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A new ganglion in male Moniliformis moniliformis (Acanthocephala).

A new ganglion identified as the bursal ganglion is described from male Moniliformis moniliformis. This ganglion is located adjacent to the pseudocoel and longitudinal muscle fibers and medial to the dorsal lacunar canal about 1 mm from the posterior end of males with non-everted bursa. The ganglion consists of four large club-shaped cells with single nuclei and bipolar neurons. The ganglion cells are paired with one neuron from each cell innervating the opposite side of the worm.

Acanthocephala↗

The cystacanth of Moniliformis moniliformis (Bremser, 1811) and its relationship with the haemocytes of the intermediate host (Periplaneta americana).

The nature of the capsule of the cystacanth of Moniliformis moniliformis was studied. Fat body, tracheal system, Malpighian tubules and haemocytes of the host are intimately associated with the cystacanth. The capsule of the cystacanth is cellular. The cells encapsulating the middle and late acanthellae are granular haemocytes of the host, whereas those encapsulating the cystacanth are agranular. Degranulation of haemocytes after encapsulation of the cystacanth recalls the common method for encapsulation of parasites of insect haemocytes, but a difference between the two kinds of encapsulation is that the capsule around the cystacanth does not bring about melanization nor destroys the parasite. It is suggested that the surface of the parasite may have inhibitors against enzyme systems causing melanization. Host haemocytes are also found in the capsular fluid. The infiltration of haemocytes into the capsule may be in response to the release of metabolites by the parasites. It is also suggested that the haemocytes may detoxify the parasitic metabolities. Rarely, capsules containing two parasites were observed. In one of the cases, one of the two cystacanths already possessed its own capsule. This finding, together with the cellular nature of the capsule, suggests that the capsule is of host origin.

Acanthocephala↗

Localization of phenoloxidase in the midgut of Periplaneta americana parasitized by larvae of Moniliformis moniliformis (Acanthocephala).

In cockroaches infected with Moniliformis moniliformis, the melanogenic enzyme phenoloxidase (PO) was histochemically localized in the posterior midgut and in haemocytes. Midguts were incubated with either 3-hydroxytyramine-HCl (dopamine) or 3-(3,4-dihydroxyphenyl)-L-alanine (dopa), and the resulting electron-dense reaction products of PO activity were found to be homogeneously distributed in the cytoplasm of both midgut cells and haemocytes. Following experimental infection, the first acanthors that reached the outer surface of the gut elicited a haemocyte response similar to that observed during wound healing. Larvae that remained attached to the gut became melanized or developed successfully. PO activity gradually decreased as the course of infection proceeded (10-50 days post-infection) but was apparently not inhibited in either midgut cells or haemocytes that were closely associated with the parasites. PO was lacking in the midgut cells of uninfected cockroaches. The results of the present study are discussed with respect to the defence reactions of the host and the survival mechanisms of the parasite.

Animals↗

Specificity of the surface aminopeptidase in Moniliformis moniliformis (Acanthocephala).

The hydrolysis of various oligopeptides in solution by intact Moniliformis moniliformis was examined using paper chromatographic analysis of the incubation medium. In the presence of transport inhibitors, the respective peptide sub-units and/or amino acid residues accumulated in the bathing medium. Only peptides with serine, methionine, leucine or alanine at the NH2-terminal end of the peptide were hydrolysed. There was no hydrolysis when these amino acids were located internally or at the COOH-terminus indicating genuine aminopeptidase activity of the class, alpha-aminoacylpeptide hydrolase. Hydrolysis was negligible when the NH2-terminus was arginine, aspartic acid, glutamic acid, glycine, histidine, lysine, phenylalanine, proline, tryptophan, tyrosine, or valine. In separate experiments, mediated uptake of 0.1 mM 3H-leucine by the worms in 2 min was inhibited 100% by 5 mM unlabelled leucine or tri-serine, but only partially inhibited by 5 mM Ser-Gly (66%), 10 mM Ser-Gly (74%), 5 mM Leu-Leu (69%), 10 mM Leu-Leu (70%), 5 mM Leu-Gly (58%) or 5 mM Met-Met (69%). Because the inhibitions produced by 5 mM Leu-Leu plus 5 mM Met-Met (79%) or 5 mM Leu-Leu plus 5 mM Ser-Gly (76%) were not additive, a single enzyme is indicated. The name serine aminopeptidase is proposed because of its preference for serine.

