Pests vs. drought as determinants of plant distribution along a tropical rainfall gradient

Journal ArticleUnderstanding the mechanisms that shape the distribution of organisms can help explain patterns of local and regional biodiversity and predict the susceptibility of communities to environmental change. In the species-rich tropics, a gradient in rainfall between wet evergreen and dry seasonal forests correlates with turnover of plant species. The strength of the dry season has previously been shown to correlate with species composition

Structural habitat use by the Many-scaled Anole, Anolis polylepis (Squamata: Polychrotidae)

Lizards of the genus Anolis are commonly used as models for several ecological studies. Nevertheless, some aspects of their ecology have not been studied and information reported previously for several species must be reanalyzed. The aim of this study is to examine the structural habitat use in a population of the Many-scaled Anole, Anolis polylepis, with the purpose of comparing our results with the information reported previously for this species. Most of the captured individuals were on stems and we did not find any differences in the structural habitat use among sex/age classes. We found differences for perch height among individuals shedding their skin regarding those that are not. We also detected differences among our results and the information reported previously for this species. Such differences could be due to intrinsic factors of each population, such as the proportion of individuals that were molting their skin in a specific time. More studies with greater sample sizes and to a longer term are required to clearly understand the influence of these factors in the habitat use of A. polylepis and other anoline lizards

Pulmonary but not subcutaneous vaccination confers protection to TB susceptible mice by an IL17-dependent mechanism.

Some of the most promising novel tuberculosis vaccine strategies currently under development are based on respiratory vaccination, mimicking the natural route of infection. In this work, we have compared pulmonary and subcutaneous delivery of BCG vaccine in the tuberculosis-susceptible DBA/2 mouse strain, a model in which parenterally administered BCG vaccine does not protect against tuberculosis. Our data show that intranasally but not subcutaneously administered BCG confers robust protection against pulmonary tuberculosis challenge. In addition, our results indicate that pulmonary vaccination triggers a Mycobacterium tuberculosis–specific mucosal immune response orchestrated by interleukin 17A (IL-17A). Thus, IL-17A neutralization in vivo reduces protection and abrogates M. tuberculosis–specific immunoglobulin A (IgA) secretion to respiratory airways and lung expression of polymeric immunoglobulin receptor induced following intranasal vaccination. Together, our results demonstrate that pulmonary delivery of BCG can overcome the lack of protection observed when BCG is given parenterally, suggesting that respiratory tuberculosis vaccines could have an advantage in tuberculosis-endemic countries, where intradermally administered BCG has inefficient effectiveness against pulmonary tuberculosis

Geochemistry and microbiology of tropical serpentine soils in the Santa Elena Ophiolite, a landscape-biogeographical approach

This is the final version. Available on open access from BMC via the DOI in this recordAvailability of data and materials: The datasets supporting the conclusions of this article are available in https://doi.org/10.17632/w6cdt3sn99.4 with CC BY 4.0 license, in NCBI SRA (Sequence Read Archive; http://www.ncbi.nlm.nih.gov/sra/, under the project accession number: PRJNA606410) and within the article and its additional file.The Santa Elena Ophiolite is a well-studied ultramafic system in Costa Rica mainly comprised of peridotites. Here, tropical climatic conditions promote active laterite formation processes, but the biogeochemistry of the resulting serpentine soils is still poorly understood. The aim of this study was to characterize the soil geochemical composition and microbial community of contrasting landscapes in the area, as the foundation to start exploring the biogeochemistry of metals occurring there. The soils were confirmed as Ni-rich serpentine soils but differed depending on their geographical location within the ophiolite area, showing three serpentine soil types. Weathering processes resulted in mountain soils rich in trace metals such as cobalt, manganese and nickel. The lowlands showed geochemical variations despite sharing similar landscapes: the inner ophiolite lowland soils were more like the surrounding mountain soils rather than the north lowland soils at the border of the ophiolite area, and within the same riparian basin, concentrations of trace metals were higher downstream towards the mangrove area. Microbial community composition reflected the differences in geochemical composition of soils and revealed potential geomicrobiological inputs to local metal biogeochemistry: iron redox cycling bacteria were more abundant in the mountain soils, while more manganese-oxidizing bacteria were found in the lowlands, with the highest relative abundance in the mangrove areas. The fundamental ecological associations recorded in the serpentine soils of the Santa Elena Peninsula, and its potential as a serpentinization endemism hotspot, demonstrate that is a model site to study the biogeochemistry, geomicrobiology and ecology of tropical serpentine areas.Ministerio de Ciencia, Tecnología y Telecomunicaciones (MICITT), Government of Costa RicaUniversidad de Costa RicaMICITTNatural Environment Research Council (NERC

