Calcium-chelating peptides from rabbit bone collagen:characterization,identification and mechanism elucidation

This study aimed to characterize and identify calcium-chelating peptides from rabbit bone collagen and explore the underlying chelating mechanism.Collagen peptides and calcium were extracted from rabbit bone by instant ejection steam explosion(ICSE)combined with enzymatic hydrolysis,followed by chelation reaction to prepare rabbit bone peptide-calcium chelate(RBCP-Ca).The chelating sites were further analyzed by liquid chromatography-tandem mass(LC-MS/MS)spectrometry while the chelating mechanism and binding modes were investigated.The structural characterization revealed that RBCP successfully chelated with calcium ions.Furthermore,LC-MS/MS analysis indicated that the binding sites included both acidic amino acids(Asp and Glu)and basic amino acids(Lys and Arg),Interestingly,three binding modes,namely Inter-Linking,Loop-Linking and Mono-Linking were for the first time found,while Inter-Linking mode accounted for the highest proportion(75.1%),suggesting that chelation of calcium ions frequently occurred between two peptides.Overall,this study provides a theoretical basis for the elucidation of chelation mechanism of calcium-chelating peptides.

Genome-edited rabbits:Unleashing the potential of a promising experimental animal model across diverse diseases

Animal models are extensively used in all aspects of biomedical research,with substantial contributions to our understanding of diseases,the development of pharmaceuticals,and the exploration of gene functions.The field of genome modification in rabbits has progressed slowly.However,recent advancements,particularly in CRISPR/Cas9-related technologies,have catalyzed the successful development of various genome-edited rabbit models to mimic diverse diseases,including cardiovascular disorders,immunodeficiencies,agingrelated ailments,neurological diseases,and ophthalmic pathologies.These models hold great promise in advancing biomedical research due to their closer physiological and biochemical resemblance to humans compared to mice.This review aims to summarize the novel gene-editing approaches currently available for rabbits and present the applications and prospects of such models in biomedicine,underscoring their impact and future potential in translational medicine.

Effects of Incorporating Mango (Mangifera indica), Avocado (Persea americana) and Guava (Psidium guajava) Leaves Powder in the Ration on Growth Characteristics in Rabbits

A study conducted on burgundy rabbits evaluated the effects of rations containing mango (Mangifera indica), avocado (Persea americana) and guava (Psidium guajava) powder. For this purpose, 36 rabbits (20 males and 16 females) aged 60 to 70 days with an average weight of 1012 ± 133 g were divided randomly into 4 equal groups (T0, T1, T2 and T3) of 9 animals each according to body weight (bw). The rabbits were divided throughout the trial, the animals were fed, those of group T0 (control) with a standard feed without any type of leaf powder, while those of groups 1, 2 and 3 received the standard feed supplemented with Mangifera indica, Persea americana and Psidium guajava leaves powder at the rate of 0.5% respectively. After two months of treatment, the animals were fasted for 12 hours (20 h - 8 h) and sacrificed to evaluate carcass and digestive organ weights. The results revealed that the values of feed intake, live weight and weight gain were non-significantly (p > 0.05) increased in all animals regardless of the ration in reference to the control. The different leaves powder induced an increase in carcass yield in rabbits but this increase was only significant (p M. indica leaf powder (51.03 ± 0.24) as compared to the control (48.63 ± 0.74). Gut length was significantly increased in animals fed rations containing Psidium guajava and Persea americana leaves powder compared to the control. A significant increase in gut weight was observed in animals fed the Persea americana leaf supplemented ration. In general, mango leaf powder performed better than other types of powders.

