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1.
To avoid the problems associated with twinning in dairy cattle, one of the embryos may be eliminated. This study compares the effect on pregnancy maintenance of two embryo reduction techniques, manual rupture (MR) and transvaginal ultrasound-guided aspiration (TUGA) of allanto-amniotic fluid, in Holstein-Friesian cows with multiple pregnancies. In the first experiment, 61 lactating cows bearing unilateral twins (n=27), bilateral twins (n=30) or triplets/quadruplets (n=4) were subjected to MR (n=45) or TUGA using a 17-G neddle (n=16) on day 28-34 of gestation. In 21 and 10 cows undergoing MR and TUGA embryo reduction, respectively, pregnancy loss occurred before day 90 (46.7 vs. 62.5%, P= 0.28). Through binary logistic regression, the type of pregnancy was identified as the only variable significantly affecting pregnancy maintenance (P=0.03). Based on the odds ratio, the risk of pregnancy loss was 4.1 times higher for unilateral twins than for bilateral twins (70.4 vs. 36.7%, respectively, P=0.01). No effect was detected on pregnancy maintenance of the technique used (P=0.17) or of the interaction technique by type of pregnancy (P=0.22). In the second experiment, a 22-G needle was used to perform TUGA on 22 lactating cows. The pregnancy loss rates were 44.4% (4/9), 18.2% (2/11) and 50% (1/2) for cows bearing unilateral twins, bilateral twins and triplets, respectively. The total pregnancy loss rate following TUGA using the 22-G needle tended to be lower than that using the 17-G needle (31.8 vs. 62.5%; P=0.06). Our results suggest that TUGA using a 22-G needle could be the method of choice to perform embryo reduction in cows carrying multiple pregnancies.  相似文献   
2.
In this work, the response of wheat (Triticum aestivum L.), rye (Secale cereale L.), oat (Avena sativa L.), and pea (Pisum sativum L.) to bromides of potassium (KBr) and ammonium (NH4Br) was studied. All plants were capable of accumulating high concentrations of bromine (Br). However, the Br accumulation depended on the Br compounds presented in the growth medium and plant species. The highest Br concentrations were observed in leaves and roots of the seedlings germinated in the medium spiked with KBr. Oat accumulated more Br than other plants and the lowest Br accumulation was observed in pea. The bioaccumulation of Br resulted in suppression of plant biomass and concentrations of several essential nutrients (K, Na, Ca, Mg, Zn and Cl). The most negative effects were caused by NH4Br. Probably, this action was due to cumulative effects of Br- and NH4+. Among other plant species, the most tolerant to bromides was oat and the most sensitive was wheat.  相似文献   
3.

Purpose

Humic substances (HS) being natural polyelectrolyte macromolecules with complex and disordered molecular structures are a key component of the terrestrial ecosystem. They have remarkable influence on environmental behavior of iron, the essential nutrient for plants. They might be considered as environmental friendly iron deficiency correctors free of synthetic iron (III) chelates disadvantages. The main goal of this study was to obtain water-soluble iron-rich humic compounds (IRHCs) and to evaluate their efficiency as chlorosis correctors.

Materials and methods

A facile preparation technique of IRHCs based on low-cost and available parent material was developed. The iron-containing precursor (ferrous sulfate) was added dropwisely into alkaline potassium humate solution under vigorous stirring and pH-control. A detailed characterization both of organic and inorganic parts of the compounds was provided, the iron species identification was carried out jointly by EXAFS and Mössbauer spectroscopy. Bioassay experiments were performed using cucumber Cucumis sativus L. as target plants. Plants were grown in modified Hoagland nutrient solution, prepared on deionized water and containing iron in the form of IRHCs. Total iron content in dry plants measured by spectrophotometry after oxidative digestion and the chlorophyll a content determined after acetone extraction from fresh plant were used as parameters illustrating plants functional status under iron deficiency condition.

Results and discussion

The high solubility (up to130 g/l) and iron content (about 11 wt%) of the IRHCs obtained allow considering them to be perspective for practical applications. A set of analytical methods has shown that the main iron species in IRHCs are finely dispersed iron (III) oxide and hydroxide nanoparticles. An application of the precursor solution acidification allows to obtain compounds containing a significant part of total iron (up to 30 %) in the form of partly disordered iron (II–III) hydroxysulphate green rust GR(SO4 2?). Bioavailability of iron from IRHCs was demonstrated using bioassay in cucumber plants grown up on hydroponics under iron deficiency conditions.

