Responsible for the ongoing coronavirus disease 19 (COVID-19) pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects host cells through binding of the viral spike protein (SARS-2-S) to the cell-surface receptor angiotensin-converting enzyme 2 (ACE2). Here we show that the high-density lipoprotein (HDL) scavenger receptor B type 1 (SR-B1) facilitates ACE2-dependent entry of SARS-CoV-2. We find that the S1 subunit of SARS-2-S binds to cholesterol and possibly to HDL components to enhance viral uptake in vitro. SR-B1 expression facilitates SARS-CoV-2 entry into ACE2-expressing cells by augmenting virus attachment. Blockade of the cholesterol-binding site on SARS-2-S1 with a monoclonal antibody, or treatment of cultured cells with pharmacological SR-B1 antagonists, inhibits HDL-enhanced SARS-CoV-2 infection. We further show that SR-B1 is coexpressed with ACE2 in human pulmonary tissue and in several extrapulmonary tissues. Our findings reveal that SR-B1 acts as a host factor that promotes SARS-CoV-2 entry and may help explain viral tropism, identify a possible molecular connection between COVID-19 and lipoprotein metabolism, and highlight SR-B1 as a potential therapeutic target to interfere with SARS-CoV-2 infection.

LoRaWAN is a MAC-layer protocol for long-range low-power communication. Since its release in 2015, it has experienced a rapid adoption in the field of Internet-of-Things (IoT). However, given that LoRaWAN is fairly novel, its level of security has not been thoroughly analyzed, which is the main objective of this paper. We highlight the security features present in LoRaWAN, namely activation methods, key management, cryptography, counter management, and message acknowledgement. Subsequently, we discover and analyze several vulnerabilities of LoRaWAN. In particular, we design and describe 5 attacks: (1) a replay attack that leads to a selective denial-of-service on individual IoT devices, (2) plaintext recovery, (3) malicious message modification, (4) falsification of delivery reports, and (5) a battery exhaustion attack. As a proof-ofconcept, the attacks are implemented and executed in a controlled LoRaWAN environment. Finally, we discuss how these attacks can be mitigated or protected against.

Maleae consists of economically and ecologically important plants. However, there are considerable disputes on generic circumscription due to the lack of a reliable phylogeny at generic level. In this study, molecular phylogeny of 35 generally accepted genera in Maleae is established using 15 chloroplast regions. Gillenia is the most basal clade of Maleae, followed by Kageneckia + Lindleya, Vauquelinia, and a typical radiation clade, the core Maleae, suggesting that the proposal of four subtribes is reasonable. In the core Maleae including 31 genera, chloroplast gene data support that the four Malus-related genera should better be merged into one genus and the six Sorbus-related genera would be classified into two genera, whereas all Photinia-related genera should be accepted as distinct genera. Although the phylogenetic relationships among the genera in Maleae are much clearer than before, it is still premature to make a formal taxonomic treatment for these genera.

The recently emerged pathogenic SARS-coronavirus 2 (SARS-CoV-2) has spread rapidly, leading to a global pandemic. In this study, we show that SARS-CoV-2 infection was associated with clinically significant lower level of HDL cholesterol (HDL-C), which can be used as indicators of disease severity and poor prognosis. Importantly, we found the spike protein of SARS-CoV-2 (SARS-2-S) bound to HDL. Antagonists of HDL receptor-Scavenger receptor class B type I (SR-B1), strongly inhibited SARS-CoV-2 infection. Notably, the lipids transfer function of SR-B1 was indispensable for this inhibition, offering explanations for the reduced serum HDL level observed in COVID-19 patients. Basing on findings here, we speculate that SR-B1-mediated pulmonary HDL-vitamin E uptake could participate in mediating SARS-CoV-2 infection of lung cells, and the unique expression profile of SR-B1 may also affect SARS-CoV-2 cell and tissue tropism. These findings might help to provide further insights into viral transmission, pathological characteristics and reveal therapeutic targets.

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The simultaneous production of hydrogen and biomass-based chemicals from biomass-derived feedstocks aqueous solutions via photocatalysis is appealing because no additional sacrificial agent is needed. However, limited successes have been achieved....

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Background Alfalfa (Medicago sativa) is an important forage material widely used for animal feed production. Ensiling is an effective method for preserving alfalfa, but it has shown some limitations in the production of high-quality alfalfa silage due to its low water soluble carbohydrates (WSC) content and high buffering capacity. Lactic acid bacteria (LAB) and cellulase are often used as silage additives to promote the ensiling process and enhance fermentation quality. Methods Experiments were conducted to investigate the effects of ferulic acid esterase (FAE)-producing Lactobacillus fermentum 17SD-2 (LF) and cellulase (CE) on the fermentation quality and microbial community of alfalfa silage. After 60 days of ensiling, analysis of fermentation quality and bacterial diversity in alfalfa silages were conducted using high-performance liquid chromatography and high-throughput sequencing methods. Results Alfalfa was ensiled with additives (LF, CE, and LF+CE) or without additives for 60 days. All additives increased lactic acid and decreased pH values and ammonia-N contents compared to control. Among all treatments, the combined addition of LF and CE showed lowest pH (4.66) and ammonia-N (NH3-N, 0.57% DM) content, highest contents of lactic acid (LA, 10.51% DM), dry matter (DM, 22.54%) and crude protein (CP, 24.60% DM). Combined addition of LF and CE performed better in reducing neutral detergent fiber (NDF, 29.76% DM) and acid detergent fiber (ADF, 22.86% DM) contents than the addition of LF (33.71, 27.39% DM) or CE (32.07, 25.45% DM) alone. Moreover, the microbial analysis indicated that LF+CE treatments increased the abundance of desirable Lactobacillus and inhibited the growth of detrimental Enterobacter and Clostridia in alfalfa silage. Discussion Combined addition of FAE-producing LF and CE is more effective than treatments of LF or CE alone in improving fermentation quality and nutrition values of alfalfa silage. This is likely due to a synergistic effect of CE and FAE produced by LF on plant cell wall degradation, indicating that these additives promote each other to improve fiber degradation and silage fermentation. In conclusion, combined addition of FAE-producing LF and CE could be a feasible way to improve alfalfa silage quality.