Discovery and characterization of a family of insecticidal neurotoxins with a rare vicinal disulfide bridge

We have isolated a family of insect-selective neurotoxins from the venom of the Australian funnel-web spider that appear to be good candidates for biopesticide engineering. These peptides, which we have named the Janus-faced atracotoxins (J-ACTXs), each contain 36 or 37 residues, with four disulfide bridges, and they show no homology to any sequences in the protein/DNA databases. The three-dimensional structure of one of these toxins reveals an extremely rare vicinal disulfide bridge that we demonstrate to be critical for insecticidal activity. We propose that J-ACTX comprises an ancestral protein fold that we refer to as the disulfide-directed beta-hairpin.

A family of perfect factorisations of complete bipartite graphs

A 1-factorisation of a graph is perfect if the union of any two of its 1-factors is a Hamiltonian cycle. Let n = p(2) for an odd prime p. We construct a family of (p-1)/2 non-isomorphic perfect 1-factorisations of K-n,K-n. Equivalently, we construct pan-Hamiltonian Latin squares of order n. A Latin square is pan-Hamiltoilian if the permutation defined by any row relative to any other row is a single Cycle. (C) 2002 Elsevier Science (USA).

Personal values and the `country-of-origin effect`: the moderating role of consumers` demographics

This article has addressed the following research problem: what consumers` personal values most influence the country-of-origin effect? Furthermore, it has verified whether there are differences on this influence, in terms of consumers` demographic characteristics such as gender, age and country familiarity. A descriptive and quantitative empirical research has been used to analyse the product category of Chinese home appliances, using a sample of Brazilian executives. Results have shown that consumers` personal values exert different influences on the evaluation of foreign products. Most influences of personal values on the country-of-origin effect are negative; the more important the personal values, the more negative the products are evaluated. Exceptions are for women. With the results of this research, marketing professionals and theoreticians may better manage the use of a product`s country of origin as a marketing tool in international marketing activities.

A New Family of Distance Functions for Perceptual Similarity Retrieval of Medical Images

A long-standing challenge of content-based image retrieval (CBIR) systems is the definition of a suitable distance function to measure the similarity between images in an application context which complies with the human perception of similarity. In this paper, we present a new family of distance functions, called attribute concurrence influence distances (AID), which serve to retrieve images by similarity. These distances address an important aspect of the psychophysical notion of similarity in comparisons of images: the effect of concurrent variations in the values of different image attributes. The AID functions allow for comparisons of feature vectors by choosing one of two parameterized expressions: one targeting weak attribute concurrence influence and the other for strong concurrence influence. This paper presents the mathematical definition and implementation of the AID family for a two-dimensional feature space and its extension to any dimension. The composition of the AID family with L (p) distance family is considered to propose a procedure to determine the best distance for a specific application. Experimental results involving several sets of medical images demonstrate that, taking as reference the perception of the specialist in the field (radiologist), the AID functions perform better than the general distance functions commonly used in CBIR.

A family of perfect hashing methods

Minimal perfect hash functions are used for memory efficient storage and fast retrieval of items from static sets. We present an infinite family of efficient and practical algorithms for generating order preserving minimal perfect hash functions. We show that almost all members of the family construct space and time optimal order preserving minimal perfect hash functions, and we identify the one with minimum constants. Members of the family generate a hash function in two steps. First a special kind of function into an r-graph is computed probabilistically. Then this function is refined deterministically to a minimal perfect hash function. We give strong theoretical evidence that the first step uses linear random time. The second step runs in linear deterministic time. The family not only has theoretical importance, but also offers the fastest known method for generating perfect hash functions.

A family of cytokine-inducible inhibitors of signalling

Cytokines are secreted proteins that regulate important cellular responses such as proliferation and differentiation(1). Key events in cytokine signal transduction are well defined: cytokines induce receptor aggregation, leading to activation of members of the JAK family of cytoplasmic tyrosine kinases. In turn, members af the STAT family of transcription factors are phosphorylated, dimerize and increase the transcription of genes with STAT recognition sites in their promoters(1-4). Less is known of how cytokine signal transduction is switched off. We have cloned a complementary DNA encoding a protein SOCS-1, containing an SH2-domain, by its ability to inhibit the macrophage differentiation of M1 cells in response to interleukin-6. Expression of SOCS-1 inhibited both interleukin-6-induced receptor phosphorylation and STAT activation. We have also cloned two-relatives of SOCS-1, named SOCS-2 and SOCS-3, which together with the previously described CIS (ref. 5) form a new family of proteins. Transcription of all four SOCS genes is increased rapidly in response to interleukin-6, in vitro and in vivo, suggesting they may act in a classic negative feedback loop to regulate cytokine signal transduction.

