What makes SARS-CoV-2 unique? Focusing on the spike protein.

Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) seriously threatens public health and safety. Genetic variants determine the expression of SARS-CoV-2 structural proteins, which are associated with enhanced transmissibility, enhanced virulence, and immune escape. Vaccination is encouraged as a public health intervention, and different types of vaccines are used worldwide. However, new variants continue to emerge, especially the Omicron complex, and the neutralizing antibody responses are diminished significantly. In this review, we outlined the uniqueness of SARS-CoV-2 from three perspectives. First, we described the detailed structure of the spike (S) protein, which is highly susceptible to mutations and contributes to the distinct infection cycle of the virus. Second, we systematically summarized the immunoglobulin G epitopes of SARS-CoV-2 and highlighted the central role of the nonconserved regions of the S protein in adaptive immune escape. Third, we provided an overview of the vaccines targeting the S protein and discussed the impact of the nonconserved regions on vaccine effectiveness. The characterization and identification of the structure and genomic organization of SARS-CoV-2 will help elucidate its mechanisms of viral mutation and infection and provide a basis for the selection of optimal treatments. The leaps in advancements regarding improved diagnosis, targeted vaccines and therapeutic remedies provide sound evidence showing that scientific understanding, research, and technology evolved at the pace of the pandemic.

Toward evaluation of multiresolution cortical thickness estimation with FreeSurfer, MaCRUISE, and BrainSuite.

Advances in Magnetic Resonance Imaging hardware and methodologies allow for promoting the cortical morphometry with submillimeter spatial resolution. In this paper, we generated 3D self-enhanced high-resolution (HR) MRI imaging, by adapting 1 deep learning architecture, and 3 standard pipelines, FreeSurfer, MaCRUISE, and BrainSuite, have been collectively employed to evaluate the cortical thickness. We systematically investigated the differences in cortical thickness estimation for MRI sequences at multiresolution homologously originated from the native image. It has been revealed that there systematically exhibited the preferences in determining both inner and outer cortical surfaces at higher resolution, yielding most deeper cortical surface placements toward GM/WM or GM/CSF boundaries, which directs a consistent reduction tendency of mean cortical thickness estimation; on the contrary, the lower resolution data will most probably provide a more coarse and rough evaluation in cortical surface reconstruction, resulting in a relatively thicker estimation. Although the differences of cortical thickness estimation at the diverse spatial resolution varied with one another, almost all led to roughly one-sixth to one-fifth significant reduction across the entire brain at the HR, independent to the pipelines we applied, which emphasizes on generally coherent improved accuracy in a data-independent manner and endeavors to cost-efficiency with quantitative opportunities.

Flower color polymorphism of a wild Iris on the Qinghai-Tibet plateau.

BACKGROUND: Flower color plays a crucial role in attracting pollinators and facilitating environmental adaptation. Investigating the causes of flower color polymorphism and understanding their potential effects on both ecology and genetics can enhance our understanding of flower color polymorphism in wild plant. RESULTS: In this study, we examined the differences of potential male and female fitness between purple- and yellow- flower individuals in Iris potaninii on the Qinghai-Tibet Plateau, and screened key genes and positively selective genes involved in flower color change. Our results showed that yellow flower exhibited a higher pollen-to-ovule ratio. Yellow flowers were derived from purple flowers due to the loss of anthocyanins, and F3H could be an essential gene affecting flower color variation though expression regulation and sequence polymorphism in this species. Furthermore, our findings suggest that genes positively selected in yellow-flowered I. potaninii might be involved in nucleotide excision repair and plant-pathogen interactions. CONCLUSIONS: These results suggest that F3H induces the flower color variation of Iris potaninii, and the subsequent ecological and additive positive selection on yellow flowers may further enhance plant adaptations to alpine environments.

Impact of Sulfoxaflor Exposure on Bacterial Community and Developmental Performance of the Predatory Ladybeetle Propylea japonica.

