Pseudohoeflea coraliihabitans sp. nov., a poly-ß-hydroxybutyrate-producing, halotolerant bacterium isolated from coral sediment in the Dapeng peninsula (Guangdong, China).

A Gram-stain-negative, strictly aerobic, motile, flagellated, rod-shaped, halotolerant, and poly-ß-hydroxyalkanoate-producing bacterium, designated DP4N28-3T, was isolated from offshore sediment surrounding hard coral in the Dapeng peninsula (Guangdong, PR China). Growth occurred at 15-35 °C (optimal at 30 °C), pH 6.0-9.5 (optimal at 6.0-7.0), and 0.0-30.0 % NaCl concentration (w/v, optimal at 0.0-2.0 %), showing halotolerance. Phylogeny based on 16S rRNA gene sequences, five housekeeping genes, and genome sequences identified Pseudohoeflea suaedae DSM 23348T (98.1 %, 16S rRNA gene sequence similarity) as the most related species to strain DP4N28-3T. Average nucleotide identity, digital DNA-DNA hybridization, and average amino acid identity values between strain DP4N28-3T and P. suaedae DSM 23348T were all below the threshold of species demarcation. Major phenotypic differences were the flagella type and the limited sources of single carbon utilization by strain DP4N28-3T, which only included acetic acid, acetoacetic acid, d-glucuronic acid, and glucuronamide. Strain DP4N28-3T harboured the class I poly-ß-hydroxyalkanoate synthase gene (phaC) and produced poly-ß-hydroxybutyrate. The fatty acids were summed feature 8 (C18 : 1 ω6c and/or C18 : 1 ω7c, 49.4 %) and C16 : 0 (13.4 %). The major cellular polar lipids consisted of phosphatidylcholine, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol, and sulfoquinovosyl diacylglycerol. The respiratory quinone was Q-10. The results of the phylogenetic, genomic, phenotypic, and chemotaxonomic analysis indicated that the isolated strain represents the type strain of a novel species. Based on these results, strain DP4N28-3T (=MCCC 1K05639T=KCTC 82803T) is proposed as the type strain of the novel species Pseudohoeflea coraliihabitans sp. nov.

Maritimibacter dapengensis sp. nov., a poly-ß-hydroxyalkanoates-producing bacterium isolated from sediment of the Dapeng peninsula (Guangdong, China).

A Gram-negative, obligate aerobic, non-motile, rod-shaped bacterium lacking a flagellum, was isolated from sediment sampled at the Dapeng peninsula of Shenzhen, Guangdong, China, and designated strain DP4N28-5T. Growth of strain DP4N28-5T occurred at 15-45 °C (optimum at 30 °C), pH 6.0-8.0 (optimum at 6.0) and in 2.0-10.0 % NaCl (w/v; optimum at 2.0-3.0 %). The 16S rRNA gene sequence analysis revealed that strain DP4N28-5T was most closely related to Maritimibacter alkaliphilus DSM 100037T (97.6 %; sequence similarity). The strain synthesized a trace amount of poly-ß-hydroxybutyrate. The dominant cellular fatty acids were summed feature 8 (C18 : 1 ω6c and/or C18 : 1 ω7c), C16 : 0, 11-mehtyl C18 : 1 ω7c and C16 : 0 2-OH. The major polar lipids included phosphatidylethanolamine, phosphatidylglycerol, phosphatidylmethylethanolamine, one unidentified aminophospholipid, three unidentified aminolipids and four unidentified lipids. The respiratory quinone was Q-10. The DNA G+C content was 62.0 mol% and the estimated genome size was 3.9 Mbp. The calculated average nucleotide value between strain DP4N28-5T and M. alkaliphilus DSM 100037T was 78.1 %. The phenotypic, genotypic and chemotaxonomic differences between strain DP4N28-5T and its phylogenetic relatives indicate that DP4N28-5T represents a novel species in the genus Maritimibacter, for which the name Maritimibacter dapengensis sp. nov. is proposed. The type strain is DP4N28-5T (=MCCC 1K05640T=KCTC 82805T). The description of genus Maritimibacter was emended to include this new species.

Differential expression of mechanotransduction complex genes in auditory/vestibular hair cells in zebrafish.

Ciliated sensory cells such as photo- and olfactory receptors employ multiple types of opsins or hundreds of unique olfactory G-protein coupled receptors to respond to various wavelengths of light or odorants. With respect to hearing and balance, the mechanotransduction machinery involves fewer variants; however, emerging evidence suggests that specialization occurs at the molecular level. To address how the mechanotransduction complex varies in the inner ear, we characterized the expression of paralogous genes that encode components required for mechanotransduction in zebrafish hair cells using RNA-FISH and bioinformatic analysis. Our data indicate striking zonal differences in the expression of two components of the mechanotransduction complex which are known to physically interact, the transmembrane channel-like 1 and 2 (tmc1/2) family members and the calcium and integrin binding 2 and 3 (cib2/3) paralogues. tmc1, tmc2b, and cib3 are largely expressed in peripheral or extrastriolar hair cells, whereas tmc2a and cib2 are enriched in central or striolar hair cells. In addition, a gene implicated in deaf-blindness, ush1c, is highly enriched in a subset of extrastriolar hair cells. These results indicate that specific combinations of these components may optimize responses to mechanical stimuli in subtypes of sensory receptors within the inner ear.

