Developing efficient and affordable catalysts is of great significance for energy and environmental sustainability. Heterostructure photocatalysts exhibit a better performance than either of the ...parent phases as it changes the band bending at the interfaces and provides a driving force for carrier separation, thus mitigating the effects of carrier recombination and back‐reaction. Herein, the photo/electrochemical applications of a variety of metal sulfides (MSx) (MoS2, CdS, CuS, PbS, SnS2, ZnS, Ag2S, Bi2S3, and In2S3)/TiO2 heterojunctions are summarized, including organic degradation, water splitting, and CO2 reduction conversion. First, a general introduction on each MSx material (especially bandgap structures) will be given. Then the photo/electrochemical applications based on MSx/TiO2 heterostructures are reviewed from the perspective of light harvesting ability, charge carrier separation and transportation, and surface chemical reactions. Special focus is given to CdS/TiO2 and PbS/TiO2‐based quantum dot sensitized solar cells. Ternary composites by taking advantages of positive synergetic effects are also well summarized. Finally, conclusions are made regarding approaches for structure design, and the authors' perspective on future architectural design and electrode construction is given. This work will make up the gap for TiO2 nanocomposites and shed light on the fabrication of more efficient MSx‐metal oxide junctions in photo/electrochemical applications.
Structure steering of MSx/TiO2 heterojunctions in photodegradation, water splitting, and CO2 conversion are reviewed herein, mainly focusing on improved light harvesting, effective interfacial charge transfer, and affordable active sites for surface chemical reactions. Special focus is given to the quantum dot sensitized solar cells.
STUDY QUESTION
Does resveratrol counteract age-associated infertility in a mouse model of reproductive aging?
SUMMARY ANSWER
Long-term-oral administration of resveratrol protects against the ...reduction of fertility with reproductive aging in mice.
WHAT IS KNOWN ALREADY
Loss of oocytes and follicles and reduced oocyte quality contribute to age-associated ovarian aging and infertility. Accumulation of free radicals with age leads to DNA mutations, protein damage, telomere shortening, apoptosis and accelerated ovarian aging. Increasing evidence shows that resveratrol, enriched in certain foods, for example red grapes and wine, has anti-tumor and anti-aging effects on somatic tissues by influencing various signaling pathways, including anti-oxidation, as well as activating Sirt1 and telomerase. We investigated the potential of resveratrol to stave off ovarian aging in the inbred C57/BL6 mouse model.
STUDY DESIGN, SIZE, DURATION
Young C57/BL6 females (aged 2–3 months) were fed with resveratrol added to drinking water at 30 mg/l (providing ∼7.0 mg/kg/day) for 6 or 12 months, and the fertility and ovarian functions were compared among mice treated with or without resveratrol, and young mice served as reproductive controls. Experiments were repeated three times, with an average of 25 females randomly allocated to each treatment group for each repeat.
PARTICIPANTS/MATERIALS, SETTING, METHODS
Reproductive performance of female mice was determined by litter size, ovarian follicles and oocyte quantity and quality, and compared with age-matched controls. The impact of resveratrol on telomeres and telomerase activity, and expression of genes associated with cell senescence also was evaluated.
MAIN RESULTS AND THE ROLE OF CHANCE
Young mice fed with resveratrol for 12 months retained the capacity to reproduce, while age-matched controls produced no pups. Consistently, mice fed with resveratrol for 12 months exhibited a larger follicle pool than controls (P < 0.05). Furthermore, telomerase activity, telomere length and age-related gene expression in ovaries of mice fed with resveratrol resembled those of young mice, but differed (P < 0.05) from those of age-matched old mice. Resveratrol improved (P < 0.05) the number and quality of oocytes, as evidenced by spindle morphology and chromosome alignment. Also, resveratrol affected embryo development in vitro in a dose-dependent manner.
LIMITATIONS, REASONS FOR CAUTION
The doses of resveratrol and the experimental conditions used by different research groups have varied considerably, and the dosage influences both the effectiveness and toxicity of resveratrol. Fine-tuning the dosage of resveratrol likely will optimize its anti-aging effects on ovarian function.
WIDER IMPLICATIONS OF THE FINDINGS
Our data provide a proof of principle of the fertility-sparing effect of resveratrol in female mice. Although depletion of the ovarian reserve of high-quality oocytes also contributes to increased infertility with reproductive aging in women, the data obtained using a mouse model may not extrapolate directly to human reproduction, and more extensive research is needed if any clinic trials are to be attempted.
STUDY FUNDING/COMPETING INTEREST(S)
This work was supported by MOST of China National Basic Research Program (grant number: 2010CB94500 and 2012CB911200). The authors have no competing interests to declare.
