Yield Of Genomic DNA Research Articles

AirDNA sampler: An efficient and simple device enabling high-yield, high-quality airborne environment DNA for metagenomic applications.

Analyzing temporal and spatial distributions of airborne particles of biological origins is vital for the assessment and monitoring of air quality, especially with regard to public health, environmental ecology, and atmospheric chemistry. However, the analysis is frequently impeded by the low levels of biomass in the air, especially with metagenomic DNA analysis to explore diversity and composition of living organisms and their components in the air. To obtain sufficient amounts of metagenomic DNA from bioaerosols, researchers usually need a long sampling time with an expensive high-volume air sampler. This work shows the utilization of an air sampling device containing an economical, high-volume portable ventilation fan in combination with customized multi-sheet filter holders to effectively obtain high yields of genomic DNA in a relatively short time. The device, named 'AirDNA' sampler, performed better than other commercial air samplers, including MD8 Airport and Coriolis compact air samplers. Using the AirDNA sampler, an average DNA yield of 40.49 ng (12.47-23.24 ng at 95% CI) was obtained in only 1 hour of air sampling with a 0.85 probability of obtaining ≥10 ng of genomic DNA. The genomic DNA obtained by the AirDNA system is of suitable quantity and quality to be further used for amplicon metabarcoding sequencing of 16S, 18S, and cytochrome c oxidase I (COI) regions, indicating that it can be used to detect various prokaryotes and eukaryotes. Our results showed the effectiveness of our AirDNA sampling apparatus with a simple setup and affordable devices to obtain metagenomic DNA for short-term or long-term spatiotemporal analysis. The technique is well suited for monitoring air in built environments, especially monitoring bioaerosols for health purposes and for fine-scale spatiotemporal environmental studies.

Quality Control of DNA Extracted from All-Cell Pellets After Cryopreservation for More Than 10 Years.

Background: Cryopreserved whole blood, all-cell pellets (ACPs), and buffy coats in biobanks are widely used to obtain DNA for genetic testing. However, there are few studies concerning the quality control of DNA extracted from them. Our research aimed to perform quality control of DNA extracted from ACPs after cryopreservation for >10 years. Materials and Methods: A total of 1377 ACP samples (separated from 3 mL of whole blood) were retrieved from our biobank, where they had been cryopreserved for 10-15 years. Chemagic STAR was used to extract the DNA. Absorbance at A260, A280, and A230 were measured by spectrophotometry, and integrity was analyzed by agarose gel electrophoresis. The quality thresholds for an Illumina Asian Screening Array (ASA) were yields greater than 0.5 μg, concentration of 25-150 ng/μL, A260/280 ratio of 1.6-2.1, and no degradation fragments in the electrophoresis gel. Results: The median yield of genomic DNA was 54.30 μg (interquartile range [IQR] 35.55-74.64). The median A260/280 and A260/230 ratios were 1.90 (IQR 1.87-1.94) and 1.98 (IQR 1.64-2.41), respectively. In total, 1377 samples (100%) had qualified yields, and 1366 samples (99.20%) had qualified integrity results. Finally, 1328 (96.44%) samples were used for ASA. Of the remaining samples, 34 needed to be repurified, 4 were obtained at an insufficient concentration, and 11 were unqualified for integrity. In addition, we analyzed the influence of hemolysis (90 samples) and clots (102 samples) on the quality of DNA samples. Hemolysis and clotting did not influence yield or integrity, but a significant difference was found in A260/230 compared to normal samples (p < 0.05). Furthermore, the samples (14 samples) with both hemolysis and clots had higher A260/280 (p < 0.05). Conclusion: ACP samples stored for >10 years at -80°C produced DNA with high quality for use in genetic analysis. Hemolysis and clots in the ACPs led to lower purity, but did not significantly affect yield or integrity.

Development of a Rapid and Low-Cost Method for the Extraction of Dermatophyte DNA.

