bluuebunny/crossref_metadata_2025 huggingface dataset:
The diet of the musky rat-kangaroo, Hypsiprymnodon moschatus, a rainforest specialist
Authors: Dennis A. J.
Published: September 2002

Musky rat-kangaroos inhabit tropical rain forest and are Australia's smallest and most primitive member of the Macropodoidea. Their ecology and behaviour has remained unknown in the wild until this study, and is expected to be representative of an early unspecialised macropodoid lifestyle. I examined the diet of musky rat-kangaroos using a range of methods including microscopic examination of faecal pellets, direct observation, spool-and-line tracking and examinion of teeth marks left in fruit on the forest floor. Musky rat-kangaroos are frugivores and consumed the fruits of 40 species of plant on a 9-ha rainforest site in Wooroonooran National Park, Queensland. They ate primarily the flesh of fruits, but 11% of seeds from approximately half the species of fruit consumed were also eaten. While musky rat-kangaroos ate fruit from all size classes, they preferred large, fleshy drupes and seeds with a moderate to soft seed coat but without latex present. Invertebrates and the epigeal fruiting bodies of some agaric fungi were the other significant dietary components and these showed seasonal patterns of significance in the diet and differential use by adults and subadults. Musky rat-kangaroos eat the lowest-fibre diet of all animals in the superfamily Macropodoidea and their size and digestive tract reflect this unspecialised, and probably ancestral, diet.
Edge effects on the distribution and abundance of birds in a southern Victorian forest
Authors: Berry Lainie
Published: September 2002

An important consequence of habitat fragmentation for wildlife communities is
the effect of an increase in the ratio of habitat edge to interior. This study
compares the bird communities at forest/farmland edges and in forest
interior at Bunyip State Park, Victoria. Overall, there was a significantly
higher number of bird species and individuals in forest edge than in forest
interior sites. The greater diversity of species at edge sites appeared to be
due to an increase in forest-edge specialists, as opposed to an influx of
open-country species. Four bird species: the white-throated treecreeper
(Cormobates leucophaeus), the superb fairy-wren
(Malurus cyaneus), the grey shrike-thrush
(Colluricincla harmonica) and the grey fantail
(Rhipidura fuliginosa) were significantly more abundant
in edge sites. There were no species that were significantly more abundant in
interior sites. Differences between the bird communities in edge and interior
sites were attributed to increased foraging opportunities in the open country
adjacent to forest edges.
Dietary overlap between the burrowing bettong (Bettongia lesueur) and the European rabbit (Oryctolagus cuniculus) in semi-arid coastal Western Australia
Authors: Robley Alan J. , Short Jeff , Bradley Stuart
Published: September 2002

The diets of burrowing bettongs and European rabbits were studied on Heirisson
Prong at Shark Bay, Western Australia, over two winters (1996 and 1997) and
two summers (1996/97 and 1997/98). This was during a period when the
rabbit population was increasing to high levels and projected foliage cover
was decreasing, presenting environmental conditions likely to exacerbate
competition. The diets of bettongs and rabbits were significantly different in
both winter and summer. The mean overlap in diets shifted from 43% in
winter to 56% in summer. Bettongs were able to vary their diet in
response to environmental conditions while rabbits perished in large numbers
during the second summer. The winter diet of bettongs included hypogeal fungi
(19–23%), fruit and forbs; their summer diet included seed, stem,
and the foliage of shrubs. Grasses dominated the winter diet of rabbits;
forbs, ‘other shrub species’, and browse from shrubs were included
also. In summer, rabbits ate mainly roots (30–35%), browse and
stems from shrub species. Bettongs ate food items that rabbits did not, and
were better able to use common resources. The lack of significant dietary
overlap between rabbits and bettongs suggests minimal competition at times of
potentially limited food resources. These results suggest that rabbits alone
are unlikely to have brought about the mainland extinction of bettongs.
The conservation status of rodents in the monsoonal tropics of the Northern Territory
Authors: Woinarski J. C. Z.
Published: September 2002

The rodent fauna of the monsoonal tropics of the Northern Territory comprises
23 native species and two introduced species. Three species
(Zyzomys maini, Z. palatalis and
Pseudomys calabyi) are endemic to the area, and four
species (Pseudomys hermannsburgensis,
P. desertor, P. johnsoni and
Notomys alexis) enter the area only on its southern
(arid) fringe. The rodent fauna is closely related to that of the Kimberley,
Western Australia.
Distribution maps for all species are given. One species
(Z. palatalis) has an extremely restricted range and is
regarded as critically endangered. The lack of information on the distribution
and abundance of rodents in general in this area is evident in the national
classification of five of its species (Xeromys myoides,
Mesembriomys macrurus,
Notomys aquilo, Pseudomys desertor
and Pseudomys johnsoni) as Insufficiently Known. The two
introduced rodents (Mus domesticus and
Rattus rattus) are virtually restricted to urban and
highly modified areas, although R. rattus also occurs on
one uninhabited island.
In contrast to that of much of the rest of Australia, this rodent fauna has
apparently retained its full complement of species since European
colonisation. This enduring legacy is attributable largely to the relatively
limited modification of its environments. However, three species
(Mesembriomys macrurus,
Rattus tunneyi and
Conilurus penicillatus) appear to be declining. The
pattern of decline in these species, and in the mammal fauna generally, is
obscured by the very limited historical data. However, declines appear most
pronounced in the cattle country of the Victoria River District and Gulf
regions.
Priorities for the management of this rodent fauna include survey of poorly
known areas, survey for poorly known species, monitoring of rodent
communities, and landscape-wide management of the three pervasive processes
with probably greatest impacts – fire, grazing and feral predators.
Population structure and dynamics of sympatric house mice, Mus domesticus, and Lakeland Downs short-tailed mice, Leggadina lakedownensis, on Thevenard Island, Western Australia
Authors: Moro Dorian , Morris Keith
Published: September 2002

