A network analysis of early arthropod evolution and the potential of the primitive.

It is often thought that the primitive is simpler, and that the complex is generated from the simple by some process of self-assembly or self-organization, which ultimately consists of the spontaneous and fortuitous collision of elementary units. This idea is included in the Darwinian theory of evolution, to which is added the competitive mechanism of natural selection. To test this view, we studied the early evolution of arthropods. Twelve groups of arthropods belonging to the Burgess Shale, Orsten Lagerstätte, and extant primitive groups were selected, their external morphology abstracted and codified in the language of network theory. The analysis of these networks through different network measures (network parameters, topological descriptors, complexity measures) was used to carry out a Principal Component Analysis (PCA) and a Hierarchical Cluster Analysis (HCA), which allowed us to obtain an evolutionary tree with distinctive/novel features. The analysis of centrality measures revealed that these measures decreased throughout the evolutionary process, and led to the creation of the concept of evolutionary developmental potential. This potential, which measures the capacity of a morphological unit to generate changes in its surroundings, is concomitantly reduced throughout the evolutionary process, and demonstrates that the primitive is not simple but has a potential that unfolds during this process. This means for us the first empirical evolutionary evidence of our theory of evolution as a process of unfolding.

A network analysis of crab metamorphosis and the hypothesis of development as a process of unfolding of an intensive complexity.

Development has intrigued humanity since ancient times. Today, the main paradigm in developmental biology and evolutionary developmental biology (evo-devo) is the genetic program, in which development is explained by the interplay and interaction of genes, that is, by the action of gene regulatory networks (GRNs). However, it is not even clear that a GRN, no matter how complex, can be translated into a form. Therefore, the fundamental enigma of development still remains: how is a complex organism formed from a single cell? This question unfolded the historical drama and the dialectical tension between preformation and epigenesis. In order to shed light on these issues, I studied the development of crabs (infraorder Brachyura), as representative of the subphylum Crustacea, using network theory. The external morphology of the different phases of brachyuran metamorphosis were modeled as networks and their main characteristics analyzed. As one could expect, the parameters usually regarded as indicative of network complexity, such as modularity and hierarchy, increased during development. However, when more sophisticated complexity measures were tested, it was evidenced that whereas a group of complexity measures increased during development, another group decreased. This led to consider that two kinds of complexities were being measured. I called them intensive and extensive complexity. In view of these results, I propose that crab development involves a passage from an intensive to an extensive complexity. In other words, crab development can be interpreted as a process of unfolding of an intensive, preexistent complexity.

Bovine viral diarrhea virus structural protein E2 as a complement regulatory protein.

Bovine viral diarrhea virus (BVDV) is a member of the genus Pestivirus, family Flaviviridae, and is one of the most widely distributed viruses in cattle worldwide. Approximately 60 % of cattle in endemic areas without control measures are infected with BVDV during their lifetime. This wide prevalence of BVDV in cattle populations results in significant economic losses. BVDV is capable of establishing persistent infections in its host due to its ability to infect fetuses, causing immune tolerance. However, this cannot explain how the virus evades the innate immune system. The objective of the present work was to test the potential activity of E2 as a complement regulatory protein. E2 glycoprotein, produced both in soluble and transmembrane forms in stable CHO-K1 cell lines, was able to reduce complement-mediated cell lysis up to 40 % and complement-mediated DNA fragmentation by 50 %, in comparison with cell lines not expressing the glycoprotein. This work provides the first evidence of E2 as a complement regulatory protein and, thus, the finding of a mechanism of immune evasion by BVDV. Furthermore, it is postulated that E2 acts as a self-associated molecular pattern (SAMP), enabling the virus to avoid being targeted by the immune system and to be recognized as self.

La vida como actividad normativa y auto-realización: debate en torno al concepto de normatividad biológica en Goldstein y Canguilhem / Life as regulatory activity and self-realization: debate surrounding the concept of biological regulation in Goldstein and Canguilhem

La influencia de Kurt Goldstein en el pensamiento de Georges Canguilhem se extendió a lo largo de toda su obra. El presente trabajo pretende recuperar esta relación con el objeto de realizar un estudio de la norma como nexo o conexión entre el concepto y la vida. En consecuencia, este trabajo será una reflexión sobre el planteamiento de la vida como actividad normativa y autorealización. Para ello, será necesario resignificar los conceptos de salud y enfermedad, y atravesar el camino que va de uno a otro. Al final de este camino, se encontrará que estos conceptos permiten explicar la identidad entre el concepto y la vida, lo cual conduce a la conclusión inesperada que la cura es, en definitiva, autocuración.

The influence of Kurt Goldstein on the thinking of Georges Canguilhem extended throughout his entire work. This paper seeks to examine this relationship in order to conduct a study of the norm as a nexus or connection between the concept and life. Consequently, this work will be a reflection on the approach to life as a regulatory activity and self-realization. For this, it will be necessary to redefine the concepts of health and disease, and make a crossover between the two. At the end of this trajectory, it will be found that these concepts can explain the identity between the concept and life, which leads to the unexpected conclusion that the cure is ultimately self-healing.

