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101.
This study evaluated the antimicrobial effect of essential oils (EO) and organic acids (OA) against Salmonella Enteritidis in chicken feed and during an in vitro model that mimics the chicken digestive process. The minimal inhibitory concentration (MIC) of allyl isothiocyanate (AITC), carvacrol (CV), propionic acid (PROP) and caproic acid (CAP) were individually determined. Then, based on the MICs of each compound, combinations of EOs and/or OAs were tested to evaluate their synergic antimicrobial effect. The synergic effect of AITC and CAP was the most efficient against the bacterial strain tested. Commercial feed was inoculated with a 5‐strain cocktail of S. Enteritidis and treated with different doses of AITC + CAP to evaluate their effect on the growth/survival of the pathogen. In addition, the simulated digestion model was used to access the antimicrobial effect of AITC + CAP added to the feed towards S. Enteritidis and Lactobacillus plantarum. Synergistic effect was found between AITC (0.065 mM) and CAP (17.5 mM) against S. Enteritidis in chicken feed, where S. Enteritidis was reduced to undetectable levels (<1.00 log CFU/g). AITC (1.95 mM) + CAP (45 mM) also decreased (p < 0.05) the population of S. Enteritidis in the simulated digestion, while the growth of Lplantarum was not affected. Therefore, the addition of AITC + CAP in feed might be a potential natural antimicrobial able to prevent economic losses caused for Salmonella in chicken.  相似文献   
102.
Staphylococcus aureus is an opportunistic pathogen that may cause severe infections in livestock, and represents the major cause of mastitis in dairy cows. Currently, instead of using antibiotics, new strategies are sought to reduce this clinical health problem. The aim of this study was to determine the efficacy of phage therapy to kill S. aureus strains obtained from farms located at the State of Guanajuato, México. Thirty-six S. aureus strains from cow milk with subclinical mastitis were isolated and identified, and the susceptibility to antibiotics and four phages also isolated in this work was tested. It was found that more of 90% of S. aureus isolates were not susceptible to six or more antibiotics, and 100% were resistant to penicillin, dicloxacillin, cefotaxime, ampicillin and cephalothin, and 81 and 77%, to tetracycline and cefuroxime, respectively. Fortunately, 100% of S. aureus isolates were susceptible to phages used in this work, which was detected as clear zones using specific phage. It was shown for the first time, that phages used in this study are active against pathogenic S. aureus and might be incorporated into the therapy as an important tool for the control of staphylococcal bovine mastitis, specially to antibiotic-resistant S. aureus strains isolated in farm located at the state of Guanajuato, México; and its use might be extended to other regions inside or outside the country.  相似文献   
103.
104.
Partial migration is a common phenomenon in many fish species. Trout (Salmo trutta) is a partially migratory species where some part of the population migrate to the marine environment, while another remains in freshwater. In the years 2008 and 2009, a total of 159 wild sea trout smolts were tagged with acoustic and PIT‐tags in the river Villestrup (Denmark) to study the initial postsmolt marine behaviour within a fjord system. We found that the strategies of the sea migrants vary: some stay in the fjord, while others migrate to the sea, suggesting that partial migration occurs even in the marine environments. Overall, a total of 53% of the tagged smolts migrated from the fjord to the sea, and 47% stayed (or potentially died) in the fjord. The ratios of fjord‐resident versus sea‐migrating postsmolts were consistent at the study times, and no differences between the early and late migration periods of the smolts were observed. The individual's size or body condition at the time of tagging did not affect survival or the migratory decisions in the fjord. High overall initial survival (74%) was found 30 days after the fjord entry. We suggest that within a continuum of migration to sea, there is a migratory decision point when sea trout postsmolts encounter a fjord system. At this point, postsmolts will assess the possibility of migration versus the alternative of fjord residency.  相似文献   
105.
