The home-field advantage (HFA) hypothesis establishes that plant litter decomposes faster at ‘home’ sites than in ‘away’ sites due to more specialized decomposers acting at home sites. This hypothesis has predominantly been tested through ‘yes or no’ transplanting experiments, where the litter decomposition of a focal species is quantified near and away from their conspecifics. Herein, we evaluated the occurrence and magnitude of home-field effects on the leaf litter decomposition of Myrcia ramuliflora (O.Berg) N. Silveira (Myrtaceae) along a natural gradient of conspecific litterfall input and also if home-field effects are affected by litter and soil traits. Litter decomposition of M. ramuliflora was assessed through litterbags placed in 39 plots in a tropical heath vegetation over a period of 12 months. We also characterized abiotic factors, litter layer traits, and litter diversity. Our results indicated the occurrence of positive (i.e. Home-field advantage) and negative (i.e. Home-field disadvantage) effects in more than half of the plots. Positive and negative effects occurred in a similar frequency and magnitude. Among all predictors tested, only the community weighted mean C/N ratio of the litterfall input was associated with home-field effects. Our results reinforce the lack of generality for home-field effects found in the literature and thus challenge the understanding of litter-decomposer interaction in tropical ecosystems.

Energetic-particle-induced geodesic acoustic modes, EGAMs (Fu, Phys. Rev. Let., vol. 101, 2008, pp. 185002), driven by neutral beam injection (NBI), have been observed in many DIII-D tokamak experiments (Nazikian et al., Phys. Rev. Lett., vol. 101, 2008, pp. 185001). This mechanism has been theoretically investigated in (Qiu et al., Plasma Phys. Control. Fusion, vol. 52, 2010, pp. 095003), using a sharp energetic particle distribution function, and in (Qu et al., Plasma Phys. Control. Fusion, vol. 59, 2017, pp. 055018), where the dispersion relation and eigenmode behaviour were obtained for the situation of early beam scenario, that is, for times smaller than the beam slowing down time. In this work, we extend these studies determining the eigenmode for beyond the slowing down time, in a scenario with reverse safety factor $q$ profile, where a small concentration of energetic ions can produce an off-axis maximum in the GAM dispersion relation. The characteristics of EGAM are analytically studied with the drift kinetic equation together with the MHD code NOVA. The toroidal energetic ion transit frequency, coupled with the GAM frequency, produces the maximum in the dispersion relation where the eigenmode can be found. The quantitative correspondence of experimental results with the predictions of the proposed model is analysed.

The current study aimed to select the strains of lactic acid bacteria (LAB) isolated from forage cactus plants and silage and assess their effects on silage fermentation and aerobic stability. Forty wild isolates from plant and cactus silage, classified as LAB, were evaluated for metabolite production and identified by 16S ribosomal DNA sequencing. These wild isolates were identified as Lactobacillus plantarum, Weissella cibaria, Weissella confusa and Weissella paramesenteroides and the LAB populations differed among the silage. The use of microbial inoculants did not influence gas or effluent losses in forage cactus silage. The silage inoculated with the microbial strain GP15 showed the highest number of LAB populations. The amounts of water-soluble carbohydrates (WSC) and ammonia nitrogen differed among the silage. The silage inoculated with the GP1 strain presented the highest WSC. Populations of enterobacteria and yeasts and moulds were below the minimum detection limit (<2.0 log cfu/g silage) in all the silage studied. The predominant action of inoculants was to maximize dry matter recovery of the silage, which could be the criterion adopted to select the strains of LAB for use as inoculants in Opuntia silage.

The mineralogy of the silt fraction of a 1.5 m-deep, well developed, intensely weathered, greyish soil profile from a toposequence on a tableland covered by agricultural crops in the upper valley of the Jequitinhonha river basin, Minas Gerais, Brazil, has been studied by X-ray powder diffraction, 57Fe Mössbauer spectroscopy at 298 K and 80 K, and vibrating sample magnetometry. Mössbauer data collected at room temperature indicated about 17 atom% of the iron content of the sample to be structural Fe2+ in phyllosilicates, which X-ray diffraction showed to be mainly halloysite and kaolinite. The magnetization curve also indicates the presence of a ferrimagnetic phase, tentatively identified by Mössbauer spectroscopy as maghemite (γ-Fe2O3).

