A myxosporean producing actinospores of the tetractinomyxon type in Hydroides norvegicus Gunnerus (Serpulidae) in Denmark was identified as a member of the family Parvicapsulidae based on small-subunit ribosomal DNA (SSU rDNA) sequences. Myxosporean samples from various Danish and Norwegian marine fishes were examined with primers that detect the novel myxosporean. Sprattus sprattus (Linnaeus) and Clupea harengus Linnaeus (Teleostei, Clupeidae) were found to be infected. The sequences of this parvicapsulid from these hosts were consistently slightly different (0.8% divergence), but both these genotypes were found in H. norvegicus. Disporic trophozoites and minute spores of a novel myxosporean type were observed in the renal tubules of some of the hosts found infected through PCR. The spores appear most similar to those of species of Gadimyxa Køie, Karlsbakk et Nylund, 2007, but are much smaller. The actinospores of the tetractinomyxon type from H. norvegicus have been described previously. In GenBank, the SSU rDNA sequences of Parvicapsulidae gen. sp. show highest identity (82%) with Parvicapsula minibicornis Kent, Whitaker et Dawe, 1997 infecting salmonids (Oncorhynchus spp.) in fresh water in the western North America. A phylogenetic analysis places P. minibicornis and Parvicapsulidae gen. sp. in a sister clade to the other parvicapsulids (Parvicapsula spp. and Gadimyxa spp.).
In the present report we study the proteolytic activity of the excretion-secretion and crude extracts of different stages of Trichinella spiralis (Owen, 1835) Railliet, 1895, (muscle-stage larvae, adult worms before and after mating, and newborn larvae) using natural substrates (structural and hematic mammalian proteins). The analysis of the results allow us to set up a certain stage-specificity, as well as an important relationship between the protease patterns throughout the parasite life cycle and how the parasite may overcome both mechanical and humoral barriers within the host. Muscle-stage larvae present a great activity against structural proteins (collagen), while newborn larvae and adult worms degrade principally hematic proteins (hemoglobin, fibrinogen and immunoglobulin G).
Duponchelia fovealis Zeller is a polyphagous insect that has been recently reported attacking strawberry plants (Fragaria x ananassa Duchesne). Despite its economic importance there are few studies on this pest because it is difficult to rear it in the laboratory. With a constant supply of insects, studies on alternative methods of pest control can be conducted. This study aimed at developing an artificial diet for rearing D. fovealis with biological characteristics similar to those reared on their natural diet. This study was carried out in a climate-controlled room (25°C ± 2°C, RH 70% ± 10%, and 14L : 10D). The natural diet consisted of 'San Andreas' strawberry leaves (D1), while the artificial diet (D2) was developed in which beans, casein, soy protein, yeast and wheat germ are used as sources of protein. Five instars were identified. D. fovealis completed its life cycle in 38 and 40 days when fed D1 and D2, respectively. Survival was highest for the larvae fed the artificial diet. Females fed D1 lay a mean of 300.2 ± 62.3 eggs, while those fed D2, 220.3 ± 41.8 eggs. The artificial diet is suitable for the continuous rearing of D. fovealis in the laboratory., Maria A. C. Zawadneak, Rodrimar B. Gonçalves, Alex S. Poltronieri, Bráulio Santos, Adélia M. Bischoff, Aline M. Borba, Ida C. Pimentel., and Obsahuje bibliografii
Six types of sphaeractinomyxon are reported from the coelomic cavity of oligochaetes collected from the Minho River estuary in northern Portugal. Four new types are morphologically and molecularly described from freshwater species belonging to the genera Psammoryctides Hrabě and Potamothrix Vejdovský et Mrázek in the upper estuary, thus significantly increasing the number of known freshwater sphaeractinomyxon. In the lower estuary, sphaeractinomyxon types 8 and 10 of Rangel et al. (2016) are recorded infecting the marine oligochaete Tubificoides pseudogaster (Dahl). A single specimen of T. pseudogaster further displayed infection by one of the four new types found in the upper estuary, suggesting the involvement of sphaeractinomyxon in the life cycles of myxosporean species that infect migratory fish hosts. The acquisition of these second hosts is proposed to have allowed the myxosporean counterparts of sphaeractinomyxon to cross environmental barriers and conquer new habitats. Phylogenetic analyses of the SSU rRNA gene reveal the four new types clustering within the monophyletic clade of mugiliform-infecting myxobolids, strengthening the previously proposed involvement of the sphaeractinomyxon collective group in the life cycles of this specific group of myxosporeans. Endocapsa types also cluster within the latter clade, having actinospores that differ from those of sphaeractinomyxon only in the presence of valvular swellings that do not change when in contact with water. In this study, however, one type was found displaying actinospores with and without valvular swellings in the same oligochaete specimen. This overlap in actinospore morphology is given as grounds for the demise of the endocapsa collective group., Sónia Rocha, Ängela Alves, Carlos Antunes, Pedro Fernandes, Carlos Azevedo and Graça Casal., and Obsahuje bibliografii
