Genetic Parameters and Genotype × Diet Interaction for Body Weight Performance and Fat in Gilthead Seabream

There has been thorough research on the genotype by diet interaction and the extent of its impact on the genetic evaluation, using a partly replaced marine animal protein on the gilthead seabream. To do that, 8356 individuals were gathered from two batches and followed different diets: a high-plant-protein diet containing 85% plant proteins and a standard commercial one containing 30% marine animal protein. During the experiment, body weight, growth and fat content were recorded. High heritability estimates were detected for the body weight performance and fat content. A small effect of genotype by diet interaction was detected in all phenotypes (presented as the genetic correlations from 0.95 to 0.97) but a medium-high ranking correlation between the breeding values for each trait was estimated (0.72-0.70). A higher expected response to selection for the body weight performance was detected using the standard commercial rather than the plant-based diet. Based on the findings, the establishment of a plant-based diet breeding strategy can be achieved provided the reduction of the cost of aquafeed is attained, though a lower genetic gain is expected.

Linkage mapping, comparative genome analysis, and QTL detection for growth in a non-model teleost, the meagre Argyrosomus regius, using ddRAD sequencing

Meagre (Argyrosomus regius), is a benthopelagic species rapidly emerging in aquaculture, due to its low food to biomass conversion rate, good fillet yield and ease of production. Tracing a species genomic background along with describing the genetic basis of important traits can greatly influence both conservation strategies and production perspectives. In this study, we employed ddRAD sequencing of 266 fish from six F1 meagre families, to construct a high-density genetic map comprising 4529 polymorphic SNP markers. The QTL mapping analysis provided a genomic appreciation for the weight trait identifying a statistically significant QTL on linkage group 15 (LG15). The comparative genomics analysis with six teleost species revealed an evolutionarily conserved karyotype structure. The synteny observed, verified the already well-known fusion events of the three-spine stickleback genome, reinforced the evidence of reduced evolutionary distance of Sciaenids with the Sparidae family, reflected the evolutionary proximity with Dicentrarchus labrax, traced several putative chromosomal rearrangements and a prominent putative fusion event in meagre’s LG17. This study presents novel elements concerning the genome evolutionary history of a non-model teleost species recently adopted in aquaculture, starts to unravel the genetic basis of the species growth-related traits, and provides a high-density genetic map as a tool that can help to further establish meagre as a valuable resource for research and production.

Partial deletion of chromosome 6p causing developmental delay and mild dysmorphisms in a child: molecular and developmental investigation and literature search

Background

The interstitial 6p22.3 deletions concern rare chromosomal events affecting numerous aspects of both physical and mental development. The syndrome is characterized by partial deletion of chromosome 6, which may arise in a number of ways.

Case presentation

We report a 2.8-year old boy presenting with developmental delay and mild dysmorphisms. High-resolution oligonucleotide microarray analysis revealed with high precision a 2.5 Mb interstitial 6p deletion in the 6p22.3 region which encompasses 13 genes.

Conclusions

Identification and in-depth analysis of cases presenting with mild features of the syndrome will sharpen our understanding of the genetic spectrum of the 6p22.3 deletion.

Breeding strategies for animal resilience to weather variation in meat sheep

BACKGROUND

The alteration in weather patterns expected due to climate change will affect farm animal performance, probably resulting in lower quantity and quality of available products. A potential mitigation strategy would be to breed selected animals for enhanced resilience to climate change. In this context, resilience would reflect stable animal performance in spite of weather variation. The objectives of this study were to (i) derive and characterise novel animal resilience phenotypes, (ii) investigate their genetic profiles and (iii) assess the impact of integrating them in breeding strategies for genetic improvement in meat sheep.

RESULTS

Random regression models were used to jointly analyse live body weight measured in different time points throughout the growth phases of 4469 Scottish Blackface sheep and weather variables during the same period to derive novel resilience phenotypes. The genetic analysis of these phenotypes revealed significant genetic variance and heritability, and an antagonistic genetic correlation with some animal performance traits. Simulated breeding strategies demonstrated that a relative emphasis of 10% on resilience compared to other traits would enhance performance stability against weather volatility without compromising animal growth.

CONCLUSIONS

Novel resilience traits exhibited sufficient genetic variation to be amenable to genetic improvement with selective breeding and are recommended to be included in future breeding goals.

QTL for Stress and Disease Resistance in European Sea Bass, Dicentrarhus labrax L

There is a growing interest in selective breeding in European sea bass (Dicentrarchus labrax), especially regarding family selection based on growth performance. In particular, quantitative trait loci (QTL) identification in sea bass enhances the application of marker-assisted breeding for the genetic improvement of the production traits. The aims of the study were to identify potential QTL affecting stress and immunological indicators, body weight, and mortality after vibriosis injection in sea bass as well as to estimate heritability and genetic/phenotypic correlations for the aforementioned traits. To this end, stress test was performed on 960 offspring and a sub-group of them (420) was selected to explore the mortality after vibrio injection. Selective genotyping was performed in 620 offspring for 35 microsatellite markers and distributed into 6 linkage groups. The length of the genetic linkage map was 283.6 cM and the mean distance between the markers was 8.1 cM. QTL affecting body weight in three different growth periods detected on linkage groups LG1, LG4, LG6, and LG14. A QTL associated with weight in early growth stages (290-306 days post-hatching) was also identified on LG3. QTL analysis confirmed the existence of QTL affecting cortisol levels, on LG3 and LG14. Moreover, new QTL affecting only cortisol and glucose levels were detected on LG1 and LG23. No QTL affecting hormonal or biochemical marks was found on LG4 and LG6. Heritability of cortisol, lysozyme levels, and mortality were high (0.36, 0.55, and 0.38, respectively).

A Novel KCNJ11 Mutation Associated with Transient Neonatal Diabetes

Neonatal diabetes mellitus (NDM) is a rare type of monogenic diabetes that presents in the first 6 months of life. Activating mutations in the KCNJ11 gene encoding for the Kir6.2 subunit of the ATP-sensitive potassium (K_ATP ) channel can lead to transient NDM (TNDM) or to permanent NDM (PNDM). A female infant presented on the 22^nd day of life with severe hyperglycemia and ketoacidosis (glucose: 907mg/dL, blood gas pH: 6.84, HCO₃: 6 mmol/L). She was initially managed with intravenous (IV) fluids and IV insulin. Ketoacidosis resolved within 48 hours and she was started on subcutaneous insulin injections with intermediate acting insulin NPH twice daily requiring initially 0.75-1.35 IU/kg/d. Pre-prandial C-peptide levels were 0.51 ng/mL (normal: 1.77-4.68). Insulin requirements were gradually reduced and insulin administration was discontinued at the age of 10 months with subsequent normal glucose and HbA1c levels. C-peptide levels normalized (pre-prandial: 1.6 ng/mL, postprandial: 2 ng/mL). Genetic analysis identified a novel missense mutation (p.Pro254Gln) in the KCNJ11 gene. We report a novel KCNJ11 mutation in a patient who presented in the first month of life with a phenotype of NDM that subsided at the age of 10 months. It is likely that the novel p.P254Q mutation results in mild impairment of the K_ATP channel function leading to TNDM.