Antonio C. Marques

Medusozoan Phylogeny and Character Evolution Clarified by New Large and Small Subunit rDNA Data and an Assessment of the Utility of Phylogenetic Mixture Models

A newly compiled data set of nearly complete sequences of the large subunit of the nuclear ribosome (LSU or 28S) sampled from 31 diverse medusozoans greatly clarifies the phylogenetic history of Cnidaria. These data have substantial power to discern among many of the competing hypotheses of relationship derived from prior work. Moreover, LSU data provide strong support at key nodes that were equivocal based on other molecular markers. Combining LSU sequences with those of the small subunit of the nuclear ribosome (SSU or 18S), we present a detailed working hypothesis of medusozoan relationships and discuss character evolution within this diverse clade. Stauromedusae, comprising the benthic, so-called stalked jellyfish, appears to be the sister group of all other medusozoans, implying that the free-swimming medusa stage, the motor nerve net, and statocysts of ecto-endodermal origin are features derived within Medusozoa. Cubozoans, which have had uncertain phylogenetic affinities since the elucidation of their life cycles, form a clade-named Acraspeda-with the scyphozoan groups Coronatae, Rhizostomeae, and Semaeostomeae. The polyps of both cubozoans and hydrozoans appear to be secondarily simplified. Hydrozoa is comprised by two well-supported clades, Trachylina and Hydroidolina. The position of Limnomedusae within Trachylina indicates that the ancestral hydrozoan had a biphasic life cycle and that the medusa was formed via an entocodon. Recently hypothesized homologies between the entocodon and bilaterian mesoderm are therefore suspect. Laingiomedusae, which has often been viewed as a close ally of the trachyline group Narcomedusae, is instead shown to be unambiguously a member of Hydroidolina. The important model organisms of the Hydra species complex are part of a clade, Aplanulata, with other hydrozoans possessing direct development not involving a ciliated planula stage. Finally, applying phylogenetic mixture models to our data proved to be of little additional value over a more traditional phylogenetic approach involving explicit hypothesis testing and bootstrap analyses under multiple optimality criteria. [18S; 28S; Cubozoa; Hydrozoa; medusa; molecular systematics; polyp; Scyphozoa; Staurozoa.].

Exceptionally Preserved Jellyfishes from the Middle Cambrian

Cnidarians represent an early diverging animal group and thus insight into their origin and diversification is key to understanding metazoan evolution. Further, cnidarian jellyfish comprise an important component of modern marine planktonic ecosystems. Here we report on exceptionally preserved cnidarian jellyfish fossils from the Middle Cambrian (∼505 million years old) Marjum Formation of Utah. These are the first described Cambrian jellyfish fossils to display exquisite preservation of soft part anatomy including detailed features of structures interpreted as trailing tentacles and subumbrellar and exumbrellar surfaces. If the interpretation of these preserved characters is correct, their presence is diagnostic of modern jellyfish taxa. These new discoveries may provide insight into the scope of cnidarian diversity shortly after the Cambrian radiation, and would reinforce the notion that important taxonomic components of the modern planktonic realm were in place by the Cambrian period.

Reassessment of the phylogenetic position of conulariids (?Ediacaran‐Triassic) within the subphylum medusozoa (phylum cnidaria)

Synopsis Fossil taxa of uncertain phylogenetic affinities can play a crucial role in the analysis of character evolution within major extant groups. Marques & Collins (2004) concluded that conulariids (?Ediacaran‐Triassic) are an extinct group of medusozoan cnidarians most closely related to Stauromedusae. However, only six of the 87 characters used by these authors can be observed in conulariid fossils. Rescoring the character states of conulariids in a conservative manner yields a new hypothesis for the phylogenetic position of conulariids, namely that they are the sister group of the scyphozoan order Coronatae rather than Stauromedusae, which is revealed as the earliest diverging lineage of Medusozoa. This new hypothesis also implies several different sequences of character evolution within Cnidaria. Specifically, the presence of a periderm completely covering the polyp in conulariids and coronates appears to be derived within Scyphozoa. Strobilation appears to be a synapomorphy uniting conulariids, Coronatae, Rhizostomeae and Semaeostomeae. This result supports the controversial interpretation of one exceptionally preserved conulariid that potentially shows that these animals produced ephyrae by strobilation. Finally, the pelagic adult medusa stage and the giant fibre nerve net appear to be features that are derived within Medusozoa.

Phylogenetics of Hydroidolina (Hydrozoa: Cnidaria)

Hydroidolina is a group of hydrozoans that includes Anthoathecata, Leptothecata and Siphonophorae. Previous phylogenetic analyses show strong support for Hydroidolina monophyly, but the relationships between and within its subgroups remain uncertain. In an effort to further clarify hydroidolinan relationships, we performed phylogenetic analyses on 97 hydroidolinan taxa, using DNA sequences from partial mitochondrial 16S rDNA, nearly complete nuclear 18S rDNA and nearly complete nuclear 28S rDNA. Our findings are consistent with previous analyses that support monophyly of Siphonophorae and Leptothecata and do not support monophyly of Anthoathecata nor its component subgroups, Filifera and Capitata. Instead, within Anthoathecata, we find support for four separate filiferan clades and two separate capitate clades (Aplanulata and Capitata sensu stricto ). Our data however, lack any substantive support for discerning relationships between these eight distinct hydroidolinan clades.

