Transcriptomic and gene-family dynamic analyses reveal gene expression pattern and evolution in toxin-producing tissues of Asiatic toad (Bufo gargarizans)

Comprising a major clade of Anura, toads produce and secrete numerous toxins from both the parotoid glands behind their eyes and their dorsal skin. These toxins, made of various proteins and compounds, possess pharmacological potential to be repurposed to benefit human health. However, the detailed genetic regulation of toad toxin production is still poorly understood. A recent publication uncovering the genome of the representative Asiatic toad (Bufo gargarizans) provides a good reference to resolve this issue. In the present study, we sequenced the transcriptomes of parotoid gland, dorsal skin and liver from the Asiatic toad. Combining our data with 35 previously published transcriptomes across eight different tissues from the same species but from different locations, we constructed a comprehensive gene co-expression network of the Asiatic toad with the assistance of the reference genome assembly. We identified 2,701 co-expressed genes in the toxin-producing tissues (including parotoid gland and dorsal skin). By comparative genomic analysis, we identified 599 expanded gene families with 2,720 genes. Through overlapping these co-expressed genes in the toad toxin-producing tissues, we observed that three cytochrome P450 (Cyp) family members (Cyp27a1, Cyp2c29, and Cyp2c39) were significantly enriched in pathways related to cholesterol metabolism. Cholesterol is a critical precursor to steroids, and the known main steroidal toxins of bufadienolides are considered as the major bioactive components in the parotoid glands of Asiatic toad. We found 3-hydroxy-methylglutaryl CoA reductase (hmgcr), encoding the major rate-limiting enzyme for cholesterol biosynthesis, appears with multiple copies in both Asiatic toad and common toad, possibly originating from a tandem duplication event. The five copies of hmgcr genes consistently displayed higher transcription levels in the parotoid gland when compared with the abdominal skin, suggesting it as a vital candidate gene in the involvement of toad toxin production. Taken together, our current study uncovers transcriptomic and gene-family dynamic evidence to reveal the vital role of both expanded gene copies and gene expression changes for production of toad toxins

An integrated control and protection scheme based on FBSM-MMC active current limiting strategy for DC distribution network

DC faults can easily lead to overcurrent in DC distribution networks; these faults pose serious threats to the safe operation of the system. The blocking of modular multilevel converters based on the full-bridge sub-modules (FBSM-MMC) is mostly utilized to cut off the fault current. However, the blocking causes short-term blackouts in the entire DC distribution network and there are presently no effective solutions to address this problem. In this study, an integrated control and protection scheme based on the FBSM-MMC active current limiting strategy is proposed. The project includes three stages: first, MMC active current limiting strategy is used to limit the output current of the converter to about 1.2 p.u. after the occurrence of the fault (Stage 1); next, faulty lines are identified based on the asynchronous zero-crossing features of the DC currents of the two ends of the line (Stage 2); then, a fault isolation scheme based on the cooperation of converters, DC circuit breakers, and high-speed switches is proposed to isolate the faulty line (Stage 3). The distribution network can restart quickly via control of the converters. Finally, the simulation of a four-terminal flexible DC distribution network in PSCAD/EMTDC demonstrates the effectiveness of the proposed integrated scheme

Comparison of the protective effects of ginsenosides Rb1 and Rg1 on improving cognitive deficits in SAMP8 mice based on anti-neuroinflammation mechanism

