Life-History and Ecological Correlates of Egg and Clutch Mass Variation in Sympatric Bird Species at High Altitude.

The variation in egg and clutch mass in sympatric species at high altitudes is poorly understood, and the potential causes of variation are rarely investigated. This study aimed to describe the interspecific variation in avian egg and clutch mass among 22 sympatric bird species at an altitude of 3430 m. Our objective was to reduce potential confounding effects of biotic/abiotic factors and investigated hypotheses concerning allometry, clutch size, parental care, nest predation, and lifespan as possible correlates and explanations for the observed variation. Our findings indicated that both egg and clutch mass evolve with body mass across species. We found that egg mass variation was not explained by clutch size when controlling for allometric effects, which contrasts the "egg mass vs. clutch size trade-off" hypothesis. Additionally, we found that clutch mass was positively associated with parental care (reflected by development period) but negatively associated with predation rate. By substituting egg mass and clutch size into the models, we found that clutch size was significantly correlated with parental care, predation rate, and lifespan, while egg mass was only significantly associated with development period. Overall, these findings support life-history theories suggesting that reduced clutch size or mass is associated with a higher risk of predation, reduced parental care, but longer adult lifespan. Interestingly, our results indicate that clutch size has a greater influence on these factors compared to egg mass. This could be attributed to the fact that smaller clutch sizes result in a more notable decrease in energetic allocation, as they require a reduced effort in terms of offspring production, incubation, and feeding, as opposed to solely reducing egg size. These findings contribute to the growing evidence that life-history and ecological traits correlate with egg and clutch mass variation in sympatric species. However, further research is needed to explore the potential evolutionary causes underlying these patterns.

Swamp eel aldehyde reductase is involved in response to nitrosative stress via regulating NO/GSH levels.

Aldehyde reductase (ALR) plays key roles in the detoxification of toxic aldehyde. In this study, the authors cloned the swamp eel ALR gene using rapid amplification of cDNA ends-PCR (RACE-PCR). The recombinant protein (rALR) was expressed in Escherichia coli and purified using a Ni2+ -NTA chelating column. The rALR protein exhibited efficient reductive activity towards several aldehydes, ketones and S-nitrosoglutathione (GSNO). A spot assay suggested that the recombinant E. coli strain expressing rALR showed better resistance to formaldehyde, sodium nitrite and GSNO stress, suggesting that swamp eel ALR is crucial for redox homeostasis in vivo. Consequently, the authors investigated the effect of rALR on the oxidative parameters of the liver in swamp eels challenged with Aeromonas hydrophila. The hepatic glutathione (GSH) content significantly increased, and the hepatic NO content and levels of reactive oxygen species and reactive nitrogen species significantly decreased when rALR was administered. In addition, the mRNA expression of hepatic Alr, HO1 and Nrf2 was significantly upregulated, whereas the expression levels of NF-κB, IL-1ß and NOS1 were significantly downregulated in the rALR-administered group. Collectively, these results suggest that ALR is involved in the response to nitrosative stress by regulating GSH/NO levels in the swamp eel.

Nest complexity correlates with larger brain size but smaller body mass across bird species.

Amniotes differ substantially in absolute and relative brain size after controlling for allometry, and numerous hypotheses have been proposed to explain brain size evolution. Brain size is thought to correlate with processing capacity and the brain's ability to support complex manipulation such as nest-building skills. The increased complexity of nest structure is supposed to be a measure of an ability to manipulate nesting material into the required shape. The degree of nest-structure complexity is also supposed to be associated with body mass, partly because small species lose heat faster and delicate and insulated nests are more crucial for temperature control of eggs during incubation by small birds. Here, we conducted comparative analyses to test these hypotheses by investigating whether the complexity of species-typical nest structure can be explained by brain size and body mass (a covariate also to control for allometric effects on brain size) across 1353 bird species from 147 families. Consistent with these hypotheses, our results revealed that avian brain size increases as the complexity of the nest structure increases after controlling for a significant effect of body size, and also that a negative relationship exists between nest complexity and body mass.

