Development and testing of an optimized method for DNA-based identification of jaguar (<Emphasis Type="Italic">Panthera onca</Emphasis>) and puma (<Emphasis Type="Italic">Puma concolor</Emphasis>) faecal samples for use in ecological and genetic studies

The elusive nature and endangered status of most carnivore species imply that efficient approaches for their non-invasive sampling are required to allow for genetic and ecological studies. Faecal samples are a major potential source of information, and reliable approaches are needed to foster their application in this field, particularly in areas where few studies have been conducted. A major obstacle to the reliable use of faecal samples is their uncertain species-level identification in the field, an issue that can be addressed with DNA-based assays. In this study we describe a sequence-based approach that efficiently distinguishes jaguar versus puma scats, and that presents several desirable properties: (1) considerably high amplification and sequencing rates; (2) multiple diagnostic sites reliably differentiating the two focal species; (3) high information content that allows for future application in other carnivores; (4) no evidence of amplification of prey DNA; and (5) no evidence of amplification of a nuclear mitochondrial DNA insertion known to occur in the jaguar. We demonstrate the reliability and usefulness of this approach by evaluating 55 field-collected samples from four locations in the highly fragmented Atlantic Forest biome of Brazil and Argentina, and document the presence of one or both of these endangered felids in each of these areas.     

Habitat level determinants of emergent macrophyte occurrence,extension and change in two large boreal lakes in Finland

Historical (1947–1950) and present day (1998–2000) aerial photograph data of aquatic vegetation were combined with soil, land use and habitat morphology variables in two lakes, oligotrophic L. Näsijärvi (256 km²) and eutrophic L. Pyhäjärvi (122 km²), with regulated water levels in southern Finland. Multivariate GLM analyses were used to examine the determining factors of occurrence and horizontal extension of vegetation, occurrence of common reed (Phragmites australis) and water horsetail (Equisetum fluviatile) and the vegetation change in 474 sites. Despite differences in geography and water level regulation between the lakes, congruent trends were identified. The vegetation occurrence in both lakes had a positive response to clay soils and incoming nutrients and a negative response to housing and shore slope. Moraine soils, housing and shore slope had a negative effect on horizontal extension of vegetation in both lakes. The occurrence of P. australis was controlled by a negative response to moraine and the occurrence of E. fluviatile to slope in both lakes. The vegetation change in both lakes was characterized by a negative response to housing and slope.     

Light- and seasonal-induced plasticity in leaf morphology, N partitioning and photosynthetic capacity of two temperate deciduous species

Processes involved in leaf photosynthetic acclimation to light and throughout the growing season were investigated in two hardwood species (Acer saccharum and Betula alleghaniensis), which differed in their level of shade-tolerance. For both species, variation in traits related to (i) leaf morphology (LMA, leaf mass:area ratio), (ii) leaf N content (N_A, leaf nitrogen content on an area basis and N_M, N concentration in leaf dry mass), (iii) leaf N partitioning among photosynthetic functions (P_r, N allocated to Rubisco, and P_b, N allocated to bioenergetics), and (iv) leaf photosynthetic capacity (V_cmax, maximal carboxylation rates, and J_max, maximal light-driven electron flow) were assessed at three different times during the growing season (early, mid- and late summer) and under four contrasting light regimes (40, 17, 6 and 2% of full sunlight). For both species, light-driven variation in most traits was greater than their seasonally driven variation. Furthermore, results showed for both species the pre-eminence of LMA changes in the light-driven acclimation of N_A. Importance of N_M to variation in N_A was restricted to seasonal acclimation, especially for the less shade-tolerant species, B. alleghaniensis. Similarly, for both species, light-driven acclimation of leaf photosynthetic capacities was tightly related to variation in N_A, which was related to LMA changes. However, variation in P_r and P_b better explained seasonally driven variation in V_cmax and J_max, specifically under lower light levels, where N_A was low. Thus, the great variability observed for leaf activity in response to contrasting light environments was related to efficient morphological adjustments, regardless of species level of shade-tolerance. Finally, physiological adjustments were mainly involved in fine-scale changes observed during seasonally driven acclimation of leaves, when LMA was constrained to a slight range of variation.     

Novel in vitro and in vivo models to study central nervous system infections due to Acanthamoeba spp.

