synapses{ M A K I N G C O N N E C T I O N S }

AUGUST 2012

István Ábráham Up close and personal… with oestrogen and brain cells – by Jill Leichter

Neil Gemmell Genetics and the Platypus – by Sue Voice

Jon Waters Unrecognised treasure trove – by Sophia McKay

Daphne Lee A question of preservation – by Sandra Copeland

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Up close and personal...with oestrogen and brain cellsA powerful microscope can tell you a lot about biology, but what if you could see living molecules interacting with each other in real time? That is precisely what Dr István Ábrahám is looking at in the Department of Physiology.

Two years ago, with help of Olympus, Dr Ábrahám’s research group acquired a custom-made microscope system that uses electromagnetic waves instead of light to observe living molecules, molecules that would die under a traditional light. Then Dr Ábrahám spent six months at Kyoto University in Japan working with Professor Akihiro Kusumi, the Director of the Center for Meso-Bio Single-Molecule Imaging (CeMI). Professor Kusumi helped Dr Ábrahám establish special imaging techniques so he could look at up to three independently coloured molecules as they interacted over time. Using a time lapse super-resolution imaging technique, Dr Ábrahám can make a 100-µsec mini film to see how his molecules change over time.

His molecules of interest are oestrogen and cholinergic neurons, neurons in the brain affected by Alzheimer’s disease. Specifically, he is investigating oestrogen-induced neuro-protective effects on living cholinergic neurons, concentrating on changes in the plasma membrane.

Unfortunately, taking oestrogen has serious side effects for people, so in a collaboration with Professor Warren Tate (Department of Biochemistry), Dr Ábrahám, will also be testing synthetic oestrogens without harmful side effects to determine whether they help cholinergic brain cells recover from injury. Dr Ábrahám hopes this research will lead to new treatments for people suffering from Alzheimer’s disease.

Professor Warren Tate and Dr Ábrahám are members of the Brain Health Research Centre (BHRC) at the University of Otago.

Genetics and the PlatypusA natural aptitude for genetics and an inquisitive mind led Professor Neil Gemmell on a quest to understand the inheritance and evolution of genetic material. Especially, genes linked to regions of XY-chromosomes that determine sex.

The quest began with a serendipitous moment in a hut in Tasmania, where waiting for the rain to clear, Neil read an advert in the local paper: research assistant wanted to investigate sex determination in marsupials and monotremes (mammals who lay eggs; platypus and echidnas). Later that year Neil started a PhD with Professor Jenny Graves at La Trobe University.

In humans and most other mammals, sex is determined by the presence of a Y chromosome, which carries the Sex-determining Region Y (SRY) gene that triggers the development of the testis and thus maleness. At the time of Neil’s PhD this gene had just been found in humans and work in the Graves’ lab sought to determine whether sex in marsupials and monotremes was controlled by the same gene.

They discovered that SRY is the sex-determining gene in marsupials, but that monotremes were more complex. Unlike other mammals, which have a single pair of sex chromosomes, monotremes have multiple Xs and Ys. Platypuses have ten, 5X5Y for males and 10X for females. However, the SRY gene was not found suggesting that sex is determined through another gene in monotremes.

We still don’t know how sex is determined in monotremes. While the initial question of the PhD was not answered, Neil used the genetic data he collected to ascertain the relationships within and among platypus populations, and the evolution of the modern mammals. This work contributed to the future completion of the platypus genome in which his laboratory played a role.

Neil has continued to explore the inheritance and evolution of genetic material. His ongoing work spans pure research through to the applied, the latter of which includes application in conservation science, biosecurity, agriculture and aquaculture.

Neil says people who ask questions, seek answers and can put together connections make good geneticists.

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CONTACT: Rose NewburnMarketing – CommunicationsDivision of SciencesUniversity of OtagoPO Box 56Dunedin 9054Email rose.newburn@otago.ac.nz www.sciences.otago.ac.nz

A question of preservationTravel about 80 km inland from Dunedin and about 23 million years back in time and watch as extremely hot magma wells up through a crack in the Earth’s crust and contacts groundwater. The resulting explosive eruption forms a crater about 2 km across and maybe 150 m deep. Rain falls and the crater slowly fills with water.

The water lies still and deep within the crater, no outflow disturbs it. Microscopic diatoms live in the water, with freshwater sponges feeding on them. Very occasionally over the centuries there may be a short-lived stream flowing into the lake, bringing tiny fish who survive for a time in the surface waters. Trees surrounding the lake lose their leaves, pollen, occasional flowers and insects are blown into the waters. Sinking into the depths is like sinking into a pickling jar; acidic and anoxic, no oxygen to breathe, nothing to decompose the remains; whatever falls to the bottom is compressed and mummified.

Fast forward 20 million years to the present. The lake is gone – filled up and dried out, but the layers of diatomite containing the preserved material are still there. Enter a team of scientists led by Daphne Lee of the Department of Geology. A serendipitous find on a scoping expedition for a field trip led to a return trip with a chainsaw, and eventually a Marsden-funded drilling exploration. Fossil leaves that have been carefully prepared have been examined and photographed – even microscopic cellular detail is preserved and can be seen using electron microscopy. Pollen grains, insects, flowers and fish are being found, photographed, named, compared and catalogued.

The fossils indicate the climate in Otago was seasonally dry, warmer, temperate to subtropical; probably similar to that of Queensland. The plants and animals were different from those we know now; many plants, like proteas, are extinct in New Zealand’s native flora, but once flourished in Otago. Among the significant finds are the earliest known southern hemisphere orchids.

Ironically, once the specimens are removed and prepared they are extremely fragile and can hardly be handled for fear of their disintegration. They are kept untouched, hidden away from light and movement, but they will not last.

Daphne is a passionate time-traveller. Her team has much material to work on, and many more remarkable discoveries lie still preserved in the core samples. Daphne’s cry is that “there is so much to be done!”

Unrecognised treasure troveWe have little trouble accepting the evolutionary consequences of ‘natural’ upheaval, but what about the evolutionary effects of human-mediated change?

As an example, it has been discovered that Yellow-eyed penguins arrived in New Zealand only in the past 500 years, replacing a prehistoric penguin species, the Waitaha penguin, that was wiped out shortly after human settlement.

Professor Jon Waters and his research team from the Department of Zoology are investigating how animals such as penguins and sea-lions responded to the impact of humans and how many of New Zealand’s coastal species were actually new arrivals from overseas. One of Waters’ former Otago PhD students, Dr Sanne Boessenkool, undertook research several years ago and discovered remains of the extinct Waitaha penguin.

“This highlights the fact that we still have a great deal to learn about New Zealand’s natural history, and especially about the impact of human arrival here.

“We tend to think that things that are here now are things that have been here for a long time, yet many people would be surprised to know that the yellow-eyed penguin may not have been living in Otago as long as previously believed,” says Professor Waters.

Supported by an $878,000 grant from the Marsden Fund, Waters and his team will use carbon dating and state-of-the-art DNA analysis of prehistoric bones to shed further light on the country’s “dramatic biological history”, and to conduct a biological audit of prehistoric New Zealand.

“The ancient DNA approach used in this penguin study is enormously powerful as it provides a direct means of characterising historical biodiversity. When coupled with more traditional techniques, this method has potential to revolutionise our understanding of the past.

“More broadly, this study indicates that we inhabit a highly dynamic part of the world - an idea that contrasts with the more traditional view of an ancient and relatively unchanging New Zealand biota inherited from Gondwana. It is now becoming clear that species respond rapidly to human-mediated impacts such as climate change and extinction.”

As Professor Waters says, “Who knows what other fascinating stories might have been overlooked?”