| ultrastructural characterisation and molecular taxonomic identification of nosema granulosis n. sp., a transovarially transmitted feminising (ttf) microsporidium. | a novel microsporidian parasite is described, which infects the crustacean host gammarus duebeni. the parasite was transovarially transmitted and feminised host offspring. the life cycle was monomorphic with three stages. meronts were found in host embryos, juveniles, and in the gonadal tissue of adults. sporoblasts and spores were restricted to the gonad. sporogony was disporoblastic giving rise to paired sporoblasts, which then differentiated to form spores. spores were not found in regular gr ... | 1999 | 10519217 |
| incomplete feminisation by the microsporidian sex ratio distorter, nosema granulosis, and reduced transmission and feminisation efficiency at low temperatures. | we investigated the effects of temperature on transovarial transmission and feminisation by nosema granulosis, a microsporidian sex ratio distorter of the brackish water amphipod gammarus duebeni. there was no difference in parasite transmission efficiency to the f(1) eggs of infected females maintained under two temperature conditions, 5 and 10 degrees c (89 and 86%, respectively). when f(1) individuals were screened as adults, the proportion infected was also similar at both temperatures (74 a ... | 2002 | 12062553 |
| infection of gammarus duebeni populations by two vertically transmitted microsporidia; parasite detection and discrimination by pcr-rflp. | we screened a population of the brackish water crustacean gammarus duebeni from the isle of cumbrae for the presence of vertically transmitted microsporidia. we compared 2 screening techniques; light microscopy and pcr-based detection using generic 16s rdna microsporidian primers. fifty percent of females from this population tested positive for vertically transmitted microsporidia. the pcr screen was 100% efficient in comparison with existing lm based screening. in addition, the pcr screen prod ... | 2002 | 12166521 |
| the impact of a vertically transmitted microsporidian, nosema granulosis on the fitness of its gammarus duebeni host under stressful environmental conditions. | although purely vertically transmitted parasites are predicted to cause low pathogenicity in their hosts, the effects of such parasites on host fitness under stressful environmental conditions have not previously been assessed. here, we investigate the effects of nosema granulosis, a vertically transmitted, microsporidian parasite of the brackish water amphipod gammarus duebeni, on host growth and survival under conditions of host-host competition and limited food. the parasite had no effect on ... | 2003 | 12636349 |
| two species of feminizing microsporidian parasite coexist in populations of gammarus duebeni. | the amphipod crustacean gammarus duebeni hosts two species of vertically transmitted microsporidian parasites, nosema granulosis and microsporidium sp. a. here it is demonstrated that these co-occurring parasite species both cause infected females to produce female-biased broods. a survey of european g. duebeni populations demonstrates that these two parasites co-occur in six of 10 populations. these findings contrast with the theoretical prediction that two vertically transmitted feminizing par ... | 2003 | 14635846 |
| association with host mitochondrial haplotypes suggests that feminizing microsporidia lack horizontal transmission. | the amphipod crustacean gammarus duebeni hosts two feminizing microsporidian parasites, nosema granulosis and microsporidium sp. samples of g. duebeni were collected from three sites on the scottish island of great cumbrae and screened for microsporidia using polymerase chain reaction. associations between the prevalence of the two feminizing parasites and haplotypes of the host mitochondrial gene cytochrome oxidase i (coi) were investigated. the prevalence of both parasites varied significantly ... | 2003 | 14640399 |
| mechanisms of parasite-induced sex reversal in gammarus duebeni. | the amphipod gammarus duebeni is host to the feminising microsporidian parasite nosema granulosis that converts males into functional females. to test the hypothesis that the parasite acts through endocrine disruption we compared the morphology of the gonad and activity of the androgenic gland, which coordinates male sexual differentiation, in infected and uninfected animals. male gonad consisted of testis, seminal vesicle and vas deferens that was anchored to the genital papilla on segment 7. t ... | 2004 | 15111096 |
| local adaptation and enhanced virulence of nosema granulosis artificially introduced into novel populations of its crustacean host, gammarus duebeni. | local adaptation theory predicts that, on average, most parasite species should be locally adapted to their hosts (more suited to hosts from local than distant populations). local adaptation has been studied for many horizontally transmitted parasites, however, vertically transmitted parasites have received little attention. here we present the first study of local adaptation in an animal/parasite system where the parasite is vertically transmitted. we investigate local adaptation and patterns o ... | 2005 | 15722078 |
| transmission and burden and the impact of temperature on two species of vertically transmitted microsporidia. | microsporidia are unusual amongst eukaryotic parasites in that they utilize both vertical and horizontal transmission and vertically transmitted species can cause sex ratio distortion in their host. here we study vertical transmission in two species of feminising microsporidia, nosema granulosis and dictyocoela duebenum, infecting a single population of the crustacean host gammarus duebeni and measure the effect of temperature on parasite transmission and replication. n. granulosis was verticall ... | 2006 | 16442539 |
