Muscular anatomy and aspects of the structure of the antennae of Anthosoma crassum (Dichelesthiidae: Siphonostomatoidae: Copepoda)

The muscular anatomy and fine structure of the antennae of adult Anthosoma crassum are described from specimens collected from jaws of shortfin makos. Casual observations of live parasites showed that embedded adult A. crassum can move toward or away from the host by shortening or lengthening the antennae, respectively. These movements were controlled by antennal retractor muscles. Microprotuberances located on the distal antennal segments may increase friction between these copepods and their hosts, thus strengthening parasite attachment.     

Application of bomb radiocarbon chronologies to shortfin mako (Isurus oxyrinchus) age validation

Age estimation is an issue for the shortfin mako, Isurus oxyrinchus, because of disagreement on vertebral band-pair deposition periodicity. In the 1950s–1960s, thermonuclear testing released large amounts of radiocarbon into the atmosphere, which diffused into the ocean through gas exchange. This influx created a time-specific marker that can be used in age validation. Annual band-pair deposition in the porbeagle, Lamna nasus, was validated in a previous study and indicated preliminary annual deposition in the shortfin mako, using four samples from one vertebra. In the present study, age estimates from 54 shortfin mako vertebrae collected in 1950–1984 ranged 1–31 years. Ageing error between readers was consistent, with 76% of the estimates ranging within 2 years. Twenty-one Δ¹⁴C values from eight shortfin mako vertebrae (collected in the western North Atlantic in 1963–1984) ranged −154.8‰ to 86.8‰. The resulting conformity with the Δ¹⁴C timeline for the porbeagle supported annual band-pair deposition in vertebrae of the shortfin mako.     

Estimating survival of the shortfin mako Isurus oxyrinchus (Rafinesque) in the north-west Atlantic from tag-recapture data

Survival was estimated for shortfin mako Isurus oxyrinchus in the north-west Atlantic from tag-recapture data. The data used in this study were collected by the National Marine Fisheries Service Cooperative Shark Tagging Programme from 1962 to 2003. In total, 6309 shortfin mako sharks were tagged, of which 730 were recaptured. The high recapture rate of 11·6% for this species provided adequate recapture data to carry out survival analyses. Estimates of survival were generated with the computer software MARK, which provided a means for estimating parameters from tagged animals when they were recaptured. The results of several models are presented with various combinations of constant and time-specific survival and recovery rates. A parametric bootstrap and the median variance inflation factor ( ) approach were used to test the fit of the general model to the data. The estimated indicated a very good model fit. The models with time invariant survival rate had the most support from the data and no group or time period effects were found. Recovery rate ( f ) appeared to increase from 0·043 in the early years to 0·056 in the later years. The nominal survival rate of 0·59 year⁻¹ was adjusted with an estimated tag-shedding rate of 0·26 year⁻¹ to generate a final corrected annual survival estimate of 0·79 with a 95% CI of 0·71–0·87.     

Pugnose eels, Simenchelys parasiticus (Synaphobranchidae) from the heart of a shortfin mako, Isurus oxyrinchus (Lamnidae)

The body depth of crucian carp, Carassius carassius, increases in the presence of predator fish, thereby decreasing the vulnerability of crucian carp to predation. This phenotypic change is mediated by chemical signals, and is believed to result from a piscivorous diet of predators. We have shown that exposure to a piscivorous predator is insufficient to induce growth changes in crucian carp, since water from northern pike, Esox lucius, fed Arctic charr, Salvelinus alpinus, does not induce a change in crucian carp morphology, while water from pike fed crucian carp does. The determining factor is a chemical signal from the skin of crucian carp, as demonstrated by exposure to skin extracts from conspecifics. We suggest that alarm substances from conspecifics, expressing primer pheromone effects, are the most likely candidates for induction of the phenotypical changes.     

