Involvement of lectin pathway activation in the complement killing of Giardia intestinalis

Giardia intestinalis (syn. G. lamblia, G. duodenalis) is a flagellated unicellular eukaryotic microorganism that commonly causes diarrheal disease throughout the world. In humans, the clinical effects of Giardia infection range from the asymptomatic carrier state to a severe malabsorption syndrome possibly due to different virulence of the Giardia strain, the number of cysts ingested, the age of the host, and the state of the host immune system at the time of infection.The question about how G. intestinalis is controlled by the organism remains unanswered. Here, we investigated the role of the complement system and in particular, the lectin pathway during Giardia infections. We present the first evidence that G. intestinalis activate the complement lectin pathway and in doing so participate in eradication of the parasite. We detected rapid binding of mannan-binding lectin, H-ficolin and L-ficolin to the surface of G. intestinalis trophozoites and normal human serum depleted of these molecules failed to kill the parasites. Our finding provides insight into the role of lectin pathway in the control of G. intestinalis and about the nature of surface components of parasite.     

Candida albicans PEP12 Is Required for Biofilm Integrity and In Vivo Virulence

To investigate the role of the prevacuolar secretion pathway in biofilm formation and virulence in Candida albicans, we cloned and analyzed the C. albicans homolog of the Saccharomyces cerevisiae prevacuolar trafficking gene PEP12. C. albicans PEP12 encodes a deduced t-SNARE that is 28% identical to S. cerevisiae Pep12p, and plasmids bearing C. albicans PEP12 complemented the abnormal vacuolar morphology and temperature-sensitive growth of an S. cerevisiae pep12 null mutant. The C. albicans pep12 Δ null mutant was defective in endocytosis and vacuolar acidification and accumulated 40- to 60-nm cytoplasmic vesicles near the plasma membrane. Secretory defects included increased extracellular proteolytic activity and absent lipolytic activity. The pep12Δ null mutant was more sensitive to cell wall stresses and antifungal agents than the isogenic complemented strain or the control strain DAY185. Notably, the biofilm formed by the pep12Δ mutant was reduced in overall mass and fragmented completely upon the slightest disturbance. The pep12Δ mutant was markedly reduced in virulence in an in vitro macrophage infection model and an in vivo mouse model of disseminated candidiasis. These results suggest that C. albicans PEP12 plays a key role in biofilm integrity and in vivo virulence.In Saccharomyces cerevisiae, distinct secreted marker proteins are trafficked differentially through a prevacuolar compartment (PVC) prior to exocytosis (14). Furthermore, prevacuolar protein sorting genes play an important role in cargo transport in the prevacuolar branch of the exocytic pathway in S. cerevisiae (13, 15). By isolating dense- and light-vesicle populations in S. cerevisiae vps1 sec6-4, vps4 sec6-4, and pep12 sec6-4 mutants, it was observed that mutants blocked in this prevacuolar pathway missort marker proteins that are normally found in high-density post-Golgi compartment vesicles into low-density vesicles (15). Gurunathan et al. (13) also demonstrated these findings for vps1 and pep12 mutants with a late secretory mutant (snc1) background similar to that of the sec6-4 strains. These results indicate that some exocytic cargo, including the conditionally regulated soluble secretory proteins invertase and acid phosphatase, are differentially sorted through a PVC prior to exocytosis in the model yeast S. cerevisiae.To study the prevacuolar branch of exocytosis in Candida albicans and its role in virulence, we have previously cloned and analyzed the C. albicans prevacuolar trafficking genes VPS1 and VPS4. We demonstrated that C. albicans VPS4 is required for extracellular secretion of Sap2p and Sap4-6p and for virulence in an in vivo model of disseminated candidiasis (19, 20). C. albicans VPS1 is required for Sap2p secretion and biofilm formation (4). Interestingly, although the C. albicans null mutant lacking VPS4 forms a biofilm that is denser than that formed by the isogenic reintegrant strain, the conditional mutant lacking VPS1 expression forms a patchy biofilm of reduced density (4, 34). Thus, it appears that interference with normal prevacuolar trafficking affects both the secretion of virulence-associated proteins and biofilm formation.S. cerevisiae PEP12 encodes a 288-amino-acid syntaxin which regulates docking of Golgi compartment-derived transport vesicles at the PVC (3). Pep12p interacts with the v-SNARE Vti1p, and overexpression of Pep12p suppresses extracellular missorting of carboxypeptidase in the vti1 mutant (37). The S. cerevisiae pep12 null mutant displays a temperature-sensitive growth defect and is characterized by an enlarged vacuole with morphology defined as class D (3). A search of the C. albicans genome database identified a structural homolog of S. cerevisiae PEP12. Thus, the experiments described below were designed to determine whether the C. albicans PEP12 homolog is functionally homologous to S. cerevisiae PEP12 and to investigate its role in secretion, biofilm formation, and virulence.     

