Quadratic Regression Analysis Research Articles

Dietary Zanthoxylum bungeanum leaf powder improves growth performance and antioxidant capacity via Nrf2/HO-1 signaling pathway in broilers.

This study focused on the effects of dietary Zanthoxylum bungeanum leaves (ZBL) powder on the growth performance and antioxidant capacity via the Nrf2/HO-1 signaling pathway in broilers. The experiment adopted a single-factor completely random design, and 440 healthy one-day-old AA broiler chicks were randomly divided into four groups: the control group (CON) was fed a corn-soybean meal-based diet, the CZ1 group was fed a basic diet with 1% ZBL powder, the CZ2 group fed a basic diet with 2% ZBL powder, and the CZ3 group fed a basic diet with 3% ZBL powder. The experiment was divided into the starter period (1-21 d) and the grower period (22-42 d). There were five replicates per group in the starter period, with 22 chickens per replicate. The same grouping as in the starter period was used in the grower period, with 20 chickens per replicate. The results showed that the addition of ZBL powder to the diet had no adverse effects on the growth performance and morphological structure of the intestine of broiler chickens in the CZ1 and CZ2 groups (P > 0.05). Compared with the control group, the diet with 1% and 2% ZBL powder significantly increased the antioxidant indicators such as CAT, T-AOC, and T-SOD in the serum and liver tissue of broiler chickens, it upregulated the related genes expression of nuclear factor erythroid derived-2/heme oxygenase-1 (Nrf2/HO-1) signaling pathway such as Nrf2, NQO1, HO-1, SOD1, and CAT in the jejunal mucosa and enhanced the expression of ZO-1 and OCLN genes in the jejunal mucosa (P < 0.05). In conclusion, dietary supplementation with 1% and 2% of ZBL powder into the daily diet can enhance the body's antioxidant capacity by elevating antioxidant levels in both serum and liver, upregulates the expression of genes associated with the Nrf2/HO-1 signaling pathway in the jejunal mucosa, and helps maintain the integrity of the intestinal mucosal barrier. The optimal addition level of ZBL powder in the diet was determined by quadratic regression analysis to be 1.36%-1.60% during days 1-21 and 1.14%-1.50% during days 22-42.

Study on the influence of pipe effect on the vibration characteristics of electro-hydraulic exciter

In this paper, an electro-hydraulic exciter controlled by an alternating current distribution valve is proposed, and a systematic analysis of the influence of pipe effect on the vibration characteristics of the electro-hydraulic exciter is investigated by simulation and experiments. The vibration characteristics curves for different pipe parameters are obtained, and the relative errors between simulation and experiment are evaluated. Moreover, a significant regression model of pipe parameters and vibration characteristics of the electro-hydraulic exciter is established by using the quadratic regression analysis method and the Box-Behnken experiment design method. Significant differences in the influence of pipe parameters on vibration characteristics are obtained by ANOVA (Analysis of Variance), and the influence of pipe parameter interaction on vibration characteristics is discussed. The results show that the relative importance of pipe parameters on the vibration characteristics of electro-hydraulic exciter, from high to low, is as follows: pipe diameter, elastic modulus, and pipe length. Notably, there is also an interaction between the pipe parameters, and the significance of these interactions is ranked from high to low as the interaction between the layers of steel wire and diameter, the interaction between diameter and length, and the interaction between the layers of steel wire and length.

Effects of dietary digestible lysine levels in breeding Japanese quails on productive and reproductive performance, egg quality, blood metabolites and immune responses.

The vegetable-based diet alone does not provide the lysine (Lys) needed to maximize poultry productive performance. This experiment aimed to evaluate the effects of dietary digestible Lys (dLys) level on productive and reproductive performance, egg quality, blood metabolites and immune responses in breeding Japanese quails (Coturnix japonica). The experiment was conducted in a completely randomized design with 6 treatments, 5 replicates and 15 (12 females and 3 meals) 10-week-old breeding Japanese quails each. A basal diet was formulated to meet nutritional requirements of breeding quails except dLys. The basal diet was supplemented with graded (+0.82g/kg) levels of l-Lys-HCl, corresponding to dietary dLys levels of 0.690%, 0.755%, 0.820%, 0.885%, 0.950% and 1.015%. The experiment lasted for 12 weeks, which was divided into 3-4-week periods. Significant differences were observed for egg production (EP), egg mass (EM) and feed efficiency (FE) in response to increasing dietary dLys concentration with quadratic trends. The highest traits were observed in the birds fed with a diet containing 0.885% dLys. However, feed intake, egg quality, reproductive performance, blood metabolites and immune responses against sheep red blood cell inoculation were not significantly affected by increasing dietary dLys concentrations. The dLys requirements during 11-14, 15-18, 19-22 and 11-22 (overall) weeks of age for optimal EP, EM and FE, based on the quadratic broken-line regression analysis, were estimated 272, 265, 250 and 266; 293, 285, 264 and 279; and 303, 294, 281 and 293mg/bird/day, respectively. The dLys requirements vary depending on the EP phase and the trait being optimized. The estimated dLys requirement for FE was higher than those for EP and EM. During the peak stage of the first laying cycle, the dietary dLys level of 0.932% and a daily intake of 303mg dLys/bird are sufficient for optimal performance.

