“纪念钟万勰院士九十诞辰暨《计算力学学报》创刊四十周年”专刊序言

2024年2月24日是本刊第二任主编、中国科学院院士、大连理工大学钟万勰教授诞辰九十周年。2024年2月又适逢《计算力学学报》(原名《计算结构力学及其应用》)创刊四十周年。为继承和弘扬钟万勰院士的学术思想和科学精神,缅怀其治学风范,秉承本刊的创刊人钱令希院士等老一辈科学家倡导的推动计算力学发展及其与工程实践相结合的办刊宗旨,交流计算力学领域的学术研究成果,我们组织了本专刊。包括钟万勰院士学生在内的计算力学领域部分知名专家应邀赐稿。

不同精粗比日粮对山羊生产性能、血清生化指标和瘤胃发酵的影响

在相同蛋能比和钙磷比下,研究不同精粗比全混合日粮对努比亚山羊生长性能、血清生化指标和瘤胃发酵的影响。选择健康、体重相近的2月龄努比亚山羊母羊36只,随机分为3组,每组12只羊,分别饲喂精粗比为40∶60(L)、50∶50(M)和60∶40(H)的全混合日粮。试验期70 d。结果表明:1)正试期第14天,L组山羊的平均日采食量显著高于其他两组(P<0.01)。正试期第35天,L组山羊的平均日采食量显著高于H组(P<0.05),而料重比则相反。正试期第56天,L组山羊的平均日增重显著高于其他两组(P<0.05),而料重比则相反。2)正试期第14天,L组山羊血清白蛋白(albumin,ALB)和尿素氮(urea nitrogen,BUN)浓度显著高于H组(P<0.05)。正试期第56天,L组山羊血清ALB和血糖(glucose,GLU)含量以及M组山羊血清甘油三酯(triglyceride,TG)含量显著高于H组(P<0.05)。3)正试期第14天,M组山羊血清瘦素(leptin,LEP)和三碘甲状腺原氨酸(triiodothyronine,T3)浓度分别显著低于H组和L组(P<0.05)。正试期第35天,L组山羊血清LEP和胰岛素(insulin,INS)浓度显著高于其他两组(P<0.05)。正试期第56天,L组山羊血清生长激素(growth hormone,GH)浓度显著高于H组(P<0.05)。4)M组山羊的后腿重和屠宰率显著高于L组(P<0.05)。5)L组的乙酸、丙酸、丁酸、戊酸和总挥发性脂肪酸浓度均显著低于其他两组(P<0.05),而pH则相反。6)L组山羊瘤胃的黄色瘤胃球菌、溶纤维丁酸弧菌、白色瘤胃球菌和产琥珀酸丝状杆菌数量显著高于H组(P<0.05),而乳酸菌数量和嗜淀粉瘤胃杆菌则相反。M组山羊瘤胃的栖瘤胃普雷沃菌数量显著高于其他两组(P<0.05)。综上所述,努比亚山羊饲喂精粗比40∶60全混合日粮能够获得最佳的生产性能。

The protective roles of tea tree oil extracts in bovine mammary epithelial cells and polymorphonuclear leukocytes

Background: Tea tree oil(TTO) plays an important role in antibacterial activity and alleviating the inflammatory responses. Bovine mammary epithelium and polymorphonuclear leukocytes(PMNL) can actively respond to bovine mastitis infection. However, regulatory effects of TTO extracts on the innate immune response of bovine mammary epithelial cells(BMECs) and PMNL remain not reported. Therefore, aim of the study was to evaluate the effects of TTO extracts on the m RNA levels of the genes involved in the innate immune response of BMECs and PMNL.Results: Our results demonstrated that addition of 0.025% and 0.05% TTO increased the proliferation of BMECs, and significantly enhanced(P < 0.05) the viability of BMECs exposed to Staphylococcus aureus(S. aureus). An inhibitory effect was observed against the growth of S. aureus by TTO incubation. The 0.05% TTO reduced S. aureus biofilm formation, association and invasion of S. aureus to BMECs, and changed the morphological and structural features of S. aureus. The proinflammatory cytokines IL-1β, IL-6, and TNF-α were decreased(P < 0.001) by the incubation of TTO. Interestingly, the expression of IL-8 known for PMNL chemotactic function was elevated(P < 0.05) by 0.05%TTO treatment. Consistently, 0.05% TTO increased the migration of PMNL in S. aureus-exposed BMECs when compared with S. aureus treatment alone(P < 0.05). In addition, PMNL incubated with 0.05% TTO decreased the levels of NFKB inhibitor alpha(NFKBIA) and TNF-α.Conclusions: Our results indicate that use of TTO can relieve the BMECs pro-inflammatory response caused by S.aureus and promote the migration of PMNL to mount the innate immune responses, and it may be novel strategy for the treatment of bovine mastitis caused by S. aureus.

