The impact of COVID-19 on aquaculture in China and recommended strategies for mitigating the impact.

We carried out a preliminary investigation to study the impact of COVID-19 on aquaculture in China and identify the strategies and measures that have been taken by the Chinese Government. The investigation involved questionnaire surveys designed for all stakeholders along the industrial chain, including grow-out farmers, seed producers, fish processors, fish traders, and feed companies engaged in the catfish sector in Hubei Province and the tilapia sector in Guangdong Province during the strict period of control and after these control measures were lifted. We also attempted to summarize the government interventions and measures taken by different stakeholders along the value chain to minimize the damage caused by COVID-19 and support the recovery of different sectors in the aquaculture industry. We found that due to delayed harvesting, fish stocks were held-up in ponds and normal farming was interrupted. Farmers and traders were more severely impacted by the pandemic than other sectors. Furthermore, a series of strategies and measures are recommended to cope with the pandemic and other similar risks in the future. We expect that this study will provide good evidence for international societies to support the aquaculture industry in minimizing the impact of the pandemic and the rapid recovery of the industry in the post-pandemic period.

A Tumor-Penetrating Nanomedicine Improves the Chemoimmunotherapy of Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant tumors with a low survival rate. The therapeutic effect of chemotherapy and immunotherapy for PDAC is disappointing due to the presence of dense tumor stroma and immunosuppressive cells in the tumor microenvironment (TME). Herein, a tumor-penetrating nanoparticle is reported to modulate the deep microenvironment of PDAC for improved chemoimmunotherapy. The tumor pH-sensitive polymer is synthesized by conjugating N,N-dipentylethyl moieties and monomethoxylpoly(ethylene glycol) onto PAMAM dendrimer, into whose cavity a hydrophobic gemcitabine (Gem) prodrug is accommodated. They self-assemble into nanoparticles (denoted as SPN@Pro-Gem) with the size around 120 nm at neutral pH, but switch into small particles (≈8 nm) at tumor site to facilitate deep delivery of Gem into the tumor parenchyma. In addition to killing cancer cells that resided deeply in the tumor tissue, SPN@Pro-Gem could modulate the TME by reducing the abundance of tumor-associated macrophages and myeloid-derived suppressor cells as well as upregulating the expression level of PD-L1 of tumor cells. This collectively facilitates the infiltration of cytotoxic T cells into the tumors and renders checkpoint inhibitors more effective in previously unresponsive PDAC models. This study reveals a promising strategy for improving the chemoimmunotherapy of pancreatic cancer.

Nanoparticle-Enabled Dual Modulation of Phagocytic Signals to Improve Macrophage-Mediated Cancer Immunotherapy.

Activation of the phagocytosis of macrophages to tumor cells is an attractive strategy for cancer immunotherapy, but the effectiveness is limited by the fact that many tumor cells express an increased level of anti-phagocytic signals (e.g., CD47 molecules) on their surface. To promote phagocytosis of macrophages, a pro-phagocytic nanoparticle (SNPACALR&aCD47 ) that concurrently carries CD47 antibody (aCD47) and a pro-phagocytic molecule calreticulin (CALR) is constructed to simultaneously modulate the phagocytic signals of macrophages. SNPACALR&aCD47 can achieve targeted delivery to tumor cells by specifically binding to the cell-surface CD47 and block the CD47-SIRPα pathway to inhibit the "don't eat me" signal. Tumor cell-targeted delivery increases the exposure of recombinant CALR on the cell surface and stimulates an "eat me" signal. Simultaneous modulation of the two signals enhances the phagocytosis of 4T1 tumor cells by macrophages, which leads to significantly improved anti-tumor efficacy in vivo. The findings demonstrate that the concurrent blockade of anti-phagocytic signals and activation of pro-phagocytic signals can be effective in macrophage-mediated cancer immunotherapy.

Angiopep-2 conjugated nanoparticles loaded with doxorubicin for the treatment of primary central nervous system lymphoma.

