Physiological function of plasma membrane Ca2+-ATPase isoform 2 in inner ear hair cells of mouse

AIM: To investigate the auditory and balanceable function of hair cell plasma membrane Ca²⁺-ATPase isoform 2 (PMCA2) channel in mouse inner ear.METHODS: Hearing threshold and endocochlear potential (EP) were measured in the PMCA2 homozygous mutants mice,heterozygous mice and wild-type mice by auditory brainstem response (ABR),distortion product otoacoustic emission (DPOAE) and EP recordings,respectively.RESULTS: The auditory function in PMCA2 wild-type mice was normal,the mean value for ABR thresholds in response to click sound stimulus was (13.75±11.08)dB SPL,EP was (91.3±11.0)mV.The mean value for ABR thresholds in response to click sound stimulus was (63.89±12.90)dB SPL in PMCA2 heterozygous mice and significantly increased relative to that observed in PMCA2 wild-type mice (P<0.01).EP in PMCA2 heterozygous mice was about (80.7±9.0) mV and lower than that in PMCA2 wild-type mice but no statistics significance was observed (P>0.05). DPOAE thresholds increased and reduced amplitudes at high frequencies in PMCA2 heterozygous mice compared to wild-type mice.PMCA2 homozygous mutant mice were completely deaf,the ABR wave form was not observed even 100 dB SPL sound stimuli was used,the value of EP was (56.6±13.0) mV lower than that in PMCA2 wild type mice (P<0.05).PMCA2 homozygous mutants mice did not produce DPOAEs,PMCA2 homozygous mutant mice were deaf and demonstrated difficulties in maintaining their balance.CONCLUSION: These data demonstrate that PMCA2 is required for both balance and hearing and suggest that it may be a major Ca²⁺ pump used in endolymph Ca²⁺ maintenance.     

Properties of ACh-sensitive BK channels in mice type Ⅱ vestibular hair cells and its modulation by calcium

AIM: To explore the properties of the acetylcholine (ACh)-sensitive potassium channel in type Ⅱ vestibular hair cells (VHCs Ⅱ) in mice saccular macula and the modulation effect of calcium ions.METHODS: Under the whole-cell patch mode,the pharmacology properties of ACh-sensitive potassium channel and the modulation of calcium ions on ACh-sensitive potassium channel were investigated.RESULTS: Following extracellular perfusion of ACh,VHCs Ⅱ displayed a slow and sustained outward current,which was sensitive to tetraethylammonium (TEA,5 mmol/L) and charybdotoxin (CTX,100 nmol/L),but not sensitive to 4-aminopyride (4-AP,15 μmol/L).ACh-sensitive potassium current was inhibited by intracellular application of ethylene glycol-bis (B-aminoethylether)-N,N,N,N-tetraacetic- acid (EGTA,5 mmol/L) and extracellular perfusion of Cd2+ and Ni2+,respectively.Intracellular application of heparin (8 g/L) failed to inhibit ACh-sensitive potassium current.CONCLUSION: Extracellular application of ACh activates the big conductance,calcium-dependent potassium current (BK) in VHCs Ⅱ of mice,which is potently modulated by extracellular Ca2+ ions.However,intracellular IP3-dependent Ca2+ ions release mechanism is not involved in the activation of the ACh-sensitive BK channel.     

力克斯兔被毛的生物学特性研究

力克斯兔的初级毛囊、次级毛囊于胚胎的18～24天先后出现。其皮肤表皮、真皮的发生与分化于胚胎的24天已基本完成。26日胎龄时,初级毛囊结构分化完全,并可见到皮脂腺。26日胎龄至仔兔出生,是表皮和毛囊分化出的各组成成分的进一步生长阶段。仔兔出生以后,皮肤表皮和毛囊的结构均无明显变化,但表皮厚度稍有增加,毛囊仍继续向真皮伸展,只是远不及胚胎期迅速。表皮的增长速度及毛囊的生长速度,在不同部位之间无显著差异,而不同胎龄(月龄)之间存在显著或极显著差异。力克斯兔皮肤的毛囊群结构很有规律。每一毛囊群由2～6个扇形分布的亚毛囊群组成,每一亚毛囊群中又含有5～12个分生毛囊和衍生分生毛囊。力克斯兔出生以后,其衍生分生毛囊数的增加几乎与体表面积的增大呈比例,使各月龄之间毛囊密度无显著差异,但不同部位之间,毛囊密度差异显著。被毛因粗毛含量少、分布均匀、直径也小;毛纤维短、且粗,细毛长度一致;强度大、伸度小(与新西兰白兔比较),从而构成了力克斯兔被毛具有弹性强、柔软性好、平整、经久耐磨等特征。通过扫描电镜及光学显微镜对力克斯兔、新西兰白兔及安哥拉兔3个不同类型的鳞片排列形态及髓腔结构的观察,发现不同类型之间,鳞片的排列形态不同,但髓腕结构的差异不明显。     

毛干DNA的快速提取及其对PCR的影响

[目的]建立毛干DNA快速稳定的提取扩增策略,使这一简便取材能在畜牧、野生动物保护等采样困难的领域得以普及应用.[方法]采用PCR缓冲液快速提取及2轮PCR逐级稀释扩增的策略提取扩增黄牛毛干DNA微卫星位点.[结果]该方法可从低至0.1mg（约1 cm长）的毛干中提取得到DNA,并成功扩增核DNA微卫星位点.48份黄牛牛毛样本均成功提得DNA.72份扩增样本,除4份样本扩增效果较差,其余样品均能正常扩增.[结论]该研究方法可快速稳定的提取扩增目标基因,为毛干在相关领域的普及应用奠定了基础.     

