Development of miniature base editors using engineered IscB nickase.

As a miniature RNA-guided endonuclease, IscB is presumed to be the ancestor of Cas9 and to share similar functions. IscB is less than half the size of Cas9 and thus more suitable for in vivo delivery. However, the poor editing efficiency of IscB in eukaryotic cells limits its in vivo applications. Here we describe the engineering of OgeuIscB and its corresponding ωRNA to develop an IscB system that is highly efficient in mammalian systems, named enIscB. By fusing enIscB with T5 exonuclease (T5E), we found enIscB-T5E exhibited comparable targeting efficiency to SpG Cas9 while showing reduced chromosome translocation effects in human cells. Furthermore, by fusing cytosine or adenosine deaminase with enIscB nickase, we generated miniature IscB-derived base editors (miBEs), exhibiting robust editing efficiency (up to 92%) to induce DNA base conversions. Overall, our work establishes enIscB-T5E and miBEs as versatile tools for genome editing.

Sow-Offspring Diets Supplemented with Probiotics and Synbiotics Are Associated with Offspring's Growth Performance and Meat Quality.

Probiotics and synbiotics supplementation have been shown to play potential roles in animal production. The present study aimed to evaluate the effects of dietary probiotics and synbiotics supplementation to sows during gestation and lactation and to offspring pigs (sow-offspring) on offspring pigs' growth performance and meat quality. Sixty-four healthy Bama mini-pigs were selected and randomly allocated into four groups after mating: the control, antibiotics, probiotics, and synbiotics groups. After weaning, two offspring pigs per litter were selected, and four offspring pigs from two litters were merged into one pen. The offspring pigs were fed a basal diet and the same feed additive according to their corresponding sows, representing the control group (Con group), sow-offspring antibiotics group (S-OA group), sow-offspring probiotics group (S-OP group), and sow-offspring synbiotics group (S-OS group). Eight pigs per group were euthanized and sampled at 65, 95, and 125 d old for further analyses. Our findings showed that probiotics supplementation in sow-offspring diets promoted growth and feed intake of offspring pigs during 95-125 d old. Moreover, sow-offspring diets supplemented with probiotics and synbiotics altered meat quality (meat color, pH45min, pH24h, drip loss, cooking yield, and shear force), plasma UN and AMM levels, and gene expressions associated with muscle-fiber types (MyHCI, MyHCIIa, MyHCIIx, and MyHCIIb) and muscle growth and development (Myf5, Myf6, MyoD, and MyoG). This study provides a theoretical basis for the maternal-offspring integration regulation of meat quality by dietary probiotics and synbiotics supplementation.

The mitigating effects of diatom-bacteria biofilm on coastal harmful algal blooms: A lab-based study concerning species-specific competition and biofilm formation.

Harmful algal blooms (HABs) in coastal areas severely affected the health of ecosystem and human beings. The HABs control by biological methods, especially for biofilms, has been research hotspots in freshwater ecosystem. However, the biofilm-relating control of HABs in marine environment was very limited. In the present study, we found the population growth of two harmful algal species, Prorocentrum obtusidens Schiller (formerly P. donghaiense Lu) and Heterosigma akashiwo, were inhibited by a diatom-bacteria biofilm. The highest inhibitory rate was 79.6 ± 2.1% for P. obtusidens when co-cultured with biofilm suspension, and was 88.6 ± 5.8% for H. akashiwo when co-cultured with the biofilm filtrate without nutrient replenishment. When nitrate and phosphate were added, the inhibition rate for P. obtusidens was 72.3 ± 2.0%, but the population inhibition was not found in H. akashiwo. It suggested that P. obtusidens was mainly inhibited via interference competition, while the inhibition of H. akashiwo was resulted from exploitation competition. We further investigated the role of fatty acids for the interference competition in P. obtusidens, and found that fatty acids at their environmental-relevance concentrations can inhibit the photosynthetic capacity of P. obtusidens, but cannot inhibit the population growth. The community of biofilm shifted, and was finally dominated by the photoheterotrophic bacterium Dinoroseobacter shibae, and the diatom Fistulifera sp. with relative abundance of higher than 90%. Our study indicated that the diatom-bacteria biofilm was likely the candidate for the HABs control in marine environment. D. shibae and Fistulifera sp. were probably the effective species in the biofilm.

