ALBERT

Description: Studies on elevation diversity gradients have covered a large number of taxa and regions throughout the world; however, studies of freshwater fish are scarce and restricted to examining their changes along a specific gradient. These studies have reported a monotonic decrease in species richness with increasing elevation, but ignore the high taxonomic differentiation of each headwater assemblage that may generate high β -diversity among them. Here, we analyzed how fish assemblages vary with elevation among regional elevation bands, and how these changes are related to four environmental clines and to changes in the distribution, habitat use, and the morphology of fish species. Using a standardized field sampling technique, we assessed three different diversity and two structural assemblage measures across six regional elevation bands located in the northern Andes (Colombia). Each species was assigned to a functional group based on its body shape, habitat use, morphological, and/or behavioral adaptations. Additionally, at each sampling site, we measured four environmental variables. Our analyses showed: (1) After a monotonic decrease in species richness, we detected an increase in richness in the upper part of the gradient; (2) diversity patterns vary depending on the diversity measure used; (3) diversity patterns can be attributed to changes in species distribution and in the richness and proportions of functional groups along the regional elevation gradient; and (4) diversity patterns and changes in functional groups are highly correlated with variations in environmental variables, which also vary with elevation. These results suggest a novel pattern of variation in species richness with elevation: Species richness increases at the headwaters of the northern Andes owing to the cumulative number of endemic species there. This highlights the need for large-scale studies and has important implications for the aquatic conservation of the region. We perform the first regional analysis of elevation diversity gradients in freshwater fish. For this we used 141 localities between 250 and 2533 m a.s.l. from seven sub-regions in the Northern Andes, Colombia. The results of our study suggest a novel pattern of variation in species richness with elevation: species richness increases at the headwaters of the Northern Andes owing to the cumulative number of endemic species there.

Description: An output-feedback control strategy for pollution mitigation in combined sewer networks is presented. The proposed strategy provides means to apply model-based predictive control to large-scale sewer networks, in-spite of the lack of measurements at most of the network sewers. In previous works, the authors presented a hybrid linear control-oriented model for sewer networks together with the formulation of Optimal Control Problems (OCP) and State Estimation Problems (SEP). By iteratively solving these problems, preliminary Receding Horizon Control with Moving Horizon Estimation (RHC/MHE) results, based on flow measurements, were also obtained. In this work, the RHC/MHE algorithm has been extended to take into account both flow and water level measurements and the resulting control loop has been extensively simulated to assess the system performance according different measurement availability scenarios and rain events. All simulations have been carried out using a detailed physically-based model of a real case-study network as virtual reality. This article is protected by copyright. All rights reserved.

Description: Host species vary in their propensity to become infected by and transmit parasites, and this variation in host competency can influence parasite transmission within host communities. Host competency is often attributed to morphological, physiological, and behavioral defenses of hosts, but hosts commonly have an additional, lesser studied form of protection: defensive symbionts. For instance, snails are facultatively defended by ectosymbiotic oligochaete worms ( Chaetogaster limnaei ) that consume free-living trematode parasites, bacteria protect amphibians from the fungus that causes chytridiomycosis, and ants protect plants from herbivores. In addition to reducing infection on their hosts, defensive symbionts may influence parasite transmission to other hosts by redirecting parasites toward other hosts and/or removing parasites from the system. We explored these possibilities by examining the relative roles of community composition and the presence of defensive symbionts ( C. limnaei ) in determining trematode infection intensity among second intermediate host communities composed of snails ( Helisoma trivolvis ) and tadpoles ( Rana catesbeiana ). Parasites were dramatically more successful at infecting snails than tadpoles, which led to more total parasites in host communities where snails were present. In addition, defensive symbionts substantially reduced snail infection intensity and thus reduced the total number of parasites in communities containing symbiont-defended snail hosts. Neither host community composition nor the presence of defensive symbionts on snails influenced individual tadpole infection in our experiments. Therefore, in our experiments, second intermediate host community structure did not influence individual host tadpole infection risk, but did influence total parasite transmission.