A trapping study from 1994 to 1996 examined
the population structure and dynamics of two sympatric populations of rodent,
Mus domesticus and
Leggadina lakedownensis, inhabiting an island off the
coast of Western Australia. Population abundance fluctuated dramatically
within and between years for both species, and those of
M. domesticuswere influenced by cyclones that passed
close to the island. Population densities for
M. domesticus reached 13.4 mice
ha–1 in November 1995, and were always twice those
of L. lakedownensis. M. domesticus bred throughout the
year. In contrast, the breeding season for
L. lakedownensis was strictly seasonal, and was
restricted to the mid-year months. Numbers of
M. domesticus were correlated with rainfall that fell
3–6 months previously. Similarly, numbers of
L. lakedownensis were correlated with rain that fell 3
months previously. Although no significant relationship was detected between
total invertebrate and mouse abundance, numbers of
M. domesticus were correlated with those of lepidopteran
larvae collected in pitfall traps. These data suggest that species coexistence
on the island may be mediated by extreme rainfall events, and a lack of
competition during low population densities.
Degradation of sodium monofluoroacetate (1080) in buried fox baits
Authors: Saunders Glen , McLeod Steven , Kay Barry
Published: September 2002

The degradation of 1080 in buried Foxoff®
baits was investigated. Baits were exposed to 5 different treatments:
shelf-stored controls, prevailing weather, no rainfall, average weekly
rainfall and twice average weekly rainfall. Curvilinear regression models were
used to model the rates of decay of 1080. These predicted that under normal
rainfall conditions, baits would become non-lethal to working dogs at 2.2
weeks and foxes at 2.8 weeks. Management implications of these results are
discussed.
Evaluation of attractants and bait preferences of captive red foxes (Vulpes vulpes)
Authors: Saunders Glen , Harris Stephen
Published: September 2002

The development of bait types, additives such
as synthetic flavours, and attractants for use in fox control and rabies
vaccination programmes is briefly reviewed. A captive colony was used to
establish bait preferences for foxes. A variety of bait types and additives
were screened for this purpose. The potential of chemical attractants to
enhance the discovery of baits by foxes was also examined. Gustatory
additives, such as beef flavour and sugar, enhanced bait acceptance, and
olfactory attractants such as synthetic fermented egg showed promise. Trials
using captive animals allow for observations impossible under field
conditions. However, field trials are also needed to determine whether
behavioural responses of free-ranging animals are similar to those observed in
captive individuals.
Population dynamics, diet and aspects of the biology of feral cats and foxes in arid South Australia
Authors: Read John , Bowen Zoë
Published: September 2002

Average cat and fox densities at Roxby Downs, in northern South Australia, of
0.8 and 0.6 km–2 respectively, determined through
spotlight counts over a 10-year period, probably considerably underestimate
true densities. Peak rabbit populations coincided with high fox numbers, which
probably suppressed cat densities. Cat abundance peaked when fox numbers were
low but rabbit numbers were relatively high.
When abundant, rabbits were the principal prey of both cats and foxes.
Declines in rabbits numbers coincided with dramatic declines in fox numbers.
By contrast, declines in cat populations were less marked, presumably because
they could more effectively switch to hunting a wide range of native
vertebrates. Sand-dwelling lizards, house mice and common small passerines
were the most abundant non-rabbit, vertebrate prey taken by cats. We estimate
that annual cat predation accounted for approximately 700 reptiles, 150 birds
and 50 native mammals per square kilometre, whereas foxes consumed on average
290 reptiles per square kilometre and few native mammals and birds in the
Roxby Downs region each year.
Male cats and foxes were heavier than females. Feral cats typically weighed
less than 4.0 kg, and cats weighing less than 2.5 kg typically preyed on more
native vertebrates than did larger cats. Male and female cats were both
typically tabby coloured, but a higher proportion of males were ginger in
colour. Peak cat breeding coincided with rabbit and bird breeding and
increased reptile activity during spring.
Responses of common brushtail possums (Trichosurus vulpecula) to translocation on farmland, southern North Island, New Zealand
Authors: Cowan P. E.
Published: September 2002

The behaviour, movements and fate of radio-tagged brushtail possums
(Trichosurus vulpecula) were studied after they were
translocated between sites on farmland in two areas in the southern North
Island, New Zealand. At both sites some possums remained near the release site
while others moved up to 12.5 km before settling. At one site, four possums
returned distances of about 3.9 km from the release site to their sites of
capture (homing), with two of these homing successfully twice. Translocated
possums displayed some of the characteristics of naturally dispersing possums
but, unlike them, their long-distance movements were not male-biased nor made
particularly by juveniles. The location and availability of suitable nest
sites appeared to influence the movements of translocated possums, but no
other major influences of landscape features on their patterns of movement
were detected. Survival during the first 9 weeks after translocation was not
influenced by sex, age, weight, distance moved or time since release.
Translocated possums on New Zealand farmland, where the main predators are
people and vehicles, suffered much lower mortality than possums in a similar
study in Australia, where canids, particularly foxes, were a major cause of
death.
Does habitat structure mediate the effects of forest fragmentation and human-induced disturbance on the abundance of Antechinus stuartii?
Authors: Knight Elizabeth H. , Fox Barry J.
Published: September 2002

