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1.
Screening for cystic fibrosis: feasibility of molecular genetic analysis of dried blood specimens 总被引:1,自引:0,他引:1
W K Seltzer F Accurso M Z Fall A J VanRiper M Descartes Y Huang E R McCabe 《Biochemical medicine and metabolic biology》1991,46(1):105-109
Direct genotypic analysis for the common Caucasian cystic fibrosis mutation (delta F508) was performed using dried blood specimens in a filter paper matrix (neonatal screening blotter). DNA was obtained from dried and liquid blood samples, amplified, and analyzed by polyacrylamide gel electrophoresis. Additionally, intact 4-mm-diameter punched discs from blotters containing dried blood specimen were used in the amplification reactions and analyzed by electrophoresis. The results agreed completely between these three sample types, demonstrating the feasibility of molecular genetic confirmation of the delta F508 mutation from the neonatal screening blotter among those with positive CF screening results. Such a program could reduce follow-up testing by at least 50% in a CF newborn screening program and would identify immediately those families who would benefit from carrier detection for the delta F508 allele. 相似文献
2.
DNA microextraction from dried blood spots on filter paper blotters: potential applications to newborn screening 总被引:18,自引:1,他引:17
Edward R. B. McCabe Shu-Zhen Huang William K. Seltzer Martha L. Law 《Human genetics》1987,75(3):213-216
Summary Microextraction of DNA from dried blood specimens would ease specimen transport to centralized laboratory facilities for recombinant DNA diagnosis in the same manner as use of dried blood spots allowed the broad application of screening tests to newborn populations. A method is described which reproducibly yields 0.5g DNA from the dried equivalent of 50l whole blood. Though DNA yields decreased with storage of dried specimens at room temperature, good-quality DNA was still obtained. Sufficient DNA was routinely obtained for Southern blot analysis using repetitive and unique sequences. This microextraction procedure will allow immediate application of molecular genetic technology to direct newborn screening follow-up of disorders amenable to DNA diagnosis, such as sickle cell anemia, and may eventually permit primary DNA screening for specific mutations. 相似文献
3.
Summary Amplification of DNA recovered from a dried blood spot was used to genotype individuals with sickle cell disease, sickle cell carriers, and controls. A single 200-l blood spot applied to a filter paper provides sufficient material for more than 20 genetic analyses. In addition, the stability of the DNA is such that adequate material for amplification can be isolated from dried blood spots up to a year following collection. The DNA analysis methods described in this study could be applied to large-scale screening of newborns for genetic disorders. 相似文献
4.
The present study describes a rapid and sensitive high-performance liquid chromatography (HPLC) method for the detection of
human globin chains in blood. The method involves direct injection of globin chains which prepared by a standard method onto
a micro bondapack C18 reversed-phase column (7.8 mm I.D.) with UV detection at 280 nm. The detection limit of hemoglobin (Hb)
was 0.1 μg, which is equivalent to about 1 ml of fresh whole blood. We report here the rapid procedure for globin chain analysis.
The present method will be useful for the determination of globin chain analysis in clinical laboratories, as well as in thalassemia
and sickle cell disease patients. 相似文献
5.
Lorey F Cunningham G Vichinsky EP Lubin BH Witkowska HE Matsunaga A Azimi M Sherwin J Eastman J Farina F Waye JS Chui DH 《Genetic testing》2001,5(2):93-100
Newborn screening is an accepted public health measure to ensure that appropriate health care is provided in a timely manner to infants with hereditary/metabolic disorders. Alpha-thalassemia is a common hemoglobin (Hb) disorder, and causes Hb H (beta4) disease, and usually fatal homozygous alpha(0)-thalassemia, also known as Hb Bart's (gamma4) hydrops fetalis syndrome. In 1996, the State of California began to investigate the feasibility of universal newborn screening for Hb H disease. Initial screening was done on blood samples obtained by heel pricks from newborns, and stored as dried blood spots on filter paper. Hb Bart's levels were measured as fast-moving Hb by automated high-performance liquid chromatography (HPLC) identical to that currently used in newborn screening for sickle cell disease. Subsequent confirmation of Hb H disease was done by DNA-based diagnostics for alpha-globin genotyping. A criterion of 25% or more Hb Bart's as determined by HPLC detects most, if not all cases of Hb H disease, and few cases of alpha-thalassemia trait. From January, 1998, through June, 2000, 89 newborns were found to have Hb H disease. The overall prevalence for Hb H disease among all newborns in California is approximately 1 per 15,000. Implementation of this program to existing newborn hemoglobinopathy screening in populations with significant proportions of southeast Asians is recommended. The correct diagnosis would allow affected infants to be properly cared for, and would also raise awareness for the prevention of homozygous alpha(0)-thalassemia or Hb Bart's hydrops fetalis syndrome. 相似文献
6.
