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排序方式: 共有439条查询结果,搜索用时 218 毫秒
91.
Esmeralda Delgado Isabel P Fonseca Isabel Fazendeiro Olga Matos Francisco Antunes Margarida B Cunha 《Journal of zoo and wildlife medicine》2003,34(4):352-356
Feces from 34 species of ruminants housed at the Lisbon Zoo was examined for Cryptosporidium spp. oocysts. Three hundred and eighty-eight samples were analyzed. Three hundred and eighty species-specific group fecal samples were collected monthly, from September 1998 until August 1999, along with eight individual specimens from eight neonates. All samples were examined by four different techniques: microscopic observation of direct and concentrated fecal smears, staining with modified Ziehl-Nielsen, immunofluorescent assay, and immunoenzymatic assay. The prevalence of infection was 3.6%. Five neonates with diarrhea were infected. Cryptosporidial oocysts were shed more frequently during winter months. Some facilities may have permitted oocysts to remain viable, possibly contributing to cryptosporidial transmission between animals. 相似文献
92.
93.
Olga Blanco Prieto Jaime Cataln Marcel Lleonart Sergi Bonet Marc Yeste Joan E. Rodríguez‐Gil 《Reproduction in domestic animals》2019,54(8):1145-1148
A survey of in vivo fertility data from 31 pig farms distributed worldwide was conducted to determine whether stimulating boar semen with LED‐based red light increases its reproductive performance following artificial insemination (AI). Red‐light stimulation with MaXipig® was found to increase farrowing rates (mean ± SEM, control: 87.2% ± 0.4% vs. light stimulation 90.3% ± 0.5%) and the number of both total and live newborn piglets. Red‐light stimulation increased farrowing rates in 27 farms, with an increase ranging from 0.2% to 9.1%. Similar results were observed in litter sizes. Suboptimal management after AI was suggested in those farms with no response to red‐light stimulation. Our results indicate that a routine use of red‐light stimulation of boar semen can have a positive effect on the reproductive performance. However, the effectiveness of this system appears to highly rely upon proper management of pig farms. 相似文献
94.
María Iniesta‐Cuerda Irene Snchez‐Ajofrín Olga García‐lvarez Alicia Martín‐Maestro Patricia Peris‐Frau Jos Antonio Ortiz María Rocío Fernndez‐Santos Jos Julin Garde Ana J. Soler 《Reproduction in domestic animals》2019,54(Z4):69-71
Nowadays, the use of foetal calf serum (FCS) during in vitro embryo culture is very controversial. Whilst some authors have encouraged its use, others reject it because of its harmful effects. Although in vitro embryo production in red deer is a promising assisted reproductive technique, it is still in its infancy and a great effort is needed to update the protocols used. The aim of this study was to assess whether FCS supplementation in red deer embryo culture medium is necessary to produce blastocyst and, if so, when is the best time to add it in terms of blastocyst production and quality. In vitro blastocysts were cultured with FCS added at 24, 48 or 96 hours post‐insemination (hpi). In addition, a treatment without FCS was used as control. Six hundred and ninety‐four cumulus–oocyte complexes were collected for in vitro fertilization. Cleavage rate was examined at 48 hpi, and blastocyst yield was recorded on days 6, 7 and 8. FCS had no influence on cleavage and blastocyst rate for any of the treatments studied. However, the number of cells was higher (p = .025) in those blastocysts cultured with FCS from 48 hpi compared with FCS‐free culture media (93.88 ± 7.76 vs. 54.11 ± 8.36). In conclusion, the addition of FCS to the embryo culture medium at 48 hpi improves the quality of red deer blastocyst, although it does not affect the percentage of embryos obtained. 相似文献
95.
