Multiple Modes of Adaptation: Regulatory and Structural Evolution in a Small Heat Shock Protein Gene.

Thermal tolerance is a key determinant of species distribution. Despite much study, the genetic basis of adaptive evolution of thermal tolerance, including the relative contributions of transcriptional regulation versus protein evolution, remains unclear. Populations of the intertidal copepod Tigriopus californicus are adapted to local thermal regimes across their broad geographic range.

Functional diversification of sea urchin ABCC1 (MRP1) by alternative splicing.

The multidrug resistance protein (MRP) family encodes a diverse repertoire of ATP-binding cassette (ABC) transporters with multiple roles in development, disease, and homeostasis. Understanding MRP evolution is central to unraveling their roles in these diverse processes. Sea urchins occupy an important phylogenetic position for understanding the evolution of vertebrate proteins and have been an important invertebrate model system for study of ABC transporters.

ABCC5 is required for cAMP-mediated hindgut invagination in sea urchin embryos.

ATP-binding cassette (ABC) transporters are evolutionarily conserved proteins that pump diverse substrates across membranes. Many are known to efflux signaling molecules and are extensively expressed during development. However, the role of transporters in moving extracellular signals that regulate embryogenesis is largely unexplored.

Localization and substrate selectivity of sea urchin multidrug (MDR) efflux transporters.

In this study, we cloned, expressed and functionally characterized Stronglycentrotus purpuratus (Sp) ATP-binding cassette (ABC) transporters. This screen identified three multidrug resistance (MDR) transporters with functional homology to the major types of MDR transporters found in humans. When overexpressed in embryos, the apical transporters Sp-ABCB1a, ABCB4a, and ABCG2a can account for as much as 87% of the observed efflux activity, providing a robust assay for their substrate selectivity.

Investigating the molecular basis of local adaptation to thermal stress: population differences in gene expression across the transcriptome of the copepod Tigriopus californicus.

Background: Geographic variation in the thermal environment impacts a broad range of biochemical and physiological processes and can be a major selective force leading to local population adaptation. In the intertidal copepod Tigriopus californicus, populations along the coast of California show differences in thermal tolerance that are consistent with adaptation, i.e.

A gene-based SNP resource and linkage map for the copepod Tigriopus californicus.

Background: As yet, few genomic resources have been developed in crustaceans. This lack is particularly evident in Copepoda, given the extraordinary numerical abundance, and taxonomic and ecological diversity of this group. Tigriopus californicus is ideally suited to serve as a genetic model copepod and has been the subject of extensive work in environmental stress and reproductive isolation.

Interpopulation patterns of divergence and selection across the transcriptome of the copepod Tigriopus californicus.

The accumulation of genetic incompatibilities between isolated populations is thought to lead to the evolution of intrinsic postzygotic isolation. The molecular basis for these mechanisms, however, remains poorly understood. The intertidal copepod Tigriopus californicus provides unique opportunities for addressing mechanistic questions regarding the early stages of speciation; hybrids between highly divergent populations are fertile and viable, but exhibit reduced fitness at the F(2) or later generations.

Bindin genes of the Pacific oyster Crassostrea gigas.

When Crassostrea gigas oyster sperm acrosome react a ring of bindin protein is exposed that bonds the sperm to the egg vitelline envelope. The putative functional unit of bindin is a fucose lectin (F-lectin) domain that is structurally conserved among phyla. There is only one bindin gene in C.

Oyster sperm bindin is a combinatorial fucose lectin with remarkable intra-species diversity.

Sperm of the oyster, Crassostrea gigas, have ring-shaped acrosomes that, after exocytosis, bind the sperm to the egg vitelline layer. Isolated acrosomal rings contain proteins of various sizes: 35-, 48-, 63-, 75- and 88-kDa. These proteins, called bindins, have identical 24-residue signal peptides and conserved 97-residue N-terminal sequences, and they differ in mass because of the presence of between 1 and 5 tandemly repeated 134-residue fucose-binding lectin (F-lectin) domains.

Molecular characterization of a novel intracellular ADP-ribosyl cyclase.

Background: ADP-ribosyl cyclases are remarkable enzymes capable of catalyzing multiple reactions including the synthesis of the novel and potent intracellular calcium mobilizing messengers, cyclic ADP-ribose and NAADP. Not all ADP-ribosyl cyclases however have been characterized at the molecular level. Moreover, those that have are located predominately at the outer cell surface and thus away from their cytosolic substrates.

The 10 sea urchin receptor for egg jelly proteins (SpREJ) are members of the polycystic kidney disease-1 (PKD1) family.

Background: Mutations in the human polycystic kidney disease-1 (hPKD1) gene result in ~85% of cases of autosomal dominant polycystic kidney disease, the most frequent human monogenic disease. PKD1 proteins are large multidomain proteins involved in a variety of signal transduction mechanisms. Obtaining more information about members of the PKD1 family will help to clarify their functions.