Under seasonal conditions, Polydesmus angustus individuals born in the first part of the breeding season have a 1-year life cycle and those born later have a 2-year life cycle (cohort-splitting). In this study, 249 juveniles from four early broods (born in mid-July) and four late broods (born in September) were reared under similar laboratory conditions, to test for possible maternal influences on life-cycle duration. Development times of early- and late-born individuals were compared under four combinations of day length and temperature (16 h - 18°C, 16 h - 16°C, 12 h - 18°C and 12 h - 16°C). The results showed that development time varied significantly in response to day length, temperature and sex, but that of individuals in the early and late broods did not differ significantly (mean development times ± SE: 180 ± 6 and 183 ± 8 days, respectively). There were no significant interactions between birth period and other factors, indicating that the effects of day length, temperature and sex on development time were similar in early- and late-born individuals. This indicates that the extended life cycle of millipedes born late in the season is not maternally determined and that cohort-splitting is controlled entirely by the environmental conditions experienced by the offspring during their development. This conclusion is supported by the absence of significant variation in offspring live weight at birth measured at different times in the breeding season. The results are discussed in relation to the bet-hedging theory, which is often put forward to account for cohort-splitting in arthropods. In P. angustus, the results are consistent with either bet-hedging or adaptive plasticity, but further studies are required to decide which interpretation is correct. and Jean-François David, Jean-Jacques Geoffroy.
Lepeophtheirus simplex Ho, Gómez et Fajer-Avila, 2001 is a parasite of Sphoeroides annulatus (Jenyns), an economically important fish species, with potential for aquaculture, in northwestern Mexico. The goal of this study was to describe the developmental stages under experimental conditions and seasonal fecundity of this parasite on wild fish. There are two naupliar, one copepodid, two chalimus and two pre-adult stages preceding the adult of L. simplex. The results support previous findings, which point out that the life cycle of the caligid copepods includes only six post-naupliar stages. The generation time from egg extrusion to adult for L. simplex was approximately 10 days at 22 °C. The body length of the ovigerous females ranged between 2.2 and 4.1 mm, and its fecundity between 12 and 36 eggs per string. Fecundity was negatively correlated with the egg size and positively correlated with the egg string length. Our data did not reveal significant differences in fecundity among sampling months, but ovigerous females were significantly larger in March (when water temperature was 22 °C) than in June and July (when water temperature was 30 °C). To some extent, our fecundity results contrast with those found in species of sea lice from higher latitudes. Undoubtedly, biological information on different species of sea lice from different environmental conditions will enhance our understanding of their infection strategies and will be valuable, given the increasing interest in marine fish farming in Mexico., Francisco Neptalí Morales-Serna, Ana Inés Rivas-Salas, Samuel Gómez, Emma Josefina Fajer-Ávila., and Obsahuje bibliografii
Oocysts/sporocysts of Sarcocystis sp. were found in the intestinal contents of the smooth snake, Coronella austriaca I .aurenti. Common voles Microtus arvalis (Pallas), bank voles Clethrionomys glareolus (Schreber), green lizards Lacerta viridis (Laurcnti), and common wall lizards Podarcis muralis (Laurenti) were experimentally inoculated as potential intermediate hosts. Only common wall lizards were found to be susceptible intermediate hosts. Transparent, macroscopically hardly visible sarcocysts found in tail striated muscles of lizards were 480 (390-640) x 210 (190-230) pm in size 72 days post-infection. Using the light microscopy, the sarcocyst wall was about 1 pm thick with an apparent layer of villi approx. 2 pm thick. Ullraslruclurally, the primary cyst wall was characterised by spine-like villar protrusions up to 2.5 pm in length and 0.5 pm in diameter. Based on sarcocyst morphology and experimental data, the discovered Sarcocystis species is suggested to be conspccific with Sarcocystis lacertae Babudieri, 1932. A redescription of Sarcocystis lacertae is presented in this study.