Olga A. Kildisheva Todd E. Erickson David J. Merritt Matthew D. Madsen Kingsley W. Dixon Jacqueline Vargas Remy Amarteifio Andrea T. Kramer 《Strength and Conditioning Journal》2018,71(3):318-322
Seed dormancy can present a significant barrier to restoration outcomes in dryland systems. Physical and combinational (physical + physiological) dormancy are prevalent among seeds of many herbaceous perennials used in restoration of drylands throughout the western United States. Although many techniques designed to alleviate these dormancy traits exist, their efficacy is species specific, may result in embryo damage, and may have limited large-scale application. To identify the most effective means of dormancy alleviation with the potential to be used on an operational scale, we examined the effects of 16 temperature-based techniques (altering temperature and duration of wet heat, freezing and wet heat, and freeze-thaw cycles) and 6 abrasion-based techniques (altering pneumatic scarification length or using a single duration of manual scarification) on the enhancement of seed permeability among two physically dormant (western prairie clover [Dalea ornata {Douglas} Eaton & Wright] and Munro’s globemallow [Sphaeralcea munroana {Douglas} Spach]) and two combinationally dormant species (basalt milkvetch [Astragalus filipes Torr. ex A. Gray] and longspur lupine [Lupinus arbustus {Douglas} ex Lindl.]). We first assessed seed imbibition following exposure to all temperature- and abrasion-based techniques to identify those most successful at promoting seed permeability and then evaluated the effectiveness of those techniques through a series of germination experiments. For combinationally dormant species, we also tested whether exposure to GA3 enhanced germination. Abrasion-based techniques were more effective than temperature-based techniques at improving water uptake across all species. Pneumatic scarification significantly improved germination, but optimal treatment durations were species specific. GA3 did not enhance germination under the tested conditions. We conclude that pneumatic scarification is a fast, safe, and effective method for alleviating physical seed dormancy with a potential to be scaled up for operational use in restoration. 相似文献
96.
The polyacrylamide gel electrophoresis of chernozem humic acids (HAs) followed by ultraviolet detection (λ = 312 nm) has revealed a new highly fluorescent fraction that has the highest electrophoretic mobility and the lowest nominal molecular weight (NMW). The preparative isolation of the fraction has been performed using the multiple microfiltration of the same HA sample in a 7 M carbamide solution on a membrane with a nominal pore size of 5 kDa. Thirty ultrafiltrates with NMW < 5 kDa and different fluorescence maximums in the region of 475–505 nm have been prepared, as well as a nonfluorescent concentrate with NMW > 5 kDa. Fluorescence maximums at and below 490 nm have been noted only in the first four ultrafiltrates. All the ultrafiltrates have been combined into the fraction with NMW < 5 kDa, which has been successively passed through membranes of 3 and 1 kDa. Solutions of subfractions F 3–5 kDa, F 1–3 kDa, and F < 1 kDa with fluorescence maximums at 505, 488, and 465 nm, respectively, have been prepared. The F < 1 kDa subfraction with the lowest NMW had the highest fluorescence intensity. The distribution of the fluorescence maximums in the ultrafiltrates has indicated the presence of at least two groups of fluorophores and has confirmed the supramolecular organization of the extracted soil HAs. 相似文献
97.
The antimicrobial activity of infusion, decoction, ethanol extract and fractions obtained by successive extraction of Viola tricolor herb with dichloromethane, ethyl acetate and methanol was evaluated. The infusion, decoction and ethanol extract were found to be most effective against the tested microorganisms. 相似文献
98.
Takuya Kajimoto Akira Osawa Yojiro Matsuura Anatoly P. Abaimov Olga A. Zyryanova Kazuma Kondo Naoko Tokuchi Muneto Hirobe 《Journal of Forest Research》2007,12(2):103-112
We present results of individual-based root system measurement and analysis applied for Larix gmelinii trees growing on the continuous permafrost region of central Siberia. The data of root excavation taken from the three stands
were used for the analyses; young (26 years old), mature (105 years old), and uneven-aged over-mature stand (220 years old).
