Genome‐wide analysis of TNF‐alpha response in pigs challenged with porcine circovirus 2b

Tumor necrosis factor alpha (TNF‐α) is a pro‐inflammatory cytokine with a role in activating adaptive immunity to viral infections. By inhibiting the capacity of plasmacytoid dendritic cells to produce interferon‐α and TNF‐α, porcine circovirus 2 (PCV2) limits the maturation of myeloid dendritic cells and impairs their ability to recognize viral and bacterial antigens. Previously, we reported QTL for viremia and immune response in PCV2‐infected pigs. In this study, we analyzed phenotypic and genetic relationships between TNF‐α protein levels, a potential indicator of predisposition to PCV2 co‐infection, and PCV2 susceptibility. Following experimental challenge with PCV2b, TNF‐α reached the peak at 21 days post‐infection (dpi), at which time a difference was observed between pigs that expressed extreme variation in viremia and growth (P < 0.10). A genome‐wide association study (n = 297) revealed that genotypes of 56 433 SNPs explained 73.9% of the variation in TNF‐α at 21 dpi. Major SNPs were identified on SSC8, SSC10 and SSC14. Haplotypes based on SNPs from a SSC8 (9 Mb) 1‐Mb window were associated with variation in TNF‐α (P < 0.02), IgG (P = 0.05) and IgM (P < 0.13) levels at 21 dpi. Potential overlap of regulatory mechanisms was supported by the correlations between genomic prediction values of TNF‐α and PCV2 antibodies (21 dpi, r > 0.22), viremia (14–21 dpi, P > 0.29) and viral load (r = 0.31, P < 0.0001). Characterization of the QTL regions uncovered genes that could influence variation in TNF‐α levels as well as T‐ and B‐cell development, which can affect disease susceptibility.     

Protective efficacy of a DNA vaccine encoding capsid protein of porcine circovirus‐like virus P1 against porcine circovirus 2 in mice

The capsid protein is the major immunogenic protein of porcine circovirus 2 (PCV2). The nucleotide sequence of porcine circovirus‐like virus P1 shares high homology with open reading frame (ORF) 2 of PCV2, and ORF1 of P1 encodes its structural protein. Mice were vaccinated twice intramuscularly with a plasmid expressing the P1 ORF1 protein (pcDNA3.1(+)‐ORF1) at 2‐week intervals. All animals vaccinated with pcDNA3.1(+)‐ORF1 developed higher specific anti‐P1 antibody levels, and had less PCV2 viremia and milder histopathological changes than PCV2‐challenged mice in the control group. Our results show that the P1 DNA vaccine elicited immune responses against PCV2 infection in a mouse model.

     

Reproductive biology of Chinese minnow Hemiculterella sauvagei Warpachowski, 1888 in the Chishui River,China

This study describes the reproductive biology of the Chinese minnow Hemiculterella sauvagei. The length‐weight relationship, sex ratio, spawning season, size at first maturity, and fecundity were analyzed based on 685 specimens collected from the Chishui River between July 2011 and July 2012. The relationship between standard length (SL) and body weight (BW) were estimated as BW = 2.14 × 10^?4 × SL^2.801 (R² = 0.839; N = 413; P < 0.05) for females and BW = 1.31 × 10^?4 × SL^3.001 (R² = 0.868; N = 272; P < 0.05) for males. The female to male sex ratio, 1.52 : 1, differed significantly from a 1 : 1 ratio. Females predominated in standard lengths >12 cm. Analyses of the monthly variation in the gonadosomatic index (GSI), the monthly proportions of macroscopic gonadal maturity, and the size distribution of oocytes consistently suggested a prolonged spawning season of H. sauvagei from March to August, with a peak from April to May. Logistic curves describing the relationship between proportion of maturity (P_r) at each length interval and standard length were estimated as P_r = 1/(1 + e^{26.867–0.306SL}) (R² = 0.999; N = 413; P < 0.05) for females and P_r = 1/(1 + e^{10.522–0.142SL}) (R² = 0.999; N = 272; P < 0.05) for males. Size at first maturity was estimated as 7.4 cm for males and 8.8 cm SL for females. Absolute fecundity varied from 563 to 5052, with a mean of 2413 ± 874 oocytes per ovary. The relative fecundity was estimated to be 41–299, with a mean of 171 ± 55 oocytes per ovary. The present study provides useful information for fishery management and resources conservation.     

