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1.
为了提高产淀粉酶枯草芽胞杆菌Bacillus subtilis N21的酶活,试验采用紫外线对该菌株进行诱变,并对该淀粉酶的部分酶学性质进行了研究。结果表明,淀粉酶酶活由出发株的32.96 U/mL增加到86.24 U/mL,比原菌株酶活提高了161.65%。该酶的最适反应温度为35℃,最适pH值为7.0,在30~40℃,pH值为5.0~8.0条件下较稳定。Ca2+和Mn2+对酶有激活作用,Cu2+、Zn2+对酶有抑制作用,而Mg2+、Fe2+对其影响较小。说明筛选出1株产酶活性较强的突变菌株。 相似文献
2.
共轭酶 (EC 3 4 2 2 12 )和二氢叶酸还原酶 (EC 1 5 1 3)是生物体内重要的叶酸代谢酶。以家蚕幼虫为材料分析了这两种酶的基本性质。 5龄幼虫体液共轭酶反应的最适pH为 7 8,最适温度为 5 0℃ ;反应体系中添加巯基乙醇、K+ 或Mg2 + 可显著提高酶活性 ,而对羟高汞苯磺酸、Co2 + 、Zn2 + 、Fe2 + 等对酶活性具有明显的抑制作用 ;以叶酸五谷氨酸为基质的水解产物为叶酸 ;另以叶酸三谷氨酸为底物 ,采用 33mmol/LHepse Ches缓冲液 (pH 7 8)在 37℃的反应条件下 ,求得Km 为 9 6 μmol/L。幼虫脂肪体等组织中二氢叶酸还原酶以NADPH为供氢体 ;在pH 4 5～7 5的范围内具有较强活性 ,最适反应温度 35℃ ;巯基乙醇、胍 ,以及高浓度的 1价金属离子 (K+ 、Na+ 等 )对酶具有活性化作用 ,对氯高汞苯甲酸、甲酰胺、Co2 + 等具有强烈的抑制作用 ;采用 35mmol/L柠檬酸 磷酸钠缓冲液 (pH 5 .0 ,10g/L抗坏血酸 )在 30℃的反应条件下 ,求得Km 值为 2 7μmol/L。家蚕体液可作为共轭酶的新酶源而加以利用。 相似文献
3.
中性植酸酶的酶学性质研究 总被引：1，自引：0，他引：1
采用钒钼酸铵法对中性植酸酶的酶学性质进行了研究,并对酶活的测定条件进行了摸索。研究结果表明,该酶的最适反应温度为48℃;最适反应pH值为6.0;在pH值5.0～6.5之间有较大的活性区间;有较强的耐酸性,在pH值2.0～9.0之间处理1h仍有90%以上的活性;具有很强的耐热性,经湿热试验箱85℃、95%RH处理5min酶活能保存70%左右;Zn2+离子对酶活有一定的抑制作用,Mn2+离子对酶活有一定的激活作用;该酶抵抗胃蛋白酶的能力比较强,抵抗胰蛋白酶的能力较弱;该酶的米氏常数Km=0.563mmol/l,最大反应速度Vmax=6.250μmol/(mg·min)。 相似文献
4.
《黑龙江畜牧兽医》2015,(9)
为了研究不同培养条件对乳酸菌黏附猪小肠黏膜上皮细胞的影响,试验采用体外细胞培养方法,观察乳酸杆菌在不同条件下(如p H值、温度、离子浓度)黏附猪小肠黏膜上皮细胞的能力。结果表明:p H值为6时,小肠黏膜上皮细胞黏附乳酸杆菌数为(15.60±0.58)个,较其他p H值时多;与其他温度(30℃和42℃)相比,37℃时猪小肠黏膜上皮细胞黏附乳酸杆菌数最多,为(22.44±1.05)个/细胞;与其他浓度相比较,猪小肠黏膜上皮细胞黏附乳酸杆菌数最多的是,2 mmol/L Ca2+时为(11.36±2.36)个/细胞,2 mmol/L Mg2+时为(18.75±1.37)个/细胞,0.005 mmol/L Fe2+时为(22.48±2.78)个/细胞,0.000 5 mmol/L Cu2+时为(20.24±2.35)个/细胞,0.002 5 mmol/L Zn2+时为(17.48±1.59)个/细胞;不同浓度的S2-对乳酸杆菌黏附小肠黏膜上皮细胞黏附性影响不显著;0.005 mmol/L I-时小肠黏膜上皮细胞黏附细菌数为(19.68±1.25)个/细胞,其他浓度I-对乳酸杆菌的细胞黏附性影响不显著。说明乳酸杆菌与猪小肠黏膜上皮细胞黏附的最佳酸碱度、温度分别为p H值为6~7、37~42℃;Ca2+、Mg2+、Fe2+、Cu2+、Zn2+、I-等6种离子的最适浓度分别为2,2,0.005,0.000 5,0.002 5,0.005 mmol/L。 相似文献
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木聚糖酶是饲用复合酶制剂中的主要酶种之一,本文对某商品酶制剂中的木聚糖酶进行了酶学性质的研究,这对于木聚糖酶的酶活测定、保存及应用均具有重要的指导意义.实验结果表明:该木聚糖酶的热稳定性良好,最适反应温度为50℃,最适pH为5.0,Km值为4.485 mg/mL,Cu2+、Zn2+、Mn2+和Fe3+对本木聚糖酶有抑制作用,而Na+、K+及(NH4)2SO4能提高此木聚糖酶的活性. 相似文献
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利用筛选培养基从不同豆制品作坊附近的土样中筛选出一株产α-半乳糖苷酶的菌株D-1,对其进行分子鉴定及所产的α-半乳糖苷酶进行酶学特性研究。研究表明,菌株D-1为Aspergillus niger,此菌株所产α-半乳糖苷酶的最适反应温度是55℃,在60℃以下热稳定性较好;最适反应pH值为5.0,在pH值3.0～5.5范围内稳定性较好,相对酶活>64.1%;Mg2+、Na+、Pb2+、K+、Mn2+、Co2+、Al3+对α-半乳糖苷酶均有不同程度的抑制作用,其中Cu2+和Fe3+的抑制作用较为明显,而Ca2+、EDTA(乙二胺四乙酸)、Zn2+对α-半乳糖苷酶有一定的促进作用。 相似文献
9.
