JOHNSON: PARASITES OF BENTHIC AMPHIPODS 



the time of sporulation, the host is castrated (Chat- 

 ton 1910, 1920). Types AA and AV resemble Hema- 

 todinium, not Syndinium, in that apparently none 

 of these organisms develop from a primary Plas- 

 modium associated with the gut, but instead they 

 multiply from a few single cells and small plasmodia 

 in the general hemocoel and never form a single 

 massive Plasmodium. Further, these parasites do 

 not castrate their hosts (Newman and Johnson 1975; 

 MacLean and Ruddell 1978; P. T. Johnson, unpubl. 

 data). 



Syndinium gammari, like Types AA and AV, is 

 perhaps more closely related to Hematodinium than 

 to Syndinium. Syndinium gammari was assigned 

 to Syndinium by Manier et al. (1971) on the assump- 

 tion that a massive Plasmodium was present dur- 

 ing development. However, none of the infections 

 studied by these authors had either a primary 

 Plasmodium associated with the gut or a later and 

 massive Plasmodium throughout the hemocoel. The 

 first stage of S. gammari observed consisted of 

 small irregular plasmodia up to 15 pm in diameter, 

 which Manier and coworkers assumed resulted from 

 the splitting-up of a large plasmodium. The small 

 plasmodia then divided to form "diplococcal" forms, 

 and these divided to give round, single organisms 

 which transformed into spores measuring 7-8 /urn by 

 3-3.5 ^m. In the later stages of division, typical 

 "dinomitosis" and "dinokaryons" were present. 

 Considering the course of development in the ap- 

 parently related parasites of benthic amphipods, 

 Types AA and AV, it is possible that S. gammari 

 does not have a primary plasmodium associated with 

 the gut wall and does not develop an extensive 

 Plasmodium in the hemocoel. If early stages of S. 

 gammari consist of a few single cells or small 

 plasmodia, these could have escaped notice because 

 the parasites were observed after their removal 

 from the host amphipod, either alive or in fixed and 

 stained smears (Manier et al. 1971). Scattered 

 organisms could more easily be missed by this tech- 

 nique than by inspection of paraffin-embedded and 

 sectioned whole amphipods. 



Chromosomes of Solenodinium globiforme and 

 three species of Syndinium, all parasites of radio- 

 larians, stain with fast green in the Alfert and 

 Geschwind method for demonstration of basic 

 nuclear proteins (Ris and Kubai 1974; Hollande 

 1975). Ris and Kubai remarked that chromosomes 

 of the Syndinium species they studied also stained 

 brightly in the Feulgen reaction. Although not 

 definitely stated by the above authors, apparently 

 chromosomes of all developmental stages of the 

 above parasites stained equally with fast green. 



Chromosomes of these species tend to remain con- 

 densed through the entire developmental cycle. On 

 the other hand, Hollande (1975) found that trophont 

 nuclei of the duboscquodinids Amoebophrya ceratii 

 and Duboscquella melo do not stain by the Alfert and 

 Geschwind method. He pointed out that chromo- 

 somes are not condensed in the trophont nuclei of 

 these forms and that he did not investigate stain- 

 ing properties of the condensed chromosomes of 

 spores. Hollande did find that a portion of the 

 nucleolus of A. ceratii stains with fast green in the 

 Alfert and Geschwind method. Like the syndinid 

 parasites of radiolarians, chromosomes of Type AA 

 and AV spores stain brightly in both Alfert and 

 Geschwind's technique and the Feulgen reaction. 

 However, Feulgen staining is less intense in stages 

 I and II nuclei and these nuclei do not stain at all 

 with fast green. 



Eukaryotes have a greater quantity of histone in 

 rapidly dividing cells than in quiescent ones (DuPraw 

 1968; Wu et al. 1982), and nonhistone basic nuclear 

 proteins— although scarce at all times— are much 

 more abundant in log-phase than in stationary-phase 

 cultures of the free-living dinoflagellates Gyro- 

 dinium cohnii and Peridinium trochoideum (Rizzo 

 and Nooden 1974). It would be interesting to deter- 

 mine the relative amounts of basic nuclear proteins 

 through the developmental cycle of syndinids and 

 other duboscquodinids, and to determine whether 

 basic proteins of the amphipod parasites increase 

 when cells are dividing rapidly; and whether these 

 proteins are masked by other substances (acidic pro- 

 teins?) in stages where both chromatin and nuclear 

 matrix stain purple with H&E and do not stain in 

 the Alfert and Geschwind method. 



Probably fixation and paraffin embedment not 

 only damaged flagella and were responsible for ap- 

 parent lack of flagella on most spores of Types AA 

 and AV, but also distorted spores of these parasites. 

 Cachon (1964) cautioned that because spores of 

 parasitic dinoflagellates become distorted or rup- 

 tured both on fixation and when physical conditions 

 are not proper, their shapes must be determined in 

 living material. 



Origin and function of the small dense bodies pres- 

 ent in Type AV, stage IA infections were not evi- 

 dent. These bodies might represent necrotic nuclei 

 like those seen in Syndinium infections (Jepps 

 1936-37), discarded chromatin resulting from reduc- 

 tion divisions, or, perhaps, nuclei of microspores 

 (Cachon 1964). 



Numbers of Gammarus locusta (Linn.) infected 

 with Syndinium gammari in the Etang de Thau, 

 France, varied from few to all members of a popula- 



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