Graphical AbstractHighlights d Skeletal stem cells increase glutamine metabolism during osteoblast differentiation d Glutamine metabolism regulates osteoblast and adipocyte specification d Mice unable to metabolize glutamine have less bone and increased marrow fat d Amino acid transaminase-derived a-ketoglutarate is critical for SSC proliferation SUMMARY Skeletal stem cells (SSCs) are postulated to provide a continuous supply of osteoblasts throughout life. However, under certain conditions, the SSC population can become incorrectly specified or is not maintained, resulting in reduced osteoblast formation, decreased bone mass, and in severe cases, osteoporosis. Glutamine metabolism has emerged as a critical regulator of many cellular processes in diverse pathologies. The enzyme glutaminase (GLS) deaminates glutamine to form glutamate-the ratelimiting first step in glutamine metabolism. Using genetic and metabolic approaches, we demonstrate GLS and glutamine metabolism are required in SSCs to regulate osteoblast and adipocyte specification and bone formation. Mechanistically, transaminasedependent a-ketoglutarate production is critical for the proliferation, specification, and differentiation of SSCs. Collectively, these data suggest stimulating GLS activity may provide a therapeutic approach to expand SSCs in aged individuals and enhance osteoblast differentiation and activity to increase bone mass.Conceptualization, C.M.K.; Investigation, Y.Y., H.N., L.

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Atonal homolog1 (Atoh1) encodes a basic helix-loop-helix protein that is the first transcription factor to be expressed in differentiating hair cells. Previous work suggests that expression of Atoh1 in prosensory precursors is necessary for the differentiation and survival of hair cells, but it is not clear whether Atoh1 is required exclusively for these processes, or whether it regulates other functions later during hair cell maturation. We used EGFP-tagged Atoh1 knock-in mice to demonstrate for the first time that Atoh1 protein is expressed in hair cell precursors several days before the appearance of differentiated markers, but not in the broad pattern expected of a proneural gene. We conditionally deleted Atoh1 at different points in hair cell development and observe a rapid onset of hair cell defects, suggesting that the Atoh1 protein is unstable in differentiating hair cells and is necessary through an extended phase of their differentiation. Conditional deletion of Atoh1 reveals multiple functions in hair cell survival, maturation of stereociliary bundles, and auditory function. We show the presence of distinct critical periods for Atoh1 in each of these functions, suggesting that Atoh1 may be directly regulating many aspects of hair cell function. Finally, we show that the supporting cell death that accompanies loss of Atoh1 in hair cells is likely caused by the abortive trans-differentiation of supporting cells into hair cells. Together our data suggest that Atoh1 regulates multiple aspects of hair cell development and function.

Microplastics (MPs) as new pollutants of environmental concern have been widely detected in sewage sludge, and may act as significant vectors for metal pollutants due to their adsorption property. Our findings show that Cd, Pb, and Co, but not Ni, contents in sewage sludge are lower than that of corresponding metal irons adsorbed on sludge-based MPs, indicating that the MPs accumulate such metal pollutants as Cd in the sludge samples. In contrast to virgin MPs, sludge-based MPs are one order of magnitude higher adsorption capacity for Cd, which reaches up to 2.523 mg g -1 , implying that there is a considerable enhancement in adsorption potential of the MPs for metals after the wastewater treatment process. SEM analysis shows that sludge-based MPs have rougher and more porous surface than virgin MPs, and FTIR spectra reveal that functional groups such as C-O and O-H are found on sludge-based MPs. Further, two-dimensional FTIR correlation spectroscopy indicates that C-O and N-H functional groups play a vital role in the process that sludge-based MPs adsorb Cd, which are not found in virgin MPs. The results imply that increased adsorption potentials of the sludge-based MPs to Cd are attributed to changes in the MP physicochemical properties during wastewater treatment process. In addition, such factors as pH value, and sludge inorganic and organic components also have an effect on the MP adsorption to Cd. Principal component analysis shows that the MPs could be divided into three categories, i.e. polyamide, rubbery MPs (polyethylene and polypropylene) and glassy MPs (polyvinyl chloride and polystyrene). Their adsorption potentials to Cd follow the decreasing order: polyamide > rubbery MPs > glassy MPs.

miRNAs are involved in the pollen development during the CMS occurrence in rice. miRNAs are 20-24 nt endogenously expressed small RNAs that play key roles in the regulation of many growth and developmental processes in plants. The knowledge on cytoplasmic male sterility (CMS) regulation by miRNAs in rice is rather limited. In this study, Illumina sequencing was employed to examine the expression profiles of rice anther miRNAs from the CMS line MeixiangA (MxA) and its maintainer line MeixiangB (MxB). A total of 518 known miRNAs and 144 novel miRNAs were identified during rice anther development. Based on the number of sequencing reads, a total of 24 miRNAs were discovered to be differentially expressed between MxA and MxB, and the results were partially validated by qRT-PCR. Among these, 16 miRNAs were decreased and 8 miRNAs were increased in MxA compared with MxB. Target prediction showed that they target genes encoding EF-hand family proteins, F-box domain-containing proteins, MYB transcription factors, PPR-containing proteins and transposons. The expression patterns for targets of osa-miR528, osa-miR5793, osa-miR1432, osa-miR159, osa-miR812d, osa-miR2118c, osa-miR172d and osa-miR5498 were selectively examined, and the results showed that there was a negative correlation on the expression patterns between miRNAs and their targets. These targets have previously been reported to be related with pollen development and male sterility, suggesting that miRNAs might act as regulators of CMS occurrence in rice anthers. Furthermore, miRNA editing events were observed. The U → C and U → A editing phenomenon was validated by molecular cloning and sequencing. These findings contribute to our understanding of the roles of miRNAs during anther development and CMS occurrence in rice.