This present study was designed to investigate the different effects of ginsenosides Rb1 and Rg1 on improving cognitive deficits in 4-month-old SAMP8 mice. Mice were divided into six groups, including the SAMP8 group, the SAMP8 + Donepezil (1.6 mg/kg) group, the SAMP8 + Rb1 (30 and 60 µmol/kg), and SAMP8 + Rg1 (30 and 60 µmol/kg) groups. SAMR1 mice of the same age were used as the control group. Ginsenosides and donepezil were administrated orally to animals for 8 weeks, then the learning and memory ability of mice were measured by using Morris water maze (MWM) test, object recognition test and passive avoidance experiments. The possible mechanisms were studied including the anti-glial inflammation of Rb1 and Rg1 using HE staining, immunohistochemistry and western blot experiments. Results revealed that Rb1 and Rg1 treatment significantly improved the discrimination index of SAMP8 mice in the object recognition test. Rb1 (60 µmol/kg) and Rg1 (30, 60 µmol/kg) could significantly shorten the escape latency in the acquisition test of the MWM test in SAMP8 mice. Furthermore, Rb1 and Rg1 treatments effectively reduced the number of errors in the passive avoidance task in SAMP8 mice. Western blot experiments revealed that Rb1 showed higher effect than Rg1 in decreasing protein expression levels of ASC, caspase-1 and Aβ in the hippocampus of SAMP8 mice, while Rg1 was more effective than Rb1 in decreasing the protein levels of iNOS. In addition, although Rb1 and Rg1 treatments showed significant protective effects in repairing neuronal cells loss and inhibiting the activation of astrocyte and microglia in hippocampus of SAMP8 mice, Rb1 was more effective than Rg1. These results suggest that Rb1 and Rg1 could improve the cognitive impairment in SAMP8 mice, and they have different mechanisms for the treatment of Alzheimer's disease.This work was supported by the National Key Research and Development Program of China (2016YFE0131800), Science & Technology department of Sichuan province (2019YFH0023), Office of Sciences & Technology and Talent work of Luzhou (2018LZXNYD-ZK32), the High - end Talents Recruitment Program (Liu Xinmin group) of Luzhou Municipal People's Government

Case report: identification of one frameshift variant and two in cis non-canonical splice variants of NEB gene in prenatal arthrogryposis

NEB mutation is associated with congenital nemaline myopathies. Here, we report a family with recurrent prenatal arthrogryposis. Trio whole exome sequencing (WES) disclosed three novel NEB (NM_001271208.2) variants including one paternal frameshift c.19049_19050delCA (p.Thr6350Argfs*14) and two double maternal variants in cis c. [24871G>T;24871-10C>G] (p. [Val8291Phe;?]). They are evaluated as “likely pathogenic (LP)”, “variant of uncertain of significance (VUS)”, and “VUS”, respectively. After further prediction, the c.24871G>T, c.24871-10C>G, and c.[24871G>T;24871-10C>G] were respectively genetically engineered into the three plasmids. Compared with their wild-type counterparts, the three plasmids all produced truncated transcripts, and also a significant proportion of the full-length transcripts, which allowed us to reclassify NEB c.24871G>T and c.24871-10C>G variants as LP. As far as we know, this is the first case carrying NEB allele-specific function of partial loss. This result helped the couple make informed reproductive choices and opt for assisted reproduction for future pregnancies. This study also increased awareness to the phenotype of prenatal nemaline myopathy and expanded the variant spectrum of NEB

Molecules of senescent glial cells differentiate Alzheimer's disease from ageing

BACKGROUND: Ageing is a major risk factor for Alzheimer's disease (AD), which is accompanied by cellular senescence and thousands of transcriptional changes in the brain. OBJECTIVES: To identify the biomarkers in the cerebrospinal fluid (CSF) that could help differentiate healthy ageing from neurodegenerative processes. METHODS: Cellular senescence and ageing-related biomarkers were assessed in primary astrocytes and postmortem brains by immunoblotting and immunohistochemistry. The biomarkers were measured in CSF samples from the China Ageing and Neurodegenerative Disorder Initiative cohort using Elisa and the multiplex Luminex platform. RESULTS: The cyclin-dependent kinase inhibitors p16/p21-positive senescent cells in human postmortem brains were predominantly astrocytes and oligodendrocyte lineage cells, which accumulated in AD brains. CCL2, YKL-40, HGF, MIF, S100B, TSP2, LCN2 and serpinA3 are biomarkers closely related to human glial senescence. Moreover, we discovered that most of these molecules, which were upregulated in senescent glial cells, were significantly elevated in the AD brain. Notably, CSF YKL-40 (β=0.5412, p<0.0001) levels were markedly elevated with age in healthy older individuals, whereas HGF (β=0.2732, p=0.0001), MIF (β=0.33714, p=0.0017) and TSP2 (β=0.1996, p=0.0297) levels were more susceptible to age in older individuals with AD pathology. We revealed that YKL-40, TSP2 and serpinA3 were useful biomarkers for discriminating patients with AD from CN individuals and non-AD patients. DISCUSSION: Our findings demonstrated the different patterns of CSF biomarkers related to senescent glial cells between normal ageing and AD, implicating these biomarkers could identify the road node in healthy path off to neurodegeneration and improve the accuracy of clinical AD diagnosis, which would help promote healthy ageing

