Mayorella

Mayorella Schaeffer, 1926 (ref. ID; 660, 3687, 3719, 7601)

Subclass Gymnamoebia: Order Amoebida: Family Paramoebidae (ref. ID; 7601)
Family Mayorellidae Schaeffer, 1926 (ref. ID; 3719)

[ref. ID; 3719]
The family Mayorellidae was erected by Schaeffer in 1926 for rhizopods of medium to large size with conical or tapering pseudopods which do not direct motion. He included his new genus Mayorella in this family. The principal characteristic of this genus is the numerous small conical pseudopods with are continuously being formed along the anterior edge of the cell. These pseudopods are always in motion, being either in a state of extension or retraction. (ref. ID; 3719)

[ref. ID; 7601]
Dactyloid, blunt, hyaline subpseudopodia of similar lengths, not furcate, usually few, usually produced from a hyaline lobe; length of locomotive form greater than breadth; in species whose fine structure is known, covering of complex, boat-shaped scales, often if not always of two sizes and pattens; large and complex Golgi region adjacent to nucleus, site of scale synthesis; no parasomes; floating forms often with distinct spherical central mass and slender radiating pseudopodia. Both freshwater and marine species. (ref. ID; 7601)

Mayorella augusta Schaeffer, 1926 (ref. ID; 3687)
Mayorella bigemma Schaeffer, 1918 (ref. ID; 660, 3719) reported author and year? (ref. ID; 7586)
Mayorella bulla Schaeffer, 1926 (ref. ID; 660, 3687, 7601)
Mayorella cantabrigiensis Page, 1983 (ref. ID; 660 original paper)
Mayorella clavabellans Bovee, 1970 (ref. ID; 660)
Mayorella conipes Schaeffer, 1926 (ref. ID; 3687)
Mayorella crystallus Schaeffer, 1926 (ref. ID; 3687)
Mayorella gemmifera Schaeffer, 1926 (ref. ID; 3687)
Mayorella godesae Arena, 1953 (ref. ID; 660)
Mayorella oblonga Bovee, 1970 (ref. ID; 660)
Mayorella palestinensis Reich, 1933
See; Acanthamoeba palestinensis (ref. ID; 3767)
Mayorella penardi Page, 1972 (ref. ID; 660, 2039)
Syn; Amoeba spumosa Penard, 1902 (ref. ID; 660, 2039)
Mayorella riparia Page, 1972 (ref. ID; 2039) reported author and year? (ref. ID; 7601)
Mayorella spumosa (Gruber) (ref. ID; 3497)
Mayorella stella (Schaeffer, 1926) Page, 1981 (ref. ID; 7601 redescribed paper), Page, 1981 (ref. ID; 660)
Mayorella vespertilio Penard, 1902 (ref. ID; 660, 3719)
Syn; Amoeba vespertilio Penard, 1902 (ref. ID; 3719)
Mayorella vespertilioides Page, 1983 (ref. ID; 660 original paper)
Mayorella viridis Leidy, 1874 (ref. ID; 660, 3719)
Syn; Amoeba viridis Leidy, 1874 (ref. ID; 3719)

Mayorella bigemma Schaeffer, 1918 (ref. ID; 660, 3719) reported author and year? (ref. ID; 7586)

Descriptions

Mayorella bigemma is recorded as containing zoochlorellae in only three individuals. (ref. ID; 3719)
Individuals of this species may have several contractile vacuoles. These may expel their contents at any point of the cell surface with the exception of the pseudopodia. The vacuole appears rounded immediately before expulsion occurs. During the expulsion of the vacuolar contents, the contractile vacuole is replaced by a layer of hyaline cytoplasm. When all of the vacuolar contents have been expelled, the hyaline region persists as a distinct region (the systolic mass) for some time. Eventually the systolic mass is dissipated by the cyclotic activity of the cytoplasm. Early stages of fillng are difficult to see, but later stages of diastole involve, at least, the fusion of contributory vesicles. (ref. ID; 7586)

Examined material

Mayorella bigemma was isolated from Chew Lake, England (National Grid reference ST 596635) and identified from Page (1976). (ref. ID; 7586)

Mayorella bull Schaeffer, 1926 (ref. ID; 660, 3687, 7601)

Diagnosis

Length of locomotive form 35-165 um, mean near 80 um; length/breadth ratio near 2.0; posterior usually not greatly narrowed; often one or more somewhat irregular dorsal ridges; floating form with spherical central mass and slender, radiate, often somewhat sinuous pseudopodia whose length may reach four or five times diameter of central cell mass; nucleus 8.5-16.5 um, often ellipsoid, highly deformable, with irregular endosomal fragments usually clumped loosely in central region of nucleus or in ring-shaped configuration; no cytoplasmic crystals known; usually two or several contractile vacuoles; larger surface scales approximately 720 nm long; with prominent horn topping each end and open-bottomed latticework basket suspended between ends and supported on each side by three upright struts from slightly concave, solid base; smaller scales approximately 150 nm long, with simple boat-like form and fine mesh work sides; no cyst known. (ref. ID; 7601)

