ウラギンシジミにおける視覚的種内他個体認識の神経行動学的研究

2014 Fiscal Year Annual Research Report

• Project/Area Number: 14F04764
• Research Institution: The Graduate University for Advanced Studies
• Principal Investigator: 蟻川 謙太郎 総合研究大学院大学, 先導科学研究科, 教授 (20167232)
• Co-Investigator(Kenkyū-buntansha): PIRIH Primoz 総合研究大学院大学, 先導科学研究科, 外国人特別研究員
• Project Period (FY): 2014-04-25 – 2017-03-31
• Keywords: insect vision / angled sunbeam / visual signalling / retinal histology / eyeshine / spectral sensitivity / laboratory rearing

Outline of Annual Research Achievements

In autumn 2014, we started a lab culture of Curetis acuta. In March 2015, we have about twenty pupae. We will use the adults for retinal electrophysiology experiments, especially for spectral sensitivity measurements.
Using the telemicroscope, we collected the eyeshine reflectance spectra in both sexes. The main reflectance maximum is at 660 nm, the secondary maximum is at 440 nm. Using template matching, the facet absorbance spectra could be explained with rhdopsin templates peaking at 541, 471 and 380 nm. The middle peak probably corresponds to a mix of a blue rhodopin and the metarhodopsins. Some facets retain bluish reflectance upon adaptation, possibly because these facets do not contain blue sensitive photoreceptors. We have prepared histological samples of the retinae of both sexes. Ommatidial typing seems to be subtle and no perirhabdomal screening pigments were detected so far.
We have studied the binary M-sequence stimulation method, which is routinely being used in studies of human ERG and mammalian visual neurones. We conclude that using M-sequences with colour LEDs and DLP projectors will likely bring significant advances to understanding insect spectral and spatial vision.

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

The months November 2014-March 2015 fell into the season when there is no flying Curetis. Establishing the initial laboratory population was not fully successful. The small number of reared specimen available in March 2015 does not allow for continuation of rearing. In the May-June experimental bout, we will rely on wild-caught individuals. As the wild population in this period will likely be small, the second electrophysiology session may be delayed to September 2015. We will restart the Curetis rearing in the autumn 2015, focussing on optimizing the feeding regime in order to increase the rearing efficiency.

Strategy for Future Research Activity

In April and May 2015, we will collect the photoreceptor sensitivity spectra from both sexest. By taking into account the angular position of the recorded cells, we will try to correlate the spectra with the eyeshine and histological data.
In May 2015, we will discuss the feasability of obtaining opsin sequence data using transcriptome analysis with the visitor Dr. Perry.
In June 2015, Dr Pirih will visit a few laboratories in Europe. With Dr Belusic (Ljubljana, Slovenia) he will be developing the M-sequence LED stimulator. With Dr Stavenga (Groningen, Netherlands), he will be maping the visual axes of Curetis. Visiting Drs Krapp (London, UK) and Nordstrom (Uppsala, Sweden), he intends to learn recording and stimulation from the spiking visual neurones. We will use the summer months of 2015 to implement the LED and wide-field stimulation techniques, and for a TEM study of the retinal ultrastructure.
In the peak of wild Curetis population in the fall of 2015, we will use a fast camera to record the flashing signalling in flight. The LED stimulator will be used to perform a series of experiments on retinal electrophysiology, focussing on the photoreceptor speeds. Using DLP projectors, we will probe into lateral interactions in the retina and try initial experiments on higher order neurones.
In 2016, we will focus on the electrophysiology of higher visual neurones, and on reporting the project results.