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PubMed1979

Cultivation requirements for Treponema pallidum, Mycobacterium leprae and other microbial and mammalian microaerophilic cells.

Atmospheric and biological evolution progressed simultaneously and today certain cell types flourish only at oxygen tensions which were ambient 600 million years ago, i.e., at 5 to 10 mm Hg. In man, a continuous oxygen flow at these pressures is supplied in the skin where Treponema pallidum, Mycobacterium leprae and members of the genus Rickettsia grow best. In vitro studies support the microaerophilic status of these organisms and of certain other microbial and mammalian cells. Vigorous growth in pure culture will await the development of techniques which can maintain these low oxygen tensions at the cell walls of the microbes as they replicate and consume increasing amounts of oxygen. Continuing failure to consistently isolate microbes from active lesions in patients with rheumatoid arthritis or systemic lupus erythematosus may reflect the universal absence of suitable methods for isolation of microaerophilic microbes.

Anaerobiosis↗
PubMed2003

Solar UV irradiation conditions on the surface of Mars.

The UV radiation environment on planetary surfaces and within atmospheres is of importance in a wide range of scientific disciplines. Solar UV radiation is a driving force of chemical and organic evolution and serves also as a constraint in biological evolution. In this work we modeled the transmission of present and early solar UV radiation from 200 to 400 nm through the present-day and early (3.5 Gyr ago) Martian atmosphere for a variety of possible cases, including dust loading, observed and modeled O3 concentrations. The UV stress on microorganisms and/or molecules essential for life was estimated by using DNA damaging effects (specifically bacteriophage T7 killing and uracil dimerization) for various irradiation conditions on the present and ancient Martian surface. Our study suggests that the UV irradiance on the early Martian surface 3.5 Gyr ago may have been comparable with that of present-day Earth, and though the current Martian UV environment is still quite severe from a biological viewpoint, we show that substantial protection can still be afforded under dust and ice.

Bacteriophage T7↗
PubMed2001

[Rapid determination of sex in Myocastor coypus embryos in the first stage of gestation].

The early knowledge of the sex may be crucial for the understanding of many features of ecological and evolutive biology, including offspring sex-ratio adjustment and evolution of breeding systems. In coypu (Myocastor coypus), significant variation in birth sex-ratios can be observed and selective abortion of entire litters is one of the cited mechanisms. In order to determine the sex of coypu embryos in the earlier stages of gestation (second week), we developed a molecular technique based on PCR amplification of a region of the Sry gene. These method used the combination of two sets of primers: one specific of the Y-chromosome; the other one, autosomal, is a positive control for amplification. Because of the direct amplification of embryo lysate without DNA extraction, the present sexing technique is rapid, relatively simple and inexpensive, and presents numerous advantages for the study at population scale.

Animals↗
PubMed1998

The thermodynamics and evolution of complexity in biological systems.

Recent advances in nonequilibrium thermodynamics leads to the conclusion that similar processes, constrained by the second law of thermodynamics, give rise to the emergence of structure and process in a broad class of dissipative systems. The second law suggests that, in systems moved away from equilibrium, processes can emerge so that the system organizes in a way that reduces the effect of the applied gradient. If dynamic and or kinetic conditions permit, self organization processes can be expected. As biosystems grow and develop, they should increase their total dissipation, and develop more complex structures with more energy flow, increase their cycling activity, develop greater diversity and generate more hierarchical levels. As a corollary to this general statement, biosystems which do not increase their total dissipation, are organisms dedicated to death, like observed during the aging of any biosystem. Species which survive in ecosystems are those that funnel energy into their own production and reproduction and contribute to autocatalytic processes which increase the total dissipation of the ecosystem while at same time surviving within the constraints of their changing environment. In a broad class of biosystems, stress and aging have similar thermodynamic properties and suggests common underlying principles.

Aging↗
PubMed1994

Animal lectins as self/non-self recognition molecules. Biochemical and genetic approaches to understanding their biological roles and evolution.

In recent years, the significant contributions from molecular research studies on animal lectins have elucidated structural aspects and provided clues not only to their evolution but also to their multiple biological functions. The experimental evidence has suggested that distinct, and probably unrelated, groups of molecules are included under the term "lectin." Within the invertebrate taxa, major groups of lectins can be identified: One group would include lectins that show significant homology to membrane-integrated or soluble vertebrate C-type lectins. The second would include those beta-galactosyl-specific lectins homologous to the S-type vertebrate lectins. The third group would be constituted by lectins that show homology to vertebrate pentraxins that exhibit lectin-like properties, such as C-reactive protein and serum amyloid P. Finally, there are examples that do not exhibit similarities to any of the aforementioned categories. Moreover, the vast majority of invertebrate lectins described so far cannot yet be placed in one or another group because of the lack of information regarding their primary structure. (See Table 1.) Animal lectins do not express a recombinatorial diversity like that of antibodies, but a limited diversity in recognition capabilities would be accomplished by the occurrence of multiple lectins with distinct specificities, the presence of more than one binding site, specific for different carbohydrates in a single molecule, and by certain "flexibility" of the binding sites that would allow the recognition of a range of structurally related carbohydrates. In order to identify the lectins' "natural" ligands, we have investigated the interactions between those proteins and the putative endogenous or exogenous glycosylated substances or cells that may be relevant to their biological function. Results from these studies, together with information on the biochemical properties of invertebrate and vertebrate lectins, including their structural relationships with other vertebrate recognition molecules, are discussed.

Animals↗
PubMed1982

Play in evolution, culture, and individual adaptation: implications for therapy.

In this paper human play is examined from the perspective of its role in evolution. A model of social evolution is proposed to extend the model of biological evolution and to demonstrate the central role of play in the social-evolutionary process. Since in evolution play is a mechanism for its process, it demands species members who are playful. Thus, man is a player by virtue of species membership and the evolutionary pathway of the species. The implications of this deep-seated characteristic of playfulness are discussed in terms of human development. Finally, a set of principles is derived from the evolutionary-developmental characteristics of play. Application of these principles in clinical practice is demonstrated and discussed.

Adolescent↗