The origins and evolutionary expansion of the Strongylida (Nematoda)

The Strongylida are thought to have arisen from free-living rhabditoid nematodes, but the relationships between the major groupings within the Strongylida, the Strongylina, the Metastrongylina, Trichostrongylina and the Ancylostomatina are far from clear in spite of the abundance of morphological data now available for analysis. Evolutionary mechanisms including co-evolution, host switching, host dispersal, use of intermediate hosts, various sites of localisation within the definitive host and modifications of life-cycle strategies appear to have been utilised in the expansion of the Strongylida, with different mechanisms predominating in different families or superfamilies. Co-evolution appears to have been a major mode of evolution in the Strongylina, in contrast to the Trichostrongylina, which have used host dispersal and host-switching to great advantage. The phylogeny of the Ancylostomatina shows little association with host evolution, but does match the feeding preferences of the hosts. The Metastrongylina have utilised intermediate hosts and life cycle modifications including a shift to extra-intestinal sites as major means of diversification, in contrast to the other sub-orders. The review, while indicating much progress in our understanding of the phylogeny of the Strongylida, also reveals that enormous gaps still exist, and emphasises the tentative nature of many of the phylogenetic hypotheses tendered to date.     

A cladistic analysis of the genera in the subfamily Pudicinae (Nematoda, Trichostrongyloidea, Heligmonellidae).

A parsimony analysis was performed on 37 specific taxa belonging to the subfamily Pudicinae (family Heligmonellidae), which contains parasites mainly from South American caviomorph rodents. Thirteen characters were used from the synlophe (rotation of axis, presence of carene, carene asymmetry, presence of comaretes, single ventral comarete length, ridge discontinuity, ventral ridge numbers, presence of a peculiar posterior synlophe, presence of supernumerary spines) and the male caudal bursa (relative length of rays 9 and 10, caudal bursa type, division of the dorsal ray, divergence of the 10th rays). The cladogram shows a consistency index of 1.0. The subfamily Pudicinae has two synapomorphies. Two suprageneric groups are recognized. Suprageneric group 1 shows one synapomorphy and contains Heligmostrongylus, Fuellebornema, Sciurodendrium and Pseudoheligmosomum; suprageneric group 2 shows two synapomorphies and contains Pudica, Acanthostrongylus, Justinema and Durettestrongylus. Five genera are defined on the basis of synapomorphies. The genera Heligmostrongylus, Sciurodendrium and Pudica which are considered paraphyletic, however, are retained due to lack of knowledge as to their relationships.     

Description of Haemonchus placei (Place, 1893) (Nematoda, Trichostrongylidae, Haemonchinae), identification and intra-specific morphologic variability

Haemonchus placei in cattle has never been completely described, possibly due to great morphological similarity with small ruminants Haemonchus contortus. It is newly described on one isolate from Argentina. It has clear distinct morphological features from sheep and goats Haemonchus contortus and presents only two female morphotypes (linguiform and knobbed) instead of three recorded in H. contortus. A key is proposed to identify females. Female as well as male Haemonchus placei from New World (Argentina, Mexico, USA) are morphologically different from those of Old World (Africa: Burkina-Faso, Mauritania and Ivory Coast) or Australia, possibly due to local evolution since their introduction several centuries ago from Africa or India. We propose to differentiate three sub-species, H. placei placei in Australia, H. placei africanus in western Africa and H. placei argentinensis in the New World.     

A new genus of Nippostrongylinae (Nematoda: Heligmonellidae) from the water rat Scapteromys aquaticus (Sigmodontinae) in Argentina

A new genus of Nippostrongylinae, Malvinema n. gen., with 3 coparasitic species M. frederici n. sp., M. carolinae n. sp., and M. victoriae n. sp. from the intestine of the water rat, Scapteromys aquaticus Thomas (Rodentia: Muridae), from the northeast of Buenos Aires Province, Argentina, is proposed in this study. The new genus shows similarities to 2 Neotropical Nippostrongylinae: Carolinensis (Travassos, 1937) by some characters of the synlophe and Stilestrongylus Freitas, Lent and Almeida, 1937, by the pattern of the caudal bursa. It is characterized by a synlophe with triple or quadruple gradient of size of the ridges, lateromedian, decreasing from the largest left and right ridges. The gradient situated in the right ventral quadrant is always present. The caudal bursa shows a pattern of type 1-4. Malvinema frederici possesses a synlophe with 17 ridges and an axis of orientation inclined at 45 degrees from the sagittal axis; M. carolinae possesses a synlophe with 22-24 ridges and an axis of orientation almost merged with the sagittal axis. Both species have a caudal bursa with the right lobe enlarged transversally. Malvinema victoriae possesses a synlophe with 22-24 ridges, an axis of orientation inclined at 45 degrees from the sagittal axis, and a caudal bursa with the right lobe enlarged vertically.     