A rapid method for detection of Y-chromosomal DNA from dried blood specimens by the polymerase chain reaction 总被引:8,自引:2,他引:6
Summary The alphoid satellite family is the only repetitive DNA family showing chromosome specificity. We have developed a simple, rapid, and reliable test for sex diagnosis based on detection of these sequences in undigested genomic DNA using the polymerase chain reaction. In our test, dried blood specimens were the source of DNA. When female DNA was used as a template for the reaction, only the expected 130-bp X-chromosome-specific fragment was detected, while with male DNA both the expected 170-bp Y-chromosome-specific and X-chromosome-specific fragments were detected. The Y-chromosome-specific fragment was further characterized by restriction enzyme analysis. The Y fragment was detectable when DNA obtained from an equivalent of 10 l of spotted blood was used in the reaction, whereas detection of the X fragment was possible with DNA from an equivalent of 5 l of blood. Our test may find various applications in newborn screening and in forensic science. 相似文献
7.
Romy Brauer Alexander Benedikt Leichtle Georg Martin Fiedler Joachim Thiery Uta Ceglarek 《Metabolomics : Official journal of the Metabolomic Society》2011,7(3):344-352
Quantitative metabolite profiling in biological samples has the potential to reflect physiological status and to identify
disease associated disturbances in metabolic networks. However, this approach is hampered by a wide range of preanalytical
variables. Hence, the aim of our study was to develop a standardized preanalytical protocol for metabolite profiling of amino
acids and acylcarnitines in human blood. Amino acids and acylcarnitines were simultaneous analyzed after butylation of 3 μL
dried blood or 10 μL whole blood, serum and anticoagulated plasma using electrospray tandem-mass spectrometry. The influence
of exogenous and endogenous preanalytical variables was investigated in healthy volunteers. Different sampling materials and
anticoagulants for blood taking were investigated. Concentrations of long-chain acylcarnitines were 5-fold higher in EDTA-whole
blood or dried whole blood compared to serum and anticoagulated plasma. Significant differences in amino acid concentrations
were found for capillary versus venous blood taking. Fasting for 8 h before specimen collection minimized the nutritional
influence. Physical activity significantly alters amino acid and short chain acylcarnitine concentrations. As a result of
our preanalytical investigation we developed a pre-treatment protocol based on EDTA whole blood dried on filter paper to reduce
the preanalytical variability and facilitate reproducible quantitative metabolite profiling in clinical trials. 相似文献
8.
Banfalvi G Ujvarosi K Trencsenyi G Somogyi C Nagy G Basnakian A 《Apoptosis : an international journal on programmed cell death》2007,12(7):1219-1228
Murine pre-B-cells grown in the presence of lower (1 μM) or higher (5 μM) concentration of cadmium chloride were separated
into 13 fractions by centrifugal elutriation. The rate of DNA synthesis after cadmium treatment determined in permeable cells
was dependent on cell culture density during cadmium treatment. Cell cycle analysis revealed a shift in the profile of DNA
synthesis from replicative to repair DNA synthesis upon cadmium treatment. The study of the relationship between cell culture
density and cell diameter at lower and higher cell densities in the presence of 1 μM cadmium chloride concentration showed
that a. at 5×105 cell/ml or lower densities cells were shrinking indicating apoptotic changes, b. at higher cell culture densities the average
cell size increased, c. the treatment of cells with low CdCl2 concentration (1 μM) at higher cell culture density (>5×105 cell/ml) did not change significantly the average cell diameter. At 5 μM cadmium concentration and higher cell culture densities
(>5×105 cell/ml) the average cell size decreased in each elutriated fraction. Most significant inhibition of cell growth took place
in early S phase (2.0–2.5 C value). Apoptotic chromatin changes in chromatin structure after cadmium treatment were seen as
large extensive disruptions, holes in the nuclear membrane and stickiness of incompletely folded chromosomes. 相似文献
9.
