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1.
Van Balen  F. 《ESHRE Monographs》2008,2008(1):25-28
1 Correspondence address. Nieuwe Prinsengracht 130, Gebouw G, 1018 VZ Amsterdam, The Netherlands. E-mail: f.vanbalen{at}uva.nl/vabalen{at}hotmail.com Childlessness is analysed on the individual, the national andthe international level. On the individual level five categoriesof consequences are described: grief and sadness; social isolationand stigma; restricted rights; religious effects and economicaspects. The first category concerns individual feelings andthe others are socio-cultural effects in broad-sense. In developingcountries childlessness has consequences on individual and socio-culturallevel. In the West consequences are mostly restricted to individualfeelings. In poor-resource areas there are limited possibilitiesfor modern biomedical treatment. Traditional medicine, withits easy access and cultural acceptation, is a serious ‘competitor’.On the national level there are few incentives and possibilitiesfor development of adequate infertility treatment. Though localand national authorities might be sensitive to the problem,allocation of funds is mostly determined by international agencies,which consider other issues more important. On the internationallevel Western perceptions about the urgency of health issuesare still dominant. In the Western world there is little interestand understanding in the problem of ‘barrenness amongplenty’ because a focus on population growth reductionand on other problems. Also, the perception of childlessnessas an individual problem, makes it difficult to change thisattitude. Possibilities for change are discussed.  相似文献   

2.
1 Correspondence address. E-mail: akandewole{at}yahoo.com Infertility in developing countries is pervasive and a seriousconcern. In addition to the personal grief and suffering itcauses, the inability to have children especially in poor communitiescan create broader problems, particularly for the woman. Infertilityservices in developing countries span the spectrum from preventionto treatment. From a societal and public health standpoint,prevention is cost–effective and is considered by manygovernments and public health care providers to be a priorityfor service delivery. While prevention remains paramount, takenalone it ignores the plight of infertile couples, includingthose with non-infectious causes of infertility. Two key argumentsare frequently used to challenge the development of new reproductivetechnologies in developing countries: overpopulation and limitedresources. Evidence supports the conclusion that there is acompelling need for infertility treatment beyond prevention.In many instances, assisted reproductive technologies (ART)are the last hope or the only means to achieve a child for couples.In an effort to make much needed ART to developing countriesaccessible and affordable, developing countries should lookto public–private partnerships. Governments have a responsibilityto ensure safe and effective services including the controlof standards for clinical procedures and the regulation of professionalpractice.  相似文献   

3.
The effects of exposure of up to 2 h with sulphur dioxide ona range of plant species was observed by measuring changes inthe rate of net photosynthesis under closely controlled environmentalconditions. Ryegrass, Lolium perenne ‘S23’ was thespecies most sensitive to SO2; significant inhibition was detectedat 200 nl l–1. Fumigations at 300 nl l–1 also inhibitedphotosynthesis in field bean (Vicia faba cv. ‘Three FoldWhite’ and ‘Blaze’) and in barley (Hordeumvulgare cv. ‘Sonja’). No effect was detected inwheat (Triticum aestivum cv. ‘Virtue’) at concentrationsup to 600 nl l–1 SO2, or in oil-seed rape (Brassica napuscv. ‘Rafal’) except at 800 nl l–1 SO2). Recoverycommenced immediately after the fumigation was terminated andwas complete within 2 h when inhibition had not exceeded 20%during the SO2 treatment. Key words: Sulphur dioxide, short-term fumigation, photosynthesis  相似文献   

4.
ERRATA     
Effects of coupled solute and water flow in plant roots withspecial reference to Brouwer's experiment. Edwin L. Fiscus. p. 71 Abstract: Line 3 delete ‘interval’ insert‘internal’. p. 73 Materials and Methods: line 6: delete ‘diversion’ insert ‘division’ line 9 equation should read Jv=Lp PRT(C0C1). 74 Last line of figure legend: 10–1 should read 10–11. 75 Line 11: delete ‘seems’ insert ‘seem’. le 1 column heading—106 should read 1011. 77 delete ‘...membrane in series of...’ insert ‘membranein series or...’ Delete final paragraph.  相似文献   

