The tau gene encodes a protein (Tau) that is a major neuronal microtubule-associated protein localized mostly in axons. It has microtubule-binding and tubulin-polymerizing activity in vitro and is thought to make short crossbridges between axonal microtubules. Further, tau-transfected non-neuronal cells extend long axon-like processes in which microtubule bundles resembling those in axons are formed. In contrast, tau antisense oligonucleotides selectively suppress axonal elongation in cultured neurons. Thus tau is thought to be essential for neuronal cell morphogenesis, especially axonal elongation and maintenance. To test this hypothesis, we used gene targeting to produce mice lacking the tau gene. We show that the nervous system of tau-deficient mice appears to be normal immunohistologically. Furthermore, axonal elongation is not affected in cultured neurons. But in some small-calibre axons, microtubule stability is decreased and microtubule organization is significantly changed. We observed an increase in microtubule-associated protein 1A which may compensate for the functions of tau in large-calibre axons. Our results argue against the suggested role of tau in axonal elongation but confirm that it is crucial in the stabilization and organization of axonal microtubules in a certain type of axon.

Transgenic Arabidopsis thaliana plants were constructed by introduction of a fusion of the gene for #-glucuronidase (GUS) to

A ferritin particle consists of 24 ferritin proteins (FTH1 and FTL) and stores iron ions within it. During iron deficiency, ferritin particles are transported to lysosomes to release iron ions. Two transport pathways have been reported: macroautophagy and ESCRT-dependent endosomal microautophagy. Although the membrane dynamics of these pathways differ, both require NCOA4, which is thought to be an autophagy receptor for ferritin. However, it is unclear whether NCOA4 only acts as an autophagy receptor in ferritin degradation. Here, we found that ferritin particles form liquid-like condensates in a NCOA4-dependent manner. Homodimerization of NCOA4 and interaction between FTH1 and NCOA4 (i.e., multivalent interactions between ferritin particles and NCOA4) were required for the formation of ferritin condensates. Disruption of these interactions impaired ferritin degradation. Time-lapse imaging and three-dimensional correlative light and electron microscopy revealed that these ferritin–NCOA4 condensates were directly engulfed by autophagosomes and endosomes. In contrast, TAX1BP1 was not required for the formation of ferritin–NCOA4 condensates but was required for their incorporation into autophagosomes and endosomes. These results suggest that NCOA4 acts not only as a canonical autophagy receptor but also as a driver to form ferritin condensates to facilitate the degradation of these condensates by macroautophagy (i.e., macroferritinophagy) and endosomal microautophagy (i.e., microferritinophagy).

Photoelectrochemical cells based on Rh-substituted α-Fe 2 O 3 films were fabricated by pulsed laser deposition. The optical bandgap of the films was found to decrease with increasing Rh content. X-ray photoemission spectroscopy analysis revealed that the bandgap narrowing in Rh-substituted films is caused by the hybridization of the Rh t 2g band with the valence band of α-Fe 2 O 3 near the Fermi level. As a result, the photoelectrochemical performance was improved in the Rh-substituted films in the visible and near-infrared regions. The photocurrent in films with a high orientation along the [110] direction was significantly larger than that in the polycrystalline films, which is possibly attributed to the anisotropic electrical conduction of α-Fe 2 O 3 .

Pure phloem sap was collected from leaf sheaths of Zea mays L. by the insect laser technique, and its chemical composition was analyzed. Sucrose was the only sugar detected. The predominant inorganic ions were K + and Cl~. The adenylate energy charge of phloem sap was between 0.72 and 0.86.