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101.
Respiration and growth of tomato fruit 总被引:1,自引:0,他引:1
The respiration rate and diameter expansion growth of young tomato fruit were measured simultaneously and related to changes in carbon import and plant water status. Respiration rate was directly proportional to the volume expansion rate of fruit growing on isolated plant tops at a positive water potential, whether the growth rate was changed by changing the fruit temperature or by manipulating the source:sink ratio of the plants. From the latter relationship, the maintenance respiration rate was estimated by extrapolation to zero growth and was found to be about 25% of the respiration rate of the average fruit at 21°C. Alternatively, when carbon import was prevented by heat-ringing the fruit peduncle, the respiration rate of the fruit declined to about 40% of the control rate and remained steady, while the expansion rate then declined steadily to >10% of the control rate. These results show that fruit expansion was not contributing significantly to fruit respiration. Indeed, large fluctuations in fruit expansion rate could also be induced by repeated darkening and illumination of potted plants without a corresponding change in fruit respiration. Most significantly, fruit expansion was considerably reduced when plants were allowed to wilt, hut there was no change in fruit respiration rate unless the fruit peduncle was subsequently heat-ringed. We conclude that a major part of the respiration of young tomato fruit was determined by the rate of carbon import, or associated processes, and that fruit expansion per se can occur with relatively low respiratory costs. 相似文献
102.
Direct measurements of urinary immunoreactive estrone conjugates (E1C) and pregnanediol glucuronide (PdG), were applied to monitoring the ovarian cycle (n = 9) and pregnancy (3 full term pregnancies, 2 mid-term abortions) in Saguinus fuscicollis. During the ovarian cycle, urinary E1C concentrations revealed a high degree of day-to-day variability and appeared to be uninformative in reflecting cyclic ovarian function. In contrast, PdG was a reliable indicator of ovarian cyclicity with excretion patterns corresponding well with plasma progesterone profiles. Luteal phase PdG concentrations were on average 4–7–fold higher than corresponding follicular phase values. On the basis of changes in circulating progesterone, a mean cycle length of 25.7 ±1.0 days with an average follicular phase of 7.1 ± 0.6 days and a mean luteal phase of 18.6 ± 0.7 days, was found (n = 14 cycles). Following conception, both urinary steroid conjugate concentrations increased and elevated levels were maintained beyond the normal luteal phase length, allowing pregnancy to be determined at around day 25–30. During mid- to late pregnancy, PdG levels declined while E1C concentrations continued to be elevated until approximately 6 weeks before parturition when a decrease occurred. Both hormones showed a clear and rapid fall to follicular phase values following termination of pregnancy at either parturition or mid-term abortion. Post partum ovulations (n = 5) occurred on average 17–18 days following birth with four ovulations leading to conceptions. The results demonstrate the potential of urinary steroid conjugate analysis as a practical and reliable method for non-invasive monitoring of reproductive status in the female saddle-back tamarin. © 1995 Wiley-Liss, Inc. 相似文献
103.
104.
Blessing Chidimuro Sean Doherty Jonathan Finch Paola Ponce Jack Eggington Sarah Delaney Camilla Speller Matthew J. Collins Malin Holst Michelle Alexander 《American journal of physical anthropology》2023,182(1):126-142
Objectives
We evaluate the potential of paired isotopic analysis of bone carbonate and collagen to examine the diet of post-medieval human and animal populations from England (17th–19th c.), including, for the first time, manufacturing towns in northern England. The potential for identifying C4 crop consumption is explored alongside regional and local patterning in diet by sex and socioeconomic status.Materials and Methods
Humans (n = 216) and animals (n = 168) were analyzed from sites in London and northern England for both carbon and nitrogen isotopes of bone collagen (𝛿13Ccoll, 𝛿15Ncoll). Isotopic analysis of bone carbonates (𝛿13Ccarb, 𝛿18Ocarb) was carried out on all humans and 27 animals, using Fourier transform infrared spectroscopy–attenuated total reflectance to assess diagenesis.Results
Variations in diet were observed between and within different populations by geographical location and socioeconomic status. Three pigs and one cow consumed C4 resources, indicating the availability of C4-fed animal protein. Londoners consumed more animal and marine protein and C4 resources. Middle- and upper-class populations from both London and northern populations also had greater access to these foods compared to those of lower status in the same regions.Discussion
This substantial multi-isotope dataset deriving from bone carbonate and collagen combined from diverse post-medieval urban communities enabled, for the first time, the biomolecular identification of the dynamics of C4 consumption (cane sugar/maize) in England, providing insight into the dynamics of food globalization during this period. We also add substantially to the animal dataset for post-medieval England, providing further insight into animal management during a key moment of agricultural change.105.
