A transcriptomic analysis of gene expression in the venom gland of the snake Bothrops alternatus (urutu)

<p>Abstract</p> <p>Background</p> <p>The genus <it>Bothrops </it>is widespread throughout Central and South America and is the principal cause of snakebite in these regions. Transcriptomic and proteomic studies have examined the venom composition of several species in this genus, but many others remain to be studied. In this work, we used a transcriptomic approach to examine the venom gland genes of <it>Bothrops alternatus</it>, a clinically important species found in southeastern and southern Brazil, Uruguay, northern Argentina and eastern Paraguay.</p> <p>Results</p> <p>A cDNA library of 5,350 expressed sequence tags (ESTs) was produced and assembled into 838 contigs and 4512 singletons. BLAST searches of relevant databases showed 30% hits and 70% no-hits, with toxin-related transcripts accounting for 23% and 78% of the total transcripts and hits, respectively. Gene ontology analysis identified non-toxin genes related to general metabolism, transcription and translation, processing and sorting, (polypeptide) degradation, structural functions and cell regulation. The major groups of toxin transcripts identified were metalloproteinases (81%), bradykinin-potentiating peptides/C-type natriuretic peptides (8.8%), phospholipases A₂(5.6%), serine proteinases (1.9%) and C-type lectins (1.5%). Metalloproteinases were almost exclusively type PIII proteins, with few type PII and no type PI proteins. Phospholipases A₂were essentially acidic; no basic PLA₂were detected. Minor toxin transcripts were related to L-amino acid oxidase, cysteine-rich secretory proteins, dipeptidylpeptidase IV, hyaluronidase, three-finger toxins and ohanin. Two non-toxic proteins, thioredoxin and double-specificity phosphatase Dusp6, showed high sequence identity to similar proteins from other snakes. In addition to the above features, single-nucleotide polymorphisms, microsatellites, transposable elements and inverted repeats that could contribute to toxin diversity were observed.</p> <p>Conclusions</p> <p><it>Bothrops alternatus </it>venom gland contains the major toxin classes described for other <it>Bothrops </it>venoms based on trancriptomic and proteomic studies. The predominance of type PIII metalloproteinases agrees with the well-known hemorrhagic activity of this venom, whereas the lower content of serine proteases and C-type lectins could contribute to less marked coagulopathy following envenoming by this species. The lack of basic PLA₂agrees with the lower myotoxicity of this venom compared to other <it>Bothrops </it>species with these toxins. Together, these results contribute to our understanding of the physiopathology of envenoming by this species.</p

Estas son algunas de las habilidades blandas demandadas en Colombia

Este producto forma parte de una serie de infografías de divulgación científica que buscan reseñar algunas de las investigaciones más importantes en las que ha tenido participación la Universidad EAFIT, publicadas en las revistas especializadas más prestigiosas del mund

Population dynamics and integrated control of the damson-hop aphid Phorodon humuli (Schrank) on hops in Spain

The hop aphid Phorodon humuli (Schrank) (Hemiptera: Aphididae) is a serious pest in most areas where hops are grown. A field trial was performed on a hop yard throughout 2002, 2003 and 2004 in León (Spain) in order to analyse the population development of Phorodon humuli and its natural enemies, as well as to determine the most effective integrated program of insecticide treatments. The basic population development pattern of P. humuli was similar in the three years: the population peaked between mid to late June, and then decreased in late June/early July, rising again and reaching another peak in mid-July, after which it began to decline, rising once more in late August; this last rise is characteristic of Spain and has not been recorded in the rest of Europe. The hop aphid�s main natural enemy found on the leaves was Coccinella septempunctata (Coleoptera: Coccinellidae). The multiple regression analysis showed that aphids are positively related with the presence of beetle eggs and mean daily temperatures and negatively related with maximum daily temperature integral above 27°C in plots without insecticide treatment. The most effective program of insecticide (imidacloprid) treatments consisted of an initial treatment in June and a second treatment in the second half of July or at the beginning of August. However, a single treatment in June would be sufficient when in this last period the maximum daily temperatures were higher than 27°C for at least 15 days, avoiding in this way the harmful effects of imidacloprid on predators

Respuesta poblacional del pulgón del lúpulo, "Phorodon humuli" (Schrank, 1801) (Hemiptera, Aphididae) a tratamientos aficidas en diferentes épocas

