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21.
Summary The breeding system of Abelmoschus species is not well known. Although being self-compatibles allogamy reaches 63%. The aim of the study was to place four Abelmoschus species on the log P/O scale devised by Cruden (1977). On this scale P = pollen grains per anther × anthers per flower and O = ovules production. Pollens and ovules productions were therefore assessed for 68 accessions of two cultivated species, A. esculentus and A. caillei, and two wild, A. manihot and A. moschatus. Extreme log P/O values ranged from 1.69 for the variety Clemson Spineliss (A. esculentus) to 2.94 for ORS 278 (A. manihot). Averages of wild species A. moschatus (2.17) and A. manihot (2.19) indicate facultative autogamy. Averages for cultivated species A. esculentus (2.00) and A. caillei (2.05) suggest more autogamy. 相似文献
22.
Summary Flowering plants of Rosa hybrida L. cv Meirutral have been obtained either from direct regeneration of adventitious shoots on leaf and root fragments, or through organogenesis and somatic embryogenesis on calli derived from anther, ovule, petal, sepal, receptacle, leaf, stem internode, root and zygotic embryo tissues. The calli derived from floral parts exhibited rhizogenesis. In this case direct induction of adventitious shoots from selected roots had to be performed in order to generate plants. A histological study of the morphogenetic calli was carried out. The plants regenerated directly and those regenerated from calli of leaf, stem internode, root and zygotic embryo tissues, together with reference plants propagated by cuttings, were compared on a phenotypic basis by taking into account petal number, form and colour, and plant growth habit. From these observations, it can be concluded that directly regenerated plants are as stable as reference plants while plants regenerated from callus are unstable, especially those derived from zygotic embryo tissues.Abbreviations BAP
6-benzylaminopurine
- 2,4-D
2,4-Dichlorophenoxyacetic acid
- GA3
gibberellic acid
- IAA
3-indole-acetic acid
- MS
Murashige and Skoog
- NAA
1-naphthalene acetic acid 相似文献
23.
Simon Bilodeau-Gauthier Daniel Houle Christian GagnonBenoît Côté Christian Messier 《Forest Ecology and Management》2011,261(1):95-104
Partitioning of elements in tree xylem is being increasingly studied, as it suggests that elements are potentially mobile within the xylem long after their uptake. A recent study revealed that only the most mobile xylem fraction (water-soluble) of base cations (calcium [Ca], magnesium [Mg], and potassium [K]) increased at higher soil acidity, while the two mobile fractions (water- and acid-soluble) of acidic metals—potentially phytotoxic aluminium (Al), cadmium (Cd) and manganese (Mn)—were significantly enhanced on very acid soils. The current paper presents an investigation of soil-wood chemistry relationships with basal area tree growth. It was hypothesized that the growth of sugar maple would be reduced by low base cation and high acidic metal concentrations in the xylem mobile fractions. Sugar maple trees (n = 55) from six watersheds in southern Quebec, Canada were analysed by sequential chemical extractions for the water-soluble, acid-soluble and residual fractions of base cations (Ca, K, Mg) and acidic metals (Al, Cd, Mn) in xylem. Generally, tree growth was positively correlated to concentrations of base cations in wood (ρ = 0.27-0.50) and soil (ρ = 0.41-0.67), and negatively correlated to concentrations of acidic metals in wood (ρ = −0.33 to −0.52) and soil (ρ = −0.67). However, these relations differed depending on the element fraction considered. Water- and acid-soluble xylem concentrations of base cations and Al were among the best predictors of growth trends (R2 = 0.46-0.51). The relationship between acidic metals and tree growth is further discussed. 相似文献
24.
Colbourne JK Pfrender ME Gilbert D Thomas WK Tucker A Oakley TH Tokishita S Aerts A Arnold GJ Basu MK Bauer DJ Cáceres CE Carmel L Casola C Choi JH Detter JC Dong Q Dusheyko S Eads BD Fröhlich T Geiler-Samerotte KA Gerlach D Hatcher P Jogdeo S Krijgsveld J Kriventseva EV Kültz D Laforsch C Lindquist E Lopez J Manak JR Muller J Pangilinan J Patwardhan RP Pitluck S Pritham EJ Rechtsteiner A Rho M Rogozin IB Sakarya O Salamov A Schaack S Shapiro H Shiga Y Skalitzky C Smith Z Souvorov A Sung W 《Science (New York, N.Y.)》2011,331(6017):555-561
We describe the draft genome of the microcrustacean Daphnia pulex, which is only 200 megabases and contains at least 30,907 genes. The high gene count is a consequence of an elevated rate of gene duplication resulting in tandem gene clusters. More than a third of Daphnia's genes have no detectable homologs in any other available proteome, and the most amplified gene families are specific to the Daphnia lineage. The coexpansion of gene families interacting within metabolic pathways suggests that the maintenance of duplicated genes is not random, and the analysis of gene expression under different environmental conditions reveals that numerous paralogs acquire divergent expression patterns soon after duplication. Daphnia-specific genes, including many additional loci within sequenced regions that are otherwise devoid of annotations, are the most responsive genes to ecological challenges. 相似文献
25.
