ECOL 182R Bacterial Symbionts of Animals: Friends, Enemies, and Frenemies Lecture
ECOL 182R Bacterial Symbionts of Animals: Friends, Enemies, and Frenemies Lecture ECOL 182R
U of M
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This 26 page Class Notes was uploaded by Jenna Pimentel on Thursday March 12, 2015. The Class Notes belongs to ECOL 182R at University of Arizona taught by Bonine, Hunter, Martinez in Spring2015. Since its upload, it has received 96 views. For similar materials see Introductory Biology II in Science at University of Arizona.
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Date Created: 03/12/15
322015 Bac rer39ial symbionTs of animals Especially mice humans and a few insecTs 03 March 2015 ECOL 182R UofA K E Bonine Many Thanks To Dr39 Molly Hun rer39 a DZL quiz 9 1 In rima re associa rion I organisms Includes parasi ric hCll beneficial rela rionsh r 5 are difficul r To ca regc A Symbiont is a smalle lives in or on The large example in head lice 322015 Microbial symbionts are everywhere not just in animals and not just bacteria 39 bacteria on forehead different from the bacteria on back of hands Once you appreciate the role of bacteria in our health you may look at handsanitizer and antibiotics in a new way Skin bacteria can protect against infectionquot I Why are we starting to find out so much NOW Less than 1 0f bacteria can be cultured Many bacteria look alike even with electron microscopes 50 we have a limited ability to investigate complex communities of bacteria with just morphology quotl j 7 tr Lian 7 77 39 39 39 i 39 r39 L 2 I i I I Why are we starting to find out so much NOW Techniques that have changed biology 1 REVIEW Polymerase chain reaction PCR makes lots of DNA out of a very small amount 2 Short segments of DNA primers bind to genes of interest at each end Then heating and cooling a DNA polymerase and free nucleotides causes exponential increase in no of copies Wilmer Backward Anneal Extend Fust cyde lll Second cvde What39s the value of making lots of DNA out of a very small amount Ill Tlllll rd cycle 322015 TACK polymerase allows you to make copies of PNA lives in water loves heat 9 heat it up rip apart DNA cool it down make copies repeat WWW3 322015 I Why are we sTarTing To find ouT so much NOW Techniques ThaT have changed biology fundamenTally 2 DNA sequencing new Techniques relatively inexpensive makes sequencing a single bacTer39ial gene from Thousands of cells affordable Why advanTage does DNA sequencing have in helping us char39acTer39ize The diver39siTy of bacTer39ia JanIhbhhbhnInhmhhnnmnIInmIh I I IIIIII 39I O U CriTical Technique ThaT changed our abiliTy To understand The mammalian gut flora ie The bacTeria in The guT 3 The axenic N0 guT microbes and gnotobiotic reduced and known number39 of microbial species mouse models Why do you Think This mighT have been an impor39TanT br39eakThr39ough can manipulate to create 39 f l acontrol 322015 Lasle 4 A cri rical effor r To charac rerize all of The bac reria associa red wi rh humans The Human Microbiome projec r ZOO Scien ris rs 80 ins ri ru rions sequenced bac reria from 250 heal rhy people Comple red in 2012 Sampled from differen r par rs of skin openings eg nose mou rh vagina and gas rroin res rinal Track gu r Sequenced a single bacterial ribosomal gene 16 rDNA Tha r allows assignmen r To bac rerial group II Bac reria ON animals A Human skin bac reria Found lOOO species of bac reria a trillion cells mos r non pa rhogenic WWW5 II Bac reria ON animals A Human skin bac reria Amazing varia rion in rhe communi ries eg compare manubrium high ches r wi rh fron r a i E g s 3 i k 1 39 339 I E A 39i i a a W E T 5quot H 39 33 L3 a A 5 2 3939 l el 0 lo el Actinabac l na denebaalerineae I P ropionibacterineae Micmmmilneae i1 Either H Etln bal iel l l i a stem i d ates Cyrano ha maria TFirmicutes 3 Other lFi rmicutes I