Eco-evolutionary evidence for the global diversity pattern of Cycas (Cycadaceae).

The evolution of the latitudinal diversity gradient (LDG), characterized by a peak in diversity toward the tropics, has captured significant attention in evolutionary biology and ecology. However, the inverse LDG (i-LDG) mechanism, wherein species richness increases toward the poles, remains inadequately explored. Cycads are among one of the oldest lineages of extant seed plants and have undergone extensive diversification in the tropics. Intriguingly, the extant cycad abundance exhibits an i-LDG pattern, and the underlying causes for this phenomenon remain largely elusive. Here, using 1,843 nuclear genes from a nearly complete sampling, we conducted comprehensive phylogenomic analyses to establish a robust species-level phylogeny for Cycas, the largest genus within cycads. We then reconstructed the spatial-temporal dynamics and integrated global environmental data to evaluate the roles of species ages, diversification rates, contemporary environment, and conservatism to ancestral niches in shaping the i-LDG pattern. We found Cycas experienced decreased diversification rates, coupled with the cooling temperature since its origin in the Eocene from continental Asia. Different regions have distinctively contributed to the formation of i-LDG for Cycas, with the northern hemisphere acting as evolutionary museums and the southern hemisphere serving as cradles. Moreover, water-related climate variables, specifically precipitation seasonality and potential evapotranspiration, were identified as paramount factors constraining Cycas species richness in the rainforest biome near the equator. Notably, the adherence to ancestral monsoonal climates emerges as a critical factor in sustaining the diversity pattern. This study underscores the imperative of integrating both evolutionary and ecological approaches to comprehensively unravel the mechanisms underpinning global biodiversity patterns.

Correlation between Anatomical and Functional Outcomes in Patients with Idiopathic Epiretinal Membrane after Vitrectomy.

BACKGROUND: Idiopathic epiretinal membrane (iERM) is a common disorder of the vitreomacular interface characterized by decreased visual acuity and metamorphopsia. This study aimed to analyze the association between the anatomical change of the retina and functional outcomes in iERM patients so as to derive the prognostic factors of visual acuity (VA) and metamorphopsia. METHODS: Forty-five patients (one eye per patient; 45 eyes in total) who underwent pars plana vitrectomy and membrane peeling for iERM by a single surgeon were enrolled in this retrospective study. The results on best-corrected visual acuity (BCVA) and metamorphopsia as well as retinal images were obtained before the surgery and 1, 3, 6 months after the surgery. The BCVA and retinal microstructure, including central retinal thickness (CRT), ganglion cell layer (GCL) thickness, inner nuclear layer (INL) and outer nuclear layer + outer plexiform layer (ONL+OPL), and continuity of photoreceptor inner/outer segment (IS/OS) junction before and after iERM surgery were compared using paired samples t-test (continuous variables) or Chi-square test (categorical variables). Multiple regression analysis was carried out to explore the association among BCVA, M-score, and the parameters derived from optical coherence tomography. RESULTS: Compared with preoperative data, a significant improvement in BCVA was observed 1, 3, and 6 months postoperatively (t = 5.37, p < 0.0001; t = 7.29, p < 0.0001; t = 6.44, p < 0.0001 for 1, 3, and 6 months postoperatively, respectively), whereas the M-score only decreased significantly 3 and 6 months after the surgery (t = 2.36, p = 0.02; t = 5.00, p < 0.0001, respectively). In comparison with the baseline, the CRT, INL, and ONL+OPL thickness showed a significant decrease at each postoperative follow-up time, and GCL thickness (t = 3.86, p = 0.0002) and IS/OS disruption ratio (χ2 = 4.86, p = 0.027) were markedly reduced only 6 months postoperatively. Six-month postoperative BCVA was considerably associated with preoperative CRT and ONL+OPL thickness, as well as postoperative CRT, ONL+OPL thickness, and severity of IS/OS disruption. Moreover, the M-score after surgery was markedly correlated with both the preoperative and postoperative INL and CRT thickness. CONCLUSIONS: Both VA and M-score in iERM patients were significantly improved after vitrectomy. Pre- and post-operative CRT was significantly associated with both postoperative BCVA and M-score. Besides, pre- and post-operative INL thickness was correlated to postoperative metamorphopsia, and postoperative BCVA was associated with postoperative ONL+OPL thickness and IS/OS integrity.

