Survival of micro-organisms in space

Survival of coliphageT ₁, tobacco mosaic virus (TMV) and spores ofPenicillium roqueforti Thom after direct exposure to space on board 6 balloons, 6 sounding rockets and 3 satellites is related to the numbers of solar UV photons incident during exposure. The survival followed exponential curves leading to complete inactivation. Solar ultraviolet radiation of wavelengths 2000 Å to 3000 Å appears to be the main cause of inactivation of broth suspended phage and, probably, TMV.T ₁ phage andPenicillium spores prepared in saline were also affected by radiation shorter than 2000 Å, while TMV seems to be resistant to radiation of these wavelengths. The biological effectiveness of the solar spectrum in the area between 3000 Å to 50 000 Å was not significant. Sterilization of interplanetary spacecraft appears necessary since micro-organisms can easily be shielded against lethal radiation.     

Survival of micro-organisms in space

Dried suspensions ofPenicillium roqueforti Thom, Coliphage T-1,Bacillus subtilis and tobacco mosaic virus were exposed to space on board the Gemini-IX-A and XII earth satellites and the Agena-VIII space rocket. All micro-organisms tested survived the direct exposure during the Gemini-IX-A experiment. In the Gemini-XII experiment only the T-1 phage survived the direct exposure. The survival was influenced by the suspending medium and depended on the species of the microorganism. After four months of space flight on the Agena-VIII space rocket surviving fractions between 2×10^–3 and 1.0 were found in the unopened flight container. However, micro-organisms exposed on the cover of the container during this period were completely inactivated. Shielding against solar ultraviolet radiation during flight resulted in survival of micro-organisms exceeding to that of the transport controls, and the survival was considered complete.Sterile methylcellulose collection surfaces were exposed to space on board the Gemini-IX-A and XII satellites in an attempt to collect viable micro-organisms in space. None of the collection surfaces yielded viable micro-organisms.     

Ecological determinants of life-history evolution.

Density-dependent natural selection has been studied, empirically with laboratory populations of Drosophila melanogaster. Populations kept at very high and low population density have become differentiated with respect to important fitness-related traits. There is now some understanding of the behavioural and physiological basis of these differences. These studies have identified larval competitive ability and efficiency of food utilization as traits that are negatively correlated with respect to effects on fitness. Theory that illuminates and motivates additional research with this experimental system has been lacking. Current research has focused on models that incorporate many details of Drosophila ecology in laboratory environments.     

Ecological niches and their evolution among Neotropical manakins (Aves: Pipridae)

Study of the evolution of ecological characteristics using phylogenetic information is only beginning, but several new tools and approaches open fascinating possibilities. The Pipridae is a diverse and well‐known family of frugivorous birds that are easily sampled and that are broadly distributed across many Neotropical environments, and as such are appropriate for studies of ecological niche evolution. Using known occurrences and climate and topography data sets, we modeled ecological niches for each species in the family, and carried out analyses aimed at describing ecological niches of manakins and understanding historical patterns of ecological change in the family. Most species’ ecological niches were characterized by warm and relatively humid conditions, reflecting the great diversification of the family in lowland and montane forests of western South America. Ecological niche evolution was in general conservative, with most sister species pairs being closely similar ecologically, indicating that isolation rather than adaptation to new ecological conditions has dominated the diversification in this family. Exceptions to this pattern represent interesting foci for future research, whereas studies of ecological niches focusing on past distributions of manakins will allow further biogeographic inferences.     

Periodontopathic micro-organisms in the rice rat (Oryzomys palustris)

The rice rat spontaneously develops periodontal disease, and this process can be accelerated if the animal is placed on a high sucrose diet. As the aetiological agent(s) is unknown, this study was undertaken to determine the micro-organisms associated with bone loss. Animals at weaning were placed on either a high sucrose diet or on regular rat chow and were sampled periodically for a variety of micro-organisms. Bacteroides spp., spirochetes, and Actinobacillus actinomycetemcomitans were not isolated from any animals, but fusiform-like organisms and Capnocytophaga spp. were isolated occasionally. An unidentified organism which had characteristics of both A. actinomycetemcomitans and Haemophilus aphrophilus was isolated from all animals at every sampling. Whether this organism is the primary aetiological agent of periodontal disease in the rice rat remains to be determined. Over the 12 week experimental period the animals on the high sucrose diet had significantly more exposed root surface than animals on regular rat chow.     

Ecological issues of arid forest cultivation in works of the Dzhanybek Research Station (60-year experience)

This paper presents a review of the key publications of the Dzhanybek Forest Research Station of the Russian Academy of Sciences. It highlights the vital mechanisms of artificial forest ecosystems in the process of their development under changing natural conditions and the basic applied aspects of stable protective afforestation in forestless areas.     

