bluuebunny/crossref_metadata_2025 huggingface dataset:
Induced 1080 Bait-Shyness in Captive Brushtail Possums and Implications for Management.
Authors: Morgan DR , Morriss G , Hickling GJ
Published: June 2005

The probable cause of possums (Trichosurus vulpecula) becoming 'shy' towards 1080 [sodium fluoroacetate] bait, a growing problem in the control of this pest, was determined. Possums captured from North Canterbury, New Zealand, (n = 131) were offered sublethal baits (1 or 2.5 g) followed by lethal (6 g) baits 2 days later. Most possums became bait shy and the proportion becoming shy appeared to be related to the size of the initial sublethal dose. Most of a group of survivors retested after 3 months with toxic pellets were still shy. Shyness was not overcome by changing to a different mask (orange flavour, as opposed to cinnamon flavour) or toxin (brodifacoum), but changing to both a different bait base (carrot) and mask (orange) resulted in most shy possums eating a lethal quantity of bait. Possums therefore appeared to learn to recognise the bait base as the cue for avoiding poisoning. More shy possums than naive possums rejected non-dyed, non-masked, non-toxic pellets, confirming that shy possums recognised the bait base. Green dye appears to act as a secondary cue for avoiding pellets as a higher percentage of 'shy' possums than naive possums rejected dyed baits.
In Vitro Survival Characteristics of Koala Chlamydiae.
Authors: Rush CM , Timms P
Published: June 2005

Extracellular stability of koala chlamydia type I and II, were compared with that of an avian C. psittaci strain. Koala types I and II, as well as avian psittacosis elementary bodies, survived 4 h exposure to solution of pH 4.0-10.0. Koala type I survived best at pH 7.2-7.5 whereas type II preferred pH of 7.0-7.2. Koala type I elementary bodies were inactivated after 5 min at 56 deg C, but at lower temperatures (18-23 deg C) the elementary bodies remained viable for up to 28 days. Koala type I elementary bodies survived for 2-4 days after drying, whereas avian chlamydiae survived for 4-6 days. The koala type I isolate maintained infectivity for cell culture after 3 days' exposure on the leaves of Eucalyptus tereticornis. It is concluded that the koala type I isolate is able to survive extreme conditions for significant time periods and that non-sexual transmission of this chlamydiae may be possible.
Habitat suitability index model for the eastern barred bandicoot, Perameles gunnii
Authors: Reading RP , Clark TW , Seebeck JH , Pearce J
Published: June 2005

The eastern barred bandicoot, Perameles gunnii, is functionally extinct on mainland Australia.
Conservation of this unique taxon is dependent on reintroduction, based on a managed captive-breeding
programme that provides founder animals. Existing reserves at which reintroduction has occurred are too
small to support long-term genetically viable populations. Therefore, reintroductions must be made at a
number of sites and the resulting populations managed as a metapopulation. A habitat-suitability model has
been developed to assess and compare reintroduction sites. This is the first application of this concept to an
Australian species. The model is composed of five variables-size, habitat structure, predation, shape and
security-values of which are combined in a simple relationship to produce comparable mathematical
statements for proposed reintroduction sites. The model has been applied to existing reserves to test their
contribution to the recovery programme.
Population ecology of the Australian frog Crinia signifera: adults and juveniles
Authors: Bull CM , Williamson I
Published: June 2005

A population of the common Australian frog Crinia signifera Girard, 1853 was studied over a 3.5 year
period at a site near Bridgewater in South Australia. In this population, C. signifera are long lived and
iteroparous, with some individual males and females participating in at least four consecutive breeding
seasons. Adult survivorship was high (up to about 70% per annum) for both males and females.
Metamorphosis occurred from October to January and some individuals reached maturity within a year.
However, most individuals reached maturity in the second breeding season following metamorphosis.
Survival of juveniles ranged from 5 to 72% per annum, with individuals emerging early having higher
survival than those that metamorphosed late. However, it was not clear whether increased survival was
associated with early emergence or large size at emergence. The data support the argument that iteroparity
is favoured in situations in which preadult mortality is higher and less predictable than adult mortality.
A Review of the Mantel Test in Dietary Studies: Effect of Sample Size and Inequality of Sample Sizes.
Authors: Luo Jia , Fox BJ
Published: June 2005

The Mantel test has been widely used in many areas of research in biological science since its publication in 1967 and is particularly well suited to use in dietary studies. It is a non-parametric test that has been suggested as appropriate for comparisons when sample sizes are small. The methodology is reviewed, benefits to be gained are examined, and effects of features that have considerable impact (sample-size dependence and sensitivity to inequality of sample size) are considered.
Fluctuations of rodent populations in response to rainfall and fire in a central Australian hummock grassland dominated by Plectrachne schinzii
Authors: Southgate R , Masters P
Published: June 2005

