Thermal priming of reef corals can enhance their heat tolerance; however, the legacy effects of heat stress during parental brooding on larval resilience remain understudied. This study investigated ...whether preconditioning adult coral Pocillopora damicornis to high temperatures (29°C and 32°C) could better prepare their larvae for heat stress. Results showed that heat‐acclimated adults brooded larvae with reduced symbiont density and shifted thermal performance curves. Reciprocal transplant experiments demonstrated higher bleaching resistance and better photosynthetic and autotrophic performance in heat‐exposed larvae from acclimated adults compared to unacclimated adults. RNA‐seq revealed strong cellular stress responses in larvae from heat‐acclimated adults that could have been effective in rescuing host cells from stress, as evidenced by the widespread upregulation of genes involved in cell cycle and mitosis. For symbionts, a molecular coordination between light harvesting, photoprotection and carbon fixation was detected in larvae from heat‐acclimated adults, which may help optimize photosynthetic activity and yield under high temperature. Furthermore, heat acclimation led to opposing regulations of symbiont catabolic and anabolic pathways and favoured nutrient translocation to the host and thus a functional symbiosis. Notwithstanding, the improved heat tolerance was paralleled by reduced light‐enhanced dark respiration, indicating metabolic depression for energy saving. Our findings suggest that adult heat acclimation can rapidly shift thermal tolerance of brooded coral larvae and provide integrated physiological and molecular evidence for this adaptive plasticity, which could increase climate resilience. However, the metabolic depression may be maladaptive for long‐term organismal performance, highlighting the importance of curbing carbon emissions to better protect corals.
Gregarious larval settlement represents an important window for chimera formation in reef corals, yet it remains largely unknown how aggregated settlement and early chimerism could modify the ...performance and responses of coral recruits under elevated temperature and
p
CO
2
. In this study, single and aggregated recruits of the broadcast spawning coral
Acropora austera
were exposed to contrasts of two temperatures (28 versus 30.5°C) and
p
CO
2
levels (~500 versus 1000 μatm) for two weeks, and algal symbiont infection success, survivorship and growth were assessed. Results showed that symbiont infection success was mainly affected by temperature and recruit type, with reduced symbiont infection at increased temperature and consistently higher infection success in chimeric recruits compared to single recruits. Furthermore, although chimeric recruits with larger areal size had significantly higher survivorship in all treatments, the polyp-specific growth rates were considerably lower in chimeric entities than individual recruits. More importantly, the recruit type significantly influenced the responses of recruit polyp-specific growth rates to elevated temperature, with chimeras exhibiting lowered skeletal lateral growth under elevated temperature. These results demonstrate the benefits and costs associated with gregarious larval settlement for juvenile corals under ocean warming and acidification, and highlight the ecological role of larval settlement behavior in mediating the responses of coral recruits to climate change stressors.
The successful dispersal of coral larvae is vital to the population replenishment and reef recovery and resilience. Despite that this critical early stage is susceptible to ocean warming and ...acidification, little is known about the responses of coral larvae to warming and acidification across different biological scales. This study explored the influences of elevated temperature (29 °C versus 33 °C) and pCO2 (500 μatm versus 1000 μatm) on brooded larvae of Pocillopora damicornis at the organismal, cellular and gene expression levels. Heat stress caused bleaching, depressed light-enhanced dark respiration, photosynthesis and autotrophy, whereas high pCO2 stimulated photosynthesis. Although survival was unaffected, larvae at 33 °C were ten-times more likely to settle than those at 29 °C, suggesting reduced capacity to disperse and differentiate suitable substrate. Remarkably, heat stress induced greater symbiont loss at ambient pCO2 than at high pCO2, while cell-specific pigment concentrations of symbionts at 33 °C increased twofold under ambient pCO2 relative to high pCO2, suggesting pCO2-dependent bleaching patterns. Considerable increases in activities of host antioxidants superoxide dismutase (SOD) and catalase (CAT) at 33 °C indicated oxidative stress, whereas lipid peroxidation and caspase activities were contained, thereby restraining larval mortality at 33 °C. Furthermore, the coral host mounted stronger transcriptional responses than symbionts. High pCO2 stimulated host metabolic pathways, possibly because of the boosted algal productivity. In contrast, host metabolic processes and symbiont photosystem genes were downregulated at 33 °C. Interestingly, the upregulation of extracellular matrix genes and glycosaminoglycan degradation pathway at 33 °C was more evident under ambient pCO2 than high pCO2, suggesting compromised host tissue integrity that could have facilitated symbiont expulsion and bleaching. Our results provide insights into how coral larvae respond to warming and acidification at different levels of biological organization, and demonstrate that ocean acidification can mediate thermal bleaching and gene expression in coral larvae under heat stress.
