I am a research associate in the Seafood Safety: Marine Algal Biotoxins group at the C3: Climate Change Cluster. My research interest lies in the evolution, ecology, and systematics of marine microbial eukaryotes, particularly species that are detrimental to marine ecosystems by producing biotoxins and causing harmful algal blooms.
After being awarded my Ph.D. in 2018 on the diversity and its functional significance in benthic microbial eukaryotes, I am currently working on developing novel genetic tools for biotoxin monitoring based on the unique genetic processes of dinoflagellates and diatoms, with the motivation to shape profitability and sustainability in the Australian aquaculture industry.
- Australian Marine Sciences Association (AMSA)
- Australasian Society of Phycology and Botany (ASPAB) (Webmaster 2015-Current)
- Ecological Society of Australia (ESA)
- International Society for the Study of Harmful Algae (ISSHA)
- Society of Molecular Biology and Evolution (SMBE)
- Environmental Microbiology
- Harmful Algae
- Journal of Experimental Marine Biology and Ecology
- Marine Pollution Bulletin
- MDPI Toxins
- The European Journal of Phycology
Can supervise: YES
- Harmful Algae
- Evolution and ecology of biotoxins
- Systematics and taxonomy of marine microbial eukaryotes
- Ecophysiological trait diversity
- Microbial Ecology
- Molecular Ecology
- Cell Biology and Genetics
- Geological Processes
Verma, A, Barua, A, Ruvindy, R, Savela, H, Ajani, PA & Murray, SA 2019, 'The Genetic Basis of Toxin Biosynthesis in Dinoflagellates.', Microorganisms, vol. 7, no. 8.View/Download from: UTS OPUS or Publisher's site
In marine ecosystems, dinoflagellates can become highly abundant and even dominant at times, despite their comparatively slow growth rates. One factor that may play a role in their ecological success is the production of complex secondary metabolite compounds that can have anti-predator, allelopathic, or other toxic effects on marine organisms, and also cause seafood poisoning in humans. Our knowledge about the genes involved in toxin biosynthesis in dinoflagellates is currently limited due to the complex genomic features of these organisms. Most recently, the sequencing of dinoflagellate transcriptomes has provided us with valuable insights into the biosynthesis of polyketide and alkaloid-based toxin molecules in dinoflagellate species. This review synthesizes the recent progress that has been made in understanding the evolution, biosynthetic pathways, and gene regulation in dinoflagellates with the aid of transcriptomic and other molecular genetic tools, and provides a pathway for future studies of dinoflagellates in this exciting omics era.
Verma, A, Kohli, GS, Harwood, DT, Ralph, PJ & Murray, SA 2019, 'Transcriptomic investigation into polyketide toxin synthesis in Ostreopsis (Dinophyceae) species.', Environmental microbiology.View/Download from: Publisher's site
In marine ecosystems, dinoflagellates can become highly abundant and even dominant at times, despite their comparatively slow growth. Their ecological success may be related to their production of complex toxic polyketide compounds. Ostreopsis species produce potent palytoxin-like compounds (PLTX), which are associated with human skin and eye irritations, and illnesses through the consumption of contaminated seafood. To investigate the genetic basis of PLTX-like compounds, we sequenced and annotated transcriptomes from two PLTX- producing Ostreopsis species; O. cf. ovata, O. cf. siamensis, one non-PLTX producing species, O. rhodesae, and compared them to a close phylogenetic relative and non-PLTX producer, Coolia malayensis. We found no clear differences in the presence or diversity of ketosynthase and ketoreductase transcripts between PLTX producing and non-producing Ostreopsis and Coolia species, as both groups contained >90 and >10 phylogenetically diverse ketosynthase and ketoreductase transcripts, respectively. We report for the first-time type I single-, multi-domain polyketide synthases (PKSs), and hybrid non-ribosomal peptide synthase/PKS transcripts from all species. The long multi-modular PKSs were insufficient by themselves to synthesize the large complex polyether backbone of PLTX-like compounds. This implies that numerous PKS domains, including both single and multi-, work together on the biosynthesis of PLTX-like and other related polyketide compounds. This article is protected by copyright. All rights reserved.
