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381.
Woo Jung Kim Joo Woong Park Jae Kweon Park Doo Jin Choi Yong Il Park 《Marine drugs》2015,13(7):4398-4417
The Search for enzyme activities that efficiently degrade marine polysaccharides is becoming an increasingly important area for both structural analysis and production of lower-molecular weight oligosaccharides. In this study, an endo-acting fucoidanase that degrades Miyeokgui fucoidan (MF), a sulfated galactofucan isolated from the sporophyll (called Miyeokgui in Korean) of Undaria pinnatifida, into smaller-sized galactofuco-oligosaccharides (1000–4000 Da) was purified from a marine bacterium, Sphingomonas paucimobilis PF-1, by ammonium sulfate precipitation, diethylaminoethyl (DEAE)-Sepharose column chromatography, and chromatofocusing. The specific activity of this enzyme was approximately 112-fold higher than that of the crude enzyme, and its molecular weight was approximately 130 kDa (FNase S), as determined by native gel electrophoresis and 130 (S1), 70 (S2) and 60 (S3) kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH and temperature of FNase S were pH 6.0–7.0 and 40–45 °C, respectively. FNase S activity was enhanced by Mn2+ and Na+ (115.7% and 131.2%), but it was inhibited by Ca2+, K+, Ba2+, Cu2+ (96%, 83.7%, 84.3%, and 89.3%, respectively), each at 1 mM. The Km, Vmax and Kcat values of FNase S on MF were 1.7 mM, 0.62 mg·min−1, and 0.38·S−1, respectively. This enzyme could be a valuable tool for the structural analysis of fucoidans and production of bioactive fuco-oligosaccharides. 相似文献
382.
Effects of dietary substitution of fishmeal with the combined dry microalgae,Nannochloropsis oceanica (NO) biomass residue and casein on growth and body composition of juvenile abalone (Haliotis discus)
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Sung Hyo Myung Won‐Gwan Jung Hee Sung Kim Ye Eun Kim Sung Hwoan Cho Min Seok Jwa Pil Youn Kim Mun Kwan Kim Min‐Woo Park Byeng‐Hak Kim 《Aquaculture Research》2016,47(1):341-348
The effects of dietary substitution of fishmeal with the combined dry Nannochloropsis oceanica (NO) biomass residue and casein on growth performance and carcass composition of juvenile abalone was determined. One thousand two hundred and sixty juvenile abalone were randomly distributed into the 18 L plastic rectangular containers. Five experimental diets in triplicate were prepared. The 28% fishmeal was included into the control (Con) diet. The 25%, 50%, 75% and 100% fishmeal were substituted with the combination of graded levels of dry NO biomass residue and casein, referred to as the NO25, NO50, NO75 and NO100 diets respectively. Finally, the salted sea tangle (ST), Laminaria japonica was prepared to compare the effect of the experimental diets on performance of abalone. The essential amino acids, such as isoleucine, leucine, phenylalanine, threonine and valine tended to increase with dietary substitution of fishmeal with NO biomass residue in the experimental diets. Arginine tended to decrease with dietary substitution of fishmeal with NO biomass residue. Survival of abalone fed the experimental diets was higher than that of abalone fed the ST diet for 16 weeks. Weight gain and specific growth rate (SGR) of abalone fed the NO100 diet were higher than those of abalone fed the all other diets. Weight gain and SGR of abalone linearly increased with dietary substation of fishmeal with NO. Shell length of abalone tended to increase with dietary substitution of fishmeal with the combined dry NO biomass residue and casein. The chemical composition of the soft body of abalone was different among treatments except for moisture content. In conclusion, fishmeal in the diets for abalone could be completely replaced with the combined dry NO biomass residue and casein when the 28% fishmeal was included. 相似文献
383.
384.