Description: Studying proteins from the M. tuberculosis H37Rv envelop is important for understanding host-pathogen interaction regarding bacterial infection and survival within a host; such knowledge is indispensable regarding studies aimed at developing drugs or vaccines against tuberculosis, a disease which continues to cause more than one million deaths worldwide every year. The present work presents a study of the Rv3705c protein which has been described as being an outer protein. Several servers and bioinformatics' tools were used for predicting its location on mycobacterial surface and a 3D model of the protein was obtained which was then compared to experimental circular dichroism results for its peptides. PCR assays were used for corroborating rv3705c gene presence and transcription in a laboratory strain and immunoblotting and electron microscopy were used for confirming protein localisation on cell envelop. Receptor-ligand assays revealed two peptides having high specific binding (HABPs); peptide 38485 ( 121 DRAFHRVVDRTVGTSGQTTA 140 ) bound to both cell lines used as infection target (U937 and A549 epithelial cell line-derived macrophages) and 38488 ( 181 RLRENVLLQAKVTQSGNAGP 200 ) bound to U937 cells. It was found that peptide 38485 provided significant inhibition regarding mycobacterial entry to both cell lines in in vitro assays. These results led to proposing peptide 38485 as one of the epitopes to be used in future studies aimed at characterising the immune response of functionally important synthetic peptides which could be included in developing a synthetic anti-tuberculosis vaccine. This article is protected by copyright. All rights reserved

Description: Wind stress over the ocean depends on the sea surface roughness which is determined by the sea state. On one hand, underdeveloped wind seas, rougher than their fully developed counterpart, increase the drag. On the other hand, the presence of swell can modify wind stress by modifying the wind sea roughness. This latter mechanism is believed to have a great impact at high winds whenever underdeveloped local waves coexist with swell. Detailed measurements of wind stress and wavefield in fetch-limited growth conditions were made in an area subjected to strong and persistent winds. Through the analysis of wavefield observations, it is found that the presence of swell dampens the short wind waves. The observed attenuation is greater for younger wind seas and decreases as the wind waves become older. Results obtained from modeling the interaction of wind waves and the air flow above point out that the attenuation of short wind waves causes a reduction of the wave-supported stress, which in turn decreases the total wind stress.

Description: In this work, a control-oriented sewer network model is presented based on a hybrid linear modeling framework. The model equations are described independently for each network element, thus allowing the model to be applied to a broad class of networks. A parameter calibration procedure using data obtained from simulation software that solves the physically-based model equations is described and validation results are given for a case study. Using the model equations, an optimal control problem to minimize flooding and pollution is formulated to be solved by means of mixed-integer linear or quadratic programming. A receding horizon control strategy based on this optimal control problem is applied to the case study using the simulation software as a virtual reality. Results of this closed-loop simulation tests show the effectiveness of the proposed approach in fulfilling the control objectives while complying with physical and operational constraints.

Description: ABSTRACT Observations of coastal-trapped waves (CTW) are limited by instrumentation technologies, and temporal and spatial resolutions; hence their complete description is still limited. In the present work we used measurements from high frequency radio scatterometers (HFR) to analyze the subinertial dynamics of the Gulf of Tehuantepec in the Mexican Pacific, a region strongly influenced by offshore gap winds. The data showed subinertial oscillations that may be explained by poleward propagating CTWs. The oscillations showed higher coherence (95% confidence) with gap winds in the Gulfs of Papagayo and Panama than with local winds. Vertical thermocline oscillations, measured with a moored thermistor-chain, also showed subinertial oscillations coherent with Papagayo and Panama winds. The period of the observed oscillations was ~4 days, which corresponds to the inertial period of the Gulf of Panama. This suggests that inertial oscillations generated by offshore wind outbursts over Panama may have traveled northward along the coastal shelf, and were detected as surface current pulses by the HFR installed approximately 2000 km further north in the Gulf of Tehuantepec. To further explore the presence of CTWs, the 4 day band-pass filtered currents measured by the HFR were analyzed using empirical orthogonal functions. We found that the first mode behaved like a CTW confined to the shelf break. Additionally, the observed oscillations were compared with baroclinic and barotropic CTW models. The results support the notion that nearly-inertial baroclinic CTWs are generated in the Gulfs of Panama and Papagayo and then propagate towards the Gulf of Tehuantepec.

