Localization of sequences regulating ancestral and acquired sites of esterase6 activity in Drosophila melanogaster

We have broadly defined the DNA regions regulating esterase6 activity in several life stages and tissue types of D. melanogaster using P- element-mediated transformation of constructs that contain the esterase6 coding region and deletions or substitutions in 5' or 3' flanking DNA. Hemolymph is a conserved ancestral site of EST6 activity in Drosophila and the primary sequences regulating its activity lie between -171 and -25 bp relative to the translation initiation site: deletion of these sequences decrease activity approximately 20-fold. Hemolymph activity is also modulated by four other DNA regions, three of which lie 5' and one of which lies 3' of the coding region. Of these, two have positive and two have negative effects, each of approximately twofold. Esterase6 activity is present also in two male reproductive tract tissues; the ejaculatory bulb, which is another ancestral activity site, and the ejaculatory duct, which is a recently acquired site within the melanogaster species subgroup. Activities in these tissues are at least in part independently regulated: activity in the ejaculatory bulb is conferred by sequences between -273 and -172 bp (threefold decrease when deleted), while activity in the ejaculatory duct is conferred by more distal sequences between -844 and -614 bp (fourfold decrease when deleted). The reproductive tract activity is further modulated by two additional DNA regions, one in 5' DNA (-613 to -284 bp; threefold decrease when deleted) and the other in 3' DNA (+1860 to +2731 bp; threefold decrease when deleted) that probably overlaps the adjacent esteraseP gene. Collating these data with previous studies suggests that expression of EST6 in the ancestral sites is mainly regulated by conserved proximal sequences while more variable distal sequences regulate expression in the acquired ejaculatory duct site.      

Phylogenetic diversification of immunoglobulin genes and the antibody repertoire

Immunoglobulins are encoded by a large multigene system that undergoes somatic rearrangement and additional genetic change during the development of immunoglobulin-producing cells. Inducible antibody and antibody-like responses are found in all vertebrates. However, immunoglobulin possessing disulfide-bonded heavy and light chains and domain-type organization has been described only in representatives of the jawed vertebrates. High degrees of nucleotide and predicted amino acid sequence identity are evident when the segmental elements that constitute the immunoglobulin gene loci in phylogenetically divergent vertebrates are compared. However, the organization of gene loci and the manner in which the independent elements recombine (and diversify) vary markedly among different taxa. One striking pattern of gene organization is the "cluster type" that appears to be restricted to the chondrichthyes (cartilaginous fishes) and limits segmental rearrangement to closely linked elements. This type of gene organization is associated with both heavy- and light-chain gene loci. In some cases, the clusters are "joined" or "partially joined" in the germ line, in effect predetermining or partially predetermining, respectively, the encoded specificities (the assumption being that these are expressed) of the individual loci. By relating the sequences of transcribed gene products to their respective germ-line genes, it is evident that, in some cases, joined-type genes are expressed. This raises a question about the existence and/or nature of allelic exclusion in these species. The extensive variation in gene organization found throughout the vertebrate species may relate directly to the role of intersegmental (V<==>D<==>J) distances in the commitment of the individual antibody-producing cell to a particular genetic specificity. Thus, the evolution of this locus, perhaps more so than that of others, may reflect the interrelationships between genetic organization and function.      

Crushing behavior of tropical and temperate crabs

The Guamunian xanthids Carpilius maculatus (L.), C. convexus (Forskal), and Eriphia sebana (Shaw & Nodder), and the parthenopid Daldorfia horrida (L.), possess large master claws with molariform teeth than are used to crush the shells of hermit crabs and snails. These crabs typically sever the spire of their prey, or make a gash in the body whorl. They tend to employ sustained pressure on the prey shell, and, except for Eriphia, rarely attack the outer lip, so that the outer lip of the shell typically remains undamaged, except in shells near the critical size, i.e., the maximum size of vulnerability to predation. Temperate species of Cancer (C. productus Randall and C. oregonensi Rathbun) may also crush shelled prey in the larger of their two claws, but more commonly they use both claws together in breaking open their victims. Sustained pressure is applied for only short periods by these crabs.Gastropod adaptations conferring resistance to crushing by crabs include a thick shell, narrow or otherwise small aperture, thickened outer lip, strong sculpture, and a low spire. Emphasis on these traits lowers the critical size of the prey, i.e., permits escape from cushing at a smaller size. An equatorward increase in the expression of the characteristics of crushing-resistance parallels an increase in crushing power of the crabs.     

