División Icnología

100 Ma sweat bee nests reported herein are the oldest evidence of crown bees. A new phylogeny for short-tongued bees, calibrated with these nests dated with 40 Ar/ 39 Ar, attests for the first time for a late Albian rapid diversification of bees along with angiosperms. Such hypothesis lacked paleontological support until this study. The new ichnospecies Cellicalichnus krausei, which was found along with wasp trace fossils and new beetle trace fossils in the Castillo Formation of Patagonia, represents typical Halictini nests composed of sessile cells that are attached to main tunnels. According to geological, paleosol, paleobotanical, and ichnological data, bees, and angiosperms cohabited in an inland and dry environment comparable to an open dry woodland or savanna, under warm-temperate and semiarid-subhumid climate, in the Southern Hemisphere by the Albian.

Independently, Roselli (1939) and Sauer (1955) described and named similar fossil brood balls from the Paleogene of Uruguay (Devincenzia murguiai) and from the Quaternary of Ecuador (Coprinisphaera ecuadoriensis), respectively. In their contributions, they illustrated and described fossil brood balls characterized by the presence of a medium-sized hole piercing the wall of spherical to sub-spherical chambers. Newly collected brood balls from palaeosols of the Cangahua Formation (Ecuador), and other previously deposited in ichnological collections from Ecuador, Uruguay, and Argentina, including type material, were revised to update Coprinisphaera ichnotaxonomy. Coprinisphaera ecuadoriensis Sauer (1955) is a subjective junior synonym of Coprinisphaera murguiai (Roselli, 1939). Coprinisphaera murguiai sensu Laza, 2006 (non Roselli, 1939) is in turn a new ichnospecies named herein Coprinisphaera lazai isp. n. Additionally, a new ichnospecies, named herein as Coprinisphaera kitu isp. n.., was found in the Cangahua Formation. It is represented by a spherical to sub-spherical chamber having a discrete wall, with a crown composed of a hemispherical structure on one pole. The statistical analysis of the size of the two ichnospecies found in the Cangahua Formation suggests that C. kitu and C. murguiai may represent two stages (closed and emerged balls, respectively) of a unique original morphology (C. kitu) and producer. There are no extant dung beetle species that construct brood balls with a morphology similar to that of C. kitu. The producer of C. kitu would be the recently described fossil Phanaeini, Phanaeus violetae. Phytoliths extracted from infillings of closed C. kitu revealed that Poaceae were mostly included in the diet of the herbivores that produced the dung. Considering the vertebate fossil record for the Pleistocene Cangahua Formation, ground sloths, mastodons, and horses could have been the dung providers. The record of Tombownichnus plenus, Lazaichnus fistulosus, and Castrichnus incolumis suggests the presence of cleptoparasites and detritivores in the dung community. Cangahua sediments accumulated in a volcaniclastic, intermontane setting located at 2500-2900 m.a.s.l. and under fluctuating syneruptive conditions. Changes in facies associations and palaeosol types enable to distinguish three stages in evolution of sedimentation and landscapes. Calcic Andisols, andic Aridisols, and andic Mollisols, in the upper section, are the pedotypes that more commonly include Coprinisphaera. The intravolcanic environments where dung beetles, and probably large herbivores, better developed were temperate, seasonal, semiarid to subhumid, grasslands and wooded grasslands. They were covered by ashfalls reworked by wind and minor volcaniclastic flows.

A new type of trace fossil from the Lower Cretaceous of Patagonia that may record the oldest evidence of insect agriculture is represented by biconvex, sub-spherical, carbonate balls composed of a dense mass of rhizoliths. The best preserved balls show an external wall, a tunnel entrance, and vertical, large rhizoliths crossing from top to base, from which a mass of smaller rhizoliths arise. In some cases there is a pelletal surface texture in internal layers of the wall. Some specimens show meniscate tubes attributed to organisms different than the constructors of the chambers, probably attracted by the original organic matter. Micromorphology, analyzed by thin sections and SEM, shows strong evidence of high fungal activity associated to the original roots. Four different hypotheses are analyzed to explain the origin of the balls. The less probable ones are either that the balls were produced only by a self induced and localised overgrowth of secondary and tertiary rootlets from a group of neighbouring primary roots, or that they were crayfishes' feeding chambers. Rhizolith arrangement, as well as other characters, essentially rule out both hypotheses. The hypotheses involving social insects, termites and ants, are more risky, considering the lack of support from the body fossil record, the biogeography of these extant insects, and particularly the lack of definitive evidence of discrete fungus or bacterial gardens in the balls. However, the trace fossils described herein partially resemble the nests and behaviour of the African termite Sphaerothermes sphaerothorax, particularly because of the presence of roots inside a thick lined chamber excavated around them to cultivate bacterial combs. The ant origin of these balls is at least a hypothesis to explore considering the size, shape, wall, entrance tunnel, presence of traces of associated organisms, and particularly roots. The roots and wall relate these balls to hypothesised scenarios for the origin of fungus agriculture in ants. One hypothesis suggests that primitive Attini developed fungus agriculture from the habit of feeding on fungi associated with roots (mycorrhizae) and still other proposes that adventitious fungi on nest walls were responsible for the arise of fungiculture. The balls would supply physical evidence that by the lower Cretaceous some social insects excavated chambers around uncut roots, which in turn provided optimal conditions for fungi development. These rhizolith balls possibly constitute the oldest physical evidence for the origin of fungiculture in social insects, and represent a critical contribution of ichnology to this hot topic intensively discussed on the basis of a scattered body fossil record and molecular phylogeny.