Induced pluripotent stem （iPS） cells generated using Yamanaka factors have great potential for use in autologous cell therapy. However, genomic abnormalities exist in human iPS cells, and most mouse ...iPS cells are not fully pluripotent, as evaluated by the tetraploid complementation assay （TCA）; this is most likely associated with the DNA damage response （DDR） occurred in early reprogramming induced by Yamanaka factors. In contrast, nuclear transfer can faithfully reprogram somatic cells into embryonic stem （ES） cells that satisfy the TCA. We thus hypothesized that factors involved in oocyte-induced reprogramming may stabilize the somatic genome during reprogramming, and improve the quality of the resultant iPS cells. To test this hypothesis, we screened for factors that could decrease DDR signals during iPS cell induction. We determined that Zscan4, in combination with the Yamanaka factors, not only remarkably reduced the DDR but also markedly promoted the efficiency of iPS cell generation. The inclusion of Zscan4 stabilized the genomic DNA, resulting in p53 downregulation. Furthermore, Zscan4 also enhanced telomere lengthening as early as 3 days post-infection through a telomere recombination-based mechanism. As a result, iPS cells generated with addition of Zscan4 exhibited longer telomeres than classical iPS cells. Strikingly, more than 50% of iPS cell lines （11/19） produced via this ＂Zscan4 protocol＂ gave rise to live-borne all-iPS cell mice as determined by TCA, compared to 1/12 for lines produced using the classical Yamanaka factors. Our findings provide the first demonstration that maintaining genomic stability during reprogramming promotes the generation of high quality iPS cells.
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•The first multi-cohort study to reveal the association of solid fuel and cognition.•This association may be mediated by physical activity, dyslipidemia, etc.•The transition from ...solid fuel to clean could decrease the risk of cognitive decline.•About 3%–18% of cognitive decline cases could be attributed to solid fuel use.
Household solid-fuel burning contributes to indoor air pollution and is linked to poor cognitive function, but how solid cooking fuel use leads to cognitive decline over time is not well elaborated.
We examine the associations of solid cooking fuel with cognitive function among three nationally representative cohorts.
This study uses data from the 2010–2018 China Family Panel Studies (CFPS), the 2011–2018 China Health and Retirement Longitudinal Study (CHARLS) and the 2003–2015 Mexican Health and Aging Study (MHAS) in adults over the age of 50. Time varying Cox model was conducted to measure the association between cooking fuel types and cognitive decline. Mediation analysis was used to estimate the potential mediation effects on the associations of cooking fuel types with cognitive decline risk.
Respondents in CFPS, CHARLS, and MHAS relied on solid cooking fuel at baseline approximately 56 %, 51 %, and 12 %, respectively. Using solid fuel was consistently associated with higher risk of cognitive decline in three cohorts (CFPS: HR = 1.300 95 % CI: 1.201, 1.407, CHARLS: HR = 1.179 95 % CI: 1.059, 1.312, MHAS: HR = 1.237 95 % CI: 1.123, 1.362). Compared to those with persistent solid fuel, persistent clean fuel and change from solid fuel to clean fuel were associated with a lower risk of cognitive decline. Hypertension, diabetes, physical activity, dyslipidemia and high-density lipoprotein cholesterol (HDL-C) may partially mediate the cognitive decline caused by solid fuel use. Of the cognitive decline burden, 18.23 % (95 % CI: 12.21 %, 24.73 %) in CFPS, 8.90 % (95 % CI: 2.93 %, 15.52 %) in CHARLS and 2.92 % (95 % CI: 1.52 %, 4.46 %) in MHAS of cognitive decline cases attributable to solid cooking fuel use.
The use of solid cooking fuel is associated with a higher risk of cognitive decline. It is essential to promote the expanded use of clean fuel to protect cognitive health.
Steroid hormones are critical for organismal development and health. The rate-limiting step in steroidogenesis is the transport of cholesterol from the outer mitochondrial membrane (OMM) to the ...cytochrome P450 enzyme CYP11A1 in the inner mitochondrial membrane (IMM). Cholesterol transfer occurs through a complex termed the "transduceosome," in which cytosolic steroidogenic acute regulatory protein interacts with OMM proteins translocator protein and voltage-dependent anion channel (VDAC) to assist with the transfer of cholesterol to OMM. It has been proposed that cholesterol transfer from OMM to IMM occurs at specialized contact sites bridging the two membranes composed of VDAC and IMM adenine nucleotide translocase (ANT). Blue native PAGE of Leydig cell mitochondria identified two protein complexes that were able to bind cholesterol at 66- and 800-kDa. Immunoblot and mass spectrometry analyses revealed that the 800-kDa complex contained the OMM translocator protein (18-kDa) and VDAC along with IMM CYP11A1, ATPase family AAA domain-containing protein 3A (ATAD3A), and optic atrophy type 1 proteins, but not ANT. Knockdown of ATAD3A, but not ANT or optic atrophy type 1, in Leydig cells resulted in a significant decrease in hormone-induced, but not 22R-hydroxycholesterol-supported, steroid production. Using a 22-phenoxazonoxy-5-cholene-3-beta-ol CYP11A1-specific probe, we further demonstrated that the 800-kDa complex offers the microenvironment needed for CYP11A1 activity. Addition of steroidogenic acute regulatory protein to the complex mobilized the cholesterol bound at the 800-kDa complex, leading to increased steroid formation. These results identify a bioactive, multimeric protein complex spanning the OMM and IMM unit that is responsible for the hormone-induced import, segregation, targeting, and metabolism of cholesterol.
