Sub-lingual oral fistulas in Sooty Terns (Onychoprion?fuscata)

Sub-lingual oral fistulas are a condition first reported in New Zealand Stitchbirds (Notiomystis cincta) in which a lesion develops on the periphery of the mandible in the oral cavity and a fistula develops through which the tongue protrudes. We report that it arises in another species, the Sooty Tern (Onychoprion fuscata), breeding on Ascension Island in the south Atlantic. We discovered five adults with oral fistulas out of a total of 13,664 adults and chicks ringed during 11 breeding seasons over 13 years. Compared with other threats to the Ascension breeding population of over 180,000 pairs of Sooty Terns, we report that oral fistulas are a minor threat to colony stability, especially because afflicted birds were incubating eggs. Nevertheless, our findings suggest that further investigations of whether the condition is sex-linked, of its pathogenesis, and of its causation would augment our knowledge of the biology of Sooty Terns; such information might also have conservation implications for our understanding of the condition in endangered Stitchbirds. We call upon ornithologists to report oral fistulas in other species, because it would seem unlikely that these are the only two species predisposed to the condition.     

Are there general patterns in plant defence against megaherbivores?

Field surveys were conducted to test whether plants deploy structural defences in ways that match the distribution of megaherbivores. In Western Australian scrublands, where adult plants are within the reach of megaherbivores, structural defences increased vertically and were deployed preferentially by adult plants. Conversely, in woodlands of Eastern Australia and California, where adult plants grow above the reach of megaherbivores, structural defences decreased vertically. Populations of closely‐related taxa on offshore islands exhibited significant reductions in defence in the absence of megaherbivores. The results also demonstrate that island plant taxa can evolve vertical changes in defence after colonizing continents, where they are exposed to megaherbivores. Overall, the results of the present study illustrate a complex array of spatial patterns in plant defence that match the distribution and foraging behaviour of large mammals. When interpreted alongside previous work demonstrating similar spatial patterns in other types of plant defence, the results may help to unify our understanding of how megaherbivores have shaped the evolution of plant form and function. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 38–48.     

Trunk spines of trees: a physical defence against bark removal and climbing by mammals?

Background and Aims The defensive role of spines has previously been related to leaves, young shoots and reproductive organs. However, some woody species harbour spines on their trunks where none of those organs are present. Several explanations are plausible: they could be (1) climbing aids, (2) remnants from defence of leaves or reproductive organs during an earlier development phase, or (3) an as-yet undescribed defence. Here we investigate whether they could play a role against either bark feeding or preventing climbing animals accessing food resources in the tree canopy.MethodsWe described 31 woody species with spines on their trunk, growing in a botanical garden, to test whether morphological strategies could be identified and suggest what could be their most likely function. As testing their function is difficult experimentally for large pools of species, we performed virtual experiments to evaluate the potential roles of trunk spines against bark removal and climbing animals of different sizes. We then compared for each species and their confamilial non-spiny species the nutritional profiles of leaf, bark and reproductive organs to test whether trunk spines were associated with a nutritious organ (more likely targeted by herbivores).Key ResultsWe identified four morphological syndromes of trunk spines. Two corresponded to already known functions (anchorage for lianas and crown defence against large ground mammals), and two strategies are newly described trait syndromes with traits suggesting a defence against bark feeding and climbing mammals. By simulation, we show how each strategy could translate into defence against debarking and prevent herbivores from climbing.ConclusionsWe identified trunk spine strategies and the criteria to classify them, their most likely function and the likely feeding mode and size of animal against which different trunk spine strategies may be effective. We discuss further perspectives for testing their function and their ecological significance.     

How effective were mangroves as a defence against the recent tsunami?

Whether or not mangroves function as buffers against tsunamis is the subject of in-depth research, the importance of which has been neglected or underestimated before the recent killer tsunami struck. Our preliminary post-tsunami surveys of Sri Lankan mangrove sites with different degrees of degradation indicate that human activity exacerbated the damage inflicted on the coastal zone by the tsunami.     

Integrin-mediated type IV secretion by Helicobacter: what makes it tick?

Helicobacter pylori (Hp) employs a multi-component type IV secretion system (T4SS) to secrete the effector protein CagA into the cytosol of infected host cells. A longstanding challenge has been to identify the host cell receptor(s) involved. Two recent studies have independently unveiled human β(1) integrin as the receptor but are divided over which T4SS proteins bind to β(1) integrin. Here we revisit the two models in light of previous findings and recent progress in the field. More concerted efforts are required to fully understand the complex T4SS mechanisms that underpin Hp pathogenesis.     

Fungal depsidones – an inducible or constitutive defence against herbivores in the lichen Lobaria pulmonaria?

