Modelling human hepato-biliary-pancreatic organogenesis from the foregut-midgut boundary.

Organogenesis is a complex and interconnected process that is orchestrated by multiple boundary tissue interactions1-7. However, it remains unclear how individual, neighbouring components coordinate to establish an integral multi-organ structure. Here we report the continuous patterning and dynamic morphogenesis of hepatic, biliary and pancreatic structures, invaginating from a three-dimensional culture of human pluripotent stem cells. The boundary interactions between anterior and posterior gut spheroids differentiated from human pluripotent stem cells enables retinoic acid-dependent emergence of hepato-biliary-pancreatic organ domains specified at the foregut-midgut boundary organoids in the absence of extrinsic factors. Whereas transplant-derived tissues are dominated by midgut derivatives, long-term-cultured microdissected hepato-biliary-pancreatic organoids develop into segregated multi-organ anlages, which then recapitulate early morphogenetic events including the invagination and branching of three different and interconnected organ structures, reminiscent of tissues derived from mouse explanted foregut-midgut culture. Mis-segregation of multi-organ domains caused by a genetic mutation in HES1 abolishes the biliary specification potential in culture, as seen in vivo8,9. In sum, we demonstrate that the experimental multi-organ integrated model can be established by the juxtapositioning of foregut and midgut tissues, and potentially serves as a tractable, manipulatable and easily accessible model for the study of complex human endoderm organogenesis.

Identification of a KLF5-dependent program and drug development for skeletal muscle atrophy.

Skeletal muscle atrophy is caused by various conditions, including aging, disuse related to a sedentary lifestyle and lack of physical activity, and cachexia. Our insufficient understanding of the molecular mechanism underlying muscle atrophy limits the targets for the development of effective pharmacologic treatments and preventions. Here, we identified Krüppel-like factor 5 (KLF5), a zinc-finger transcription factor, as a key mediator of the early muscle atrophy program. KLF5 was up-regulated in atrophying myotubes as an early response to dexamethasone or simulated microgravity in vitro. Skeletal muscle-selective deletion of Klf5 significantly attenuated muscle atrophy induced by mechanical unloading in mice. Transcriptome- and genome-wide chromatin accessibility analyses revealed that KLF5 regulates atrophy-related programs, including metabolic changes and E3-ubiquitin ligase-mediated proteolysis, in coordination with Foxo1. The synthetic retinoic acid receptor agonist Am80, a KLF5 inhibitor, suppressed both dexamethasone- and microgravity-induced muscle atrophy in vitro and oral Am80 ameliorated disuse- and dexamethasone-induced atrophy in mice. Moreover, in three independent sets of transcriptomic data from human skeletal muscle, KLF5 expression significantly increased with age and the presence of sarcopenia and correlated positively with the expression of the atrophy-related ubiquitin ligase genes FBXO32 and TRIM63 These findings demonstrate that KLF5 is a key transcriptional regulator mediating muscle atrophy and that pharmacological intervention with Am80 is a potentially preventive treatment.

Prognostic significance of pre-treatment albumin-bilirubin grade in metastatic urothelial carcinoma receiving pembrolizumab.

BACKGROUND: Pre-treatment albumin-bilirubin grade is a useful biomarker for predicting prognosis in patients receiving immune checkpoint inhibitors for advanced malignancies. We evaluated the prognostic impact of pre-treatment albumin-bilirubin grade in patients receiving pembrolizumab for metastatic urothelial carcinoma. METHODS: In this multicenter retrospective study, we calculated pre-treatment albumin-bilirubin scores of 96 patients who received pembrolizumab for metastatic urothelial carcinoma between January 2018 and March 2022. Patients were classified according to albumin-bilirubin grade. Progression-free survival and cancer-specific survival were compared between the groups. To evaluate the prognostic impact of pre-treatment albumin-bilirubin grade, we also performed Cox proportional regression analyses for progression-free survival and cancer-specific survival. RESULTS: The median pre-treatment albumin bilirubin score was -2.52 (quartile: -2.76 to -2.10), and albumin-bilirubin grade was grade 1 in 37 patients (39%), grade 2a in 30 patients (31%), 2b in 22 patients (23%) and grade 3 in 7 patients (7%). The median progression-free survival and cancer-specific survival were 2 and 7 months, respectively. Progression-free survival and cancer-specific survival were significantly different between the albumin-bilirubin grade groups (P < 0.01 and P < 0.01, respectively) and prognosis became poorer as albumin-bilirubin grade increased. High albumin-bilirubin grade was shown in multivariable Cox proportional analyses to be independently associated with both poor progression-free survival and poor cancer-specific survival. CONCLUSIONS: High pre-treatment albumin-bilirubin grade could be a significant independent predictor of poor prognosis in patients receiving pembrolizumab for advanced urothelial carcinoma.

