This paper describes one neurotoxin and three cytolysins isolated from the venom of the Caribbean box jellyfish Carybdea marsupialis. To assess the cytolytic and neurotoxic activity of the nematocyst venom, several bioassays were carried out, and to evaluate the effect of the toxin, the dose causing 50% lethality (LD(50)) was determined in vivo using sea crabs (Ocypode quadrata). The proteins with neurotoxic and cytolytic effects were isolated using low-pressure liquid chromatography. The fraction containing the neurotoxic activity was analyzed by SDS-PAGE and showed a single protein band with an apparent molecular weight of 120 kDa (CmNt). To demonstrate the neurotoxic activity of this protein, a small fraction of the purified protein was injected into a crab, and the typical convulsions, paralysis, and death provoked by neurotoxins were observed. Three fractions containing cytolysins had protein bands in SDS PAGE with apparent molecular weights of 220, 139, and 36 kDa, and their cytolytic activity was confirmed with the haemolysis assay.

Today, the picture of an evolutionary tree is a very well-known visual image. It is almost impossible to think of the ancestry and relationships of living beings without it. As natural history museums play a major role in the public understanding of evolution, they often present a wide variety of evolutionary trees. However, many studies have shown (Baum and Offner 2008;Baum et al. 2005;Catley and Novick 2008;Evans 2009;Gregory 2008;Matuk 2007;Meir et al. 2007b;Padian 2008) that even though evolutionary trees have the potential to engage visitors of natural history museums with the phenomena of evolution, many of them unwittingly might lead to misunderstandings about the process. As valuable research and educational institutions, one of the museum's important missions should be the careful design of their exhibits on evolution considering, for example, common preconceptions visitors often bring, such as the notion that evolution is oriented from simple toward complex organisms (incarnating the idea of a single ladder of life amidst the extraordinary diversity of organisms) and that humans are at the pinnacle of the evolutionary story, as well as naïve interpretations of phylogenies. Our aim in this article is to show from history where many of these misunderstandings come from and to determine whether five important Western natural history museums inadvertently present "problematic" evolutionary trees (which might lead to non-scientific notions).

This paper provides an overview of the state of Mexican genetics and biomedical knowledge during the second half of the twentieth century, as well as its impact on the visual representation of human groups and racial hierarchies, based on social studies of scientific imaging and visualization (SIV) and theoretical concepts and methods. It also addresses the genealogy and shifts of the concept of race and racialization of Mexican bodies, concluding with the novel visual culture that resulted from genetic knowledge merged with the racist phenomenon in the second half of the twentieth century in Mexico.

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The authors of this manuscript are interested mainly in meta-scientific studies, particularly in historical reflection on biology. Species in the Age of Discordance being the main theme of this special issue, and taking inspiration from the idea that "biological lineages move through time, space and each other", we find it thought-provoking to show that just as biological lineages have histories, diverse conceptual categories have also been historically constituted. Moreover their visual representations have been discordant at different levels, such as the concepts of species and race. This article presents how the struggle to achieve a human taxonomy in late nineteenth-and early twentieth-century Europe had a fundamental visual component that reflects the discussions and theories that led to important discordances in the racial classification of Homo sapiens and in other species of hominins. Using as main visual artifacts the representation of evolutionary trees, the painting of castes, as well as the natural classification tree of the Mexican naturalist Manuel Ortega from 1877, the authors will show on the one hand how European ideas about human species and race in the scientific mainstream were deployed in the very distinctive situations of Mexico. On the other hand, it will be shown that visual culture was fundamental and decisive in establishing and disseminating scientific accounts of species and race, and how both concepts have interacted in the visual characterization of human diversity, both to define it and to restrain it.

This article uses a review of a number of tree diagrams to highlight how the fact that Darwin was to choose the metaphor of a tree to describe evolutionary relationships between organisms should come as no great surprise, as the tree already occupied an important position in European iconography. In the review of some of the uses of a "tree" to represent different types of relationships in the pre-Darwinian age, we want to illustrate two basic issues. One particularly important issue is that Darwin had the insight of including various symbols and metaphors that were already being used to represent different aspects of the living world in his own theory of evolution, particularly the general metaphor of branching and rebranching. The other is that when Darwin published On the Origin of Species in 1859, people were already familiar with the idea of a tree to represent genealogy. This may have been an important factor in people's familiarity with evolutionary diagrams and also in strongly associating them with religious metaphors. KEYWORDS:Evolutionary tree; The tree of life; Evolution; Darwin; Genealogy. RESUMEN:En este artículo queremos mostrar mediante una revisión de algunos diagramas en forma de árbol, que el hecho de que Darwin escogiera la metáfora de un árbol para representar relaciones evolutivas entre los organismos no resulta enteramente sorpresivo, ya que la figura arbórea ya guardaba una posición importante en la tradición iconográfica europea. En la revisión de algunos usos del "árbol" para representar diferentes clases de relaciones en la época pre-darwiniana, queremos ilustrar dos cuestiones fundamentales. Una particularmente importante es que Darwin tuvo la brillantez de incorporar una variedad de sím-bolos y metáforas que ya estaban siendo usadas para representar diferentes aspectos del mundo vivo, en su propia teoría de la evolución, particularmente la metáfora general de la ramificación y re-ramificación. La otra es que cuando Darwin publicó El Origen de las especies en 1859, la gente ya estaba familiarizada con el tema del "árbol" para representar genealogías. Esto pudo haber sido importante para sentirse familiarizado con los diagramas evolutivos y para aceptarlos como entidades reales, también para asociarlos fuertemente con metáforas religiosas.

El tema de la evolución de los seres vivos resulta fundamental tanto para la biología como para la educación científica. En este trabajo se presenta una parte de un proyecto de investigación mayor que busca analizar tanto la presencia, como el estado de la teoría de la evolución biológica en los libros de texto de educación básica mexicanos, desde que se creó la Secretaría de Educación Pública en 1921.El análisis histórico y de los contenidos del tema de la evolución biológica en los libros de texto mexicanos ha sido poco tratado. El presente texto se enfoca en un periodo interesante y de particular importancia en la historia educativa de México: el proyecto de la educación socialista, que fue propuesto e implementado brevemente durante la década de 1930. Las autoras ponen particular énfasis en la ideología socialista detrás de la enseñanza de la evolución, puesto que es lo distintivo del periodo y del proyecto.

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