The gene complement of the ancestral bilaterian - was Urbilateria a monster?

Expressed sequence tag analyses of the annelid Pomatoceros lamarckii, recently published in BMC Evolutionary Biology, are consistent with less extensive gene loss in the Lophotrochozoa than in the Ecdysozoa, but it would be premature to generalize about patterns of gene loss on the basis of the limited data available

Land Quality in an International Comparison: It's Importance in Measuring Productivity

The purpose of this paper has been to present quality-adjusted values for land in the United States and nine European countries using price and quantity data for 1990. Disregarding such differences in the quality-adjusted land input would generate biased estimates of the land input and thus of total factor productivity. Land quality adjustments could potentially be enhanced further with additional data on soil characteristics, climate, and other productivity-related characteristics.total factor productivity, hedonic techniques, soil stress, quality-adjusted land, Productivity Analysis,

A comparative view of early development in the corals Favia lizardensis, Ctenactis echinata, and Acropora millepora - morphology, transcriptome, and developmental gene expression

Fasta file of sequences of PCR products. (TXT 7 kb

Acropora - The most-studied coral genus

Over the last 2 million years, Acropora (the staghorn or elkhorn corals) has become the dominant genus of reef-building corals throughout the Indo-Pacific. Like other coral genera, Acropora taxonomy is presently undergoing comprehensive revision as a consequence of large-scale sequencing projects, which will substantially alter our understanding of the diversity and biogeography of the group. Acropora spp. are among the most stress sensitive of corals, and as a consequence, population declines are occurring worldwide, most significantly due to global warming. Despite diverse adult colony morphology, all members of the genus are similar at the tissue and polyp level and follow common reproductive and developmental programs. Some progress has recently been made in development of gene knockdown/knockout methods despite the long generation times of corals and need to rely on natural spawning events. Since 2018, the number of Acropora genome sequences available has increased dramatically, although taxonomic uncertainties complicate their evolutionary interpretation. Areas of particularly active research include settlement and the control of metamorphosis; metabolic interactions with both bacterial and eukaryotic symbionts, particularly Symbiodinaceae, and their gain and loss; and how best to restore reefs destroyed by storms and coral bleaching

Differential expression of three galaxin-related genes during settlement and metamorphosis in the scleractinian coral Acropora millepora

Background: The coral skeleton consists of CaCO3 deposited upon an organic matrix primarily as aragonite. Currently galaxin, from Galaxea fascicularis, is the only soluble protein component of the organic matrix that has been characterized from a coral. Three genes related to galaxin were identified in the coral Acropora millepora.\ud \ud Results: One of the Acropora genes (Amgalaxin) encodes a clear galaxin ortholog, while the others (Amgalaxin-like 1 and Amgalaxin-like 2) encode larger and more divergent proteins. All three proteins are predicted to be extracellular and share common structural features, most notably the presence of repetitive motifs containing dicysteine residues. In situ hybridization reveals distinct,\ud but partially overlapping, spatial expression of the genes in patterns consistent with distinct roles in calcification. Both of the Amgalaxin-like genes are expressed exclusively in the early stages of\ud calcification, while Amgalaxin continues to be expressed in the adult, consistent with the situation in the coral Galaxea.\ud \ud Conclusion: Comparisons with molluscs suggest functional convergence in the two groups; lustrin A/pearlin proteins may be the mollusc counterparts of galaxin, whereas the galaxin-like proteins combine characteristics of two distinct proteins involved in mollusc calcification. Database searches indicate that, although sequences with high similarity to the galaxins are restricted to the Scleractinia, more divergent members of this protein family are present in other cnidarians and some other metazoans. We suggest that ancestral galaxins may have been secondarily recruited to roles in calcification in the Triassic, when the Scleractinia first appeared. Understanding theevolution of the broader galaxin family will require wider sampling and expression analysis in a\ud range of cnidarians and other animals

Sox genes in the coral Acropora millepora: divergent expression patterns reflect differences in developmental mechanisms within the Anthozoa

Background: Sox genes encode transcription factors that function in a wide range of developmental processes across the animal kingdom. To better understand both the evolution of the Sox family and the roles of these genes in cnidarians, we are studying the Sox gene complement of the coral, Acropora millepora (Class Anthozoa).\ud \ud Results: Based on overall domain structures and HMG box sequences, the Acropora Sox genes considered here clearly fall into four of the five major Sox classes. AmSoxC is expressed in the ectoderm during development, in cells whose morphology is consistent with their assignment as sensory neurons. The expression pattern of the Nematostella ortholog of this gene is broadly similar to that of AmSoxC, but there are subtle differences – for example, expression begins significantly earlier in Acropora than in Nematostella. During gastrulation, AmSoxBb and AmSoxB1 transcripts are detected only in the presumptive ectoderm while AmSoxE1 transcription is restricted to the presumptive endoderm, suggesting that these Sox genes might play roles in germ layer specification. A third type B Sox gene, AmSoxBa, and a Sox F gene AmSoxF also have complex and specific expression patterns during early development. Each of these genes has a clear Nematostella ortholog, but in several cases the expression pattern observed in Acropora differs significantly from that reported in Nematostella.\ud \ud Conclusion: These differences in expression patterns between Acropora and Nematostella largely reflect fundamental differences in developmental processes, underscoring the diversity of mechanisms within the anthozoan Sub-Class Hexacorallia (Zoantharia)

Unexpected diversity of cnidarian integrins: expression during coral gastrulation