New insights on the trophic ecology of blue (Prionace glauca) and shortfin mako sharks (Isurus oxyrinchus) from the oceanic eastern South Pacific

The blue shark (Prionace glauca) and the shortfin mako shark (Isurus oxyrinchus) are two large and highly migratory sharks distributed in most oceans. Although they are often caught in the south Pacific Ocean long-line fisheries, their trophic ecology is poorly understood. Stable isotopes with Bayesian mixing and dependence concentration models were performed to determine the diet and trophic differences between the two species in the South-eastern Pacific Ocean. According to the mixing models, fishes are the most important prey of these sharks. Dolphin calves and remains were found in the stomachs of both species, which represents a novel finding in trophic ecology of South Pacific sharks. Intra-specific differences were found in P. glauca, but not in specimens of I. oxyrinchus. The two sharks showed a high degree of diet overlap (73%), primarily over mackerel and dolphin carcasses. Our results indicate that blue and shortfin mako sharks have a generalist feeding strategy in the eastern Pacific Ocean, with a strong preference for teleost fishes and also for dolphin carcasses. Therefore, trophic studies are useful to understand energy flow through the food web, and the trophic position of key species.     

Quantification of red myotomal muscle volume and geometry in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis) using T1-weighted magnetic resonance imaging

T1-weighted magnetic resonance imaging (MRI) in conjunction with image and segmentation analysis (i.e., the process of digitally partitioning tissues based on specified MR image characteristics) was evaluated as a noninvasive alternative for differentiating muscle fiber types and quantifying the amounts of slow, red aerobic muscle in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis). MRI-determinations of red muscle quantity and position made for the mid-body sections of three mako sharks (73.5-110 cm fork length, FL) are in close agreement (within the 95% confidence intervals) with data obtained for the same sections by the conventional dissection method involving serial cross-sectioning and volumetric analyses, and with previously reported findings for this species. The overall distribution of salmon shark red muscle as a function of body fork length was also found to be consistent with previously acquired serial dissection data for this species; however, MR imaging revealed an anterior shift in peak red muscle cross-sectional area corresponding to an increase in body mass. Moreover, MRI facilitated visualization of the intact and anatomically correct relationship of tendon linking the red muscle and the caudal peduncle. This study thus demonstrates that MRI is effective in acquiring high-resolution three-dimensional digital data with high contrast between different fish tissue types. Relative to serial dissection, MRI allows more precise quantification of the position, volume, and other details about the types of muscle within the fish myotome, while conserving specimen structural integrity.     

Movement of sturgeons (Acipenser oxyrinchus oxyrinchus and A. fulvescens) in the St. Lawrence Estuary: A 35-year tagging study

Movement of Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) and lake sturgeon (A. fulvescens) in the St. Lawrence Estuary (Québec, Canada) are not fully understood. To assess the movement extent of both species, a mark–recapture study was conducted in collaboration with commercial fishermen operating in the St. Lawrence Estuary. Between 1981 and 2015, 3,367 Atlantic sturgeon (fork length 21.8–199.5 cm) and 3,180 lake sturgeon (fork length 17.8–190.8 cm) were tagged and released. Of these, 673 Atlantic sturgeon and 42 lake sturgeon were recaptured. The maximum distances traveled between capture and recapture locations were 1,307 km for Atlantic sturgeon (8 years after initial capture) and 252 km for lake sturgeon (less than 1 year after initial capture). Statistical analyses identified differences in the dispersal distance of both species as revealed by a first component characterized by individuals with short dispersal distances (98% and <35 km for Atlantic sturgeon; 58% and <1 km for lake sturgeon) and a second component characterized by individuals with longer dispersal distances (2% and >600 km for Atlantic sturgeon; 42% and >190 km for lake sturgeon). We suggest that the short dispersal distances detected in the vast majority of Atlantic sturgeon recaptures likely reflect strong site fidelity, highlighting the importance of the St. Lawrence Estuary as a preferred habitat for juveniles and subadults. Although recaptures were low for lake sturgeon because this species is only marginally targeted by commercial fishermen in the St. Lawrence Estuary, our results also showed that this species uses estuarine habitats and that half of the population seems to exhibit strong site fidelity (67% of individuals were recaptured within 2 km).     

Cardiac and pancreatic lesions in guinea pigs infected with encephalomyocarditis (EMC) virus.

Cardiac and pancreatic lesions were observed in guinea pigs infected with 2 variants (B and D) of encephalomyocarditis (EMC) virus. Cardiac changes were characterized by focal myocardial necrosis and subsequent replacement by immature granulation tissue, and the pancreatic ones by vacuolar degeneration of acinar cells. In the electron microscopic examinations, the affected cardiomyocytes showed intracellular oedema, swelling and/or partial destruction of mitochondria, and distortion and disruption of myofibrils. Intracellular vacuolization and dilatation of rough-surfaced endoplasmic reticulum (rER) were conspicuous in the damaged pancreatic acinar cells. In addition, intracisternal granules were found in dilated rER with a high frequency. These changes were common to animals infected with the B and D variants. On the contrary, B cell alterations; i.e. degranulation and degeneration of insulin granules, were detected only in animals infected with the D variant.     