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•High temperature induced bleaching and settlement of Pocillopora damicornis larvae.•High pCO2 stimulated larval photosynthesis and mitigated symbiont loss at 33 °C.•Coral was far more transcriptionally responsive to heat stress than symbionts.•Transcriptomic signatures of compromised metabolism and tissue integrity in coral.•High pCO2 mediates bleaching and gene expression in P. damicornis larvae under heat.
The role of Fat Mass and Obesity-associated protein （FTO） and its substrate N6-methyladenosine （m6A） in mRNA processing and adipogenesis remains largely unknown. We show that FTO expression and m6A ...levels are inversely correlated during adipogenesis. FTO depletion blocks differentiation and only catalytically active FTO restores adi- pogenesis. Transcriptome analyses in combination with m6A-seq revealed that gene expression and mRNA splicing of grouped genes are regulated by FTO. M6A is enriched in exonic regions flanking 5＇- and 3＇-splice sites, spatially over- lapping with mRNA splicing regulatory serine/arginine-rich （SR） protein exonic splicing enhancer binding regions. Enhanced levels of m6A in response to FTO depletion promotes the RNA binding ability of SRSF2 protein, leading to increased inclusion of target exons. FTO controls exonic splicing of adipogenie regulatory factor RUNX1T1 by regulating m6A levels around splice sites and thereby modulates differentiation. These findings provide compelling evidence that FTO-dependent m6A demethylation functions as a novel regulatory mechanism of RNA processing and plays a critical role in the regulation of adipogenesis.
N6-methyladenosine (m6A) is the most prevalent internal modification of messenger RNA (mRNA) in higher eukaryotes. Here we report ALKBH5 as another mammalian demethylase that oxidatively reverses m6A ...in mRNA in vitro and in vivo. This demethylation activity of ALKBH5 significantly affects mRNA export and RNA metabolism as well as the assembly of mRNA processing factors in nuclear speckles. Alkbh5-deficient male mice have increased m6A in mRNA and are characterized by impaired fertility resulting from apoptosis that affects meiotic metaphase-stage spermatocytes. In accordance with this defect, we have identified in mouse testes 1,551 differentially expressed genes that cover broad functional categories and include spermatogenesis-related mRNAs involved in the p53 functional interaction network. The discovery of this RNA demethylase strongly suggests that the reversible m6A modification has fundamental and broad functions in mammalian cells.
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► ALKBH5 is a mammalian m6A RNA demethylase ► RNA demethylation affects mRNA export and RNA metabolism ► RNA demethylation is important for mouse fertility ► Reversible mammalian messenger RNA methylation affects gene expression
The nature of molecule-electrode interface is critical for the integration of atomically precise molecules as functional components into circuits. Herein, we demonstrate that the electric field ...localized metal cations in outer Helmholtz plane can modulate interfacial Au-carboxyl contacts, realizing a reversible single-molecule switch. STM break junction and I-V measurements show the electrochemical gating of aliphatic and aromatic carboxylic acids have a conductance ON/OFF behavior in electrolyte solution containing metal cations (i.e., Na
, K
, Mg
and Ca
), compared to almost no change in conductance without metal cations. In situ Raman spectra reveal strong molecular carboxyl-metal cation coordination at the negatively charged electrode surface, hindering the formation of molecular junctions for electron tunnelling. This work validates the critical role of localized cations in the electric double layer to regulate electron transport at the single-molecule level.
