scholarly journals Calcium Localization and Tipburn Development in Lettuce Leaves during Early Enlargement

2000 ◽  
Vol 125 (3) ◽  
pp. 294-298 ◽  
Author(s):  
Daniel J. Barta ◽  
Theodore W. Tibbitts
Keyword(s):  
Lactuca Sativa ◽  
Electron Microprobe ◽  
Dry Weight ◽  
Tissue Concentrations ◽  
X Ray ◽  
Ca Deficiency ◽  
Low Concentrations ◽  
Wavelength Dispersive Spectrometer ◽  
Low Levels ◽  
Mineral Accumulation

Tissue concentrations of Ca, Mg, and K were determined across immature leaves of lettuce (Lactuca sativa L. `Buttercrunch') at different stages of enlargement using electron microprobe x-ray analysis. The analysis was with a wavelength dispersive spectrometer to permit detection of low concentrations of Ca. Patterns of mineral accumulation in immature leaves that were exposed were compared to patterns of accumulation in leaves that were enclosed within a developing head. The leaves developing without enclosure were free to transpire and developed normally whereas leaves developing with enclosure were restricted in transpiration and developed an injury that was characteristic of Ca deficiency. In the exposed leaves, Ca concentrations increased from an average of 1.0 to 2.1 mg·g-1 dry weight (DW) as the leaves enlarged from 5 to 30 mm in length. In the enclosed leaves, Ca concentrations decreased from 1.0 to 0.7 mg·g-1 DW as the leaves enlarged from 5 to 30 mm in length. At the tips of these enclosed leaves a larger decrease was found, from 0.9 to 0.3 mg·g-1 DW during enlargement. Necrotic injury first became apparent in this tip area when the concentration was ≈0.4 mg·g-1 DW. Magnesium concentrations across the exposed leaves were similar to concentrations across the enclosed leaves, and did not change with enlargement. Magnesium concentrations averaged 3.5. mg·g-1 DW in both enclosed and exposed leaves during enlargement from 5 to 30 mm. In both exposed and enclosed leaves, K concentrations increased during enlargement from 40 to ≈60 mg·g-1 DW. Potassium concentrations were highest toward the leaf apex and upper margin where injury symptoms occurred, and this may have enhanced injury development. This research documents the critical low levels of Ca (0.2 to 0.4 mg·g-1 DW) that can occur in enclosed leaves of plants and which apparently leads to the marginal apex necrosis of developing leaves seen frequently on lettuce and other crops.

Heavy Metal Concentrations in the Muscle Tissue of 12 Species of Teleost from Cockburn Sound, Western Australia

1979 ◽  
Vol 30 (5) ◽  
pp. 607 ◽  
Author(s):  
D Plaskett ◽  
IC Potter
Keyword(s):  
Muscle Tissue ◽  
Movement Pattern ◽  
Dry Weight ◽  
Metal Concentrations ◽  
Fish Flesh ◽  
Low Concentrations ◽  
Drug Regulations ◽  
The Indian Ocean ◽  
Low Levels ◽  
Teleost Muscle

The wet and dry weight concentrations of Cd, Zn, Cu, Pb, Fe, Mn, Ni, Cr and Co have been measured in muscle tissue taken from 12 species of teleost caught in Cockburn Sound. The maximum concentration of each of the metals found in the fish was well below the values given in the National Health and Medical Research Council Standards and the Western Australian Food and Drug Regulations. Considering the rate at which metals are known to be discharged into the Sound the low concentrations found in fish flesh contrast with the appreciable rate at which metals are discharged and accumulate in certain regions of the Sound. Furthermore, the metal concentrations in fish flesh are many times lower than in invertebrates such as the mussel, Mytilus edulis. It is suggested that the low levels in fish flesh reflect both the relatively low rate at which heavy metals are accumulated by teleost muscle and also the movement pattern of fish within the polluted and relatively unpolluted regions of the Sound, and between the Sound and the Indian Ocean.

scholarly journals Calcium Localization in Lettuce Leaves with and without Tipburn: Comparison of Controlled-environment and Field-grown Plants

1991 ◽  
Vol 116 (5) ◽  
pp. 870-875 ◽  
Author(s):  
Daniel J. Barta ◽  
Theodore W. Tibbitts
Keyword(s):  
Electron Microprobe ◽  
Leaf Tissue ◽  
Dry Weight ◽  
Field Conditions ◽  
Controlled Environment ◽  
Tissue Concentrations ◽  
Calcium Localization ◽  
Controlled Environments ◽  
K Concentration ◽  
Faster Development