Observed habitat

Fresh water: USA, Britain. (ref. ID; 7601)

Mayorella cantabrigiensis Page, 1983 (ref. ID; 660 original paper)

Diagnosis

Locomotive form often considerably broader anteriorly; usually with dactyloid subpseudopodia, which sometimes occur in distinct pairs; often with a morulate uroid. Nucleus with central nucleolus; diameter of nucleus 8.4-13.0 um, mean 9.4-11.1 um, approximately 1.5-1.6 times diameter of nucleolus. Contractile vacuole replaced after emptying by temporary hyaloplasmic area. Paired cytoplasmic inclusions, each pair in its own vesicle and one of pair crystalline. Floating form rounded, sometimes with short projections but not known to be radiate. No cyst known. Cuticle usually 200-230 nm thick, sometimes to 280 nm or slightly more. (ref. ID; 660)

Type locality

Freshwater, England. (ref. ID; 660)

Type slides

Holotype (1982:7:13:1) and paratype (1982:7:13:2), both prepared from strain 311, at British Museum (Natural History). (ref. ID; 660)

Measurements

Length of locomotive form 55-180 um, mean 93-115 um; mean length/breadth ratio 2.4-3.3. (ref. ID; 660)

Mayorella spumosa (Gruber) (ref. ID; 3497)

Descriptions

The median sized form usually has triangular pseudopodia, short uroids and a number of contractile vacuoles, of which one is often large. Distinct plasmic granulation is generally seen, and faint dorsal ridges are rarely observed in developed specimens. (ref. ID; 3497)

Comments

The common amoeba of fresh water is also frequent in sea water of low salinities, occuring in brackish and sea water of salinities of 15.21-31.87 o/oo in Hiroshima Bay throughout the year. Specimens examined from the sea are generally small: most of those being as long as 40-60 um. (ref. ID; 3497)

Measurements

Length without pseudopodia 40-120 um. (ref. ID; 3497)

Mayorella stella (Schaeffer, 1926) Page, 1981 (ref. ID; 7601 redescribed paper), Page, 1981 (ref. ID; 660)

Re-diagnosis

Length of locomotive form varying greatly among strains, approximately 20 to 120 um, means from 35 to 65 um; mean length/breadth ratio near 3.0 or slightly less, but elongate forms with length/breadth ratio greater than 4.0 not rare; much variation of shape; elongate forms occasionally with longitudinal dorsal ridge; floating form with more or less spherical central mass and radiating, usually bent pseudopodia whose length may reach or exceed twice diameter of central mass; nucleus often elongate, often with semblance of binucleate condition when nucleus lobed or twisted; endosomal material in long, lobed, often twisted body, perhaps sometimes fragmented, not parietal in nucleus; length of nucleus 4-13 um, means 7-9 um; no cytoplasmic crystals known; usually two contractile vacuoles; larger scales approximately 550 nm long, with latticework basket suspended between two ends, its bottom parallel to concave soild bottom of scale, to which basket is attached laterally; smaller scales approximately 150 nm long, with simple boat-like form and fine meshwork sides; no cyst known. Distinguished for Mayorella riparia primarily by form of nucleus and nucloelus. (ref. ID; 7601)

Observed habitats

Fresh water, USA: estuary, Scotland: estuarine tolerates salinities only to about 3 0/00. (ref. ID; 7601)

Type slides

Neotype (1981:7:10:3) and paraneotype (1981:7:10:4), both prepared from strain 272, at British Museum (Natural History). (ref. ID; 7601)

Mayorella vespertilioides Page, 1983 (ref. ID; 660 original paper)

Diagnosis

Locomotive form sometimes lacking dactyloid subpseudopodia; often with a morulate uroid. Nucleus with central nucleolus; diameter of nucleus 5.6-10.0 um, mean, 6.5-8.3 um, approximately 1.8 times diameter of nucleolus. Contractile vacuole replaced after emptying by temporary hyaloplasmic area. Often with paired cytoplasmic inclusions, each pair in its own vesicle and one of pair crystalline. Floating form with small, bumpy projections, or with radiate hyaline pseudopodia tapering from a broad base but without regularly spherical central mass. No cyst known. Cuticle 180-200 nm thick; Golgi bodies sometimes paired. (ref. ID; 660)

Type locality

Freshwater, England. (ref. ID; 660)

Type slides

Holotype (1982:7:13:3) and paratype (1982:7:13:4), both prepared from strain 314, at British Museum (Natural History). (ref. ID; 660)

