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21.
G. Hardarson F. A. Bliss M. R. Cigales-Rivero R. A. Henson J. A. Kipe-Nolt L. Longeri A. Manrique J. J. Peña-Cabriales P. A. A. Pereira C. A. Sanabria S. M. Tsai 《Plant and Soil》1993,152(1):59-70
Field experiments were performed in Austria, Brazil, Chile, Colombia, Guatemala, Mexico and Peru as part of an FAO/IAEA Co-ordinated Research Programme to investigate the nitrogen fixing potential of cultivars and breeding lines of common bean (Phaseolus vulgaris L.). Each experiment included approximately 20 bean genotypes which were compared using the 15N isotope dilution method. Great differences in nitrogen fixation were observed between and within experiments, with average values of 35% N derived from atmosphere (% Ndfa) and highest values of 70% Ndfa being observed. These values which were larger than had been reported previously for common bean, were observed only when environmental factors were favorable. Therefore, common bean lines are available, which can support high biological nitrogen fixation. These can be used either directly as cultivars for production or in breeding programmes to enhance nitrogen fixation in other cultivars. 相似文献
22.
A scanning electron microscope study of normal and vitrified leaves from Datura insignis plantlets cultured in vitro 总被引:5,自引:0,他引:5
Flavio Costa Miguens Ricardo Pereira Louro Raul Dodsworth Machado 《Plant Cell, Tissue and Organ Culture》1993,32(1):109-113
The surface anatomy of normal and vitreous leaves of plantlets obtained from Datura insignis Barb Rodr nodal segment cultures was compared using scanning electron microscopy. Normal and vitrified leaves are similar in several ways. They are both amphistomatic, and have similar distributions of glandular and non-glandular trichomes. Stomata have similar length, diameter and distribution in normal and vitreous plants. Immature stomata, which have closed pores, and plugged stomata, which contain an amorphous material between their guard cells, occur in both normal and vitrified leaves. Normal and vitreous leaves differ in the frequency of normal and abnormal stomata. Normal stomata have kidney-shaped guard cells and resemble closely those found in field-grown plants, whereas abnormal stomata have deformed guard cells. Normal stomata represent approximately 80% of the total number of stomata in normal leaves, but only 7% of the total number of stomata in vitreous leaves. Abnormal stomata represent 90% of the total number in vitreous leaves. The deformation of guard cells could possibly be a mechanical impediment to stomatal function. 相似文献
23.
A. El-Kharbotly C. Leonards-Schippers D. J. Huigen E. Jacobsen A. Pereira W. J. Stiekema F. Salamini C. Gebhardt 《Molecular genetics and genomics : MGG》1994,242(6):749-754
Phytophthora infestans (Mont.) de Bary is the most important fungal pathogen of the potato (Solanum tuberosum). The introduction of major genes for resistance from the wild species S. demissum into potato cultivars is the earliest example of breeding for resistance using wild germplasm in this crop. Eleven resistance alleles (R genes) are known, differing in the recognition of corresponding avirulence alleles of the fungus. The number of R loci, their positions on the genetic map and the allelic relationships between different R variants are not known, except that the R1 locus has been mapped to potato chromosome V The objective of this work was the further genetic analysis of different R alleles in potato. Tetraploid potato cultivars carrying R alleles were reduced to the diploid level by inducing haploid parthenogenetic development of 2n female gametes. Of the 157 isolated primary dihaploids, 7 set seeds and carried the resistance alleles R1, R3 and R10 either individually or in combinations. Independent segregation of the dominant R1 and R3 alleles was demonstrated in two F1 populations of crosses among a dihaploid clone carrying R1 plus R3 and susceptible pollinators. Distorted segregation in favour of susceptibility was found for the R3 allele in 15 of 18 F1 populations analysed, whereas the RI allele segregated with a 1:1 ratio as expected in five F1 populations. The mode of inheritance of the R10 allele could not be deduced as only very few F1 hybrids bearing R10 were obtained. Linkage analysis in two F1 populations between R1, R3 and RFLP markers of known position on the potato RFLP maps confirmed the position of the R1 locus on chromosome V and localized the second locus, R3, to a distal position on chromdsome XI. 相似文献
24.
Jean-Luc J. Pellegrin Eduardo Ortega-Barria Reginaldo P. Prioli Mary Buerger Richard G. Strout Joseph Alroy Miercio E. A. Pereira 《Glycoconjugate journal》1993,10(1):57-63
Sporozoites and merozoites of three species ofEimeria, E. tenella, E. maxima, andE. necatrix, that cause diarrhea in chickens worldwide, were examined for their expression of sialidase (SA) activity. The enzyme was found in three species, and the activity of merozoites was 10–20 times higher than that of sporozoites. The enzyme was resistant to degradation by proteases that are normally present in the intestine, a site inhabited by theEimeria parasites, and it was relatively resistant to heat, with optimum activity being at 40°C, which is within the range of temperature in the chicken intestine (40–43°C).E. tenella SA was immuniprecipitated by monoclonal and polyclonal antibodies raised against theTrypanosoma cruzi SA (TCSA), and enzyme activity was neutralized by these antibodies.E. tenella SA was identified by immunoblots as a doublet of molecular weight 190 000 and 180 000 using, as a probe, anti-TCSA antibodies and antibodies against a synthetic peptide (TR) derived from the long tandem repeat domain of TCSA. Binding of the monoclonal and polyclonal antibodies toE. tenella was completely blocked by TR, but not by an irrelevant peptide (BR). Therefore,E. tenella expresses a developmentally regulated SA that is structurally related to theT. cruzi counterpart. Because of the high SA activity in merozoites, and by analogy with other SA-producing microbes that inhabit mucin-rich epithelia, we suggest that theEimeria SA plays a role in desialylating intestinal mucins to reduce viscosity of the local environment and thereby facilitate parasite migration. The enzyme could also play a role in host cell-parasite interaction.Abbreviations SA
sialidase (neuraminidase)
- Neu5Ac
N-acetylneuraminic acid
- 4-MU-Neu5Ac
2-(4-methylumbelliferyl)--N-acetyl-d-neuraminic acid
- BSA
bovine serum albumin
- PBS
phosphate buffered saline
- PMSF
phenylmethylsulfonyl fluoride
- PNA
peanut agglutinin
- Ab
antibody
- TCN-2
monoclonal antibody toT. cruzi sialidase, anti-Ars, monoclonal antibody top-azophenylarsonate
- TCSA
Trypanosoma cruzi sialidase 相似文献
25.
