Prey-mimetism in cercariae of Apatemon (Digenea, Strigeidae) in freshwater in northern latitudes

Cercariae, the free-living larval stages of trematodes, have adopted an amazing variety of transmission strategies. One of them is prey-mimetism, i.e. cercariae mimicking prey to attract motile hosts to be eaten. In a period between 2002 and 2019, we examined small planorbid snails, Bathyomphalus contortus, Gyraulus parvus and Planorbis planorbis from lakes in Finland and Iceland and from the Curonian Lagoon in Lithuania. Cercariae with conspicuously enlarged tails and unusual swimming behaviour, likely mimicking invertebrate prey, were detected and studied by the use of morphological and molecular (cox1, ITS1-5.8S-ITS2 and 28S rDNA) methods. Cercariae of two species belonging to the genus Apatemon (Strigeidae) were recognised. We consider Apatemon sp. 5 ex P. planorbis from the Curonian Lagoon identical to Cercaria globocaudata U. Szidat, 1940. Cercariae ex G. parvus from Iceland and ex B. contortus from Finland were conspecific, and we named them Apatemon sp. 6; these cercariae could not be associated with any known species. For the first time, we verified that cercariae of the Bulbocauda group belong to the genus Apatemon. We provide a mini-review on records of furcocercariae of the family Strigeidae with enlarged tails reported in freshwaters of the northern hemisphere and reveal that it is not only Apatemon but also Australapatemon and most likely Strigea which belong to the Bulbocauda group, rendering it a purely ecological assemblage. Understanding which invertebrate swimming behaviour these cercariae are mimicking will enhance our knowledge of the processes behind trematode transmission and will help to assess evolutionary pathways of host-finding strategies in trematodes.

Hemiurid Trematodes (Digenea: Hemiuridae) from Marine Fishes off the Coast of Rio de Janeiro, Brazil, with Novel Molecular Data

Brazil is a tropical country with remarkably diverse marine habitats that harbour a rich diversity of fish. Only a small portion of this fish diversity has been investigated for parasites, and thus the diversity of their trematode parasites remains unexplored. Moreover, only 5 out of 184 known digenean trematode species of marine fish in Brazil have been genetically characterised. The Hemiuridae Looss, 1899 is the second most speciose trematode family in marine fishes from Brazil but, in many ways, it remains a neglected group. Forty-three trematode specimens from nine fish species were collected from the coastal zone off Rio de Janeiro, Brazil. Trematodes were found in the stomach of 14 specimens of 9 fish species belonging to 8 families (Carangidae, Clupeidae, Haemulidae, Muraenidae, Percophidae, Pinguipedidae, Trichiuridae, and Triglidae). Trematode specimens were studied using morphological and molecular genetic analyses. A total of eight hemiurid species from four genera, Ectenurus, Lecithochirium, Myosaccium, and Parahemiurus were identified. This paper reports on new host records for four species of hemiurids, adds a new record on the geographical distribution for one species, and provides the first DNA sequence data supplemented with the detailed description of morphology for five species. Phylogenetic analyses supported that the subfamily classifications of the Hemiuridae-based entirely on morphological characters-needs to be reconsidered, taking into account a wider range of information sources.

Digenean trematodes infecting the frigate tuna Auxis thazard (Scombriformes, Scombridae) off the Rio de Janeiro coast, Brazil, including molecular data

