Research Progress on Developmental Biology of Sarcosaprophagous Insects / 法医学杂志

Forensic entomology provides a feasible way to estimate postmortem interval (PMI), of which the growth and development of sarcosaprophagous insects is the most widely used indicator in forensic practice. Over the years, forensic entomologists have carried out a large number of studies on the development biology of sarcosaprophagous insects. This paper illustrates the main factors that affect the development of sarcosaprophagous insects, including temperature, humidity, light, food types and poisons. The development indicators of sarcosaprophagous insects were reviewed from the perspectives of morphology, differential gene expression and biochemical characteristics. It is emphasized that future research of development biology on sarcosaprophagous insects should fully absorb and integrate the methods of artificial intelligence and omics, and the research object also needs further expansion in order to establish a more objective and more accurate PMI estimation method.

Identification of Common Sarcosaprophagous Flies in the Yangtze River Delta by COⅠ Gene / 法医学杂志

OBJECTIVES@#To identify the common sarcosaprophagous flies in the Yangtze River Delta based on mitochondrial cytochrome c oxidase subunit Ⅰ(COⅠ) gene sequence and verify the reliability of this method.@*METHODS@#Seven common genetically stable sarcosaprophagous flies in three families and six genera were collected from large domestic pig carcasses placed in the field and cultured in the laboratory for many generations. The whole genome DNA was extracted and the COⅠ gene fragment was amplified. The forward and reverse sequencing was followed by splicing. The base composition of the amplified fragment and the rate of interspecific evolutionary divergence were analyzed by software such as Mega 7.0.26. The phylogenetic tree of COⅠ gene sequence of common necrophagous flies in the Yangtze River Delta was established by neighbor joining (NJ) method and unweighted pair-group method with arithmetic means (UPGMA) method.@*RESULTS@#The average base composition of different flies was A(30.14%), T(38.23%), C(15.98%), G(15.65%). The rate of interspecific evolutionary divergence ranged from 2.2% to 15.3%, the lowest rate was between Chrysomya megacephala and Chrysomya pinguis, the highest rate was between Muscina stabulans and Boettcherisca peregrina.@*CONCLUSIONS@#COⅠ gene can be used to identify the common necrophagous flies in the Yangtze River Delta.

Application of Sarcosaprophagous Insects to Estimate the Postmortem Interval in 11 Cases / 法医学杂志

Objective To test the feasibility and accuracy of with sarcosaprophagous insects postmortem interval （PMI） estimation with sarcosaprophagous insects and provide references for estimation practice. Methods Eleven cases confirmed by the detection results, with complete entomological evidence were selected. The insect species, estimation results and true results involved in the cases were statistically analyzed and compared. Results Thirteen species of insects were found at the criminal scene, including Chrysomya megacephala （Fabricius）, Chrysomya rufifacies （Macquart）, Chrysomya nigripes （Aubertin）, Lucilia sericata （Meigen）, Hydrotaea spinigera Stein, Muscina stabulans （Fallén）, Sarcophagid （species were not identified）, Megaselia scalaris （Loew）, Hermetia illucens （Linnaeus）, Saprinus splendens （Paykull）, Creophilus maxillosus （Linnaeus）, Dermestes maculatus （De Geer） and Necrobia ruficollis （Fabricius）. The PMI of all eleven cases was within the range of estimated PMI. The estimated results of 72.73% cases were on the same day of the true results. Conclusion Sarcosaprophagous insects can estimate the PMI simply and conveniently. In cases where the PMI is within the time range of one generation of flies or beetles, the estimation results are relatively accurate. However, the estimation is less accurate when the PMI is beyond the time range.

Development of Dermestes Maculatus at a Constant Temperature and Its Larval Instar Determination / 法医学杂志

Objective To establish the basic data for estimating minimum postmortem interval （PMImin） of heavily decayed and skeletonized remains by studying the development of Dermestes maculatus DeGeer （Coleoptera: Dermestidae）. Methods The developmental stages of Dermestes maculatus were observed at four constant temperatures of 20 ℃, 24 ℃, 28 ℃ and 32 ℃, and the changes in body length were also examined as the biological indicator to estimate larval day-age and instar. Results The total developmental time from egg to adult at 20 ℃, 24 ℃, 28 ℃ and 32 ℃ were （126.7±10.6） d, （69.4±8.2） d, （50.4±8.4） d and （49.6±6.5） d, respectively. The body length increased gradually, but changed irregularly as a whole. Conclusion The study provides basic data on the development and growth of Dermestes maculatus, especially on its developmental duration as a significant value for estimating PMImin of heavily decayed and skeletonized remains. Nevertheless, the change of body length is not found to be the best biological indicator for instar determination.