Unnikrishnan, A, Vo, ANQ, Pickford, R, Raftery, MJ, Nunez, AC, Verma, A, Hesson, LB & Pimanda, JE 2018, 'AZA-MS: a novel multiparameter mass spectrometry method to determine the intracellular dynamics of azacitidine therapy in vivo.', Leukemia, vol. 32, no. 4, pp. 900-910.View/Download from: UTS OPUS or Publisher's site
The cytidine analogue, 5-azacytidine (AZA; 5-AZA-cR), is the primary treatment for myelodysplastic syndrome and chronic myelomonocytic leukaemia. However, only ~50% of treated patients will respond to AZA and the drivers of AZA resistance in vivo are poorly understood. To better understand the intracellular dynamics of AZA upon therapy and decipher the molecular basis for AZA resistance, we have developed a novel, multiparameter, quantitative mass spectrometry method (AZA-MS). Using AZA-MS, we have accurately quantified the abundance of the ribonucleoside (5-AZA-cR) and deoxyribonucleoside (5-AZA-CdR) forms of AZA in RNA, DNA and the cytoplasm within the same sample using nanogram quantities of input material. We report that although AZA induces DNA demethylation in a dose-dependent manner, it has no corresponding effect on RNA methylation. By applying AZA-MS to primary bone marrow samples from patients undergoing AZA therapy, we have identified that responders accumulate more 5-AZA-CdR in their DNA compared with nonresponders. AZA resistance was not a result of impaired AZA metabolism or intracellular accumulation. Furthermore, AZA-MS has helped to uncover different modes of AZA resistance. Whereas some nonresponders fail to incorporate sufficient 5-AZA-CdR into DNA, others incorporate 5-AZA-CdR and effect DNA demethylation like AZA responders, but show no clinical benefit.
Ajani, PA, Verma, A, Lassudrie, M, Doblin, MA & Murray, SA 2018, 'A new diatom species P. hallegraeffii sp. nov. belonging to the toxic genus Pseudo-nitzschia (Bacillariophyceae) from the East Australian Current.', PloS one, vol. 13, no. 4, pp. e0195622-e0195622.View/Download from: UTS OPUS or Publisher's site
A new species belonging to the toxin producing diatom genus Pseudo-nitzschia, P. hallegraeffii sp. nov., is delineated and described from the East Australian Current (EAC). Clonal cultures were established by single cell isolation from phytoplankton net hauls collected as part of a research expedition in the EAC region in 2016 on the RV Investigator. Cultures were assessed for their morphological and genetic characteristics, their sexual compatibility with other Pseudo-nitzschia species, and their ability to produce domoic acid. Light and transmission electron microscopy revealed cells which differed from their closest relatives by their cell width, rows of poroids, girdle band structure and density of band straie. Phylogenetic analyses based on sequencing of nuclear-encoded ribosomal deoxyribonucleic acid (rDNA) regions showed this novel genotype clustered within the P. delicatissima complex, but formed a discrete clade from its closest relatives P. dolorosa, P. simulans, P. micropora and P. delicatissima. Complementary base changes (CBCs) were observed in the secondary structure of the 3' nuclear ribosomal transcribed spacer sequence region (ITS2) between P. hallegraeffii sp. nov. and its closest related taxa, P. simulans and P. dolorosa. Under laboratory conditions, and in the absence of any zooplankton cues, strains of P. hallegraeffii sp. nov. did not produce domoic acid (DA) and were not sexually compatible with any other Pseudo-nitzschia clones tested. A total of 18 Pseudo-nitzschia species, including three confirmed toxigenic species (P. cuspidata, P. multistriata and P. australis) have now been unequivocally confirmed from eastern Australia.
Kretzschmar, AL, Verma, A, Harwood, T, Hoppenrath, M & Murray, S 2017, 'Characterization of Gambierdiscus lapillus sp. nov. (Gonyaulacales, Dinophyceae): a new toxic dinoflagellate from the Great Barrier Reef (Australia).', Journal of phycology, vol. 53, no. 2, pp. 283-297.View/Download from: UTS OPUS or Publisher's site
Gambierdiscus is a genus of benthic dinoflagellates found worldwide. Some species produce neurotoxins (maitotoxins and ciguatoxins) that bioaccumulate and cause ciguatera fish poisoning (CFP), a potentially fatal food-borne illness that is common worldwide in tropical regions. The investigation of toxigenic species of Gambierdiscus in CFP endemic regions in Australia is necessary as a first step to determine which species of Gambierdiscus are related to CFP cases occurring in this region. In this study, we characterized five strains of Gambierdiscus collected from Heron Island, Australia, a region in which ciguatera is endemic. Clonal cultures were assessed using (i) light microscopy; (ii) scanning electron microscopy; (iii) DNA sequencing based on the nuclear encoded ribosomal 18S and D8-D10 28S regions; (iv) toxicity via mouse bioassay; and (v) toxin profile as determined by Liquid Chromatography-Mass Spectrometry. Both the morphological and phylogenetic data indicated that these strains represent a new species of Gambierdiscus, G. lapillus sp. nov. (plate formula Po, 3', 0a, 7″, 6c, 7-8s, 5‴, 0p, 2″″ and distinctive by size and hatchet-shaped 2' plate). Culture extracts were found to be toxic using the mouse bioassay. Using chemical analysis, it was determined that they did not contain maitotoxin (MTX1) or known algal-derived ciguatoxin analogs (CTX3B, 3C, CTX4A, 4B), but that they contained putative MTX3, and likely other unknown compounds.
