Extra-pair mating in a passerine bird with highly duplicated major histocompatibility complex class II: Preference for the golden mean.

Genes of the major histocompatibility complex (MHC) are essential in vertebrate adaptive immunity, and they are highly diverse and duplicated in many lineages. While it is widely established that pathogen-mediated selection maintains MHC diversity through balancing selection, the role of mate choice in shaping MHC diversity is debated. Here, we investigate female mating preferences for MHC class II (MHCII) in the bluethroat (Luscinia svecica), a passerine bird with high levels of extra-pair paternity and extremely duplicated MHCII. We genotyped family samples with mixed brood paternity and categorized their MHCII alleles according to their functional properties in peptide binding. Our results strongly indicate that females select extra-pair males in a nonrandom, self-matching manner that provides offspring with an allelic repertoire size closer to the population mean, as compared to offspring sired by the social male. This is consistent with a compatible genes model for extra-pair mate choice where the optimal allelic diversity is intermediate, not maximal. This golden mean presumably reflects a trade-off between maximizing pathogen recognition benefits and minimizing autoimmunity costs. Our study exemplifies how mate choice can reduce the population variance in individual MHC diversity and exert strong stabilizing selection on the trait. It also supports the hypothesis that extra-pair mating is adaptive through altered genetic constitution in offspring.

The gut microbial profile in patients with primary sclerosing cholangitis is distinct from patients with ulcerative colitis without biliary disease and healthy controls.

OBJECTIVE: Gut microbiota could influence gut, as well as hepatic and biliary immune responses. We therefore thoroughly characterised the gut microbiota in primary sclerosing cholangitis (PSC) compared with healthy controls (HC) and patients with ulcerative colitis without liver disease. DESIGN: We prospectively collected 543 stool samples. After a stringent exclusion process, bacterial DNA was submitted for 16S rRNA gene sequencing. PSC and HC were randomised to an exploration panel or a validation panel, and only significant results (p<0.05, QFDR<0.20) in both panels were reported, followed by a combined comparison of all samples against UC. RESULTS: Patients with PSC (N=85) had markedly reduced bacterial diversity compared with HC (N=263, p<0.0001), and a different global microbial composition compared with both HC (p<0.001) and UC (N=36, p<0.01). The microbiota of patients with PSC with and without IBD was similar. Twelve genera separated PSC and HC, out of which 11 were reduced in PSC. However, the Veillonella genus showed a marked increase in PSC compared with both HC (p<0.0001) and UC (p<0.02). Using receiver operating characteristic analysis, Veillonella abundance yielded an area under the curve (AUC) of 0.64 to discriminate PSC from HC, while a combination of PSC-associated genera yielded an AUC of 0.78. CONCLUSIONS: Patients with PSC exhibited a gut microbial signature distinct from both HC and UC without liver disease, but similar in PSC with and without IBD. The Veillonella genus, which is also associated with other chronic inflammatory and fibrotic conditions, was enriched in PSC.

FUT2 and FUT3 genotype determines CA19-9 cut-off values for detection of cholangiocarcinoma in patients with primary sclerosing cholangitis.

BACKGROUND & AIMS: Allelic variants of fucosyltransferases 2 and 3 (FUT2/3) influence serum levels of CA19-9, a screening parameter commonly used for detection of biliary malignancy in PSC. We aimed at improving diagnostic accuracy of CA19-9 by determining the impact of FUT2/3 genotypes. METHODS: CA19-9 levels were measured in 433 PSC patients, 41 of whom had biliary malignancy. Genotypes for FUT3 and FUT2 were used to assign patients to one of three groups: A, no FUT3 activity regardless of FUT2 activity; B, both FUT2 and FUT3 activity and C, no FUT2 activity without loss of FUT3 activity. Group-specific cut-off values were determined by Youden's index. RESULTS: The median CA19-9 values of cancer-free patients were significantly different (p<0.001) in Groups A (2.0U/ml), B (17.0U/ml), and C (37.0U/ml). Biliary malignancy patients in Groups B and C had significantly higher CA19-9 values than cancer-free patients (p<0.001). The optimal cut-off, as determined by ROC analysis, for all patients was 88.5U/ml. Optimal cut-off values in Groups A, B, and C were 4.0U/ml, 74.5U/ml, and 106.8U/ml, respectively. Use of these values improved sensitivity of CA19-9 in Groups B and C. Further, use of group-dependent cut-off values with 90% sensitivity resulted in a 42.9% reduction of false positive results. CONCLUSIONS: Use of FUT2/3 genotype-dependent cut-off values for CA19-9 improved sensitivity and reduced the number of false positive results.

RAF-targeted therapy for hepatocellular carcinoma in the regenerating liver.

