bluuebunny/crossref_metadata_2025 huggingface dataset:
Water metabolism and renal function and structure in eastern grey kangaroos (Macropus giganteus): responses to water deprivation
Authors: Blaney C. E. , Dawson T. J. , McCarron H. C. K. , Buffenstein R. , Krockenberger A. K.
Published: January 2006

The eastern grey kangaroo (M. giganteus) is usually
found in mesic habitats but in the past 30–40 years it has expanded its
range into arid rangelands. A suggested reason for this expansion has been the
provision of additional water sites for domestic stock. In this study we
examined aspects of kidney function and water metabolism of
M. giganteus. This was done during normal hydration and
water restriction so that the water-conserving abilities of
M. giganteus could be compared with those of the red
kangaroo (M. rufus), the habitat of which is arid
rangelands and desert.
The indices relative medullary thickness (RMT) and medullary to cortical
ratio, derived from the morphology of the kidney, are indicators of renal
concentrating ability. In M. giganteus both these
indices were lower than in M. rufus: the RMT was 5.24
0.15 (mean s.e.) for M. giganteus and 6.00 0.10 for
M. rufus. Measured maximal urine concentrations of these
species were 2444 59 (M. giganteus) and 3135 165 mosmol
kg–1 (M. rufus), with the
respective maximum individual concentrations being 2752 and 4054 mosmol
kg–1. Kidney function in hydrated and dehydrated
M. giganteus was assessed via glomerular filtration
rate, urine flow rate and concentration index. As measured by these
parameters, M. giganteus had renal water-conserving
capacities similar to, or superior to, those of many comparable-sized
arid-zone-inhabiting placental mammals, but below those of
M. rufus. Water metabolism, as measured by water
turnover, showed a similar pattern.
Displacement of Tasmanian native megachilid bees by the recently introduced bumblebee Bombus terrestris (Linnaeus, 1758) (Hymenoptera : Apidae)
Authors: McQuillan Peter B. , Hingston Andrew B.
Published: January 2006

The assertion that the recently introduced large earth bumblebee,
Bombus terrestris, does not compete with other bees was
investigated by examining the impact of B. terrestris on the foraging of two
species of Chalicodoma(Megachilidae) on flowers of
Gompholobium huegelii (Fabaceae).
Chalicodoma spp. spent less time at each flower during
the afternoon in quadrats where B. terrestris foraged
than at quadrats from which B. terrestriswas excluded,
indicating that standing crops of nectar were depleted by
B. terrestris during the course of the day. This decline
in resources was associated with reductions in the numbers of flowers visited,
and the amount of time spent foraging, by Chalicodoma
spp. It is proposed that the native bees avoided foraging in the quadrat where
B. terrestris occurred as a response to reduced foraging
efficiency in that situation. Thus, B. terrestris
displaced these two species of Chalicodoma through
competition for a limited resource. The high densities at which
B. terrestris occurred, together with its ability to
forage at lower ambient temperatures than the native bees, exacerbated the
impact of this exotic species. The possibility that this will adversely affect
pollination in G. huegelii is also discussed.
The effects of moonlight on microhabitat use by Antechinus agilis (Marsupialia : Dasyuridae)
Authors: Sutherland Duncan R. , Predavec Martin
Published: January 2006

This study investigates the effect of lunar illumination on microhabitat use
of Antechinus agilis, an insectivorous, semi-arboreal
species of dasyurid marsupial. The study was conducted in tall open forest
near Melbourne, Australia, from April to August 1997. Microhabitat was
investigated by use of live trapping and fluorescent pigment tracking. The
influence of light on spatial and temporal activity was investigated by
comparing microhabitat use in the field at two extremes of moonlight
intensity, full and new moon, and by manipulating light intensity in the
field. Antechinus agilis were trapped in and tracked
through dense microhabitats in a greater proportion than was available,
although this pattern was evident only in the vegetation stratum below one
metre from the ground. Furthermore, animals did not respond to the
microhabitat at the point of capture, but responded to a larger microhabitat
scale radiating 10 m from the trap. However, light intensity appears to have
little influence on the spatial or temporal activity of
A. agilis at this site. Therefore
A. agilis appear not to differentially use denser
microhabitats in relation to light intensity. Habitat complexity, prey
availability, interspecific competition and predation are discussed as
possible reasons why A. agilis differentially use denser
microhabitats.
Short-term host discrimination in the parasitoid wasp Trissolcus basalis Wollaston (Hymenoptera : Scelionidae)
Authors: Field S. A. , Keller M. A.
Published: January 2006

The ability of host discrimination allows insect parasitoids to avoid
superparasitism (oviposition in a previously attacked host). However,
superparasitism can sometimes be adaptive, so attempts to identify host
discrimination must be made under appropriate ecological conditions. We tested
the ability of the parasitoid wasp Trissolcus basalis to
discriminate between self- and conspecific-parasitised hosts (conspecific
discrimination) under ecologically realistic conditions, in which conspecific
discrimination should be adaptive. Data were analysed using a Monte Carlo
simulation model that permitted testing of several different ways in which
conspecific discrimination could be achieved. We obtained the novel result
that females avoided self-superparasitism on a patch consisting of a mixture
of self- and conspecific-parasitised hosts, but that this avoidance was not
due to true conspecific discrimination. Instead, it was due to short- term
discrimination between newly and previously parasitised hosts. Two likely
mechanisms for such discrimination are proposed: a short-lived host-derived
volatile; and the presence of two or more chemical components in the marking
pheromone.
Diet selection by immature green turtles, Chelonia mydas, in subtropical Moreton Bay, south-east Queensland
Authors: Brand-Gardner S. J. , Limpus C. J. , Lanyon J. M.
Published: January 2006