5.
Valentincic  Tine 《Chemical senses》1991,16(3):251-266
Feeding behavior of the brittle star Ophiura ophiura includesorienting posture, orienting movements, arm ‘walking’,changing the direction of ‘walking’ arm coilingand ingestion. All sequential behavior patterns were releasedor enhanced by single low-molecular-weight compounds. Stimuliwhich released ‘walking’ behavior at high concentrations(10–4 M) in all the test animals are listed in decreasingorder of sensitivity: sarcosine, glycine, urea, L-valine, L-leucine,L-methionine, L-homocysteine, L-norvaline, L-norleucine, L-threonine,L-serine, S-methyl-L-cysteine, L-proline. Threshold values forsingle amino acids were as much as 100 times different in differentindividuals and ranged from 3 x 10–9 to 3 x 10–7M for the most effective stimulus, sarcosine, and from 10–6to 10–4 M for proline. Above 10–5 M, only L-prolineregularly released a second behavior pattern, the arm coilingresponse, which temporarily inhibited the ‘walking’behavior. Behavioral thresholds for the ‘walking’behavior for L(+)-lactate and L-alanine were higher than thosefor the orienting movements. Thyoglycolic acid and ß-alaninereleased tube feet walking, which is not part of the feedingbehavior. Structure—activity comparisons were studied at estimated10–5 M concentrations. Gycline, sarcosine, L-valine, L-norvaline,L-leucine, L-isoleucine, DL-norleucine and DL-homocysteine releasedarm ‘walking’ behavior in more than 75% of all thetests. With the exceptions of S-methyl-and S-ethyl-cysteine,and glycine methylester, derivatives of amino acids were noteffective behavioral stimuli in Ophiura ophiura. L-Isomers ofvaline and leucine regularly stimulated the ‘walking’behavior while their D-isomers were effective in some testsand ineffective in others. Acetylcholine iodide, acetyl-ß-methylcholine chloride and choline phosphate chloride regularly released‘walking’ behavior at concentrations above 10–5M.  相似文献   

6.
HARVEY  D. M.; GOODWIN  J. 《Annals of botany》1978,42(5):1091-1998
The effect of the ‘leafless’ mutation (in whichtendrils replace leaflets and the stipules are reduced to avestigial form) upon foliage area, photosynthetic net CO2 uptakepotential, dry matter production and seed yield in Pisum sativumwas studied by comparing two near-isogenic lines of genotypeafafstst and ++++. The mutation is of potential agronomic valuein that it offers improved lodging resistance, crop drying andharvester throughput. In the conventional phenotype the total foliage area of themain axis attained a plateau (456 cm2) at day 56 from seedlingemergence, whereas corresponding values for the ‘leafless’mutant showed a total area of 208 cm2 at day 68 with no indicationof a plateau. The agronomic consequence of this is discussed.During the vegetative phase of the plant the maximum CO2 uptakepotential in the fully expanded conventional leaf was 8·5mg CO2 leaf–1 h–1 and in the ‘leafless’mutant this value was 7·0 mg CO2 leaf–1 h–1.For most ‘leaves’ of the latter phenotype this valuewas between 30 and 60 per cent less than for their conventionalcounterpart. There was a consistently higher photosyntheticpotential per unit area in tendrils of the ‘leafless’mutant than in leaflets of the conventional phenotype. The respectivemean specific values for the two phenotypes were 53 and 37 mgCO2 dm–2 h–1. The problem of obtaining a meaningfulsurface area value for tendrils is discussed and the cylindricalnature of tendrils is taken into account. The ‘leafless’ mutant consistently accumulated 50per cent less dry matter than did conventional plants in theperiod from seedling emergence to anthesis and yield of maturedry seed per plant showed a reduction of 50 per cent both inseed number and total seed weight. The implications for future breeding and selection programmesaimed at haulm reduction are discussed in relation to evaluatingthe ability of the background genotype to produce adequate tendrilsin the presence of afafstst. Triticum aestivum, wheat, callus culture, organogenesis  相似文献   