Surveys were conducted among 30 remnants of differing size and degree of
disturbance to examine the effects of forest fragmentation and human-induced
disturbance on the abundance of a small, carnivorous marsupial,
Antechinus stuartii. The underlying aim of the study was
to evaluate the role of habitat structure in mediating the changes associated
with fragmentation and anthropogenic disturbance on
A. stuartii. The direct effects of remnant area and
disturbance on the abundance of A. stuartii were
marginal. Rather, the species responded more strongly to structural components
of the remnant habitat, including understorey height and complexity, litter
depth and the abundance of logs. In turn, these structural characteristics
were, to some extent, influenced by the remnant size and the degree of remnant
disturbance. The argument is therefore made that
A. stuartii generally responded to area-dependent
changes in habitat structure, rather than area per se, and that changes to
habitat structure were the primary mechanism by which remnant area and
disturbance regulated changes in the abundance of
A. stuartii. It appears that
A. stuartii may form a functional
‘metapopulation’ among the system of remnants at Tomago, New South
Wales. The Tomago metapopulation may be responding to habitat structure across
this heterogeneous landscape rather than being locally constrained within
isolated remnants, as the theory of island biogeography might predict.
Behavioural mechanisms of competition in small dasyurid marsupials
Authors: Righetti Joanne , Fox Barry J. , Croft David B.
Published: September 2002

The competitive behaviour of three species of small dasyurid marsupial,
Antechinus swainsonii,
Antechinus stuartii and
Sminthopsis murina, was assessed in specially designed
enclosures and smaller encounter cages, by videotaping the activity of pairs
of animals, both as conspecifics and members of different species (except for
A. swainsoni versus S. murina).
Spatio-temporal analyses revealed differences in activity patterns and
interactions within and between the species. Interference competition occurred
in all intraspecific and interspecific comparisons tested. Encounter
competition was judged to be the mechanism operating as all animals entered
into interactions with other individuals. Encounters were particularly
prevalent within Antechinus, indicating that they were
more social than the relatively solitary Sminthopsis.
Avoidance behaviour occurred between the two Antechinus
species and this may enable them to coexist, so that this mechanism may be
considered to be avoidance competition. The smaller competitor,
S. murina, showed avoidance of the larger
A. stuartii. Intraspecific competition was judged to be
stronger than interspecific competition, but the latter could have more severe
consequences, with the death of the smaller species occurring in some
situations. This highlighted the asymmetric nature of competition, with body
size determining the outcome of interactions between species.
Temperature variation within and between nests of the green sea turtle, Chelonia mydas (Chelonia: Cheloniidae) on Heron Island, Great Barrier Reef
Authors: Booth David T. , Astill Katherine
Published: September 2002

Four temperature data-loggers were placed in each of five green sea turtle
nests on Heron Island in the 1998–99 nesting season. Temperatures in all
nests increased as incubation progressed due to general sand heating and
increased metabolic heat production of the developing embryos. Even at the top
of nests no daily diurnal fluctuation in temperature was evident. The
temperature of eggs in the middle of the nest increased above those in the
nest periphery during the last third of incubation. However, this metabolic
nest heating would have little effect on hatchling sex ratio because it
occurred after the sex-determining period. Small differences in temperature
between regions of a nest persisted throughout incubation and may be important
in ensuring the production of at least some individuals of the opposite sex in
nests that have temperatures close to either the all-male or all-female
determining temperatures. Location and degree of shading of nests had little
effect on mean nest temperature, but deeper nests were generally cooler and
therefore were predicted to produce a higher proportion of males than were
shallower nests. Nest temperature profile data indicated that the
1998–99 nesting season on Heron Island would have produced a strongly
female-biased sex ratio amongst hatchlings.
Exploitation of the green tree ant, Oecophylla smaragdina, by the salticid spider Cosmophasis bitaeniata
Authors: Allan Rachel A. , Elgar Mark A.
Published: September 2002

The salticid spider Cosmophasis bitaeniata is a
myrmecophilic associate of the green tree ant,
Oecophylla smaragdina. The abundance of
C. bitaeniata on a tree or shrub is positively
correlated with the number of nests of O. smaragdina on
that vegetation. Experiments with captive spiders confirmed that the spiders
prey on the larvae of their highly territorial and aggressive ant host,
typically by removing the larvae from the mandibles of minor workers.
C. bitaeniata avoids direct contact with major workers
of O. smaragdina in daylight, but congeners elicited
higher activity levels of major workers than either nestmate workers or
C. bitaeniata. These data suggest
thatC. bitaeniata may be an exploitative chemical mimic
of its host.
Comparative phylogeography of three rainforest-restricted lizards from mid-east Queensland
Authors: Stuart-Fox Devi M. , Schneider Christopher J. , Moritz Craig , Couper Patrick J.
Published: September 2002