Conclusions

The application of iron oxides chemistry for humic substance containing solution was proved to be an effective approach to synthesis of IRHCs. Using bioassay on cucumber plants C. sativus L. under iron deficiency conditions, the efficiency of compounds obtained as chlorosis correctors was demonstrated. Application of water-soluble IRHCs led to significant increase of chlorophyll a content (up to 415 % of the blank) and iron content in plants (up to 364 % of the blank) grown up on hydroponics.  相似文献   
4.
To investigate the nutritional value of the marine micro‐alga Isochrysis galbana Tahitian Isochrysis strain (T.iso) as an alternative feed for aquaculture during culture age, its biochemical composition was studied under autotrophic and controlled culture conditions at different growth stages: exponential phase, early and late stationary phases and decay phase. Analysis showed that C14:0, C16:0, C16:1, C18:4 (n‐3) and C22:6 (n‐3) were the most abundant fatty acids in this alga at different growth stages. The highest values of monounsaturated fatty acids were recorded at the late stationary and the decay phases. However, the highest levels of polyunsaturated fatty acids were observed at the early stationary phase. At all growth stages, I. galbana (T.iso) contained arabinose, xylose, mannose, galactose and glucose. Glucose represented the main sugar, and its content per dry alga biomass weight increased with increasing age of the culture and reached about fourfold in the decay phase. The maximum protein content was also observed during this last phase.  相似文献   
5.
Temporal variability and spatial heterogeneity of surface runoff generation triggers the dynamics of source areas of sediment and sediment-associated nutrient transport. Reliable modelling of hydrological special situations i.e. snowmelt is of high importance for the quality of erosion and sediment yield modelling. Data from the research catchment Schäfertal demonstrate the individuality of snowmelt events in terms of runoff coefficient and delivery ratio. This 1.44 km2 low mountain catchment is characterised by a high portion of arable land with a winter grain/winter rape crop rotation. The integrated winter erosion and nutrient load model (IWAN) considers these dynamic aspects by coupling a hydrological model with a sediment load model. Cell size of this raster-based approach is 10 × 10 m2. Additionally, snowmelt rill erosion is simulated with a newly developed physically based model that is firstly applied on a catchment scale. A sensitivity analysis of this model system component demonstrates the plausibility of the model approach and the overall robustness of the model system IWAN. The results of the long-term hydrological modelling from 1991 to 2003 are reliable and form the basis for the simulation of six snowmelt events which were observed in the Schäfertal catchment. The estimated total runoff volumes for these events match the observations well. The modelled overland runoff coefficients vary from 0.001 to 0.72. The mean values of cell erosion, which were modelled with one set of parameters for all six events range from 0.0006 to 0.96 t ha− 1. The total modelled erosion for the events with unfrozen soil and low amount of surface runoff is of a factor 50 below those with partly frozen soil. In addition to these distinctions, the major differences are caused by flow accumulation in shallow depressions in variable parts of the catchment. However, the validation of these results on the single event scale is restricted due to limited spatial data. Total simulated sediment yield at the catchment outlet was as high as 13.84 t which underestimates the observed values, with the exception of one event. Oversimplification of the modelled channel processes may be a reason. The temporal variability and spatial heterogeneity of the surface roughness parameter, which was identified to be sensitive, also causes uncertainty in the parameter estimation. Despite these findings, the model system IWAN was applied successfully on the catchment scale and the simulated results are reliable.  相似文献   
6.
The risk of oil contamination, either through produced water discharges, accidents, or non-point-sources, has increased, and it is attributed with the negative impact on the Black Sea ecosystem, and especially in coastal waters. Coastal marine waters are known as the areas of fish and invertebrates spawning sites, including commercial species, which early developmental stages are highly sensitive to crude oil and its derivates. The aim of the present study was to investigate the effects of mazut at concentrations of 0.00001, 0.0001, 0.001, 0.01, 0.1, and 1 ml l−1 on the biomarker response in the developmental embryos (stages IV and V) of tubenose goby Proterorhinus marmoratus. We used the biomarkers of antioxidant enzyme activities, namely superoxide dismutase (SOD), catalase (CAT), peroxidase (PER) and glutathione reductase (GR). The non-uniform response on mazut impact at tested concentrations on fish embryos was shown. The best biomarker was peroxidase activity, which was highly sensitive to oil pollution and reflected the response of the organism on stressful environment. The imbalance between tested antioxidant enzyme activities was clearer at low and high levels of mazut, and it was less in the case of medium values. The obtained results can be applied for the development of oil toxicity tests for monitoring management and for perspectives of conservation ecology.  相似文献   
