Mannan oligosaccharides alleviate oxidative injury in the head kidney and spleen in grass carp (Ctenopharyngodon idella) via the Nrf2 signaling pathway after Aeromonas hydrophila infection

BACKGROUND

Mannan oligosaccharides (MOS) are recommended as aquaculture additives owing to their excellent antioxidant properties. In the present study, we examined the effects of dietary MOS on the head kidney and spleen of grass carp (Ctenopharyngodon idella) with Aeromonas hydrophila infection.

METHODS

A total of 540 grass carp were used for the study. They were administered six gradient dosages of the MOS diet (0, 200, 400, 600, 800, and 1,000 mg/kg) for 60 d. Subsequently, we performed a 14-day Aeromonas hydrophila challenge experiment. The antioxidant capacity of the head kidney and spleen were examined using spectrophotometry, DNA fragmentation, qRT-PCR, and Western blotting.

RESULTS

After infection with Aeromonas hydrophila, 400-600 mg/kg MOS supplementation decreased the levels of reactive oxygen species, protein carbonyl, and malonaldehyde and increased the levels of anti-superoxide anion, anti-hydroxyl radical, and glutathione in the head kidney and spleen of grass carp. The activities of copper-zinc superoxide dismutase, manganese superoxide dismutase, catalase, glutathione S-transferase, glutathione reductase, and glutathione peroxidase were also enhanced by supplementation with 400-600 mg/kg MOS. Furthermore, the expression of most antioxidant enzymes and their corresponding genes increased significantly with supplementation of 200-800 mg/kg MOS. mRNA and protein levels of nuclear factor erythroid 2-related factor 2 also increased following supplementation with 400-600 mg/kg MOS. In addition, supplementation with 400-600 mg/kg MOS reduced excessive apoptosis by inhibiting the death receptor pathway and mitochondrial pathway processes.

CONCLUSIONS

Based on the quadratic regression analysis of the above biomarkers (reactive oxygen species, malondialdehyde, and protein carbonyl) of oxidative damage in the head kidney and spleen of on-growing grass carp, the recommended MOS supplementation is 575.21, 557.58, 531.86, 597.35, 570.16, and 553.80 mg/kg, respectively. Collectively, MOS supplementation could alleviate oxidative injury in the head kidney and spleen of grass carp infected with Aeromonas hydrophila.

Inactivation of two SARS-CoV-2 virus surrogates by electron beam irradiation on large yellow croaker slices and their packaging surfaces

The detection of infectious SARS-CoV-2 in food and food packaging associated with the cold chain has raised concerns about the possible transmission pathway of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in foods transported through cold-chain logistics and the need for novel decontamination strategies. In this study, the effect of electron beam (E-beam) irradiation on the inactivation of two SARS-CoV-2surrogate, viruses porcine epidemic diarrhea virus (PEDV) and porcine transmissible gastroenteritis virus (TGEV), in culture medium and food substrate, and on food substrate were investigated. The causes of virus inactivation were also investigated by transmission electron microscopy (TEM) and Quantitative Real-time PCR (QRT-PCR). Samples packed inside and outside, including virus-inoculated large yellow croaker and virus suspensions, were irradiated with E-beam irradiation (2, 4, 6, 8, 10 kGy) under refrigerated (0 °C)and frozen (−18 °C) conditions. The titers of both viruses in suspension and fish decreased significantly (P < 0.05) with increasing doses of E-beam irradiation. The maximum D₁₀ value of both viruses in suspension and fish was 1.24 kGy. E-beam irradiation at doses below 10 kGy was found to destroy the spike proteins of both SARS-CoV-2 surrogate viruses by transmission electron microscopy (TEM) and negative staining of thin-sectioned specimens, rendering them uninfectious. E-beam irradiation at doses greater than 10 kGy was also found to degrade viral genomic RNA by qRT-PCR. There were no significant differences in color, pH, TVB-N, TBARS, and sensory properties of irradiated fish samples at doses below 10 kGy. These findings suggested that E-beam irradiation has the potential to be developed as an efficient non-thermal treatment to reduce SARS-CoV-2 contamination in foods transported through cold chain foods to reduce the risk of SARS-CoV-2 infection in humans through the cold chain.

The interaction between dietary fiber and gut microbiota, and its effect on pig intestinal health

Intestinal health is closely associated with overall animal health and performance and, consequently, influences the production efficiency and profit in feed and animal production systems. The gastrointestinal tract (GIT) is the main site of the nutrient digestive process and the largest immune organ in the host, and the gut microbiota colonizing the GIT plays a key role in maintaining intestinal health. Dietary fiber (DF) is a key factor in maintaining normal intestinal function. The biological functioning of DF is mainly achieved by microbial fermentation, which occurs mainly in the distal small and large intestine. Short-chain fatty acids (SCFAs), the main class of microbial fermentation metabolites, are the main energy supply for intestinal cells. SCFAs help to maintain normal intestinal function, induce immunomodulatory effects to prevent inflammation and microbial infection, and are vital for the maintenance of homeostasis. Moreover, because of its distinct characteristics (e.g. solubility), DF is able to alter the composition of the gut microbiota. Therefore, understanding the role that DF plays in modulating gut microbiota, and how it influences intestinal health, is essential. This review gives an overview of DF and its microbial fermentation process, and investigates the effect of DF on the alteration of gut microbiota composition in pigs. The effects of interaction between DF and the gut microbiota, particularly as they relate to SCFA production, on intestinal health are also illustrated.

