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141.
Fluorescent antibody and complement-fixation tests of agents isolated in tissue culture from measles patients 总被引:4,自引:0,他引:4
142.
RYLE G. J. A.; POWELL C. E.; TIMBRELL M. K.; GORDON A. J. 《Journal of experimental botany》1989,40(7):733-739
Single, clonal plants of white clover were grown without inorganicnitrogen in four contrasting day/night temperature regimes,with a 12 h photoperiod, in controlled environments. Root andnodule respiration and acetylene reduction activity were measuredin a flow-through system during both day and night for plantsacclimated to day/night regimes of 23/18, 15/10 and 10/5 ?C.Similar measurements were made on plants acclimated to 20/15?C and stepwise at temperatures from 4 to 33 ?C. Peak rate of ethylene production, nitrogenase-linked respirationand basal root + nodule respiration increased approximatelylinearly from 5 to 23 ?C both in temperature-acclimated plantsand in plants exposed to varying measurement temperatures. Themeasured attributes did not vary significantly between day andnight. Temperatures above 2325 ?C did not further enhancethe rate of ethylene production, which remained essentiallythe same up to the maximum measured temperature of 33 ?C. The measurements of nitrogenase-linked respiration between 5and 23 ?C, during both day and night, demonstrated a constantenergetic cost of acetylene reduction of 2.9 µmolCO2 µmol C2H41,. Over the same temperature range,the approximate activation energy of acetylene reduction was60 kJ mol1. The integrated day plus night nitrogenase-linkedrespiration accounted for 13.416% of the plantsnet shoot photosynthesis in a single diurnal period: there wasno significant effect of temperature between 5 and 23 ?C. Key words: Trifolium repens, white clover, temperature, N2 fixation, respiration 相似文献
143.
144.
GORDON B. CURRY ALWYN WILLIAMS 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1983,16(2):111-118
A fine hexagonal network of microscopic ridges has been discovered on the internal shell surface of the cosmopolitan Lower Palaeozoic inarticulate genus Lingulella. The micro-ornamentation has been recognised on all well-preserved specimens examined, from Cambrian and Ordovician successions in Ireland, North America, Gt. Britain, Spitzbergen, and China. Examination of the mantle of the related Recent genus Lingula revealed that the outer epithelial cells are arranged in a hexagonal close-packed pattern comparable in size and form to the micro-ornamentation in the fossil shells. This fact, along with the discovery of a polygonal pattern on some organic layers in the Lingula shell, suggests that the micro-ornamentation in fossil Lingulella is the mould of the outer epithelium responsible for shell secretion. No trace of epithelial moulds has yet been found in specimens of Lingula from younger Palaeozoic successions. This difference may prove to be a useful diagnostic feature in distinguishing linguloid inarticulates from one another. Epithelial moulds , Lingulella, Palaeoglossa, Lingula, Cambrian, Ordovician, Recent. 相似文献
145.
A device for measuring the integrated temperature sensed by a thermocouple during a grass, forest or other landscape fire is described and its performance evaluated. It consists of a small tube containing an electronic circuit to which is attached a length of thermocouple wire. The tube is buried for the duration of the fire. Principal component of the circuit is an E-cell (or microcoulometer) which when cleared allows calculation of the temperature/time integral. Performance was found to be reliable and accurate: because of its low cost it has widespread application for measuring the temperature in soil, plants or air during fires. 相似文献
146.
SYNOPSIS. Social groups of rhesus monkeys (Macaca mulatto) livingin outdoor environments exhibit a distinct seasonal mating patternand female rhesus are observed to be sexually receptive fordiscrete periods averaging about 9 days duration. In the laboratoryenvironment mating occurs throughout the year and, in the pairtest, female rhesus are observedto be sexually receptive throughall phases of a menstrual cycle, with a periovulatory peak incopulatorybehavior. The apparent conflict between results from field andlaboratory studies has been difficult to resolve because ofmethodological limitations inherent in each study environment.Studies conducted on social groups of rhesus monkeys housedin outdoor compounds, an environment in which the species typicalseasonal mating pattern is preserved and which allowsfor concomitantmeasurement of behavioral and hormonal variables, provided informationabout the covariance between female sexual behavior and ovariancycles. Female copulations were observed only in associationwith ovulatory cycles, and were limited to the follicular andperi-ovulatory phases of such cycles, demonstrating that copulatorybehavior in female rhesus monkeys is strongly influenced bycyclic hormonal variables. The studies also revealed that femalestend to conceive on the first ovulatory cycle of the season,that there was no synchrony of cycles among the females, andthat the best predictor of the timing of ovulation in a particularfemale is reproductive outcome in the previous year. 相似文献
147.