Background:Polymerase chain reaction (PCR) is the most optimized method for the rapid detection and analysis of any environmental or clinically significant organism. While PCR amplification directly from samples has been shown effective for several bacteria and viruses, for filamentous fungus and yeast, extraction of genomic DNA is a must. The extraction of DNA from fungal cultures is often reported using user-friendly commercially available kits, which are designed to decrease the time, extensive manual work in extraction procedures but are often expensive. Dermatophytes pose an added drawback to efficient DNA extraction due to their poor recovery on culture media and slow growth rate.Aims and Objectives:In the present study, we developed and validated a method for effective genomic DNA extraction from dermatophytes.Materials and Methods:DNA yield from standard dermatophytes extracted from spore suspensions and mycelia mat by commercially available kits was compared. A modified method using lyticase buffer and phenol-chloroform extraction was developed. The yield obtained was compared with the existing methods (kit-based method and cetyl trimethyl ammonium bromide method). The yield and quality of the total genomic DNA were estimated spectrophotometrically and by successful PCR amplification of the ITS region. The results were validated using 21 clinical isolates from recalcitrant dermatophytosis.Results:Minimal fungal DNA was obtained from the spores compared to that obtained from mycelial mat. Commercially available kits yielded lower amounts of DNA compared to the CATB method. The modified method developed in this study yielded better quality and quantity of DNA.Conclusion:Of the three extraction methods evaluated, the developed method gave significantly higher total genomic DNA yield and better purity than the reference methods. In addition, the turnaround time for DNA extraction was reduced to half based on modifications in culture conditions.

Comparative account of DNA extraction protocols in some freshwater prawns of Genus Macrobrachium (Bate, 1868) (Family Palaemonidae) from Jammu waters for PCR based applications

Genetic variations among prawns act as an important tool to characterize and differentiate between the species. Molecular and phylogenetic analysis of shrimps and prawns like any other organism rely on high yields of pure and better quality genomic DNA. In this regard isolation of DNA is the first and basic step. In spite of the availability of many protocols of DNA extraction from animal tissues, it is difficult to ascertain that which one would provide desired results for prawn tissue. In the present study, three different techniques of DNA isolation i.e., salting out, phenol-chloroform and Qiagen DNA extraction kit were performed and compared for their yield. Cephalothoracic tissue and muscle tissue of pleopods were used for isolation. Tissue samples from fresh specimens as well as from alcohol preserved specimens were employed for extraction. The quantity (µg/ml) and quality of isolated DNA were determined by UV spectrophotometry and agarose gel electrophoresis. Results showed that Phenol-chloroform method with slight modifications obtained higher yield of genomic DNA as compared to other methods. The present work also revealed that among fresh specimens cephalotoracic tissue yielded high concentration DNA than muscle tissue. However, among alcohol preserved specimens, the concentration of DNA was higher in muscle tissue of pleopods. The high quality DNA was then subjected to randomly amplified polymorphic DNA (RAPD) and inter simple sequence repeats (ISSR) analysis. The DNAs produced clear, sharp and reproducible PCR (Polymerse chain reaction) product pattern.

MON-292 THE IDENTIFICATION OF POTENTIAL BIOMARKERS OF CHRONIC KIDNEY DISEASE IN INDIVIDUALS WITH DIABETES

To characterise the genomic DNA (gDNA) yield from urine and quality of derived methylation data generated from the widely used Illuminia Infinium MethylationEPIC (HM850K) platform and compare this with buffy coat samples.DNA methylation is the most widely studied epigenetic mark and variations in DNA methylation profile have been implicated in diabetes which affects approximately 415 million people worldwide. Previous studies have assessed DNAm in whole blood genomic DNA and saliva samples. The studies showing differential methylation in a number of genes linked with diabetic kidney disease. Urine however, has not previously been examined as a source of genomic DNA in this group of patients. QIAamp Viral RNA Mini Kit and QIAamp DNA micro kit were used to extract DNA from frozen and fresh urine samples as well as increasing volumes of fresh urine. Matched buffy coats to the frozen urine were also obtained and DNA was extracted from the buffy coats using the QIAamp DNA Mini Kit. Genomic DNA of greater concentration than 20μg/ml were used for methylation analysis using the HM850K array. Irrespective of extraction technique or the use of fresh versus frozen urine samples, limited genomic DNA was obtained using a starting sample volume of 5ml (0±0.86μg/mL). In order to optimize the yield, we increased starting volumes to 50ml fresh urine, which yielded only 0±9.66μg/mL A different kit, QIAamp DNA Micro Kit, was trialled in six fresh urine samples and ten frozen urine samples with inadequate DNA yields from 0±17.7μg/mL and 0±1.6μg/mL respectively. Sufficient genomic DNA was obtained from only 4 of the initial 41 frozen urine samples (10%) for DNA methylation profiling. In comparison, all four buffy coat samples (100%) provided sufficient genomic DNA. High quality data can be obtained provided a sufficient yield of genomic DNA is isolated.Despite optimizing various extraction methodologies, the modest amount of genomic DNA derived from urine, may limit the generalisability of this approach for the identification of DNA methylation biomarkers of chronic diabetic kidney disease.