BACKGROUND: Post-operative liver regeneration may contribute to tumor recurrence. There is a theoretical need for an adjuvant therapy that can suppress tumor growth without adversely affecting post-operative liver regeneration. OBJECTIVE: To evaluate the effect of RAF inhibitor Sorafenib on cell viability and proliferation of hepatoma cells and hepatocytes in vitro and in an in vivo rat model. METHODS: Cell viability, DNA synthesis, and RAF/MAPK kinase activity in the primary hepatocyte and hepatoma cell lines were investigated after Sorafenib exposure. Sequence analysis of the B-RAF gene in hepatic cells was determined. Tumor markers were compared within the rats after 70% hepatectomy with or without daily oral gavages of Sorafenib. Liver regeneration was assessed by liver function tests and proliferation markers. RESULTS: Primary hepatocytes showed higher cell viability, proliferation rate, and stronger RAF/MAPK kinase activity compared with hepatoma cell lines. The in vivo tumor volumes, size, and metastases were significantly decreased (P < 0.05) whereas no significant change in liver regeneration related to Sorafenib exposure was found (P > 0.05). B-RAF V600E mutation was not detected neither in the hepatic cells nor untransformed hepatocytes. CONCLUSIONS: The RAF targeted inhibitor can reduce tumor growth without retarding liver regeneration in this experiment.

DNA Metabarcoding for Quality Control of Basil, Oregano, and Paprika.

Herbs and spices are some of the most vulnerable products in terms of fraud and adulteration in the food sector. Although standard analytical methods are accurate for quality control of specific lead or marker compounds, they cannot accurately assess the entire species composition of many marketed products. Complementary analytical approaches are thus often used for comprehensive screening of herbs and spices. In this study we evaluate DNA metabarcoding for the identification and authentication of 62 products, containing basil, oregano, and paprika collected from different retailers and importers in Norway. Our results show varying degrees of discrepancy between the constituent species and those listed on the product labels, despite high product authenticity. We suggest the false positives result from the sensitivity of DNA metabarcoding and filtering thresholds should be integrated into protocols to reduce false positives. Our results highlight how integrating DNA metabarcoding into the toolbox of analytical methods for quality control of fresh and/or processed plant-based food can improve product quality.

DNA Metabarcoding Authentication of Ayurvedic Herbal Products on the European Market Raises Concerns of Quality and Fidelity.

Ayurveda is one of the oldest systems of medicine in the world, but the growing commercial interest in Ayurveda based products has increased the incentive for adulteration and substitution within this herbal market. Fraudulent practices such as the use of undeclared fillers and use of other species of inferior quality is driven both by the increased as well as insufficient supply capacity of especially wild plant species. Developing novel strategies to exhaustively assess and monitor both the quality of raw materials and final marketed herbal products is a challenge in herbal pharmacovigilance. Seventy-nine Ayurvedic herbal products sold as tablets, capsules, powders, and extracts were randomly purchased via e-commerce and pharmacies across Europe, and DNA metabarcoding was used to assess the ability of this method to authenticate these products. Our analysis reveals that only two out of 12 single ingredient products contained only one species as labeled, eight out of 27 multiple ingredient products contained none of the species listed on the label, and the remaining 19 products contained 1 to 5 of the species listed on the label along with many other species not specified on the label. The fidelity for single ingredient products was 67%, the overall ingredient fidelity for multi ingredient products was 21%, and for all products 24%. The low level of fidelity raises concerns about the reliability of the products, and detection of threatened species raises further concerns about illegal plant trade. The study highlights the necessity for quality control of the marketed herbal products and shows that DNA metabarcoding is an effective analytical approach to authenticate complex multi ingredient herbal products. However, effort needs to be done to standardize the protocols for DNA metabarcoding before this approach can be implemented as routine analytical approaches for plant identification, and approved for use in regulated procedures.

Genotyping strategy matters when analyzing hypervariable major histocompatibility complex-Experience from a passerine bird.

Genotyping of classical major histocompatibility complex (MHC) genes is challenging when they are hypervariable and occur in multiple copies. In this study, we used several different approaches to genotype the moderately variable MHC class I exon 3 (MHCIe3) and the highly polymorphic MHC class II exon 2 (MHCIIße2) in the bluethroat (Luscinia svecica). Two family groups (eight individuals) were sequenced in replicates at both markers using Ion Torrent technology with both a single- and a dual-indexed primer structure. Additionally, MHCIIße2 was sequenced on Illumina MiSeq. Allele calling was conducted by modifications of the pipeline developed by Sommer et al. (BMC Genomics, 14, 2013, 542) and the software AmpliSAS. While the different genotyping strategies gave largely consistent results for MHCIe3, with a maximum of eight alleles per individual, MHCIIße2 was remarkably complex with a maximum of 56 MHCIIße2 alleles called for one individual. Each genotyping strategy detected on average 50%-82% of all MHCIIße2 alleles per individual, but dropouts were largely allele-specific and consistent within families for each strategy. The discrepancies among approaches indicate PCR biases caused by the platform-specific primer tails. Further, AmpliSAS called fewer alleles than the modified Sommer pipeline. Our results demonstrate that allelic dropout is a significant problem when genotyping the hypervariable MHCIIße2. As these genotyping errors are largely nonrandom and method-specific, we caution against comparing genotypes across different genotyping strategies. Nevertheless, we conclude that high-throughput approaches provide a major advance in the challenging task of genotyping hypervariable MHC loci, even though they may not reveal the complete allelic repertoire.

