Thrombospondin 1 and Reelin act through Vldlr to regulate cardiac growth and repair.

Adult mammalian cardiomyocytes have minimal cell cycle capacity, which leads to poor regeneration after cardiac injury such as myocardial infarction. Many positive regulators of cardiomyocyte cell cycle and cardioprotective signals have been identified, but extracellular signals that suppress cardiomyocyte proliferation are poorly understood. We profiled receptors enriched in postnatal cardiomyocytes, and found that very-low-density-lipoprotein receptor (Vldlr) inhibits neonatal cardiomyocyte cell cycle. Paradoxically, Reelin, the well-known Vldlr ligand, expressed in cardiac Schwann cells and lymphatic endothelial cells, promotes neonatal cardiomyocyte proliferation. Thrombospondin1 (TSP-1), another ligand of Vldlr highly expressed in adult heart, was then found to inhibit cardiomyocyte proliferation through Vldlr, and may contribute to Vldlr's overall repression on proliferation. Mechanistically, Rac1 and subsequent Yap phosphorylation and nucleus translocation mediate the regulation of the cardiomyocyte cell cycle by TSP-1/Reelin-Vldlr signaling. Importantly, Reln mutant neonatal mice displayed impaired cardiomyocyte proliferation and cardiac regeneration after apical resection, while cardiac-specific Thbs1 deletion and cardiomyocyte-specific Vldlr deletion promote cardiomyocyte proliferation and are cardioprotective after myocardial infarction. Our results identified a novel role of Vldlr in consolidating extracellular signals to regulate cardiomyocyte cell cycle activity and survival, and the overall suppressive TSP-1-Vldlr signal may contribute to the poor cardiac repair capacity of adult mammals.

Gene Rearrangements in the Mitochondrial Genome of Gonatopsis borealis and Onychoteuthis compacta Reveal Their Phylogenetic Implications for Oegopsida.

The complete mitochondrial genome provides crucial information for comprehending gene rearrangement, molecular evolution, and phylogenetic analysis. Here, we have determined the complete mitogenome sequence of Gonatopsis borealis and Onychoteuthis compacta for the first time. Their genome sizes were 20,148 bp and 20,491 bp, respectively, including 18 protein-coding genes, COI-COIII, ATP6, and ATP8 are duplicated, 23 transfer RNA genes, and 2 ribosomal RNA (rRNA) genes (12S and 16S rRNA). Specifically, the overall A+T content is 70.69% and 72.67%. It shows a significant AT bias. The whole mitogenomes indicate positive AT skew (0.070 and 0.062). Furthermore, the gene order has been rearranged within Oegopsida. The tandem duplication random loss model was determined as most likely to explain the observed gene rearrangements. Phylogenetic analysis was performed, and the result tree was found to be consistent with the morphological identification classification. Estimation of divergence time for 35 species showed that the main differentiation of Oegopsida occurred in 140.70 Mya. These results will help to better understand the gene rearrangements and evolution of G. borealis and O. compacta and lay a foundation for further phylogeny genetic studies of Oegopsida.

Genome-based reclassification of Deinococcus saudiensis Hussain et al. 2016 as a later heterotypic synonym of Deinococcus soli Cha et al. 2014.

Deinococcus saudiensis YIM F302T was compared with Deinococcus soli N5T to examine the taxonomic relationship between the two type strains. The 16S rRNA gene sequence of D. saudiensis YIM F302T showed high similarity (99.9 %) to that of D. soli N5T. The results of phylogenetic analyses based on 16S rRNA gene sequences indicated that the two strains formed a tight cluster within the genus Deinococcus. A draft genomic comparison between the two strains revealed average nucleotide identity values of 96.8-97.9 % and a digital DNA-DNA hybridization estimate of 80.7±1.9 %, strongly indicating that the two strains represented a single species. Based on the combined phylogenetic, genomic and phenotypic characterization presented here, we propose D. saudiensis as a later heterotypic synonym of D. soli N5T.

Pseudomonas marianensis sp. nov., a marine bacterium isolated from deep-sea sediments of the Mariana Trench.

