germ-free wasp embryo collection and rearing with nasonia-rearing medium (nrm)

Rearing Germ-Free &lt;em&gt;Nasonia&lt;/em&gt; Wasps

Germ-free animals are animals that have no detectable living microorganisms and parasites1. Germ-free embryos can be obtained by dissecting the mother under aseptic conditions and subsequently raised in barrier systems2. Such animals can be used to study the effects of microorganisms on animals, such as on the intestinal microbiota, immune system, and metabolism1. With certain technical means, many insects and even mammals can be rendered sterile3,4. Germ-free animals have a unique role and have been widely used in various aspects of microbiology research5. For example, the use of germ-free Nasonia wasps has revealed that microorganisms can help hosts adapt to new environments under long-term exogenous environmental stress6,7.
Nasonia parasitoids are small parasitic wasps that inject their eggs into the pupae of flies4. There are four known species of Nasonia, including Nasonia vitripennis, Nasonia longicornis, Nasonia giraulti, and Nasonia oneida8. N. vitripennis can be found worldwide, while the other three species have limited ranges in North America4. Nasonia parasitoid wasps are regarded as ideal model insects because of their characteristics, such as easy cultivation, short reproduction cycle, sequenced genome, and long term diapause8,9. They can be used to study various aspects of insect evolution, genetics, development, behavior, and symbiosis10. Moreover, Nasonia parasitoid wasps can also help control harmful flies in agriculture and disease11. The successful establishment of a sterile insect system involves two major steps: (1) sterilization of the embryos and (2) provision of sterile food to the larvae in vitro. In order to obtain sterile food, Brucker and Bordenstein12 developed Nasonia rearing medium (NRMv1) in 2012 by using chemicals such as antibiotics, bleach, and fetal bovine serum to kill bacteria12. However, the chemical sterilization method resulted in low survival and eclosion rates of N. vitripennis13. Then, in 2016, Shropshire et al. developed NRMv2 by using a filter sterilization method instead of a chemical sterilization method to eliminate the hazards of antibiotics and other substances, and optimized the breeding process13. Unfortunately, this method still has some disadvantages, such as the challenges associated with preparing and using the medium, as well as the risks of drowning, underfeeding, or dehydration for the embryos, larvae, and closed pupae14. Wang and Brucker14 recently improved the Nasonia rearing media version 3 (NRMv3) and the germ-free rearing version 2 (GFRv2) protocols. These improvements reduced the cost and media consumption. However, the NRMv3 has a very short storage time and is highly susceptible to contamination.
Building on NRMv3, the NRM preparation tool storage method and nutrient ratio were optimized in this study. This methodological refinement facilitates using N. vitripennis as a model for microbiome studies. Compared with the NRMv3 developed by Wang et al.14, the improved tool for squeezing Sarcophaga bullata pupa, one of the NRM raw materials, greatly enhances the production efficiency of S. bullata pupa tissue fluid compared with the 60 mL syringe with a bottom hole used by Wang et al.14. We adjusted the nutrient ratio of NRM, which led to a certain increase in the survival rate of germ-free Nasonia wasps without affecting their development time. In addition, the NRM was packed into small-capacity centrifuge tubes (1.5 mL) and frozen in a -20 &#176;C refrigerator to extend the storage time. It is worth noting that while we used the housefly Lucilia sericata as the host and source for NRM preparation, this protocol can likely be adapted for other Nasonia hosts that are available in the laboratory.

Author Spotlight: Optimizing the Rearing Procedure of Germ-Free Wasps  

Optimizing the Rearing Procedure of Germ-Free Wasps

Our research focuses on the study of insect-microbiota interactions, specifically investigating the impact of in those symbiotic bacteria and exploring the dynamics of host-microbe relationships. Germ-free Nasonia is an essential tool for conducting this research. Current research utilize technologies such as high-throughput sequencing, germ-free insect rearing, transcriptoptomics, proteomics, and advanced microscope.This tool enable comprehensive analysis and virtualization of insect-microbe host interaction for advancing our understanding of this field. The optimized the procedure for preparing the Nasonia Rearing Medium provides economic advantages and saves time and effort. Additionally, it effectively reduces the risk of NRM contamination during the feeding process, greatly improving the efficiency of producing aseptic Nasonia

Watch this Scientific Journal Video about Germ-Free Wasp Embryo Collection and Rearing with Nasonia-Rearing Medium NRM at JoVE.com

Germ-Free Wasp Embryo Collection and Rearing with Nasonia-Rearing Medium (NRM)  

Germ-Free Wasp Embryo Collection and Rearing with Nasonia-Rearing Medium (NRM)

To begin, parasitize about 40 Lucilia sericata pupae onto emerging adult male and female Nasonia wasps mated for 1.5 days. Within 12 to 24 hours after parasitization, carefully open one end of the pupal shell using a sterile dissecting needle. Hold the other end of the shell and locate the wasp embryo.Then transfer the embryo to a sterile cell strainer moistened with PBS. Once 20 to 30 embryos have been transferred, wash them with 1, 000 microliters of 10%sodium hypochlorite solution followed by sterile PBS and 70%ethanol. Finally, wash them three times with sterile PBS.Next, place a polypropylene mesh sheet pre-wetted with PBS into a 24 well plate. Using a sterilized small brush, gently transfer the wasp embryos from the cell strainer to the polypropylene mesh sheet. For the wasp rearing, add 50 microliters of prepared NRM to each well with a sheet.Then add one milliliter of sterile water between each well to maintain a humid environment for growth. The next day, transfer the polypropylene mesh containing the larva from one well to another well using alcohol disinfected tweezers, and add 50 microliters of equilibrated NRM. After nine to 11 days of feeding, over 80%of the larva should develop into white or yellow pupae.then transfer the mesh to a clean well plate. In the present study, the survival rate of the germ-free wasps from larva to pupae was significantly improved compared to rearing germ-free wasps with NRM version three. Additionally, there was no difference in the generation period between the germ-free and conventionally reared wasps.

germ-free-wasp-embryo-collection-rearing-with-nasonia-rearing-medium

Research

JoVE Journal

Biology

456 Views.  Chinese Academy of Sciences. To begin, parasitize about 40 Lucilia sericata pupae onto emerging adult male and female Nasonia wasps mated for 1.5 days. Within 12 to 24 hours after parasitization, carefully open one end of the pupal shell using a sterile dissecting needle. Hold the other end of the shell and locate the wasp embryo.Then transfer the embryo to a sterile cell strainer moistened with PBS. Once 20 to 30 embryos have been transferred, wash them with 1, 000 microliters of 10%sodium hypochlorite solution f...