Feed competition reduces heritable variation for body weight in Litopenaeus vannamei.

BACKGROUND: Competition is a common social interaction among shrimp and depending on its intensity, it can affect heritable variation and response to selection. Little is known about the variance of indirect genetic effects (IGE) under competitive and non-competitive conditions in shrimp. In this study, we used extended mixed linear models to estimate genetic parameters for the direct genetic effect (DGE) and IGE on body weight in Litopenaeus vannamei raised under ad libitum (AF, non-competitive environment) and restricted (RF, competitive environment) feeding regimes. RESULTS: Estimates of heritabilities for body weight obtained with a traditional animal model (i.e. without accounting for IGE) were 0.11 ± 0.09 under AF and 0.25 ± 0.11 under RF. With extended animal models that accounted for IGE, the corresponding estimates for body weight were 0.07 ± 0.08 and 0.34 ± 0.11. Thus, heritabilities were higher under the RF regime than under the AF regime, regardless of whether IGE was accounted for or not. The log-likelihood ratio test revealed significant IGE under the RF regime. Although estimates of indirect genetic variance were low (0.0023 ± 0.0013 for AF and 0.0028 ± 0.0012 for RF), they contributed substantially to the total heritable variance: 66.8% for AF and 692.2% for RF. The total heritable variance was smaller under the RF regime (0.7 ± 1.3) than under the AF regime (5.8 ± 2.6) because of the high contribution of the negative covariance between DGE and IGE (- 7.03). Estimates of the correlation between DGE and IGE were 0.32 ± 0.47 under AF and - 0.93 ± 0.15 under RF, those of DGE and IGE for body weight between both regimes were 0.94 ± 0.07 and 0.67 ± 0.20, respectively, and those of IGE for body weight with DGE for survival were - 0.12 ± 0.22 under AF and - 0.58 ± 0.20 under RF. CONCLUSIONS: These results indicate that strong competitive interactions occurred under the RF regime in L. vannamei. Significant reranking and variation in IGE of individuals were observed between the two feeding regimes. Strong competitive interactions reduced the total heritable variation for body weight when food was restricted. These results indicate that the extent of competition among L. vannamei depends on the feeding regime applied and that this competition affects the genetic basis of body weight.

Plasma exchange therapy for familial chylomicronemia syndrome in infant: A case report.

INTRODUCTION: Familial chylomicronemia syndrome (FCS) is a rare genetic disease. FCS usually manifests by the age of 10 years, and 25% of cases of FCS occur during infancy. Here we present a case of FCS in a male infant and summarize our experiences on the diagnosis and therapy of this case. PATIENT CONCERNS: A male infant aged 1 month and 8 days had recurrent hematochezia and hyperchylomicronemia. DIAGNOSIS: FCS based on symptoms and genetic test. INTERVENTIONS: Plasma exchange therapy. OUTCOMES: His development was normal with a good spirit and satisfactory weight gain, and no hematochezia occurred again. CONCLUSION: Genetic test is important for accurate diagnosis of FCS, and we identified a new mutation of lipoprotein lipase gene c.88C>A which conformed to autosomal recessive inheritance. Plasma exchange therapy can be applied to infants with FCS with low risk and good outcomes.

Integrative phenotypic and gene expression data identify myostatin as a muscle growth inhibitor in Chinese shrimp Fenneropenaeus chinensis.

Growth traits, largely determined by muscle growth, are the most critical economic traits in shrimp breeding. Myostatin (Mstn) is a conserved inhibitor of muscle growth in vertebrates, but until now solid evidence supporting a similar function of Mstn in invertebrates has been lacking. In the present study, we examined the Mstn expression along with growth trait data in a Fenneropenaeus chinensis population, to establish a potential correlation between Mstn and growth. The heritabilities of FcMstn expression, body weight at 190 days of culture, body weight and length at 230 days of culture, and average daily gain were estimated using 773 individuals and a thirteen-generation pedigree. The results showed FcMstn expression was negatively correlated with the growth traits, and the mean FcMstn expression in females was significantly lower than that of males, indicating Mstn negatively regulates muscle growth in shrimp, and its lower expression may underscore the faster growth of females. Low heritabilities were detected for FcMstn expression, suggesting that the expression of Mstn might be heritable in shrimp. These results provide strong support for a growth inhibitory function of Mstn in F. chinensis, and suggest a potential method for selective breeding of this species without substantial experimental resources and labor force.