Phylotranscriptomics Shed Light on Intrageneric Relationships and Historical Biogeography of Ceratozamia (Cycadales).

Ceratozamia Brongn. is one of the species-rich genera of Cycadales comprising 38 species that are mainly distributed in Mexico, with a few species reported from neighboring regions. Phylogenetic relationships within the genus need detailed investigation based on extensive datasets and reliable systematic approaches. Therefore, we used 30 of the known 38 species to reconstruct the phylogeny based on transcriptome data of 3954 single-copy nuclear genes (SCGs) via coalescent and concatenated approaches and three comparative datasets (nt/nt12/aa). Based on all these methods, Ceratozamia is divided into six phylogenetic subclades within three major clades. There were a few discrepancies regarding phylogenetic position of some species within these subclades. Using these phylogenetic trees, biogeographic history and morphological diversity of the genus are explored. Ceratozamia originated from ancestors in southern Mexico since the mid-Miocene. There is a distinct distribution pattern of species through the Trans-Mexican Volcanic Belt (TMVB), that act as a barrier for the species dispersal at TMVB and its southern and northern part. Limited dispersal events occurred during the late Miocene, and maximum diversification happened during the Pliocene epoch. Our study provides a new insight into phylogenetic relationships, the origin and dispersal routes, and morphological diversity of the genus Ceratozamia. We also explain how past climatic changes affected the diversification of this Mesoamerica-native genus.

Eight TRIM32 isoforms from oriental river prawn Macrobrachium nipponense are involved in innate immunity during white spot syndrome virus infection.

Tripartite motif (TRIM) proteins comprise a large family of RING-type ubiquitin E3 ligases that regulate important biological processes. In this study, full-length MnTRIM32 cDNA was obtained from oriental river prawn Macrobrachium nipponense, and eight MnTRIM32 isoforms generated by alternative splicing were identified. The open reading frames of the eight MnTRIM32 isoforms were predicted to be separately composed of 402, 346, 347, 346, 414, 358, 359, and 358 amino acid residues. Protein structural analysis revealed that all MnTRIM32 isoforms contained a RING domain and a coiled coil region. MnTRIM32 was ubiquitously expressed in all tissues tested, with the highest expression in the hepatopancreas. The mRNA levels of MnTRIM32 in the gills, stomach, and intestine of prawns were found to undergo time-dependent enhancement following white spot syndrome virus (WSSV) stimulation. Double-stranded RNA interference studies revealed that MnTRIM32 silencing significantly downregulated the expression levels of interferon (IFN) regulatory factor MnIRF, IFN-like factor MnVago4, and tumor necrosis factor MnTNF. Furthermore, knockdown of MnTRIM32 in WSSV-challenged prawns increased the expression of VP28 and the number of WSSV copies, suggesting that MnTRIM32 plays a positive role in limiting WSSV infection. These findings provided strong evidence for the important role of MnTRIM32 in the antiviral innate immunity of M. nipponense.

Phylotranscriptomics reveal the spatio-temporal distribution and morphological evolution of Macrozamia, an Australian endemic genus of Cycadales.

BACKGROUND AND AIMS: Cycads are regarded as an ancient lineage of living seed plants, and hold important clues to understand the early evolutionary trends of seed plants. The molecular phylogeny and spatio-temporal diversification of one of the species-rich genera of cycads, Macrozamia, have not been well reconstructed. METHODS: We analysed a transcriptome dataset of 4740 single-copy nuclear genes (SCGs) of 39 Macrozamia species and two outgroup taxa. Based on concatenated (maximum parsimony, maximum likelihood) and multispecies coalescent analyses, we first establish a well-resolved phylogenetic tree of Macrozamia. To identify cyto-nuclear incongruence, the plastid protein coding genes (PCGs) from transcriptome data are extracted using the software HybPiper. Furthermore, we explore the biogeographical history of the genus and shed light on the pattern of floristic exchange between three distinct areas of Australia. Six key diagnostic characters are traced on the phylogenetic framework using two comparative methods, and infra-generic classification is investigated. KEY RESULTS: The tree topologies of concatenated and multi-species coalescent analyses of SCGs are mostly congruent with a few conflicting nodes, while those from plastid PCGs show poorly supported relationships. The genus contains three major clades that correspond to their distinct distributional areas in Australia. The crown group of Macrozamia is estimated to around 11.80 Ma, with a major expansion in the last 5-6 Myr. Six morphological characters show homoplasy, and the traditional phenetic sectional division of the genus is inconsistent with this current phylogeny. CONCLUSIONS: This first detailed phylogenetic investigation of Macrozamia demonstrates promising prospects of SCGs in resolving phylogenetic relationships within cycads. Our study suggests that Macrozamia, once widely distributed in Australia, underwent major extinctions because of fluctuating climatic conditions such as cooling and mesic biome disappearance in the past. The current close placement of morphologically distinct species in the phylogenetic tree may be related to neotenic events that occurred in the genus.