Insects maintain a vast number of symbiotic bacteria, and these symbionts play key roles in the hosts' life processes. Propylea japonica (Coleoptera: Coccinellidae) is an abundant and widespread ladybeetle in agricultural fields in Asia. Both larvae and adults of P. japonica are likely to be exposed to insecticide residue in the field during their predatory activity. Sulfoxaflor is a highly powerful insecticide that has strong efficacy in controlling sap-sucking pests. To date, there have been several studies on the acute and long-term toxicity of sulfoxaflor to insects, but few studies have reported the impact of sulfoxaflor on the predators' micro-ecosystems. This study was to determine the impact of sulfoxaflor on the symbiotic bacteria and developmental performance of P. japonica. In the present study, two concentrations (1 mg/L and 5 mg/L) and two exposure periods (1 day and 5 days) were set for P. japonica under sulfoxaflor exposure. The survival rate, developmental duration, pupation rate, emergence rate, and body weight of P. japonica were examined. Moreover, the bacterial community of P. japonica was investigated by high-throughput 16S ribosomal RNA gene sequencing. Our results indicated that bacterial community of P. japonica was mainly composed of Staphylococcus, Pantoea, Acinetobacter, Rhodococcus, and Ralstonia at the genus level. The bacterial community of P. japonica in 1 mg/L and 5 mg/L sulfoxaflor groups was significantly altered on day 1, compared with that in control group. The results also showed that the larval duration was significantly prolonged but the pupal duration was significantly shortened in both sulfoxaflor groups. Meanwhile, the pupation and emergence rate was not significantly changed, but the body weights of adults were significantly decreased in both sulfoxaflor groups. Our study will provide a new perspective for evaluating the safety of pesticides to beneficial arthropods.

Xinmai 'an extract enhances the efficacy of sildenafil in the treatment of pulmonary arterial hypertension via inhibiting MAPK signalling pathway.

CONTEXT: Xinmai 'an tablet has been used to improve myocardial blood supply. Recently, some compounds from its formula have shown that they can treat pulmonary arterial hypertension (PAH). OBJECTIVE: This study investigates the effects of Xinmai 'an extract (XMA) on PAH and further tests the co-therapeutic enhancement with sildenafil (SIL). MATERIALS AND METHODS: Pulmonary artery smooth muscle cells were subjected to stimulation with SIL (12.5 µM) and XMA (250 µg/mL) for 48 h. Sprague-Dawley rats were randomly grouped into eight groups (n = 8 per group): (I) control group received saline; (II) MCT group received MCT (60 mg/kg); (III) SIL-Low group received MCT + SIL at 10 mg/kg/day; (IV) SIL-high group received MCT + SIL at 30 mg/kg/day; (V) XMA-High group received MCT + XMA at 251.6 mg/kg/day; (VI) SIL (Low)+XMA (Low) group received SIL (10 mg/kg) + XMA at 62.9 mg/kg/day; (VII) SIL (Low)+XMA (Medium) group received SIL (10 mg/kg) + XMA at 125.8 mg/kg/day; (VIII) SIL (Low)+XMA (High) group received SIL (10 mg/kg) + XMA at 251.6 mg/kg/day. Both XMA and SIL were given by gavage and were maintained daily for 2 weeks. RESULTS: XMA could improve SIL's efficacy in the treatment of PAH by decreasing cell viability more effectively at non-cytotoxic concentrations (250 µg/mL) and reducing Right Ventricular Systolic Pressure (RVSP) in PAH rat. Potential mechanisms might at least in part be through activating the MAPK signalling pathway. DISCUSSION AND CONCLUSIONS: The combination of XMA and SIL can improve the efficacy of pulmonary hypertension and reduce the dosage of SIL.

High-lipid prey reduce juvenile survivorship and delay egg laying in a small linyphiid spider Hylyphantes graminicola.

Prey proteins and lipids greatly impact predator life-history traits. However, life-history plasticity offers predators the opportunity to tune the life-history traits in response to the limited macronutrients to allocate among traits. A fast-growing predator species with a strict maturation time may be more likely to consume nutritionally imbalanced prey. Here, we tested this hypothesis by examining the effect of the protein-to-lipid ratio in prey on a small sheet web-building spider, Hylyphantes graminicola, with a short life span, using adult Drosophila melanogaster as the prey. By manipulating the macronutrient content of the prey to generate three prey types with different protein-to-lipid ratios (i.e. high, intermediate and low), we demonstrated that the majority of the spiders that consumed only these flies could reach full maturity. However, juvenile spiders that consumed high-lipid (low protein-to-lipid ratio) flies had a higher rate of mortality than those consuming medium-protein and high-protein flies. The prey protein-to-lipid ratio had no significant effects on the developmental duration and size at maturity. Although the prey protein-to-lipid ratio had no significant influence on mating behaviour and female fecundity, females reared on high-lipid flies exhibited a significant delay in oviposition compared with those reared on high-protein flies. We conclude that high-lipid prey has negative effects on the survival and reproductive function of H. graminicola Our study thus provides clear evidence that low plasticity with fast development to a certain size means a high nutritional requirement for protein at a cost of lower survival and prolonged time to egg laying when prey have low protein-to-lipid content in H. graminicola.