Stock composition of Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) encountered in marine and estuarine environments on the U.S. Atlantic Coast

Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) is a large, anadromous fish native to the Atlantic Coast of North America. Although this species once supported important fisheries, centuries of exploitation and habitat degradation have resulted in dramatic declines, presumed extirpation in some rivers, and ultimately listing under the U.S. Endangered Species Act (ESA). Under the ESA, Atlantic sturgeon are listed as five separate Distinct Population Segments (DPSs), which form the basis for federal management. Despite state and federal protections Atlantic sturgeon still face significant threats to their recovery, including fisheries bycatch mortality, marine construction, dredging, dams, and vessel strikes. However, because subadult and adult Atlantic sturgeon migrate extensively across estuarine and marine environments and frequently form mixed-stock aggregations in non-natal habitats, it can be difficult to determine how these threats impact specific populations and DPSs. To better understand ontogenetic shifts in habitat use and stock-specific exposure to anthropogenic threats, we performed a mixed-stock analysis of 1704 Atlantic sturgeon encountered across the U.S. Atlantic Coast. Collections made north of Cape Cod, MA and south of Cape Hatteras, NC were dominated by individuals from regional stocks; however, we found extensive stock mixing in the mid-Atlantic region, particularly in coastal environments where individuals from all five DPSs were commonly observed. Subadults and adults that were encountered in offshore environments had moved, on average, 277 km from their natal source; however, 23% were sampled over 500 km from their natal river suggesting long-distance movements are relatively common in these age classes. Overall, our work highlights that Atlantic sturgeon populations are vulnerable to threats over vast areas and emphasizes the need for continued genetic monitoring to track recovery progress.

     

First report of Gyrodactylus spp. (Platyhelminthes: Monogenea) in the western Mediterranean Sea: molecular and morphological descriptions

The Gyrodactylus spp. fauna on species of gobies, Pomatoschistus, Gobiusculus, and Knipowitschia (Gobiidae: Teleostei), from the western Mediterranean and Adriatic seas is strikingly similar to that found in the Baltic Sea and eastern Atlantic Ocean, both in morphology and in internal transcribed spacer (ITS) rRNA. The fauna consisted of Gyrodactylus branchialis, G. ostendicus, G. gondae, G. rugiensis, G. rugiensoides, and G. arcuatus. No new species have been found. A morphometric comparison between G. branchialis from the Mediterranean and Adriatic seas and its type locality in Ostend (Belgium) showed significant differences in ventral bar and marginal hook features. The morphometric variation was lower in G. rugiensis, whereas no significant differences were found in G. ostendicus. Gyrodactylus branchialis and G. ostendicus collected on P. microps were slightly different in the ITS rDNA (-0.6%) compared with specimens on the closely related P. marmoratus, probably reflecting ongoing speciation. A hybrid zone was identified in the Vaccarès lagoon complex (France) where both host species are sympatric. There was no clear geographic or host-related pattern in the variation found in the ITS2 rDNA in G. arcuatus sampled from P. microps, G. flavescens, Pungitius pungitius, K. panizzae, and its original host Gasterosteus aculeatus (2 polymorphic sites). Of all studied species, only G. arcuatus, G. rugiensis, and G. rugiensoides showed minor intraspecific variation in the ITS rDNA. Hence, the physical separation by a shoreline of more than 10,000 km is hardly reflected in the parasite ITS rDNA.     

p16(INK4A) immunohistochemical overexpression in premalignant and malignant oral lesions infected with human papillomavirus.