Single cell genomics yields a wide diversity of small planktonic protists across major ocean ecosystems

Marine planktonic protists are critical components of ocean ecosystems and are highly diverse. Molecular sequencing methods are being used to describe this diversity and reveal new associations and metabolisms that are important to how these ecosystems function. We describe here the use of the single cell genomics approach to sample and interrogate the diversity of the smaller (pico- and nano-sized) protists from a range of oceanic samples. We created over 900 single amplified genomes (SAGs) from 8 Tara Ocean samples across the Indian Ocean and the Mediterranean Sea. We show that flow cytometric sorting of single cells effectively distinguishes plastidic and aplastidic cell types that agree with our understanding of protist phylogeny. Yields of genomic DNA with PCR-identifiable 18S rRNA gene sequence from single cells was low (15% of aplastidic cell sorts, and 7% of plastidic sorts) and tests with alternate primers and comparisons to metabarcoding did not reveal phylogenetic bias in the major protist groups. There was little evidence of significant bias against or in favor of any phylogenetic group expected or known to be present. The four open ocean stations in the Indian Ocean had similar communities, despite ranging from 14°N to 20°S latitude, and they differed from the Mediterranean station. Single cell genomics of protists suggests that the taxonomic diversity of the dominant taxa found in only several hundreds of microliters of surface seawater is similar to that found in molecular surveys where liters of sample are filtered.

Genotyping of Single Nucleotide Polymorphisms Using Allele-Specific qPCR Producing Amplicons of Small Sizes Directly from Crude Serum Isolated from Capillary Blood by a Hand-Powered Paper Centrifuge

The cell-free genomic DNA (gDNA) concentration in serum ranges from 1500 to 7500 copies/mL within 2 h after phlebotomy (6–24 times the concentration observed in plasma). Here, we aimed to evaluate the gDNA size distribution in serum with time after coagulation and to test if crude serum can be directly used as a source of gDNA for qPCR. Next, we investigated if single nucleotide polymorphisms (SNPs) could be genotyped directly from the crude serum isolated from capillary blood using a hand-powered paper centrifuge. All tested PCR targets (65, 100, 202 and 688 base pairs) could be successfully amplified from DNA extracted from serum, irrespective of their amplicon size. The observed qPCR quantitation cycles suggested that the genomic DNA yield increased in serum with incubation at room temperature. Additionally, only 65 and 101 base pair qPCR targets could be amplified from crude serum soon after the coagulation. Incubation for 4 days at room temperature was necessary for the amplification of PCR targets of 202 base pairs. The 688 base pair qPCR target could not be amplified from serum directly. Lastly, serum was successfully separated from capillary blood using the proposed paper centrifuge and the genotypes were assigned by testing the crude serum using allele-specific qPCR, producing small amplicon sizes in complete agreement with the genotypes assigned by testing the DNA extracted from whole blood. The serum can be used directly as the template in qPCR for SNP genotyping, especially if small amplicon sizes are applied. This shortcut in the SNP genotyping process could further molecular point-of-care diagnostics due to elimination of the DNA extraction step.

DNA methylation profiling of genomic DNA isolated from urine in diabetic chronic kidney disease: A pilot study.

