Threatened aquatic Andean frogs and mining activity in the Lithium Triangle of South America: Can both coexist?

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Magnetic microstructure of magnetotactic bacteria by electron holography

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.     

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

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.     

水分胁迫下4种冷季型草坪草抗旱性比较研究

采用盆栽育苗法,研究了4种冷季型草坪草在不同水分胁迫下的抗旱性,结果表明:1)随着水分胁迫程度的加深,4种冷季型草坪草的外观质量和叶片相对含水量显著下降,细胞质膜透性、MDA含量和Pro含量上升。2)模糊数学综合评价结果表明,4种冷季型草坪草种抗旱性能由强到弱的顺序为:高羊茅>多年生黑麦草>草地早熟禾>匍匐翦股颖。     

Collection mission ofH. chilense Roem. et Schult. in Chile and Argentina

Summary An expedition to Chile and Argentina was made with the main purpose of collecting representative samples of the genetic variability of the speciesHordeum chilense Roem. et Schult. During the field trips 55 populations ofH. chilense and 45 populations of otherHordeum species were collected. The habitats where the species were growing were analyzed.     

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

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.     

Larger islands house more bacterial taxa

The power law that describes the relationship between species richness and area size is one of the few generalizations in ecology, but recent studies show that this relationship differs for microbes. We demonstrate that the natural bacterial communities inhabiting small aquatic islands (treeholes) do indeed follow the species-area law. The result requires a re-evaluation of the current understanding of how natural microbial communities operate and implies that analogous processes structure both microbial communities and communities of larger organisms.     

Rib osteomyelitis in three foals

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.