An electron microprobe was used to determine tissue concentrations of Ca across 20-mm-long leaves of `Green Lakes' crisphead lettuce (Luctuca sativa L.) with and without tipburn injury. Concentrations within the fifth and 14th leaves, counted from the cotyledons, from plants grown under controlled-environment conditions were compared to concentrations within similar leaves obtained from plants grown under field conditions. Only the 14th leaf from plants grown under controlled-environment conditions developed tipburn. Injured areas on these leaves had Ca concentrations as low as 0.2 to 0.3 mg·g-1 dry weight. Uninjured areas of tipburned leaves contained from 0.4 to 0.5 mg·g-1 dry weight. Concentrations across the uninjured 14th leaf from field-grown plants averaged 1.0 mg·g-1 dry weight. Amounts across the uninjured fifth leaves from both environments averaged 1.6 mg·g-1 dry weight. In contrast, Mg concentrations were higher in injured leaves than in uninjured leaves and thus were negatively correlated with Ca concentrations. Magnesium concentrations averaged 4.7 mg·g-1 dry weight in injured leaves compared with 3.4 mg·g-1 dry weight in uninjured leaves from both environments. Magnesium concentrations were uniform across the leaf. Potassium concentrations were highest at the leaf apex and decreased toward the base and also decreased from the midrib to the margin. Potassium averaged 51 mg·g-1 dry weight in injured and uninjured leaves from both environments. No significant differences in K concentration were present between injured and uninjured leaves. This study documented that deficient concentrations of Ca were present in areas of leaf tissue developing tipburn symptoms and that concentrations were significantly higher in similar areas of other leaves that had no symptoms. This study also documented that Ca concentrations were significantly lower in enclosed leaves that exhibited tipburn symptoms than in exposed leaves that did not exhibit tipburn. Also, the amounts of Ca in plants that developed tipburn in controlled environments were lower than in plants of the same cultivar that did not develop tipburn in field plantings. The reduced levels of Ca in plants grown in controlled environments were associated with faster development rates compared with field-grown plants.

Growth Effects of Pb stress on Seedling of Lactuca sativa L. and Brassica campestris L.ssp

2014 ◽  
Vol 886 ◽  
pp. 309-313
Author(s):  
Yan Yu Shi ◽  
Jing Hui Yang ◽  
Feng Yue Zuo ◽  
Jian Ke Li ◽  
Jun Xuan Huang ◽  
...  
Keyword(s):  
Lactuca Sativa ◽  
Brassica Campestris ◽  
Nitrate Solution ◽  
Lead Nitrate ◽  
Growth Index ◽  
Dry Weight ◽  
Growth Speed ◽  
Fresh Weight ◽  
Low Concentrations ◽  
Soilless Cultivation

In order to understand the effects of lead on the growth of Lactuca sativa L. and Brassica Campestris L. ssp, the change of growth index of seedling was studied under lead stress (different concentrations of lead nitrate solution), and by soilless cultivation of seedlings in pots and in greenhouse. The results showed that two kinds of plant growth were affected by lead stress of different level, the growth speed of seedlings reduced but a great number of growth index were increased, in addition to fresh weight and dry weight of stem and leaf. The leaf number, leaf area, plant height and the fresh weight, dry weight of stem and leaf in Lactuca sativa L. were declined obviously, and the fresh weight, dry weight of roots were increased under higher levels of lead treatment at the same time. The each growth index of Brassica Campestris L.ssp was decreased in higher concentration of lead treatment. The growth of Lactuca sativa L. was slightly better and Brassica Campestris L. was slightly lower than control under 0.005 mg/L lead treatment. So, Lactuca sativa L. wasmore sensitive in low concentrations of lead than Brassica Campestris L. Both of them reduced their growth significantly, especially Brassica Campestris L.in 0.015 mg/L lead treatment. Each grow index of Lactuca sativa L.and Brassica Campestris L. changed most in all kinds of lead concentration, and the growth was inhibited most in 0.045 mg/L lead. The growth of Brassica Campestris L.was decreased more under higher concentrations of lead compared with Lactuca sativa L..