High-Fidelity Drug-Induced Liver Injury Screen Using Human Pluripotent Stem Cell-Derived Organoids.

BACKGROUND & AIMS: Preclinical identification of compounds at risk of causing drug induced liver injury (DILI) remains a significant challenge in drug development, highlighting a need for a predictive human system to study complicated DILI mechanism and susceptibility to individual drug. Here, we established a human liver organoid (HLO)-based screening model for analyzing DILI pathology at organoid resolution. METHODS: We first developed a reproducible method to generate HLO from storable foregut progenitors from pluripotent stem cell (PSC) lines with reproducible bile transport function. The qRT-PCR and single cell RNA-seq determined hepatocyte transcriptomic state in cells of HLO relative to primary hepatocytes. Histological and ultrastructural analyses were performed to evaluate micro-anatomical architecture. HLO based drug-induced liver injury assays were transformed into a 384 well based high-speed live imaging platform. RESULTS: HLO, generated from 10 different pluripotent stem cell lines, contain polarized immature hepatocytes with bile canaliculi-like architecture, establishing the unidirectional bile acid transport pathway. Single cell RNA-seq profiling identified diverse and zonal hepatocytic populations that in part emulate primary adult hepatocytes. The accumulation of fluorescent bile acid into organoid was impaired by CRISPR-Cas9-based gene editing and transporter inhibitor treatment with BSEP. Furthermore, we successfully developed an organoid based assay with multiplexed readouts measuring viability, cholestatic and/or mitochondrial toxicity with high predictive values for 238 marketed drugs at 4 different concentrations (Sensitivity: 88.7%, Specificity: 88.9%). LoT positively predicts genomic predisposition (CYP2C9∗2) for Bosentan-induced cholestasis. CONCLUSIONS: Liver organoid-based Toxicity screen (LoT) is a potential assay system for liver toxicology studies, facilitating compound optimization, mechanistic study, and precision medicine as well as drug screening applications.

Myosteatosis as a novel predictor of urinary incontinence after robot-assisted radical prostatectomy.

OBJECTIVES: To evaluate the impact of sarcopenia and myosteatosis on urinary incontinence after prostatectomy. METHODS: We retrospectively reviewed consecutive patients who underwent robot-assisted radical prostatectomy without nerve sparing between December 2012 and March 2019. Psoas muscle index and average total psoas density, which were measured on preoperative computed tomography images at level L3, were used to evaluate sarcopenia and myosteatosis, respectively. In addition, several magnetic resonance imaging variables associated with pelvic muscles, the urethra and the prostate were measured. Urinary continence was defined as non-use or use of just one incontinence pad per day. Logistic regression analyses aimed to identify the predictors of urinary incontinence 3 and 12 months after surgery. RESULTS: Overall, 121 patients were included in the analysis. The incidence rates of urinary incontinence 3 and 12 months after surgery were 42% (51/121 cases) and 16% (19/121 cases), respectively. Logistic multivariable analysis showed that low average total psoas density was the only significant independent predictor of urinary incontinence 3 months after surgery (P < 0.01), and low obturator internus muscle thickness (P = 0.01), short membranous urethral length (P = 0.01) and low average total psoas density (P < 0.01) were significant independent predictors of urinary incontinence 12 months after surgery. By contrast, psoas muscle index was not statistically associated with urinary incontinence after surgery. CONCLUSIONS: Myosteatosis (low average total psoas density) could be a novel predictor of urinary incontinence after robot-assisted radical prostatectomy.

Impact of preoperative sarcopenia and myosteatosis on prognosis after radical cystectomy in patients with bladder cancer.