Compound effects of biochar application and irrigation on soil water and temperature transport

The issue of soil salinization poses a significant barrier to sustainable agricultural development, particularly in arid and semi-arid regions. Finding methods to enhance the quality of salinized soils while conserving water resources has become a pressing challenge. In arid and semi-arid environments, conserving water resources while maintaining soil health is a critical challenge. This study, conducted from 2021 to 2023, aimed to explore the combined effects of irrigation and biochar application on soil physicochemical properties, such as bulk density, porosity, and pH, as well as on Weighted Plane Soil Water Storage (WPSWS), soil temperature, and soil water evaporation. The experimental design included four irrigation levels, based on actual crop evapotranspiration (ETc): I1 (0.6 ETc), I2 (0.8 ETc), I3 (1.0 ETc), and I4 (1.2 ETc), coupled with four amounts of biochar application (AOBA) of 0, 10, 20, and 30 t ha−1, designated as C0, C10, C20, and C30, respectively. Through binary quadratic regression analysis, we sought to identify the optimal combination of irrigation amount and AOBA for enhancing soil quality. The results revealed that as AOBA increased from 10 to 30 t ha−1, soil bulk density decreased by 1.31–8.58% and soil pH by 0.23–1.31%. However, higher levels of AOBA adversely affected WPSWS, with the C10 treatment showing the maximum improvement in WPSWS, registering an average increase of 6.77, 7.49, and 11.16% compared to the C0, C20, and C30 treatments, respectively. We observed that an increase in irrigation amount significantly elevated accumulated soil evaporation (ASE) and WPSWS but led to a reduction in accumulated soil temperature (AST). The most notable soil quality improvements were recorded when irrigation levels were between 340 and 380 mm and AOBA ranged from 10 to 25 t ha−1. This study provides insights into the effective combination of biochar application and irrigation for optimizing soil resilience, thereby offering a sustainable approach to soil management in water-limited environments.

Effects of Dietary Inclusion of Enzymatically Hydrolyzed Compound Soy Protein on the Growth Performance and Intestinal Health of Juvenile American Eels (Anguilla rostrata).

The enzymatic hydrolysis of soybeans could enhance their application as an ingredient and alternative to fishmeal in aquafeeds. Here, a 10-week feeding trial was conducted to evaluate the impacts of different dietary inclusion levels of enzymatically hydrolyzed compound soy protein (EHCS) on the growth performance and intestinal health of juvenile American eels (Anguilla rostrata). Five experimental diets were formulated with graded EHCS inclusion levels at 0% (EHCS0), 8% (EHCS8), 16% (EHCS16), 24% (EHCS24), and 32% (EHCS32). Each diet was randomly assigned to four replicate tanks. The results showed that eels fed the EHCS8 diet exhibited superior growth performance, decreased serum lipid content, and increased immunity compared to those fed the EHCS0 diet. Eels fed the EHCS8 diet also displayed improved intestinal histology, enhanced antioxidant capacity and balance of intestinal microbiota as well as an enhanced proliferation of probiotics compared to those receiving the EHCS0 diet. Compared with eels fed the EHCS0 diet, those fed the EHCS16 diet exhibited comparable growth performance and values for the aforementioned markers. The quadratic regression analysis of weight gain rate and feed efficiency against the dietary EHCS inclusion levels determined the maximum levels of dietary EHCS inclusion for American eels range from 17.59% to 17.77%.