Herbivore-deterrent depsidones in the epiphytic lichen Lobaria pulmonaria were quantified after a 104-day exposure to indigenous lichen-feeding mollusc communities in broadleaved deciduous forests in southeastern Norway. Controls and acetone-rinsed living thalli were transplanted under open and shaded tree canopies. Rinsed thalli had their depsidone concentration reduced to 36% of the pre-rinsing level, which is below the level needed to deter grazing molluscs. Grazing did not raise the concentration of depsidones beyond the level occurring in control to which molluscs had no access. Inducible responses were not detected in controls nor in acetone-rinsed thalli. Depsidone resynthesis was negligible in acetone-rinsed thalli regardless of grazing and/or light regimes. Our results suggest that C-based depsidones represent a constitutive type of herbivore defence in L. pulmonaria. A constitutive defence is probably an advantage for stress-tolerant slow-growing lichens inhabiting habitats with a constant presence of generalist invertebrate herbivores.     

Are Morphometrics Sufficient for Estimating Age of Pre-Fledging Birds in the Field? A Test Using Common Terns (Sterna hirundo)

Age is a key component of fitness, affecting survival and reproductive capacities. Where it is not possible to study known individuals from birth, morphometrics (predominantly patterns of plumage development for birds) are most often used to estimate age. Although criteria for age estimations exist for many species, the degree to which these criteria improve the precision of estimates remains to be tested, restricting their widespread acceptance. We develop a photographic tool for estimating ages of Common Tern (Sterna hirundo) chicks and test it using 100 human observers of varying prior experience across four breeding colonies (three North American sites and one European site) and under controlled laboratory conditions. We followed the design approach of other morphometric tools, expanding it to create a user-friendly guide (divided into six age groupings). The majority (86%) of observers improved in chick-aging accuracy when using the tool by an average of 20.1% (±1.4 SE) and correctly estimated 60.3% (±1.4) of chick ages. This was similar to the intrinsic aging ability of our best field observer (63.3%). Observers with limited experience showed the greatest increases in chick-aging accuracy over experienced observers who likely had established a method for estimating chick ages prior to using the tool. Even the best observers only correctly estimated ages of chicks 62.9% (±2.8) of the time in the field and 84.0% (±2.9) of the time in the lab when using the tool and typically underestimated ages. This indicates that developmental variation between individual chicks can prevent completely reliable age estimates and corroborates the few existing data that suggest that morphometric criteria fail to achieve robust levels of accuracy and may introduce error into studies that rely on them. We conclude that novel approaches for estimating age, not only morphometric criteria, must be pursued.     

Are ruminal bacteria protected against environmental stress by plant antioxidants?

AIMS: To investigate the activity response of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSHPx) of the rumen bacterium Streptococcus bovis following exposure to mercury(II) chloride (HgCl(2) in the presence of plant antioxidants. METHODS AND RESULTS: Streptococcus bovis was grown with 0 or 5 microg ml(-1) of HgCl(2) alone or together with antioxidant substances (AOS): seleno-l-methionine (Se), alpha-tocopherol (alpha toc), beta-carotene (beta car), melatonin (mel). The activities of SOD and GHPx were estimated in supernatants of disrupted bacterial cells. A significant decrease in the Strep. bovis SOD activity in the presence of HgCl(2) and tested AOS, except mel, was observed. The GSHPx activity of Strep. bovis was under the same cultivation conditions nonsignificantly changed and a significant decrease in the GSHPx activity was recorded only in the presence of beta car. CONCLUSIONS: The positive effect of Se, alpha toc and beta car on the elimination of environmental stress, evoked by mercury, in ruminal bacterium Strep. bovis in vitro was documented. SIGNIFICANCE AND IMPACT OF THE STUDY: The potential role of plant antioxidants in elimination of the environmental stress of ruminal bacteria evoked by heavy metals is discussed.     

Did fleshy fruit pulp evolve as a defence against seed loss rather than as a dispersal mechanism?

Relatively few studies have examined the evolution of the mutualism between endozoochorous plants and seed dispersers. Most seed dispersal studies are ecological and examine the role of fruit pulp in promoting seed dispersal. This interaction is often assumed to have originated due to selection stemming from seed dispersers. Here I suggest a "defence scenario" wherein fleshy fruits originated as mechanisms to defend seeds and secondarily became structures to promote seed dispersal. I suggest that frugivory followed from herbivores that specialized on consuming seed defensive tissues and that enhanced seed dispersal was initially a consequence of seed defence. The proposed defence scenario is not posited as an explanation for the sequence that led to all modern frugivores. However, it is suggested that seed predation was the initial source of selection that led to fleshy fruits; the necessary precursor to frugivory. Support is described from the fossil record and from modern structures and interactions. Testable predictions are made in hope that greater interest will be focused on the defensive role of fleshy fruit pulp both in modern interactions and historically.     