These findings support a pedogenetic model for this soil profile, by which the remaining Fe2+ bearing minerals were first formed under relatively anoxic palaeo-conditions of an intense hydric regime. Subsequent drier local conditions, due to a much improved drainage, favoured intensive weathering, leading to the presently developed Oxisol. Even under the more oxidative conditions, part of the Fe2+ -containing phyllosilicates still remained in the profile, which is believed to impart the rather unusual greyish colour (Munsell 10YR 3/2) to this deep tropical soil.

The upper Jequitinhonha Valley is located within the Serra do Espinhaço Meridional mountain range in the State of Minas Gerais, Brazil. The topography is flat or gently undulating with large flat areas known as chapadas (‘high plains’) that are dissected by rivers forming swamps known locally as veredas (‘paths’). The present study is concerned mainly with a representative toposequence in the watershed of the Lagoa do Leandro vereda, a swamp near the city of Minas Novas on a chapada of the highlands of the Alto (Upper) Jequitinhonha region.

The soils of this sequence were studied by a variety of physical and chemical techniques, including Mössbauer, electron spin resonance (ESR) and photoacoustic (PAS) spectroscopies, as well as X-ray diffraction (XRD) and carbon isotope data. Mössbauer spectra of the silt fraction of a grey Xanthic Haplustox (Munsell 10YR 3/2) from the Lagoa do Leandro vereda, referred to here as a ‘Grey Haplustox’ (‘LAC’), proved the existence of Fe2+- and Fe3+-bearing components. Photoacoustic spectroscopy confirmed the presence of Fe2+, as shown by Mössbauer spectroscopy, probably in an octahedrally coordinated site, but the principal optical absorption bands are due to different Fe3+ sites. A ferrimagnetic contribution and three other paramagnetic lines attributed to Fe3+ and Ti3+ were demonstrated by means of ESR. The ESR and PAS results are thus in agreement with the chemical composition and Mössbauer spectroscopy, allowing a detailed characterization of the mineralogy of this silt.

Carbon isotope data indicate the climate to have varied during the past: awetter climate in the Pleistocene, with drier phases in the Late Pleistocene and Holocene, and again a more humid climate 1200 years ago. δ13C data indicate the C3 scrubland vegetation to have occupied the bottom of the vereda in the past (Bispo & Silva, 2014).

Greyish Oxisols that consist chiefly of phyllosilicate minerals of the kaolinite group (which are usually associated with binary oxides and hydroxides) are of common occurrence in tropical soils resulting from leaching and precipitation. Such Oxisols of greyish appearance and similar mineralogy have been described elsewhere from Brazil and, for example, from India. Such soils are therefore proposed here as a new hierarchical level of the Soil Classification System.

The study of the mechanical properties of nanostructured systems has gained importance in theoretical and experimental research in recent years. Carbon nanotubes (CNTs) are one of the strongest nanomaterials found in nature, with Young’s Modulus (EY) in the order 1.25 TPa. One interesting question is about the possibility of generating new nanostructures with 1D symmetry and with similar and/or superior CNT properties. In this work, we present a study on the dynamical, structural, mechanical properties, fracture patterns and EY values for one class of these structures, the so-called pentagraphene nanotubes (PGNTs). These tubes are formed rolling up pentagraphene membranes (which are quasi-bidimensional structures formed by densely compacted pentagons of carbon atoms in sp3 and sp2 hybridized states) in the same form that CNTs are formed from rolling up graphene membranes. We carried out fully atomistic molecular dynamics simulations using the ReaxFF force field. We have considered zigzag-like and armchair-like PGNTs of different diameters. Our results show that PGNTs present EY ∼ 800 GPa with distinct elastic behavior in relation to CNTs, mainly associated with mechanical failure, chirality dependent fracture patterns and extensive structural reconstructions.