Enhancing and stabilization of cord blood regulatory T-cell suppressive function by human mesenchymal stem cell (MSC)-derived exosomes.

FOXP3+ regulatory T cells (Tregs) are central to maintaining peripheral tolerance and immune homeostasis. They have the potential to be developed as a cellular therapy to treat various clinical ailments such as autoimmune disorders, inflammatory diseases and to improve transplantation outcomes. However, a major question remains whether Tregs can persist and exert their function effectively in a disease state, where a broad spectrum of inflammatory mediators could inactivate Tregs. In this study, we investigated the potential of mesenchymal stem cell (MSC)-derived exosomes to promote and sustain Tregs function. MSC-conditioned media (MSC-CM) cultured Tregs were more suppressive in both polyclonal and allogeneic responses and were resistant to inflammatory stimulation in vitro compared with the controls. A similar enhancement of Treg function was also observed by culturing Tregs with MSC-derived exosomes alone. The enhanced suppressive activity and stability of Treg cultured in MSC-CM was reduced when exosomes were depleted from MSC-CM. We identified that MSC-derived exosomes could upregulate the expression of LC3(II/I), phosphorylate Jak3 and Stat5 to promote Treg survival, and regulate FOXP3 expression in Tregs. Overall, our study demonstrates that MSC-derived exosomes are capable of enhancing Hucb-Tregs function and stability by activating autophagy and Stat5 signalling pathways. Our findings provide a strong rationale for utilizing MSC-derived exosomes as an effective strategy to enhance Treg function, and improve the overall Tregs-based cell therapy landscape.

Advanced single-cell pooled CRISPR screening identifies C19orf53 required for cell proliferation based on mTORC1 regulators.

Multiplexed single-cell CRISPR screening has accelerated the systematic dissection of biological discoveries; however, the efficiency of CRISPR-based gene knockout has inherent limitations. Here, we present DoNick-seq, an advanced method for facilitating gene knockout and reducing off-target activity. We re-engineered two popular plasmid constructs suitable for use in pooled CRISPR screening of the single-cell transcriptome. We then used DoNick-seq to probe mTORC1 regulators and obtain genomic perturbation and transcriptome profiles from the same cell. Thus, DoNick-seq enabled us to simultaneously evaluate multiple gene interactions and the effect of amino acid depletion. By analyzing more than 20,000 cells from two cell lines, DoNick-seq efficiently identified gene targets, cell numbers, and cellular profiles. Our data also revealed the characteristics of mTORC1 negative and positive regulators, thereby shedding new insights into the mechanisms regulating cell growth and inhibition. We demonstrate that mTORC1 hyperactivation exhausts cellular free amino acids via increased proliferation ability. Furthermore, DoNick-seq identified the gene C19orf53, which mediates excessive cell proliferation, resulting in metabolic imbalance, and greatly enhances oxidative stress in response to toxins. Thus, our findings suggest that DoNick-seq facilitates high-throughput functional dissection of complex cellular responses at the single-cell level and increases the accuracy of CRISPR single-cell transcriptomics.

Maternal probiotics supplementation improves immune and antioxidant function in suckling piglets via modifying gut microbiota.