Fluctuations in the composition and abundance of a small-mammal assemblage were studied in a hummock
grassland dominated by Plectrachne schinzii at Watarrka National Park from 1988 to 1993. During this
period an experiment was conducted to examine the short-term effects of fire on the rodents. We caught
three species of rodent (Pseudomys hermannsburgensis, Notomys alexis and Mus domesticus). All species
reached their greatest density in spring 1989 during an exceptionally wet period that extended from mid-
1988 to 1990. P. hermannsburgensis was the most abundant species and showed a 10-fold fluctuation in
numbers over the sample period; N. alexis was the next most abundant species and showed a 5-fold increase
but the population took longer to decline. M. domesticus was recorded only during the period of high
rainfall. The number of M. domesticus was significantly less on the burnt plots than on the unburnt plots.
Neither P. hermannsburgensis nor N. alexis showed significant differences between burnt and unburnt
plots. This study illustrates the impact of rainfall events on the composition and density of small-mammal
populations in spinifex grasslands in central Australia.
Our results lead to the prediction that rodent populations will achieve densities in the order of
10 individuals ha-' or more in regions that experience three consecutive 6-month periods each with rainfall
at 150% of the long-term average. This sequence apparently needs to follow a dry period where rainfall is
no more than 85% of the long-term annual average for two consecutive 12-month periods.
Density estimates of cane toads from native populations based on mark-recapture data
Authors: Lampo M , Bayliss P
Published: June 2005

The cane toad (Bufo marinus) has received considerable attention because of its rapid spread in Australia and
the potential threat it may represent to native species. Although the introduction of pathogens from native
populations is now being considered to control this species, population estimates based on comparable
methods that demonstrate that native populations are in fact less dense than the introduced ones are not
available. Accurate population estimates are necessary to evaluate potential techniques for the control of the
cane toad. We estimated population densities of cane toads over a wide range of habitat types and climate
conditions by means of mark-recapture data. The capture history and location of toads each night were
analysed to explore the validity of some of the assumptions of mark-recapture models. Because migrations,
deaths and recruitment over three nights appear to be unimportant, populations may be legitimately regarded
as closed for that period. However, cane toads seem highly sensitive to disturbance effects due to trapping
andlor handling. Consequently, density estimates based on removal methods seem the most reliable because
they are not sensitive to handling and trapping effects. Similarly, analyses of residuals of regressions between
1-night counts and density estimates suggested that toad nightly activity is affected by the air temperature
during sampling. However, only 60% of the variation in estimated densities can be predicted by 1-night
counts and air temperature. Estimates of population density over a wide range of habitats in South America
were one order of magnitude lower than estimates in Australia. We speculate on the possible factors that may
account for the lower densities in populations in the native range of the species.
Reproductive seasonality of the bush rat (Rattus fuscipes greyi) South Australia
Authors: White RM , Kennaway DJ , Semark RF
Published: June 2005

The reproductive seasonality of the bush rat (Rattus fuscipes greyi) was investigated in Scott Creek
Conservation Park near Adelaide, South Australia, by catch and release trapping conducted at irregular
intervals over a 4-year period in a population of higher density than previously reported for this species. A
seasonal pattern in breeding activity was observed with the production of young in spring and summer
(October-February) with a peak in December. There was seasonal variation in the testicular index of males
with minimal values from April to June. Some animals may have retained the ability to mate throughout the
year but there was no evidence of offspring surviving from any winter matings. Differences were seen in
the timing and intensity of the non-breeding season between years. Possible causes of reproductive
seasonality were seasonal changes in vegetative growth and the abundance of fungi and insects and
predictive cues provided by seasonal changes in ambient temperature and photoperiod.
Habitat Relationships of the Herpetofauna of Remnant Buloke Woodlands of the Wimmera Plains, Victoria.
Authors: Hadden SA , Westbrooke ME
Published: June 2005

Twelve remnants of woodland dominated by buloke (Allocasuarina leuhmannii [A. luehmannii]) in the Wimmera Plains of Victoria, Australia, were investigated to evaluate the habitat relationships of the herpetofauna. Reptiles and amphibians were assessed by pitfall trapping, systematic searching and recording of frog vocalisations. Site characteristics that are likely to affect the species richness of herpetofauna in buloke remnants were determined. Nine reptile and 4 amphibian species were recorded from 6048 trap-nights and 216 h of systematic searching. A significant relationship was found between the herpetofaunal and reptile species richness and the level of past grazing pressure and vegetation understorey structure. No correlation was found between herpetofaunal species richness and the area of the remnant. Species richness of amphibians was best predicted by soil type. Habitat features associated with each species are presented. Implications for the management of remnant buloke woodlands and their herpetofauna are discussed and recommendations made.
Home ranges, time budgets and food-tree use in a high-density tropical population of greater gliders, Petauroides volans minor (Pseudocheiridae : Marsupialia)
Authors: Comport SS , Ward SJ , Foley WJ
Published: June 2005

The socio-ecology of Petauroides volans has been studied for subtropical and temperate populations, but
not for the northern tropical subspecies, Petauroides volans minor. Data on the effects of a high population
density on home ranges, time budgets and food-tree use were obtained by means of radio-telemetry. Three
techniques were used to estimate home-range area (kernel, MCP and harmonic mean) and the kernel
method was preferred. Estimates of home-range area (defined by the 95% kernel) gave mean values of 2.5
and 1.3 ha for males and females, respectively. Broad overlap of home ranges of males was observed,
which has not been reported previously for populations of P. volans. Behaviour patterns for males and
females were similar to those in previous studies, although the mating system may differ, possibly because
of the high population density. Dietary patterns were similar to those previously reported for this species,
the most important food items being young leaves and flower buds of particular eucalypt species, notably
Eucalyptus acmenoides.
Use of External Mound Structures as Indicators of the Presence of the Pebble-Mound Mouse, Pseudomys Chapmani, in Mound Systems.
Authors: Anstee SD
Published: June 2005