The status of the Diplosentidae (Acanthocephala : Palaeacanthocephala) and a new family of acanthocephalans from Australian wrasses (Pisces : Labridae)

The status and composition of the Diplosentidae Tubangui et Masilungan, 1937 are reviewed. The type species of the type genus, Diplosentis amphacanthi Tubangui et Masilungan, 1937 from Siganus canaliculatus (Park, 1797) in the Philippines, is concluded to have been described inaccurately,in supposedly possessing, only two cement glands and lemnisci enclosed in a membranous sac. The species is almost certainly very close to species of Neorhadinorhynchus yamaguti, 1939 and Sclerocollum Schmidt of Paperna, 1978 which have also been reported from siganids from the tropical Indo-Pacific. Species of these genera have four cement glands and unexceptional lemnisci. As a result, Diplosentis Tubangui et Masilungan, 1937 is best considered to have affinities with the Cavisomidae Meyer, 1932. The Cavisomidae has priority over the Diplosentidae; thus the Diplosentidae becomes a synonym of the Cavisomidae. Neorhadinorhynchus and Sclerocollum are considered synonyms of Diplosentis. The affinities of the other species and genera formerly included in the Diplosentidae (other species of Diplosentis, Allorhadinorhynchus Yamaguti, 1959, Amapacanthus Salgado-Maldonado et Santos, 2000, Pararhadinorhynchus Johnston et Edmonds, 1947, Golvanorhynchus Noronha, do Fabio et Pinto, 1978 and Slendrorhynchus Amin et Soy, 1996) are discussed. It is concluded that all but Pararhadinorhynchus, two species of Diplosentis and Amapacanthus can be accommodated elsewhere satisfactorily. A new family, Transvenidae, is proposed for a small group of acanthocephalans that genuinely possess only two cement glands. Transvena annulospinosa gen. n., sp. n. is described from the labrids Anampses neoguinaicus Bleeker, 1878 (type host), A. geographicus Valenciennes, 1840, A. caeruleopunctatus Ruppell, 1829, Hemigymnus fasciatus (Bloch, 1792), and H. melapterus (Bloch, 1791) from the Great Barrier Reef, Queensland, Australia. Transvena gen. n. is distinguished from all other acanthocephalan genera by having a combination of a single ring of small spines on its trunk near or at the junction between the neck and trunk, two cement glands, a double-walled proboscis receptacle and hooks which decrease in length from the apex to the base of the proboscis. A second new genus within the Transvenidae, Trajectura, is proposed for T. perinsolens sp. n. from Anampses neoguinaicus, also from the Great Barrier Reef. Trajectura gen. n. is distinguished by the possession of only two cement glands and an anterior conical projection (function unknown) on the females. Diplosentis ikedai Machida, 1992 shares these characters and is recombined as Trajectura ikedai comb. n. Pararhadinorhynchus is transferred to the Transvenidae and Diplosentis manteri Gupta et Fatma, 1979 is recombined as Pararhadinorhynchus manteri comb. n.

Major colour patterns of reef-building corals are due to a family of GFP-like proteins

Reef-building corals are renowned for their brilliant colours yet the biochemical basis for the pigmentation of corals is unknown. Here, we show that these colours are due to a family of GFP-like proteins that fluoresce under ultraviolet (UV) or visible light. Pigments from ten coral species were almost identical to pocilloporin (Dove et al. 1995) being dimers or trimers with approximately 28-kDa subunits. Degenerative primers made to common N-terminal sequences yielded a complete sequence from reef-building coral cDNA, which had 19.6% amino acid identity with green fluorescent protein (GFP). Molecular modelling revealed a 'beta -can' structure, like GFP, with 11 beta -strands and a completely solvent-inaccessible fluorophore composed of the modified residues Gln-61, Tyr-62 and Gly-63. The molecular properties of pocilloporins indicate a range of functions from the conversion of high-intensity UV radiation into photosynthetically active radiation (PAR) that can be regulated by the dinoflagellate peridinin-chlorophyll-protein (PCP) complex, to the shielding of the Soret and Q(x) bands of chlorophyll a and c from scattered high-intensity light. These properties of pocilloporin support its potential role in protecting the photosynthetic machinery of the symbiotic dinoflagellates of corals under high light conditions and in enhancing the availability of photosynthetic light under shade conditions.