Epimorphic regeneration in the mammalian tympanic membrane.

Adult mammals are generally believed to have limited ability to regenerate complex tissues and instead, repair wounds by forming scars. In humans and across mammalian species, the tympanic membrane (TM) rapidly repairs perforations without intervention. Using mouse models, we demonstrate that the TM repairs itself through a process that bears many hallmarks of epimorphic regeneration rather than typical wound healing. Following injury, the TM forms a wound epidermis characterized by EGFR ligand expression and signaling. After the expansion of the wound epidermis that emerges from known stem cell regions of the TM, a multi-lineage blastema-like cellular mass is recruited. After two weeks, the tissue architecture of the TM is largely restored, but with disorganized collagen. In the months that follow, the organized and patterned collagen framework of the TM is restored resulting in scar-free repair. Finally, we demonstrate that deletion of Egfr in the epidermis results in failure to expand the wound epidermis, recruit the blastema-like cells, and regenerate normal TM structure. This work establishes the TM as a model of mammalian complex tissue regeneration.

A Hierarchy of Proliferative and Migratory Keratinocytes Maintains the Tympanic Membrane.

The tympanic membrane (TM) is critical for hearing and requires continuous clearing of cellular debris, but little is known about homeostatic mechanisms in the TM epidermis. Using single-cell RNA sequencing, lineage tracing, whole-organ explant, and live-cell imaging, we show that homeostatic TM epidermis is distinct from other epidermal sites and has discrete proliferative zones with a three-dimensional hierarchy of multiple keratinocyte populations. TM stem cells reside in a discrete location of the superior TM and generate long-lived clones and committed progenitors (CPs). CP clones exhibit lateral migration, and their proliferative capacity is supported by Pdgfra+ fibroblasts, generating migratory but non-proliferative progeny. Single-cell sequencing of the human TM revealed similar cell types and transcriptional programming. Thus, during homeostasis, TM keratinocytes transit through a proliferative CP state and exhibit directional lateral migration. This work forms a foundation for understanding TM disorders and modeling keratinocyte biology.

Functions of Enyolreductase (ER) Domains of PKS Cluster in Lipid Synthesis and Enhancement of PUFAs Accumulation in Schizochytrium limacinum SR21 Using Triclosan as a Regulator of ER.

The polyketide synthase (PKS) cluster genes are supposed to synthesize polyunsaturated fatty acids (PUFAs) in S. limacinum. In this study, two enyolreductase (ER) genes located on PKS cluster were knocked out through homologous recombination to explore their functions. The knock-out of OrfB-ER (located on OrfB subunit) decreased lipid content and had obvious decrease on PUFAs content, indicating OrfB-ER domain played a vital role on PUFAs synthesis; the knock-out of OrfC-ER (located on OrfC subunit) decreased SFAs content and increased total lipid content, indicating OrfC-ER domain was likely to be related with SFAs synthesis, and lipid production could be improved by down-regulating OrfC-ER domain expression. Therefore, the addition of triclosan as a reported regulator of ER domain induced the increase of PUFAs production by 51.74% and lipids yield by 47.63%. Metabolic analysis indicated triclosan played its role through inhibiting the expression of OrfC-ER to reduce the feedback inhibition of SFAs and further to enhance NADPH synthesis for lipid production, and by weakening mevalonate pathway and tricarboxylic acid (TCA) cycle to shift precursors for lipid and PUFAs synthesis. This research illuminates functions of two ER domains in S. limacinum and provides a potential targets for improving lipid production.

9-O-benzoyl-substituted berberine exerts a triglyceride-lowering effect through AMPK signaling pathway in human hepatoma HepG2 cells.

Berberine is an isoquinoline alkaloid extracted from Rhizoma coptidis and shows anti-hyperlipidemia effect in vivo and in vitro. We previously found that berberine could decrease the intracellular triglyceride content in human hepatoma HepG2 cells through activation of AMP-activated protein kinase (AMPK), a major regulator of lipid metabolism. Herein, to find a more effective agent, several berberine analogues (A1-A13) were isolated and synthesized, and the triglyceride-lowering effects and potential mechanisms were investigated in HepG2 cells. Among these berberine analogues, 9-O-benzoyl-substituted berberine (A13) showed strong affinity to AMPK and significantly up-regulated the levels of phospho-Thr172 AMPK α subunit. Meanwhile, A13 reduced the cellular triglyceride levels. Furthermore, A13 could mediate the mRNA levels of downstream proteins involved in triglyceride synthesis and fatty acid oxidation of AMPK signaling pathway. These results suggested that A13 exerts a triglyceride-lowering effect via stimulation of AMPK pathway, which may be beneficial to regulate hyperlipidemia.