Pebble mounds constructed by Pseudomys chapmani are found throughout the Pilbara region of Western Australia. Studies have shown that not all mounds within an area are occupied by P. chapmani at any one time. This paper reports a system of scoring pebble mounds on their external features to determine whether the mound is occupied by P. chapmani. Active mounds were found to have a significantly higher index score than inactive mounds. The scoring system reported here is an effective predictor of the presence of P. chapmani in pebble mounds.
The Effect of an Intensive Shooting Exercise From a Helicopter on the Behaviour of Surviving Feral Pigs.
Authors: Dexter N
Published: June 2005

The hypothesis that disturbance from a shooting exercise using a helicopter will influence the behaviour of
surviving feral pigs, Sus scrofa, was tested on a population of radio-collared feral pigs in north-western
New South Wales. No significant differences existed in hourly distance moved by pigs, diel variation in
distance moved by pigs, or home-range size of pigs, between a radio-tracking session conducted
immediately before a shooting exercise from a helicopter and a radio-tracking session conducted during and
after the exercise. The position of the home ranges of feral pigs did not appear to be affected by the
shooting exercise, although several radio-collared feral pigs moved into and out of the study area between
tracking sessions. Overall, the results suggest that the disturbance caused by shooting has little effect on the
behaviour of surviving feral pigs.
Ground-penetrating radar: a technique for investigating the burrow structures of fossorial vertebrates
Authors: Stott P
Published: June 2005

Ground-penetrating radar (GPR) was tested as a technique to map the subterranean tunnels of the European
rabbit, as a representative fossorial vertebrate. The technique readily located tunnels separated by at least
1 m in a dry coarse compacted sandy soil, but images of tunnels less than 0.4 m apart were fused. GPR was
of no use in a highly saline, sandy light-clay soil. GPR is a non-invasive technique by which the routes of
isolated blind-ending tunnels of any length can be ascertained, even in unstable soil.
Use of Nest Trees by the Mountain Brushtail Possum (Trichosurus Caninus) (Phalangeridae: Marsupialia). Ii. Characteristics of Occupied Trees.
Authors: Lindenmayer DB , Welsh A , Donnelly CF , Cunningham RB
Published: June 2005

The use of den trees by a population of the mountain brushtail possum (Trichosorus caninus) in forests of mountain ash (Eucalyptus regnans) at Cambarville, in the central Highlands of Victoria, is described. Relationships are explored between the use of trees with hollows by 16 radio-tracked T. caninus and a range of measures of the morphological characteristics of the 113 different den trees they occupied. The results of the analyses indicate that the most used trees contained a relatively large number of cavities and were not surrounded by dense vegetation. Male possums were found most frequently in the southern part of the 35-ha study area, and females were found most often in the northern part.
Waterbird surveys of the Middle Fly River floodplain, Pap New Guinea
Authors: Halse SA , Pearson GB , Jaensch RP , Kulmoi P , Gregory P , Kay WR , Storey AW
Published: June 2005

In total, 58 species of waterbird were recorded on the grassed floodplain of the Middle Fly during surveys
in December 1994 and April 1995. The floodplain is an important dry-season habitat both in New Guinea
and internationally, with an estimated (+/- s.e.) 587249 +/- 62741 waterbirds in December. Numbers
decreased 10-fold between December and April to 54914 +/- 9790: the area was less important during the
wet season when it was more deeply inundated. Only magpie geese, comb-crested jacanas and spotted
whistling-ducks were recorded breeding on the floodplain. The waterbird community was numerically
dominated by fish-eating species, especially in December. Substantial proportions of the populations of
many species that occurred on the Middle Fly in December were probably dry-season migrants from
Australia, suggesting that migration across Torres Strait is important to the maintenance of waterbird
numbers in both New Guinea and Australia.
Dingoes in Queensland, Australia: skull dimensions and the indenity of wild canids
Authors: Woodall PF , Pavlov P , Twyford KL
Published: June 2005

More than 100 canid skulls lodged in the Queensland Museum were measured and analysed to determine
the frequency of dingoes, Canis lupus dingo, in some wild populations of canids in Queensland. The
highest frequency of dingoes (95%) was found in a sample from Augathella, central Queensland, and the
highest frequency of dogs and hybrids (50%) was found in south-eastern Queensland. Fraser Island had a
relatively low frequency of hybrids (17%), which were largely confined to the southern half of the island.
Skull measurements from Augathella were generally significantly larger than those from central Australia,
but there were few significant differences in size within Queensland.
Feeding Behaviour and Food Availability of the Yellow-Bellied Glider in North Queensland.
Authors: Quin D , Goldingay R , Churchill S , Engel D
Published: June 2005

