Zinc is an essential nutrient for all forms of life. Within cells, most zinc is bound to protein. Because zinc serves as a catalytic or structural cofactor for many proteins, cells must maintain zinc homeostasis under severely zinc-deficient conditions. In yeast, the transcription factor Zap1 controls the expression of genes required for uptake and mobilization of zinc, but to date the fate of existing zinc-binding proteins under zinc starvation remains poorly understood. Autophagy is an evolutionarily conserved cellular degradation/recycling process in which cytoplasmic proteins and organelles are sequestered for degradation in the vacuole/lysosome. In this study, we investigated how autophagy functions under zinc starvation. Zinc depletion induced non-selective autophagy, which is important for zinclimited growth. Induction of autophagy by zinc starvation was not directly related to transcriptional activation of Zap1. Instead, TORC1 inactivation directed zinc starvation-induced autophagy. Abundant zinc proteins, such as Adh1, Fba1, and ribosomal protein Rpl37, were degraded in an autophagy-dependent manner. But the targets of autophagy were not restricted to zinc-binding proteins. When cellular zinc is severely depleted, this non-selective autophagy plays a role in releasing zinc from the degraded proteins and recycling zinc for other essential purposes.

Bone undergoes constant remodeling throughout life. The cellular and biochemical mechanisms of bone remodeling vary in a region-specific manner. There are a number of notable differences between the mandible and long bones, including developmental origin, osteogenic potential of mesenchymal stem cells, and the rate of bone turnover. Collagen, the most abundant matrix protein in bone, is responsible for determining the relative strength of particular bones. Posttranslational modifications of collagen, such as intermolecular crosslinking and lysine hydroxylation, are the most essential determinants of bone strength, although the amount of collagen is also important. In comparison to long bones, the mandible has greater collagen content, a lower amount of mature crosslinks, and a lower extent of lysine hydroxylation. The great abundance of immature crosslinks in mandibular collagen suggests that there is a lower rate of cross-link maturation. This means that mandibular collagen is relatively immature and thus more readily undergoes degradation and turnover. The greater rate of remodeling in mandibular collagen likely renders more flexibility to the bone and leaves it more suited to constant exercise. As reviewed here, it is important in clinical dentistry to understand the distinctive features of the bones of the jaw.

Background/Aim: We recently reported that renal tubular acidosis (RTA) in Sjögren’s syndrome (SjS) is associated with high titers of an autoantibody against carbonic anhydrase (CA) II, an important enzyme in renal acid-base regulation. The purpose of this study was to determine whether a CA-II antibody could cause RTA in a mouse model of SjS. Methods: PL/J mice were immunized with human CA II to induce CA II antibody formation, whereas controls were injected with phosphate-buffered saline and adjuvant. After 6 weeks, anti-CA-II antibody titers were measured, then ammonium chloride was administered orally for 1 week to detect any acidification defect. Results: CA-II-immunized mice showed higher anti-CA-II antibody titers than control mice. Pathologically, lymphocytic and plasma cell infiltration was seen in the salivary glands and kidneys of CA-II-immunized mice, but not in controls. On acid loading, blood pH and urine pH decreased in both groups of mice, but the slope of urine pH versus blood pH was less steep in the CA-II-immunized mice, suggesting that these mice had an impaired ability to reduce their urine pH in the face of metabolic acidosis. Conclusion: CA-II-immunized mice had a urinary acidification defect, which may be similar to that seen in patients with SjS.

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We investigated phonons with long mean free paths (MFPs) in amorphous Si (a-Si) and amorphous Ge (a-Ge). The thermal conductivity of a-Si and a-Ge thin films prepared by magnetron sputtering was found to depend on film thickness and deposition temperature. From the film thickness dependence, we conclude that phonons with MFPs longer than 100 nm contribute to heat transport in a-Si and a-Ge. Also, as deposition temperature was increased, phonons with MFPs ranging from 100 to 250 nm in a-Si and from 15 to 250 nm in a-Ge increased.