Primary central nervous system lymphoma (PCNSL) is a rare brain tumor. Its therapeutic efficacy is much lower than that of traditional lymphoma, largely due to the presence of the blood-brain barrier (BBB), which hinders the effective drug delivery and deposition on the disease site. Angiopep-2 (ANG) can target low-density lipoprotein receptor-related protein (LRP) on the surface of brain capillary endothelial cells (BCECs) and exhibits high BBB transport capability. In this study, we designed an ANG conjugated poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-b-PCL) (APP) nanoparticle to deliver doxorubicin (DOX) for the treatment of PCNSL. Our data indicated that the targeted APP nanoparticles showed significantly increased cellular uptake by BCECs compared with the control nanoparticles. In the intracranial SU-DHL-2-LUC lymphoma xenograft mice model, APP enhanced drug deposition in tumor tissues, and DOX-loaded APP (APP@DOX) exhibited a better therapeutic effect than free DOX and nontargeted PP@DOX, which significantly prolonged the survival time of mice.

Electrochemical detection of microRNAs based on AuNPs/CNNS nanocomposite with Duplex-specific nuclease assisted target recycling to improve the sensitivity.

MicroRNAs (miRNAs) are important biomarkers in early diagnosis of disease. In this work, we developed a simple and effective electrochemical biosensor based on Au nanoparticles (AuNPs)/Carbon nitride nanosheet (CNNS) nanocomposite for the miRNAs detection. Duplex-specific nuclease (DSN) and hairpin structure probe were utilized to improve the sensitivity and selectivity respectively. In the presence of miRNA-21, the signal molecule could be released from the surface of the electrode and decrease the current peak in square wave voltammetry (SWV) test. Under the optimal conditions, the reported biosensor showed that the detection range of miRNA-21 is from 10 fM to 1 nM and detection limit is as low as 2.9 fM. Furthermore, the detection of miRNA-21 added in serum samples indicates the developed biosensor with good selectivity, stability and reproducibility which verify its potential to be used in the early diagnosis of diseases.

Tuning the near infrared II emitting wavelength of small molecule dyes by single atom alteration.

A series of small molecule dyes demonstrate the feasibility of manipulating Near Infrared II emission by simply altering the donors' heteroatoms, which involved both electronegativity and intramolecular steric effects. Furthermore, these dyes show high resolution and stability for in vivo imaging after being complexed with human serum albumin.

Reactive Oxygen Species and Nrf2: Functional and Transcriptional Regulators of Hematopoiesis.

Hematopoietic stem cells (HSCs) are characterized by self-renewal and multilineage differentiation potentials. Although they play a central role in hematopoietic homeostasis and bone marrow (BM) transplantation, they are affected by multiple environmental factors in the BM. Here, we review the effects of reactive oxygen species (ROS) and Nrf2 on HSC function and BM transplantation. HSCs reside in the hypoxic microenvironment of BM, and ROS play an important role in HSPC regulation. Recently, an extraphysiologic oxygen shock/stress phenomenon was identified in human cord blood HSCs collected under ambient air conditions. Moreover, Nrf2 has been recently recognized as a master transcriptional factor that regulates multiple antioxidant enzymes. Since several years, the role of Nrf2 in hematopoiesis has been extensively studied, which has functional similarities of cellular oxygen sensor hypoxia-inducible factor-1 as transcriptional factors. Increasing evidence has revealed that abnormally elevated ROS production due to factors such as genetic defects, aging, and ionizing radiation unexceptionally resulted in lethal impairment of HSC function and hematopoiesis. Both experimental and clinical studies have identified elevated ROS levels as a major culprit of ineffective BM transplantation. Lastly, we discuss the possibility of using small molecule antioxidants, such as N-acetyl cysteine, resveratrol, and curcumin, to augment HSC function and improve the therapeutic efficacy of BM transplantation. Further research on the function of ROS levels and improving the efficacy of BM transplantation may have a great potential for broad clinical applications of HSCs.