OBJECTIVE: To evaluate the prognostic impact of sarcopenia and myosteatosis on survival after radical cystectomy for bladder cancer. METHODS: We retrospectively reviewed consecutive patients who underwent radical cystectomy for bladder cancer between 2010 and 2019, and 123 patients were finally included in this single-center study. Pretreatment computed tomography images at the L3 level were used to calculate skeletal muscle index and skeletal muscle density. Sarcopenia and myosteatosis were diagnosed according to the gender-specific cutoff values of skeletal muscle index and skeletal muscle density used in a previous study. We compared overall survival and cancer-specific survival between patients with and without sarcopenia/myosteatosis. We also performed Cox proportional regression analyses to identify the predictors of overall survival and cancer-specific survival. RESULTS: The median patient age was 74 years, and 20 patients (16%) were female. Thirty-eight patients (31%) died from bladder cancer and 13 (11%) died from other causes. The patients with sarcopenia (n = 48, 39%) and those with myosteatosis (n = 101, 82%) had significantly lower overall survival and cancer-specific survival rates than those without sarcopenia and those without myosteatosis, respectively. In multivariable analysis, in addition to the number of pathological risk factors, both sarcopenia (P < 0.01) and myosteatosis (P = 0.04) were independent significant predictors of poor cancer-specific survival. CONCLUSIONS: In our experience, sarcopenia and myosteatosis are independent predictors of poor cancer-specific survival in patients undergoing radical cystectomy for bladder cancer. Sarcopenia is also associated with poor overall survival.

Nutritional modulation of mouse and human liver bud growth through a branched-chain amino acid metabolism.

Liver bud progenitors experience a transient amplification during the early organ growth phase, yet the mechanism responsible is not fully understood. Collective evidence highlights the specific requirements in stem cell metabolism for expanding organ progenitors during organogenesis and regeneration. Here, transcriptome analyses show that progenitors of the mouse and human liver bud growth stage specifically express the gene branched chain aminotransferase 1, encoding a known breakdown enzyme of branched-chain amino acids (BCAAs) for energy generation. Global metabolome analysis confirmed the active consumption of BCAAs in the growing liver bud, but not in the later fetal or adult liver. Consistently, maternal dietary restriction of BCAAs during pregnancy significantly abrogated the conceptus liver bud growth capability through a striking defect in hepatic progenitor expansion. Under defined conditions, the supplementation of L-valine specifically among the BCAAs promoted rigorous growth of the human liver bud organoid in culture by selectively amplifying self-renewing bi-potent hepatic progenitor cells. These results highlight a previously underappreciated role of branched-chain amino acid metabolism in regulating mouse and human liver bud growth that can be modulated by maternal nutrition in vivo or cultural supplement in vitro.

Vascularized and functional human liver from an iPSC-derived organ bud transplant.

A critical shortage of donor organs for treating end-stage organ failure highlights the urgent need for generating organs from human induced pluripotent stem cells (iPSCs). Despite many reports describing functional cell differentiation, no studies have succeeded in generating a three-dimensional vascularized organ such as liver. Here we show the generation of vascularized and functional human liver from human iPSCs by transplantation of liver buds created in vitro (iPSC-LBs). Specified hepatic cells (immature endodermal cells destined to track the hepatic cell fate) self-organized into three-dimensional iPSC-LBs by recapitulating organogenetic interactions between endothelial and mesenchymal cells. Immunostaining and gene-expression analyses revealed a resemblance between in vitro grown iPSC-LBs and in vivo liver buds. Human vasculatures in iPSC-LB transplants became functional by connecting to the host vessels within 48 hours. The formation of functional vasculatures stimulated the maturation of iPSC-LBs into tissue resembling the adult liver. Highly metabolic iPSC-derived tissue performed liver-specific functions such as protein production and human-specific drug metabolism without recipient liver replacement. Furthermore, mesenteric transplantation of iPSC-LBs rescued the drug-induced lethal liver failure model. To our knowledge, this is the first report demonstrating the generation of a functional human organ from pluripotent stem cells. Although efforts must ensue to translate these techniques to treatments for patients, this proof-of-concept demonstration of organ-bud transplantation provides a promising new approach to study regenerative medicine.