Export, Mobilization, and Respiration of Assimilates in Uniculm Barley during Light and Darkness 总被引:3,自引:0,他引:3
GORDON A. J.; RYLE G. J. A.; POWELL C. E.; MITCHELL D. 《Journal of experimental botany》1980,31(2):461-473
The respiratory losses and the pattern of carbon supply froma leaf of unicuim barley were examined during a complete diurnalperiod using a steady state 14C-labelling technique. After a delay of c. 1 h a portion of the 14C exported from acontinuously assimilating leaf was lost in respiration in thelight. This respiratory loss amounted to c. 20% of the total14C fixed. A further 28% of the total 14C fixed was respiredduring the dark period. In the light, carbon was fixed at a rate of c. 8·9 mgC dm2 h1 and exported from the leaf at c. 5·3mg C dm2 h1. Dark export averaged c. 31% of theday-time rate. Carbohydrate was stored in the leaf during the day and was almostcompletely remobilized during the dark. Sucrose, the major reservecarbohydrate, was exported first whilst the starch level remainedconstant. After some 9 h of darkness, sucrose declined to alow level and starch remobilization began. 相似文献
148.
The Relationship between Sucrose and Starch during 'Dark' Export from Leaves of Uniculm Barley 总被引:7,自引:0,他引:7
Uniculm barley plants were grown in 8 h photoperiods at a quantumflux density of 655 µE m2 s1. Groups ofplants were transferred to four different light environmentsfor one 8 h photoperiod (106, 270, 665, and 975 µE m2s1) and harvested at intervals throughout the succeedingdark period for subsequent carbohydrate analysis of the youngestmature leaf. Sucrose was the predominant carbohydrate in the leaves (attaininga level of c. 100 mg dm2 after 8 h at 975 µE m2s1) but starch was also of significance (20 mg dm2after 8 h at 975 µE m2 s1). During the dark period, following a photoperiod at the threehighest light levels (270, 665, and 975 µE m2 s1),sucrose was exported first while the starch level remained fairlyconstant. When the-sucrose level fell to 1520 mg dm2starch degradation began. This critical sucrose level was reachedearlier in those plants subjected to lower quantum flux densitiesduring the preceding photoperiod. The delay in the remobilizationof starch suggests an important regulatory mechanism which maybe dependent upon the sucrose level. At 106 µE m2s1 the sucrose level rose to only 10 mg dm2. Herethere was no discernible delay in the depletion of sucrose orstarch. 相似文献
149.
The assemblage of carabid species trapped over a 3 yr period in eight separate but contiguous fields was analysed by Canonical Correspondence Analysis (CCA), Seven of the fields were subject to arable crop rotations involving a mixture of autumn and early spring‐sown cereals (wheat or barley), late spring‐sown crops (potatoes, sugar and fodder beet and maize) and short‐term uncultivated grass leys, The eighth field was an established ‘permanent’ grass pasture of at least 50 yrs standing, Pooled samples collected in the first half of the growing season (April‐June) showed clear evidence of soil cultivation effects on community structure, Systematic exclusion of samples and re‐analysis distinguished the fauna of firstly, old pasture samples, samples from ley pastures of increasing age and finally samples from fields with different times of soil cultivation, In the latter analysis, the main effects of soil cultivation were related to differences in ground cover over the winter and a direct effect of spring soil cultivation on autumn breeding populations, The ordination of pooled catches for the second half of the growing season (July‐September) could not be related to known year, field or crop cultivation variables, The underlying species ordination suggested that later in the summer the effect of crop cover on soil microclimate may mask cultivation effects by influencing the post‐emergence dispersal of autumn‐breeding populations and the reproductive success of spring‐breeders, The combination of earlier soil cultivation effects, and probably microclimatic influences later in the season, resulted in the strong distinction of whole season carabid catches from individual fields, It is concluded that the uniqueness of individual field histories may provide a mechanism to promote the co‐existence of ecologically similar species within the farmed landscape and enhance the abundance and bio‐diversity of species in the face of routine soil cultivation. 相似文献
150.
WILSON M. M.; GORDON M. E.; LETHAM D. S.; PARKER C. W. 《Journal of experimental botany》1974,25(4):725-732
Excised immature radish cotyledons were allowed to take up [3H]6-benzylaminopurinefor up to 5 h and were then transferred to cytokinin.free mediumfor various intervals, after which they were extracted. Thecytokinin was rapidly metabolized by the tissue to two mainproducts which accounted for 20 per cent of the extracted radioactivityafter 1 h of uptake, and for 95 per cent after transfer to thecytokinin-free medium. These metabolites were coincident withcytokinin activity on chromatograms of the cotyledon extractand were also formed when 6-benzylaminopurine was supplied to9-d-old derooted seedlings through the transpiration stream.The metabolites were identified by mass spectrometry, u.v. spectroscopy and chemical degradation as 6-benzylarnino-7-glucosylpurineand 6-benzylamino-9. glucosylpurine. Several minor metaboliteswere detected in the derooted seedlings; one was 6-benzylaminopurineriboside while another appeared to possess high cytokinin activity. 相似文献