Sequencing of the complete mitochondrial genome of the common raven Corvus corax (Aves: Corvidae) confirms mitogenome-wide deep lineages and a paraphyletic relationship with the Chihuahuan raven C. cryptoleucus.

Previous studies based on single mitochondrial markers have shown that the common raven (Corvus corax) consists of two highly diverged lineages that are hypothesised to have undergone speciation reversal upon secondary contact. Furthermore, common ravens are paraphyletic with respect to the Chihuahuan raven (C. cryptoleucus) based on mitochondrial DNA (mtDNA). Here we explore the causes of mtDNA paraphyly by sequencing whole mitochondrial genomes of 12 common ravens from across the Northern Hemisphere, in addition to three Chihuahuan ravens and one closely related brown-necked raven (C. ruficollis) using a long-range PCR protocol. Our raven mitogenomes ranged between 16925-16928 bp in length. GC content varied from 43.3% to 43.8% and the 13 protein coding genes, two rRNAs and 22 tRNAs followed a standard avian mitochondrial arrangement. The overall divergence between the two common raven clades was 3% (range 0.3-5.8% in 16 regions including the protein coding genes, rRNAs and the control region). Phylogenies constructed from whole mitogenomes recovered the previously found mitochondrial sister relationship between the common raven California clade and the Chihuahuan raven (overall divergence 1.1%), which strengthens the hypothesis that mtDNA paraphyly in the common raven results from speciation reversal of previously distinct Holarctic and California lineages.

The role of natural killer T cells in a mouse model with spontaneous bile duct inflammation.

Natural killer T (NKT) cells are activated by lipid antigens presented by CD1d molecules and represent a major lymphocyte subset of the liver. NODc3c4 mice spontaneously develop biliary inflammation in extra- and intrahepatic bile ducts. We demonstrated by flow cytometry that invariant NKT (iNKT) cells were more abundant in the thymus, spleen, and liver of NODc3c4 mice compared to NOD mice. iNKT cells in NODc3c4 mice displayed an activated phenotype. Further, NOD and NODCd1d-/- mice were irradiated and injected with NODc3c4 bone marrow, and injection of NODc3c4 bone marrow resulted in biliary infiltrates independently of CD1d expression in recipient mice. Activation or blocking of NKT cells with α-galactosylceramide or anti-CD1d antibody injections did not affect the biliary phenotype of NODc3c4 mice. NODc3c4.Cd1d-/- mice were generated by crossing NODCd1d-/- mice onto a NODc3c4 background. NODc3c4.Cd1d-/- and NODc3c4 mice developed the same extent of biliary disease. This study demonstrates that iNKT cells are more abundant and activated in the NODc3c4 model. The portal inflammation of NODc3c4 mice can be transferred to irradiated recipients, which suggests an immune-driven disease. Our findings imply that NKT cells can potentially participate in the biliary inflammation, but are not the primary drivers of disease in NODc3c4 mice.

The Influence of the Autoimmunity-Associated Ancestral HLA Haplotype AH8.1 on the Human Gut Microbiota: A Cross-Sectional Study.

Multiple immune-related genes are encoded in the HLA complex on chromosome 6p21. The 8.1 ancestral haplotype (AH8.1) include the classical HLA alleles HLA-B*08:01 and HLA-DRB1*03:01, and has been associated with a large number of autoimmune diseases, but the underlying mechanisms for this association are largely unknown. Given the recently established links between the gut microbiota and inflammatory diseases, we hypothesized that the AH8.1 influences the host gut microbial community composition. To study this further, healthy individuals were selected from the Norwegian Bone Marrow Donor Registry and categorized as either I. AH8.1 homozygote (n=34), II. AH8.1 heterozygote (n=38), III. Non AH8.1 heterozygote or IV. HLA-DRB1 homozygote but non AH8.1 (n=15). Bacterial DNA from stool samples were subjected to sequencing of the V3-V5 region of the 16S rRNA gene on the 454 Life Sciences platform and data analyzed using Mothur and QIIME. The results showed that the abundances of different taxa were highly variable within all pre-defined AH8.1 genotype groups. Using univariate non-parametric statistics, there were no differences regarding alpha or beta diversity between AH8.1 carriers (categories I and II) and non-carriers (categories III and IV), however four different taxa (Prevotellaceae, Clostridium XVIII, Coprococcus, Enterorhabdus) had nominally significant lower abundances in AH8.1 carriers than non-carriers. After including possible confounders in a multivariate linear regression, only the two latter genera remained significantly associated. In conclusion, the overall contribution of the AH8.1 haplotype to the variation in gut microbiota profile of stool in the present study was small.