The diet of the yellow-bellied glider (Petaurus australis) was examined at a site in north Queensland by extensive observation of individuals from 10 glider groups. The diet was assessed in four seasons over 12 months by collating large numbers of qualitative feeding observations and by analysis of faeces. Data were also collected on flowering and bark shedding in the forest. Sap feeding accounted for more than 80% of the feeding observations throughout the year. Nectar and pollen of eucalypts (Eucalyptus spp.) and banksias (Banksia spp.) accounted for much of the remainder of the diet although arthropods and honeydew were present in spring and summer. Faecal analysis was based on much smaller sample sizes but confirmed the qualitative result obtained from direct observations. It also revealed the presence of a wide variety of pollen types. Many of these could be attributed to incidental ingestion but at least six rain forest genera were moderately common in faeces, which is consistent with observations of brief and infrequent visits by gliders to these trees. Examination of eucalypt, banksia and other pollen types showed that 60-70% of pollen was devoid of cell contents, supporting earlier suggestions that gliders obtained protein from pollen digestion, but at this site also from harvesting arthropods. This study confirms the dependence of the yellow-bellied glider in north Queensland on the sap of the red stringybark (Eucalyptus resinifera) and that conservation of the yellow-bellied glider is intimately associated with the management of this tree species. The use of various species for nectar and pollen suggests that the yellow-bellied glider may be an important pollinator in these forests. Moreover, sap from the wounds created by gliders is used by a range of other animal species. These observations suggest that the yellow-bellied glider is likely to be a keystone species in the open-forest ecosystems of north Queensland and that it deserves special emphasis in management.
Population and Habitat Characteristics of the Golden Bandicoot (Isoodon Auratus) on Marchinbar Island, Northern Territory.
Authors: Southgate R , Palmer C , Adams M , Masters P , Triggs B , Woinarski J
Published: June 2005

The presence of the golden bandicoot (Isoodon auratus) on Marchinbar Island off north-eastern Arhemland, Northern Territory, was confirmed by means of morphological features, hair characteristics and allozyme electrophoresis. Evidence of I. auratus was found at most points sampled along the 50-km length of Marchinbar Island. The species showed a strong habitat preference for low heath or shrubland on sand or sandstone, a combination that covers some 70% or 140 km2 of the island. No sign was found in the remaining forest/thicket or strand/Casuarina habitat. No major changes occurred in the distribution of the species between seasons, and individuals maintained overlapping home ranges of similar size, about 10-35 ha. Considerable variation occurred in the characteristics of sites used for daytime shelter, including rocky shelves, shrubs and Triodia hummocks. Different shelter sites were frequently occupied on consecutive days. Foraging sites were sparsely vegetated and diet consisted mainly of a broad range of invertebrates. It is likely that the rocky habitat of Marchinbar Island is sufficiently dissected to ensure the availability of suitable habitat without the necessity of a managed fire regime. The bandicoot population on Marchinbar Island has at least two terrestrial predators, wild dogs (Canis familiaris) and carpet pythons (Morelia spilota). The current predation pressure is not considered to threaten the existence of the bandicoots on the island; however, the addition of another predator species (e.g. the feral cat) may create unacceptable conditions.
Trends in numbers and changes in the distribution of feral goats (capra hircus) in the South Australia pastoral zone
Authors: Pople AR , Grigg GC , Cairns SC , Alexander P , Beard LA , Henzell RP
Published: June 2005

Trends in numbers and changes in the distribution of feral goats in the South Australian pastoral zone
(217300 km*2) during 1978-94 were determined by winter aerial surveys. Only the presence or absence of
goats on sample units was scored between 1978 and 1988. On the assumption of a random distribution of
goat groups, these indices were transformed to densities of goat groups. Between 1989 and 1994 actual goat
numbers were recorded on each sample unit, allowing goat density to be estimated. Goats were consistently
at their highest densities in the south-east of the pastoral zone, a region dominated by open mallee scrub and
chenopod shrubland. Densities of goat groups fluctuated from a low in 1984, following a drought, to a peak
in 1990, following above-average rainfalls, when there were an estimated 193700 +/- 29600 goats in the
pastoral zone. This estimate is conservative because it is uncorrected for the visibility bias associated with
sighting groups and undercounting their sizes. The estimate also excludes the Flinders Ranges for which a
similar number of goats has been estimated.
Changes in the abundance of New Zealand fur seals, Arctocephalus forsteri, on the Neptune Islands, South Australia
Authors: Shaughnessy PD , Stirling I , Dennis TE
Published: June 2005

