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Observation of live ticks (Haemaphysalis flava) by scanning electron microscopy under high vacuum pressure.

Ishigaki Y, Nakamura Y, Oikawa Y, Yano Y, Kuwabata S, Nakagawa H, Tomosugi N, Takegami T - PLoS ONE (2012)

Bottom Line: Various conventional methods exist for SEM sample preparation.During 1.5×10(-3) Pa vacuum pressure and electron beam irradiation with accelerated voltages (2-5 kV), many ticks remained alive and moved their legs.These data also indicate, for the first time, the usefulness of tick as a model system for biology under extreme condition.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Institute, Kanazawa Medical University, Uchinada-machi, Kahoku-gun, Japan.

ABSTRACT
Scanning electron microscopes (SEM), which image sample surfaces by scanning with an electron beam, are widely used for steric observations of resting samples in basic and applied biology. Various conventional methods exist for SEM sample preparation. However, conventional SEM is not a good tool to observe living organisms because of the associated exposure to high vacuum pressure and electron beam radiation. Here we attempted SEM observations of live ticks. During 1.5×10(-3) Pa vacuum pressure and electron beam irradiation with accelerated voltages (2-5 kV), many ticks remained alive and moved their legs. After 30-min observation, we removed the ticks from the SEM stage; they could walk actively under atmospheric pressure. When we tested 20 ticks (8 female adults and 12 nymphs), they survived for two days after SEM observation. These results indicate the resistance of ticks against SEM observation. Our second survival test showed that the electron beam, not vacuum conditions, results in tick death. Moreover, we describe the reaction of their legs to electron beam exposure. These findings open the new possibility of SEM observation of living organisms and showed the resistance of living ticks to vacuum condition in SEM. These data also indicate, for the first time, the usefulness of tick as a model system for biology under extreme condition.

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Related in: MedlinePlus

Motion of a live tick under SEM.Images of the TV mode were recorded. Time under vacuum conditions is shown on top of each picture. Leg movements are indicated by triangles.
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pone-0032676-g003: Motion of a live tick under SEM.Images of the TV mode were recorded. Time under vacuum conditions is shown on top of each picture. Leg movements are indicated by triangles.

Mentions: Under the TV mode of SEM, we recorded a video of the SEM monitor after initiating decompression to 1.5×10−3 Pa and observed leg action. Fig. 3 shows representative pictures clipped from SEM monitor videos. The tick moved its second left leg actively for approximately one min. We observed this motion in both adults and nymphs. Ticks tested under SEM could move all four legs. High-resolution capture was possible, and the ticks could move their legs after the capture. Gradually, they stopped moving, but remained alive after being placed outside SEM (a walking tick on tweezers is shown in movie S1). The ticks were alive and could move after they were removed from the tape fixing them to the SEM stub. We repeated the observation with 20 ticks and obtained similar results. We also observed dead ticks under the same SEM conditions, but only a slight shrinkage of legs was observed with capture. We concluded that the action under SEM was the real motion of live ticks.


Observation of live ticks (Haemaphysalis flava) by scanning electron microscopy under high vacuum pressure.

Ishigaki Y, Nakamura Y, Oikawa Y, Yano Y, Kuwabata S, Nakagawa H, Tomosugi N, Takegami T - PLoS ONE (2012)

Motion of a live tick under SEM.Images of the TV mode were recorded. Time under vacuum conditions is shown on top of each picture. Leg movements are indicated by triangles.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3303806&req=5

pone-0032676-g003: Motion of a live tick under SEM.Images of the TV mode were recorded. Time under vacuum conditions is shown on top of each picture. Leg movements are indicated by triangles.
Mentions: Under the TV mode of SEM, we recorded a video of the SEM monitor after initiating decompression to 1.5×10−3 Pa and observed leg action. Fig. 3 shows representative pictures clipped from SEM monitor videos. The tick moved its second left leg actively for approximately one min. We observed this motion in both adults and nymphs. Ticks tested under SEM could move all four legs. High-resolution capture was possible, and the ticks could move their legs after the capture. Gradually, they stopped moving, but remained alive after being placed outside SEM (a walking tick on tweezers is shown in movie S1). The ticks were alive and could move after they were removed from the tape fixing them to the SEM stub. We repeated the observation with 20 ticks and obtained similar results. We also observed dead ticks under the same SEM conditions, but only a slight shrinkage of legs was observed with capture. We concluded that the action under SEM was the real motion of live ticks.

Bottom Line: Various conventional methods exist for SEM sample preparation.During 1.5×10(-3) Pa vacuum pressure and electron beam irradiation with accelerated voltages (2-5 kV), many ticks remained alive and moved their legs.These data also indicate, for the first time, the usefulness of tick as a model system for biology under extreme condition.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Institute, Kanazawa Medical University, Uchinada-machi, Kahoku-gun, Japan.

ABSTRACT
Scanning electron microscopes (SEM), which image sample surfaces by scanning with an electron beam, are widely used for steric observations of resting samples in basic and applied biology. Various conventional methods exist for SEM sample preparation. However, conventional SEM is not a good tool to observe living organisms because of the associated exposure to high vacuum pressure and electron beam radiation. Here we attempted SEM observations of live ticks. During 1.5×10(-3) Pa vacuum pressure and electron beam irradiation with accelerated voltages (2-5 kV), many ticks remained alive and moved their legs. After 30-min observation, we removed the ticks from the SEM stage; they could walk actively under atmospheric pressure. When we tested 20 ticks (8 female adults and 12 nymphs), they survived for two days after SEM observation. These results indicate the resistance of ticks against SEM observation. Our second survival test showed that the electron beam, not vacuum conditions, results in tick death. Moreover, we describe the reaction of their legs to electron beam exposure. These findings open the new possibility of SEM observation of living organisms and showed the resistance of living ticks to vacuum condition in SEM. These data also indicate, for the first time, the usefulness of tick as a model system for biology under extreme condition.

Show MeSH
Related in: MedlinePlus