Bayesian inference was used to estimate the main population parameters (sex ratio, L50, LWR and somatic growth) and to evaluate sexual dimorphism and growth patterns (isometric/allometric and monophasic/biphasic growth) of Astyanax paranae of the Upper Paraná River. This study brings three statistical differentials: (a) the reparametrisation of the logistic model as a function of L50; (b) the reparameterisations of the LWR models based on the exponential of a piecewise linear regression to evaluate the hypotheses of polyphase growth; and (c) the first application of the recently proposed somatic growth models based only on length data to real data, as well as its expansion and generalisation. The models estimated L50 of females at 37.75 mm and sex ratio at 1.4 females per male. LWR models showed that both sexes presented biphasic growth with a lower increase in weight for males in first stanza. In second stanza, both sexes presented a greater increase in weight. Growth models showed that the growth rates were low, equal for both sexes in early life and slightly higher for females after the eighteenth months old. The studied population inhabits streams, therefore being exposed to constraining conditions that can limit the expression of their whole growth potential since they prioritise energy allocation for reproduction and survival, including reducing L50 in order to ensure the maintenance of the population. Finally, the complex biological patterns that arose from the proposed LWR and growth models demonstrated high potential and applicability for population studies.  相似文献   
106.
107.
Alcoholic extracts of seven plants belonging to the Solanaceae family were phytochemically screened and evaluated for their cytotoxic activity by Brine Shrimp Test (BST) with Artemia salina larvae, Inhibition of Cell Division Test (ICDT) on sea urchin Loxechinus albus fertilized eggs and inhibition of crown gall tumors on Potato Disk Bioassay (PDB). From Salpichroa diffusa, bioassay-guided chromatographic separation afforded some active fractions from which epi-katonic acid was identified.  相似文献   
108.
Little is known about ponderosa pine forest ecosystem responses to restoration practices in the Northern Rocky Mountains, USA. In this study, restoration treatments aimed at approximating historical forest structure and disturbances included modified single-tree selection cutting, with and without prescribed burning. We compared the effectiveness of restoration treatments on growth, vigor, and composition of recruitment responses with untreated controls. We used a randomized block design to detect treatment differences in mean individual tree basal area increment (BAInc10), growth efficiency (GE), and recruitment abundance between two restoration treatments (Cut-only and Cut-burn) and a Control. We further examined treatment effects by tree age-class (Young, Mature, Presettlement) using a spatial ANOVA model that incorporates the spatial autocorrelation among trees within experimental units. Ten years after implementing restoration treatments, mean individual tree BAInc10 and GE were significantly higher for treated units relative to Control units; all three age-classes benefited similarly from restoration treatments relative to the Control, with the greatest response in the Cut-only and moderate response in the Cut-burn. When treated units were compared, Cut-burn negatively affected BAInc10 and GE relative to Cut-only. Presettlement trees responded positively to treatment relative to the Control, particularly for BAInc10, demonstrating the potential of these old trees to respond to reduced competition. The Cut-burn treatment, in contrast, negatively affected the BAInc10 and GE response of postsettlement trees when compared to Cut-only. Restoration treatments did not reduce the amount of Douglas-fir recruits. In addition, the recruitment of both ponderosa pine and Douglas-fir species was associated with the proximate cover of woody debris in Cut-only and Control treatments. Finally, special consideration needs to be taken for spring Cut-burn treatments, which appeared to dampen growth and vigor, relative to Cut-only, particularly for Young and Mature trees, and increased recruitment of ponderosa pine and particularly Douglas-fir.  相似文献   
109.
The degradation of polyunsaturated fatty acids through the lipoxygenase pathway is responsible for the production of volatile compounds that confer green sensory notes to the aroma of fruits and vegetables. The peroxidation of free linoleic or linolenic acid by action of lipoxygenase and then the lysis of the resulting hydroperoxides, through a reaction catalyzed by the hydroperoxide lyase, are the most determinant steps of this pathway. This work analyzes the impact of the hydroperoxide lyase depletion on the volatile composition of leaves from Arabidopsis thaliana that is used as model system. The work involves the characterization of the volatile profiles of the Arabidopsis plants followed by a study of the metabolism of radio-labeled linoleic acid and determinations of lipoxygenase activity. Hydroperoxide lyase-knockout plants show similar levels of C6 compounds, but the total amount of C5 compounds is 4-fold higher in mutant plants. The perspectives of production of vegetable products with a modified aroma by genetically engineering the lipoxygenase pathway were discussed with respect to the statistical results.  相似文献   
110.
Humans create vast quantities of wastewater through inefficiencies and poor management of water systems. The wasting of water poses sustainability challenges, depletes energy reserves, and undermines human water security and ecosystem health. Here we review emerging approaches for reusing wastewater and minimizing its generation. These complementary options make the most of scarce freshwater resources, serve the varying water needs of both developed and developing countries, and confer a variety of environmental benefits. Their widespread adoption will require changing how freshwater is sourced, used, managed, and priced.  相似文献   
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