Se estudia la dinámica poblacional del pulgón del lúpulo, Phorodon humuli (Schrank), en plantas de lúpulo sometidas a tratamientos aficidas en diferentes épocas durante el año 2002. En cada planta se realizan tres medidas: a 2, 3,25 y 6 m de altura, obteniéndose el número de pulgones por m² de superficie de trepa. En las plantas que no recibieron tratamientos el esquema de la dinámica fue: ligero descenso de la población a finales de junio-principios de julio; pico de la población a sobre mediados de julio; caída de la población hasta finales de agosto, momento en que empieza a ascender de nuevo. En los conos se encontró una pequeña población de pulgones durante todo el muestreo. En el resto de los grupos, que recibieron tratamientos, la dinámica poblacional fue: si se trató en junio, no se produjo el pico inicial de junio y los picos de julio y agosto fueron más pequeños; si se trató en julio o en agosto, no se observó el pico de agosto. Los tratamientos aficidas más adecuados para el año 2002 hubieran sido, probablemente: un primer tratamiento en junio y uno segundo en la segunda mitad de julio - principios de agosto. Dado el creciente interés del Control Integrado, sería interesante conocer el umbral económico de tratamiento de P. humuli. Este estudio sienta las bases para su cálculo

Within-field distribution of the damson-hop aphid Phorodon humuli (Schrank) (Hemiptera: Aphididae) and natural enemies on hops in Spain

A field trial was performed in a hop yard throughout 2002, 2003 and 2004 in order to determine the within-field distribution of Phorodon humuli (Schrank) (Hemiptera: Aphididae) and its natural enemies. The distribution of P. humuli was directly affected by the position of the hop plants in the garden, with significantly higher concentrations of aphids (p=0.0122 in 2002 and p=0.0006 in 2003) observed along the edge. However, in 2004 the plants located on the marginal plots had similar populations to those on the more inner plots. This can be explained by a higher wind speed which made it more difficult to land on edge plants first. The hop aphid’s main natural enemy was Coccinella septempunctata (Coleoptera: Coccinellidae), whose population was greatest where the aphids were most abundant with a significantly greater number of eggs (p=0.0230) and adults (p=0.0245) in 2003. Lacewing eggs were also frequently observed, with a significantly higher population (p=0.0221 in 2003 and p=0.0046 in 2004) where the aphid numbers were high. The number of winged aphids was greatest towards the margins of the garden in 2003. It is argued that the spatial distribution of the hop aphid and its natural enemies could be used to plan a sampling program and to estimate the population densities of these insects for use in integrated pest management programs

Timescale dependent sign of amorphous titanium dioxide thermo-optic coefficient

We report on the thermo-optic properties of electron-beam evaporated amorphous titanium dioxide (TiO 2 ) at different timescales. We investigate the thermo-optic response of TiO 2 from static regime down to the micro-second regime by applying Joule heating on hybrid metallo-dielectric integrated Mach-Zehnder interferometers. We show that amorphous TiO 2 exhibits a very large negative thermo-optical coefficient in the range of -6.5×10 −4 K −1 at 1550 nm at typical timescales of a few seconds. Such a slow thermo-optic response is consistent with an organic origin of amorphous TiO 2 negative thermo-optic coefficient. However, when observed at the micro-second timescale, we show that the same amorphous TiO 2 has a positive thermo-optic coefficient, just like many other materials. Based on our results, TiO 2 can be conveniently deployed in energy-effective integrated optic devices by taking into account the specific multi-timescale thermo-optic properties of this material

Inline Photothermal Surface Plasmon Detector Integrated in Titanium Dioxide Waveguides

Densely integrated photonic integrated circuits (PICs) require efficient solutions for monitoring the light intensity on chip in order to implement control and configuration operations to set and stabilize the working point of the circuit. To this end, waveguides supporting the propagation of surface plasmon polaritons (SPPs) are good candidates to realize smallfootprint light detectors. In this work, we report on the realization of an in-line Surface Plasmon Detector (SPD) that exploits the photothermal effect to monitor the optical power in a titanium dioxide (TiO2) optical waveguide. Detailed design guidelines are provided to maximize the responsivity of the SPD, taking into account the effects of the metal geometry on the coupling between the dielectric and plasmonic modes, the power dissipated in the metal, and the equivalent thermal resistance of the structure. Experimental validation of the proposed device is provided demonstrating an ultra-compact 1.6-mu m-long SPD operating at a wavelength of 1550 nm with a sensitivity of-20 dBm and a bandwidth higher than 100 kHz. The proposed device concept can be ported to generic dielectric platforms and to other wavelength ranges where SPP propagation is supported