Traces within traces is a new ichnological field that is meant to shed light on significative palaeoecological aspects. Dung beetle fossil brood balls (Coprinisphaera ispp.), from the Middle Eocene-Lower Miocene Sarmiento Formation of Patagonia, Argentina, show two different trace fossils excavated in its infillings and ⁄ or wall that reveal the presence and relationships among different components of past dung communities. Tombownichnus pepei n. isp. is represented by elongated pits, circular to elliptical in crosssection, occurring in the centre or beside ovoid mounds in the internal surface of the Coprinisphaera wall. These traces record the activity of cleptoparasites, such as other dung beetles or flies, whose larvae were probably carried passively with the dung for provisions. Tombownichnus pepei would represent the pupation chambers excavated by full grown larvae in the Coprinisphaera wall after completing their development inside provisioned dung. The other trace fossil, Lazaichnus fistulosus is represented by circular to subcircular borings occurring in Coprinisphaera walls, in connection with an internal gallery in their infillings. Its connection also with meniscate burrows and chambers in the surrounding palaeosol attributable to aestivation chambers of earthworms revealed that these organisms would have been active cleptoparasites or detritivores in dung beetle fossil brood balls.

El uso de los lenguajes interpretados ha venido en crecimiento y cuyos máximos representantes son los lenguajes usados para el desarrollo web entre estos Ruby, Python, PHP (se interpreta del lado del servidor), JavaScript y otros como Perl, Smalltalk, MATLAB, Mathematica (el que usan en Wolfram Alpha). Básicamente un lenguaje interpretado es aquel en el cual sus instrucciones o más bien el código fuente, escrito por el programador en un lenguaje de alto nivel, es traducido por el interprete a un lenguaje entendible para la máquina paso a paso, instrucción por instrucción. El proceso se repite cada vez que se ejecuta el programa el código en cuestión.

Ya no es una novedad los cambios que las Nuevas Tecnologías han producido en la Educación. En los últimos tiempos y en forma acelerada la introducción de las Tecnologías de la Comunicación y la Información en los procesos de enseñanza y aprendizaje ha tenido un desarrollo bien heterogéneo. Las causas de estos diferentes recorridos son variadas y pueden ir desde los distintos soportes tecnológicos con que cada escuela ha contado históricamente hasta el interés por el desarrollo de proyectos dentro de esta línea. Dentro de estos recorridos tampoco resultan menores las resistencias naturales que se generan en algunos grupos de personas por la introducción de dichas tecnologías, que suelen presentarse en una fase inicial y luego van disipándose a medida que se incrementa el conocimiento sobre las herramientas informáticas.

The aim of this study was to characterize new nanoparticles (NPs) containing chitosan (CS), or CS/cyclodextrin (CDs), and evaluate their potential for the oral delivery of the peptide glutathione (GSH). More precisely, NP formulations composed of CS, CS/a-CD and CS/sulphobutyl ether-b-cyclodextrin (SBE 7mb-CD) were investigated for this application. CS/CD NPs showed particle sizes ranging from 200 to 500 nm. GSH was loaded more efficiently in CS/SBE 7m -b-CD NPs by forming a complex between the tripeptide and the CD. X-ray Photoelectron Spectroscopy (XPS) analysis suggested that GSH is located in the core of CS/SBE 7m -b-CD NPs and that it is almost absent from the NP surface. Release studies performed in vitro at pH 1.2 and pH 6.8 showed that NP release properties can be modulated by selecting an appropriate CD. Transport studies performed in the frog intestine model confirmed that both CS and CS/CD nanoparticles could induce permeabilization of the intestinal epithelia. However, CS/SBE 7m -b-CD NPs provided absorption-enhancing properties in all segments of the duodenum, whereas CS NPs effect was restricted to the first segment of the duodenum. From the data obtained, we believe that CS/CD nanoparticles might represent an interesting technological platform for the oral administration of small peptides.