Correction: TAC102 Is a Novel Component of the Mitochondrial Genome Segregation Machinery in Trypanosomes.

[This corrects the article DOI: 10.1371/journal.ppat.1005586.]

Phonons become chiral in the pseudogap phase of cuprates

The nature of the pseudogap phase of cuprates remains a major puzzle. One of its new signatures is a large negative thermal Hall conductivity κxy, which appears for dopings p below the pseudogap critical doping p∗, but whose origin is as yet unknown. Because this large κxy is observed even in the undoped Mott insulator La2CuO4, it cannot come from charge carriers, these being localized at p=0. Here we show that the thermal Hall conductivity of La2CuO4 is roughly isotropic, being nearly the same for heat transport parallel and normal to the CuO2 planes, i.e. κzy(T)≈κxy(T). This shows that the Hall response must come from phonons, these being the only heat carriers able to move as easily normal and parallel to the planes . At p>p∗, in both La1.6−xNd0.4SrxCuO4 and La1.8−xEu0.2SrxCuO4 with p=0.24, we observe no c-axis Hall signal, i.e. κzy(T)=0, showing that phonons have zero Hall response outside the pseudogap phase. The phonon Hall response appears immediately below p∗=0.23, as confirmed by the large κzy(T) signal we find in La1.6−xNd0.4SrxCuO4 with p=0.21. The microscopic mechanism by which phonons become chiral in cuprates remains to be identified. This mechanism must be intrinsic - from a coupling of phonons to their electronic environment - rather than extrinsic, from structural defects or impurities, as these are the same on both sides of p∗. This intrinsic phonon Hall effect provides a new window on quantum materials and it may explain the thermal Hall signal observed in other topologically nontrivial insulators.Center for Dynamics and Control of Material

TAC102 is a novel component of the mitochondrial genome segregation machinery in trypanosomes

Trypanosomes show an intriguing organization of their mitochondrial DNA into a catenated network, the kinetoplast DNA (kDNA). While more than 30 proteins involved in kDNA replication have been described, only few components of kDNA segregation machinery are currently known. Electron microscopy studies identified a high-order structure, the tripartite attachment complex (TAC), linking the basal body of the flagellum via the mitochondrial membranes to the kDNA. Here we describe TAC102, a novel core component of the TAC, which is essential for proper kDNA segregation during cell division. Loss of TAC102 leads to mitochondrial genome missegregation but has no impact on proper organelle biogenesis and segregation. The protein is present throughout the cell cycle and is assembled into the newly developing TAC only after the pro-basal body has matured indicating a hierarchy in the assembly process. Furthermore, we provide evidence that the TAC is replicated de novo rather than using a semi-conservative mechanism. Lastly, we demonstrate that TAC102 lacks an N-terminal mitochondrial targeting sequence and requires sequences in the C-terminal part of the protein for its proper localization

RNA-Seq analysis validates the use of culture-derived Trypanosoma brucei and provides new markers for mammalian and insect life-cycle stages

Abstract Background Trypanosoma brucei brucei, the parasite causing Nagana in domestic animals, is closely related to the parasites causing sleeping sickness, but does not infect humans. In addition to its importance as a pathogen, the relative ease of genetic manipulation and an innate capacity for RNAi extend its use as a model organism in cell and infection biology. During its development in its mammalian and insect (tsetse fly) hosts, T. b. brucei passes through several different life-cycle stages. There are currently four life-cycle stages that can be cultured: slender forms and stumpy forms, which are equivalent to forms found in the mammal, and early and late procyclic forms, which are equivalent to forms in the tsetse midgut. Early procyclic forms show coordinated group movement (social motility) on semi-solid surfaces, whereas late procyclic forms do not. Results RNA-Seq was performed on biological replicates of each life-cycle stage. These constitute the first datasets for culture-derived slender and stumpy bloodstream forms and early and late procyclic forms. Expression profiles confirmed that genes known to be stage-regulated in the animal and insect hosts were also regulated in culture. Sequence reads of 100–125 bases provided sufficient precision to uncover differential expression of closely related genes. More than 100 transcripts showed peak expression in stumpy forms, including adenylate cyclases and several components of inositol metabolism. Early and late procyclic forms showed differential expression of 73 transcripts, a number of which encoded proteins that were previously shown to be stage-regulated. Moreover, two adenylate cyclases previously shown to reduce social motility are up-regulated in late procyclic forms. Conclusions This study validates the use of cultured bloodstream forms as alternatives to animal-derived parasites and yields new markers for all four stages. In addition to underpinning recent findings that early and late procyclic forms are distinct life-cycle stages, it could provide insights into the reasons for their different biological properties

Additional file 4: of RNA-Seq analysis validates the use of culture-derived Trypanosoma brucei and provides new markers for mammalian and insect life-cycle stages

Differentially expressed genes (≥ 2-fold) in successive life-cycle stages. Sl: slender bloodstream forms; St: stumpy bloodstream forms; Ea: early procyclic forms; La: late procyclic forms. (XLSX 5584 kb

Additional file 1: of RNA-Seq analysis validates the use of culture-derived Trypanosoma brucei and provides new markers for mammalian and insect life-cycle stages

Summary of mapping information. (DOCX 45 kb

Additional file 4: of RNA-Seq analysis validates the use of culture-derived Trypanosoma brucei and provides new markers for mammalian and insect life-cycle stages

Differentially expressed genes (≥ 2-fold) in successive life-cycle stages. Sl: slender bloodstream forms; St: stumpy bloodstream forms; Ea: early procyclic forms; La: late procyclic forms. (XLSX 5584 kb

Additional file 6: of RNA-Seq analysis validates the use of culture-derived Trypanosoma brucei and provides new markers for mammalian and insect life-cycle stages

Differential expression ≥2-fold in early and late procyclic forms based on 3′ untranslated regions. Ea: early procyclic forms; La: late procyclic forms. (XLSX 44 kb

Additional file 2: of RNA-Seq analysis validates the use of culture-derived Trypanosoma brucei and provides new markers for mammalian and insect life-cycle stages

Mean expression values (reads per million) for all transcripts. Sl: slender bloodstream forms; St: stumpy bloodstream forms; Ea: early procyclic forms; La: late procyclic forms. (XLSX 762 kb