Diet selection by immature green turtles
(Chelonia mydas) in Flathead Gutter, Moreton Bay, was
determined by examining food ingested in relation to food availability
(measured as vegetation composition and abundance within the feeding site).
Food composition was sampled by oesophageal lavage. Turtles were repeatedly
located over a 10-week period by means of sonic telemetry and visual
identification. The number of resightings indicated that these turtles
remained within their feeding grounds for at least short periods of time.
Immature green turtles fed on both seagrass and algal species. However, most
fed selectively on algae, primarily Gracilaria sp. Food
items consumed frequently by these turtles were analysed for total nitrogen,
gross energy and neutral detergent fibre levels. There was a negative
correlation between fibre level and the preferred food species, where the more
frequently selected species had lower levels of fibre. The preferred species
also had higher nitrogen levels
The metabolic response to hypoxia and emersion of aestivating fishes (Lepidogalaxias salamandroides and Galaxiella nigrostriata) and a non-aestivating fish (Bostockia porosa) from south-western Australia
Authors: Thompson Graham G. , Withers Philip C.
Published: January 2006

We measured the metabolic rate of three fishes
(Lepidogalaxias salamandroides,
Galaxiella nigrostriata,
Bostockia porosa) that are endemic to the south-west of
Western Australia. The first two species have been reported to aestivate, the
third does not aestivate when the ponds dry up in late summer. For normoxic
conditions, the metabolic rates of B. porosa and
G. nigrostriata in water (0.48 mL
g–1 h–1 and 0.44 mL
g–1 h–1 respectively),
are significantly higher than in air (0.21 mL g–1
h–1 and 0.08 mL g–1
h–1 respectively) but for the more benthic and
terrestrially mobile L. salamandroides there was no
significant difference between VO2 in water (0.29 mL
g–1 h–1 ) and air
(0.18 mL g–1 h–1).
Progressive hypoxia (12, 5 and 2% O2) decreased
the metabolic rate of G. nigrostriata and
B. porosa in both water and air but there was a
reduction in metabolic rate for L. salamandroides only
in water. The metabolic physiology of L. salamandroides
in water and air is consistent with the capacity to aestivate in moist soil,
but the different metabolic response of G. nigrostriata
suggests that it adopts a different strategy to
L. salamandroides to survive when the ponds dry up in
summer. The metabolism of G. nigrostriata in air and
water declines with progressive hypoxia (from 12 to 5 to 2%
O2). B. porosa does not appear to
be able to cope metabolically when out of water or under hypoxic conditions,
and therefore would not be able to aestivate.
The importance of pair duration and biparental care to reproductive success in the monogamous Australian magpie-lark
Authors: Hall Michelle L.
Published: January 2006

Biparental care is common in birds, where monogamy is the predominant mating
system. Australian magpie-larks (Grallina cyanoleuca)
are socially monogamous, and relatively unusual among passerines in the extent
to which parental care is shared. Males contributed as much or more to
parental care as females, sharing nest-building, incubation, brooding and
feeding of nestlings and fledglings. Biparental care was thus important to
survival of offspring, and probably constrained partners to stay together
thoughout a breeding attempt. However, partners usually remained together
longer. Pairs that had bred together in the previous season tended to lay
their first clutch earlier, were more likely to fledge two broods in the
season, and had higher annual reproductive success than pairs breeding
together for the first time. Females benefitted from staying with a male they
had bred with previously, as females in established pairs decreased their
feeding rates and their partners compensated to some extent. Differences
between new and established pairs may have been due to the effects of the age
and experience of each partner, or to pair duration, or both. Divorce rates
were low, consistent with benefits associated with staying together, but also
with high costs of divorce as year-round territoriality probably limited
opportunities for taking different partners.
A population study of the mountain brushtail possum (Trichosurus caninus) in the central highlands of Victoria
Authors: Viggers K. L. , Lindenmayer D. B.
Published: January 2006

Life-history attributes are described for the mountain brushtail possum
(Trichosurus caninus) in mountain ash
(Eucalyptus regnans) forest at Cambarville in the
central highlands of Victoria, south-eastern Australia. The population was
trapped on a regular basis between 1992 and 1995. Population density of
T. caninus at Cambarville was high (2.3 animals
ha–1). The adult sex ratio was female-biased (1.4
: 1) and the age class structure differed between sexes. There were more adult
females than males in very old age classes (those animals assigned to Age
Classes 7–9 and exceeding an estimated 10 years of age), whereas there
were more males in the young adult cohorts (Age Classes 3 and 4). The breeding
season was restricted to March–April, when a single young was produced.
A second young was not produced if the first was lost. The survival of young
from birth to emergence from the pouch showed strong between-year variation
(30–80%). Sex ratios at birth were strongly male-biased (average
= 2.6 : 1) but female young were far more likely to survive to advanced
back-young stage. Breeding success of females at Cambarville was not
influenced by the presence of semi-independent young from a previous year
remaining in the natal territory. There was some evidence of senescence in
breeding success among females in older age cohorts (Age Classes 7–9)
and these animals did not successfully rear young.
Many animals were trapped repeatedly at the same place, whereas others ranged
over a much wider area (up to 3 ha). There was also considerable overlap
between individuals in the spatial location of the areas where they were
trapped.
Parasites of the northern quoll, Dasyurus hallucatus (Marsupialia:Dasyuridae) in tropical savanna, Northern Territory
Authors: Oakwood Meri , Spratt David M.
Published: January 2006