AIM: Probiotics could improve the health, growth, and development of host or their foetuses/offspring via regulating gut microbiota. The present study was conducted to determine the effects of maternal probiotics supplementation on gut microbiota and metabolites of sows and their suckling piglets, as well as plasma biochemical parameters, oxidative/anti-oxidative indexes, and inflammatory cytokine levels of suckling piglets. METHODS AND RESULTS: A total of 32 pregnant Bama mini-pigs were selected and randomly divided into two groups. The sows were fed a basal diet (control group) or a basal diet supplemented with probiotics (probiotics group) from mating to day 21 of lactation. Samples from sows were collected on day 105 of pregnancy and day 21 of lactation and from piglets on day 21 of lactation. The results showed that probiotics supplementation increased the faecal abundances of Ruminococcus, Bacteroides, and Anaeroplasma and decreased Tenericutes on day 105 of pregnancy while increased the abundances of Actinobacteria and Anaerostipes and decreased Proteobacteria and Desulfovibrio on day 21 of lactation. In addition, probiotics supplementation decreased the faecal levels of tryptamine, putrescine, and cadaverine on day 105 of pregnancy and isovalerate and skatole on day 21 of lactation while increased butyrate level on day 21 of lactation. Further studies showed that maternal probiotics supplementation decreased the plasma levels of AMM, TC, LDL-C, Ala, Tau, MDA, H2 O2 , IL-1ß, IL-2, IL-6, and IFN-α of suckling piglets. Moreover, maternal probiotics supplementation increased the abundances of Deferribacteres, Fusobacteria, and Fusobacterium while decreased Anaerostipes in piglet's colon. Spearman's correlation analysis revealed a potential link between gut microbiota alterations and their metabolites. CONCLUSIONS: Dietary probiotics supplementation during pregnancy and lactation periods could improve sow status, alleviate oxidative stress and inflammation response, and improve nutrient metabolism of piglets by altering the gut microbiota. SIGNIFICANCE AND IMPACT OF THE STUDY: The probiotics alter maternal and offspring's gut microbiota involving in offspring's physiological and metabolic changes, and present a new perspective that the effects of gut microbiota changes induced by probiotics supplementation will help in addressing the growth and development and health problem of their foetuses/offspring.

Dynamic alteration in the gut microbiota and metabolome of Huanjiang mini-pigs during pregnancy.

BACKGROUND: Maternal gut microbiota and metabolites are associated with their offspring's health. Our previous study showed that maternal body fat percentage increased from days 45 to 110 of gestation in a Huanjiang mini-pig model. Thus, this study aimed to investigate the changes in gut microbiota composition and microbial metabolite profile of sows from days 45 to 110 of gestation. RESULTS: Twenty-four Huanjiang mini-pigs with average body weight were assigned for sample collection during early- (day 45 of pregnancy), mid- (day 75 of pregnancy), and late-pregnancy (day 110 of pregnancy). The results showed that the relative abundances of Clostridium_sensu_stricto_1, Romboutsia, Turicibacter, and Streptococcus in jejunal contents were higher at day 110 than those at day 45 or 75 of gestation. In the ileum, the relative abundance of Streptococcus was higher (P < 0.05) at day 110 of gestation, as well as the metabolism function of the jejunal and ileal microbiota. The ileal butyrate and acetate concentrations were higher at days 45 and 110 of gestation, respectively. In the colon, the concentrations of cadaverine and spermine were higher (P < 0.05) at days 45 and 110 of gestation, respectively. Metabolomic analyses demonstrated that the metabolic pathways, including D-glutamine and D-glutamate metabolism, phenylalanine/tyrosine/tryptophan biosynthesis, and alanine/aspartate/glutamate metabolism changed during gestation. CONCLUSION: Collectively, our results showed that gut microbiota composition and microbial metabolites changed dramatically from early to late pregnancy in a Huanjiang mini-pig model. These findings will provide new targets in formulating maternal nutritional interventions to alleviate the adverse effects during pregnancy on offspring health outcomes.

Developmental Changes of Immunity and Different Responses to Weaning Stress of Chinese Indigenous Piglets and Duroc Piglets during Suckling and Weaning Periods.