Optimal DL-Methionyl-DL-Methionine Supplementation Improved Intestinal Physical Barrier Function by Changing Antioxidant Capacity, Apoptosis and Tight Junction Proteins in the Intestine of Juvenile Grass Carp (Ctenopharyngodon idella)

The present study was a part of a larger research project that aimed to investigate the effects of Met-Met supplementation on fish growth and intestinal health. This study mainly focused on the relationship between dietary Met-Met and intestinal physical barrier function in fish. Seven iso-nitrogenous diets supplemented with 2.50 g/kg DL-methionine (DL-Met) and six graded levels of Met-Met (0.00, 0.79, 1.44, 1.84, 2.22, and 2.85 g/kg) were used to feed juvenile grass carp for 10 weeks, after which a 14-day Aeromonas hydrophila challenge test was performed. The results indicated that optimum levels of Met-Met decreased intestinal oxidative damage, probably by increasing total antioxidant capacity, and the activity and gene expression levels of several antioxidant enzymes, which were closely related to the changed Nrf2/Keap1 signaling. Meanwhile, optimum levels of Met-Met decreased intestinal apoptosis and improved the intestinal tight junction, as evident by the downregulated mRNA levels of initiator and executioner caspases; the pro-apoptotic-related proteins FasL, Apaf-1, and Bax; and upregulated mRNA levels of the anti-apoptotic proteins Bcl-2, Mcl-1b, and IAP and the TJ proteins claudins, occludin, and ZOs. Furthermore, the positive effects of Met-Met on improving intestinal physical barrier function were superior to those of DL-Met in fish. These findings showed that optimal Met-Met supplementation improved intestinal physical barrier function, probably by changing antioxidant capacity, apoptosis, and tight junction proteins in fish.

Dietary protein levels changed the hardness of muscle by acting on muscle fiber growth and the metabolism of collagen in sub-adult grass carp (Ctenopharyngodon idella)

Background

Nutrient regulation has been proven to be an effective way to improve the flesh quality in fish. As a necessary nutrient for fish growth, protein accounts for the highest proportion in the fish diet and is expensive. Although our team found that the effect of protein on the muscle hardness of grass carp was probably related to an increased collagen content, the mechanism for this effect has not been deeply explored. Moreover, few studies have explored the protein requirements of sub-adult grass crap (Ctenopharyngodon idella). Therefore, the effects of different dietary protein levels on the growth performance, nutritional value, muscle hardness, muscle fiber growth, collagen metabolism and related molecule expression in grass carp were investigated.

Methods

A total of 450 healthy grass carp (721.16 ± 1.98 g) were selected and assigned randomly to six experimental groups with three replicates each (n = 25/replicate), and were fed six diets with 15.91%, 19.39%, 22.10%, 25.59%, 28.53% and 31.42% protein for 60 d.

Results

Appropriate levels of dietary protein increased the feed intake, percentage weight gain, specific growth rate, body composition, unsaturated fatty acid content in muscle, partial free amino acid content in muscle, and muscle hardness of grass carp. These protein levels also increased the muscle fiber density, the frequency of new muscle fibers, the contents of collagen and IGF-1, and the enzyme activities of prolyl 4-hydroxylases and lysyloxidase, and decreased the activity of matrix metalloproteinase-2. At the molecular level, the optimal dietary protein increased collagen type I α1 (Colα1), Colα2, PI3K, Akt, S6K1, La ribonucleoprotein domain family member 6a (LARP6a), TGF-β1, Smad2, Smad4, Smad3, tissue inhibitor of metalloproteinase-2, MyoD, Myf5, MyoG and MyHC relative mRNA levels. The levels of the myostatin-1 and myostatin-2 genes were downregulated, and the protein expression levels of p-Smad2, Smad2, Smad4, p-Akt, Akt, LARP6 and Smad3 were increased.

Conclusions

The appropriate levels of dietary protein promoted the growth of sub-adult grass carp and improved muscle hardness by promoting the growth of muscle fibers, improving collagen synthesis and depressing collagen degradation. In addition, the dietary protein requirements of sub-adult grass carp were 26.21% and 24.85% according to the quadratic regression analysis of growth performance (SGR) and the muscle hardness (collagen content), respectively.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-022-00747-7.

The Genetic Characterization of a Novel Natural Recombinant Pseudorabies Virus in China

We sequenced the complete genome of the pseudorabies virus (PRV) FJ epidemic strain, and we studied the characteristics and the differences compared with the classical Chinese strain and that of other countries. Third-generation sequencing and second-generation sequencing technology were used to construct, sequence, and annotate an efficient, accurate PRV library. The complete FJ genome was 143,703 bp, the G+C content was 73.67%, and it encoded a total of 70 genes. The genetic evolution of the complete genome and some key gene sequences of the FJ strain and PRV reference strains were analyzed by the maximum likelihood (ML) method of MEGA 7.0 software. According to the ML tree based on the full-length genome sequences, PRV FJ strain was assigned to the branch of genotype II, and it showed a close evolutionary relationship with PRV epidemic variants isolated in China after 2011. The gB, gC, gD, gH, gL, gM, gN, TK, gI, and PK genes of the FJ strain were assigned to the same branch with other Chinese epidemic mutants; its gG gene was assigned to the same branch with the classic Chinese Fa and Ea strains; and its gE gene was assigned to a relatively independent branch. Potential recombination events were predicted by the RDP4 software, which showed that the predicted recombination sites were between 1694 and 1936 bp, 101,113 and 102,660 bp, and 107,964 and 111,481 bp in the non-coding region. This result broke the previously reported general rule that pseudorabies virus recombination events occur in the gene coding region. The major backbone strain of the recombination event was HLJ8 and the minor backbone strain was Ea. Our results allowed us to track and to grasp the recent molecular epidemiological changes of PRV. They also provide background materials for the development of new PRV vaccines, and they lay a foundation for further study of PRV.

Effects of Dietary Zinc Sources on Growth Performance and Gut Health of Weaned Piglets

