Characterization of six microsatellite markers in Trillium camschatcense using a dual‐suppression‐polymerase chain reaction technique

Trillium camschatcense is a herbaceous perennial plant distributed in Hokkaido and northern Honshu, Japan. Geographical variations in the breeding system (partial selfing or obligate outcrossing) are reported in the populations of Hokkaido. We isolated six polymorphic microsatellite loci from this species. The number of allele per locus ranged from four to 12, whereas the expected heterozygosities ranged from 0.69 to 0.83. These markers may allow further investigations to reveal the evolutionary and ecological processes of mating system in T. camschatcense.     

Cobalt‐Free High‐Capacity Ni‐Rich Layered Li[Ni0.9Mn0.1]O2 Cathode

Li[Ni_0.9Co_0.1]O₂ (NC90), Li[Ni_0.9Co_0.05Mn_0.05]O₂ (NCM90), and Li[Ni_0.9Mn_0.1]O₂ (NM90) cathodes are synthesized for the development of a Co‐free high‐energy‐density cathode. NM90 maintains better cycling stability than the two Co‐containing cathodes, particularly under harsh cycling conditions (a discharge capacity of 236 mAh g^?1 with a capacity retention of 88% when cycled at 4.4 V under 30 °C and 93% retention when cycled at 4.3 V under 60 °C after 100 cycles). The reason for the enhanced stability is mainly the ability of NM90 to absorb the strain associated with the abrupt anisotropic lattice contraction/extraction and to suppress the formation of microcracks, in addition to enhanced chemical stability from the increased presence of stable Mn⁴⁺. Although the absence of Co deteriorates the rate capability, this can be overcome as the rate capability of the NM90 approaches that of the NCM90 when cycled at 60 °C. The long‐term cycling stability of NM90 is confirmed in a full cell, demonstrating that it is one of the most promising Co‐free cathodes for high‐energy‐density applications. This study not only provides insight into redefining the role of Mn in a Ni‐rich cathode, it also represents a clear breakthrough in achieving a commercially viable Co‐free Ni‐rich layered cathode.     

New Class of Ni‐Rich Cathode Materials Li[NixCoyB1−x−y]O2 for Next Lithium Batteries

A new class of layered cathodes, Li[Ni_xCo_yB_1?x?y]O₂ (NCB), is synthesized. The proposed NCB cathodes have a unique microstructure in which elongated primary particles are tightly packed into spherical secondary particles. The cathodes also exhibit a strong crystallographic texture in which the a–b layer planes are aligned along the radial direction, facilitating Li migration. The microstructure, which effectively suppresses the formation of microcracks, improves the cycling stability of the NCB cathodes. The NCB cathode with 1.5 mol% B delivers a discharge capacity of 234 mAh g^?1 at 0.1 C and retains 91.2% of its initial capacity after 100 cycles (compared to values of 229 mAh g^?1 at 0.1 C and 78.8% for pristine Li[Ni_0.9Co_0.1]O₂). This study shows the importance of controlling the microstructure to obtain the required cycling stability, especially for Ni‐rich layered cathodes, where the main cause of capacity fading is related to mechanical strain in their charged state.     

Co‐suppression in Pyropia yezoensis (Rhodophyta) Reveals the Role of PyLHCI in Light Harvesting and Generation Switch

The red macroalga Pyropia yezoensis is an economically important seaweed widely cultured in Asian countries and is a model organism for molecular biological and commercial research. This species is unique in that it utilizes both phycobilisomes and transmembrane light‐harvesting proteins as its antenna system. Here, one of the genes of P. yezoensis (PyLHCI) was selected for introduction into its genome to overexpress PyLHCI. However, the co‐suppression phenomenon occurred. This is the first documentation of co‐suppression in algae, in which it exhibits a different mechanism from that in higher plants. The transformant (T1) was demonstrated to have higher phycobilisomes and lower LHC binding pigments, resulting in a redder color, higher sensitivity to salt stress, smaller in size, and slower growth rate than the wildtype (WT). The photosynthetic performances of T1 and WT showed similar characteristics; however, P700 reduction was slower in T1. Most importantly, T1 could release a high percentage of carpospores in young blades to switch generation during its life cycle, which was rarely seen in WT. The co‐suppression of PyLHCI revealed its key roles in light harvesting, stress resistance, and generation alternation (generation switch from gametophytes to sporophytes, and reproduction from asexual to sexual).     