Molineus torulosus (Nematoda, Trichostrongylina, Molineoidea) a parasite of Neotropical primates: new morphological and histological data

Molineus torulosus (Molin, 1861) parasite of Cebus spp. from South America is redescribed in Cebus apella and C. olivecaeus (new host) from French Guyana with emphasis on the synlophe. During the maturation process, the larvae dwelt in the cysts carved alongside the external part of the small intestine. The turn-out of the mature worms and the laid eggs depended on the tissular organisation of cyst walls as the inflammatory process waned and fibrosis progressed to seal the cystic lumen. Adult worms entwine themselves in the cysts, live there permanently as their presence has never been evidenced in the intestinal lumen. They copulated, laid eggs, degenerated and died once entrapped by the fibrotic process. Laid eggs released in the intestinal lumen through a narrow channel ensured the continuation of the developmental cycle. However, erratic migration was possible via the vascular channels surrounding the cysts.     

Life cycle of Trichostrongylus retortaeformis in its natural host,the rabbit (Oryctolagus cuniculus)

The chronology of the life cycle of Trichostrongylus retortaeformis (Zeder, 1800) (Nematoda, Trichostrongyloidea) is studied in its natural host Oryctolagus cuniculus. The free living period lasted 5 days at 24 degrees C. Worm-free rabbits were each infected per os with T. retortaeformis larvae. Rabbits were killed at 12 h post-infection (p.i.) and every day from one day to 13 days p.i. By 12 h p.i., all the larvae were exsheathed and in the small intestine. The third moult occurred between 3 and 5 days p.i. and the last moult between 4 and 7 days p.i. The prepatent period lasted 12 to 13 days. The patent period lasted five and a half months. The four known life cycles of species of Trichostrongylus in ruminants were compared with that of T. retortaeformis. No significant difference was found except in the duration of the prepatent period. These similarities in the life cycles confirm the previously formulated hypotheses on the relationship between the parasites of the two host groups (Durette-Desset, 1985).     

Trichostrongylina (Nematoda) from Malagasy muridae. II--Description of two new species of Heligmonina (Heligmonellidae) in Nesomys rufus and Eliurus tanala

Two new species of Heligmonellidae from Madagascar are described, Heligmonina madagascariensis n. sp. in Nesomys rufus and Heligmonina tanala n. sp. in Eliurus tanala. Both species belong to the Heligmonina species with a pattern of type 1-3-1 for the right lobe of the caudal bursa and 1-4 for the left lobe. In H. madagascariensis, H. dupuisi (Desset, 1964) and H. praomyos Baylis, 1928, left ray 6 arises before ray 3 from the common trunk to rays 3 to 6 while in H. tanala and the other species, it arises at the same level. H. madagascariensis is differentiated from H. dupuisi and H. praomyos by the symmetry of the branches of the dorsal ray. H. tanala is differentiated from H. malacomys Sakka & Durette-Desset, 1988, the closely related species by a different pattern of the cuticular ridges at mid-body, by the sharpness of the tips of the spicules and by the ratio of the length of the spicules on the length of the body (6.9, 8.8% versus 25-27.8%). Heligmonina chippauxi (Desset, 1964) a parasite of Oenomys hypoxanthus from the Republic of Central Africa is considered a valid species.     

Ultrasound imaging in an experimental model of fatty liver disease and cirrhosis in rats

Background

Atypical scrapie was first identified in Norwegian sheep in 1998 and has subsequently been identified in many countries. Retrospective studies have identified cases predating the initial identification of this form of scrapie, and epidemiological studies have indicated that it does not conform to the behaviour of an infectious disease, giving rise to the hypothesis that it represents spontaneous disease. However, atypical scrapie isolates have been shown to be infectious experimentally, through intracerebral inoculation in transgenic mice and sheep. The first successful challenge of a sheep with 'field' atypical scrapie from an homologous donor sheep was reported in 2007.

Results

This study demonstrates that atypical scrapie has distinct clinical, pathological and biochemical characteristics which are maintained on transmission and sub-passage, and which are distinct from other strains of transmissible spongiform encephalopathies in the same host genotype.

Conclusions

Atypical scrapie is consistently transmissible within AHQ homozygous sheep, and the disease phenotype is preserved on sub-passage.     

Mapping of citrullinated fibrinogen B-cell epitopes in rheumatoid arthritis by imaging surface plasmon resonance

Introduction  

Rheumatoid arthritis (RA) frequently involves the loss of tolerance to citrullinated antigens, which may play a role in pathogenicity. Citrullinated fibrinogen is commonly found in inflamed synovial tissue and is a frequent target of autoantibodies in RA patients. To obtain insight into the B-cell response to citrullinated fibrinogen in RA, its autoepitopes were systematically mapped using a new methodology.