DNA degradation within mouse brain and dental pulp cells 72 hours postmortem

In this study, we sought to elucidate the process of DNA degradation in brain and dental pulp cells of mice, within postmortem 0-72 hours, by using the single cell gel electrophoresis assay and professional comet image analysis and processing techniques. The frequency of comet-like cells, the percentage of tail DNA, tail length, tail moment, Olive moment and tail area increased in tandem with increasing postmortem interval. In contrast, the head radius, the percentage of head DNA and head area showed a decreasing trend. Linear regression analysis revealed a high correlation between these parameters and the postmortem interval. The findings suggest that the single cell gel electrophoresis assay is a quick and sensitive method to detect DNA degradation in brain and dental pulp cells, providing an objective and accurate new way to estimate postmortem interval.

Determination of the Early Time of Death by Computerized Image Analysis of DNA Degradation: Which Is the Best Quantitative Indicator of DNA Degradation?

This study evaluated the correlation between DNA degradation of the splenic lymphocytes and the early time of death, examined the early time of death by computerized image analysis technique （CIAT） and identified the best parameter that quantitatively reflects the DNA degradation. The spleen tissues from 34 SD rats were collected, subjected to cell smearing every 2 h within the first 36 h after death, stained by Feulgen-Van＇s staining, three indices reflecting DNA content in splenic lymphocytes, including integral optical density （IOD）, average optical density （AOD）, average gray scale （AG） were measured by the image analysis. Our results showed that IOD and AOD decreased and AG increased over time within the first 36 h. A stepwise linear regression analysis showed that only AG was fitted. A correlation between the postmortem interval （PMI） and AG was identified and the corresponding regression equation was obtained. Our study suggests that CIAT is a useful and promising tool for the estimation of early PMI with good objectivity and reproducibility, and AG is a more effective and better quantitative indicator for the estimation of PMI within the first 36 h after death in rats.

Uptake and Organ Distribution of Feed Introduced Plasmid DNA in Growing or Pregnant Rats

Fragments of DNA present in food and feed are taken up by the gastrointestinal tract (GIT) of mammals. The extent of uptake varies according to organism, study design and DNA source. This study explores the hypothesis that actively growing, as well as pregnant rats, are more likely to take up DNA from the GIT than mature animals due to the high demand for nutrients for tissue and organ development. Plasmid DNA (pDNA) was added to standard feed for growing, and pregnant rats. The young rats received one pDNA (50 μg) containing meal by gavage. Blood, organ and tissue samples were harvested at 2 h to 3 days post feeding (p.f). The pregnant females were fed pellets containing pDNA (100 μg) daily, starting at day 5 after established pregnancy. Females and foeti were killed at days 7 and 14 of gestation, and pups at the time of weaning. Genomic DNA was analyzed by PCR followed by Southern blot and real-time PCR. A 201 bp target sequence was detected in mesenteric lymph nodes, spleen, liver and pancreas from growing rats 2 h p.f. At 6 h, target DNA was detectable in the kidneys, and at three days p.f. in the liver. Target DNA was not detected in samples from pregnant rats, their foeti or pups. In conclusion, low level of feed introduced DNA could be transiently detected in organs of young, growing rats. However, indications of increased DNA uptake levels in the GIT of growing rats were not found.

Potential anticancer activity analysis of piscidin 5-like from Larimichthys crocea

Antitumor activity is one characteristic function of some certain antimicrobial peptides(AMPs)found in recent years.In the present study,we attempted to detect potential anticancer activity of a recombinant piscidin 5-like from Larimichthys crocea(r Lc-P5L)which owned widely antibacterial and strong antiparasitic activity in vitro.The light microscope observation indicated r Lc-P5L was of antitumor activity to He La cells,293 T cells and L929 cells.MTT assay showed the toxic sensitivity of r Lc-P5L to three tumor cell strains was 293 T>L929>He La.Scanning electron microscope(SEM)results showed r Lc-P5L behaved like a lytic peptide to cause damage on cells membrane of L929 cells by forming globular clusters,even pores at 60μmol/L,or degrading membrane to make it completely lose cytoskeleton structure at 80μmol/L;r Lc-P5L treatment also resulted in DNA degradation.Fluorescence observation results indicated r Lc-P5L could cause L929 cells at least two obvious changes:one is nucleus,nuclear chromatin condensed in the margin,nuclear volume became smaller and shrank to be out of shape,or lysed to be debris;the other is cytoskeleton,they became disordered and polarized to make cells atrophic shapes,or even lysed to be debris.In summary,r Lc-P5L owned potential anticancer activity causing membrane structure damage and genome DNA degradation.Interestingly,treatment with different concentration of r Lc-P5L seemingly caused the similar but different changes,whether it indeed gave rise to cancer cells diverse death way,the further studies should be performed,and the detailed mechanisms were still need further explored.

Twenty years hunting for sulfur in DNA

Here we tell a 20-year long story.It began with an easily overlooked DNA degradation(Dnd)phenomenon during electrophoresis and eventually led to the discovery of an unprecedented DNA sulfur modification governed by five dnd genes.This unusual DNA modification,called phosphorothioation,is the first physiological modification identified on the DNA backbone,in which the nonbridging oxygen is replaced by sulfur in a sequence selective and stereo-specific manner.Homologous dnd gene clusters have been identified in diverse and distantly related bacteria and thus have drawn immediate attention of the entire microbial scientific community.Here,we summarize the progress in chemical,genetic,enzymatic,bioinformatical and analytical aspects of this novel postreplicative DNA modification.We also discuss perspectives on the physiological functions of the DNA phosphorothioate modification in bacteria and their implications.

Application of Next-generation Sequencing Technology in Forensic Science

Next-generation sequencing （NGS） technology, with its high-throughput capacity and low cost, has developed rapidly in recent years and become an important analytical tool for many genomics researchers. New opportunities in the research domain of the forensic studies emerge by harnessing the power of NGS technology, which can be applied to simultaneously analyzing multi- ple loci of forensic interest in different genetic contexts, such as autosomes, mitochondrial and sex chromosomes. Furthermore, NGS technology can also have potential applications in many other aspects of research. These include DNA database construction, ancestry and phenotypic inference, monozygotic twin studies, body fluid and species identification, and forensic animal, plant and microbiological analyses. Here we review the application of NGS technology in the field of forensic science with the aim of providing a reference for future forensics studies and practice.