Toxoplasma gondii is an intracellular protozoan parasite that causes toxoplasmosis, a prevalent infection related to abortion, ocular diseases and encephalitis in immuno-compromised individuals. In the untreatable (and life-long) chronic stage of toxoplasmosis, parasitophorous vacuoles (PVs, containing T. gondii tachyzoites) transform into tissue cysts, containing slow-dividing bradyzoite forms. While acute-stage infection with tachyzoites involves global rearrangement of the host cell cytoplasm, focused on favouring tachyzoite replication, the cytoplasmic architecture of cells infected with cysts had not been described. Here, we characterized (by fluorescence and electron microscopy) the redistribution of host cell structures around T. gondii cysts, using a T. gondii strain (EGS) with high rates of spontaneous cystogenesis in vitro. Microtubules and intermediate filaments (but not actin microfilaments) formed a ‘cage’ around the cyst, and treatment with taxol (to inhibit microtubule dynamics) favoured cystogenesis. Mitochondria, which appeared adhered to the PV membrane, were less closely associated with the cyst wall. Endoplasmic reticulum (ER) profiles were intimately associated with folds in the cyst wall membrane. However, the Golgi complex was not preferentially localized relative to the cyst, and treatment with tunicamycin or brefeldin A (to disrupt Golgi or ER function, respectively) had no significant effect on cystogenesis. Lysosomes accumulated around cysts, while early and late endosomes were more evenly distributed in the cytoplasm. The endocytosis tracer HRP (but not BSA or transferrin) reached bradyzoites after uptake by infected host cells. These results suggest that T. gondii cysts reorganize the host cell cytoplasm, which may fulfil specific requirements of the chronic stage of infection.

Urban slums provide suitable conditions for infestation by rats, which harbour and shed a wide diversity of zoonotic pathogens including helminths. We aimed to identify risk factors associated with the probability and intensity of infection of helminths of the digestive tract in an urban slum population of Rattus norvegicus. Among 299 rats, eleven species/groups of helminths were identified, of which Strongyloides sp., Nippostrongylus brasiliensis and, the human pathogen, Angiostrongylus cantonensis were the most frequent (97, 41 and 39%, respectively). Sex interactions highlighted behavioural differences between males and females, as eg males were more likely to be infected with N. brasiliensis where rat signs were present, and males presented more intense infections of Strongyloides sp. Moreover, rats in poor body condition had higher intensities of N. brasiliensis. We describe a high global richness of parasites in R. norvegicus, including five species known to cause disease in humans. Among these, A. cantonensis was found in high prevalence and it was ubiquitous in the study area – knowledge which is of public health importance. A variety of environmental, demographic and body condition variables were associated with helminth species infection of rats, suggesting a comparable variety of risk factors for humans.

Intrauterine growth restriction (IUGR) can induce deleterious changes in the modulatory ability of the vascular endothelium, contributing to an increased risk of developing cardiovascular diseases in the long term. However, the mechanisms involved are not fully understood. Emerging evidence has suggested the potential role of endothelial progenitor cells (EPCs) in vascular health and repair. Therefore, we aimed to evaluate the effects of IUGR on vascular reactivity and EPCs derived from the peripheral blood (PB) and bone marrow (BM) in vitro. Pregnant Wistar rats were fed an ad libitum diet (control group) or 50% of the ad libitum diet (restricted group) throughout gestation. We determined vascular reactivity, nitric oxide (NO) concentration, and endothelial nitric oxide synthase (eNOS) protein expression by evaluating the thoracic aorta of adult male offspring from both groups (aged: 19–20 weeks). Moreover, the amount, functional capacity, and senescence of EPCs were assessed in vitro. Our results indicated that IUGR reduced vasodilation via acetylcholine in aorta rings, decreased NO levels, and increased eNOS phosphorylation at Thr495. The amount of EPCs was similar between both groups; however, IUGR decreased the functional capacity of EPCs from the PB and BM. Furthermore, the senescence process was accelerated in BM-derived EPCs from IUGR rats. In summary, our findings demonstrated the deleterious changes in EPCs from IUGR rats, such as reduced EPC function and accelerated senescence in vitro. These findings may contribute towards elucidating the possible mechanisms involved in endothelial dysfunction induced by fetal programming.