BackgroundAn emerging cavefish model, the cyprinid genus Sinocyclocheilus, is endemic to the massive southwestern karst area adjacent to the Qinghai-Tibetan Plateau of China. In order to understand whether orogeny influenced the evolution of these species, and how genomes change under isolation, especially in subterranean habitats, we performed whole-genome sequencing and comparative analyses of three species in this genus, S. grahami, S. rhinocerous and S. anshuiensis. These species are surface-dwelling, semi-cave-dwelling and cave-restricted, respectively.ResultsThe assembled genome sizes of S. grahami, S. rhinocerous and S. anshuiensis are 1.75 Gb, 1.73 Gb and 1.68 Gb, respectively. Divergence time and population history analyses of these species reveal that their speciation and population dynamics are correlated with the different stages of uplifting of the Qinghai-Tibetan Plateau. We carried out comparative analyses of these genomes and found that many genetic changes, such as gene loss (e.g. opsin genes), pseudogenes (e.g. crystallin genes), mutations (e.g. melanogenesis-related genes), deletions (e.g. scale-related genes) and down-regulation (e.g. circadian rhythm pathway genes), are possibly associated with the regressive features (such as eye degeneration, albinism, rudimentary scales and lack of circadian rhythms), and that some gene expansion (e.g. taste-related transcription factor gene) may point to the constructive features (such as enhanced taste buds) which evolved in these cave fishes.ConclusionAs the first report on cavefish genomes among distinct species in Sinocyclocheilus, our work provides not only insights into genetic mechanisms of cave adaptation, but also represents a fundamental resource for a better understanding of cavefish biology.Electronic supplementary materialThe online version of this article (doi:10.1186/s12915-015-0223-4) contains supplementary material, which is available to authorized users.

Reversing the charges: Targeted charge‐reversal nanoparticles (TCRNs) comprised of poly(ε‐caprolactone)‐block‐polyethyleneimine (PCL‐PEI), whose amine groups are converted into amides, are negatively charged at neutral pH but become positively charged at pH<6 (see picture). TCRNs effectively enter cells, regenerate the PEI layer in lysosomes, and localize in the nucleus for nuclear drug delivery.

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We reexamined the cellular drug delivery mechanism by poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) to determine their utility and limitations as an intracellular drug delivery system. First, we prepared PLGA NPs which physically encapsulated Nile red (a hydrophobic fluorescent dye), in accordance with the usual procedure for labeling PLGA NPs, incubated them with mesothelial cells, and observed an increase in the intracellular fluorescence. We then prepared NPs from PLGA chemically conjugated to a fluorescent dye and observed their uptake by the mesothelial cells using confocal microscopy. We also used Coherent Anti-Stokes Raman Scattering (CARS) microscopy to image cellular uptake of unlabeled PLGA NPs. Results of this study coherently suggest that PLGA NPs (i) are not readily taken up by cells, but (ii) deliver the payload to cells by extracellular drug release and/or direct drug transfer to contacting cells, which are contrasted with the prevalent view. From this alternative standpoint, we analyzed cytotoxicities of doxorubicin and paclitaxel delivered by PLGA NPs and compared with those of free drugs. Finally, we revisit previous findings in the literature and discuss potential strategies to achieve efficient drug delivery to the target tissues using PLGA NPs.

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Diabetic cardiomyopathy is manifested by compromised systolic and diastolic function. This study was designed to examine the role of advanced glycation endproduct (AGE) and AGE receptor (RAGE) in diabetic cardiomyopathy. Heart function was assessed in isolated control and streptozotocin‐induced diabetic hearts following in vivo RAGE gene knockdown using RNA interference. Cardiomyocyte mechanical properties were evaluated including peak shortening (PS), time‐to‐PS (TPS) and time‐to‐90% relengthening (TR90). RAGE was assayed by RT‐PCR and immunoblot. Diabetes significantly enhanced cardiac MG, AGE and RAGE levels accompanied with colocalization of AGE and RAGE in cardiomyocytes. Diabetes‐elicited increase in RAGE was inhibited by in vivo siRNA interference. The AGE formation inhibitor benfotiamine significantly attenuated diabetes‐induced elevation in MG, AGE, RAGE and collagen cross‐linking without affecting hypertriglyceridaemia and hypercholesterolaemia in diabetes. Diabetes markedly decreased LV contractility, as evidenced by reduced ±dP/dt and LV developed pressure (LVDP), which were protected by RAGE gene knockdown. In addition, MG‐derived AGE (MG‐AGE) up‐regulated cardiac RAGE mRNA and triggered cardiomyocyte contractile dysfunction reminiscent of diabetic cardiomyopathy. The MG‐AGE‐elicited prolongation of TPS and TR90 was ablated by an anti‐RAGE antibody in cardiomyocytes. Interestingly, MG‐AGE‐induced cardiomyocyte dysfunction was associated with mitochondrial membrane potential (MMP) depolarization and reduced GSK‐3β inactivation in control cardiomyocytes, similar to those from in vivo diabetes. Treatment with siRNA‐RAGE ablated diabetes‐induced MMP depolarization and GSK‐3β inactivation. Collectively, our result implicated a role of AGE‐RAGE in the pathogenesis of diabetic cardiomyopathy.