Any Bernstein Amanda Mangeon Janice Almeida-Engler Gilbert Engler Marc Van Montagu Gilberto Sachetto-Martins Dulce Eleonora de Oliveira 《Plant signaling & behavior》2015,10(1)
Over the past decades, several studies indicate a correlation between the phytohormone auxin and cell division. The molecular players of this signaling pathway are now being uncovered. DNA Binding Protein1 from Arabidopsis (AtDBP1) is an auxin-inducible gene able to bind DNA non-specifically. In this work the tissue-expression pattern of this gene was investigated. Promoter-GUS analysis demonstrated that the AtDBP1 promoter is active in regions exhibiting intense cell division such as meristems and nematode feeding sites. Also, the promoter expression was modulated upon incubation with cell cycle blockers, indicating a potential role in cell division for this gene. Lastly, AtDBP1 antisense plants presented a higher insensitivity to auxin, and interfered negatively with auxin–induced callus formation and reduced apical dominance. 相似文献
106.
The green marine macroalga Ulva lactuca L. was found to be able to utilize HCO3? from sea water in two ways. When grown in flowing natural sea water at 16°C under constant dim irradiance, photosynthesis at pH8.4 was suppressed by acetazolamide but unaffected by 4,4′-diisothiocyanostilbene-2,2′-disulphonate. These responses indicate that photosynthetic HCO3? utilization was via extracellular carbonic anhydrase (CA) -mediated dehydration followed by CO2 uptake. The algae were therefore described as being in a ‘CA state’. If treated for more than 10 h in a sea water flow-through system at pH9.8, these thalli became insensitive to acetazolamide but sensitive to 4,4′-diisothiocyanostilbene-2,2′-disulphonate. This suggests the involvement of an anion exchanger (AE) in the direct uptake of HCO3?, and these plants were accordingly described as being in an ‘AE state’. Such thalli showed an approximately 10-fold higher apparent affinity for HCO3? (at pH9.4) than those in the ‘CA state’, while thalli of both states showed a very high apparent affinity for CO2. These results suggest that the two modes of HCO3? utilization constitute two ways in which inorganic carbon may enter the Ulva lactuca cells, with the direct entry of HCO3?, characterizing the ‘AE state’, being inducible and possibly functioning as a complementary uptake system at high external pH values (e.g. under conditions conducive to high photosynthetic rates). Both mechanisms of entry appear to be connected to concentrating CO2 inside the cell, probably via a separate mechanism operating intracellularly. 相似文献
107.