Acanthocephala↗

Survival of shelled acanthors of Moniliformis moniliformis (Acanthocephala) under laboratory conditions.

Shelled acanthors (= eggs) of two isolates of Moniliformis moniliformis (Acanthocephala) were tested for their capacity to respond to a hatching stimulus in vitro and for their retention of infectivity to a natural intermediate host (Periplaneta americana). The shelled acanthors were stored for more than 120 weeks (Australian isolate) and for 104 weeks (Texan isolate) together with rat faeces in an incubator maintained at 22.2 +/- 0.1 degrees C. In both cases, infectivity to P. americana was shown to have been retained. In vitro tests of the hatching response were carried out on many occasions during this period of faecal storage. Shelled acanthors continued to respond and no differences were detected either between isolates or within an isolate through time.

Acanthocephala↗

A simple method for the oral transfer of Moniliformis moniliformis (Acanthocephala) between rats.

A technique is described whereby young adult Moniliformis moniliformis, aged up to 7 days, can be transferred via the oral route from one rat to another. The method is dependent on giving the recipient rats a dose of Cimetidine (0.25 ml/250 g body weight of a solution containing 950 mg/ml) 1 h before transfer. Cimetidine functions as an H2-receptor antagonist and gastric acid secretion in the rat is inhibited temporarily. The technique does not appear to interfere with the reproductive biology of the parasite.

Acanthocephala↗

Linked metabolism of L-serine and L-alanine by Moniliformis moniliformis (Acanthocephala) in vitro.

Experiments to investigate the linked metabolism of L-serine and L-alanine by Moniliformis moniliformis in vitro were carried out by incubating adult worms aerobically for 3 h at 37 degrees C in Tyrode's solution containing L-[U-14C]alanine and other amino acids. When present in the medium alone, alanine was totally removed by the worms and metabolized almost entirely to ethanol and a compound identified as carbon dioxide. When present in the medium with serine and no other amino acids, alanine was largely metabolized as before but additional alanine, believed to originate from serine, was excreted. The same results were obtained with serine and 16 other amino acids in the incubation medium.

Acanthocephala↗

Features of amino acid metabolism in Moniliformis moniliformis (Acanthocephala) in vitro.

Experiments to investigate the metabolism of glycine, L-glutamic acid and L-aspartic acid by Moniliformis moniliformis were carried out by incubating adult worms aerobically for 3 h at 37 degrees C in Tyrode's solution containing either [U-14C]glycine, L-[U-14C]glutamic acid, L-[U-14C]aspartic acid or L-[4-14C]aspartic acid. Much of the glycine and glutamic acid was absorbed by the worms, but little of either was metabolized. Aspartic acid was readily taken up and metabolized. After incubating with L[U-14C]aspartic acid, most radioactivity was found in ethanol and a volatile compound, presumed to be carbon dioxide, with smaller amounts in lactate, alanine, acetate, malate, glucose and succinate. After incubating with L-[4-14C]aspartic acid, most radioactivity was found in lactate and the presumed CO2 with small amounts in alanine, malate and succinate. No radioactivity was found associated with ethanol or acetate. Possible metabolic pathways and suggestions for a relationship between the metabolism of aspartate with that of alanine and serine in this parasite are discussed.

Acanthocephala↗

A comparison of behavioral alterations in the brown cockroach, Periplaneta brunnea, and the American cockroach, Periplaneta americana, infected with the acanthocephalan, Moniliformis moniliformis.

We examined behavioral alterations in the brown cockroach, Periplaneta brunnea, infected with the acanthocephalan, Moniliformis moniliformis. The responses of infected and uninfected P. brunnea to light, substrate choice, and activity were compared. Infected brown cockroaches spent more time on white horizontal substrates under red and white light. Infected brown cockroaches also had a shorter freeze time than uninfected cockroaches after being presented with a light source. There was no difference in photophilia or activity of infected and uninfected brown cockroaches. These behavioral alterations in brown cockroaches were compared to those in Periplaneta americana, the American cockroach, infected with the same parasite. American and brown cockroaches differed in some responses to substrate, phototaxis, and activity.

