Observations on the Spores of Pleistophora gigantea (Thélohan, 1895) Swellengrebel, 1911, a Microsporidan Parasite of the Fish Crenilabrus melops*

SYNOPSIS. After 1914 protozoologists have generally agreed that Pleistophora gigantea (Thélohan, 1895) Swellengrebel, 1911, Ichthyosporidium giganteum (Thélohan, 1895) Swarczewsky, 1914, and I. phymogenes Caullery and Mesnil, 1905, are identical. Because no polar filament was found in the spores, however, some authors have followed Swarczewsky in considering this species to be a haplosporidan, while others have persisted in thinking it a microsporidan. Using preserved material that Swellengrebel saved from a tumor on which he based his studies, we have found a polar filament in the spores both with the PAS reaction and with the electron microscpe. This new information removes the only basis for the doubt which some authors have entertained, that Thélohan and Sweliengrebel correctly considered the parasite to belong to the Microsporida. Since Pleistophora gigantea is believed to be identical with I. phymogenes, recently selected by Sprague as type species of genus Ichthyosporidium Caullery and Mesnil, 1905, then Ichthyosporidium, originally assigned to the Haplosporida, must be regarded as a microsporidan genus. Whether it is distinct from all other microsporidan genera is a matter needing further consideration.     

Antigenic characterization of Sphaerospora dicentrarchi (Myxosporea: Bivalvulida), a parasite from European sea bass Dicentrarchus labrax (Teleostei: Serranidae)

The biochemical composition of Sphaerospora dicentrarchi was studied. Periodate and Proteinase K treatments as well as lectin blots were used to analyse carbohydrate terminals. Zymography was applied to detect proteases. Four polyclonal antisera, raised against S. dicentrarchi (RaSdic), S. testicularis (RaStest), Ceratomyxa labracis (RaClab) and C. sparusaurati (RaCspr), were used in SDS polyacrylamide gel electrophoresis and immunoblot. Bands with molecular weight (MW) between 32 and 130 kDa were detected by electrophoresis. After Proteinase K treatment, apparent digestion of bands heavier than 43 kDa took place. RaSdic and RaStest detected similar bands with MW between 20 and 50 kDa, whereas RaClab and RaCspr recognized bands between 50 and 140 kDa. The 50 kDa band was recognized by all the polyclonal antisera, suggesting that it could correspond to an antigen shared by several myxosporean parasites. Four proteases were observed by zymography. From the 5 lectins assayed, binding was only observed using Con-A, which detected 2 bands of 96 and 78 kDa. Periodate treatment did not produce any effect on the binding of RaSdic and RaStest, but a high decrease of intensity in the antibody binding occurred at a concentration of 10 and 20 mM periodate when RaClab and RaCspr were tested. These results give information on the antigenic composition of S. dicentrarchi which could be useful for further diagnostic or immunoprevention studies.     

PKX,the Causative Agent of Proliferative Kidney Disease (PKD) in Pacific Salmonid Fishes and Its Affinities with the Myxozoa1

Proliferative kidney disease (PKD), caused by an unclassified protozoan (PKX), is reported from Pacific salmon, Oncorhynchus tshawytscha (Walbaum) and O. kisutch (Walbaum), and steelhead trout, Salmo gairdneri Richardson, held at the Mad River Hatchery in California, USA. The cumulative mortality attributed to the disease was 95, 13, and 18% respectively. The mortalities were greatest at mean water temperatures of 12-14°C during July 1983. The ultrastructure of the PKX organism and its associated pathology during clinical disease in all three species were consistent with those of the parasite in rainbow trout (Salmo gairdneri) as described in European outbreaks. Significant mortalities did not occur after August, at which time the parasite could no longer be detected in the salmon species. The steelhead continued to exhibit parasites in the kidney interstitium and epithelium and lumens of the tubules. Myxosporidan trophozoites and developing spores were also observed in the lumens of the kidney tubules of these fish. Although a mixed infection with another parasite may have occurred, evidence suggests that the myxosporidans are later stages of PKX. They were only observed in fish exposed to water with the infective stage and were particularly prominent in recovering fish. The PKX organism is similar to UBO, an unclassified protozoan of carp suspected to be an early stage of Sphaerospora renicola Dyková & Lom. Both parasites infect the blood and kidney, divide by endogeny, and are released by disintegration of the primary mother cell. The intraluminal myxosporean forms show similarities to Sphaerospora spp. in that they are monosporous and sporoblasts are formed within pseudoplasmodia. It is possible that PKX migrates to the lumen of the kidney tubule and subsequently sporulates. If the myxosporean forms are later stages of PKX, then it would belong to the phlyum Myxozoa.     