The ectoparasites of northern quolls,
Dasyurus hallucatus, are reported from 79 animals
live-trapped at Kapalga Research Station, Kakadu National Park, during
1992–95. The ecto- and endoparasites are reported from 62 dead
D. hallucatus during the same period; these were mostly
road-kills collected from an 88-km section of the Arnhem Highway between
Jabiru and the Northern Entry Station of Kakadu National Park. Tissues from 28
of the road-kills were examined histologically. Additionally, 214 scat samples
were examined for ecto- and endoparasites. Seven species of ectoparasite,
including two species of tick, a larval trombiculid mite, a louse and two
(possibly three) species of flea, and 17 species of endoparasite including a
trematode, a larval cestode, 13 species of nematode, a larval pentastome and a
protozoan were recorded from D. hallucatus. Sarcocystis
sp. was found in tissues but neither Toxoplasma gondii
nor Trichinella pseudospiralis were detected in
histological sections or tissue digests. Ticks, mites and nematodes were found
in scats. The tick Haemaphysalis bancrofti, the flea
Echidnophaga aranka and possibly
E. ambulans, and the nematodes
Mackerrastrongylus peramelis and
Cylicospirura heydoni represent new host records for
D. hallucatus. Although parasitism was common in
D. hallucatus, few individuals harboured large burdens.
Consequently, it appears unlikely that parasitism is a major factor
contributing to the decline of northern quolls in this region.
The black flying-fox (Pteropus alecto) in north Australia: juvenile mortality and longevity
Authors: Vardon Michael J. , Tidemann Christopher R.
Published: January 2006

Mortality rates for juvenile black flying-fox
(Pteropus alecto) are presented from data collected in
the Northern Territory of Australia
(12˚24′–13˚03′S) between 1992 and 1998. Forearm
size data were used to construct a two-stage life table for each sex.
Mortality rates from birth to adult size (170 mm) varied between sexes,
between camp-sites and between years, and ranged from 0.43 to 0.80. Overall,
the mortality rates from birth to adult size were 0.70 for females
(n = 846) and 0.63 for males
(n = 990). These rates represent annual juvenile
mortality rates of 0.57 for females and 0.47 for males, given that females
reach adult size at 14.8 months of age and males at 16.3 months of age. The
maximum age of P. alecto recorded in this study was 4.5
years. The mean lifespan of females reaching adulthood would need to be seven
years for a stable population size to be maintained, but may be shorter given
that the mortality rates may have been over-estimated. The mortality rates and
lifespan of P. alecto are not unusual amongst Chiroptera
or small mammals in general.
Possums in the park: efficient foraging under the risk of predation or of competition?
Authors: McDonald-Madden Eve , Akers Lian K. , Brenner Deena J. , Howell Sarah , Patullo Blair W. , Elgar Mark A.
Published: January 2006

Many eutherian mammals adjust their foraging behaviour according to the
presence or threat of predators. Here, we examine experimentally whether an
urban population of brushtail possums,
Trichosurus vulpecula, similarly adjust their foraging
behaviour. Our field experiments manipulated the quantity of food items in
artificial feeders placed at different distances from trees. These experiments
showed that the possums remained longer at feeders placed far from the trees,
but their foraging behaviour did not change with the initial amount of food.
The scanning behaviour of possums did not simply increase with distance from
the trees, as predicted from studies of other vertebrates. Nevertheless, the
number of physical conflicts between individuals increased as the amount of
available food decreased. These data suggest that the changes in the foraging
behaviour of the possums in this population do not reflect a simple trade-off
between foraging efficiency and the risk of predation or competition.
The basis of life-history plasticity in the tropical butterfly Hypolimnas bolina (L.) (Lepidoptera : Nymphalidae)
Authors: Kemp Darrell J.
Published: January 2006

The common eggfly, Hypolimnas bolina (L.)
(Lepidoptera:Nymphalidae), is an adult-diapausing tropical and sub-tropical
species that exhibits seasonal plasticity in adult body size. Here I
investigated (a) whether size plasticity in this species is due solely to
variations in rearing temperature, or whether photoperiod is also involved,
and (b) whether rearing photoperiod affects the timing of ovarian development
in adults. Individuals were cultured at temperatures ranging from 21˚C to
30˚C, and under daylengths of 11.5, 12.5 and 13.5 h in two separate
experiments. Significant plasticity in juvenile developmental traits was
detected in response to both variables, with cooler temperatures and shorter
daylengths both leading to decreased developmental rates and increased size at
maturity. Although juveniles grew more slowly with decreasing temperature,
they grew faster with decreasing daylength. The timing of ovarian maturation
was also related to rearing photoperiod; whereas ‘long day’ adults
(13.5-h photoperiod) had gravid ovaries after 10 days, the ovaries of
‘short day’ adults (11.5-h photoperiod) were either regressed or
nearly so. These preliminary results suggest that size variation observed in
field populations of H. bolina may not be wholly
accounted for by variations in developmental temperature and, furthermore,
that photoperiod may be used by this tropical species as an environmental cue
for the seasonal timing of reproduction.
Mitochondrial DNA and morphology reveal three geographically distinct lineages of the large bentwing bat (Miniopterus schreibersii) in Australia
Authors: Cardinal B. R. , Christidis L.
Published: January 2006