Nutritional enhancement of leaves by a psyllid through senescence-like processes: insect manipulation or plant defence?

Some herbivores can modify the physiology of plant modules to meet their nutritional requirements. Induction of premature leaf senescence could benefit herbivores since it is associated with the mobilisation of nutrients. We compared the effects of nymphal feeding by Cardiaspina near densitexta on Eucalyptus moluccana with endogenous processes associated with senescence to assess the relative merits of an insect manipulation or plant defence interpretation of responses. Evidence supporting insect manipulation included increased size of fourth and fifth instar nymphs (in the latter the effect was restricted to forewing pad length of females) on leaves supporting high numbers of conspecifics and feeding preventing leaf necrosis. Intra-specific competition negated greater performance at very high densities. High and very high abundances of nymphs were associated with increased concentrations of amino acid N but only very high abundances of nymphs tended to be associated with increased concentrations of six essential amino acids. Contrary to the insect manipulation interpretation, feeding by very high abundances of nymphs was associated with significant reductions in chlorophyll, carotenoids and anthocyanins. Evidence supporting plant defence included the severity of chlorosis increasing with the abundance of nymphs. Leaf reddening did not develop because ambient conditions associated with photoinhibition (high irradiance and low temperature) were not experienced by leaves with chlorotic lesions. Leaf reddening (from anthocyanins) alone is not expected to adversely affect nymphal survival; only leaf necrosis would kill nymphs. For senescence-inducing psyllids, nutritional enhancement does not fit neatly into either an insect manipulation or plant defence interpretation.     

Cabbage (Brassica oleracea var. Capitata) fails to show wound-induced defence against a specialist and a generalist herbivore?

This paper presents tests of a model of wound-induced defence in herbaceous plants. Many studies have reported both chemical changes in leaves and changes in the behaviour and/or physiology of herbivores as a result of wounding leaves. These studies and others have led to the development of various models to explain wound-induced effects both in terms of plant response and herbivore behaviour. The model under test was proposed by Edwards and Wratten (1987) and predicts that wounding a plant will cause herbivores (1) to take more meals of a smaller size and/or consume less foliage overall (2) grow more slowly and (3) be more mobile. These predictions were tested in cabbage Brassica oleracea L. var. Capitata cv. Pixie with Pieris brassicae L. (Lepidoptera: Pieridae) as a herbivore specialising on cabbage, and Spodoptera littoralis Boisd. (Lepidoptera: Noctuidae) as a generalist herbivore. Both insects showed some reduction in consumption of leaves from upper parts of the plant, but no change in meal size. There were no effects on the growth or mobility of either species as a result of wounding foliage. These results are discussed in relation to the predictions of the model.     

Trade‐offs in oviposition choice? Food‐dependent performance and defence against predators of a herbivorous sawfly

The sawfly Athalia rosae L. (Hymenoptera: Tenthredinidae) is a feeding specialist on plant species of the Brassicaceae, which are characterised by secondary metabolites, called glucosinolates. The larvae can take up the respective glucosinolates of their hosts and concentrate them in their haemolymph to protect themselves against predators. Oviposition preferences of naïve females were tested for three species, Sinapis alba L., Brassica nigra (L.) Koch, and Barbarea stricta Andrz., and were related to larval performance patterns. Larvae were reared on either one of these plants and it was investigated how host‐plant quality influences both the developmental times and growth of larvae (bottom‐up) and the defence efficiency against predators (top‐down). Innately, almost all adult females avoided B. stricta for oviposition and clearly preferred B. nigra over S. alba. On average, larvae developed best on B. nigra. Female larvae reached similar final body masses on all host‐plant species, but males reared on S. alba were slightly lighter. The developmental time of larvae reared on B. stricta was significantly longer than on the other two plants. However, larvae reared on B. stricta were best protected against the predatory wasp Polistes dominulus Christ (Hymenoptera: Vespidae). The wasps rejected these larvae most often, while they attacked larvae reared on S. alba most frequently. Thus, larvae feeding on B. stricta theoretically run a higher risk of predation due to a prolonged developmental time, but in practice they are better protected against predators. Overall, oviposition preferences of A. rosae seem to be more influenced by bottom‐up effects on larval performance than by top‐down effects.     

Targeting of histamine producing cells by EGCG: a green dart against inflammation?