Animals↗

The possible influence of male worm age on the fecundity of Moniliformis moniliformis (Acanthocephala) in laboratory rats.

During the course of a primary infection of Moniliformis moniliformis in rats, involving an experimentally structured population of worms derived from infective doses of 10 male and 10 female cystacanths per rat, the fecundity of the female worms appeared to be influenced by the age of the males. The experimental design ensured that all the female worms were 35 days old when fecundity was assessed. On average, the number of eggs in females recovered from rats containing 28-day-old males was 20,930 +/- 2,143, that from rats containing 35-day-old males was 7,434 +/- 937, and that from 42-day-old males was 14,396 +/- 1,704; these values were found to be significantly different (least significant difference, P less than or equal to 0.01). The results suggest that the variable age of the worms would be likely to favor fecundity in naturally occurring infections.

Acanthocephala↗

Ultrastructural study of the host-parasite interface of Moniliformis moniliformis (Archiacanthocephala) in laboratory-infected rats.

The fine structure of the host-parasite interface of Moniliformis moniliformis in rats is described, comprising investigations on the ontogenic development of the presomal tegument, on the lesions caused by the worms, and on the host cellular reactions at the points of attachment of the worm. The presomal tegument of the worm contained more fibrous elements than the metasomal tegument. The sclerotization increased with the ages of the worms and toward the tip of the proboscis. The presomal surface coat was more coarsely structured and osmiophilic than that of the metasoma and was neither continuous with the contents of the tegumental crypts nor supported by lipids from necrotic host tissue. The surface coat occasionally detached from the proboscis, probably due to the activity of the surrounding granulocytes of the host. The proboscis hooks lost their tegumental covering during their larval development. Hooks of all worms from rats were invested with a semiliquid lipid coat, apparently derived from tegumental excretions at the base of the hooks. The invaginated area of excretion around the base of the hooks was rich in endoplasmic reticulum. The hooks seemed to renew their lipid coats at certain intervals by dipping into the excreted lipid. In rats all worms, irrespective of their age, attached superficially, penetrating only the intestinal mucosa and the tunica propria. No fibrous connective tissue was found in the lesions caused by the worms, indicating that they frequently changed their site of attachment. At 3-10 days postinfection the host's defense cells observed in the lesions consisted mainly of granulocytes, whereas plasma cells were the predominant leukocytes in lesions of older infections.

Acanthocephala↗

Ultrastructural morphology of the neuropile of the cerebral ganglion of Moniliformis moniliformis (Acanthocephala).

The cerebral ganglion of Moniliformis moniliformis consists of an outer single layer of cell bodies and an inner core of neuropile occupied by cellular processes. Morphological characteristics of 5 types of cellular processes have been described. Most of the processes in the neuropile were of large size, although sites containing numerous small processes (neurites) were also observed. Small processes in the neuropile were the sites of synaptic interaction. The majority of presynaptic membranes were well defined by the presence of electron-dense material at the inner leaflet, while postsynaptic membranes appeared to lack marked postsynaptic density. Round or flattened lucent vesicles were concentrated around the presynaptic membranes. Electron-dense and dense-cored vesicles were usually separated from the clear vesicles and situated at some distance from synaptic sites.

Acanthocephala↗

Anatomy of the genital ganglion of the male acanthocephalan, Moniliformis moniliformis.

Male Moniliformis moniliformis possess paired genital ganglia each measuring approximately 280 micron long by 80 micron wide by 25 micron thick. They are located on either side of Saefftigen's pouch on the ventral surface of the ejaculatory duct where it joins the bursal cap. The cellular organization consists of externally located soma and a poorly developed internal neuropile. Most of the 19 cells in each ganglion exit via axons from the anterior and posterior extremities. A single dorsal commissure connects the 2 ganglia. No ventral commissure was observed. Many cells contained large nuclei with perinuclear rings but no cell had 2 nuclei.

Acanthocephala↗

Ultrastructural morphology of the nerve cells in the cerebral ganglion of the Acanthocephalan Moniliformis moniliformis.