Several small isolates of rainforest situated on the central eastern coast of
Australia are home to a rich herpetofauna, including four endemic species of
leaftail geckos (Phyllurusspp.) and two skinks
(Eulamprus spp.). To examine the extent and geographic
pattern of historical subdivision among isolates, we assayed mtDNA variation
in two species endemic to rainforests of this region
(Phyllurus ossa and
Eulamprus amplus) and, for comparison, a more widespread
and less specialised lizard, Carlia rhomboidalis. There
is a clear genetic signature of historical changes in population size and
distribution in P. ossa that is consistent with
Pleistocene (or earlier) rainforest contraction and subsequent expansion.
Although more pronounced in the gecko, phylogeographic structure was congruent
between E. amplusand P. ossa. In
contrast to the saxicolous, rainforest-restricted
P. ossaand E. amplus, the
rainforest-generalist species, C. rhomboidalis, does not
display strong geographic population structure. The differences in genetic
population structure exhibited by the three species are consistent with
species-specific differences in ecology.
Activity times and body temperature in Australian copperheads (Serpentes : Elapidae)
Authors: Rohr Detlef H. , Malone Brian S.
Published: September 2002

Local climatic conditions influence the way in which ectotherms regulate their
body temperature and activity. We examined correlations between local climatic
conditions, body temperature and activity in adult, basking lowland
copperheads (Austrelaps superbus) from two localities
(warm-temperate versus cool-temperate) in south-eastern
Australia. We also collected data from highland copperheads
(Austrelaps ramsayi) at a locality with cold-temperate
climate. We found that across the active season, mean body temperatures were
similar among localities (approximately 27˚C) irrespective of species. In
contrast, activity times differed. Cool-temperate
A. superbus emerged earlier in spring and in the morning
and retreated earlier in the evening and in autumn than their conspecifics
from the warm-temperate locality. Spring emergence was correlated with yearly
fluctuations in thermal conditions, suggesting that activity times depend on
environmental temperatures. Predator–prey interactions influenced body
temperature and activity to some extent in spring when warm-temperate
A. superbus with relatively low body temperatures (as
low as 18.5˚C) were captured around ponds in which they had been foraging
for frogs. Austrelaps ramsayi from the cold-temperate
locality not only displayed a later emergence in spring and reduced daily
activity times compared with warm and cool-temperate
A. superbus but also compared with
A. ramsayi, as reported from a warmer locality in
eastern Australia. These data indicate that activity times vary on a
geographic basis while snake body temperatures largely remain inflexible. The
surprising exception was that cold-temperate A. ramsayi
retreated later in autumn than cool-temperate
A. superbus, and at that time they showed body
temperatures as low as 12.5˚C, well below those we had recorded for
A. superbus. We suggest that
A. ramsayi retreat later in autumn because they need to
extend their reproductive season and that this is mediated via adaptive
changes in the critical minimum body temperature, as has been reported for
other snakes.
A comparison of anterior adhesive areas and secretions in Troglocephalus rhinobatidis and Neoheterocotyle rhinobatidis (Monogenea : Monocotylidae) from the gills of the shovelnose ray, Rhinobatos typus (Rhinobatidae)
Authors: Cribb B. W. , Gould R. J. , Whittington I. D.
Published: September 2002

This study continues the collection of data on the anterior adhesive areas and
secretions of monopisthocotylean monogenean (flatworm) parasites and begins an
investigation of their phylogenetic usefulness. Here, two species of parasitic
worms from an elasmobranch, Troglocephalus rhinobatidis
(Monocotylidae: Dasybatotreminae) and
Neoheterocotyle rhinobatidis (Monocotylidae:
Heterocotylinae), are compared and contrasted. It has been suggested in recent
literature that these two taxa are more closely related than is currently
recognised. Our data support this view. Both species have multiple apertures
on the ventral anterior margin through which adhesive is secreted. Two types
of secretion exit from multiple adjacent duct endings terminating in each
aperture: rod-shaped (S1) and spherical-shaped (S2) bodies. S1 bodies of both
species show nano-banding of similar size and are membrane bound.
Ultrastructure of the glands, ducts, duct endings and secreted adhesive is
similar for both species, but aperture shape differs. Away from the adhesive
areas, tegumental inclusions are found to differ between the two species and
another, apparently non-adhesive, secretion is found in
N. rhinobatidis.
Group size effects in quokkas
Authors: Blumstein Daniel T. , Daniel Janice C. , McLean Ian G.
Published: September 2002

The amount of time allocated to vigilance, foraging, and locomotion as a
function of group size were studied in the quokka
(Setonix brachyurus), a small, moderately social,
macropodid marsupial, on Rottnest Island. Despite living in isolation from
most predators for up to 7000 years, quokkas exhibited typical group size
effects of aggregation: they foraged more and showed less visual vigilance as
group size increased. Group size effects, therefore, may result from factors
other than antipredator benefits. In groups larger than 10, quokkas, uniquely
among macropodids, allocated virtually all of their time to foraging and none
to looking. Given virtually no predation risk on Rottnest Island and no
antipredator benefit from aggregation, competition for food or other resources
may also be important factors influencing time allocation in quokkas. Quokkas
seemingly retained some apparent antipredator behaviour: they remained
sensitive to the distance they were from cover and to the time of day when
allocating time to foraging and looking.
Genetic and morphological variation in Australian Christinus (Squamata : Gekkonidae): preliminary overview with recognition of a cryptic species on the Nullarbor Plain
Authors: Donnellan S. C. , Aplin K. P. , Dempsey P. J.
Published: September 2002