Effects of Bacteria on Artemia franciscana Cultured in Different Gnotobiotic Environments

ABSTRACT The use of probiotics is receiving considerable attention as an alternative approach to control microbiota in aquaculture farms, especially in hatching facilities. However, application with consistent results is hampered by insufficient information on their modes of action. To investigate whether dead bacteria (allowing investigation of their nutritional effect) or live bacteria (allowing evaluation of their probiotic effect) have any beneficial effect towards Artemia franciscana and, subsequently, if live bacteria have probiotic effects beyond the effects observed with dead bacteria, a model system was employed using gnotobiotic Artemia as a test organism. Nauplii were cultured in the presence of 10 bacterial strains combined with four different major axenic live feeds (two strains of Saccharomyces cerevisiae and two strains of Dunaliella tertiolecta) differing in their nutritional values. In combination with poor- and medium-quality live feeds, dead bacteria exerted a strong effect on Artemia survival but a rather weak or no effect on individual length and constituted a maximum of only 5.9% of the total ash-free dry weight supplied. These effects were reduced or even disappeared when medium- to good-quality major feed sources were used, possibly due to improvements in the health status of Artemia. Some probiotic bacteria, such as GR 8 (Cytophaga spp.), improved (not always significantly) the performance of nauplii beyond the effect observed with dead bacteria, independently of the feed supplied. The present approach can be an excellent system to study the exact mode of action of bacteria, especially if combined with challenge tests or other types of analysis (e.g., transcriptome and proteonomic analysis).

Checklist of the Cnidaria Medusozoa of Brazil

Uma lista dos Cnidaria Medusozoa marinhos do Brasil foi composta a partir de registros de ocorrencia disponiveis na literatura. Ate o momento, ha um total de 373 especies registradas para o Brazil: 347 de Hydrozoa, 3 de Cubozoa e 23 de Scyphozoa.

Proteomic characterisation of toxins isolated from nematocysts of the South Atlantic jellyfish Olindias sambaquiensis

Surprisingly little is known of the toxic arsenal of cnidarian nematocysts compared to other venomous animals. Here we investigate the toxins of nematocysts isolated from the jellyfish Olindias sambaquiensis. A total of 29 unique ms/ms events were annotated as potential toxins homologous to the toxic proteins from diverse animal phyla, including cone-snails, snakes, spiders, scorpions, wasp, bee, parasitic worm and other Cnidaria. Biological activities of these potential toxins include cytolysins, neurotoxins, phospholipases and toxic peptidases. The presence of several toxic enzymes is intriguing, such as sphingomyelin phosphodiesterase B (SMase B) that has only been described in certain spider venoms, and a prepro-haystatin P-IIId snake venom metalloproteinase (SVMP) that activates coagulation factor X, which is very rare even in snake venoms. Our annotation reveals sequence orthologs to many representatives of the most important superfamilies of peptide venoms suggesting that their origins in higher organisms arise from deep eumetazoan innovations. Accordingly, cnidarian venoms may possess unique biological properties that might generate new leads in the discovery of novel pharmacologically active drugs.

