Trypanosoma vivax Adhesion to Red Blood Cells in Experimentally Infected Sheep

Trypanosomosis, a globally occurring parasitic disease, poses as a major obstacle to livestock production in tropical and subtropical regions resulting in tangible economic losses. In Latin America including Venezuela, trypanosomosis of ruminants is mainly caused by Trypanosoma vivax. Biologically active substances produced from trypanosomes, as well as host-trypanosome cellular interactions, contribute to the pathogenesis of anemia in an infection. The aim of this study was to examine with a scanning electron microscope the cellular interactions and alterations in ovine red blood cells (RBC) experimentally infected with T. vivax. Ovine infection resulted in changes of RBC shape as well as the formation of surface holes or vesicles. A frequent observation was the adhesion to the ovine RBC by the trypanosome’s free flagellum, cell body, or attached flagellum in a process mediated by the filopodia emission from the trypanosome surface. The observed RBC alterations are caused by mechanical and biochemical damage from host-parasite interactions occurring in the bloodstream. The altered erythrocytes are prone to mononuclear phagocytic removal contributing to the hematocrit decrease during infection.

The flagellum and tempers of some male tiger beetles (Coleoptera: Carabidae: Cicindelinae)

The male flagellum of 32 North American tiger beetle (Cicindela Linnaeus; Coleoptera: Carabidae: Cicindelinae) species was examined with a scanning electron microscope for new, stable characters that might be useful in studies of taxonomy and functional morphology. Two sets of characters were observed, shape and size of the flagellum, and the form and distribution of tempers (micro teeth-like structures on the surface of the flagellum). These characteristics were surprisingly uniform for most species. It is inferred that the inner walls of the female spermatheca duct are gripped by the male flagellum, achieved either by flexing the inserted temper-free long flagellum, or direct insertion by the temper-covered short flagellum. It is proposed that an inverse relationship pattern exists between the elongate temper-free flagellum, and the temper-covered shorter flagellum.

Spermatological characteristics of Elstia stossichianum (Digenea, Mesometridae) from the intestine of the cow bream (Sarpa salpa) off Dakar, Senegal

The current study was designed to increase the spermatological ultrastructural database on Digenea, thus contributing to the future establishment of phylogenetic relationships within this group based on ultrastructural characteristics of both spermiogenesis and spermatozoa. Spermiogenesis in Elstia stossichianum begins with the formation of a differentiation zone containing two centrioles, two striated rootlets, a nucleus, several mitochondria and an intercentriolar body constituted by seven electron-dense layers. Each centriole develops into a free flagellum growing orthogonally to the median cytoplasmic process. Proximo-distal fusion of the flagella with the median cytoplasmic process occurs after flagellar rotation. Both nucleus and mitochondria migrate before the complete proximo-distal fusion of both flagella with the median cytoplasmic process. Finally, the constriction of the ring of arched membranes gives rise to the young spermatozoon. The mature spermatozoon of E. stossichianum exhibits two axonemes of different length of the 9+‘1’ trepaxonematan pattern, a nucleus, a mitochondrion, two bundles of parallel cortical microtubules, external ornamentation of the plasma membrane, a lateral expansion, spine-like bodies, cytoplasmic ornamented buttons and granules of glycogen. The formation of cytoplasmic ornamented buttons during the final stages of spermiogenesis is reported here for the first time.

Spermiogenesis and ultrastructure of the spermatozoon of Wardula capitellata (Digenea, Mesometridae), an intestinal parasite of the sparid teleost Sarpa salpa in Senegal

The spermiogenesis process in Wardula capitellata begins with the formation of a differentiation zone containing two centrioles associated with striated rootlets and an intercentriolar body. Each centriole develops into a free flagellum orthogonal to a median cytoplasmic process. Later these flagella rotate and become parallel to the median cytoplasmic process, which already exhibits two electron-dense areas and spinelike bodies before its proximodistal fusion with the flagella. The final stage of the spermiogenesis is characterized by the constriction of the ring of arched membranes, giving rise to the young spermatozoon, which detaches from the residual cytoplasm. The mature spermatozoon of W. capitellata presents most of the classical characters reported in digenean spermatozoa such as two axonemes of different lengths of the 9 + “1” trepaxonematan pattern, nucleus, mitochondrion, two bundles of parallel cortical microtubules and granules of glycogen. However, some peculiarities such as two lateral expansions accompanied by external ornamentation of the plasma membrane and spinelike bodies characterize the mature sperm. Moreover, a new spermatological character is described for the first time, the so-called cytoplasmic ornamented buttons.