Acanthamoeba granulomatous encephalitis is a serious human infection with fatal consequences. The most distressing aspect of Acanthamoeba granulomatous encephalitis is the limited improvement in mortality. The underlying neurobiology is at present not well understood and treatment options are often of limited efficacy. There is therefore a real need to obtain more knowledge regarding the pathogenesis and pathophysiology of Acanthamoeba granulomatous encephalitis and to develop new chemotherapeutic approaches. However, the difficulties in using mammalian models to study this infection have hindered our search for therapeutic interventions. Recent availability of the blood-brain barrier, in vitro and use of locust as an in vivo model will undoubtedly allow us to investigate disease pathogenesis, mechanisms of parasite traversal across the blood-brain barrier and new drug therapies. It is argued that the models described here can offer several advantages in terms of speed, cost, technical convenience, and ethical acceptance. Furthermore, they are extremely valuable tools to discriminate molecules participating from both sides of the host-parasite interaction and will generate potentially useful leads in the identification of new potential drugs, as well as testing drug toxicity.     

Ventilatory and cardiovascular modulation associated with burying behaviour in two sympatric crab species, Cancer magister and Cancer productus

Physiological parameters associated with burying were investigated in the Dungeness crab, Cancer magister, and the red rock crab, Cancer productus. Ventilation frequency of the branchial chambers increased while the crabs were burying, this was associated with the greater oxygen demand of the tissues. The number of ventilatory reversals in C. magister increased in number as well as in duration and magnitude when the crabs were buried, which functioned to clear the branchial chambers of sediment. In contrast, the number of ventilatory reversals in C. productus decreased. On the surface of the sand, cardiac parameters (heart rate, stroke volume, cardiac output) of both species remained stable. During the burial process, there was a large increase in cardiac output which was afforded primarily by an increased stroke volume of the heart. Once buried, cardiac output declined in both species; this was due to a decrease in stroke volume in C. productus, but a decreased heart rate in C. magister. There were also differences in haemolymph flows through each arterial system. During the burying process, both species increased haemolymph flow to the muscles of the limbs via the sternal artery. Once buried haemolymph flows to the limbs decreased, and increased flow to eyestalks and antennae via the anterior aorta occurred. Perfusion of the digestive organs via the anterolateral and hepatic arteries did not change when the crabs were buried. There was an increase in flow through the posterior aorta, of C. magister, but flow through this artery did not change in C. productus. Periods of spontaneous cardiac arrest were observed in both species while resting on the surface. These increased in duration in C. productus when buried, but there was no change in C. magister. Changes in ventilatory and cardiac variables were closely linked on the surface, but tended to uncouple when the animals were buried. The physiological responses of C. magister resembled those of true sand-dwelling crabs, whereas the responses of C. productus paralleled those of crabs that only bury occasionally in the substrate. Although these two species often occur sympatrically, they employ different physiological mechanisms when buried in the sediment.     

DEBtox theory and matrix population models as helpful tools in understanding the interaction between toxic cyanobacteria and zooplankton

Bioassays were performed to find out how field samples of the toxic cyanobacteria Microcystis aeruginosa affect Moina micrura, a cladoceran found in the tropical Jacarepagua Lagoon (Rio de Janeiro, Brazil). The DEBtox (Dynamic Energy Budget theory applied to toxicity data) approach has been proposed for use in analysing chronic toxicity tests as an alternative to calculating the usual safety parameters (NOEC, ECx). DEBtox theory deals with the energy balance between physiological processes (assimilation, maintenance, growth and reproduction), and it can be used to investigate and compare various hypotheses concerning the mechanism of action of a toxicant. Even though the DEBtox framework was designed for standard toxicity bioassays carried out with standard species (fish, daphnids), we applied the growth and reproduction models to M. micrura, by adapting the data available using a weight-length allometric relationship. Our modelling approach appeared to be very relevant at the individual level, and confirmed previous conclusions about the toxic mechanism. In our study we also wanted to assess the toxic effects at the population level, which is a more relevant endpoint in risk assessment. We therefore incorporated both lethal and sublethal toxic effects in a matrix population model used to calculate the finite rate of population change as a continuous function of the exposure concentration. Alongside this calculation, we constructed a confidence band to predict the critical exposure concentration for population health. Finally, we discuss our findings with regard to the prospects for further refining the analysis of ecotoxicological data.     

