Space use and genetic structure do not maintain color polymorphism in a species with alternative behavioral strategies

Space use including territoriality and spatial arrangement within a population can reveal important information on the nature, dynamics, and evolutionary maintenance of alternative strategies in color polymorphic species. Despite the prevalence of color polymorphic species as model systems in evolutionary biology, the interaction between space use and genetic structuring of morphs within populations has rarely been examined. Here, we assess the spatial and genetic structure of male throat color morphs within a population of the tawny dragon lizard, Ctenophorus decresii. Male color morphs do not differ in morphology but differ in aggressive and antipredator behaviors as well as androgen levels. Despite these behavioral and endocrine differences, we find that color morphs do not differ in territory size, with their spatial arrangement being essentially random with respect to each other. There were no differences in genetic diversity or relatedness between morphs; however, there was significant, albeit weak, genetic differentiation between morphs, which was unrelated to geographic distance between individuals. Our results indicate potential weak barriers to gene flow between some morphs, potentially due to nonrandom pre‐ or postcopulatory mate choice or postzygotic genetic incompatibilities. However, space use, spatial structure, and nonrandom mating do not appear to be primary mechanisms maintaining color polymorphism in this system, highlighting the complexity and variation in alternative strategies associated with color polymorphism.     

Solution Radioactivated by Hadron Radiation Can Increase Sister Chromatid Exchanges

When energetic particles irradiate matter, it becomes activated by nuclear reactions. Radioactivation induced cellular effects are not clearly understood, but it could be a part of bystander effects. This investigation is aimed at understanding the biological effects from radioactivation in solution induced by hadron radiation. Water or phosphate buffered saline was activated by being exposed to hadron radiation including protons, carbon- and iron-ions. 1 mL of radioactivated solution was transferred to flasks with Chinese hamster ovary (CHO) cells cultured in 5 mL of complete media. The induction of sister chromatid exchanges (SCE) was used to observe any increase in DNA damage responses. The energy spectrum and the half-lives of the radioactivation were analyzed by NaI scintillation detector in order to identify generated radionuclides. In the radioactivated solution, 511 keV gamma-rays were observed, and their half-lives were approximately 2 min, 10 min, and 20 min. They respectively correspond to the beta+ decay of ¹⁵O, ¹³N, and ¹¹C. The SCE frequencies in CHO cells increased depending on the amount of radioactivation in the solution. These were suppressed with a 2-hour delayed solution transfer or pretreatment with dimethyl sulfoxide (DMSO). Our results suggest that the SCE induction by radioactivated solution was mediated by free radicals produced by the annihilated gamma-rays. Since the SCE induction and DMSO modulation are also reported in radiation-induced bystander effects, our results imply that radioactivation of the solution may have some contribution to the bystander effects from hadron radiation. Further investigations are required to assess if radioactivation effects would attribute an additional level of cancer risk of the hadron radiation therapy itself.     

A low-spin iron complex in human melanoma and rat hepatoma cells and a high-spin iron(II) complex in rat hepatoma cells.

Human melanoma and rat hepatoma cells cultured in the presence of low concentrations (2.5 microM) of low-molecular-weight iron (Fe) chelates and Fe-transferrin complexes have been studied with 57Fe M?ssbauer spectroscopy. The spectra show that holoferritin is only a minor fraction of the total iron present in the cells. The major form of Fe was in a low-spin state unlike the high-spin Fe(III) found in ferritin. Only about 10% of the Fe could be attributed to ferritin. In addition, the hepatoma cells had a high-spin Fe(II) spectral component which made up about 20% of the Fe present.     

Protein-protein cross-linking of the 50 S ribosomal subunit of Escherichia coli using 2-iminothiolane. Identification of cross-links by immunoblotting techniques

We have investigated the protein-protein cross-links formed within the 50 S subunit of the Escherichia coli ribosome using 2-iminothiolane as the cross-linking reagent. The members of the cross-links have been identified by immunoblotting from one-dimensional and two-dimensional diagonal sodium dodecyl sulfate-polyacrylamide gels using antisera specific for the individual ribosomal proteins. This method also allowed a quantitation of the yield of cross-linking for each cross-link. A total of 14 cross-links have been identified: L1-L33, L2-L9, L2-L9-L28, L3-L19, L9-L28, L13-L21, L14-L19, L16-L27, L17-L30, L17-L32, L19-L25, L20-L21, L22-L32, and L23-L34. Our results are compared with those of Traut and coworkers (Traut, R. R., Tewari, D. S., Sommer, A., Gavino, G. R., Olson, H. M., and Glitz, D. G. (1986) in Structure, Function and Genetics of Ribosomes (Hardesty, B. and Kramer, G., eds) pp. 286-308, Springer-Verlag, New York). Our cross-linking data allow us to propose the approximate locations of eight proteins of the 50 S ribosomal subunit that so far have not been localized by immunoelectron microscopy and they thus contribute considerably to our knowledge of ribosome structure.     

A recombination event excludes the ROM1 locus from the Best's vitelliform macular dystrophy region

Best's vitelliform macular degeneration has been genetically linked to chromosome 11. Subsequently, the disease locus has been refined to an interval between D11S903 and PYGM and, more recently, between D11S986 and D11S480. The gene encoding ROM1, a photoreceptor-specific membrane protein, has been independently mapped within the Best's disease region and has thus become a strong candidate for the Best's disease gene. In this study, we have mapped ROM1 relative to Best's disease and the loci D11S986, UGB (uteroglobin), and PYGM (human muscle glycogen phosphorylase) in recombinant Best's disease chromosomes. We demonstrate that UGB is localized proximal to ROM1 and that both UGB and ROM1 recombine with the disease phenotype. Thus, this analysis excluded ROM1 as the Best's disease gene.     

A comparison of the nitrogen metabolic networks of Kluyveromyces marxianus and Saccharomyces cerevisiae

In grape must, nitrogen is available as a complex mixture of various compounds (ammonium and amino acids). Wine yeasts assimilate these multiple sources in order to suitably fulfil their anabolic requirements during alcoholic fermentation. Nevertheless, the order of uptake and the intracellular fate of these sources are likely to differ between strains and species. Using a two-pronged strategy of isotopic filiation and RNA sequencing, the metabolic network of nitrogen utilization and its regulation in Kluyveromyces marxianus were described, in comparison with those of Saccharomyces cerevisiae. The data highlighted differences in the assimilation of ammonium and arginine between the two species. The data also revealed that the metabolic fate of certain nitrogen sources differed, thereby resulting in the production of various amounts of key wine aroma compounds. These observations were corroborated by the gene expression analysis.