QTL analysis of body weight and carcass body length traits in an F2 intercross between Landrace and Korean native pigs

Growth traits, such as body weight and carcass body length, directly affect productivity and economic efficiency in the livestock industry. We performed a genome‐wide linkage analysis to detect the quantitative trait loci (QTL) that affect body weight, growth curve parameters and carcass body length in an F₂ intercross between Landrace and Korean native pigs. Eight phenotypes related to growth were measured in approximately 1000 F₂ progeny. All experimental animals were subjected to genotypic analysis using 173 microsatellite markers located throughout the pig genome. The least squares regression approach was used to conduct the QTL analysis. For body weight traits, we mapped 16 genome‐wide significant QTL on SSC1, 3, 5, 6, 8, 9 and 12 as well as 22 suggestive QTL on SSC2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16 and 17. On SSC12, we identified a major QTL affecting body weight at 140 days of age that accounted for 4.3% of the phenotypic variance, which was the highest test statistic (F‐ratio = 45.6 under the additive model, nominal P = 2.4 × 10^?11) observed in this study. We also showed that there were significant QTL on SSC2, 5, 7, 8, 9 and 12 affecting carcass body length and growth curve parameters. Interestingly, the QTL on SSC2, 3, 5, 6, 8, 9, 10, 12 and 17 influencing the growth‐related traits showed an obvious trend for co‐localization. In conclusion, the identified QTL may play an important role in investigating the genetic structure underlying the phenotypic variation of growth in pigs.     

PERMANENT GENETIC RESOURCES: Isolation of microsatellite loci from the endangered plant Sibara filifolia (Brassicaceae)

Sibara filifolia (Brassicaceae) is a federally endangered annual herb found on two of the California Channel Islands. Previous studies based on allozymes revealed little genetic variability on San Clemente Island. Nine polymorphic microsatellite loci were isolated from individuals on San Clemente Island. We found low levels of allelic variation (mean N_A = 2.3), with seven loci exhibiting significant deviations from Hardy–Weinberg equilibrium (P < 0.01) and 10 pairs of loci exhibiting significant linkage disequilibrium (P < 0.01). Most of the observed variability (mean H_O = 0.003) occurred among populations or in rare homozygous individuals.     

Carbon isotope discrimination in leaves of the broad‐leaved paperbark tree,Melaleuca quinquenervia,as a tool for quantifying past tropical and subtropical rainfall

Quantitative reconstructions of terrestrial climate are highly sought after but rare, particularly in Australia. Carbon isotope discrimination in plant leaves (Δ_leaf) is an established indicator of past hydroclimate because the fractionation of carbon isotopes during photosynthesis is strongly influenced by water stress. Leaves of the evergreen tree Melaleuca quinquenervia have been recovered from the sediments of some perched lakes on North Stradbroke and Fraser Islands, south‐east Queensland, eastern Australia. Here, we examine the potential for using M. quinquenervia ?_leaf as a tracer of past rainfall by analysing carbon isotope ratios (δ¹³C) of modern leaves. We firstly assess Δ_leaf variation at the leaf and stand scale and find no systematic pattern within leaves or between leaves due to their position on the tree. We then examine the relationships between climate and Δ_leaf for a 11‐year time series of leaves collected in a litter tray. M. quinquenervia retains its leaves for 1–4 years; thus, cumulative average climate data are used. There is a significant relationship between annual mean ?_leaf and mean annual rainfall of the hydrological year for 1–4 years (i.e. 365–1460 days) prior to leaf fall (r² = 0.64, P = 0.003, n = 11). This relationship is marginally improved by accounting for the effect of pCO₂ on discrimination (r² = 0.67, P = 0.002, n = 11). The correlation between rainfall and Δ_leaf, and the natural distribution of Melaleuca quinquenervia around wetlands of eastern Australia, Papua New Guinea and New Caledonia offers significant potential to infer past rainfall on a wide range of spatial and temporal scales.     

