Complex effects of testosterone level on ectoparasite load in a ground squirrel: an experimental test for the immunocompetence handicap hypothesis.

BACKGROUND: The immunocompetence handicap hypothesis suggests that males with a higher testosterone level should be better at developing male secondary traits, but at a cost of suppressed immune performance. As a result, we should expect that males with an increased testosterone level also possess a higher parasite load. However, previous empirical studies aimed to test this prediction have generated mixed results. Meanwhile, the effect of testosterone level on parasite load in female hosts remains poorly known. METHODS: In this study, we tested this prediction by manipulating testosterone level in Daurian ground squirrels (Spermophilus dauricus), a medium-sized rodent widely distributed in northeast Asia. S. dauricus is an important host of ticks and fleas and often viewed as a considerable reservoir of plague. Live-trapped S. dauricus were injected with either tea oil (control group) or testosterone (treatment group) and then released. A total of 10 days later, the rodents were recaptured and checked for ectoparasites. Fecal samples were also collected to measure testosterone level of each individual. RESULTS: We found that testosterone manipulation and sex of hosts interacted to affect tick load. At the end of the experiment, male squirrels subjected to testosterone implantation had an averagely higher tick load than males from the control group. However, this pattern was not found in females. Moreover, testosterone manipulation did not significantly affect flea load in S. dauricus. CONCLUSIONS: Our results only lent limited support for the immunocompetence handicap hypothesis, suggesting that the role of testosterone on regulating parasite load is relatively complex, and may largely depend on parasite type and gender of hosts.

The structural and functional properties of hemp protein isolate-epigallocatechin-3-gallate biopolymer covalent complex during heating.

BACKGROUND: It is well known that hemp proteins have the disadvantages of poor solubility and poor emulsification. To improve these shortcomings, an alkali covalent cross-linking method was used to prepare hemp protein isolate-epigallocatechin-3-gallate biopolymer (HPI-EGCG) and the effects of different heat treatment conditions on the structure and emulsifying properties of the HPI-EGCG covalent complex were studied. RESULTS: The secondary and tertiary structures, solubility, and emulsification ability of the HPI-EGCG complexes were evaluated using particle size, zeta potential, circular dichroism (CD), and fluorescence spectroscopy indices. The results showed that the absolute value of zeta potential of HPI-EGCG covalent complex was the largest, 18.6 mV, and the maximum binding amount of HPI to EGCG was 29.18 µmol g-1 . Under heat treatment at 25-35 °C, the α-helix content was reduced from 1.87% to 0%, and the ß-helix content was reduced from 82.79% to 0% after the covalent binding of HPI and EGCG. The solubility and emulsification properties of the HPI-EGCG covalent complexes were improved significantly, and the emulsification activity index (EAI) and emulsion stability index (ESI) were increased by 2.77-fold and 1.21-fold, respectively. CONCLUSION: A new HPI-EGCG covalent complex was developed in this study to provide a theoretical basis for the application of HPI-EGCG in food industry. © 2023 Society of Chemical Industry.

Metabolic regulation reduces the oxidative damage of arid lizards in response to moderate heat events.

Climate warming poses a significant threat to species worldwide, particularly those inhabiting arid and semi-arid regions where extreme temperatures are increasingly prevalent. However, empirical studies investigating how moderate heat events affect the physiological processes of arid and semi-arid animals are largely scarce. To address this knowledge gap, we used an arid and semi-arid lizard species (Phrynocephalus przewalskii) as a study system. We manipulated thermal environments to simulate moderate heat events (43.5 ± 0.3°C during the heating period) for lizards and examined physiological and biochemical traits related to survival, metabolism, locomotion, oxidative stress, and telomere length. We found that the body condition and survival of the lizards were not significantly affected by moderate heat events, despite an increase in body temperature and a decrease in locomotion at high test temperatures were detected. Mechanistically, we found that the lizards exhibited down-regulated metabolic rates and enhanced activities of antioxidative enzymes, resulting in reduced oxidative damage and stable telomere length under moderate heat events. Based on these findings, which indicated a beneficial regulation of fitness by physiological and biochemical processes, we inferred that moderate heat events did not have a detrimental effect on the toad-headed agama, P. przewalskii. Overall, our research contributes to understanding the impacts of moderate heat events on arid and semi-arid species and highlights the adaptive responses and resilience exhibited by the toad-headed agama in the face of climate warming.