A combined molecular and morphological analysis was undertaken to resolve the
systematics of the Miniopterus schreibersii complex in
Australia. The study of skull morphology and sequence analysis of two
mitochondrial genes, nicotinamine dehydrogenase subunit 2 and
cytochrome-b, revealed three distinct Australian forms
of M. schreibersii which are treated as subspecies.
M. s. orianae occurs in northern Australia,
M. s. oceanensis occurs in eastern Australia from
Queensland through to central Victoria and
M. s. bassanii, sp. nov. occurs in Western Victoria and
eastern South Australia. The biogeographical history of the complex in
Australia is discussed in the light of this new revision.
Regulation of sodium-proton exchanger isoform 3 (NHE3) by PKA and exchange protein directly activated by cAMP (EPAC)
Authors: Honegger Katharina J. , Capuano Paola , Winter Christian , Bacic Desa , Stange Gerti , Wagner Carsten A. , Biber Jürg , Murer Heini , Hernando Nati
Published: January 2006

The Na+/H+exchanger 3 (NHE3) is expressed in the brush border membrane (BBM) of proximal tubules (PT). Its activity is down-regulated on increases in intracellular cAMP levels. The aim of this study was to investigate the contribution of the protein kinase A (PKA) and the exchange protein directly activated by cAMP (EPAC) dependent pathways in the regulation of NHE3 by adenosine 3′,5′-cyclic monophosphate (cAMP). Opossum kidney cells and murine kidney slices were treated with cAMP analogs, which selectively activate either PKA or EPAC. Activation of either pathway resulted in an inhibition of NHE3 activity. The EPAC-induced effect was independent of PKA as indicated by the lack of activation of the kinase and the insensitivity to the PKA inhibitor H89. Both PKA and EPAC inhibited NHE3 activity without inducing changes in the expression of the transporter in BBM. Activation of PKA, but not of EPAC, led to an increase of NHE3 phosphorylation. In contrast, activation of PKA, but not of EPAC, inhibited renal type IIa Na+-coupled inorganic phosphate cotransporter (NaPi-IIa), another Na-dependent transporter expressed in proximal BBM. PKA, but not EPAC, induced the retrieval of NaPi-IIa from BBM. Our results suggest that EPAC activation may represent a previously unrecognized mechanism involved in the cAMP regulation of NHE3, whereas regulation of NaPi-IIa is mediated by PKA but not by EPAC.
The peptidoglycan recognition protein PGRP-SC1a is essential for Toll signaling and phagocytosis of
Staphylococcus aureus
in
Drosophila
Authors: Garver Lindsey S. , Wu Junlin , Wu Louisa P.
Published: January 2006

From a forward genetic screen for phagocytosis mutants in
Drosophila melanogaster
, we identified a mutation that affects peptidoglycan recognition protein (PGRP)
SC1a
and impairs the ability to phagocytose the bacteria
Staphylococcus aureus
, but not
Escherichia coli
and
Bacillus subtilis
. Because of the differences in peptidoglycan peptide linkages in these bacteria, our data suggest that PGRP-SC1a is necessary for recognition of the Lys-type peptidoglycan typical of most Gram
+
bacteria.
PGRP-SC1a
mutants also fail to activate the Toll/NF-κB signaling pathway and are compromised for survival after
S. aureus
infection. This mutant phenotype is the first found for an
N
-acetylmuramoyl-
l
-alanine amidase PGRP that cleaves peptidoglycan at the lactylamide bond between the glycan backbone and the crosslinking stem peptides. By generating transgenic rescue flies that express either wild-type or a noncatalytic cysteine–serine mutant PGRP-SC1a, we find that PGRP-SC1a amidase activity is not necessary for Toll signaling, but is essential for uptake of
S. aureus
into the host phagocytes and for survival after
S. aureus
infection. Furthermore, we find that the PGRP-SC1a amidase activity can be substituted by exogenous addition of free peptidoglycan, suggesting that the presence of peptidoglycan cleavage products is more important than the generation of cleaved peptidoglycan on the bacterial surface for PGRP-SC1a mediated phagocytosis.
The ratToxo1locus directs toxoplasmosis outcome and controls parasite proliferation and spreading by macrophage-dependent mechanisms
Authors: Cavaillès Pierre , Sergent Véronique , Bisanz Cordelia , Papapietro Olivier , Colacios Céline , Mas Magali , Subra Jean-François , Lagrange Dominique , Calise Maryline , Appolinaire Sylvie , Faraut Thomas , Druet Philippe , Saoudi Abdelhadi , Bessieres Marie-Hélène , Pipy Bernard , Cesbron-Delauw Marie-France , Fournié Gilbert J.
Published: January 2006

Toxoplasmosis is a healthcare problem in pregnant women and immunocompromised patients. Like humans, rats usually develop a subclinical chronic infection. LEW rats exhibit total resistance toToxoplasma gondiiinfection, which is expressed in a dominant mode. A genome-wide search carried out in a cohort of F2progeny of susceptible BN and resistant LEW rats led to identify on chromosome 10 a major locus of control, which we calledToxo1. Using reciprocal BN and LEW lines congenic for chromosome 10 genomic regions from the other strain,Toxo1was found to govern the issue ofT. gondiiinfection whatever the remaining genome. Analyzes of rats characterized by genomic recombination withinToxo1, reduced the interval down to a 1.7-cM region syntenic to human 17p13.In vitrostudies showed that theToxo1-mediated refractoriness toT. gondiiinfection is associated with the ability of the macrophage to impede the proliferation of the parasite within the parasitophorous vacuole. In contrast, proliferation was observed in fibroblasts whatever the genomic origin ofToxo1. Furthermore,ex vivostudies indicate that macrophage controls parasitic infection spreading by aToxo1-mediated mechanism. This forward genetics approach should ultimately unravel a major pathway of innate resistance to toxoplasmosis and possibly to other apicomplexan parasitic diseases.
A landscape effect in tenosynovial giant-cell tumor from activation of CSF1 expression by a translocation in a minority of tumor cells
Authors: West Robert B. , Rubin Brian P. , Miller Melinda A. , Subramanian Subbaya , Kaygusuz Gulsah , Montgomery Kelli , Zhu Shirley , Marinelli Robert J. , De Luca Alessandro , Downs-Kelly Erinn , Goldblum John R. , Corless Christopher L. , Brown Patrick O. , Gilks C. Blake , Nielsen Torsten O. , Huntsman David , van de Rijn Matt
Published: January 2006