Atomic force microscopy (AFM) was used to image celery (Apium graveolens L.) parenchyma cell walls in situ. Cellulose microfibrils could clearly be distinguished in topographic images of the cell
wall. The microfibrils of the hydrated walls appeared smaller, more uniformly distributed, and less enmeshed than those of
dried peels. In material that was kept hydrated at all times and imaged under water, the microfibril diameter was mainly in
the range 6–25 nm. The cellulose microfibril diameters were highly dependent on the water content of the specimen. As the
water content was decreased, by mixing ethanol with the bathing solution, the microfibril diameters increased. Upon complete
dehydration of the specimen we observed a significant increase in microfibril diameter. The procedure used to dehydrate the
parenchyma cells also influenced the size of cellulose microfibrils with freeze-dried material having larger diameters than
air-dried material.
Received: 16 November 1999 / Accepted: 7 March 2000 相似文献
10.
This study was undertaken to develop a quantitative polymerase chain reaction assay that would improve the utility of PCR
for detecting Haplosporidium nelsoni (MSX), a serious parasite of the eastern oyster Crassostrea virginica. A competitive PCR sequence was generated from the H. nelsoni small subunit ribosomal DNA fragment, originally described by Stokes and colleagues, that was amplified by the same PCR primers
and had similar amplification performance. Assays performed using competitor dilutions ranging from 0.05 to 500 pg/μl DNA
were used to test oyster samples designated using histological techniques as having ``light' or ``heavy' MSX infections.
Visual diagnoses were confirmed equally well with three methods: densitometry of ethidium-bromide-stained agarose, densitometry
of SYBRGreen-stained polyacrylamide gels, and analysis by GeneScan 3.0 of fluorescent products detected in ultrathin gels.
Oysters diagnosed as negative for MSX tested as negative or light by PCR. Oysters with light MSX infections generally had
less than 5 pg/μl infectious DNA. Oysters with heavy infections generally corresponded to 5 pg/μl or greater competitor dilutions.
Received September 3, 1999; accepted March 3, 2000. 相似文献
11.
Increased sensitivity of malaria detection by nested polymerase chain reaction using simple sampling and DNA extraction 总被引:1,自引:0,他引:1
Janet Cox-Singh Suraya Mahayet Mohd Shukri Abdullah Balbir Singh 《International journal for parasitology》1997,27(12):1575-1577
Malaria remains a disease of underdeveloped and remote regions of the world. The application of polymerase chain reaction (PCR) technology to malaria epidemiology has the potential for increasing our knowledge and understanding of this disease. In order to study malaria in all geographical locations it is important that specimen collection and DNA extraction for PCR be kept simple. Here we report a method for extracting DNA from dried blood spots on filter paper which is capable of detecting one Plasmodium falciparum and two Plasmodium vivax parasites/μl of whole blood by nested PCR without compromising the simplicity of specimen collection or DNA extraction. 相似文献
12.
Tonya D. Mitchell Ajmer S. Bhagsari Peggy Ozias-Akins Sarwan K. Dhir 《In vitro cellular & developmental biology. Plant》1998,34(4):319-324
Summary Transient expression of the β-glucuronidase (GUS) gene has been studied in leaf-derived embryogenic callus of sweetpotatoIpomoea batatas L. (Lam.) by electroporation. The influence of several factors including electric field strength, buffer composition, time
course of transientGUS gene expression, DNA concentration, enzyme, and polyethylene glycol (PEG) treatment was examined onGUS gene expression (number of blue spots). MaximumGUS gene expression (an average of 90 blue spots/fifty mg fresh weight callus tissue) was observed after 48 h when callus pieces
were preincubated with electroporation (EPR) buffer for 1 h, followed by electroporation with a single electric pulse of 500
V/cm discharged from a 960-μF capacitor in the presence of 20 μg DNA/ml and 8.3 μl NaCl (3M). Changing the electroporation buffer conductivity (by varying the buffer composition with low-high salt concentrations),
had only slight effect on the number of blue spots. Similarly, the time course study ofGUS gene expression revealed that GUS activity could be detected 12 h after electroporation with a maximum activity after 72
h (112 blue spots). Increasing the amount of DNA from 5 to 50 μg/ml in the EPR buffer had a slight effect on the expression
frequency (from 20–110 blue spots, and 112 blue spots with 20 μg/ml). The number of blue spots was increased by enzymatic
wounding of callus pieces for 10 min and by addition of 200 μl PEG 4000 (15%) before electroporation. These results suggest
that intact cell electroporation can be used for producing transgenic sweetpotato tissue. 相似文献
13.
