Cytogenetics of Dictyocaulus arnfieldi (Cobbod, 1884) Railliet and Henry, 1907

A cytogenetic study of Dictyocaulus arnfieldi was made for the first time. The diploid chromosome number was 2n = 11 for males and 2n = 12 for females; there was an XO/XX sex determinism mechanism. Diplotene stage showed bivalents with 3, 2 or 1 chiasmata. The possible differences in the evolution of D. arnfieldi and Dictyocaulus filaria are discussed.     

The spermatogenesis of Dictyocaulus filaria (Nematoda, Trichostrongyloidea)

A cytological study was carried out, using male Dictyocaulus filaria, that revealed the diploid number of chromosomes was 2n = 11 and the sex determining mechanism was XO. The behaviour of the chromosomes in the different stages of meiosis was also investigated. Cross, open ring and rod bivalents were observed in diakinesis. The chromosomes appeared to be acrocentric since they acquired a radial disposition in Metaphase-II. The chiasma frequency was 1 and the nucleolus-organizing region was located at the ends of the chromosomes.     

The life cycle of Euclinostomum heterostomum (Rudolphi, 1809) (Trematoda: Clinostomatidae)

In small forest streams of West Nigeria the snail species Bulinus globosus was found to be the first intermediate host of a clinostomatid species which proved in successful infection experiments with the cichlid fish Tilapia zillii as second intermediate host to be Euclinostomum heterostomum (Rudolphi, 1809). Final hosts are herons. The morphology of the redia and the morphology and behaviour of the cercaria are described for the first time. The metacercaria which settles dorsal to the swim-bladder or in the kidney of the host fish requires more than two months (at tropical temperatures) for full development. Histological sections of the metacercaria revealed that its pharynx is provided with only few muscle fibres but surrounded by many myoblast-like cells, and the fact that the interior surface of this organ has a dense brush-like lining consisting of long microtriches. The pathology of infected fish is briefly described, and remarks about the geographical distribution of the parasite are given.     

Prevalence of Dictyocaulus arnfieldi (Cobbald, 1884) Railiet & Henry 1907, in Pantaneira breed horses of the region of Pocone, MT

The authors sacrificed fifty-five horses originated from the "Pantanal", lowlands in the State of Mato Grosso in two different periods, droughty period and flooded and they described for the first time the Dictyocaulus arnfieldi in Mato Grosso. Relationship between droughty and flooded periods proved not to occur.     

Karyological studies on three strigeid digeneans: Ichthyocotylurus erraticus (Rudolphi, 1809), I. variegatus (Creplin, 1825) and Apatemon gracilis (Rudolphi, 1819)

Previous work has shown that karyology may be a valuable technique for discriminating morphologically similar species. In the present study, chromosome number and morphology were described for three strigeid species, Ichthyocotylurus erraticus (Rudolphi, 1809), I. variegatus (Creplin, 1825) and Apatemon gracilis (Rudolphi, 1819). The results show that these species possess the same diploid number of chromosomes (2n = 20) in somatic cells. The relative length and the position of the centromere were determined, and significant inter-specific differences in the karyotypes are demonstrated, enabling the ready discrimination of I. erraticus and I. variegatus cercariae. A review of known karyotypes of the family Strigeidae suggests that possible routes of evolutionary changes involve pericentric inversions within chromosomes rather than Robertsonian translocations between elements.     

Euclinostomum heterostomum (Rudolphi, 1809) (Trematoda): life-cycle,growth and development of the metacercaria and adult

The life-history of Euclinostomum heterostomum (Rudolphi, 1809), a clinostomid trematode occurring in the oesophagus and buccal cavity of pond heron Ardeola grayii and cattle egret Bubulcus ibis at Visakhapatnam, India, has been traced from egg to adult stage, based on field and laboratory studies. Eggs released by gravid flukes hatched into miracidia in 10 days. The snail Indoplanorbis exustus served as the first intermediate host and the intramolluscan phase, involving the development of two redial generations and cercariae, took two months. Natural infections with the metacercaria were found in the kidneys and liver of the fish Channa punctatus and muscles of C. orientalis. Laboratory experiments demonstrated that more than 2 months are required for the development of the cercaria into the infective metacercarial stage. The morphology of all of the stages in the life-cycle has been studied in detail, as well as the growth characteristics of the metacercaria within the fish host. Two phases in the metacercarial growth were noted, a lag phase followed by an exponential phase. Allometric growth parameters of body proportions and organs of the metacercaria and the adult are compared. The validity of various species included in the genus Euclinostomum is discussed.     

