bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution of the F374 Allele of the SLC45A2 (MATP) Gene and Founder‐Haplotype Analysis
Authors: Yuasa I. , Umetsu K. , Harihara S. , Kido A. , Miyoshi A. , Saitou N. , Dashnyam B. , Jin F. , Lucotte G. , Chattopadhyay P. K. , Henke L. , Henke J. 
Published: March 2006

SummaryThe membrane‐associated transporter protein (MATP) plays an important role in melanin synthesis. The L374F mutation in the SLC45A2 gene encoding MATP has been suggested to be associated with skin colour in major human populations. In this study more detailed distribution of the F374 allele was investigated in 1649 unrelated subjects from 13 Eurasian populations and one African population. The highest allele frequency was observed in Germans (0.965); French and Italians showed somewhat lower frequencies; and Turks had an intermediate value (0.615). Indians and Bangladeshis from South Asia were characterized by low frequencies (0.147 and 0.059, respectively). We also found the F374 allele in some East and Southeast Asian populations, and explained this by admixture. Haplotype analysis revealed that the haplotype diversity was much lower in Germans than in Japanese, and suggest that the L374F mutation occurred only once in the ancestry of Caucasians. The large differences in distribution of the F374 allele and its haplotypes suggest that this allele may be an important factor in hypopigmentation in Caucasian populations.
Trophic ecology of East African caecilians (Amphibia: Gymnophiona), and their impact on forest soil invertebrates
Authors: Jones D. T. , Loader S. P. , Gower D. J. 
Published: March 2006

AbstractDiets of the syntopic caecilian amphibians Boulengerula boulengeri and Scolecomorphus vittatus were studied from gut content analyses of 108 specimens collected from Nilo Forest Reserve, East Usambara Mountains, Tanzania. Head length and width relative to body length is greater in male B. boulengeri than in females, but no such dimorphism is apparent in S. vittatus. No differences, other than females consuming disproportionately more ants and invertebrate eggs and fewer termites than males, occur in the diets of B. boulengeri. The gut contents of S. vittatus are dominated by large, surface‐active earthworms, in contrast to those of B. boulengeri which contained smaller, endogeic earthworms and a much greater number and diversity of soil arthropods (particularly termites, ants and Diptera larvae). These dietary characteristics underline differences in microhabitat use between these caecilian species and thus corroborate a previously proposed hypothesis of niche separation. The ecological impact of caecilians and other limbless endogeic vertebrates is little studied and poorly known. Approximations based on current knowledge are not clear, but are interpreted as indicating that predation by caecilians is unlikely to be among the most important factors influencing population densities of soil‐dwelling termites and perhaps also ants: two groups recognized as soil ecosystem engineers.
Possible impact of snow depth and ungulate carcasses on red fox (Vulpes vulpes) populations in Norway, 1897–1976
Authors: Selås V. , Vik J. O. 
Published: March 2006

AbstractDuring the 1900s, the number of red foxes Vulpes vulpes increased in northern Europe. At higher altitudes and latitudes, red fox populations are likely to be limited by thick snow cover, which makes small rodents less available. The negative effects of snow could, however, be compensated for by high ungulate numbers, because of increased availability of carcasses in snow‐rich winters. In the period 1897–1932, the number of foxes (mainly red foxes) killed was negatively related to snow depth indices in 13 of the 17 Norwegian counties. During 1947–1976, after a strong increase in ungulate and red fox numbers, the number of red foxes killed was negatively related to snow in only one county. The counties where ungulate density increased the most also had higher increases in the number of red fox bounties paid. The absence of large predators may at least partly be responsible for the strong increase in red fox populations, because eradication of large predators such as wolf Canis lupus in the late 1800s and early 1900s probably was a necessary condition for the strong increase in ungulate numbers, especially roe deer Capreolus capreolus.
Courtship and copulation, but not ejaculates, reduce the longevity of female field crickets (Gryllus bimaculatus)
Authors: Bateman P. W. , Ferguson J. W. H. , Yetman C. A. 
Published: March 2006

AbstractFemales of many taxa incur fitness costs from male sexual coercion and harassment leading to mating. Although male crickets cannot force copulations on females, female Gryllus bimaculatus in this study incurred significant reductions in longevity through being exposed to different levels of male courtship. Virgin females kept in isolation had the longest life spans. Reductions in longevity applied to females in sensory contact with males (without the opportunity to mate), females that courted and mated and females that mated but with fertilization being prevented. Females also incurred significant reductions in longevity when kept with other females, which may have been due to high levels of cannibalism. Consistent with previous studies, females appeared to incur no cost to longevity from receiving sperm or seminal fluid. It is known that female G. bimaculatus benefit genetically from multiple mating. However, this benefit could possibly be offset by the negative effect that male courtship and mating behaviour has on female longevity.
Home range, denning behaviour and microhabitat use of the carnivorous marsupial Dasyurus maculatus in eastern Australia
Authors: Glen A. S. , Dickman C. R. 
Published: March 2006

