Intrigue surrounding the life-cycles of species of Clistobothrium (Cestoda: Phyllobothriidea) parasitising large pelagic sharks.

This study aimed to locate the adults, and thus also the definitive hosts, of three species of marine mammal-parasitising larval cestodes that have molecular affinities with Clistobothrium. New collections led to the discovery of adults of two new species of Clistobothrium, one from the longfin mako shark and one from the salmon shark. New material of Clistobothrium tumidum was collected from the great white shark and new material of a previously reported undescribed species of Clistobothrium was collected from the porbeagle shark. Larvae of Clistobothrium were opportunistically collected from sockeye salmon and four species of small squaliform sharks. Sequence data for the D1-D3 region of the 28S rDNA gene were generated for all but one of these taxa. The tree resulting from maximum likelihood analysis of those data, in combination with comparable data from GenBank, indicates that squaliform sharks can serve as intermediate hosts for the species from the porbeagle shark. The larvae from salmon exhibit a unique molecular signature and, based on diet data, may be conspecific with adults from the salmon shark. Informed by sequence data for new material of Monorygma and existing data for Phyllobothrium, the larvae provisionally identified as Monorygma grimaldii and Phyllobothrium delphini were formally transferred to Clistobothrium. Especially puzzling was that the molecular signatures of none of the eight species of Clistobothrium match those of the three marine mammal-parasitising larval forms. We are at a loss as to where else to look for the three corresponding adult forms. The great white shark remains the most likely candidate given it consumes marine mammals with some regularity, but seems unlikely to host five species of Clistobothrium. Alternatively, we are left wondering if the large marine mammal predator Carcharocles megalodon may not be extinct after all.

Long-term changes in liana loads and tree dynamics in a Malaysian forest.

The importance of lianas through time and their effect on tree reproduction are evaluated for the first time in a Southeast Asian Dipterocarp forest. We quantified flower and seed production by lianas and trees for 13 years, assessed liana loads in the crowns of all trees larger than 30 cm in diameter at breast height (1.3 m) in 2002 and 2014, and assessed levels of reproduction for the same trees during a strong general flowering event in 2014 for the 50-ha forest dynamics plot at the Pasoh Forest Reserve, Malaysia. General flowering refers to synchronous reproduction by hundreds of plant species at irregular, multiyear intervals and only occurs in Southeast Asian Dipterocarp forests. Overall, lianas were present in 50% of tree crowns and comprised 31% of flower production and 46% of seed production. Lianas reduced growth, survival, and reproduction by their host trees. Lianas were less frequent in canopy- emergent trees, Dipterocarps comprised a disproportionately large proportion of canopy emergents, and, as a consequence, lianas were less frequent in Dipterocarps than in trees from other plant families. Lianas infested the crowns of significantly fewer trees in 2014 (47.9%) than in 2002 (52.3%); however, the decrease was restricted to trees with the lightest liana loads and sample sizes and statistical power were enormous. Lianas comprised a stable proportion of flower production and a highly variable proportion of seed production from 2002 through 2013. We conclude lianas have a huge impact on trees in this forest and were a stable component of the forest between 2002 and 2014. The emergent habit and associated ability to avoid lianas might contribute to the success of the Dipterocarpaceae.

The dismantling of Calliobothrium (Cestoda: Tetraphyllidea) with erection of Symcallio n. gen. and description of two new species.

This paper aims to resolve the dual composition of the triakid shark-hosted tetraphyllidean genus Calliobothrium--an issue that has been recognized for over a decade. As it stands, this genus includes a number of large species with laciniate proglottids, most of which bear 3 suckers at the anterior margin of each bothridium, but it also includes a number of species that lack proglottid laciniations and bear only a single sucker per bothridium, most of which are relatively small. Discovery of 2 new species, 1 of each form, parasitizing the whitespot smoothhound shark, Mustelus palumbes, off South Africa, prompted the first molecular analysis of the genus. Bayesian inference and maximum likelihood analyses of 28S rDNA (D1-D3) sequence data generated for specimens of both new species as well as of 2 known species of the laciniate form (Calliobothrium australis and Calliobothrium cf. verticillatum) and 3 known species of the non-laciniate form (Calliobothrium violae, Calliobothrium riseri, and Calliobothrium barbarae) confirmed the reciprocal monophyly of the 2 clades, supporting establishment of a new genus. Because the type of Calliobothrium, C. verticillatum, is of the laciniate form, Symcallio n. gen., with Symcallio peteri n. gen., n. sp., from M. palumbes described as its type, is established to house members of the non-laciniate clade. The 11 described species consistent with this form are transferred to the new genus. A new species of the laciniate clade, Calliobothrium euzeti n. sp., is described from M. palumbes, and a revised diagnosis of Calliobothrium is presented.