Human SAMD9 is a poxvirus-activatable anticodon nuclease inhibiting codon-specific protein synthesis.

As a defense strategy against viruses or competitors, some microbes use anticodon nucleases (ACNases) to deplete essential tRNAs, effectively halting global protein synthesis. However, this mechanism has not been observed in multicellular eukaryotes. Here, we report that human SAMD9 is an ACNase that specifically cleaves phenylalanine tRNA (tRNAPhe), resulting in codon-specific ribosomal pausing and stress signaling. While SAMD9 ACNase activity is normally latent in cells, it can be activated by poxvirus infection or rendered constitutively active by SAMD9 mutations associated with various human disorders, revealing tRNAPhe depletion as an antiviral mechanism and a pathogenic condition in SAMD9 disorders. We identified the N-terminal effector domain of SAMD9 as the ACNase, with substrate specificity primarily determined by a eukaryotic tRNAPhe-specific 2'-O-methylation at the wobble position, making virtually all eukaryotic tRNAPhe susceptible to SAMD9 cleavage. Notably, the structure and substrate specificity of SAMD9 ACNase differ from known microbial ACNases, suggesting convergent evolution of a common immune defense strategy targeting tRNAs.

Telomere length, oxidative stress and their links with growth and survival in a lizard facing climate warming.

Higher temperatures enhance ectothermic metabolism and development, which can reduce individual health and life expectancy, and therefore increase their vulnerability to climate warming. However, the mechanistic causes and consequences of such a temperature-driven impact remain unclear. Our study aimed to address two questions: (1) does climate warming alter early-life growth and physiology, and, if so, what are the associated carry-over effects in terms of reduced survival, increased oxidative stress and telomere shortening? (2) can oxidative stress and telomere dynamics at early life stages predict the effect of climate warming on individual survival? To answer these questions, we conducted a longitudinal experiment under semi-natural conditions where we exposed multiocellated racerunner (Eremias multiocellata) to warming conditions from juvenile to adult stages. We found that exposure to climate warming enhanced growth rates, induced oxidative stress, and shortened telomere length of juvenile lizards. Warming conditions did not induce carry-over effects in terms of altered growth rate or physiology but resulted in increased mortality risk in the later life. Intriguingly, telomere shortening in young individuals was associated with mortality risk later in life. This study improves our mechanistic understanding of how global warming impacts on ectotherms' life-history traits, which encourages the inclusion of physiological information in assessing species vulnerability to climate change.

The Nucleocapsid Proteins of SARS-CoV-2 and Its Close Relative Bat Coronavirus RaTG13 Are Capable of Inhibiting PKR- and RNase L-Mediated Antiviral Pathways.