This study examined how the availability of inorganic nitrogen (N) modified the anatomical characteristics of white spruce
(Picea glauca (Moench) Voss) roots related to their hydraulic properties. Seedlings were grown for one growing season in 4
L capacity pots filled with sand under one of three N levels: low (10 ppm), medium (50 ppm) and high (125 ppm). First order
lateral roots with intact tips were sampled from dormant seedlings in October. Root segments were collected from 4, 10, and
14 cm distances above the root tip for fixation and sectioning and for maceration. Additional specimens were collected from
the 4 and 14 cm distances for maceration and scanning electron microscopy of xylem pits. Root diameter and surface area occupied
by the xylem in root cross sections increased basipetally in all treatments but exceptions were found. Higher N-levels significantly
increased root diameter and surface area occupied by the xylem. In the two higher N treatments secondary root development
was more advanced near the root tip than in the low N treatment. There was a strong positive correlation between root diameter
and cross-sectional root area occupied by the xylem (30–50% of the root cross section) but not in portions with little secondary
development. Non-conducting space within the xylem occupied 10–13% of its cross-sectional surface. Tracheids of the primary
xylem were larger, had larger lumens but thinner cell walls than those of the secondary xylem. Low N treatment seedling tracheids
had smaller total cross-sectional area, less lumen, and less cell wall surface area than the two other N treatments. Tracheid
diameter means were between 19–20 μm in the high and medium N treatments, and 15.2 μm in the low N treatment. The range was
4.5–51.3 μm. Tracheid length was not significantly affected by N. The average tracheid was about 1000 μm long, and the range
was 110–3530 μm. Pit-border diameters ranged between 4.1–20.6 μm (average 10–11 μm) and were not affected by the N treatment.
Pit aperture diameters were within 0.62–10.2 μm range (average between 3–4 μm) and were also not significantly affected by
the N treatment, although tracheids from the medium N-treatment roots tended to have larger apertures. The pit border diameter
equals that of the margo while the aperture size should be similar to that of the torus of the pit membrane. If the capacity
for axial water transport in spruce roots is affected by N, it would be by its impact on conduit diameter and, possibly on
the pit-membrane pore sizes but not by changes to conduit length and to the size of the pit membrane surface area.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
14.
Véronique Breguet Raphaël Gugerli Urs von Stockar Ian William Marison 《Cytotechnology》2007,53(1-3):81-93
Microencapsulation offers a unique potential for high cell density, high productivity mammalian cell cultures. However, for
successful exploitation there is the need for microcapsules of defined size, properties and mechanical stability. Four types
of alginate/poly-l-Lysine microcapsules, containing recombinant CHO cells, have been investigated: (a) 800 μm liquid core microcapsules, (b)
500 μm liquid core microcapsules, (c) 880 μm liquid core microcapsules with a double PLL membrane and (d) 740 μm semi-liquid
core microcapsules. With encapsulated cells a reduced growth rate was observed, however this was accompanied by a 2–3 fold
higher specific production rate of the recombinant protein. Interestingly, the maximal intracapsular cell concentration was
only 8.7 × 107 cell mL-1, corresponding to a colonization of 20% of the microcapsule volume. The low level of colonization is unlikely to be due to
diffusional limitations since reduction of microcapsule size had no effect. Measurement of cell leaching and mechanical properties
showed that liquid core microcapsules are not suitable for continuous long-term cultures (>1 month). By contrast semi-liquid
core microcapsules were stable over long periods with a constant level of cell colonization (ϕ = 3%). This indicates that
the alginate in the core plays a predominant role in determining the level of microcapsule colonization. This was confirmed
by experiments showing reduced growth rates of batch suspension cultures of CHO cells in medium containing dissolved alginate.
Removal of this alginate would therefore be expected to increase microcapsule colonization. 相似文献
15.
Ruyi Xu Ping Ye Leiming Luo Hongmei Wu Jin Dong Xinxin Deng 《Molecular biotechnology》2010,46(3):258-264
Rapid purification of DNA from samples of highly clotted blood is a challenging problem due to the difficulty in recovering
and dispersing blood clots. We developed a new method for discarding the serum-separator gel and rapidly dispersing the blood
clots. A special disposable tip was inserted into the serum-separator gel so that the serum-separator gel could be discarded.