Tenosynovial giant-cell tumor (TGCT) and pigmented villonodular synovitis (PVNS) are related conditions with features of both reactive inflammatory disorders and clonal neoplastic proliferations. Chromosomal translocations involving chromosome 1p13 have been reported in both TGCT and PVNS. We confirm that translocations involving 1p13 are present in a majority of cases of TGCT and PVNS and show that
CSF1
is the gene at the chromosome 1p13 breakpoint. In some cases of both TGCT and PVNS,
CSF1
is fused to
COL6A3
(2q35). The
CSF1
translocations result in overexpression of
CSF1
. In cases of TGCT and PVNS carrying this translocation, it is present in a minority of the intratumoral cells, leading to
CSF1
expression only in these cells, whereas the majority of cells express
CSF1R
but not
CSF1
, suggesting a tumor-landscaping effect with aberrant
CSF1
expression in the neoplastic cells, leading to the abnormal accumulation of nonneoplastic cells that form a tumorous mass.
The diversity and biogeography of soil bacterial communities
Authors: Fierer Noah , Jackson Robert B.
Published: January 2006

For centuries, biologists have studied patterns of plant and animal diversity at continental scales. Until recently, similar studies were impossible for microorganisms, arguably the most diverse and abundant group of organisms on Earth. Here, we present a continental-scale description of soil bacterial communities and the environmental factors influencing their biodiversity. We collected 98 soil samples from across North and South America and used a ribosomal DNA-fingerprinting method to compare bacterial community composition and diversity quantitatively across sites. Bacterial diversity was unrelated to site temperature, latitude, and other variables that typically predict plant and animal diversity, and community composition was largely independent of geographic distance. The diversity and richness of soil bacterial communities differed by ecosystem type, and these differences could largely be explained by soil pH (
r
2
= 0.70 and
r
2
= 0.58, respectively;
P
< 0.0001 in both cases). Bacterial diversity was highest in neutral soils and lower in acidic soils, with soils from the Peruvian Amazon the most acidic and least diverse in our study. Our results suggest that microbial biogeography is controlled primarily by edaphic variables and differs fundamentally from the biogeography of “macro” organisms.
Declarative memory consolidation in humans: A prospective functional magnetic resonance imaging study
Authors: Takashima A. , Petersson K. M. , Rutters F. , Tendolkar I. , Jensen O. , Zwarts M. J. , McNaughton B. L. , Fernández G.
Published: January 2006

Retrieval of recently acquired declarative memories depends on the hippocampus, but with time, retrieval is increasingly sustainable by neocortical representations alone. This process has been conceptualized as system-level consolidation. Using functional magnetic resonance imaging, we assessed over the course of three months how consolidation affects the neural correlates of memory retrieval. The duration of slow-wave sleep during a nap/rest period after the initial study session and before the first scan session on day 1 correlated positively with recognition memory performance for items studied before the nap and negatively with hippocampal activity associated with correct confident recognition. Over the course of the entire study, hippocampal activity for correct confident recognition continued to decrease, whereas activity in a ventral medial prefrontal region increased. These findings, together with data obtained in rodents, may prompt a revision of classical consolidation theory, incorporating a transfer of putative linking nodes from hippocampal to prelimbic prefrontal areas.
Global genetic positioning: Evidence for early human population centers in coastal habitats
Authors: Amos William , Manica Andrea
Published: January 2006

For an alternative perspective on relationships among human populations, we combined genetic and geographic information, using allele frequency gradients to place populations and individuals on the globe. Reanalyzing published data on 51 worldwide populations [Rosenberg, N. A., Pritchard, J. K., Weber, J. L., Cann, H. M., Kidd, K. K., Zhivitovsky, L. A. & Feldman, M. W. (2002)
Science
298, 2381–2385] reveals five geographic clusters lying in plausible sites either of early agricultural innovation or on ancient migration routes. Also, the inferred sites show significant association with coastlines, suggesting that most early humans lived near large bodies of water. Our approach is flexible, and developments should prove useful both for exploring historical demography and for the identification of likely origin for unknown forensic samples.
Immature dendritic cell-derived exosomes can mediate HIV-1 trans infection
Authors: Wiley Rebecca D. , Gummuluru Suryaram
Published: January 2006

Immature dendritic cells (DCs) capture HIV type 1 (HIV-1) and can transmit captured virus particles to T cells. In this report, we show that HIV-1 particles captured by DCs can be transmitted to T cells by exocytosis without
de novo
infection. Captured HIV-1 particles were rapidly endocytosed to tetraspan protein (CD9, CD63)-positive endocytic compartments that were reminiscent of multivesicular endosomal bodies. Furthermore, some of the endocytosed virus particles were constitutively released into the extracellular milieu in association with HLA-DR1
+
, CD1b
+
, CD9
+
, and CD63
+
vesicles (exosomes) and could initiate productive infections of CD4
+
target cells. Surprisingly, the exocytosed vesicle-associated HIV-1 particles from DCs were 10-fold more infectious on a perparticle basis than cell-free virus particles. These studies describe a previously undescribed mechanism of DC-mediated HIV-1 transmission and suggest that virus particle trafficking to multivesicular endosomal bodies and subsequent exocytosis can provide HIV-1 particles captured by DCs an avenue for immune escape.
CaMKII and Polo-like kinase 1 sequentially phosphorylate the cytostatic factor Emi2/XErp1 to trigger its destruction and meiotic exit
Authors: Hansen David V. , Tung Jeffrey J. , Jackson Peter K.
Published: January 2006

