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101.
Tetravalent uranium in calcite 总被引:1,自引:0,他引:1
NC Sturchio MR Antonio L Soderholm SR Sutton JC Brannon 《Science (New York, N.Y.)》1998,281(5379):971-973
X-ray absorption spectroscopy and x-ray fluorescence microprobe studies of 35-million-year-old calcite from a Mississippi Valley-type zinc ore deposit indicate substitution of tetravalent uranium for divalent calcium. Thus, tetravalent uranium has a stable location in calcite deposited under reducing conditions. This result validates uranium-series dating methods (including uranium/lead dating) for ancient calcite and shows that calcite provides a sink for uranium in deep groundwater aquifers and anoxic lacustrine and marine basins. 相似文献
102.
103.
SUMMARY This paper reviews the laboratory diagnosis of Leptospira hardjo infection in cattle. Two genotypes of L hardjo, Hardjoprajitno and Hardjobovis, have been identified in cattle, but only Hardjobovis has been isolated in Australia. There are problems with diagnosis and control of bovine leptospirosis. Infection is usually subclinical and the serological titres vary greatly in peak and duration. Leptospires may be excreted in urine for up to 18 months. Low microscopic agglutination test titres may be significant in unvaccinated herds as indicators of endemic infection. Vaccines differ in their composition, and their efficacy is difficult to evaluate. The serological response after vaccination is difficult to differentiate from the response after infection. Pregnant cows that become infected may abort, but this is usually after the serological response has peaked. Therefore, paired serum samples are of little use in diagnosing abortion caused by L hardjo. Fluorescent antibody techniques are more sensitive than dark field microscopy for detection of leptospires in urine and tissue samples. Techniques for culture have improved but are still difficult to perform and take 3 months or longer for results to be known. DNA probes and polymerase chain reaction tests are very sensitive and specific, quick to perform, and can be used on fluid and tissue samples. 相似文献
104.
Sublethal effects of the insecticidal fusion protein ω‐ACTX‐Hv1a/GNA on the parasitoid Eulophus pennicornis via its host Lacanobia oleracea 下载免费PDF全文
105.
Isaac Kiyingi Abdi-Khalil Edriss Alexander MR Phiri Buyinza Mukadasi Susan Tumwebaze Hillary Agaba 《Southern Forests》2016,78(3):201-208
This study assessed the amount of carbon stored and the economic viability of the small-scale Clean Development Mechanism (CDM) carbon offsets in Pinus caribaea and Eucalyptus grandis plantations under varying rotations. Volume equations were used to estimate carbon stocks and merchantable wood volume in the plantations, while net present value (NPV) and annual equivalent value (AEV) were used as measures of profitability at the optimum economic rotation age as well as at the CDM-defined crediting period of 20 years. The findings show that over a 20-year rotation, E. grandis and P. caribaea plantations sequestered 638 and 418 t CO2-e ha?1, respectively. The NPVs of E. grandis and P. caribaea with carbon credits over the CDM carbon-crediting period of 20 years were US$2 540 ha?1 and US$1 814 ha?1, respectively. This is higher than the NPVs without carbon credits of US$1 543 ha?1 and US$1 390 ha?1 for E. grandis and P. caribaea, respectively. The AEV of E. grandis harvested at its optimal economic rotation of 10 years was US$316 ha?1. This is slightly higher than the AEV of US$298 ha?1, utilising the CDM carbon-crediting period of 20 years. In contrast, the AEV of P. caribaea under the 20-year CDM carbon-crediting period was higher than harvesting at the optimal economic rotation of 16 years without carbon credits. When the average CDM contract establishment costs exceed US$500 ha?1 and US$1 000 ha?1 for P. caribaea and E. grandis woodlots, respectively, it is not economically viable for one to participate in the CDM forest carbon offsets programme. In conclusion, the study results indicate that whereas E. grandis has a higher biological potential to sequester carbon than P. caribaea, it is currently not economically viable for participation in the CDM forest carbon offset scheme. In contrast, it is economically viable for P. caribaea plantations to participate in the CDM, if the CDM contract establishment costs are low. 相似文献
106.
MR Namazi 《Journal of Autoimmune Diseases》2009,6(1):4
The Cytochrome-P-450 enzymes (CYP) are among the most important xenobiotic-metabolizing enzymes, which produce reactive oxygen species (ROS) as the result of metabolizing xenobiotics.ROS are believed to play important roles in the pathophysiology of autoimmune diseases. ROS can alter the structure of cellular antigens to produce a "neo-antigen" which could mount an autoimmune response against the original antigen through molecular mimicry. ROS are involved in apoptosis, activation of antigen presenting cells and initiation or amplification of diverse immunologic reactions.Taking all these facts together, it could be speculated that CYP may be involved in the initiation and/or amplification of autoimmune phenomena. 相似文献
107.
Effects of supplemental dietary vitamin C on quality of semen from Nile tilapia (Oreochromis niloticus) breeders 下载免费PDF全文
NLAF Sarmento EFF Martins DC Costa WS Silva CC Mattioli MR Luz RK Luz 《Reproduction in domestic animals》2017,52(1):144-152
The objective of this study was to evaluate the effects of vitamin C on growth and quality of semen from Oreochromis niloticus breeders. One hundred and sixty males were fed with different levels of vitamin C (0, 261, 599 and 942 mg/kg diet). The higher weight values were recorded for 599 (166 g) and 942 (175 g) mg of vitamin C/kg diet. Sperm motility, vigour and concentration were higher with 599 and 942 mg of vitamin C/kg diet. The semen volume, gonadosomatic index and plasma protein data from the last week showed a direct relationship with increasing levels of vitamin C. No changes were observed in the hepatosomatic index and blood glucose. The haematocrit and erythrocyte showed higher values estimated by equations derived at 850 and 638 mg vitamin C/kg diet, respectively. The leucocytes were inversely proportional to the increasing levels of vitamin C. After 100 days of feeding, animals fed the diet containing 942 mg vitamin C/kg diet had higher sperm motility, linearity, curvilinear velocity, straight line velocity and average path velocity (p < .05). Higher values of beat cross‐frequency were observed in broodfish fed diets containing 942 and 599 mg vitamin C/kg. The different vitamin C levels did not cause differences in straightness, lateral head displacement and sperm morphology. For Nile tilapia males on intensive rearing and handling conditions, vitamin C levels between 599 and 942 mg/kg may be used for a better performance and quality of semen. 相似文献
108.