7.
Pattern of Respiration of a Perennial Ryegrass Crop in the Field   总被引:3,自引:0,他引:3  
‘Dark’ respiratory losses of CO2 were measured ona one year old sward of S24 perennial ryegrass (Lolium perenneL.) at intervals during a 74 day reproductive growth period,between April and June, and a 21 day vegetative growth period,in July and August. Part of the sward was shaded for one weekbefore measure ments commenced. Measurements of ‘dark’respiration continued for 46 hand it was possible to distinguishtwo components which are designated ‘maintenance’and ‘synthetic’ ‘Maintenance’ respiration was taken to be the meanrate of CO2 efflux after 40–46 h darkness. When calculatedon a plant d. wt basis at 15°C it ranged between 6 to 32mgCO2 g-1 day-1 during reproductive growth and 10–14 mgCO2 g-1 day-1 during vegetative growth. During reproductivegrowth, sward protein content ranged between 7–23 percent and when maintenance respiration was recalculated on thebasis of protein content it changed relatively little throughoutthe growth period (90–140 mg CO2 g pro tein-1 day-1);the value for vegetative growth ranged between 70–100mgCO2 g protein-day-1. Total ‘synthetic’ CO2 flux was determined duringreproductive growth and a rate of ‘synthetic’ CO2flux was determined during both reproductive and vegetativegrowth. Between 15 and 35 per cent of the CO2 fixed in the previousphotoperiod was lost in ‘synthetic’ respirationof above-ground material in reproductive swards. Previous shadingincreased the proportion of ‘synthetic’ CO2 lossfrom above ground. The rate of ‘synthetic’ CO2 outputduring the first hours of darkness increased with amount ofCO2 fixed in the previous photoperiod, although it was not proportionalto it. There is some evidence that assimilate is ‘carried-over’from one photoperiod to the next.  相似文献   

8.
Marked changes in the activity of the ‘de novo’and ‘salvage’ pathways of pyrimidine biosynthesisduring growth of Vinca rosea cells in a batch suspension culturewere observed. The activity of these pathways was investigated by determiningthe contribution of 14C of [2-14Cluracil, 12-14Cluridine. and[6-14Clorotate to the cell constituents and by measuring theactivity of the several enzymes of these pathways. During the lag phase of the culture, ‘uracil-’ and‘uridine-salvage’ pathways made the predominantcontribution to nucleotide biosynthesis, but, following theinitiation of cell division, the ‘de novo’ pathwayfor nucleotide biosynthesis operated appreciably. These results suggest that nucleotide synthesis during cellgrowth in a suspension culture can be divided into two stages:a ‘turnover stage’, during the lag phase of cellgrowth, and a ‘true biosynthetic stage’, which isinitiated in the cell division phase.  相似文献   

9.
Some charophyte species, like some other freshwater plants,have been shown to take up for photosynthetic fixation. Such plants show localized deposits of CaCO3 associatedwith localized ‘OH excretion’. Chara corallinaproduces acid and alkaline regions in unbuffered external media,in the light, even when CaCO3 is not being precipitated. Theseregions are associated with uptake and ‘OHefflux’ respectively. We have found that large currentscirculate, in the light, between acid and alkaline zones ofChara internodes, by (i) direct measurement of the short-circuitcurrent and (ii) measurement of potential differences in thesolution around the cell. Both methods suggest currents of 0.5–1µA per zone, with local current densities of about 75mA m–2, or local univalent fluxes of 0.75 µmol m–2s–1. These circulating currents produce mean peak-to-peakpotential differences of 7 mV in the external medium. The fluxesare believed to be of and H+ or OH.While active transport of is strongly indicated, passive uniport of H+ or OH appears to be sufficient.Control systems for both fluxes would be required.  相似文献   