Standardized Application of Forensic Entomology and Application Data of Sarcosaprophagous Insects in China / 法医学杂志

Postmortem interval （PMI） estimation is a major problem in forensic medicine and a vital indicator of crime investigations. Forensic entomology provides a new way to the PMI estimation, and its superiority has been confirmed through many cases, especially in relation to the cadaver at the stage of advanced decomposition even skeleton. The technologies of forensic entomology have become more mature. This review describes the mechanism of forensic entomology used for PMI estimation, emphasizes the standardized application of technology, and lists the data for the reference of forensic experts in China.

Detection of Metabolism Function of Microbial Community of Corpses by Biolog-Eco Method / 法医学杂志

OBJECTIVES@#To detect the changes of microbial community functional diversity of corpses with different postmortem interval （PMI） and to evaluate forensic application value for estimating PMI.@*METHODS@#The cultivation of microbial community from the anal swabs of a Sus scrofa and a human corpse placed in field environment from 0 to 240 h after death was performed using the Biolog-Eco Microplate and the variations of the absorbance values were also monitored. Combined with the technology of forensic pathology and flies succession, the metabolic characteristics and changes of microbial community on the decomposed corpse under natural environment were also observed.@*RESULTS@#The diversity of microbial metabolism function was found to be negatively correlated with the number of maggots in the corpses. The freezing processing had the greatest impact on average well color development value at 0 h and the impact almost disappeared after 48 h. The diversity of microbial metabolism of the samples became relatively unstable after 192 h. The principal component analysis showed that 31 carbon sources could be consolidated for 5 principal components （accumulative contribution ratio >90%）.The carbon source tsquare-analysis showed that N-acetyl-D-glucosamine and L-serine were the dominant carbon sources for estimating the PMI （0=240 h） of the Sus scrofa and human corpse.@*CONCLUSIONS@#The Biolog-Eco method can be used to reveal the metabolic differences of the carbon resources utilization of the microbial community on the corpses during 0-240 h after death, which could provide a new basis for estimating the PMI.

The community succession of sarcosaphagous insects on pig carcasses in summer indoor and outdoor environment in Shenzhen area / 法医学杂志

OBJECTIVE@#To explore the growing development and community succession of main sarcosaphagous insects on pig carcasses in summer indoor and outdoor environment in Shenzhen area and to estimate the postmortem interval (PMI).@*METHODS@#From early May to August in 2013, in Forensic Medical Examination Center of Shenzhen Public Security Bureau, the main insect species and the decomposition process were observed in two adult pig carcasses of simulative indoor and outdoor environment. The different decomposition stages and the community succession of insects were recorded.@*RESULTS@#The indoor and outdoor pig carcasses showed skeleton 412.5 and 325 hours after death, respectively. The main species of flies on pig carcasses were Chrysomya megacephala, Chrysomya rufifacies and Chrysomya chani. The main species of beetles were Crecphilus maxillosus, Necrobia ruficollis, Saprinus splendens and Dermestes maculatu. The dominant species of flies in the outdoor pig carcasses obviously produced the second generations due to the effect of mass rainfall, nor in the indoor pig carcasses.@*CONCLUSION@#There are regular patterns on the community succession of insects on pig carcasses in summer indoor and outdoor environment in Shenzhen area. The activity patterns of seven typical insects and their larva show important value for estimating PMI.

Polymers poly (β-amino esters) nanoparticles for gene delivery / 第二军医大学学报

Objective: To synthesize a new type of cationic polymers (β-ammo esters) (PBAE) and to study its role as a gene vector. Methods: PBAE was synthesized by the Michael addition reaction. PBAE/pDNA complex nanoparticles were prepared by self-assembly, and the gene tranfection efficiency mediated by the nanoparticles into HEK293 cells in vitro was observed. Results: When weight ratio of PBAE/pDNA was 50: 1, pDNA was completely wrapped. And the transfection efficiency of PBAE/pDNA nanoparticles (PBAE/pDNA weight ratio being 200: 1) was significantly higher than PEI/pDNA nanoparticles (43.3% ± 3.7% vs 30.3% ± 2.1%, P < 00.05). Conclution: Cationic poly(β-amino esters) can electrostatically bind to and condense anionic DNA into nanometersized parties. PBAE/pDNA nanopartides has a high transfection efficiency in in vitro transfection experiments.

A preliminary study on estimation of postmortem interval according to beta-actin mRNA stability in rat / 法医学杂志

OBJECTIVE@#In order to find a new parameter to estimate the postmortem interval, beta-actin mRNA in lung and thoracic muscle of rats was detected at different time point postmortem.@*METHODS@#Rats were killed by neck dislocation and left in a temperature controlling system at 21 degrees C for 12 days postmortem. Total RNA in lung and thoracic muscle at different time point was extracted and beta-actin mRNA expression was examined by RT-PCR. Semi-quantification analysis of the image of electrophoresis was performed to confirm the changes of beta-actin mRNA expression.@*RESULTS@#beta-actin mRNA in lung of rats still could be detected at 12 days postmortem, but-disappeared in thoracic muscle at 8 days postmortem.@*CONCLUSION@#The expression of beta-actin mRNA in lung and thoracic muscle could be a new parameter for estimation of PMI.