E39laphy looomameae rdteoibaateria i Divisions mntributing s 1 HF Unclassified A Human skin bac reria wha r do They do Bac reria and swea r cause acid environmen r Tha r makes if more difficul r for pa rhogenic bac reria To es rablish May secre re an rimicrobial subs rances rha r keep pa rhogenic bac reria from domina ring A common Theme pathogens inon healthy individuals jus r not causing disease 322015 gorearm comple rely differen r bac reria 11 12 W mio 322015 Boc rer39io on beewolves 13 Beewolf noTuml hisTory CopTur39e bees Nes r in sandy soil PuT paralyzed bee in bur39r39ow Ior39voe feed on bees When Ior39vol beewolves compleTe developmen r They spin cocoon over39win rer39 Nes r is mois r risk of bacterial or fungal infection 14 322015 Beewolves carry bac reria on Their anTennae actinobacteria Transmi r red from mo rher To offspring Secrefed in burrow by mo rher incorporafed info cocoon by larvae Each species of beewOIf has 5 Own Beewolf cocoon using imaging Spec39es of bader39um Technique showing mul riple na rural an ribio rics on surface 15 Bac reria live inside pocke rs in an rennae fed by wasp secre rions 16 322015 What do you think the role of the bacterium is How would you test thatidea remove bacteria and expose to certain conditions remove specifictarget bacteria see if it affects growth 17 III Bacteria in animal CELLS h A Not just bacteria but lots of viruses some protists are parasitic symbionts pathogens of human cells Bacterial cell pathogens are less dangerous now than they werelI I Malaripamsifem d whyvaccnnes urbanization antibiotics39oodce39f The bacterium Rickettsia prowazakii is carried by human lice and causes typhus C 322015 Typhus a disease caused by The bacTerium Rickettsia Very high fever poTenTially leading To deaTh Epidemics ofTen followed wars and naTural disasTers where lice density is high During World War I Typhus caused 3 million deaThs Thousands of inmaTes in Nazi concentration camps died of Typhus 2 Killing lice wiTh DDT l Can be effecTively TreaTed wiTh anTibioTics 19 III BacTeria in animal CELLS A In insects many bacteria in cells are then transmitted from mother To offspring in the egg cytoplasm They are vertically transmitted parem offspring not horizontally or contagiously like a cold or most diseases we can Think of Can we guess anything about the relationship between insect and bacterium from knowing how the bacteria are transmitted transmitted to hands from door 20 knob etc horizontal transmission eat fecies to consume bacteria needed for digestion W m 10 322015 Many of These in rerac rions are beneficial for bo rh par rners mu rualism Aphids plan r sap sucking insec rs live on a die r Tha r39s mosle sugar39 wa rer39 wi rh low levels of amino acids many ml The kind They need To make pr39o reins 21 How do aphids survive on such a lousy dieT They house bac rer39ia in a special or39gan bac rer39ia syn rhesize essen rial amino acids Aphids wi rhou r bac rer39ia cannot reproduce Aphids and bac rer39ia have evolved Toge rher39 39 Bac rer39ia in specialized aphid cell 22 WWW 11 322015 IV Bacteria in GUTS A In mice and menquot i Historical and quite recent characterization of gut bacteria as commensal ie beneficial to bacteria no effect on us We assumed that the bacteria were just there and occasionally bad ones got in and made us sick 23 IV Bacteria in GUTS In humans What39s in there About 1000 species 100 trillion cells We carry more bacterial cells than human cells Sli i E39ECGHDUCIDRS r 39l Gluingquot nit HI I PRDLiFEMTl H Rankin uranium About 25 pounds of our weight 322015 IV BacTeria in GUTS A Where do They come from 1 BirTh canal a few species 2 mother39s milk 600 species In firsT few years more and more are acquired 25 IV BacTeria in GUTS In humans whaT do They do Make viTamins digesT complex sTarches Help The guT develop normally Help The immune sysTem develop