Measurements

Length of locomotive form 35-90 um, mean 57-65 um; mean length/breadth ratio 2.3-2.8. (ref. ID; 660)

Mayorella viridis Leidy, 1874 (ref. ID; 660, 3719)

Synonym

Amoeba viridis Leidy, 1874 (ref. ID; 3719)

Descriptions

Light microscopy: Examination of a hanging drop preparation by light microscopy showed the cell shape to be typically elongated, with the length always greater than the breadth. The length of 100 cells, measured from the uroid to the base of the pseudopodia, averaged 111 um, with a range of 61 um to 55.5 um. The uroid was often seen to be rounded. Blunt, hyaline, conical subpseudopodia are produced from the anterior hyaline region of the cell. When the amoeba is in motion the anterior subpseudopodia are rapidly overtaken by the active cytoplasmic streaming, new ones being formed very quickly. In the active state, conical subpseudopodia are also formed along the sides of the cell. The subpseudopodia do not control the direction of motion of the amoeba, which was 77 um per minute in its most active state. Granular endoplasm containing zoochlorellae streams rapidly towards the anterior end of the cell. No active ingestion was observed, and only one food vacuole per organism was seen, the contents of which appeared to be algal. The majority of cells however, seemed to lack and food vacuole. When present, a food vacuole is spherical and approximately 11 um in diameter, enlarging to 16 um before rapidly discharging the apparently only partly digested food remains. The nucleus is approximately central and is spherical, with central spherical nucleolus. The average diameter of the nucleus is 12.4 um, that of the nucleolus 7.6 um. In the culture medium M. viridis was observed to have numerous contractile vacuoles which reach a maximum diameter of 12 um prior to systole. The period from the commencement of diastole to systole is approximately 90 sec. These are readily observed when the cells have been left under a cover slip for a few minutes. Other vacuoles up to 18.5 um in diameter are also present throughout the endoplasm. No crystals were found. No dividing cells were seen. (ref. ID; 3719)
Electron microscopy: Preliminary studies of the fine structure of M. viridis were conducted by Miss S.M. Blakey and her results, as far as they involved the surface coat, were reported in paper read in 1977 before the British Section, Society of Protozoologists (Page & Blakey 1977). The cell coat exterior to the plasma membrane is 0.2 um thick and is composed of three layers. The layer adjacent to the membrane is composed of fibrils running parallel to the plasma membrane and is 94 nm thick. The next layer is 73 nm thick and consists of striations perpendicular to the plasma membrane. The outer layer is similar, but is only 33 nm wide. A gap of varying thickness separates the plasma membrane from the cell coat. The nucleus contains a large nucleolus of irregular outline, typically consisting of two heterogenous areas. Three membranes surround the nucleus, and vesicles present in the cytoplasm are concentrated around the surface of the nucleus. Active vesicle formation appears to occur from the outer membrane. The distance across the three membranes is 50 um. The outer membrane surrounding the nucleus may be smooth endoplasmic reticulum, as it appears to be more folded and less regular than the inner two membranes. Nuclear pores are 30 nm in diameter and appear to be spaced at intervals of up to 1.3 um. Mitochondria containing anastomosing cristae are found throughout the cell, but appears to be concentrated in the region of the zoochlorellae. They may be quite elongated, reaching a length of 1.6 um. The endozoic zoochlorellae are in membrane-bound vesicles and are typically 3x2 um in size. The vesicles were observed to sometimes be joined, with the zoochlorellae in direct contact with each other (possibly after cell division?). The algae have a typically chlorophycean structure with a plastid consisting of a bundle of 3 thylakoid membranes. The pyrenoid, approximately 1 um in diameter, is surrounded by a dominant starch sheath about 4.4 um across. The starch sheath is invaginated by 2 thylakoid lamellae, and the pyrenoid is transversed by one of them. Dictyosomes were seen throughout the cytoplasm and were observed to be either highly concave, or less concave. The distance across the stack of the highly concave dictyosome is 0.3 um. In the section obtained, it was not possible to determine the precise number of saccules. The distance across the less concave dictylosome is 0.7 um, and 7 saccules are present. Ribosomes are scattered throughout the cytoplasm associated with rough endoplasmic reticulum. Dense bodies are also found throughout the cytoplasm. (ref. ID; 3719)

Comments

Preliminary studies of the surface structure of M. viridis showed that it differed structurally and apparently chemically from the usual glycocalyx (Page & Blakey 1977). In a paper delivered to the Society of Protozoologists in 1977 they reported that the outer layer of the cell coat is the only one to give a positive reaction with the Thiery procedure for glycopolysaccharides. Another main feature of the ultrastructure of M. viridis is the close proximity of a third membrane to the nuclear membrane. This is probably endoplasmic reticulum and almost certainly accounts for the large number of vesicles surrounding the nucleus. (ref. ID; 3719)