Protective effects of Cu/Zn-SOD and Mn-SOD on UVC radiation-induced damage in NIH/3T3 cells and murine skin.

Superoxide dismutase (SOD) is an antioxidant enzyme with multiple metal cofactors that can specifically clear reactive oxygen species (ROS), which plays an important role in a variety of ultraviolet-induced lesions. Therefore, SOD has the anti-ultraviolet radiation effect. The objective of this study was to compare the differences in the anti-ultraviolet radiation effect of SOD with distinct metal cofactors: Cu/Zn-SOD and Mn-SOD. SOD was first purified using hydrophobic interaction chromatography and ion-exchange chromatography. Second, the Methylthiazolyldiphenyl-tetrazolium bromide method and cell senescence kits were used to study the protective effect of SOD on ultraviolet-induced cell damage. Finally, the protective effect of SOD on ultraviolet -induced skin damage was histopathologically evaluated, and the expression levels of malondialdehyde (MDA) and matrix metalloproteinases (MMPs) in tissues were detected. The results showed that Cu/Zn-SOD was superior to Mn-SOD in promoting cell proliferation, alleviating cell damage, protecting skin structure, and regulating the expression levels of MDA and MMPs, and it has no side effects. In conclusion, Cu/Zn-SOD had a better anti-ultraviolet radiation effect than Mn-SOD, and it can be used in anti-aging and anti-ultraviolet skin-care products.

Large brain size is associated with low extra-pair paternity across bird species.

BACKGROUND: Gaining extrapair copulations (EPCs) is a complicated behavior process. The interaction between males and females to procure EPCs may be involved in brain function evolution and lead to a larger brain. Thus, we hypothesized that extrapair paternity (EPP) rate can be predicted by relative brain size in birds. Past work has implied that the EPP rate is associated with brain size, but empirical evidence is rare. METHODS: We collated data from published references on EPP levels and brain size of 215 bird species to examine whether the evolution of EPP rate can be predicted by brain size using phylogenetically generalized least square (PGLS) models and phylogenetic path analyses. RESULTS: We found that EPP rates (both the percentage EP offspring and percentage of broods with EP offspring) are negatively associated with relative brain size. We applied phylogenetic path analysis to test the causal relationship between relative brain size and EPP rate. Best-supported models (ΔCICc < 2) suggested that large brain lead to reduced EPP rate, which failed to support the hypothesis that high rates of EPP cause the evolution of larger brains. CONCLUSION: This study indicates that pursuing EPCs may be a natural instinct in birds and the interaction between males and females for EPCs may lead to large brains, which in turn may restrict their EPC level for both sexes across bird species.

Nest concealment is associated with reproductive traits across sympatric bird species.

Nest-site characteristics are thought to play an important role in reproductive performance in birds (e.g., influencing reproductive success and predation risk). Nest-site characteristics such as concealment may be particularly critical at high elevation where nests are exposed to challenging environmental conditions. In this study, we conducted both conventional and phylogenetically controlled analyses to investigate whether nest concealment affected several reproductive traits across 21 sympatric bird species living on Tibet Plateau (3,400 m altitude). Qualitatively equivalent results were reached in analyses, regardless of phylogenetic controls. We found that clutch size, incubation period, nestling period, and nest success were strongly and positively associated with nest concealment across species. Our study addressed such a high-elevation bird community that is lacking in the previous studies. This study adds to theory that while there are a few exceptions, overall evidence supports a positive effect of nest concealment on reproductive performance across coexisting alpine species.

Development of a subunit vaccine based on fiber2 and hexon against fowl adenovirus serotype 4.