The costs of describing the entire animal kingdom

In the otherwise excellent special issue of Trends inEcology and Evolution on long-term ecological research(TREE 25(10),2010), none of the contributors mentionedthe importance of natural history collections (NHCs) assources of data that can strongly complement past andongoing survey data. Whereas very few field surveyshave operated for more than a few decades, NHCs,conserved in museums and other institutions, comprisesamples of the Earth’s biota typically extending backwell into the nineteenth century and, in some cases,before this time. They therefore span the period ofaccelerated anthropogenic habitat destruction, climatewarming and ocean acidification, in many cases reflect-ing baseline conditions before the major impact of thesefactors.Natural history collections (NHCs) provide a rich source ofdata at thetaxic andcommunitylevels, andcan contributeto a wide range of studies [1]. These include biogeographicrange changes (spatial and/or altitudinal) [2]; phenologicalshifts (e.g. in flowering time [3]); and evolutionary change(genetic or morphological). They can also (if unsorted bulksamples are available) document changes in communitycomposition in the recent past (historical samples) andthrough deeper geological time (fossil samples). In addi-tion, museum specimens provide source material for arange of genetic, biochemical, isotopic and trace-elementstudies into organismal responses to environmentalchange (e.g. use of preserved feathers to trace changesin the diet and migration of birds [4]).NHCs comprise not only the products of opportunisticcollecting but are also (particularly in the major nationalmuseums and institutions) repositories of major surveys.The Natural History Museum (NHM) in London, UK, forexample, houses thousands of jars from the Discovery andChallenger marine expeditions that were collected at hun-dredsofstationsinthelatenineteenthandearlytwentiethcenturies. These samples provide an outstanding (andlargely untapped) resource for comparison with modernsurveydata.Collectionsmadewithacoherentandsystem-aticsamplingstrategyareinevitablymorelikelytoprovideresearch-quality material than ad-hoc or point samples.Unknown or inconsistent sampling strategy can bea problem, but this is not unique to museum collections;methodological changes or gaps also occur in long-termfielddatasetsandneedtobeaccommodatedintheanalysis[5].Of particular value, a proportion of historical and mod-ern collections comprise time-series (i.e. the same localityand/ortaxonhasbeenregularlycollectedovermanyyears).For exploration of long-term ecological responses, NHC-derived datasets can be integrated with local or regionalclimatic and other records, such as the Central EnglandTemperature Record, which is continuous back to 1659(http://hadobs.metoffice.com/hadcet/). Time-series throughmuch longer intervals of the Earth’s history are availablein palaeontological collections.Central to all such endeavours is the availability ofaccurate provenance data on the NHC material. Museumspecimenlabelsandregistersideallyindicatetheplaceanddate of collection. However, even when such information isavailable, considerable work may be required to make itaccessible for research, for example, by georeferencing(establishing the latitude and longitude of) obscureplace-names, and entering all records onto an electronicdatabase [2]. Collaboration between researchers and col-lectionsmanagersisessentialand,ifresourcesforcurationare limited, researchers should consider including collec-tions databasing into their funding proposals.Curators and collections managers, for their part, havea vital part to play in this process. Policies crucial forenabling collections-based research include:Maintaining unpicked sub-samples of bulk-sampledcollections.Prioritising databasing of collections with researchpotential.Facilitating responsible destructive sampling. Thisincludes retaining duplicate imperfect specimens forthe purpose, and simplifying paperwork.Maintaining and extending time-series through con-tinued collecting, and collaboration with modernsurveys to enable acquisition of voucher specimens.Collaboratingwithothermuseumstocreate,ultimately,an integrated global resource (e.g. through the SciCollinitiative: http://www.scicoll.org/).In a recent example embodying many of these aspects,the NHM, in a project funded by the UK Government,compiled a database on the extent of NHM and otherBritish collections potentially suitable for investigatingthe effects of ocean acidification on marine biocalcifyingorganisms. The results of the project, summarizingsamplesaccumulatedgloballyover200 years,are available

Molecules Clarify a Cnidarian Life Cycle – The “Hydrozoan” Microhydrula limopsicola Is an Early Life Stage of the Staurozoan Haliclystus antarcticus

Background Life cycles of medusozoan cnidarians vary widely, and have been difficult to document, especially in the most recently proposed class Staurozoa. However, molecular data can be a useful tool to elucidate medusozoan life cycles by tying together different life history stages. Methodology/Principal Findings Genetic data from fast-evolving molecular markers (mitochondrial 16S, nuclear ITS1, and nuclear ITS2) show that animals that were presumed to be a hydrozoan, Microhydrula limopsicola (Limnomedusae, Microhydrulidae), are actually an early stage of the life cycle of the staurozoan Haliclystus antarcticus (Stauromedusae, Lucernariidae). Conclusions/Significance Similarity between the haplotypes of three markers of Microhydrula limopsicola and Haliclystus antarcticus settles the identity of these taxa, expanding our understanding of the staurozoan life cycle, which was thought to be more straightforward and simple. A synthetic discussion of prior observations makes sense of the morphological, histological and behavioral similarities/congruence between Microhydrula and Haliclystus. The consequences are likely to be replicated in other medusozoan groups. For instance we hypothesize that other species of Microhydrulidae are likely to represent life stages of other species of Staurozoa.

Synopsis of knowledge on Cnidaria Medusozoa from Brazil

Uma sinopse sobre o conhecimento dos Medusozoa (Cnidaria) da costa brasileira e apresentada. Este estudo e baseado em uma lista com todos os registros de Medusozoa para o Brasil, incluindo informacoes sobre a distribuicao das especies e suas fases (polipo ou medusa). O numero de especies de Medusozoa registradas para o Brasil ate o momento e 377 (205 generos e 82 familias), com 348 especies de hidrozoarios, 22 de cifozoarios, 3 de cubozoarios e 1 de estaurozoario. Analises geografica e historica tambem foram conduzidas. A analise geografica mostra claramente a ausencia de conhecimento sobre a biodiversidade da costa norte bem como de parte da costa nordeste do pais. Embora a costa sudeste seja a melhor conhecida em termos de numeros de especies e representantes de taxons supragenericos registrados, ha em geral ausencia de conhecimento sobre ambientes diferentes das aguas rasas, um padrao tambem observado para as outras regioes. Historicamente, o crescimento dos registros de hidrozoarios iniciou-se apos a decada de 1940, com um aumento na ultima decada; os estudos com coronados estao todos concentrados na ultima decada mas, em geral, outros grupos mostram um acumulo lento e gradual nos registros de especies. Linhas gerais e politicas para o estudo da biodiversidade dos Medusozoa sao sugeridas.