An allozyme electrophoretic analysis of the geographically widespread,
southern Australian gekkonid lizard
Christinus marmoratus demonstrates the presence of a
hithertofore unsuspected, second species of Christinus.
The second species, which was found to be syntopic with the
2n = 36 ‘race’ of
C. marmoratus on the south-western side of the Nullarbor
Plain, is strikingly cryptic and possesses a very similar
2n =36 karyotype. Small but consistent
morphological differences between the two species allow their wider
distributions to be mapped in detail. As the holotype of
Phyllodactylus m. alexanderi Storr is identified as an
example of the second species, Storr’s taxon is elevated to a full
species and redefined. The geographic pattern of genetic variation within
C. marmoratus crosses the distribution of the four
recorded chromosome ‘races’. Reanalysis of previously reported
reproductive data reveals likely differences in the timing of gametogenesis
between C. alexanderi and the sympatric
2n = 36 C. marmoratus.
Males of C. alexanderi show maximal testicular
enlargement approximately six months before fertilisation, suggestive of
oviducal sperm storage through winter, whereas the 2n
= 36 C. marmoratus shows greatest testicular
volumes at the presumed time of fertilisation. While females of both taxa
carry eggs during September–October; C. marmoratus
invariably carry two eggs, but C. alexanderi have a
single egg in 36% of cases.
A review of feeding and diet selection in koalas (Phascolarctos cinereus)
Authors: Moore Benjamin D. , Foley William J.
Published: September 2002

Food quality and availability are believed to be primary determinants of
habitat quality for koalas (Phascolarctos cinereus), so
we need to know ‘what makes good food for koalas?’ An answer to
this question must define the dietary niche of koalas, describe how much
koalas eat and also consider variation in food choice by koalas at several
scales. Ultimately, all these issues must be related to variation in foliar
chemistry. Recent studies have shown that there is a closer relationship
between leaf composition and the food preferences of koalas than had
previously been appreciated but we emphasise the importance of evaluating diet
selection within a theoretical framework and at appropriate temporal and
spatial scales. Finally, we discuss the steps needed to incorporate an
understanding of the nutritional challenges faced by koalas into a broader
understanding of the species’ ecology to assist in its conservation.
Metabolic physiology of the north-western marsupial mole, Notoryctes caurinus (Marsupialia : Notoryctidae)
Authors: Withers P. C. , Thompson G. G. , Seymour R. S.
Published: September 2002

We studied the thermal and metabolic physiology of a single specimen of the
north-western marsupial mole, Notoryctes caurinus, an
almost completely fossorial Australian marsupial, and compared it with the
morphologically convergent Namib desert golden mole,
Eremitalpa granti namibensis. This was the first study
of any aspect of the physiology of this rare marsupial.
Mean body mass of the marsupial mole was 34 g. Body temperature
(Tb) was low and labile, ranging from 22.7 to
30.8˚C over a range of ambient temperature (Ta)
from 15 to 30˚C. The highest Tb of 30.8˚C was
significantly lower than expected for a marsupial of this body mass. Metabolic
rate varied with Ta in an attenuated fashion for an
endotherm, because of the labile Tb. Basal metabolic
rate (BMR) was 0.63 mL O2
g–1 h–1, at a
Ta of 30˚C. This was lower than expected for a 34-g
marsupial, but was not different from expected for a marsupial when corrected
to a Tb of 35˚C (0.94 mL O2
g–1 h–1). Evaporative
water loss increased from 0.8 mg g–1
h–1 at 15˚C to 3.7 at 30˚C. Wet thermal
conductance was 0.2 mL O2
g–1 h–1
˚C–1 at 15˚C and 0.6 at 25˚C; these
values were higher than expected for a marsupial. The net metabolic cost of
transport (NCOT) for running (0.0022 mL O2
g–1 m–1 at a mean
velocity of 484 m h–1) was similar to expected
values for walking and running mammals. The NCOT for sand-swimming (0.124 mL
O2 g–1
m–1 at a mean velocity of 7.6 m
h–1) was substantially higher, and at a much lower
velocity than for running, but was similar to NCOT for sand-swimming by the
Namib golden mole. We conclude that the marsupial mole differs in some aspects
of thermal and metabolic physiology from other marsupials, most likely
reflecting its almost completely fossorial existence.
Adenovirus triggers macropinocytosis and endosomal leakage together with its clathrin-mediated uptake
Authors: Meier Oliver , Boucke Karin , Hammer Silvija Vig , Keller Stephan , Stidwill Robert P. , Hemmi Silvio , Greber Urs F.
Published: September 2002

Adenovirus type 2 (Ad2) binds the coxsackie B virus Ad receptor and is endocytosed upon activation of the αv integrin coreceptors. Here, we demonstrate that expression of dominant negative clathrin hub, eps15, or K44A-dynamin (dyn) inhibited Ad2 uptake into epithelial cells, indicating clathrin-dependent viral endocytosis. Surprisingly, Ad strongly stimulated the endocytic uptake of fluid phase tracers, coincident with virus internalization but without affecting receptor-mediated transferrin uptake. A large amount of the stimulated endocytic activity was macropinocytosis. Macropinocytosis depended on αv integrins, PKC, F-actin, and the amiloride-sensitive Na+/H+ exchanger, which are all required for Ad escape from endosomes and infection. Macropinocytosis stimulation was not a consequence of viral escape, since it occurred in K44A-dyn–expressing cells. Surprisingly, 30–50% of the endosomal contents were released into the cytosol of control and also K44A-dyn–expressing cells, and the number of fluid phase–positive endosomes dropped below the levels of noninfected cells, indicating macropinosomal lysis. The release of macropinosomal contents was Ad dose dependent, but the presence of Ad particles on macropinosomal membranes was not sufficient for contents release. We conclude that Ad signaling from the cell surface controls the induction of macropinosome formation and leakage, and this correlates with viral exit to the cytosol and infection.
Hyaluronan–CD44 interaction hampers migration of osteoclast-like cells by down-regulating MMP-9
Authors: Spessotto Paola , Rossi Francesca Maria , Degan Massimo , Di Francia Raffaele , Perris Roberto , Colombatti Alfonso , Gattei Valter
Published: September 2002