Brunette I Rosolen SG Carrier M Abderrahman M Nada O Germain L Proulx S 《Veterinary ophthalmology》2011,14(6):365-377
Purpose The goal of this study was to report on the advantages and limitations of the pig and feline models for experimental in vivo corneal transplantation. Methods Ten healthy domestic pigs and ten healthy cats were used. Full thickness penetrating keratoplasty was performed using autologous (eight cases), allogeneic (seven cases) or human xenogeneic (three cases) tissue. In two other cases, the inflammatory response to partial thickness trephination (without transplantation) was evaluated. Eyes were assessed daily before and after surgery by slit‐lamp, pachymetry, and tonometry. A transparency score ranging from 0 (opaque graft) to 4 (clear graft) was used, based on the slit‐lamp examination. Optical coherence tomography, histology, and electron microscopy were performed postmortem. Results In the pig, the mean (±SD) transparency score for the eight full thickness grafts was 0.88 ± 0.99, ranging from 0 to 3. In the feline model, the mean transparency score for the seven uncomplicated grafts was 3.93 ± 0.19, ranging from 3.5 to 4. Both negative controls without endothelium remained opaque at all time. Intraoperative tendency for iris incarceration into the wound, rapid corneal swelling, suture cheese wiring, and postoperative intraocular inflammation were the main factors jeopardizing the functional success of the corneal transplant in the pig model. Conclusion Suboptimal functional results were obtained after full thickness corneal transplantation in the pig model, while in the feline model, the same protocol yielded uneventful surgeries and clear transplants, with functional results similar to those achieved in human subjects. 相似文献
26.
Regional Sediment Deficits in the Dutch Lowlands: Implications for Long-Term Land-Use Options (8 pp)
Michiel J. van der Meulen Ad J. F. van der Spek Ger de Lange Stephan H. L. L. Gruijters Serge F. van Gessel Buu-Long Nguyen Denise Maljers Jeroen Schokker Jan P. M. Mulder Rob A. A. van der Krogt 《Journal of Soils and Sediments》2007,7(1):9-16
Background, Aim and Scope
Coastal and river plains are the surfaces of depositional systems, to which sediment input is a parameter of key-importance.
Their habitation and economic development usually requires protection with dikes, quays, etc., which are effective in retaining
floods but have the side effect of retarding sedimentation in their hinterlands. The flood-protected Dutch lowlands (so-called
dike-ring areas) have been sediment-starved for up to about a millennium. In addition to this, peat decomposition and soil
compaction, brought about by land drainage, have caused significant land subsidence. Sediment deficiency, defined as the combined
effect of sediment-starvation and drainage-induced volume losses, has already been substantial in this area, and it is expected
to become urgent in view of the forecasted effects of climate change (sea-level rise, intensified precipitation and run-off).
We therefore explore this deficiency, compare it with natural (Holocene) and current human sediment inputs, and discuss it
in terms of long-term land-use options.
Materials and Methods:
We use available 3D geological models to define natural sediment inputs to our study area. Recent progress in large-scale
modelling of peat oxidation and compaction enables us to address volume loss associated with these processes. Human sediment
inputs are based on published minerals statistics. All results are given as first-order approximations.
Results:
The current sediment deficit in the diked lowlands of the Netherlands is estimated at 136 ± 67 million m3/a. About 85% of
this volume is the hypothetical amount of sediment required to keep up with sea-level rise, and 15% is the effect of land
drainage (peat decomposition and compaction). The average Holocene sediment input to our study area (based on a total of 145
km3) is ~14 million m3/a, and the maximum (millennium-averaged) input ~26 million m3/a. Historical sediment deficiency has
resulted in an unused sediment accommodation space of about 13.3 km3. Net human input of sediment material currently amounts
to ~23 million m3/a.
Discussion:
As sedimentary processes in the Dutch lowlands have been retarded, the depositional system's natural resilience to sea-level
rise is low, and all that is left to cope is human countermeasure. Preserving some sort of status quo with water management
solutions may reach its limits in the foreseeable future. The most viable long-term solutions therefore seem a combination
of allowing for more water in open country (anything from flood-buffer zones to open water) and raising lands that are to
be built up (enabling their lasting protection). As to the latter, doubling or tripling the use of filling sand in a planned
and sustained effort may resolve up to one half of the Dutch sediment deficiency problems in about a century.
Conclusions:
Conclusions, Recommendations and Perspectives. We conclude that sediment deficiency – past, present and future – challenges
the sustainable habitation of the Dutch lowlands. In order to explore possible solutions, we recommend the development of
long-term scenarios for the changing lowland physiography, that include the effects of Global Change, compensation measures,
costs and benefits, and the implications for long-term land-use options.
Recommendations and Perspectives:
- 相似文献
27.