Microtubule nucleation sequence studied by time-resolved x-ray scattering and electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 766-767
Author(s):  
Eva-Maria Mandelkow ◽  
Eckhard Mandelkow ◽  
Joan Bordas
Keyword(s):  
Electron Microscopy ◽  
Dynamic Equilibrium ◽  
Time Resolved ◽  
X Ray ◽  
Additional Information ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Microtubule Growth ◽  
Ray Patterns ◽  
Ray Scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

The CM120 Biotwin: a high-contrast objective lens, optimum cryo-vacuum and improved EDX performance

1995 ◽  
Vol 53 ◽  
pp. 584-585
Author(s):  
Uwe Lücken ◽  
Michael Felsmann ◽  
Wim M. Busing ◽  
Frank de Jong
Keyword(s):  
Life Science ◽  
Focal Length ◽  
Objective Lens ◽  
High Contrast ◽  
Contrast Imaging ◽  
X Ray ◽  
Forming Mechanism ◽  
Similar Image ◽  
High Contrast Imaging ◽  
Low Concentrations

A new microscope for the study of life science specimen has been developed. Special attention has been given to the problems of unstained samples, cryo-specimens and x-ray analysis at low concentrations.A new objective lens with a Cs of 6.2 mm and a focal length of 5.9 mm for high-contrast imaging has been developed. The contrast of a TWIN lens (f = 2.8 mm, Cs = 2 mm) and the BioTWTN are compared at the level of mean and SD of slow scan CCD images. Figure 1a shows 500 +/- 150 and Fig. 1b only 500 +/- 40 counts/pixel. The contrast-forming mechanism for amplitude contrast is dependent on the wavelength, the objective aperture and the focal length. For similar image conditions (same voltage, same objective aperture) the BioTWIN shows more than double the contrast of the TWIN lens. For phasecontrast specimens (like thin frozen-hydrated films) the contrast at Scherzer focus is approximately proportional to the √ Cs.

Long-term variations in individual particle types in the aerosol of Phoenix, Arizona, as determined using automated electron microprobe analysis and multivariate statistical techniques

1993 ◽  
Vol 51 ◽  
pp. 742-743
Author(s):  
Karen A. Katrinak ◽  
James R. Anderson ◽  
Peter R. Buseck
Keyword(s):  
Electron Microprobe ◽  
Fine Fraction ◽  
Coarse Fraction ◽  
Motor Vehicles ◽  
Multivariate Statistical Methods ◽  
Multivariate Statistical ◽  
X Ray ◽  
Mineral Particles ◽  
Anthropogenic Air Pollutants

Aerosol samples were collected in Phoenix, Arizona on eleven dates between July 1989 and April 1990. Elemental compositions were determined for approximately 1000 particles per sample using an electron microprobe with an energy-dispersive x-ray spectrometer. Fine-fraction samples (particle cut size of 1 to 2 μm) were analyzed for each date; coarse-fraction samples were also analyzed for four of the dates.The data were reduced using multivariate statistical methods. Cluster analysis was first used to define 35 particle types. 81% of all fine-fraction particles and 84% of the coarse-fraction particles were assigned to these types, which include mineral, metal-rich, sulfur-rich, and salt categories. "Zero-count" particles, consisting entirely of elements lighter than Na, constitute an additional category and dominate the fine fraction, reflecting the importance of anthropogenic air pollutants such as those emitted by motor vehicles. Si- and Ca-rich mineral particles dominate the coarse fraction and are also numerous in the fine fraction.

Localization of calcium and zinc in the sperm storage tubules of chicken, quail and turkey using X-ray microanalysis

Reproduction ◽  
2000 ◽  
pp. 331-336 ◽  
Author(s):  
L Holm ◽  
H Ekwall ◽  
GJ Wishart ◽  
Y Ridderstrale
Keyword(s):  
Calcium Concentration ◽  
Sperm Storage ◽  
X Ray ◽  
Elemental Concentrations ◽  
Low Concentrations ◽  
Intracellular Content ◽  
Wet Weight ◽  
The Mean ◽  
Sperm Storage Tubules ◽  
Scanning Electron

Sperm storage tubules from the utero-vaginal junction of chickens, quails and turkeys were analysed for calcium and zinc using X-ray microanalysis of ultra-rapidly frozen tissue in a scanning electron microscope. This technique enabled the tubular fluid surrounding the stored spermatozoa and the intracellular content of the cells of the sperm storage tubules to be analysed separately and, by using standards with known concentrations, their elemental concentrations were estimated. The mean (+/- SEM) concentration of calcium in the tubular fluid from chickens, quails and turkeys was 17 +/- 3, 19 +/- 3 and 17 +/- 4 mmol kg(-1) wet weight, respectively. The intracellular calcium concentration of the cells of the tubules did not differ significantly from these values and was also similar in the mucosal epithelial cells of the utero-vaginal junction. Zinc was localized in the cells of turkey sperm storage tubules and tubular fluid, but at low concentrations. No zinc could be detected in corresponding structures from chickens and quails. The concentration of calcium in the tubular fluid is within the range known to inhibit the motility of spermatozoa, supporting this function for calcium during storage. Zinc is known to depress turkey sperm metabolism and it may also be involved in inducing quiescence of spermatozoa during storage in this species.