A comparative study of wavelength-dependent photoinactivation in photosystem II of drought-tolerant photosynthetic organisms in Antarctica and the potential risks of photoinhibition in the habitat.

Background and Aims: All photosynthetic organisms are faced with photoinhibition, which would lead to death in severe environments. Because light quality and light intensity fluctuate dynamically in natural microenvironments, quantitative and qualitative analysis of photoinhibition is important to clarify how this environmental pressure has impacted ecological behaviour in different organisms. Methods: We evaluated the wavelength dependency of photoinactivation to photosystem II (PSII) of Prasiola crispa (green alga), Umbilicaria decussata (lichen) and Ceratodon purpureus (bryophyte) harvested from East Antarctica. For evaluation, we calculated reaction coefficients, Epis, of PSII photoinactivation against energy dose using a large spectrograph. Daily fluctuation of the rate coefficient of photoinactivation, kpi, was estimated from Epis and ambient light spectra measured during the summer season. Key Results: Wavelength dependency of PSII photoinactivation was different for the three species, although they form colonies in close proximity to each other in Antarctica. The lichen exhibited substantial resistance to photoinactivation at all wavelengths, while the bryophyte showed sensitivity only to UV-B light (<325 nm). On the other hand, the green alga, P. crispa, showed ten times higher Epi to UV-B light than the bryophyte. It was much more sensitive to UV-A (325-400 nm). The risk of photoinhibition fluctuated considerably throughout the day. On the other hand, Epis were reduced dramatically for dehydrated compared with hydrated P. crispa. Conclusions: The deduced rate coefficients of photoinactivation under ambient sunlight suggested that P. crispa needs to pay a greater cost to recover from photodamage than the lichen or the bryophyte in order to keep sufficient photosynthetic activity under the Antarctic habitat. A newly identified drought-induced protection mechanism appears to operate in P. crispa, and it plays a critical role in preventing the oxygen-evolving complex from photoinactivation when the repair cycle is inhibited by dehydration.

Upper urinary tract stone disease in patients with poor performance status: active stone removal or conservative management?

BACKGROUND: It remains controversial as to whether active stone removal should be performed in patients with poor performance status because of their short life expectancy and perioperative risks. Our objectives were to evaluate treatment outcomes of active stone removal in patients with poor performance status and to compare life prognosis with those managed conservatively. METHODS: We retrospectively reviewed 74 patients with Eastern Cooperative Oncology Group performance status 3 or 4 treated for upper urinary tract calculi at our four hospitals between January 2009 and March 2016. Patients were classified into either surgical treatment group or conservative management group based on the presence of active stone removal. Stone-free rate and perioperative complications in surgical treatment group were reviewed. In addition, we compared overall survival and stone-specific survival between the two groups. Cox proportional hazards analysis was performed to investigate predictors of overall survival and stone-specific survival. RESULTS: Fifty-two patients (70.3%) underwent active stone removal (surgical treatment group) by extracorporeal shock wave lithotripsy (n = 6), ureteroscopy (n = 39), percutaneous nephrolithotomy (n = 6) or nephrectomy (n = 1). The overall stone-free rate was 78.8% and perioperative complication was observed in nine patients (17.3%). Conservative treatment was undergone by 22 patients (29.7%) (conservative management group). Two-year overall survival rates in surgical treatment and conservative management groups were 88.0% and 38.4%, respectively (p < 0.01) and two-year stone-specific survival rates in the two groups were 100.0% and 61.3%, respectively (p < 0.01). On multivariate analysis, stone removal was not significant, but was considered a possible favorable predictor for overall survival (p = 0.07). Moreover, stone removal was the only independent predictor of stone-specific survival (p < 0.01). CONCLUSIONS: Active stone removal for patients with poor performance status could be performed safely and effectively. Compared to conservative management, surgical stone treatment achieved longer overall survival and stone-specific survival.

Macrocystic ductal adenocarcinoma of prostate: A rare gross appearance of prostate cancer.

