Liz Dennis

Last updated

Elizabeth Dennis

AC
Born (1943-12-10) 10 December 1943 (age 80)
Sydney, Australia
NationalityAustralian
Education MLC 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

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]

Contents

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, 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

Related Research Articles

<i>Arabidopsis thaliana</i> Model plant species in the family Brassicaceae

Arabidopsis thaliana, the thale cress, mouse-ear cress or arabidopsis, is a small plant from the mustard family (Brassicaceae), native to Eurasia and Africa. Commonly found along the shoulders of roads and in disturbed land, it is generally considered a weed.

<span class="mw-page-title-main">Vernalization</span> Induction of a plants flowering process

Vernalization is the induction of a plant's flowering process by exposure to the prolonged cold of winter, or by an artificial equivalent. After vernalization, plants have acquired the ability to flower, but they may require additional seasonal cues or weeks of growth before they will actually do so. The term is sometimes used to refer to the need of herbal (non-woody) plants for a period of cold dormancy in order to produce new shoots and leaves, but this usage is discouraged.

<span class="mw-page-title-main">Antisense RNA</span>

Antisense RNA (asRNA), also referred to as antisense transcript, natural antisense transcript (NAT) or antisense oligonucleotide, is a single stranded RNA that is complementary to a protein coding messenger RNA (mRNA) with which it hybridizes, and thereby blocks its translation into protein. The asRNAs have been found in both prokaryotes and eukaryotes, and can be classified into short and long non-coding RNAs (ncRNAs). The primary function of asRNA is regulating gene expression. asRNAs may also be produced synthetically and have found wide spread use as research tools for gene knockdown. They may also have therapeutic applications.

<span class="mw-page-title-main">Repressor</span> Sort of RNA-binding protein in molecular genetics

In molecular genetics, a repressor is a DNA- or RNA-binding protein that inhibits the expression of one or more genes by binding to the operator or associated silencers. A DNA-binding repressor blocks the attachment of RNA polymerase to the promoter, thus preventing transcription of the genes into messenger RNA. An RNA-binding repressor binds to the mRNA and prevents translation of the mRNA into protein. This blocking or reducing of expression is called repression.

Florigens are proteins capable of inducing flowering time in angiosperms. The prototypical florigen is encoded by the FT gene and its orthologs in Arabidopsis and other plants. Florigens are produced in the leaves, and act in the shoot apical meristem of buds and growing tips.

Polycomb-group proteins are a family of protein complexes first discovered in fruit flies that can remodel chromatin such that epigenetic silencing of genes takes place. Polycomb-group proteins are well known for silencing Hox genes through modulation of chromatin structure during embryonic development in fruit flies. They derive their name from the fact that the first sign of a decrease in PcG function is often a homeotic transformation of posterior legs towards anterior legs, which have a characteristic comb-like set of bristles.

The MADS box is a conserved sequence motif. The genes which contain this motif are called the MADS-box gene family. The MADS box encodes the DNA-binding MADS domain. The MADS domain binds to DNA sequences of high similarity to the motif CC[A/T]6GG termed the CArG-box. MADS-domain proteins are generally transcription factors. The length of the MADS-box reported by various researchers varies somewhat, but typical lengths are in the range of 168 to 180 base pairs, i.e. the encoded MADS domain has a length of 56 to 60 amino acids. There is evidence that the MADS domain evolved from a sequence stretch of a type II topoisomerase in a common ancestor of all extant eukaryotes.

The family of heterochromatin protein 1 (HP1) consists of highly conserved proteins, which have important functions in the cell nucleus. These functions include gene repression by heterochromatin formation, transcriptional activation, regulation of binding of cohesion complexes to centromeres, sequestration of genes to the nuclear periphery, transcriptional arrest, maintenance of heterochromatin integrity, gene repression at the single nucleosome level, gene repression by heterochromatization of euchromatin, and DNA repair. HP1 proteins are fundamental units of heterochromatin packaging that are enriched at the centromeres and telomeres of nearly all eukaryotic chromosomes with the notable exception of budding yeast, in which a yeast-specific silencing complex of SIR proteins serve a similar function. Members of the HP1 family are characterized by an N-terminal chromodomain and a C-terminal chromoshadow domain, separated by a hinge region. HP1 is also found at some euchromatic sites, where its binding can correlate with either gene repression or gene activation. HP1 was originally discovered by Tharappel C James and Sarah Elgin in 1986 as a factor in the phenomenon known as position effect variegation in Drosophila melanogaster.

Evolutionary developmental biology (evo-devo) is the study of developmental programs and patterns from an evolutionary perspective. It seeks to understand the various influences shaping the form and nature of life on the planet. Evo-devo arose as a separate branch of science rather recently. An early sign of this occurred in 1999.