In vertebrate meiosis, unfertilized eggs are arrested in metaphase II by cytostatic factor (CSF), which is required to maintain mitotic cyclin-dependent kinase activity. Fertilization triggers a transient increase in cytosolic free Ca
2+
, which leads to CSF inactivation and ubiquitin-dependent cyclin destruction through the anaphase promoting complex or cyclosome (APC/C). The Ca
2+
/calmodulin-dependent protein kinase II (CaMKII) and the Polo-like kinase Plx1 are essential factors for Ca
2+
-induced meiotic exit, but the critical targets of these kinases were unknown. The APC/C inhibitor Emi2 or XErp1 has recently been characterized as a pivotal CSF component, required to maintain metaphase II arrest and rapidly destroyed in response to Ca
2+
signaling through phosphorylation by Plx1 and ubiquitination by the SCF
βTrCP
complex. An important question is how the increase in free Ca
2+
targets Plx1 activity toward Emi2. Here, we demonstrate that CaMKII is required for Ca
2+
-induced Emi2 destruction, and that CaMKII functions as a “priming kinase,” directly phosphorylating Emi2 at a specific motif to induce a strong interaction with the Polo Box domain of Plx1. We show that the strict requirement for CaMKII to phosphorylate Emi2 is a specific feature of CSF arrest, and we also use phosphatase inhibitors to demonstrate an additional mode of Emi2 inactivation independent of its destruction. We firmly establish the CSF component Emi2 as the first-known critical and direct target of CaMKII in CSF release, providing a detailed molecular mechanism explaining how CaMKII and Plx1 coordinately direct APC/C activation and meiotic exit upon fertilization.
TAF7: A possible transcription initiation check-point regulator
Authors: Gegonne Anne , Weissman Jocelyn D. , Zhou Meisheng , Brady John N. , Singer Dinah S.
Published: January 2006

Transcription consists of a series of highly regulated steps: assembly of a preinitiation complex (PIC) at the promoter nucleated by TFIID, followed by initiation, elongation, and termination. The present study has focused on the role of the TFIID component, TAF7, in regulating transcription initiation. In TFIID, TAF7 binds to TAF1 and inhibits its intrinsic acetyl transferase activity. We now report that although TAF7 remains bound to TAF1 and associated with TFIID during the formation of the PIC, TAF7 dissociates from the PIC upon transcription initiation. Entry of polymerase II into the assembling PIC is associated with TAF1 and TAF7 phosphorylation, coincident with TAF7 release. We propose that the TFIID composition is dynamic and that TAF7 functions as a check-point regulator suppressing premature transcription initiation until PIC assembly is complete.
Osmotic stress mechanically perturbs chemoreceptors in
Escherichia coli
Authors: Vaknin Ady , Berg Howard C.
Published: January 2006

Two-component signaling systems play a major role in the long-term adaptation of microorganisms to changes in osmolarity, but how osmoreceptors work is not well understood. Temporal changes in solute concentration are sensed by the chemotaxis system in
Escherichia coli
, enabling these bacteria to avoid regions of high osmolarity. To study how osmolarity is detected in this system, we fused yellow fluorescent protein (YFP) to the C terminus of the serine or aspartate chemoreceptor, monitored the steady-state fluorescence polarization of YFP, and found that the polarization decreased substantially upon addition of osmotic agents. This decrease was due to an increase in fluorescence resonance energy transfer between YFP fluorophores in adjacent homodimers within trimers of dimers. Thus, changes in homodimer spacing and/or orientation appear to initiate osmotactic signaling.
Imaging membrane potential in dendritic spines
Authors: Nuriya Mutsuo , Jiang Jiang , Nemet Boaz , Eisenthal Kenneth B. , Yuste Rafael
Published: January 2006

Dendritic spines mediate most excitatory inputs in the brain. Although it is clear that spines compartmentalize calcium, it is still unknown what role, if any, they play in integrating synaptic inputs. To investigate the electrical function of spines directly, we used second harmonic generation (SHG) imaging of membrane potential in pyramidal neurons from hippocampal cultures and neocortical brain slices. With FM 4-64 as an intracellular SHG chromophore, we imaged membrane potential in the soma, dendritic branches, and spines. The SHG response to voltage was linear and seemed based on an electro-optic mechanism. The SHG sensitivity of the chromophore in spines was similar to that of the parent dendritic shaft and the soma. Backpropagation of somatic action potentials generated SHG signals at spines with similar amplitude and kinetics to somatic ones. Our optical measurements of membrane potential from spines demonstrate directly that backpropagating action potentials invade the spines.
Cyclin-dependent kinase 5 activity regulates pain signaling
Authors: Pareek Tej K. , Keller Jason , Kesavapany Sashi , Pant Harish C. , Iadarola Michael J. , Brady Roscoe O. , Kulkarni Ashok B.
Published: January 2006