The blood clot obtained was dispersed into small pieces through a copper mesh (pore size, 250 μm) in a special dispersing
instrument by centrifugation. After lysis of red blood cells and white blood cells, genomic DNA was concentrated and desalted
by isopropanol precipitation. The mean yield of DNA purified from a 0.3-ml blood clot was 22.70 μg in 173 samples of clotted
blood cryopreserved for 1 month, and 19.02 μg in 1,372 samples of clotted blood cryopreserved for >6 months. DNA samples were
successfully performed through polymerase chain reaction, real time polymerase chain reaction, and melt curve analysis. Their
quality was comparable with that purified directly from EDTA-anticoagulated blood. The new method overcomes the difficulties
in recovering and dispersing blood clots, allowing efficient purification of DNA from samples of highly clotted blood. 相似文献
16.
The collection efficiency and sample retention of a batch-type wetted wall bioaerosol sampling cyclone (BWWC) were experimentally
characterized. The BWWC is designed to sample air at 400 l/min and concentrate the particles into 12 ml of water. Aerosol
is transported into a cylindrically-shaped axial flow cyclone through a tangential slot and the particles are impacted on
the inner wall, which is wetted by air shear acting on a liquid pool at the base of the cyclone. The retention of collected
particles and the aerosol collection efficiency of the BWWC were evaluated with polystyrene latex beads (PSL), sodium fluorescein/oleic
acid droplets, and Bacillus atrophaeus (aka BG) spores. The retention of particles was determined by adding hydrosol directly into the device, running the BWWC
for a pre-set period of time, and then determining the amount of particulate matter recovered relative to the initial amount.
For 1-μm diameter PSL, 90% of the particles were recoverable from the cyclone body immediately after their introduction; however,
only 10% were retained in the collection liquid after 8 h of operation. The aerosol sampling efficiency was determined by
comparing the amount of particulate matter collected in the liquid with that collected by a reference filter. The collection
efficiency was 50–60% for 1- and 3-μm polystyrene (PSL) particles, and 1.5% for 10-μm oleic acid particles. The efficiency
for 3-μm oleic acid droplets was 35%. Explanations are provided for the difference between liquid and solid particle behavior,
and for the low efficiency for the large liquid particles. The collection efficiency for single spore BG was slightly lower
than that for 1-μm PSL. 相似文献
17.
Tetraploid plants were produced from leaf explants of diploid Populus pseudo-simonii by treating the leaves with colchicine. Leaf explants were cultured on MS basal medium containing 1.78 μM BA and 1.08 μM
NAA for 0, 6 and 12 days, and then transferred to the same MS liquid medium with colchicine at concentrations of 25, 50 and
75 μM for 1, 2 and 3 days. The highest efficiency of tetraploid induction was 14.6% by treating leaf explants that were pre-cultured
for 6 days and then cultured in liquid MS with 50 μM colchicine for 3 days. Flow cytometric analysis was used to screen the
tetraploids out from the regenerated plants and chromosome number counting was employed to confirm the polyploidy level. Size
and frequency of leaf stomata between diploid and tetraploid plants were demonstrated to have significant differences. 相似文献
18.
The inhibitory effect of silibinin on ochratoxin A (OTA)-mediated apoptosis on primary rat hepatocytes was investigated. Rat
hepatocytes were prepared by two different methods: the classical enzymatic digestion method by collagenase perfusion and
a new EDTA-perfusion method. The EDTA-perfusion method yielded hepatocytes, which were stably cultivated without DNA fragmentation
for up to 96 h, whereas the collagenase-prepared hepatocytes showed apoptosis events as early as from the start of preparation
even in the absence of OTA. Treatment with 12.5 μmol/l OTA of cultured hepatocytes prepared under ETDA perfusion developed
DNA-laddering after 24–36 h. Lipopolysaccharide (LPS) of 0.1 up to 12.5 μg/ml showed no apoptotic DNA-effects under these
conditions. A low concentration of 26 μmol/l silibinin given prior to OTA slightly prevented OTA-mediated DNA-laddering, whereas
a five times higher concentration of silibinin (130 μmol/l) completely inhibited OTA-mediated apoptosis. Under the same conditions,
caspase-3 activity in hepatocytes increased in a time-dependent manner under OTA exposure within 12–24 h but was blocked by
130 μmol/l silibinin. In contrast, LPS incubation for 12 and 24 h did not alter caspase-3 activity. To measure viability of
OTA-/LPS-treated hepatocytes, the MTT-test and Live/Dead kit were applied. The results demonstrated that the used OTA concentration
of 12.5 μmol/l only moderately decreased viability for up to 24 h but showed cytotoxic effects depending on longer incubation
times (≥36 h). In contrast, LPS up to 12.5 μg/ml exhibited no cytotoxic effects up to 48 h. In summary, our results showed
contrasting effects on apoptosis in primary rat hepatocytes by OTA (produces apoptosis) versus LPS (produces no apoptosis),
also depending on the method of hepatocyte preparation. Silibinin at 130 μmol/l showed significant hepatoprotective and antiapoptotic
effects against OTA-mediated cell damage on cultured rat hepatocytes. 相似文献
19.