Growth performance and meat characteristics of hair lambs grazing stargrass pasture without supplementation or supplemented with concentrate containing different levels of crude protein

Abstract

Forty crossbreed hair lambs (19.1 kg body weight; 8 months of age) grazing on a Cynodon plestoctachyus pasture without supplementation or supplemented with 300 g of concentrate containing different levels of crude protein (CP) were randomly assigned to treatments defined as follows: control (without supplementation); CP130 (concentrate 130 g CP/kg), CP150 (concentrate 150 g/kg), CP170 (concentrate 170 g/kg), and CP190 (concentrate 190 g CP/kg). Lambs fed supplements had higher final body weight (BW), total gain, average daily gain (ADG), total dry matter intake (DMI), total tract digestion, and carcass dressing than lambs in control treatment. Final BW, total gain, ADG, total DMI, feed conversion, and total tract digestion were improved linearly as protein level in concentrate increased. Meat of lambs fed supplements was lighter, redder, and less yellow than meat of lambs in control treatment. It is concluded that supplementation improved ADG, feed conversion, carcass dressing, and meat color.     

内蒙古阿尔巴斯绒山羊毛囊结构及形态发生过程研究

 【目的】了解绒山羊毛囊的组织结构及毛囊形态发生变化过程，为研究绒山羊绒毛发育的分子调控机理奠定组织学基础。【方法】制作内蒙古阿尔巴斯绒山羊胚胎皮肤组织切片，显微镜下观察照相。【结果】绒山羊的毛囊结构同其它动物一样，由毛球、连接组织鞘、外根鞘、内根鞘和毛干几部分组成。在胎龄55～65 d毛囊开始发生形成毛芽；胎龄135 d，大多数初级毛囊和一部分次级毛囊发育基本成熟；次级毛囊是初级毛囊的一个分支。【结论】了解了绒山羊毛囊的结构组成及毛囊从发生到发育成熟的整个形态变化过程，为相关领域研究者提供借鉴。     

大豆叶片结构与灰斑病抗性的研究 Ⅰ．大豆叶片气孔密度、茸毛密度与灰斑病抗性的关系

采用火棉胶法和水合氯醛法研究了大豆叶片气孔密度、茸毛密度与灰斑病抗性的关系。试验结果表明，抗病品种和感病品种叶片正面和背面的茸毛密度并没有什么差异；但抗病品种叶片正面及叶片背面的气孔密度明显少于感病品种，这是抗病品种抵抗菌丝侵入的第一结构屏障。     

Pyridoxine regulates hair follicle development via the PI3K/Akt,Wnt and Notch signalling pathways in rex rabbits

This study was conducted to evaluate the effect of pyridoxine on the development of hair follicles in Rex rabbits and the underlying molecular mechanism. Two hundred 3-month-old Rex rabbits were randomly divided into 5 groups and fed diets supplemented with 0, 5, 10, 20, or 40 mg/kg pyridoxine. The hair follicle density on the dorsal skin and the gene and protein expression levels of components of the phosphoinositide 3-kinase (PI3K)/protein kinase B (PKB or Akt), Wnt, Notch and bone morphogenetic protein (BMP) signalling pathways were measured. In addition, free hair follicles were isolated from Rex rabbits and cultured with pyridoxine in vitro to measure hair shaft growth. Furthermore, dermal papilla cells (DPC) were isolated from the skin of Rex rabbits and cultured with pyridoxine in vitro to measure the gene and protein expression levels of components of the PI3K/Akt, Wnt, Notch and BMP signalling pathways. The results showed that the addition of dietary pyridoxine significantly increased the total follicle density, secondary follicle density, and secondary-to-primary ratio (S/P, P < 0.05), that the growth ratio of hair stems was promoted by pyridoxine in basic culture medium, and that the growth length of tentacle hair follicles cultured in the pyridoxine group was longer than that in the control group (P < 0.05). In addition, pyridoxine changed the DPC cycle progression and promoted cell proliferation, and appropriate concentrations of pyridoxine (10 and 20 μmol/L) significantly inhibited cell apoptosis (P < 0.05). Pyridoxine significantly affected the gene expression of components of the PI3K/Akt, Wnt and Notch signalling pathways in the skin and DPC of Rex rabbits (P < 0.05), increased the levels of phosphorylated catenin beta 1 (CTNNB1) and Akt, and decreased the level of phosphorylated glycogen synthase kinase 3 beta (GSK-3β) (P < 0.05). Therefore, the molecular mechanism by which pyridoxine promotes hair follicle density in Rex rabbits probably occurs through activation of the PI3K/Akt, Wnt and Notch signalling pathways, prolonging hair follicle growth and delaying the onset of telogen.     

陕西甘泉县黄牛毛色遗传分析

随机抽取陕西甘泉县１４８头黄牛进行毛色分析，结果表明：其毛色遗传受９个位点的等位基因支配，基本毛色以黄色为主，红色和草白色次之，黑色、沙毛、黑背线及眼圈浅色在群体中以极低的频率出现。确认该地域黄牛在毛色上具有蒙古牛和秦川牛的一些共同特征。