Ultrastructure of spermiogenesis in the caryophyllidean cestode Wenyonia virilis Woodland, 1923, with re-assessment of flagellar rotation in Glaridacris catostomi Cooper, 1920

The ultrastructure of spermiogenesis in Wenyonia virilis Woodland, 1923, a caryophyllaeid cestode from the silurid Nile fish Synodontis schall (Bloch et Schneider, 1801), is described by means of transmission electron microscopy (TEM) for the first time. Spermiogenesis follows the characteristic caryophyllidean type and is initiated by the formation of a differentiation zone. This area, delimited at its base by a ring of arching membranes and bordered by cortical microtubules, contains two centrioles associated with typical striated rootlets with a reduced intercentriolar body between them. The apical area of the differentiation zone exhibits electron-dense material that is present only during the early stages of spermiogenesis. Only one of the centrioles develops into a free flagellum that grows at an angle of >90° in relation to the cytoplasmic extension. Spermiogenesis is also characterized by a flagellar rotation and a proximodistal fusion of the flagellum with the cytoplasmic extension. The most interesting features observed in W virilis are the presence of a reduced, very narrow intercentriolar body and the unique type of flagellar rotation >90°. Results are compared with those described in two caryophyllideans, Glaridacris catostomi Cooper, 1920 and Khawia armeniaca (Cholodkovski, 1915). Contrary to the original report of Świderski and Mackiewicz (2002), that flagellar rotation has never been observed in spermiogenesis of G. catostomi, re-assessment of their description and illustrations leads us to conclude that flagellar rotation must logically occur in that species. The value of various morphological features of sperm in phylogenetic inference is discussed.

Ultrastructure of spermiogenesis and mature spermatozoon of Skrjabinoporus merops (Cyclophyllidea, Metadilepididae)

The ultrastructure of the mature spermatozoon and the spermiogenesis of a cestode belonging to the family Metadilepididae is described for the first time. The mature spermatozoon of Skrjabinoporus merops is characterized by twisted peripheral microtubules, the presence of a single crested body, periaxonemal sheath and electron-dense rods, and the absence of intracytoplasmic walls and inclusions (glycogen or proteinaceous granules); no peripheral microtubules where nucleus contacts the external plasma membrane. Four morphologically distinct regions of the mature spermatozoon are differentiated. The proximal part (Region I) contains a single crested body, periaxonemal sheath is absent in some (proximal) sections and is present in others situated closer to the nucleus. The central Region II is nucleated, and is followed by Region III that contains a periaxonemal sheath. The distal pole, Region IV, is characterized by disintegration of the axoneme. Spermiogenesis follows the type III pattern (Bâ and Marchand 1995) although in S. merops a slight flagellar rotation is observed. The differentiation zone is characterized by the absence of striated roots and intercentriolar body; two centrioles are present, one of which gives rise to a free flagellum. The latter rotates and undergoes proximodistal fusion with the cytoplasmic protrusion of the differentiation zone. Spermiological characters of S. merops are similar to those of the families Taeniidae and Catenotaeniidae. The mature spermatozoon differs from those of the Dilepididae (where the metadilepidid species have previously been classified) by the lack of glycogen.