[Preparation of evodiamine-glycyrrhizic acid micelles with glycyrrhizic acid as carrier and their anti-hepatic fibrosis activity].

This study aimed to prepare evodiamine-glycyrrhizic acid(EVO-GL) micelles to enhance the anti-hepatic fibrosis activity of evodiamine. Firstly, EVO-GL micelles were prepared with use of thin film dispersion method. With particle size, encapsulation efficiency, loading capacity of micelles and the solubility of evodiamine as the indexes, the effect of different factors on micelles was observed to screen the optimal preparation methods and process. Then the pharmaceutical properties and the therapeutic effects of EVO-GL micelles prepared by optimal process were evaluated on CCl_4-induced hepatic fibrosis. The results showed that the micelles prepared by the thin film dispersion method had an even size, with an average particle size of(130.80±12.40)nm, Zeta potential of(-41.61±3.12) mV, encapsulation efficiency of 91.23%±1.22%, drug loading of 8.42%±0.71%, high storage stability at 4 ℃ in 3 months, and slow in vitro release. Experimental results in the treatment of CCl_4-induced hepatic fibrosis in rats showed that EVO-GL micelles had a synergistic anti-hepatic fibrosis effect, which significantly reduced the liver function index of hepatic fibrosis rats. In conclusion, the EVO-GL micelles prepared with glycyrrhizic acid as a carrier would have a potential application prospect for the treatment of hepatic fibrosis.

MYB-CC transcription factor, TaMYBsm3, cloned from wheat is involved in drought tolerance.

BACKGROUND: MYB-CC transcription factors (TFs) genes have been demonstrated to be involved in the response to inorganic phosphate (Pi) starvation and regulate some Pi-starvation-inducible genes. However, their role in drought stress has not been investigated in bread wheat. In this study, the TaMYBsm3 genes, including TaMYBsm3-A, TaMYBsm3-B, and TaMYBsm3-D, encoding MYB-CC TF proteins in bread wheat, were isolated to investigate the possible molecular mechanisms related to drought-tolerance in plants. RESULTS: TaMYBsm3-A, TaMYBsm3-B, and TaMYBsm3-D were mapped on chromosomes 6A, 6B, and 6D in wheat, respectively. TaMYBsm3 genes belonged to MYB-CC TFs, containing a conserved MYB DNA-binding domain and a conserved coiled-coil domain. TaMYBsm3-D was localized in the nucleus, and the N-terminal region was a transcriptional activation domain. TaMYBsm3 genes were ubiquitously expressed in different tissues of wheat, and especially highly expressed in the stamen and pistil. Under drought stress, transgenic plants exhibited milder wilting symptoms, higher germination rates, higher proline content, and lower MDA content comparing with the wild type plants. P5CS1, DREB2A, and RD29A had significantly higher expression in transgenic plants than in wild type plants. CONCLUSION: TaMYBsm3-A, TaMYBsm3-B, and TaMYBsm3-D were associated with enhanced drought tolerance in bread wheat. Overexpression of TaMYBsm3-D increases the drought tolerance of transgenic Arabidopsis through up-regulating P5CS1, DREB2A, and RD29A.

Nitrogen inaccessibility protects spider silk from bacterial growth.