Although some parasitological efforts have focused on the frigate tuna Auxis thazard (Lacepède) (Scombriformes, Scombridae) in Brazil, its digenean fauna remains poorly known. Combining morphological and molecular methods, we investigated the diversity of digenean trematodes of A. thazard collected from the coastal waters off the state of Rio de Janeiro, Brazil in 2021. Six species belonging to four families were recorded: the bucephalid Rhipidocotyle cf. angusticolle Chandler, 1941, the didymozoid Didymocystis sp. 6 sensu Louvard et al. (2022), the fellodistomid Tergestia sp., and three hemiurids, Dinurus euthynni Yamaguti, 1934, Lecithochirium floridense (Manter, 1934), and L. synodi Manter, 1931. The current study brings the total number of digenean trematode species parasitising A. thazard in Brazil up to eight, with hemiuroid trematodes being most diverse. Auxis thazard is a new host record for L. floridense, L. synodi and potentially for R. angusticolle. The geographic distribution of several species found in our study appeared to be wider than previously known. Our study is the first to apply a DNA-based approach to digenean diversity in marine fishes in Brazil and we believe that both morphological descriptions and molecular sequence data provided in our study will aid future research assessing the diversity of digenean trematodes of A. thazard and other marine fishes in Brazil.

Another plea for 'best practice' in molecular approaches to trematode systematics: Diplostomum sp. clade Q identified as Diplostomum baeri Dubois, 1937 in Europe

DNA sequence data became an integral part of species characterization and identification. Still, specimens associated with a particular DNA sequence must be identified by the use of traditional morphology-based analysis and correct linking of sequence and identification must be ensured. Only a small part of DNA sequences of the genus Diplostomum (Diplostomidae) is based on adult isolates which are essential for accurate identification. In this study, we provide species identification with an aid of morphological and molecular (cox1, ITS-5.8S-ITS2 and 28S) characterization of adults of Diplostomum baeri Dubois, 1937 from naturally infected Larus canus Linnaeus in Karelia, Russia. Furthermore, we reveal that the DNA sequences of our isolates of D. baeri are identical with those of the lineage Diplostomum sp. clade Q , while other sequences labelled as the ‘D. baeri’ complex do not represent lineages of D. baeri. Our new material of cercariae from Radix balthica (Linnaeus) in Ireland is also linked to Diplostomum sp. clade Q. We reveal that D. baeri is widely distributed in Europe; as first intermediate hosts lymnaeid snails (Radix auricularia (Linnaeus), R. balthica) are used; metacercariae occur in eye lens of cyprinid fishes. In light of the convoluted taxonomy of D. baeri and other Diplostomum spp., we extend the recommendations of Blasco-Costa et al. (2016, Systematic Parasitology 93, 295–306) for the ‘best practice’ in molecular approaches to trematode systematics. The current study is another step in elucidating the species spectrum of Diplostomum based on integrative taxonomy with well-described morphology of adults linked to sequences.

CFD study of the water production in mature heavy oil fields with horizontal wells

Excessive water production in mature heavy oil fields causes incremental costs, energy consumption, and inefficiency. Understanding multiphase flows near the wellbore is an alternative to improve production efficiency. Therefore, this study conducts a series of numerical experiments based on the full set of the Navier-Stokes equations in 3D to simulate multiphase flows in porous media for heavy oil production horizontal wells. The solution given by this advanced mathematical formulation led to the description of the movement of the fluids near the wellbore with unprecedented detail. A sensitivity analysis was conducted on different rock and fluid properties such as permeability and oil viscosity, assuming homogeneous porous media. The influence of these parameters on the prediction of the breakthrough time, aquifer movement, and the severity of water production was noticed. Finally, the numerical model was verified against field data using two approaches. The first one was conducting a history match assuming homogeneous rock properties. In contrast, the second one used heterogeneous rock properties measured from well logging, achieving a lower deviation than field data, about 20%. The homogeneous numerical experiments showed that the breakthrough occurs at the heel with a subsequent crestation along the horizontal well. Moreover, at adverse mobility ratios, excessive water production tends to happen in water connings at the heel with an inflow area less than 1% of the total inflow area of the completion liner. Different aquifer movement dynamics were found for the heterogeneous case, like the breakthrough through multiple locations along the horizontal well. Finally, critical hydraulic data in the well, such as the pressure and velocity profiles, were obtained, which could be used to improve production efficiency. The numerical model presented in this study is proposed as an alternative to conducting subsurface modeling and well designs.