Methods to Reduce the Hypoglycemic Mortality of Alloxan in Diabetic Rabbit Model

Objective: To explore an intervention method to reduce the mortality of alloxan diabetes model, and to preliminarily analyze the mechanism of alloxan induced animal death. Methods: Healthy New Zealand rabbits were randomly divided into injection group, control group, experimental group and blank group. The single injection group was injected with 100 mg/kg alloxan once. The control group was given 5% glucose solution and 100 mg/kg alloxan was injected in two times. The experimental group was given 5% glucose solution orally, 100 mg/kg alloxan, 7 mL 0.9% NaCl intravenously and 5 mL 5% glucose intraperitoneally immediately, and blood glucose was continuously monitored, 10 mL 5% glucose intravenously and 10 mL 5% glucose intraperitoneally every 4 h in the hypoglycemic stage. The blank group does nothing. Liver and kidney tissues at different time periods were stained with HE and organ index was evaluated. Results: 1) A single injection of 100 mg/kg alloxan without any intervention resulted in 100% mortality. Before modeling, oral administration of 5% glucose solution, divided into two injections of 100 mg/kg alloxan, mortality reached 100%;A single injection of 100 mg/kg alloxan and continuous intervention of normal saline and glucose for 20 h can significantly reduce the mortality of alloxan induced diabetic rabbit model. 2) Liver and kidney tissues were damaged in different degrees at different time periods, and liver and kidney indexes were significantly increased after alloxan injection compared with the normal group, with statistical significance (P > 0.05). Conclusion: 1) Every 4 hours of hypoglycemia, 10 ml 5% glucose was injected intravenously 10 ml 5% glucose intraperitoneally. It can reduce the death rate of alloxan diabetic rabbit model and shorten the time of blood glucose measurement. 2) After the injection of alloxan, acute lesions of liver and kidney may occur in different degrees, or one of the causes of acute death of experimental animals.

Effects of Carrot (Daucus carota) Leaves Powder on Reproductive and Growth Characteristics of Rabbit (Oryctolagus cuniculus) Does

The present study was conducted to evaluate the effects of carrot leaf powder in the diet on reproductive and growth characteristics in rabbits. Thirty sexually matured rabbits does of 8 months old, 3.00 to 3.20 kg, were divided into three groups of 10 rabbits each, which were comparable in terms of body weight. Throughout the experiment, the rabbits of group 1 (control group) were fed ad libitum with a feed not containing carrot leaf powder (control ration), while those of groups 2 and 3 received the control ration supplemented with carrot leaf powder in concentrations of 0.5% and 1% respectively. Data was collected on feed intake, weight gain, receptivity, fertility, gestation length of does, litter size, weight, viability and sex ratio of the young rabbits till 5 weeks post-partum. There was no significant (P > 0.05) difference in the fertility rate, gestation duration and sex ratio of the kits with reference to the control. Litter size at birth was not significantly (P > 0.05) influenced in does fed diets containing carrot leaf powder compared to the control. However, the reversed effects were observed at five weeks post-partum. The live weight of weaned kits and weight gain of rabbit does at birth were significantly (P < 0.05) increased in treated rabbits compared to the control. The supplementation of carrot leaf powder in feed can improve production performance in female rabbits, through their antioxidant activities thanks to their various components, thus fighting against oxidative stress effects to which animals are exposed both from endogenous and environmental sources.

Betaine addition to the diet alleviates intestinal injury in growing rabbits during the summer heat through the AAT/mTOR pathway

Background The aim of this experiment was to investigate the effect of different levels of betaine(Bet)inclusion in the diet on the intestinal health of growing rabbits under summer heat.A total of 100 weaned Qixing meat rabbits aged 35 d with body weight of 748.61±38.59 g were randomly divided into 5 treatment groups:control group(basal diet)and Bet groups(basal diet+0.75,1.0,1.5 or 2.0 g/kg Bet).The average daily temperature in the rabbitry during the experiment was 30.48°C and the relative humidity was 69.44%.Results Dietary addition of Bet had no significant effect on growth performance and health status of growing rabbits(P>0.05),but it increased ileal secretory immunoglobulin A content compared to the control under summer heat(P<0.05).Addition of 0.75 g/kg Bet up-regulated jejunal IL-4,down-regulated ileal TNF-αexpression(P<0.05).The addition of 1.0 g/kg Bet increased the villi height(VH)in the jejunum(P<0.05).Serum glucose levels were reduced,and the expression of SLC6A20 was up-regulated in jejunum and ileum of rabbits fed with 1.5 g/kg Bet(P<0.05).When added at 2.0 g/kg,Bet reduced serum HSP70 content,increased jejunal VH,and up-regulated duodenal SLC7A6,SLC38A2,mTOR and 4EBP-2 expression(P<0.05).Correlation analysis revealed that intestinal mTOR expression was significantly and positively correlated with SLC7A6,SLC38A2,SLC36A1 and IL-4 expression(P<0.05).Conclusions Dietary addition of Bet can up-regulate the expression of anti-inflammatory factors through the AAT/mTOR pathway,improve the intestinal immune function,alleviate intestinal damage in growing rabbits caused by summer heat,and improve intestinal health.