Wnt/β‐catenin signaling and adipogenic genes are associated with intramuscular fat content in the longissimus dorsi muscle of Korean cattle

Intramuscular fat (IMF) is an important trait that influences beef quality. In two studies, we examined the possible involvement of the Wnt/β‐catenin signaling pathway in IMF deposition in Korean cattle. In study 1, using a group of bulls and steers, we found that castration, a non‐genetic factor, decreased (P < 0.01) the expression of both the WNT10B and CTNNB1 genes, whereas it increased the expression of the Wnt antagonist secreted frizzled‐related proteins 4 (SFRP4, P < 0.001) and the adipogenic CCAAT/enhancer binding protein (C/EPB), alpha (CEBPA, P < 0.001) and peroxisome proliferator‐activated receptor gamma (PPARG, P < 0.05) genes in longissimus dorsi muscle (LM) tissue. The WNT10B and CTNNB1 mRNA levels showed strong (P < 0.001) negative correlations (r = ?0.68 and r = ?0.73 respectively) with the IMF content, whereas the SFRP4, CEBPA and PPARG mRNA levels showed strong (P < 0.01) positive correlations (r = 0.70, 0.70 and 0.64 respectively) with the IMF content. Large variation still exists in the IMF content of steers, implying that genetic factors affect IMF deposition. Using a different group of steers, a correlation analysis in study 2 also showed that the expression of the WNT10B and CTNNB1 genes, and SFRP4 and adipogenic genes was negatively and positively associated with the IMF content respectively. Our findings suggest that downregulation of the Wnt/β‐catenin signaling pathway genes, but upregulation of Wnt antagonist SFRP4 and adipogenic gene expression following castration, contributes to increased IMF deposition in the LM. Our results demonstrate that both non‐genetic factors (castration) and genetic variation within the steer group affect the gene expression pattern of the Wnt/β‐catenin signaling pathway.     

The porcine fat mass and obesity associated (FTO) gene is associated with fat deposition in Italian Duroc pigs

In humans, common variants in the fat mass and obesity associated ( FTO ) gene are associated with body mass index and obesity. Here we sequenced exon 4, parts of introns 3 and 4 and two portions of the 3'-untranslated region of the porcine FTO gene in a panel of nine pigs of different breeds and identified three SNPs. Allele frequencies of the g.276T>G ( AM931150 ) mutation were studied in seven pig breeds. This mutation was used to linkage-map FTO to SSC6. Association analyses between the g.276T>G polymorphism and several traits [pH of semimembranosus muscle and estimated breeding values (EBV) for average daily gain, back fat thickness, lean cuts, ham weight and feed:gain ratio] were carried out in 257 sib-tested Italian Large White pigs. Only feed:gain ratio showed P  <   0.05. A selective genotyping approach was applied, analysing two extreme and divergent groups of Italian Large White pigs selected on the basis of back fat thickness EBV (50 with most positive and 50 with most negative values). Fisher's exact test (two-tailed) was not significant when comparing the allele frequencies of these two groups. The same approach was used in the Italian Duroc breed for which two extreme and divergent groups of animals were selected according to visible intermuscular fat EBV. Differences of allele frequencies between these two groups were highly significant ( P  <   0.00001, P  <   0.001 and P  <   0.0001, considering all animals or only two- or three-generation unrelated animals respectively), indicating association between the analysed FTO marker and intermuscular fat deposition.     

Length–weight relationship and condition factor of wild,grow‐out and ‘loose‐shell affected’ giant tiger shrimp,Penaeus monodon (Fabricius, 1798) (Decapoda: Penaeidae)

Length–weight relationships and condition factors of wild, cultured, and cultured loose‐shell affected Penaeus monodon (2,609 specimens total) were studied from March to August 2007. The regression equation for healthy cultured shrimps was log W = ?1.811 + 2.721 log L (r² = 0.71); log W = ?1.444 + 2.485 log L (r² = 0.91) for wild shrimps; and log W = ?1.112 + 2.237 log L (r² = 0.92) for loose‐shell affected shrimps. All shrimps showed negative allometric growth, although ancova indicated significant differences (P < 0.05) among them. This study presents the first known reference dealing with LWRs and condition factors of cultured, wild and loose‐shell affected P. monodon.     