The Natural History of Spinocerebellar Ataxia Type 3 in Mainland China: A 2-Year Cohort Study.

Objective: The natural history of spinocerebellar ataxia type 3 (SCA3) has been reported in several populations and shows heterogeneity in progression rate and affecting factors. However, it remains unexplored in the population of Mainland China. This study aimed to identify the disease progression rate and its potential affecting factors in patients with SCA3 in Mainland China. Participants and Methods: We enrolled patients with genetically confirmed SCA3 in Mainland China. Patients were seen at three visits, i.e., baseline, 1 year, and 2 years. The primary outcome was the Scale for the Assessment and Rating of Ataxia (SARA), and the secondary outcomes were the Inventory of Non-Ataxia Signs (INAS) as well as the SCA Functional Index (SCAFI). Results: Between 1 October 2015, and 30 September 2016, we enrolled 263 patients with SCA3. We analyzed 247 patients with at least one follow-up visit. The annual progression rate of SARA was 1.49 points per year (SE 0.08, 95% confidence interval [CI] 1.33-1.65, p < 0.0001). The annual progression rates of INAS and SCAFI were 0.56 points per year (SE 0.05, 95% CI 0.47-0.66, p < 0.001) and -0.30 points per year (SE 0.01, 95% CI -0.33∼-0.28, p < 0.001), respectively. Faster progression in SARA was associated with longer length of the expanded allele of ATXN3 (p < 0.0001); faster progression in INAS was associated with lower INAS at baseline (p < 0.0001); faster decline in SCAFI was associated with shorter length of the normal allele of ATXN3 (p = 0.036) and higher SCAFI at baseline (p < 0.0001). Conclusion: Our results provide quantitative data on the disease progression of patients with SCA3 in Mainland China and its corresponding affecting factors, which could facilitate the sample size calculation and patient stratification in future clinical trials. Trial Registration: This study was registered with Chictr.org on 15 September 2015, number ChiCTR-OOC-15007124.

The Cycas genome and the early evolution of seed plants.

Cycads represent one of the most ancient lineages of living seed plants. Identifying genomic features uniquely shared by cycads and other extant seed plants, but not non-seed-producing plants, may shed light on the origin of key innovations, as well as the early diversification of seed plants. Here, we report the 10.5-Gb reference genome of Cycas panzhihuaensis, complemented by the transcriptomes of 339 cycad species. Nuclear and plastid phylogenomic analyses strongly suggest that cycads and Ginkgo form a clade sister to all other living gymnosperms, in contrast to mitochondrial data, which place cycads alone in this position. We found evidence for an ancient whole-genome duplication in the common ancestor of extant gymnosperms. The Cycas genome contains four homologues of the fitD gene family that were likely acquired via horizontal gene transfer from fungi, and these genes confer herbivore resistance in cycads. The male-specific region of the Y chromosome of C. panzhihuaensis contains a MADS-box transcription factor expressed exclusively in male cones that is similar to a system reported in Ginkgo, suggesting that a sex determination mechanism controlled by MADS-box genes may have originated in the common ancestor of cycads and Ginkgo. The C. panzhihuaensis genome provides an important new resource of broad utility for biologists.

CRISPR/Cas9 mediated gene correction ameliorates abnormal phenotypes in spinocerebellar ataxia type 3 patient-derived induced pluripotent stem cells.

Spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) is a progressive autosomal dominant neurodegenerative disease caused by abnormal CAG repeats in the exon 10 of ATXN3. The accumulation of the mutant ataxin-3 proteins carrying expanded polyglutamine (polyQ) leads to selective degeneration of neurons. Since the pathogenesis of SCA3 has not been fully elucidated, and no effective therapies have been identified, it is crucial to investigate the pathogenesis and seek new therapeutic strategies of SCA3. Induced pluripotent stem cells (iPSCs) can be used as the ideal cell model for the molecular pathogenesis of polyQ diseases. Abnormal CAG expansions mediated by CRISPR/Cas9 genome engineering technologies have shown promising potential for the treatment of polyQ diseases, including SCA3. In this study, SCA3-iPSCs can be corrected by the replacement of the abnormal CAG expansions (74 CAG) with normal repeats (17 CAG) using CRISPR/Cas9-mediated homologous recombination (HR) strategy. Besides, corrected SCA3-iPSCs retained pluripotent and normal karyotype, which can be differentiated into a neural stem cell (NSCs) and neuronal cells, and maintained electrophysiological characteristics. The expression of differentiation markers and electrophysiological characteristics were similar among the neuronal differentiation from normal control iPSCs (Ctrl-iPSCs), SCA3-iPSCs, and isogenic control SCA3-iPSCs. Furthermore, this study proved that the phenotypic abnormalities in SCA3 neurons, including aggregated IC2-polyQ protein, decreased mitochondrial membrane potential (MMP) and glutathione expressions, increased reactive oxygen species (ROS), intracellular Ca2+ concentrations, and lipid peroxidase malondialdehyde (MDA) levels, all were rescued in the corrected SCA3-NCs. For the first time, this study demonstrated the feasibility of CRISPR/Cas9-mediated HR strategy to precisely repair SCA3-iPSCs, and reverse the corresponding abnormal disease phenotypes. In addition, the importance of genetic control using CRISPR/Cas9-mediated iPSCs for disease modeling. Our work may contribute to providing a potential ideal model for molecular mechanism research and autologous stem cell therapy of SCA3 or other polyQ diseases, and offer a good gene therapy strategy for future treatment.

Anxiety and depression in spinocerebellar ataxia patients during the COVID-19 pandemic in China: A cross-sectional study.

Coronavirus disease 2019 (COVID-19) is currently a global concern, and the psychological impact cannot be overlooked. Our purpose was to evaluate the anxiety and depression in spinocerebellar ataxia (SCA) patients during the pandemic and to analyse the influencing factors. We conducted an online questionnaire survey among 307 SCA patients from China and selected 319 healthy people matched by sex and age as the control group. The questionnaire included general information, the self-rating anxiety scale (SAS), and the self-rating depression scale (SDS). The relevant factors included COVID-19 risk factors, age, sex, body mass index (BMI), educational background, disease course, score on the scale for the assessment and rating of ataxia (SARA), Mini-mental State Examination (MMSE) and International Cooperative Ataxia Rating Scale (ICARS). The proportion of SCA patients with anxiety was 34.9%, and the proportion with depression was 56.7%. The SAS and SDS scores of the SCA patients were significantly higher than those of the control group (SAS: 45.8 ± 10.1 vs. 40.6 ± 8.9, P < 0.01; SDS: 55.1 ± 12.2 vs. 43.6 ± 11.9, P < 0.01). In SCA3, the risk of exposure to COVID-19, educational level, disease course and the severity of ataxia may be factors affecting patients' mental health. More attention should be paid to the mental health of SCA patients during the COVID-19 pandemic.

New Model for Estimation of the Age at Onset in Spinocerebellar Ataxia Type 3.