A molecular pathology method for sequential fluorescence in situ hybridization for multi-gene analysis at the single-cell level.

Multi-gene detection at the single-cell level is desirable to enable more precise genotyping of heterogeneous hematology and oncology samples. This study aimed to establish a single-cell multi-gene fluorescence in situ hybridization (FISH) method for use in molecular pathology analyses. Five fluorochromes were used to label different FISH gene probes, and 5 genes were detected using a five-color FISH protocol. After the first hybridization, the previous FISH probe set was stripped, and a second set of five-color FISH probes was used for rehybridization. After each hybridization, the fluorescence signals were recorded in 6 fluorescence filter channels that included DAPI, Spectrum Green™, Cy3™ v1, Texas Red, Cy5, and PF-415. A digital automatic relocation procedure was used to ensure that exactly the same microscopic field was studied in each stripping and hybridization cycle. By using this sequential stripping and rehybridization strategy, up to 20 genes can be detected within a single nucleus. In conclusion, a practical molecular pathology method was developed for analyzing multiple genes at the single-cell level.

Theaflavin ameliorates ionizing radiation-induced hematopoietic injury via the NRF2 pathway.

It has been well established that reactive oxygen species (ROS) play a critical role in ionizing radiation (IR)-induced hematopoietic injury. Theaflavin (TF), a polyphenolic compound from black tea, has been implicated in the regulation of endogenous cellular antioxidant systems. However, it remains unclear whether TF could ameliorate IR-induced hematopoietic injury, particularly the hematopoietic stem cell (HSC) injury. In this study, we explored the potential role of TF in IR-induced HSC injury and the underlying mechanism in a total body irradiation (TBI) mouse model. Our results showed that TF improved survival of irradiated wild-type mice and ameliorated TBI-induced hematopoietic injury by attenuating myelosuppression and myeloid skewing, increasing HSC frequency, and promoting reconstitution of irradiated HSCs. Furthermore, TF inhibited TBI-induced HSC senescence. These effects of TF were associated with a decline in ROS levels and DNA damage in irradiated HSCs. TF reduced oxidative stress mainly by up-regulating nuclear factor erythroid 2-related factor 2 (NRF2) and its downstream targets in irradiated Lineage-c-kit+ positive cells. However, TF failed to improve the survival, to increase HSC frequency and to reduce ROS levels of HSCs in irradiated Nrf2-/- mice. These findings suggest that TF ameliorates IR-induced HSC injury via the NRF2 pathway. Therefore, TF has the potential to be used as a radioprotective agent to ameliorate IR-induced hematopoietic injury.

Astaxanthin attenuates total body irradiation-induced hematopoietic system injury in mice via inhibition of oxidative stress and apoptosis.

BACKGROUND: The hematopoietic system is especially sensitive to total body irradiation (TBI), and myelosuppression is one of the major effects of TBI. Astaxanthin (ATX) is a powerful natural anti-oxidant with low toxicity. In this study, the effect of ATX on hematopoietic system injury after TBI was investigated. METHODS: Flow cytometry was used to detect the proportion of hematopoietic progenitor cells (HPCs) and hematopoietic stem cells (HSCs), the level of intracellular reactive oxygen species (ROS), expression of cytochrome C, cell apoptosis, and NRF2-related proteins. Immunofluorescence staining was used to detect Nrf2 translocation. Western blot analysis was used to evaluate the expression of apoptotic-related proteins. Enzymatic activities assay kits were used to analyze SOD2, CAT, and GPX1 activities. RESULTS: Compared with the TBI group, ATX can improve radiation-induced skewed differentiation of peripheral blood cells and accelerate hematopoietic self-renewal and regeneration. The radio-protective effect of ATX is probably attributable to the scavenging of ROS and the reduction of cell apoptosis. These changes were associated with increased activation of Nrf2 and downstream anti-oxidative proteins, and regulation of apoptotic-related proteins. CONCLUSIONS: This study suggests that ATX could be used as a potent therapeutic agent to protect the hematopoietic system against TBI-induced bone marrow suppression.

