Does asymmetric gene flow among matrilines maintain the evolutionary potential of the European eel?

Using evolutionary theory to predict the dynamics of populations is one of the aims of evolutionary conservation. In endangered species, with geographic range extending over continuous areas, the predictive capacity of evolutionary-based conservation measures greatly depends on the accurate identification of reproductive units. The endangered European eel (Anguilla anguilla) is a highly migratory fish species with declining population due to a steep recruitment collapse in the beginning of the 1980s. Despite punctual observations of genetic structure, the population is viewed as a single panmictic reproductive unit. To understand the possible origin of the detected structure in this species, we used a combination of mitochondrial and nuclear loci to indirectly evaluate the possible existence of cryptic demes. For that, 403 glass eels from three successive cohorts arriving at a single location were screened for phenotypic and genetic diversity, while controlling for possible geographic variation. Over the 3 years of sampling, we consistently identified three major matrilines which we hypothesized to represent demes. Interestingly, not only we found that population genetic models support the existence of those matriline-driven demes over a completely panmictic mode of reproduction, but also we found evidence for asymmetric gene flow amongst those demes. We uphold the suggestion that the detection of demes related to those matrilines reflect a fragmented spawning ground, a conceptually plausible consequence of the low abundance that the European eel has been experiencing for three decades. Furthermore, we suggest that this cryptic organization may contribute to the maintenance of the adaptive potential of the species

Genomics in eels — towards aquaculture and biology

Animal science

First draft genome sequence of the Japanese eel, Anguilla japonica

The Japanese eel is a much appreciated research object and very important for Asian aquaculture; however, its genomic resources are still limited. We have used a streamlined bioinformatics pipeline for the de novo assembly of the genome sequence of the Japanese eel from raw Illumina sequence reads. The total assembled genome has a size of 1.15 Gbp, which is divided over 323,776 scaffolds with an N50 of 52,849 bp, a minimum scaffold size of 200 bp and a maximum scaffold size of 1.14 Mbp. Direct comparison of a representative set of scaffolds revealed that all the Hox genes and their intergenic distances are almost perfectly conserved between the European and the Japanese eel. The first draft genome sequence of an organism strongly catalyzes research progress in multiple fields. Therefore, the Japanese eel genome sequence will provide a rich resource of data for all scientists working on this important fish species.Microbial Biotechnolog

Diagnostic test accuracy of ultrasonography for synovitis in rheumatoid arthritis: systematic review and meta-analysis

Objective. To evaluate diagnostic test accuracy of US compared with MRI for the detection of synovitis in RA patients. Methods. A systematic literature search was performed in the PubMed, EMBASE, Cochrane Library and Web of Science Core Collection databases. Studies evaluating the diagnostic test accuracy of US for synovitis detected by MRI as the reference standard for wrist, MCP, PIP and knee joints were included. To assess the overall accuracy, we calculated the diagnostic odds ratio using a DerSimonian–Laird random effects model and the area under the curve (AUC) for the hierarchical summary receiver operating characteristics using Holling’s proportional hazards models. The summary estimate of the sensitivity and specificity were obtained using the bivariate model. Results. Fourteen of 601 identified articles were included in the review. The diagnostic odds ratio was 11.6 (95% CI 5.6, 24; I2 = 0%), 28 (95% CI 12, 66; I2 = 11%), 23 (95% CI 6.5, 84; I2 = 19%) and 5.3 (95% CI 0.60, 48; I2 = 0%) and the AUC was 0.81, 0.91, 0.91 and 0.61 for wrist, MCP, PIP and knee joints, respectively. The summary estimates of sensitivity and specificity were 0.73 (95% CI 0.51, 0.87)/0.78 (95% CI 0.46, 0.94), 0.64 (95% CI 0.43, 0.81)/0.93 (95% CI 0.88, 0.97), 0.71 (95% CI 0.33, 0.93)/0.94 (95% CI 0.89, 0.97) and 0.91 (95% CI 0.56, 0.99)/0.60 (95% CI 0.20, 0.90) for wrist, MCP, PIP and knee joints, respectively. Conclusion. US is a valid and reproducible technique for detecting synovitis in the wrist and finger joints. It may be considered for routine use as part of the standard diagnostic tools in RA

The clinical utility of molecular diagnostic testing for primary immune deficiency disorders: a case based review

Primary immune deficiency disorders (PIDs) are a group of diseases associated with a genetic predisposition to recurrent infections, malignancy, autoimmunity and allergy. The molecular basis of many of these disorders has been identified in the last two decades. Most are inherited as single gene defects. Identifying the underlying genetic defect plays a critical role in patient management including diagnosis, family studies, prognostic information, prenatal diagnosis and is useful in defining new diseases. In this review we outline the clinical utility of molecular testing for these disorders using clinical cases referred to Auckland Hospital. It is written from the perspective of a laboratory offering a wide range of tests for a small developed country

Oceanic spawning ecology of freshwater eels in the western North Pacific

The natural reproductive ecology of freshwater eels remained a mystery even after some of their offshore spawning areas were discovered approximately 100 years ago. In this study, we investigate the spawning ecology of freshwater eels for the first time using collections of eggs, larvae and spawning-condition adults of two species in their shared spawning area in the Pacific. Ovaries of female Japanese eel and giant mottled eel adults were polycyclic, suggesting that freshwater eels can spawn more than once during a spawning season. The first collection of Japanese eel eggs near the West Mariana Ridge where adults and newly hatched larvae were also caught shows that spawning occurs during new moon periods throughout the spawning season. The depths where adults and newly hatched larvae were captured indicate that spawning occurs in shallower layers of 150–200 m and not at great depths. This type of spawning may reduce predation and facilitate reproductive success