In this article, we highlight two topics: (1) factors affecting spatio-temporal pattern of root system development, and (2)
interactions between aboveground (i.e., crown) and belowground (i.e., root) competition. For the first topic, the detailed
observation of lateral roots was applied to one sample tree of the overmature stand. The tree constructed a superficial (<30 cm
in depth) and rather asymmetric root system, and each lateral root expanded mainly into elevated mounds rather than depressed
troughs. This indicated that spatial development of an individual root system was largely affected by microtopography (i.e.,
earth hummocks). For these lateral roots, elongation growth curves were reconstructed using annual-ring data, and annual growth
rates and patterns were compared among them. The comparison suggested that temporal root system development is associated
with differences in carbon allocation among the lateral roots. For the second topic, we examined relationships between individual
crown projection area (CA) and horizontal rooting area (RA) for the sample trees of each stand. RA was almost equal to CA
in the young stand, while RA was much larger (three or four times) than CA in the mature and overmature stands. Two measures
of stand-level space occupation, crown area index (aboveground: CAI; sum of CAs per unit land area) and rooting area index
(belowground: RAI; sum of RAs), were estimated in each stand. The estimates of RAI (1.3–1.8 m2 m−2) exceeded unity in all stands. In contrast, CAI exceeded unity (1.3 m2 m−2) only in the young stand, and was much smaller (<0.3 m2 m−2) in the two older stands. These between-stand differences in RAI–CAI relationships suggest that intertree competition for
both aboveground and belowground spaces occurred in the young stand, but only belowground competition still occurred in the
two older stands. Based on this finding, we hypothesized that competition below the ground may become predominant as a stand
ages in L. gmelinii forests. Methodological limitations of our analysis are also discussed, especially for the analysis using the two indices
of space occupation (CAI, RAI). 相似文献
99.
Rojas-Graü MA Avena-Bustillos RJ Friedman M Henika PR Martín-Belloso O McHugh TH 《Journal of agricultural and food chemistry》2006,54(24):9262-9267
Edible films, as carriers of antimicrobial compounds, constitute an approach for incorporating plant essential oils (EOs) onto fresh-cut fruit surfaces. The effect against Escherichia coli O157:H7 of oregano, cinnamon, and lemongrass oils in apple puree film-forming solution (APFFS) and in an edible film made from the apple puree solution (APEF) was investigated along with the mechanical and physical properties of the films. Bactericidal activities of APFFS, expressed as BA50 values (BA50 values are defined as the percentage of antimicrobial that killed 50% of the bacteria under the test conditions) ranged from 0.019% for oregano oil to 0.094% for cinnamon oil. Oregano oil in the apple puree and in the film was highly effective against E. coli O157:H7. The data show that (a) the order of antimicrobial activities was oregano oil > lemongrass oil > cinnamon oil and (b) addition of the essential oils into film-forming solution decreased water vapor permeability and increased oxygen permeability, but did not significantly alter the tensile properties of the films. These results show that plant-derived essential oils can be used to prepare apple-based antimicrobial edible films for various food applications. 相似文献
100.
Qian W Miki D Zhang H Liu Y Zhang X Tang K Kan Y La H Li X Li S Zhu X Shi X Zhang K Pontes O Chen X Liu R Gong Z Zhu JK 《Science (New York, N.Y.)》2012,336(6087):1445-1448
Active DNA demethylation is an important part of epigenetic regulation in plants and animals. How active DNA demethylation is regulated and its relationship with histone modification patterns are unclear. Here, we report the discovery of IDM1, a regulator of DNA demethylation in Arabidopsis. IDM1 is required for preventing DNA hypermethylation of highly homologous multicopy genes and other repetitive sequences that are normally targeted for active DNA demethylation by Repressor of Silencing 1 and related 5-methylcytosine DNA glycosylases. IDM1 binds methylated DNA at chromatin sites lacking histone H3K4 di- or trimethylation and acetylates H3 to create a chromatin environment permissible for 5-methylcytosine DNA glycosylases to function. Our study reveals how some genes are indicated by multiple epigenetic marks for active DNA demethylation and protection from silencing. 相似文献