Coronaviruses (CoVs), including severe acute respiratory syndrome CoV (SARS-CoV), Middle East respiratory syndrome CoV (MERS-CoV), and SARS-CoV-2, produce double-stranded RNA (dsRNA) that activates antiviral pathways such as PKR and OAS/RNase L. To successfully replicate in hosts, viruses must evade such antiviral pathways. Currently, the mechanism of how SARS-CoV-2 antagonizes dsRNA-activated antiviral pathways is unknown. In this study, we demonstrate that the SARS-CoV-2 nucleocapsid (N) protein, the most abundant viral structural protein, is capable of binding to dsRNA and phosphorylated PKR, inhibiting both the PKR and OAS/RNase L pathways. The N protein of the bat coronavirus (bat-CoV) RaTG13, the closest relative of SARS-CoV-2, has a similar ability to inhibit the human PKR and RNase L antiviral pathways. Via mutagenic analysis, we found that the C-terminal domain (CTD) of the N protein is sufficient for binding dsRNA and inhibiting RNase L activity. Interestingly, while the CTD is also sufficient for binding phosphorylated PKR, the inhibition of PKR antiviral activity requires not only the CTD but also the central linker region (LKR). Thus, our findings demonstrate that the SARS-CoV-2 N protein is capable of antagonizing the two critical antiviral pathways activated by viral dsRNA and that its inhibition of PKR activities requires more than dsRNA binding mediated by the CTD. IMPORTANCE The high transmissibility of SARS-CoV-2 is an important viral factor defining the coronavirus disease 2019 (COVID-19) pandemic. To transmit efficiently, SARS-CoV-2 must be capable of disarming the innate immune response of its host efficiently. Here, we describe that the nucleocapsid protein of SARS-CoV-2 is capable of inhibiting two critical innate antiviral pathways, PKR and OAS/RNase L. Moreover, the counterpart of the closest animal coronavirus relative of SARS-CoV-2, bat-CoV RaTG13, can also inhibit human PKR and OAS/RNase L antiviral activities. Thus, the importance of our discovery for understanding the COVID-19 pandemic is 2-fold. First, the ability of SARS-CoV-2 N to inhibit innate antiviral activity is likely a factor contributing to the transmissibility and pathogenicity of the virus. Second, the bat relative of SARS-CoV-2 has the capacity to inhibit human innate immunity, which thus likely contributed to the establishment of infection in humans. The findings described in this study are valuable for developing novel antivirals and vaccines.

Combined effects of light pollution and vegetation height on behavior and body weight in a nocturnal rodent.

At a global scale, organisms are under threat due to various kinds of environmental changes, such as artificial light at night (ALAN), noise, climatic change and vegetation destruction. Usually, these changes co-vary in time and space and may take effect simultaneously. Although impacts of ALAN on biological processes have been well documented, our knowledge on the combined effects of ALAN and other environmental changes on animals remains limited. In this study, we conducted field experiments in semi-natural enclosures to explore the combined effects of ALAN and vegetation height on foraging behavior, vigilance, activity patterns and body weight in dwarf striped hamsters (Cricetulus barabensis), a nocturnal rodent widely distributed in East Asia. We find that ALAN and vegetation height affected different aspects of behavior. ALAN negatively affected search speed and positively affected handling speed, while vegetation height negatively affected giving-up density and positively affected body weight. ALAN and vegetation height also additively shaped total time spent in a food patch. No significant interactive effect of ALAN and vegetation height was detected. C. barabensis exposed to ALAN and short vegetation suffered a significant loss in body weight, and possessed a much narrower temporal niche (i.e. initiated activity later but became inactive earlier) than those under other combinations of treatments. The observed behavioral responses to ALAN and changes in vegetation height may bring fitness consequences, as well as further changes in structure and functioning of local ecosystems.

Ecological correlates of ectoparasite load in a rodent: Complex roles of seasonality.

Understanding the mechanisms driving parasite distributions is not only important for understanding ecosystem functioning, but also crucial for disease control. Previous studies have documented the important roles of host sex, host body size, host behavioral trait (such as boldness and trappability), and seasonality in shaping parasite load. However, few studies have simultaneously assessed the roles of these factors, as well as their interactions. In spring and summer of 2021, we conducted live trapping in Hohhot, China, to collect ectoparasites on Daurian ground squirrel (Spermophilus dauricus), a small rodent widely distributed in East Asian grassland. We then used generalized linear models to explore the effects of several biological factors (sex, body weight, trappability, and reproductive status) and seasonality on the abundance of ticks and fleas in S. dauricus. Significant but inconsistent seasonal effects were observed: tick load was significantly greater in summer than in spring, while flea load was greater in spring than in summer. Seasons also significantly interacted with host trappability and body weight to affect tick abundance. Our results highlight the importance of considering seasonal changes in parasitism, as well as interactions between season and host biological traits in shaping parasite distributions.