Spider silks are protein-based fibers that are incorporated into webs with the unique combination of high mechanical toughness and resistance to microbial degradation. While spiders are undoubtedly exposed to saprophytic microorganisms in their native habitats, such as the forest understory and bush, their silks have rarely been observed to decompose in either field or laboratory studies. We performed cross-streaking assays using silk from three spider species and four bacterial strains and found no inhibition zones, indicating the absence of antibacterial properties. We also cultured all bacteria directly upon silk in Luria-Bertani (LB) broth (full nutrients), phosphate-buffered saline (PBS; no nutrients) and nitrogen-free glucose broth (NFG; full nutrients, no nitrogen), and found that bacteria grew readily on silk in LB broth but not in PBS or NFG buffer. Our results indicate that spider silk's resistance to bacterial degradation is likely due to bacteriostatic rather than antibacterial mechanisms when nitrogen is inaccessible.

Nutrient intake determines post-maturity molting in the golden orb-web spider Nephila pilipes (Araneae: Araneidae).

While molting occurs in the development of many animals, especially arthropods, post-maturity molting (PMM, organisms continue to molt after sexual maturity) has received little attention. The mechanism of molting has been studied intensively; however, the mechanism of PMM remains unknown although it is suggested to be crucial for the development of body size. In this study, we investigated factors that potentially induce PMM in the golden orb-web spider Nephila pilipes, which has the greatest degree of sexual dimorphism among terrestrial animals. We manipulated the mating history and the nutrient consumption of the females to examine whether they affect PMM. The results showed that female spiders under low nutrition were more likely to molt as adults, and mating had no significant influence on the occurrence of PMM. Moreover, spiders that underwent PMM lived longer than those that did not and their body sizes were significantly increased. Therefore, we concluded that nutritional condition rather than mating history affect PMM.

Integration of single-layer skin hollow fibers and scaffolds develops a three-dimensional hybrid bioreactor for bioartificial livers.

Bioartificial liver support systems are expected to be an effective therapy as a "bridge" for liver transplantation or reversible acute liver disease. A major roadblock in the application of bioartificial livers is the need for a bioreactor that fully meets the requirements of hepatocyte culture, mass transfer and immunobarriers. In this study, we developed a three-dimensional hybrid bioreactor (3DHB) on a base of single-layer skin polyethersulfone hollow fibers by integrating with polyurethane scaffolds. The mass transfer of bilirubin and albumin from the intracapillary space to the extracapillary space of the hollow fibers was not significantly different between 3DHBs and hollow fiber bioreactors (HFBs). Cell viability staining showed that high-density hepatocytes were uniformly found in different regions of the 3DHB after 7 days of culture. Liver-specific functions of human mature hepatocytes cultured in the 3DHB, such as albumin secretion, urea production, ammonia removal rate and cytochrome P450 activity, were maintained stably and were significantly higher compared with the HFB. These results indicated that the 3DHB has good mass transfer and improves cell distribution and liver-specific functions. Meanwhile, the ammonia and unconjugated bilirubin concentrations in plasma from patients with liver failure were significantly decreased during 6 h of circulation by hepatocytes cultured in the 3DHB. Most hepatocytes in the 3DHB were viable after 6 h exposure to the patient plasma. We further demonstrated that bioartificial liver systems with 3DHB can remove toxins from and endure the deleterious effects of the patient plasma. Therefore, the 3DHB has the potential to accomplish different actions for the clinical application of bioartificial livers.

Three-dimensional culture in a microgravity bioreactor improves the engraftment efficiency of hepatic tissue constructs in mice.

Tissue-engineered liver using primary hepatocytes has been considered a valuable new therapeutic modality as an alternative to whole organ liver transplantation for different liver diseases. The development of clinically feasible liver tissue engineering approaches, however, has been hampered by the poor engraftment efficiency of hepatocytes. We developed a three-dimensional (3D) culture system using a microgravity bioreactor (MB), biodegradable scaffolds and growth-factor-reduced Matrigel to construct a tissue-engineered liver for transplantation into the peritoneal cavity of non-obese diabetic severe combined immunodeficient mice. The number of viable cells in the hepatic tissue constructs was stably maintained in the 3D MB culture system. Hematoxylin-eosin staining and zonula occludens-1 expression revealed that neonatal mouse liver cells were reorganized to form tissue-like structures during MB culture. Significantly upregulated hepatic functions (albumin secretion, urea production and cytochrome P450 activity) were observed in the MB culture group. Post-transplantation analysis indicated that the engraftment efficiency of the hepatic tissue constructs prepared in MB cultures was higher than that of those prepared in the static cultures. Higher level of hepatic function in the implants was confirmed by the expression of albumin. These findings suggest that 3D MB culture systems may offer an improved method for creating tissue-engineered liver because of the higher engraftment efficiency and the reduction of the initial cell function loss.

