Symptom development on two wild, perennial grasses infected by Peronosclerospora species (Family Peronosporaceae: the downy-mildew fungi)

The reproductive structures of the downy-mildew fungi, Peronosclerospora noblei and Peronosclerospora eriochloae, develop only on chlorotic leaves of tall, vegetative tillers of the perennial grasses Sorghum leiocladum (wild sorghum) and Eriochloa pseudoacrotricha (early spring grass), respectively. They are never found on the leaves of flowering tillers, even when tillers of both types grow from the same tussock. The development of symptoms on infected tillers of both hosts and the morphological and anatomical changes to host tissues on infected tillers are detailed.

Of mites and bees: A review of mite-bee associations in Australia and a revision of Raymentia Womersley (Acari : Mesostigmata : Laelapidae), with the description of two new species of mites from Lasioglossum (Parasphecodes) spp. (Hymenoptera : Halictidae)

Social bees have a diverse fauna of symbiotic mesostigmatic mites, including highly pathogenic parasites of the honeybee, but there are few reports of Mesostigmata phoretic on or inhabiting the nests of solitary or communal, ground-nesting bees. In south-eastern Australia, however, native bees in the family Halictidae carry what appears to be a substantial radiation of host-specific mesostigmatans in the family Laelapidae. Herein, we redescribe the obscure genus Raymentia , associated with Lasioglossum (Parasphecodes ) spp. bees (Halictidae) and describe two new species, R. eickwortiana from L. lacthium (Smith) and R. walkeriana from L. atronitens (Cockerell). The type species, R. anomala Womersley, is associated with L. altichum (Smith). In addition, we review the mites known to be associated with Australian bees, provide a key to differentiate them, and describe and illustrate acarinaria of the Halictinae. We also report on the first occurrences in Australia of the genera Trochometridium Cross (Heterostigmata: Trochometridiidae), from L. eremaean Walker (Halictidae), and Cheletophyes Oudemans (Prostigmata: Cheyletidae) from Xylocopa Latreille (Xylocopinae), and on the previously unknown association between a Neocypholaelaps Vitzthum (Mesostigmata: Ameroseiidae) and Lipotriches tomentifera (Friese) (Halictidae).

The Building Partnerships Program: An Approach to Community-based Learning for Medical Students in Australia

The Building Partnerships Program at the University of Queensland, Australia seeks to address the dual challenge of preparing doctors who are responsive to the community while providing a meaningful context for social sciences learning. Through partnerships with a diverse range of community agencies, the program offers students opportunities to gain non-clinical perspectives on health and illness through structured learning activities including: family visits; community agency visits and attachments; and interview training. Students learn first-hand about psychosocial influences on health and how people manage health problems on a day-to-day basis. They also gain insights into the work of community agencies and how they as future doctors might work in partnership with them to enhance patient care. We outline the main components of the program, identify challenges and successes from student and community agency perspectives, and consider areas that invite further development.

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.

Discovery and structures of the cyclotides: novel macrocyclic peptides from plants

Circular disulfide-rich polypeptides were unknown a decade ago but over recent years a large family of such molecules has been discovered, which we now refer to as the cyclotides. They are typically about 30 amino acids in size, contain an N- to C-cyclised backbone and incorporate three disulfide bonds arranged in a cystine knot motif. In this motif, an embedded ring in the structure formed by two disulfide bonds and their connecting backbone segments is penetrated by the third disulfide bond. The combination of this knotted and strongly braced structure with a circular backbone renders the cyclotides impervious to enzymatic breakdown and makes them exceptionally stable. This article describes the discovery of the cyclotides in plants from the Rubiaceae and Violaceae families, their chemical synthesis, folding, structural characterisation, and biosynthetic origin. The cyclotides have a diverse range of biological applications, ranging from uterotonic action, to anti-HIV and neurotensin antagonism. Certain plants from which they are derived have a history of uses in native medicine, with activity being observed after oral ingestion of a tea made from the plants. This suggests the possibility that the cyclotides may be orally bioavailable. They therefore have a range of potential applications as a stable peptide framework.

Relationships of extant lower Brachycera (Diptera): a quantitative synthesis of morphological characters

With over 80 000 described species, Brachycera represent one of the most diverse clades of organisms with a Mesozoic origin. Larvae of the majority of early lineages are detritivores or carnivores. However, Brachycera are ecologically innovative and they now employ a diverse range of feeding strategies. Brachyceran relationships have been the subject of numerous qualitative analyses using morphological characters. These analyses are often based on characters from one or a few character systems and general agreement on relationships has been elusive. In order to understand the evolution of basal brachyceran lineages, 101 discrete morphological characters were scored and compiled into a single data set. Terminals were scored at the family level, and the data set includes characters from larvae, pupae and adults, internal and external morphology, and male and female terminalia. The results show that all infraorders of Brachycera are monophyletic, but there is little evidence for relationships between the infraorders. Stratiomyomorpha, Tabanomorpha, and Xylophagomorpha together form the sister group to Muscomorpha. Xylophagomorpha and Tabanomorpha are sister groups. Within Muscomorpha, the paraphyletic Nemestrinoidea form the two most basal lineages. There is weak evidence for the monophyly of Asiloidea, and Hilarimorphidae appear to be more closely related to Eremoneura than other muscomorphs. Apsilocephalidae, Scenopinidae and Therevidae form a clade of Asiloidea. This phylogenetic evidence is consistent with the contemporaneous differentiation of the main brachyceran lineages in the early Jurassic. The first major radiation of Muscomorpha were asiloids and they may have diversified in response to the radiation of angiosperms in the early Cretaceous.

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.

Comparative sperm ultrastructure in five genera of the nudibranch family Chromodorididae (Gastropoda : Opisthobranchia)

Sperm ultrastructure is examined in representatives of five genera of the nudibranch gastropod family Chromodorididae: (Chromodoris, Hypselodoris, Glossodoris, Risbecia and Pectenodoris) and the results compared with previous work on other gastropods, especially other nudibranchs. As chromodoridid phylogeny is still incompletely understood, this study partly focuses on the search for new and as yet untapped sources of informative characters. Like spermatozoa of most other heterobranch gastropods, those of the Chromodorididae are elongate, complex cells composed of an acrosomal complex (small, rounded acrosomal vesicle, and columnar acrosomal pedestal), a condensed nucleus, sub-nuclear ring, a highly modified mid-piece (axoneme + coarse fibres surrounded by a glycogen-containing, helically-coiled mitochondrial derivative) and terminally a glycogen piece (or homologue thereof). The finely striated acrosomal pedestal is a synapomorphy of all genera examined here, but interestingly also occurs in at least one dorid (Rostanga arbutus). Substantial and potentially taxonomically informative differences were also observed between genera in the morphology of the nucleus, the neck region of the mid-piece, and also the terminal glycogen piece. The subnuclear ring is shown for the first time to be a segmented, rather than a continuous structure; similarly, the annular complex is shown to consist of two structures, the annulus proper and the herein-termed annular accessory body.

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.