The draft genome of Ciona intestinalis: Insights into chordate and vertebrate origins

The first chordates appear in the fossil record at the time of the Cambrian explosion, nearly 550 million years ago. The modern ascidian tadpole represents a plausible approximation to these ancestral chordates. To illuminate the origins of chordate and vertebrates, we generated a draft of the protein-coding portion of the genome of the most studied ascidian, Ciona intestinalis. The Ciona genome contains similar to16,000 protein-coding genes, similar to the number in other invertebrates, but only half that found in vertebrates. Vertebrate gene families are typically found in simplified form in Ciona, suggesting that ascidians contain the basic ancestral complement of genes involved in cell signaling and development. The ascidian genome has also acquired a number of lineage-specific innovations, including a group of genes engaged in cellulose metabolism that are related to those in bacteria and fungi.

Molecular evidence for the common origin of snap-traps among carnivorous plants

The snap-trap leaves of the aquatic waterwheel plant (Aldrovanda) resemble those of Venus' flytrap (Dionaea), its distribution and habit are reminiscent of bladderworts (Utricularia), but it shares many reproductive characters with sundews (Drosera). Moreover, Aldrovanda has never been included in molecular phylogenetic studies, so it has been unclear whether snap-traps evolved only once or more than once among angiosperms. Using sequences from nuclear 18S and plastid rbcL, atpB, and matK genes, we show that Aldrovanda is sister to Dionaea, and this pair is sister to Drosera. Our results indicate that snap-traps are derived from flypaper-traps and have a common ancestry among flowering plants, despite the fact that this mechanism is used by both a terrestrial species and an aquatic one. Genetic and fossil evidence for the close relationship between these unique and threatened organisms indicate that carnivory evolved from a common ancestor within this caryophyllid clade at least 65 million years ago.

Neuro-angiostrongylosis in wild Black and Grey-headed flying foxes (Pteropus spp)

Objective To identify nematodes seen in histological sections of brains of flying foxes (fruit bats) and describe the associated clinical disease and pathology. Proceedures Gross and histological examination of brains from 86 free-living flying foxes with neurological disease was done as part of an ongoing surveillance program for Australian bat lyssavirus. Worms were recovered, or if seen in histological sections, extracted by maceration of half the brain and identified by microscopic examination. Histological archives were also reviewed. Results There was histological evidence of angiostrongylosis in 16 of 86 recently submitted flying foxes with neurological disease and in one archival case from 1992. In 10 flying foxes, worms were definitively identified as Angiostrongylus cantonensis fifth-stage larvae. A worm fragment and third stage larvae were identified as Angiostrongylus sp, presumably A cantonensis, in a further three cases. The clinical picture was dominated by paresis, particularly of the hind-limbs, and depression, with flying foxes surviving up to 22 days in the care of wildlife volunteers. Brains containing fifth-stage larvae showed a moderate to severe eosinophilic and granulomatous meningoencephalitis (n = 14), whereas there was virtually no inflammation of the brains of bats which died when infected with only smaller, third-stage larvae (n = 3). There was no histological evidence of pulmonary involvement. Conclusion This is the first report of the recovery and identification of A cantonensis from free-living Australian wildlife. While anglostrongylosis is a common cause of paresis in flying foxes, the initial clinical course cannot be differentiated from Australian bat lyssavirus infection, and wildlife carers should be urged not to attempt to rehabilitate flying foxes with neurological disease.

The spread of Angiostrongylus cantonensis in Australia

Until the recent establishment of Angiostrongylus cantonensis in North America. Australia was the only developed region endemic for this parasite. Almost 50 years ago the life cycle was elucidated there, in the city of Brisbane, and the first human infections probably occurred in 1959. From the 1970s, increasing numbers of autochthonous infections have been reported along the central east coast of the continent (southeast Queensland and northern New South Wales), involving humans, rats, dogs, horses, flying foxes and marsupials. Ten years ago, the parasite was discovered in Sydney, almost 1,000 km to the south, in dogs. In that city, it has since been diagnosed as a cause of neurological disease in increasing numbers of dogs, flying foxes, marsupials and zoo primates. Presumably, these infections resulted from the ingestion of snails or slugs, and it seems that virtually all species of native and exotic terrestrial molluscs can serve as intermediate hosts. It is not known how the parasite was introduced to this continent, or how it has spread over such an extensive territory, although eventually its range could encompass the entire east coast, and potentially other regions. It is also not known if the almost identical, native species, A. mackerrasae, is able to infect people (or other non-rodent hosts). All worms recovered to date, from one fatal human case, and from many animal infections, have been confirmed as A. cantonensis.