Macroscopic cyst-formation by prostatic adenocarcinoma, herein referred to as macrocystic prostatic adenocarcinoma (MPA), is extremely rare. To date, no studies of prostate cancer performed based on gross cystic appearance have been reported. MPA can include various diseases, one of which is cystadenocarcinoma. Several cases of ductal adenocarcinoma exhibiting a macrocystic appearance have recently been reported; however, the histological and clinicopathological characteristics of MPAs have yet to be characterized and established. Therefore, we aimed to determine the histological and clinicopathological characteristics of MPA, via a multi-institutional investigation. We discovered five patients with MPA out of 1559 treated patients (0.32%); all cases were ductal adenocarcinomas. MPA was found to have three growth patterns: Two cases showed a prevalence of exuberant papillary proliferation with a fibrovascular core in the macroscopic multilocular cysts. Two others predominantly exhibited multilocular cysts lined by flat epithelium with foci of low papillae, and the fifth had a cystic lesion with intracancerous necrosis. Three of the cases showed extraprostatic invasion; however, none of the patients experienced recurrence during the follow-up period. Each predominant growth pattern tended to exhibit unique clinicopathological characteristics with respect to serum prostate specific antigen level and tumor size and location. In conclusion, we demonstrated that MPA is a ductal adenocarcinoma that is composed of intracystic exuberant papillary proliferation and flat proliferation with foci of low papillae, both of which might exhibit different clinicopathololgical appearances.

Intraspinal collateral circulation to the artery of Adamkiewicz detected with intra-arterial injected computed tomographic angiography.

When the intercostal and lumbar arteries are occluded by plaque or thrombus, spinal cord perfusion depends on collateral circulation. Some reports have demonstrated collateral circulation to the artery of Adamkiewicz via computed tomography and magnetic resonance angiographies. However, intraspinal collateral circulation to the artery of Adamkiewicz along the spinal cord has not been reported previously. Here, we report two patients with intraspinal collateral circulation to the artery of Adamkiewicz along the spinal cord that was detected with intra-arterial injected computed tomography angiography.

Prognostic factors and risk stratification in patients with castration-resistant prostate cancer receiving docetaxel-based chemotherapy.

BACKGROUND: While novel drugs have been developed, docetaxel remains one of the standard initial systemic therapies for castration-resistant prostate cancer (CRPC) patients. Despite the excellent anti-tumor effect of docetaxel, its severe adverse effects sometimes distress patients. Therefore, it would be very helpful to predict the efficacy of docetaxel before treatment. The aims of this study were to evaluate the potential value of patient characteristics in predicting overall survival (OS) and to develop a risk classification for CRPC patients treated with docetaxel-based chemotherapy. METHODS: This study included 79 patients with CRPC treated with docetaxel. The variables, including patient characteristics at diagnosis and at the start of chemotherapy, were retrospectively collected. Prognostic factors predicting OS were analyzed using the Cox proportional hazard model. Risk stratification for overall survival was determined based on the results of multivariate analysis. RESULTS: PSA response ≥50 % was observed in 55 (69.6 %) of all patients, and the median OS was 22.5 months. The multivariate analysis showed that age, serum PSA level at the start of chemotherapy, and Hb were independent prognostic factors for OS. In addition, ECOG performance status (PS) and the CRP-to-albumin ratio were not significant but were considered possible predictors for OS. Risk stratification according to the number of these risk factors could effectively stratify CRPC patients treated with docetaxel in terms of OS. CONCLUSIONS: Age, serum PSA level at the start of chemotherapy, and Hb were identified as independent prognostic factors of OS. ECOG PS and the CRP-to-albumin ratio were not significant, but were considered possible predictors for OS in Japanese CRPC patients treated with docetaxel. Risk stratification based on these factors could be helpful for estimating overall survival.

Ring1B promotes hepatic stem/progenitor cell expansion through simultaneous suppression of Cdkn1a and Cdkn2a in mice.