Impact of dietary lysine on growth, nutrient utilization, and intestinal health in triploid rainbow trout (Oncorhynchus mykiss) fed low fish meal diets

Lysine is one of the essential amino acids for fish growth and development. This study investigated the effect of dietary lysine on growth performance, digestion, and intestinal health of triploid rainbow trout (Oncorhynchus mykiss) (initial body weight: 9.00 ± 0.33 g) fed a low fish meal diet (15 %). Five dietary lysine levels (3.66 %, 3.84 %, 4.19 %, 4.32 %, and 4.55 %) were evaluated for 56 days, with three replicates of 30 fish per level. The results showed that the weight gain rate (198.55 %), specific growth rate (1.95), and VSI were maximized when the dietary lysine level was 4.19 %. The 4.19 % lysine group exhibited minimum moisture (66.66 %) and maximum crude protein (15.47 %), with no significant differences in crude lipid and ash contents. Growth factors mTOR and 4EBP-1, on the other hand, had the highest expression in the 4.19 % group, while IGF-1 and S6K1 peaked in the 4.32 % group. The anti-inflammatory factors TGF-β, NF-κB, IL-4, and IL-10 peaked at different levels and then decreased with increasing lysine levels. The pro-inflammatory factor IL-1β, on the other hand, had the lowest expression at the 4.19 % level. Based on quadratic regression analysis of specific growth rate, the lysine requirement of triploid O. mykiss in low fish meal diets was 4.24 %.

Replacing sea mud with attachment of suspension cage can improve growth and gut health for sea cucumber Apostichopus japonicus

During the suspension cage culture procedure, a substantial quantity of attachments from the suspension cage will amass in the tidal flats, resulting in environmental pollution and resource wastage. The aim of the present study was to explore the feasibility of using attachments of suspension cage (ASC) as a raw feed material for sea cucumbers. Different ASC concentrations (0, 25, 50, 75, and 100%) were used in sea cucumber (Apostichopus japonicus) fed for 60 d. Replacing sea mud with 50% ASC significantly improved sea cucumber growth, reduced the feed coefficient, significantly increased the activity of intestinal digestive enzymes, improved the activities of acid phosphatase and alkaline phosphatase, improved the intestinal structure, and enriched intestinal microbiome diversity (P&amp;lt;0.05). Replacing sea mud with 75% and 100% ASC significantly improved sea cucumber total antioxidant capacity and total superoxide dismutase (P&amp;lt;0.05).Furthermore, expressions of c-myc gene, mapk-7 gene and fgfr-1 gene, which all three growth genes, significantly increased in the 50% ASC treatment compared to that in the control; whereas, that of gdf-8 gene, a negative growth regulator, was inhibited (P&amp;lt;0.05). Based on the quadratic regression analysis for the weight gain rate, the appropriate levels of ASC substitution were estimated as to be 44.28%. The results suggested the potential of ASC as a new raw feed material for sea cucumbers.

Electromagnetic mixed convective flow of dusty hyperbolic tangent hybrid nanofluid over a stretching surface: A quadratic regression analysis using RSM

This article investigates the flow dynamics of electrically conducting dusty hyperbolic tangent fluid over a stretching sheet with thermal radiation and heat source effects. Moreover, the suspension of Aluminium oxide (Al2O3) and Tantalum nanoparticles in engine oil as base fluid at 300 K is considered. The flow and thermal dynamics are analysed using Xue and Hamilton Crosser's thermal conductivity models. Moreover, using various ranges, the effect of the Richardson number on forced, mixed and natural convection is examined. The governing partial differential equations of the flow model are converted into ordinary differential equations and then solved numerically using the boundary value problem solver BVP4C along with the shooting technique in MATLAB. The Xue model enhances the heat transfer rate by 3.55% compared to the Hamilton Crosser model ϕ1 = 0.03, ϕ2 = 0.01, R = 0.1, Q = 0.6, βt = 0.2, βv = 0.07. A moderate adjustment to the Richardson number can reduce skin friction by 0.889% in the case of forced convection. The absence of dust particles enhances the thermal and momentum boundary layer thickness. Tantalum nanoparticles outperform Al2O3 in terms of temperature and velocity. It is possible to regulate the temperature and velocity of the backflow by changing the heat source parameter and the nanoparticle volume percentage. The maximum achievable heat transfer rate in the fourth experimental run is 0.2609 when R = 2.5 and Q = 1.5 as determined by the quadratic regression analysis.

The effect of selenium on the intestinal health of juvenile grass carp based on the ERS-autophagy pathway