To investigate developmental changes in immunity and different responses to weaning stress of piglets from different breeds during suckling and weaning periods, a total of 30 litters of Taoyuan black (TB) piglets, Xiangcun black (XB) piglets, and Duroc (DR) piglets (ten litters per breed) were selected at 1, 10, 21, and 24 days of age, respectively. The results showed that the liver index of TB piglets was higher at 10 days of age than that of the other days of age and breeds. Regardless of the days of age, TB and XB piglets had a higher plasma IgA level and lower ileal IgM level than in the DR piglets, and XB piglets had a lower plasma IgG level than the other breeds. TB and XB piglets had a higher IL-6 level and lower IL-17 level in plasma at 24 days of age than DR piglets, regardless of the days of age. The ileal levels of IL-2, IL-10, IFN-γ, and TNF-α were lower in the TB and XB piglets at 24 days of age than in the DR piglets. The ileal expression levels of IRAK1, CD14, MyD88, and NF-κB were down-regulated in the TB and XB piglets at 24 days of age compared to those in the DR piglets. These findings suggest that there were differences in the development of immune function among different pig breeds. Moreover, TB and XB piglets presented stronger resistance to weaning stress than the DR piglets, which may be related to the immune regulation mediated by the MyD88/NF-κB signaling pathway.

Betaine hydrochloride addition in Bama mini-pig's diets during gestation and lactation enhances immunity and alters intestine microbiota of suckling piglets.

BACKGROUND: Maternal nutrition during gestation and lactation is essential for offspring's health. The present study aimed to investigate the effects of betaine hydrochloride addition to sow diets during gestation and lactation on suckling piglet's immunity and intestine microbiota composition. Forty Bama mini-pigs were randomly allocated into two groups and fed a basal diet (control group) and a basal diet supplemented with 3.50 kg ton-1 betaine hydrochloride (betaine group) from day 3 after mating to day 21 of lactation. After 21 days of the delivery, 12 suckling piglets from each group with similar body weight were selected for sample collection. RESULTS: The results showed that maternal betaine hydrochloride addition decreased (P < 0.05) the plasma levels of interleukin (IL)-1ß, IL-2, IL-6, and tumor necrosis factor-α in suckling piglets. Furthermore, dietary betaine hydrochloride addition in sow diets increased (P < 0.05) the villus height (VH) and VH to crypt depth ratio in the jejunum and ileum of suckling piglets. In the piglets' intestinal microbiota community, the relative abundances of Roseburia (P < 0.05) and Clostridium (P = 0.059) were lower in the betaine group compared to those in the control group. Moreover, betaine hydrochloride addition in sow diets decreased the colonic tyramine (P = 0.091) and skatole (P = 0.070) concentrations in suckling piglets. CONCLUSION: Betaine hydrochloride addition in sow diets enhanced the intestinal morphology, improved immunity, and altered intestinal microbiota of suckling piglets. These findings indicated that betaine hydrochloride addition in sow diets during gestation and lactation will impact suckling piglets' health. © 2021 Society of Chemical Industry.

Dietary addition of fermented sorghum distiller's dried grains with soluble improves carcass traits and meat quality in growing-finishing pigs.

The fermented sorghum distiller's dried grain with soluble (FS-DDGS) contains numerous nutrients, yet its nutritional effects on growing-finishing pigs remain unclear. The present study evaluated the effects of dietary FS-DDGS addition on growth performance, carcass traits, and meat quality in growing-finishing pigs. A total of 48 healthy male crossbred (Large White × Landrace × Duroc) barrows with initial body weight (BW) of 39.95 ± 2.15 kg were allocated to one of four dietary treatments (12 pigs per treatment). The dietary treatments were as follows: basal diet without (FS-DDGS0 group) or with 50 g/kg (FS-DDGS50 group), 100 g/kg (FS-DDGS100 group), or 150 g/kg (FS-DDGS150 group) FS-DDGS, respectively. Results showed that there were no significant differences in the final BW, average daily gain, average daily feed intake, and feed to gain ratio among these four groups. However, dietary FS-DDGS addition increased (linear, P < 0.05) the pH24h value, contents of ash, crude protein, and proline in Longissimus dorsi muscle, and alanine, arginine, aspartic acid, glutamic acid, isoleucine, leucine, lysine, serine, and tyrosine in Biceps femoris (BF) muscle, when compared with the control group. In addition, dietary FS-DDGS addition decreased (linear, P < 0.05) the drip loss, yellowness (b*) value, and lightness (L*) value, while quadratically improved (P < 0.05) the total bone percentage and glycine and proline contents in BF muscle compared with the control group. Collectively, these findings suggested that dietary FS-DDGS addition could improve the carcass traits and meat quality in growing-finishing pigs although further research is needed to explore the underlying mechanisms.

