Arbuscular mycorrhizal fungi in a mountain grassland II: Seasonal variation of colonization studied, along with its relation to grazing and metabolic host type

The relationships among seasons, host metabolic type, grazing and arbuscular mycorrhizal colonization were analyzed in a high South American native grassland. This study investigated seasonal changes and grazing effects on the symbiotic endomycorrhizal interaction in 5 Poaceae [C(3) metabolic pathway: Briza subaristata Lam., Deyeuxia hieronymi (Hack.) Türpe and Poa stuckertii (Hack.) Parodi; with C(4) metabolic pathway: Eragrostis lugens Nees and Sorghastrum pellitum (Hack.) Parodi; and a Rosaceae (Alchemilla pinnata Ruíz & Pav.)]. All hosts were dominant species in the mountain grassland in central Argentina. It was found that the seasons markedly influenced endomycorrhizal colonization, whereas grazing did not affect this interaction. C(4) grasses presented the highest root colonization. Hosts Briza subaristata (C(3) metabolic pathway) and Sorghastrum pellitum (C(4) metabolic pathway) showed Arum- and Paris-type colonization and intermediate forms.     

Native arbuscular mycorrhizal fungi (AMF) from mountain grassland (Cordoba, Argentina) I. Seasonal variation of fungal spore diversity

Arbuscular mycorrhizal fungi (AMF) were studied in the rhizosphere of 3 Poaceae with metabolic pathway C(3) (Briza subaristata Lam., Deyeuxia hieronymi (Hack.) Türpe and Poa stuckertii (Hack.) Parodi), 2 Poaceae with C(4) metabolic type (Eragrostis lugens Nees and Sorghastrum pellitum (Hack.) Parodi.), and a Rosaceae (Alchemilla pinnata Ruíz & Pav.) from a natural mountain grassland in Central Argentina (South America). Host species, their metabolic type, seasonal changes, and grazing effects over AM fungal diversity were analyzed. Seventeen mycorrhizal fungi taxa were found, widespread in all families of Glomales. Density of endomycorrhizal fungi was found to be strongly influenced with seasons and host metabolic pathway, although biodiversity (H), richness (S) and evenness (E) did not change. In most cases grazing did not affect these variables.     

Phytoplankton of cenotes and anchialine caves along a distance gradient from the northeastern coast of Quintana Roo,Yucatan Peninsula

This work details the taxonomic composition of suspended algae (phytoplankton and tycoplankton) communities in five cenotes (sinkholes) and two anchialine caves in northeastern Quintana Roo, Mexico. The sample set of cenotes are Casa, Nohoch Nah Chich, Maya Blue, Cristal, and Carwash, as well as the two associated caves leading from the cenotes of Maya Blue and Cristal. The site distribution represents a distance gradient with respect to the coastline with which we observe the effects of tidal movement and the mixing of waters (e.g. saline water and freshwater) on the composition of the suspended algae communities. Two sample sets were taken, one at the end of the dry season (March–April 1995) and the second at the end of the rainy season (September–October 1995) with the goal of comparing the contrasting climatic conditions of the region. A total of 79 species were identified, of which, diatoms were the most important with respect to species richness with a total of 75% of species. The floristic composition is very similar between the freshwater cenotes. The distance of a cenote site with respect to the coastline was a determining factor in the species composition. Casa Cenote is the most distinct of the sample set for the presence of marine species due to its proximity to the coastline. The tides are a large determining factor of the floristic composition of Casa Cenote with 24% all species identified in this study found exclusively in this system. The anchialine system species are transported from the cenotes and the adjacent cave systems. The largest percentage or species (95%) are freshwater, and only 5% of the total number of identified species are of marine origin. It is recognized that the most distant cenotes from the coast, Carwash and Cristal, as well as Maya Blue and Nohoch Nah Chich, are the most similar, despite being part of different cave systems. In these inland systems the marine species decreased drastically (2.4% in Nohoch Nah Chich and no marine species in the remaining cenotes). Marine species are found at the halocline of the caves.     

