Reproductive roles predict sexual dimorphism in internal and external morphology of lake whitefish,Coregonus clupeaformis

Abstract – The different reproductive roles of the sexes can predict the direction and magnitude of sexual dimorphism of external and internal morphology. Males should have enlarged structures that enhance the acquisition of mating opportunities, whereas females are predicted to have enlarged organs that are associated with the production of eggs. We tested these predictions in male and female lake whitefish, a species in which both sexes have similar overall body size and shape. After controlling for body size, male lake whitefish had significantly longer jaws and pectoral and pelvic fins, larger hearts, and more muscle than females. Sexual dimorphism in relative muscle mass may be one of the most fundamental morphological differences between males and females. Females had relatively heavier livers than males. Because the liver is important for the breakdown of fats and vitellogenesis, selection should favour an enlarged liver in females for the processing of energy and the production of large numbers of eggs.     

金霉素和代谢物差向金霉素在肉鸡肌肉和肝脏中的残留分布

为了研究金霉素(CTC)、差向金霉素(ECTC)在肉鸡肌肉、肝脏中的残留分布情况,样品经提取液提取后过Oasis HLB SPE小柱净化,采用电喷雾正离子模式(ESI+)和多反应监测模式(MRM),用高效液相色谱-串联质谱仪检测;试验组鸡按体重以50 mg/(kg·d)剂量内服CTC,连续5 d,每天给药1次。结果表明:该方法测定肉鸡肌肉和肝脏中CTC检测限和定量限分别为5.0、10.0μg/kg。ECTC检测限和定量限分别为20.0、30.0μg/kg。CTC和ECTC在肉鸡肌肉中平均回收率分别在73.0%~95.20%和81.80%~101.60%,相对标准偏差(RSD)分别在8.85%~12.18%和2.05%~9.29%;在肉鸡肝脏中平均回收率分别在67.06%~90.80%和78.64%~106.98%,RSD分别在2.90%~8.88%和4.72%~9.48%;肉鸡肌肉和肝脏中CTC、代谢物ECTC的残留量分别在给药后第1、5 d时达到最高。肉鸡肝脏中ECTC的残留量约占总残留量的1/2。停药后CTC及其代谢物ECTC代谢缓慢,在停药第6 d时,仍能检测到CTC及其代谢物ECTC,但其残留量均低于最高残留限量(MRLs)。从保障食品安全方面考虑,建议我国将CTC和ECTC均作为金霉素的残留标示物进行监测。     

用基于遗传算法的BP神经网络识别牛肉肌肉与脂肪

利用遗传算法的全局搜索能力,改进标准BP算法随机选取初始权重的不足,并构建了3-12-1的三层遗传BP神经网络,进行了3次牛肉肌肉与脂肪像素的分类试验,研究用BP网络对牛肉肌肉与脂肪两类像素点进行识别的可行性。以像素点的RGB值作为BP网络输入向量,每次训练集样本数62,测试集样本数43。测试的最终结果为：训练集的样本识别率分别为100%、100%、98.3871%;对应测试集的样本识别率分别为97.6744%、97.6744%、100%。试验结果表明,尽管基于遗传算法的BP神经网络对训练样本集以及测试样本集的肌肉和脂肪的识别率均在97%以上,但由于牛肉图像像素值在颜色空间中比较分散,有利于聚类的规律性不明显,因而是否可用BP网络来完成肌肉与脂肪的识别,还需要在网络拓扑结构、训练样本集等方面进一步研究。     

二花脸猪和大白猪背最长肌中肌肉生长抑制素和生肌调节因子基因的表达及其性别特点

用相对定量RT—PCR方法研究大白猪和二花脸猪背最长肌中肌肉生长抑制素（Myostatin）和生肌调节因子（Myo—genin）基因表达的发育性变化并进行品种及性别间比较。研究结果表明：大白猪公猪Myostatin mRNA表达水平在20日龄时达到高峰且显著高于相同日龄二花脸公猪（P〈0．05）,而二花脸公猪在45日龄时才显著升高,其他日龄品种间差异不显著。二花脸公猪和母猪出生后Myostatin mRNA表达水平均表现为上升,45日龄时达到高峰,120日龄时公母猪间差异显著（P〈0．05）。二花脸公猪与大白猪公猪Myogenin mRNA的表达发育模式基本相同,均在20日龄达到最高值,品种问差异不显著。90日龄二花脸母猪Myogenin mRNA表达水平较公猪显著下调（P〈0．05）。结果提示,猪背最长肌中Myostatin和Myogenin基因表达水平在猪出生后早期均较高,但没有出现随着日龄的增加而一直升高或降低的趋势;两种基因的表达在20日龄出现品种间差异;性成熟前后二花脸公母猪间表达有差异。     

牦牛MYL3基因的克隆及组织表达分析

【目的】研究牦牛MYL3基因的结构和表达特征,探究其生物学功能及影响牦牛肌肉生长发育的机制。【方法】以美仁牦牛cDNA为模板,PCR扩增MYL3基因编码区序列(CDS),利用MEGA11软件构建系统进化树,利用生物信息学软件对其编码蛋白进行分析。通过实时荧光定量PCR(RT-qPCR)检测MYL3基因在心脏、肝脏、脾脏、肺脏（参照）、睾丸、肌肉和脂肪组织中的相对表达量。【结果】牦牛MYL3基因CDS区长600 bp,共编码199个氨基酸,存在1个碱基突变位点,位于第165位(A>T)。系统进化分析结果显示,牦牛与普通牛的亲缘关系最近,与单峰驼的亲缘关系最远。生物信息学分析结果显示,牦牛MYL3蛋白为不稳定的亲水性蛋白,无信号肽,不存在跨膜结构,主要存在于细胞质内,有8个磷酸化位点和2个N 糖基化位点,蛋白的二级结构以α-螺旋为主,主要与调控肌肉生长发育的相关蛋白相互作用。RT-qPCR结果表明,MYL3基因在心脏中的表达量最高,极显著高于其他组织;肌肉中次之,与除心脏外的其他组织存在极显著差异。【结论】MYL3基因可能与牦牛心脏发育有关,对肌肉的生长发育和肉质有一定影响。     

