Fumigant Toxicity of Essential Oils Against Frankliniella occidentalis, F. insularis (Thysanoptera: Thripidae), and Solanum lycopersicum (Solanceae) as Affected by Polymer Release and Adjuvants

M.S

Analysis of the meiotic segregation in intergeneric hybrids of tilapias

Tilapia species exhibit a large ecological diversity and an important propensity to interspecific hybridisation. This has been shown in the wild and used in aquaculture. However, despite its important evolutionary implications, few studies have focused on the analysis of hybrid genomes and their meiotic segregation. Intergeneric hybrids between Oreochromis niloticus and Sarotherodon melanotheron, two species highly differentiated genetically, ecologically, and behaviourally, were produced experimentally. The meiotic segregation of these hybrids was analysed in reciprocal second generation hybrid (F2) and backcross families and compared to the meiosis of both parental species, using a panel of 30 microsatellite markers. Hybrid meioses showed segregation in accordance to Mendelian expectations, independent from sex and the direction of crosses. In addition, we observed a conservation of linkage associations between markers, which suggests a relatively similar genome structure between the two parental species and the apparent lack of postzygotic incompatibility, despite their important divergence. These results provide genomics insights into the relative ease of hybridisation within cichlid species when prezygotic barriers are disrupted. Overall our results support the hypothesis that hybridisation may have played an important role in the evolution and diversification of cichlids

Special features of RAD Sequencing data:implications for genotyping

Restriction site-associated DNA Sequencing (RAD-Seq) is an economical and efficient method for SNP discovery and genotyping. As with other sequencing-by-synthesis methods, RAD-Seq produces stochastic count data and requires sensitive analysis to develop or genotype markers accurately. We show that there are several sources of bias specific to RAD-Seq that are not explicitly addressed by current genotyping tools, namely restriction fragment bias, restriction site heterozygosity and PCR GC content bias. We explore the performance of existing analysis tools given these biases and discuss approaches to limiting or handling biases in RAD-Seq data. While these biases need to be taken seriously, we believe RAD loci affected by them can be excluded or processed with relative ease in most cases and that most RAD loci will be accurately genotyped by existing tools

Microsatellites Cross-Species Amplification across Some African Cichlids

The transfer of the genomic resources developed in the Nile tilapia, Oreochromis niloticus, to other Tilapiines sensu lato and African cichlid would provide new possibilities to study this amazing group from genetics, ecology, evolution, aquaculture, and conservation point of view. We tested the cross-species amplification of 32 O. niloticus microsatellite markers in a panel of 15 species from 5 different African cichlid tribes: Oreochromines (Oreochromis, Sarotherodon), Boreotilapiines (Tilapia), Chromidotilapines, Hemichromines, and Haplochromines. Amplification was successfully observed for 29 markers (91%), with a frequency of polymorphic (P95) loci per species around 70%. The mean number of alleles per locus and species was 3.2 but varied from 3.7 within Oreochromis species to 1.6 within the nontilapia species. The high level of cross-species amplification and polymorphism of the microsatellite markers tested in this study provides powerful tools for a wide range of molecular genetic studies within tilapia species as well as for other African cichlids

Identifying the larva of the fan mussel, Atrina fragilis (Pennant, 1777) (Pinnidae)

This work was funded by the Scottish Government project SP004 and a MSS PhD studentship to DS. Many thanks are due to the Crews of the MV Alba na Mara (MSS), RV Sir John Murray (SEPA) and the MV Lochnevis (Caledonian Macbrayne) for facilitating sample collection, John Dunn for assistance with the manufacture and installation of the ferry sampler, Marian Thomson and other staff at the University of Edinburgh for laboratory assistance, Anastasia Imsiridou, Sofia Galinou-Mitsoudi and Vassilis Katsares of the Greek Department of Fisheries and Aquaculture Technology for supplying reference adult A. fragilis DNA, Pablo Diaz and staff at the University of Aberdeen microscopy department for assistance with SEM analysis, the National Museum of Wales for allowing reproduction of the juvenile A. fragilis image, Keith Hiscock and Eve Southward of Plymouth Marine Laboratory for historical information on the identification of A. fragilis larvae, Colin McAlister and the staff of the Fishery offices in Mallaig and Fraserburgh for assistance in the transport of zooplankton samples and materials, and the British Oceanographic Data Centre for supplying data on the UK Tidal Gauge Network. Comments from Associate Editor Simon Cragg and two anonymous reviewers were greatly appreciated for improving the manuscriptPeer reviewedPostprintPostprintPostprintPostprintPostprintPostprintPostprintPostprintPostprin

