Liz Dennis

Elizabeth Salisbury Dennis AC FTSE FAA (born 10 December 1943) is an Australian scientist working mainly in the area of plant molecular biology. She is currently a chief scientist at the plant division of CSIRO Canberra. She was elected a Fellow of the Australian Academy of Technological Sciences and Engineering (FTSE) in 1987, and the Australian Academy of Science in 1995. She jointly received the inaugural Prime Minister's Science Prize together with Professor Jim Peacock in 2000 for her outstanding achievements in science and technology.[1][2][3]

Elizabeth Dennis

AC
Born (1943-12-10) 10 December 1943
Sydney, Australia
NationalityAustralian
EducationMLC School
University of Sydney
AwardsPrime Minister's Prize for Science (2000)
Scientific career
FieldsPlant molecular biology
InstitutionsAlbert Einstein College of Medicine, New York
University of Papua New Guinea
Australian National University
CSIRO

Personal background

Early years and education

Elizabeth Salisbury Dennis, known as Liz Dennis, was born in Sydney, New South Wales, Australia, on 10 December 1943. In her school years at MLC School in Sydney[4][5] she was inspired by the life of Marie Curie and decided to become a scientist. She completed a Bachelor of Science in chemistry and biochemistry at the University of Sydney (1964), and focused on DNA replication in bacteria during her Ph.D entitled "Studies on the Bacillus subtilis genome" (awarded in 1968).[6]

Career posts

Dennis went on to study the replication of the yeast mitochondrial DNA during her post-doctoral years in the laboratory of Dr Julius Marmur in New-York (1968–1970).

She then spent four years in Papua New Guinea where she became a lecturer in Microbiology and Biochemistry (1970–1972) and Senior Lecturer in Biochemistry (1974–1976). At this time, she was studying chromosomes and DNA of native rodents, and wrote a guide on the rodents of Papua New Guinea together with Jim Menzies, the zoologist she worked with. In 1972, she was appointed as a Research Scientist at the CSIRO Division of Plant Industry in Canberra, promoted to the grade of Chief Research Scientist in 1991 and subsequently became CSIRO Fellow in 2001.

Meanwhile, she had the chance to visit the Biochemistry Department of Stanford University thanks to a Fulbright Fellowship and worked in the laboratory of the Nobel Prize winner Paul Berg (1982–83). She also visited Australian National University in 1991 and became Adjunct Professor there between 1992 and 1998.[7]

Research

With a strong interest in plant gene expression and regulation, Prof Elizabeth Dennis studied plant development using molecular approaches and was involved in mapping plant genomes.

Plant response to hypoxia

Her early work in the plant field was dedicated to the molecular responses of plants to hypoxia and waterlogging, i.e. which genes are switched on by low oxygen levels. She, together with her collaborators, cloned the gene encoding the enzyme alcohol dehydrogenase[8][9] and identified the regulatory motifs controlling its expression in response to the lack of oxygen.[10][11] She also was involved in the research showing that all plants contain haemoglobin and that this molecule protects the plant against oxygen deprivation stress [12][13]

Plant flowering

Understanding how flowering is regulated in plants is another research area she successfully tackled. Her team worked on genes that represses flowering (FLC and FLF, FLOWERING LOCUS C and FLOWERING LOCUS F) and showed that their effect is down-regulated by vernalisation.[14] They also observed that a reduction in DNA methylation plays an important role in this response to cold.[15][16][17] The mechanism involves histone de-acetylation at FLC and methylation of FLC in vernalised plants, both reactions performed by a single protein complex.[18][19][20][21]

Molecular bases of heterosis

Her more recent work is dedicated to understanding the phenomenon of heterosis or hybrid vigour, i.e. the increased biomass of hybrids as compared with their parents. Factors involved in this regulation are small RNA molecules (sRNA), DNA methylation and histone modification.[22][23]

Honours

Past
  • Chairman of the Multinational Arabidopsis Genome Project
  • President of the Australian Society of Biochemistry and Molecular Biology (1992–94)[24]
  • Director of the International Society of Plant Molecular Biology from 1990–93[24]

