Today’s Phenomenon:

UC Davis https://www.ucdavis.edu/news/zika-virus-and-other-ailments-take-flight-infographic

San Gabriel Valley Mosquito & Vector Control District: http://www.sgvmosquito.org/newsevents_articles_details.php?aid=68

https://www.youtube.com/watch?v=2wA9YJNxRSA

Video

Article

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3775348/pdf/nihms504082.pdf

DNA Extraction Insect Identification

Overview of the Wolbachia laboratory component

709 bp

438 bp

Gel Electrophoresis PCR

Insect Taxonomy

We will classify our insects to “Order”

Insect Orders

Approx 30; many taxonomists disagree on the # of orders and their names

“ptera” means wing.

Wings are the most obvious

way that the orders differ

http://www.backyardnature.net/insects.htm

“Key to Insect Orders” app

Online version: http://www.discoverlife.org/mp/20q?guide=Insect_orders

tarsomeres

3 pairs of legs

compound eye

pretarsus

Main insect characteristics Chitinous exoskeleton

3-part body 3 pairs of jointed legs

2 antennae Mouthparts

Compound eyes

Insect Identification

https://www.youtube.com/watch?v=1ErcwogWbIA

After Lunch – Revisit the Phenomenon

Possibly the most common intracellular bacteria in the biosphere

Found in ~66% of arthropod species; 20% of all insects contain it

Transmitted through eggs needs host to produce females

Can alter host biology to promote their survival

.

What is Wolbachia?

Nature Reviews Microbiology 6, 741-751 (October 2008)

Maternally inherited microbial infections that manipulate the reproduction of their host species towards the production or survival of

infected female hosts

Wolbachia is a Reproductive Parasite

Employs 4 strategies to increase # of infected females

Widespread Lateral Gene Transfer from Intracellular Bacteria to Multicellular Eukaryotes Science. 2007 Sep 21;317(5845):1753-6

Host chromosomal rearrangements new protein products Acquisition of new genes (gain-of-function) Disruption of existing genes (loss-of-function) Reproductive isolation and speciation Rapid change, Reduced genetic diversity Accumulation of mutations between isolated groups

Horizontal Gene Transfer

Approximately one-third of sequenced invertebrate genomes contain Wolbachia genes

HGT is more frequent between unrelated species than scientists previously believed

This poses dramatic implications for evolution

Wolbachia can insert its genome into the host cell

Have Wolbachia induced evolutionary change?

Population Replacement

Transmits Disease Does Not Transmit Disease

https://www.youtube.com/watch?v=F3G3oPUfh60

Wolbachia Infection Reduces Blood Feeding Success in Dengue Fever Mosquito

http://wolbachiamap.herokuapp.com

Duplex PCR Results

Students can expect a positive Wolbachia diagnosis in one out of five insects.

1. 100bp Ladder

2. Fly from SJSU lab, ‘11

3. Ladybug from Mt. View, ‘09

4. Aphids from my tomato plant, ‘10

5. Ant from Sunnyvale, ‘09

6. Large mosquito from San Mateo, ‘09

7. Wol+ control, Nasonia, ‘10

1 2 3 4 5 6 7

709 bp

438 bp

Gene #1: Cytochrome C Oxidase (CCOI) This is a gene that is present in all insects. It is used to verify that you had a successful DNA extraction. This gene will be present in all samples, regardless of whether or not the insect is infected with Wolbachia. It serves as an internal cntrol, or a reference gene, to make sure that your reaction worked. The PCR product for this goene will be 709bp in length. Gene #2: Wolbachia specific ribosomal DNA (Wspec) This gene is only found in Wolbachia, and will be present only if your insect was infected. The PCR product for this gene will be 438bp in length.