The present study aimed to investigate the effects of dietary zinc sources on the growth performance and gut health of weaned piglets. In total, 96 Duroc × Landrace × Yorkshire (DLY) weaned piglets with an initial average body weight of 8.81±0.42kg were divided into four groups, with six replicates per treatment and four pigs per replicate. The dietary treatment groups were as follows: (1) control group, basal diet; (2) zinc sulphate (ZnSO4) group, basal diet +100mg/kg ZnSO4; (3) glycine zinc (Gly-Zn) group, basal diet +100mg/kg Gly-Zn and (4) zinc lactate group, and basal diet +100mg/kg zinc lactate. The whole trial lasted for 28days. Decreased F/G was noted in the Gly-Zn and zinc lactate groups (p<0.05). The zinc lactate group had a lower diarrhea rate than the control group (p<0.05). Moreover, the ZnSO4, Gly-Zn, and zinc lactate groups had significantly higher apparent total tract digestibility of dry matter (DM), crude protein (CP), ether extract (EE), crude ash, and zinc than the control group (p<0.05). The Gly-Zn and zinc lactate groups had higher jejunal villus height and a higher villus height:crypt depth ratio than the control group (p<0.05). In addition, the ZnSO4, Gly-Zn and zinc lactate groups had a significantly lower mRNA expression level of jejunal ZRT/IRT-like protein 4 (ZIP4) and higher mRNA expression level of jejunal interleukin-1β (IL-1β) than the control group (p<0.05). The mRNA expression level of jejunal zinc transporter 2 (ZNT2) was higher and that of jejunal Bcl-2-associated X protein (Bax) was lower in the Gly-Zn and zinc lactate groups than in the control group (p<0.05). Moreover, the zinc lactate group had a higher count of Lactobacillus spp. in the cecal digesta and higher mRNA expression levels of jejunal occludin and mucin 2 (MUC2) than the control group (p<0.05). In conclusion, dietary supplementation with 100mg/kg ZnSO4, Gly-Zn, or zinc lactate could improve the growth performance and gut barrier function of weaned piglets. Dietary supplementation with organic zinc, particularly zinc lactate, had the best effect.

Lysine deficiency impaired growth performance and immune response and aggravated inflammatory response of the skin, spleen and head kidney in grown-up grass carp (Ctenopharyngodon idella)

This dissertation was primarily focused on the immune response, inflammatory response and molecular mechanisms in the skin, head kidney and spleen of grown-up grass carp (Ctenopharyngodon idella). Six iso-nitrogen diets differing in lysine concentrations (5.6, 8.5, 11.6, 14.4, 17.5 and 20.7 g/kg) were fed to 540 grass carp (164.85 ± 0.79 g) for 60 d. After that, grass carp were challenged by Aeromonas hydrophila for 6 d. This study revealed that lysine deficiency (1) suppressed the growth performance of the fish and decreased their ability to resist skin lesion morbidity, (2) impaired the immune organ^'s immune response by decreasing the gene expressions of mucin, liver-expressed antimicrobial peptide (LEAP)-2B, β-defensin-1 and LEAP-2A and the production of antibacterial compounds of grown-up grass carp, and (3) aggravated the inflammatory response of immune organs in the fish by increasing the gene expressions of pro-inflammatory cytokines (interferon γ2 [IFN-γ2], tumor necrosis factor α [TNF-α], interleukin [IL]-15, IL-17D, IL-12p40, IL-6 and IL-8) and down-regulating anti-inflammatory cytokines (IL-11, transforming growth factor β1 [TGF-β1], IL-10 and IL-4/13A), which were tightly correlated with signal transducer and activator of transcription (STAT)1 and STAT3 signaling pathway, respectively. The different phenomenon in the skin, spleen and head kidney of fish may be correlated with the difference in gene subtype. In addition, using quadratic regression analysis of percent weight gain (PWG), skin lesion morbidity, and the lysozyme activities in the spleen and head kidney, the dietary lysine requirements for grown-up grass carp were estimated to be 13.58, 13.51, 14.56 and 14.18 g/kg, respectively.

Genetic characterization of a novel porcine reproductive and respiratory syndrome virus type I strain from southwest China

Porcine reproductive and respiratory syndrome (PRRS) is one of the most economically devastating viral diseases in the global pig industry. Recently, we isolated and plaque-purified porcine reproductive and respiratory syndrome virus (PRRSV) strain SC2020-1 from "aborted piglets" on a farm in Sichuan, China. To investigate the molecular biological characteristics of this strain, it was subjected to genome sequencing and analysis. The full-length genome sequence of strain SC2020-1 was 87.7% identical to that of the Lelystad strain (PRRSV type I protoype strain) and 82.2-84.8% identical to PRRSV type I isolates from China. NSP2, ORF3, and ORF4 were the most variable regions and contained discontinuous deletions or insertions when compared to other PRRSV type I strains. Phylogenetic analysis of the complete genome sequence showed that SC2020-1 clustered with PRRSV type I but outside of the three previously described branches (Lelystad virus-like, Amervac PRRS-like, and BJEU06-1-like). The Nsp2 gene was in the same branch with EUGDHD strains from China. This is the first report of PRRSV type I infection associated with abortion in sows in southwest China. Close attention should be paid to the prevention and control of this evolving virus.

Validation of the TOLNet lidars during SCOOP (Southern California Ozone Observation Project)

Five TOLNet lidars participated to a validation campaign at the JPL-Table Mountain Facility, CA in August 2016. All lidars agreed within ±10% of each other and within ±7% of the ozonesondes. Centralized data processing was used to compare the uncertainty budgets. The results highlight the TOLNet potential to address science questions ranging from boundary layer processes to long range transport. TOLNet can now be seen as a robust network for use in field campaigns and long term monitoring.

Effect of high-fat diet on secreted milk transcriptome in midlactation mice

High-fat diet (HFD) during lactation alters milk composition and is associated with development of metabolic diseases in the offspring. We hypothesized that HFD affects milk microRNA (miRNA) and mRNA content, which potentially impact offspring development. Our objective was to determine the effect of maternal HFD on secreted milk transcriptome. To meet this objective, 4 wk old female ICR mice were divided into two treatments: control diet containing 10% kcal fat and HFD containing 60% kcal fat. After 4 wk on CD or HFD, mice were bred while continuously fed the same diets. On postnatal day 2 (P2), litters were normalized to 10 pups, and half the pups in each litter were cross-fostered between treatments. Milk was collected from dams on P10 and P12. Total RNA was isolated from milk fat fraction of P10 samples and used for mRNA-Seq and small RNA-Seq. P12 milk was used to determine macronutrient composition. After 4 wk of prepregnancy feeding HFD mice weighed significantly more than did the control mice. Lactose and fat concentration were significantly ( P < 0.05) higher in milk of HFD dams. Pup weight was significantly greater ( P < 0.05) in groups suckled by HFD vs. control dams. There were 25 miRNA and over 1,500 mRNA differentially expressed (DE) in milk of HFD vs. control dams. DE mRNA and target genes of DE miRNA enriched categories that were primarily related to multicellular organismal development. Maternal HFD impacts mRNA and miRNA content of milk, if bioactive nucleic acids are absorbed by neonate differences may affect development.