OBJECTIVES: The aim of this study was to develop an appropriate parametric survival model to predict patient's age at onset (AAO) for spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) populations from mainland China. METHODS: We compared the efficiency and performance of 6 parametric survival analysis methods (exponential, weibull, log-gaussian, gaussian, log-logistic, and logistic) based on cytosine-adenine-guanine (CAG) repeat length at ATXN3 to predict the probability of AAO in the largest cohort of patients with SCA3/MJD. A set of evaluation criteria, including -2 log-likelihood statistic, Akaike information criterion (AIC), bayesian information criterion (BIC), Nagelkerke R-squared (Nagelkerke R^2), and Cox-Snell residual plot, were used to identify the best model. RESULTS: Among these 6 parametric survival models, the logistic model had the lowest -2 log-likelihood (6,560.12), AIC (6,566.12), and BIC (6,566.14) and the highest value of Nagelkerke R^2 (0.54), with the closest graph to the bisector Cox-Snell residual graph. Therefore, the logistic survival model was the best fit to the studied data. Using the optimal logistic survival model, we indicated the age-specific probability distribution of AAO according to the CAG repeat size and current age. CONCLUSIONS: We first demonstrated that the logistic survival model provided the best fit for AAO prediction in patients with SCA3/MJD from mainland China. This optimal model can be valuable in clinical and research. However, the rigorous clinical testing and practice of other independent cohorts are needed for its clinical application. A unified model across multiethnic cohorts is worth further exploration by identifying regional differences and significant modifiers in AAO determination.

The genome of Magnolia biondii Pamp. provides insights into the evolution of Magnoliales and biosynthesis of terpenoids.

Magnolia biondii Pamp. (Magnoliaceae, magnoliids) is a phylogenetically, economically, and medicinally important ornamental tree species widely grown and cultivated in the north-temperate regions of China. Determining the genome sequence of M. biondii would help resolve the phylogenetic uncertainty of magnoliids and improve the understanding of individual trait evolution within the Magnolia genus. We assembled a chromosome-level reference genome of M. biondii using ~67, ~175, and ~154 Gb of raw DNA sequences generated via Pacific Biosciences single-molecule real-time sequencing, 10X Genomics Chromium, and Hi-C scaffolding strategies, respectively. The final genome assembly was ~2.22 Gb, with a contig N50 value of 269.11 kb and a BUSCO complete gene percentage of 91.90%. Approximately 89.17% of the genome was organized into 19 chromosomes, resulting in a scaffold N50 of 92.86 Mb. The genome contained 47,547 protein-coding genes, accounting for 23.47% of the genome length, whereas 66.48% of the genome length consisted of repetitive elements. We confirmed a WGD event that occurred very close to the time of the split between the Magnoliales and Laurales. Functional enrichment of the Magnolia-specific and expanded gene families highlighted genes involved in the biosynthesis of secondary metabolites, plant-pathogen interactions, and responses to stimuli, which may improve the ecological fitness and biological adaptability of the lineage. Phylogenomic analyses revealed a sister relationship of magnoliids and Chloranthaceae, which are sister to a clade comprising monocots and eudicots. The genome sequence of M. biondii could lead to trait improvement, germplasm conservation, and evolutionary studies on the rapid radiation of early angiosperms.

Prediction of the Age at Onset of Spinocerebellar Ataxia Type 3 with Machine Learning.

BACKGROUND: In polyglutamine (polyQ) disease, the investigation of the prediction of a patient's age at onset (AAO) facilitates the development of disease-modifying intervention and underpins the delay of disease onset and progression. Few polyQ disease studies have evaluated AAO predicted by machine-learning algorithms and linear regression methods. OBJECTIVE: The objective of this study was to develop a machine-learning model for AAO prediction in the largest spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) population from mainland China. METHODS: In this observational study, we introduced an innovative approach by systematically comparing the performance of 7 machine-learning algorithms with linear regression to explore AAO prediction in SCA3/MJD using CAG expansions of 10 polyQ-related genes, sex, and parental origin. RESULTS: Similar prediction performance of testing set and training set in each models were identified and few overfitting of training data was observed. Overall, the machine-learning-based XGBoost model exhibited the most favorable performance in AAO prediction over the traditional linear regression method and other 6 machine-learning algorithms for the training set and testing set. The optimal XGBoost model achieved mean absolute error, root mean square error, and median absolute error of 5.56, 7.13, 4.15 years, respectively, in testing set 1, with mean absolute error (4.78 years), root mean square error (6.31 years), and median absolute error (3.59 years) in testing set 2. CONCLUSION: Machine-learning algorithms can be used to predict AAO in patients with SCA3/MJD. The optimal XGBoost algorithm can provide a good reference for the establishment and optimization of prediction models for SCA3/MJD or other polyQ diseases. © 2020 International Parkinson and Movement Disorder Society.

