Francisco Carrapiço

Symbiogenesis: the hidden face of Constantin Merezhkowsky.

Constantin Merezhkowsky is celebrated today for his theory of symbiogenesis, postulated in the early decades of the twentieth century, particularly that chloroplasts were symbiotic cyanophytes (cyanobacteria). While biologists point singularly to what they see as his heroic achievement, its neglect and subsequent rediscovery, we introduce a broader and much more complex perspective on his science, his troubled life and career. We present a view of Merezhkowsky as zoologist, anthropologist, botanist, philosopher, and novelist. We explain the genesis of his theory of the origin of chloroplasts and of nucleus and cytoplasm as symbionts, as well as his depiction of the geo-chemical context of the origins and early evolution of life on earth. We also disclose his sordid social and political activities, his eugenics and racist writings, his paedophilia, and his metaphysics. Finally, we describe the context of his elaborate suicide in 1921.

Azolla as a Superorganism. Its Implication in Symbiotic Studies

The symbiosis history begun many million years ago, probably even before the first manifestation of life arose in our planet (Carrapico et al., 2007). But it was only in the nineteenth century with the presentation in 1867, by the Swiss botanist Simon Schwendener, of the “dual hypothesis” related to the lichens structure, that this “real story” had a scientific starting point for society (Boucher, 1985; Sapp, 1994; Honegger, 2000).

Morphological and genetic diversity of the family Azollaceae inferred from vegetative characters and RAPD markers

Family Azollaceae has seven species with a controversial taxonomy. The identification of species without reproductive structures relies on vegetative characters but some are variable, leading to misinterpretations. The molecular methods may be helpful, but until now, they did not provide a conclusive Azolla taxonomy. Therefore, we studied the family Azollaceae at vegetative and molecular levels. Analysis of vegetative, random amplified polymorphic DNA (RAPD) and combined data showed a comparable grouping of the Azolla species in two main clusters: cluster I, referred to as section Rhizosperma (A. pinnata and A. nilotica) and cluster II, referred to as section Azolla (A. filiculoides, A. microphylla, A. caroliniana and A. mexicana), with the exception of A. rubra, which clustered differently depending on the method. All the Azolla species were distinguished by the 13 polymorphic vegetative characters, the 211 RAPD markers or the combined data, with the latest showing the highest discrimination. The Shannon Index diversity was greater with RAPD (2.276) than with vegetative characters (0.054), highlighting the higher discriminating power of the molecular data. The partitioning of diversity was, as expected, high among species for all the types of data and low within species, with the lowest diversity obtained for morphological data. Both data sets (vegetative and RAPD) allowed the distinction of all the species and their clustering into sections Rhizosperma and Azolla, suggesting this as the most correct for this family. The dendrogram from the combined data was the most accurate, highlighting the benefit of integrating different types of data to study the family Azollaceae.

How symbiogenic is evolution

When new entities are formed by the integration of individual organisms, these new entities possess characteristics which go beyond the sum of the individual properties of each element of the association, resulting in the development of new attributes and capacities as an integrated whole. In this process, these new entities also agglutinate and dynamize synergies not present in the individual organisms. In this sense, evolution is a dynamic process that evolves not in the way of perfection or progress, but in the way of adaptation to new conditions. Symbiogenesis, as an evolutionary mechanism, allows a coherent conceptual rupture with some evolutionary ideas of the past and, at the same time, shows and builds a new approach to life, based on solid evolutionary ideas, expanding evolution to an adequate level of integration with the more recent data in biology. These ideas and concepts should be integrated in a post-neodarwinian approach to evolution that needs further attention from the scientific community. The development of a Symbiogenic Theory of Evolution could contribute toward a new epistemological approach of the symbiotic phenomenon in the evolutionary context. This, in our point of view, could be the beginning of a new paradigm in science that rests almost unexplored.

Taxonomic re-evaluation of the Azolla genus in Portugal

ABSTRACT The Portuguese and the European Flora refer to the presence of two or three Azolla species in Portugal: A. filiculoides Lam., A. caroliniana Willd. and/or Azolla mexicana Presl., the latter included in the last edition of Flora Europaea. In the present work, the taxonomy of Azolla species is reviewed using the two most important characters that can distinguish between these two/three species: papillae in the dorsal leaf lobe and perine architecture of the megaspore apparatus. Other characteristics, such as the hyaline border cells of the dorsal leaf lobes and the number of glochidia septa in microsporangium massulae, are also used. All the Azolla specimens, collected from several locations in Portugal, were identified as Azolla filiculoides Lam. This identification disagrees with previous published reports on Azolla taxonomy in Portugal as well as with herbarium identification.