Osteoclast (OC) precursors migrate to putative sites of bone resorption to form functionally active, multinucleated cells. The preOC FLG 29.1 cells, known to be capable of irreversibly differentiating into multinucleated OC-like cells, displayed several features of primary OCs, including expression of specific integrins and the hyaluronan (HA) receptor CD44. OC-like FLG 29.1 cells adhered to and extensively migrated through membranes coated with fibronectin, vitronectin, and laminins, but, although strongly binding to HA, totally failed to move on this substrate. Moreover, soluble HA strongly inhibited OC-like FLG 29.1 cell migration on the permissive matrix substrates, and this behavior was dependent on its engagement with CD44, as it was fully restored by function-blocking anti-CD44 antibodies. HA did not modulate the cell–substrate binding affinity/avidity nor the expression levels of the corresponding integrins. MMP-9 was the major secreted metalloproteinase used by OC-like FLG 29.1 cells for migration, because this process was strongly inhibited by both TIMP-1 and GM6001, as well as by MMP-9–specific antisense oligonucleotides. After HA binding to CD44, a strong down-regulation of MMP-9 mRNA and protein was detected. These findings highlight a novel role of the HA–CD44 interaction in the context of OC-like cell motility, suggesting that it may act as a stop signal for bone-resorbing cells.
Involvement of TRPC in the abnormal calcium influx observed in dystrophic (mdx) mouse skeletal muscle fibers
Authors: Vandebrouck Clarisse , Martin Dominique , Schoor Monique Colson-Van , Debaix Huguette , Gailly Philippe
Published: September 2002

Duchenne muscular dystrophy results from the lack of dystrophin, a cytoskeletal protein associated with the inner surface membrane, in skeletal muscle. The absence of dystrophin induces an abnormal increase of sarcolemmal calcium influx through cationic channels in adult skeletal muscle fibers from dystrophic (mdx) mice. We observed that the activity of these channels was increased after depletion of the stores of calcium with thapsigargin or caffeine. By analogy with the situation observed in nonexcitable cells, we therefore hypothesized that these store-operated channels could belong to the transient receptor potential channel (TRPC) family. We measured the expression of TRPC isoforms in normal and mdx adult skeletal muscles fibers, and among the seven known isoforms, five were detected (TRPC1, 2, 3, 4, and 6) by RT-PCR. Western blot analysis and immunocytochemistry of normal and mdx muscle fibers demonstrated the localization of TRPC1, 4, and 6 proteins at the plasma membrane. Therefore, an antisense strategy was used to repress these TRPC isoforms. In parallel with the repression of the TRPCs, we observed that the occurrence of calcium leak channels was decreased to one tenth of its control value (patch-clamp technique), showing the involvement of TRPC in the abnormal calcium influx observed in dystrophic fibers.
Reorganization of the microtubule array in prophase/prometaphase requires cytoplasmic dynein-dependent microtubule transport
Authors: Rusan Nasser M. , Tulu U. Serdar , Fagerstrom Carey , Wadsworth Patricia
Published: September 2002

When mammalian somatic cells enter mitosis, a fundamental reorganization of the Mt cytoskeleton occurs that is characterized by the loss of the extensive interphase Mt array and the formation of a bipolar mitotic spindle. Microtubules in cells stably expressing GFP–α-tubulin were directly observed from prophase to just after nuclear envelope breakdown (NEBD) in early prometaphase. Our results demonstrate a transient stimulation of individual Mt dynamic turnover and the formation and inward motion of microtubule bundles in these cells. Motion of microtubule bundles was inhibited after antibody-mediated inhibition of cytoplasmic dynein/dynactin, but was not inhibited after inhibition of the kinesin-related motor Eg5 or myosin II. In metaphase cells, assembly of small foci of Mts was detected at sites distant from the spindle; these Mts were also moved inward. We propose that cytoplasmic dynein-dependent inward motion of Mts functions to remove Mts from the cytoplasm at prophase and from the peripheral cytoplasm through metaphase. The data demonstrate that dynamic astral Mts search the cytoplasm for other Mts, as well as chromosomes, in mitotic cells.
ΔNp73, A Dominant-Negative Inhibitor of Wild-type p53 and TAp73, Is Up-regulated in Human Tumors
Authors: Zaika Alex I. , Slade Neda , Erster Susan H. , Sansome Christine , Joseph Troy W. , Pearl Michael , Chalas Eva , Moll Ute M.
Published: September 2002

p73 has significant homology to p53. However, tumor-associated up-regulation of p73 and genetic data from human tumors and p73-deficient mice exclude a classical Knudson-type tumor suppressor role. We report that the human TP73 gene generates an NH2 terminally truncated isoform. ΔNp73 derives from an alternative promoter in intron 3 and lacks the transactivation domain of full-length TAp73. ΔNp73 is frequently overexpressed in a variety of human cancers, but not in normal tissues. ΔNp73 acts as a potent transdominant inhibitor of wild-type p53 and transactivation-competent TAp73. ΔNp73 efficiently counteracts transactivation function, apoptosis, and growth suppression mediated by wild-type p53 and TAp73, and confers drug resistance to wild-type p53 harboring tumor cells. Conversely, down-regulation of endogenous ΔNp73 levels by antisense methods alleviates its suppressive action and enhances p53- and TAp73-mediated apoptosis. ΔNp73 is complexed with wild-type p53, as demonstrated by coimmunoprecipitation from cultured cells and primary tumors. Thus, ΔNp73 mediates a novel inactivation mechanism of p53 and TAp73 via a dominant-negative family network. Deregulated expression of ΔNp73 can bestow oncogenic activity upon the TP73 gene by functionally inactivating the suppressor action of p53 and TAp73. This trait might be selected for in human cancers.
Lymphangiogenic Gene Therapy With Minimal Blood Vascular Side Effects
Authors: Saaristo Anne , Veikkola Tanja , Tammela Tuomas , Enholm Berndt , Karkkainen Marika J. , Pajusola Katri , Bueler Hansruedi , Ylä-Herttuala Seppo , Alitalo Kari
Published: September 2002