Lestienne I Caporiccio B Besançon P Rochette I Trèche S 《Journal of agricultural and food chemistry》2005,53(21):8342-8348
In vitro digestions were performed on pearl millet flours with decreased phytate contents and on two dephytinized or nondephytinized pearl millet grain fractions, a decorticated fraction, and a bran fraction with low and high fiber and tannin contents, respectively. Insoluble residues of these digestions were then incubated with buffer or enzymatic solutions (xylanases and/or phytases), and the quantities of indigestible iron and zinc released by these different treatments were determined. In decorticated pearl millet grain, iron was chelated by phytates and by insoluble fibers, whereas zinc was almost exclusively chelated by phytates. In the bran of pearl millet grain, a high proportion of iron was chelated by iron-binding phenolic compounds, while the rest of iron as well as the majority of zinc were chelated in complexes between phytates and fibers. The low effect of phytase action on iron and zinc solubility of bran of pearl millet grain shows that, in the case of high fiber and tannin contents, the chelating effect of these compounds was higher than that of phytates. 相似文献
28.
Wheatley Brian Paradis Sylvain Lassonde Maryse Giguere Marie-France Tanguay Serge 《Water, air, and soil pollution》1997,97(1-2):63-73
Health Canada has been collecting data on Inuit and First Nations' methylmercury (MeHg) levels for 25 years. A national overview has been completed and more focussed analyses have now been initiated. This paper deals with two interdependent analytical components: 1) a longitudinal overview of the two most extensively sampled communities in Canada: Grassy Narrows and Whitedog, the residents of which were exposed to ‘point source’ mercury pollution in the 1970's; 2) fetal and post-natal exposure to mercury in these two communities including an outline of the First Nation MeHg child development pilot project in the two communities. A retrospective analysis of Grassy Narrows and Whitedog shows a decreasing MeHg trend in both communities. In Grassy Narrows the average individual annual peak methylmercury level in blood has decreased significantly, from 23.80 ppb (range 1.50–322.90) in 1976 to 7.5 ppb (1.7–46.7) in 1995 (r=-0.65, p<0.001). In Whitedog the average peak has also decreased significantly, from 12.87 ppb (1.50–172.00) in 1976 to 6.1 ppb (1.7–33.3) in 1995 (r=-0.59, p<0.005). However, behind these positive trends is the reality of two communities still suffering the effects of disrupted lifestyles and socio-cultural damage. A number of cord blood samples, maternal blood samples, and samples from women of child-bearing age from these communities have been in the “risk” group (according to the 1990 WHO guidelines). We are therefore now assessing the long term effects of fetal exposure in the communities. Standard clinical examinations in the past failed to prove abnormalities attributable to methylmercury but did not include subtle neuropsychological development tests. Many of the fetally exposed children are now in secondary school. Therefore, we have initiated a pilot project to assess long term effects of methylmercury exposure on the neuropsychological development of these children whose fetal exposure we know. The pilot child development project which was initiated in 1995 in Grassy Narrows and Whitedog, with community support, includes four main components: i) a school records review, looking at attendance, marks, and atypical behaviour; ii) teachers' questionnaires, targeting child behaviour; iii) an in-depth neuropsychological test battery focussing on subtle factors, such as memory, attention, executive functions, perceptual functions and sensory / motor development; and iv) hair sampling, providing current MeHg levels to correlate with results from the previous sampling and findings from the first three components. An overview of progress is given. 相似文献
29.
Development of an experimental model allowing discrimination between virulent and avirulent isolates of Serpulina (Treponema) hyodysenteriae. 下载免费PDF全文
Variation in virulence among different strains of Serpulina hyodysenteriae was studied by oral inoculation of specific pathogen free piglets and CD-1 mice. Piglets infected with serotype 2 reference strain B204 and an untypable field strain LHV-90-9-I had severe diarrhea tainted intermittently with mucus and fresh blood. The piglets inoculated with B169, B8044, B6933, and ACK300-8 reference strains representing serotypes 3, 5, 6, and 7 respectively developed moderate diarrhea. However, reference strains B234 and A-1 of serotypes 1 and 4, respectively, failed to cause any diarrhea. None of the S. hyodysenteriae strains caused diarrhea in mice. The results indicate a great variation in virulence among strains of different serotypes of S. hyodysenteriae. Mice were less susceptible to infection with S. hyodysenteriae. 相似文献
30.
Summary The use of Cruden's index (1977), for studying okra sexual reproductive allocations, indicates a facultative autogamy mode. The purpose of the research described is to obtain more accurate information on the self-fertilization process. For this, self-pollen grain germination was stopped at different times of the day. Twelve varieties of Abelmoschus esculentus were used. Self-fertilization kinetics—expressed by the setting rate—displayed an increase between 7.00 to 16.00 hr. Study of obtained progenies, by stimulated allogamy, confirmed the process and showed that allo-pollen grains deposited on a stigma after midday had only a very little chance of contributing to fertilization. As a result, the polymorphism of the flower structure and particularly the distance between anther and stigmas, insect types and movement habits play major roles in governing okra allogamy. We also show that self-fertilization kinetics can be used to improve controlled hybrid production. 相似文献