Ageing in a variable habitat: environmental stress affects senescence in parasite resistance in St Kilda Soay sheep

Despite widespread empirical evidence for a general deterioration in the majority of traits with advancing age, it is unclear whether the progress of senescence is chronologically determined, or whether factors such as environmental conditions experienced over the lifespan are more important. We explored the relative importance of ‘chronological’ and ‘environmental’ measures of age to changes in parasite resistance across the lifespan of free-living Soay sheep. Our results show that individuals experience an increase in parasite burden, as indicated by gastrointestinal helminth faecal egg count (FEC) with chronological age. However, chronological age fails to fully explain changes in FEC because a measure of environmental age, cumulative environmental stress, predicts an additional increase in FEC once chronological age has been accounted for. Additionally, we show that in females age-specific changes are dependent upon the environmental conditions experienced across individuals'' life histories: increases in FEC with age were greatest among individuals that had experienced the highest degree of stress. Our results illustrate that chronological age alone may not always correspond to biological age, particularly in variable environments. In these circumstances, measures of age that capture the cumulative stresses experienced by an individual may be useful for understanding the process of senescence.     

Bluetongue epidemiology in the Caribbean region: serological and entomological evidence from a pilot study in Barbados

Variation in the percentage of lambs seroconverting to bluetongue viruses was seen between sites and years in Barbados. Transmission at some sites was nearly absent whereas all lambs at one site became seropositive. The agar gel immunodiffusion test for bluetongue gave consistent results in series of serum samples from 112 of 121 sentinel lambs. Collections of biting midges in association with sheep yielded six species: Culicoides insignis Lutz, C. pusillus Lutz, C. phlebotomus (Williston), C. furens (Poey), C. jamaicensis Edwards and C. trilineatus Fox. The first two species comprised 92% of those caught during a sentinel lamb study and were the predominant species trapped for virus isolation. No viruses were recovered from 5517 C. insignis, 614 C. pusillus, three C. trilineatus and two C. furens placed into pools during two brief intensive trapping operations.     

How fish-helminth associations arise: an example from Arctic charr in Loch Rannoch

Three sympatric morphs of Arctic charr Salvelinus alpinus occur in Loch Rannoch, Scotland, and are identified by their differing head morphology and diet. These are small-headed benthic, large-headed benthic and pelagic morphs. Six species of endoparasitic helminth were found in the fish, but the morphs had different patterns of infection. Overall infections in pelagic charr were heavier than in large-headed benthics, which were in turn heavier than in small-headed benthics, even though benthic charr live longer than pelagics. Pelagic fish had high prevalences and intensities of pseudophyllidean tapeworms, the intermediate hosts of which are copepods. The prevalence and intensity of metacercariae of Diplostomum sp. (the intermediate hosts of which are snails) were high in the benthic morphs. The results are discussed in terms of the effects of ecological factors on transmission of helminth parasites to their hosts and the evolution of host-parasite associations.     

Synthesis of complex-type glycans derived from parasitic helminths

Chemical syntheses of complex-type glycans derived from the eggs of parasitic helminths, Schistosoma mansoni and Schistosoma japonicum were achieved. In addition, their analogs, which lack xylose and/or fucose residue(s), are described. These branched sugar chains were synthesized regio- and stereoselectively by using beta-mannosylation, desilylation under high-pressure and glycosylation in frozen solvent as key transformations.     

Anthelmintic treatment alters the parasite community in a wild mouse host

Individuals are often co-infected with several parasite species, yet the consequences of drug treatment on the dynamics of parasite communities in wild populations have rarely been measured. Here, we experimentally reduced nematode infection in a wild mouse population and measured the effects on other non-target parasites. A single oral dose of the anthelmintic, ivermectin, significantly reduced nematode infection, but resulted in a reciprocal increase in other gastrointestinal parasites, specifically coccidial protozoans and cestodes. These results highlight the possibility that drug therapy may have unintended consequences for non-target parasites and that host–parasite dynamics cannot always be fully understood in the framework of single host–parasite interactions.     

Etude hydrobiologique des lagunes du nord de la Tunisie

The limnology of three lakes in Tunisia was studied over a period of two years. These lakes differed substantially in the degree of salinity and resistivity. Physical and chemical parameters occurring in the lakes were analysed for a year. The investigation indicated some discussion about the following factors: Temperature, chlorides, potassium, sodium, calcium, carbonates, bicarbonates, dissolved oxygen, nitrats...In an another paper (second part), the author will study the interrelationships between annual variations of algal populations (plankton) and annual variations of these physical and chemical factors.