A new SNP-based vision of the genetics of sex determination in European sea bass (Dicentrarchus labrax)

Background: European sea bass (Dicentrarchus labrax) is one of the most important farmed species in Mediterranean aquaculture. The observed sexual growth and maturity dimorphism in favour of females adds value towards deciphering the sex determination system of this species. Current knowledge indicates the existence of a polygenic sex determining determination system that interacts with temperature. This was explored by restriction-site associated DNA (RAD) marker analysis in a test panel of 175 offspring that originated from a factorial cross between two dams and four sires from a single full-sib family. Results: The first high-density single nucleotide polymorphism (SNP) based linkage map for sea bass was constructed, consisting of 6706 SNPs on 24 linkage groups. Indications for putative sex-determining QTL (quantitative trait loci) that were significant at the genome-wide threshold were detected on linkage groups 6, 11 and 18 to 21, although a genome-wide association study (GWAS) did not identify individual significant SNPs at a genome-wide threshold. A preliminary genomic prediction approach that tested the efficiency of SNP-based selection for female sea bass showed a slight advantage compared to traditional pedigree-based selection. However, when the same models were tested on the same animals for selection for greater length, a clear advantage of the SNP-based selection was observed. Conclusions: Overall, the results of this study provide additional support to the polygenic sex determination hypothesis in sea bass. In addition, identification of sex-ratio QTL may provide new opportunities for sex-ratio control in sea bass

Mapping and Validation of the Major Sex-Determining Region in Nile Tilapia (Oreochromis niloticus L.) Using RAD Sequencing

Sex in Oreochromis niloticus (Nile tilapia) is principally determined by an XX/XY locus but other genetic and environmental factors also influence sex ratio. Restriction Associated DNA (RAD) sequencing was used in two families derived from crossing XY males with females from an isogenic clonal line, in order to identify Single Nucleotide Polymorphisms (SNPs) and map the sex-determining region(s). We constructed a linkage map with 3,802 SNPs, which corresponded to 3,280 informative markers, and identified a major sex-determining region on linkage group 1, explaining nearly 96% of the phenotypic variance. This sex-determining region was mapped in a 2 cM interval, corresponding to approximately 1.2 Mb in the O. niloticus draft genome. In order to validate this, a diverse family (4 families; 96 individuals in total) and population (40 broodstock individuals) test panel were genotyped for five of the SNPs showing the highest association with phenotypic sex. From the expanded data set, SNPs Oni23063 and Oni28137 showed the highest association, which persisted both in the case of family and population data. Across the entire dataset all females were found to be homozygous for these two SNPs. Males were heterozygous, with the exception of five individuals in the population and two in the family dataset. These fish possessed the homozygous genotype expected of females. Progeny sex ratios (over 95% females) from two of the males with the "female" genotype indicated that they were neomales (XX males). Sex reversal induced by elevated temperature during sexual differentiation also resulted in phenotypic males with the "female" genotype. This study narrows down the region containing the main sex-determining locus, and provides genetic markers tightly linked to this locus, with an association that persisted across the population. These markers will be of use in refining the production of genetically male O. niloticus for aquaculture

Heavy metals and aluminium intake from stored canned tomato, sardines and tuna in Algeria