Evading resistance to gene drives

Gene drives offer the possibility of altering and even suppressing wild populations of countless plant and animal species, and CRISPR technology now provides the technical feasibility of engineering them. However, population-suppression gene drives are prone to select resistance, should it arise. Here, we develop mathematical and computational models to identify conditions under which suppression drives will evade resistance, even if resistance is present initially. Previous models assumed resistance is allelic to the drive. We relax this assumption and show that linkage between the resistance and drive loci is critical to the evolution of resistance and that evolution of resistance requires (negative) linkage disequilibrium between the two loci. When the two loci are unlinked or only partially so, a suppression drive that causes limited inviability can evolve to fixation while causing only a minor increase in resistance frequency. Once fixed, the drive allele no longer selects resistance. Our analyses suggest that among gene drives that cause moderate suppression, toxin-antidote systems are less apt to select for resistance than homing drives. Single drives of moderate effect might cause only moderate population suppression, but multiple drives (perhaps delivered sequentially) would allow arbitrary levels of suppression. The most favorable case for evolution of resistance appears to be with suppression homing drives in which resistance is dominant and fully suppresses transmission distortion; partial suppression by resistance heterozygotes or recessive resistance are less prone to resistance evolution. Given that it is now possible to engineer CRISPR-based gene drives capable of circumventing allelic resistance, this design may allow for the engineering of suppression gene drives that are effectively resistance-proof.     

[PSI+] turns 50

abstract

The year 2015 sees the fiftieth anniversary of the publication of a research paper that underpins much of our understanding of fungal prion biology, namely “ψ, a cytoplasmic suppressor of super-suppressor in yeast” by Brian Cox. Here we show how our understanding of the molecular nature of the [PSI⁺] determinant evolved from an ‘occult’ determinant to a transmissible amyloid form of a translation termination factor. We also consider the impact studies on [PSI] have had – and continue to have - on prion research. To demonstrate this, leading investigators in the yeast prion field who have made extensive use of the [PSI⁺] trait in their research, provide their own commentaries on the discovery and significance of [PSI].     

Automated analysis of courtship suppression learning and memory in Drosophila melanogaster

Study of the fruit fly, Drosophila melanogaster, has yielded important insights into the underlying molecular mechanisms of learning and memory. Courtship conditioning is a well-established behavioral assay used to study Drosophila learning and memory. Here, we describe the development of software to analyze courtship suppression assay data that correctly identifies normal or abnormal learning and memory traits of individual flies. Development of this automated analysis software will significantly enhance our ability to use this assay in large-scale genetic screens and disease modeling. The software increases the consistency, objectivity, and types of data generated.     

黄瓜抗黑星病相关基因的差异表达分析

以抗黑星病黄瓜材料HX1为试材,接种黑星病菌（Cladosporium cucumerinum）2h、8h、20h、32h和72h的叶片作为试验方（Tester）,相应的未接种叶片作为对照方（Driver）,利用SSH技术,构建了黑星病菌侵染初期的正向和反向cDNA-SSH文库。用巢式引物PCR检测插入片段,获得了200个阳性克隆,通过测序,除去重复序列,共得到105个Unique ESTs。与非冗余蛋白数据库进行BLASTx比对,结果显示,17条ESTs未找到同源序列,88条非重复序列和已知基因的同源性较高,占全部ESTs序列的83.8%,其中86条ESTs与非冗余蛋白数据库已知功能的蛋白具有高度的相似性。结合高密度点阵膜杂交差异筛选,阳性率为75.0%。经初步分析这些序列的功能,差异表达的ESTs功能涉及能量和基础代谢、信号转导、蛋白和核酸代谢、光合作用及逆境中特异表达的基因等方面。为研究黄瓜抗黑星病基因提供了依据。