Enhancement of the immunogenicity of a porcine circovirus type 2 DNA vaccine by a recombinant plasmid coexpressing capsid protein and porcine interleukin‐6 in mice

The development of effective vaccines against porcine circovirus type 2 (PCV2) has been accepted as an important strategy in the prophylaxis of post‐weaning multisystemic wasting syndrome; a DNA vaccine expressing the major immunogenic capsid (Cap) protein of PCV2 is considered to be a promising candidate. However, DNA vaccines usually induce weak immune responses. In this study, it was found that the efficacy of a DNA vaccine expressing Cap protein was improved by simultaneous expression of porcine IL‐6. A plasmid (pIRES‐ORF2/IL6) separately expressing both Cap protein and porcine IL‐6 was constructed and compared with another plasmid (pIRES‐ORF2) expressing Cap protein for its potential to induce PCV2‐specific immune responses. Mice were vaccinated i.m. twice at 3 week intervals and the induced humoral and cellular responses evaluated. All animals vaccinated with pIRES‐ORF2/IL6 and pIRES‐ORF2 developed specific anti‐PCV2 antibodies (according to enzyme‐linked immunosorbent assay) and a T lymphocyte proliferation response. The percentages of CD3⁺, CD3⁺CD8⁺, and CD3⁺CD4⁺ subgroups of peripheral blood T‐lymphocytes were significantly higher in mice immunized with pIRES‐ORF2/IL6 than in those that had received pIRES‐ORF2. After challenge with the virulent PCV2 Wuzhi isolate, mice vaccinated with pIRES‐ORF2/IL6 had significantly less viral replication than those vaccinated with pIRES‐ORF2, suggesting that the protective immunity induced by pIRES‐ORF2/IL6 is superior to that induced by pIRES‐ORF2.     

The Pillars of Hercules as a bathymetric barrier to gene flow promoting isolation in a global deep‐sea shark (Centroscymnus coelolepis)

Knowledge of the mechanisms limiting connectivity and gene flow in deep‐sea ecosystems is scarce, especially for deep‐sea sharks. The Portuguese dogfish (Centroscymnus coelolepis) is a globally distributed and near threatened deep‐sea shark. C. coelolepis population structure was studied using 11 nuclear microsatellite markers and a 497‐bp fragment from the mtDNA control region. High levels of genetic homogeneity across the Atlantic (Φ_ST = ?0.0091, F_ST = 0.0024, P > 0.05) were found suggesting one large population unit at this basin. The low levels of genetic divergence between Atlantic and Australia (Φ_ST = 0.0744, P < 0.01; F_ST = 0.0015, P > 0.05) further suggested that this species may be able to maintain some degree of genetic connectivity even across ocean basins. In contrast, sharks from the Mediterranean Sea exhibited marked genetic differentiation from all other localities studied (Φ_ST = 0.3808, F_ST = 0.1149, P < 0.001). This finding suggests that the shallow depth of the Strait of Gibraltar acts as a barrier to dispersal and that isolation and genetic drift may have had an important role shaping the Mediterranean shark population over time. Analyses of life history traits allowed the direct comparison among regions providing a complete characterization of this shark's populations. Sharks from the Mediterranean had markedly smaller adult body size and size at maturity compared to Atlantic and Pacific individuals. Together, these results suggest the existence of an isolated and unique population of C. coelolepis inhabiting the Mediterranean that most likely became separated from the Atlantic in the late Pleistocene.     

Similarities and differences in 13C and 15N stable isotope ratios in two non‐lethal tissue types from shovelnose sturgeon Scaphirhynchus platorynchus (Rafinesque, 1820)