Light and Electron Microscopic Description of Sphaerospora dicentrarchi N. Sp. (Myxosporea: Sphaerosporidae) from Wild and Cultured Sea Bass, Dicentrarchus labrax L.

ABSTRACT. A new myxosporean, Sphaerospora dicentrarchi n. sp., was found in numerous organs of wild and cultured sea bass ( Dicentrarchus labrax L.). It is distinguished from all previously reported Sphaerospora spp. by the shape and small size of the spores, location in the host and its geographical distribution. Prevalence of infection was 100% and 83.5% in wild and cultured fish, respectively. Outstanding ultrastructural features are the presence of a binucleate sporoplasm, valvogenic spheroidal structures and capsulogenic lipid inclusions. Other data concerning ultrastructure and sporogenesis are presented.     

Immunohistochemical reactivity of polyclonal antibodies against Sphaerospora testicularis and Ceratomyxa labracis (Myxosporea: Bivalvulida), with other myxosporean parasites.

Immunological staining with rabbit antibodies raised against Sphaerospora testicularis and Ceratomyxa labracis was used to characterise their specificity and their reactivity towards other fish parasites. Polar capsules and valves of S. testicularis and C. labracis were labelled with their homologous antibody and cross reaction was observed with all the myxosporean parasites assayed from marine and freshwater fish hosts. All polar capsules were stained with both antibodies, except those of Zschokkella mugilis, which were not labelled with anti-S. testicularis serum. These observations suggest that polar capsules may be very conserved structures in myxosporean parasites from different hosts.     

Zschokkella mugilis N. Sp. (Myxosporea: Bivalvulida) from Mullets (Teleostei: Mugilidae) of Mediterranean Waters: Light and Electron Microscopic Description

A new Myxosporea, Zschokkella mugilis n. sp., was found in the gall bladder of several mugilids. It is distinguished from all previously reported Zschokkella from mugilids by the absence of valve ornamentation and from other species by the size of the spores. Prevalence of infection was 62.5% for Mugil capito, 70% for M. cephalus and 64.3% for Liza saliens. Plasmodia with rhizoids attached to epithelial cells appeared to compromise the host as evidenced in light and transmission electron micrographs presented herein. General ultrastructure and disporous sporogenesis of Z. mugilis resembled other Myxosporeans, but sporogonic cells did not seem to be formed in pansporoblasts.     

New species of Myxosporidia (Myxosporea: Cnidosporidia) from cottids (Abyssocottidae) and the oilfishes (Comephorus spp.) of Baikal Lake

Two new species of Myxosporidia, Myxidium baicalensis sp. n., Myxidium donecae sp. n. are described from the gall bladder of fishes from Baikal. Myxidium baicalensis sp. n. parasitising gobies Cyphocottus megalops, Asprocottus platycephalus, and other host species, while Myxidium donecae sp. n. parasitising Baikal oil fishes Comephorus baicalensis and C. dybowski.     

Unicapsula seriolae n. sp. (Myxosporea,Multivalvulida) from Australian Yellowtail Kingfish Seriola lalandi1

Unicapsula seriolae n. sp. forms long plasmodia within the striated muscle fibers of Seriola lalandi off eastern Australia. Its spores are composed of three valves, only one of which contains a developed polar capsule. Within the capsule, the filament makes 2 1/2–3 turns, and this criterion can be used to separate U. seriolae from the two other members of the genus. The flesh of infected fish disintegrates during slow cooking.     