Several molecules and cellular pathways have been implicated in nociceptive signaling, but their precise molecular mechanisms have not been clearly defined. Cyclin-dependent kinase 5 (Cdk5) is a proline-directed serine/threonine kinase implicated in the development and disease of the mammalian nervous system. The precise role of this kinase in sensory pathways has not been well characterized. Here we report a molecular role for Cdk5 in nociception. We identified the expression of Cdk5 and its activator p35 in nociceptive neurons, which is modulated during a peripheral inflammatory response. Increased calpain activity in sensory neurons after inflammation resulted in the cleavage of p35 to p25, which forms a more stable complex with Cdk5 and, consequently, leads to elevation of Cdk5 activity. p35 knockout mice (p35–/–), which exhibit significantly decreased Cdk5 activity, showed delayed responses to painful thermal stimulation compared with WT controls. In contrast, mice overexpressing p35, which exhibit elevated levels of Cdk5 activity, were more sensitive to painful thermal stimuli than were controls. In conclusion, our data demonstrate a role for Cdk5/p35 activity in primary afferent nociceptive signaling, suggesting that Cdk5/p35 may be a target for the development of analgesic drugs.
Microcalcifications of the breast: how does radiologic classification correlate with histology?
Authors: Müller-Schimpfle M. , Wersebe A. , Xydeas T. , Fischmann A. , Vogel U. , Fersis N. , Claussen C. D. , Siegmann K.
Published: January 2006

Purpose: To assess the correlation between the pre-biopsy classification of microcalcifications and the underlying histology.

Material and Methods: Using the morphology and distribution patterns according to the Breast Imaging-Reporting and Data System (BI-RADS®) lexicon, the microcalcifications of 199 lesions in 163 consecutive patients scheduled to undergo 11 G vacuum core biopsy were classified within the BI-RADS® categories. The correlation between BI-RADS® assessment categories 3, 4, and 5 and the final histological results was statistically evaluated with the χ2 test. The diagnostic indices were calculated.

Results: The prospectively classified BI-RADS® 3/4/5 findings revealed a malignant histology in 5.9%/17.6%/90.9% of all lesions, respectively. The relationship between BI-RADS® categories 3, 4, and 5 and histology was statistically highly significant ( P<0.0001). The sensitivity, specificity, positive and negative predictive values were 95.7%/21.2%/37.8%/94.3%, respectively.

Conclusion: The BI-RADS® lexicon describes microcalcifications of the breast and provides diagnostic categories that lead to standardized biopsy recommendations. Nevertheless, how to link description to classification of microcalcifications is still a difficult diagnostic task. The evaluation of microcalcifications as proposed in this article may help to set standards in the clinical routine and in the comparability of scientific data.
Renal artery stenosis evaluated with 3D-gd-magnetic resonance angiography using transstenotic pressure gradient as the standard of reference. a multireader study
Authors: Eklöf H. , Ahlstrom H. , Bostrom A. , Bergqvist D. , Andrén B. , Karacagil S. , Nyman R.
Published: January 2006

Purpose: To evaluate 3D-Gd-magnetic resonance angiography (MRA) in detecting hemodynamically significant renal artery stenosis (RAS).

Material and Methods: Thirty patients evaluated for atherosclerotic RAS by MRA and digital subtraction angiography (DSA) were retrospectively included. Standard of reference for hemodynamically significant RAS was a transstenotic gradient of 15 mmHg. DSA visualized 60 main renal arteries and 9 accessory arteries. Pressure gradient measurement (PGM) was available from 61 arteries. Three radiologists evaluated all examinations independently in a blinded fashion.

Results: RAS was present in 26 arteries. On MRA, each reader identified 4 of 9 accessory renal arteries, a detection rate of 44%. The three readers correctly classified 22/25/22 of the 26 vessels with a significant gradient as ⩾60% RAS and 31/25/32 of the 35 with no significant gradient as <60% RAS on MRA. Interobserver agreement was substantial. MRA image quality was adequate for RAS evaluations in all patients. ROC curves indicated that MRA is an adequate method for evaluating RAS. When screening for RAS, a 50% diameter reduction cut-off is better than 60%. RAS with 40–80% diameter reductions accounted for 65% of discrepancies.

Conclusion: MRA is an adequate method for evaluating RAS limited mainly by poor detection rate for accessory renal arteries.
Sentinel node biopsy in breast cancer
Authors: Leidenius M. H. K.
Published: January 2006

In breast cancer, sentinel node biopsy (SNB) has replaced diagnostic axillary clearance (AC) in nodal staging in numerous breast surgery units all over the world. However, there is no international standard in imaging, harvesting, and histological examination of the sentinel nodes. SNB has been validated in nodal staging of small, unifocal, clinically axillary-node-negative tumors, with a false-negative rate of approximately 5% of all axillary-node-positive cases. Despite the false-negative results, the method is assumed to provide accurate nodal staging, revealing metastases that remain undetected in AC. Furthermore, clinically overt axillary metastases have been rare when omitting AC relying on tumor-negative sentinel node findings, at least during a short follow-up. SNB is associated with faster recovery and less long-term morbidity than AC. Although the results of the large randomized trials have still to come, SNB has become the standard of care in early breast cancer.
An update on childhood snoring
Authors: Ng Daniel K. , Chow Pok‐Yu , Chan Chung‐Hong , Kwok Ka‐Li , Cheung Josephine M. , Kong Flora Y.
Published: January 2006