Two Chloroplast Proteins Negatively Regulate Plant Drought Resistance Through Separate Pathways.

Drought is one of the most deleterious environmental conditions affecting crop growth and productivity. Here we report the important roles of a nuclear-encoded chloroplast protein, PsbP Domain Protein 5 (PPD5), in drought resistance in Arabidopsis (Arabidopsis thaliana). From a forward genetic screen, a drought-resistant mutant named ppd5-2 was identified, which has a knockout mutation in PPD5 The ppd5 mutants showed increased H2O2 accumulation in guard cells and enhanced stomatal closure in response to drought stress. Further analysis revealed that the chloroplast-localized PPD5 protein interacts with and is phosphorylated by OST1, and phosphorylation of PPD5 increases its protein stability. Double mutant ppd5-2ost1-3 exhibited phenotypes resembling the ost1-3 single mutant with decreased stomatal closure, increased water loss, reduced H2O2 accumulation in guard cells, and hypersensitivity to drought stress. These results indicate that the chloroplast protein PPD5 negatively regulates drought resistance by modulating guard cell H2O2 accumulation via an OST1-dependent pathway. Interestingly, the thf1-1 mutant defective in the chloroplast protein THF1 displayed drought-resistance and H2O2 accumulation similar to the ppd5 mutants, but the thf1-1ost1-3 double mutant resembled the phenotypes of the thf1-1 single mutant. These results indicate that both OST1-dependent and OST1-independent pathways exist in the regulation of H2O2 production in chloroplasts of guard cells under drought stress conditions. Additionally, our findings suggest a strategy to improve plant drought resistance through manipulation of chloroplast proteins.

Gut microbiota mediates the protective effects of dietary ß-hydroxy-ß-methylbutyrate (HMB) against obesity induced by high-fat diets.

Obesity increases the risk of developing insulin resistance and diabetes and is a major public health concern. Our previous study shows that dietary ß-hydroxy-ß-methylbutyrate (HMB) improves lipid metabolism in a pig model. However, it remains unclear whether HMB blocks obesity through gut microbiota. In this study, we found that HMB reduced body weight, alleviated the whitening of brown adipose tissue, and improved insulin resistance in mice fed a high-fat diet (HFD). High-throughput pyrosequencing of the 16S rRNA demonstrated that HMB administration significantly reversed the gut microbiota dysbiosis in HFD-fed mice, including the diversity of gut microbiota and relative abundances of Bacteroidetes and Firmicutes. Moreover, microbiota transplantation from HMB-treated mice attenuated HFD-induced lipid metabolic disorders. Furthermore, HFD-fed mice showed lower short-chain fatty acids, whereas administration of HMB increased the propionic acid production. Correlation analysis identified a significant correlation between propionic acid production and the relative Bacteroidetes abundance. Sodium propionate treatment also attenuated HFD-induced lipid metabolic disorders. Collectively, our results indicated that HMB might be used as a probiotic agent to reverse HFD-induced obesity, and the potential mechanism was associated with reprogramming gut microbiota and metabolism, especially Bacteroidetes-mediated propionic acid production. In future studies, more efforts should be made to confirm and expand the beneficial effects of HMB to human models.-Duan, Y., Zhong, Y., Xiao, H., Zheng, C., Song, B., Wang, W., Guo, Q., Li, Y., Han, H., Gao, J., Xu, K., Li, T., Yin, Y., Li, F., Yin, J., Kong, X. Gut microbiota mediates the protective effects of dietary ß-hydroxy-ß-methylbutyrate (HMB) against obesity induced by high-fat diets.

Sulfur-containing amino acid supplementation to gilts from late pregnancy to lactation altered offspring's intestinal microbiota and plasma metabolites.