UNLABELLED: Polycomb-group (PcG) proteins play crucial roles in self-renewal of stem cells by suppressing a host of genes through histone modifications. Identification of the downstream genes of PcG proteins is essential for elucidation of the molecular mechanisms of stem cell self-renewal. However, little is known about the PcG target genes in tissue stem cells. We found that the PcG protein, Ring1B, which regulates expression of various genes through monoubiquitination of histone H2AK119, is essential for expansion of hepatic stem/progenitor cells. In mouse embryos with a conditional knockout of Ring1B, we found that the lack of Ring1B inhibited proliferation and differentiation of hepatic stem/progenitor cells and thereby inhibited hepatic organogenesis. These events were characterized by derepression of cyclin-dependent kinase inhibitors (CDKIs) Cdkn1a and Cdkn2a, known negative regulators of cell proliferation. We conducted clonal culture experiments with hepatic stem/progenitor cells to investigate the individual genetic functions of Ring1B, Cdkn1a, and Cdkn2a. The data showed that the cell-cycle inhibition caused by Ring1B depletion was reversed when Cdkn1a and Cdkn2a were suppressed simultaneously, but not when they were suppressed individually. CONCLUSION: Our results show that expansion of hepatic stem/progenitor cells requires Ring1B-mediated epigenetic silencing of Cdkn1a and Cdkn2a, demonstrating that Ring1B simultaneously regulates multiple CDKIs in tissue stem/progenitor cells.

Ideal osmotic spaces for chlorobionts or cyanobionts are differentially realized by lichenized fungi.

Lichens result from symbioses between a fungus and either a green alga or a cyanobacterium. They are known to exhibit extreme desiccation tolerance. We investigated the mechanism that makes photobionts biologically active under severe desiccation using green algal lichens (chlorolichens), cyanobacterial lichens (cyanolichens), a cephalodia-possessing lichen composed of green algal and cyanobacterial parts within the same thallus, a green algal photobiont, an aerial green alga, and a terrestrial cyanobacterium. The photosynthetic response to dehydration by the cyanolichen was almost the same as that of the terrestrial cyanobacterium but was more sensitive than that of the chlorolichen or the chlorobiont. Different responses to dehydration were closely related to cellular osmolarity; osmolarity was comparable between the cyanolichen and a cyanobacterium as well as between a chlorolichen and a green alga. In the cephalodium-possessing lichen, osmolarity and the effect of dehydration on cephalodia were similar to those exhibited by cyanolichens. The green algal part response was similar to those exhibited by chlorolichens. Through the analysis of cellular osmolarity, it was clearly shown that photobionts retain their original properties as free-living organisms even after lichenization.

[Surgery for Ventricular Tachycardia Arising from Left Ventricular Aneurysm in a Patient with Dilated Cardiomyopathy；Report of a Case].

A left ventricular aneurysm (LVA) generally results from myocardial infarction, but rarely LVA can be associated with dilated cardiomyopathy (DCM). We herein report a surgical case of malignant ventricular tachycardia (VT) in a patient with LVA associated with DCM. A 57-year-old woman was diagnosed with DCM and LVA when she 1st presented with sustained VT. She had anti-arrhythmic medical therapy and implantable cardiac defibrillator. Subsequently, she presented with recurrent monomorophic VT arising from the LVA. Because anti-arrhythmic medical therapy and endocardial ablation were not effective, the patient was performed left ventricular aneurysmectomy and encircling endocardial cryoablation and could achive good arrhythmic control and clinical outcome.

Androgen deprivation induces phenotypic plasticity and promotes resistance to molecular targeted therapy in a PTEN-deficient mouse model of prostate cancer.

Castration-resistant prostate cancer is an incurable heterogeneous disease that is characterized by a complex multistep process involving different cellular and biochemical changes brought on by genetic and epigenetic alterations. These changes lead to the activation or overexpression of key survival pathways that also serve as potential therapeutic targets. Despite promising preclinical results, molecular targeted therapies aimed at such signaling pathways have so far been dismal. In the present study, we used a PTEN-deficient mouse model of prostate cancer to show that plasticity in castration-resistant tumors promotes therapeutic escape. Unlike castration-naïve tumors which depend on androgen receptor and PI3K/AKT signal activation for growth and survival, castration-resistant tumors undergo phenotypic plasticity leading to increased intratumoral heterogeneity. These tumors attain highly heterogeneous phenotypes that are characterized by cancer cells relying on alternate signal transduction pathways for growth and survival, such as mitogen-activated protein kinase and janus kinase/signal transducer and activator of transcription, and losing their dependence on PI3K signaling. These features thus enabled castration-resistant tumors to become insensitive to the therapeutic effects of PI3K/AKT targeted therapy. Overall, our findings provide evidence that androgen deprivation drives phenotypic plasticity in prostate cancer cells and implicate it as a crucial contributor to therapeutic resistance in castration-resistant prostate cancer. Therefore, incorporating intratumoral heterogeneity in a dynamic tumor model as a part of preclinical efficacy determination could improve prediction for response and provide better rationale for the development of more effective therapies.