Particulate and soluble adenylyl cyclases participate in the sperm acrosome reaction.

cAMP is important in sea urchin sperm signaling, yet the molecular nature of the adenylyl cyclases (ACs) involved remained unknown. These cells were recently shown to contain an ortholog of the mammalian soluble adenylyl cyclase (sAC). Here, we show that sAC is present in the sperm head and as in mammals is stimulated by bicarbonate.

Diversity of olfactomedin proteins in the sea urchin.

Olfactomedin (OLF) domain proteins maintain extracellular protein-protein interactions in diverse phyla. Only one OLF family member, amassin-1, has been described from the sea urchin Strongylocentrotus purpuratus, a basal invertebrate deuterostome. Amassin-1 mediates intercellular adhesion of coelomocytes (immunocytes).

The genome of the sea urchin Strongylocentrotus purpuratus.

We report the sequence and analysis of the 814-megabase genome of the sea urchin Strongylocentrotus purpuratus, a model for developmental and systems biology. The sequencing strategy combined whole-genome shotgun and bacterial artificial chromosome (BAC) sequences. This use of BAC clones, aided by a pooling strategy, overcame difficulties associated with high heterozygosity of the genome.

A functional genomic and proteomic perspective of sea urchin calcium signaling and egg activation.

The sea urchin egg has a rich history of contributions to our understanding of fundamental questions of egg activation at fertilization. Within seconds of sperm-egg interaction, calcium is released from the egg endoplasmic reticulum, launching the zygote into the mitotic cell cycle and the developmental program. The sequence of the Strongylocentrotus purpuratus genome offers unique opportunities to apply functional genomic and proteomic approaches to investigate the repertoire and regulation of Ca(2+) signaling and homeostasis modules present in the egg and zygote.

A sodium bicarbonate transporter from sea urchin spermatozoa.

Bicarbonate (HCO3-) transporters play crucial roles in cell-signaling pathways and are essential for cell viability. Here we describe the first cloning and localization of a HCO3- transporter from sperm of the sea urchin, Strongylocentrotus purpuratus. The deduced protein is 1214 amino acids and has a calculated molecular mass of 135 kDa.

A perforin-like protein from a marine mollusk.

Abalone (gastropod mollusks) express a protein, abMpeg1, which is a homolog of two mammalian proteins that share homology with mammalian perforin, a cytolytic and immune-regulatory protein of lymphocytes. One of the mammalian proteins, Mpeg1, is expressed in mature macrophage and prion-infected mouse brains, while the other, Epcs50, is expressed in ectoplacental cone cells of the invading placenta. Although the functions of these three proteins remain unknown, their structural similarity to mammalian perforin suggests that they may be involved in cell killing, the inflammatory response or tissue invasion.

A third sea urchin sperm receptor for egg jelly module protein, suREJ2, concentrates in the plasma membrane over the sperm mitochondrion.

Sea urchin spermatozoa are model cells for studying signal transduction events underlying flagellar motility and the acrosome reaction. We previously described the sea urchin sperm receptor for egg jelly 1 (suREJ1) which consists of 1450 amino acids, has one transmembrane segment and binds to the fucose sulfate polymer of egg jelly to induce the sperm acrosome reaction. We also cloned suREJ3 which consists of 2681 amino acids and has 11 putative transmembrane segments.

Polycystin-2 associates with the polycystin-1 homolog, suREJ3, and localizes to the acrosomal region of sea urchin spermatozoa.

Polycystin-2, the protein mutated in type 2 autosomal dominant polycystic kidney disease, is an integral transmembrane protein with nonselective cation channel activity. Here we report on the sea urchin sperm homolog of polycystin-2 (suPC2). Like other polycystin-2 family members, suPC2 is a six-pass transmembrane protein containing C-terminal cytoplasmic EF hand and coiled-coil domains.

Full-length sequence of VERL, the egg vitelline envelope receptor for abalone sperm lysin.

Abalone sperm use 16 kDa lysin to create a hole in the egg vitelline envelope (VE) by a species-specific, nonenzymatic mechanism. To create the hole, lysin binds tightly to VERL (the VE receptor for lysin), a giant, unbranched glycoprotein comprising 30% of the VE. Binding of lysin to VERL causes the VERL molecules to lose cohesion and splay apart creating the hole.

suREJ3, a polycystin-1 protein, is cleaved at the GPS domain and localizes to the acrosomal region of sea urchin sperm.

The sea urchin sperm acrosome reaction (AR) is a prerequisite for sperm-egg fusion. This report identifies sea urchin sperm receptor for egg jelly-3 (suREJ3) as a new member of the polycystin-1 family (the protein mutated in autosomal dominant polycystic kidney disease). suREJ3 is a multidomain, 2,681-amino acid, heavily glycosylated orphan receptor with 11 putative transmembrane segments (TMS) that localize to the plasma membrane covering the sperm acrosomal vesicle.