Air-borne fungi in the air of Barcelona (Spain). III. The genus Aspergillus link

During a survey on the presence of species of the genusAspergillus in the air of the city of Barcelona (Spain), the following species were identified:Aspergillus flavus Link,A. niger van Tieghem,A. fumigatus Fresenius,A. clavatus Desmazières,A. terreus Thorn,A. chevalieri (Mang.) Thomet Church,A. niveus Bloch, emend. Thomet Church,A. ochraceus Wilhelm,A. versicolor (Vuillemin) Tiraboschi, andA. amstelodami (Mang.) Churchet Thom.     

Disturbance and Seasonal Dynamics of Mycorrhizae in a Tropical Deciduous Forest in Mexico1

Mycorrhizal fungi were sampled in a deciduous tropical forest on the Pacific coast of Mexico during different seasons and in natural treefall gaps and pastures. All 12 plant species sampled in the forest were arbuscular mycorrhizal. The percent root infection and spore production were closely related to the phenology of the plants. Most tree species and all herbaceous species had the highest infection in the summer rainy season, but two species, Opuntia excelsa and Jacquinia pungens, had highest infection in the dry season. Unusually high rainfall during the dry season was associated with increased infection but not increased spore production. Spore density was low for all species at all sample times, except at the beginning of the July 1993 rainy season in, when we observed up to 28 spores/g soil. The percent cover of shrubs or herbs did not increase in gaps after two years, and we observed no colonizing seedlings. No plant species with cover higher than 2.7 percent occurred exclusively in gaps or forest. The percent mycorrhizal infection did not differ significantly between gaps and forest. Spore counts were as high in the gaps as in the forest in two of the three gaps but lower in the third gap. The lack of significant response of plants in these gaps after two years differed from the rapid response in tropical rainforests. It is likely related to the small size of the gaps and to light infiltration to the forest floor. Pastures were dominated by two species of exotic grasses and one species of mycorrhizal fungus, whereas forests had 15 fungal species. The slow regrowth of vegetation in gaps was not limited by mycorrhizal fungi, since they were still abundant after the treefalls, but recovery in pastures could be affected by low fungal diversity and dominance of grasses.     

Integrative taxonomy reveals extreme morphological conservatism in sympatric Mugil species from the Tropical Southwestern Atlantic

The biodiversity crisis has had particularly harsh impacts on marine environments. However, there is still considerable uncertainty about how many species have been seriously impacted and the effectiveness of protection measures (e.g., marine protected areas or MPAs) due to high levels of cryptic species in many taxa. Here, we employ an integrative taxonomy approach to mullet species in the genus Mugil. In addition to its high economic value, this genus is notable for having diversified ~29 million years ago without marked morphological and ecological divergence. We obtained 129 specimens of Mugil from the Coral Coast MPA, the largest of its kind in the Tropical Southwestern Atlantic marine province. Although morphometric and meristic traits revealed six taxonomically recognized species, only five mitochondrial lineages were observed. All individuals morphologically identified as M. incilis belonged to the mitochondrial lineage of Mugil curema, which is consistent with misidentification of morphologically similar species and an overestimation of species diversity. Remarkably, Mugil species in our sample that diverged up to ~23 million years ago are also the most morphologically similar (M. curema and M. rubrioculus), suggesting extreme morphological conservatism, possibly driven by similarities in habitat use and life‐history traits. This study demonstrates the potential utility of integrative taxonomy (including DNA barcoding) for contributing to the conservation and sustainable use of natural resources.     