不同游泳运动对菊黄东方鲀非特异性免疫的影响

通过水槽实验法,观察了菊黄东方鲀的游泳行为,测量了其爆发游速及临界游速,同时观察了鱼体过氧化氢酶、溶菌酶、超氧化物歧化酶等的活性变化,分析了游泳对菊黄东方鲀免疫力影响,为菊黄东方鲀的健康养殖及科学的增殖放流提供参考。结果表明:体长在（18.1-19.8）cm的菊黄东方鲀的临界游速在45-62cm/s,体长在（18.8-20.6）cm的菊黄东方鲀的爆发游速为（58.5-78.2）cm/s;与对照组相比,爆发游速实验组菊黄东方鲀肝脏过氧化氢酶、溶菌酶、超氧化物歧化酶的活性均高于对照实验组菊黄东方鲀（P?0.05）;临界游速实验组菊黄东方鲀溶菌酶高于对照组（P?0.05）,血液中的超氧化物歧化酶和肝脏过氧化氢酶的活性没有显著变化(P>0.05)。研究表明,急性应激反应对超氧化物歧化酶、过氧化氢酶、溶菌酶的活性影响较大。     

Effects of hypoxia-inducible factor-1 signal pathway on proliferation in hypoxic pulmonary artery smooth muscle cells

AIM: To investigate the effect of hypoxia on the proliferation and apoptosis of pulmonary artery smooth muscle cells (PASMC); and to evaluate the role of hypoxia-inducible factor-1α(HIF-1α), iNOS, P-ERK1/2 protein expression in hypoxic pulmonary hypertension (HPH) pathogenesis.METHODS: Cultured rat PASMC were divided into normoxic group; hypoxic group; hypoxia+ADM(adrenomedulin) group, hypoxia+L-NAME(iNOS inhibitor) group; hypoxia+PD98059 group. Proliferation was investigated by MTT and PCNA. Apoptosis was examined by flow-cytometry. Westen blotting was used to measure protein expression of HIF-1α, P-ERK1/2 and iNOS. RESULTS: (1) A value of 24 h-hypoxia was significantly higher than that in the normoxic group (P<0.01). In the hypoxia+PD98059 group, ADM was significantly lower than that in hypoxia group, whereas A value of the hypoxia+L-NAME was significantly higher than that in hypoxic group and normoxic group (P<0.01). (2) PCNA was positive in PASMC after 24 h hypoxia (P<0.01). PD98059, ADM inhibited the expression of PCNA significantly (P<0.01), whereas L-NAME increased the expression of PCNA significantly (P<0.01). (3) Apoptosis index was not significantly difference among the different groups (P>0.05). (4) HIF-1α, iNOS and P-ERK1/2 expression was poorly positive in normoxic group, positive after hypoxia for 4h (P<0.01), reaching its peak at 8 h hypoxia (P<0.01), HIF-1α, P-ERK1/2 expression declined after 24 h hypoxia. L-NAME promoted the expression of HIF-1α, PD98059 inhibited the expression of HIF-1α, iNOS and P-ERK1/2 partly. ADM inhibited the expression of HIF-1α partly, promoted the expression of iNOS. CONCLUSION: (1) Hypoxia stimulates the proliferation of PASMC, and has no obvious effects on the apoptosis of PASMC. (2) HIF-1 plays an importent role in the proliferation of hypoxic PASMC.     

Effects of Nrf2 overexpression on proliferation,activation and collagen type I synthesis in cultured hepatic stellate cells stimulated by ethanol

AIM：To investigate the effects of nuclear factor E2-related factor 2 (Nrf2) overexpression on the proliferation, cell cycle distribution, collagen type I (Col I) synthesis and alpha-smooth muscle actin (α-SMA) expression in cultured hepatic stellate cell line HSC-T6 stimulated by ethanol. METHODS：Cultured HSC-T6 cells were transfected with pEGFP-Nrf2 or pEGFP-N1 (empty vector) plasmid by liposome transient transfection. The cells were divided into control group, ethanol group, ethanol+pEGFP-Nrf2 group and ethanol+pEGFP-N1 group. The mRNA expression of Nrf2, α-SMA and Col I was determined by RT-PCR, and their protein expression was detected by Western blotting. Cell proliferation was assessed by MTT assay, and cell cycle was detected by flow cytometry. RESULTS：The pEGFP-Nrf2 plasmid was successfully transfected into HSC-T6 cells, and the mRNA and protein expression of Nrf2 was higher than other three groups 48 h after transfection (P<0.05). Compared with control group, the cell proliferation and the mRNA and protein expression of α-SMA and Col I in ethanol group and ethanol+pEGFP-N1 group were significantly increased (P<0.05), and the numbers of HSC-T6 cells were decreased in G1 phase and increased in S phase (P<0.05), without significant differences between the two groups (P>0.05). Meanwhile, the cells in ethanol+pEGFP-Nrf2 group showed significantly decreased proliferation level, down-regulated mRNA and protein expression of α-SMA and Col I, higher numbers in G1 phase and lower numbers in S phase compared with ethanol group and ethanol+pEGFP-N1 group (P<0.05). CONCLUSION：Nrf2 overexpression could significantly down-regulate the expression of α-SMA and Col I and cause G1/S phase arrest in HSC-T6 cells cultured with ethanol, thus inhibiting the proliferation and activation of the cells.