The relationship between dietary methionine and growth, digestion, absorption, and antioxidant status in intestinal and hepatopancreatic tissues of sub-adult grass carp (Ctenopharyngodon idella)

BACKGROUND

Methionine is an essential amino acid for fish. The present study was conducted to investigate the effects of dietary methionine on growth performance, digestive and absorptive ability, as well as antioxidant capacity in the intestine and hepatopancreas of sub-adult grass carp (Ctenopharyngodon idella).

RESULTS

Dietary methionine deficiency significantly decreased percentage weight gain (PWG), feed intake, feed efficiency and protein efficiency ratio, as well as activities of hepatopancreatic glutamate-oxaloacetate transaminase and muscle glutamate-pyruvate transaminase in sub-adult grass carp (P < 0.05). Furthermore, methionine deficiency significantly reduced activities of trypsin, lipase and amylase in the intestine, Na+/K+-ATPase, alkaline phosphatase and γ-glutamyl transpeptidase in three intestinal segments, and creatine kinase (CK) in the proximal intestine (P < 0.05). However, an unexplained and significant increase in CK activity in the mid intestine was associated with dietary methionine deficiency. Malondialdehyde and protein carbonyl contents in the intestine and hepatopancreas were significantly increased by methionine deficiency (P < 0.05), whereas anti-hydroxyl radical capacity in the hepatopancreas and intestine, and anti-superoxide anion capacity in the intestine, were significantly decreased by methionine deficiency (P < 0.05). Moreover, methionine deficiency significantly decreased superoxide dismutase and glutathione reductase activities, glutathione contents in the hepatopancreas and intestine, as well as glutathione peroxidase activity in the intestine (P < 0.05), whereas it significantly increased activities of catalase in the hepatopancreas and glutathione-S-transferase in the hepatopancreas and intestine (P < 0.05).

CONCLUSIONS

The present results demonstrated that dietary methionine deficiency induced poor growth, and decreased digestive and absorptive function and antioxidant capacity in the hepatopancreas and intestine of sub-adult grass carp. Methionine requirements for sub-adult grass carp (450-1, 170 g) based on PWG, intestinal trypsin, and hepatopancreatic anti-hydroxyl radical activities were estimated to be 6.12 g/kg diet (21.80 g/kg protein), 6.99 g/kg diet (24.90 g/kg protein) and 5.42 g/kg diet (19.31 g/kg protein), respectively, in the presence of 1.50 g cysteine/kg (5.35 g/kg protein).

Growth, digestive and absorptive capacity and antioxidant status in intestine and hepatopancreas of sub-adult grass carp Ctenopharyngodonidella fed graded levels of dietary threonine

Background

This study was carried out to investigate effects of threonine levels on growth, digestive and absorptive capacity and antioxidant status in intestine and hepatopancreas of sub-adult grass carp (Ctenopharyngodonidella).

Results

Weight gain, specific growth rate, feed intake and feed efficiency were significantly improved by dietary threonine (P < 0.05). Intestinal activities of trypsin, chymotrypsin, alpha-amylase, lipase, alkaline phosphatase, γ-glutamyl transpeptidase and creatine kinase took the similar trends. Contents of malondialdehyde and protein carbonyl in intestine and hepatopancreas were significantly decreased by dietary optimal threonine supplementation (P < 0.05). Anti-superoxide anion capacity, anti-hydroxyl radical capacity, glutathione content and activities of superoxide dismutase, catalase and glutathione-S-transferase in intestine and hepatopancreas were enhanced by dietary threonine (P < 0.05).

Conclusions

Dietary threonine could improve growth, enhance digestive and absorptive capacity and antioxidant status in intestine and hepatopancreas of sub-adult grass carp. The dietary threonine requirement of sub-adult grass carp (441.9-1,013.4 g) based on weight gain was 11.6 g/kg diet or 41.5 g/kg of dietary protein by quadratic regression analysis.

The influence of graded levels of available phosphorus on growth performance, muscle antioxidant and flesh quality of young grass carp (Ctenopharyngodon idella)

Growth, muscle composition, meat quality characteristics and antioxidant capacity in muscle of young grass carp (Ctenopharyngodon idella) (initial weight 282.9 ± 3.3 g) fed graded levels of phosphorus (1.0, 2.5, 3.8, 5.6, 7.8 and 9.5 g/kg diet) for 8 wk were investigated. Results indicated that percentage weight gain, feed intake, feed efficiency, serum phosphorus and alkaline phosphatase were improved with optimal phosphorus supplementations (P < 0.05). Muscle protein content and water holding capacity were significantly elevated, while moisture, lipid and ash contents were significantly decreased with dietary phosphorus to a certain level (P < 0.05). The meat shear force value and hydroxyproline content were not influenced by different levels of phosphorus. Muscle anti-hydroxyl radical, superoxide dismutase, catalase, glutathione S-transferase activities and glutathione content were significantly improved (P < 0.05). Conversely, anti-superoxide anion, glutathione reducase and glutathione peroxidase activities were decreased (P < 0.05) with dietary phosphorus to a certain level. These results indicated that suitable dietary phosphorus improved growth performance, meat quality and muscle antioxidant capacity. Dietary available phosphorus requirement of young grass carp for percentage weight gain was 4.0 g/kg diet.

