Genetic variation in the emblematic Puya raimondii (Bromeliaceae) from Huascarán National Park, Peru

Puya raimondii, the giant Peruvian and Bolivian terrestrial bromeliad, is an emblematic endemic Andean species well represented in Huascarán National Park in Peru. This park is the largest reserve of puna (high altitude plateau) vegetation. The objective of this study is to report on genetic variation in populations of P. raimondii from Huascarán and neighboring areas. AFLP profiles with four selective primer combinations were retrieved for 60 individuals from different zones. Genetic variability was estimated and a total of 172 bands were detected, of which 79.1% were polymorphic loci. The results showed genetic differentiation among populations, and gene flow. A cluster analysis showed that individuals of P. raimondii populations located in different mountain systems could be grouped together, suggesting long distance dispersal. Thus, conservation strategies for P. raimondii have to take into account exchange between populations located far apart in distance in order to preserve the genetic diversity of this showy species

Impedimetric Biosensor Based on a Hechtia argentea Lectin for the Detection of Salmonella spp.

A sensitive electrochemical detection method for Salmonella spp. was described, based on the use of Hechtia argentea lectin immobilised on a screen-printed gold electrode. The lectin was extracted from Hechtia argentea, a plant belonging to the Bromeliaceae family. The lectin with molecular weight near 27.4 kDa showed selectivity towards D-mannose, contained on the lipopolysaccharide cell wall of Salmonella spp. Carbohydrate selectivity of the lectin was measured as a change in impedance with respect to concentration. The binding of the bacteria to the biosensor surface increased impedance with increasing concentrations of Salmonella spp., achieving a linear range of detection of 15–2.57 × 107 CFU mL−1, with a limit of detection of 5 CFU mL−1. Increases in impedance were measured using electrochemical impedance spectroscopy and analysed using Nyquist plots. The biosensor was applied in analysis of hen egg samples, and the results were consistent with those obtained using the official analysis methodologyS

Leaf anatomy of Tillandsia complanata Benth

Las epífitas juegan un papel importante en los bosques y selvas tropicales, y son capaces de absorber humedad del medio ambiente desarrollando para ello estructuras anatómicas particulares. Tillandsia complanata es una especie epífita que se encuentra en los bosques venezolanos. Se estudió la anatomía foliar mediante cortes a mano alzada, macerado y raspado de epidermis de material fijado en FAA. La epidermis está constituida por células rectangulares de paredes anticlinales sinuosas y engrosadas, en transcorte son alargadas tubulares con pared periclinal fina, la cutícula es delgada, y la epidermis presenta modificaciones de tipo pelo escamoso pluricelular en ambas caras, el cual consta de 4 células del disco, 8 de la periferia y aproximadamente 48 células del ala. Los estomas abaxiales son hundidos y protegidos por prolongaciones digitiformes de las células periestomáticas. El mesófilo está diferenciado en bandas de parénquima adaxial y abaxial de 3 a 4 corridas de células parenquimáticas isodiamétricas grandes; al centro se encuentra el parénquima esponjoso estrellado y fotosintetizador, alternando con el tejido vascular constituido de haces colaterales cerrados desplazados hacia la cara adaxial con doble vaina vascular, la externa parenquimática, y la interna fibrosa, a veces con extensiones hacia la epidérmis adaxial. Algunos haces se encuentran conectados entre sí[email protected]; [email protected] have an important role in tropical forests, being capable of water uptake from moisture because of special anatomical features. Tillandsia complanata is a Venezuelan epiphytic species, its leaf anatomy was studied on FAA preserved material. Free hand sectioning, tissue macerates and epidermal scrapings were made. Epidermal cells are rectangular, with thick sinuous anticlinal walls, and thin periclinal walls; cuticle is thin; the epidermis bear multicellular scaly trichomes on both surfaces. These scales have a 4 cells central disc, 8 on its periphery, and approximately 48 cells forming the wing. Abaxial stomata are sunk and protected by fingerlike appendages of the peristomatal cells. Mesophyll differentiates in adaxial and abaxial parenchymatous layers, with 3-4 large isodiametric parenchymatic cell rows, with an in-between photosynthetic spongy parenchyma that holds closed vascular bundles; these are placed towards the adaxial surface, have a double vascular sheath, the outermost layer parenchymatous, the inner one fibrous, sometimes extended to the adaxial epidermis. Some vascular bundles interconnect