<p>Abstract</p> <p>Background</p> <p>Adhesion mediated through the integrin family of cell surface receptors is central to early development throughout the Metazoa, playing key roles in cell-extra cellular matrix adhesion and modulation of cadherin activity during the convergence and extension movements of gastrulation. It has been suggested that <it>Caenorhabditis elegans</it>, which has a single β and two α integrins, might reflect the ancestral integrin complement. Investigation of the integrin repertoire of anthozoan cnidarians such as the coral <it>Acropora millepora </it>is required to test this hypothesis and may provide insights into the original roles of these molecules.</p> <p>Results</p> <p>Two novel integrins were identified in <it>Acropora</it>. AmItgα1 shows features characteristic of α integrins lacking an I-domain, but phylogenetic analysis gives no clear indication of its likely binding specificity. AmItgβ2 lacks consensus cysteine residues at positions 8 and 9, but is otherwise a typical β integrin. In situ hybridization revealed that AmItgα1, AmItgβ1, and AmItgβ2 are expressed in the presumptive endoderm during gastrulation. A second anthozoan, the sea anemone <it>Nematostella vectensis</it>, has at least four β integrins, two resembling AmItgβ1 and two like AmItgβ2, and at least three α integrins, based on its genomic sequence.</p> <p>Conclusion</p> <p>In two respects, the cnidarian data do not fit expectations. First, the cnidarian integrin repertoire is more complex than predicted: at least two βs in <it>Acropora</it>, and at least three αs and four βs in <it>Nematostella</it>. Second, whereas the bilaterian αs resolve into well-supported groups corresponding to those specific for RGD-containing or laminin-type ligands, the known cnidarian αs are distinct from these. During early development in <it>Acropora</it>, the expression patterns of the three known integrins parallel those of amphibian and echinoderm integrins.</p

Microarray analysis identifies candidate genes for key roles in coral development

Background: Anthozoan cnidarians are amongst the simplest animals at the tissue level of organization, but are surprisingly complex and vertebrate-like in terms of gene repertoire. As major components of tropical reef ecosystems, the stony corals are anthozoans of particular ecological significance. To better understand the molecular bases of both cnidarian development in general and coral-specific processes such as skeletogenesis and symbiont acquisition, microarray analysis was carried out through the period of early development – when skeletogenesis is initiated, and symbionts are first acquired. Results: Of 5081 unique peptide coding genes, 1084 were differentially expressed (P ≤ 0.05) in comparisons between four different stages of coral development, spanning key developmental transitions. Genes of likely relevance to the processes of settlement, metamorphosis, calcification and interaction with symbionts were characterised further and their spatial expression patterns investigated using whole-mount in situ hybridization. Conclusion: This study is the first large-scale investigation of developmental gene expression for any cnidarian, and has provided candidate genes for key roles in many aspects of coral biology, including calcification, metamorphosis and symbiont uptake. One surprising finding is that some of these genes have clear counterparts in higher animals but are not present in the closely-related sea anemone Nematostella. Secondly, coral-specific processes (i.e. traits which distinguish corals from their close relatives) may be analogous to similar processes in distantly related organisms. This first large-scale application of microarray analysis demonstrates the potential of this approach for investigating many aspects of coral biology, including the effects of stress and disease.Lauretta C Grasso, John Maindonald, Stephen Rudd, David C Hayward, Robert Saint, David J Miller and Eldon E Bal

Analyses of corallimorpharian transcriptomes provide new perspectives on the evolution of calcification in the Scleractinia (corals)

Corallimorpharians (coral-like anemones) have a close phylogenetic relationship with scleractinians (hard corals) and can potentially provide novel perspectives on the evolution of biomineralization within the anthozoan subclass Hexacorallia. A survey of the transcriptomes of three representative corallimorpharians led to the identification of homologs of some skeletal organic matrix proteins (SOMPs) previously considered to be restricted to corals. Carbonic anhydrases (CAs), which are ubiquitous proteins involved in CO2 trafficking, are involved in both coral calcification and photosynthesis by endosymbiotic Symbiodinium (zooxanthellae). These multiple roles are assumed to place increased demands on the CA repertoire and have presumably driven the elaboration of the complex CA repertoires typical of corals (note that "corals" are defined here as reef-building Scleractinia). Comparison of the CA inventories of corallimorpharians with those of corals reveals that corals have specifically expanded the secreted and membrane-associated type CAs, whereas similar complexity is observed in the two groups with respect to other CA types. Comparison of the CA complement of the nonsymbiotic corallimorph Corynactis australis with that of Ricordea yuma, a corallimorph which normally hosts Symbiodinium, reveals similar numbers and distribution of CA types and suggests that an expansion of the CA repertoire has been necessary to enable calcification but may not be a requirement to enable symbiosis. Consistent with this idea, preliminary analysis suggests that the CA complexity of zooxanthellate and nonzooxanthellate sea anemones is similar. The comparisons above suggest that although there are relatively few new genes in the skeletal organic matrix of corals (which controls the skeleton deposition process), the evolution of calcification required an expanded repertoire of secreted and membrane- associated CAs

The innate immune repertoire in Cnidaria - ancestral complexity and stochastic gene loss

Analysis of genomic resources available for cnidarians revealed that several key components of the vertebrate innate immune repertoire are present in representatives of the basal cnidarian class Anthozoa, but are missing in Hydra, a member of the class Hydrozoa, indicating ancient origins for many components of the innate immune system