Maternal nutrition during late pregnancy and lactation is highly involved with the offspring's health status. The study was carried out to evaluate the effects of different ratios of methionine and cysteine (Met/Cys: 46% Met, 51% Met, 56% Met, and 62% Met; maintained with 0.78% of total sulfur-containing amino acids; details in "Materials and methods") supplements in the sows' diet from late pregnancy to lactation on offspring's plasma metabolomics and intestinal microbiota. The results revealed that the level of serum albumin, calcium, iron, and magnesium was increased in the 51% Met group compared with the 46% Met, 56% Met, and 62% Met groups. Plasma metabolomics results indicated that the higher ratios of methionine and cysteine (0.51% Met, 0.56% Met, and 0.62% Met)-supplemented groups enriched the level of hippuric acid, retinoic acid, riboflavin, and δ-tocopherol than in the 46% Met group. Furthermore, the 51% Met-supplemented group had a higher relative abundance of Firmicutes compared with the other three groups (P < 0.05), while the 62% Met-supplemented group increased the abundance of Proteobacteria compared with the other three groups (P < 0.05) in piglets' intestine. These results indicated that a diet consisting with 51% Met is the optimum Met/Cys ratio from late pregnancy to lactation can maintain the offspring's health by improving the serum biochemical indicators and altering the plasma metabolomics profile and intestinal gut microbiota composition, but higher proportion of Met/Cys may increase the possible risk to offspring's health.

Alterations in the Blood Parameters and Fecal Microbiota and Metabolites during Pregnant and Lactating Stages in Bama Mini Pigs as a Model.

This study was conducted to analyze plasma reproductive hormone and biochemical parameter changes, as well as fecal microbiota composition and metabolites in sows, at different pregnancy and lactation stages, using Bama mini pig as an experimental animal model. We found that plasma prolactin (PRL), progesterone, follicle-stimulating hormone (FSH), and estrogen levels decreased from day 45 to day 105 of pregnancy. Plasma total protein and albumin levels were lower in pregnant sows, while glucose, urea nitrogen, total cholesterol, and high-density lipoprotein-cholesterol, as well as fecal acetate, butyrate, valerate, total short-chain fatty acids, skatole, and tyramine levels, were higher in lactating sows. Interestingly, the lactating sows showed lower α-diversity and Spirochaetes and Verrucomicrobia relative abundances, while pregnant sows showed a higher Proteobacteria relative abundance. Notably, the Akkermansia relative abundance was highest on day 7 of lactation. Spearman analysis showed a positive correlation between plasma triglyceride and cholinesterase levels and Akkermansia and Streptococcus relative abundances. Moreover, Oscillospira and Desulfovibrio relative abundances were also positively correlated with plasma FSH, LH, and E2 levels, as well as PRL and LH with Bacteroides. Collectively, plasma reproductive hormones, biochemical parameters, and fecal microbiota composition and metabolite levels could alter along with pregnancy and lactation, which might contribute to the growth and development demands of fetuses and newborns.

Dynamic changes in circulating levels of metabolites in the portal-drained viscera of finishing pigs receiving acute administration of l-arginine.

In this study, we examined the effects of acute intravenous administration of l-arginine on circulating levels of metabolites in the portal-drained viscera (PDV) of 12 barrows surgically fitted with chronic catheters in the portal vein. At day 14 post-surgery, the pigs were fasted for 12 hr and then randomly allocated to one of three groups to receive administration of normal saline, l-alanine [103 mg/kg body weight (BW), isonitrogenous control] or l-arginine-HCl (61 mg/kg BW), via the portal vein. Blood samples were obtained from the carotid artery before and at 30-min intervals for 5 hr after the administration of saline or amino acid in order to determine metabolic profiles. The results showed that, compared with the saline treatment, arginine infusion increased plasma concentrations of insulin-like growth factor-I, arginine and cystine in the portal vein plasma, whereas plasma concentrations of threonine, serine, leucine and methionine were reduced. These findings indicate that increasing arginine concentrations in the portal vein alters the metabolic profile in swine, an established animal model for studying human nutrition and metabolism.

Recruitment of the NineTeen Complex to the activated spliceosome requires AtPRMT5.