Selenium (Se), a trace element, is vital for the maintenance of cellular redox balance, thyroid hormone metabolism, inflammation, and immunity. Aeromonas hydrophila (A. hydrophila) is a common Gram-negative conditional pathogenic bacterium in fish culture, posing a serious threat to intensive aquaculture. Our study investigated the influence of dietary Se on the intestinal immune function of grass carp (Ctenopharyngodon idella) and the related regulatory mechanisms. The 2160 healthy juvenile grass carp (9.76 ± 0.005 g) were randomly assigned to 6 test groups of 6 replicates each, and fed graded selenomethionine (0.05, 0.20, 0.40, 0.61, 0.77, 0.98 mg Se/kg diet) for 70 days and then injected with A. hydrophila for a 6-day attack test. The results indicated that appropriate Se levels (0.40 mg/kg diet) alleviated intestinal damage caused by A. hydrophila and increased intestinal immune substances C3 and C4 levels as well as the activity of acid phosphatase (ACP) and lysozyme (LZ) (P > 0.05). Appropriate levels of Se (0.40 mg/kg-0.61 mg/kg diet) decreased intestinal pro-inflammatory cytokines (IFN-γ2, IL-6, IL-12p35, IL-17 A F and IL-17D) mRNA levels (P > 0.05) and increased intestinal anti-inflammatory factors (TGF-β1, IL-4/13A, IL-4/13B, IL-10 and IL-22) mRNA levels (P > 0.05) in juvenile grass carp. Further studies revealed that Se (0.40 mg/kg-0.61 mg/kg diet) inhibited intestinal endoplasmic reticulum stress (ERS)-related signaling pathway. Furthermore, we found that appropriate levels of Se (0.40 mg/kg-0.61 mg/kg diet) inhibited intestinal autophagy in juvenile grass carp, which may be related to ULK1, Beclin 1, ATG5, ATG12, LC3, and P62. In conclusion, appropriate levels of Se can alleviate intestinal inflammation and inhibit ERS and autophagy in juvenile grass carp. A quadratic regression analysis of intestinal ACP and LZ also indicated that the Se requirements of juvenile grass carp were 0.59 and 0.51 mg/kg, respectively.

Study on characteristics of the resistivity parameter and its coupling model of Chazangcuo copper-lead-zinc deposits based on microscopic analysis

Abstract The resistivity exploration has made a great contribution to prospecting at the macro level, but the resistivity exploration at the micro level is relatively weak. In this paper, the corresponding resistivity is analyzed through a geochemical element test, temperature and pressure test, water content and porosity test, and the resistivity parameter model of the rock and ore is established based on the response surface. The main conclusions and understandings obtained are as follows: with the increase of Cu-Pb-Zn content, the rock-ore resistivity shows an obvious decreasing trend, with sphalerite resistivity (72.8×10−2 Ω·m) &gt; pyrite resistivity (32.5×10−2 Ω·m) &gt; galena resistivity (76.5×10−3 Ω·m) &gt; chalcopyrite (11.3×10−3 Ω·m). The resistivity increases with the temperature, showing a quadratic term function trend increases. The resistivity decreases with the increase of pressure, decreasing rapidly at the beginning of loading and gradually slowing down. The resistivity decreases rapidly with the increase of water content and porosity in an exponential function trend. The degree of influence of four factors, temperature, pressure, porosity, and water content, on the resistivity of the ore samples, is the order of water content, porosity, pressure, and temperature. The coupled model of resistivity of Cu-Pb-Zn ores established by multivariate quadratic regression analysis is more reliable, and the predicted value of rock and ore resistivity is more consistent with the test data.

The regulatory effects of arginine on ovary development in the Chinese mitten crab Eriocheir sinensis

This study aimed to investigate the effects of arginine (Arg) on the vitellogenesis and ovarian maturation of Chinese mitten crab. Six isonitrogenous and isolipidic diets (1.83, 2.52, 3.26, 3.96, 4.81 and 5.52 % Arg) were fed to adult female Chinese mitten crab (60.05 ± 4.33 g). The feeding period lasted for eleven weeks. The results showed that gonadosomatic index of crabs increased with increasing dietary Arg concentrations from 1.83 % to 2.52 % and significantly decreased from 2.52 % to 5.52 %. The quadratic regression analysis based on gonadosomatic index estimated that the optimal Arg requirement for adult female crabs was 2.60 %. Dietary supplementation with 2.52 % Arg significantly increased the crude protein concentration in the ovary. A dose of 2.52 % Arg significantly decreased the vitellogenesis-inhibiting hormone (VIH) content in the hemolymph. Arg (2.52 %) significantly upregulated the Vg and protein kinase A (PKA) gene expressions and increased the cyclic adenosine monophosphate (cAMP) concentration in the hepatopancreas. Moreover, dietary supplementation with 2.52 % Arg significantly decreased the cyclic guanosine monophosphate (cGMP) concentration and downregulated protein kinase G (PKG) and p38 mitogen-activated protein kinase (p38 MAPK) gene expression. Arg at 2.52 % significantly increased hemolymph Vg content and the gene expression of the vitellogenin receptor (VgR). In conclusion, Arg at 2.52 % improved vitellogenesis and ovarian maturation by reducing the VIH content and regulating Vg expression via the cGMP/cAMP pathway.

