Acidovorax avenae subsp.citrulli transmitted by solanaceous seeds     

I. Assouline  Hillela Milshtein  M. Mizrahi  Edna Levy  I. S. Ben-Ze’ev 《Phytoparasitica》1997,25(2):117-118

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Effect of Stocking Density on Growth,Survival, and Condition of the Mexican Cichlid Cichlasoma beani     

Edgar A. Aragon‐Flores  Edna F. Valdez‐Hernandez  Leonardo Martinez‐Cardenas  Maria R. Castaeda‐Chavez  Alfonso A. Gonzales‐Diaz  Miriam Soria‐Barreto  Javier M. J. Ruiz‐Velazco  Emilio Pea‐Messina 《Journal of the World Aquaculture Society》2014,45(4):447-453

The Mexican cichlid Cichlasoma beani is currently exploited regionally as food and can be commercialized in the aquarium trade. Natural populations of C. beani may already be negatively affected by anthropogenic alteration of the areas in which it is distributed. The aim of the present study was to examine the effect on growth, survival, and condition of C. beani cultured in three stocking densities: three (D3), six (D6), and nine (D9) fish per each 40 L tank. At the end of a 6‐wk trial the fish cultured in D3 were longer, heavier, and grew faster than the rest of the treatments but their survival was the lowest compared to D6 and D9. The mortalities were caused by a strong aggressive behavior in D3.  相似文献   

Parasitism of <Emphasis Type="Italic">Trichoderma</Emphasis> on <Emphasis Type="Italic">Meloidogyne javanica</Emphasis> and role of the gelatinous matrix     

Edna Sharon  Ilan Chet  Ada Viterbo  Meira Bar-Eyal  Harel Nagan  Gary J. Samuels  Yitzhak Spiegel 《European journal of plant pathology / European Foundation for Plant Pathology》2007,118(3):247-258

Trichoderma (T. asperellum-203, 44 and GH11; T. atroviride-IMI 206040 and T. harzianum-248) parasitism on Meloidogyne javanica life stages was examined in vitro. Conidium attachment and parasitism differed beween the fungi. Egg masses, their derived eggs and second-stage juveniles (J2) were parasitized by Trichoderma asperellum-203, 44, and T. atroviride following conidium attachment. Trichoderma asperellum-GH11 attached to the nematodes but exhibited reduced penetration, whereas growth of T. harzianum-248 attached to egg masses was inhibited. Only a few conidia of the different fungi were attached to eggs and J2s without gelatinous matrix; the eggs were penetrated and parasitized by few hyphae, while J2s were rarely parasitized by the fungi. The gelatinous matrix specifically induced J2 immobilization by T. asperellum-203, 44 and T. atroviride metabolites that immobilized the J2s. A constitutive-GFP-expressing T. asperellum-203 construct was used to visualize fungal penetration of the nematodes. Scanning electron microscopy revealed the formation of coiling and appressorium-like structures upon attachment and parasitism by T. asperellum-203 and T. atroviride. Gelatinous matrix agglutinated T. asperellum-203 and T. atroviride conidia, a process that was Ca²⁺-dependent. Conidium agglutination was inhibited by carbohydrates, including fucose, as was conidium attachment to the nematodes. All but T. harzianum could grow on the gelatinous matrix, which enhanced conidium germination. A biomimetic system based on gelatinous-matrix-coated nylon fibers demonstrated the role of the matrix in parasitism: T. asperellum-203 and T. atroviride conidia attached specifically to the gelatinous-matrix-coated fibers and parasitic growth patterns, such as coiling, branching and appressoria-like structures, were induced in both fungi, similarly to those observed during nematode parasitism. All Trichoderma isolates exhibited nematode biocontrol activity in pot experiments with tomato plants. Parasitic interactions were demonstrated in planta: females and egg masses dissected from tomato roots grown in T. asperellum-203-treated soil were examined and found to be parasitized by the fungus. This study demonstrates biocontrol activities of Trichoderma isolates and their parasitic capabilities on M. javanica, elucidating the importance of the gelatinous matrix in the fungal parasitism.  相似文献   

Preparation and comparison of biological properties of recombinant carp (Cyprinus carpio) growth hormone and its Cys-123 to Ala mutant     

Mira Fine  Edna Sakal  Dorit Vashdi  Nava Chapnik-Cohen  Violet Daniel  Avigdor Levanon  Orli Lipshitz  Arieh Gertler 《Fish physiology and biochemistry》1993,11(1-6):353-361

Carp growth hormone (cGH) cDNA, in which Cys-123 was mutated to Ala, was prepared, transferred to the expression vector, expressed in Escherichia coli and the mutant was purified to homogeneity. The mutation only slightly improved yield of the monomeric fraction, indicating that Cys-123 is not involved in improper refolding. As compared to cGH, the mutant (cGH-C123A) exhibited lower binding affinity toward homologous liver receptors and lower bioactivity in a 3T3-F442A preadipocyte bioassay despite the fact that both hormones exhibited almost identical cross-reactivity with anti-cGH antibodies. These results, along with those of a structural comparison to hGH, suggest that Cys-123 is located in the hydrophobic core of the hormone, and is most likely affecting the conformation of the binding site. Dimeric forms of the hormone and its mutant were less active than their respective monomers. Homologous binding experiments using a carp liver microsomal fraction revealed a single receptor population with Kd = 0.77 nM and B_max = 241 fmol/mg microsomal protein.