Chemical Composition of Pineapple Press Residues (Ananas comosus) and Effect on Growth Performance of Rabbit (Oryctolagus cuniculus)

With a view to improving rabbit production performance, a trial on the chemical composition of pineapple press residue (Ananas comosus) and the effect of its incorporation in the ration on rabbit growth performance (Oryctolagus cuniculus) was carried out at the KUATE Cunicole Farm in Bandjoun, in Western Cameroon. To do this, 36 rabbits of the local breed, aged 53 days with an average weight of 1337 ± 119 g were distributed and randomly assigned to 3 experimental rations corresponding respectively to treatments or batches T0, T1 and T2. The animals in treatment T0 received a ration containing no pineapple press residue, while those in treatments T1 and T2 received a ration containing 20% and 40% pineapple press residue, respectively. These residues were dried and ground for chemical composition analysis. The feed served as well as refusals from the previous day were weighed each morning to assess feed intake. The animals were weighed every 7 days to assess weight performance. At the end of the trial which lasted 7 weeks, the animals were fasted for 24 hours, then sacrificed to evaluate carcass characteristics and the relative weights of some digestive organs. The results of this study showed that pineapple press residues had a high crude fiber content (19.2%) and energy (2500 Kcal/kg DM). Their incorporation had no significant effect on feed intake and feed conversion ratio. The average live weight, weight gain and average daily weight gain of the animals receiving the ration with 20% inclusion of pineapple press residue were comparable to those of the control group and significantly higher than those of animals fed with 40% inclusion of pineapple residue. The highest carcass yields were obtained with rabbits fed 20% pineapple press residue in their ration. The cost of feed for the production of a kilogram live weight of rabbit tends to decrease with the ration incorporated with 20% pineapple press residue. Pineapple press residues constitute a by-product that can be recycled and their incorporation at 20% can increase rabbit growth performance and reduce production costs.

Awake rabbit model of ischemic spinal cord injury with delayed paraplegia:The role of ambient temperature

Background:Paraplegia after spinal cord ischemia is a devastating condition in the clinic.Here,we develop an awake rabbit model of spinal cord ischemia with delayed paraplegia and explore the influence of ambient temperature on the outcomes after injury.Methods:A total of 47 male rabbits were involved in the present study.Transient spinal cord ischemia was induced by occluding the infrarenal abdominal aorta of awake rabbits at different ambient temperatures.To find the optimal conditions for developing delayed paraplegia,hindlimb motor function after ischemia was evaluated between experiments.Results:The onset and magnitude of ischemic injury varied with the ambient temperature maintained during the peri-i schemia period.More serious spinal cord injury occurred when ischemia was induced at higher temperatures.At 18°C,25-minute ischemia resulted in 74%of rabbits developing delayed paraplegia.At a temperature of 28°C or higher,most of the animals developed acute paraplegia immediately.While at 13°C,rabbits usually regained normal motor function without paraplegia.Conclusion:This awake rabbit model is highly reproducible and will be helpful in future studies of delayed paraplegia after spinal cord ischemia.The ambient temperature must be considered while using this model during investigation of therapeutic interventions.

An Improved Artificial Rabbits Optimization Algorithm with Chaotic Local Search and Opposition-Based Learning for Engineering Problems and Its Applications in Breast Cancer Problem