10.
ERRATA     
Page 806, Preparation of Mitochondrial Fraction, line 4: The following should be inserted between ‘centrifugedat’ and ‘20 000 g for’: 3000 for 10 mm. Thesupernatant was centrifuged at The following corrections are required: Page 104, line 20: ‘2-hydroxylation’ should read ‘2-ß3-hydroxylation’ Page 106, line 11: ‘of Ga8’ should read ‘to GA8’ Page 113, last line:‘length 50 µm’ shouldread ‘length 150 µm’ Formula 15 should read: Formula 17 should read: y(0)– y* = ß1V12V2 page 118: Formula 18 should read: Formula 23 should read: Formula 24 should read:   相似文献   

11.
Pennings  Guido 《ESHRE Monographs》2008,2008(1):15-20
1 Correspondence address. Tel/Fax: +32-16-620767; E-mail: guido.pennings{at}ugent.be The provision of infertility treatment in developing countriesis controversial. Reports over the last decades have inculcatedin people from Western countries the belief that overpopulationis the major problem of developing countries. This paper willanalyse the different arguments advanced for and against providinginfertility treatment to resource-poor countries. There aretwo arguments in favour: reproductive autonomy and the hugeburden of infertility in these countries. Pronatalism, whichreigns in almost all developing countries, is to a great extentresponsible for the devastating effects of infertility. Thefive arguments against the application of infertility treatmentare overpopulation, prioritization of limited resources, preventionrather than cure, justice and equal access and risk of abuse.The importance of a person's reproductive autonomy demands thatefforts should be made to enable people to determine how manychildren to have. This is equally true in developing countries.However, given the enormous difficulties of resource-poor countriesto provide even the most basic goods, the contribution by societyshould be directed mostly at prevention and should depend ona strong cost reduction for assisted reproductive technology.  相似文献   

12.
The levels of purine and pyrimidine nucleotides in suspensioncultures of Catharanthus roseus were determined 24 h after stationary-phasecells were transferred to fresh complete (‘+Pi’)or phosphate-deficient (‘–Pi’) Murashige-Skoogmedium. The levels of ATP, GTP, UTP and CTP were from approx.3 to 5-fold greater in the cells grown in ‘+Pi’medium than in the cells grown in ‘–Pi’ medium.The levels of almost all other nucleotides were slightly higherin the cells in ‘+Pi’ medium. The rates of de novoand salvage biosynthesis of purine and pyrimidine nucleotideswere estimated from the rates of incorporation of radioactivityfrom [14C]formate, [2–14C]glycine, NaH14CO3, [6–14C]orotate,[8–14C]adenine, [8–14C]adenosine, [2–14C]uraciland [2–14C]uridine. The results indicated that the activityof both the de novo and the salvage pathway was higher in thecells in ‘+Pi’ medium than in the cells in ‘–Pi’medium. The rate of degradation estimated from the rate of releaseof 14CO2 from labelled purines and pyrimidines indicated thatdegradation of uridine was significantly reduced in the cellsin ‘+Pi’ medium, but no significant difference wasfound in the degradation of adenine, adenosine and uracil. Thepossible role of Pi in the control of the biosynthesis of nucleotidesand in the degradation of uridine is discussed. Catharanthus roseus, Madagascar periwinkle, suspension culture, inorganic phosphate, nucleotides, purines, pyrimidines, biosynthesis, degradation  相似文献   