Two types of fucoxanthin-chlorophyll-binding proteins I tightly bound to the photosystem I core complex in marine centric diatoms.

Intact fucoxanthin (Fucox)-chlorophyll (Chl)-binding protein I-photosystem I supercomplexes (FCPI-PSIs) were prepared by a newly developed simple fast procedure from centric diatoms Chaetoceros gracilis and Thalassiosira pseudonana to study the mechanism of their efficient solar energy accumulation. FCPI-PSI purified from C. gracilis contained 252 Chl a, 23 Chl c, 56 Fucox, 34 diadinoxanthin+diatoxanthin, 1 violaxanthin, 21 ß-carotene, and 2 menaquinone-4 per P700. The complex showed a high electron transfer activity at 185,000µmolmg Chl a(-1)·h(-1) to reduce methyl viologen from added cytochrome c6. We identified 14 and 21 FCP proteins in FCPI-PSI of C. gracilis and T. pseudonana, respectively, determined by N-terminal and internal amino acid sequences and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses. PsaO and a red lineage Chla/b-binding-like protein (RedCAP), Thaps3:270215, were also identified. Severe detergent treatment of FCPI-PSI released FCPI-1 first, leaving the FCPI-2-PSI-core complex. FCPI-1 contained more Chl c and showed Chl a fluorescence at a shorter wavelength than FCPI-2, suggesting an excitation-energy transfer from FCPI-1 to FCPI-2 and then to the PSI core. Fluorescence emission spectra at 17K in FCPI-2 varied depending on the excitation wavelength, suggesting two independent energy transfer routes. We formulated a model of FCPI-PSI based on the biochemical assay results.

Characterization of the far-red light absorbing light-harvesting chlorophyll a/b binding complex, a derivative of the distinctive Lhca gene family in green algae.

Prasiola crispa, an aerial green alga, exhibits remarkable adaptability to the extreme conditions of Antarctica by forming layered colonies capable of utilizing far-red light for photosynthesis. Despite a recent report on the structure of P. crispa's unique light-harvesting chlorophyll (Chl)-binding protein complex (Pc-frLHC), which facilitates far-red light absorption and uphill excitation energy transfer to photosystem II, the specific genes encoding the subunits of Pc-frLHC have not yet been identified. Here, we report a draft genome sequence of P. crispa strain 4113, originally isolated from soil samples on Ongul Island, Antarctica. We obtained a 92 Mbp sequence distributed in 1,045 scaffolds comprising 10,244 genes, reflecting 87.1% of the core eukaryotic gene set. Notably, 26 genes associated with the light-harvesting Chl a/b binding complex (LHC) were identified, including four Pc-frLHC genes, with similarity to a noncanonical Lhca gene with four transmembrane helices, such as Ot_Lhca6 in Ostreococcus tauri and Cr_LHCA2 in Chlamydomonas reinhardtii. A comparative analysis revealed that Pc-frLHC shares homology with certain Lhca genes found in Coccomyxa and Trebouxia species. This similarity indicates that Pc-frLHC has evolved from an ancestral Lhca gene with four transmembrane helices and branched out within the Trebouxiaceae family. Furthermore, RNA-seq analysis conducted during the initiation of Pc-frLHC gene induction under red light illumination indicated that Pc-frLHC genes were induced independently from other genes associated with photosystems or LHCs. Instead, the genes of transcription factors, helicases, chaperones, heat shock proteins, and components of blue light receptors were identified to coexpress with Pc-frLHC. Those kinds of information could provide insights into the expression mechanisms of Pc-frLHC and its evolutional development.

Corrigendum: Macrophage SREBP1 regulates skeletal muscle regeneration.

[This corrects the article DOI: 10.3389/fimmu.2023.1251784.].