Chromosome complement, C-banding and Ag-NOR in Gymnammodytes cicerelus (Ammodytidae, Perciformes)

The karyotype of a sandlance species, Gymnammodytes cicerelus , comprises: seven meta-centric, seven submetacentric and nine subtelocentric-acrocentric pairs (2 n =46, FN=74). The C-bands appear in paracentromeric and telomeric areas of most chromosomes and the NOR regions, in two pairs of larger chromosomes. All these characteristics indicate that a large number of rearrangements seem to have been involved in the karyotype evolution of this species.     

The characterization of somatic chromosomes of Gymnothorax unicolor (Delaroche, 1809) by C-banding and NOR staining (Osteichthyes,Anguilliformes)

The diploid chromosome number of Gymnothorax unicolor (Delaroche, 1809) is 2n=42, the karyotype comprising six pairs of meta-submetacentric and fifteen pairs of acrocentric chromosomes. C-positive chromatin is present in the centromeres of all chromosomes as well as in the paracentromeric regions of some chromosomes. A nucleolar organizer region was identified on the long arm of chromosome 9, near the centromere. This region is also positive to C-banding.Cytotaxonomical relationships are evidenced between the described karyotype and that of the related species Muraena helena.     

Phylogenetic relationships of Echinostoma Rudolphi, 1809 (Digenea: Echinostomatidae) and related genera re-assessed via DNA and morphological analyses

In order to investigate the relationships within the Echinostomatidae two data sets of gene sequences were analysed. The first consisted of all previously published ND1 sequences (20) together with 17 new sequences. The latter represented six species from the cosmopolitan genera Echinostoma, Echinoparyphium, Hypoderaeum and Isthmiophora. The second data-set of ITS sequences again included all previously published sequences (12) and three new sequences from species of Echinostoma, Echinoparyphium and Isthmiophora. All new isolates, as well as voucher material from five previously sequenced isolates, were identified on the basis of morphological characters. The phylogenetic trees inferred from the ND1 data set helped to clarify the generic affiliation of all isolates and confirmed the morphological identifications. The only exception was Echinoparyphium aconiatum, whose current position in the genus Echinoparyphium was not supported by the sequence data. Although the ITS data provided insufficient resolution for an unequivocal solution to the relationships within the genus Echinostoma, it supported the identification of Echinoparyphium ellisi and the distinct species status of three isolates of Echinostoma revolutum as predicted from the ND1 data.     

宜昌百合根尖染色体C-带分析

利用Giemsa C-带方法对宜昌百合（Lilium leucanthum(Baker) Baker）进行研究。结果表明：宜昌百合（L. leucanthum）的染色体数目为2n＝2x=24,单套染色体的条带总数目为21条。其带型公式为：2n＝24＝6C+2CI+2I+2CI⁺+2CI⁺+4I⁺+2I⁺+2T⁺+2I+S。宜昌百合（L. leucanthum）每条染色体上都显示出显著的特征带,且带纹的深浅差异明显。宜昌百合（L. leucanthum）的强带主要集中在着丝点及附近区域。通过Giemsa C-带方法可以将宜昌百合（L. leucanthum）的每条染色体区分开。     

Pelecitus helicinus Railliet & Henry, 1910 (Filarioidea,Dirofilariinae) and other nematode parasites of Brazilian birds

We report Pelecitus helicinus Railliet & Henry, 1910 from 13 species of birds of 2 orders and 7 families, collected from the states of S?o Paulo and Mato Grosso, Brazil. All 13 constitute new host records for this nematode. In addition, we report the first record of Aprocta golvani Diaz-Ungria, 1963 from Brazil and Monasa nigrifrons (Bucconidae), as well as a number of other nematode records from Neotropical birds.     

Thelazia gulosa Railliet & Henry, 1910 and T. skrjabini Erschow, 1928 infection in southern Europe (Italy)

The occurrence of Thelazia gulosa and T. skrjabini in cattle in Italy, together with an update of the prevalence of Thelazia spp. in the southern Italy, is reported. On 764 slaughtered native cattle, fifty-five (7.2%) bovines were infected by Thelazia spp: T. rhodesi was found in 44 (80%) animals, T. gulosa was found in 19 (34.5%) cattle and only one (1.8%) cattle harboured T. skrjabini. This is the first report of T. gulosa and T. skrjabini in Southern Europe.     

Haemonchus longistipes Railliet & Henry, 1909 in goats in the Sudan

Haemonchus longistipes specimens were collected from experimentally infected Sudanese goats and camels for morphological studies. The specimens from goats were much smaller than those from camels, but their infectivity to camels was not affected by their passage in goats. Goats inhabiting the same areas as camels in the Sudan were found to be naturally infected with H. longistipes, but sheep were not and were resistant to experimental infection.