Protein arginine methylation, catalyzed by protein arginine methyltransferases (PRMTs), is involved in a multitude of biological processes in eukaryotes. Symmetric arginine dimethylation mediated by PRMT5 modulates constitutive and alternative pre-mRNA splicing of diverse genes to regulate normal growth and development in multiple species; however, the underlying molecular mechanism remains largely unknown. A genetic screen for suppressors of an Arabidopsis symmetric arginine dimethyltransferase mutant, atprmt5, identified two gain-of-function alleles of pre-mRNA processing factor 8 gene (prp8-8 and prp8-9), the highly conserved core component of the U5 small nuclear ribonucleoprotein (snRNP) and the spliceosome. These two atprmt5 prp8 double mutants showed suppression of the developmental and splicing alterations of atprmt5 mutants. In atprmt5 mutants, the NineTeen complex failed to be assembled into the U5 snRNP to form an activated spliceosome; this phenotype was restored in the atprmt5 prp8-8 double mutants. We also found that loss of symmetric arginine dimethylation of Sm proteins prevents recruitment of the NineTeen complex and initiation of spliceosome activation. Together, our findings demonstrate that symmetric arginine dimethylation has important functions in spliceosome assembly and activation, and uncover a key molecular mechanism for arginine methylation in pre-mRNA splicing that impacts diverse developmental processes.

Dietary nutrient levels alter the metabolism of arginine family amino acids in the conceptus of Huanjiang mini-pigs.

BACKGROUND: The arginine family amino acids (AFAAs) exert important roles in the metabolism, growth and development of the conceptus. However, to date, few studies have investigated the effects of maternal nutrient levels on the concentrations and metabolism of AFAAs in the conceptus. RESULTS: Compared to low nutrient diets, high nutrient diets increased (P < 0.05) the concentrations of citrulline and proline (Pro) in plasma; the concentrations of arginine, glutamine, Pro and ornithine (Orn) in the amniotic fluid; and the concentrations of all detected AFAAs in the allantoic fluid, which were most pronounced on day 45 of pregnancy. High nutrient diets upregulated (P < 0.05) mRNA expression of arginase I (Arg I), Pro oxidase and spermidine synthetase (SRM) in the fetal placenta, as well as Arg II, SRM and spermine synthetase (SMS) expression in the fetal liver (most pronounced on day 45 of pregnancy). The same effect was observed for mRNA expression of NO synthase and Orn aminotransferase (OAT), mainly on day 110 of pregnancy, and for mRNA expression of Arg I, Arg II, OAT, Orn decarboxylase and SMS throughout pregnancy. High nutrient diets upregulated (P < 0.05) mRNA expression of Y+ L-type amino acid transporter (LAT) and cationic amino acid transporter 1 (CAT1) in the fetal jejunum throughout pregnancy. Dietary treatments did not affect (P > 0.05) mRNA expression of Y+ LAT1, sodium-coupled neutral amino acid transporter 2 (SNAT2) and CAT1 in the fetal placenta, skeletal muscle and colon. CONCLUSION: High nutrient diets increased the concentration and transport of AFAAs in the mothers and conceptus, which likely improves growth and development of the conceptus. © 2018 Society of Chemical Industry.

α-Ketoisocaproate and ß-hydroxy-ß-methyl butyrate regulate fatty acid composition and lipid metabolism in skeletal muscle of growing pigs.

OBJECTIVES: This study aims to investigate the effects and roles of excess leucine (Leu) versus its metabolites α-ketoisocaproate (KIC) and ß-hydroxy-ß-methyl butyrate (HMB) on fatty acid composition and lipid metabolism in skeletal muscle of growing pigs. METHODS AND RESULTS: Thirty-two pigs with a similar initial weight (9.55 ± 0.19 kg) were fed one of the four diets (basal diet, L-Leu, KIC-Ca and HMB-Ca) for 45 days. Results indicated that dietary treatments did not affect the intramuscular fat (IMF) content (p > 0.05), but differently influenced the fatty acid composition of longissimus dorsi muscle (LM) and soleus muscle (SM). In particular, the proportion of N3 PUFA specifically in LM was significantly decreased in the Leu group and increased in both KIC and HMB group relative to the basal diet group (p < 0.05). Furthermore, pigs fed KIC-supplemented diets exhibited decreased expression of FATP-1, ACC, ATGL, C/EBPα, PPARγ and SREBP-1c in LM and increased expression of FATP-1, FAT/CD36, ATGL and M-CPT-1 in SM relative to the basal diet control (p < 0.05). CONCLUSIONS: These findings indicated that doubling dietary Leu content decreased the percentage of N3 PUFA mainly in glycolytic skeletal muscle, whereas KIC and HMB improved muscular fatty acid composition and altered lipid metabolism in skeletal muscle of growing pigs. The mechanism of action of KIC might be related to the TFs, and the mechanism of action of HMB might be associated with the AMPK-mTOR signalling pathway.