AimTo characterise the genomic DNA (gDNA) yield from urine and quality of derived methylation data generated from the widely used Illuminia Infinium MethylationEPIC (HM850K) platform and compare this with buffy coat samples.BackgroundDNA methylation is the most widely studied epigenetic mark and variations in DNA methylation profile have been implicated in diabetes which affects approximately 415 million people worldwide.MethodsQIAamp Viral RNA Mini Kit and QIAamp DNA micro kit were used to extract DNA from frozen and fresh urine samples as well as increasing volumes of fresh urine. Matched buffy coats to the frozen urine were also obtained and DNA was extracted from the buffy coats using the QIAamp DNA Mini Kit. Genomic DNA of greater concentration than 20μg/ml were used for methylation analysis using the HM850K array.ResultsIrrespective of extraction technique or the use of fresh versus frozen urine samples, limited genomic DNA was obtained using a starting sample volume of 5ml (0–0.86μg/mL). In order to optimize the yield, we increased starting volumes to 50ml fresh urine, which yielded only 0–9.66μg/mL A different kit, QIAamp DNA Micro Kit, was trialled in six fresh urine samples and ten frozen urine samples with inadequate DNA yields from 0–17.7μg/mL and 0–1.6μg/mL respectively. Sufficient genomic DNA was obtained from only 4 of the initial 41 frozen urine samples (10%) for DNA methylation profiling. In comparison, all four buffy coat samples (100%) provided sufficient genomic DNA.ConclusionHigh quality data can be obtained provided a sufficient yield of genomic DNA is isolated. Despite optimizing various extraction methodologies, the modest amount of genomic DNA derived from urine, may limit the generalisability of this approach for the identification of DNA methylation biomarkers of chronic diabetic kidney disease.

The Integrity and Yield of Genomic DNA Isolated from Whole Blood Following Long-Term Storage at -30°C.

Long-term storage of whole blood can affect the integrity of DNA if it is not done under optimal conditions. The aim of this study was to determine whether long-term storage (2-19 years) of whole blood samples at -30°C had a negative effect on the quality or quantity of genomic DNA that could be recovered at extraction. Genomic DNA was isolated from 2758 whole blood samples collected in 4 mL EDTA vacutainers from 1997 to 2012. DNA was extracted using the Qiagen® FlexiGene® DNA kit. The average storage duration at -30°C was 12 years. The quality and quantity of the isolated DNA were assessed using spectrophotometry (NanoDrop™), a fluorometric assay for double-stranded DNA (Qubit™), and agarose gel electrophoresis. The mean DNA yield per sample was found to be 114 μg from whole blood volumes that ranged from 0.5 to 4 mL. The mean A260/280 ratio and median A260/280 ratios were both 1.8. No correlation was found between the duration of storage and the total yield or the quality of DNA extracted. These data suggest that high-quality DNA can be extracted from whole blood samples that are stored at -30°C for up to 19 years.

Comparative analysis and innovation of a simple and rapid method for high-quality RNA and DNA extraction of kiwifruit

RNA and DNA extraction is a requirement for the study of gene expression and has an increasingly important role in genetic studies of all fleshy fruits. RNA and DNA extraction is difficult in kiwifruit due to the significant amount of polysaccharides and polyphenols compounds. So far, no commercial kit has been developed specifically for high-quality RNA and DNA extraction in kiwifruit and the common protocols for RNA extraction have poor yields. This study developed a new protocol for high quality RNA extraction in Actinidia deliciosa. According to the results, the average yield of RNA extraction of fruit and leaf of A. deliciosa was ~2180.7?ng/µl (~545.175?µg/g?FW) and ~3424.9?ng/µl (~856.225?µg/g?FW), respectively with A260/A280 between 1.95 to 2.07 and A260/A230 higher than 2 indicating high RNA purity. While the averages yield of RNA extraction using previous methods from kiwifruit and leaf was 23?µg/g?FW and 527?µg/g?FW, respectively. Also, the average yields of genomic DNA from kiwifruit ranged from 52 to 98?ng/µl with A260/A230 between 0.60 to 1.64 and A260/A280 between 1.40 to 1.48. To our knowledge, this is the first report of a highly efficient and rapid method of RNA and DNA extraction in kiwifruit which can be used for a broad spectrum of the all fleshy fruits.

Profiling soil microbial communities with next-generation sequencing: the influence of DNA kit selection and technician technical expertise.