A novel marine Gram-stain-negative, aerobic, rod-shaped bacterium, designated as strain PS1T, was isolated from the deep-sea sediments of the Mariana Trench and characterized phylogenetically and phenotypically. Bacterial optimal growth occurred at 35 °C (ranging 10-45 °C), pH 6 (ranging pH 5-10) and with 11% (w/v) NaCl (ranging 0-17%). The 16S rRNA gene sequence similarity results revealed that strain PS1T was most closely related to Pseudomonas stutzeri ATCC 17588T, Pseudomonas nitrititolerans GL14T, Pseudomonas zhaodongensis NEAU-ST5-21T, Pseudomonas xanthomarina DSM 18231T and Pseudomonas kunmingensis HL22-2T with 98.3-98.7%. The digital DNA-DNA hybridization values and the average nucleotide identity between strain PS1T and the reference strains were 20.4-40.1% and 78.7-79.4%, respectively. The major respiratory quinone is ubiquinone Q-9. The major polar lipids were phosphatidylethanolamine, diphosphatidyglycerol, phosphatidylglycerol, phosphatidylcholine, aminoglycolipid, two unidentified glycolipids and one unidentified lipid. The predominant cellular fatty acids of strain PS1T were summed feature 8 (C18:1ω7c and/or C18:1ω6c), summed feature 3 (C16:1ω7c and/or C16:1ω6c), C16:0 and cyclo-C19:0 ω8c. The G + C content of the genomic DNA was 63.0%. The combined genotypic and phenotypic data indicated that strain PS1T represents a novel species of the genus Pseudomonas, for which the name Pseudomonas marianensis sp. nov. is proposed, with the type strain PS1T (= DSM 112238T = MCCC 1K05112T).

Muricauda abyssi sp. nov., a marine bacterium isolated from deep seawater of the Mariana Trench.

A Gram-stain-negative, non-motile and rod-shaped bacterium, designated as strain W52T, was isolated from deep seawater of the Mariana Trench and characterized phylogenetically and phenotypically. The strain could grow at 10-47 °C (optimum 32 °C), at pH 5.0-8.0 (optimum 6.0) and with 0-9% NaCl (optimum 3 %, w/v). The results of phylogenetic analysis based on 16S rRNA gene sequences indicated that W52T was related to members of the genus Muricauda and shared the highest identity with Muricauda oceani 501str8T (99.0 %), followed by Muricauda aquimarina JCM 11811T, Muricauda ruestringensis DSM 13258T, Muricauda oceanensis 40DY170T, Muricauda beolgyonensis KCTC 23501T and Muricauda zhangzhouensis 12C25T with 97.0-98.8 % sequence similarity. 16S rRNA gene sequence identities between W52T and other members of the genus Muricauda were below 97.0 %. The major respiratory quinone was MK-6. The polar lipids were phosphatidylethanolamine (PE), one unidentified aminolipid and three unidentified lipids. The strain had iso-C15 : 0, iso-C17 : 0 3-OH and iso-C15 : 1G as the major fatty acids. The G+C content of the genomic DNA was 41.7 %. The combined genotypic and phenotypic data indicated that strain W52T represents a novel species of the genus Muricauda, for which the name Muricauda abyssi sp. nov. is proposed, with the type strain W52T (=MCCC 1K05111T= KCTC 82315T).

Mitoflash generated at the Qo site of mitochondrial Complex III.

The previous research has shown that mitochondrial flash (mitoflash) genesis are functionally and mechanistically integrated with mitochondrial electron transport chain (ETC) energy metabolism. However, the response of mitoflash to superoxide is not entirely consistent with the response of MitoSOX Red. The generation mechanism of mitoflash is still unclear. Here, we investigated mitoflash activities, using the different combinations of ETC substrates and inhibitors, in permeabilized cardiomyocytes or hearts. We found that blocking the complete electron flow, from Complex I to IV, with any one of ETC inhibitors including rotenone (Rot), antimycin A (AntA), myxothiazol (Myxo), stigmatellin, and sodium cyanide, will lead to the abolishment of mitoflashes triggered by substrates in adult permeabilized cardiomyocytes. However, Myxo boosted mitoflashes triggered by the reverse electron of N,N,N',N'-tetramethyl-p-phenylenediamine/ascorbate. Moreover, Rot and AntA furtherly enhanced mitoflash activity rather than depressed it, suggesting that mitoflashes generated at the Complex III Qo site. Meanwhile, the inhibition of Complex III protein expression resulted in the activity of Complex III decrease, which decreased mitoflash frequency. The function defect (no change of protein level) of the Qo site of Complex III in aging hearts augmented mitoflash generation confirmed the Qo site function was critical to mitoflash genesis. Thus, our results indicate that mitoflash detected by circularly permuted yellow fluorescent protein is generated at the Qo site of Complex III.

