Opecoelidae (Digenea) from western Mediterranean fishes: three rare species

Three little-known opecoelid digeneans from marine fishes off Corsica, France, are redescribed and their relationships discussed. Plagioporus novella Maillard & Lambert, 1978 from Conger conger is transferred to Podocotyle as P. novella (Maillard & Lambert, 1978) n. comb. The new combinations Podocotyle tohei (Yamaguti, 1970) and P. congeri (Yamaguti, 1970) are formed for species originally assigned to Plagioporus. Podocotyle temensis Fischthal & Thomas, 1970 from Epinephelus guaza is redescribed and compared with the other Podocotyle species reported from the Mediterranean. A third species, Pseudopecoeloides chloroscombri (Fischthal & Thomas, 1970) n. comb. (was Podocotyloides), is redescribed from three Trachurus species and a key to the species of this Pseudopecoeloides is given.     

Lecithostaphylus retroflexus (Molin, 1859) (Zoogonidae) and Tergestia acanthocephala (Stossich, 1887) (Fellodistomidae) (Digenea) from the epipelagic teleost Belone belone (L.) in the western Mediterranean

Numerous individuals of the poorly known species Lecithostaphylus retroflexus (Zoogonidae) and Tergestia acanthocephala (Fellodistomidae) have been recovered from the teleost fish Belone belone gracilis from off the Scandola Nature Reserve, Western Mediterranean. They are redescribed, incorporating previously undescribed features: for L. retroflexus, a post-oral ring, a bipartite seminal vesicle, the shape of the excretory vesicle, the subterminal excretory pore and the flask-shaped gland-cells associated with the distinctly pedunculate ventral sucker; and for T. acanthocephala, the intestinal bifurcation in the forebody, necessitating its return to the genus Tergestia from Theledera. Additionally, T. acanthocephala is compared with T. laticollis from various species of Trachurus from the same geographical area.     

Species of Stephanostomum Looss, 1899 (Digenea: Acanthocolpidae) from fishes of Australian and South Pacific waters,including five new species

Nine species of Stephanostomum are described from Australian and Southern Pacific marine fishes: Stephanostomum madhaviae n. sp. [syn. S. orientalis of Madhavi (1976)] from Caranx ignobilis, off Hope Island, Queensland, with 30-34 circum-oral spines and vitelline fields almost reaching to the posterior extremity of the cirrus-sac; S. bicoronatum (Stossich, 1883) from Argyrosomus hololepidotus, off Southport Broadwater, Queensland; S. votonimoli n. sp. from Scomberoides lysan, off Moorea, French Polynesia (type-locality) and Western Samoa, with 33-38 circum-oral spines, a uroproct and the vitelline fields not reaching the cirrus-sac; S. nyoomwa n. sp. from Caranx sexfasciatus, off Heron Island, Queensland, with 33-38 circum-oral spines, a uroproct and the vitelline fields reaching the cirrus-sac; S. cobia n. sp. from Rachycentron canadum, off Heron Island, with 36 circum-oral spines, a uroproct and the vitelline fields reaching the cirrus-sac; S. petimba Yamaguti, 1970 from Seriola hippos, off Rottnest Island, Western Australia; S. pacificum (Yamaguti, 1951) from Pseudocaranx wrighti, off Fremantle, Western Australia; S. aaravi n. sp. from Lethrinus miniatus, off Heron Island, with 36-39 circum-oral spines, probably a uroproct and the vitelline fields reaching the ventral sucker; S. pagrosomi (Yamaguti, 1939) from L. nebulosus, L. miniatus and L. atkinsoni off Heron Island, Pagrus auratus, off Rottnest Island, Western Australia and Gymnocranius audleyi, off Heron Island. A digest of described species of Stephanostomum is included as an appendix.     

Lepocreadiidae (Digenea) from the batfish of the genus Platax Cuvier (Teleostei: Ephippidae) from the southern Great Barrier Reef,Queensland, Australia

The following species are described from Platax spp.: Neomultitestis aspidogastriformis n. sp., from P. teira, off Heron Island, Queensland, which can be distinguished from its congeners by the transversely elongate ventral sucker divided into three loculi and probably by testis number; Multitestis magnacetabulum Mamaev, 1970, from P. teira, off Heron Island, Queensland; Diploproctodaeum rutellum (Mamaev, 1970), from P. teira, off Heron Island, Queensland; Diploproctodaeum tsubameuo n. sp., from P. batavianus, from the Swain Reefs, off Queensland, which differs from its congeners in its overlapping, posteriorly attenuated testes and 38-55 ovarian lobes; and Diplocreadium sp., from P. batavianus, from the Swain Reefs, off Queensland.     