The effect of heart rate variability on the choroidal vascularity of the optical coherence tomography and angiography in central serous chorioretinopathy.

To investigate the correlation between the autonomic nervous system and choroidal vascularity in patients with central serous chorioretinopathy (CSC), using heart rate variability (HRV) analysis, optical coherence tomography (OCT) and OCT angiography (OCTA). We retrospectively analyzed data of 25 patients with unilateral CSC (50 eyes, including the unaffected fellow eyes) and 25 healthy controls. The assessment involved a 5-minute HRV analysis encompassing both frequency and time domains, especially low frequency (LF), high frequency (HF), and LF/HF ratio. In OCT (12 × 9mm) and en-face OCTA (3 × 3mm) scans, we measured parameters including choroidal vascularity index (CVI), choroidal vessel density in the middle and deep layers, and choriocapillaris flow void. Regression analysis was conducted to elucidate the associations between HRV parameters and OCT/OCTA measurements. Normalized LF(LFnorm) and LF/HF ratios were higher in patients with CSC than in healthy controls. LFnorm and the log-transformed ratio of LF to HF [log(LF/HF)] demonstrated a significant and borderline correlation with CVI in the linear regression analysis (P = 0.040, R2 = 0.171, and P = 0.059, R2 = 0.147, respectively). Both CVI and deep choroid vessel density showed a more significant association with LFnorm and log (LF/HF) in the non-linear quadratic regression analysis than in the linear analysis (all, P < 0.04, R2 > 0.25). The frequency-domain parameters of HRV, including LFnorm and log (LF/HF), demonstrated a significant association with indicators reflective of large choroidal vessel luminal area on macular OCT/OCTA scans. This observation implies complicated modulation of choroidal blood flow by the autonomic nervous system in CSC.

A - 28 Relationship between Sleep and Symptom Severity during Initial Post-Injury Testing in High School Athletes

Abstract Purpose Examine the relationship between reported symptom severity and hours of sleep the night before completing the ImPACT Post-Injury 1 (PI-1) Post-Concussion Symptom Checklist. Method A sample of 414 high school (ages 14–17) athletes (188 females, 226 males) who completed the PI-1 pre-test ImPACT Post-Concussion Symptom Checklist and reported hours of sleep the night before testing, from 2019 to present, was analyzed. Responses were divided into two groups, ‚â§8 hours sleep (n = 253) and ≥ 8 hours sleep (n = 246), and compared to ratings of pre-test total symptom score (TS) and 22 individual symptoms (IS) using a correlation test (Pearon’s r). A quadratic regression analysis was completed combining both sleep groups (n = 414) to assess for a curvilinear relationship between reported sleep, IS, and TSS. Results There was a statistically significant negative correlation between ‚â§8 hours sleep and 15 IS (r = −0.292 to −0.141, p = &amp;lt;0.001 to 0.024) and TS (r = −0.272, p = &amp;lt;0.001). A statistically significant positive correlation was found between ≥8 hours sleep and 10 IS (r = 0.138 to 0.261, p = &amp;lt;0.001 to 0.030) and TS (r = 0.193, p = 0.002). A quadratic regression analysis confirmed a statistically significant quadratic relationship between hours of sleep and TSS (coefficient for the quadratic term was 1.030, p = &amp;lt;0.001) and for 15 IS (all p = &amp;lt;0.001). Conclusions A significant U-shaped relationship was found between high school athletes’reported hours of sleep and reported symptom severity at first post-concussion assessment. This is consistent with other research indicating that too much or too little sleep can be problematic.

Establishing the link between D-mannose and juvenile grass carp (Ctenopharyngodon idella): Improved growth and intestinal structure associated with endoplasmic reticulum stress, mitophagy, and apical junctional complexes

