Myostatin Mutation in Japanese Quail Increased Egg Size but Reduced Eggshell Thickness and Strength

Abstract

Recently developed myostatin (MSTN) mutant quail and chickens demonstrated similar effects of MSTN on muscle and fat developments between avian and mammalian species. However, the effect of MSTN mutation on the quality of eggshells, an important avian specific characteristic, has not yet been investigated although egg production traits of mutant quail have been studied. In this study, several parameters for eggshell quality, including eggshell size, eggshell weight, eggshell breaking strength (EBS), and eggshell thickness, were all compared between MSTN mutant and wild-type (WT) eggs. MSTN mutant eggs had greater height and width along with heavier eggshell weight compared to WT eggs, which shows proportional improvement in egg size as affected by the MSTN mutation. However, EBS and eggshell thickness were decreased in mutant eggs compared to WT eggs. In addition, the palisade layer, the thickest and most important layer for the strength of an eggshell, was also decreased without a change in the number of vesicular holes. These data indicated that decreases in the thickness of the eggshell and the palisade layer would be a main factor contributing to a lower EBS in mutant eggs. MSTN mutant quail provide a useful model to better understand the function of MSTN on avian uterine cell development and eggshell biomineralization.

Myostatin gene role in regulating traits of poultry species for potential industrial applications

“…The effect of MSTN mutation on egg production traits was further confirmed in MSTN mutant quail [ 45 ], after an SNP in the MSTN gene, G2283A, was reported to be associated with body weight, age of first egg laying, and egg numbers [ 66 ]. The eggs of MSTN mutant quail were bigger and heavier compared to those of WT quail [ 45 , 46 ]. Because the positive association between hens’ body weight and their egg size was reported in chickens [ 67 , 68 ], heavier body weight of the MSTN mutant quail might have an indirect effect on bigger egg size in the mutant group compared to the WT group.…”

“…Like egg size, eggshell strength is also positively associated with avian body weight [ 72 ]. However, eggshell strength of the mutant eggs, analyzed by breaking strength, was lower compared to that of WT eggs, mainly due to decreased eggshell thickness [ 46 ]. Reduction in the thickness of the palisade layer in the mutant group played a major role in making the eggshell thinner and weaker than the WT group [ 46 ], because a palisade layer is the thickest and major calcified layer in the eggshell [ 73 ].…”

“…However, eggshell strength of the mutant eggs, analyzed by breaking strength, was lower compared to that of WT eggs, mainly due to decreased eggshell thickness [ 46 ]. Reduction in the thickness of the palisade layer in the mutant group played a major role in making the eggshell thinner and weaker than the WT group [ 46 ], because a palisade layer is the thickest and major calcified layer in the eggshell [ 73 ]. In addition, a decreased expression level of MSTN in the uterus, the specific region of avian oviduct for eggshell formation, in egg-laying hens compared to non-laying hens at the same age further supports a potential regulatory role of the MSTN gene in eggshell formation [ 74 ].…”

“…In addition to the increased muscle mass, decreased fat deposition is another major phenotypic change caused by the MSTN mutation in various farm animals [14,15,53,54], suggesting an additional benefit of the MSTN mutation for production of leaner meat. Lean meat is not only favorable for consumers who are looking for healthier foods, but Body weight [39,40]; Muscle [40] Quail Lentivirus-mediated overexpression Overexpression of MSTN-B form Muscle [41] Quail Adenovirus-mediated genome editing 3 nucleotide deletion mutation by CRISPR/Cas9 Body weight, muscle and fat [19]; Feed efficiency and fat [42]; Bone size and quality [43,44]; Egg production [45]; Eggshell quality [46] Chicken PGC-mediated genome editing 14 nucleotide deletion mutation & multiple indel mutations by CRISPR/Cas9…”

Research Note: Growth promoting potential in Mstn mutant quail dependent and independent of increased egg size

“…In our previous studies, Mstn mutant quail exhibited delayed egg laying time and produced fewer numbers of eggs during an actively laying period ( Lee et al, 2021 ). In addition, eggs from Mstn mutant quail are larger in size and a heavier egg weight than wild-type ( WT ) eggs ( Lee et al, 2022 ), but have similar fertility and hatchability as wild-type eggs ( Lee et al, 2021 ). However, there is a lack of further investigation focusing on the association between egg weights from Mstn mutants and body growth.…”