Molecular analysis of dimethyl sulphide dehydrogenase from Rhodovulum sulfidophilum: its place in the dimethyl sulphoxide reductase family of microbial molybdopterin-containing enzymes

Dimethyl sulphide dehydrogenase catalyses the oxidation of dimethyl sulphide to dimethyl sulphoxide (DMSO) during photoautotrophic growth of Rhodovulum sulfidophilum . Dimethyl sulphide dehydrogenase was shown to contain bis (molybdopterin guanine dinucleotide)Mo, the form of the pterin molybdenum cofactor unique to enzymes of the DMSO reductase family. Sequence analysis of the ddh gene cluster showed that the ddhA gene encodes a polypeptide with highest sequence similarity to the molybdop-terin-containing subunits of selenate reductase, ethylbenzene dehydrogenase. These polypeptides form a distinct clade within the DMSO reductase family. Further sequence analysis of the ddh gene cluster identified three genes, ddhB , ddhD and ddhC . DdhB showed sequence homology to NarH, suggesting that it contains multiple iron-sulphur clusters. Analysis of the N-terminal signal sequence of DdhA suggests that it is secreted via the Tat secretory system in complex with DdhB, whereas DdhC is probably secreted via a Sec-dependent mechanism. Analysis of a ddhA mutant showed that dimethyl sulphide dehydrogenase was essential for photolithotrophic growth of Rv. sulfidophilum on dimethyl sulphide but not for chemo-trophic growth on the same substrate. Mutational analysis showed that cytochrome c (2) mediated photosynthetic electron transfer from dimethyl sulphide dehydrogenase to the photochemical reaction centre, although this cytochrome was not essential for photoheterotrophic growth of the bacterium.

The DMSO reductase family of microbial molybdenum enzymes; Molecular properties and role in the dissimilatory reduction of toxic elements

The dimethylsulfoxide (DMSO) reductase family of molybdenum enzymes is a large and diverse group that is found in bacteria and archaea. These enzymes are characterised by a bis(molybdopterin guanine dinucleotide)Mo form of the molybdenum cofactor, and they are particularly important in anaerobic respiration including the dissimilatory reduction of certain toxic oxoanions. The structural and phylogenetic relationship between the proteins of this family is discussed. High-resolution crystal structures of enzymes of the DMSO reductase family have revealed a high degree of similarity in tertiary structure. However, there is considerable variation in the structure of the molybdenum active site and it seems likely that these subtle but important differences lead to the great diversity of function seen in this family of enzymes. This diversity of catalytic capability is associated with several distinct pathways of electron transport.

N4WBP5, a potential target for ubiquitination by the Nedd4 family of proteins, is a novel golgi-associated protein

Nedd4 belongs to a family of ubiquitin-protein ligases that is characterized by 2-4 WW domains, a carboxyl-terminal Hect ((h) under bar omologous to (E) under bar6-AP (C) under bar arboxyl (t) under bar erminus)-domain and in most cases an amino-terminal C2 domain. We had previously identified a series of proteins that associates with the WW domains of Nedd4. In this paper, we demonstrate that one of the Nedd4-binding proteins, N4WBP5, belongs to a small group of evolutionarily conserved proteins with three transmembrane domains. N4WBP5 binds Nedd4 WW domains via the two PPXY motifs present in the amino terminus of the protein. In addition to Nedd4, N4WBP5 can interact with the WW domains of a number of Nedd4 family members and is ubiquitinated. Endogenous N4WBP5 localizes to the Golgi complex. Ectopic expression of the protein disrupts the structure of the Golgi, suggesting that N4WBP5 forms part of a family of integral Golgi membrane proteins. Based on previous observations in yeast, we propose that N4WBP5 may act as an adaptor for Nedd4-like proteins and their putative targets to control ubiquitin-dependent protein sorting and trafficking.

A family of textilinin genes, two of which encode proteins with antihaemorrhagic properties

Two peptides, textilinins 1 and 2, isolated from the venom of the Australian common brown snake, Pseudonaja textilis textilis, are effective in preventing blood loss. To further investigate the potential of textilinins as anti-haemorrhagic agents, we cloned cDNAs encoding these proteins. The isolated full-length cDNA (430 bp in size) was shown to code for a 59 amino acid protein, corresponding in size to the native peptide, plus an additional 24 amino acid propeptide. Six such cDNAs were identified, differing in nucleotide sequence in the coding region but with an identical propeptide. All six sequences predicted peptides containing six conserved cysteines common to Kunitz-type serine protease inhibitors. When expressed as glutathione S-transferase (GST) fusion proteins and released by cleavage with thrombin, only those peptides corresponding to textilinin 1 and 2 were active in inhibiting plasmin with K-i values similar to those of their native counterparts and in binding to plasmin less tightly than aprotinin by two orders of magnitude. Similarly, in the mouse tail vein blood loss model only recombinant textilinin 1 and 2 were effective in reducing blood loss. These recombinant textilinins have potential as therapeutic agents for reducing blood loss in humans, obviating the need for reliance on aprotinin, a bovine product with possible risk of transmissible disease, and compromising the fibrinolytic system in a less irreversible manner.