Socijalni imunitet mravljih zajednica potaknut bakterijskom infekcijom

master's thesis

• Title (english): Social defences of ant colonies against bacterial infection
• Author: Marko Bračić
• Mentor: Sylvia Cremer (mentor)
• Mentor: Duje Lisičić (mentor)
• Committee member: Duje Lisičić (predsjednik povjerenstva)
• Committee member: Zlatko Liber (član povjerenstva)
• Committee member: Ivana Maguire (član povjerenstva)
• Committee member: Domagoj Đikić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2016-06-30, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Kao odgovor na patogene, zadružni kukci su razvili specifične organizacijske i fiziološke adaptacije te adaptacije u ponašanju, što je rezultiralo izbjegavanjem, kontrolom ili eliminacijom parazita. Takve grupne mjere koje poduzimaju pojedinci na razini čitave kolonije se nazivaju “socijalni imunitet”; primarno utvrđen na vanjskim gljivičnim infekcijama. Unatoč tome, paraziti koji zaražavaju oralno, slabo su istraženi. Stoga sam u svojim istraživanjima koristio entomopatogenu bakteriju Bacillus thuringiensis i mrave kako bih testirao utjecaj ingestije bakterijske spore na preživljavanje mrava, te postavio novi modelni sustav za istraživanje socijalnog imuniteta. Međutim, spore tri različita soja B. thuringiensis nisu dosljedno uzrokovale smrtnost u korištenom eksperimentalnom dizajnu. S obzirom da mehanizmi socijalnog imuniteta mogu djelovati prije nego što je parazit uopće započeo infekciju, istražio sam jesu li opažene promjene u ponašanju u Linepithema humile mravima, nakon izlaganja B. thuringiensis. Mravi izloženi bakteriji su dulje čistili vrh zatka nego kontrolna skupina. Nadalje, L. humile ima različite žlijezde u zatku čije sekrecije, konzumirane nakon ingestije spora, bi mogle inhibirati rast bakterija. Otkrio sam da sekreti zatka stvarno inhibiraju rast B. thuringiensis, što indicira da čišćenje vrha zatka može poslužiti kao prva linija obrane od oralno inducirane invazije kolonije od strane parazita, prije nego što se ona proširi po tijelu domaćina.

Abstract (english)

In response to pathogen pressure, social insects evolved specific organisational, physiological and behavioural adaptations resulting in avoidance, control or elimination of parasites. Such collective action of individuals at the level of the whole colony is called social immunity; established primary on fungal “external” infections. However, orally infecting parasites are poorly investigated. Therefore, I here used an entomopathogenic bacterium Bacillus thuringiensis and ants, to test the influence of bacterial spore ingestion on ant survival, in order to establish a novel model system for exploring social immunity. However, spores from three different B. thuringiensis strains did not consistently induce mortality under used experimental setup. Given that mechanisms of social immunity may act before the parasite had established an infection, I further tested whether behavioural changes in Linepithema humile ants are observed after exposure to B. thuringiensis. Indeed, B. thuringiensis-exposed ants self-groomed their gaster tip longer then the control-exposed ants. L. humile have different gaster glands, which secretions consumed after spore ingestion might inhibit bacterial growth. Indeed, I found that the gaster secretions inhibit B. thuringiensis growth, indicating gaster tip self-grooming may serve as the first line of defence against orally induced parasite invasion of the colony, before the infection was even established within the host body.

• Keywords: socijalni imunitet; žljezde zatka; Bt; L. humile; paraziti
• Keywords (english): social immunity; host-parasite interaction; gaster glands; orally infecting parasites; Bt
• Language: croatian
• URN:NBN: urn:nbn:hr:217:209661
• Study programme: Title: Experimental Biology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra eksperimentalne biologije (magistar/magistra eksperimentalne biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-04-25 10:29:02