The morphology of the cerebral ganglion of the Acanthocephalan Moniliformis moniliformis was studied in serial sections using electron microscopy. The organization of the cerebral ganglion was typical of other invertebrates with the cell bodies forming a rind, 1 cell thick, and their processes forming the central core of the neuropile. The ganglion was surrounded by a connective tissue capsule composed of collagen-like fibrils. Externally, the free surface of the cell bodies was covered by an electron-dense extracellular lamina. Seventy-six cells were identified in every ganglion examined and, on the basis of their cellular characteristics, they were divided into 5 distinct cell types, classified as type A, B, C, D and E cells. The characteristic morphological features of each cell type have been described, and the distribution of the different cell types in the cerebral ganglion was mapped.

Acanthocephala↗

Morphogenesis of the proboscis hooks of an archiacanthocephalan, Moniliformis moniliformis (Bremser 1811) Travassos 1915.

Proboscis hooks of Moniliformis moniliformis were noted first as small protrusions on developing proboscides of 20- to 28-day-old acanthellae from hemocoels of experimentally infected cockroaches (Periplaneta americana). On the basis of proximity, residual connecting strands of tissue, and ultrastructural similarity, origin of the hooks has been determined to be from primordial muscle tissue. During development, primordial proboscis hooks extended into hypodermal tissue, but remained separated by the basement membrane and a characteristic space. Within this space, under the curvature of the hook, fibrous material began to accumulate at about 38 days during development. The fibrous material appeared to be produced at the distal end of the primordial hook as evidenced by the appearance of organelles in that area, and the compact, parallel nature of fibrous material immediately adjacent. Upon completion of development, the proboscis hook of the 46- to 54-day-old acanthella was observed to consist of a central core of parallel fibrous material, an outer layer of crisscrossed fibers, and a thin covering of hypodermis and cuticle.

Acanthocephala↗

Altered behavior in two species of blattid cockroaches infected with Moniliformis moniliformis (Acanthocephala).

Moniliformis moniliformis-infected Periplaneta australasiae and Blatta orientalis were less active than uninfected controls in behavioral arena tests under both red and white light regimes. There was a strong interaction between light regime and parasitism for substrate use by P. australasiae. Under red light, parasitism decreased the use of black horizontal surfaces, whereas under white light, parasitism increased the use of black horizontal surfaces. In contrast, B. orientalis substrate use was unaffected by parasitism, although infected animals were less active than uninfected conspecifics under both light regimes. For both species, parasitism did not change the percentage of time spent in light, the freeze time, or the directional response to light.

Animals↗

Syncytial organization of acanthors of Polymorphus minutus (Palaeacanthocephala), Neoechinorhynchus rutili (Eoacanthocephala), and Moniliformis moniliformis (Archiacanthocephala) (Acanthocephala).

The fine structures of immature and of developed shelled acanthors of three species belonging to the three subgroups of the Acanthocephala were investigated. Acanthors are surrounded by four eggshells (embryonic envelopes) and are composed of three syncytia: a frontal syncytium, a central syncytium, and an epidermal syncytium. Neither a sense organ nor a nervous system has been found. The central syncytium shows a mass of condensed nuclei and 12 decondensed nuclei and gives rise to 10 anterior/posterior subepidermal myofibrillar systems and 2 oblique retractor muscles. Circular muscles are missing. A single decondensed nucleus can be assigned to each of the 12 muscular systems. The epidermal syncytium embeds the other two syncytia and forms the wrinkled epidermis, which shows an extracellular glycocalyx and intrasyncytial condensations. Prominent recurved hooks, which mark the anterior end of each acanthor, and body spines are intraepidermal differentiations. Partly branched tubular infoldings of the epidermal plasma membrane of the acanthor exist and represent precursors of the pore ducts typical of the adult epidermis. Autapomorphies in the ground pattern of the monophylum Acanthocephala are the four eggshells, the early development of three syncytia, the condensed nuclei in the central syncytium, and the differentiation of ten longitudinal muscle bands and two muscle retractors and of intraepidermal hooks and spines. The syncytial organization of the epidermis with intraepidermal skeletal condensations and infoldings of the apical plasma membrane are characteristics inherited from a stem species common to Acanthocephala, Seison, and Rotifera.

Acanthocephala↗