Monsters of the sea serpent: parasites of an oarfish, Regalecus russellii.

Examination of a small portion of the viscera of an oarfish ( Regalecus russellii ) recovered from Santa Catalina Island, southern California, revealed numerous tetraphyllidean tapeworm plerocercoids, Clistobothrium cf. montaukensis; 2 juvenile nematodes, Contracaecum sp.; and a fragment of an adult acanthocephalan, family Arhythmacanthidae. This suggests that the fish was relatively heavily parasitized. The presence of larval and juvenile worms suggests that oarfish are preyed upon by deep-swimming predators such as the shortfin mako shark, Isurus oxyrinchus , known to be a definitive host for the adult tapeworm, and also by diving mammals such as sperm whales, Physeter catodon L., hosts of Contracaecum spp. nematodes.

Seasonal dynamics of the cestode fauna in spiny dogfish, Squalus acanthias (Squaliformes: Squalidae).

This study furthers understanding of cestode infections in a marine environment through time and space by following seasonal fluctuations in infection parameters of three cestode species (Gilquinia squali, Trilocularia gracilis and Phyllobothrium squali) parasitizing spiny dogfish (Squalus acanthias) in the northwest Atlantic and comparing them to work previously published from the northeast Atlantic on T. gracilis. For each cestode species, host size, season and presence of the other cestode species were analysed using generalized linear models to determine if they were good predictors of prevalence and intensity. Infection parameters differed across season for the three cestode species. However, within T. gracilis seasonal trends were found to be remarkably similar on both sides of the Atlantic, differing only in a somewhat delayed decline in prevalence in the northwest Atlantic. The differences seen in infection measures across cestode species likely reflect the unique life history strategies of different parasite species. While general trends appear to be maintained across disparate localities, variation seen is likely due to differences in accessibility to intermediate hosts and host diet across sites. The knowledge gained from understanding cestode infections in the vast ocean environment allows us to speculate about the factors driving fluctuations in parasite infections in elasmobranchs.

Differences in microthrix form between stomach and spiral intestine stages of the cestode, Trilocularia: interspecific variation or development?

Tetraphyllidean cestodes of the genus Trilocularia have been reported from Squalus acanthias throughout this shark's global distribution, occupying both the stomach and spiral intestine. This study investigated whether variation seen in microthrix form among specimens within this host species is indicative of interspecific variation or is attributable to developmental transformation of a single cestode species. Sequence data for the 2 nuclear genes 28S rDNA (D1-D3) and ITS1, and the mitochondrial gene 16S rDNA, were generated for 22 specimens of Trilocularia; 3 from the stomach and 19 from the spiral intestine, including individuals exhibiting each of the 3 spinithrix forms found. Sequence data for 22 specimens were identical for the 2 nuclear genes. Some variation was seen in the mitochondrial gene but maximum likelihood analysis revealed no pattern with either site or microthrix type, suggesting microthrix variation may be developmental. To explore the developmental hypothesis further, a total of 118 juvenile worms from the stomach and 124 from the spiral intestine were collected from S. acanthias off the coast of Rhode Island and examined with either scanning electron microscopy (SEM) or light microscopy. SEM revealed differences in microthrix form between worms from the 2 sites. Of the stomach and spiral intestine worms examined, respectively, 98% versus 30% were scolopate, 2% versus 47% were aristate gladiate, and 0% versus 15% were lingulate in microthrix form. In addition, 3 of the 77 specimens from the spiral intestine examined with SEM exhibited mixtures of spinitriches. ANOVAs showed significant differences in the morphometrics of stomach worms, when compared to spiral intestine worms, as well as significat differences in the scolex width:below scolex width ratio of worms with scolopate spinitriches when compared to those with aristate gladiate or lingulate spinitriches. In combination, these data suggest that microthrix form may change over the course of development, indicating that caution should be exercised when interpreting microthrix patterns in the context of species designations.