Mitochondrial fusion mediated by fusion promotion and fission inhibition directs adult mouse heart function toward a different direction.

Mitochondrial fusion and fission are essential for heart function. Abrogating mitochondrial dynamism leads to cardiomyopathy. Excessive mitochondrial fragmentation is involved in most heart diseases, thus enhancing mitochondrial fusion will be a potential therapeutic strategy. To understand the effects of promoting mitochondrial fusion in adult cardiac, we investigated mice hearts, and cultured murine embryonic fibroblasts (MEFs), in which mitofusin 2 (Mfn2) overexpressed or dynamin-related protein 1 (Drp1) was abrogated concomitantly forcing mitochondrial fusion. Parallel studies revealed that fission-defective Drp1 knockout hearts and MEFs evoked stronger mitochondrial enlargement, enhanced mitophagy with mitochondrial volume decrease and increased mitochondrial calcium uptake, superoxide production, and permeability transition pore opening, contributed to cardiomyocyte apoptosis and dilated cardiomyopathy. Mfn2 overexpression in the adult heart is comparable with the control except for slight mitochondrial enlargement and mitochondrial volume increase, but without mitophagy induction. Moreover, Mfn2 overexpression increases mitochondrial biogenesis and fusion could protect against mitochondrial fragmentation and Drp1 deletion evoking mitophagy in MEFs. Our findings indicate that mitochondrial fusion provoked by fusion promotion and fission inhibition direct the different fate of heart, Mfn2 upregulation other than Drp1 downregulation well maintains heart mitochondrial function is a more safe strategy for correcting excessive mitochondrial fragmentation in hearts.

Comparative study on isolation and mitochondrial function of adult mouse and rat cardiomyocytes.

BACKGROUND: Cultured adult mouse and rat cardiomyocytes are the best and low-cost cell model for cardiac cellular physiology, pathology, drug toxicity screening, and intervention. The functions of mouse cardiomyocytes decline faster than rat cardiomyocytes in culture conditions. However, little is known about the difference of mitochondrial function between cultured mouse and rat myocytes. METHODS AND RESULTS: A large number of adult mouse and rat cardiomyocytes were comparative isolated using a simple perfusion system. Cardiomyocytes mitochondrial functions were measured after 2 h, 1 day, 2 days, 3 days, and 4 days culture by monitoring mitoflashes. We found that the mitochondrial function of mouse myocytes was remarkedly declined on the third day. Then, we focused on the third day cultured mouse and rat myocytes, comparatively analyzing the respiration function and superoxide generation stimulated by pyruvate/malate/ADP and the mitochondrial permeability transition pore (mPTP) opening induction. Mouse myocytes showed lower respiration and mitoflash activity, but without the change of maximum uncoupled respiration when compared with rat myocytes. Although the response to superoxide production stimulated by respiration substrates was slower than rat myocytes, the basal superoxide generation is faster than the rat. The faster mitochondrial reactive oxygen species (ROS) generation of mouse myocytes upon laser stimulation triggered the faster mPTP opening compared with the rat. Finally, antioxidant MitoTEMPO pretreatment preserved the mitochondrial function of mouse myocytes on the third day. CONCLUSIONS: The mitochondrial function and stability are different between cultured mouse and rat cardiac myocytes beyond 3 days even though they both belong to Muridae. Mitochondrial ROS impairs the mitochondrial functions of mouse cardiomyocytes on the third day. Suppressing superoxide maintained the mitochondrial function of mouse myocytes on the third day.

Mitoflash lights single mitochondrial dynamics events in mature cardiomyocytes.