Comparative proteomic analysis on chloroplast proteins provides new insights into the effects of low temperature in sugar beet.

BACKGROUND: Low temperature, which is one of the main environmental factors that limits geographical distribution and sucrose yield, is a common abiotic stress during the growth and development of sugar beet. As a regulatory hub of plant response to abiotic stress, activity in the chloroplasts is related to many molecular and physiological processes, particularly in response to low temperature stress. RESULTS: The contents of chlorophyll (Chl) and malondialdehyde (MDA), relative electrical conductivity (REL), and superoxide dismutase (SOD) activity were measured. The results showed that sugar beet could manage low temperature stress by regulating the levels of Chl, REL and MDA, and the activity of SOD. The physiological responses indicated that sugar beets respond positively to low temperature treatments and are not significantly damaged. Moreover, to determine the precise time to response low temperature in sugar beet, well-known abiotic stresses-responsive transcript factor family, namely DEHYDRATION RESPONSIVE ELEMENT BINDING PROTEIN (DREB), was selected as the marker gene. The results of phylogenetic analyses showed that BvDREBA1 and BvDREBA4 were in the same branch as the cold- and drought-responsive AtDREB gene. In addition, the expression of BvDREBs reached its maximum level at 24 h after low temperature by RNA-Seq and qRT-PCR analysis. Furthermore, the changes in chloroplast proteome after low temperature at 24 h were detected using a label-free technique. A total of 416 differentially expressed proteins were identified. GO enrichment analysis showed that 16 GO terms were significantly enriched, particularly chloroplast stroma, chloroplast envelope, and chloroplast thylakoid membrane. It is notable that the transport of photosynthetic proteins (BvLTD and BvTOC100), the formation of starch granules (BvPU1, BvISA3, and BvGWD3) and the scavenging of reactive oxygen species (BvCu/Zn-SOD, BvCAT, BvPrx, and BvTrx) were the pathways used by sugar beets to respond to low temperatures at an early stage. CONCLUSIONS: These results provide a preliminarily analysis of how chloroplasts of sugar beet respond to low temperature stress at the translational level and provide a theoretical basis for breeding low temperature resistant varieties of sugar beet.

Meta-Analysis of Tai Chi Chuan in Treating Lumbar Spondylosis and Back Pain.

BACKGROUND: The effectiveness of Tai Chi Chuan in treating various ailments has been well reported; however, its effect on back pain and lumbar spondylosis remains unclear. METHODS: We performed this meta-analysis under the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), and the research-associated search was performed over the provided databases: Embase, Cochrane Library, Web of Science, PubMed, Scopus, and CINAHL in the period of 2008 to 2016, to recognize the related studies. We used the Physiotherapy Evidence Database (PEDro) scale to measure the standard of the involved randomized control trials (RCTs). The accumulated outcomes with parameters of weighted mean difference (WMD) and confidence level (CI) of 95% were evaluated to discover the influence of Tai Chi over pain as well as dysfunction among the patients suffering from pain depending on the outcome model. RESULTS: Seven eligible studies with a total of 296 participants were identified that met inclusion criteria for the systematic review; in the forest plot analysis, it was noted that for 95% CI, the standardized mean difference found to be -1.58 (-1.79, -1.38) with the heterogeneity of 87%, thereby favoring Tai Chi over the control group; a comparison was drawn for Tai Chi with routine therapy against the routine therapy alone, where 95% CI for -1.22 [-1.47, -0.97] is observed for I 2 = 0% for the overall effect Z = 9.42 (P < 0.00001); pain intensity of Tai Chi was compared with the control group, where 95% CI for -1.62 [-2.09, -1.14] was observed for Z = 6.69 (P < 0.00001). The forest plot subgroup analysis of Tai Chi was compared with the control group for an unchanged lifestyle, where 95% CI for -2.26 [-2.61, -1.91] was observed for Z = 12.76 (P < 0.00001). CONCLUSION: Our results indicate that Tai Chi individually or with additional treatment along with routine physical exercises might reduce the pain and functional disorders for the patients suffering from back pain.