Structure and diversity of microbial communities are an important research topic in biology, since microbes play essential roles in the ecology of various environments. Different DNA isolation protocols can lead to data bias and can affect results of next-generation sequencing. To evaluate the impact of protocols for DNA isolation from soil samples and also the influence of individual handling of samples, we compared results obtained by two researchers (R and T) using two different DNA extraction kits: (1) MO BIO PowerSoil® DNA Isolation kit (MO_R and MO_T) and (2) NucleoSpin® Soil kit (MN_R and MN_T). Samples were collected from six different sites on Okinawa Island, Japan. For all sites, differences in the results of microbial composition analyses (bacteria, archaea, fungi, and other eukaryotes), obtained by the two researchers using the two kits, were analyzed. For both researchers, the MN kit gave significantly higher yields of genomic DNA at all sites compared to the MO kit (ANOVA; P < 0.006). In addition, operational taxonomic units for some phyla and classes were missed in some cases: Micrarchaea were detected only in the MN_T and MO_R analyses; the bacterial phylum Armatimonadetes was detected only in MO_R and MO_T; and WIM5 of the phylum Amoebozoa of eukaryotes was found only in the MO_T analysis. Our results suggest the possibility of handling bias; therefore, it is crucial that replicated DNA extraction be performed by at least two technicians for thorough microbial analyses and to obtain accurate estimates of microbial diversity.

Evaluation of the impact of six different DNA extraction methods for the representation of the microbial community associated with human chronic wound infections using a gel-based DNA profiling method

Infected chronic wounds are polymicrobial in nature which include a diverse group of aerobic and anaerobic microorganisms. Majority of these communal microorganisms are difficult to grow in vitro. DNA fingerprinting methods such as polymerase chain reaction-denaturation gradient gel electrophoresis (PCR-DGGE) facilitate the microbial profiling of complex ecosystems including infected chronic wounds. Six different DNA extraction methods were compared for profiling of the microbial community associated with chronic wound infections using PCR-DGGE. Tissue debris obtained from chronic wound ulcers of ten patients were used for DNA extraction. Total nucleic acid was extracted from each specimen using six DNA extraction methods. The yield, purity and quality of DNA was measured and used for PCR amplification targeting V2–V3 region of eubacterial 16S rRNA gene. QIAGEN DNeasy Blood and Tissue Kit (K method) produced good quality genomic DNA compared to the other five DNA extraction methods and gave a broad diversity of bacterial communities in chronic wounds. Among the five conventional methods, bead beater/phenol–chloroform based DNA extraction method with STES buffer (BP1 method) gave a yield of DNA with a high purity and resulted in a higher DGGE band diversity. Although DNA extraction using heat and NaOH had the lowest purity, DGGE revealed a higher bacterial diversity. The findings suggest that the quality and the yield of genomic DNA are influenced by the DNA extraction protocol, thus a method should be carefully selected in profiling a complex microbial community.

Modified Method of High Quality Genomic DNA Extraction from Mungbean [Vigna radiata(L.) Wilczek] Suitable for PCR Based Amplification

Objectives: Mungbean is one among the foremost necessary pulse crops. It is necessary to extract good quality genomic DNA for molecular work in plant science. Hence, present study intended to establish a robust and cost effectively genomic DNA extraction method for mungbean. Methods/Statistical Analysis: The prevailing CTAB method for genomic DNA extraction from plant was altered by avoiding usage of liquid nitrogen or lyophilization. Genomic DNA of plant was extracted from leaves of seven mungbean genotypes by grinding in pre-heated CTAB extraction buffer. Increased concentration of CTAB, PVP, β-mercaptoethanol, use of RNase treatment and repetition of purification step with C:I after P:C:I treatment will suppress the interference of the contaminants. The effectiveness of DNA extraction protocol for PCR amplification was evaluated using SSR and RAPD markers. Findings: The quality of DNA was assured by the presence of intact bands of genomic DNA separated on 0.8% agarose gel. The yield of genomic DNA ranged from 871.6 to 1143.2 ng/μL with an average of 979.14 ng/μL. When measured spectrophotometrically, the A 260 /A 280 ratio was in the range of 1.78 to 1.86, with an average of 1.82, indicating very low levels of contamination such as polysaccharides, phenolics and protein. The results of PCR amplification using SSR and RAPD markers indicated that the DNA extracted by this modified protocol was of decent quality and appropriate for various molecular studies. This protocol is suitable for underdeveloped countries, where resources for high throughput DNA isolation are not or less available. Application/Improvement: An effective, simple and cost-effective protocol for genomic DNA extraction with good yield as well as high purity was developed for mungbean which can be applied to other pulse crops also.