<span class="mw-page-title-main">Caroline Dean</span> British botanist

Dame Caroline Dean is a British plant scientist working at the John Innes Centre. She is focused on understanding the molecular controls used by plants to seasonally judge when to flower. She is specifically interested in vernalisation — the acceleration of flowering in plants by exposure to periods of prolonged cold. She has also been on the Life Sciences jury for the Infosys Prize from 2018.

Flowering Locus C (FLC) is a MADS-box gene that in late-flowering ecotypes of the plant Arabidopsis thaliana is responsible for vernalization. In a new seedling FLC is expressed, which prevents flowering. Upon exposure to cold, less FLC is expressed, and flowering becomes possible. FLC is extensively regulated through epigenetic modifications and transcriptional control.

<span class="mw-page-title-main">Nagendra Kumar Singh</span> Indian agricultural scientist (born 1958)

Nagendra Kumar Singh is an Indian agricultural scientist. He is presently a National Professor Dr. B.P. Pal Chair and JC Bose National Fellow at ICAR-National Institute for Plant Biotechnology, Indian Agricultural Research Institute, New Delhi. He was born in a small village Rajapur in the Mau District of Uttar Pradesh, India. He is known for his research in the area of plant genomics, genetics, molecular breeding and biotechnology, particularly for his contribution in the decoding of rice, tomato, wheat, pigeon pea, jute and mango genomes and understanding of wheat seed storage proteins and their effect on wheat quality. He has made significant advances in comparative analysis of rice and wheat genomes and mapping of genes for yield, salt tolerance and basmati quality traits in rice. He is one of the highest cited agricultural scientists from India for the last five years.

Richard Arthur is a professor of biochemistry and genetics at the University of Wisconsin-Madison. He got his bachelor's degree in biology at Pennsylvania State University. He went on to receive his PhD in biochemistry at Indiana University in 1982 and did post doctoral research at the University of Washington. Amasino's research focuses on plants and how plants know when to flower. In 2006 he was elected to the National Academy of Sciences.

Elizabeth Jean Finnegan FAA is an Australian botanist who researches plant flowering processes and epigenetic regulation in plants. She currently works at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) as a senior scientist, leading research on the "Control of Floral Initiation", part of the CSIRO Agriculture Flagship.

Plants depend on epigenetic processes for proper function. Epigenetics is defined as "the study of changes in gene function that are mitotically and/or meiotically heritable and that do not entail a change in DNA sequence". The area of study examines protein interactions with DNA and its associated components, including histones and various other modifications such as methylation, which alter the rate or target of transcription. Epi-alleles and epi-mutants, much like their genetic counterparts, describe changes in phenotypes due to epigenetic mechanisms. Epigenetics in plants has attracted scientific enthusiasm because of its importance in agriculture.

LUX or Phytoclock1 (PCL1) is a gene that codes for LUX ARRHYTHMO, a protein necessary for circadian rhythms in Arabidopsis thaliana. LUX protein associates with Early Flowering 3 (ELF3) and Early Flowering 4 (ELF4) to form the Evening Complex (EC), a core component of the Arabidopsis repressilator model of the plant circadian clock. The LUX protein functions as a transcription factor that negatively regulates Pseudo-Response Regulator 9 (PRR9), a core gene of the Midday Complex, another component of the Arabidopsis repressilator model. LUX is also associated with circadian control of hypocotyl growth factor genes PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and PHYTOCHROME INTERACTING FACTOR 5 (PIF5).

<span class="mw-page-title-main">Julie Law</span> American molecular and cellular biologist

Julie Law is an American molecular and cellular biologist. Law's pioneering work on DNA methylation patterns led to the discovery of the role of the CLASSY protein family in DNA methylation. Law is currently an associate professor at the Salk Institute for Biological Studies.

Michel Delseny is director of research emeritus at the CNRS and a member of the French Academy of sciences.

Jian-Kang Zhu is a plant scientist, researcher and academic. He is a Senior Principal Investigator in the Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences (CAS). He is also the Academic Director of CAS Center of Excellence in Plant Sciences.

<span class="mw-page-title-main">RNA-directed DNA methylation</span> RNA-based gene silencing process

RNA-directed DNA methylation (RdDM) is a biological process in which non-coding RNA molecules direct the addition of DNA methylation to specific DNA sequences. The RdDM pathway is unique to plants, although other mechanisms of RNA-directed chromatin modification have also been described in fungi and animals. To date, the RdDM pathway is best characterized within angiosperms, and particularly within the model plant Arabidopsis thaliana. However, conserved RdDM pathway components and associated small RNAs (sRNAs) have also been found in other groups of plants, such as gymnosperms and ferns. The RdDM pathway closely resembles other sRNA pathways, particularly the highly conserved RNAi pathway found in fungi, plants, and animals. Both the RdDM and RNAi pathways produce sRNAs and involve conserved Argonaute, Dicer and RNA-dependent RNA polymerase proteins.

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. 1 2 3 4 5 6 7 8 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.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.