This document provides an overview of microRNAs (miRNAs) in insects. It discusses the biogenesis and evolution of miRNAs, and provides several case studies examining the roles of specific miRNAs in regulating development and physiology in various insect species. Some key points covered include how plant miRNAs in larval food can regulate caste development in honey bees, the differential expression of miRNA pathway genes during development in Helicoverpa armigera, and studies on the effects of depleting particular miRNAs in Drosophila and Blattella germanica. The document concludes with a discussion of the roles of miRNAs in insect development, physiology and evolution.

1. WELCOME
1

2. Micro RNA’s in insects
Kavyashree, B. A.
III Ph.D.
PA1TAH079

3. 3
Glimpse through
History of Nucleic acids
Introduction
Biogenesis of m-RNA
Evolution of m-RNA
Case studies
Conclusion

4. A three-stage history of nucleic acid study
Chao and Chen (2020) 4

5. MicroRNAs (miRNAs) - Non-coding RNAs that function in gene
regulatory processes in plants and animals
In insects, miRNAs have been shown to regulate a variety of
physiological processes throughout insect development
Introduction
5

6. MicroRNA - Biogenesis in insects
Keira et al. (2015)
6

7. The molecular hallmarks of lin-4, the founding member of the microRNA family
Lin and Gregory (2004) 7

8. microRNAs Function
Caenorhabditis elegans
lin-4 Regulation of developmental transition between the first two larval stages, L1
and L2
let-7 Regulation of developmental transition between the last larval stage (L4) and
the adult stage
lsy-6 Determination of left/right asymmetry of neuronal development
Drosophila melanogaster
Bantam Promotion of cell proliferation and suppression of apoptosis
miR-14 Suppression of apoptosis and regulation of fat metabolism
Mus musculus
miR-181 Promotion of haematopoietic differentiation towards the B-cell lineage
miR-196 -
Zea mays
miR-166 Regulation of leaf morphogenesis
MicroRNAs with functions
Lin and Gregory (2004) 8

9. MiRNAs during insect evolution
Xavier (2017) 9

10. Zhu et al. (2017) 10
Plant microRNAs in Larval food regulate honey caste
development

11. Contd.
11
Zhu et al. (2017)
Comparison of the levels of plant and animal miRNAs

12. Contd.
12
Zhu et al. (2017)
Comparison of the levels of plant and animal miRNAs

13. Rahimpour et al. (2019) 13
Differential expression of microRNA pathway core genes during
development of insects
Helicoverpa armigera

14. Dynamic expression of miRNA pathway core genes during development of
H. armigera
14
Rahimpour et al. (2019)
Drosha

15. Expression of miRNA pathway core genes in different tissues of H. armigera
Contd.
Rahimpour et al. (2019)
Loquacious
Exportin-5

16. 16
Effect of silencing dicer 1 in Helicoverpa armigera

17. Antisense-mediated depletion reveals essential and specific
functions of Micro RNAs in Drosophila development
Leaman et al. (2005) 17
Injection of 2OM-ORNs

18. Leaman et al. (2005) 18
miR-9 depletion affects cellularization

19. Leaman et al. (2005) 19
miR-31 and miR-310 afffects segmentation

20. Leaman et al. (2005) 20
Depletion of miR-2 family causing apoptosis

21. Blood meal induced microRNA regulates development and immune
associated genes in the dengue mosquito vector, Aedes aegypti
Hussain et al. (2013) 21
Northern blot hybridization of miRNAs differentially
expressed in blood fed mosquitoes

22. Contd.
Hussain et al. (2013)
22
Northern blot hybridization of miRNAs in blood fed mosquitoes

23. Contd.
Hussain et al. (2013) 23
Immune related genes cactus and REL1 are affected after blood feeding

24. MicroRNA-dependent metamorphosis in hemimetabolan insects
Eva and Xavier (2009)
Blattella germanica Dicer-1 (BgDcr1) and effects of RNAi
24

25. Eva and Xavier (2009)25

26. Subtle roles of microRNAs let-7, miR-100 and miR-125 on wing
morphogenesis in hemimetabolan metamorphosis
Rubio and Xavier (2013)
26

27. Rubio and Xavier (2013) 27
Effects of let-7, miR-100 and miR-125 depletion in B. germanica

28. The Drosophila microRNA iab-4 causes a dominant homeotic
transformation of halteres to wings
Matthew et al. (2005)
28

29. CONCLUSION
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30. 30