     

Population structure of Tunisian Leishmania infantum and evidence for the existence of hybrids and gene flow between genetically different populations

Twenty-seven strains of Leishmania infantum from north and central Tunisia belonging to the three main MON zymodemes (the MON-typing system is based on multilocus enzyme electrophoresis (MLEE) of 15 enzymes) found in this country (MON-1, MON-24 and MON-80) and representing different pathologies (visceral, cutaneous and canine leishmaniasis) have been studied to understand the genetic polymorphism within this species. Intraspecific variation could be detected in L. infantum by the use of 14 hypervariable microsatellite markers. In addition to microsatellite repeat length variation, a high degree of allelic heterozygosity has been observed among the strains investigated, suggestive of sexual recombination within L. infantum groups. The two major clusters found by using Bayesian statistics as well as distance analysis are consistent with the classification based on isoenzymes, dividing Tunisian L. infantum into MON-1 and MON-24/MON-80. Moreover, the existence of hybrid strains between the MON-1 and the non-MON-1 populations has been shown and verified by analysis of clones of one of these strains. Substructure analysis discriminated four groups of L. infantum. The major MON-1 cluster split into two groups, one comprising only Tunisian strains and the second both Tunisian and European strains. The major MON-24 cluster was subdivided into two groups with geographical and clinical feature correlations: a dermotropic group of strains mainly from the north, and a viscerotropic group of strains from the centre of Tunisia. The four viscerotropic hybrid strains all originated from central Tunisia and were typed by MLEE as MON-24 or MON-80. To our knowledge, this is the first report describing relationships between clinical picture and population substructure of L. infantum MON-24 based on genotype data, as well as the existence of hybrids between zymodemes MON-1 and MON-24/MON-80, and proving one of these hybrid strains by molecular analysis of the parent strain and its clones.     

The intestinal parasite infection status of inhabitants in the Roxas city,The Philippines

We carried out a small-scale survey to investigate the status of intestinal protozoa and helminthes infection of inhabitants in Roxas city, Mindoro, the Philippines. Total 301 stool samples were subjected to the formalin-ether concentration method for the detection of helminth ova and protozoan cysts. The overall positive rate was 64.5%, and that of male and female were 56.6% and 72.5%, respectively. The highest infected helminth was Ascaris lumbricoudes (51.2%), followed by Trichuris trichiura (27.6%), hookworm (8.0%) and Enterobius vermicularis (0.3%). The protozoa infection status revealed that Entamoeba coli was the most frequent (15.0%). Iodoamoeba buetschlii and E. histolytica were found but few. The multiple infection more than two parasites was 29.6%, and double infection with A. lumbricoides and T. trichiura was most common. The intestinal helminth infections were highly prevalent in this area, according to this result, and we concluded that anthelminthic drugs should be given to inhabitants, especially to children of 1 to 15 years-old.     

Inventaire des algues et phanérogames marines benthiques de la Tunisie

Abstract

Check list of the benthic marine flora of Tunisia. — 393 species, varieties, formae and stadii of algae and seagrasses are listed: 6 Bangiophyceae, 239 Florideophyceae, 1 Xanthophyceae, 82 Phaeophyceae, 20 Chlorophyceae, 45 Bryopsidophyceae and 5 seagrasses.     

Identification of first-stage dorsal-spined lungworm larvae of Tunisian barbary red deer: First report of Varestrongylus sagittatus and Elaphostrongylus cervi in Africa

Barbary red deer (Cervus elaphus barbarus) is a protected rare subspecies of red deer. The study of its Protostrongylidae fauna based only on sporadic necropsy of naturally dead animals is difficult. Therefore diagnosis of lungworms rely mainly on the identification of the first stage larvae (L1). The L1 of the different species are not readily diagnosed on morphological basis since much variation is recorded within and among dorsal-spined larvae belonging to various species. The aim of this study was to identify the dorsal-spined lungworm larvae of the Barbary red deer. A discriminant function was established, using the measurements of L1 lungworms recorded from red deer in the literature, then applied to identify 220 dorsal-spined larvae extracted from 25 Tunisian Barbary red deer fresh fecal samples. Also the ITS2 region of rDNA of four pools of larvae (n?=?25–60) were amplified, sequenced and analyzed. Using discriminant analysis of morphological traits, Elaphostrongylus cervi and Varestongylus sagittatus were identified. Molecular identification confirmed the presence of E. cervi which is the most prevalent species. This study represents the first identification of V. sagittatus and E. cervi in North Africa.