Nereis diversicolor O.F. Müller and N. succinea Frey et Leuckart (Polychaeta, Nereidae) living in brackish shallow areas in Denmark are naturally infected with tetractinomyxon actinospores. Infected Nereis spp. were experimentally fed to various potential fish hosts, and the actinosporean stages developed into myxosporean stages of Ellipsomyxa gobii Køie, 2003 (Ceratomyxidae) in the gallbladder of the common goby Pomatoschistus microps (Krøyer) (Gobiidae). The European eel Anguilla anguilla (L.), three-spined stickleback Gasterosteus aculeatus L., small sand eel Ammodytes tobianus L., flounder Platichthys flesus (L.), European plaice Pleuronectes platessa L. and common sole Solea solea (L.) did not become experimentally infected. In Danish shallow brackish areas P. microps is naturally infected with E. gobii, in some areas with a prevalence >90%. We compared small subunit ribosomal DNA sequences of the actinosporean with E. gobii from P. microps. Sequences were identical, which further verifies that both forms belong to the same organism. This is the first myxozoan two-host life cycle in the marine environment.
Six young tortoises Testudo marginata Schoepff, 1792 were experimentally infected with Hemolivia mauritanica (Sergent et Sergent, 1904). The prepatent period ranged from 6 to 8 weeks. Young, smaller, club-like forms (6-9 × 3-6 µm) of gametocytes appeared in the peripheral blood first, whereas mature, elongated, cylindrical forms (9-12 × 5-7 µm) were detected after 1-2 weeks and predominated during later patency. Three of the infected tortoises were euthanized and dissected to study the endogenous stages. Meronts occurred in the cells of the reticulo-endothelial system and in the erythrocytes; these were observed mostly in parenchymatous organs. Mature forms measured 14.2 × 9.3 µm and contained 7-12 merozoites. Cysts with two (exceptionally one) cystozoites were also found predominantly in parenchymatous organs and measured 14.8 × 7.9 µm. Pathological changes attributable to Hemolivia were mild and limited to liver and kidneys. The role of individual developmental stages of haemogregarines is discussed with respect to evolution of heteroxenous life cycle and long-term persistence of parasites in their intermediate hosts.
The life cycle of marine Eubothrium sp. (Cestoda: Pseudophyllidea), from Atlantic salmon (Salmo salar L.) was experimentally completed in one year and included only one intermediate host (Acartia tonsa Dana) (Copepoda: Calanoida). Adult cestodes were collected from farmed salmon, and ripe eggs released by the cestodes were fed to Acartia tonsa. Ingested eggs hatched in the gut and the larvae developed in the haemocoel of the copepod for 15 days at 16°C. A total of 170 seawater-reared salmon were exposed to infected copepods and the total prevalence of Eubothrium sp. in the salmon after infection was 95.3%, with a mean intensity of 15.0 (range 1-87). The infected salmon were kept in the laboratory where the growth of the cestodes was studied for eleven months. Mean length of the cestodes increased with time, but a large variation among the cestodes was observed. Growth and maturation of the cestodes were dependent on host size and the number of worms present in the intestine. No evidence of mortality of Eubothrium sp. was observed during the experimental period.