Trypanosoma (Nannomonas) godfreyi sp. nov. from tsetse flies in The Gambia: biological and biochemical characterization

SUMMARYWe provide evidence from isoenzyme analysis, hybridization with repetitive DNA probes, behavioural studies and morphometrics that 4 trypanosome isolates from Glossina morsitans submorsitans in The Gambia constitute a new species now named Trypanosoma (Nannomonas) godfreyi. The bloodstream trypomastigotes of T. (N.) godfreyi are relatively small with a mean length of 13·7 μm (range: 9·1–21·8 μm) and a mean width of 1·65 μm (range: 0·65–2·69 μm). There is no free flagellum and the marginal kinetoplast is subterminal to a rounded posterior end; the undulating membrane is usually conspicuous. As with other Nannomonas, T. godfreyi developed in the midgut and proboscis of Glossina and infections matured in 21–28 days in laboratory G. m. morsitans. In The Gambia the normal vertebrate host appears to be the warthog, Phacochoerus aethiopicus, although elsewhere other wild and domestic suids may also be implicated in the life-cycle. T. godfreyi was identified unequivocally using a 380 bp DNA probe specific for a major genomic repeat sequence; its isoenzyme profile distinguished it clearly from T. simiae and three strain groups of T. congolense: savannah, riverine-forest and kilifi.

Hematozoa of Fishes From Heron Island, Australia, With the Description of 2 New Species of Trypanosoma

Two species of Trypanosoma, three species of Haemogregarina and one species of Haemohormidium were found in 69 fishes belonging to 28 species. Trypanosoma mackerrasi, sp, nov., from Hemiscyllium ocellatum, measures 125 �m long by 18 �m wide, has no free flagellum, and has the kinetoplast located 37% of the body length from the posterior end. Trypanosoma taeniurae, sp. nov., from Taeniura lymma measures 55 �m long by 4 �m wide and has a free flagellum 9 �m long. Haemogregarina hemiscyllii was found in H. ocellatum, H. tetraodontis parasitised Diodon hystrix, and H. bigemina was found in Ecsenius bicolor. A species of Haemohorrnidium was found in Pomacentrus melanochir, but it could not be identified with certainty.

Flagellar Attachment in Selected Trypanosomes

Movement in epimastigote and trypomastigote stages of trypanosomes is accomplished by planar sinusoidal beating of the anteriorly directed flagellum and associated undulating membrane. The flagellum emerges from a bottle-shaped depression, the flagellar pocket, opening on the lateral surface of the cell. The limiting cell membrane envelopes not only the body of the trypanosome but is continuous with and insheathes the flagellar axoneme forming the undulating membrane. In some species a paraxial rod parallels the axoneme from its point of emergence at the flagellar pocket and is an integral component of the undulating membrane. A portion of the flagellum may extend beyond the anterior apex of the cell as a free flagellum; the length is variable in different species of trypanosomes.

Trypanosoma superciliosaesp.nov. from the lizardUranoscodon superciliosaL.

This paper records the presence of a new species of trypanosome in the lizardUranoscodon superciliosaL. (family Iguanidae), caught near Codajaz, Amazonas, Brazil, in August 1964 during the Guy's Hospital Expedition to the Lower Amazon.Examination of a methanol-fixed and Giemsa-stained smear of blood taken from the heart of the lizard showed a heavy infection of trypanosomes. Camera lucida drawings of twenty were made, measurements being determined with dividers and a map-measuring wheel. The animal was preserved in 10% formalin, portions of liver, spleen, brain, heart, and lung being later extracted. Sections 5μin thickness were cut and stained in Ehrlich's haematoxylin and eosin, and in Giemsa's stain.The chief distinguishing feature of the trypanosomes was their comparatively enormous size, up to 124μin total length, including the free flagellum, and 19μin width. The cytoplasm stained deep blue in Giemsa's stain, there being little indication of any vacuoles or inclusions. The posterior end was generally less intensely stained, and in certain cases pale, narrow, channel-like extensions from this region forward into the main body of the organism could be detected (Fig. 1). The nucleus, elongated and rather variable in shape, was distinguished by being less deeply coloured than the surrounding cytoplasm; it lay slightly posterior to the mid-point of the body, its longest diameter being parallel to the longitudinal axis of the animal. The kinetoplast, situated slightly posterior to the nucleus, was usually of circular shape, staining deep red; from it arose the flagellum, which passed forward along the margin of an undulating membrane and terminated in a free portion at the anterior end. Measurements of the organisms are given in Table 1.