The South Neptune Island group is a well-known site for the New Zealand fur seal, Arctocephalus forsteri.
A survey of seals in South Australia and Western Australia in the 1989-90 summer indicated that colonies
on the South Neptunes and the adjacent North Neptunes group contained half of the breeding population in
Australia.
The abundance of pups at the South Neptune group was determined in four breeding seasons: 1969-70,
1988-89, 1989-90 and 1992-93. The population on Main Island increased at an exponential rate of
r = 0.053 (equivalent to 5.4% per annum) between the first two surveys: counts of pups increased from 487
to 1333, and the breeding area expanded to include several new colonies. Mark-recapture estimates of pup
numbers in the two largest colonies in 1989-90 and 1992-93 did not differ statistically. Rates of increase in
individual colonies over the 19 or 20 years from 1970 ranged from r = 0.031 (3.1%) to r = 0.256 (29.2%).
On the South Neptune Islands, the estimate of pup abundance in the most recent survey (1992-93) was
1916, on the basis of mark-recapture in most colonies and of counting in a few small ones.
On the North Neptune Islands, the estimate of pup abundance in 1992-93 was 2756, on the basis of
mark-recapture in most colonies. By applying a multiplier of 4.9 to convert pup numbers to an estimate of
abundance of the whole population, estimates of 9400 and 13500 fur seals were obtained for the South
Neptune and North Neptune Islands in 1992-93, respectively. These estimates provide a firm foundation
for comparisons in future years.
Highly effective phosphorylation by G protein-coupled receptor kinase 7 of light-activated visual pigment in cones
Authors: Tachibanaki Shuji , Arinobu Daisuke , Shimauchi-Matsukawa Yoshie , Tsushima Sawae , Kawamura Satoru
Published: June 2005

Cone photoreceptors show briefer photoresponses than rod photoreceptors. Our previous study showed that visual pigment phosphorylation, a quenching mechanism of light-activated visual pigment, is much more rapid in cones than in rods. Here, we measured the early time course of this rapid phosphorylation with good time resolution and directly compared it with the photoresponse time course in cones. At the time of photoresponse recovery, almost two phosphates were incorporated into a bleached cone pigment molecule, which indicated that the visual pigment phosphorylation coincides with the photoresponse recovery. The rapid phosphorylation in cones is attributed to very high activity of visual pigment kinase [G protein-coupled receptor kinase (GRK) 7] in cones. Because of this high activity, cone pigment is readily phosphorylated at very high bleach levels, which probably explains why cone photoresponses recover quickly even after a very bright light and do not saturate under intense background light. The high GRK7 activity is brought about by high content of a highly potent enzyme. The expression level of GRK7 was 10 times higher than that of rod kinase (GRK1), and the specific activity of a single GRK7 molecule was ≈10 times higher than that of GRK1. The specific activity of GRK7 is the highest among the GRKs so far known. Our result seems to explain the response characteristics of cone photoreceptors in many aspects, including the nonsaturation of the cone responses during daylight vision.
Production of infectious human papillomavirus independently of viral replication and epithelial cell differentiation
Authors: Pyeon Dohun , Lambert Paul F. , Ahlquist Paul
Published: June 2005

Papillomaviruses are small DNA viruses that are associated with benign and malignant epithelial lesions, including >95% of cervical cancers and ≈20% of head and neck cancers. Because papillomavirus replication and virion production are tied to epithelial cell differentiation, infectious papillomavirus virion production has been limited to cumbersome organotypic cultures and mouse xenografts. Consequent difficulties in obtaining useful amounts of wild-type or mutant human papillomavirus (HPV) virions have greatly limited studies on many aspects of papillomavirus biology. To overcome these limitations, we developed a system to encapsidate the full-length papillomaviral genome into infectious virions, independently of viral DNA replication and epithelial differentiation. This transient-transfection-based system produces >1,000 times more infectious virus per cell culture dish than the much more labor-intensive organotypic culture. Furthermore, we show that this method allows the facile generation of infectious particles containing wild-type, mutant, or chimeric papillomaviral genomes, overcoming barriers to studying many facets of replication, host interactions, and vaccine and drug development, which has been limited by the insufficient availability of infectious virions.
Bone turnover and nutritional status in Crohn's disease: relationship to circulating mononuclear cell function and response to fish oil and antioxidants
Authors: Trebble T. M.
Published: June 2005

Crohn's disease is associated with osteoporosis, malnutrition and altered function of peripheral blood mononuclear cells (PBMC). The responses of circulating immune cells and extra-intestinal manifestations to increased inflammatory activity and to modulation by dietary supplementation are uncertain. The relationships between disease status, bone turnover and body mass and composition, PBMC function and fatty acid availability have been investigated in patients with Crohn's disease. The availability of n-3 and n-6 PUFA is altered in adult patients and interferon (IFN)-γ production by PBMC is lower. Increased inflammatory activity is associated with increased bone resorption in adult patients and decreased body mass in paediatric patients. In healthy male subjects there is a proportionate relationship between supplementary intake of EPA and DHA (0.3–2.0 g as fish oil/d) in combination with antioxidants (vitamins A, C and E and Se) and incorporation into plasma phospholipids and PBMC, and a non-linear relationship with PBMC synthesis of TNF-α, IL-6 and prostaglandin E2 (decrease) and IFN-γ (increase). In adults with Crohn's disease high-dose fish oil (2.7 g EPA+DHA/d) in combination with antioxidants (vitamins A, C and E and Se) increases the EPA and DHA content of PBMC and decreases the production of IFN-γ by PBMC, but is not associated with effects on bone turnover or nutritional status.
Vitamin D status and its relationship with parathyroid hormone and bone mineral status in older adolescents
Authors: Willett Alexis M.
Published: June 2005