D-mannose, essential for protein glycosylation, has been reported to have immunomodulatory effects and to maintain intestinal flora homeostasis. In addition to evaluating growth performance, we examined the impact of D-mannose on the structure of epithelial cells and apical junction complexes in the animal intestine. All 1800 grass carp (16.20 ± 0.01 g) were randomly divided into six treatments with six replicates of 50 fish each and fed with six different levels of D-mannose (0.52, 1.75, 3.02, 4.28, 5.50 and 6.78 g/kg diet) for 70 d. The study revealed that D-mannose increased feed intake (P < 0.001) but did not affect the percent weight gain (PWG), special growth rate, and feed conversion ratio (P > 0.05). D-mannose supplementation at 1.75 g/kg increased crude protein content in fish and lipid production value (P < 0.05). D-mannose supplementation at 4.28 g/kg increased intestinal length, intestinal weight and fold height of grass carp compared to the control group (P < 0.05). This improvement may be attributed to the phosphomannose isomerase (PMI)-mediated enhancement of glycolysis. This study found that D-mannose supplementation at 4.28 or 3.02 g/kg reduced serum diamine oxidase activity or D-lactate content (P < 0.05) and improved cellular and intercellular structures for the first time. The improvement of cellular redox homeostasis involves alleviating endoplasmic reticulum (ER) stress through the inositol-requiring enzyme 1 (IRE1), RNA-dependent protein kinase-like ER kinase (PERK), and activating transcription factor 6 (ATF6) signaling pathways. The alleviation of ER stress may be linked to the phosphomannomutase (PMM)-mediated enhancement of protein glycosylation. In addition, ubiquitin-dependent [PTEN-induced putative kinase 1 (PINK1)/Parkin] and ubiquitin-independent [BCL2-interacting protein 3-like (BNIP3L), BCL2-interacting protein 3 (BNIP3), and FUN14 domain containing 1 (FUNDC1)] mitophagy may play a role in maintaining cellular redox homeostasis. The enhancement of intercellular structures includes enhancing tight junction and adherent junction structures, which may be closely associated with the small Rho GTPase protein (RhoA)/the Rho-associated protein kinase (ROCK) signaling pathway. In conclusion, D-mannose improved intestinal cellular redox homeostasis associated with ER stress and mitophagy pathways, and enhanced intercellular structures related to tight junctions and adherent junctions. Furthermore, quadratic regression analysis of the PWG and intestinal reactive oxygen species content indicated that the optimal addition level of D-mannose for juvenile grass carp was 4.61 and 4.59 g/kg, respectively.

Effect of dietary iron (Fe) supplementation on growth performance, hematological parameters and anti-oxidant responses of coho salmon Oncorhynchus kisutch (Walbaum, 1792) post-smolts

Effects of graded dietary iron (Fe) levels on coho salmon Oncorhynchus kisutch (Walbaum, 1792) post-smolts were assessed by determining the growth performance, Fe deposited in tissue, liver and serum antioxidant and immunity responses. Six experimental diets containing graded Fe (FeSO4·7 H2O as a Fe source) levels of 23.70, 42.40, 63.80, 89.30, 102.70 and 125.70 mg/kg were made and fed to three replicate groups of fish. A total 180 coho salmon post-smolts (188.28 ± 0.40 g) were randomly distributed to 18 floating cages (water volume 1000-L) with a flow-through system for 10 weeks, and fed three times daily until satiation. The results showed that the final body weight (FBW) and specific growth rate (SGR) were increased (p < 0.05) with increasing Fe content (from 23.70 to 89.30 mg/kg) in the diet, and significantly decreased (p < 0.05) in these traits were recorded when dietary Fe supplementation was further increased (from 89.30 to 125.70 mg/kg). However, feed conversion ratio (FCR) showed the opposite trend. Survival rate, morphological indices, and body proximate compositions did not differ significantly among the groups (p > 0.05). Nevertheless, the Fe contents in the whole body and muscle exhibited a steady rise (linear, p < 0.05), meanwhile, the liver Fe content significantly increased with increasing dietary Fe levels (linear and quadratic, p < 0.05). Increasing dietary Fe levels increased (p < 0.05) the hemoglobin (Hb), erythrocyte counts and hematocrit. In serum, lysozyme activity was significantly increased in 89.30 mg/kg diets ( p < 0.05). There was a significant increase in liver and serum superoxide dismutase (SOD) and catalase activities in response to the Fe levels in the diet, whereas a significant quadratic decrease in malondialdehyde levels (p < 0.05). Quadratic regression analysis of SGR and FCR against dietary Fe levels indicated that the optimal dietary Fe requirements were estimated to be 100.00 mg/kg and 104.17 mg/kg. Broken-line model analyses of the hepatic Fe content and SOD activity, the Hb content in the blood, and serum SOD activity against dietary Fe levels indicated that the optimal dietary Fe levels are 85.01, 87.53, 87.04, 91.23 mg/kg in Oncorhynchus kisutch post-smolts, respectively.