Leucine alone or in combination with glutamic acid, but not with arginine, increases biceps femoris muscle and alters muscle AA transport and concentrations in fattening pigs.

Forty-eight Duroc × Large White × Landrace pigs with an average initial body weight of 77.09 ± 1.37 kg were used to investigate the effects of combination of leucine (Leu) with arginine (Arg) or glutamic acid (Glu) on muscle growth, free amino acid profiles, expression levels of amino acid transporters and growth-related genes in skeletal muscle. The animals were randomly assigned to one of the four treatment groups (12 pigs/group, castrated male:female = 1:1). The pigs in the control group were fed a basal diet (13% Crude Protein), and those in the experimental groups were fed the basal diet supplemented with 1.00% Leu (L group), 1.00% Leu + 1.00% Arg (LA group) or 1.00% Leu + 1.00% Glu (LG group). The experiment lasted for 60 days. Results showed an increase (p < 0.05) in biceps femoris (BF) muscle weight in the L group and LG group relative to the basal diet group. In longissimus dorsi (LD) muscle, Lys, taurine and total essential amino acid concentration increased in the LG group relative to the basal diet group (p < 0.05). In LG group, Glu and carnosine concentrations increased (p < 0.05) in the BF muscle, when compared to the basal diet group. The Leu and Lys concentrations of BF muscle were lower in the LA group than that in the L group (p < 0.05). A positive association was found between BF muscle weight and Leu concentration (p < 0.05). The LG group presented higher (p < 0.05) mRNA levels of ASCT2, LAT1, PAT2, SANT2 and TAT1 in LD muscle than those in the basal diet group. The mRNA levels of PAT2 and MyoD in BF muscle were upregulated (p < 0.05) in the LG group, compared with those in the basal diet group. In conclusion, Leu alone or in combination with Glu is benefit for biceps femoris muscle growth in fattening pig.

Phosphogypsum stabilization of bauxite residue: Conversion of its alkaline characteristics.

Reduction of the high alkalinity of bauxite residue is a key problem to solve to make it suitable for plant growth and comprehensive utilization. In this study, phosphogypsum, a waste product from the phosphate fertilizer industry, was used to drive the alkaline transformation of the bauxite residue. Under optimal water washing conditions (liquid/solid ratio of 2 mL/g, 30°C, 24 hr), the impact of quantity added, reaction time and reaction mechanism during phosphogypsum application were investigated. Phosphogypsum addition effectively lowered pH levels and reduced the soluble alkalinity by 92.2%. It was found that the concentration of soluble Na and Ca ions in the supernatant increased gradually, whilst the exchangeable Na+ and Ca2+ in solid phase changed 112 mg/kg and 259 mg/kg, respectively. Ca2+ became the dominant element in the solid phase (phosphogypsum addition of 2%, liquid/solid ratio of 2 mL/g, 30°C, 12 hr). X-ray diffraction data indicated that cancrinite and hydrogarnet were the primary alkaline minerals. SEM images suggested that phosphogypsum could promote the formation of stable macro-aggregates, whilst the content of Ca2+ increased from 5.6% to 18.2% and Na reduced from 6.8% to 2.4%. Treatment with phosphogypsum could significantly promote the transformation of alkalinity cations by neutralization, precipitation and replacement reactions. This research provided a feasible method to promote soil formation of bauxite residue by phosphogypsum amendment.