Microbiota of Telenomus tridentatus (Platygastroidea: Scelionidae): An unwanted parasitoid

The microbiota of Hymenoptera is limited to certain bacterial species that vary according to the habitat and diet; however, the bacterial populations are not known in Telenomus tridentatus Johnson & Bin, an egg parasitoid of agricultural importance. We determined the microbiota composition of adults of T. tridentatus using next‐generation sequencing technologies. We found the presence of the Phylums Proteobacteria, in greater proportion followed by Actinobacteria and Firmicutes, respectively. The most abundant species were Cutibacterium acnes, Aquabacterium sp. and Massilia sp. The results of this study could lead to investigating the importance of symbiotic bacteria in T. tridentatus and its relation with agricultural plantations.     

Land use history, hurricane disturbance, and the fate of introduced species in a subtropical wet forest in Puerto Rico

Tropical forests are suffering from increasing intensities and frequency of disturbances. As a result, non-native species accidentally introduced or intentionally planted for farming, plantations, and ornamental purposes may spread and potentially invade undisturbed native forest. It is not known if these introduced species will become invasive, as a result of recurrent natural disturbances such as hurricanes. Using data from three censuses (spanning 15 years) of a 16-ha subtropical wet forest plot, we investigated the impact of two hurricanes on populations of plant species that were planted in farms and plantations that were then abandoned and from the natural spread of species introduced into Puerto Rico in the past. The populations of four species (Citrus paradis, Mangifera indica, Musa sp., and Simarouba glauca) changed little over time. Six species (Artocarpus altilis, Calophyllum calaba, Genipa americana, Hibiscus pernambucensis, Syzygium jambos, and Swietenia macrophylla) declined between the first two censuses after Hurricane Hugo, then increased again in Census 3 after Hurricane Georges. Spathodea campanulata gradually increased from census to census, while Coffea arabica declined. These introduced species represent only a small part of the forest basal area and few show signs of increasing over time. The number of stems per plant, new recruits, and the growth rates of these introduced species were within the ranges of those for native plant species. The mortality rates over both census intervals were significantly lower for introduced species (<5% year⁻¹) than for native ones (15% year⁻¹). Many new recruits established after Hurricane Hugo (prior to this study) had opened the forest canopy and these high mortality rates reflect their death as the canopy recovered. Only Swietenia macrophylla and Syzygium jambos showed an increase in stem numbers in the closed canopy area of forest that had suffered limited human disturbance in the past. A future increase in frequency of disturbance may enable greater stem numbers of introduced species to establish, while lower-mortality rates compared to native species, may allow them to persist during inter-hurricane intervals. An increase in the population of introduced species, especially for those that grow into large trees, may have an impact on this tropical forest in the future.     

A time-course comparative clinical and immune response evaluation study between the human pathogenic Orientia tsutsugamushi strains: Karp and Gilliam in a rhesus macaque (Macaca mulatta) model

BackgroundScrub typhus is a vector-borne febrile illness caused by Orientia tsutsugamushi transmitted by the bite of Trombiculid mites. O. tsutsugamushi has a high genetic diversity and is increasingly recognized to have a wider global distribution than previously assumed.Methodology/principle findingsWe evaluated the clinical outcomes and host immune responses of the two most relevant human pathogenic strains of O. tsutsugamushi; Karp (n = 4) and Gilliam (n = 4) in a time-course study over 80 days post infection (dpi) in a standardized scrub typhus non-human primate rhesus macaque model. We observed distinct features in clinical progression and immune response between the two strains; Gilliam-infected macaques developed more pronounced systemic infection characterized by an earlier onset of bacteremia, lymph node enlargement, eschar lesions and higher inflammatory markers during the acute phase of infection, when compared to the Karp strain. C-reactive protein (CRP) plasma levels, interferon gamma (IFN-γ, interleukin-1 receptor antagonist (IL-1ra), IL-15 serum concentrations, CRP/IL10- and IFN-γ/IL-10 ratios correlated positively with bacterial load in blood, implying activation of the innate immune response and preferential development of a T helper-type 1 immune response. The O. tsutsugamushi-specific immune memory responses in cells isolated from skin and lymph nodes at 80 dpi were more markedly elevated in the Gilliam-infected macaques than in the Karp-infected group. The comparative cytokine response dynamics of both strains revealed significant up-regulation of IFN-γ, tumor necrosis factor (TNF), IL-15, IL-6, IL-18, regulatory IL-1ra, IL-10, IL-8 and granulocyte-colony-stimulating factor (G-CSF). These data suggest that the clinical outcomes and host immune responses to scrub typhus could be associated with counter balancing effects of pro- and anti-inflammatory cytokine-mediated responses.Currently, no data on characterized time-course comparisons of O. tsutsugamushi strains regarding measures of disease severity and immune response is available. Our study provides evidence for the strain-specificity of host responses in scrub typhus, which supports our understanding of processes at the initial inoculation site (eschar), systemic disease progression, protective and/or pathogenic host immune mechanisms and cellular immune memory function.Conclusions/significanceThis study characterised an improved intradermal rhesus macaque challenge model for scrub typhus, whereby the Gilliam strain infection associated with higher disease severity in the rhesus macaque model than the previous Karp strain infection. Difficulties associated with inoculum quantitation for obligate-intracellular bacteria were overcome by using functional inoculum titrations in outbred mice. The Gilliam-based rhesus macaque model provides improved endpoint measurements and contributes towards the identification of correlates of protection for future vaccine development.     