Structure and function of an effector domain in antiviral factors and tumor suppressors SAMD9 and SAMD9L.

SAMD9 and SAMD9L (SAMD9/9L) are antiviral factors and tumor suppressors, playing a critical role in innate immune defense against poxviruses and the development of myeloid tumors. SAMD9/9L mutations with a gain-of-function (GoF) in inhibiting cell growth cause multisystem developmental disorders including many pediatric myelodysplastic syndromes. Predicted to be multidomain proteins with an architecture like that of the NOD-like receptors, SAMD9/9L molecular functions and domain structures are largely unknown. Here, we identified a SAMD9/9L effector domain that functions by binding to double-stranded nucleic acids (dsNA) and determined the crystal structure of the domain in complex with DNA. Aided with precise mutations that differentially perturb dsNA binding, we demonstrated that the antiviral and antiproliferative functions of the wild-type and GoF SAMD9/9L variants rely on dsNA binding by the effector domain. Furthermore, we showed that GoF variants inhibit global protein synthesis, reduce translation elongation, and induce proteotoxic stress response, which all require dsNA binding by the effector domain. The identification of the structure and function of a SAMD9/9L effector domain provides a therapeutic target for SAMD9/9L-associated human diseases.

Expedited Approach toward the Rational Design of Noncovalent SARS-CoV-2 Main Protease Inhibitors.

The main protease (Mpro) of SARS-CoV-2 is a validated antiviral drug target. Several Mpro inhibitors have been reported with potent enzymatic inhibition and cellular antiviral activity, including GC376, boceprevir, calpain inhibitors II, and XII, with each containing a reactive warhead that covalently modifies the catalytic Cys145. Coupling structure-based drug design with the one-pot Ugi four-component reaction, we discovered one of the most potent noncovalent inhibitors, 23R (Jun8-76-3A) that is structurally distinct from the canonical Mpro inhibitor GC376. Significantly, 23R is highly selective compared with covalent inhibitors such as GC376, especially toward host proteases. The cocrystal structure of SARS-CoV-2 Mpro with 23R revealed a previously unexplored binding site located in between the S2 and S4 pockets. Overall, this study discovered 23R, one of the most potent and selective noncovalent SARS-CoV-2 Mpro inhibitors reported to date, and a novel binding pocket in Mpro that can be explored for inhibitor design.

Influence of Mindfulness and Relaxation on Treatment of Essential Hypertension: Meta-Analysis.

Background: Some studies published previously have shown a strong correlation between hypertension and psychological nature including impulsion emotion or mindfulness and relaxation temperament, among which mindfulness and relaxation temperament might have a benign influence on blood pressure, ameliorating the hypertension. However, the conclusion was not confirmed. Objective: The meta-analysis was performed to investigate the influence of mindfulness and relaxation on essential hypertension interventions and confirm the effects. Methods: Systematic searches were conducted in common English and Chinese electronic databases (i.e., PubMed/MEDLINE, EMBASE, Web of Science, CINAHL, PsycINFO, Cochrane Library, and Chinese Biomedical Literature Database) from 1980 to 2020. A meta-analysis including 5 studies was performed using Rev Man 5.4.1 software to estimate the influence of mindfulness and relaxation on blood pressure, ameliorating the hypertension. Publication bias and heterogeneity of samples were tested using a funnel plot. Studies were analyzed using either a random-effect model or a fixed-effect model. Results: All the 5 studies investigated the influence of mindfulness and relaxation on diastolic and systolic blood pressure, with total 205 participants in the control group and 204 in the intervention group. The random-effects model (REM) was used to calculate the pooled effect for mindfulness and relaxation on diastolic blood pressure (I 2 = 0%, t 2 = 0.000, P=0.41). The random pooled effect size (MD) was 0.30 (95% CI = -0.81-1.42, P=0.59). REM was used to calculate the pooled effect for mindfulness and relaxation on systolic blood pressure (I 2 = 49%, t 2 = 3.05, P=0.10). The random pooled effect size (MD) was -1.05 (95% CI = -3.29-1.18, P=0.36). The results of this meta-analysis were influenced by publication bias to some degree. Conclusion: All the results showed less influence of mindfulness and relaxation might act on diastolic or systolic blood pressure, when mindfulness and relaxation are used to intervene in treating CVD and hypertension.

