This study used measurements and observations on the burrows of extant species of Dodecaceria fimbriata and D. concharum to identify their possible fossil burrows. The extant burrows were from marine littoral shale and the calcareous alga Lithothamnion. From published records unequivocal fossil burrows were not found for these two species. Trace fossils of D. fimbriata appear to have been present in the Miocene and Dodecaceria cretacea (probably not Dodecaceria) in the Cretaceous. The conclusion is that D. fimbriata and D. concharum separated from a common ancestor in the late Cretaceous.

Oersted in 1843 gave a brief description of Dodecaceria concharum collected from the Kattegat. This was inadequate for identifying the species. Caullery and Mesnil in 1898 described three forms of Dodecaceria (A, B and C) but they were uncertain which form Oersted described. Dehorne in 1933 described D caulleryi (now D. fimbriata), which reproduce asexually, and Form B of Caullery and Mesnil. By default Form B became D. concharum the parthenogenetic species Form A of Caullery and Mesnil. Gibson and Heppell in 1995 in an attempt to consolidate these names deposited new types for the two species at the Cambers Street Museum in Edinburgh.

The authors report here robust autophagy observed by electron microscopy in both the Echigo-1 strain of Creutzfeldt-Jakob disease in hamsters and the Fujisaki strain of Gerstmann-Sträussler-Scheinker disease in mice. In both models, autophagic vacuoles were observed in several cellular compartments. In neuronal cell bodies, autophagic vacuoles of different size were seen. The cytoplasm of some neurons also contained semicircular cisterns equivalent to an early autophasophore. The major target of autophagy was dystrophic neurites, i.e., enlarged neuritic processes--mostly dendrites but also axonal terminals and preterminals. They contained numerous double- or multiple-membrane-bound autophagosomes or autophagolysosomes and large multivesicular bodies. Multivesicular bodies were also observed within autophagic vacuoles, and large multivesicular bodies were seen within synaptic terminals. Some dystrophic neurites was filled almost completely with multivesicular bodies; the latter were occasionally confluent. The authors conclude that autophagy is an important part of neuropathology in prion disease. They also suggest that spongiform vacuoles, a hallmark for the whole group of prion diseases, may in reality originate from autophagic vacuoles.

Simultaneous bilateral avulsion fractures of the tibial tuberosity is a rare injury. Since it was first described in 1955, there have been eight similar cases. We have reviewed each of these reports and describe an additional case of a 13-year-old boy, who sustained simultaneous bilateral avulsion fractures of the tibial tuberosity from jumping while playing soccer. Like the previous reports, our patient had a satisfactory result from open reduction and internal fixation of both fractures. Despite being bilateral, these injuries have a low complication rate and good outcome comparable with that of unilateral avulsion fractures of the tibial tuberosity.

Temporal cortex from 14 cases of Alzheimer-type dementia and 6 cases of Down's syndrome, all selected for severe Alzheimer pathology, was homogenised in distilled water, NaOH, or sodium dodecylsulphate (SDS) containing 0.1% β-mercaptoethanol. The homogenates were stained with Congo red, and the neurofibrillary tangles and plaque cores were counted under crossed-polarisation microscopy. The number of tangles and plaque cores in the water-treated extracts was not related to age, sex, postmortem interval or duration of dementia. The number of tangles after extraction in SDS or NaOH, as a percentage of tangles in water-treated extracts, was 57±25 (mean±SD) for 1% SDS, 43±17 for 5% SDS and 37±22 for 0.2 M NaOH. Plaque cores were essentially insoluble in all three agents. The percentage of tangles insoluble in 1% SDS did not correlated with age or post-mortem interval but decreased with increasing duration of dementia. Enhanced tangle solubility with increasing duration of dementia suggests that the nature of tangles changes with time; one possibility is that this reflects transformation of intracellular to extracellular tangles. Paired helical filament (PHF) length and the number of repeats per PHF were measured in electron micrographs of PHF prepared with and without treatment by 1% SDS. There was no significant multimodality of PHF length to suggest that PHF broke at regular intervals. The mean repeat length (PHF length/number of repeats) was greater for PHF isolated in the presence of 1% SDS than in its absence, showing that SDS affects ultrastructure by untwisting PHF. An untwisting process may also occur in vivo producing the straight filaments found, together with PHF, in tangles and neurites.