Human papillomavirus (HPV) is believed to promote the oncogenic process, and the correlation between viral oncoproteins and dysfunction of p16(INK4A) tumor suppressor protein in oral lesions is controversial. To test the hypothesis that anogenital HPV types participate in disruption of the regulation of p16(INK4A) suppressor protein in oral lesions, we analyzed 46 oral biopsy specimens for the presence of HPV 6/11 and 16/18 by in situ hybridization (ISH) and for p16(INK4A) expression by immunohistochemistry (IHC). Eighteen (39%) of the 46 oral lesions were HPV-positive and 28 (61%) were HPV-negative. HPV 6/11 DNA was found in 5 (11%) and HPV 16/18 in 13 (28%) of 46 biopsies. Nine of the 18 HPV-positive oral lesions (50%), assessed by catalyzed signal amplification coupled to ISH (CSA-ISH), gave high-intensity p16(INK4A) immunostaining. Focal and diffuse patterns were observed in 11/13 (77%) lesions with HPV 16/18, focal immunopositivity in 3/5 (80%) with HPV 6/11, and negative or sporadic p16-labeling in 18/28 (64%) without the presence of HPV DNA. These results showed a strong association between overexpression of p16 protein and malignant oral lesions, mainly those infected by HPV 16/18. We can conclude that high-risk HPV types are associated with p16 overexpression, and p16 may serve as a biomarker in oral cancer related to high-risk HPV infection.     

A revision of the family Dissonidae Kurtz, 1924 (Copepoda: Siphonostomatoida)

Two new species of the parasitic copepod genus Dissonus Wilson, 1906 are described: D. excavatus n. sp. from the gills of a labrid, Bodianus perditio, and a lutjanid, Macolor niger, collected off New Caledonia and Taiwan, and D. inaequalis n. sp. from a hemiscylliid elasmobranch, Chiloscyllium punctatum, collected off Sarawak (Malaysia) and the Philippines. Material of D. heronensis Kabata, 1966 is described from a balistid host, Pseudobalistes fuscus, off New Caledonia, and this constitutes a new host record for this parasite. D. manteri Kabata, 1966 was collected from four serranid host species off New Caledonia and from one of the same hosts off Taiwan. Two of the hosts from New Caledonia, Plectropomus laevis and Epinephelus cyanopodus, represent new host records. D. pastinum Deets & Dojiri, 1990 was recognised as a new synonym of D. nudiventris Kabata, 1966, so the total number of valid species is now twelve. Material from museum collections of D. nudiventris, D. similis Kabata, 1966 and D. spinifer Wilson, 1906 was re-examined and provided new information which is utilised in a key to all valid species of Dissonus.     

Asterocheres flustrae n. sp. (Copepoda: Siphonostomatoida: Asterocheridae) associated with Flustra foliacea L. (Bryozoa) from the White Sea

Asterocheres flustrae n. sp. is described from Flustra foliacea L. (Bryozoa) found in the Kandalaksha Bay of the White Sea. This is the first siphonostomatoid copepod to be reported in association with a bryozoan. Distinctive features of the new species are: (1) a female with 21- and male with 18-segmented antennules; (2) five setae on the inner lobe of the maxillule with one much reduced; (3) an aesthetasc on the syncoxa of the maxilla; (4) a 6-segmented maxilliped with a distal claw; and (5) the armature of endopodal segments 2, 1, 1 and 1. Sexual dimorphism was observed not only on the antennules, but also for maxilliped and legs 1–6. By using SEM some new fine structures were revealed, including: one seta on each of antennulary segments 1 to 4, 6 and 8 with a nipple-like tip and an apical pore surrounded at its base by a circlet of cuticular denticles; a rostral region having a circular area ornamented with minute cuticular protuberances; and the labrum ornamented with fine hair-like setules on either side of its apex.     

First record of the tribe Trigonoderini (Hymenoptera: Pteromalidae) from South Korea with descriptions of two new species

The tribe Trigonoderini (Hymenoptera: Pteromalidae) contains six genera (Gastracanthus Westwood, Janssoniella Kerrich, Miscogasteriella Girault, Platygerrhus Thomson, Plutothrix Förster and Trigonoderus Westwood). This tribe is recorded from South Korea for the first time. Two new species, Janssoniella albiclava Tselikh & Lee sp. nov. from South Korea and J. magna Tselikh & Lee sp. nov. from South Korea and the South Far East of Russia, are described. Eight species (Gastracanthus acutus (Kamijo), G. nigrescens Kamijo, Janssoniella intermedia Hedqvist, Miscogasteriella sulcate (Kamijo), Plutothrix scrobicula Kamijo, P. trifasciata (Thomson), Trigonoderus fraxini Yang and T. nigrocephalus Kamijo) are recorded from South Korea for the first time. The keys for identification of the Eastern–Palearctic species of Janssoniella and Gastracanthus are given and photos of diagnostic characters of the new species are provided.