49 research outputs found
Metallosphaera sedula on a Mission – mimicking Mars in frames of the Tanpopo 4 mission
With future long-term space exploration and life detection missions on Mars, understanding the
microbial survival beyond Earth as well as the identification of past life traces on other planetary
bodies becomes increasingly important. The series of the Tanpopo space mission experiments target
a long-term exposure (one to three years) of microorganisms on the KIBO Module of the
International Space Station (ISS) in the low Earth orbit (LEO) (Kawaguchi et al., 2020; Ott et al.,
2020). In the search for possible past and/or present microbial life on Mars, metallophilic archaeal
species are of a special interest due to their inherent extraordinary characteristics.
Chemolithotrophic archaea (e.g., from the order Sulfolobales) employ a number of ancient metabolic
pathways to extract energy from diverse inorganic electron donors and acceptors. Metallosphaera
sedula, an iron- and sulfur-oxidizing chemolithotrophic archaeon, which flourishes under hot and
acidic conditions (optimal growth at 74°C and pH 2.0), was cultivated on genuine extraterrestrial
minerals (Milojevic et al., 2019; Milojevic et al., 2021) as well as synthetic Martian materials (Kölbl
et al., 2017). In all cases, M. sedula cells were able to utilize given mineral materials as the sole
energy source for cellular growth and proliferation. During the growth of M. sedula cells on these
materials, a natural mineral impregnation and encrustation of microbial cells was achieved, followed
by their preservation under the conditions of desiccation (Kölbl et al. 2020). Our studies indicate
that this archaeon, when impregnated and encrusted with minerals, withstand long-term desiccation
and can be even recovered from the dried samples to the liquid cultures (Kölbl et al., 2020). The
achieved preservation of desiccated M. sedula cells facilitated our further survivability studies with
this desiccated microorganism under simulated Mars-like environmental conditions and during the
Tanpopo-4 space exposure experiment. [...
Mouse inter-subspecific consomic strains for genetic dissection of quantitative complex traits
Consomic strains, also known as chromosome substitution strains, are powerful tools for assigning polygenes that control quantitative complex traits to specific chromosomes. Here, we report generation of a full set of mouse consomic strains, in which each chromosome of the common laboratory strain C57BL/6J (B6) is replaced by its counterpart from the inbred strain MSM/Ms, which is derived from Japanese wild mouse, Mus musculus molossinus. The genome sequence of MSM/Ms is divergent from that of B6, whose genome is predominantly derived from Western European wild mouse, Mus musculus domesticus. MSM/Ms exhibits a number of quantitative complex traits markedly different from those of B6. We systematically determined phenotypes of these inter-subspecific consomic strains, focusing on complex traits related to reproduction, growth, and energy metabolism. We successfully detected more than 200 statistically significant QTLs affecting 26 traits. Furthermore, phenotyping of the consomic strains revealed that the measured values for quantitative complex traits often far exceed the range between B6 host and MSM/Ms donor strains; this may result from segregation of alleles or nonadditive interactions among multiple genes derived from the two mouse subspecies (that is, epistasis). Taken together, the results suggest that the inter-subspecific consomic strains will be very useful for identification of latent genetic components underlying quantitative complex traits
Disruption of Genetic Interaction Between Two Autosomal Regions and the X Chromosome Causes Reproductive Isolation Between Mouse Strains Derived From Different Subspecies
Reproductive isolation that initiates speciation is likely caused by incompatibility among multiple loci in organisms belonging to genetically diverging populations. Laboratory C57BL/6J mice, which predominantly originated from Mus musculus domesticus, and a MSM/Ms strain derived from Japanese wild mice (M. m. molossinus, genetically close to M. m. musculus) are reproductively isolated. Their F(1) hybrids are fertile, but successive intercrosses result in sterility. A consomic strain, C57BL/6J-ChrX(MSM), which carries the X chromosome of MSM/Ms in the C57BL/6J background, shows male sterility, suggesting a genetic incompatibility of the MSM/Ms X chromosome and other C57BL/6J chromosome(s). In this study, we conducted genomewide linkage analysis and subsequent QTL analysis using the sperm shape anomaly that is the major cause of the sterility of the C57BL/6J-ChrX(MSM) males. These analyses successfully detected significant QTL on chromosomes 1 and 11 that interact with the X chromosome. The introduction of MSM/Ms chromosomes 1 and 11 into the C57BL/6J-ChrX(MSM) background failed to restore the sperm-head shape, but did partially restore fertility. This result suggests that this genetic interaction may play a crucial role in the reproductive isolation between the two strains. A detailed analysis of the male sterility by intracytoplasmic sperm injection and zona-free in vitro fertilization demonstrated that the C57BL/6J-ChrX(MSM) spermatozoa have a defect in penetration through the zona pellucida of eggs