Toxicity and mutagenicity of radiation from fluorescent lamps and a sunlamp in L5178y mouse lymphoma cells

Unfiltered broad spectrum radiation emitted by black light, cool white, and black light blue fluorescent lamps and a sunlamp, is both toxic and mutagenic to L5178Y mouse lymphoma cells when the cells are irradiated in phosphate-buffered saline. The increase in mutant frequency seen after exposure of the cells is linear throughout the range of exposures tested. The linear increase in mutagenesis is observed even at exposure levels which do not cause significant toxicity. To facilitate comparison of the differing rates of mutagenesis derived from exposure-response curves obtained for each light source, we have defined a parameter, joule-equivalent mutagenesis (jem), equal to mutants per 10(5) survivors per joule per square meter. Jem values are calculated using the integrated irradiance of each lamp. Based on jem values, the relative mutagenicity of the various lamps tested (compared with a germicidal ultraviolet lamp) is 3 x 10(-3) for the sunlamp, 1 x 10(-4) for the black light and cool white lamps, and 3 x 10(-5) for the black light blue lamp. The toxic and mutagenic effects of the lamps are in reasonable agreement with their relative spectral output from 290 to 330 nm.     

Genetic Landscapes GIS Toolbox: tools to map patterns of genetic divergence and diversity

The Landscape Genetics GIS Toolbox contains tools that run in the Geographic Information System software, ArcGIS^®, to map genetic landscapes and to summarize multiple genetic landscapes as average and variance surfaces. These tools can be used to visualize the distribution of genetic diversity across geographic space and to study associations between patterns of genetic diversity and geographic features or other geo‐referenced environmental data sets. Together, these tools create genetic landscape surfaces directly from tables containing genetic distance or diversity data and sample location coordinates, greatly reducing the complexity of building and analyzing these raster surfaces in a Geographic Information System.     

Place of Preoperative Treatment of Acromegaly with Somatostatin Analog on Surgical Outcome: A Systematic Review and Meta-Analysis

Context

Transsphenoidal neurosurgery is the accepted first-line treatment of acromegaly in the majority of patients. Previous studies addressing preoperative somatostatin analog (SSA) treatment and subsequent surgical cure rates are conflicting, reporting either benefits or no significant differences.

Objective

The aim of this study, based on a meta-analysis of all published reports, was to investigate whether treatment with SSA before surgery improves the surgical outcome of acromegaly.

Data Sources

All studies of preoperative treatment of acromegaly with SSA were systematically reviewed up to December 2011. We searched the Medline, Embase, Cochrane and Google Scholar electronic databases. Study Selection: The primary endpoint was the biochemical postoperative cure rate. We identified 286 studies, out of which 10 studies (3.49%) fulfilling the eligibility criteria were selected for analysis; five retrospective studies with a control group, two prospective non-randomized trials, and three prospective controlled trials. The meta-analysis was conducted using the random-effects model.

Data Extraction

Data were extracted from published reports by two independent observers. Data Synthesis: A borderline effect was detected in the analysis of all of the trials with control groups, with a pooled odds ratio (OR) for biochemical cure with SSA treatment of 1.62 (95% CI, 0.93–2.82). In the analysis of the three prospective controlled trials, a statistically significant effect was idenfified OR: 3.62 (95% CI, 1.88–6.96).

Conclusions

Preoperative treatment with SSA og GH-secreting pituitary adenomas shows a significant improvement on surgical results. This meta-analysis suggests that in centers without optimal results all patients with a GH-secreting pituitary macroadenoma should be treated with a long-acting SSA prior to surgical treatment.