Hepatitis-hydropericardium syndrome (HHS) is widespread in China and causes high chicken mortality that results in great economic losses. A safe and effective vaccine is needed, and a subunit vaccine has potential for development. In this study, a truncated region of the FAdV-4 fiber 2 fused with coding sequence of one epitope of hexon was expressed in a prokaryotic expression system, and the immune protective effects of different doses of recombinant fiber 2 subunit vaccine on SPF chickens were compared. The recombinant fiber2 (Gly275- Pro479 aa)-hexon (Met21-Val51 aa) protein (rFH) obtained in Escherichia coli showed good solubility. The chicken survival rate at the lowest dose (2.5 µg/bird) was 75% (6/8), and at higher doses (≥5 µg/bird) was 100% (8/8) in challenge experiment. Two chickens in the 2.5 µg/bird treatment showed severe lesions, while birds in the higher dose treatments showed no obvious tissue damage as determined by histopathologic analysis of liver and spleen. Absolute quantitative real-time PCR showed no viral load in the ≥5 µg/bird treatments, but two chickens in the 2.5 µg/bird treatment had high viral loads. The challenge experience demonstrated that the rFH vaccine provided 100% protection at ≥5 µg/bird. These results suggested that rFH protein as an effective vaccine to protect against FAdV-4 and provided a new idea for the development of vaccine against HHS.

Displaying epitope B and epitope 7 of porcine reproductive and respiratory syndrome virus on virus like particles of porcine circovirus type 2 provides partial protection to pigs.

The Cap of porcine circovirus type 2 (PCV2) can be assembled into virus like particles (VLPs) in vitro that have multiple loops located on the particle surface. This would make it a good vehicle for displaying exogenous proteins or epitopes. We derived two epitopes, epitope B (EpB, S37HIQLIYNL45) and epitope 7 (Ep7, Q196WGRL200) from Gp5 of the highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV). We replaced the core region of Loop CD (L75PPGGGSN82) and the carboxyl terminus (K222DPPL226) of PCV2 Cap, respectively, to construct a bi-epitope chimeric PCV2 Cap. Its immunogenicity and protective effects were evaluated as one PRRSV subunit vaccine. The chimeric PCV2 Cap was soluble, efficiently expressed in an Escherichia coli expression system, and could be self-assembled into chimeric virus like particles (cVLPs) with a diameter of 12-15 nm. Western blotting confirmed that the cVLPs could be specifically recognized by anti-PCV2, anti-EpB and anti-Ep7 antibodies. The cVLPs vaccine could alleviate the clinical symptoms and reduce the viral loads after HP-PRRSV challenge in 100-120 days old pigs. These data suggest that the cVLPs vaccine could provide pigs with partial protection against homologous PRRSV strains, and it provides a new design for additional PRRSV subunit vaccines.

Establishment of a Rep' protein antibody detection method to distinguish natural infection with PCV2 from subunit vaccine immunization.

Introduction. PCV2 is a DNA virus that exists widely in pigs and has caused great economic losses to the pig industry worldwide. In the existing commercial PCV2 enzyme-linked immunosorbent assay (ELISA) kits both natural infection with PCV2 and vaccine immunization produce results that are positive for PCV2 Cap antibodies and therefore they cannot diagnose PCV2 infection in immunized pig farms.Aim. To establish a PCV2 non-structural protein antibody detection method that distinguishes between antibodies resulting from natural prior exposure (infection) and those induced by subunit vaccine immunization.Methodology. Based on the non-structural Rep' protein, we established an indirect ELISA (iELISA) using sera from guinea pigs and piglets.Results. The results for iELISA for guinea pig serum showed that animals vaccinated with a whole-virus inactivated PCV2 vaccine had 100 % (10/10) Cap antibody positivity and 100 % (10/10) Rep' antibody positivity. Guinea pigs vaccinated with a recombinant subunit PCV2 vaccine had 100 % (10/10) Cap antibody positivity, while no (0/10) guinea pigs were Rep' antibody-positive. The combined detection results for the Rep' iELISA and a PCV2 Antibody Test kit (Commercial) showed that pigs vaccinated with a whole-virus inactivated PCV2 vaccine or PCV2 SD/2017 had 100 % (5/5) Cap antibody positivity and 100 % (5/5) Rep' antibody positivity. Pigs vaccinated with a recombinant subunit PCV2 vaccine had 100 % (5/5) Cap antibody positivity, while no (0/10) pigs were Rep' antibody-positive.Conclusion. This paper describes an effective iELISA method that can distinguish natural infection with PCV2 (Cap and Rep positive) or inoculation with a whole-virus inactivated vaccine (Cap and Rep positive) from subunit vaccine immunization (Cap-positive, Rep-negative). These comparative assays could be very useful in the control of PCV2 in pig herds.