Diversity of echinostomes (Digenea: Echinostomatidae) in their snail hosts at high latitudes

The biodiversity of freshwater ecosystems globally still leaves much to be discovered, not least in the trematode parasite fauna they support. Echinostome trematode parasites have complex, multiple-host life-cycles, often involving migratory bird definitive hosts, thus leading to widespread distributions. Here, we examined the echinostome diversity in freshwater ecosystems at high latitude locations in Iceland, Finland, Ireland and Alaska (USA). We report 14 echinostome species identified morphologically and molecularly from analyses of nad1 and 28S rDNA sequence data. We found echinostomes parasitising snails of 11 species from the families Lymnaeidae, Planorbidae, Physidae and Valvatidae. The number of echinostome species in different hosts did not vary greatly and ranged from one to three species. Of these 14 trematode species, we discovered four species (Echinoparyphium sp. 1, Echinoparyphium sp. 2, Neopetasiger sp. 5, and Echinostomatidae gen. sp.) as novel in Europe; we provide descriptions for the newly recorded species and those not previously associated with DNA sequences. Two species from Iceland (Neopetasiger islandicus and Echinoparyphium sp. 2) were recorded in both Iceland and North America. All species found in Ireland are new records for this country. Via an integrative taxonomic approach taken, both morphological and molecular data are provided for comparison with future studies to elucidate many of the unknown parasite life cycles and transmission routes. Our reports of species distributions spanning Europe and North America highlight the need for parasite biodiversity assessments across large geographical areas.

First molecular assessment of the interrelationships of cladorchiid digeneans (Digenea: Paramphistomoidea), parasites of Neotropical fishes, including descriptions of three new species and new host and geographical records

The first molecular assessment of phylogenetic relationships of cladorchiid digeneans (superfamily Paramphistomoidea Fischoeder, 1901) from freshwater fishes based on 28S rDNA, ITS2 and cox1 sequences reveals the subfamilies Dadayiinae Fukui, 1929 and Kalitrematinae Travassos, 1933 as non-monophyletic, whereas Dadaytrema Travassos, 1931 represented by three species is monophyletic. Fourteen species of cladorchiids were found in characiform, perciform and siluriform fishes in the Neotropical Region (Brazil and Peru), with numerous new host and geographical records. The first scanning electron micrographs of seven species are presented. Two new species of dadayiine and one new species of kalitrematine paramphistomes are described. Microrchis macrovarium sp. n. from Pimelodella cristata (Müller et Troschel) (type host), Tetranematichthys quadrifilis (Kner) and Pterodoras granulosus (Valenciennes) in Brazil and Peru differs from all three congeners in that the testes are directly tandem, not oblique, and that the ovary, between the caecal ends, is widely separated from the testes. Pronamphistoma philippei sp. n. from Heros sp. in Brazil is distinguished from the type and only species, Pronamphistoma cichlasomae Thatcher, 1992, by the absence of the anterior collar-like expansion present in the type species, the presence of extramural rather than intramural pharyngeal sacs, and the unusual development of the dorsal and ventral exterior circular muscle fibre series in the acetabulum. Pseudocladorchis romani sp. n. from P. granulosus (type host), Brachyplatystoma vaillantii (Valenciennes), Calophysus macropterus (Lichtenstein), Megalodoras uranoscopus (Eigenmann et Eigenmann) and Oxydoras niger (Valenciennes) in Brazil and Peru, is most similar to Pseudocladorchis nephrodorchis Daday, 1907 but differs in the shape of the testes (irregular, versus reniform in the latter species) and the size of the ovary (as large as, or larger than, the testes in the new species). The generic diagnosis of Pronamphistoma Thatcher, 1992 is amended. Dadaytremoides parauchenipteri Lunaschi, 1989 is transferred to Doradamphistoma Thatcher, 1979 as D. parauchenipteri (Lunaschi, 1989) comb. n. based on morphological and molecular evidence.