References
  1. "Dennis, Elizabeth Salisbury (1943 - )". Biographical entry. Encyclopaedia of Australian Science.
  2. "Dennis, Elizabeth Salisbury, FAA, FTSE (1943-)". trove.nla.gov.au.
  3. "Dennis, Elizabeth Salisbury (1943 - )". The Encyclopaedia of Women & Leadership in Twentieth-Century Australia. Australian Women's Archives Project. 2 May 2014.
  4. "MLC School Alumni in Science". www.mlcsyd.nsw.edu.au. MLC School Sydney. Retrieved 28 March 2017.
  5. Bhathal, Ragbir (1999). Profiles : Australian women scientists. National Library of Australia. p. 34. ISBN 978-0-642-10701-5.
  6. Elizabeth Dennis, CSIROpedia
  7. Frank Gibson (2000). "Dr Liz Dennis, plant biologist". Interviews with Australian Scientists. Australian Academy of Science.
  8. Dennis, E.S., et al., Molecular analysis of the alcohol dehydrogenase (Adh1) gene of maize. Nucleic Acids Research, 1984. 12(9): p. 3983-4000
  9. Dennis, E.S., et al., Molecular analysis of the alcohol dehydrogenase 2 (Adh2) gene of maize. Nucleic Acids Research, 1985. 13(3): p. 727-43
  10. Ellis, J.G., et al., Maize Adh-1 promoter sequences control anaerobic regulation: addition of upstream promoter elements from constitutive genes is necessary for expression in tobacco. The EMBO Journal, 1987. 6(1): p. 11-6
  11. Dolferus, R., et al., Differential interactions of promoter elements in stress responses of the Arabidopsis Adh gene. Plant physiology, 1994. 105(4): p. 1075-87
  12. Appleby, C.A., et al., A Role for Hemoglobin in All Plant-Roots. Plant Cell and Environment, 1988. 11(5): p. 359-367
  13. Bogusz, D., et al., Functioning Hemoglobin Genes in Non-Nodulating Plants. Nature, 1988. 331(6152): p. 178-180
  14. Sheldon, C.C., et al., The FLF MADS box gene: a repressor of flowering in Arabidopsis regulated by vernalization and methylation. The Plant Cell, 1999. 11(3): p. 445-58
  15. Sheldon, C.C., et al., Resetting of FLOWERING LOCUS C expression after epigenetic repression by vernalization. Proceedings of the National Academy of Sciences of the United States of America, 2008. 105(6): p. 2214-9
  16. Finnegan, E.J., et al., A cluster of Arabidopsis genes with a coordinate response to an environmental stimulus. Current Biology, 2004. 14(10): p. 911-6
  17. Sheldon, C.C., et al., Different regulatory regions are required for the vernalization-induced repression of FLOWERING LOCUS C and for the epigenetic maintenance of repression. The Plant Cell, 2002. 14(10): p. 2527-37
  18. Wood, C.C., et al., The Arabidopsis thaliana vernalization response requires a polycomb-like protein complex that also includes VERNALIZATION INSENSITIVE 3. Proceedings of the National Academy of Sciences of the United States of America, 2006. 103(39): p. 14631-6
  19. Helliwell, C.A., et al., The Arabidopsis FLC protein interacts directly in vivo with SOC1 and FT chromatin and is part of a high-molecular-weight protein complex. The Plant Journal, 2006. 46(2): p. 183-92
  20. Trevaskis, B., et al., The molecular basis of vernalization-induced flowering in cereals. Trends in plant science, 2007. 12(8): p. 352-7
  21. Dennis, E.S. and W.J. Peacock, Epigenetic regulation of flowering. Current Opinion in Plant Biology, 2007. 10(5): p. 520-7
  22. Groszmann, M., et al., Intraspecific Arabidopsis hybrids show different patterns of heterosis despite the close relatedness of the parental genomes. Plant physiology, 2014
  23. Greaves, I.K., et al., Inheritance of Trans Chromosomal Methylation patterns from Arabidopsis F1 hybrids. Proceedings of the National Academy of Sciences of the United States of America, 2014. 111(5): p. 2017-22
  24. Ward, Colin (14 February 2011). "Elizabeth Salisbury (Liz) Dennis". CSIROpedia. Retrieved 31 March 2022.
  25. "Liz Dennis". Australian Academy of Science. Retrieved 31 March 2022.
  26. "Lemberg Medal". Australian Society for Biochemistry and Molecular Biology. Retrieved 31 March 2022.
  27. "Dr Elizabeth Salisbury Dennis". It's An Honour. Retrieved 18 December 2020.
  28. "Elizabeth S. Dennis". National Academy of Sciences. Retrieved 18 December 2022.
  29. "2022 awardees". Australian Academy of Science. Retrieved 31 March 2022.
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