The fusion oncogene, promyelocytic leukemia (PML)-retinoic acid receptor-α (RARα), is crucial for acute promyelocytic leukemia (APL) pathogenesis. Previous studies have reported that PML-RARα is cleaved by neutrophil elastase (NE), an early myeloid-specific serine protease, leading to translocation of the nuclear localization signal (NLS) of the PML protein to the N-terminal of RARα. This study was designed to evaluate the value of NLS-RARα in the early diagnosis of APL. To investigate the potential functional role of NLS-RARα in leukemogenesis, HL-60 and U937 cell lines were transfected with NLS-RARα lentivirus and negative control (LVNC). The results showed that the induced expression of NLS-RARα down-regulated expressions of CD11b, CD11c, and CD14 compared to the LVNC group induced by 1α, 25-dihydroxyvitamin D3(1,25(OH)2D3). This suggested that NLS-RARα overexpression inhibited granulocytic and monocytic differentiation of myeloid leukemia cells. In addition, Wright-Giemsa staining, flow cytometry, respiratory burst assay, and NBT reduction assay all confirmed the importance of NLS-RARα in differentiation. The mechanistic investigations revealed that induced NLS-RARα expression inhibited 1,25(OH)2D3-induced granulocytic differentiation by regulating the cell cycle regulators p19INK4D, p21WAF1/CIP1, cyclinD1, cyclin E1, and pRB. Furthermore, the cleaved protein NLS-RARα enhanced the oncogenicity of U937 cells in NOD/SCID mice. These findings collectively demonstrated that NLS-RARα blocked granulocytic and monocytic differentiation of myeloid leukemia cells by inhibiting the downstream targets of the RARα signal pathway and the cell cycle. This may provide a promising new target and method for diagnosing and treating APL. 相似文献
108.
109.
Abstract. Steady-state photosynthesis (Pn ), post-illumination CO2 release rates (R), sucrose-phosphate synthase (SPS) activities, and levels of starch, sucrose and hexoses were measured in the source leaf of corn ( Zea mays L.) during a 16-h photoperiod at 800 μmol m 2 s 1 . Pn and SPS activity remained constant. Carbohydrate pools increased at a linear rate, except the first and last hour of the photoperiod. Both the CO2 evolution rate at the moment of light removal (Rmax ) and SPS activity decreased by one half after the onset of darkness (0 60 min). Sucrose diminished during this period by 40%, whereas the starch remained constant. Thereafter, starch mobilization began, followed by a gradual decline in leaf respiration. The average dark export rate was calculated to be 60% less than that during the day. Maintenance respiration (Rm ) of an attached leaf after 48 h darkness was determined. Plants were illuminated for different intervals (e.g. 5, 10 or 20 min), each followed by dark periods sufficient for respiration to decline to Rm . The ratio of C assimilated in light to that released in dark was 6:1. After the 48-h dark period, the minimal period of illumination (Tmin ) required to restore Pn and Rmax to the original level was determined. A mathematical analysis of the kinetics involved in the recovery of Pn and Rmax provided an estimate of turnover time (0.22h) and pool size 9.15 mmol m 2 ) for the newly fixed carbon. 相似文献
110.
Dissolved organic carbon (DOC) plays an important role in surface water chemistry and ecology and trends in DOC concentration
have been also associated with shifts in terrestrial carbon pools. Numerous studies have reported long-term trends in DOC
concentration; however, some studies consider changes in average measured DOC whereas other compute discharge weighted concentrations.
Because of differences in reporting methods and variable record lengths it is difficult to compare results among studies and
make regional generalizations. Furthermore, changes in stream discharge may impact long-term trends in DOC concentration and
the potentially subtle effect of shifts in stream flow may be missed if only measured DOC concentrations are considered. In
this study we compare trends in volume-weighted vs. average measured DOC concentration between 1980 and 2001 at seven headwater
streams in south-central Ontario, Canada that vary in wetland coverage and DOC (22-year mean vol. wt.) from 3.4 to 10.6 mg l−1. On average, annual measured DOC concentrations were 13–34% higher than volume-weighted values, but differences of up to
290% occurred in certain years. Estimates of DOC flux were correspondingly higher using measured concentration values. Both
measured and volume-weighted DOC concentrations increased significantly between 1980 and 2001, but slopes were larger in measured
data (0.04–0.35 mg l−1 year−1 compared with 0.05–0.15 mg l−1 year−1) and proportional increases at the most wetland-influenced sites ranged from 32 to 43% in volume-weighted DOC and from 52
to 75% in measured DOC. In contrast, DOC flux did not change with time when estimated using either method, because of the
predominant influence of stream flow on DOC export. Our results indicate that changes in stream flow have an important impact
on trends in DOC concentration, and extrapolation of trend results from one region to another should be made cautiously and
consider methodological and reporting differences among sites. 相似文献