GC Preps: Fast and Easy Extraction of Stable Yeast Genomic DNA.

Existing yeast genomic DNA extraction methods are not ideally suited to extensive screening of colonies by PCR, due to being too lengthy, too laborious or yielding poor quality DNA and inconsistent results. We developed the GC prep method as a solution to this problem. Yeast cells from colonies or liquid cultures are lysed by vortex mixing with glass beads and then boiled in the presence of a metal chelating resin. In around 12 minutes, multiple samples can be processed to extract high yields of genomic DNA. These preparations perform as effectively in PCR screening as DNA purified by organic solvent methods, are stable for up to 1 year at room temperature and can be used as the template for PCR amplification of fragments of at least 8 kb.

Genomic DNA Isolation from Maize (Zea mays) Leaves Using a Simple, High-Throughput Protocol.

A simple, robust, inexpensive, high-throughput method for isolating genomic DNA from maize (Zea mays) leaf tissues is described. The DNA obtained using this extraction protocol is suitable for polymerase chain reaction (PCR) genotyping, which can be employed for the identification of alleles in diverse genetic and breeding approaches, such as marker-assisted selection, genetic fine mapping, and mutant introgression. This method utilizes 96-well plates for the collection of leaf tissue and the subsequent isolation of genomic DNA. The DNA isolation step is performed inexpensively within 3hr and uses a urea-based extraction buffer that does not require an organic extraction step. Yields of genomic DNA are sufficient to perform ∼25 PCR-genotyping reactions per sample. These qualities, coupled with the protocol being robust and easy for inexperienced users to master, make this method ideal for new researchers. © 2016 by John Wiley & Sons, Inc.

Quality Analysis of DNA from Cord Blood Buffy Coat: The Best Neonatal DNA Source for Epidemiological Studies?

Umbilical cord blood is an economical and easy to obtain source of high-quality neonatal genomic DNA. However, although large numbers of cord blood samples have been collected, information on the yield and quality of the DNA extracted from cord blood is scarce. Moreover, considerable doubt still exists on the utility of the buffy coat instead of whole blood as a DNA source. We compared the sample storage and DNA extraction costs for whole blood, buffy coat, and all-cell pellet. We evaluated three different DNA purification kits and selected the most suitable one to purify 1011 buffy coat samples. We determined the DNA yield and optical density (OD) ratios and analyzed 48 single-nucleotide polymorphisms using time-of-flight mass spectrometry (TOF MS). We also analyzed eight possible preanalytical variables that may correlate with DNA yield or quality. Buffy coat was the most economical and least labor-intensive source for sample storage and DNA extraction. The average yield of genomic DNA from 200 μL of buffy coat sample was 16.01 ± 8.00 μg, which is sufficient for analytic experiments. The mean A260/A280 ratio and the mean A260/A230 ratio were 1.89 ± 0.09 and 1.95 ± 0.66, respectively. More than 99.5% of DNA samples passed the TOF MS test. Only hemolysis showed a strong correlation with OD ratios of DNA, but not with yield. Our findings show that cord blood buffy coat yields high-quality DNA in sufficient quantities to meet the requirements of experiments. Buffy coat was also found to be the most economic, efficient, and stable source of genomic DNA.

A comparison of DNA extraction methods for biodiversity studies of eukaryotes in marine sediments

There is increasing interest in understanding the diversity of eukaryotic microorgan- isms living in marine sediments, particularly to assess the effects of anthropogenic activities. Sequencing technologies generate high-resolution data for biodiversity studies that are useful for environmental monitoring. However, there are challenges in coupling classical monitoring with new sequencing technology and, consequently, there is a requirement for stringent optimization and standardization of any new protocol. Sample preparation is a critical factor because errors introduced during this step will severely affect further analyses and conclusions. This is particu- larly important in studies where biodiversity between different samples is compared, such as in environmental monitoring programs. Several protocols for extracting genomic DNA from soil and sediment samples have been developed, but most are optimized for prokaryotes in terrestrial soils and may therefore not be optimally adapted for investigating benthic marine eukaryotes. In this study, we compared existing and modified genomic DNA extraction methods on 2 different mar- ine sediments with the aim to find an optimal protocol for processing a high number of sediment samples for further sequencing analysis. The protocols were evaluated based on quantity and quality of genomic DNA and recovered biodiversity. Results indicated significant variations in overall genomic DNA yield and purity among protocols. Further, our data suggest an effect of genomic DNA extraction procedure on eukaryotic diversity profiles, particularly for sediments with a high content of silt and clay.

