PCR-mediated chromosome splitting (PCS) was developed in the yeast Saccharomyces cerevisiae. It is based on homologous recombination and enables division of a chromosome at any point to form two derived and functional chromosomes. However, because of low homologous recombination activity, PCS is limited to a single site at a time, which makes the splitting of multiple loci laborious and time-consuming. Here we have developed a highly efficient and versatile chromosome engineering technology named CRISPR-PCS that integrates PCS with the novel genome editing CRISPR/Cas9 system. This integration allows PCS to utilize induced double strand breaks to activate homologous recombination. CRISPR-PCS enhances the efficiency of chromosome splitting approximately 200-fold and enables generation of simultaneous multiple chromosome splits. We propose that CRISPR-PCS will be a powerful tool for breeding novel yeast strains with desirable traits for specific industrial applications and for investigating genome function.
Recently, applications of light-emitting diodes (LEDs) for enhancing the efficiency of photosynthesis have attracted the attentions by many researchers and agriculturalists. In the present study, we proposed both empirical (experimental) and simulative evaluations of chlorophyll-targeting monochromic and white fluorescence-type LEDs as the light sources for algal photosynthesis based on the evolution of O2 by Synechocystis sp. PCC6803.
Edaphic specialization is one of the main drivers of plant diversification and has multifaceted effects on population dynamics. Carex angustisquama is a sedge plant growing only on heavily acidified soil in solfatara fields, where only extremophytes can survive. Because of the lack of closely related species in similar habitats and its disjunct distribution, the species offers ideal settings to investigate the effects of adaptation to solfatara fields and of historical biogeography on the genetic consequences of plant edaphic specialization to solfatara fields. Here, genome‐wide single nucleotide polymorphisms were used to reveal the phylogenetic origin of C. angustisquama, and 16 expressed sequence tag–simple sequence repeat markers were employed to infer population demography of C angustisquama. Molecular phylogenetic analysis strongly indicated that C. angustisquama formed a monophyletic clade with Carex doenitzii, a species growing on nonacidified soil in the sympatric subalpine zone. The result of population genetic analysis showed that C. angustisquama has much lower genetic diversity than the sister species, and notably, all 16 loci were completely homozygous in most individuals of C. angustisquama. Approximate Bayesian computation analysis supported the model that assumed hierarchical declines of population size through its evolutionary sequence. We propose that the edaphic specialist in solfatara fields has newly attained the adaptation to solfatara fields in the process of speciation. Furthermore, we found evidence of a drastic reduction in genetic diversity in C. angustisquama, suggesting that the repeated founder effects associated with edaphic specialization and subsequent population demography lead to the loss of genetic diversity of this extremophyte in solfatara fields.
Premise of the StudyExpressed sequence tag–simple sequence repeat (EST‐SSR) markers were developed for Carex angustisquama (Cyperaceae) to investigate the evolutionary history of this plant that is endemic to solfatara fields in northern Japan.Methods and ResultsUsing RNA‐Seq data generated by the Illumina HiSeq 2000, 20 EST‐SSR markers were developed. Polymorphisms were assessed in C. angustisquama and the closely related species C. doenitzii and C. podogyna. In C. angustisquama, many loci were monomorphic within populations; the average number of alleles ranged from one to five, and levels of expected heterozygosity ranged from 0.000 to 0.580, while all markers were polymorphic in a population of C. doenitzii. This indicates that low genetic polymorphism of C. angustisquama is likely due to the species’ population dynamics, rather than to null alleles at the developed markers.ConclusionsThese markers will be used to assess genetic diversity and structure and to investigate evolutionary history in future studies of C. angustisquama and related species.
Arnica mallotopus Makino is a perennial herb of Asteraceae endemic to Honshu and its adjacent islands in Japan (Ohashi et al., 2016). The species occurs preferentially on rock outcrops along mountain streams that are well watered by snowmelt and are often maintained by natu-
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