7.
CASE DESCRIPTION: A 6.5-year-old female eastern black and white colobus monkey (Colobus guereza) was evaluated after acute onset of ataxia and inappetence. CLINICAL FINDINGS: The monkey was ataxic and lethargic, but no other abnormalities were detected via physical examination, radiography, or clinicopathologic analyses. During the next 2 days, the monkey's clinical condition deteriorated, and its WBC count decreased dramatically. Cytologic examination of a CSF sample revealed marked lymphohistiocytic inflammation. TREATMENT AND OUTCOME: Despite supportive care, the monkey became apneic; after 20 hours of mechanical ventilation, fatal cardiac arrest occurred. At necropsy, numerous petechiae were detected within the white matter tracts of the brain; microscopic lesions of multifocal necrosis and hemorrhage with intranuclear inclusions identified in the brain and adrenal glands were consistent with an acute herpesvirus infection. A specific diagnosis of herpesvirus papio-2 (HVP-2) infection was made on the basis of results of serologic testing; PCR assay of tissue specimens; live virus isolation from the lungs; and immunohistochemical identification of the virus within brain, spinal cord, and adrenal gland lesions. Via phylogenetic tree analysis, the colobus HVP-2 isolate was grouped with neuroinvasive strains of the virus. The virus was most likely transmitted to the colobus monkey through toys shared with a nearby colony of baboons (the natural host of HVP-2). CLINICAL RELEVANCE: To the authors' knowledge, this is the first reported case of natural transmission of HVP-2 to a nonhost species. Infection with HVP-2 should be a differential diagnosis for acute encephalopathy in primate monkeys and humans, particularly following exposure to baboons.  相似文献   
8.
Journal of Soils and Sediments - The investigation of accumulation, migration, and transformation features of benzo[a]pyrene (BaP) in a soil-plant system by using new ecologically friendly...  相似文献   
9.
Changes in small-scale forest governance as a reaction to global changes are viewed from the system dynamics perspective, focused on two levels of dynamic systems: the policy system with sets of interactions at the national level and the management system at the local level. These interactions are considered through permanent adaptation and re-shaping of stakeholders’ networks and positions provoking further changes in the systems. Empirical evidence has been obtained from two case studies related to small-scale rural forestry in distinct contexts—France (the Territorial Forestry Charters) and Kyrgyzstan (collaborative forest management and leasing of forest plots)—and viewed through a theoretical framework of social-political systems dynamics. The changes caused by the systems’ capacity for adaptability and resilience are expressed through a double spiral of decision-making, characterising the interactions between national policies and local management practices. The analysis leads to a conclusion that changes are basically determined by the formal and informal stakeholders’ strategies developed in a specific context and their mutual adaptation aimed at system resilience.
Irina Kouplevatskaya-ButtoudEmail:
  相似文献   
10.
While previous studies have evaluated levels of tobacco-specific nitrosamines (TSNA) and total N-nitroso compounds (NOC) in tobacco, there are no reports in the literature on TSNA and total NOC in the same tobacco products. We compared levels of TSNA, total NOC, and NOC precursors (NOCP) in tobacco of cigarettes purchased in Moldova and in some tobacco types commonly used for the manufacturing of Moldovan cigarettes. Cigarette tobaccos included those from non-Moldovan, traditional Moldovan, and blended Moldovan cigarettes. The results demonstrate that tobacco of non-Moldovan cigarettes contains higher TSNA and NOC levels (mean, 16 and 63 nmol/g tobacco, n = 6) than that of Moldovan cigarettes (mean, 5 and 23 nmol/g tobacco, n = 25). TSNA and NOC levels were also generally higher in tobacco of blended than in traditional Moldovan cigarettes. NOCP levels in Moldovan and non-Moldovan cigarette tobacco were similar as follows: 29000 +/- 30000 and 33000 +/- 28000 nmol/g tobacco (mean +/- SD). Total NOC were strongly correlated with total TSNA levels (r = 0.66; P < 0.0001). These findings demonstrate that current technologies involved in the manufacture of some blended cigarettes create conditions that favor N-nitrosation of alkaloids and other tobacco constituents.  相似文献   
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