Effect of dietary arginine on the immune response and gene expression in head kidney and spleen following infection of Jian carp with Aeromonas hydrophila

This study was conducted to test the hypothesis that elevated dietary arginine enhances immunity of juvenile Jian carp (Cyprinus carpio var. Jian). Fish were fed graded levels of dietary arginine for 9 weeks. Subsequently, a challenge test was conducted by injection of Aeromonas hydrophila. Head kidney and spleen weights, as well as erythrocyte and leukocyte counts were significantly influenced by dietary arginine levels. A similar trend was also observed for hemagglutination titre, serum lysozyme activity, IgM concentration, C3 and C4 content. The highest survival rates following A. hydrophila infection were obtained in fish fed the diets containing arginine at 16.1-21.9 g/kg diet. Phagocytic activity of leukocytes was significantly enhanced by dietary arginine supplementation. In contrast, acid phosphatase activity significantly decreased with dietary arginine levels. Dietary arginine levels did not have a significant effect on the total iron-binding capacity. Gene expression of TNF-α and TGF-β in head kidney significantly increased with dietary arginine levels up to 21.9 g/kg diet, and decreased thereafter. Fish fed the basal diet exhibited the highest IL-10 mRNA expression level. Gene expression of IL-1β and TOR increased with dietary arginine addition, reaching a plateau at 18.5 and 21.9 g arginine/kg diet, respectively. In spleen, higher IL-1β and TNF-α gene expressions were obtained in fish fed the diets containing 24.5 g arginine/kg diet than in fish fed the other dietary treatments. TGF-β mRNA expression levels were significantly lower in fish fed the diets containing ≤21.9 g arginine/kg diet. IL-10 and TOR mRNA expression levels were lower in fish fed 16.1 g arginine/kg diet, while 4E-BP mRNA expression levels increased with dietary arginine levels up to 12.7 g/kg diet and decreased thereafter. Our results indicate that arginine has beneficial effects on regulating mRNA expression of inflammatory cytokines, as well as TOR and 4E-BP and improving humoral and cellular immunity, therefore enhancing disease resistance of fish.

Dietary tryptophan modulates intestinal immune response, barrier function, antioxidant status and gene expression of TOR and Nrf2 in young grass carp (Ctenopharyngodon idella)

The present research evaluated the effects of dietary tryptophan (Trp) on growth performance, intestinal mucosal immune, barrier function and antioxidant capacity and gene expression of young grass carp (Ctenopharyngodon idella). Fish were fed six different experimental diets containing graded levels of Trp at 0.7(control), 1.7, 3.1, 4.0, 5.2 and 6.1 g kg(-1) diet for 8 weeks. The results showed that Trp supplementation significantly enhanced the percent weight gain (PWG), feed intake and feed efficiency (P < 0.05), and decreased the plasma ammonia content (PAC) (P < 0.05). After the 8-week feeding trail, an environmental copper exposure trail was conducted for 4 days. Results from the copper exposure trail showed that dietary Trp enhanced the lysozyme, acid phosphatase activities and complement 3 contents in the intestine of young grass carp (P < 0.05). In addition, Trp supplementation increased the copper/zinc superoxide dismutase (SOD1), glutathione peroxidase (GPx) activities and glutathione contents (P < 0.05), and decreased the protein carbonyl and malondialdehyde contents (P < 0.05). Furthermore, the relative gene expression levels of interleukin 10, transforming growth factor-β1, occludin, zonula occludens 1, claudin-b, -c, and -3, SOD1, GPx and NF-E2-related factor 2 in the intestine were significantly up-regulated with increasing of dietary Trp up to a certain level (P < 0.05). Conversely, the mRNA levels of tumor necrosis factor α, interleukin 8, target of rapamycin, Kelch-like-ECH-associated protein 1, claudin-12 and -15a in the intestine were significantly down-regulated by Trp (P < 0.05). Collectively, appropriate dietary Trp level improves fish growth, intestinal immune response, barrier function and antioxidant status, and regulated the mRNA levels of related signal molecules of young grass carp. Based on the quadratic regression analysis of the PWG and PAC, the dietary Trp requirement of young grass carp (287-699 g) was estimated to be 3.81 g kg(-1) diet (12.7 g kg(-1) protein) and 3.89 g kg(-1) diet (13.0 g kg(-1) protein), respectively.

Effects of dietary isoleucine on the immune response, antioxidant status and gene expression in the head kidney of juvenile Jian carp (Cyprinus carpio var. Jian)

This study was conducted to evaluate the effects of dietary isoleucine (Ile) on the immune response, antioxidant status and gene expression in the head kidney of juvenile Jian carp (Cyprinus carpio var. Jian). Six semi-purified isonitrogenous diets (4.2, 7.0, 9.5, 11.9, 13.9 and 16.9 g Ile kg(-1) diet) were fed to Jian carp (6.9 ± 0.03 g) for 60 days. The results showed that Ile supplementation improved the head kidney index, red and white blood cell counts, anti-hydroxyl radical capacity and the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase (P < 0.05), and decreased the malondialdehyde, protein carbonyl and glutathione contents in the head kidney (P < 0.05). After a 60 day feeding trial, an Aeromonas hydrophila challenge study was conducted for 17 days. Differences in survival rate, leucocyte phagocytic activity, serum lysozyme activity, acid phosphatase activity, haemagglutination titre, complement components 3 and 4, immunoglobulin M level and A. hydrophila agglutination antibody titre followed the same trend as that of the head kidney index (P < 0.05). Furthermore, real time polymerase chain reaction revealed that relative mRNA expression of transforming growth factor β2 and target of rapamycin (TOR) in the head kidney significantly increased with increasing Ile levels (P < 0.05). Conversely, the relative mRNA expression of tumour necrosis factor α, interleukin 10 and eIF4E-binding protein (4E-BP) in the head kidney showed a downward trend (P < 0.05). Collectively, this study indicates that dietary Ile improves the fish immune response, regulates the antioxidant status and cytokine, TOR and 4E-BP gene expression in the head kidney.

Porcine satellite cells are restricted to a phenotype resembling their muscle origin