13.
1 Correspondence address. E-mail: petra.desutter{at}ugent.be In 2% of assisted reproductive techniques (ART) cycles complicationsoccur. Some are preventable, some are not. In this paper, wewill discuss risks and complications of the standard ‘Western’approach in ART today and point to some measures to be takenwhen implementing ART in developing countries, where resourcesand access to medical care may be limited. Ovarian hyperstimulationsyndrome (OHSS, and its thrombo-embolic complications) is responsiblefor the majority of cycle-related complications, followed bybleeding and infection at oocyte retrieval. ART pregnanciesare complicated by first-trimester bleeding more often thanspontaneous pregnancies, they are more often ectopic, but themajor complication is the very high incidence of multiple pregnancies,when more than one embryo is transferred. OHSS can be preventedby screening patients at risk and by using mild or no stimulation.Simple measures can minimize the risks of bleeding or infection.Obviously single embryo transfer is the only way to avoid multiplepregnancies, which have a highly increased risk for severe maternaland neonatal morbidity and mortality (mainly due to prematurity).Special attention should be given to pre-existing pathologies.Risk minimization of ART in developing countries is not onlymandatory from an economical but also an ethical point of view.  相似文献   

14.
Abstract line 12: for ‘below 2.03, 0.53 and 0.28 mequiv.K+l–1 respectively’ read ‘below 0.28, 0.53and 2.03 mequiv. K+l–1 respectively.’  相似文献   

15.
The growth, morphology and carbon allocation patterns of F1progeny white clover (Trifolium repens L.) plants selected foreither low (‘LBF’) or high (‘HBF’) frequencyof stolon branching were compared in two controlled-environmentexperiments. Selections from within both a small-leaved (‘GrasslandsTahora’) and a large-leaved (‘Grasslands Kopu’)clover cultivar were compared, and plants were grown under arelatively lenient defoliation treatment (expt 1) or under threelevels of defoliation seventy (expt 2). Carbon allocation patternswere measured by 14CO2 pulse-chase labelling using fully unfoldedleaves on the main (parent) stolon. LBF and HBF displayed consistent differences in the selectedcharacter though, within cultivars, the difference between selectionswas most pronounced for Kopu. The selections developed fundamentallydifferent branching structures resulting from differences inbranching frequency, with total branch weight per plant averaging122 mg for LBF and 399 mg for HBF (mean of both experiments).More C moved from parent stolon leaves to branches in HBF thanin LBF (mean 22.6% vs. 15.1% respectively of the 14C exportedfrom source leaves). More C also moved to stolon tissue in HBF,but, counterbalancing this and the difference in allocationto branches, less moved to developing leaves and roots on theparent stolon itself compared to LBF. However, the total weightof developing leaves and roots per parent stolon was generallygreater in HBF than in LBF, probably reflecting greater C importby these sinks from the higher number of branches present perplant in the former selection. HBF plants were consistentlylarger at harvest than LBF plants. There were no defoliationtreatment x selection interactions in C allocation patternsin expt 2. The implications of the results for plant performancein grazed pastures are discussed. Branching, carbon translocation, defoliation, growth, morphology, Trifolium repens, white clover  相似文献   

16.
Nitrate provision has been found to regulate the capacity forChara corallina cells to take up nitrate. When nitrate was suppliedto N sufficient cells maximum nitrate uptake was reached after8 h. Prolonged treatment of the cells in the absence of N alsoresulted in the apparent ability of these cells to take up nitrate.Chlorate was found to substitute partially for nitrate in the‘induction’ step. The effects on nitrate reductionwere separated from those on nitrate uptake by experiments usingtungstate. Tungstate pretreatment had no effect on NO3uptake ‘induced’ by N starvation, but inhibitedNO3 uptake associated with NO3 pretreatment. Chloridepretreatment similarly had no effect on NO3 uptake ‘induced’by N deprivation, but inhibited NO3 uptake followingNO3 pretreatment. The data suggest that there are atleast two mechanisms responsible for the ‘induction’of nitrate uptake by Chara cells, one associated with NO3reduction and ‘induced’ by CIO3 or NO3and one associated with N deprivation. Key words: Nitrate, Chlorate, Chara corallina, Induction  相似文献   