Mucus provisioning as milk in an amphibian.

Two examples of vertebrates that feed young with mucus. Left: A female cichlid fish Symphysodon aequifasciatus; Right: A female caecilian Siphonops annulatus.

RNA interference against the putative insulin receptor substrate gene IRS1 affects growth and development in the pest natural enemy Pardosa pseudoannulata.

BACKGROUND: Insulin signalling pathways play crucial roles in regulating growth and development in insects, but their effects on the growth and development of Arachnids, such as spiders, have rarely been studied. As a valuable pest natural enemy in agricultural fields, the molecular mechanisms of insulin signalling pathway-mediated growth and development of the wolf spider, Pardosa pseudoannulata, are of particular interest. RESULTS: In this study, we identified and characterized six insulin signalling pathway genes - InR, InR2, IRS1, PI3K1, PI3K2, and PDK - in Pardosa pseudoannulata. Real-time quantitative polymerase chain reaction results were used to analyse the relative expression levels of the six genes in different developmental instars and tissues, and in response to starvation treatment. In addition, the function of the insulin receptor substrate (IRS1) gene was investigated using RNA interference technology, which found that IRS1 significantly influenced nutrient content, developmental duration, body weight, and gonad development. CONCLUSION: This study revealed the roles of six key insulin signalling pathway genes in Pardosa pseudoannulata, and in particular the importance of the IRS1 gene in regulating growth and development in the spider. The results lay the foundation for further research on the internal regulation mechanisms of growth and development in Araneae species, and also provide a reference for the artificial breeding of spiders. © 2023 Society of Chemical Industry.

Antipredator defences in motion: animals reduce predation risks by concealing or misleading motion signals.

Motion is a crucial part of the natural world, yet our understanding of how animals avoid predation whilst moving remains rather limited. Although several theories have been proposed for how antipredator defence may be facilitated during motion, there is often a lack of supporting empirical evidence, or conflicting findings. Furthermore, many studies have shown that motion often 'breaks' camouflage, as sudden movement can be detected even before an individual is recognised. Whilst some static camouflage strategies may conceal moving animals to a certain extent, more emphasis should be given to other modes of camouflage and related defences in the context of motion (e.g. flicker fusion camouflage, active motion camouflage, motion dazzle, and protean motion). Furthermore, when motion is involved, defence strategies are not necessarily limited to concealment. An animal can also rely on motion to mislead predators with regards to its trajectory, location, size, colour pattern, or even identity. In this review, we discuss the various underlying antipredator strategies and the mechanisms through which they may be linked to motion, conceptualising existing empirical and theoretical studies from two perspectives - concealing and misleading effects. We also highlight gaps in our understanding of these antipredator strategies, and suggest possible methodologies for experimental designs/test subjects (i.e. prey and/or predators) and future research directions.

Nature's disguise: Empirical demonstration of dead-leaf masquerade in Kallima butterflies.

Animals deploy diverse color-based defenses against predators, including crypsis, mimicry, aposematism, and masquerade. While crypsis, mimicry, aposematism have been extensively studied, the strategy of masquerade-where organisms imitate inedible or inanimate objects such as leaves, twigs, stones, and bird droppings-remains comparatively underexplored, particularly in adult butterflies. The Indian oakleaf butterfly ( Kallima inachus) exemplifies this phenomenon, with its wings resembling dead leaves, providing a classic example of natural selection. Although it has long been postulated that these butterflies evade predation by being misidentified as dead leaves, direct experimental evidence is lacking. In the current study, using domestic chicks as predators, we manipulated their prior experience with dead leaves (model objects) while maintaining constant exposure to butterflies to test whether dead-leaf masquerade provides a protective advantage by preventing recognition. Results showed a marked delay in the initiation of attacks by chicks familiar with dead leaves compared to those with no prior exposure or those exposed to visually altered leaves. Chicks with prior dead-leaf experience required a similar amount of time to attack the butterflies as they did to attack dead leaves. These findings provide the first empirical demonstration of dead-leaf masquerade in Kallima butterflies, shedding light on its evolutionary significance. Our study highlights the effectiveness of masquerade in inducing the misclassification of butterflies as inanimate objects, showcasing the precise mimicry achieved by these organisms when viewed in isolation from the model objects. This study advances our understanding of the evolution of masquerade and its role as a potent antipredator strategy in nature.