Pentamidine uptake and resistance in pathogenic protozoa: past,present and future

Diamidines, and pentamidine in particular, have a long history as valuable chemotherapeutic agents against infectious disease. Their selectivity is due mostly to selective accumulation by the pathogen, rather than the host cell; and acquired resistance is frequently the result of changes in transmembrane transport of the drug. Here, recent progress in elucidating the mechanisms of diamidine transport in three important protozoan pathogens, Trypanosoma brucei, Leishmania and Plasmodium falciparum, is reviewed, and the implications for drug resistance are discussed.     

Target selection and determination of function in structural genomics

The first crucial step in any structural genomics project is the selection and prioritization of target proteins for structure determination. There may be a number of selection criteria to be satisfied, including that the proteins have novel folds, that they be representatives of large families for which no structure is known, and so on. The better the selection at this stage, the greater is the value of the structures obtained at the end of the experimental process. This value can be further enhanced once the protein structures have been solved if the functions of the given proteins can also be determined. Here we describe the methods used at either end of the experimental process: firstly, sensitive sequence comparison techniques for selecting a high-quality list of target proteins, and secondly the various computational methods that can be applied to the eventual 3D structures to determine the most likely biochemical function of the proteins in question.     

Bowl is required downstream of Notch for elaboration of distal limb patterning

In the Drosophila leg, activation of Notch leads to the establishment of the joints that subdivide the appendage into segments. We find that mutations in bowl result in similar phenotypes to Notch, causing fusion and truncations of tarsal segments (tarsomeres) and, like its close relative Odd-skipped, Bowl is produced in response to Notch signalling at a subset of segment boundaries. However, despite the fact that bowl mutant clones result in fusion of tarsomeres, Bowl protein is only found at the t1/tibial and t5/pretarsal boundaries, not at tarsomere joints. One hypothesis to reconcile these data is that bowl has a role at an earlier stage in tarsal development. We therefore investigated the effects of bowl mutations on the expression of leg 'gap' genes that confer regional identity on the developing leg. Several of these genes have altered expression in bowl mutant cells. For example, bric-a-brac2 is normally expressed in the central part of the tarsus domain but expands into distal and proximal regions in bowl clones. Conversely, ectopic bowl leads to a reduction in bric-a-brac2, with a concomitant expansion of proximal (t1) and distal (t5) tarsomere fates. The bowl gene is therefore required for the elaboration of pattern in the tarsus and its effects suggest a progressive model for the determination of P/D identities. This mechanism might be important in the diversification of arthropod limbs, because it explains how segmented tarsomeres could have arisen from an ancestral limb with an unsegmented tarsus.     

Analysis of binding of the family 2a carbohydrate-binding module from Cellulomonas fimi xylanase 10A to cellulose: specificity and identification of functionally important amino acid residues

The family 2a carbohydrate-binding module (CBM2a) of xylanase 10A from Cellulomonas fimi binds to the crystalline regions of cellulose. It does not share binding sites with the N-terminal family 4 binding module (CBM4-1) from the cellulase 9B from C.fimi, a module that binds strictly to soluble sugars and amorphous cellulose. The binding of CBM2a to crystalline matrices is mediated by several residues on the binding face, including three prominent, solvent-exposed tryptophan residues. Binding to crystalline cellulose was analyzed by making a series of conservative (phenylalanine and tyrosine) and non-conservative substitutions (alanine) of each solvent-exposed tryptophan (W17, W54 and W72). Other residues on the binding face with hydrogen bonding potential were substituted with alanine. Each tryptophan plays a different role in binding; a tryptophan is essential at position 54, a tyrosine or tryptophan at position 17 and any aromatic residue at position 72. Other residues on the binding face, with the exception of N15, are not essential determinants of binding affinity. Given the specificity of CBM2a, the structure of crystalline cellulose and the dynamic nature of the binding of CBM2a, we propose a model for the interaction between the polypeptide and the crystalline surface.