Muscles in most domestic animals differ in function and growth potential based largely on muscle fiber type composition. Though much is known about satellite cells (SC), information is limited regarding how populations of SC differ with muscle fiber type, especially in pigs. Therefore, the objective of this study was to isolate and culture SC from red (RST) and white (WST) portions of the semitendinosus muscle of neonatal and adult pigs and determine their capacity to proliferate, differentiate, and express various myosin heavy chain (MyHC) isoforms in vitro. Porcine satellite cells were isolated from RST and WST muscles of 6-wk-old and adult (>6-mo-old) pigs and cultured under standard conditions. Muscle from neonatal pigs yielded nearly 10 times more (P < 0.001) presumptive satellite cells as those from adult pigs, with fusion percentages close to 60% for the former. The RST yielded more (P < 0.001) SC per gram muscle compared to WST, 8.1 ± 0.2 × 10(4) cells versus 6.7 ± 0.1 × 10(4) cells/gram muscle in young pigs, and 9.7 ± 0.4 × 10(3) cells versus 5.5 ± 0.4 × 10(3) cells/gram muscle in adult pigs, respectively. Likewise, satellite cells from RST proliferated faster (P < 0.001) than those from WST across both ages, as indicated by a shorter cell doubling time, 18.6 ± 0.8 h versus 21.3 ± 0.9 h in young pigs, and 23.2 ± 0.7 h versus 26.7 ± 0.9 h in adult pigs, respectively. As a result of shorter times to confluence, satellite cells from RST also formed myotubes earlier than those SC originating from WST. Once induced, however, SC from WST differentiated and fused faster (P < 0.05) as evidenced by fusion percentage within the first 24 h, 41.6% versus 34.3%, respectively; but reached similar ultimate fusion percentages similar to WST by 48 h. Over 90% of MyHC expressed in maximally fused SC cultures from both RST and WST was restricted to the embryonic isoform. Type IIX MyHC mRNA was not detected in any culture. Myotube cultures from RST expressed more (P < 0.01) Type I MyHC isoform mRNA than those from WST, whereas those cultures from WST expressed more (P < 0.05) Type II (including Types IIA and IIB) MyHC transcripts. These data show SC cultures from porcine fast and slow muscles express MyHC profiles largely reflective of their muscle of origin and suggest satellite cells are partially restricted to a particular muscle phenotype in which they are juxtapositioned. Understanding the molecular nature of these intrinsic control mechanisms may lead to improved strategies for augmenting meat animal growth or muscle regeneration.

Meat Science and Muscle Biology Symposium: stem cell niche and postnatal muscle growth

Stem cell niche plays a critical role in regulating the behavior and function of adult stem cells that underlie tissue growth, maintenance, and regeneration. In the skeletal muscle, stem cells, called satellite cells, contribute to postnatal muscle growth and hypertrophy, and thus, meat production in agricultural animals. Satellite cells are located adjacent to mature muscle fibers underneath a sheath of basal lamina. Microenvironmental signals from extracellular matrix mediated by the basal lamina and from the host myofiber both impinge on satellite cells to regulate their activity. Furthermore, several types of muscle interstitial cells, including intramuscular preadipocytes and connective tissue fibroblasts, have recently been shown to interact with satellite cells and actively regulate the growth and regeneration of postnatal skeletal muscles. From this regard, interstitial adipogenic cells are not only important for marbling and meat quality, but also represent an additional cellular component of the satellite cell niche. At the molecular level, these interstitial cells may interact with satellite cells through cell surface ligands, such as delta-like 1 homolog (Dlk1) protein whose overexpression is thought to be responsible for muscle hypertrophy in callipyge sheep. In fact, extracellular Dlk1 protein has been shown to promote the myogenic differentiation of satellite cells. Understanding the cellular and molecular mechanisms within the stem cell niche that regulate satellite cell differentiation and maintain muscle homeostasis may lead to promising approaches to optimizing muscle growth and composition, thus improving meat production and quality.

An Intelligent Bone Spinal Disc Implant for Asian Population

There is a high level of patient appeal and physician acceptance of motion preservation as the future treatment of symptomatic and painful degenerative disc disease. However, spinal artificial disc replacement is still in its infancy. We have been designing, developing and evaluating motor articulated implants for use in bone-spinal disc surgery for Asian population. Apart from the generally smaller built of Asian compared to the American and European, the motor articulated implant should make provisions for the difference in eastern and western lifestyles. In the eastern world, we generally sit on a lower platform. Frequent activities like squatting result in a different stress-strain profile on the lower spine of an Asian compared to that of the Westerner. Preserving the motion of flexion bending in human lumbar spine is important. The motion preservation characteristics have to be maintained without compromising device durability, bone-device interfaces and corrective intervention. A systematic approach was adapted in designing the implant. Physical size of the implant should replicate the actual Intravertebral Disc (IVD). Implant should be able to fit into vertebral body. This is aid by shaping the spine vertebral body to accommodate the implant. A motor articulated implant must have suitable spaces for the implementation of sensors to detect forces and motors to control the motion of the prototype. The device must be able to receive real-time sensory inputs which can then modulate the implant orientation in bending accordingly. A prototype of the implant device has been fabricated to study its motion preservation capabilities. The prototype comprises of a parallel manipulator mechanism where the top plate is linked to the base plate by independent kinematic chains. The mechanical structure is made of Aluminium 6061. The mechanical parts were also put through the chemical process of anodizing for a good finishing surface. In the prototype device, we used three DC micromotors (Faulhaber) for actuation. Due to the small dimension, fibre optics pressure sensors were used. Three customized sensors were developed, calibrated and deployed on the upper plate. A PIC32 microprocessor was used to compute the compliance motion of the prototype when subjected to forces during flexion bending motion. The computer simulation of the kinematics of the parallel mechanism demonstrated the implant's flexion bending capabilities. We are conducting biomechanical experiments with this prototype implant deployed between L3–L5 of an artificial spinal column. The prototype device should achieve motion preservation capabilities comparable to the existing implants. More computer simulation will also be conducted to improve the mechanical design and control mechanisms of the proposed disc implant.

The molecular regulation of muscle stem cell function

Muscle satellite cells are responsible for the postnatal growth and robust regeneration capacity of adult skeletal muscle. A subset of satellite cells purified from adult skeletal muscle is capable of repopulating the satellite cell pool, suggesting that it has direct therapeutic potential for treating degenerative muscle disease. Satellite cells uniformly express the transcription factor Pax7, and Pax7 is required for satellite cell viability and to give rise to myogenic precursors that express the basic helix-loop-helic (bHLH) transcription factors Myf5 and MyoD. Pax7 activates expression of target genes such as Myf5 and MyoD through recruitment of the Wdr5/Ash2L/MLL2 histone methyltransferase complex. Extensive genetic analysis has revealed that Myf5 and MyoD are required for myogenic determination, whereas myogenin and MRF4 have roles in terminal differentiation. Using a Myf5-Cre knockin allele and an R26R-YFP Cre reporter, we observed that in vivo about 10% of satellite cells only express Pax7 and have never expressed Myf5. Moreover, we found that Pax7(+)/Myf5(-) satellite cells give rise to Pax7(+)/Myf5(+) satellite cells through basal-apical asymmetric cell divisions. Therefore, satellite cells in skeletal muscle are a heterogeneous population composed of satellite stem cells (Pax7(+)/Myf5(-)) and satellite myogenic cells (Pax7(+)/Myf5(+)). Evidence is accumulating that indicates that satellite stem cells represent a true stem cell reservoir, and targeting mechanisms that regulate their function represents an important therapeutic strategy for the treatment of neuromuscular disease.