The role of snail aestivation in transmission of schistosomiasis in changing climatic conditions

Schistosomiasis vector snails are subjected to extreme seasonal changes, particularly in ephemeral rivers and lentic waterbodies. In the tropics, aestivation is one of the adaptive strategies for survival and is used by snails in times of extremely high temperatures and desiccation. Aestivation therefore plays an important role in maintaining the transmission of schistosomiasis. This review assesses the possible impacts of climate change on the temporal and spatial distribution of schistosomiasis-transmitting snails with special emphasis on aestivation, and discusses the effect of schistosome infection on aestivation ability. The impacts of parasite development on snails, as well as physiological changes, are discussed with reference to schistosomiasis transmission. This review shows that schistosome-infected snails have lower survival rates during aestivation, and that those that survive manage to get rid of the infection. In general, snail aestivation ability is poor and survival chances diminish with time. Longer dry periods result in fewer, as well as uninfected, snails. However, the ability of the surviving snails to repopulate the habitats is high.     

Attenuation of pattern recognition receptor signaling is mediated by a MAP kinase kinase kinase

Pattern recognition receptors (PRRs) play a key role in plant and animal innate immunity. PRR binding of their cognate ligand triggers a signaling network and activates an immune response. Activation of PRR signaling must be controlled prior to ligand binding to prevent spurious signaling and immune activation. Flagellin perception in Arabidopsis through FLAGELLIN‐SENSITIVE 2 (FLS2) induces the activation of mitogen‐activated protein kinases (MAPKs) and immunity. However, the precise molecular mechanism that connects activated FLS2 to downstream MAPK cascades remains unknown. Here, we report the identification of a differentially phosphorylated MAP kinase kinase kinase that also interacts with FLS2. Using targeted proteomics and functional analysis, we show that MKKK7 negatively regulates flagellin‐triggered signaling and basal immunity and this requires phosphorylation of MKKK7 on specific serine residues. MKKK7 attenuates MPK6 activity and defense gene expression. Moreover, MKKK7 suppresses the reactive oxygen species burst downstream of FLS2, suggesting that MKKK7‐mediated attenuation of FLS2 signaling occurs through direct modulation of the FLS2 complex.     

Validation of a universal set of primers to study animal-associated microeukaryotic communities

The application of metabarcoding to study animal-associated microeukaryotes has been restricted because the universal barcode used to study microeukaryotic ecology and distribution in the environment, the Small Subunit of the Ribosomal RNA gene (18S rRNA), is also present in the host. As a result, when host-associated microbial eukaryotes are analysed by metabarcoding, the reads tend to be dominated by host sequences. We have done an in silico validation against the SILVA 18S rRNA database of a non-metazoan primer set (primers that are biased against the metazoan 18S rRNA) that recovers only 2.6% of all the metazoan sequences, while recovering most of the other eukaryotes (80.4%). Among metazoans, the non-metazoan primers are predicted to amplify 74% of Porifera sequences, 4% of Ctenophora, and 15% of Cnidaria, while amplifying almost no sequences within Bilateria. In vivo, these non-metazoan primers reduce significantly the animal signal from coral and human samples, and when compared against universal primers provide at worst a 2-fold decrease in the number of metazoan reads and at best a 2800-fold decrease. This easy, inexpensive, and near-universal method for the study of animal-associated microeukaryotes diversity will contribute to a better understanding of the microbiome.     