A simplified genomic DNA extraction protocol for pre-germination genotyping in rice.

Genotyping is a critical step for molecular marker-assisted selection in rice. Rice genomic DNA samples for genotyping are typically isolated from living tissues such as seedlings. This requires the germination of all candidate seeds and extraction of DNA from the seedlings. Currently, an ideal individual is selected from a very large number of plants, which is time- and labor-consuming, requiring several transplantations of materials and sampling processes. In this study, we developed a simplified genomic DNA extraction protocol in rice by using amylase to treat half-seeds. The yields of genomic DNA from a half-seed of Indica and Japonica rice were greater than 203.8 ± 32.5 and 143.2 ± 25.5 ng, respectively, and the 260/280 nm absorbance ratio was 1.75-2.10. The DNA was confirmed to be sufficient for polymerase chain reaction amplification and can be used in a marker-assisted selection program.

Partial characterization of Acanthamoeba castellanii (T4 genotype) DNase activity.

The deoxyribonuclease (DNase) activities of Acanthamoeba castellanii belonging to the T4 genotype were investigated. Using zymographic assays, the DNase activities had approximate molecular masses of 25 and 35 kDa. A. castellanii DNases exhibited activity at wide-ranging temperature of up to 60 °C and at pH ranging from 4 to 9. The DNases activities were unaffected by proteinase-K treatment, divalent cations such as Ca(++), Cu(++), Mg(++), and Zn(++), or divalent cation chelating agent ethylenediaminetetraacetic acid (EDTA) or sodium dodecyl sulfate (SDS). The non-reliance on divalent cations and homology data suggests that A. castellanii DNases belong to the class of eukaryotic lysosomal DNase II but exhibit robust properties. The DNases activity in A. castellanii interfered with the genomic DNA extraction. Extraction methods involving EDTA, SDS, and proteinase-K resulted in low yield of genomic DNA. On the other hand, these methods resulted in high yield of genomic DNA from human cells suggesting the robust nature of A. castellanii DNases that are unaffected by reagents normally used in blocking eukaryotic DNases. In contrast, the use of chaotropic agent such as guanidine thiocyanate improved the yield of genomic DNA from A. castellanii cells significantly. Further purification and characterization of Acanthamoeba DNases is needed to study their non-classic distinct properties and to determine their role in the biology, cellular differentiation, cell cycle progression, and arrest of Acanthamoeba.

Isolation and amplification of genomic DNA from barks of Cinnamomum spp.

Cinnamomum verum Presl (syn. C. zeylanicum Blume), the cinnamon of commerce, is an important aromatic tree spice having wide applications in perfumery, flavoring, beverages, and medicine. Adulteration of cinnamon with the cheaper and inferior barks of C. aromaticum and C. malabatrum is a problem. Morphological distinction of the barks is difficult; in the case of powdered barks, the situation is even worse. DNA-based molecular tools are preferred under these circumstances. Isolation of high quality DNA is a prerequisite for molecular studies, but barks contain polysaccharides, polyphenols, and secondary metabolites that hamper DNA isolation. Since attempts at isolating DNA using existing protocols and commercial DNA isolation kits (Qiagen) have failed, a reliable and efficient protocol for the isolation and amplification of genomic DNA from the dried barks of 3 species of Cinnamomum (true cinnamon plus 2 spurious species), very recalcitrant materials, was perfected by trial and error. The yield of genomic DNA ranged from 5 to 8.1 µg g -1 of dried bark and the absorbance values at 260 nm and 280 nm gave a ratio higher than 1.8, indicating the good quality of DNA. The isolated DNA was PCR-amplified using 3 RAPD primers, 1 barcoding locus (rbcL ) primer, and restriction digested (EcoR V and Hind III). Complete restriction digestion and PCR amplification of the isolated DNA confirmed the good quality of the results and supported the efficacy of this protocol to yield DNA that can be utilized in further molecular analysis.