Poor nutritional condition promotes high-risk behaviours: a systematic review and meta-analysis

Animal behaviour can lead to varying levels of risk, and an individual's physical condition can alter the potential costs and benefits of undertaking risky behaviours. How risk-taking behaviour depends on condition is subject to contrasting hypotheses. The asset protection principle proposes that individuals in better condition should be more risk averse, as they have higher future reproductive potential (i.e. more to lose). The state-dependent safety hypothesis proposes that high-condition individuals that are more likely to survive and maximise the benefits of risky situations may make apparently riskier choices, as their individual risk is in fact lower. We systematically searched for studies that experimentally manipulated animals’ nutritional or energetic condition through diet treatments, and subsequently measured risk-taking behaviour in contexts relating to predation, novelty and exploration. Our meta-analysis quantified condition effects on risk-taking behaviour at both the mean and variance level. We preregistered our methods and hypotheses prior to conducting the study. Phylogenetic multilevel meta-analysis revealed that the lower-nutritional-condition individuals showed on average ca. 26% greater tendency towards risk than high-condition individuals (95% confidence interval: 15–38%; N = 126 studies, 1297 effect sizes). Meta-regressions revealed several factors influencing the overall effect, such as the experimental context used to measure risk-taking behaviour, and the life stage when condition was manipulated. Meta-analysis of variance revealed no clear overall effect of condition on behavioural variance (on average ca. 3% decrease in variance in low- versus high-condition groups; 95% confidence interval: −8 to 3%; N = 119 studies, 1235 effect sizes), however, the experimental context was an important factor influencing the strength and direction of the variance effect. Our comprehensive systematic review and meta-analysis provide insights into the roles of state dependency and plasticity in intraspecific behavioural variation. While heterogeneity among effect sizes was high, our results show that poor nutritional state on average increases risk taking in ecological contexts involving predation, novelty and exploration.     

Coordination Analysis Reveals Differences in Motor Strategies for the High Bar Longswing among Novice Adults

Coordination between arm-trunk and trunk-leg is important for effective longswing performance. This research describes inter-segmental coordination changes after a practice period of longswing on high bar in a novice cohort. Novices were divided by initial skill level (talent) into two groups: spontaneously-talented, (ST, n = 10, closer to expert performance) and non-spontaneously-talented (NST, n = 15). Additionally, post-practice longswing coordination was compared to expert gymnasts (n = 9). Longswing amplitude and coordination (inter-joint reversal points and continuous relative phase, CRP) were assessed for pre- and post-practice sessions. ANOVAs showed similar practice effects in swing enlargements for the ST (11%) and NST (18%), but inter-joint reversal points and positive area in CRP during the downswing were different. Due to practice, the ST group paired shoulder and hip reversal points (events) during the downswing closer and with larger velocity of the arm in relation to the trunk than the NST group. The NST failed to modify coordination probably due to a large variability at the beginning of the downswing. Given a similar amount of practice, talent could help to achieve the right temporal events’ sequence during downswing, which would allow the exploration of different segmental coordination. However, upswing coordination of the novice groups (ST and NST) requires more focused practice to achieve expert levels than downswing, especially the arm-trunk coordination.     

Patterns of Knowledge and Use of Medicinal Plants in Santiago Camotlán,Oaxaca, Mexico

Medicinal plants continue to play an important role in healthcare, both in Mexico and around the world. We investigated the relationship between various sociodemographic factors, such as age, economic activity, years of schooling, socioeconomic levels, gender, and language proficiency, and the knowledge and frequency of medicinal plant use in Santiago Camotlán, Sierra Norte of Oaxaca, with a mainly Zapotec population. In a first stage, we interviewed specialists in depth and collected and identified plants for a catalogue of the medicinal plant flora (90 species). With this catalogue, we then interviewed a sample of the general population and the specialists on knowledge and frequency of use. The relationship between the sociodemographic variables and knowledge was analyzed by multiple regression. To explore differences of knowledge within the population, we identified three groups with a two-step cluster analysis; the results were compared statistically with a Kruskal-Wallis non-parametric test and then a post hoc Dunn’s test to see if all the differences between groups were significant. Age and occupation explained 54% of the variation of knowledge. Medicinal plant knowledge in the region persists mainly because of the necessity to treat the diseases that the “doctor does not cure,” the culture-bound syndromes, and the most common ailments, malfunctions of the digestive system.