Ceratomyxa spp. (Protozoa: Myxosporea) infections in wild and cultured sea bass, Dicentrarchus labrax, from the Spanish Mediterranean area

Ceratomyxa labracis and Ceratomyxa diplodae , parasitic in the gall bladder of wild and cultured Mediterranean sea bass ( Dicentrarchus labrax L.) were studied. Prevalences were clearly higher in cultured fish, especially for C. labracis . Starvation seems to favour the appearance of ceratomyxosis. Infection varied seasonally, with maxima in winter and minima in summer, a pattern almost contrary to temperature. Prevalence of C. labracis decreased in older fish. No clear influence of host sex was observed, and the apparent negative association between the two Ceratomyxa spp. was not confirmed statistically. Different degrees of histopathological damage of the gall bladder were observed by light and electron microscopy, mainly consisting of vacuolation, deformation or even necrosis of epithelial cells, and thickening and inflammation of the subepithelial connective tissue. Trophozoites appeared frequently lining the epithelium, closely attached to the cell surface or even forming invaginations in it. The importance of ceratomyxosis for sea bass and the influence of culture and stress conditions are discussed.     

A new species of Myxidium (Cnidaria: Myxosporea: Myxidiidae) from the gallbladder of pickerels,Esox spp. (Esociformes: Esocidae), from southwestern Arkansas,USA

Systematic Parasitology - During April 2016 and again in November 2021, four Chain Pickerels, Esox niger were collected from Union (n = 3) and Nevada (n = 1) counties, Arkansas, USA, and 65 Grass...     

Comparative Morphology of Atalodera spp. and Thecavermiculatus spp. (Heteroderidae) with Scanning Electron Microscopy

SEM examination of second-stage juveniles (J2) and adults of Atalodera ucri, A. lonicerae (syn. Sherodera lonicerae), Thecavermiculatus sp. (undescribed new species), T. andinus, and T. crassicrustatus revealed new characters. A primitive en face pattern with six separate lips occurs in J2 of Thecavermiculatus spp. examined and in about half the polymorphic A. lonicerae. A derived en face pattern with fused adjacent submedial lips occurs in the other half of A. lonicerae and all A. ucri. Posteriorly, the J2 head of all species is annulated. The primitive en face pattern also occurs in males of A. lonicerae and Thecavermiculatus spp., and posteriorly the head of these species consists of plates. Fewer plates occur rarely in males of A. ucri. Males of A. ucri have a derived en face pattern where lips are fused and the head is annulated. Fusion of lips occurs rarely in males of A. lonicerae. Females of all species have similar derived en face patterns. En face patterns of J2 and males o f Atalodera and Thecavermiculatus may aid in species identification and to elucidate intergeneric relationships, but en face characters shared by the two genera are primitive and are not useful for demonstrating monophyly. Perineal region of females indicates the closeness of the vulval-anal distance, as a derived character, which is shared by Atalodera and most Thecavermiculatus spp. suggesting possible monophyly. T. andinus, while having a similar en face pattern to J2 of other Thecavermiculatus species, lacks the derived character of the perineal region. Phasmid openings were not observed in adults of any of the species examined.     

LCA of Danish Fish Products. New methods and insights (9 pp)

Goal, Scope and Background This article presents the main results from a PhD dissertation about environmental impacts from Danish fish products. The focus is on LCA results for flatfish, but the article also gives an overview of screenings of other fish species. Furthermore, it includes an analysis of the energy consumption in the fishing stage – as a function of fish species and fishing methods. Alternative impact categories that have not been included in the quantitative LCA and policy perspectives are elaborated in the discussion part of the paper. Methods The study represents a consequential LCA approach (opposed to attributional) and the functional unit is one kg consumed flatfish filet in units of 300 gram (cardboard boxes). Data are obtained from statistics, interviews, literature, and databases – mainly ETH-ESU 96 and the Danish LCA food database. The EDIP 97 method has been applied for life cycle impact assessment (LCIA) and the results have been verified by Ecoindicator 99. Results The results of the flatfish LCA show that the fishing stage has the largest impact potential for the investigated impact categories. This is mainly due to a relatively high fuel consumption and significant emissions of biocides from anti-fouling agents (contributing to ecological toxicity). But large reductions in fuel intensity (fuel consumption per kg caught fish) can be obtained by changing the type of fishing gear – particularly in flatfish fisheries. The consumption and retail stages represent significant impact potentials as well, while processing is insignificant. LCA screenings of other fish species show the same picture, but there are cases (herring, mackerel and mussels) where the fishing stage is less important, while the opposite is the case for processing – mainly due to energy intensive packaging materials. Discussion A limited number of impact categories have been investigated, but a 'qualitative' LCA, focusing on other fishery specific impacts, emphasises that the fishing stage is indeed the overall most important. In this regard, it is argued that fuel requirements in many cases are proportional to environmental impacts related to 'discard' and 'seafloor damage'. Hence, it is worth focusing on energy for many reasons. In a policy context, it is a paradox that mainly the fish processing industry has been subjected to environmental regulations. Recommendation and Perspective Future scenarios indicate that energy consumption will remain one of the most important environmental aspects in the fishing stage – partly due to regulations of anti-fouling biocides (e.g. TBT) and partly because of the continued depletion of fish stocks. From an environmental policy perspective, it is therefore recommended to broaden the perspective of existing fishery regulations and increase the focus on fishing gear and energy in the primary production (fishing stage).     