New genera and species of paramphistomes (Digenea: Paramphistomoidea: Cladorchiidae) parasitic in fishes from the Amazon basin in Peru

Two new genera and three new species of paramphistomoid digeneans are described in the family Cladorchiidae Fischoeder, 1901 from doradid, heptapterid, pimelodid and pseudopimelodid fishes in the Amazon River in Peru. Goeldamphistomum amazonum n. g., n. sp. (type-species) from Goeldiella eques (Müller & Troschel) (type-host) and Tenellus trimaculatus (Boulenger), and Goeldamphistomum peruanum n. g., n. sp. from Duopalatinus peruanus Eigenmann & Allen (type-host), Calophysus macropterus (Lichtenstein) and Microglanis sp. are placed in the Dadayiinae Fukui, 1929. Both species have an accessory acetabular sucker, which distinguishes the genus from all taxa previously reported from South American freshwater fishes. They differ from each other primarily in that G. amazonum has a prebifurcal genital pore and oblique, separated testes, the levels of which rarely overlap longitudinally, whereas G. peruanum has a postbifurcal genital pore and testes directly to obliquely tandem. Iquitostrema papillatum n. g., n. sp. (Kalitrematinae Travassos, 1933) from the intestine of Hassar orestis (Steindachner) differs from other members of the subfamily in the combination of a massive acetabulum with a papillate luminal surface and symmetrical testes which overlie the caeca close to the caecal arch. These are the first records of paramphistomes from the five host species studied here.

Different reactions obtained using the same DNA detection reagents for Thai and Korean hepatopancreatic parvovirus of penaeid shrimp

Hepatopancreatic parvovirus (HPV) can cause stunted growth and death in penaeid shrimp including Penaeus monodon. We used PCR primers and a commercial DNA probe designed from HPV of Penaeus chinensis (HPVchin) to examine HPV-infected Thai P. monodon (HPVmon). We found that the PCR primers produced a 732 bp DNA amplicon rather than the 350 bp amplicon obtained with HPVchin template and that the DNA probe gave weak to variable in situ DNA hybridization results. In addition, hybridization to PCR products from HPVmon was weak compared with hybridization with PCR products from HPVchin. By contrast, the 732 bp amplicon hybridized strongly with HPVmon-infected cells by in situ hybridization but not with uninfected shrimp tissue or other shrimp viruses, thus confirming its origin from HPVmon. Cloning, sequencing and analysis of the 732 bp amplicon showed that 696 bp (excluding the primer sequences) contained 47% GC content and had only 78% homology to 701 aligned bases from a 3350 bp DNA fragment of HPVchin from GenBank. These results explain why the reagents based on HPVchin gave a different PCR product and weak hybridization results with HPVmon, and they show that multiple primers or degenerate primers may be necessary for general detection of HPV varieties. Together with previously published information on the estimated total genome sizes for HPVchin (approximately 4 kb) and HPVmon (approximately 6 kb), these data support the contention that HPVchin and HPVmon are different varieties or species, in spite of their similar histopathology.

Identification of the gene immediately downstream of the murine INK4a/ARF locus

The tumor suppressor gene ARF is formed by three exons, namely exons 1 beta, 2 and 3. Here, we show that embryo fibroblasts from mice genetically deficient in exons 2 and 3 (Delta 2,3) express a transcript formed by exon 1 beta followed by the 3'-terminal exon of the gene immediately downstream of the INK4a/ARF locus, which we have called NTp16 (Next-To-p16). The chimeric ARF-NTp16 transcript is not detectable in wild-type fibroblasts but its expression level in Delta 2,3 fibroblasts is 30% compared to the level of the normal ARF transcript in wild-type cells. Expression of the ARF-NTp16 transcript in Delta 2,3 cells is subject to normal regulatory features, such as upregulation by the accumulation of cell doublings, and by the presence of oncogenic Ras or E1a. The chimeric ARF-NTp16 transcript has the potential to encode a 17kDa peptide; however, this peptide is not accumulated in cells at detectable levels, probably reflecting poor codon usage or protein instability. We conclude that Delta 2,3 cells do not retain ARF functionality, at least to a significant extent. Interestingly, the expression pattern of the full-length NTp16 gene is altered in several tissues by the presence of the Delta 2,3 mutation. Finally, these data identify the gene immediately downstream of the INK4a/ARF locus, a region that has been previously proposed to contain another tumor suppressor different from the INK4a/ARF genes.

