Endogenous opioids in marine invertebrates

A study of the presence of opioids in invertebrates was carried out on 11 species of marine organisms, ranging from sponges to tunicates. Delipidized acid-acetone extracts from whole organisms or dissected organs were assayed by receptor binding assays and radioimmuno assays. The extracts from all species tested were found to contain substances capable of competing in both assays with opioid peptides.     

Speciation genes in free-spawning marine invertebrates

Research on speciation of marine organisms has lagged behind that of terrestrial ones, but the study of the evolution of molecules involved in the adhesion of gametes in free-spawning invertebrates is an exception. Here I review the function, species-specificity, and molecular variation of loci coding for bindin in sea urchins, lysin in abalone and their egg receptors, in an effort to assess the degree to which they contribute to the emergence of reproductive isolation during the speciation process. Bindin is a protein that mediates binding of the sperm to the vitelline envelope (VE) of the egg and the fusion of the gametes' membranes, whereas lysin is a protein involved only in binding to the VE. Both of these molecules are important in species recognition by the gametes, but they rarely constitute absolute blocks to interspecific hybridization. Intraspecific polymorphism is high in bindin, but low in lysin. Polymorphism in bindin is maintained by frequency-dependent selection due to sexual conflict arising from the danger of polyspermy under high densities of sperm. Monomorphism in lysin is the result of purifying selection arising from the need for species recognition. Interspecific divergence in lysin is due to strong positive selection, and the same is true for bindin of four out of seven genera of sea urchins studied to date. The differences between the sea urchin genera in the strength of selection can only partially be explained by the hypothesis of reinforcement. The egg receptor for lysin (VERL) is a glycoprotein with 22 repeats, 20 of which have evolved neutrally and homogenized by concerted evolution, whereas the first two repeats are under positive selection. Selection on lysin has been generated by the need to track changes in VERL, permitted by the redundant structure of this molecule. Both lysin and bindin are important in reproductive isolation, probably had a role in speciation, but it is hard to determine whether they meet the strictest criteria of "speciation loci," defined as genes whose differentiation has caused speciation.     

Antimicrobial activity in sub-Arctic marine invertebrates

In the marine environment, any living or non-living surface is exposed to bacterial colonization. Many invertebrate species in temperate, tropical and Antarctic regions have demonstrated chemical defences against the formation of microbial films. In the present study, the antimicrobial activity of sub-Arctic invertebrates was investigated for the first time. Crude extracts of abundant invertebrates belonging to several taxonomic groups were tested for their inhibitory effects on the growth of five sympatric phylogenetically diverse bacterial strains. Six out of 18 (33%) crude extracts inhibited bacterial growth at natural extract concentrations. The crude extract of the sponge Haliclona viscosa inhibited growth of all five bacterial strains, suggesting the presence of metabolites with broad-spectrum activity. Three active compounds were isolated from H. viscosa having antibacterial properties similar to those of the crude extract. Our data indicate that antibacterial secondary metabolites are present in sub-Arctic marine invertebrates but are less abundant than in temperate, tropical or Antarctic species.     

Carbohydrate-binding proteins of marine invertebrates

The information on the carbohydrate specificity and molecular organization of some carbohydrate-binding proteins (lectins) of marine invertebrates is reported. Antiviral activity of some of the lectins against human immunodeficiency virus has been studied. Lectins of marine invertebrates are promising tools for studying natural glycoconjugates and cell effectors in vitro.     

Microwave fixation of marine invertebrates

Marine invertebrates may be rapidly fixed for histological examination using microwave irradiation generated by household microwave ovens. Ten-second irradiation of whole intact clams gave tissue fixation equal or superior to standard procedures using formaldehyde solutions and eliminated the need for that hazardous chemical. We suggest that invertebrates can be fixed while relaxed in sea-water baths, without having to remove or open the shell, and that invertebrates in bottom sediment cores also may be fixed in situ without being disturbed.     