Osteoporosis is an important contributor to the global burden of disease, and in the UK alone results in one in three women and one in twelve men aged >50 years experiencing a fragility fracture. Optimising peak bone mass in early adulthood is thought to reduce osteoporosis risk by offsetting bone losses in later life. Ensuring sufficient vitamin D status (measured as 25-hydroxyvitamin D (25OHD) in plasma), among other factors, is believed to facilitate the achievement of optimum peak bone mass. Lower 25OHD is associated with a higher plasma concentration of parathyroid hormone (PTH). As PTH is associated with increased bone turnover and bone loss, maintenance of sufficient 25OHD is thought to have a protective effect on bone health. However, there is a lack of consensus internationally on what constitutes an optimum 25OHD concentration, and values between 30 and 80 nmol/l have been suggested. These values have been based on findings from various studies in adults in which PTH has been observed to plateau at a 25OHD concentration of >30 nmol/l; however, not all studies have found such a plateau. Although studies in younger adolescents (14–16 years) have shown an inverse relationship between PTH and 25OHD, the concentration of 25OHD required for achievement of optimum peak bone mass is unknown. The present review examines the evidence defining vitamin D insufficiency thresholds, and the relevance of such thresholds to adolescent bone health.
Influence of triacylglycerol structure of stearic acid-rich fats on postprandial lipaemia
Authors: Berry Sarah E. E. , Sanders Thomas A. B.
Published: June 2005

Exaggerated postprandial lipaemia may increase the risk of CHD by contributing to both thrombotic and atherogenic processes. Previous research has focused on the quantity and composition of dietary fat, whereas the effect of triacylglycerol (TAG) structure on postprandial lipaemia and clotting factor VII activity has received little attention. TAG with similar fatty acid composition may have different biochemical and physical properties that are dependent on their TAG structure, and these differences may affect lipid metabolism. Recent findings suggest that differences in the physical properties of stearic acid-rich fats are associated with differences in postprandial lipaemia, and may play an important role in determining their rates of digestion and absorption.
Actin Depolymerization Disrupts Tight Junctions via Caveolae-mediated Endocytosis
Authors: Shen Le , Turner Jerrold R.
Published: June 2005

The tight junction (TJ) determines epithelial barrier function. Actin depolymerization disrupts TJ structure and barrier function, but the mechanisms of this effect remain poorly understood. The goal of this study was to define these mechanisms. Madin-Darby canine kidney (MDCK) cells expressing enhanced green fluorescent protein-, enhanced yellow fluorescent protein-, or monomeric red fluorescent protein 1-fusion proteins of β-actin, occludin, claudin-1, ZO-1, clathrin light chain A1, and caveolin-1 were imaged by time-lapse multidimensional fluorescence microscopy with simultaneous measurement of transepithelial electrical resistance (TER). Actin depolymerization was induced with latrunculin A (LatA). Within minutes of LatA addition TER began to fall. This coincided with occludin redistribution and internalization. In contrast, ZO-1 and claudin-1 redistribution occurred well after maximal TER loss. Occludin internalization and TER loss, but not actin depolymerization, were blocked at 14°C, suggesting that membrane traffic is required for both events. Inhibition of membrane traffic with 0.4 M sucrose also blocked occludin internalization and TER loss. Internalized occludin colocalized with caveolin-1 and dynamin II, but not with clathrin, and internalization was blocked by dominant negative dynamin II (K44A), but not by Eps15Δ95-295 expression. Inhibition of caveolae-mediated endocytosis by cholesterol extraction prevented both LatA-induced TER loss and occludin internalization. Thus, LatA-induced actin depolymerization causes TJ structural and functional disruption by mechanisms that include caveolae-mediated endocytosis of TJ components.
Genetic, Genomic, and Functional Analysis of the Granule Lattice Proteins inTetrahymenaSecretory Granules
Authors: Cowan Andrew T. , Bowman Grant R. , Edwards Kyle F. , Emerson J. J. , Turkewitz Aaron P.
Published: June 2005

In some cells, the polypeptides stored in dense core secretory granules condense as ordered arrays. In ciliates such as Tetrahymena thermophila, the resulting crystals function as projectiles, expanding upon exocytosis. Isolation of granule contents previously defined five Granule lattice (Grl) proteins as abundant core constituents, whereas a functional screen identified a sixth family member. We have now expanded this screen to identify the nonredundant components required for projectile assembly. The results, further supported by gene disruption experiments, indicate that six Grl proteins define the core structure. Both in vivo and in vitro data indicate that core assembly begins in the endoplasmic reticulum with formation of specific hetero-oligomeric Grl proprotein complexes. Four additional GRL-like genes were found in the T. thermophila genome. Grl2p and Grl6p are targeted to granules, but the transcripts are present at low levels and neither is essential for core assembly. The ΔGRL6 cells nonetheless showed a subtle change in granule morphology and a marked reduction in granule accumulation. Epistasis analysis suggests this results from accelerated loss of ΔGRL6 granules, rather than from decreased synthesis. Our results not only provide insight into the organization of Grl-based granule cores but also imply that the functions of Grl proteins extend beyond core assembly.
Cell Cycle-dependent Dynamics and Regulation of Mitotic Kinesins inDrosophilaS2 Cells
Authors: Goshima Gohta , Vale Ronald D.
Published: June 2005