Neuza Domingues André R. A. Marques Rita Diogo Almeida Calado Inês S. Ferreira Cristiano Ramos José Ramalho Maria I. L. Soares Telmo Pereira Luís Oliveira José R. Vicente Louise H. Wong Inês C. M. Simões Teresa M. V. D. Pinho e Melo Andrew Peden Cláudia Guimas Almeida Clare E. Futter Rosa Puertollano Winchil L. C. Vaz Otília V. Vieira 《Traffic (Copenhagen, Denmark)》2023,24(7):284-307
26.
27.
Measurements of anther (length, width, depth), pollen grain (percent fertility, polar diameter, equatorial diameter, polar diameter/equatorial diameter ratio, volume) and pistil (stigma length, style length, ovary length, total pistil length, stigma width, style width, ovary width) were taken on 12 diverse sesame (Sesamum indicum L.) genotypes on each of four collection dates in 1994. Highly significant differences among genotype means were obtained for all characters except polar diameter. Highly significant differences among environment (collection date) means were found for ten of the 15 characters measured. Highly significant genotype x environment interactions were obtained for all characters except anther length. For the anther characters measured, relatively high repeatability values were found, ranging from 99.8% for length to 87.6% for depth. For the pollen grain characters measured, the repeatability values ranged from 67.6% for percent fertility to 23.1% for polar diameter. For the pistil characters measured, the repeatability values ranged from 94.0% for style width to 49.6% for total pistil length. These results indicate that genotype and environment influence anther, pollen grain and pistil characters. Variation in some of these morphological aspects could influence the consistency and interpretation of male transmission studies on both the applied and evolutionary levels. 相似文献
28.
José A. A. Sant''Ana Pereira Arnold De Haan Andy Wessels Antoon F. M. Moorman Anthony J. Sargeant 《The Histochemical journal》1995,27(9):715-722
Summary In the present study we report a novel histochemical method which, by sequential pre-incubations in alkaline and acidic media,
selectively differentiates muscle fibres expressing myosin heavy chain IIX, on the basis of a specific profile for myofibrillar
actomyosin ATPase (mATPase) activity. The enzyme reactions were tested for specificity by means of anti-myosin heavy chain
monoclonal antibodies, which were characterized on Western blots of muscle homogenates. Enzyme histochemical reactions with
the traditional pH buffers were compared to those of the new method and, in conjunction with the immunoreactions, used to
confirm the relationship between MyHC expression and the distinct profiles for mATPase. Imrnunohistochemical reactions demonstrated
that the new method only differentiates those fibres expressing myosin heavy chain IIX. The method revealed a continuum in
which the intermediate staining intensities corresponded to hybrid fibres expressing myosin heavy chain IIX in combination
with either the IIA or IIB forms. Quantitative histochemistry and immunohistochemistry (by image analysis), used to examine
the relationship between staining intensities for mATPase and amounts of myosin heavy chain IIX expression, revealed that
the new method discriminates well between hybrid fibres expressing variable amounts of the IIX isoform (r2 = 0.93). 相似文献
29.
Dr J. O. Lopes D. V. Pereira L. A. Streher A. A. Fenalte S. H. Alves J. P. Benevenga 《Mycopathologia》1995,130(2):89-92
A case of cutaneous zygomycosis caused byAbsidia coryabifera in a leukemic patient submitted to chemotherapy is reported. The lesion was located on the little finger of the right hand and probably resulted from a latent osteomyelitis. It progressed to form extensive necrotic area. No systemic infection was detected and the lesion did not appear to be associated with any trauma. 相似文献
30.
Bernadette M. Kelly-Basetti Darren J. Cundy Suzanne M. Pereira Wolfgang H. F. Sasse G. Paul Savage Gregory W. Simpson 《Bioorganic & medicinal chemistry letters》1995,5(24):2989-2992
A series of substituted 2,2′-bipyridine derivatives was prepared using the Kröhnke reaction and alkylation of 4,4′-dimethyl-2,2′-bipyridine. These compounds were screened for fungicidal activity against 9 plant diseases. 5-Phenyl-2,2′-bipyridine exhibited strong preventative and curative fungicidal activity against wheat powdery mildew (Erisyphe graminis) and wheat leaf rust (Puccinia recondita). 相似文献