Multilocus molecular systematics and evolution in time and space of Calligrapha (Coleoptera: Chrysomelidae,Chrysomelinae)

Calligrapha (Coleoptera: Chrysomelidae) is a genus with species present in most of the American continent, from the Arctic polar circle to the Pampas in Argentina. In its current concept, the genus comprises some 80 species, but the diagnosis of the genus is problematic, based on a combination of potentially symplesiomorphic character states. In this study, we investigate the largest taxonomic sample of Calligrapha diversity to date (43 species) using a phylogenetic perspective based on more than 6000 molecular characters from eight genes (four mitochondrial and four nuclear) for a systematic evaluation of the genus. The analyses also include thirteen species in the closely related Zygospila (currently a subgenus of Zygogramma) to assist the systematic delimitation of Calligrapha. Partitioned and total evidence phylogenetic trees were additionally used for molecular clock analyses and dating based on standard mtDNA evolutionary rates, and for likelihood‐based inference of ancestral areas. Calligrapha and Zygospila are reciprocally paraphyletic, and our interpretation of taxonomic stability merges both taxa into a larger genus Calligrapha which plausibly originated in the dry steppes of southern North America in the Late Miocene. The genus includes a minimum of five strongly supported lineages which initially diversified in the Pliocene, fully congruent with expectations from morphology, but of uncertain mutual relationships. Only two of these lineages dispersed to South America: the group of C. polyspila right at the time of the final closure of the Isthmus of Panama in the Early Pliocene and the group of C. argus only in recent times, well in the Pleistocene. The most species‐rich lineage of Calligrapha, associated to trees and shrubs typical of riverine and lacustrine environments (as opposed to herbaceous steppe plants, generally Malvaceae and Asteraceae, for most other groups) diversified and spread in North America in the Late Pliocene. The ecological shift to a stable habitat spreading in the continent due to climate change is hypothesized as one possible explanation for the evolutionary success of this group.     

Social evolution in micro-organisms and a Trojan horse approach to medical intervention strategies

Medical science is typically pitted against the evolutionary forces acting upon infective populations of bacteria. As an alternative strategy, we could exploit our growing understanding of population dynamics of social traits in bacteria to help treat bacterial disease. In particular, population dynamics of social traits could be exploited to introduce less virulent strains of bacteria, or medically beneficial alleles into infective populations. We discuss how bacterial strains adopting different social strategies can invade a population of cooperative wild-type, considering public good cheats, cheats carrying medically beneficial alleles (Trojan horses) and cheats carrying allelopathic traits (anti-competitor chemical bacteriocins or temperate bacteriophage viruses). We suggest that exploitation of the ability of cheats to invade cooperative, wild-type populations is a potential new strategy for treating bacterial disease.     

Milestones of space medicine development in Russia (establishment and evolution of the Institute of Biomedical Problems)

This paper describes the history of the Institute of Biomedical Problems (IMBP): its birth and development. IMBP's directors were: Andrei V. Libedinsky (1963-1965), Vasily V. Parin (1965-1967), Oleg G. Gazenko (1968-1988), and Anatoly I. Grigoriev (1988 to the present). Most of the early employees of IMBP came from the USSR Air Force Institute of Aviation Medicine and the USSR Ministry of Health Institute of Biophysics. The major goals of IMBP were: development of a system of medical monitoring and support of long-duration space missions, selection and training of civilian crew members, bioengineering testing of flight equipment, and development of life support system concepts and requirements. The paper presents major results of the above research activities.     

Ecological constraints drive social evolution in the African mole-rats.

The African mole-rats (family Bathyergidae) are subterranean hystricomorph rodents occurring in a variety of habitats and displaying levels of sociality which range from solitary to eusocial, making them a unique mammalian taxonomic group to test ecological influences on sociality. Here, we use an extensive DNA-based phylogeny and comparative analysis to investigate the relationship between ecology, sociality and evolution within the family. Mitochondrial cytochrome-b and 12s rRNA trees reveal that the solitary species are monophyletic when compared to the social species. The naked mole-rat (Heterocephalus glaber) is ancestral and divergent from the Damaraland mole-rat (Cryptomys damarensis), supporting previous findings that have suggested the multiple evolution of eusociality within the family. The Cryptomys genus is species-rich and contains taxa exhibiting different levels of sociality, which can be divided into two distinct clades. A total of seven independent comparisons were generated within the phylogeny, and three ecological variables were significantly correlated with social group size: geophyte density (p < 0.05), mean months per year of rainfall greater than 25 mm (p < 0.001), and the coefficient of rainfall variation (p = 0.001). These results support the food-aridity hypothesis for the evolution of highly social cooperative behaviour in the Bathyergidae, and are consistent with the current theoretical framework for skew theory.     