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Résumé Un ADN complémentaire (cDNA) de l'hormone de croissance de carpe (cGH), dans lequel l'acide aminé Cys-123 a été muté en Ala, a été préparé, inséré dans un vecteur d'expression, et exprimé dans Escherichia coli. Le mutant a ensuite été purifié jusqu'à homogénéité. La mutation améliore seulement faiblement la production de la fraction monomérique, indiquant que le Cys-123 n'est pas impliqué dans un repliement erroné. Comparé à la cGH, sa forme mutée (cGH-C123A) montre une plus faible affinité de liaison vis à vis de récepteurs hépatiques homologues, et une plus faible activité biologique dans un test réalisé sur des préadipocytes 3T3-F442A; cela en dépit du fait que les deux hormones présentent des réactions croisées presque identiques avec un anticorps anti-cGH polyclonale. Ces résultats, associés à une comparaison à la structure de l'hGH, suggèrent que le Cys-123 est localisé dans la partie hydrophobique de l'hormone, et affecte, le plus vraisemblablement, la conformation du site de liaison. Les formes dimériques de l'hormone et de sa forme mutée sont moins actives que leurs monomères respectifs. Les études de liaison homologue, réalisées avec des fractions microsomales de foie, révèlent une population unique de récepteurs de Kd = 0,77 nM et de B_max = 241 fmol/mg de proteine microsomale.

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Chiral amplification of oligopeptides in two-dimensional crystalline self-assemblies on water     

Zepik H  Shavit E  Tang M  Jensen TR  Kjaer K  Bolbach G  Leiserowitz L  Weissbuch I  Lahav M 《Science (New York, N.Y.)》2002,295(5558):1266-1269

Differences in the two-dimensional packing arrangements of racemic and enantiomeric crystalline self-assemblies on the water surface of amphiphilic activated analogs of lysine and glutamic acid have been used to prepare oligopeptides of homochiral sequence and oligopeptides of single handedness from chiral nonracemic mixtures. The crystalline structures on the water surface were determined by grazing incidence x-ray diffraction and the diastereomeric composition of the oligopeptides by matrix-assisted laser desorption time-of-flight mass spectrometry with enantio-labeling. These results suggest that reactivity of ordered clusters at interfaces might have played a role in the generation of early homochiral biopolymers.  相似文献   

Communication. Social values and the governance of science     

Gaskell G  Einsiedel E  Hallman W  Priest SH  Jackson J  Olsthoorn J 《Science (New York, N.Y.)》2005,310(5756):1908-1909

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Low-oxygen treatment for inhibition of decay and ripening in organic bananas     

Edna Pesis  Azica Cope  Rosa Ben-Arie  Oleg Feygenberg  Yair Aharoni 《The Journal of Horticultural Science and Biotechnology》2013,88(5):648-652

Summary

Application of a low-O₂ atmosphere for several days prior to storing organic banana clusters was effective in preventing decay development on the crown cuts, and in delaying ripening. Preclimacteric banana clusters (Musa spp. AAA group cultivar Ziv) were treated with a low-oxygen atmosphere (2%) at 208C for 24, 48 and 72.h immediately after harvest. After removal from low-O₂ stress, the bananas were stored at 128C for 21.d, and were then treated with ethylene at 188C for 24.h and transferred to shelf life at 208C for an additional 4.d. The low-O₂ treatments were compared with the commercial treatment of dipping the crown cuts in 0.2% thiabendazole (TBZ). The low-O₂ stress for 48 or 72.h was effective in preventing decay after shelf life, but less so than the TBZ treatment. Low-O₂ for 24.h was not effective enough, and the 72.h treatment markedly impaired colour development after ripening with ethylene. The 48.h low-O₂ treatment which resulted in the best decay prevention also retarded ripening processes (colour, ®rmness, respiration and ethylene production) and reduced chilling injury symptoms, without impairing the taste. The level of reducing sugars in the 48.h-treated fruit was similar to that in the control fruit after ripening and shelf life. The endogenous levels of acetaldehyde (AA) and ethanol produced by the treated fruit were lower than those in the control fruit during shelf life. It seems that there is a high potential for this physical treatment of low-O₂ stress to replace chemical treatments, as means of maintaining the quality of organic bananas.  相似文献   