Naïve and primed pluripotent stem cells (PSCs) represent two different pluripotent states. Primed PSCs following in vitro culture exhibit lower developmental potency as evidenced by failure in ...germline chimera assays, unlike mouse naïve PSCs. However, the molecular mechanisms underlying the lower developmental competency of primed PSCs remain elusive.
We examine the regulation of telomere maintenance, retrotransposon activity, and genomic stability of primed PSCs and compare them with naïve PSCs. Surprisingly, primed PSCs only minimally maintain telomeres and show fragile telomeres, associated with declined DNA recombination and repair activity, in contrast to naïve PSCs that robustly elongate telomeres. Also, we identify LINE1 family integrant L1Md_T as naïve-specific retrotransposon and ERVK family integrant IAPEz to define primed PSCs, and their transcription is differentially regulated by heterochromatic histones and Dnmt3b. Notably, genomic instability of primed PSCs is increased, in association with aberrant retrotransposon activity.
Our data suggest that fragile telomere, retrotransposon-associated genomic instability, and declined DNA recombination repair, together with reduced function of cell cycle and mitochondria, increased apoptosis, and differentiation properties may link to compromised developmental potency of primed PSCs, noticeably distinguishable from naïve PSCs.
Ageing is an irreversible phenomenon and the processes which can delay it are under consideration for a long time by the scientific community. Selenium is an important candidate for it, but the ...impact of selenoprotein on nutritional changes and ageing has not been reported well. In this regard, antioxidant activities and free radical scavenging effect of selenoproteins extracted from selenium-rich rice were studied. Mice were administered a subcutaneous abdominal injection of
d
-galactose to induce the ageing model and fed with different selenoprotein dosage diet. Deviations among biochemical activities (total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and malondialdehyde (MDA)) in liver and serum of the mice were assessed. The degree of liver injury, antioxidant genes and protein relative expression were estimated. The protein content, selenium content, hydroxyl scavenging and DPPH radicals were accessed in selenoprotein components. The selenoprotein constituent had protein and selenium contents in different components as water-soluble proteins > alkali-soluble proteins > salt-soluble proteins > ethanol-soluble proteins. The enzymatic activity (total antioxidant capacity, GSH-Px and SOD) in liver and serum of mice was significantly enhanced in selenoprotein diet groups.
d
-Galactose-induced liver injury was significantly reduced by selenoprotein diet of 25 μg/(kg day). Real-time qPCR and Western blot disclosed the enhanced relative expression of antioxidant genes (
SOD2
,
GPX1
,
TrxR2
and
Nrf2
) and HO-1 protein in the positive control (Vc) and selenoprotein diet groups. In conclusion, selenoprotein treatment was found to have a positive influence on liver hepatocytes and biochemical features in mice. It might be used as a potential diet in scavenging oxidative injury and supporting enzymatic antioxidant system.
The generation of genomically stable and functional oocytes has great potential for preserving fertility and restoring ovarian function. It remains elusive whether functional oocytes can be generated ...from adult female somatic cells through reprogramming to germline-competent pluripotent stem cells (gPSCs) by chemical treatment alone. Here, we show that somatic granulosa cells isolated from adult mouse ovaries can be robustly induced to generate gPSCs by a purely chemical approach, with additional Rock inhibition and critical reprogramming facilitated by crotonic sodium or acid. These gPSCs acquired high germline competency and could consistently be directed to differentiate into primordial-germ-cell-like cells and form functional oocytes that produce fertile mice. Moreover, gPSCs promoted by crotonylation and the derived germ cells exhibited longer telomeres and high genomic stability like PGCs in vivo, providing additional evidence supporting the safety and effectiveness of chemical induction, which is particularly important for germ cells in genetic inheritance.
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•Granulosa cells can be reprogrammed to form oocytes by chemical reprogramming•Rock inhibition and crotonic acid facilitate the chemical induction of gPSCs from GCs•PGCLCs derived from gPSCs exhibit longer telomeres and high genomic stability
Tian et al. report the successful generation of functional oocytes with genomic stability that produce fertile pups from adult-granulosa-cell-derived gPSCs through chemical reprogramming, which exhibits great potential for preserving fertility and restoring ovarian function.
Daily rhythms of mammalian physiology, metabolism, and behavior parallel the day-night cycle. They are orchestrated by a central circadian clock in the brain, the suprachiasmatic nucleus (SCN). ...Transcription of clock genes is sensitive to metabolic changes in reduction and oxidation (redox); however, circadian cycles in protein oxidation have been reported in anucleate cells, where no transcription occurs. We investigated whether the SCN also expresses redox cycles and how such metabolic oscillations might affect neuronal physiology. We detected self-sustained circadian rhythms of SCN redox state that required the molecular clockwork. The redox oscillation could determine the excitability of SCN neurons through nontranscriptional modulation of multiple potassium (K + ) channels. Thus, dynamic regulation of SCN excitability appears to be closely tied to metabolism that engages the clockwork machinery.
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