A new giant Gram-negative non-cultivatable symbiotic endospore-forming bacterium was found in the gut of the European hamster.
This “Metabacterium” sp., provisionally named “Metabacterium criceti”, sp. n., has a length of approximately 20 μm and thickness of 4 μm. It forms 1 to 2 cylindrical endospores, approximately
9 μm long and 1.4 μm thick. TEM-micrographs show a cell wall structure characteristic of Gram-negative bacteria. Vegetative
cells are filled with granules 0.3 μm in diameter which resemble starch granules. The reproduction occurs with binary fission
and by formation of two endospores. Of thirteen biochemical components sought, four,i.e. glycogen, triacylglyceroles, peroxidase and alkaline phosphatase, were not found. Starch, acid mucosubstances, DNA, RNA,
lipids, proteins, adenosine triphosphatase and acid phosphatase were found in different patterns, depending on the developmental
stage of the bacterium. In the vegetative cell stage all these components, with the exception of starch, were found. In the
endospore-bearing cell stage, only the starch-like cell component granulose could be detected. In free endospores only DNA,
RNA and acid phosphatase were found. Some of the components,i.e. DNA, lipids, starch-like granulose, were linked to certain cell substructures, the distribution of others,viz. polysaccharides, RNA, adenosine triphosphatase and proteins was diffuse. The lipids, found only in vegetative cells, were
associated with the cell wall.
Presented in part during the19th Congress of the Czechoslovak Society for Microbiology, Košice (Slovakia) September 14–17, 1992.
An erratum to this article is available at . 相似文献
20.
Ivan Famelaer Harrie A. Verhoeven Paul Dijkhuis Kamisetti S. Ramulu 《Plant Cell, Tissue and Organ Culture》2007,90(2):169-179
The process of synchronization and micro-nuclei induction in a suspension culture of Beta vulgaris, was induced by the sequential treatment with the DNA-synthesis inhibitor aphidicolin (30 μM, 24 h) and the spindle-toxin
amiprophos-methyl (32 μM, 24 h). Mitotic arrest of divisions, spreading of G2-metaphase chromosomes, re-grouping of chromosomes,
formation of a nuclear cell wall around single and re-grouped chromosomes and restitution of nuclei with a doubled DNA content
was observed. The process of micro-nucleation was induced much less efficiently in Beta vulgaris than in Nicotiana plumbaginifolia. Cytological observations and monitoring of the process with flow cytometry and confocal laser scanning microscopy, was essential
to follow up the course of events and to monitor the development of an efficient procedure for micro-protoplast isolation.
Micro-nucleated protoplasts were fractioned by iso-osmotic Percoll gradient centrifugation to obtain heterogeneous micro-protoplast
populations with cytoplasts and micro-protoplasts of different size. An enriched fraction with small sub-diploid micro-protoplasts
was obtained with the equivalent DNA content of 1–4 chromosomes, as revealed by confocal laser scanning microscopy and flow
cytometry. Sub-diploid micro-protoplasts with DNA amounts equivalent to 1–4 chromosomes were predominantly observed in the
size classes of 1.8–10.2 μm at a frequency of 34.2–34.5%. The DNA measurements of micro-nuclei and micro-protoplasts, confirmed
the hypothesis that the process of micro-nucleation followed the same course of cellular events as observed in N. plumbaginifolia. The correlation between DNA content and size of micro-nuclei and micro-protoplasts was not linear and affected by the degree
of DNA condensation, total amount of DNA, and the presence of cytoplasm. 相似文献