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NROC34 Lec 5.docx

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Karen Williams

NROC34 Lec 5 - Pub med, scopist, med of science - Stuff in pub med is older and in process - Peer review is a subset of academic o All pree reviewed are academic o Not all academic are peer reviewed - Go with peer reviewed - Medline and pubmed are similar - Medline is easier because UofT pays for it - Pubmed – turn on advance search - Mesh = medical subject headings - On pubmed – can limit to reviews – turn off critical trial - Can limit by year - When searching databases – not searching the whole text so if the word neuroethology (if searching) is in the article it will not show up immediately o When searching stuff it is only the databases parts of text - Web of science (web of knowledge – umbrella database) o Change everything to topic o Useful: gives a list of broad categories from which articles are coming - Scopist o Advanced search o Put terms in brackets  (sdjsfhjad) and (akjsdkfj) - Refworks – on utsc library site o Makes a folder of citations together o Once you have citations in refwork , can make bibliography for you o Need to make account – free for uoft o In library homepage under research – tools and utilities – manage citations Cats and mice - Generally many people like sweet - Same articles are fruit fly foraging - Talking about taste receptors - Food vs poison in drosophila - Octanoic acid and avoidance of merinda fruit - Octanoic acid causes taste and poison of merinda fruit Olfactory receptors and glomeruli - Or22a - In drosophila melanogaster there are differences from sechelia - The ab1 cells may express the or85a receptor usually found in melanogaster - DM2 is larger in sechelia than in melanogaster o Sechelia for 22A is different from the one in melanogaster - Sequence differences say something about the genetic similarity between these species Comparative genomics - Can do when we know there is a behavioural difference between flies that like morinda fruit and those that don’t - Compare OR and GR o Are important in CHEMORECEPTION  Lipophilic dissolving in oil  Or hydrophilic dissolving in water - Sechellia has fewer OR and GR than melanogaster - Olfactory binding proteins (obp) are not much difference BUT there is one fewer in sechellia than in melanogaster An Oviposition Assay How flies taste - The oviposition assay is a taste-based assay because flies have gustatory R at their ovipositor - Who prefers to taste morinda fruit? Melanogaster prefers to oviposit as the simulant on REGULAR food - Sechellia prefers to oviposit on morinda fruit o Likely because they detected the taste of morinda fruit - Can use this assay to ask… if we reduce the expression of something do we express the avoidance of morinda fruit Loss of octanoic acid detection reduces avoidance of Morinda fruit - Prediction: if a loss of obp56e influences the avoidance of morinda fruit then knocking expression of obp56e reduces the avoidance of morinda fruit o Can knock down expression by expressing RNAi - Results: o No silencing of obp56e – does not reduce avoidance  98% avoided Morinda fruit o When knocking obp56e –  loss of this caused decreased avoidance of morinda fruit  85% avoided Morinda fruit Taste and olfaction in mammals - Mammalian OR and GRs are organized in the same way but do NOT share sequence similarity - In mammals: o Olfactory organs detect volatile lipophilic molecules o Taste organs typically detect hydrophilic non-volatile molecules such as those found in food Do cats and mice taste sweet? Taste in flies and mice - For taste – looking at the tongue - In drosophila, have the head, labellum, etc - Tongue of a mouse and different taste receptors - Generally, taste with our tongue - Difference between smelling coffee and tasting coffee? - In mammals there are more specialization o Food we prefer are the ones that give high caloric content – sweet food - Have an ability to tell difference between ripe and unripe fruit o Ability to detect ripeness = ability to detect sweetness - Detection of ethanol in odours Rats: taste and learning - Taste aversion learning: - If you pair bar pressing with sweet food BUT if pairing bar pressing with a bad food  rat learns to not press the bar - Pairing bar with shock or loud sound – rats do not learn to not bar press for sucrose o Not usually paired together Cats and mice Mice taste saccharin: variation - X axis – sodium saccharin intake = solid line o Dashed line = water intake - P = concentration they used - One that prefers taste of saccharin  - Crossed mice and looked at F1 - Taster mice (B) and non-taster mice (d) cross gave the cross - Taster is dominant if b x d cross are more like b - Can track tasting from one phenotype from one gen to the next Mice taste saccharin: single locus? - Simplest model of a single gene is likely in this case Mouse Tas1r3 (T1R3) in taste receptor cells - Locus for tasting saccharin was also Tas1R - Took a piece of DNA – if that piece was where the sac locus was (tasting sac). Putting into mouse that didn’t taste and express that transgene, should be able to convert taster mouse into a non-taster mouse - BGH = transgene - UTR giving location of expression – where taste buds are (parts of the tongue) - Transgene is expressed in the taste buds – where we’d expect it to be expressed Tas1r3 is Sac - Test taste in saccharin vs sucrose - Difference: tastes sweeter than sucrose o Find saccharin in diet drinks - Use artificial sweetener because it is not metabolized – major difference = caloric metabolic information in the body - Cannot metabolize saccharin - If just taste, both taste sweet – should get same response - If is taste and increase in insulin then should get a difference between sucrose and saccharin - Unfilled circle = regular non-taster mice vs.
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