Constructing a mitotic spindle requires the coordinated actions of several kinesin motor proteins. Here, we have visualized the dynamics of five green fluorescent protein (GFP)-tagged mitotic kinesins (class 5, 6, 8, 13, and 14) in live Drosophila Schneider cell line (S2), after first demonstrating that the GFP-tag does not interfere with the mitotic functions of these kinesins using an RNA interference (RNAi)-based rescue strategy. Class 8 (Klp67A) and class 14 (Ncd) kinesin are sequestered in an active form in the nucleus during interphase and engage their microtubule targets upon nuclear envelope breakdown (NEB). Relocalization of Klp67A to the cytoplasm using a nuclear export signal resulted in the disassembly of the interphase microtubule array, providing support for the hypothesis that this kinesin class possesses microtubule-destabilizing activity. The interactions of Kinesin-5 (Klp61F) and -6 (Pavarotti) with microtubules, on the other hand, are activated and inactivated by Cdc2 phosphorylation, respectively, as shown by examining localization after mutating Cdc2 consensus sites. The actions of microtubule-destabilizing kinesins (class 8 and 13 [Klp10A]) seem to be controlled by cell cycle-dependent changes in their localizations. Klp10A, concentrated on microtubule plus ends in interphase and prophase, relocalizes to centromeres and spindle poles upon NEB and remains at these sites throughout anaphase. Consistent with this localization, RNAi analysis showed that this kinesin contributes to chromosome-to-pole movement during anaphase A. Klp67A also becomes kinetochore associated upon NEB, but the majority of the population relocalizes to the central spindle by the timing of anaphase A onset, consistent with our RNAi result showing no effect of depleting this motor on anaphase A. These results reveal a diverse spectrum of regulatory mechanisms for controlling the localization and function of five mitotic kinesins at different stages of the cell cycle.
Targeting of Tsc13p to Nucleus–Vacuole Junctions: A Role for Very-Long-Chain Fatty Acids in the Biogenesis of Microautophagic Vesicles
Authors: Kvam Erik , Gable Kenneth , Dunn Teresa M. , Goldfarb David S.
Published: June 2005

TSC13 is required for the biosynthesis of very-long-chain fatty acids (VLCFAs) in yeast. Tsc13p is a polytopic endoplasmic reticulum (ER) membrane protein that accumulates at nucleus–vacuole (NV) junctions, which are formed through Velcro-like interactions between Nvj1p in the perinuclear ER and Vac8p on the vacuole membrane. NV junctions mediate piecemeal microautophagy of the nucleus (PMN), during which bleb-like portions of the nucleus are extruded into invaginations of the vacuole membrane and degraded in the vacuole lumen. We report that Tsc13p is sequestered into NV junctions from the peripheral ER through Vac8p-independent interactions with Nvj1p. During nutrient limitation, Tsc13p is incorporated into PMN vesicles in an Nvj1p-dependent manner. The lumenal diameters of PMN blebs and vesicles are significantly reduced in tsc13-1 and tsc13-1 elo3-Δ mutant cells. PMN structures are also smaller in cells treated with cerulenin, an inhibitor of de novo fatty acid synthesis and elongation. The targeting of Tsc13p-GFP into NV junctions is perturbed by cerulenin, suggesting that its binding to Nvj1p depends on the availability of fatty acid substrates. These results indicate that Nvj1p retains and compartmentalizes Tsc13p at NV junctions and that VLCFAs contribute to the normal biogenesis of trilaminar PMN structures in yeast.
The Cotranslational Maturation of the Type I Membrane Glycoprotein Tyrosinase: The Heat Shock Protein 70 System Hands Off to the Lectin-based Chaperone System
Authors: Wang Ning , Daniels Robert , Hebert Daniel N.
Published: June 2005

The maturation of eukaryotic secretory cargo initiates cotranslationally and cotranslocationally as the polypeptide chain emerges into the endoplasmic reticulum lumen. Here, we characterized the cotranslational maturation pathway for the human type I membrane glycoprotein tyrosinase. To recapitulate the cotranslational events, including glycosylation, signal sequence cleavage, chaperone binding, and oxidation, abbreviated transcripts lacking a stop codon were in vitro translated in the presence of semipermeabilized melanocyte membranes. This created a series of ribosome/translocon-arrested chains of increasing lengths, simulating intermediates in the cotranslational folding process. Initially, nascent chains were found to associate with the heat shock protein (Hsp) 70 family member BiP. As the nascent chains elongated and additional glycans were transferred, BiP binding rapidly decreased and the lectin-based chaperone system was recruited in its place. The lectin chaperone calnexin bound to the nascent chain after the addition of two glycans, and calreticulin association followed upon the addition of a third. The glycan-specific oxidoreductase ERp57 was cross-linked to tyrosinase when calnexin and calreticulin were associated. This timing coincided with the formation of disulfide bonds within tyrosinase and the cleavage of its signal sequence. Therefore, tyrosinase maturation initiates cotranslationally with the Hsp70 system and is handed off to the lectin chaperone system that first uses calnexin before calreticulin. Interestingly, divergence in the maturation pathways of wild-type and mutant albino tyrosinase can already be observed for translocon-arrested nascent chains.
In vitro
apatite formation on organic polymers modified with a silane coupling reagent
Authors: Shirosaki Yuki , Kubo Masaaki , Takashima Seisuke , Tsuru Kanji , Hayakawa Satoshi , Osaka Akiyoshi
Published: June 2005