Vam3 ameliorates total body irradiation-induced hematopoietic system injury partly by regulating the expression of Nrf2-targeted genes.

Vam3, a resveratrol dimer, has been implicated in the regulation of chronic obstructive pulmonary disease. However, the effect of Vam3 on total body irradiation (TBI)-induced hematopoietic progenitor cells (HPCs), and hematopoietic stem cells (HSCs) injury is unknown. In this study, we examined whether Vam3could ameliorate hematopoietic system injury induced by TBI. Our results indicated that Vam3 alleviated TBI-induced injury by improving the self-renewal and differentiation of HPCs, and HSCs. Vam3 decreased the intracellular ROS levels in irradiated mice HPCs/HSCs or c-kit positive cells and inhibited apoptosis and DNA damage in LSKs and HPCs after TBI. Vam3 up-regulated the expression of Nrf2 and related genes and proteins in irradiated c-kit positive cells in vitro. However, Vam3 did not increase the cell viability or the number of CFU-GM c-kit positive cells in irradiated Nrf2-/- mice but decreased the cellular ROS level. The above data showed that Vam3 ameliorates total body irradiation-induced hematopoietic system injury and that Nrf2 is essential in mediating Vam3's protective effect on the proliferation of c-kit positive cells after irradiation but not its ability to scavenge for free radicals.

Dimethyl Fumarate and Monomethyl Fumarate Promote Post-Ischemic Recovery in Mice.

Oxidative stress plays an important role in cerebral ischemia-reperfusion injury. Dimethyl fumarate (DMF) and its primary metabolite monomethyl fumarate (MMF) are antioxidant agents that can activate the nuclear factor erythroid-2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway and induce the expression of antioxidant proteins. Here, we evaluated the impact of DMF and MMF on ischemia-induced brain injury and whether the Nrf2 pathway mediates the effects provided by DMF and MMF in cerebral ischemia-reperfusion injury. Using a mouse model of transient focal brain ischemia, we show that DMF and MMF significantly reduce neurological deficits, infarct volume, brain edema, and cell death. Further, DMF and MMF suppress glial activation following brain ischemia. Importantly, the protection of DMF and MMF was mostly evident during the subacute stage and was abolished in Nrf2-/- mice, indicating that the Nrf2 pathway is required for the beneficial effects of DMF and MMF. Together, our data indicate that DMF and MMF have therapeutic potential in cerebral ischemia-reperfusion injury and their protective role is likely mediated by the Nrf2 pathway.

Small-molecule inhibitors targeting INK4 protein p18(INK4C) enhance ex vivo expansion of haematopoietic stem cells.

Among cyclin-dependent kinase inhibitors that control the G1 phase in cell cycle, only p18 and p27 can negatively regulate haematopoietic stem cell (HSC) self-renewal. In this manuscript, we demonstrate that p18 protein is a more potent inhibitor of HSC self-renewal than p27 in mouse models and its deficiency promoted HSC expansion in long-term culture. Single-cell analysis indicated that deleting p18 gene favoured self-renewing division of HSC in vitro. Based on the structure of p18 protein and in-silico screening, we further identified novel smallmolecule inhibitors that can specifically block the activity of p18 protein. Our selected lead compounds were able to expand functional HSCs in a short-term culture. Thus, these putative small-molecule inhibitors for p18 protein are valuable for further dissecting the signalling pathways of stem cell self-renewal and may help develop more effective chemical agents for therapeutic expansion of HSC.

Fluorescence in situ hybridization (FISH): an increasingly demanded tool for biomarker research and personalized medicine.