Azolla-anabaena-bacteria system as a natural microcosm

Azolla is an aquatic fern that contains a permanent endosymbiotic prokaryotic community (cyanobacteria and bacteria) inside of the cavity in the leaf dorsal lobe of the pteridophyte. This is a unique situation and can be seen as a microcosm inside of an organism and also can be considered a good example of a living model for biological and environmental studies. These symbionts are specific of this symbiosis and lives immobilized in a mucilaginous fibrillar network, which fills part of the cavity. The symbionts works as immobilized organisms in a natural system that can be used as a model for biotechnological research and in biologically based life support systems. The nature and the complexity of this system is simultaneously a reference and a challenge for the research in the communication between the two levels of nature organization (microcosm and mesocosm), and can also be used as a reference for the design of new environmental engineered symbiotic systems that include man as a prelude to life in space.

Functional anatomy of the midgut gland of Gammarus locusta (Crustacea: Amphipoda)

A description of the midgut gland of Gammarus locusta with the aim of using this organ as a complementary tool in ecotoxicological studies was made. The hepatopancreas is composed of two pairs of blind-ending tubular structures. The thickness and length of these tubules were ∼50 μm and 5 mm, respectively, in adult males (10-12 mm length). The distal part of each tubule is characterized by non-vacuolated E-cells typically exhibiting a relatively high nuclear to cytoplasmatic ratio. The epithelium of the remaining tubules is characterized by abundant columnar R- and F-cells, both ∼40 μm long. Large vacuolated B-cells (∼60 μm length) were very common along the midgut gland but seemed to increase in number in the proximal region of each tubule. An SEM examination revealed a delicate network of muscle fibres that limits the organ.

Histochemistry of simple hairs from the foliar cavities of Azolla filiculoides

Abstract The foliar cavities of the water fern Azolla filiculoides have as many as 20 – 25 simple hairs (SH) protruding from the epidermal cells that delimit the cavity. These SH have a transfer-like ultrastructure normally associated with secretion of metabolites. The aim of this study was the chemical characterization of the compounds that accumulated in the SH of the zones F1-12 (from 1st to 12th leaves) and F13 (from 13th until the end of the sporophyte) throughout the seasons during a 1-year study. The histochemical tests show that the vacuoles of simple hairs contain a mixture of lipids, unsaturated lipids, polysaccharides, polyphenols (o-dihydroxyphenols, phenols with free ‒OH groups and tannins) and alkaloids or alkaloid-like compounds. These substances do not show seasonal variation, having been present throughout the one-year study. The histochemical analysis demonstrated that the SH always have a variety of metabolites. The function within the Azolla-Anabaena symbiosis is not known.

Culture of Azolla filiculoides in artificial conditions

Abstract Azolla filiculoides showed a planar development in four culture media, but with overlapping of sporophytes after 28 days, and curled roots in all cases except for IRRI2. The difference in biomass between the media IRRI2 and IRRI1‐Fe10x was statistically significant at Days 14, 21 and 28 by ANOVA. Medium IRRI2 gave the highest duplication time.

A Symbiogenic Way in the Origin of Life

The scientific question relating to the origin of life remains, so far, without a consensual answer. The advanced theories essentially highlight a Darwinist or neo-Darwinist approach to the problem, preventing a more global and comprehensive overview, which could be made possible through consideration of other t principles, namely symbiogenic ones. The notion of a dynamic and systemic Earth, with natural interdependent and interrelated subsystems, with life in all environments and ecological niches, even in the extreme ones, reveal an evolution of life in close relation with the primitive Earth’s geochemical contexts. Under extreme and adverse environmental conditions, life chooses cooperative and synergistic strategies, establishing symbiotic relationships. The extremophile organisms, besides broadening the limits of the known life, instigate new reflections about life beyond Earth. Astrobiology is a privileged eye scoping the very dimensions of the origin, evolution and distribution of life in the Universe. The study presently being carried out, which concerns, among others, extremophile organisms and the search for earthly extreme extraterrestrial environments, analogous to the primitive ones on Earth, is of high importance. Besides characterizing the Earth’s primitive environments, it also reinforces the exogenous models of the origin of life.