γ-Methacryloxypropyltrimethoxysilane (γ-MPS) was grafted to high-density polyethylene, polyamide and silicone rubber substrates by the emulsion polymerization procedure in order to provide these organic polymers with
in vitro
apatite-forming ability. The contact angles towards distilled water of the γ-MPS-grafted specimens were lower than those of the original organic polymer specimens, indicating that the grafted substrates were more hydrophilic. The
in vitro
apatite formation in a simulated body fluid (Kokubo solution) was confirmed for several of the γ-MPS-grafted specimens.
Numerical simulation of boundary-layer disturbance evolution
Authors: Davies Christopher
Published: June 2005

The use of numerical simulations to study the development of boundary-layer disturbances is illustrated for a number of different incompressible flow configurations. These include cases where the disturbances are generated by, or interact with, flow-control devices in the form of compliant panels, suction slots and microelectromechanical systems actuators. The velocity–vorticity system of governing equations used for the simulations is reviewed, along with the numerical discretization.
Interfirm Modularity and Its Implications for Product Development*
Authors: Staudenmayer Nancy , Tripsas Mary , Tucci Christopher L.
Published: June 2005

Industries characterized by interfirm modularity, in which the component products of different firms work together to create a system, are becoming increasingly widespread. In such industries, the existence of a common architecture enables consumers to mix and match the products of different firms. Industries ranging from stereos, cameras, and bicycles to computers, printing, and wireless services are now characterized by interfirm modularity. While the increasing presence of this context has been documented, the implications for the product development process remain underdeveloped. For the present study, in‐depth field‐based case studies of seven firms experiencing an environment of interfirm modularity were conducted in order to deepen understanding of this important phenomenon. What unique challenges did this context pose and why? What solutions did firms experiment with, and which seemed to work?

Based on an inductive process of data analysis from these case studies, three primary categories of challenges raised by this environment were identified. First, firms were frustrated at their lack of control over the definition of their own products. The set of features and functions in products were constrained to a great extent by an architecture that the firm did not control. Second, while an environment of interfirm modularity should in theory eliminate interdependencies among firms since interfaces between products are defined ex‐ante, the present study found, ironically, that interdependencies were ubiquitous. Interdependencies continually emerged throughout the product development process, despite efforts to limit them. Third, firms found that the quantity and variegated nature of external relationships made their management exceedingly difficult. The sheer complexity was daunting, given both the size of the external network as well as the number of ties per external collaborator. Partners with whom control over the architecture was shared often had divergent interests—or at least not fully convergent interests.

The solutions to these challenges were creative and in many cases counter to established wisdom. For instance, research has suggested many ways for a firm to influence architectural standards. While the firms in the present sample followed some of this advice, they also focused on a more neglected aspect of architecture—the compliance and testing standards that accompany modules and interfaces. By concentrating their efforts in a different area, even smaller firms in this sample were able to have some influence. Instead of focusing on the elimination of interdependencies, it was found that firms benefited from concentrating on the management of interdependencies as they emerged. Finally, while layers of management and “bureaucracy” are often viewed as unproductive, these firms found that adding structure, through positions such as Relationship Manager, was highly beneficial in handling the coordination and control of a wide range of external relationships.
Predictors of the Survival of Innovations*
Authors: Åstebro Thomas , Michela John L.
Published: June 2005

This article examines the impact of key success factors on the survival of innovations that have reached the market and were developed by inventors outside of established organizations. It is of interest to learn which characteristics predict, at an early stage, the duration of the innovation's length of sales, because this duration is important to the financial success of new products. A focus on survival also can contribute conceptual clarity to the study of new product development. This study uses the Inventor's Assistance Program (IAP) at the Canadian Innovation Centre (CIC) in Waterloo, Canada, as the source of data. The CIC is a not‐for‐profit agency that provides various services to foster business development involving innovative products and services. Analysts in the IAP evaluate a specific product idea or invention on 37 dimensions before it has reached the market. The data for the present study involved these 37 variables evaluated each with a three‐point linguistic scale. As the evaluations of the criteria are subjective, they might be argued to contain inaccuracies compared to objective data. On the other hand, the analysts use multiple related measures of concepts that have been shown to increase predictive accuracy. The use of experts who are unrelated to the projects avoids decision‐making biases potentially associated with project managers' assessment of their own projects, such as unrealistic optimism. The recording of the expert evaluations of the ideas before they reached the market and independent of the measure of success, rather than using post‐project completion evaluations, eliminates measurement biases such as hindsight bias and common method variance bias. Identifying information was used in these records to conduct a telephone survey of the inventors. An exploratory method of data analysis is identified and used that distinguishes research‐appropriate constructs and their indicators in these data. Cluster analysis was performed, and survival regression correlated cluster scores with survival. Three variables were found to significantly affect survival: anticipated stable demand, price required for profitability, and technical product maturity. In addition, the degree of competition had a marginally significant effect. Because these variables can be assessed at an early stage of an inventions' development, the expected survival time for a specific invention may be computed by entering these assessment values into the described survival model. Then this and other information may be used to compute the expected return of an invention.