Albuminuria as a Risk Factor for Anemia in Chronic Kidney Disease: Result from the KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease (KNOW-CKD)

Background

Anemia is a common complication among patients with chronic kidney disease (CKD), and it is associated with unfavorable clinical outcomes in patients with CKD independent of the estimated glomerular filtration rate (eGFR). We assessed the association of the urinary albumin-to-creatinine ratio (ACR) and eGFR with anemia in CKD patients.

Methods

We conducted a cross-sectional study using baseline data from the KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease (KNOW-CKD). Multiple regression analysis was performed to identify the independent association of albuminuria with anemia. Furthermore, odds ratios for anemia were calculated by cross-categorization of ACR and eGFR.

Results

Among 1,456 patients, the mean age was 53.5 ± 12.4 years, and the mean eGFR and ACR were 51.9 ± 30.5 mL/min per 1.73 m² and 853.2 ± 1,330.3 mg/g, respectively. Anemia was present in 644 patients (40.5%). Multivariate analysis showed that the odds ratio of anemia increased according to ACR levels, after adjusting for age, sex, eGFR, body mass index, pulse pressure, cause of CKD, use of erythropoiesis stimulating agents, serum calcium and ferritin (ACR < 30 mg/g as a reference group; 30–299 mg/g, adjusted odds ratio (OR) = 1.43, 95% confidence interval (CI) = 0.88–2.33; ≥300 mg/g, adjusted OR = 1.86, 95% CI = 1.12–3.10). In addition, graded associations were observed in cross-categorized groups of a higher ACR and eGFR compared to the reference group with an ACR <30 mg/g and eGFR ≥60 mL/min per 1.73 m².

Conclusion

The present study demonstrated that albuminuria was a significant risk factor for anemia in CKD patients independent of the eGFR.     

Expressed Sequence Tag Analysis of Kidney and Gill Tissues from Rainbow Trout (Oncorhynchus mykiss) Infected with Infectious Hematopoietic Necrosis Virus

Expressed sequence tags (ESTs) were obtained from the kidney and gill tissues of rainbow trout, Oncorhynchus mykiss, infected with infectious hematopoietic necrosis virus (IHNV). The results of single-pass sequencing of ESTs from 198 clones (AU081027–AU081192) from kidney complementary DNA and 45 clones (AU081193–AU081236) from gill cDNA are reported herein. Sequences of the cDNA clones were compared with sequences in the GenBank database. Fourteen clones (20%) appeared to be completely unknown and may represent newly described genes, whereas 158 clones (80%) were identified on the basis of matches to sequences in the database. Three of the unidentified sequences were isolated from both the kidney and the gill cDNA libraries. However, no sequences were identical between kidney and gill clones. Received December 7, 1999; accepted April 28, 2000.     

Naturally Occurring Mutations Alter the Stability of Polycystin-1 Polycystic Kidney Disease (PKD) Domains

Mutations in polycystin-1 (PC1) can cause autosomal dominant polycystic kidney disease, which is a leading cause of renal failure. The available evidence suggests that PC1 acts as a mechanosensor, receiving signals from the primary cilia, neighboring cells, and extracellular matrix. PC1 is a large membrane protein that has a long N-terminal extracellular region (about 3000 amino acids) with a multimodular structure including 16 Ig-like polycystic kidney disease (PKD) domains, which are targeted by many naturally occurring missense mutations. Nothing is known about the effects of these mutations on the biophysical properties of PKD domains. Here we investigate the effects of several naturally occurring mutations on the mechanical stability of the first PKD domain of human PC1 (HuPKDd1). We found that several missense mutations alter the mechanical unfolding pathways of HuPKDd1, resulting in distinct mechanical phenotypes. Moreover, we found that these mutations also alter the thermodynamic stability of a structurally homologous archaeal PKD domain. Based on these findings, we hypothesize that missense mutations may cause autosomal dominant polycystic kidney disease by altering the stability of the PC1 ectodomain, thereby perturbing its ability to sense mechanical signals.     