Current concepts - Schistosomiasis

In 1851, Theodor Bilharz described a parasitic infection (bilharzia) that would later be termed schistosomiasis. Currently, 200 million people in 74 countries have this disease; 120 million of them have symptoms, and 20 million have severe illness.1 Schistosomiasis is caused by parasitic trematode worms (schistosomes) that reside in the abdominal veins of their vertebrate definitive hosts. The life cycle of the schistosome is depicted in Figure 1. Schistosomiasis is 1 of the 10 tropical diseases especially targeted for control by the Special Program for Research and Training in Tropical Diseases of the United Nations Development Program, the World Bank, . . . [Full Text of this Article]

Anomalies in the developing neural and visceral head skeleton of the Australian lungfish, Neoceratodus forsteri

Several anomalies occur in the developing neural and visceral head skeleton of young specimens of Neoceratodus forsteri that have been reared under laboratory conditions. These include anomalies of the basicranium and its derivatives, aberrations of the anterior mandible and hyoid apparatus, and abnormalities in the articulation of the jaws and the elements that produce them. Apart from the occasional absence of the basihyal, and failure of the quadrate processes to form, the anomalies are not deficiencies. Most involve malformations of parts of the neurocranium and visceral skeleton, inappropriate articulations or fusions between elements, disunity in structures that are normally fused and the appearance of supernumerary elements. The incidence of chondral anomalies, generally higher than aberrations that occur in the dermal skeleton in juvenile lungfish, ranges from 1-10% in laboratory reared individuals that have not been subjected to experimental interference. The anomalies differ from those found in many amphibian populations, in the field and in the laboratory, because they involve the cranium, and not the limbs, and the lungfish have not been exposed to the factors that cause anomalies in the amphibians. It is unlikely that the existence of those anomalies, if it is reflected in the wild population, places a selective pressure on the lungfish, because, in a normal season, less than 1% of the total number of eggs produced survive to be recruited into the adult population.

Dental and skeletal pathology in lungfish jaws and tooth plates

Many lungfish of the tooth plated lineage, both fossil and living, are affected by dental and skeletal pathologies including dental caries, abscesses and cysts within the bone or tooth plate, osteopenia, bone hypertrophy, and malocclusion. These conditions, while influenced in part by structural relationships of soft and hard tissues in the tooth plates, jaw bones and surrounding oral tissues, can also be used as indicators of the kind of environment inhabited by the fish. The disease processes have specific structural consequences, related either to the pathology or to attempts to heal the damage, and usually alter the form and function of the tooth plate or bone. Consequently they can be distinguished from postmortem diagenetic or taphonomic effects, which alter the structure in less specific ways and show no sign of healing. Dental caries, the most common pathological condition in dipnoan dentitions, is recognisable in lungfish from the Devonian of Western Australia, the Tertiary of South Australia and the Northern Territory and from living lungfish in south east Queensland. Other pathologies have a more sporadic occurrence.

The last dicynodont: An Australian Cretaceous relict

Some long-forgotten fossil evidence reveals that a dicynodont (mammal-like reptile of the infraorder Dicynodontia) inhabited Australia as recently as the Early Cretaceous, ca. 110 Myr after the supposed extinction of dicynodonts in the Late Triassic. This remarkably late occurrence more than doubles the known duration of dicynodont history (from ca. 63 Myr to ca. 170 Myr) and betrays the profound impact of geographical isolation on Australian terrestrial faunas through the Mesozoic. Australia's late-surviving dicynodont may be envisaged as a counterpart of the ceratopians (homed dinosaurs) in Cretaceous tetrapod faunas of Asia and North America.