Cytogenetic analysis of hybrids and hybrid triploids between the river puffer,Takifugu obscurus,and the tiger puffer,Takifugu rubripes
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Gwang Yeol Yoo Tae Ho Lee Hyun Woo Gil Sang Gu Lim In‐Seok Park 《Aquaculture Research》2018,49(2):637-650
Cytogenetic analyses of the river puffer, Takifugu obscurus, the tiger puffer, Takifugu rubripes and hybrids produced between female T. obscurus and male T. rubripes and their hybrid triploids (produced by cold shock treatment at 4°C) were performed. T. obscurus had 2n = 44 chromosomes and 1.84 ± 0.019 pg DNA/cell, T. rubripes had 2n = 44 and 2.64 ± 0.015, the hybrids had 2n = 44 and 2.15 ± 0.010 and the hybrid triploids had 3n = 66 and 3.22 ± 0.010. The erythrocyte values of the hybrids were more similar to those for T. obscurus, whereas the hepatocyte, midgut and proximal tubule kidney cell values of the hybrids fell down between those for the parental species (p < .05). The erythrocyte, proximal tubule, hepatocyte and midgut epithelial cell sizes for the hybrid triploids were 1.5‐fold larger than those for the hybrids (p < .05). The thickness of retina and each layer in the hybrid triploids were 1.1‐fold larger than those of the hybrids (p < .05) and did not differ significantly among T. obscurus, T. rubripes and the hybrids (p > .05); however, the hybrid triploids had fewer cell nucleus outer layers than the hybrids (p < .05). Gonad development in the hybrids and hybrid triploids was less matured than in T. obscurus and T. rubripes. The metaphase nucleolus organizer regions (NORs) and the gill cells of T. obscurus, T. rubripes and the hybrids contained two satellite telocentrics, whereas the hybrid triploids contained three satellite telocentrics. 相似文献
385.
Cotton fabrics exhibiting superhydrophobic and antibacterial properties were prepared through a non-solvent induced phase separation method using hydrophobic poly(vinylidene fluoride) (PVDF) and its hybrids with photocatalytic zinc oxide nanoparticles (nano-ZnO) as surface modifying agents for cotton fabric. The effects of coagulating medium and temperature on microstructural morphology and surface hydrophobictity of the cotton fabrics were investigated by FE-SEM observation and contact angle measurement. Superhydrophobic cotton fabrics exhibiting water contact angle higher than 150 ° could be obtained by coating the fabrics with solutions of PVDF and nano-ZnO followed by coagulation in ethanol as non-solvent. This phenomenon is considered to be originated from both chemically hydrophobic PVDF layer and physical micro- and nano-bumps formed on the surface of cotton fabric, which are essential requirements for Lotus effect. Moreover, antibacterial properties could be synergistically obtained by utilizing photocatalytic effect of nano-ZnO. 相似文献
386.
Background:Whey permeate is an effective lactose source for nursery pigs and the most benefits are obtained when pigs are at 7 to 11 kg BW.Altering weaning ages could cause different length of early-weaner phases until 7 kg BW and thus it would influence the dietary need of whey permeate during 7 to 11 kg BW of pigs.This study aimed to evaluate if weaning ages would affect the dietary needs of whey permeate for optimum growth performance of pigs at 7 to 11 kg BW.Methods:A total of 1,632 pigs were weaned at d 21(d 21.2±1.3)or d 25(d 24.6±1.1)after birth.All pigs had a common early-weaner feeds until they reached 7 kg BW.When pigs reached 7 kg BW within a weaning age group,they were allotted in a randomized complete block design(2×4 factorial).Two factors were weaning age groups(21 and 25 d of age)and varying whey permeate levels(7.50%,11.25%,15.00%,and 18.75%).Data were analyzed using the GLM and NLIN procedures of SAS for slope-ratio and broken-line analyses to determine the growth response to whey permeate and optimal daily whey permeate intake for the growth of the pigs weaned at different ages.Results:Pigs weaned at 21 d of age had a common diet for 11 d to reach 7 kg BW whereas pigs weaned at 25 d of age needed 2 d.The G:F of pigs weaned at 25 d of age responded to increased daily whey permeate intake greater(P<0.05)than pigs weaned at 21 d of age.Breakpoints were obtained(P<0.05)at 88 and 60 g/d daily whey permeate intake or 17.0%and 14.4%of whey permeate for G:F of pigs weaned at 21 and 25 d of age,respectively.Conclusion:Pigs weaned at an older age with a short early-weaner phase had a greater growth response to whey permeate intake compared with pigs weaned at a younger age with a long early-weaner phase.Altering weaning ages affected dietary needs of whey permeate for optimum growth performance of pigs from 7 to 11 kg BW. 相似文献
387.
