Tag Archives: MQ

Understanding the role that sugars play

30 March 2018:

CNBP scientists Chris Ashwood (pictured) and Prof Nicki Packer at Macquarie University have shown that sugars with exactly the same chemical composition but slightly different structure break apart differently in their latest publication in the area of mass spectrometry. This work is their first step in automating sugar analysis, to understand the role sugars play in human disease.

Journal: Journal of The American Society for Mass Spectrometry.

Publication title: Discrimination of Isomers of Released N- and O-Glycans Using Diagnostic Product Ions in Negative Ion PGC-LC-ESI-MS/MS.

Authors: Christopher Ashwood, Chi-Hung Lin, Morten Thaysen-Andersen, Nicolle H. Packer.

Profiling cellular protein glycosylation is challenging due to the presence of highly similar glycan structures that play diverse roles in cellular physiology. As the anomericity and the exact linkage type of a single glycosidic bond can influence glycan function, there is a demand for improved and automated methods to confirm detailed structural features and to discriminate between structurally similar isomers, overcoming a significant bottleneck in the analysis of data generated by glycomics experiments. We used porous graphitized carbon-LC-ESI-MS/MS to separate and detect released N- and O-glycan isomers from mammalian model glycoproteins using negative mode resonance activation CID-MS/MS. By interrogating similar fragment spectra from closely related glycan isomers that differ only in arm position and sialyl linkage, product fragment ions for discrimination between these features were discovered. Using the Skyline software, at least two diagnostic fragment ions of high specificity were validated for automated discrimination of sialylation and arm position in N-glycan structures, and sialylation in O-glycan structures, complementing existing structural diagnostic ions. These diagnostic ions were shown to be useful for isomer discrimination using both linear and 3D ion trap mass spectrometers when analyzing complex glycan mixtures from cell lysates. Skyline was found to serve as a useful tool for automated assessment of glycan isomer discrimination. This platform-independent workflow can potentially be extended to automate the characterization and quantitation of other challenging glycan isomers.

Sameera Iqbal awarded poster prize

2 February 2018:

Sameera Iqbal, CNBP PhD student at Macquarie University has been awarded a certificate and cash prize for her poster presentation at the Australasian Glycoscience Symposium at the Lorne Proteomics Conference, 2 Feb, 2018.

Her poster detailed the following work –

‘PolySialic Acid (PolySia) is an α2-8-linked sialic acid chain present on cell surfaces in embryonic brains. Changes in polysialylation pattern are reported to be associated with immune defense and inflammation in the CNS. Opioids such as Morphine-3-Glucuronide (M3G) (metabolite of morphine) activates neuroinflammation in a manner parallel to Lipopolysaccharide (LPS), compromising opioid-induced analgesia. In this study, morphine (Morphine-3-glucuronide) was hypothesized to affect the polySia expression in neurons and astrocyte cell lines. It was observed that PolySia expression was significantly increased in neurons following LPS and M3G stimulation.’

Well done Sameera!

Neurophotonics Summer School

21 June 2017:

This years Neurophotonics Summer School held in Quebec, Canada, June 11-21, was attended by three CNBP members – Vicky Staikopoulos (University of Adelaide, pictured), Antony Orth (RMIT University) and Varun Sreenivasan (UNSW).

The school focuses on teaching physics and biology and how they can merge, and runs for 10 days and includes 14 lectures from world class speakers and 10 workshops that teach the latest technology in the bio-imaging of the central nervous system.

For the last 4 days of the summer school, students are given a project to participate in for direct hands-on experience which is then presented on the last day,  with prizes awarded for the top 3 presentations.

This year, equal second prize was given to Vicky Staikopoulos for her work on Digital Holographic Microscopy in red blood cells.


Centre represented at Glycoinformatics Symposium

13 June 2017:

CNBP Chief Investigator Prof Nicki Packer has attended the Beilstein Glycoinformatics Symposium, Berlin, Germany, 13-15th June 2017.

Prof Packer was an invited speaker, session chair and sat on a discussion panel, with her attendance fully funded by the conference organisers.

Prof Packer’s talk was titled, “Technology Shapes Glycoinformatics.”


Centre CI at Gordon Glycobiology conference

25 March 2017:

CNBP Chief Investigator Professor Nicki Packer was an invited chair of a session and leader of the Power Hour (gender equality workshop)  at the Gordon Glycobiology conference at Ventura, California 19-24 March, 2017.

As session Chair, Prof Packer led discussion on advances in omics, integrated omics, bioinformatics for glycobiology and the impact of altered glycosylation for human disorders.

The Power Hour was an informal session designed to help address the challenges women face in science and to support the professional growth of women by providing an open forum for discussion and mentoring.

Further conference information is accessible online.


Breaking apart sugars

9 March 2017:

CNBP scientists Chris Ashwood and Prof Nicki Packer at Macquarie University have shown alternative ways to break apart sugars, improving their characterisation in their latest publication in the area of mass spectrometry (Enhancing structural characterisation of glucuronidated O-linked glycans using negative mode ion trap higher energy collision-induced dissociation mass spectrometry).

The work was published online in the journal Rapid Communications in Mass Spectrometry on 9th March 2017 and was funded by the Australian Research Council Centre of Excellence for Nanoscale BioPhotonics.

Investigating cell metabolism

Aziz Rehman1 March 2017:

A new publication from CNBP researchers (lead author Aziz Ul Rehman pictured) reports on the application of hyperspectral imaging in combination with fluorescence spectroscopy and chemical quenching to provide a new methodology to investigate cell metabolism.

The work has just been reported in the journal ‘Biomedical Optics Express’ and is accessible online.

Journal: Biomedical Optics Express.

Title: Fluorescence quenching of free and bound NADH in HeLa cells determined by hyperspectral imaging and unmixing of cell autofluorescence.

Authors: Aziz Ul Rehman, Ayad G. Anwer, Martin E. Gosnell, Saabah B. Mahbub, Guozhen Liu, and Ewa M. Goldys.

Abstract: Carbonyl cyanide-p-trifluoro methoxyphenylhydrazone (FCCP) is a well-known mitochondrial uncoupling agent. We examined FCCP-induced fluorescence quenching of reduced nicotinamide adenine dinucleotide / nicotinamide adenine dinucleotide phosphate (NAD(P)H) in solution and in cultured HeLa cells in a wide range of FCCP concentrations from 50 to 1000µM. A non-invasive label-free method of hyperspectral imaging of cell autofluorescence combined with unsupervised unmixing was used to separately isolate the emissions of free and bound NAD(P)H from cell autofluorescence. Hyperspectral image analysis of FCCP-treated HeLa cells confirms that this agent selectively quenches fluorescence of free and bound NAD(P)H in a broad range of concentrations. This is confirmed by the measurements of average NAD/NADH and NADP/NADPH content in cells. FCCP quenching of free NAD(P)H in cells and in solution is found to be similar, but quenching of bound NAD(P)H in cells is attenuated compared to solution quenching possibly due to a contribution from the metabolic and/or antioxidant response in cells. Chemical quenching of NAD(P)H fluorescence by FCCP validates the results of unsupervised unmixing of cell autofluorescence.