Digitalization Of Leafhopper Specimens For Molecular Research And Study On Their Preservation Conditions

This study deals with the digital management of the leafhopper specimens for molecular research and studies on their preservation conditions. Biological specimens are the essential material for us to recognize the world’s biodiversity and the living environment. With the help of computer and network technology, biological samples can be digitalized, based on which a database with quick inquiry function may conducive to share resources, and improve the speed of people to gain information at various level, i.e. specimens, species, etc.In order to study the systematics of leafhoppers (Hemiptera, Cicadellidae), over the past ten years, Entomological Museum of Northwest A&F University has accumulated a large number of leafhopper specimens, which were all immersed with absolute alcohol in the ultra low temperature freezer (-80℃), formed a specimen bank for molecular research. Digitalizing these specimens can not only provide data for research but also let the taxonomists be aware of their usefulness. Digitalization of leafhopper specimens for molecular research mainly contains the following steps:First we put each leafhopper specimen into a small vial, which is full of absolute alcohol, then number the specimen; preserve the specimen in the ultra low temperature freezer; secondly, digitalize its text information and picture; finally, upload all these information into Animal Information System so that all the people concerned can share the information for various purpose.Preservation conditions of the specimens for molecular research are the primary factors influencing DNA extraction and usefulness of the specimens. Studies on the relationship between the speed of gene degradation and the preservation conditions can provide a scientific basis for the preservation of specimens for molecular research.We studied the effects of preservation time and preservation temperature on the gene degradation of the leafhopper specimens. The total genomic DNA was extracted from the species Kolla paulula, which were preserved in -80℃ for 1 day,1 month,3 months,6 months, 5.5 years and 6.5 years for the research on the effect of preservation time. The results show that fresh leafhopper samples have the highest DNA extraction rate and DNA will quickly degrade after the death of the specimens; and with the decrease of DNA content, the degradation rate become slower when they are preserved in -80℃.The total genomic DNA was also extracted from the Kolla paulula, which were preserved in -80℃,-40℃,-20℃,4℃,30℃ for 3 months, when we study the effects of preservation temperature. The results indicate that temperature has a great influence on the degradation of DNA; The higher the temperature is, the greater degradation degree of DNA when preserved them in a fixed time;-80℃ is the best preservation temperature of specimens for molecular research; the effects of preservation temperature under -40℃ and -20℃ are not different in the degradation rate of genomic DNA. The degradation rate of DNA is the fastest in insect specimens preserved in 30℃, but even in this case, we can still extract some genomic DNA if they are not preserved for too long.The study of leafhopper specimens’ digitization and preservation conditions not only standardize the management of collection specimens but also provide scientific basis for setting up the preservation conditions. It also provides reference for the digital management of other biological specimens.