Discovery of Di- and Trihaloacetamides as Covalent SARS-CoV-2 Main Protease Inhibitors with High Target Specificity.

The main protease (Mpro) is a validated antiviral drug target of SARS-CoV-2. A number of Mpro inhibitors have now advanced to animal model study and human clinical trials. However, one issue yet to be addressed is the target selectivity over host proteases such as cathepsin L. In this study we describe the rational design of covalent SARS-CoV-2 Mpro inhibitors with novel cysteine reactive warheads including dichloroacetamide, dibromoacetamide, tribromoacetamide, 2-bromo-2,2-dichloroacetamide, and 2-chloro-2,2-dibromoacetamide. The promising lead candidates Jun9-62-2R (dichloroacetamide) and Jun9-88-6R (tribromoacetamide) had not only potent enzymatic inhibition and antiviral activity but also significantly improved target specificity over caplain and cathepsins. Compared to GC-376, these new compounds did not inhibit the host cysteine proteases including calpain I, cathepsin B, cathepsin K, cathepsin L, and caspase-3. To the best of our knowledge, they are among the most selective covalent Mpro inhibitors reported thus far. The cocrystal structures of SARS-CoV-2 Mpro with Jun9-62-2R and Jun9-57-3R reaffirmed our design hypothesis, showing that both compounds form a covalent adduct with the catalytic C145. Overall, these novel compounds represent valuable chemical probes for target validation and drug candidates for further development as SARS-CoV-2 antivirals.

Discovery of SARS-CoV-2 Papain-like Protease Inhibitors through a Combination of High-Throughput Screening and a FlipGFP-Based Reporter Assay.

The papain-like protease (PLpro) of SARS-CoV-2 is a validated antiviral drug target. Through a fluorescence resonance energy transfer-based high-throughput screening and subsequent lead optimization, we identified several PLpro inhibitors including Jun9-72-2 and Jun9-75-4 with improved enzymatic inhibition and antiviral activity compared to GRL0617, which was reported as a SARS-CoV PLpro inhibitor. Significantly, we developed a cell-based FlipGFP assay that can be applied to predict the cellular antiviral activity of PLpro inhibitors in the BSL-2 setting. X-ray crystal structure of PLpro in complex with GRL0617 showed that binding of GRL0617 to SARS-CoV-2 induced a conformational change in the BL2 loop to a more closed conformation. Molecular dynamics simulations showed that Jun9-72-2 and Jun9-75-4 engaged in more extensive interactions than GRL0617. Overall, the PLpro inhibitors identified in this study represent promising candidates for further development as SARS-CoV-2 antivirals, and the FlipGFP-PLpro assay is a suitable surrogate for screening PLpro inhibitors in the BSL-2 setting.

Rational Design of Hybrid SARS-CoV-2 Main Protease Inhibitors Guided by the Superimposed Cocrystal Structures with the Peptidomimetic Inhibitors GC-376, Telaprevir, and Boceprevir.