Metal biosorption by two cyanobacterial mats in relation to pH, biomass concentration, pretreatment and reuse

The pH-dependent metal sorption by Oscillatoria- and Phormidium-dominated mats was effectively expressed by the Hill function. The estimated Hill functions can fruitfully predict the amount of metal sorbed at a particular initial pH. Pretreatment of biomass with 0.1 mmol L⁻¹ HCl was more effective than pretreatment with CaCl₂, HNO₃, NaOH, and SDS in enhancing metal sorption ability of the biomass. Desorption of metal ions in the presence of 100 mmol L⁻¹ HCl from metal-loaded mat biomass was completed within 1 h. After six cycles of metal sorption/desorption, sorption decreased by 6-15%. Only 6% and 11% of the biomass derived from the Oscillatoria sp.- and Phormidium sp.-dominated mats was lost during the cycling. The cyanobacterial mats seem to have better potential than several biomass types for use in metal sorption from wastewaters as they are ubiquitous, self-immobilized, and have good reusability.     

Chimpanzees' choices of prey between two sympatric species ofMacrotermes in the Campo Animal Reserve,Cameroon

Details are presented relating to chimpanzees' choices between two sympatric species of termites,Macrotermes lillijeborgi andM. vitrialatus, as food in the Campo Animal Reserve, southwest Cameroon, West Africa. An attempt was made to determine the various factors that affected such choices. The two species of termites seemed to have almost the same value in terms of ecological factors. However, chimpanzees fed almost exclusivelyonM. lillijeborgi, using digging sticks and fisching probes, during the study period which extended from the end of August to the middle of January, with their feeding activity showing peak at the beginning of the rainy season. By contrast,M. vitrialatus was rarely eaten in spite of the ease with which such prey could be obtained, namely, by desctruction of termite mounds by hand, without the need for tools. The reason that the chimpanzees discriminated between the two species of termite cannot be explained in terms of ecological factors such as size of prey, seasonal differences in termite activity, etc. Sticks used as tools were fairly uniform in size and character, mainly because of physical constraints related to the structure of termite mounds, and the brush-like ends of sticks seemed to be incidentaly byproducts of the chimpanzee's choice of plant species. Ecological factors could provide chimpanzees with a basis for the use of some kind of tool and help them modify it, while other factors, for example, something akin to leisure or the chimpanzee's interest in use of a tool, could provide an opportunity for inventing some tool-using behavior or for maintaining such behavior. These different factors, not being exclusive of one another, might affect the invention and maintenance of tool using-behavior at different phases. It is possible that chimpanzee's choice of prey may not always be the most efficient or appropriate in a given ecological situation.     

Lutzomyia vectors for cutaneous leishmaniasis in Southern Brazil: ecological niche models,predicted geographic distributions,and climate change effects

Geographic and ecological distributions of three Lutzomyia sand flies that are cutaneous leishmaniasis vectors in South America were analysed using ecological niche modelling. This new tool provides a large-scale perspective on species' geographic distributions, ecological and historical factors determining them, and their potential for change with expected environmental changes. As a first step, the ability of this technique to predict geographic distributions of the three species was tested statistically using two subsampling techniques: a random-selection technique that simulates 50% data density, and a quadrant-based technique that challenges the method to predict into broad unsampled regions. Predictivity under both test schemes was highly statistically significant. Visualisation of ecological niches provided insights into the ecological basis for distributional differences among species. Projections of potential geographic distributions across scenarios of global climate change suggested that only Lutzomyia whitmani is likely to be experiencing dramatic improvements in conditions in south-eastern Brazil, where cutaneous leishmaniasis appears to be re-emerging; Lutzomyia intermedia and Lutzomyia migonei may be seeing more subtle improvements in climatic conditions, but the implications are not straightforward. More generally, this technique offers the possibility of new views into the distributional ecology of disease, vector, and reservoir species.     

夜间增温和施肥对川西亚高山针叶林两种树苗根际效应的影响

开展植物根际效应对全球变化响应的研究是深入认识根际微生态系统中植物根系与土壤微生物相互作用过程及机制的关键。以川西亚高山针叶林两种主要树种幼苗--云杉(Picea asperata)和岷江冷杉(Abies faxoniana)为研究材料,采用红外辐射模拟增温和外施NH₄NO₃氮肥的方法,研究了夜间增温和施肥对两种幼苗根际效应的影响。结果表明:红外辐射增温导致气温增加了1.62 ℃,土壤5 cm和10 cm层月均温度显著增加了2.89 ℃和3.10℃。增温和施肥处理对两种幼苗不同参数根际效应的影响各不相同,表现为不同程度的正根际效应、负根际效应或者无影响。增温使云杉幼苗根际与非根际土SMB-C含量均显著增加(分别为42.28%和31.02%),非根际土有机碳含量降低了7.03%;而增温对两种幼苗土壤肥力因素根际效应的影响总体并不显著,增温仅对云杉全氮有显著的负根际效应(79.43%),而岷江冷杉通过根际土全氮和SMB-N含量的增加,其根际效应大小在增温处理下显著增强。施肥处理和两因子的联合作用显著提高了两种幼苗的NO^-₃-N、NH⁺₄-N和云杉非根际土SMB-N含量,并使岷江冷杉NH⁺₄-N表现出正根际效应,而云杉SMB-N表现出明显的负根际效应(120.80%和253.06%)。这种响应差异可能与不同植物种类地下碳分配及其植物根系所吸收的养分有关,从而赋予了不同植物种类在未来全球变化背景下可能具有不同的适应力和竞争优势,并进一步对亚高山针叶林地下过程及其早期更新产生潜在影响。     