[A clinical analysis of 102 cases of chronic n-hexane intoxication]

OBJECTIVE

Chronic n-hexane exposure can result in n-hexane intoxication which is mainly characterized by a series of manifestations of peripheral nerve lesions. The disease was sometimes misdiagnosed as "unknown multiple peripheral neuropathy". 102 cases of n-hexane intoxication were investigated and reported in order to call attention to the disease.

METHODS

All the 102 cases, male 30, female 72; age 17 - 29, mean (21 +/- 3) were n-hexane workers. During the hospitalization the following data were collected: medical history, neurological check up, electromyogram, electrocardiogram, serum biochemical analysis, ophthalmologic study and the metabolite of n-hexane- the urinary 2, 5-hexanedione level. The airborne n-hexane levels of the working environment were also measured.

RESULTS

The average incubation period of the 102 cases was (8.3 +/- 2.6) months. The average course of the disease was (12.1 +/- 4.2) months. Airborne n-hexane concentration of the working places ranged from 188.0 to 7,848.6 mg/m(3). The most common prodromes were headache, anorexia, dizziness and weight loss. The main clinical manifestations of the disease were ascending abnormal sensation. Sensory loss and dyskinesia began from the distant parts of the limbs. The patient had reduction or disappearance of tendon reflexes, weakness and muscle atrophy in the limbs. Electromyography showed a neuropathic pattern, which was parallel to the clinical symptoms and signs. Delayed worsening of symptoms and signs after cessation of n-hexane exposure was observed in some cases. All the 102 cases recovered totally after treatment with Vitamin B, Chinese traditional medicine, physical therapy and training.

CONCLUSION

The main lesion of the disease is multiple peripheral neuropathy. Diagnosis should be made according to the history of n-hexane exposure, the typical clinical manifestations of peripheral neuropathy as well as the neuropathic changes on electromyography. Therapeutic measures for peripheral neuropathy of other etiologies may be used and the prognosis is optimistic if correct diagnosis is made and further exposure stopped.

Laser ablation reveals regulation of ciliary activity by serotonergic neurons in molluscan embryos

Early in embryonic development, the pond snail Helisoma trivolvis exhibits a rotational behavior that is generated by beating of cilia in the dorsolateral and pedal bands. Although previous anatomical and pharmacological studies provided indirect evidence that a pair of serotonergic neurons, Embryonic Neurons C1 (ENC1s), is involved in regulating embryonic rotation, direct evidence linking ENC1 to ciliary function is still lacking. In the present study, we used laser microbeams to perturb ENC1 in vivo while monitoring ciliary activity in identified ciliary bands. A laser treatment protocol to specifically ablate ENC1 without damaging the surrounding cells was established. Unilateral laser treatment of ENC1 caused transient increases in the activity of the pedal and ipsidorsolateral cilia, lasting 30-50 min. In contrast, activity of cilia that were not anatomically associated with ENC1 was unaffected by laser treatment. Mianserin, an effective serotonin antagonist in Helisoma ciliated cells, decreased the overall CBF of pedal and dorsolateral cilia by reducing the occurrence of spontaneous CBF surges in these cilia. Finally, the cilioexcitatory action of ENC1 laser treatment was mimicked by serotonin and reduced in the presence of mianserin. These results suggest that laser treatment provokes a release of serotonin from ENC1, resulting in a prolonged elevation of activity in the target ciliary cells. We conclude that, in addition to their previously established role in regulating neurodevelopment, ENC1s also function as serotonergic motor neurons to regulate ciliary activity, and therefore the rotational behavior of early embryos.

[Study on clinical and molecular biological characteristics of infant acute leukemia]

OBJECTIVE

To study the clinical and molecular biological characteristics of infant acute leukemia (IAL).

METHODS

R and/or G banding technique was used for analysis of karyotype. DNA blotting for HRX gene rearrangement, and polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR) for fusion gene detection.

RESULTS

Twenty cases of IAL were detected. HRX gene rearrangement was found in 10 cases, including HRX/AF-4 fusion gene in 5, HRX/AF-9 fusion in 2, and HRX/ENL fusion in 1, HRX self-fusion mediated by alu-repeat homologous recombination and HRX/EEN fusion each in one (HRX/EEN is a novel fusion gene reported for the first time).

CONCLUSION

High frequency of HRX gene rearrangement occurred in IAL, which is characterised by a massive leukemia cell burden and 11q23 translocation, forming fusion genes, especially HRX/AF-4 (about 50%). The results are of important significance in guiding clinical treatment and approaching the etiology of IAL.

[Hepatitis B virus infection and aflatoxin exposure in the development of primary liver cancer]

OBJECTIVE

To investigate the role of hepatitis B Virus (HBV) infection and aflatoxin (AF) exposure in the development of primary liver cancer (PLC).

METHODS

A 10-year prospective case-control study was carried out in 737 HBsAg carriers and 699 HBsAg negative cases, and the aflatoxin B1 albumin adducts (AFB1-Alb) were detected in the serum of the cohort including 30 HBsAg postive cases and 150 control individuals according to the case-control study model (ratio 1:5) at random in the high prevalance area of PLC.

RESULTS

The average year-incidence rate was significantly higher in the HBsAg postive group (824.13/100,000) than in the control group (70.97/100,000, RR = 11.61). There was no significant difference in the incidence rate of other tumors between the two groups (P > 0.05). The serum positive rate of AFB1-Alb was significantly higher in the PLC group (76.67%) than in the control group (48.67%, OR = 3.47), and the serum concentration of AFB1-Alb was also significantly higher in the PLC group than in the control group (P < 0.01).

CONCLUSION

HBV infection and AF exposure are important etiological factors in the development of PLC and both result in carcinogenic synergy.