A new hyperapolytic species, Trilocularia eberti sp. n. (Cestoda: Tetraphyllidea), from Squalus cf. mitsukurii (Squaliformes: Squalidae) off South Africa with comments on its development and fecundity.

A new species of tetraphyllidean cestode in the genus Trilocularia is described from an undescribed shark species, Squalus cf. mitsukurii, off the coast of South Africa. Trilocularia eberti sp. n. is the second known member of its genus, and like its congener, T. gracilis (Olsson, 1866-1867) Olsson, 1869, is extremely hyperapolytic, dropping proglottids from its strobila while they are still very immature. Characteristic of the genus, it possesses a distinctive scolex with triloculated bothridia, but differs conspicuously from its congener in its possession of an anterior loculus that is much larger in width relative to the paired posterior loculi, and also in its possession of an anterior, enlarged region of its free proglottids that is triangular with a slit-like ventral aperture, rather than rounded and cup-like. This anterior region of the free proglottid is used in attachment, and its development is described. For assessment of fecundity, an attempt was made to record all free proglottids of all ages found in both host individuals, and yielded an average estimate of 362 free proglottids being produced per individual worm of T. eberti sp. n. Both Trilocularia species parasitize sharks of the genus Squalus, and given the host specificity typically exhibited by tetraphyllideans and preliminary examinations of other members of this shark genus, it is likely that other Squalus species will be found to host additional new Trilocularia species.

Ecosystem energetic implications of parasite and free-living biomass in three estuaries.

Parasites can have strong impacts but are thought to contribute little biomass to ecosystems. We quantified the biomass of free-living and parasitic species in three estuaries on the Pacific coast of California and Baja California. Here we show that parasites have substantial biomass in these ecosystems. We found that parasite biomass exceeded that of top predators. The biomass of trematodes was particularly high, being comparable to that of the abundant birds, fishes, burrowing shrimps and polychaetes. Trophically transmitted parasites and parasitic castrators subsumed more biomass than did other parasitic functional groups. The extended phenotype biomass controlled by parasitic castrators sometimes exceeded that of their uninfected hosts. The annual production of free-swimming trematode transmission stages was greater than the combined biomass of all quantified parasites and was also greater than bird biomass. This biomass and productivity of parasites implies a profound role for infectious processes in these estuaries.

Diagnosis of the small round blue cell tumors using multiplex polymerase chain reaction.

The small round blue cell tumors of childhood, which include neuroblastoma, rhabdomyosarcoma, non-Hodgkin's lymphoma, and the Ewing's family of tumors, are so called because of their similar appearance on routine histology. Using cDNA microarray gene expression profiles and artificial neural networks (ANNs), we previously identified 93 genes capable of diagnosing these cancers. Using a subset of these, together with some additional genes (total 39), we developed a multiplex polymerase chain reaction (PCR) assay to diagnose these cancer types. Blinded testing of 96 new samples (26 Ewing's family of tumors, 29 rhabdomyosarcomas, 24 neuroblastomas, and 17 lymphomas) using ANNs in a complete leave-one-out analysis demonstrated that all except one sample were accurately diagnosed as their respective category. Moreover, using an ANN-based gene minimization strategy in a separate analysis, we found that the top 31 genes could correctly diagnose all 96 tumors. Our results suggest that this molecular test based on a multiplex PCR reaction may assist the physician in the rapid confirmation of the diagnosis of these cancers.

Analysis of microbial gene transcripts in environmental samples.

We analyzed gene expression in marine and freshwater bacterioplankton communities by the direct retrieval and analysis of microbial transcripts. Environmental mRNA, obtained from total RNA by subtractive hybridization of rRNA, was reverse transcribed, amplified with random primers, and cloned. Approximately 400 clones were analyzed, of which approximately 80% were unambiguously mRNA derived. mRNAs appeared to be from diverse taxonomic groups, including both Bacteria (mainly alpha- and gamma-Proteobacteria) and Archaea (mainly Euryarchaeota). Many transcripts could be linked to environmentally important processes such as sulfur oxidation (soxA), assimilation of C1 compounds (fdh1B), and acquisition of nitrogen via polyamine degradation (aphA). Environmental transcriptomics is a means of exploring functional gene expression within natural microbial communities without bias toward known sequences, and provides a new approach for obtaining community-specific variants of key functional genes.