Description: The 14-3-3 proteins are evolutionarily conserved acidic proteins that form a family with several isoforms in many cell types of plants and animals. In invertebrates, including dipteran and lepidopteran insects, only two isoforms have been reported. 14-3-3 proteins are scaffold molecules that form homo- or heterodimeric complexes, acting as molecular adaptors mediating phosphorylation-dependent interactions with signaling molecules involved in immunity, cell differentiation, cell cycle, proliferation, apoptosis, and cancer. Here, we describe the presence of two isoforms of 14-3-3 in the mosquito Aedes aegypti , the main vector of dengue, yellow fever, chikungunya, and zika viruses. Both isoforms have the conserved characteristics of the family: two protein signatures (PS1 and PS2), an annexin domain, three serine residues, targets for phosphorylation (positions 58, 184, and 233), necessary for their function, and nine alpha helix-forming segments. By sequence alignment and phylogenetic analysis, we found that the molecules correspond to Ɛ and ζ isoforms ( Aeae 14-3-3ε and Aeae 14-3-3ζ). The messengers and protein products were present in all stages of the mosquito life cycle and all the tissues analyzed, with a small predominance of Aeae 14-3-3ζ except in the midgut and ovaries of adult females. The 14-3-3 proteins in female midgut epithelial cells were located in the cytoplasm. Our results may provide insights to further investigate the functions of these proteins in mosquitoes.

Description: Pseudoperonospora cubensis , the causal agent of cucurbit downy mildew (CDM), is known to exhibit host specialization. The virulence of different isolates of the pathogen can be classified into pathotypes based on their compatibility with a differential set composed of specific cucurbit host types. However, the genetic basis of host specialization within P. cubensis is not yet known. Total genomic DNA extracted from nine isolates of P. cubensis collected from 2008 to 2013 from diverse cucurbit host types ( Cucumis sativus, C. melo var.  reticulatus, Cucurbita maxima , C. moschata , C. pepo, and Citrullus lanatus ) in the United States were subjected to whole-genome sequencing. Comparative analysis of these nine genomes confirmed the presence of two distinct evolutionary lineages (lineages I and II) of P. cubensis . Many fixed polymorphisms separated lineage I comprising isolates from Cucurbita pepo , C. moschata, and Citrullus lanatus from lineage II comprising isolates from Cucumis spp. and Cucurbita maxima . Phenotypic characterization showed that lineage II isolates were of the A1 mating type and belonged to pathotypes 1 and 3 that were not known to be present in the United States prior to the resurgence of CDM in 2004. The association of lineage II isolates with the new pathotypes and a lack of genetic diversity among these isolates suggest that lineage II of P. cubensis is associated with the resurgence of CDM on cucumber in the United States. Cucurbit downy mildew caused by Pseudoperonospra cubensis has resurged around the world in the last two decades. Comparative analysis of nine genomes confirmed the presence of two distinct evolutionary lineages. Lineage II that lacked genetic diversity had pathoytpes that have never been reported in the United States hinting to possible cause of the resurgence.

Description: Threshold is defined as the point where small changes in an environmental driver produce large responses in the ecosystem. Generalized additive models (GAMs) were used to estimate the thresholds and contribution of key dynamic physical variables in terms of phytoplankton production and variations in biomass in the tropical-subtropical Pacific Ocean off Mexico. The statistical approach used here showed that thresholds were shallower for primary production than for phytoplankton biomass (pycnocline 〈 68 m and mixed layer 〈 30 m vs. pycnocline 〈 45 m and mixed layer 〈 80 m), but were similar for absolute dynamic topography and Ekman pumping (ADT 〈 59 cm and EkP 〉 0 cm d -1 vs. ADT 〈 60 cm and EkP 〉 4 cm d -1 ). The relatively high productivity on seasonal (spring) and interannual (La Niña 2008) scales were linked to low ADT (45-60 cm), and shallow pycnocline depth (9-68 m), and mixed layer (8-40 m). Statistical estimations from satellite data indicated that the contribution of ocean circulation to phytoplankton variability was 18% (for phytoplankton biomass), and 46% (for phytoplankton production). Although the statistical contribution of models constructed with in-situ integrated chlorophyll- a and primary production data was lower than the one obtained with satellite data (11%), the fits were better for the former, based on the residual distribution. The results reported here suggest that estimated thresholds may reliably explain the spatial-temporal variations of phytoplankton in the tropical-subtropical Pacific Ocean off the coast of Mexico.