Effect of replacing soybean meal with Hermetia illucens meal on cecal microbiota, liver transcriptome, and plasma metabolome of broilers.

Despite the existence of a number of studies investigating the effect of insect meal on the growth performance of broilers, knowledge about the metabolic effects of insect meal in broilers is still scarce. Thus, the present study investigated the effect of partial replacement of soybean meal with Hermetia illucens (HI) larvae meal on the liver transcriptome, the plasma metabolome, and the cecal microbiota in broilers. For the study, 72 male one-day-old Cobb 500 broilers were divided into three groups and fed 3 different diets with either 0% (HI0), 7.5% (HI7.5), or 15% (HI15) defatted HI meal for 35 d. Each group consisted of 6 cages (replicates) with 4 broilers/cage. While body weight (BW) gain, feed intake, and feed:gain ratio did not differ between groups, breast muscle weight, carcass yield, and apparent ileal digestibility (AID) of 5 amino acids were higher in group HI15 than in group HI0 (P < 0.05). Indicators of α-diversity (Chao1 and Observed) in the cecal digesta were higher in groups HI15 and HI7.5 than in group HI0 (P < 0.05). The abundance of 5 families and 18 genera, all of which belonged to the Firmicutes phylum, in the cecal digesta differed among groups (P < 0.05). Concentrations of butyric acid, valeric acid, and isobutyric acid in the cecal digesta were lower in group HI15 than in the other 2 groups (P < 0.05), whereas those of total and other short-chain fatty acids were not different between groups. Liver transcriptomics revealed a total of 70 and 61 differentially expressed transcripts between groups HI15 vs. HI0 and between groups HI7.5 vs. HI0, respectively, (P < 0.05). Targeted metabolomics identified 138 metabolites, most of which were triglyceride species, being different between the 3 groups (FDR < 0.05). According to this study, dietary inclusion of HI larvae meal has no detrimental impact but increases breast muscle weight and carcass weight in broilers suggesting that HI larvae meal can be recommended as a sustainable alternative protein source for broilers.

Cytosolic iron-sulfur protein assembly system identifies clients by a C-terminal tripeptide.

The eukaryotic cytosolic Fe-S protein assembly (CIA) machinery inserts iron-sulfur (Fe-S) clusters into cytosolic and nuclear proteins. In the final maturation step, the Fe-S cluster is transferred to the apo-proteins by the CIA-targeting complex (CTC). However, the molecular recognition determinants of client proteins are unknown. We show that a conserved [LIM]-[DES]-[WF]-COO- tripeptide is present at the C-terminus of more than a quarter of clients or their adaptors. When present, this targeting complex recognition (TCR) motif is necessary and sufficient for binding to the CTC in vitro and for directing Fe-S cluster delivery in vivo. Remarkably, fusion of this TCR signal enables engineering of cluster maturation on a nonnative protein via recruitment of the CIA machinery. Our study advances our understanding of Fe-S protein maturation and paves the way for bioengineering novel pathways containing Fe-S enzymes.

Cytosolic iron-sulfur protein assembly system identifies clients by a C-terminal tripeptide.

The eukaryotic cytosolic Fe-S protein assembly (CIA) machinery inserts iron-sulfur (Fe-S) clusters into cytosolic and nuclear proteins. In the final maturation step, the Fe-S cluster is transferred to the apo-proteins by the CIA-targeting complex (CTC). However, the molecular recognition determinants of client proteins are unknown. We show that a conserved [LIM]-[DES]-[WF]-COO- tripeptide present at the C-terminus of clients is necessary and sufficient for binding to the CTC in vitro and directing Fe-S cluster delivery in vivo. Remarkably, fusion of this TCR (target complex recognition) signal enables engineering of cluster maturation on a non-native protein via recruitment of the CIA machinery. Our study significantly advances our understanding of Fe-S protein maturation and paves the way for bioengineering applications.

Influence of Brewer's Spent Grain Compounds on Glucose Metabolism Enzymes.

With a yearly production of about 39 million tons, brewer's spent grain (BSG) is the most abundant brewing industry byproduct. Because it is rich in fiber and protein, it is commonly used as cattle feed but could also be used within the human diet. Additionally, it contains many bioactive substances such as hydroxycinnamic acids that are known to be antioxidants and potent inhibitors of enzymes of glucose metabolism. Therefore, our study aim was to prepare different extracts-A1-A7 (solid-liquid extraction with 60% acetone); HE1-HE6 (alkaline hydrolysis followed by ethyl acetate extraction) and HA1-HA3 (60% acetone extraction of alkaline residue)-from various BSGs which were characterized for their total phenolic (TPC) and total flavonoid (TFC) contents, before conducting in vitro studies on their effects on the glucose metabolism enzymes α-amylase, α-glucosidase, dipeptidyl peptidase IV (DPP IV), and glycogen phosphorylase α (GPα). Depending on the extraction procedures, TPCs ranged from 20-350 µg gallic acid equivalents/mg extract and TFCs were as high as 94 µg catechin equivalents/mg extract. Strong inhibition of glucose metabolism enzymes was also observed: the IC50 values for α-glucosidase inhibition ranged from 67.4 ± 8.1 µg/mL to 268.1 ± 29.4 µg/mL, for DPP IV inhibition they ranged from 290.6 ± 97.4 to 778.4 ± 95.5 µg/mL and for GPα enzyme inhibition from 12.6 ± 1.1 to 261 ± 6 µg/mL. However, the extracts did not strongly inhibit α-amylase. In general, the A extracts from solid-liquid extraction with 60% acetone showed stronger inhibitory potential towards a-glucosidase and GPα than other extracts whereby no correlation with TPC or TFC were observed. Additionally, DPP IV was mainly inhibited by HE extracts but the effect was not of biological relevance. Our results show that BSG is a potent source of α-glucosidase and GPα inhibitors, but further research is needed to identify these bioactive compounds within BSG extracts focusing on extracts from solid-liquid extraction with 60% acetone.