Biallelic Intronic AAGGG Expansion of RFC1 is Related to Multiple System Atrophy.

OBJECTIVE: A recessive biallelic repeat expansion, (AAGGG)exp , in the RFC1 gene has been reported to be a frequent cause of late-onset ataxia. For cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS), the recessive biallelic (AAGGG)exp genotype was present in ~92% of cases. This study aimed to examine whether the pentanucleotide repeat (PNR) was related to multiple system atrophy (MSA), which shares a spectrum of symptoms with CANVAS. METHODS: In this study, we screened the pathogenic (AAGGG)exp repeat and 5 other PNRs in 104 Chinese sporadic adult-onset ataxia of unknown aetiology (SAOA) patients, 282 MSA patients, and 203 unaffected individuals. Multiple molecular genetic tests were used, including long-range polymerase chain reaction (PCR), repeat-primed PCR (RP-PCR), Sanger sequencing, and Southern blot. Comprehensive clinical assessments were conducted, including neurological examination, neuroimaging, nerve electrophysiology, and examination of vestibular function. RESULTS: We identified biallelic (AAGGG)exp in 1 SAOA patient and 3 MSA patients. Additionally, 1 MSA patient had the (AAGGG)exp /(AAAGG)exp genotype with uncertain pathogenicity. We also described the carrier frequency for different PNRs in our cohorts. Furthermore, we summarized the distinct phenotypes of affected patients, suggesting that biallelic (AAGGG)exp in RFC1 could be associated with MSA and should be screened routinely in the MSA diagnostic workflow. INTERPRETATION: Our results expanded the clinical phenotypic spectrum of RFC1-related disorders and raised the possibility that MSA might share the same genetic background as CANVAS, which is crucial for re-evaluating the current CANVAS and MSA diagnostic criteria. ANN NEUROL 2020;88:1132-1143.

Generation and characterization of expressed sequence tags (ESTs) from coralloid root cDNA library of Cycas debaoensis.

A normalized full-length cDNA library was constructed from the coralloid roots of Cycas debaoensis by the DSN (duplex-specific nuclease) normalization method combined with the SMART (Switching Mechanism At 5' end of the RNA Transcript) technique. The titer of the original cDNA library was about 1.5 × 106 cfu·mL-1 and the average insertion size was about 1 kb with a high recombination rate (97%). The 5011 high-quality expressed sequence tags (ESTs) were obtained from 5393 randomly picked cDNA clones. Clustering and assembly of ESTs resulted in 2984 unique sequences, consisting of 618 contigs and 2366 singlets. EST sequence annotation revealed that 2333 and 1901 unigenes were functionally annotated in the NCBI non-redundant database and Swiss-Prot protein database, respectively. Functional analysis demonstrated that 1495 (50.1%) unigenes were associated with 4082 Gene Ontology (GO) terms. A total of 847 unigenes were grouped into 22 Cluster of Orthologous Groups (COG) functional categories. Based on the EST dataset, 22 ESTs that encoded putative receptor-like protein kinase (RLK) genes were screened. Furthermore, a total of 94 simple sequence repeats (SSRs) were discovered, of which 20 loci were successfully amplified in C. debaoensis. This study is the first EST analysis for the coralloid roots of C. debaoensis and provides a valuable genomic resource for novel gene discovery, gene expression and comparative genomics, conservation and management studies as well as applications in C. debaoensis and related cycad species.

SC79 protects retinal pigment epithelium cells from UV radiation via activating Akt-Nrf2 signaling.