Artificial rabbits optimization(ARO)is a recently proposed biology-based optimization algorithm inspired by the detour foraging and random hiding behavior of rabbits in nature.However,for solving optimization problems,the ARO algorithm shows slow convergence speed and can fall into local minima.To overcome these drawbacks,this paper proposes chaotic opposition-based learning ARO(COARO),an improved version of the ARO algorithm that incorporates opposition-based learning(OBL)and chaotic local search(CLS)techniques.By adding OBL to ARO,the convergence speed of the algorithm increases and it explores the search space better.Chaotic maps in CLS provide rapid convergence by scanning the search space efficiently,since their ergodicity and non-repetitive properties.The proposed COARO algorithm has been tested using thirty-three distinct benchmark functions.The outcomes have been compared with the most recent optimization algorithms.Additionally,the COARO algorithm’s problem-solving capabilities have been evaluated using six different engineering design problems and compared with various other algorithms.This study also introduces a binary variant of the continuous COARO algorithm,named BCOARO.The performance of BCOARO was evaluated on the breast cancer dataset.The effectiveness of BCOARO has been compared with different feature selection algorithms.The proposed BCOARO outperforms alternative algorithms,according to the findings obtained for real applications in terms of accuracy performance,and fitness value.Extensive experiments show that the COARO and BCOARO algorithms achieve promising results compared to other metaheuristic algorithms.

How Clever Miss Rabbit Was!

One day in autumn,Miss Rabbit went out to look for food.She found a big pumpkin very soon.She was so happy that she decided to carryit home.However,it was too heavy for her to carry.And soon she got tired.Just then,Mr.Panda came over on his bike.Miss Rabbit saw the wheels of the bike and came up with a good idea.

Effect of Chinese Herbal Feed Additive on Meat Quality of Rex Rabbit

[ Objective] The aim of this study was to provide a theoretical basis for population and application of Chinese herbal feed additive in the rex rabbit breeding. [ Methyl] 108 weaned -rex rabbits aged 40 days were divided into three groups with thirty -six each group. Group A were fed basal diet, while group B were fed basal diet supplemented with 0.3% Chinese herbal feed additive and group C were fed basal diet supplemented with 0.4% Chinese herbal feed additive. The meat quality indexes were measured when feeding to 150 age in days. [ Result] There was significant difference among pH value, water loss rate, storing loss rate and crude protein content in each group （P〈0.05）, but no significant difference was found in tenderness, cooking percentage, moisture content and crude fat content （ P 〉 0.05）. The total content of ami- no acids, essential amino acids and semi essential amino acids as well as main delicious amino acids was highest in group C accounting for 23.84%, 11.47% and 8.32% respectively, next came group B accounting for 20.94%, 10.64% and 6.81% respectively, and lowest in group C （ control group） accounting for 19.06%, 9.61% and 6.46% respectively. [ Conclusion] The Chinese herbal feed additive can improve meat quality of rex rabbit the best addition of 0.4%.

Effects of Diets with Different Corn-to-Soybean Ratios on Performance of Lactational Rex Rabbits

[ Objective] To study the effects of diets with different com-to-soybean ratios on production performance of lactational Rex rabbits and select the best feed formula. [Method] A total of 80 lactational healthy Rex rabbits （similar age, body weight and delivery time） were randomly divided into five groups, 16 in each group. The Rex rabbits in group I were fed with corn-based meal diet, group II with soybean-based meal diet, group III with the developed corn-soybean meal diet, group IV with corn-soybean meal free diet, and group CK with conventional corn-soybean meal diet. During the lactation period, the changes in the lactation performance, growth rate of baby rabbits, weight and feed costs were observed. [ Result] The lactation performance of mother rabbits and the growth rate of baby rabbits in the experimental groups were similar to that in the control group. The weaning survival rate of the group III was the highest, but it was not significantly higher than that of the control group. The weaning survival rate of the other three groups was lower than that of the control group （P〈0.05）. The weight loss of mother rabbits in the group I, II and III was not significantly different from that of the control group, but the weight loss of the group IV was higher than that of the control group （ P 〈 0.01 ）. [ Conclusion] Diets with appropriate corn-to-soybean ratios not only reduce feed costs but also give the best feeding effects.

Overexpression of hepatic plasminogen activator inhibitor type 1 mRNA in rabbits with fatty liver

INTRODUCTIONPlasminogen activator inhibitor type 1 ( PAI-I ), an approximately Mr 50000 glycoprotein, is the major physiological inhibitor of plasminogen activators. It is not only the priming factor for atherosclerosis and coronary thrombosis[1-3] , but also participates in the genesis of chronic hepatitis and liver fibrosis[4-11] . However, there has been no available report yet about the research of hepatic PAl-1 gene expression in hyperlipidemia and fatty liver. The present study aimed to explore the change of hepatic PAl-1 mRNA and its plasma activity by means of animal model.