Habitual snoring or daily snoring is a symptom of sleep‐disordered breathing (SDB) in children and it is reported in about 10% of children. SDB includes primary snoring, upper airway resistance syndrome (UARS), obstructive hypoventilation syndrome and obstructive sleep apnea syndrome (OSAS). Classification of SDB in a particular snoring child requires an overnight polysomnography (PSG). Manual scoring of PSG is mandatory in children. Risk factors for SDB include allergic rhinitis, passive smoking, obesity, dysmorphic syndromes and neuromuscular disorders. Conclusion: Treatment includes general measures like treatment of allergic rhinitis, weight reduction in obese children, and avoidance of sleep deprivation. Specific measures include removal of adenoid and tonsils. Complications of SDB include neurocognitive impairment, hypertension and failure to thrive.
Stat3 regulates microtubules by antagonizing the depolymerization activity of stathmin
Authors: Ng Dominic Chi Hiung , Lin Bao Hong , Lim Cheh Peng , Huang Guochang , Zhang Tong , Poli Valeria , Cao Xinmin
Published: January 2006

Stat3 is a member of the signal transducer and activator of transcription family, which is important in cytokine signaling. Gene ablation studies have revealed a requirement for Stat3 in diverse biological processes (Akira, S. 2000. Oncogene. 19: 2607–2611; Levy, D.E., and C.K. Lee. 2002. J. Clin. Invest. 109:1143–1148). Previously, the function of Stat3 had been attributed exclusively to its transcriptional activity in the nucleus. In this study, we reveal an interaction between Stat3 and the microtubule (MT)-destabilizing protein stathmin. Stathmin did not overtly affect ligand-stimulated Stat3 activation. In contrast, the expression of Stat3 is required for the stabilization of MTs and cell migration. We further demonstrate that Stat3-containing cells are resistant to the MT-destabilizing effect of stathmin overexpression. In addition, down-regulation of stathmin protein levels in Stat3-deficient cells partially reversed the MT and migration deficiencies. Recombinant Stat3 was also capable of reversing stathmin inhibition of tubulin polymerization in vitro. Our results indicate that Stat3 modulates the MT network by binding to the COOH-terminal tubulin-interacting domain of stathmin and antagonizing its MT destabilization activity.
Focal adhesion size controls tension-dependent recruitment of α-smooth muscle actin to stress fibers
Authors: Goffin Jérôme M. , Pittet Philippe , Csucs Gabor , Lussi Jost W. , Meister Jean-Jacques , Hinz Boris
Published: January 2006

Expression of α-smooth muscle actin (α-SMA) renders fibroblasts highly contractile and hallmarks myofibroblast differentiation. We identify α-SMA as a mechanosensitive protein that is recruited to stress fibers under high tension. Generation of this threshold tension requires the anchoring of stress fibers at sites of 8–30-μm-long “supermature” focal adhesions (suFAs), which exert a stress approximately fourfold higher (∼12 nN/μm2) on micropatterned deformable substrates than 2–6-μm-long classical FAs. Inhibition of suFA formation by growing myofibroblasts on substrates with a compliance of ≤11 kPa and on rigid micropatterns of 6-μm-long classical FA islets confines α-SMA to the cytosol. Reincorporation of α-SMA into stress fibers is established by stretching 6-μm-long classical FAs to 8.1-μm-long suFA islets on extendable membranes; the same stretch producing 5.4-μm-long classical FAs from initially 4-μm-long islets is without effect. We propose that the different molecular composition and higher phosphorylation of FAs on supermature islets, compared with FAs on classical islets, accounts for higher stress resistance.
Follistatin induction by nitric oxide through cyclic GMP: a tightly regulated signaling pathway that controls myoblast fusion
Authors: Pisconti Addolorata , Brunelli Silvia , Di Padova Monica , De Palma Clara , Deponti Daniela , Baesso Silvia , Sartorelli Vittorio , Cossu Giulio , Clementi Emilio
Published: January 2006

The mechanism of skeletal myoblast fusion is not well understood. We show that endogenous nitric oxide (NO) generation is required for myoblast fusion both in embryonic myoblasts and in satellite cells. The effect of NO is concentration and time dependent, being evident only at the onset of differentiation, and direct on the fusion process itself. The action of NO is mediated through a tightly regulated activation of guanylate cyclase and generation of cyclic guanosine monophosphate (cGMP), so much so that deregulation of cGMP signaling leads to a fusion-induced hypertrophy of satellite-derived myotubes and embryonic muscles, and to the acquisition of fusion competence by myogenic precursors in the presomitic mesoderm. NO and cGMP induce expression of follistatin, and this secreted protein mediates their action in myogenesis. These results establish a hitherto unappreciated role of NO and cGMP in regulating myoblast fusion and elucidate their mechanism of action, providing a direct link with follistatin, which is a key player in myogenesis.
An intramolecular t-SNARE complex functions in vivo without the syntaxin NH2-terminal regulatory domain
Authors: Van Komen Jeffrey S. , Bai Xiaoyang , Scott Brenton L. , McNew James A.
Published: January 2006

Membrane fusion in the secretory pathway is mediated by SNAREs (located on the vesicle membrane [v-SNARE] and the target membrane [t-SNARE]). In all cases examined, t-SNARE function is provided as a three-helix bundle complex containing three ∼70–amino acid SNARE motifs. One SNARE motif is provided by a syntaxin family member (the t-SNARE heavy chain), and the other two helices are contributed by additional t-SNARE light chains. The syntaxin family is the most conformationally dynamic group of SNAREs and appears to be the major focus of SNARE regulation. An NH2-terminal region of plasma membrane syntaxins has been assigned as a negative regulatory element in vitro. This region is absolutely required for syntaxin function in vivo. We now show that the required function of the NH2-terminal regulatory domain (NRD) of the yeast plasma membrane syntaxin, Sso1p, can be circumvented when t-SNARE complex formation is made intramolecular. Our results suggest that the NRD is required for efficient t-SNARE complex formation and does not recruit necessary scaffolding factors.