Extensive studies of the genetic aberrations related to human diseases conducted over the last two decades have identified recurrent genomic abnormalities as potential driving factors underlying a variety of cancers. Over the time, a series of cutting-edge high-throughput genetic tests, such as microarrays and next-generation sequencing, have been developed and incorporated into routine clinical practice. Although it is a classical low-throughput cytogenetic test, fluorescence in situ hybridization (FISH) does not show signs of fading; on the contrary, it plays an increasingly important role in detecting specific biomarkers in solid and hematologic neoplasms and has therefore become an indispensable part of the rapidly developing field of personalized medicine. In this article, we have summarized the recent advances in FISH application for both de novo discovery and routine detection of chromosomal rearrangements, amplifications, and deletions that are associated with the pathogenesis of various hematopoietic and non-hematopoietic malignancies. In addition, we have reviewed the recent developments in FISH methodology as well.

The p53-PUMA axis suppresses iPSC generation.

Mechanisms underlying the reprogramming process of induced pluripotent stem cells remain poorly defined. Like tumorigenesis, generation of induced pluripotent stem cells was shown to be suppressed by the Trp53 (p53) pathway, at least in part via p21Cdkn1a (p21)-mediated cell cycle arrest. Here we examine the role of PUMA, a pro-apoptotic mediator of p53, during somatic reprogramming in comparison to p21 in the p53 pathway. Using mouse strains deficient in these molecules, we demonstrate that PUMA is an independent mediator of the negative effect of p53 on induced pluripotent stem cell induction. PUMA deficiency leads to a better survival rate associated with reduced DNA damage and fewer chromosomal aberrations in induced pluripotent stem cells, whereas loss of p21 or p53 results in an opposite outcome. Given these new findings, PUMA may serve as a distinct and more desirable target in the p53 pathway for induced pluripotent stem cell generation, thereby having important implications for potential therapeutic applications of induced pluripotent stem cells.

Hematopoietic stem cell regeneration enhanced by ectopic expression of ROS-detoxifying enzymes in transplant mice.

High levels of reactive oxygen species (ROS) can exhaust hematopoietic stem cells (HSCs). Thus, maintaining a low state of redox in HSCs by modulating ROS-detoxifying enzymes may augment the regeneration potential of HSCs. Our results show that basal expression of manganese superoxide dismutase (MnSOD) and catalase were at low levels in long-term and short-term repopulating HSCs, and administration of a MnSOD plasmid and lipofectin complex (MnSOD-PL) conferred radiation protection on irradiated recipient mice. To assess the intrinsic role of elevated MnSOD or catalase in HSCs and hematopoietic progenitor cells, the MnSOD or catalase gene was overexpressed in mouse hematopoietic cells via retroviral transduction. The impact of MnSOD and catalase on hematopoietic progenitor cells was mild, as measured by colony-forming units (CFUs). However, overexpressed catalase had a significant beneficial effect on long-term engraftment of transplanted HSCs, and this effect was further enhanced after an insult of low-dose γ-irradiation in the transplant mice. In contrast, overexpressed MnSOD exhibited an insignificant effect on long-term engraftment of transplanted HSCs, but had a significant beneficial effect after an insult of sublethal irradiation. Taken together, these results demonstrate that HSC function can be enhanced by ectopic expression of ROS-detoxifying enzymes, especially after radiation exposure in vivo.

An opposite effect of the CDK inhibitor, p18(INK4c) on embryonic stem cells compared with tumor and adult stem cells.

Self-renewal is a feature common to both adult and embryonic stem (ES) cells, as well as tumor stem cells (TSCs). The cyclin-dependent kinase inhibitor, p18(INK4c), is a known tumor suppressor that can inhibit self-renewal of tumor cells or adult stem cells. Here, we demonstrate an opposite effect of p18 on ES cells in comparison with teratoma cells. Our results unexpectedly showed that overexpression of p18 accelerated the growth of mouse ES cells and embryonic bodies (EB); on the contrary, inhibited the growth of late stage teratoma. Up-regulation of ES cell markers (i.e., Oct4, Nanog, Sox2, and Rex1) were detected in both ES and EB cells, while concomitant down-regulation of various differentiation markers was observed in EB cells. These results demonstrate that p18 has an opposite effect on ES cells as compared with tumor cells and adult stem cells. Mechanistically, expression of CDK4 was significantly increased with overexpression of p18 in ES cells, likely leading to a release of CDK2 from the inhibition by p21 and p27. As a result, self-renewal of ES cells was enhanced. Our current study suggests that targeting p18 in different cell types may yield different outcomes, thereby having implications for therapeutic manipulations of cell cycle machinery in stem cells.