Mitochondria, the powerhouse of eukaryotic cells, are highly dynamic organelle. Mitochondrial fission, fusion, kissing and contraction have been reported over and over again in non-static cells, such as fibroblast, with tubular mitochondrial networks. Even though the fluorescence propagation among mitochondria of mature cardiomyocytes had been captured using mitochondrial matrix targeted photoactivatable GFP (PAGFP) or MitoDendra proteins, there are no direct evidence that single real time mitochondrial dynamics events exist in mature cardiomyocytes with ball-like mitochondria. Here we first time revealed the visualizable single mitochondrial dynamics events in adult mature cardiomyocytes by the mitochondrial flash (mitoflash). We found fission, fusion, contraction and kissing were accompanied by a mitoflash event. Metabolism could increase mitochondrial contraction. Fusion and Kissing mediated inter-mitochondrial communication with higher frequency than fission. These results demonstrate that mitochondria of static mature cardiomyocytes are undergoing the rare, but real dynamics change.

Catanionic lipid nanosystems improve pharmacokinetics and anti-lung cancer activity of curcumin.

Novel catanionic lipid nanosystems (CLNs) incorporating curcumin (CCM) were developed, and improvements in pharmacokinetics and enhanced anti-lung cancer activity were observed. CCM was present in a lipid matrix surrounded by cationic, anionic and zwitterionic surfactants, forming the core-shell nanosystems. Compared with free CCM, the CCM-CLNs had much higher oral and intravenous bioavailabilities due to enhanced absorption and reduced clearance. The CCM-CLNs exhibited greater cytotoxicity in Lewis lung cancer (LLC) cells, which might have been due to increased antiproliferative, proapoptotic and anti-invasive activities and induction of cell cycle arrest. The CCM-CLNs increased the antitumor efficacy of CCM and decreased the tumor growth rate in tumor-bearing mice. This is the first report of induction of apoptosis in LLC cells by CCM through the PI3K/Akt/FoxO1/Bim signaling pathway. Catanionic lipid nanocarriers show promise for the therapeutic delivery of insoluble anti-tumor drugs.

Application of Gradient-Dependent Optimal Interpolation in Fishery Analysis of Neon Flying Squid (Ommastrephes bartramii) in the Kuroshio-Oyashio Confluence Region.

A key issue in fishery forecasting is the collection of high-precision subsurface environmental data. A data assimilation method, named gradient-dependent optimal interpolation, was used to construct the near-real-time vertical temperature and salinity structure of a squid fishery ground based on Argo observations. The results were verified by truth-finding comparisons and applied to analyze the relationship between neon flying squid and the subsurface environment in the Kuroshio-Oyashio Confluence Region. The temperature and salinity differences between the constructed results and survey data were less than ±0.5 °C and ±0.02, respectively. Most of the relative analysis errors were less than the observational errors. Statistical analysis revealed that the most suitable temperature for squid was 18-24 °C at the near-surface (<5 m), although the squid can endure a temperature range from 11 to 12 °C at a depth of 300 m. There was an obvious thermocline in the fishery ground, with a thermocline depth of 65 m and a mean strength of approximately 0.10 °C/m. The regressive relationship between vertical temperature (thermocline parameters) and squid catch per unit effort (CPUE) followed the exponential (Gaussian) function. The most suitable salinity was 33.0-34.2 at depths shallower than 300 m.

Feeding Strategies and Trophic Niche Divergence of Three Groups of Dosidicus gigas off Peru: Based on Stable Carbon and Nitrogen Isotopes and Morphology of Feeding Apparatuses.

Dosidicus gigas (D. gigas) is a pelagic cephalopod of ecological and economic importance widely distributed in the eastern Pacific Ocean. Generally, small-, medium-, and large-sized groups of the squids have been respectively identified on the basis of the mantle length (ML) of adults. Intraspecific feeding variability maximizes the utilization of available food resources by D. gigas. However, the coexistence mechanism of three groups has not been fully understood yet. In our study, based on the analyses of beak morphology and stable carbon and nitrogen isotopes, the feeding strategies and coexistence patterns of large-, medium-, and small-sized groups of D. gigas were investigated. D. gigas had a wide range of 13C/12C (δ13C) and 15N/14N (δ15N) values in muscle tissue, variable feeding behaviors, and wide food sources. The δ13C or δ15N values showed no significant difference between the small- and medium-sized groups, which shared the same habitats and fed on preys with the similar trophic level. Compared to small- and medium-sized groups, the large-sized group had a smaller range of habitats and consumed more nearshore foods. Both isotopes and feeding apparatus morphology indicated a high degree of niche overlap between the small- and medium-sized groups, whereas the large-sized group differed significantly from other groups. In addition, the niche width of the female was larger than that of the male in all three groups. We inferred that the sex differences in body length and reproductive behavior led to the difference in niche width. The isotopic niche overlap between female and male samples was the most significant in large-sized group and the least significant in the small-sized group, indicating that different feeding strategies were adopted by the three groups. These findings proved that the three groups of D. gigas off Peruvian waters adopted a feeding strategy with inter- and intra-group regulation. This feeding strategy maximizes the use of food and habitat resources and ensures that different size groups can coexist in the same waters.