Non-typeable Haemophilus influenzae and Streptococcus pneumoniae as primary causes of acute otitis media in colombian children: a prospective study

<p>Abstract</p> <p>Background</p> <p>Acute otitis media (AOM) is one of the most frequently encountered bacterial infections in children aged < 5 years; <it>Streptococcus pneumoniae </it>(<it>S. pneumoniae</it>) and non-typeable <it>Haemophilus influenzae </it>(NTHi) are historically identified as primary AOM causes. Nevertheless, recent data on bacterial pathogens causing AOM in Latin America are limited. This prospective study aimed to identify and characterize bacterial etiology and serotypes of AOM cases including antimicrobial susceptibility in < 5 year old Colombian children.</p> <p>Methods</p> <p>From February 2008 to January 2009, children ≥3 months and < 5 years of age presenting with AOM and for whom a middle ear fluid (MEF) sample was available were enrolled in two medical centers in Cali, Colombia. MEF samples were collected either by tympanocentesis procedure or spontaneous otorrhea swab sampling. Bacteria were identified using standard laboratory methods, and antimicrobial resistance testing was performed based on the 2009 Clinical and Laboratory Standards Institute (CLSI) criteria. Most of the cases included in the study were sporadic in nature.</p> <p>Results</p> <p>Of the 106 enrolled children, 99 were included in the analysis. Bacteria were cultured from 62/99 (63%) of samples with <it>S. pneumoniae, H. influenzae, or S. pyogenes</it>. The most commonly isolated bacteria were <it>H. influenzae </it>in 31/99 (31%) and <it>S. pneumoniae </it>in 30/99 (30%) of samples. The majority of <it>H. influenzae </it>episodes were NTHi (27/31; 87%). 19F was the most frequently isolated pneumococcal serotype (10/30; 33%). Of the 30 <it>S. pneumoniae </it>positive samples, 8/30 (27%) were resistant to tetracycline, 5/30 (17%) to erythromycin and 8/30 (27%) had intermediate resistance to penicillin. All <it>H. influenzae </it>isolates tested were negative to beta-lactamase.</p> <p>Conclusions</p> <p>NTHi and <it>S. pneumoniae </it>are the leading causes of AOM in Colombian children. A pneumococcal conjugate vaccine that prevents both pathogens could be useful in maximizing protection against AOM.</p

Do differences in understory light contribute to species distributions along a tropical rainfall gradient?

In tropical forests, regional differences in annual rainfall correlate with differences in plant species composition. Although water availability is clearly one factor determining species distribution, other environmental variables that covary with rainfall may contribute to distributions. One such variable is light availability in the understory, which decreases towards wetter forests due to differences in canopy density and phenology. We established common garden experiments in three sites along a rainfall gradient across the Isthmus of Panama in order to measure the differences in understory light availability, and to evaluate their influence on the performance of 24 shade-tolerant species with contrasting distributions. Within sites, the effect of understory light availability on species performance depended strongly on water availability. When water was not limiting, either naturally in the wetter site or through water supplementation in drier sites, seedling performance improved at higher light. In contrast, when water was limiting at the drier sites, seedling performance was reduced at higher light, presumably due to an increase in water stress that affected mostly wet-distribution species. Although wetter forest understories were on average darker, wet-distribution species were not more shade-tolerant than dry-distribution species. Instead, wet-distribution species had higher absolute growth rates and, when water was not limiting, were better able to take advantage of small increases in light than dry-distribution species. Our results suggest that in wet forests the ability to grow fast during temporary increases in light may be a key trait for successful recruitment. The slower growth rates of the dry-distribution species, possibly due to trade-offs associated with greater drought tolerance, may exclude these species from wetter forests