[Differential expression of oxidative reductases in different subsets of mouse hematopoietic cells].

Hematopoietic stem cells (HSC) are the source of all blood cells, which can differentiate into various hematopoietic hierarchy cells. Physiological level of reactive oxygen species (ROS) plays an important role in regulating functions of HSC as excessive ROS is harmful to HSC. Oxidative reductases and antioxidants can eliminate cellular ROS to maintain ROS homeostasis and thus avoid excessive ROS-caused damages. There are several types of oxidative reductases in cells such as catalase, manganese superoxide dismutase (MnSOD), glutathione peroxidase 1 (GPX1), thioredoxin reductase 1 (Txrnd1) and Nqo1 [NAD(P)H dehydrogenase quinone 1]. However, the functional roles of various oxidative reductases in regulating ROS level in hematopoietic cells remain unclear. This study was to investigate the expression patterns of these oxidative reductases in mouse hematopoietic cells that were sorted out via flow cytometry and to find out important oxidative reductases involving in HSC ROS regulation. The expression of various oxidative reductases was detected by semi-quantitative real-time PCR. The results showed that the expression level of catalase in T cell population was 0.14 times that in LT-HSC population (P < 0.05). The expression levels of MnSOD in CLP population and myeloid cells were 0.56 and 0.47 times that in LT-HSC population respectively (P < 0.05). The expression levels of GPX1 in ST-HSC, GMP, Myeloid cells, MEP, T lymphocytes and B lymphocytes were 1.79, 2.96, 2.07, 0.58, 0.10, 0.6 times that in LT-HSC population respectively (P < 0.05). The expression levels of Txrnd1 in ST-HSC, MPP, CMP, GMP, Myeloid cells, T lymphocytes and B lymphocytes were 3.36, 3.18, 4.19, 6.39, 4.27, 0.016, 0.56 time that in LT-HSC population, respectively (P < 0.05). The expression levels of Nqo1 in ST-HSC, MPP, CMP, GMP, CLP and B cell were 0.30, 0.17, 0.25, 0.10, 0.04, 0.01 times that in LT-HSC population, respectively (P < 0.05). It is concluded that the expression levels of oxidative reductases (catalase, MnSOD, GPX1, Txrnd1 and Nqo1) in hematopoietic hierarchy cells are cell-type specific. It suggests that reductases may play divergent roles in various hematopoietic cell populations. More importantly, the expression level of Nqo1 in LT-HSC population significantly increased as compared with other cell populations, thereby suggesting its unique regulatory role in HSC.

Design, synthesis, and biological evaluation of 4-(5-dimethylamino-naphthalene-1-sulfon-amido)-3-(4-iodophenyl)butanoic acid as a novel molecular probe for apoptosis imaging.

Apoptosis (programmed cell death) plays a crucial role in the pathogenesis of many disorders, thus the detection of apoptotic cells can provide the physician with important information to further therapeutic strategies and would substantially advance patient care. A small molecule, 4-(5-dimethylamino-naphthalene-1-sulfonamido)-3-(4-iodo-phenyl)butanoic acid (DNSBA), was designed as a novel probe for imaging apoptosis and synthesized with good yield. The biological characterization demonstrated that DNSBA can be used to specifically and selectively detect apoptotic cancer cells at all stages. DNSBA is also designed as a potential SPECT and PET probe when labeled with radioiodine (I-123, -124, and -131).