We tested the hypothesis that δ¹³C and δ¹⁵N signatures of pectoral spines would provide measures of δ¹³C and δ¹⁵N similar to those obtained from fin clips for adult shovelnose sturgeon Scaphirhynchus platorynchus. Thirty‐two shovelnose sturgeon (fork length [FL] = 500–724 mm) were sampled from the lower Mississippi River, USA on 23 February 2013. Isotopic relationships between the two tissue types were analyzed using mixed model analysis of covariance. Tissue types differed significantly for both δ¹³C (P < 0.01; spine: mean = ?23.83, SD = 0.62; fin clip: mean = ?25.74, SD = 0.97) and δ¹⁵N (P = 0.01; spine: mean = 17.01, SD = 0.51; fin clip: mean = 17.19, SD = 0.62). Neither FL nor the FL × tissue type interaction had significant (P > 0.05) effects on δ¹³C. Fin clip δ¹³C values were highly variable and weakly correlated (r = 0.16, P = 0.40) with those from pectoral spines. We found a significant FL‐tissue type interaction for δ¹⁵N, reflecting increasing δ¹⁵N with FL for spines and decreasing δ¹⁵N with FL for fin clips. These results indicate that spines are not a substitute for fin clip tissue for measuring δ¹³C and δ¹⁵N for shovelnose sturgeon in the lower Mississippi River, but the two tissues have different turnover rates they may provide complementary information for assessing trophic position at different time scales.     

Evaluation of the causality of the low‐density lipoprotein receptor gene (LDLR) for serum lipids in pigs

A significant quantitative trait locus (QTL) for low‐density lipoprotein cholesterol (LDL‐C) and total cholesterol (TC) was identified around the LDLR gene on chromosome 2 (SSC2) in a White Duroc × Erhualian F₂ resource population and Sutai pigs in our previous study. However, in previous reports, the causality of LDLR with serum lipids is controversial in pigs. To systematically assess the causality of LDLR with serum lipids, association analyses were successively performed in three populations: Sutai pigs, a White Duroc × Erhualian F₂ resource population and a Duroc × (Landrace × Large White) population. We first performed a haplotype‐based association study with 60K SNP genotyping data and evidenced the significant association with LDL‐C and TC around the LDLR gene region. We also found that there is more than one QTL for LDL‐C and TC on SSC2. Then, we evaluated the causalities of two missense mutations, c.1812C>T and c.1520A>G, with LDL‐C and TC. We revealed that the c.1812C>T SNP showed the strongest association with LDL‐C (P = 5.40 × 10^?11) and TC (P = 3.64 × 10^?8) and explained all the QTL effect in Sutai pigs. Haplotype analysis found that two missense SNPs locate within a 1.93‐Mb haplotype block. One major haplotype showed the strongest significant association with LDL‐C (P = 4.62 × 10^?18) and TC (P = 1.06 × 10^?9). However, the c.1812C>T SNP was not identified in the White Duroc × Erhualian intercross, and the association of c.1520A>G with both LDL‐C and TC did not achieve significance in this F₂ population, suggesting population heterogeneity. Both missense mutations were identified in the Duroc × (Landrace × Large White) population and showed significant associations with LDL‐C and TC. Our data give evidence that the LDLR gene should be a candidate causative gene for LDL‐C and TC in pigs, but heterogeneity exists in different populations.     

Immunogenicity of plant‐produced porcine circovirus‐like particles in mice

Porcine circovirus type 2 (PCV‐2) is the main causative agent associated with a group of diseases collectively known as porcine circovirus‐associated disease (PCAD). There is a significant economic strain on the global swine industry due to PCAD and the production of commercial PCV‐2 vaccines is expensive. Plant expression systems are increasingly regarded as a viable technology to produce recombinant proteins for use as pharmaceutical agents and vaccines. However, successful production and purification of PCV‐2 capsid protein (CP) from plants is an essential first step towards the goal of a plant‐produced PCV‐2 vaccine candidate. In this study, the PCV‐2 CP was transiently expressed in Nicotiana benthamiana plants via agroinfiltration and PCV‐2 CP was successfully purified using sucrose gradient ultracentrifugation. The CP self‐assembled into virus‐like particles (VLPs) resembling native virions and up to 6.5 mg of VLPs could be purified from 1 kg of leaf wet weight. Mice immunized with the plant‐produced PCV‐2 VLPs elicited specific antibody responses to PCV‐2 CP. This is the first report describing the expression of PCV‐2 CP in plants, the confirmation of its assembly into VLPs and the demonstration of their use to elicit a strong immune response in a mammalian model.     