Comparative genetic study confirms exceptionally low genetic variation in the ancient and endangered relictual conifer, Wollemia nobilis (Araucariaceae)

The Wollemi pine, Wollemia nobilis (Araucariaceae), was discovered in 1994 as the only extant member of the genus, previously known only from the fossil record. With fewer than 100 trees known from an inaccessible canyon in southeastern Australia, it is one of the most endangered tree species in the world. We conducted a comparative population genetic survey at allozyme, amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) loci in W. nobilis, Araucaria cunninghatnii and Agathis robusta - representatives of the two sister genera. No polymorphism was detected at 13 allozyme loci, more than 800 AFLP loci or the 20 SSR loci screened in W. nobilis. In Ag. robusta only one of 12 allozyme loci, five of 800 AFLP loci and none of the 15 SSR loci were variable. For A. cunninghamii, 10 of > 800 AFLP loci and five of 20 SSR loci were variable. Thus low genetic diversity characterizes all three species. While not ruling out the existence of genetic variation, we conclude that genetic diversity is exceptionally low in the Wollemi pine. To our knowledge this is the most extreme case known in plants. We conclude that the combination of small population effects, clonality and below-average genetic variation in the family are probable contributing factors to the low diversity. The exceptionally low genetic diversity of the Wollemi pine, combined with its known susceptibility to exotic fungal pathogens, reinforces current management policies of strict control of access to the pines and secrecy of the pine locations.

New Zealand climate in the Neogene and implications for global atmospheric circulation

New Zealand has a good Neogene plant fossil record. During the Miocene it was without high topography and it was highly maritime, meaning that its climate, and the resulting vegetation, would be controlled dominantly by zonal climate conditions. Its vegetation record during this time suggests the climate passed from an ever-wet and cool but frostless phase in the Early Miocene in which Nothofagus subgenus Brassospora was prominent. Then it became seasonally dry, with vegetation in which palms and Eucalyptus were prominent and fires were frequent, and in the mid-Miocene, it developed a dry-climate vegetation dominated by Casuarinaceae. These changes are reflected in a sedimentological change from acidic to alkaline chemistry and the appearance of regular charcoal in the record. The vegetation then changed again to include a prominent herb component including Chenopodiaceae and Asteraceae. Sphagnum became prominent, and Nothofagus returned, but mainly as the subgenus Fuscospora (presently restricted to temperate climates). This is interpreted as a return to a generally wet, but now cold climate, in which outbreaks of cold polar air and frost were frequent. The transient drying out of a small maritime island and the accompanying vegetation/climate sequence could be explained by a higher frequency of the Sub-Tropical High Pressure (STHP) cells (the descending limbs of the Hadley cells) over New Zealand during the Miocene. This may have resulted from an increased frequency of 'blocking', a synoptic situation which occurs in the region today. An alternative hypothesis, that the global STHP belt lay at a significantly higher latitude in the early Neogene (perhaps 55degreesS) than today (about 30degreesS), is considered less likely because of physical constraints on STHP belt latitude. In either case, the difference between the early Neogene and present situation may have been a response to an increased polar-equatorial temperature gradient. This contrasts with current climate models for the geological past in which the latitude of the High Pressure belt impact is held invariant though geological time. (C) 2003 Elsevier Science B.V. All rights reserved.

Poracanthodid acanthodian from the Upper Silurian (Pridoli) of Nevada

Dissociated remains of the acanthodian Poracanthodes punctatus are described from Upper Silurian (Pridoli) limestones of the Roberts Mountains Formation at Pete Hanson Creek, Eureka County, Nevada. The vertebrate microremains in sample residues comprise scales, a dentigerous jaw bone fragment, and a fin spine fragment assigned to P. punctatus, plus one possible acanthothoracid placoderm scale. Some macroremains from the same locality are also assigned to P. punctatus. This taxon has been nominated as, a zone fossil for the Silurian vertebrate biozonal scheme, and its presence has been recorded throughout the circum-Arctic region. Identification of the taxon in Nevada extends its known geographic range.