This study assessed heavy metals intake and their impacts on healthcare in Algeria. Peculiar attention was given to heavy metals found in largely consumed canned foods in Algeria such as double concentrated tomato, tuna crumbs and sardines. Chemical analyses of the metal and aluminium containers (foil, tray) were performed by X-Ray Fluorescence (XRF) and EDS spectrometry (Energy Dispersive Spectrometry). The determination of the trace metal content in canned food (element metal trace EMT) was achieved by Atomic Absorption Spectrometry (AAS). The approach proposed in this study aimed to highlight the interaction of the product and packaging material, and thus to identify and quantify heavy metals traces that were able to undergo specific or overall migration to food. The morphology of the contact surface food / packaging was observed by Scanning Electron Microscope (SEM) and showed a slight degradation of the base metal (Black Iron).  There was an obvious increase in EMTs during tuna, sardines and tomatoes storage and artificial aging. A special interest was given to cooking modes using aluminium foil and trays.  ‎‎The respective dosages of aluminium, in baked food (fresh tuna) were obtained. Specific Aluminium migration was noticed and was strong for the flame cooking mode

Genetic dissection of MHC-associated susceptibility to Lepeophtheirus salmonis in Atlantic salmon

Background: Genetic variation has been shown to play a significant role in determining susceptibility to the salmon louse, Lepeophtheirus salmonis. However, the mechanisms involved in differential response to infection remain poorly understood. Recent findings in Atlantic salmon (Salmo salar) have provided evidence for a potential link between marker variation at the major histocompatibility complex (MHC) and differences in lice abundance among infected siblings, suggesting that MHC genes can modulate susceptibility to the parasite. In this study, we used quantitative trait locus (QTL) analysis to test the effect of genomic regions linked to MHC class I and II on linkage groups (LG) 15 and 6, respectively. Results: Significant QTL effects were detected on both LG 6 and LG 15 in sire-based analysis but the QTL regions remained unresolved due to a lack of recombination between markers. In dam-based analysis, a significant QTL was identified on LG 6, which accounted for 12.9% of within-family variance in lice abundance. However, the QTL was located at the opposite end of DAA, with no significant overlap with the MHC class II region. Interestingly, QTL modelling also revealed evidence of sex-linked differences in lice abundance, indicating that males and females may have different susceptibility to infection. Conclusion: Overall, QTL analysis provided relatively weak support for a proximal effect of classical MHC regions on lice abundance, which can partly be explained by linkage to other genes controlling susceptibility to L. salmonis on the same chromosom

Benefits and pitfalls of captive conservation genetic management: evaluating diversity in scimitar-horned oryx to support reintroduction planning

The reintroduction of the scimitar-horned oryx to Chad is a multi-disciplinary endeavour, planned and implemented over the past decade, utilizing a wide range of conservation science applications to maximise the chances of long-term population sustainability. The principle of incorporating genetic diversity information into founder selection for species reintroductions is widely recognized; however, in practice, a full assessment of available ex-situ genetic variation is rarely attempted prior to identifying individuals for release.In this study we present the results of over ten years of research analyzing and interpreting the genetic diversity present in the key source populations for the Chad scimitar-horned oryx reintroduction. Three empirical genetic datasets (mitochondrial DNA sequence, nuclear DNA microsatellite and SNP markers) comprising over 500 individuals sampled from public and private institutions were analysed, accompanied by simulation studies to address applied questions relating to management of the reintroduction.The results strongly demonstrate the importance of conservation genetic analysis in ensuring that founders represent the greatest breadth of evolutionary diversity available. The inclusion of both intensively and lightly managed collections allowed us to bridge the gap between studbook and group managed populations, enabling the inclusion of individuals from populations that lack historic data on their origins, but which may hold unique diversity of significant conservation value. Importantly, however, our study also reveals the potential risks of applying standard population genetic approaches to multiple captive populations, for which small founder sizes are likely to strongly bias results, with potentially serious consequences for the genetic management of conservation breeding programmes