IFNalpha 2b induces apoptosis and proteasome-mediated degradation of p27Kip1 in a human lung cancer cell line

IFNs are a family of cytokines involved in antiviral defense, cell growth regulation and immune activation. IFNs either inhibit cell proliferation or control apoptosis depending on factors such as cell type and state of cell differentiation. It is important to determine how IFN-induced gene products interact with other cellular proteins to produce these responses. We have investigated the effect of IFNalpha 2b on a human small cell lung carcinoma (SCLC) cell line H82. We have found that IFNalpha efficiently induces apoptosis in H82 cells. The induction of apoptosis by IFNalpha 2b is accompanied by decreased levels of c-myc and Cdk2. We have also observed that in H82 cells IFNalpha induces downregulation of p27 and this is in contrast to the upregulation of p27 observed in other cell types where IFNs induce cell cycle arrest. IFNalpha-induced downregulation of p27 is due to protein destabilization and can be prevented by the proteasome inhibitor LLnL. The data suggest that in H82 cells, IFNalpha 2b induces degradation of p27Kip1 independently of CDK2 kinase activity and through a ubiquitin or ubiquitin-related pathway and that the degradation of p27Kip1 could be a molecular event of importance for IFN-induced apoptosis in cancer cells.

Murine fibroblasts lacking p21 undergo senescence and are resistant to transformation by oncogenic Ras

The cell-cycle inhibitor p21 is upregulated during senescence and upon induction of senescence-like arrest by oncogenic Ras. We have used primary fibroblasts derived from p21-null mice to evaluate the role of p21 in these processes. We find that primary p21-/- cells enter senescence and have a lifespan similar to wild-type cells. Upon immortalization, most wild-type and p21-/- cultures acquire alterations in either p53 or p16INK4a, further indicating that p21-deficiency is not sufficient by itself to allow immortalization. Primary p21-/- cells, like wild-type cells, respond to oncogenic Ras by accumulating p53 and p16INK4a, and by decreasing their proliferation rate. In agreement with this, p21-/- cells are refractory to neoplasic transformation by oncogenic Ras when compared to p53-/- cells. We conclude that, in murine fibroblasts, p21 is not essential neither for senescence nor for preventing neoplasic transformation by oncogenic Ras.

Involvement of calcium in the cardiac depressant actions of a garlic dialysate

In order to elucidate a possible role for calcium on the negative cardiotropic effects of a garlic (Allium sativum L., Liliaceae) dialysate in rat atria we studied: (a) the effects of our extract 15 min after preincubation with high and low concentrations of extracellular calcium ([Ca2+]o) on left and right activity of rat atria. The negative inotropism of garlic dialysate increased with calcium 0.75 mM; in contrast, high level of calcium (4.5 mM) induced a significant reduction of this depressant effect. None of these treatments modified the negative chronotropism of garlic; (b) nifedipine (10(-9) to 10(-7) M, verapamil (10(-9) to 10(-7) M) and diltiazem (10(-9) to 10(-7) M) induced a concentration-dependent synergism of the log concentration-effect of garlic dialysate on left atria. Verapamil and diltiazem (10(-7)M), but not nifedipine increased the inhibitory chronotropism of garlic in right atria; (c) negative inotropic and chronotropic effects demonstrated by nifedipine (1 x 10(-10) to 1.1 x 10(-6) M) were antagonized as expected by preincubation with Bay K-8644. Depressant actions of garlic were not modified with this pretreatment. These results suggest that the negative inotropic effect of our garlic dialysate is related to [Ca2+]o availability. It is possible that a restriction of intracellular calcium contributes to this effect. However, the negative chronotropic effect of garlic is scarcely affected by these modifications.