•Supplementation of β-carotene improved the larval survival of H. axyridis on artificial diet.•The fourth instar AD-D-Har showed similar predation and prey preference as MP-Har.•H. axyridis adults in ...AD/MP produced less eggs but had similar pre-oviposition period and larval hatch rate than in MP/MP.•Supplementation of carotenoids had potential to improve the quality of artificial diet, which can be applied as alternative diets in rearing of H. axyridis.
Artificial diets that devoid of insect components have been widely developed for predatory insects, but often yield disappointing results. Carotenoids play vital roles in insects and generally must be acquired from diet, but their supplementation in insect artificial diets has been rarely concerned. Here, we tried to evaluate the function and application prospect of carotenoids in artificial diet of Harmonia axyridis. Firstly, the physical form of component pork liver in artificial diet was improved using fine powder to replace the homogenate, and the survival of infant larvae was greatly increased. Then, four β-carotene-amended artificial diets were developed (0, 0.3, 3 and 30 μg/g (β-carotene/pork liver powder), indicated as AD-A, AD-B, AD-C and AD-D respectively) to evaluate their feeding efficiency for H. axyridis, and the aphid Myzus persicae was used as control. The larval survival on AD-D was equal to that on aphids, and was significantly higher than those on other artificial diets. However, H. axyridis feeding on artificial diets, whichever of the concentration of β-carotene, had significantly longer pre-imaginal development time and obtained smaller newly emerged adults than those on M. persicae. Overall, AD-D showed to be the optimal diet. Finally, the performance of AD-D-fed H. axyridis was evaluated on the target pest M. persicae. Compared to aphid-fed lady beetles, the fourth instar larvae raised with AD-D had similar number of aphid consumption and both showed preference for non-parasitized aphid than newly parasitized by Aphidius gifuensis; the adults produced fewer eggs but had undifferentiated pre-ovipostion period and egg hatch rate.
In conclusion, supplementation of β-carotene could increase the efficiency of artificial diet. On M. persicae, H. axyridis developed from AD-D had outstanding performance which was applicable for releasing in biological control. Our results highlight the importance of carotenoids in artificial diet and might provide a new approach for developing artificial diets.
Significant variability issues in metal-molecule contacts, such as adsorption geometry, lead to characteristic variability in the electrical responses of individual molecules. Herein, co-assembling ...1-ethylimidazole (EIM) on Au(111) has been shown to be a feasible and effective strategy for tuning the binding configurations of pyridine-linked molecular junctions in the most common aqueous environments and atmospheric environments. The single-molecule conductance measurements clearly show a transition from multiple conductance peaks to a single conductance peak with increasing EIM concentration. Raman spectroscopy and DFT calculations suggest that the thermodynamically favorable EIM adsorbate results in the vertical orientation of the bipyridine.
Co-assembling 1-ethylimidazole on Au(111) has been shown to be a feasible strategy for tuning the binding configurations of pyridine-linked molecular junctions in the most common aqueous and atmospheric environments.
Porphyrin-based molecular wires as promising candidates for nanoelectronic devices have attracted much attention. Therefore, it is fundamentally important to investigate structure–electrical ...properties involving such molecules. Herein, a series of 5-ethynyl-2,3-dihydrobenzobthiophene-substituted free-metal porphyrins and metalloporphyrins have been synthesized. Rigid, structurally well-defined, and highly conjugated porphyrin-based molecular wires offer a good platform to explore the impact of coordinated metal ions (Cu, Fe, and Zn) on charge transport at a single-molecule scale. Using the scanning tunneling microscope break-junction (STM-BJ) technique, it is found that single-molecule conductance can change by nearly 500% when the central coordinated metal ions are changed. The theoretically simulated energy-dependent transmission spectra reveal that the spin state of FeTPP can tune charge transport at E = E F, and transmission coefficient T(E) is well correlated with the experimental observation. Our work proves a pronounced metal ion effect on charge transport through a porphyrin plane, providing guidance to design high-performance porphyrin-based nanodevices.
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