17.
Assimilate Uptake and Water Loss in Maturing Barley Grains   总被引:1,自引:1,他引:0  
When detached ears of barley were supplied with [U-14C] sucrosefor 4 h, 14C was detected in the endosperms of grains from earsharvested 50 ‘days’ after anthesis, i.e. 10–15‘days’ after cell wall modifications had taken placein the chalazal region of the caryopsis. In 55-‘day’ears which had been supplied with [U-14C] sucrose for 20 h no14C was detected in the upper part of the rachis or in grainswith a moisture content of less than about 25%. In the rachisof wheat and barley, the walls of the xylem parenchyma and phloemcells stain strongly with ruthenium red, and in immature rachidesthis stainability is lost when sections are incubated with pectinase.Near the apex of 55-‘day’ ears the pectinaceouswall material in the vascular bundles is resistant to digestionby pectinase, and pectic substances, which are removed by pectinase,fill the lumina of the xylem elements. These observations arediscussed in relation to the dehydration of the maturing grain. Key words: Barley, 14C-sucrose, Pectic material, Xylem  相似文献   

18.
Floral buds of the ‘False Horn’ plantain clonesMusa (AAB) ‘Harton Verde’, ‘Harton Negra’,and ‘Currare’ terminate in a large single floralstructure. The apices of these floral buds are here designatedas determinate since they have lost the ability to produce additionalfloral initials or buds. Terminal peduncle segments can be culturedin a modified Murashige and Skoog (1962) medium supplementedwith N6-benzyl-aminopurine (5 mg I–1). Under these conditions,this apparent inability to yield buds can be overcome as vegetativeshoot clusters form in the axils of the bracts. Rooted plantletsare obtainable by treating shoots with naphthaleneacetic acid(1 mg I–1) and activated charcoal (0.025%). The adventitiousorigin of the shoots has been established. Musa cultivars, plantains, floral bud, adventitious buds, tissue culture  相似文献   

19.
Five Gladiolus cultivars, namely ‘Aldebaran’, ‘BrightEye’, ‘Illusion’, ‘Manisha’ and‘Manmohan’, were exposed to 1 and 2 µg l–1sulphur dioxide to test their relative-sensitivity toleranceto the pollutant Plants were fumigated experimentally for 2h daily Foliar injury symptoms were observed first in ‘Manisha’followed by ‘Aldebaran’ and ‘Illusion’at the higher dose Photosynthetic pigments and leaf extractpH were significantly decreased, particularly in ‘Manisha’and ‘Illusion’ Overall disturbances in the plantmetabolism due to SO2 treatment led to retarded growth of plants,as evident from decreased shoot length and phytomass valuesThe order of sensitivity of the five Gladiolus cultivars toSO2 was as follows, with the greatest first Manisha, Illusion,Aldebaran, Bright Eye, Manmohan Cultivars, Gladiolus, sensitivity, sulphur dioxide, tolerance  相似文献   

20.
Patterns of distribution of 14C were determined in 47-day-oldtomato plants (Lycopersicon esculentum Mill.) 24 h after theapplication of [14C]sucrose to individual source leaves fromleaves 1–10 (leaf 1 being the first leaf produced abovethe cotyledons). The first inflorescence of these plants wasbetween the ‘buds visible’ and the ‘firstanthesis’ stages of development. The predominant sink organs in these plants were the root system,the stem, the developing first inflorescence and the shoot ‘apex’(all tissues above node 10). The contribution made by individualsource leaves to the assimilate reaching these organs dependedupon the vertical position of the leaf on the main-stem axisand upon its position with respect to the phyllotactic arrangementof the leaves about this axis. The root system received assimilateprincipally from leaf 5 and higher leaves, and the stem apexfrom the four lowest leaves. The developing first inflorescencereceived assimilates mainly from leaves in the two orthostichiesadjacent to the radial position of the inflorescence on thevertical axis of the plant; these included leaves which weremajor contributors of 14C to the root system (leaves 6 and 8)and to the shoot apex (leaves 1 and 3). This pattern of distributionof assimilate may explain why root-restriction treatments andremoval of young leaves at the shoot apex can reduce the extentof flower bud abortion in the first inflorescence under conditionsof reduced photoassimilate availability. Lycopersicon esculentum Mill, tomato, assimilate distribution, source-sink relationships  相似文献   

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