Histology and transcriptomic analyses of barnacles with different base materials and habitats shed lights on the duplication and chemical diversification of barnacle cement proteins

Background Barnacles are sessile crustaceans that attach to underwater surfaces using barnacle cement proteins. Barnacles have a calcareous or chitinous membranous base, and their substratum varies from biotic (e.g. corals/sponges) to abiotic surfaces. In this study, we tested the hypothesis that the cement protein (CP) composition and chemical properties of different species vary according to the attachment substrate and/or the basal structure. We examined the histological structure of cement glands and explored the variations in cement protein homologs of 12 barnacle species with different attachment habitats and base materials. Results Cement gland cells in the rocky shore barnacles Tetraclita japonica formosana and Amphibalanus amphitrite are eosinophilic, while others are basophilic. Transcriptome analyses recovered CP homologs from all species except the scleractinian coral barnacle Galkinia sp. A phylogenomic analysis based on sequences of CP homologs did not reflect a clear phylogenetic pattern in attachment substrates. In some species, certain CPs have a remarkable number of paralogous sequences, suggesting that major duplication events occurred in CP genes. The examined CPs across taxa show consistent bias toward particular sets of amino acid. However, the predicted isoelectric point (pI) and hydropathy are highly divergent. In some species, conserved regions are highly repetitive. Conclusions Instead of developing specific cement proteins for different attachment substrata, barnacles attached to different substrata rely on a highly duplicated cementation genetic toolkit to generate paralogous CP sequences with diverse chemical and biochemical properties. This general CP cocktail might be the key genetic feature enabling barnacles to adapt to a wide variety of substrata.

A new opilioacarid species (Parasitiformes: Opilioacarida) from Crete (Greece) with notes on its karyotype

A new species of opilioacarid mite, Opilioacarus thaleri n. sp., is described from mid-level elevation close to the seashore in Crete (Greece). It was found on moister sites, under stones or inside stone accumulations in phrygana vegetation. The peak of activity was found to be in early May. The diagnostic morphological characters include 7–8 eugenital setae (female), 5/7 setae on each sclerite at pregenital and genital areas, 11 setae on genital area (male), anterior dorsal shield with two pairs of eyes and 60–70 stout, ribbed setae, 5 (female) or 6 (male) leaf setae plus one pectinate seta on the palp tarsus, and the "simple" type of ovipositor with two pairs of glands, a pair of ducts plus a basal structure. The female karyotype comprises 16 monocentric chromosomes, predominantly with acrocentric morphology. Comparison with data of the ixodids and mesostigmatids indicates that a low number of chromosomes and predomination of acrocentric chromosomes could be plesiomorphies of the parasitiform mites.

The type III secretion injectisome, a complex nanomachine for intracellular ‘toxin’ delivery

The type III secretion injectisome is a nanomachine that delivers bacterial proteins into the cytosol of eukaryotic target cells. It consists of a cylindrical basal structure spanning the two bacterial membranes and the peptidoglycan, connected to a hollow needle, eventually followed by a filament (animal pathogens) or to a long pilus (plant pathogens). Export employs a type III pathway. During assembly, all the protein subunits of external elements are sequentially exported by the basal structure itself, implying that the export apparatus can switch its substrate specificity over time. The length of the needle is controlled by a protein that it also secreted during assembly and presumably acts as a molecular ruler.

<i>Navilithus altivelum</i>: a remarkable new genus and species of deep photic coccolithophores

A very distinctive new deep-photic coccolithophore is described from the NE Indian Ocean. The new species is trimorphic with: 200–300 body coccoliths bearing low spines attached by narrow stems to a basal narrow-rimmed placolith structure; up to 18 circum-flagellar coccoliths with tall sail-like spines; and up to 22 coccoliths with moderately elevated spines occurring both around the circum-flagellar coccoliths and antapically. These features make the coccolithophore unique and require placement in a new species and genus. The basal structure, however, shows similarities to a recently recognized group of narrow-rimmed placoliths. Hence, the new coccolithophore provides some support for this grouping as a significant addition to our understanding of coccolithophore biodiversity, and potentially an explanation for a set of anomalous molecular genetic results. In addition the new taxon provides further evidence that the deep-photic coccolithophore community is more diverse than has been assumed.

Systematics of the Acanthoparyphinae (Trilobita), by species from the Silurian of Arctic Canada

Cladistic analysis of the trilobite subfamily Acanthoparyphinae Whittington and Evitt, 1954, yields an explicit hypothesis of relationship for the group. All Silurian species together form a robustly supported monophylum including the genera Hyrokybe Lane, 1972, Parayoungia Chatterton and Perry, 1984, and Youngia Lindström, 1885. Sister to this is the Ordovician type species of Acanthoparypha Whittington and Evitt, 1954. Remaining species that have historically been assigned to either Acanthoparypha or Pandaspinapyga Esker and Levin, 1964, form a rather labile paraphylum. Nevertheless, the entire group thus identified is definitely monophyletic, and supported by several prominent synapomorphic character-states.The basal structure and basal node of the subfamily are more difficult to assess. The relationships of the genera Hammannopyge Přibyl, Vaněk, and Pek, 1985, Holia Bradley, 1930, and Nieszkowskia Schmidt, 1881, need to be addressed within the wider context of the family as a whole. The traditional assignment of Holia to the acanthoparyphines is followed.Wenlock acanthoparyphines from the Cape Phillips Formation of the central Canadian Arctic islands include several species of Hyrokybe and Parayoungia. They are similar to, and in one case conspecific with, coeval forms to the southwest in the southern Mackenzie Mountains.Five species are new: Holia glabra, Hyrokybe lightfooti, Hyrokybe youngi, Hyrokybe mitchellae, and Parayoungia mclaughlini. At least four other potentially new species are reported in open nomenclature.