Recent work from many laboratories has demonstrated that the vascular endothelial growth factor-C/VEGF-D/VEGFR-3 signaling pathway is crucial for lymphangiogenesis, and that mutations of the Vegfr3 gene are associated with hereditary lymphedema. Furthermore, VEGF-C gene transfer to the skin of mice with lymphedema induced a regeneration of the cutaneous lymphatic vessel network. However, as is the case with VEGF, high levels of VEGF-C cause blood vessel growth and leakiness, resulting in tissue edema. To avoid these blood vascular side effects of VEGF-C, we constructed a viral vector for a VEGFR-3–specific mutant form of VEGF-C (VEGF-C156S) for lymphedema gene therapy. We demonstrate that VEGF-C156S potently induces lymphangiogenesis in transgenic mouse embryos, and when applied via viral gene transfer, in normal and lymphedema mice. Importantly, adenoviral VEGF-C156S lacked the blood vascular side effects of VEGF and VEGF-C adenoviruses. In particular, in the lymphedema mice functional cutaneous lymphatic vessels of normal caliber and morphology were detected after long-term expression of VEGF-C156S via an adeno associated virus. These results have important implications for the development of gene therapy for human lymphedema.
Autophosphorylation of the DNA-dependent protein kinase catalytic subunit is required for rejoining of DNA double-strand breaks
Authors: Chan Doug W. , Chen Benjamin Ping-Chi , Prithivirajsingh Sheela , Kurimasa Akihiro , Story Michael D. , Qin Jun , Chen David J.
Published: September 2002

Nonhomologous end-joining (NHEJ) is the predominant pathway that repairs DNA double-strand breaks (DSBs) in mammalian cells. The DNA-dependent protein kinase (DNA-PK), consisting of Ku and DNA-PK catalytic subunit (DNA-PKcs), is activated by DNA in vitro and is required for NHEJ. We report that DNA-PKcs is autophosphorylated at Thr2609 in vivo in a Ku-dependent manner in response to ionizing radiation. Phosphorylated DNA-PKcs colocalizes with both γ-H2AX and 53BP1 after DNA damage. Mutation of Thr2609 to Ala leads to radiation sensitivity and impaired DSB rejoining. These findings establish that Ku-dependent phosphorylation of DNA-PKcs at Thr2609 is required for the repair of DSBs by NHEJ.
The suppression of brain cold-stable microtubules in mice induces synaptic defects associated with neuroleptic-sensitive behavioral disorders
Authors: Andrieux Annie , Salin Paul A. , Vernet Muriel , Kujala Pekka , Baratier Julie , Gory-Fauré Sylvie , Bosc Christophe , Pointu Hervé , Proietto Dominique , Schweitzer Annie , Denarier Eric , Klumperman Judith , Job Didier
Published: September 2002

Neurons contain abundant subsets of highly stable microtubules that resist depolymerizing conditions such as exposure to the cold. Stable microtubules are thought to be essential for neuronal development, maintenance, and function. Previous work has indicated an important role of the microtubule-associated protein STOP in the induction of microtubule cold stability. Here, we developed STOP null mice. These mice were devoid of cold-stable microtubules. In contrast to our expectations, STOP−/− mice had no detectable defects in brain anatomy but showed synaptic defects, with depleted synaptic vesicle pools and impaired synaptic plasticity, associated with severe behavioral disorders. A survey of the effects of psychotropic drugs on STOP−/− mice behavior showed a remarkable and specific effect of long-term administration of neuroleptics in alleviating these disorders. This study demonstrates that STOP is a major factor responsible for the intriguing stability properties of neuronal microtubules and is important for synaptic plasticity. Additionally, STOP−/− mice may yield a pertinent model for study of neuroleptics in illnesses such as schizophrenia, currently thought to result from synaptic defects.
Multidrug Pump Inhibitors Uncover Remarkable Activity of Plant Antimicrobials
Authors: Tegos George , Stermitz Frank R. , Lomovskaya Olga , Lewis Kim
Published: September 2002