An Updated Genome Assembly Improves Understanding of the Transcriptional Regulation of Coloration in Midas Cichlid

Midas cichlid (Amphilophus citrinellus), a popular aquarium fish, attracts extensive attention from worldwide biologists mainly due to its morphological polymorphism (dark versus gold). Continuous efforts have therefore been paid to address mechanisms of its coloration variants, while it is far away from the detailed illustration of a clear regulatory network. Some limits may come from the absence of a high-quality genome assembly and a relatively accurate gene set. In this study, we sequenced about 149 Gb of nucleotide sequences of Midas cichlid, generating a genome assembly with a total size of 933.5 Mb, which exhibits a good genome continuity with a contig N50 of 10.5 Mb. A total of 25,911 protein-coding genes were annotated and about 90% completeness was achieved, which helps to build a good gene pool for understanding expressional differences of color variation. With the assistance of the final gene set, we identified a total of 277 differential expressional genes (DEGs), of which 97 up- and 180 downregulated were determined in dark-vs-gold comparisons. Two protein-protein interaction (PPI) networks were constructed from these DEGs, and three key functional modules were classified. Hub genes within each module were evaluated, and we found that the third key module contains tyrp1b, oca2, pmela, tyr, and slc24a5, which were previously proven to be associated with melanin formation. Two downregulated DEGs (myl1 and pgam2) in the first key module may be involved in muscle movement and spermatogenesis, implying that certain side effects could result from the morphological polymorphism. The first key module, consisting of proteins encoded by upregulated DEGs that were associated with MAPK signaling, Toll-like receptor signaling, and gonadotropin-releasing hormone pathways, may contribute to a negative upstream regulation or downstream influence on melanin biosynthesis. Taken together, our new genome assembly and gene annotation of Midas cichlid provide a high-quality genetic resource for biological studies on this species, and the newly identified key networks and hub genes in dark-vs-gold comparisons enhance our understanding of the transcriptional regulatory mechanisms underlying coloration changes not only in Midas cichlid but also in other fishes from freshwater to marine ecosystems

Protective effects of ginsenosides Rg1 and Rb1 against cognitive impairment induced by simulated microgravity in rats

Microgravity experienced during space flight is known to exert several negative effects on the learning ability and memory of astronauts. Few effective strategies are currently available to counteract these effects. Rg1 and Rb1, the major steroidal components of ginseng, have shown potent neuroprotective effects with a high safety profile. The present study aimed to investigate the effects of Rg1 and Rb1 on simulated microgravity-induced learning and memory dysfunction and its underlying mechanism in the hindlimb suspension (HLS) rat model. Administration of Rg1 (30 and 60 μmol/kg) and Rb1 (30 and 60 μmol/kg) for 2 weeks resulted in a significant amelioration of impaired spatial and associative learning and memory caused by 4-week HLS exposure, measured using the Morris water maze and Reward operating conditioning reflex (ROCR) tests, respectively. Furthermore, Rg1 and Rb1 administration alleviated reactive oxygen species production and enhanced antioxidant enzyme activities in the prefrontal cortex (PFC). Rg1 and Rb1 also assisted in the recovery of mitochondrial complex I (NADH dehydrogenase) activities, increased the expression of Mfn2 and decreased the fission marker dynamin-related protein (Drp)-1expression. Additionally, Rg1 and Rb1 treatment increased the SYN, and PSD95 protein expressions and decreased the ratio of Bax:Bcl-2 and reduced the expression of cleaved caspase-3 and cytochrome C. Besides these, the BDNF-TrkB/PI3K-Akt pathway was also activated by Rg1 and Rb1 treatment. Altogether, Rg1 and Rb1 treatment attenuated cognitive deficits induced by HLS, mitigated mitochondrial dysfunction, attenuated oxidative stress, inhibited apoptosis, increased synaptic plasticity, and restored BDNF-TrkB/PI3K-Akt signaling