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What exactly are Wolbachia and how do we know if an insect is infected with them?

Learn about Wolbachia, an intracellular parasite that can manipulate insect reproduction. Discover how Wolbachia causes feminization, parthenogenesis, and cytoplasmic incompatibility in insects. Explore its potential role in gene flow and sympatric speciation. Also, understand the PCR technique used to detect Wolbachia DNA.

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What exactly are Wolbachia and how do we know if an insect is infected with them?

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  1. What exactly are Wolbachia and how do we know if an insect is infected with them?

  2. Feminization, Parthenogenesis and C.I., oh my! Important!! Wolbachia are inherited via infected eggs. Wolbachia are intracellular parasites Feminization – Somehow, maybe by influencing hormone levels, Wolbachia cause developing male woodlice to be born as female. Wolbachia-infected wasp embryo Parthenogenesis-inducing – In wasps and some other arthropods, females are diploid (result of fertilization) and males are haploid (develop from unfertilized eggs). Wol-bachia prevent chromosome division so eggs remain diploid, resulting in all female births. Q. How might Wolbachia affect gene flow in a population? How might this lead to sympatric speciation? Cytoplasmic Incompatibility (CI) – Infected females can reproduce with any mate whereas uninfected females are restricted to breeding with fewer uninfected males.

  3. DNA Replicatiton DNA sequence Bacteria “fishing” What do we use to “hook” Wolbachia DNA? Primers – a strand of RNA that serves as the starting point for DNA replication. WSPEC-F (5’-CATACCTATTCGAAGGGATAG-3’) WSPEC-R (5’-AGCTTCGAGTGAAACCAATTC-3’) DNA copies What gene (DNA) is being copied using PCR? http://nitro.biosci.arizona.edu/courses/EEB105/lectures/DNA_replication/DNA_rep.html PCR + primer animation : Use primers in PCR to help copy DNA (animation) - http://www.wiley.com/legacy/college/boyer/0470003790/animations/pcr/pcr.htm http://www.mcb.harvard.edu/Losick/images/TromboneFINALd.swf

  4. Objective: Use primers to copy the 16S rDNA gene in Wolbachia bacteria Bacterium with ribosomes Ribosome synthesizing a protein 16S rDNA gene – codes for making SSU rRNA Forward primer Reverse primer 5’ 3’ Conserved region Variable regions F R Copied DNA (using PCR) Campbell & Reece, 6th Ed. Loops (sites that are more free to mutate & evolve faster) Stems (sites that rarely mutate & are conserved) http://en.wikipedia.org/wiki/Image:10_small_subunit.gif Atomic structure of the small subunit a ribosome. The rRNA, shown in orange, helps match the mRNA (codon) to the tRNA (anticodon). Small subunit ribosomal RNA http://en.wikipedia.org/wiki/Ribosomal_RNA

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