Mesorhizobial strains nodulating Anagyris latifolia and Lotus berthelotii in Tamadaya ravine (Tenerife, Canary Islands) are two symbiovars of the same species, Mesorhizobium tamadayense sp. nov

Barranco de Tamadaya is a deep ravine located in southern Tenerife, which is included within a protected area where several endemic plants grow. Among them, two legumes are catalogued as critically endangered, Anagyris latifolia and Lotus berthelotii. Rhizobial strains isolated from their root nodules grown in soil samples from this ravine harboured symbiotic genes belonging to two distant symbiovars, but they shared identical 16S rRNA gene sequences (rrs). The phylogeny based on the rrs sequences placed these isolates in a separate subbranch that did not include any of the currently recognised Mesorhizobium species, but the resolution of the ribosomal tree did not permit further taxonomic conclusions. Nevertheless, multilocus sequence analysis (MLSA) of four housekeeping genes (atpD, recA, glnII and dnaK) and the rrs gene generated a highly supported Bayesian phylogeny, identifying these isolates as a new Mesorhizobium lineage. DNA-DNA hybridisation homology percentages were lower than 30% compared to type strains of the closest related species, and supported the phylogenetic data. Phenotypic characterisation also distinguished this lineage from the other closest Mesorhizobium species. The polyphasic approach thus confirmed that the isolates represented a novel species for which we propose the name Mesorhizobium tamadayense sp. nov. The type strain is Ala-3(T) (CECT 8040(T), LMG 26736(T)).     

Reckless males, rational females: dynamic trade-off between food and shelter in the marine isopod Idotea balthica

Habitat choice of herbivores is expected to be a resolution of a trade-off between food and shelter. The resolution of this trade-off may, however, be dynamic within a species because distinct phenotypes may value these factors differently and the value may vary temporally. We studied this hypothesis in the marine herbivore Idotea balthica (Isopoda), by simultaneously manipulating both food and shelter, and investigated whether the resolution of the trade-off differed between sexes, colour morphs and day and night (i.e. high and low predation risk). Isopods chose between exposing and concealing backgrounds in which the quantity or quality of food varied. When choosing between the backgrounds in the absence of food, females preferred the concealment more than males did. However, in a trade-off situation the isopods traded shelter for food, and females more so than males. Thus, males' lower preference for the shelter was not counterbalanced by a stronger preference for food. The microhabitat use also differed between night and day showing adaptation to diurnally fluctuating predation risk. We suggest that microhabitat utilization of females is more strongly tied to variation in risk and resources than that of males, for whom other factors, such as seeking mates, may be more important.     

Mutations in orbit/mast reveal that the central spindle is comprised of two microtubule populations, those that initiate cleavage and those that propagate furrow ingression

We address the relative roles of astral and central spindle microtubules (MTs) in cytokinesis of Drosophila melanogaster primary spermatocytes. Time-lapse imaging studies reveal that the central spindle is comprised of two MT populations, "interior" central spindle MTs found within the spindle envelope and "peripheral" astral MTs that probe the cytoplasm and initiate cleavage furrows where they contact the cortex and form overlapping bundles. The MT-associated protein Orbit/Mast/CLASP concentrates on interior rather than peripheral central spindle MTs. Interior MTs are preferentially affected in hypomorphic orbit mutants, and consequently the interior central spindle fails to form or is unstable. In contrast, peripheral MTs still probe the cortex and form regions of overlap that recruit the Pav-KLP motor and Aurora B kinase. orbit mutants have disorganized or incomplete anillin and actin rings, and although cleavage furrows initiate, they ultimately regress. Our work identifies a new function for Orbit/Mast/CLASP and identifies a novel MT population involved in cleavage furrow initiation.