SARS-CoV-2 main protease (Mpro) is a cysteine protease that mediates the cleavage of viral polyproteins and is a validated antiviral drug target. Mpro is highly conserved among all seven human coronaviruses, with certain Mpro inhibitors having broad-spectrum antiviral activity. In this study, we designed two hybrid inhibitors UAWJ9-36-1 and UAWJ9-36-3 based on the superimposed X-ray crystal structures of SARS-CoV-2 Mpro with GC-376, telaprevir, and boceprevir. Both UAWJ9-36-1 and UAWJ9-36-3 showed potent binding and enzymatic inhibition against the Mpro's from SARS-CoV-2, SARS-CoV, MERS-CoV, HCoV-OC43, HCoV-NL63, HCoV-229E, and HCoV-HKU1. Cell-based Flip-GFP Mpro assay results show that UAWJ9-36-1 and UAWJ9-36-3 inhibited the intracellular protease activity of SARS-CoV-2 Mpro. In addition, UAWJ9-36-1 and UAWJ9-36-3 had potent antiviral activity against SARS-CoV-2, HCoV-OC43, HCoV-NL63, and HCoV-229E, with UAWJ9-36-3 being more potent than GC-376 in inhibiting SARS-CoV-2. Selectivity profiling revealed that UAWJ9-36-1 and UAWJ9-36-3 had an improved selectivity index over that of GC-376 against host cysteine proteases calpain I and cathepsin L, but not cathepsin K. The X-ray crystal structures of SARS-CoV-2 Mpro with UAWJ9-36-1 and UAWJ9-36-3 were both solved at 1.9 Å, which validated our design hypothesis. Overall, hybrid inhibitors UAWJ9-36-1 and UAWJ9-36-3 are promising candidates to be further developed as broad-spectrum coronavirus antivirals.

A reciprocal egg-swap experiment reveals sources of variation in developmental success among populations of a desert lizard.

Identifying intrinsic and extrinsic sources of variation in life history traits among populations has been well-studied at the post-embryonic stage but rarely at the embryonic stage. To reveal these sources of variation in the developmental success of embryos, we measured the physical characteristics of nest environments and conducted reciprocal egg-swap experiments in two populations of the toad-headed agamid lizard (Phrynocephalus przewalskii), isolated from each other by a mountain range. We determined the effects of population origin and nest environment on embryonic and offspring traits related to developmental success, including incubation period, hatching success, and offspring growth and survival. Females from the northern population constructed deeper nests that were colder and wetter than those from the southern population. Northern embryos had higher hatching success than the southern embryos when incubated at the northern nest environment, but not when they were incubated at the southern nest environment. The southern hatchlings grew faster than the northern hatchlings when incubated at the southern nest environment, but not after incubation at the northern nest environment. These phenomena likely reflect local adaptation of embryonic development to their nest environments among populations in lizards. In addition, the southern hatchlings had higher survivorship than the northern hatchlings regardless of nest environment, suggesting the southern population has evolved a superior phenotype at the hatchling stage to maximize its fitness.

Discovery of SARS-CoV-2 papain-like protease inhibitors through a combination of high-throughput screening and FlipGFP-based reporter assay.

The papain-like protease (PL pro ) of SARS-CoV-2 is a validated antiviral drug target. PL pro is involved in the cleavage of viral polyproteins and antagonizing host innate immune response through its deubiquitinating and deISG15ylating activities, rendering it a high profile antiviral drug target. Through a FRET-based high-throughput screening, several hits were identified as PL pro inhibitors with IC 50 values at the single-digit micromolar range. Subsequent lead optimization led to potent inhibitors with IC 50 values ranging from 0.56 to 0.90 µM. To help prioritize lead compounds for the cellular antiviral assay against SARS-CoV-2, we developed the cell-based FlipGFP assay that is suitable for quantifying the intracellular enzymatic inhibition potency of PL pro inhibitors in the BSL-2 setting. Two compounds selected from the FlipGFP-PL pro assay, Jun9-53-2 and Jun9-72-2, inhibited SARS-CoV-2 replication in Caco-2 hACE2 cells with EC 50 values of 8.89 and 8.32 µM, respectively, which were 3-fold more potent than GRL0617 (EC 50 = 25.1 µM). The X-ray crystal structures of PL pro in complex with GRL0617 showed that binding of GRL0617 to SARS-CoV-2 induced a conformational change in the BL2 loop to the more closed conformation. Overall, the PL pro inhibitors identified in this study represent promising starting points for further development as SARS-CoV-2 antivirals, and FlipGFP-PL pro assay might be a suitable surrogate for screening PL pro inhibitors in the BSL-2 setting.