Butyrate inhibits the bovine rumen epithelial cell proliferation via downregulation of positive regulators at G0/G1 phase checkpoint

Short-chain fatty acids(SCFAs)butyrate promote the postnatal rumen epithelial development and maturation in ruminants.However,molecular mechanisms of effects of butyrate on the bovine rumen epithelial cells(BRECs)proliferation remain elusive.Therefore,purpose of this study was to investigate the effects of butyrate on the expression of genes and proteins at G0/G1 and S phase of BRECs cycle.Our results showed that BRECs treated with butyrate inhibited(P<0.05)the proliferation of BRECs,relatively to control.Flow cytometric assays revealed that butyrate triggers the BRECs cycle arrest at the G0/G1 phase.qRT-PCR analyses of mRNA level of genes involved in the G0/G1 phase of cell cycle showed that butyrate significantly upregulated(P<0.001)the expression of mRNA encoding p21^(Cip1)compared with control group,but it decreased(P<0.05)the mRNA levels of cyclin D1 and CDK4 genes at G0/G1 phase checkpoint compared with control.Moreover,Western blot also revealed that butyrate downregulated the expression of cyclin D3,CDK6,p-Rb,and E2F1 proteins involved in the modulation of G0/G1 phase of cell cycle.In conclusion,our results demonstrated that butyrate inhibits the proliferation of BRECs via downregulation of positive regulators at G0/G1 phase checkpoint.

Hexokinase 1 and 2 mediates glucose utilization to regulate the synthesis of kappa casein via ribosome protein subunit 6 kinase 1 in bovine mammary epithelial cells

Glucose plays a vital part in milk protein synthesis through the mTOR signaling pathway in bovine mammary epithelial cells(BMEC).The objectives of this study were to determine how glucose affects hexokinase(HK)activity in BMEC and investigate the regulatory effect of HK in kappa casein(CSN3)synthesis via the mechanistic target of rapamycin complex 1(mTORC1)signaling pathway in BMEC.For this,HK1 and HK2 were knocked out in BMEC using the CRISPR/Cas9 system.The gene and protein expression,glucose uptake,and cell proliferation were measured.We found that glucose uptake,cell proliferation,CSN3 gene expression levels,and expression of HK1 and HK2 increased with increasing glucose concentrations.Notably,glucose uptake was significantly reduced in HK2 knockout(HK2KO)BMEC treated with 17.5 mM glucose.Moreover,under the same glucose treatment conditions,the proliferative ability and abundance of CSN3 were significantly diminished in both HK1 knockout(HK1KO)and HK2KO BMEC compared with that in wild-type BEMC.We further observed that the phosphorylation levels of ribosome protein subunit 6 kinase 1(S6K1)were reduced in HK1KO and HK2KO BMEC following treatment with 17.5 mM glucose.As expected,the levels of glucose-6-phosphate and the m RNA expression levels of glycolysis-related genes were decreased in both HK1KO and HK2KO BMEC following glucose treatment.These results indicated that the knockout of HK1 and HK2 inhibited cell proliferation and CSN3 expression in BMEC under glucose treatment,which may be associated with the inactivation of the S6K1 and inhibition of glycolysis.

Optimization of low-abundance protein extraction and abundant protein removal from defatted soybean meal

The aim of this study was to optimize the conditions for the extraction of low-abundance proteins（LAPs） and the removal of abundant proteins（APs; β-conglycinin and glycinin） from soybean meal.Single factor and orthogonal experiments were designed to determine the effects of four factors（isopropanol concentration, total extraction time, ultrasonic power, and ultrasonic time） on protein concentration in isopropanol extracts.Proteins in the isopropanol supernatant and the cold acetone precipitate of isopropanol were identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis（SDS-PAGE） and matrix-assisted laser desorption/ionization-time of flight mass spectrometry（MALDI-TOF-MS）.The results showed that the optimal conditions were 50% isopropanol, ultrasonic pretreatment for 15 min at 350 W, and a total extraction time of 1 h.Under these conditions, the protein concentration in the isopropanol extracts reached 0.8081 g/L.Many LAPs were detected, including β-amylase, soybean agglutinin, soybean trypsin inhibitor, fumarylacetoacetase-like, phospholipase D alpha 1-like, oleosin, and even some unknown soybean proteins.The soybean APs（β-conglycinin and glycinin） were not found.The method may be useful for discovering new soybean proteins and extracting enough LAPs of soybean to allow further studies of their physiological effects on animals without the influence of APs.