Rhodes, L, Smith, KF, Verma, A, Curley, BG, Harwood, DT, Murray, S, Kohli, GS, Solomona, D, Rongo, T, Munday, R & Murray, SA 2017, 'A new species of Gambierdiscus (Dinophyceae) from the south-west Pacific: Gambierdiscus honu sp. nov.', Harmful Algae, vol. 65, pp. 61-70.View/Download from: UTS OPUS or Publisher's site
Two isolates of a new tropical, epiphytic dinoflagellate species, Gambierdiscus honu sp. nov., were obtained from macroalgae sampled in Rarotonga, Cook Islands, and from North Meyer Island, Kermadec Islands. Gambierdiscus honu sp. nov. had the common Gambierdiscus Kofoidian plate formula: Po, 3', 6″, 6C?, 6 or 7S, 5‴, 1p and 2⁗. The characteristic morphological features of this species were its relatively small short dorsoventral length and width and the shape of individual plates, in particular the combination of the hatchet-shaped 2' and pentagonal 3' plates and the length to width ratio of the antapical 1p plate. The combination of these characteristics plus the smooth thecal surface and equal sized 1⁗ and 2⁗ plates differentiated this species from other Gambierdiscus species. The phylogenetic analyses supported the unique description. Both isolates of G. honu produced the putative maitotoxin (MTX)-3 analogue, but neither produced ciguatoxin (CTX) or MTX. Extracts of G. honu were shown to be highly toxic to mice by intraperitoneal injection (0.2mg/kg), although less toxic by gavage. It is possible that toxins other than putative MTX-3 are produced.
Murray, SA, Ajani, P, Kretzschmar, AL & Verma, A 2017, 'Response to "More surprises in the global greenhouse: Human health impacts form recent toxic marine aerosol formulations, due to centennial alterations or world-wide coastal food webs".', Marine Pollution Bulletin, vol. 123, no. 1-2, pp. 415-417.View/Download from: UTS OPUS or Publisher's site
Unnikrishnan, A, Papaemmanuil, E, Beck, D, Deshpande, NP, Verma, A, Kumari, A, Woll, PS, Richards, LA, Knezevic, K, Chandrakanthan, V, Thoms, JAI, Tursky, ML, Huang, Y, Ali, Z, Olivier, J, Galbraith, S, Kulasekararaj, AG, Tobiasson, M, Karimi, M, Pellagatti, A, Wilson, SR, Lindeman, R, Young, B, Ramakrishna, R, Arthur, C, Stark, R, Crispin, P, Curnow, J, Warburton, P, Roncolato, F, Boultwood, J, Lynch, K, Jacobsen, SEW, Mufti, GJ, Hellstrom-Lindberg, E, Wilkins, MR, MacKenzie, KL, Wong, JWH, Campbell, PJ & Pimanda, JE 2017, 'Integrative Genomics Identifies the Molecular Basis of Resistance to Azacitidine Therapy in Myelodysplastic Syndromes.', Cell Reports, vol. 20, no. 3, pp. 572-585.View/Download from: UTS OPUS or Publisher's site
Myelodysplastic syndromes and chronic myelomonocytic leukemia are blood disorders characterized by ineffective hematopoiesis and progressive marrow failure that can transform into acute leukemia. The DNA methyltransferase inhibitor 5-azacytidine (AZA) is the most effective pharmacological option, but only ∼50% of patients respond. A response only manifests after many months of treatment and is transient. The reasons underlying AZA resistance are unknown, and few alternatives exist for non-responders. Here, we show that AZA responders have more hematopoietic progenitor cells (HPCs) in the cell cycle. Non-responder HPC quiescence is mediated by integrin α5 (ITGA5) signaling and their hematopoietic potential improved by combining AZA with an ITGA5 inhibitor. AZA response is associated with the induction of an inflammatory response in HPCs in vivo. By molecular bar coding and tracking individual clones, we found that, although AZA alters the sub-clonal contribution to different lineages, founder clones are not eliminated and continue to drive hematopoiesis even in complete responders.
