Effect of breed of cattle on transmission rate and innate resistance to infection with Babesia bovis and B bigemina transmitted by Boophilus microplus     

RE BOCK  TG KINGSTON  AJ de  VOS 《Australian veterinary journal》1999,77(7):461-464

OBJECTIVE: To assess the effect of breed of cattle on the transmission rates of and innate resistance to Babesia bovis and B bigemina parasites transmitted by Boophilus microplus ticks. DESIGN: Groups of 56 purebred B indicus and 52 B indicus cross B taurus (50%, F1 generation) steers were placed in a paddock seeded with and also naturally infested with B microplus which were the progeny of females ticks fed on B taurus cattle specifically infected with a virulent isolate of B bovis. The cattle were placed in the infested paddock 50 days after seeding had started. PROCEDURE: Cattle were inspected from horseback daily for 50 days. Clinically ill cattle were brought to yards and assessed by monitoring fever, depression of packed-cell volume, parasitaemia and severity of clinical signs. Any animals that met preset criteria were treated for babesiosis. Blood samples were collected from all cattle on day 28, 35 and 42 after exposure and antibodies to Babesia spp and packed cell volume measured. RESULTS: All steers, except for one crossbred, seroconverted to B bovis and B bigemina by day 35 and 75% of the crossbred steers showed a maximum depression in packed cell volume of more than 15% due to infection with Babesia spp compared with only 36% of the B indicus group. Ten of the 52 crossbreds and 1 of the 56 B indicus steers showed severe clinical signs. Two of the crossbreds required treatment of which one died 2 weeks after initial treatment. CONCLUSIONS: Pure-bred B indicus cattle have a high degree of resistance to babesiosis, but crossbred cattle are sufficiently susceptible to warrant the use of preventive measures such as vaccination. Transmission rates of B bovis and B bigemina to B indicus and crossbred cattle previously unexposed to B microplus were the same.  相似文献   

Magnetic microstructure of magnetotactic bacteria by electron holography     

RE Dunin-Borkowski  MR McCartney  RB Frankel  DA Bazylinski  M Posfai  PR Buseck 《Science (New York, N.Y.)》1998,282(5395):1868-1870

Off-axis electron holography in the transmission electron microscope was used to correlate the physical and magnetic microstructure of magnetite nanocrystals in magnetotactic bacteria. The magnetite crystals were all single magnetic domains, and the magnetization directions of small superparamagnetic crystals were constrained by magnetic interactions with larger crystals in the chains. Shape anisotropy was found to dominate magnetocrystalline anisotropy in elongated crystals. A coercive field between 300 and 450 oersted was determined for one chain.  相似文献   

设施老汉瓜采后干制技术研究     

杜娟  热比古丽·哈力克  沙吾提·阿布拉江  廖新福 《农产品加工．学刊》2020,(4):30-32

以设施老汉瓜为试材,采用不同成熟度、前处理、预处理温度后进行干制,测定含水率、失重率、色差等指标变化。相同的干燥温度、时间条件下,6个成熟度、2种不同的前处理、5种预处理温度的设施老汉瓜的失重率、最终含水率、总色差值在干制期内变化不同。结果表明,不同成熟度的设施老汉瓜,干制期的预处理温度、前处理和烘制温度差距,影响老汉瓜在干制过程中水分的散失。采用不同处理方式至完全干燥,可溶性固形物含量11%的设施老汉瓜,瓜干失重率、含水率、瓜干总色差值ΔE变化略慢,较好地保持瓜干的品质,适宜于老汉瓜的加工。  相似文献   

Magnetic Collapse in Transition Metal Oxides at High Pressure: Implications for the Earth     

RE Cohen  II Mazin  DG Isaak 《Science (New York, N.Y.)》1997,275(5300):654-657

Magnetic collapse in transition metal ions is predicted from first-principles computations at pressures reached in the Earth's lower mantle and core. Magnetic collapse would lead to marked changes in geophysically important properties, such as elasticity and conductivity, and also to different geochemical behavior, such as element partitioning, than estimated by extrapolating low-pressure data, and thus change the understanding of Earth's structure and evolution. Magnetic collapse results from band widening rather than from changes in crystal field splitting under pressure. Seismic anomalies in the outer core and the lowermost mantle may be due to magnetic collapse of ferrous iron, dissolved in iron liquid in the outer core, and in solution in magnesiowustite in the lowermost mantle.  相似文献   

Evolution. Transitions from nonliving to living matter     

Rasmussen S  Chen L  Deamer D  Krakauer DC  Packard NH  Stadler PF  Bedau MA 《Science (New York, N.Y.)》2004,303(5660):963-965

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WHAT IS NATURE STUDY?     

Beal WJ  Packard AS  Coulter JM  Gillette CP  Davis WM  Verrill EA  Jordan DS  Macbride TH 《Science (New York, N.Y.)》1902,16(414):910-913

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Rib osteomyelitis in three foals     

KM Neil  RE Charman  JR Vasey 《Australian veterinary journal》2010,88(3):96-100

Three foals aged between 21 and 44 days were presented for evaluation of pyrexia and lameness. Each had subcutaneous abscessation associated with osteomyelitis of a rib at the costochondral junction and pathological fracture of the affected rib; one foal had more than one rib affected. Other localised sites of infection included other sites of osteomyelitis, omphalophlebitis, uveitis, enterocolitis, and calcaneal bursitis. The subcutaneous abscessation and rib osteomyelitis was treated surgically in two foals. Salmonella typhimurium was isolated from the subcutaneous abscess in one foal and from the faeces of another. Two of the three foals were euthanased. Ultrasonography was a more useful modality than radiography for establishing the diagnosis of costal osteomyelitis.  相似文献   

林业病虫害防治工作中的问题及对策   总被引：2，自引：0，他引：2  

苏玉珍  热希 《内蒙古林业调查设计》2007,30(6):71-72,6

林业有害生物防治是国家减灾工程的重要组成部分,通过对乌拉特前旗林业有害生物防治工作存在问题的分析,提出了解决这类问题切实可行的对策措施。  相似文献   

Calcium absorption from three salts and CaSO(4)-fortified bread in premenopausal women     

Martin BR  Weaver CM  Heaney RP  Packard PT  Smith DL 《Journal of agricultural and food chemistry》2002,50(13):3874-3876

Two studies were conducted to measure calcium absorption from calcium sulfate fortified bread and three salts (calcium lactate, calcium carbonate, and calcium sulfate) in healthy premenopausal women using a crossover design. In study I, calcium fractional absorption levels from the three salts labeled with a stable isotope, 44Ca, were not significantly different (0.039-0.47) as determined by the fecal recovery method. In a second study, absorption of 45Ca from CaSO(4)-fortified labeled bread or labeled milk was measured in serum exactly 5 h postingestion. Fractional calcium absorption was slightly but significantly greater from fortified bread than from milk (mean within subject difference = 0.0675 +/- 0.016). Calcium sulfate is a bioavailable fortificant for white bread that compares favorably with milk and two other salts.  相似文献   

THE BIOLOGICAL EFFECT OF HIGH VOLTAGE X-RAYS     

Packard C  Lauritsen CC 《Science (New York, N.Y.)》1931,73(1890):321-322

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