Effects of dietary melatonin supplementation on growth performance and intestinal health of rice field eel (Monopterus albus)

The objective was to assess the impact of melatonin supplementation on the growth performance and intestinal health of rice field eel, Monopterus albus. Three hundred and sixty fish (28.46 ± 0.24 g) were fed five diets supplemented with melatonin of 0, 30, 60, 120, and 240 mg/kg for 70 days. The study found that the variables FBW, WGR, SGR, and FCR exhibited a statistically significant quadratic relationship (P < 0.05) with the dietary melatonin concentrations, and the highest FBW, WGR and SGR as well as lowest FCR were observed in the 120 mg/kg melatonin group, digestive enzymes activities (such as amylase, trypsin, and lipase) also had significant quadratic relationship (P < 0.05), and the highest intestinal villus height and goblet cells were found in the 120 mg/kg diet (P < 0.01), melatonin in diets significantly increased SOD and CAT activities in serum, up-regulated the expression of anti-inflammatory factors (IL-10) and tight junction protein (ZO-1), and down-regulated the expression of pro-inflammatory factors (IL-1β, IL-8, IL-15, and TNF-α) in the gut, dietary melatonin improved the intestinal microflora compositions, in the group that supplementation a dosage of 120 mg/kg, there was a noticeable rise in the abundance of Firmicutes and the ratio of Firmicutes/Bacteroidota, compared with control group (P < 0.1). Conclusively, dietary supplementation of melatonin promoted growth performance, enhanced intestinal immune capacity and serum antioxidant level, and improved intestinal morphology properties and intestinal flora composition in M. albus. In conclusion, based on quadratic broken-line regression analysis of WGR and FCR, the optimal concentration of melatonin to be supplied is predicted to be 146–148 mg/kg.

Influence of increasing acclimation temperature on growth, digestion, antioxidant capacity, liver transcriptome and intestinal microflora of Ussruri whitefish Coregonus ussuriensis Berg

For effective restoration, conservation of Ussruri whitefish Coregonus ussuriensis Berg and coping with global climate change, effects of environmental temperature on Ussruri whitefish urgently need to be explored. In current study, the effects of different acclimation temperatures on the growth, digestive physiology, antioxidant ability, liver transcriptional responses and intestinal microflora patterns of Ussruri whitefish were investigated. Ussruri whitefish (15.20 g ± 1.23 g) were reared for 42 days under different acclimation temperatures, i.e., 10, 13, 16, 19, 22 and 25 °C, respectively. Result first determined 28 °C as the semi-lethal temperature in order to design the temperature gradient test. Highest main gain rate (MGR) and specific growth rate (SGR) were observed in fish group having acclimation temperature of 19 °C. Significantly decrease (P < 0.05) in triglyceride (TG) content appeared at 19 °C as compared to the 10 °C and 13 °C temperature groups. 19 °C notablely increased protease activities of stomach and intestine and intestinal lipase and amylase activities. 19 °C group obtained the highest activities of chloramphnicol acetyltransferase (CAT) and total antioxidant capacity (T-AOC) and higher activities of superoxide dismutase (SOD). The intestinal microflora composition was most conducive to maintaining overall intestinal health when the temperature was 19 °C, compared to 10 °C and 25 °C. Ussruri whitefish exposed to 10 °C and 25 °C possessed the lower Lactobacillus abundance compared to exposure to 19 °C. Temperature down to 10 °C or up to 25 °C, respectively, triggered cold stress and heat stress, which leading to impairment in intestinal digestion, liver antioxidant capacity and intestinal microflora structure. Liver transcriptome response to 10 °C, 19 °C and 25 °C revealed that Ussruri whitefish might require the initiation of endoplasmic reticulum stress to correct protein damage from cold-temperature and high-temperature stress, and it was speculated that DNAJB11 could be regarded as a biomarker of cold stress response.Based on the quadratic regression analysis of MGR and SGR against temperature, the optimal acclamation temperature were, respectively, 18.0 °C and 18.1 °C. Our findings provide valuable theoretical insights for an in-depth understanding of temperature acclimation mechanisms and laid the foundation for conservation and development of Ussruri whitefish germplasm resources.

Exploring the novel benefits of leucine: Protecting nitrite-induced liver damage in sub-adult grass carp (Ctenopharyngodon idella) through regulating mitochondria quality control

