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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Willaertia

Willaertia De Jonckheere, Pussard, Dive and Vickerman, 1984 (ref. ID; 7712 original paper)

Heterolobosea: Vahlkampfidae (ref. ID; 7280)
Vahlkampfidae (ref. ID; 7712)

[ref. ID; 7712]
Diagnosis; Trophozoite with eruptive pseudopod formation, uni- or multinucleated. Promitosis without typical interzonal bodies. No flagellate stage known. Round cyst with pores, closed by mucous plugs as in Naegleria. Cyst wall composed of very thin exocyst and thick endocyst. Serologically distinct from Naegleria. (ref. ID; 7712)
Type species; Willaertia magna (ref. ID; 7712)
  1. Willaertia magna De Jonckheere, Pussard, Dive and Vickerman, 1984 (ref. ID; 7712 original paper) reported author and year? (ref. ID; 7050)
  2. Willaertia minor Dobson, Robinson, Christy & Hayes, 1993 (ref. ID; 7280 original paper)

Willaertia magna De Jonckheere, Pussard, Dive and Vickerman, 1984 (ref. ID; 7712 original paper) reported author and year? (ref. ID; 7050)

Diagnosis

Large trophozite (50-100 um) and cyst (18-21 um). Some strains adapt to growth in axenic medium. Thermophilic amoeba, but not pathogenic for mice. Destroys Vero cells in culutre. Specific isoenzyme pattern. Habitat: freshwater and soil. (ref. ID; 7712)

Descriptions

The internal transcribed spacer (ITS) sequences. (ref. ID; 7050)

Examined materials

Z503 and Z504, two clones from faeces taken directly from the rectum of bovines (Pussard and Pons 1979). TS-9 from soil in France (Pussard et al. 1979). M-1 from thermally polluted water in Frane (Dive, unpublished). T5(S)44 from sediment at the thermal effluent of a nuclear power station in Belgium (De Jonckheere 1982). (ref. ID; 7712)

Willaertia minor Dobson, Robinson, Christy & Hayes, 1993 (ref. ID; 7280 original paper)

Diagnosis

Trophozoites moving by eruptive, rounded bulges, typical of vahlkampfiids, 17 to 38 um long in extended locomotion. Cysts approximately spherical with ecto- and endocyst loosely attached, 11 to 23 um in diameter (average=18.9 um), lacking perinuclear granules and with two to seven prominent pores. Differentiates to flagellates, predominantly mononucleate and usually bearing four flagellates, lacking a cytostome but capable of a single division; motile flagellates appearing after 130 min at 30 degrees C. Primary flagellates ovoid, 12 to 22 um in length (average=17.5 um), with mean length/breadth ratio of 1.22. Daughter cells predominantly biflagellate, failing to replace the flagella lost during division. Maximum growth temperature 38 degrees C. Allelic states differ from W. magna for numerous enzymes including Gpi, Hbdh, Mdh and Me. (ref. ID; 7280)

Descriptions

All stages of WT043 were predominantly mononucleate, although binucleate cells were common, as they are in W. magna. Trophozoites moved by eruptive, rounded bulges typical of vahlkampfiids and were 17.1 to 37.5 um long (average=26.1 um), significantly smaller than W. magna (50 to 100 um (De Jonckheere et al. 1984)). Cyst of WT043 were circular to ovoid when grown on moist plates, with distinctly separated endo- and ectocyst. Under drier conditions, their shape was less regular and the separation of the ectocyst more pronounced. Like W. magna, WT043 did not have perinuclear granules in mature cysts, but unlike W. magna, these were also absent from trophozoites and immature cysts. The greatest dimension of mature mononucleate cysts as 11.9 to 22.6 um (average=18.9 um), smaller than those reported for W. magna (18-21 um (De Jonckheere et al. 1984), but larger and more variable in many isolates). The average diameter of the endocyst was 13.6 um. The number of pores observed in variable mononucleate cysts was one to seven (average=3.8), with a slightly higher mean (4.5) in vacant cysts, in which pores were more easily observed. Some vacant cysts may also have originally been binucleate. The original description of W. magna reported seven to eight pores (De Jonckheere et al. 1984), but for most isolates the number is more variable; 3 to 15 pores, with a mean around 8 to 10 (unpubl. observ.). Differentiation to flagellates by WT043 was poor in agitated suspensions (maximum of 5% flagellates in several trials) but occurred readily in microtitre wells. At 30 degrees C, motile flagellates appeared after 130 min, with many present by 160 min. Mature primary flagellates (those arising directly from trophozoites) were ovoid, lacked a cytostome, were capable of division and had predominantly four flagella. They were 12.3 to 21.8 um long (average=17.5), 8.4 to 19.1 um wide (average=14.0) with a mean length/breadth ratio of 1.22, compared to 16.5 to 25 um long (average=20.7 um) and a mean length/breadth ratio of 1.36 for W. magna. The mean cell volume of the primary flagellates of WT043 was 1,700 um3, compared with 2,500 um3 for W. magna (Robinson et al. 1989). Occasional binucleate flagellates had six to eight flagella. During nuclear division, the flagellates became more rounded and the nucleus progressively more elongate. In binucleate flagelles, division of the nuclei was usually synchronous. After cell division the daughter cells were smaller and most had only two flagella. By 300 min the majority of flagellates present were biflagellate daughter cells. (ref. ID; 7280)

Remarks

In field studies of free-living amoebae, the trophozoites and cysts of W. minor are more likely than W. magna to be mistaken for a Naegleria species. The structure and behavior of flagellates should therefore be closely examined for any presumed Naegleria species that cannot by assigned to one of the genetically defined species. (ref. ID; 7280)

Known geographic distribution

Tropical Australia. (ref. ID; 7280)

Type location

Berry Springs, Northern Territory, Australia. Willaertia minor WT-043 has been lodged in the American Type Culture Collection, as ATCC50320. (ref. ID; 7280)