Excessive Ultra-violet (UV) radiation causes oxidative damages and apoptosis in retinal pigment epithelium (RPE) cells. Here we tested the potential activity of SC79, a novel small molecule activator of Akt, against the process. We showed that SC79 activated Akt in primary and established (ARPE-19 line) RPE cells. It protected RPE cells from UV damages possibly via inhibiting cell apoptosis. Akt inhibition, via an Akt specific inhibitor (MK-2206) or Akt1 shRNA silence, almost abolished SC79-induced RPE cytoprotection. Further studies showed that SC79 activated Akt-dependent NF-E2-related factor 2 (Nrf2) signaling and inhibited UV-induced oxidative stress in RPE cells. Reversely, Nrf2 shRNA knockdown or S40T mutation attenuated SC79-induced anti-UV activity. For the in vivo studies, we showed that intravitreal injection of SC79 significantly protected mouse retina from light damages. Based on these results, we suggest that SC79 protects RPE cells from UV damages possibly via activating Akt-Nrf2 signaling axis.

3H-1,2-dithiole-3-thione protects retinal pigment epithelium cells against Ultra-violet radiation via activation of Akt-mTORC1-dependent Nrf2-HO-1 signaling.

Excessive UV radiation and reactive oxygen species (ROS) cause retinal pigment epithelium (RPE) cell injuries. Nrf2 regulates transcriptional activation of many anti-oxidant genes. Here, we tested the potential role of 3H-1,2-dithiole-3-thione (D3T) against UV or ROS damages in cultured RPE cells (both primary cells and ARPE-19 line). We showed that D3T significantly inhibited UV-/H2O2-induced RPE cell death and apoptosis. UV-stimulated ROS production was dramatically inhibited by D3T pretreatment. D3T induced Nrf2 phosphorylation in cultured RPE cells, causing Nrf2 disassociation with KEAP1 and its subsequent nuclear accumulation. This led to expression of antioxidant response elements (ARE)-dependent gene heme oxygenase-1 (HO-1). Nrf2-HO-1 activation was required for D3T-mediated cytoprotective effect. Nrf2 shRNA knockdown or S40T dominant negative mutation as well as the HO-1 inhibitor Zinc protoporphyrin (ZnPP) largely inhibited D3T's RPE cytoprotective effects against UV radiation. Yet, exogenous overexpression Nrf2 enhanced D3T's activity in RPE cells. Further studies showed that D3T activated Akt/mTORC1 in cultured RPE cells. Akt-mTORC1 inhibitors, or Akt1 knockdown by shRNA, not only inhibited D3T-induced Nrf2-HO-1 activation, but also abolished the RPE cytoprotective effects. In vivo, D3T intravitreal injection protected from light-induced retinal dysfunctions in mice. Thus, D3T protects RPE cells from UV-induced damages via activation of Akt-mTORC1-Nrf2-HO-1 signaling axis.

The historical demography and genetic variation of the endangered Cycas multipinnata (Cycadaceae) in the red river region, examined by chloroplast DNA sequences and microsatellite markers.

Cycas multipinnata C.J. Chen & S.Y. Yang is a cycad endemic to the Red River drainage region that occurs under evergreen forest on steep limestone slopes in Southwest China and northern Vietnam. It is listed as endangered due to habitat loss and over-collecting for the ornamental plant trade, and only several populations remain. In this study, we assess the genetic variation, population structure, and phylogeography of C. multipinnata populations to help develop strategies for the conservation of the species. 60 individuals from six populations were used for chloroplast DNA (cpDNA) sequencing and 100 individuals from five populations were genotyped using 17 nuclear microsatellites. High genetic differentiation among populations was detected, suggesting that pollen or seed dispersal was restricted within populations. Two main genetic clusters were observed in both the cpDNA and microsatellite loci, corresponding to Yunnan China and northern Vietnam. These clusters indicated low levels of gene flow between the regions since their divergence in the late Pleistocene, which was inferred from both Bayesian and coalescent analysis. In addition, the result of a Bayesian skyline plot based on cpDNA portrayed a long history of constant population size followed by a decline in the last 50,000 years of C. multipinnata that was perhaps affected by the Quaternary glaciations, a finding that was also supported by the Garza-Williamson index calculated from the microsatellite data. The genetic consequences produced by climatic oscillations and anthropogenic disturbances are considered key pressures on C. multipinnata. To establish a conservation management plan, each population of C. multipinnata should be recognized as a Management Unit (MU). In situ and ex situ actions, such as controlling overexploitation and creating a germplasm bank with high genetic diversity, should be urgently implemented to preserve this species.