A study on age and growth characteristics of spiny gurnard (Lepidotrigla dieuzeidei Blanc & Hureau, 1973), northeastern Mediterranean Sea

This study investigated the age and growth characteristics of spiny gurnard, Lepidotrigla dieuzeidei, from the northeastern Mediterranean. Samples were collected by commercial trawls during the 2012–2013 fishing seasons. A total 1,878 speciments ranged from 7.10 to 15.90 cm total length and 2.28–35.88 g in weight. Female/male ratio was 1.2/1. The total length–weight relationship was W = 0.002 TL^3.579 (r² = .909) for sexes combined, W = 0.0021 TL^3.551 (r² = .914) for males and W = 0.0019 TL^3.602 (r² = .904) for females. Age determination was conducted using the sagittal otoliths. Ages of examined individulas ranged from 3 to 11 years. Total length‐at‐age data were fitted using the von Bertalanffy growth model. Estimated growth functions were TL_t = 18.100 [1?e^{?0.14 (t + 0.63)}] for sexes combined, TL_t = 23.587 [1?e^{?0.08 (t + 1.56)}] for males and TL_t = 16.612 [1?e^{?0.19 (t + 0.15)}] for females.     

An experimental live chimeric porcine circovirus 1-2a vaccine decreases porcine circovirus 2b viremia when administered intramuscularly or orally in a porcine circovirus 2b and porcine reproductive and respiratory syndrome virus dual-challenge model

Commercially available inactivated vaccines against porcine circovirus type 2 (PCV2) have been shown to be effective in reducing PCV2 viremia. Live-attenuated, orally administered vaccines are widely used in the swine industry for several pathogens because of their ease of use yet they are not currently available for PCV2 and efficacy. The aims of this study were to determine the efficacy of a live-attenuated chimeric PCV2 vaccine in a dual-challenge model using PCV2b and porcine reproductive and respiratory syndrome virus (PRRSV) and to compare intramuscular (IM) and oral (PO) routes of vaccination. Eighty-three 2-week-old pigs were randomized into 12 treatment groups: four vaccinated IM, four vaccinated PO and four non-vaccinated (control) groups. Vaccination was performed at 3 weeks of age using a PCV1-2a live-attenuated vaccine followed by no challenge, or challenge with PCV2b, PRRSV or a combination of PCV2b and PRRSV at 7 weeks of age. IM administration of the vaccine elicited an anti-PCV2 antibody response between 14 and 28 days post vaccination, 21/28 of the pigs being seropositive prior to challenge. In contrast, the anti-PCV2 antibody response in PO vaccinated pigs was delayed, only 1/27 of the pigs being seropositive at challenge. At 21 days post challenge, PCV2 DNA loads were reduced by 80.4% in the IM vaccinated groups and by 29.6% in the PO vaccinated groups. PCV1-2a (vaccine) viremia was not identified in any of the pigs. Under the conditions of this study, the live attenuated PCV1-2a vaccine was safe and provided immune protection resulting in reduction of viremia. The IM route provided the most effective protection.     

The influence of iron,siderophores and refractory DOM on cyanobacterial biomass in oligotrophic lakes

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The association between paraoxonase 1 activity and the susceptibilities of diabetes mellitus,diabetic macroangiopathy and diabetic microangiopathy

We carried out this meta‐analysis to explore the influence of paraoxonase 1 activity on the susceptibility of diabetes mellitus (DM), diabetic macroangiopathy and diabetic microangiopathy. Relevant studies were identified from PubMed, Web of Science and CNKI without language limitation, following the inclusion and exclusion criteria. Statistical analyses were implemented with the STATA 12.0 statistical software. Thirty‐six case‐control studies were included in the meta‐analyses, in which 35 for the association between paraoxonase 1 activity and DM risk, 8 for diabetic macroangiopathy and 7 for diabetic microangiopathy. Paraoxonase 1 activity was significantly associated with the susceptibility of DM in pooled population (SMD = ?1.37, 95% CI = ?1.79 ～ ?0.96, P = .000), and Asians (SMD = ?2.00, 95% CI = ?2.56 ～ ?1.44, P = .000), but not in non‐Asians (SMD = ?0.44, 95% CI = ?0.91 ～ 0.03, P = .069). However, marked heterogeneity was existed (I² = 98.10%, P = .000) and subgroup analyses failed to investigate the sources of heterogeneity. Then, meta‐regression was performed and found that ethnicity could explain the observed between‐study heterogeneity (P = .002). Meanwhile, significant associations were found between paraoxonase 1 activity and diabetic macroangiopathy (SMD = ?1.06, 95% CI = ?1.63 ～ ?0.48, P = .000) and diabetic microangiopathy (SMD = ?0.72, 95% CI = ?1.32 ～ ?0.13, P = .018). In conclusion, paraoxonase 1 activity plays important roles in the risk of DM, diabetic macroangiopathy and microangiopathy with ethnicity differences. Further studies with large sample and well design are needed to confirm these results.     