Functional Interaction between Angiotensin II Receptor Type 1 and Chemokine (C-C Motif) Receptor 2 with Implications for Chronic Kidney Disease

Understanding functional interactions between G protein-coupled receptors is of great physiological and pathophysiological importance. Heteromerization provides one important potential mechanism for such interaction between different signalling pathways via macromolecular complex formation. Previous studies suggested a functional interplay between angiotensin II receptor type 1 (AT₁) and Chemokine (C-C motif) Receptor 2 (CCR2). However the molecular mechanisms are not understood. We investigated AT₁-CCR2 functional interaction in vitro using bioluminescence resonance energy transfer in HEK293 cells and in vivo using subtotal-nephrectomized rats as a well-established model for chronic kidney disease. Our data revealed functional heteromers of these receptors resulting in CCR2-Gαi1 coupling being sensitive to AT₁ activation, as well as apparent enhanced β-arrestin2 recruitment with agonist co-stimulation that is synergistically reversed by combined antagonist treatment. Moreover, we present in vivo findings where combined treatment with AT₁- and CCR2-selective inhibitors was synergistically beneficial in terms of decreasing proteinuria, reducing podocyte loss and preventing renal injury independent of blood pressure in the subtotal-nephrectomized rat model. Our findings further support a role for G protein-coupled receptor functional heteromerization in pathophysiology and provide insights into previous observations indicating the importance of AT₁-CCR2 functional interaction in inflammation, renal and hypertensive disorders.     

Myxidium lesminteri n. sp. (Myxosporea: Myxidiidae) from the gall-bladder of three southern African Anura

During 1988 and 1989 409 specimens, representing 50 species in 9 families of southern African Anura from 26 localities throughout the Republic of South Africa and from Swaziland, were examined for gallbladder myxozoans. Myxidium lesminteri n. sp. was the only myxozoan found and was observed in one tomopterna krugerensis (Ranidae), one Bufo garmani (Bufonidae) and one Heleophryne natalensis (Heleophrynidae), all from Transvaal. The spore of Myxidium lesminteri (9.5–15.0 × 5.0–8.0 m) is characterised by a smooth shell devoid of striations but has one longitudinal ridge.     

Host-Parasite Relationships of Atalodera spp. (Heteroderidae)

Atalodera ucri, Wouts and Sher, 1971, and A. lonicerae, (Wouts, 1973) Luc et al., 1978, induce similar multinucleate syncytia in roots of golden bush and honeysuckle, respectively. The syncytium is initiated in the cortex; as it expands, it includes several partially delimited syncytial units and distorts vascular tissue. Outer walls of the syncytium are relatively smooth and thickest near the feeding site of the nematode; inner walls are interrupted by perforations which enlarge as syncytial units increase in size. The cytoplasm of the syncytium is granular and includes numerous plastids, mitochondria, vacuoles, Golgi, and a complex network of membranes. Nuclei are greatly enlarged and amoeboid in shape. Although more than one nucleus sometimes occur in a given syncytial unit, no mitotic activity was observed. Syncytia induced by species of Atalodera chiefly differ from those of Heterodera sensu lato by the absence of cell wall ingrowths; wall ingrowths increase solute transport and characterize transfer cells. In syncytia of Atalodera spp., a high incidence of pits and pit fields in walls adjacent to vasctdar elements suggests that in this case plasmodesmata provide the pathway for increased entry of sohttes. The formation of a syncytium by species of Atalodera and Heterodera sensu lato, but a single uninucleate giant cell by Sarisodera and Hylonema, indicates a pattern of host responses that may be useful, with other characters, for phylogenetic inference for Heteroderidae.