normally Keep pathogens from makinq us sick LoTs more claims including roles in auTism reducing sTress To be deTermined 26 W WB My bacTer39ia ar39e noT your39 322015 IV BacTeria in GUTS bacTer39ia CommuniTies of bacTer39ia differ an envir39onmenTal componenT some 1 gt I I similaritv within a household 39 geneTic componenT idenTical quot 5 W 39 Twins bacTer39ia more similar Than fr39aTer39nal Twins IV BacTeria in GUTS Differences in bacTer39ial communiTies beTween obese and Thin people Obese people have more bacTer39ia from The phylum Fir39micuTes fewer39 BacTer39oideTes Thin people had The reverse and a more diverse seT Obese people who became Thin acquired a 39thin person39s bacterial community39 ll 14 322015 IV BacTeria in GUTS NuTriTion differs depending on what bacteria one has STudy performed in Malawi on 317 pairs of Twins some fraTernal some idenTical buT living in The same household geTTing The same dieT 29 IV BacTeria in GUTS Of The pairs of Twins 43 o boTh wellnourished 7 o boTh malnourished 50 one well nourished one malnourished In cases where Twins differed The guT flora community of gut bacteria also differed Does This show The guT flora is responsible 3o no correlation doesn39t mean causation could be other factorsy 15 322015 IV BacTeria in GUTS CriTical experimenT Samples of guT flora from malnourished and wellnourished Twins used To infecT axenic mice Mice wiTh guT flora from malnourished children lacked The abiliTy To make some vitamins and digesT complex carbohydraTes Nutrition varies depending on your guT flora So when Jason amp Jonah compeTe in This Twinkie eaTing conTesT v Nutrltlon Facts Size 1 cake Amnut tl Calories 150 Calories from Fat 41 Value Total Fat 4 Saturated Fat 25 Trans Fat I Cholesterol Sodium Total Protein 1 t lu39itamin A 0 vitamin C 0 Calcium 0 Iran Elased on aEDUD calorie diet They may eaT The same number of Twinkies buT get different numbers of calories from Them 32 WWW 16 322015 IV BacTeria in GUTS WhaT is The role of bacTeria in determining obesiTy WhaT do we know so far39 WhaT kind of daTa is The kind we39ve heard abouT so far WhaT are l 1 a7 limiTaTions of These v C daTa CorrelaTive daTa may noT accounT for criTical var39iables Imagine you saw This figure WhaT does iT say WhaT does iT mean MighT Ther39e be a more impor39TanT variable for39 each Type of evenT 33 could be in the summer Swnmmmg pool dr39ownmgs and Ice cream sales in MeTr39opolis When bOth Swlmmmg g 10 pool use and Ice cream 0 s 8 I I truck use would go up 8 6 correlation does not Q I I g 4 I mean causation E 0 2 l l E E l E k 0 I I l l I l l 939 0 200 400 600 800 1000 1200 Ice cream Tr39uck sales per39 monTh 34 17 what you eat vs what your gut flora are 322015 Correlative data may also not differentiate between cause and effect Does the gut flora in an obese person obesity causal explanation Or does obesity the different h siological state of an obese person the type of bacteria that thrive in an obese person What kind of experiment would you like to do If not in humans in mice In Sept 2013 someone did a better S39l39Udy Ridaura V K et al Science 341 1241214 2013 1 Collected microbes from guts of human twins in each case one lean one obese e 2 Inserted collection of microbes from each twin into axenic mice f a 7 3 First result mice that received floraffrom obese twin gained weight ones that received 39lean twin39 flora didn39t even though ate similar amounts 36 18 322015 In SepT 2013 someone did a beTTer S39l39Udy Ridaur39a V K et al Science 341 1241214 2013 4 Then wonder39ed whaT if mice are in the same environment 5IF and 39lean39 communiTy bacTer39ia invaded mice wiTh 39obese39 bacteria and helped pr39evenT weighT gain in The r39ecipienTs 37 So should you jusT geT a Thin housemaTe To sTay Thin I g E 6 0y quot3 hi I I l housemaTe who also eaTs The 39lean bacteria39 did not transfer or prevent weight