Grow fast but don't die young: Maternal effects mediate life-history trade-offs of lizards under climate warming.

As postulated by life-history theory, not all life-history traits can be maximized simultaneously. In ectothermic animals, climate warming is predicted to increase growth rates, but at a cost to overall life span. Maternal effects are expected to mediate this life-history trade-off, but such effects have not yet been explicitly elucidated. To understand maternal effects on the life-history responses to climate warming in lizard offspring, we conducted a manipulative field experiment on a desert-dwelling viviparous lacertid lizard Eremias multiocellata, using open-top chambers in a factorial design (maternal warm climate and maternal present climate treatments × offspring warm climate and offspring present climate treatments). We found that the maternal warm climate treatment had little impact on the physiological and life-history traits of adult females (i.e. metabolic rate, reproductive output, growth and survival). However, the offspring warm climate treatment significantly affected offspring growth, and both maternal and offspring warm climate treatments interacted to affect offspring survival. Offspring from the warm climate treatment grew faster than those from the present climate treatment. However, the offspring warm climate treatment significantly decreased the survival rate of offspring from maternal present climate treatment, but not for those from the maternal warm climate treatment. Our study demonstrates that maternal effects mediate the trade-off between growth and survival of offspring lizards, allowing them to grow fast without a concurrent cost of low survival rate (short life span). These findings stress the importance of adaptive maternal effects in buffering the impact of climate warming on organisms, which may help us to accurately predict the vulnerability of populations and species to future warming climates.

The in vitro antiviral activity of lactoferrin against common human coronaviruses and SARS-CoV-2 is mediated by targeting the heparan sulfate co-receptor.

Coronavirus disease 2019 (COVID-19) is an ongoing pandemic that lacks effective therapeutic interventions. SARS-CoV-2 infects ACE2-expressing cells and gains cell entry through either direct plasma membrane fusion or endocytosis. Recent studies have shown that in addition to ACE2, heparan sulfate proteoglycans (HSPGs) also play an important role in SARS-CoV-2 cell attachment by serving as an attachment factor. Binding of viral spike protein to HSPGs leads to the enrichment of local concentration for the subsequent specific binding with ACE2. We therefore hypothesize that blocking the interactions between viral spike protein and the HSPGs will lead to inhibition of viral replication. In this study, we report our findings of the broad-spectrum antiviral activity and the mechanism of action of lactoferrin (LF) against multiple common human coronaviruses as well as SARS-CoV-2. Our study has shown that LF has broad-spectrum antiviral activity against SARS-CoV-2, HCoV-OC43, HCoV-NL63, and HCoV-229E in cell culture, and bovine lactoferrin (BLF) is more potent than human lactoferrin. Mechanistic studies revealed that BLF binds to HSPGs, thereby blocking viral attachment to the host cell. The antiviral activity of BLF can be antagonized by the HSPG mimetic heparin. Combination therapy experiment showed that the antiviral activity of LF is synergistic with remdesivir in cell culture. Molecular modelling suggests that the N-terminal positively charged region in BLF (residues 17-41) confers the binding to HSPGs. Overall, LF appears to be a promising drug candidate for COVID-19 that warrants further investigation.