Fatemeh Nikmard Elham Hosseini Mehrdad Bakhtiyari Mahnaz Ashrafi Fardin Amidi Reza Aflatoonian 《Animal Science Journal》2017,88(4):586-592
The purpose of oocyte in vitro maturation is generation of mature oocytes that could support future development. Efforts have been made to enhance oocyte developmental competence by developing optimal culture conditions. The present study is conducted to determine melatonin effects on quality of polycystic ovarian syndrome (PCOS) oocytes when it has been added during in vitro maturation, and immature oocytes were cultured in defined conditioned medium with and without different melatonin concentrations. Melatonin could significantly improve nuclear maturation of PCOS oocytes (81.1% vs. 56.3%, P < 0.05 were achieved with 10?6 mol/L concentration). Cleavage rate was significantly higher in 10?5 mol/L concentration compared to untreated oocytes in PCOS (54% vs. 35%, respectively) and it was significantly higher with 10?6 mol/L concentration in the control group, 55% versus 38%, compared to untreated oocytes. This study showed that melatonin has the potential to induce oocyte nuclear maturation and guarantee fertilization potential. © 2016 Japanese Society of Animal Science 相似文献
109.
ÁE Domínguez‐Rebolledo F Martínez‐Pastor MR Fernández‐Santos E Del Olmo A Bisbal JL Ros‐Santaella JJ Garde 《Reproduction in domestic animals》2010,45(6):e360-e368
Several methods are used to measure lipid peroxidation (LPO) in spermatozoa. The objective of this study was comparing the thiobarbituric acid reactive species (TBARS) method and the BODIPY 581/591 C11 (B581) and BODIPY 665/676 C11 (B665) fluorescent probes to measure induced peroxidative damage in thawed epididymal spermatozoa from Iberian red deer. Samples from three males were thawed, pooled, diluted in PBS, incubated at room temperature and assessed at 0, 3, 6 and 24 h under different experimental conditions: Control, hydrogen peroxide (H2O2) 0.1 mm or 1 mm , or tert‐butyl hydroperoxide (TBH) 0.1 mm or 1 mm . LPO was assessed by the TBARS assay [malondialdehyde (MDA) detection] and by the fluorescence probes B581 and B665 (microplate fluorimeter and flow cytometry). Increasing MDA levels were only detectable at 1 mm of TBH or H2O2. Both fluorescence probes, measured with fluorometer, detected significant increases of LPO with time in all treatments, except Control. Flow cytometry allowed for higher sensitivity, with both probes showing a significant linear relationship of increasing LPO with time for all oxidizing treatments (p < 0.001). All methods showed a good agreement, except TBARS, and flow cytometry showed the highest repeatability. Our results show that both B581 and B665 might be used for LPO analysis in Iberian red deer epididymal spermatozoa, together with fluorometry or flow cytometry. Yet, the TBARS method offered comparatively limited sensitivity, and further research must determine the source of that limitation. 相似文献
110.
A Dalman P Eftekhari‐Yazdi MR Valojerdi A Shahverdi H Gourabi E Janzamin R Fakheri F Sadeghian F Hasani 《Reproduction in domestic animals》2010,45(5):e46-e53
Cell cycle stage and synchronization of donor cells are important factors influencing the success of somatic cell nuclear transfer. This study examined whether serum starvation has any effect on specific cell death. We also studied the effects of serum starvation, culture to confluence, and full confluency (confluent + 72 h) on cell cycle characteristics and apoptosis of goat dermal fibroblast cells. The cells were obtained from the ear of a 1.5‐year‐old female goat. The following experimental groups were analysed for fibroblast cells: (i) normally growing, (ii) confluent, (iii) full confluency, (iv) cells starved for 48 h and (v) cells starved for 72 h. Analysis of cell cycle distribution by flow cytometry showed that 4.56 and 51.88% of normal cycling cells were at the G0 and G1 phases respectively. In the confluent group, 80% of the cells were arrested in the G0/G1 phase. Serum starvation for 48 and 72 h arrested 84.78% and 90.1% cells at the G0/G1 phase respectively which showed a significant difference when compared with the control group (p < 0.05). Double staining by PI and FITC distinguishes G0 phase from G1 phase. In the full confluency group, 91.53% of cells were at G0/G1 stage, but in contrast to the serum starved group, this high percentage of G0/G1 cells was mainly associated with G1 cells. Under normal culture conditions, 6.39% of cells underwent early apoptosis. In the confluent group 8.93% of cells showed early apoptosis. Serum starvation for 48 and 72 h caused early apoptosis in 8.91 and 39.83% of the cells respectively. Full confluency treatment did not increase the number of apoptotic cells significantly (8.67%). After 72 h, serum starvation significantly increased early apoptosis (p < 0.05). In conclusion, the use of full confluency is suitable for cell cycle synchronization because it arrests cells at the G0/G1 phase and also induces less apoptosis in comparison with the serum starvation group. 相似文献