Fusing Local Shallow Features and Global Deep Features to Identify Beaks.

Cephalopods are an essential component of marine ecosystems, which are of great significance for the development of marine resources, ecological balance, and human food supply. At the same time, the preservation of cephalopod resources and the promotion of sustainable utilization also require attention. Many studies on the classification of cephalopods focus on the analysis of their beaks. In this study, we propose a feature fusion-based method for the identification of beaks, which uses the convolutional neural network (CNN) model as its basic architecture and a multi-class support vector machine (SVM) for classification. First, two local shallow features are extracted, namely the histogram of the orientation gradient (HOG) and the local binary pattern (LBP), and classified using SVM. Second, multiple CNN models were used for end-to-end learning to identify the beaks, and model performance was compared. Finally, the global deep features of beaks were extracted from the Resnet50 model, fused with the two local shallow features, and classified using SVM. The experimental results demonstrate that the feature fusion model can effectively fuse multiple features to recognize beaks and improve classification accuracy. Among them, the HOG+Resnet50 method has the highest accuracy in recognizing the upper and lower beaks, with 91.88% and 93.63%, respectively. Therefore, this new approach facilitated identification studies of cephalopod beaks.

Global squid contamination by halogenated polycyclic aromatic hydrocarbons and its trade induced risk transfer.

Squid is traded globally as an important food resource. However, the occurrence of carcinogenic halogenated polycyclic aromatic hydrocarbons (HPAHs) in squid and the risk of their transfer through trade is little understood or recognized. Here, we comprehensively evaluated the occurrence and risk transfer by quantifying the congener-specific concentrations of HPAHs in 121 squid samples collected from the Pacific, Atlantic and Indian oceans. This was the first time that nine of the 36 target chlorinated and brominated PAH congeners had been detected in squid. The HPAHs exhibited growth-dilution effects in the squid. The lipid content of squid was the most significant factor influencing HPAH bioaccumulation, while differences in squid growth and local ocean contamination influenced by geographical distribution also affected HPAH bioaccumulation. The redistribution and risk transfers of HPAHs in squid as a food could be affected by international trading. The cancer risks from squid consumption in China and Mexico were increased by 50 % and 30 %, respectively, because of international squid trading.

The phylogeny and metabolic potentials of an n-alkane-degrading Venatorbacter bacterium isolated from deep-sea sediment of the Mariana Trench.

Recently, several reports showed that n-alkanes were abundant in the hadal zone, suggesting that n-alkanes could be an important source of nutrients for microorganisms in hadal ecosystems. To date, most of the published studies on the microbial capacity to degrade hydrocarbons were conducted only at atmospheric temperature and pressure (0.1 MPa), and little is known about whether and which microbes could utilize n-alkanes at in situ environmental conditions in the hadal zone, including low temperature and high hydrostatic pressure (especially >30 MPa). In this study, a piezotolerant bacterium, strain C2-1, was isolated from a Mariana Trench sediment at depth of 5,800 m. Strain C2-1 was able to grow at in situ temperature (4°C) and pressure (58 MPa) with n-alkanes as the sole carbon source. Phylogenetically, strain C2-1 and related strains (TMPB967, ST750PaO-4, IMCC1826, and TTBP476) should be classified into the genus Venatorbacter. Metagenomic analysis using ~5,000 publicly available datasets showed that Venatorbacter has a wide environmental distribution in seawater (38), marine sediments (3), hydrothermal vent plumes (2), Antarctic ice (1), groundwater (13), and marine sponge ecosystems (1). Most Venatorbacter species are non-obligate n-alkane degraders that could utilize, at a minimal, C16-C18 n-alkanes, as well as other different types of carbon substrates, including carbohydrates, amino acids, peptides, and phospholipids. The type II secretion system, extracellular proteases, phospholipase, and endonuclease of Venatorbacter species were robustly expressed in the metatranscriptomes of deep-sea hydrothermal vents, suggesting their important contribution to secondary productivity by degrading extracellular macromolecules. The identification of denitrifying genes suggested a genus-specific ecological potential that allowed Venatorbacter species to be active in anoxic environments, e.g., the oxygen-minimal zone (OMZ) and the deeply buried marine sediments. Our results show that Venatorbacter species are responsible for the degradation of hydrocarbon and extracellular macromolecules, suggesting that they may play an important role in the biogeochemistry process in the Trench ecosystems.