Leucine is an essential amino acid for fish. The ability of leucine to resist stress in fish has not been reported. Nitrite is a common pollutant in the aquatic environment. Therefore, we investigated the effects of dietary leucine on growth performance and nitrite-induced liver damage, mitochondrial dysfunction, autophagy, and apoptosis for sub-adult grass carp. A total of 450 grass carp (615.91 ± 1.15 g) were selected and randomly placed into 18 net cages. The leucine contents of the six diets were 2.91, 5.90, 8.92, 11.91, 14.93, and 17.92 g/kg, respectively. After a 9-week feeding trial, the nitrite exposure experiment was set up for 96 h. These results indicated that dietary leucine significantly promoted FW, WG, PWG, and SGR of sub-adult grass carp (P < 0.05). Appropriate levels of dietary leucine (11.91–17.92 g/kg) decreased the activities of serum parameters (glucose, cortisol, and methemoglobin contents, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, and lactate dehydrogenase), the contents of reactive oxygen species (ROS), nitric oxide (NO) and peroxynitrite (ONOO−). In addition, appropriate levels of dietary leucine (11.91–17.92 g/kg) increased the mRNA levels of mitochondrial biogenesis genes (PGC-1α, Nrf1/2, TFAM), fusion-related genes (Opa1, Mfn1/2) (P < 0.05), and decreased the mRNA levels of caspase 3, caspase 8, caspase 9, fission-related gene (Drp1), mitophagy-related genes (Pink1, Parkin) and autophagy-related genes (Beclin1, Ulk1, Atg5, Atg7, Atg12) (P < 0.05). Appropriate levels of dietary leucine (8.92–17.92 g/kg) also increased the protein levels of AMP-activated protein kinase (AMPK), prostacyclin (p62) and decreased the protein levels of protein light chain 3 (LC3), E3 ubiquitin ligase (Parkin), and Cytochrome c (Cytc). Appropriate levels of leucine (8.92–17.92 g/kg) could promote growth performance and alleviate nitrite-induced mitochondrial dysfunction, autophagy, apoptosis for sub-adult grass carp. Based on quadratic regression analysis of PWG and serum GPT activity, dietary leucine requirements of sub-adult grass carp were recommended to be 12.47 g/kg diet and 12.55 g/kg diet, respectively.

Visible-Light-Induced Acylative Pyridylation of Styrenes.

A visible-light-induced photocatalyst-free acylative pyridylation of styrenes with 4-acyl-1,4-dihydropyridines (DHPs) and 4-cyanopyridines has been described, featuring mild reaction conditions, a broad substrate scope, and good functional group tolerance. The reaction could also be performed under sunlight irradiation albeit with a slightly lower conversion. 4-Acyl-1,4-DHPs serve a dual role, acting as both a photoreductant to reduce the cyanopyridine to its radical anion intermediate and a radical precursor to produce the acyl radical. The mechanism was especially elucidated through the Hammett analysis, with the quadratic linear regression analysis by using radical dual parameters, σmb and σjj·. The findings from Hammett analysis further demonstrate that the rate-limiting step of the process is the single electron transfer between 4-acyl-1,4-DHPs and 4-cyanopyridines.

Liver transcriptome and physiological analyses preliminarily revealed the adaptation mechanisms of Amur grayling (Thymallus arcticus grubei, Dybowski, 1869) fry for dietary lipid nutrition.

The Amur grayling (Thymallus arcticus grubei Dybowski, 1869), a species of potentially economic and research value, is renowned for its tender meat, exquisite flavor, and high nutritional contents. This study was conducted to investigate the physiological adaptation mechanisms to dietary lipids in Amur grayling fry (with average initial weight 4.64±0.03 g). This study involved a 56-day feeding trial with diets containing varying lipid levels (9.07%, 12.17%, 15.26%, 18.09%, 21.16%, and 24.07%, designated as GL1 through GL6, respectively) to explore the impact of dietary lipids on growth performance, intestinal digestion, liver antioxidative function, and transcriptomic profiles. Results showed that The group receiving 18% dietary lipid exhibited a markedly higher weight gain rate (WGR) and specific growth rate compared to other groups, alongside a reduced feed conversion ratio (FCR), except in comparison to the 15% lipid group. Activities of lipase in pancreatic secretion and amylase in stomach mucosa peaked in the 18% lipid treatment group, indicating enhanced digestive efficiency. The liver of fish in this group also showed increased activities of antioxidative enzymes and higher levels of glutathione and total antioxidative capacity, along with reduced malondialdehyde content compared to the 9% and 24% lipid treatments. Additionally, serum high-density lipoprotein cholesterol levels were highest in the 18% group. Transcriptomic analysis revealed four significant metabolic pathways affected: Cholesterol metabolism, Fat digestion and absorption, PPAR signaling, and Fatty acid degradation, involving key genes such as Lipase, Lipoprotein lipase, Fatty acid-binding protein, and Carnitine palmitoyltransferase I. These findings suggest that the liver of Amur grayling employs adaptive mechanisms to manage excessive dietary lipids. Quadratic regression analysis determined the optimal dietary lipid levels to be 16.62% and 16.52%, based on WGR and FCR, respectively. The optimal dietary lipid level for juvenile Amur grayling appears to be around 18%, as evidenced by improved growth performance, digestive function, balanced serum lipid profile, and enhanced liver antioxidative capacity. Exceeding this lipid threshold triggers both adaptive and potentially detrimental liver responses.