Arsenic removal by MF membrane with chemical sludge adsorption and NF membrane equipped with vibratory shear enhanced process

2003 ◽  
Vol 3 (5-6) ◽  
pp. 303-310 ◽  
Author(s):  
S.-H. Yi ◽  
S. Ahmed ◽  
Y. Watanabe ◽  
K. Watari
Keyword(s):  
Arsenic Removal ◽  
Membrane Surface ◽  
Membrane Process ◽  
Low Concentrations ◽  
Strong Shear ◽  
Low Levels ◽  
Removal Processes ◽  
Removal Of Arsenic ◽  
Concentration Polarization Layer ◽  
Chemical Sludge

Conventional arsenic removal processes have difficulty removing low concentrations of arsenic ion from water. Therefore, it is very hard to comply with stringent low levels of arsenic, such as below 10 μg/L. So, we have developed two arsenic removal processes which are able to comply with more stringent arsenic regulations. They are the MF membrane process combined with chemical sludge adsorption and NF membrane process equipped with the vibratory shear enhanced process (VSEP). In this paper, we examine the performance of these new processes for the removal of arsenic ion of a low concentration from water. We found that chemical sludge produced in the conventional rapid sand filtration plants can effectively remove As (V) ions of H2AsO4- and HAsO42- through anion exchange reaction. The removal efficiency of MF membrane process combined with chemical sludge adsorption increased to about 36%, compared to MF membrane alone. The strong shear force on the NF membrane surface produced by vibration on the VSEP causes the concentration polarization layer to thin through increased back transport velocity of particles. So, it can remove even dissolved constituents effectively. Therefore, As (V) ions such as H2AsO4- and HAsO42- can be removed. The concentration of As (V) ions decreased from 50 μg/L to below 10 μg/L and condensation factor in recirculating water increased up to 7 times by using NF membrane equipped with VSEP.

scholarly journals Co-Occurrence of Regulated and Emerging Mycotoxins in Corn Silage: Relationships with Fermentation Quality and Bacterial Communities

Toxins ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 232
Author(s):  
Antonio Gallo ◽  
Francesca Ghilardelli ◽  
Alberto Stanislao Atzori ◽  
Severino Zara ◽  
Barbara Novak ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Bacterial Communities ◽  
Dry Matter ◽  
Kojic Acid ◽  
Corn Silage ◽  
Fungal Metabolites ◽  
Fusarium Mycotoxins ◽  
Low Concentrations ◽  
Fermentation Quality ◽  
Low Levels

Sixty-four corn silages were characterized for chemicals, bacterial community, and concentrations of several fungal metabolites. Silages were grouped in five clusters, based on detected mycotoxins, and they were characterized for being contaminated by (1) low levels of Aspergillus- and Penicillium-mycotoxins; (2) low levels of fumonisins and other Fusarium-mycotoxins; (3) high levels of Aspergillus-mycotoxins; (4) high levels of non-regulated Fusarium-mycotoxins; (5) high levels of fumonisins and their metabolites. Altersetin was detected in clusters 1, 3, and 5. Rugulusovin or brevianamide F were detected in several samples, with the highest concentration in cluster 3. Emodin was detected in more than 50.0% of samples of clusters 1, 3 and 5, respectively. Kojic acid occurred mainly in clusters 1 and 2 at very low concentrations. Regarding Fusarium mycotoxins, high occurrences were observed for FB3, FB4, FA1, whereas the average concentrations of FB6 and FA2 were lower than 12.4 µg/kg dry matter. Emerging Fusarium-produced mycotoxins, such as siccanol, moniliformin, equisetin, epiequisetin and bikaverin were detected in the majority of analyzed corn silages. Pestalotin, oxaline, phenopirrozin and questiomycin A were detected at high incidences. Concluding, this work highlighted that corn silages could be contaminated by a high number of regulated and emerging mycotoxins.

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