[Scanning electron microscope observation of plerocercoid from Rana nigromaculata in Guizhou Province].

Five integral and active plerocercoids collected from naturally infected frogs were fixed by glutaraldehyde-osmic acid, dehydrated in graded series of ethanol, dried via vacuum freeze and coated with carbon gold. They were then observed by scanning electron microscopy. The results showed that the anterior and posterior ends of the plerocercoids were slightly swell and without segmentation. Annular furrows ran irregularly along the body surface. The anterior end was drawn inside and had a deep dorsoventral hollow, around which, the plasma membrane displayed a lip bulge. The posterior end was similar to the anterior one in the shape, but a fissure in its central part was comparatively narrower and shallower than the hollow in the anterior end. There were thousands of pits and grooves on the body surface, unequal in size. The whole body surface of the plerocercoid was densely covered by sharp spine-like microtriches.

[Effect of physicochemical factors on infectivity of Spirometra mansoni plerocercoid].

OBJECTIVE: To observe the effect of different physicochemical factors on the infectivity of Spirometra mansoni plerocercoids. METHODS: The muscle samples with plerocercoids taken from Rana nigromaculata (about 1 cm3 each piece) were treated with different temperature (-20 degrees C, 4 degrees C, 37 degrees C and 56 degrees C) or different concentrations of ethanol (20%, 30%, 40%, 50% and 60%) for 1, 2 or 3 h, or soaked in ginger juice, vinegar (total acid concentration of 4.5%, pH 3.05) or soy sauce (containing 19.3% NaCl) for 3, 6, 12 or 24 h. The muscle with plerocercoids treated with normal saline under 20 degrees C served as control. 30 plerocercoids were used under each condition and fed to 10 mice averagely (3 larvae/mouse). Another 20 plerocercoids with frog meat were comminuted for 3 min then fed to 10 mice. One week later, the mice were sacrificed to collect the parasitic plerocercoids and the number of positive mice and plerocercoids was recorded. RESULTS: None of the mice fed with plerocercoids treated under -20 degrees C for 2 h was infected. All the mice fed with plerocercoids treated under 56 degrees C for 2 h and 3 h were infected. The percentage of infective plerocercoids was 60% (18/30) and 43% (13/30), respectively, considerably lower than those of the control (90%, 27/30) (P < 0.05). None of the mice fed with plerocercoids soaked in 60% ethanol for 2 h was infected. All the mice fed with plerocercoids soaked in 60% ethanol for 1 h, or in 50% ethanol for 2 h or 3 h were infected. The percentage of infective plerocercoids was 60% (18/30), 57% (17/30), and 50% (15/30), respectively, considerably lower than those of the control (93%, 28/30) (P<0.05). None of the mice fed with plerocercoids soaked in vinegar for 24 h, or soy sauce for 6 h was infected. The infectivity of the plerocercoids treated by ginger juice for 24 h was similar to the control (P>0.05). Among the ten mice fed with comminuted frog meat with plerocercoids, five were infected with 6 plerocercoids. CONCLUSION: Treatment with -20 degrees C or 60% ethanol for 2 h, soy sauce for 6 h, or vinegar for 24 h can destroy the infectivity of plerocercoids in 1 cm3 frog muscle.

[Observation on the ultrastructure of Spirometra mansoni plerocercoid].

Plerocercoids of Spirometra mansoni were collected from muscles of the frogs. Specimens were treated following the routine procedure, embedded, sliced and stained. The ultrastructure of plerocercoid was observed with transmission electron microscopy. It was found that the wall of plerocercoid consisted of tegument and parenchyma. Thornshape microtriches distributed over the outer surface of the tegument. Matrix zone had a lot of granular discoidal bodies, vesicles, mitochondria and endoplasmic reticulum. Most of the mitochondria were near the basal membrane. Parenchyma zone consisted of muscular layer, tegument cells, parenchymal cells, excretory system, and so on. Many cytoplasmic pathways of tegumentary cells stretch into muscular layer, suggesting that the tegument may be the absorptive site of nutrients.

[Soluble proteins of the plerocercoid of Spirometra mansoni].

OBJECTIVE: To analyze soluble proteins of the plerocercoid of Spirometra mansoni. METHODS: The total protein of the plerocercoid of S. mansoni was separated by SDS-PAGE and two-dimensional electrophoresis (2-DE). Western blotting was performed to find out distinct antigens by sera of plerocercoid-infected mice. RESULTS: A total of 33 protein bands were separated by SDS-PAGE (Mr 13,800-145,400). Four of them were high-abundance proteins with Mr 26,500, Mr 37,600, Mr 88,200, and Mr 130,200, respectively. At least two protein bands of Mr 31,600 and 37,600 reacted with the infected mice sera. 367 protein spots were detected on 2-DE gel, among which. about 67% proteins were found within Mr 18,840-46,800 and isoelectric point (pI) 4-7. Western blotting showed 30 antigen spots specifically reacting with sera from mice infected by S. mansoni. CONCLUSION: Two protein bands and thirty protein spots are specific acidic proteins of S. mansoni plerocercoid.