[Life as regulatory activity and self-realization: debate surrounding the concept of biological regulation in Goldstein and Canguilhem]. / La vida como actividad normativa y auto-realización: debate en torno al concepto de normatividad biológica en Goldstein y Canguilhem.

The influence of Kurt Goldstein on the thinking of Georges Canguilhem extended throughout his entire work. This paper seeks to examine this relationship in order to conduct a study of the norm as a nexus or connection between the concept and life. Consequently, this work will be a reflection on the approach to life as a regulatory activity and self-realization. For this, it will be necessary to redefine the concepts of health and disease, and make a crossover between the two. At the end of this trajectory, it will be found that these concepts can explain the identity between the concept and life, which leads to the unexpected conclusion that the cure is ultimately self-healing.

Efficacy of a BVDV subunit vaccine produced in alfalfa transgenic plants.

Bovine viral diarrhea virus (BVDV) is considered an important cause of economic loss within bovine herds worldwide. In Argentina, only the use of inactivated vaccines is allowed, however, the efficacy of inactivated BVDV vaccines is variable due to its low immunogenicity. The use of recombinant subunit vaccines has been proposed as an alternative to overcome this difficulty. Different studies on protection against BVDV infection have focused the E2 protein, supporting its putative use in subunit vaccines. Utilization of transgenic plants expressing recombinant antigens for the formulation of experimental vaccines represents an innovative and cost effective alternative to the classical fermentation systems. The aim of this work was to develop transgenic alfalfa plants (Medicago sativa, L.) expressing a truncated version of the structural protein E2 from BVDV fused to a molecule named APCH, that target to antigen presenting cells (APCH-tE2). The concentration of recombinant APCH-tE2 in alfalfa leaves was 1 µg/g at fresh weight and its expression remained stable after vegetative propagation. A methodology based an aqueous two phases system was standardized for concentration and partial purification of APCH-tE2 from alfalfa. Guinea pigs parentally immunized with leaf extracts developed high titers of neutralizing antibodies. In bovine, the APCH-tE2 subunit vaccine was able to induce BVDV-specific neutralizing antibodies. After challenge, bovines inoculated with 3 µg of APCH-tE2 produced in alfalfa transgenic plants showed complete virological protection.

Development and validation of an ELISA for quantitation of bovine viral diarrhea virus antigen in the critical stages of vaccine production.

Bovine Viral Diarrhea Virus (BVDV) is the causative agent of a worldwide disease. The virus infects bovines of all ages, causing reproductive problems and contaminating biological products of high commercial value. The large-scale production of BVDV vaccines presents the challenge of processing antigenic proteins that are highly susceptible to the processing environment. Potency testing requires the immunization of cattle in order to determine the neutralizing antibodies titers induced by the vaccine. An alternative to the in vivo test is an in vitro measurement of key viral antigens. This paper describes the development and validation of a sandwich-type indirect ELISA that is able to detect and quantify BVDV E2 glycoprotein in live and inactivated BVDV. Validation parameters such as repeatability, intermediate precision, and reproducibility indicated that the developed ELISA constitutes an advanced tool for evaluating the BVDV antigen throughout manufacturing and vaccine release testing.

Age-related lung cell response to urban Buenos Aires air particle soluble fraction.

Exposure to particulate matter (PM) may alter lung homeostasis inducing changes in fluid balance and host defense. Bioavailability of soluble PM compounds like polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and transition metals has been shown to play a key role in lung injury. We have previously characterized the size, shape, and chemical components of urban air particles from Buenos Aires (UAP-BA) and their biological impact on lungs. Herein, we evaluate the possible toxic effect of UAP-BA-soluble fraction (UAP-BAsf) on pulmonary cells obtained from young (1-2 months old) and aged (9-12 months old) Wistar rats using phagocytosis, oxidant-antioxidant generation, and apoptosis as endpoints. UAP-BA were collected in downtown BA and residual oil fly ash (ROFA), employed as a positive control, was collected from Boston Edison Co., Mystic Power Plant, Mystic, CT, USA. Both particle-soluble fractions (sf) were employed at concentrations ranging from 0 to 100 microg/mL. UAP-BAsf and ROFAsf even at the lowest dose assayed (10 microg/mL) showed in both lung cell populations the ability to stimulate phagocytosis and increase superoxide anion (O(2)(-)) generation. Both types of air particles caused a marked intracellular oxidant stress in aged pulmonary cells that may contribute to subsequent cell activation and production of proinflammatory mediators, leading to cell dysfunction. These data suggest that the impact of UAP-BAsf on phagocytosis, oxidant radical generation, and apoptosis is clearly dependent on the maturational state of the animal and might have different mechanisms of action.