Plant antimicrobials are not used as systemic antibiotics at present. The main reason for this is their low level of activity, especially against gram-negative bacteria. The reported MIC is often in the range of 100 to 1,000 μg/ml, orders of magnitude higher than those of common broad-spectrum antibiotics from bacteria or fungi. Major plant pathogens belong to the gram-negative bacteria, which makes the low level of activity of plant antimicrobials against this group of microorganisms puzzling. Gram-negative bacteria have an effective permeability barrier, comprised of the outer membrane, which restricts the penetration of amphipathic compounds, and multidrug resistance pumps (MDRs), which extrude toxins across this barrier. It is possible that the apparent ineffectiveness of plant antimicrobials is largely due to the permeability barrier. We tested this hypothesis in the present study by applying a combination of MDR mutants and MDR inhibitors. A panel of plant antimicrobials was tested by using a set of bacteria representing the main groups of plant pathogens. The human pathogens
Pseudomonas aeruginosa
,
Escherichia coli
, and
Salmonella enterica
serovar Typhimurium were also tested. The results show that the activities of the majority of plant antimicrobials were considerably greater against the gram-positive bacteria
Staphylococcus aureus
and
Bacillus megaterium
and that disabling of the MDRs in gram-negative species leads to a striking increase in antimicrobial activity. Thus, the activity of rhein, the principal antimicrobial from rhubarb, was potentiated 100- to 2,000-fold (depending on the bacterial species) by disabling the MDRs. Comparable potentiation of activity was observed with plumbagin, resveratrol, gossypol, coumestrol, and berberine. Direct measurement of the uptake of berberine, a model plant antimicrobial, confirmed that disabling of the MDRs strongly increases the level of penetration of berberine into the cells of gram-negative bacteria. These results suggest that plants might have developed means of delivering their antimicrobials into bacterial cells. These findings also suggest that plant antimicrobials might be developed into effective, broad-spectrum antibiotics in combination with inhibitors of MDRs.
Mutations in 23S rRNA Account for Intrinsic Resistance to Macrolides in
Mycoplasma hominis
and
Mycoplasma fermentans
and for Acquired Resistance to Macrolides in
M. hominis
Authors: Pereyre S. , Gonzalez P. , de Barbeyrac B. , Darnige A. , Renaudin H. , Charron A. , Raherison S. , Bébéar C. , Bébéar C. M.
Published: September 2002

The mechanisms of intrinsic resistance of
Mycoplasma hominis
to 14- and 15-membered macrolides were investigated in comparison with those of
M. pneumoniae
, which is naturally susceptible to macrolides. Radiolabeled erythromycin was not accumulated by
M. hominis
PG21, but addition of an ABC transporter inhibitor increased the level of erythromycin uptake more than two times, suggesting the existence of an active efflux process. The affinity of [
14
C]erythromycin to ribosomes isolated from
M. hominis
was dramatically reduced relative to that to ribosomes isolated from
M. pneumoniae.
The nucleotide sequences of 23S rRNA of both ribosomal operons
rrnA
and
rrnB
and ribosomal proteins L4 and L22 of
M. hominis
were obtained. Compared to the sequence of
M. pneumoniae
,
M. hominis
harbored a G2057A transition in its 23S rRNA sequence, as did
M. fermentans
, another mycoplasma that is erythromycin resistant. An additional C2610U change was also found in the sequence of
M. hominis
. Moreover, two
M. hominis
clinical isolates with acquired resistance to 16-membered macrolides were examined for mutations in domain II and domain V of 23S rRNA and in ribosomal proteins L4 and L22. Compared to the sequence of reference strain PG21, one isolate harbored a A2059G transition and a C2611U transition in one of the two
rrn
operons, while the other one was mutated only at position 2059, also on the same operon. No mutation was found in the two ribosomal protein sequences. Overall, the present study is an exhaustive characterization of the intrinsic resistance of
M. hominis
to 14- and 15-membered macrolides and the first description of mycoplasma clinical isolates resistant to macrolide, lincosamide, and streptogramin antibiotics harboring a mutation at position 2611 in the 23S rRNA.
Bactericidal Activity of Rifampin-Amikacin against
Mycobacterium ulcerans
in Mice
Authors: Dega Herve , Bentoucha Abdelhalim , Robert Jerome , Jarlier Vincent , Grosset Jacques
Published: September 2002

To identify the most active curative treatment of Buruli ulcer, two regimens incorporating the use of rifampin (RIF) were compared with the use of RIF alone in a mouse footpad model of
Mycobacterium ulcerans
infection. Treatments began after footpad swelling from infection and continued for 12 weeks with five doses weekly of one of the following regimens: (i) 10 mg of RIF/kg alone; (ii) 10 mg of RIF/kg and 100 mg of amikacin (AMK)/kg; and (iii) 10 mg of RIF/kg, 100 mg of clarithromycin (CLR)/kg, and 50 mg of sparfloxacin (SPX)/kg. The activity of each regimen was assessed in terms of the reduction of the average lesion index and acid-fast bacillus (AFB) and CFU counts. All three regimens displayed various degrees of bactericidal activity against
M. ulcerans
. The ranking of bactericidal activity was found to be as follows: RIF-AMK > RIF-CLR-SPX > RIF. RIF-AMK was able to cure
M. ulcerans
-infected mice and prevent relapse 26 weeks after completion of treatment. To determine the impact of different rhythms of administration of RIF-AMK on the suppression of
M.ulcerans
growth, mice were given the RIF-AMK combination for 4 weeks but doses were administered either 5 days a week or twice or once weekly. After completion of treatment, the mice were kept under supervision for 30 additional weeks.
M. ulcerans
was considered to have grown in the footpad if swelling was visually observed and harvests contained more than 5 × 10
5
AFB per footpad. The proportion of mice in which growth of
M. ulcerans
occurred, irrespective of drug dosage, was compared with the control mice to determine the proportion of
M. ulcerans
killed. Each dosage of RIF-AMK was bactericidal for
M. ulcerans
(
P
< 0.001), but the effect was significantly stronger in mice treated 5 days per week. The promising results of RIF-AMK treatment in
M. ulcerans
-infected mice support the clinical trial that is currently in progress under World Health Organization auspices in Ghana.