Development of a recombinant VP2 vaccine for the prevention of novel variant strains of infectious bursal disease virus.

Since 2017, novel variant strains of infectious bursal disease virus (nvIBDV) have been detected in China, while the current vaccines on the market against very virulent IBDV have limited protection against this subtype virus. In this context, a strain of the virus has been isolated, and sequencing alignment and bird regression experiments showed that the virus was IBDV, belonging to the nvIBDV subtype (and named IBDV FJ-1812). Furthermore, the Escherichia coli expression system was used to successfully express soluble nvIBDV rVP2, which is specifically recognized by an anti-IBDV standard serum and anti-nvIBDV positive serum, and could be assembled into 14 - 17 nm virus-like particles. Based on the purified nvIBDV rVP2, we developed an IBDV FJ-1812 VP2 VLP vaccine at a laboratory scale to evaluate protection by this vaccine; in addition, we also prepared an IBDV JZ 3/02 VP2 subunit vaccine targeting very virulent IBDV and evaluated its cross-protection against nvIBDV. Results of bird experiments showed that the nvIBDV rVP2 vaccine could induce high titres of specific antibodies, completely protect the bursa of Fabricius from viral infection, and provide 100% immune protection to SPF and Ross 308 broiler chickens. Furthermore, the IBDV JZ 3/02 VP2 subunit vaccine targeting very virulent IBDV could provide 60% protection for SPF chickens and 80% protection for Ross 308 broiler chickens. This report provides important technical supports for the prevention and control of nvIBDV in the future.

Characterization of complete mitochondrial genome of the Brown Accentor Prunella fulvescens on the Tibet Plateau.

The Brown Accentor (Prunella fulvescens) is a poorly known bird species distributed in Eurasia high-montane areas. In this paper, we described the whole mitochondrial genome of the Brown Accentor. The entire mitochondrial sequences were determined using long-range PCR and conserved primer walking approaches. The results demonstrated that the whole mitochondrial genome of P. fulvescens was 16,837 bp in length with 54.1% A + T content; the genome harboured the same gene order as that of other passerine birds, including 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes and 1 non-coding control region. The control region (D-loop) of P. fulvescens was located between tRNA-Gln and tRNA-Phe with 1247 bp length. These mitochondrial data are potentially important for the further studies on molecular evolution and conservation genetics in avian species.

Complete mitochondrial genome of the isabelline wheatear Oenanthe isabellina (Passeriformes, Muscicapidae).

The isabelline wheatear Oenanthe isabellina was widespread in Northern Hemisphere, but the information of this species is poorly known. In this study, the complete sequence of O. isabellina mitochondrial genome was obtained by L-PCR and conserved primer-walking approaches. The results showed that the entire mitochondrial genome of O. isabellina was 16,812 bp in length with 52.7% A + T content; the genome harbored the same gene order as that of other birds, including 2 rRNA genes, 22 tRNA genes, 13 protein-coding genes and 1 non-coding control region (D-loop). All protein-coding genes of O. isabellina mitochondrial genome started with an ATG codon, except for COI with GTG. For terminate codon usage, most of the genes use TAA or TAG. The control region of O. isabellina was located between tRNA-Glu and tRNA-Phe with 1244 bp length, no repetitive sequence. The mitochondrial data are potentially important for understanding this poorly known species.