Melanocortin-4 Receptor and Lipocalin 2 Gene Variants in Spanish Children with Abdominal Obesity: Effects on BMI-SDS After a Lifestyle Intervention

Mutations leading to a reduced function of the melanocortin-4 receptor (MC4R) exert a major gene effect on extreme obesity. Recently it was shown that the bone derived hormone lipocalin 2 (LCN2) binds to the MC4R and activates a MC4R dependent anorexigenic pathway. We identified mutations in both genes and screened the effects of MC4R and LCN2 mutations on eating behavior and weight change after a lifestyle intervention. One hundred and twelve children (11.24 ± 2.6 years, BMI-SDS 2.91 ± 1.07) with abdominal obesity participated in a lifestyle intervention. MC4R and LCN2 coding regions were screened by Sanger sequencing. Eating behavior was assessed at baseline with the Children Eating Behavior Questionnaire (CEBQ). We detected three previously described non-synonymous MC4R variants (Glu42Lys, Thr150Ile, and Arg305Gln) and one non-synonymous polymorphism (Ile251Leu). Regarding LCN2, one known non-synonymous variant (Thr124Met) was detected. Eating behavior was described in carriers of the MC4R and LCN2 mutation and in non-carriers. MC4R and LCN2 mutations were detected in 2.42% and 0.84%, respectively, of Spanish children with abdominal obesity. A number of subjects with functional mutation variants in MC4R and LCN2 were able to achieve a reduction in BMI-SDS after a lifestyle intervention.

Determining the inheritance of agronomic traits in chili pepper

ABSTRACT The Capsicum genus is widely studied in many countries but most of research focuses on C. annuum. Although its importance as potential genetic resource for breeding to disease resistance and fruit quality, studies on genetics and breeding in C. baccatum var. pendulum are still scarce and it still remains as an underexploited crop. This paper aimed to study the inheritance of agronomic characteristics, to estimate the genetic parameters for seven agronomic traits in C. baccatum var. pendulum, using generation mean analysis and to verify the existence of major genes and polygenes with additive and non-additive effects, using the method of maximum likelihood with the aid of Monogen software. The agronomic traits evaluated were: number of fruits per plant (NFP); average fruit mass per plant (AFM); fruit length (FRL); fruit diameter (FRD); fruit pulp thickness (FPT); soluble solids content (SSC) and fruit dry mass (FDM). There was a significant difference among generations (P1, P2, F1, F2, BC1 and BC2) for all traits evaluated. Narrow sense heritability estimates ranged from 45% for NFP to 75% for FRD. By estimating the average degree of dominance (ADD), we found that partial dominance is the gene action involved in the genetic control for FRL and FRD, while additive effect was observed for NFP, FPT and SSC, complete dominance for FDM and overdominance for AFM. The additive-dominant model was sufficient to explain the results obtained for all evaluated traits. Maximum likelihood method identified the existence of polygenes with additive and dominance effects in SSC, FPT and FDM. Major gene effect was identified for FRL and NFP characteristics. The results indicated the complexity of the inheritance of these traits with the presence of major gene involved.

Inheritance of resistance to papaya ringspot virus-watermelon strain (PRSV-W) in 'Whitaker' summer squash line

The objective of this work was to study the genetic control of the PRSV-W (Papaya Ringspot Virus - Watermelon Strain) resistance in Cucurbita pepo 'Whitaker' line. Plants of parental lines Whitaker (resistant) and Caserta (susceptible), and of the generations F1, F2, BC11 and BC12 were evaluated for their reactions to PRSV-W. Caserta plants showed severe mosaic symptoms, while Whitaker grew vigorously and remained almost totally symptom-free. Most of the F1, F2 and backcross plants also presented severe mosaic symptoms. Data were used to test a hypothesis of monogenic inheritance under different presumed degrees of dominance, and genetic models were tested using maximum likelihood tests of genetic control. Broad-sense heritability was of 0.57 for the first evaluation. Resistance to PRSV-W in C. pepo 'Whitaker' is due to a major gene effect summed to polygenic effects.

A genetic analysis of parasite resistance traits in a tropically adapted line of Bos taurus

For cattle raised in tropical and subtropical environments, production can be limited by the susceptibility of many breeds to parasites. Chemical control, coupled with the use of breeds with higher levels of resistance to parasites, allows beef production to be a viable industry, but at a cost. The Hereford Shorthorn (HS) line of beef cattle at Rockhampton has been used extensively to study genetic aspects of parasite resistance. The hypothesis that a gene with a large effect on resistance to cattle ticks is segregating in this line of cattle has been raised in the past, and is considered again here, with the benefit of data recorded up to the late 1990s. A model in which no major gene effect is fitted provides a satisfactory fit to the data, providing little evidence in support of the segregation of major genes for resistance to either ticks or worms in the HS line. This conclusion is supported by the lack of animals of extreme resistance in later generations, an unlikely result if key animals are assumed to be homozygous in earlier generations.

Detection of a major gene for litter size in Thoka Cheviot sheep using Bayesian segregation analyses

Segregation analyses were applied to data from an experimental sheep flock to investigate the presence of a major gene affecting litter size. The data set contained 14 years of litter size data, with up to five parities per ewe, from Cheviot sheep carrying the putative Thoka fecundity gene from Icelandic sheep. Segregation analyses were performed using a Markov chain Monte Carlo method implemented using Gibbs sampling. Uniform priors were initially used for estimating variance components, the gene effect and fixed effects in the data. Genotypes in the base generation were assumed known based on the use of the imported Icelandic donor semen from the founder rams. The use of alternative priors (naïve and inverse-gamma distributions) for the variance components did not significantly affect the results, demonstrating the data to be sufficiently powerful for the analyses used. Segregation analyses detected a major gene for litter size in the Thoka Cheviot flock increasing litter size by 0·70 lambs per ewe lambing for a single copy of the gene. When the analysis was repeated without fixing the genotypes in the base population, the analyses predicted a different genotype than that previously used for one of the founder rams and suggested the major gene to be segregating in the Cheviot founder animals prior to the introduction of the Thoka rams. A liability threshold analysis was also applied to the data. As identified in other studies, the threshold analysis overestimated the heritability, but the estimated major gene effect was not significantly different from other analyses. The results confirm the segregation of the Thoka gene in a Cheviot flock and highlight the statistical method as a useful tool for identifying carrier animals to be used for future matings.