The ssu locus plays a key role in organosulfur metabolism in Pseudomonas putida S-313

Pseudomonas putida S-313 can utilize a broad range of aromatic sulfonates as sulfur sources for growth in sulfate-free minimal medium. The sulfonates are cleaved monooxygenolytically to yield the corresponding phenols. miniTn5 mutants of strain S-313 which were no longer able to desulfurize arylsulfonates were isolated and were found to carry transposon insertions in the ssuEADCBF operon, which contained genes for an ATP-binding cassette-type transporter (ssuABC), a two-component reduced flavin mononucleotide-dependent monooxygenase (ssuED) closely related to the Escherichia coli alkanesulfonatase, and a protein related to clostridial molybdopterin-binding proteins (ssuF). These mutants were also deficient in growth with a variety of other organosulfur sources, including aromatic and aliphatic sulfate esters, methionine, and aliphatic sulfonates other than the natural sulfonates taurine and cysteate. This pleiotropic phenotype was complemented by the ssu operon, confirming its key role in organosulfur metabolism in this species. Further complementation analysis revealed that the ssuF gene product was required for growth with all of the tested substrates except methionine and that the oxygenase encoded by ssuD was required for growth with sulfonates or methionine. The flavin reductase SsuE was not required for growth with aliphatic sulfonates or methionine but was needed for growth with arylsulfonates, suggesting that an alternative isozyme exists for the former compounds that is not active in transformation of the latter substrates. Aryl sulfate ester utilization was catalyzed by an arylsulfotransferase, and not by an arylsulfatase as in the related species Pseudomonas aeruginosa.     

1-Thio-beta-D-galactofuranosides: synthesis and evaluation as beta-D- galactofuranosidase inhibitors

Beta-D-galactofuranosidase is a good chemotherapeutic target for the design of inhibitors, since beta-D-galactofuranose is a constituent of important parasite glycoconjugates but is not present in the host mammals. With this aim, we have synthesized for the first time alkyl, benzyl and aryl 1-thio-beta-D-galactofuranosides by condensation of penta-O-benzoyl-alpha,beta-D-galactofuranose with the corresponding thiols, in the presence of SnCl4as catalyst. The complete chemical and spectroscopical characterization of these compounds showed that the reaction was stereoselective. Debenzoylation with sodium methoxide afforded the beta-S-galactofuranosides in high yield. The thioglycosides were tested as inhibitors of the beta-D- galactofuranosidase of Penicillium fellutanum, using for the first time 4-nitrophenyl-beta-D-galactofuranoside as chromogenic substrate. The 4- aminophenyl-1-thio-beta-D-galactofuranoside, obtained by catalytic hydrogenation of the nitrophenyl derivative, was the best inhibitor being then an adequate ligand for the preparation of an affinity phase aimed at the isolation of beta-d-galactofuranosidases from different sources. Also the inhibitory activity of d-galactono-1, 4-lactone was shown.      

Shell characters and taxonomy of Latirus and related fasciolariid groups

The neogastropod family Fasciolariidae contains a complex ofgenera related to Latirus Montfort, 1810, many of which havetraits unusual for the family. In a taxonomic revision of someof these genera, based on shell characters, we restrict Latirusto a mainly Indo-West Pacific group of Pliocene to Recent species,which closely resemble the middle Miocene to Recent pantropicalgenus Hemipolygona Rovereto, 1899. Hemipolygona stenomphalus(Habe & Kosuge, 1966) is synonymized with H. recurvirostris(Schubert & Wagner, 1829). Lathyropsis Oostingh, 1939, basedon a small Pliocene species from Indonesia, is here tentativelysubsumed under Polygona Schumacher, 1817. The latter genus,ranging from the late Oligocene to Recent, occurs mainly inthe New World and eastern Atlantic, and contains at least twospecies groups centered on P. infundibulum Schumacher, 1817(type of genus) and P. angulatus (Röding, 1798). Taxa assignedby many authors to Latirulus Cossmann, 1889, are here reassignedto the new genus Turrilatirus (type species: Voluta turritaGmelin, 1791), from the Pliocene to Recent of the Indo-WestPacific. Latirulus is restricted to Eocene species. We assignvarious early Miocene to Recent species from the western Atlanticand eastern Pacific to the new genus Pustulatirus (type species:Latirus mediamericanus, Hertlein & Strong, 1951a). Taxaformerly assigned to Latirus but here removed from Fasciolariidaeinclude Latirus ewekoroensis Adegoke, 1977; the Eocene RusculaCasey, 1904; Lathyrus granifer and L. compactilis, both of Martin,1931; Latirus kirbyi Clark, 1938; Latirus tortilis var. nanafaliusHarris, 1899; and Latirus quercotillaensis Olsson, 1931. (Received 6 September 2005; accepted 29 May 2006)