Viral diseases of marine invertebrates

Approximately 40 viruses are known from marine sponges; turbellarian and monogenetic flatworms; cephalopod, bivalve, and gastropod mollusks; nereid polychaetes; and isopod and decapod crustaceans. Most of the viruses can be tentatively assigned to the Herpesviridae, Baculoviridae, Iridoviridae, Adenoviridae, Papovaviridae, Reoviridae, Birnaviridae, Bunyaviridae, Rhabdoviridae, and Picornaviridae. Viruslike particles found in oysters might be representatives of the Togaviridae and Retroviridae. Enveloped single-stranded RNA viruses from crustaceans have developmental and morphological characteristics intermediate between families, and some show evidence of relationships to the Paramyxoviridae as well as the Bunyaviridae or Rhabdoviridae. Certain small viruses of shrimp cannot be assigned, even tentatively, to a particular family. Some viruses cause disease in wild and captive hosts, others are associated with disease states but may not be primary instigators, and many occur in apparently normal animals. The frequency of viral disease in natural populations of marine invertebrates is unknown. Several viruses that cause disease in captive animals, with or without experimental intervention, have also been found in diseased wild hosts, including herpeslike viruses of crabs and oysters, iridovirus of octopus, and reolike and bunyalike viruses of crabs. Iridolike viruses have been implicated in massive mortalities of cultured oysters. Baculoviruses, and IHHN virus, which is of uncertain affinities, cause economically damaging diseases in cultured penaeid shrimp. Double or multiple viral infection is common in crabs. For example, a reolike virus and associated rhabdolike virus act synergistically to cause paralytic and fatal disease inCallinectes sapidus. Information on host range, most susceptible stage, and viral latency is available only for viruses of shrimp. One baculovirus attacks five species of New World penaeid shrimp. IHHN virus infects three species ofPenaeus and causes catastrophic mortalities inP. stylirostris, but usually exhibits only inapparent infection inP. vannamei. Some shrimp viruses apparently are latent in larvae, causing disease only when shrimp have reached the postlarval or juvenile stages. Others are equally or more pathogenic in larvae. Studies of shrimp viruses and iridovirus-associated disease in cultured oysters point up the need for rapid and accurate diagnostic methods. Until appropriate cell cultures from marine invertebrates are devised, the viral identifications necessary for understanding of epizootiology, rapid containment of epizootics in cultured animals, and decisions regarding introductions of exotic species will be difficult or impossible.     

Carbohydrate-binding proteins of marine invertebrates

The information on the carbohydrate specificity and molecular organization of some carbohydrate-binding proteins (lectins) of marine invertebrates is reported. Antiviral activity of some of the lectins against human immunodeficiency virus has been studied. Lectins of marine invertebrates are promising tools for studying natural glycoconjugates and cell effectors in vitro.     

Superweak irradiation of marine invertebrates

The inhibitory analysis of the spontaneous ("ultraweak") and the luminole-induced chemiluminescence of marine Sycon sponges and Aiptasia actinias supports the idea that ultraweak photon emission of marine invertebrates is a consequence of Ca(2+)-dependent processes related to the interaction of reactive oxygen species with some endogenous fluorophore substrates.     

Endemism and evolution in Hawaiian marine invertebrates

Endemism in Hawaiian marine invertebrates is strikingly lower than that in Hawaiian terrestrial organisms. Although marine speciation has been widespread, there have been no major radiations or species swarms comparable with those commonly reported for terrestrial animals and plants; the marine fauna of the Hawaiian islands is differentiated from its Indo-west Pacific roots but has not diversified. The marked differences between marine and terrestrial endemism provide broad support for several models in which speciation depends on dispersal, colonization rate, or effective population size. Distinguishing among these models will require detailed information on the genetic structure and phylogenies of marine species both in the Hawaiian archipelago and throughout the Pacific.     

Functions of digestive diverticula in marine invertebrates

Summary The movement of labelled glucose along the digestive tract of two ascidian species, Sidnyum argus and Dendrodoa grossularia is compared. In Dendrodoa grossularia, glucose absorption takes place in all parts of the digestive tract except the oesophagus. Labelled glucose passes through the digestive tract in less than 12 h, and it accumulates in the pyloric ampullae in less than 3 days. In this species, the pyloric gland has more capacity to stock glucidic compounds than other tissues. Under normal feeding conditions, after five days, there is no transfer of labelled glucose to other tissues. Whatever the substances given to Sidnyum argus, its pyloric gland never accumulates labelled products.