Rhodes, LL, Smith, KF, Verma, A, Murray, S, Harwood, DT & Trnski, T 2017, 'The dinoflagellate genera Gambierdiscus and Ostreopsis from subtropical Raoul Island and North Meyer Island, Kermadec Islands', New Zealand Journal of Marine and Freshwater Research, vol. 51, no. 4, pp. 490-504.View/Download from: UTS OPUS or Publisher's site
© 2016 The Royal Society of New Zealand. An expedition to North Meyer Island, Kermadec Islands, in November 2015, resulted in the isolation of two Gambierdiscus species, G. australes and a previously unknown Gambierdiscus species maintained in the Cawthron Institute Culture Collection of Micro-algae as CAWD242. Identifications were based on morphology and DNA sequence data analysis. Nine isolates of G. australes produced maitotoxin-1 (MTX-1) ranging from present (detectable but below the confidence level) to 36.6 pg per cell. One further isolate did not produce MTX-1, but all G. australes isolates produced putative MTX-3. Isolate CAWD242 was negative for MTX-1 but produced MTX-3. Ostreopsis sp. 3 isolated from samples collected during an earlier expedition in 2013 produced low concentrations of palytoxin (PLTX)-like compounds (0.013 pg per cell), but an isolate of the same species from samples collected in 2015 was non-toxic. Other dinoflagellates isolated and identified were Coolia malayensis, Amphidinium carterae and Prorocentrum hoffmannianum.
Verma, A, Hoppenrath, M, Harwood, T, Brett, S, Rhodes, L & Murray, S 2016, 'Molecular phylogeny, morphology and toxigenicity of Ostreopsis cf. siamensis (Dinophyceae) from temperate south-east Australia', PHYCOLOGICAL RESEARCH, vol. 64, no. 3, pp. 146-159.View/Download from: Publisher's site
Murray, SA, Smith, K, Rhodes, L, Verma, A, Curley, B, Harwood, DT, Kohli, G, Solomona, D, Rongo, T & Munday, R 2016, 'A new Gambierdiscus species (Dinophyceae) from Rarotonga, Cook Islands: Gambierdiscus cheloniae sp. nov', Harmful Algae, vol. 60, pp. 45-56.View/Download from: UTS OPUS or Publisher's site
Verma, A, Hoppenrath, M, Jose Dorantes-Aranda, J, Harwood, DT & Murray, SA 2016, 'Molecular and phylogenetic characterization of Ostreopsis (Dinophyceae) and the description of a new species, Ostreopsis rhodesae sp nov., from a subtropical Australian lagoon', HARMFUL ALGAE, vol. 60, pp. 116-130.View/Download from: UTS OPUS or Publisher's site
Ertan, H, Cassel, C, Verma, A, Poljak, A, Charlton, T, Aldrich-Wright, J, Omar, SM, Siddiqui, KS & Cavicchioli, R 2015, 'A new broad specificity alkaline metalloprotease from a Pseudomonas sp isolated from refrigerated milk: Role of calcium in improving enzyme productivity', JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC, vol. 113, pp. 1-8.View/Download from: Publisher's site
Murray, S, Verma, A, Palanisami, S & Ajani, P 2019, 'The use of eDNA and arrays for precise estuarine water quality assessment', 3rd Australian and New Zealand Marine Biotechnology Society Conference, Sydney, Australia.
Verma, A, Palanisami, S, Ajani, P & Murray, S 2019, 'Novel molecular ecology tools to predict harmful algal blooms in oyster- producing estuaries', Australian Marine Science Association Conference, Freemantle, Australia.
Murray, S, Verma, A, Ajani, P, Zammit, A, Farrell, H, Palanisami, S & O'Connor, W 2018, 'Building profitability and sustainability in the NSW oyster industry (Oral Presentation)', Australian Shellfish Quality Assurance Advisory Committee Science Day, UTS.
Verma, A, Kohli, G, Hoppenrath, M, Harwood, T, Kuzhiumparambil, U, Ralph, P & Murray, S 2016, 'Systematics and diversity of the genus Ostreopsis in the East Australian Current region', Marine and Fresh-Water Harmful Algae. Proceedings of the 17th International Conference on Harmful Algae., International Conference on Harmful Algae, International Society for Study of Harmful Algae, Brazil, pp. 84-88.View/Download from: UTS OPUS