gain when mice were fed a high faT low fiber39 dieT eg pelleTed pizza and sweeT breakfast cereal BuT DID when The dieT was low in saturated faT high in fr39uiTs and vegeTables 38 19 322015 WhoT can we conclude from This sTudy Does The sTudy suggesT o dir39ecT role of The guT flow on Tendency To gain weighT WhoT r39ole mighT dieT ploy How much can we exTr39opoloTe from mice To people 39 Role of guT bocTerio in developmenT The guT lining epiThelium does noT develop cor39r39echy in oxenic mice Among oTher39 Things The bocTer39io influence The number39 of micr39ovilli and The inTesTine s capacity to absorb nutrients Cloud of guT bocTer39io GuT epiThelium wiTh micr39ovilli 4O 20 322015 Role of gut bacteria in development Early exposure to microbes may be necessary for calibrating the immune response to microbes Desired immune response activate for pathogens not against oneself or harmless bacteria Cloud of gut bacteria Gut epithelium with microvilli 41 Role of gut bacteria in development Axenic mice produce abnormally doesn39t know what normal hiqh numbers of killer T cells caused gut bacteria are like so inflammation label them as not friendly As adults more likely to have asthma and inflammatory bowel disease 42 322015 iv Role of gu r bac reria in preven ring disease or The bes r Thing you39ve ever heard abou r feces The woman who almost died Likely con rrac red a pa rhogenic bac rerial quotOdif y infec rion Clostridium difficile in hospi ral s ray Clostridium infec rions linked wi rh overuse of cer rain an ribio rics 3 million people infec red in USyear 43 Role of gu r bac reria in preven ring disease The woman who almost died Had ongoing diarrhea cramps Si vomi ring for a year and helps in only 1525 o of pa rien rs generaHy Why migh r an ribio rics no r if Russpll aihh 322015 Role of guT bacTeria in prevenTing disease EvenTually goT a fecal Tr39ansplanT from her39 husband Tube wenT down her39 nose pasT The sTomach and inTo The small inTesTine Cured within 24 hours d Feces abouT 50 l baCTer39a The shar39ing couple Was iniTialIy The cure of IasT r39esor39T39 45 she was lacking in gut bacteria that fights Cdiff Role of guT bacTeria in prevenTing disease RecenT clinical Tr39ial published in Jan 2013 in New England J of Medicine PaTienTs wiTh C difficile infecTions 16 received bowel lavagequot fecal Tr39ansplanT 13 received bowel lavagequot anTibioTics 13 received anTibioTics alone 46 WWW 23 322015 ResulTs Percent of paTienTs cured 13 of 16 81 fecal Tr39ansplanT r39ose To 93 15 of 16 when 2 of The paTienTs had a second Tr39ansplanT 4 of 13 30 paTienTs 3 of 13 23 on bowel lavage anTibioTics on anTibioTics alone 18 of The anTibioTic Tr39eaTmenT paTienTs wer39e Then given a fecal Tr39ansplanT and iT cur39ed 15 83 of Them 47 InTerpreT The result Why did jusT adding loTs of bacteria cure The infection Likely competition with other bacteria suppressed The dominance of C difficile You will learn more abouT species inTer39acTions in lectures coming up Ecology is noT jusT ouTside of us iTs inside of us Too 48 322015 BacTeria in guTs Given whaT we39ve learned abouT The imporTance of The inTesTinal bacTeria whaT abouT anTibioTics Are They harmful Always BacTeria in guTs Think of anTibioTics as a large hamme i Tremendously miraculously effective in some cases For many years anTibioTics have alleviaTed human disease from bacterial pathogens BUT even a large hammer is noT effecTive aT pounding in a benT nail ie resisTanT bacTeria 5O 322015 AnTibioTic effecTs on guT flora And large hammers can smash more Than The nail I WhaT are The effecTs of anTibioTics The guT flora Can be harmful alThough mosle effecTs appear To be shorTlived 51 FuTure Likely manipulaTing bacTeria more good bacTeria fewer bad Some challenges IdenTifying the role of each one Many cannoT currenle be culTured 52
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