intro

Introduction

The olfactory gene is mainly seen to be to main culprit behind a mammalians ability to smell. It is in fact on of the largest genes found in mammals (Young 2003). Mice have over 1,500 olfactory genes within them (Young 2003), but because of alternative splicing they do not all aid in a mammal’s ability to smell. The equivalent sequence in humans has been found in tissue unrelated to olfactory tissues such as taste tissues and testis tissue (Young 2003). These no not in any form aid with smell, but rather they have different functions altogether within these alternative tissues. Within the testis, olfactory genes are used as a form of guidance for a sperm cell to reach the egg (Young 2013).

Olfactory genes differ between mice and humans in that mice have over 1,500 olfactory receptor genes whereas humans only contain 851 (Verbeurgt 2014). They both share a commonality in that over 50% of the gene is nonfunctional (Verbeurgt 2014).

It has been found that the olfactory gene aids in social communication within fire ants. Alternative slicing within the species yield different haplotypes in different hierarchy levels. (Cohanim 2018). This means that each ant can differentiate between their queen and the other worker ants using chemicals based on the expression of the gene. This is done because olefactory genes within insects contain chemosensory binding proteins (Yuan 2019). Alternative splicing of olfactory genes also is the primary gene responsible for mating within insects (Yuan 2019) female and male insects secrete different chemicals that are a product of the two alternative spliced variants in the gene. This allows for the male and female insects to detect chemical odorants of the opposite sex. Males will follow the chemical odorants found within the female insects pheromones (Gu 2104)

Hypothesis

With the use of alternative splicing of the olfactory genes, many different functions of the gene can be expressed such as aid in mating, hierarchy, and orientation.

References

Cohanim AB, Amsalem E, Saad R, Shoemaker D, Privman E. 2018. Evolution of olfactory functions on fire ant social chromosome. Genome Biol Evol. 10(11): 2947-2960.

DeMaria S, Berke AP, Van Name E, Heravian A, Ferreira T Ngai J. 2013. Role of a ubiquitously expressed receptor in the vertebrate olfactory system. J Neurosci. 33(38): 15235-15247.

Gu SH, Sun L, Yang RN, Wu KM, Guo YY, Li XC, Zhou JJ, Zhang YJ. 2014. Molecular characterization and differential expression of olfactory genes in the antennae of the black cutworm moth agrotis ipsilon. PLoS One. 9(8): 103420

Verbeurgt C, Wilkin F, Tarabichi M, Gregoire F, Dumont JE, Chatelain P. 2014. Profiling of olfactory receptor gene expression in whole human olfactory mucosa. PLoS One.9(5): 96333.

Yuan H, Chang H, Zhao L, Yang C, Huang Y. 2019. Sex- and tissue-specific transcriptome analyses and expression profiling of olfactory-related genes in ceracris nigricornis walker (orthoptera: Acrididae). BMC Genomics. 20(1): 808.

Young J, Shykind B, Lane R, Tonnes-Priddy L, Ross J, Walker M, Williams E, Trask B. 2003. Odorant receptor expressed sequence tags demonstrate olfactory expression of over 400 genes, extensive alternate splicing and unequal expression levels. Genome Biology.4(11): 71.