Spiders manipulate and exploit bioluminescent signals of fireflies.

Predators often search for prey while moving through the environment, but there are important exceptions, including the way sedentary predators sometimes rely on signals for drawing prey to within striking distance1,2. Some spiders, for instance, leave the remnants of previously-captured prey in their webs where they function as static lures that effectively attract a diverse array of additional prey3456. However, important questions remain concerning how specific the targeted prey may be and how dynamic, instead of static, signalling might be. With these questions as our rationale, we initiated research on Araneus ventricosus (L. Koch, 1878), an orb-weaving spider, as the predator and the firefly Abscondita terminalis males as the prey (Figure 1A-C). Using two lanterns situated on their abdomen (Figure 1D,F), A. terminalis males make female-attracting multi-pulse flash trains (Figure 1J), whereas sedentary females attract males by making single-pulse signals (Figure 1C,K) with a single lantern (Figure 1E,G). Drawing from extensive field observations, we propose that A. ventricosus practices deceptive interspecific communication by first ensnaring firefly males in its web and then predisposing the entrapped male fireflies to broadcast bioluminescent signals that deviate from female-attracting signals typically made by A. terminalis males and instead mimic the male-attracting signals typically made by females. The outcome is that the entrapped male fireflies broadcast false signals that lure more male fireflies into the web.

Phosphination of amino-modified mesoporous silica for the selective separation of strontium.

Radioactive strontium (90Sr) is considered as one of the most dangerous radionuclides due to its high biochemical toxicity. For the efficient and selective separation of Sr from acidic environments, a novel functional adsorbent CEPA@SBA-15-APTES was prepared in this work through the phosphorylation of amino-modified mesoporous silica with organic content of approximately 20 wt%. CEPA@SBA-15-APTES was characterized by TEM, SEM, EDS, TG-DSC, BET, FTIR, and XPS techniques, revealing its characteristics of an ordered hexagonal lattice-like structure and rich functional groups. The experimental results demonstrated that the adsorbent exhibited good adsorption capacity for Sr over a wide acidity range (i.e., from 10-10 M to 4 M HNO3). The adsorption equilibriums of Sr by CEPA@SBA-15-APTES in 10-6 M and 3 M HNO3 solutions were reached within 30 and 5 min, respectively, and the adsorption capacities at 318 K were 112.6 and 71.8 mg/g, respectively. Furthermore, by combining the experimental and characterization results, we found that the adsorption mechanism consisted of ion exchange between Sr(II) and H+ (in P-OH) in the 10-6 M HNO3 solution and coordination between the Sr(II) and oxygen-containing (CO and P = O) functional groups in the 3 M HNO3 solution.

Males armed with big weapons win fights at limited cost in ant-mimicking jumping spiders.

A core assumption of sexual selection theory is that sexually selected weapons, specialized morphological structures used directly in male contests, can improve an individual's reproductive success but only if the bearer can overcome associated costs, the negative effects on the bearer's fitness components. However, recent studies have shown that producing and wielding exaggerated weapons may not necessarily be costly. Rather, some traits can be selected for supporting, or compensating for, the expense of producing and wielding such exaggerated weapons. In the ant-mimicking jumping spider Myrmarachne gisti, exaggerated chelicerae are borne only by adult males and not females, showing sexual dimorphism and steep positive allometry with body size. Here, we determine the potential benefits of bearing exaggerated chelicerae during male contests and explore the potential for costs in terms of prey-capture efficiency and compensation between chelicera size and neighboring trait size. While males with longer chelicerae won most of their male-male contests, we found no significant differences in prey-capture efficiency between males and females regardless of whether prey was winged or flightless. Males' elongated chelicerae thus do not impede their efficiency at capturing prey. Furthermore, we found that the sizes of all neighboring traits are positively correlated with chelicera size, suggesting that these traits may be under correlational selection. Taken together, our findings suggest that M. gisti males armed with the exaggerated chelicerae that function as weapons win more fights at limited cost for performance in prey capture and compensate for neighboring structures.