We have prepared a series of polypropylene/exfoliated graphene (PP/EG) nanocomposite films via efficient meltcompounding and
compression, and investigated their morphology, structures, thermal transition behavior, thermal stability, electrical and
mechanical properties as a function of EG content. For the purpose, EG, which is composed of disordered graphene platelets
as reinforcing nanoscale fillers, is prepared by the oxidation/exfoliation process of natural graphite flakes. SEM images
and X-ray diffraction data confirm that the graphene platelets of EG are well dispersed in PP matrix for the nanocomposites
with EG contents less than 1.0 wt%. It is found that thermo-oxidative degradation of PP/EG nanocomposites is noticeably retarded
with the increasing of EG content. Electrical resistivity of the nanocomposite films was dramatically changed from ∼1016 to ∼106 Ω·cm by forming electrical percolation threshold at an certain EG content between 1 and 3 wt%. Tensile drawing experiments
demonstrate that yielding strength and initial modulus of PP/EG nanocomposite films are highly improved with the increment
of EG content. 相似文献
388.
Six pine species or hybrids were tested for susceptibility to pitch canker caused by Fusarium circinatum. Pinus densiflora, Pinus thunbergii, Pinus x rigitaeda (Pinus rigida × Pinus taeda), P. rigida × P. x rigitaeda, Pinus echinata and Pinus virginiana were inoculated with three spore loads (50, 500 and 5000 per tree) of F. circinatum. External symptoms, lesion length, and the frequency of reisolation of the fungus were investigated. External symptoms were greatest in P. echinata, followed by P. virginiana, however, P. densiflora was not susceptible to F. circinatum. Based on mean lesion lengths, the six pine species or hybrids differed significantly (p < 0.01) in susceptibility to pitch canker. Pinus echinata sustained the longest lesions, whereas P. densiflora sustained the shortest lesions. The effect of inoculum density was not significant among three spore treatments within species (p = 0.17), although lesion length was slightly greater at higher spore loads over all pine species. The fungus was reisolated from inoculated stems of all pine species tested, even on trees showing little or no damage from the disease. Additional studies are needed to further explore the basis for resistance to pitch canker. 相似文献
389.
Francesco Vinale Krishnapillai Sivasithamparam Emilio L. Ghisalberti Roberta Marra Sheridan L. Woo Matteo Lorito 《Soil biology & biochemistry》2008,40(1):1-10
Biological control involves the use of beneficial organisms, their genes, and/or products, such as metabolites, that reduce the negative effects of plant pathogens and promote positive responses by the plant. Disease suppression, as mediated by biocontrol agents, is the consequence of the interactions between the plant, pathogens, and the microbial community. Antagonists belonging to the genus Trichoderma are among the most commonly isolated soil fungi. Due to their ability to protect plants and contain pathogen populations under different soil conditions, these fungi have been widely studied and commercially marketed as biopesticides, biofertilizers and soil amendments. Trichoderma spp. also produce numerous biologically active compounds, including cell wall degrading enzymes, and secondary metabolites. Studies of the three-way relationship established with Trichoderma, the plant and the pathogen are aimed at unravelling the mechanisms involved in partner recognition and the cross-talk used to maintain the beneficial association between the fungal antagonist and the plant. Several strategies have been used to identify the molecular factors involved in this complex tripartite interaction including genomics, proteomics and, more recently, metabolomics, in order to enhance our understanding. This review presents recent advances and findings regarding the biocontrol-resulting events that take place during the Trichoderma–plant–pathogen interaction. We focus our attention on the biological aspects of this topic, highlighting the novel findings concerning the role of Trichoderma in disease suppression. A better understanding of these factors is expected to enhance not only the rapid identification of effective strains and their applications but also indicate the potentials for improvement of natural strains of Trichoderma. 相似文献
390.
Shot holes on oriental cherry (Prunus serrulata var. spontanea) leaves were investigated to evaluate their role in the elimination of pathogens using analytical electron microscopy. Small brown spots caused by Mycosphaerella cerasella appeared on the leaf surface and developed into shot holes that were approximately 1–5 mm in diameter. Field emission scanning electron microscopy revealed clusters of fungal conidiophores and hyphal growth on the leaf surface around the shot holes. The fungal structures were mostly located within a radius of 500 μm from the shot holes and confined to the epidermal sector separated by veins. X‐ray microanalysis revealed distinct calcium ring patterns encircling the shot holes. The abscised surfaces consisted of suberized plant cells colonized with filamentous fungi and yeasts. Embedded in the mesophyll tissue, druse crystals were co‐localized with calcium and oxygen. Despite the fungal presence around the shot holes, no further expansion of the shot holes was observed on the leaf surface. These results suggest that shot holes may represent an incomplete but neutral abscission of infection loci in the presence of necrotrophic fungal pathogens. This microscopy study provides insight into the formation and roles of calcium oxalate in plants under pathological conditions. 相似文献