| targeting of host cell lineages by vertically transmitted, feminising microsporidia. | feminising microsporidian parasites are transmitted vertically from generation to generation of their crustacean hosts. little is known about the mechanisms underpinning vertical transmission, in particular, parasite transmission to the host gonad during host development. here, we investigate the burden and distribution of two species of vertically transmitted, feminising microsporidia (dictyocoela duebenum and nosema granulosis) during early embryogenesis (zygote to eight-cells) of the gammarus ... | 2006 | 16696983 |
| strategic sperm allocation under parasitic sex-ratio distortion. | parasitic sex-ratio distorters are a major selective force in the evolution of host mating behaviour and mate choice. here, we investigate sperm limitation in the amphipod gammarus duebeni and the impact of the microsporidian sex-ratio distorter nosema granulosis on sperm allocation strategies. we show that males become sperm limited after three consecutive matings and provide uninfected, high fecundity, females with more sperm than infected females. we show that sperm limitation leads to a decr ... | 2006 | 17148331 |
| infection by a vertically-transmitted microsporidian parasite is associated with a female-biased sex ratio and survival advantage in the amphipod gammarus roeseli. | summaryvertically transmitted parasites may have positive, neutral or negative effects on host fitness, and are also predicted to exhibit sex-specific virulence to increase the proportion or fitness of the transmitting sex. we investigated these predictions in a study on the survival and sex ratio of offspring of the amphipod gammarus roeseli from females infected by the vertically transmitted microsporidia nosema granulosis. we found, to our knowledge, the first evidence for a positive relation ... | 2007 | 17445328 |
| molecular characterisation of the microsporidia of the amphipod gammarus duebeni across its natural range revealed hidden diversity, wide-ranging prevalence and potential for co-evolution. | microsporidia comprise an unusual group of intracellular, eukaryotic parasites that exhibit ubiquitous distribution throughout the animal kingdom. we analysed the small subunit ribosomal gene (ssurdna) using pcr and sequencing and screened 894 gammarus duebeni (crustacea, amphipoda) specimens from 35 european marine and freshwater populations. we discovered considerable hidden microsporidian diversity. blast searches, sequence analysis and phylogenetic analysis revealed intraspecific sequence va ... | 2010 | 20601176 |
| paramyxean-microsporidian co-infection in amphipods: is the consensus that microsporidia can feminise their hosts presumptive? | the current consensus is that microsporidia belong to a select group of parasites capable of causing both intersexuality and complete sex reversal in their hosts. indeed, species such as nosema granulosis and dictyocoela duebenum, which infect amphipod crustaceans, are regularly referred to as 'feminising microsporidians'. this categorisation is based on a combination of findings: that these species are vertically transmitted and occur at a high prevalence of infection in intersex and female amp ... | 2012 | 22609329 |
| microsporidian parasites feminise hosts without paramyxean co-infection: support for convergent evolution of parasitic feminisation. | feminisation of amphipod crustaceans is associated with the presence of at least three microsporidian parasites and one paramyxean parasite, suggesting that the ability to feminise has evolved multiple times in parasites of amphipods. co-infection by a paramyxean with one of the putative microsporidian feminisers, dictyocoela duebenum, has inspired the alternative hypothesis that all feminisation of amphipods is caused by paramyxea and that all microsporidian associations with feminisation are d ... | 2015 | 25747725 |
| ultrastructure and molecular characterization of the microsporidium, nosema chrysoperlae sp. nov., from the green lacewing, chrysoperla carnea (stephens) (neuroptera: chrysopidae) used for biological pest control. | lacewing larvae are generalist predators that are commercially available for aphid control on a variety of crops in both europe and north america. although lacewings are known for their symbiotic association with yeasts and bacteria, there are few reports of microsporidia in these natural enemies. an undescribed microsporidium was found in chrysoperla carnea (stephens) during the routine examination of specimens that were obtained from a commercial insectary for biological pest control. the obje ... | 2013 | 23727346 |
| (cryptic) sex in the microsporidian nosema granulosis--evidence from parasite rdna and host mitochondrial dna. | microsporidia are single-celled, intracellular eukaryotes that parasitise a wide range of animals. the nosema/vairimorpha group includes some putative asexual species, and asexuality is proposed to have originated multiple times from sexual ancestors. here, we studied the variation in the ribosomal dna (rdna) of 14 isolates of the presumed apomictic and vertically transmitted nosema granulosis to evaluate its sexual status. the analysed dna fragment contained a part of the small-subunit ribosoma ... | 2014 | 24269340 |
| effects of feminizing microsporidia on the masculinizing function of the androgenic gland in gammarus duebeni. | feminizing parasites enhance their vertical transmission to the host offspring by converting genetic male hosts into phenotypic females. crustacea are the only invertebrates where sexual differentiation is controlled by a specialised endocrine organ, the androgenic gland, rather than by the gonads. we showed that a feminizing microsporidian microsporidium sp. inhibits androgenic gland differentiation. we investigated the effect of microsporidium sp. and a second feminizing microsporidium, nosema ... | 2013 | 23207223 |