Shared versus derived characters in the pore-system of <i>Loxoconcha</i> (Ostracoda, Crustacea)

Ontogenetic development of the pore-systems of two species of Loxoconcha, phytal L. japonica and bottom-dwelling L. uranouchiensis, were examined. Adult pore-systems differ between the two species in number and distribution of “smooth”-type bristles, the basal structure of “twisted”-type bristles and the existence of microhairs. These specific features start to differentiate after the A-2 or A-3 juvenile stage, a fairly late moulting stage, and continue to differentiate until the adult stage. These characters are identified as lower phylogenetic ones based on the ontogeny-phylogeny relationship. The result is consistent with the estimate that the characters were regarded as adaptive and specialized through the consideration of their function to the respective habitats. The mode of increase of the two types of pore-systems was revealed. The “twisted”-type bristle, whose number is common between the two species at all stages, reaches the final number, except for one, at the A-3 juvenile stage. In contrast, the “smooth”-type bristle continues to increase in number until adult stage, and, as mentioned above, the specific differences become more obvious as the moulting stages advance. This type of pore-system is valuable for specific differentiation. Two types of pore-system that differ from each other in the pattern of increase were recognized in other ostracod taxa. The two types of pore-systems have different significance in ostracod taxonomy and the recognition of the type is indispensable for future taxonomy.

An SEM study of the structure and classification of the leaf trichomes in the genus Lycopersicon (tomato)

Species of the genus Lycopersicon characteristically possess pubescent leaves; seven types of trichomes were described in 1943, based on light microscopic observations. Recently, there has been renewed interest in trichomes since the presence and density of certain types of trichomes has been related to insect resistance in some species and/or varieties of tomato.Trichomes can be divided into two functional categories, depending on whether the tips are pointed or glandular. Within each of these categories, trichome types have been further differentiated according to the length and number of cells in the stalk and the complexity of the basal structure. Three non-glandular and four glandular types have been described in Lycopersicon. Our SEM observations of tomato leaf surfaces suggest that there may be a need to re-evaluate Luckwill's classification of trichome types.

Bacterial Flagella

Movement of bacterial cells is accomplished through the action of flagella, organelles consisting of three morphologically distinct portions, a spiral tubular filament [(f)n] which constitutes over 90% of the organelle, an extracellular hook, and a basal structure, which is intimately associated with the cell surface. The spiral (f)n is constructed of polarly oriented ovoid subunits of flagellin (f) apparently arranged in a helical fashion. Flagellin is a unique protein in that it contains no or only few residues of cys/2, trp, pro, his, or tyr, and is capable of forming normal (f)n by self-assembly. In cells of Bacillus pumilus 101 (f)n contains two types of f(fA,fB) in a ratio of 7:3. Amino acid analyses and examination of the tryptic peptides from purified fA and fB indicate that both molecules are much alike. Both fA and fB are synthesized by the same cell and are located within the same flagellum, since both anti-fA and anti-fB sera, which react specifically with synthetic (fA)n or (fB)n can be seen to coat native (f)n of all cells and the entire length of each (f)n when examined electron microscopically.

The immunochemistry of Shigella flexneri O-antigens. The biochemical basis of smooth to rough mutation

1. Smooth to rough mutation has the same biochemical basis in Shigella as in Salmonella. It is the result of enzyme defects blocking the incorporation of the O-specific side chains that characterize the smooth lipopolysaccharide with the consequent exposure of the underlying basal structures that determine ‘rough’-specificity. 2. The Shigella flexneri basal structure resembles its Salmonella analogue in that it has the same qualitative sugar composition, and enzyme defects in its biosynthetic pathway give rise to ‘rough’-lipopolysaccharides that are indistinguishable from those of Salmonella chemotypes Ra, Rb, Rc and Rd. However, the Salmonella and Shigella basal structures are not identical as judged by quantitative analysis and the absence of serological cross-reaction. 3. The Sh. flexneri basal structure side chain has been isolated and characterized as an α-N-acetylglucosaminyl-(1→4)-galactosyl-(1→3)-glucose sequence with α-glucosyl radicals substituted on the 3- and 4-positions of the galactose and glucose respectively. The different sugar types in this side chain are incorporated into the growing molecule in the same order as in Salmonella, which explains why the enzyme defects associated with smooth to rough mutation produce the same series of R-chemotypes from both genera. The terminal α-glucosyl and α-N-acetylglucosaminyl-(1→4)-galactosyl residues of the Sh. flexneri basal structure are sufficiently different from the terminal α-galactosyl and α-N-acetylglucosaminylglucosyl residues of the Salmonella analogue that they offer an explanation for the absence of serological cross-reaction between these two basal structures.