[Fluorescence-based semi-automated gene scan with microsatellite markers by multiplex PCR techniques]

OBJECTIVE

To develop a high output and low cost multiplex PCR approach to facilitating large scale gene scan and gene typing with microsatellite markers.

METHODS

5-15 pairs of primers of microsatellite loci were added in one single tube with 5ul reaction volume, containing 10 mmol/L Tris-HCl (pH8.3), 50 mmol/L KCl,0. 1mg/ml gelatin, 3.0 mmol/L MgCl2, 200micromol/L dNTPs (each), 0.25U Taq DNA polymerase, Taq Start antibody and DNA templates. PCR thermocycles were carried out on Perkin Elmer Gene Amp PCR System 9600 with touch-down algorithm (the annealing temperature was decreased by 0.5 C in each cycle) to meet the different demands of different primers.

RESULTS

Up to 10-15 loci were labeled by different fluorescents or by the same fluorescent, but their PCR amplification fragments did not overlap in size. Almost all target microsatellite loci were successfully co-amplified in a 5 microliter reaction volume,electrophoresized and analyzed in a single gel lane with Perkin Elmer ABI 373A DNA sequencer, and 9 microsatellite loci were well genotyped.

CONCLUSION

This high output and low cost genotyping protocol is applicable to gene mapping, human evolution and forensic analysis.

[Study of dominant negative effect of the PLZF-RARalpha against the wild-type RARalpha in acute promyelocytic leukemia]

OBJECTIVE

To explore the role of promyelocytic leukemia zinc finger (PLZF) gene on 11q23 and RARalpha gene on 17q21.

METHODS

Eight PLZF/RARalpha expression plasmids with deletions of different PLZF motifs were constructed by using PCR based-method.

RESULTS AND CONCLUSION

By transient co-transfection, it was confirmed that PLZF/RARalpha had a dominant negative effect against the wild-type RARalpha, the POZ domain of PLZF/RARalpha was responsible for the dominant negative effect and the PLZF/RARalpha may play certain role through a spatial interaction with POZ.

[Immunoglobulin super-gene family and its related genes in detecting MRD in ALL]

OBJECTIVE

To study the rearrangements of the immunoglobulin super-gene family and its related genes, as well as their application in the detection of minimal residual disease (MRD) in acute lymphoblastic leukemia (ALL).

METHODS

15 ALL cases including 11 B-ALLs and 3 T-ALLs were studied separately by using immunophenotype detection and molecular clonging methods.

RESULTS

Using DNA Southern blot analysis, we found that the rearrangement of IgH gene existed in 11 B-lineage ALL cases. The specific PCR band was visualized through amplification of the CDR3 region and J region of IgH gene. Furthermore, we sequenced the V-D-J junctional region of IgH gene in 3 B-lineage patients and synthesized two probes against the V-D-J junctional region in order to detect MRD. The hybridization results showing the sensitive of the two probes were 10(-4). In addition, we performed comparative study of MRD detection by using both T cell receptor (TCR) gamma gene as gene specific marker and SIL-TAL-1 fusion gene as tumor-specific marker in one T-ALL patient.

CONCLUSION

The rearrangements of IgH gene, as well as TCR gene and tumor fusion gene can be used as specific markers in the detection of MRD in ALL.

Long-term follow-up of minimal residual disease in childhood acute lymphoblastic leukemia patients by polymerase chain reaction analysis of multiple clone-specific or malignancy-specific gene markers

Two types of markers, namely the clone-specific markers including T-cell receptor (TCR) gamma, TCR delta, and Ig heavy-chain (IgH) gene rearrangements, and malignancy-specific fusion gene mRNA such as SIL-TAL-1, BCR-ABL, and HRX-partner genes, were investigated by molecular biology techniques in 65 Chinese patients with acute lymphoblastic leukemia (ALL). In combination, these markers were informative among 96% of patients. Minimal residual disease (MRD) was followed up in 23 of these patients with available materials over a period varying from 8 to 54 months with at least one leukemia-specific probe. In most children, MRD was decreased continuously to an ultimately undetectable level within 6 to 12 months after remission induction therapy. One patient exhibited low-level residual leukemic cells for 4 years before the MRD turned negative. Another patient remained in complete remission for 45 months, although a positive signal was detected at 34 months using TCR delta probe, but was negative with a TCR gamma marker which was positive at presentation. In three patients who relapsed, MRD either persisted through the clinical course or became positive and eventually increased 3-11 months before clinical relapse. These data suggested that the combined use of multiple gene markers is a valuable tool for the PCR-based MRD detection, since it can cover most ALL patients. Furthermore, long-term follow-up of MRD is helpful for determining the dosage as well as the period of maintenance chemotherapy and for predicting impending relapse.

[Junctional sequences of T cell receptor V delta 2-D delta 3 or D delta 2-D delta 3 rearrangements in acute lymphoblastic leukemia]

T-cell receptor (TCR) delta chain gene rearrangements were studied by polymerase chain reaction (PCR) analysis in 46 patients with acute lymphoblastic leukemia (ALL). Sixteen patients were found to have incomplete rearrangements of the TCR delta genes. Among them, 13 patients displayed V delta 2-D delta 3 rearrangement, while 3 had both V delta 2-D delta 3 and D delta 2-D delta 3 rearrangements. To determine the junctional sequence of TCR delta gene, PCR products from the 16 patients were sequenced directly or after M13 cloning. The results showed the junctional sequences of TCR delta gene are highly specific for each allele. This sequence diversity resulted from several factors including deletion of the 3' end of V delta 2 or D delta 2 segment and 5' end of D delta 3 segment, the presence of D delta 1 or D delta 2 sequences, insertion of N nucleotides and the association of P nucleotides with intact V delta 2 and D delta 3 segments. In addition, analysis of N-nucleotide contents revealed that the amount of GC was much larger than that of AT (70%: 30%), indicating the insertion of N nucleotide was not fully random. Our sequence data confirmed that the imcomplete rearrangement of TCR delta gene is an early event in the lymphoid cell ontogenesis, and its N sequences in V-(D)-J junctional region may be used as a specific marker of clonality to detect the minimal residual disease (MRD) in ALL.