Dactylomyza gibsoni n.g., n. sp (Digenea: Opecoelidae) from Schuettea woodwardi (Waite) (Monodactylidae) from off Western Australia

An opecoelid digenean, Dactylomyza gibsoni n. g., n. sp. is described and figured from Schuettea woodwardi (Waite), a monodactylid from off the coast of Western Australia. The new genus conforms to the concept of the opecoelid subfamily Opecoelinae. The resemblance of the new genus to three other opecoelid genera, Pseudopecoeloides Yamaguti, 1940, Opecoeloides Odhner, 1928 and Poracanthium Dollfus, 1948, is discussed. Dactylomyza n. g. is distinguished from these morphologically similar worms on the basis of its median genital pore, ventral sucker appendages, uroproct and the absence of an accessory sucker. Pseudopecoeloides equesi Manter, 1947 is transferred to the new genus as Dactylomyza equesi (Manter, 1947) n. comb.

Experimental human infection with the dog hookworm, Ancylostoma caninum

Objective: To investigate possible routes for human infection by the dog hookworm (Ancylostoma caninum). Design, setting and participant. Relatively small numbers of infective larvae were administered orally and percutaneously to an informed healthy volunteer (J K L) under medical supervision, at intervals between May 1998 and May 1999. Main outcome measures: Symptoms; weekly blood eosinophil counts; faecal microscopy. Results: A marked blood eosinophilia followed a single oral exposure to 100 infective larvae, while faecal examination remained negative. Eosinophil counts then declined gradually, although a rapid, spontaneous rise several months later, at the beginning of spring, possibly indicated reactivation of dormant larvae. Blood eosinophil numbers did not rise significantly after percutaneous infection with 200 larvae. A subsequent, smaller, oral inoculum of 20 larvae provoked an eosinophil response similar to that of the first experiment. Conclusions: Our findings suggest that, following ingestion, some infective larvae of A. caninum develop directly into adult worms in the human gut (as they do in dogs). While the percutaneous route might be the most common means of human exposure to canine hookworm larvae, leading generally to subclinical infection, oral infection may be more likely to provoke symptomatic eosinophilic enteritis.

Developmental anomalies in the tooth plates and jaw bones of lungfish

Lungfish of the tooth-plated lineage, both fossil and living, may be affected by alterations in the permanent tooth plates and associated jaw bones as they grow. In a few taxa, the unusual structures may be so common that they must be considered as normal for those species, or as a variation of the normal condition. In others the condition is rare, affecting only a few individuals. Variations, or anomalies, may appear in the growing tissues of the lungfish tooth plate at any time in the life cycle, although they usually appear early in development. Once the changes appear, they persist in the dentition. The altered structures include divided or intercalated ridges, short ridge anomaly, changes in the shape, number and position of cusps, pattern loss, and fused ridges or cusps. Criteria used to distinguish alteration from normal conditions are the incidence of the character in the population, the associated changes in the jaw bone, and the position of the altered structure in the tooth plate. The occurrence of similar changes across a wide range of different species suggests that they may have a genetic cause, especially when they are a rare occurrence in most taxa, but common enough to be a part of the normal variation in others. Prevalence of related anomalies throughout the history of the group suggests that dipnoans of the tooth-plated lineage are closely related, despite significant differences in morphology, microstructure, and function of the denfitions.

Biodegradation and ecotoxicity evaluation of a bionolle and starch blend and its degradation products in compost

A polymer based on a blend of starch and Bionolle(TM) has been prepared and tested for biodegradation in compost. The polymer was completely mineralised to carbon dioxide in 45 days. The potential toxicity of the polymer was tested against the earthworm Eisenia fetida using a modification of the American Standard for Testing Materials E1976-97. The earthworms were exposed to 30 g of the polymer for 28 days and changes in weight recorded. In addition, the polymer was firstly degraded by the compost and the worms exposed to the breakdown products for 28 days. Differences in weight were also recorded. In each case the production of juveniles was noted and all earthworms were examined for pathology. The results obtained were processed statistically using a t-test. The number of juveniles, produced from the breakdown products, was highly significant (P < 0.001) when compared to the earthworms added to the intact polymer. There was a definitely significant difference (P < 0.01, t = 3.25) in change in weight between the earthworms that were exposed to the polymer directly and those that were exposed to the breakdown products. There was no indication of any pathology of any earthworms. The polymer is considered safe for this species. (C) 2002 Elsevier Science Ltd. All rights reserved.