应用高效体积排阻色谱偶联多角度激光散射鉴定猪圆环病毒2型灭活疫苗及病毒样颗粒疫苗抗原

本文旨在建立基于高效体积排阻色谱(high-performance size-exclusion chromatography,HPSEC)偶联多角度激光散射仪(multi-angle laser light scattering,MALLS)的猪圆环病毒2型(porcine circovirus type 2,PCV2)疫苗抗原检测方法。以纯化的PCV2灭活病毒及病毒样颗粒(virus-like particles,VLP)为参照,对4家生产企业的2种PCV2灭活病毒疫苗(a、b)及VLP疫苗(c、d)破乳后进行HPSEC-MALLS检测及分子量分析;结合PCV2抗原检测卡、Western blotting和透射电子显微镜(transmission electron microscope,TEM),鉴定了特征色谱峰;考察了方法的重复性和检测线性。结果表明,两家企业生产的PCV2灭活病毒疫苗破乳液水相经HPSEC分离,在保留时间约13.3 min处出现抗原特征峰;MALLS计算该色谱峰分子量分别为2.61×10⁶(±4.34%) Da和2.40×10⁶(±2.51%) Da。两种VLP疫苗也在13.3 min处出现抗原特征峰,分子量分别为2.09×10⁶(±2.94%) Da和2.88×10⁶(±11.85%) Da,接近PCV2的理论分子量;同时在保留时间约11.4 min处也出现色谱峰,经检测分子量为4.37×10⁶(±0.42%) Da,TEM表征显示为VLP二聚体。取疫苗d和PCV2 VLP纯品进行重复检测,抗原色谱峰面积的RSD(n=3)均小于1.5%,重复性好;将PCV2 VLP纯品梯度稀释检测,VLP及其多聚体的色谱峰面积与浓度均呈良好的线性关系,R²分别为0.999及0.997,能够满足定量及多聚体含量分析。该方法有望成为一种准确、高效的PCV2疫苗的体外评价方法,用于质量评价与提升。     

Association of Ant Predators and Edaphic Conditions with Termite Diversity in an Amazonian Rain Forest

Predation is a key determinant of prey community structure, but few studies have measured the effect of multiple predators on a highly diverse prey community. In this study, we asked whether the abundance, species richness, and species composition of a species‐rich assemblage of termites in an Amazonian rain forest is more strongly associated with the density of predatory ants or with measures of vegetation, and soil texture and chemistry. We sampled termite assemblages with standardized hand‐collecting in 30 transects arranged in a 5 km × 6 km grid in a terra firme Amazonian rain forest. For each transect, we also measured vegetation structure, soil texture, and soil phosphorus, and estimated the density of predatory ants from baits, pitfall traps, and Winkler samples. Seventy‐nine termite species were recorded, and the total density of predatory ants was the strongest single predictor of local termite abundance (r = ?0.66) and termite species richness (r = ?0.44). In contrast, termite abundance and species richness were not strongly correlated with edaphic conditions (¦r¦ < 0.01), or with the density of non‐predatory ants (r_abund = ?0.27; r_s = ?0.06). Termite species composition was correlated with soil phosphorus content (r = 0.79), clay content (r = ?0.75), and tree density (r = ?0.42). Assemblage patterns were consistent with the hypothesis that ants collectively behaved as generalist predators, reducing total termite abundance, and species richness. There was no evidence that ants behaved as keystone predators, or that any single termite species benefited from the reduction in the abundance of potential competitors.