Gene Expression Patterns in Different Wool Densities of Rex Rabbit Using cDNA Microarray

This study was carried out to identify gene expression patterns in different wool densities of rex rabbit. The mid-dorsal skin samples from 8 rex rabbits were studied. They were divided into two groups according to different wool densities. Total RNA was isolated and labeled by reverse transcription reaction with Cy5-dCTP and Cy3-dCTP for cDNA probe. The cDNA probe was hybridized with cDNA microarrays containing 14 601 rabbit’s genes. The differently expressed genes were analysed with the Gene Ontology （GO） classification and the pathway analysis. Hierarchical clustering was performed to clarify genes in association with different wool densities. The 2 657 differentially expressed genes were identified. Among them, 1 103 genes were functionally known genes, 687 genes were up-regulated and 419 were down-regulated. GO analysis indicated that these altered genes were associated with metabolism, signal transduction, cell cycle, cell adhesion, cell proliferation, cell division, apoptosis, and other processes. KEGG analysis showed that 95 signal pathways associated with up-regulated genes and 87 signal pathways associated with down-regulated genes had changed significantly （P0.05）. Some important differentially expressed genes in different wool densities of rex rabbit were identified, such as MMP2, TGF-β1, TGF-β2, IGF-1, ITGB1, RPS6KB1, BMP2, ActRIIB, CDK2, and CCNA2. Hierarchical clustering analysis separated the differentially expressed genes into 5 main characteristic groups. Data from cDNA microarray experiments clearly distinguished between group A and group B. Some important genes were identified, which might be useful in further study on wool density markers of rex rabbit.

Thickness Method for Measuring Hair Density of Rex Rabbit

[Objective] The paper was to characterize hair density by changes in hair thickness under certain pressure.[Method] Tile effects of weight of thickness tester and wafer urea at the hottom of presser foot on measurement results were studied, and the optimal measuring weight and wafer diameter was determined. The measurement results of hair thickness under the ahove condition were compared with the results of manual counting. Meanwhile, the effects of hair length and hair fineness on hair density were analyzed.[Result] The hair density obtained by manual count- ing had consistent change trend with the hair thickness measured under certain conditions. If the length and fineness of hairs were introduced for modification, the correlation between hair thickness and hair density would be better. There were little changes in hair length and finelless of rex rabbit, and their effects on hair thickness could be ignored under general condition. [Conclusion] It is completely feasible to characterize hair den- sity of rex rabbit by hair thickness under pressure.

Differential Expression of CCNA2 Gene and MMP2 Gene in Skin Tissue of Rex Rabbit with Different Fur Densities

[ Objective] The paper was to search for the molecular marker highly associated with fur density of rex rabbit. [ Method ] Experimental rex rabbits were divided into dense fur group and sparse fur group. The variation rule of gene expression in skin tissue of rex rabbits with different fur densities was detected using rabbit whole gene cDNA microarray. [ Result] A total of 2 657 genes with differential expression were detected by microarray test, including 1 106 genes with known function, 687 genes with up-regulated expression and 419 genes with down-regulated expression. The expression levels of multiple genes involving in cell proliferation, differentiation, apoptosis and migration had significant changes. MMP2 gene had high expression in skin tissue of rex rabbits in dense fur group, which was 8. 195 times of gene expression in sparse fur group ; CCNA2 gene had low expression in skin tissue of rex rabbit in dense fur group, which was 0. 143 times of gene expression in spaarse fur group. [ Conclusion ] The results provide the theoretical basis and research direction for early breeding of rex rabbit in practical production.

Phenotypic and Genetic Characteristics of a Bordetella hinzii Isolated from a Rex Rabbit

A Bordetella hinzii strain, isolated from the lung of a dead breast-feeding infant rex rabbit with a respiratory infection, was used as study object to investigate its phenotypic and genetic characteristics. The strain could grow on MacConkey agar and was gram-negative, oxidase-positive, catalase-positive, short rodshaped, and it can produce alkali from malonate. Its 6S rRNA sequence was partially identical with B. hinzii （AF177667）. Animal experiments revealed nasal mucous hyperemia, tracheal congestion and bronchopneumonia in 28-day old rex rabbits. To sum up, this Bordetella hinzii isolate was deemed as a novel causative agent of respiratory disease in rex rabbit.