SummaryThe density of the New Zealand flatworm,Artioposthia triangulata, found between 1993 and 1995 on the surface of the soil under various types of debris scattered in four allotments, was 1–2 m−2. The type of debris did not markedly affect the density of the flatworm and the distribution of the flatworm within the allotment studied was significantly clustered. Fluctuation in numbers of specimens under different sets of compost‐filled plastic sacks varied in a similar manner to one another. The flatworm was most abundant in the upper 100 mm of soil and its egg capsules were most numerous between 100 and 200 mm below the surface. The flatworm was as abundant under the soil surface shelters as it was beneath shelters buried below the soil surface.

The flatworm Artioposthia triangulata was found, from studies using weighted down plastic sheeting, to move predominantly through the soil rather than over it and to use earthworm burrows. Under compost-filled plastic sacks the flatworm was most active at night although its numbers were similar to those during the day. The transfer of specimens into an area covered with weighted plastic sheeting had no lasting effect on their numbers. The flatworm was regularly removed over 6 years from under paving stones, sheets of newspaper and cardboard placed on the ground in a garden. The rise and fall of the numbers of the flatworm under this debris suggest a predator-prey periodicity between the flatworm and earthworms of 3 years.

The distributions of Dodecaceria fimbriata and D. concharum were shown previously to differ slightly within Europe and this was thought to be due to variation in salinity of the sea. In the present study the ability of individuals of the two species with more than 35 chaetose segments to survive a range of dilutions was tested. The percentage survival of individuals from St Abbs (Borders, Scotland) for 24, 48 and 72 h at these salinities appeared to be the same for both species. From this can be inferred that the differences in geographical distributions are independent of the ability of post larval individuals to withstand different salinities. These studies support the argument made earlier that the difference depends upon D. fimbriata reproducing asexually. The fragments produced are, unlike the adults, mobile and more likely to withstand lower salinities than the eggs and larvae of both species. This explanation can account for the presence of D. fimbriata and absence of D. concharum in the upper reaches of the Firth of Forth (Scotland).

The locomotion of Artioposthia triangulata was studied in the laboratory by comparing the relative positions of a series of markers placed on the dorsal side of the body as specimens moved over a variety of types of surfaces. They were found to glide over damp surfaces or to use retrograde peristaltic waves over dry surfaces. These waves passed down the body as three or four muscular bulges with the body held slightly off the ground between each bulge. The specimens travelled faster over dry surfaces than damp ones. Cilia were seen over the entire body surface and were longer and more numerous in the head region and at the sides of the body. Using mark and recapture the distance travelled over 30 days was found for 100 marked specimens released back into the allotment. The greatest distance from the point of release at which a specimen was recaptured after 30 days was 17 m. The speed of locomotion is compared with published data for four other species of terrestrial planarians.

SummaryA chance finding in an Edinburgh allotment was made of a stained carabid beetle larva that had eaten Artioposthiu triungulata previously stained red and released into the allotment during a dispersal experiment. In a pilot laboratory study the flatworm was eaten by larval and adult carabid and staphylinid beetles whereas seven other carnivorous species from five arthropod families did not. In another feeding experiment a carabid and a staphylinid larva each ate several specimens of the flatworm and gained tissue weight over 14 days. The conclusion drawn from these preliminary studies and the field observation is that certain carabid and staphylinid beetles are potential predators of A. triangulata.

A significant negative correlation between the numbers of earthworms and the flatworm was demonstrated in fromalin‐sampled lawns. Their distributions, recorded by a transect from a shrub border where the flatworm is suspected to have been introduced, indicated that predation may lead to earthworm extinction. Two different vermarium designs demonstrated a gradation of earthworm vulmerability to the flatworm due to depth within the soil and burrow width rather than perference for specific earthworm species. A strong correlation between the level of earth worm predation and flatworm movement implied active hunting. A predation rate was found to be 0.67 of an earthworm per flatworm per week with a metabolic conversion rate of 10%.

The distribution ofDodecaceriain northern Europe was found for samples borrowed from museums and other collections.Dodecaceria fimbriatawas present in the coastal waters of mainland Britain and the Continent from the English Channel northwards.Dodecaceria concharumwas only found in British mainland coastal waters and on the French coast at the western end of the English Channel. It was absent where salinities were below ~34%0. The two species were sampled along the Lothian and Borders coasts and the numbers of D.concharumfell with decreasing salinity as the Firth of Forth was approached.Dodecaceria diceriawas found for the first time in the North Sea at depths of 100–200 m. The benthic salinity here is ~35%0.