Nematicidal Activity of Chrysanthemum coronarium     

Meira Bar-Eyal  Edna Sharon  Yitzhak Spiegel 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(4):427-433

Organic amendments and green manure are potential alternatives to the harmful chemical control means currently used against plant-parasitic nematodes. In this work, Chrysanthemum coronarium was applied to the soil as a green manure to control the root-knot nematodes Meloidogyne incognita and M. javanica. Chrysanthemum coronarium significantly reduced nematode infection of tomato roots and improved plant-top fresh weight, both in the greenhouse and in microplots. Other green manures, derived from Anthemis pseudocotula, wild chickpea (Cicer pinnatifidum), Geranium spp. and wheat, were not as effective as C. coronarium. Chrysanthemum coronarium, retained its nematicidal activity even when applied as a dried material. Only mature C. coronarium plants, in their flowering stage, exhibited nematode control activity, but the green plant parts were more effective than the flowers. An aqueous extract of C. coronarium exhibited in vitro, nematostatic activity towards M. incognita and M. javanica second-stage juveniles and inhibited their hatching from eggs and egg-masses; its nematostatic activity was expressed also against other phytonematode species such as Heterodera avenae and Pratylenchus mediterraneus, but did not affect the beneficial entomopathogenic nematode Steinernema feltiae.  相似文献   

Improved attachment and parasitism of <Emphasis Type="Italic">Trichoderma</Emphasis> on <Emphasis Type="Italic">Meloidogyne javanica</Emphasis> in vitro     

Edna Sharon  Ilan Chet  Yitzhak Spiegel 《European journal of plant pathology / European Foundation for Plant Pathology》2009,123(3):291-299

Monoclonal and polyclonal antibodies that bind to eggs and/or second-stage juveniles of the nematode Meloidogyne javanica were tested for their effects on the parasitic interactions between this nematode and the fungus Trichoderma. Parasitism of Trichoderma asperellum-203 and Trichoderma atroviride on nematode egg masses, eggs and juveniles was enhanced when antibodies were incorporated into in vitro parasitism bioassays. Parasitism on separated eggs (without gelatinous matrix) and their hatched juveniles was also improved, compared to controls without antibodies that did not attach fungal conidia. Improved parasitism could be due to bilateral binding of the antibodies to the nematodes and conidia, enabling better conidial attachment to the nematodes. Enhanced germination of antibody-bound conidia further improved parasitism. Differences were observed among antibodies in their effects on fungal parasitism and their interaction with Trichoderma species. We focused mainly on the egg- and juvenile-binding monoclonal antibody MISC that exhibited a stronger reaction with T. asperellum-203 than with T. atroviride. Pretreatment of this antibody with fucose inhibited its binding to nematodes and conidial attachment to nematodes, as well as conidial agglutination in the presence of the antibody. Antibody binding to juveniles affected their movement and viability, especially gelatinous matrix-originated juveniles. The fucose-specific lectin Ulex europaeus-I enhanced conidial attachment to nematode life-stages, and conidial agglutination occurred in its presence. These phenomena were inhibited by preincubating lectin with fucose. Our results suggest that carbohydrate residues, such as fucose, on the surface of the nematode and fungal conidia are involved in the antibody- and lectin-mediated improved parasitism.  相似文献   

Genetic analysis of early-maturing maize (Zea Mays L.) inbred lines under stress and nonstress conditions     

Edna K. Mageto  Kiarie Njoroge  Richard Nyankanga 《Journal of Crop Improvement》2017,31(4):560-588

Early-maturing maize (Zea Mays L.) germplasm developed from diverse sources has the potential for use in developing maize hybrids suitable for increasing maize production in the dry ecologies of eastern Africa. A diallel study was conducted to estimate general combining ability (GCA) of 12 early-maturing maize inbred lines, identify potential single-cross hybrids for use as parents, assess genetic diversity among the inbred lines, and relate genetic distance to specific combining ability (SCA) and hybrid performance. Sixty-six F₁ diallel hybrids were evaluated under optimal and drought stress conditions at four locations in Kenya and Uganda. The parental inbred lines were genotyped using 94 single nucleotide polymorphism (SNP) markers. Additive gene action was more important than nonadditive gene action for inheritance of grain yield (GY) under optimal conditions. However, nonadditive gene effects were more important in the inheritance of GY under drought and across all environments. Inbred lines CKL0722, VL058014, and CZL0724 were among the best with positive GCA effects for GY across both optimal and drought stress conditions. The correlation between SCA and both genetic distance and F₁ GY was significant under both drought stress and across all environments. Inbred lines with desirable GCA effects for GY and other agronomic traits and hybrids with good performance under both optimal and drought stress conditions are potential parents for development of various types of high-yielding, stress-tolerant, and early-maturing hybrids.  相似文献