[Tuberculin reactivity in the elderly. Comparison of PPD-RT23 and PPD-CT68]

BACKGROUND

Tuberculin reactivity varies on the basis of the PPD lot and the population studied.

AIMS

To compare tuberculin reactivity in the elderly following successive applications of PPD from 2 different lots.

POPULATION

Elderly nursing-home residents, from the province of Guadalajara, Spain.

METHODS

The elderly were randomly selected and administered with a first Mantoux intradermoreaction of 2 UT of PPD-RT23 or 2 UT of PPD-CT68. The study was performed in a scaled basis, eliminating the reactors (transversal induration > or = 5 mm at 72 h). The non reactors were restudied with a second and third test in alternative arms at a 7-day interval with the same lot and initial dosis of PPD. At one year the scaled study was repeated with 2 UT of PPD-CT68.

RESULTS

Eight hundred and thirty elderly persons (79 +/- 9 years) were studied, with 410 receiving PPD-RT23 and 420 receiving PPD-CT68. No differences were observed in the percentage of initial reactors (31% vs 29%; p = 0.26) or in the booster reactors (23% vs 20%; p = 0.16). The PPD-RT23 was found to trigger more intensive reactions than the PPD-CT68 leading to a greater frequency of indurations > 14 mm. After one year, the percentage of stable reactions was similar in both groups (50.5% vs 49.5%; NS).

CONCLUSIONS

1) In elderly nursing-home residents 2 UT of PPD-RT23 and 2 UT of PPD-CT68 showed similar results in regard to the number of reactors and the frequency of booster reactions. 2) The proportion of intense reactions was greater with 2 UT of PPD-RT23 than with 2 UT of PPD-CT68. 3) The stability of the reactions at one year was independent of the lot used in the first phase.

Anti-arrhythmic profile of a garlic dialysate assayed in dogs and isolated atrial preparations

The effects of garlic (Allium sativum L., Liliaceae) dialysate were studied on arrhythmias induced in anaesthetized dogs and on isolated left rat atria. Garlic dialysate suppressed premature ventricular contractions (PVC) and ventricular tachycardia (VT) in ouabain-intoxicated dogs as well as the ectopic rhythms induced by isoprenaline (10(-6) M) and aconitine (10(-8) M) on electrically driven left rat atria. The effective refractory period (ERP) and the sinus node recovery time (SNRT) of isolated rat atria were prolonged in a dose-dependent manner by the administration of this extract. Garlic dialysate decreased the positive inotropic and chronotropic effects of isoprenaline in a concentration-dependent manner. These last effects were increased by propranolol. The results suggest that garlic dialysate has a significant antiarrhythmic effect in both ventricular and supraventricular arrhythmias.

Effect of bovine heart atrial natriuretic and diuretic fractions on sodium transport in isolated toad skin

The effects of two bovine heart atrial fractions (AF I and AF II) were investigated in toad skin. When added to the inner (serosal) solution, AF I caused a maximal reversible depression of the transepithelial potential and short-circuit current of about 60% and AF II induced maximal decline of these parameters of only 35%. When added to the outer (mucosal) solution, the effect of both fractions was often only partially reversible. Isaacson's amiloride test showed that AF I decreased the numerical estimates of all the components in the electrical equivalent circuit. The net Na+ flux decreased due to a fall in Na+ flux in the active direction. Incubation with Ca2+-free Ringer's solution decreased and Ca2+ ionophore A 23187 increased the effect of AF II. Partial replacement of sodium by choline in the outer solution slightly reduced the effect and substitution of normal Ringer's solution with sulfate or isethionate Ringer's solution in the outer solution significantly enhanced the effect of the AF. These results indicate that bovine heart atrial natriuretic fractions decrease the sodium potential (ENa), sodium conductance (GNa) and passive conductance (Gsh). The fall in net Na+ transport measured with sodium tracer fluxes confirms the decrease in ENa and GNa.