Pathogenicity of Escherichia coli O_(123) from Rex Rabbit on White Mice

[Objective]The paper was to analyze the pathogenesis of Escherichia coli O123 from rex rabbit. [Method]E. coli O123 isolated from rabbit liver with diarrhea symptom in scale rex rabbit farm was intraperitoneally injected into 18- 22 g Kunming mice,and its pathogenicity was determined by clinical symptoms and pathological examination. [Result]When the inoculation concentration was about 8. 5 × 107 CFU /mL,Kunming mice appeared the clinical symptoms of drooping spirit,diarrhea and gathering,and the mortality reached 50%. Anatomical examination found that intestinal wall was thinning and intestinal mucosa was bleeding. [Conclusion]E. coli from rex rabbit has strong pathogenicity,and establishing animal model with Kunming mice to study its pathogenesis is of great reference significance for diagnosis and prevention of E. coli disease of rex rabbit.

Effects of Different Feed Additives on Fur Production Performance of Rex Rabbit

[ Objectivel To investigate the effects of three different levels of feed additives on fur production performance of Rex rabbit. [ Method] A total of 60 healthy American strain Rex rabbits at the age of 60 d （female：male =1：1 ） were randomly divided into group I, group II and group III. The Rex rabbits in the group I were fed basal diet containing nutritional substances; those in the group II were fed basal diet containing nutdtionai substances and Chinese herbal additive; and those in the group III were fed basal diet containing nutritional substances, Chinese herbal additive and enzyme. The trial lasted for 100 d. After slaughtering, the fur area, fur thickness, wool density, wool fineness and coarse wool rate were determined. [Result] The fur production performance of group III was significantly higher than that of group I （ P 〈 0.05）. There was no significant difference between group III and group II. [ Conclusion] Supplementing Chinese herbal additive and enzyme in diet can improve the fur production performance of Rex rabbit.

Intravitreal slow-release dexamethasone alleviates traumatic proliferative vitreoretinopathy by inhibiting persistent inflammation and Müller cell gliosis in rabbits

AIM:To evaluate the effects of intravitreal slow-release dexamethasone on traumatic proliferative vitreoretinopathy(PVR)and Müller cell gliosis and preliminarily explored the possible inflammatory mechanism in a rabbit model induced by penetrating ocular trauma.METHODS:Traumatic PVR was induced in the right eyes of pigmented rabbits by performing an 8-mm circumferential scleral incision placed 2.5 mm behind the limbus,followed by treatment with a slow-release dexamethasone implant(Ozurdex)or sham injection.Left eyes were used as normal controls.The intraocular pressure(IOP)was monitored using an iCare tonometer.PVR severity was evaluated via anatomical and histopathological examinations every week for 6wk;specific inflammatory cytokine and proliferative marker levels were measured by quantitative real-time polymerase chain reaction,Western blot,protein chip analysis,or immunofluorescence staining.RESULTS:During the observation period,PVR severity gradually increased.Intense Müller cell gliosis was observed in the peripheral retina near the wound and in the whole retina of PVR group.Ozurdex significantly alleviated PVR development and Müller cell gliosis.Post-traumatic inflammation fluctuated and was persistent.The interleukin-1β(IL-1β)mRNA level was significantly upregulated,peaking on day 3 and increasing again on day 21 after injury.The expression of nod-like receptor family pyrin domain containing 3(NLRP3)showed a similar trend that began earlier than that of IL-1βexpression.Ozurdex suppressed the expression of IL-1β,NLRP3,and phosphorylated nuclear factor-kappa B(NF-κB).The average IOP after treatment was within normal limits.CONCLUSION:The present study demonstrates chronic and fluctuating inflammation in a traumatic PVR rabbit model over 6wk.Ozurdex treatment significantly inhibites inflammatory cytokines expression and Müller cell gliosis,and thus alleviates PVR severity.This study highlights the important role of IL-1β,and Ozurdex inhibites inflammation presumably via the NF-κB/NLRP3/IL-1βinflammatory axis.In summary,Ozurdex provides a potential therapeutic option for traumatic PVR.