Dietary tea tree (Melaleuca alternifolia) oil supplementation enhances the expressions of amino acid transporters in goat ileal mucosa and improves intestinal immunity.

Tea tree oil (TTO) is a plant-derived additive with anti-inflammatory, bactericidal, and growth-promoting properties. However, little is known about the effects of TTO on intestinal amino acid transport and immune function in goats. Twenty-four Ganxi goats (initial body weight of 13.5 ± 0.70 kg) were randomly allotted two treatments and fed either control (CON) or CON+TTO (0.2 ml/kg) diet. The addition of TTO to the diet significantly decreased (p < .05) tumor necrosis factor-α content and increased (p < .05) interleukin-2 (IL-2) content in goat serum; significantly decreased (p < .05) IL-12, and increased (p < .05) IL-2 content in goat ileal mucosa; significantly increased (p < .05) secreted IgA content in the jejunal and ileal mucosa; significantly upregulated (p < .05) IL-2 and downregulated (p < .05) IL-12 at the mRNA level in the ileal mucosa; significantly elevated the levels of serine, arginine, and total amino acids in the ileal mucosa (p < .05); significantly upregulated (p < .05) SLC1A1 and SLC7A1 in the ileum; and significantly enhanced (p < .05) the protein expression of Claudin-1 in the ileal mucosa. In summary, adding 0.2 ml/kg of TTO to the diet enhanced SLC1A1 and SLC7A1 mRNA expression in the ileal mucosa, and SLC1A1 and SLC7A1 could transport serine and arginine from the chyme to the ileal mucosa. Thus, increased serine and arginine content in the mucosa could improve intestinal immunity. TTO supplementation upregulated the expression of IL-2 and Claudin-1 in goat ileal mucosa, and enhanced immune function in the intestine.

Effect of polyamines on the grain filling of wheat under drought stress.

Drought inhibits wheat grain filling. Polyamines (PAs) are closely associated with plant resistance due to drought and grain filling of cereals. However, little is known about the effect of PAs on the grain filling of wheat under drought stress. This study investigated whether and how PAs are involved in regulating wheat grain filling under drought stress. Two wheat genotypes differing in drought resistance were used, and endogenous PA levels were measured during grain filling under different water treatments. Additionally, external PAs were used, and the variation of hormone levels in grains was measured during grain filling under drought stress. The results indicated that spermidine (Spd) and spermine (Spm) relieve the inhibition caused by drought stress, and putrescine (Put) has the opposite effect. The higher activities of S-adenosylmethionine decarboxylase and Spd synthase in grains promotes the synthetic route from Put to Spd and Spm and notably increases the free Spd and Spm concentrations in grains, which promotes grain filling and drought resistance in wheat. The effect of PA on the grain filling of wheat under drought stress was closely related to the endogenous ethylene (ETH), zeatin (Z) + zeatin riboside (ZR) and abscisic acid (ABA). Spd and Spm significantly increased the Z + ZR and ABA concentrations and decreased the ETH evolution rate in grains, which promoted wheat grain filling under drought. Put significantly increased the ETH evolution rate, which led to excessive ABA accumulation in grains, subsequently aggravating the inhibition of drought on wheat grain filling. This means that the interaction of hormones, rather than the action of a single hormone, was involved in the regulation of wheat grain filling under drought.