Origin of the Anomalous Electrical Transports in Quasi-One-Dimensional Ta2NiSe7.

Exploration of exotic transport behavior is of great interest and importance for revealing the properties of the CDW phase of quasi-one-dimensional Ta2NiSe7. We report the anisotropic electrical transport properties of Ta2NiSe7 single crystals in the CDW phase. The anisotropic constant (γ = ρb/ρc) increased rapidly at TCDW = 60 K upon cooling. The results of the Hall resistivity show that both the concentrations and mobilities of carriers change abruptly at TCDW. The out-of-plane AMR exhibits C2 and C4 symmetry components while the in-plane AMR exhibits C2, C4, and C6 at the CDW state. The planar Hall effect is observed in Ta2NiSe7 at low temperature, which is suggested to originate from the anisotropic orbital magnetoresistance. The calculated results show that the Fermi surface of Ta2NiSe7 was slightly reconstructed due to the CDW transition. This work highlights the enhancement of Fermi surface anisotropy during CDW formation and provides a novel approach to study the CDW materials.

Origin of the Anomalous Electrical Transport Behavior in Fe-Intercalated Weyl Semimetal Td -MoTe2.

Weyl semimetal Td -MoTe2 has recently attracted much attention due to its intriguing electronic properties and potential applications in spintronics. Here, Fe-intercalated Td -Fex MoTe2 single crystals (0 < x < 0.15 ) are grown successfully. The electrical and thermoelectric transport results consistently demonstrate that the phase transition temperature TS is gradually suppressed with increasing x. Theoretical calculation suggests that the increased energy of the Td phase, enhanced transition barrier, and more occupied bands in 1T' phase is responsible for the suppression in TS . In addition, a ρα -lnT behavior induced by Kondo effect is observed with x ≥ 0.08, due to the coupling between conduction carriers and the local magnetic moments of intercalated Fe atoms. For Td -Fe0.15 MoTe2 , a spin-glass transition occurs at ≈10 K. The calculated band structure of Td -Fe0.25 MoTe2 shows that two flat bands exist near the Fermi level, which are mainly contributed by the dyz and d x 2 - y 2 ${{\rm{d}}_{{x^2} - {y^2}}}$ orbitals of the Fe atoms. Finally, the electronic phase diagram of Td -Fex MoTe2 is established for the first time. This work provides a new route to control the structural instability and explore exotic electronic states for transition-metal dichalcogenides.

Identification and Characterization of ATP-Binding Cassette Transporters in Chlamydomonas reinhardtii.

Microalgae are promising microorganisms used to produce value-added products or to develop sustainable approaches for environmental remediation. The ATP-binding cassette proteins (ABCs) of Chlamydomonas reinhardtii have been characterized as indispensable transporters for CO2 concentrating mechanism, lipid biosynthesis, and heavy metal sequestration. However, few microalgal ABC proteins have been studied compared with higher plants or non-photosynthetic microorganisms. This study performed a genome-wide, evolutionary, and transcriptomic survey of C. reinhardtii ABC proteins (CrABCs). A total of 75 CrABCs were identified and classed into eight ABC subfamilies, from ABCA to ABCI. We found that no whole or partial genome duplication events occurred in C. reinhardtii after the ancient endosymbiosis events, but gene duplications occurred in a small range of chromosomal regions, which forced ABC family expansion. Abundant light, abscisic acid, and jasmonic acid response cis-elements were mapped in the CrABC promoters, coinciding with the evolutionary history of hormone signaling in Chlorophyta. The expression survey under light/dark rhythms revealed a close bond of CrABCs with cell division and development. A broad study of CrABCs supported their expected roles in heavy metal detoxification, lipid metabolism, and environmental adaptation. Moreover, the evolutionary and expression survey predicted the functions of unknown CrABCs, which are elaborated in the text. Two half-size CrABCGs-CrABCG3 and CrABCG26-were described as plasma-membrane transporters that might participate in lipidic compound secretion. This study provides fundamental and exhaustive information about CrABCs, which are indispensable for the functional elucidation of ABC proteins in microalgae.

Increased Lipids in Chlamydomonas reinhardtii by Multiple Regulations of DOF, LACS2, and CIS1.

Microalgal lipids are essential for biofuel and dietary supplement production. Lipid engineering for higher production has been studied for years. However, due to the complexity of lipid metabolism, single-gene engineering gradually encounters bottlenecks. Multiple gene regulation is more beneficial to boosting lipid accumulation and further clarifying the complex regulatory mechanism of lipid biosynthesis in the homeostasis of lipids, carbohydrates, and protein metabolism. Here, three lipid-related genes, DOF, LACS2, and CIS, were co-regulated in Chlamydomonas reinhartii by two circles of transformation to overexpress DOF and knock down LACS2 and CIS simultaneously. With the multiple regulations of these genes, the intracellular lipids and FA content increased by 142% and 52%, respectively, compared with CC849, whereas the starch and protein contents decreased by 45% and 24%. Transcriptomic analysis showed that genes in TAG and FA biosynthesis were up-regulated, and genes in starch and protein metabolism were down-regulated. This revealed that more carbon precursor fluxes from starch and protein metabolism were redirected towards lipid synthesis pathways. These results showed that regulating genes in various metabolisms contributed to carbon flux redirection and significantly improved intracellular lipids, demonstrating the potential of multiple gene regulation strategies and providing possible candidates for lipid overproduction in microalgae.