisure, mining and urbanization. There was a high degree of concordance in ranking of perceived threats among experts for most threat categories. The major overall perceived threats to Alpine birds identified through expert knowledge were land abandonment, urbanization, leisure and forestry, although other perceived threats were ranked highly for particular species groups (renewable energy and hunting for raptors, hunting for gamebirds). For groups of species defined according to their breeding habitat, open habitat species and treeline species were perceived as the most threatened. A spatial risk assessment tool based on summed scores for the whole community showed threat levels were highest for bird communities of the northern and western Alps. Development of the approaches given in this paper, including addressing biases in the selection of experts and adopting a more detailed ranking procedure, could prove useful in the future in identifying future threats, and in carrying out risk assessments based on levels of threat to the whole bird community.

The impact of overgrazing on dung beetle diversity in the Italian Maritime Alps

Dung beetles (Coleoptera: Scarabaeidae) are undoubtedly the most typical and ecologically relevant insects of grazed alpine habitats because they provide valuable ecological services such as biological pest control and soil fertilization. Despite the great ecological contribution of these insects to pasture ecosystem functioning, little is known about their direct or indirect relationships with pastoral activities. The main aim of the study was to assess whether dung beetle diversity was influenced by different intensities of cattle grazing. Dung beetle communities of two adjacent alpine valleys within the Maritime Alps Natural Park (north-western Italian Alps), representing overgrazed and ungrazed pastures, were studied by pitfall trapping. A hierarchical design (three levels: valleys, transects, and replicates) was established for additive partitioning of γ-diversity and Indicator Species Analysis. Evenness and Shannon diversity were significantly higher at the ungrazed than at the overgrazed site because abundances were much more evenly distributed at the former than at the latter site (where one species was dominant over all the others). Dung beetle abundance and species richness of the overgrazed graminaceous pasture vegetation types were in most cases significantly lower than those of the ungrazed nongraminaceous vegetation type. In the additive partitioning of γ -diversity analysis relative to the whole study area, the randomization procedure indicated that the contribution of β to γ-diversity was significantly different from that expected by chance, suggesting that one or more environmental factors has intervened to change the partition of total diversity in the system considered. The analysis of the preferences and fidelity of species (Indicator Species Analysis) showed that only one species chose overgrazed pastures; all the others positively selected the ungrazed site, or the only ungrazed pasture vegetation type (Rumicetum alpini Beger) occurring at the overgrazed site. Results conformed to evidences that overgrazing represents a serious threat to the conservation of alpine dung beetles. To conserve local dung beetle assemblages, especially in protected areas, cattle overgrazing should be avoided. This does not mean, however, that pastoral activities are incompatible with biodiversity conservation. The contemporaneous presence of wild ungulates and low intensity extensive pastoral activities may be useful to preserve both local dung beetle assemblages and alpine pasture ecosystems.

Combination of geometric morphometric and genetic approaches applied to a debated taxonomical issue: the status of Onthophagus massai (Coleoptera, Scarabaeidae) as an endemic species vicarious to Onthophagus fracticornis in Sicily

The present study deals with the phenomenon of insular speciation and discusses, as a case study, the debated taxonomical issue of the status of Onthophagus massai (Coleoptera, Sarabaeidae) as an endemic species vicarious to Onthophagus fracticornis in Sicily. The authors investigated the differentiation patterns between an insular population belonging to the supposed species O. massai (collected in its locus typicus, Piano Battaglia) and three Italian O. fracticornis populations (collected along a N-S latitudinal gradient). These patterns are described and analysed using multiple approaches: the qualitative inspection of the microsculpture of elytral surfaces, considered a diagnostic character for O. massai identification; the comparison of horn static allometries, known to be a good indicator of divergence processes between closely related species or isolated populations of the same species; the comparison of the patterns of shape and size difference of the head, epipharynx and genitalia attained with a combination of traditional and geometric (landmark and semilandmark) morphometric methods; and, finally, the estimation of the genetic relationships between Sicilian and continental populations obtained by analysing cytochrome oxidase subunit 1 mitochondrial gene sequences. The integration of the results of these approaches indicates that there is not sufficient evidence to vindicate the species status for O. massai, which should more likely be considered a small-sized version of O. fracticornis (a possible case of insular dwarfism). However, the complex pattern of shape, size and genetic variation observed between the populations analysed hinted at the possibility that a diversification process is ongoing, but not only between insular and continental populations; each population showed a tendency to evolve as an evolutionarily independent unit.

Dung beetles as drivers of ecosystem multifunctionality: Are response and effect traits interwoven?

Rapid biodiversity loss has emphasized the need to understand how biodiversity affects the provisioning of ecological functions. Of particular interest are species and communities with versatile impacts on multiple parts of the environment, linking processes in the biosphere, lithosphere, and atmosphere to human interests in the anthroposphere (in this case, cattle farming). In this study, we examine the role of a specific group of insects - beetles feeding on cattle dung - on multiple ecological functions spanning these spheres (dung removal, soil nutrient content and greenhouse gas emissions). We ask whether the same traits which make species prone to extinction (i.e. response traits) may also affect their functional efficiency (as effect traits). To establish the link between response and effect traits, we first evaluated whether two traits (body mass and nesting strategy, the latter categorized as tunnelers or dwellers) affected the probability of a species being threatened. We then tested for a relationship between these traits and ecosystem functioning. Across Scandinavian dung beetle species, 75% of tunnelers and 30% of dwellers are classified as threatened. Hence, nesting strategy significantly affects the probability of a species being threatened, and constitutes a response trait. Effect traits varied with the ecological function investigated: density-specific dung removal was influenced by both nesting strategy and body mass, whereas methane emissions varied with body mass and nutrient recycling with nesting strategy. Our findings suggest that among Scandinavian dung beetles, nesting strategy is both a response and an effect trait, with tunnelers being more efficient in providing several ecological functions and also being more sensitive to extinction. Consequently, functionally important tunneler species have suffered disproportionate declines, and species not threatened today may be at risk of becoming so in the near future. This linkage between effect and response traits aggravates the consequences of ongoing biodiversity loss.