《饲料工业》2021,(2)
从青藏高原土壤中筛选出一株产木聚糖酶较高的菌株Neurospora crassa SD10。通过单因素试验和正交试验对菌株进行发酵条件优化和酶学性质探究。结果表明,菌株SD10最佳发酵条件为:麸皮30 g/L、蛋白胨20 g/L、Mn2+0.5 g/L、培养温度33℃、转速230 r/min、接种量2%、初始pH值8.0、发酵时间84 h。菌株产木聚糖酶的最适反应温度为50℃,最适反应p H值为6.0,在40～50℃和pH值4.0～8.0时有较好的稳定性,能保持80%以上酶活力,Fe2+、Zn2+、K+对酶活力有促进作用,Na+、Mg2+、Ca2+、Mn2+、Cu2+对酶活力有抑制作用。Neurospora crassa SD10优化后产木聚糖酶活力达9.4 U/mL,所产木聚糖酶具有良好的pH值稳定性。 相似文献
10.
探讨实验室条件下人工培植牛黄过程中 ,温度、p H值、钙、乙二醇等因素对 β-葡萄糖醛酸苷酶活性的影响 ,结果表明 ,温度升高可显著提高该酶的活性 ( P<0 .0 1 ) ,且在 5 5℃时 ,其活性比在37℃提高近 4.1倍 ;该酶的最适 p H值为 7.0 ;Ca2 +在 0 .5～ 1 0 m Mol/L浓度范围内对该酶具有激活作用且与浓度成正比 ,在 1 0 m Mol/L时其激活作用最大 ;乙二醇在 0 .3～ 3Mol/L的浓度范围内对该酶具有激活作用 ,其最适浓度为 1 .5 Mol/L。 相似文献
11.
Rassnick KM Gieger TL Williams LE Ruslander DM Northrup NC Kristal O Myers NC Moore AS 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2001,15(3):196-199
1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks. 相似文献
12.
Davis MS Willard MD Nelson SL Mandsager RE McKiernan BS Mansell JK Lehenbauer TW 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2003,17(3):311-314
Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large. 相似文献
13.
Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects 总被引：1，自引：0，他引：1
Johansson AM Gardner SY Levine JF Papich MG LaFevers DH Fuquay LR Reagan VH Atkins CE 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2003,17(6):887-895
Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses. 相似文献
14.
Waruiru RM Thamsborg SM Nansen P Kyvsgaard NC Bogh HO Munyua WK Gathuma JM 《Tropical animal health and production》2001,33(3):173-187
The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round. 相似文献
15.
The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host. 相似文献
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Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ 
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下载免费PDF全文 S. Pashaei T. Ghoorchi A. Yamchi 《Journal of animal physiology and animal nutrition》2016,100(2):211-216
An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed. 相似文献
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Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb
albumin
- ALT
alanine aminotransferase
- AST
aspartate aminotransferase
- BUN
blood urea nitrogen
- Chol
cholesterol
- Glob
globulin
- -GT
-glutamyl transpeptidase
- IP
inorganic phosphorus
- TP
total protein 相似文献
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正We are pleased to publish the second special issue on avian brood parasitism and to be responsible guest editors for the two special issues of Chinese Birds (Vol. 3, No. 4, 2012 and Vol. 4, No. 1, 2013), entitled "Avian Brood Parasitism - A Growing Research Area in Behavioral Ecology". The first issue was published in December 2012. The goal of the two special issues is to publish accumulated knowledge and some of the recent developments in 相似文献
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Tropical Animal Health and Production - 相似文献