Corrigendum: The significance of cephalopod beaks as a research tool: An update.

[This corrects the article DOI: 10.3389/fphys.2022.1038064.].

Mitochondrial autophagy: molecular mechanisms and implications for cardiovascular disease.

Mitochondria are highly dynamic organelles that participate in ATP generation and involve calcium homeostasis, oxidative stress response, and apoptosis. Dysfunctional or damaged mitochondria could cause serious consequences even lead to cell death. Therefore, maintaining the homeostasis of mitochondria is critical for cellular functions. Mitophagy is a process of selectively degrading damaged mitochondria under mitochondrial toxicity conditions, which plays an essential role in mitochondrial quality control. The abnormal mitophagy that aggravates mitochondrial dysfunction is closely related to the pathogenesis of many diseases. As the myocardium is a highly oxidative metabolic tissue, mitochondria play a central role in maintaining optimal performance of the heart. Dysfunctional mitochondria accumulation is involved in the pathophysiology of cardiovascular diseases, such as myocardial infarction, cardiomyopathy and heart failure. This review discusses the most recent progress on mitophagy and its role in cardiovascular disease.

PGC-1α-Mediated Mitochondrial Quality Control: Molecular Mechanisms and Implications for Heart Failure.

Mitochondria with structural and functional integrity are essential for maintaining mitochondrial function and cardiac homeostasis. It is involved in the pathogenesis of many diseases. Peroxisome proliferator-activated receptor γ coactivator 1 α (PGC-1α), acted as a transcriptional cofactor, is abundant in the heart, which modulates mitochondrial biogenesis and mitochondrial dynamics and mitophagy to sustain a steady-state of mitochondria. Cumulative evidence suggests that dysregulation of PGC-1α is closely related to the onset and progression of heart failure. PGC-1α deficient-mice can lead to worse cardiac function under pressure overload compared to sham. Here, this review mainly focuses on what is known about its regulation in mitochondrial functions, as well as its crucial role in heart failure.

[Composition and distribution of zooplankton species in the subtropical areas of the Northwestern Pacific Ocean]. / 西北太平洋亚热带海域浮游动物种类组成与分布.

Based on the investigation data of 44 stations in the area 28°ï¼35° N, 147°ï¼154° E of the Northwestern Pacific Ocean by the research ship 'Songhang' in March 2019, we analyzed species composition and distribution of zooplankton to understand zooplankton community structure in the subtropical areas of the Northwestern Pacific Ocean. The results showed that a total of 456 zooplankton species (including planktonic larvae and unidentified species) were recorded in the surveyed area, which were belonged to 8 categories and 14 groups. There were 163 species of copepods, as the dominant group. The dominant species included 9 warm-water species, Eudoxoides spiralis, Neocalanus gracilis, Pleuromamma gracilis, Sagitta enflata, Doliolum nationalis, S. hexaptera, Euchirella rostrata, Nannocalanus minor and Mesocalanus tenuicornis, and one temperate species, Calanus jashnovi. Both the warm current indicator species S. hexaptera and the cold current indicator species C. jashnovi occurred simultaneously in the subtropical area, indicating that the Kuroshio Current and the Oyashio Current had an important impact on the diversity and temporal-spatial distribution of marine zooplankton. The average biomass was (31.64±23.81) mg·m-3, and the average abundance was (22.2±17.6) ind·m-3. The average values of purity index (C), eveness index (J), Shannon diversity index (H) and richness index (D) were 0.09±0.10, 0.76±0.10, 4.88±0.71, and 23.53±8.08, respectively. The spatial distribution of the four indices were uneven and irregular. During the study period, species composition of zooplankton in the Northwest Pacific was rich, species distribution was uneven, and community structure was stable.