a NutriGenomics Laboratory, Department of Poultry Science , University of Georgia , Athens , GA , USA.
b Department of Pathology, College of Veterinary Medicine , University of Georgia , Athens , GA , USA.
Anim Biotechnol. 2019 Apr;30(2):175-179. doi: 10.1080/10495398.2018.1461634. Epub 2018 Apr 30.
Cysteine is a nonessential amino acid in poultry nutrition. Poultry diets are deficient in cysteine, but the bird's cysteine need is met through the transsulfuration pathway (TSP) where homocysteine is converted to cysteine: a process catalyzed by cystathionine β-synthase (CBS) and cystathionine γ-lyase (CTH). Cysteine is also a major component of keratinized protein found in feathers, but the extent to which cysteine is involved in feather and skin development in poultry is unknown. We randomly assigned chicks to control and treatment (control diet plus 100 mg/kg body weight of propargylglycine which is an inhibitor of CTH) diets. The thickness of skin layers, primary feather follicle parameters, growth, and mRNA expression of CBS and CTH were measured. Inhibition of TSP corresponded with the upregulation of liver mRNA of both CBS and CTH and reduction in growth from 35 to 40 days of age. The epidermis thickness, feather follicle length, and diameter were reduced from 10 to 40 days of age. Incorporation of cysteine into keratinized protein may be more sensitive to the level of available cysteine than into nonkeratinized proteins. Thus, disruption of the TSP could affect the thermoregulatory ability of the bird.
半胱氨酸是禽类营养中的一种非必需氨基酸。禽类日粮中半胱氨酸含量不足,但禽类的半胱氨酸需求可以通过转硫途径(TSP)得到满足,其中同型半胱氨酸转化为半胱氨酸:这一过程由胱硫醚 β-合酶(CBS)和胱硫醚 γ-裂合酶(CTH)催化。半胱氨酸也是羽毛中角蛋白的主要成分,但半胱氨酸在禽类羽毛和皮肤发育中的参与程度尚不清楚。我们将小鸡随机分配到对照组和治疗组(对照饮食加 100mg/kg 体重的丙炔甘氨酸,这是 CTH 的抑制剂)饮食中。测量了皮肤层厚度、初级羽毛滤泡参数、生长和 CBS 和 CTH 的 mRNA 表达。TSP 的抑制与肝脏中 CBS 和 CTH 的 mRNA 上调以及 35 至 40 日龄生长的减少相对应。从 10 到 40 日龄,表皮厚度、羽毛滤泡长度和直径减小。角蛋白化蛋白质掺入半胱氨酸的水平可能比非角蛋白化蛋白质更敏感。因此,TSP 的破坏可能会影响鸟类的体温调节能力。