The human body is made of some 250 different cell types. From them, only a small subset of cell types is able to produce histamine. They include some neurons, enterochromaffin-like cells, gastrin-containing cells, mast cells, basophils, and monocytes/macrophages, among others. In spite of the reduced number of these histamine-producing cell types, they are involved in very different physiological processes. Their deregulation is related with many highly prevalent, as well as emergent and rare diseases, mainly those described as inflammation-dependent pathologies, including mastocytosis, basophilic leukemia, gastric ulcer, Crohn disease, and other inflammatory bowel diseases. Furthermore, oncogenic transformation switches some non-histamine-producing cells to a histamine producing phenotype. This is the case of melanoma, small cell lung carcinoma, and several types of neuroendocrine tumors. The bioactive compound epigallocatechin-3-gallate (EGCG), a major component of green tea, has been shown to target histamine-producing cells producing great alterations in their behavior, with relevant effects on their proliferative potential, as well as their adhesion, migration, and invasion potentials. In fact, EGCG has been shown to have potent anti-inflammatory, anti-tumoral, and anti-angiogenic effects and to be a potent inhibitor of the histamine-producing enzyme, histidine decarboxylase. Herein, we review the many specific effects of EGCG on concrete molecular targets of histamine-producing cells and discuss the relevance of these data to support the potential therapeutic interest of this compound to treat inflammation-dependent diseases.     

Can a pairwise contact potential stabilize native protein folds against decoys obtained by threading?

We present a method to derive contact energy parameters from large sets of proteins. The basic requirement on which our method is based is that for each protein in the database the native contact map has lower energy than all its decoy conformations that are obtained by threading. Only when this condition is satisfied one can use the proposed energy function for fold identification. Such a set of parameters can be found (by perceptron learning) if Mp, the number of proteins in the database, is not too large. Other aspects that influence the existence of such a solution are the exact definition of contact and the value of the critical distance Rc, below which two residues are considered to be in contact. Another important novel feature of our approach is its ability to determine whether an energy function of some suitable proposed form can or cannot be parameterized in a way that satisfies our basic requirement. As a demonstration of this, we determine the region in the (Rc, Mp) plane in which the problem is solvable, i.e., we can find a set of contact parameters that stabilize simultaneously all the native conformations. We show that for large enough databases the contact approximation to the energy cannot stabilize all the native folds even against the decoys obtained by gapless threading.     

Facilitation of tree saplings by nurse plants: Microhabitat amelioration or protection against herbivores?

Question: Positive interactions are predicted to be common in communities developing under high physical stress or high herbivory pressure due to neighbour amelioration of limiting physical and consumer stresses, respectively. However, when both stress sources meet in the same community, the relative importance of the two facilitation mechanisms is poorly understood. We ask: What is the relative importance of abiotic vs. biotic mechanisms of facilitation of tree saplings by shrubs in Mediterranean mountain forests? Location: Sierra Nevada, SE Spain (1800–1850 m a.s.l.) Methods: Saplings of four tree taxa (Acer opalus ssp. grana‐tense, Quercus ilex, Pinus nigra ssp. salzmanii and P. sylvestris var. nevadensis) were planted following a 2 × 2 factorial design: two levels of herbivory (control and ungulate exclusion) and two microhabitats (under shrubs and in open areas). Sapling survival and growth were monitored for five years. Results: Shrubs had positive effects on sapling survival both in control and ungulate excluded plots. This effect was species‐specific, with shrubs increasing the survival of Acer opalus and Quercus ilex three and twofold, respectively, but having a minor effect on the Pinus species. Herbivory damage was also species‐specific, being much higher for Acer opalus than for any other species. Shrubs did not protect saplings of any species against ungulates. Thus, all Acer saplings (the most damaged species) suffered herbivory outside the exclosures, which largely reduced sapling height. Conclusions: Protection from abiotic stress (summer drought and winter frost) was much more relevant than protection from biotic stress (herbivory). However, we propose that the final balance between the two mechanisms can be expected to vary strongly between sites, depending on the relative magnitude of the different sources of stress and the intrinsic traits (e.g. palatability) of the species interacting.     

Signal transduction induced by activated protein C: no role in protection against sepsis?

The anticoagulant activated protein C (APC) is historically known as a risk factor for venous thrombosis. However, after the positive results of the protein C worldwide evaluation in severe sepsis (PROWESS) trial, which showed that APC was the first drug that considerably reduced sepsis-related mortality, APC is considered a pleiotropic protein with both anticoagulant and anti-inflammatory properties. In addition, in vitro studies have suggested that APC-induced intracellular signal transduction is a potential mechanism by which APC might be protective against sepsis. Recently, however, the efficacy of APC in sepsis has been argued, and also the extent to which the signal transduction capacity of APC contributes to its pro-survival effects is debated. Here, we review the role of APC in the body natural defense against sepsis and discuss the mechanism by which APC might act at a cellular level.