The evolution of culture (or the lack thereof): mapping the conceptual space

This short essay is based on a lecture that I gave at short notice on a subject in which I am by no means an expert. The combination of lack of expertise and time for preparation, created an unexpectedly unique opportunity for thinking outside the box. I decided not to try to read up (as there was no time in any case) but instead to organize the little that I already knew about cultural evolution in a systematic schema—I attempted to create a scaffolding, on which I could hang everything I knew about cultural evolution, and hopefully, everything I might ever discover about cultural evolution in the future. I considered three dimensions of the study of cultural evolution, namely (i) the phenomenon of cultural evolution, (ii) production of knowledge in the field of cultural evolution, and (iii) the consequences or applications of an understanding of the evolution of culture.     

Characterization of the lipid-carrier involved in the synthesis of enterobacterial common antigen (ECA) and identification of a novel phosphoglyceride in a mutant of Salmonella typhimurium defective in ECA synthesis

The polysaccharide chains of enterobacterial common antigen (ECA) consist of linear trisaccharide repeat units with the structure -->3)- alpha-d-Fuc4NAc-(1-->4)-beta-d-ManNAcA-(1--> 4)-alpha-d-GlcNAc-(1-->, where Fuc4NAc is 4-acetamido-4, 6-dideoxy-d-galactose, ManNAcA is N - acetyl-d- mannosaminuronic acid, and GlcNAc is N -acetyl-d-glucosamine. The major form of ECA (ECAPG) consists of polysaccharide chains that are believed to be covalently linked to diacylglycerol through phosphodiester linkage; the phospholipid moiety functions to anchor molecules in the outer membrane. The ECA trisaccharide repeat unit is assembled as a polyisoprenyl-linked intermediate which has been tentatively identified as Fuc4NAc-ManNAcA-GlcNAc- pyrophosphorylundecaprenol (lipid III). Subsequent chain-elongation presumably occurs by a block-polymerization mechanism. However, the identity of the polyisoprenoid carrier-lipid has not been established. Accordingly, the current studies were conducted in an effort to structurally characterize the polyisoprenyl lipid-carrier involved in ECA synthesis. Isolation and characterization of the lipid carrier was facilitated by the accumulation of a ManNAcA-GlcNAc- pyrophosphorylpolyisoprenyl lipid (lipid II) in mutants of Salmonella typhimurium defective in the synthesis of TDP-Fuc4NAc, the donor of Fuc4NAc residues for ECA synthesis. Analyses of lipid II preparations by fast atom bombardment tandem mass spectroscopy (FAB-MS/MS) resulted in the identification of the lipid-carrier as the 55-carbon polyisoprenyl alcohol, undecaprenol. These analyses also resulted in the identification of a novel glycolipid which copurified with lipid II. FAB-MS/MS analyses of this glycolipid revealed its structure to be 1,2-diacyl- sn -glycero-3-pryophosphoryl-GlcNAc-ManNAcA (DGP- disaccharide). An examination of purified ECAPGby phosphorus-31 nuclear magnetic resonance spectroscopy confirmed that the polysaccharide chains are linked to diacylglycerol through phosphodiester linkage. Thus, DGP-disaccharide does not appear to be an intermediate in ECAPGsynthesis. Nevertheless, although the available evidence clearly indicate that lipid II is a precursor of DGP-disaccharide, the function of this novel glycolipid is not yet known, and it may be an intermediate in the biosynthesis of a molecule other than ECAPG.      

Neutral evolution of model proteins: diffusion in sequence space and overdispersion.

We stimulate the evolution of model protein sequences subject to mutations. A mutation is considered neutral if it conserves (1) the structure of the ground state, (2) its thermodynamic stability and (3) its kinetic accessibility. All other mutations are considered lethal and are rejected. We adopt a lattice model, amenable to a reliable solution of the protein folding problem. We prove the existence of extended neutral networks in sequence space-sequences can evolve until their similarity with the starting point is almost the same as for random sequences. Furthermore, we find that the rate of neutral mutations has a broad distribution in sequence space. Due to this fact, the substitution process is overdispersed (the ratio between variance and mean is larger than 1). This result is in contrast with the simplest model of neutral evolution, which assumes a Poisson process for substitutions, and in qualitative agreement with the biological data.