AbstractRadio‐tracking of spotted‐tailed quolls Dasyurus maculatus (Marsupialia: Dasyuridae) in the forested ranges of north‐eastern New South Wales revealed that home ranges were extensive, with males occupying large, overlapping ranges [minimum convex polygon (MCP) up to 757 ha] and females occupying smaller, non‐overlapping territories (MCP up to 175 ha). Quolls were partly arboreal, although most activity occurred on the ground or on fallen logs. Hollow logs were most frequently used as dens, but rock crevices, burrows, tree hollows and artificial structures were also used. Individual quolls were located in up to nine different dens and, with the exception of maternal dens, rarely sheltered in the same location on successive days. The large home ranges of the spotted‐tailed quoll and the non‐overlapping nature of female ranges necessitate very large areas of habitat to support viable populations. Fallen timber, used extensively for shelter and in travelling, may serve to enhance the quality of habitat for the species, and should be retained by forest and wildlife managers.
Population dynamics of two sympatric antelope species, grey rhebok (Pelea capreolus) and mountain reedbuck (Redunca fulvorufula), in a highveld grassland region of South Africa
Authors: Taylor W. A. , Skinner J. D. , Williams M. C. , Krecek R. C. 
Published: March 2006

AbstractPopulation dynamics of grey rhebok Pelea capreolus and mountain reedbuck Redunca fulvorufula were monitored at Sterkfontein Dam Nature Reserve in South Africa over three breeding seasons. Birth and death rates were recorded in both species, and causes of death were investigated. Immigration and emigration were monitored in grey rhebok. Grey rhebok bred seasonally, with 91% of lambs being born between November and February. The average fecundity rate was 74% and lamb sex ratios were 22M:19F. Mountain reedbuck also bred seasonally, with a birth peak between October and December. The average fecundity rate was 92%, and lamb sex ratios were 12M:8F. Most deaths in both species occurred between June and November each year. Sixteen grey rhebok deaths occurred during the study, of which 10 resulted from hypothermia during one spring snowfall event. This represented 27% of the population at the time. Males and females were affected to the same degree by the snow, but juveniles suffered more than adults. There was no evidence of infectious disease or predation. Forty‐three mountain reedbuck deaths occurred during the study, of which 32 resulted from hypothermia following the snowfall. This represented 51% of the population at the time. Females were affected by hypothermia more than males. There was no evidence of disease in the population from the examination of 41 culled animals, and no evidence of predation. Immigration and emigration within the grey rhebok population were uncommon, but dispersal of yearling males occurred every year between October and December when they were evicted from their natal herds. Herd structure of adult animals was very stable. In mountain reedbuck, emigration was very hard to detect.
Costs and benefits of flocking in foraging white‐fronted geese (Anser albifrons): effects of resource depletion
Authors: Amano T. , Ushiyama K. , Fujita G. , Higuchi H. 
Published: March 2006

AbstractThis study investigated the costs and benefits of flocking in white‐fronted geese Anser albifrons foraging on rice grains in Japan. The time budgets of focal geese were recorded, and the effects of flock size on the proportions of time spent in vigilant and agonistic behaviour were tested. The results showed that the decline in vigilance level and consequent increase in foraging time were beneficial results of flocking whereas agonistic interactions, a potential cost of flocking, did not increase with increasing flock size. However, seasonal variation in flock size suggested that exploitative competition could be a cost of flocking; the sizes of flocks in spring, when resource depletion had progressed, were significantly reduced compared with those in autumn. An experimental increase in rice density resulted in a significant increase in flock size. We conclude that the flock size of foraging white‐fronted geese is a result of compromise between a constant benefit of flocking (i.e. decline in vigilance level) and a cost of flocking varying with food abundance (i.e. exploitative competition).
Comparative signaling pathways of insulin‐like growth factor‐1 and brain‐derived neurotrophic factor in hippocampal neurons and the role of the PI3 kinase pathway in cell survival
Authors: Zheng Wen‐Hua , Quirion Rémi 
Published: March 2006

AbstractInsulin‐like growth factor‐1 (IGF‐1) and brain‐derived neurotrophic factor (BDNF) are trophic factors required for the viability and normal functions of various neuronal cells. However, the detailed intracellular mechanism(s) involved in these effects in neuronal cells remains to be fully elucidated. In present study, the respective intracellular signaling pathway induced by IGF‐1 and BDNF and their possible role in neuronal survival were investigated. Both IGF‐1 and BDNF protected hippocampal neurons from serum deprivation‐induced death with IGF‐1 apparently being more potent. Western blot analyses showed that both IGF‐1 and BDNF induced the activation of the phosphatidylinositide 3 kinase (PI3)/Akt (protein kinase B) kinase and the mitogen‐activated protein kinase (MAPK) pathways. The phosphorylation of Akt and its downstream target, FKHRL1, induced by IGF‐1 was rapid and sustained while that of MAPK was transient. The reverse situation was observed for BDNF. Moreover, IGF‐1 potently induced the tyrosine phosphorylation of insulin receptor substrate‐1 (IRS‐1) and its association with PI3 kinase while BDNF was weak in these assays. In contrast, the tyrosine phosphorylation of Shc proteins was dramatically stimulated by BDNF, with IGF‐1 having only a minimal effect. Most interestingly, only the inhibitor of the PI3K/Akt pathway, LY294002, was able to block the survival effects of both IGF‐1 and BDNF; an inhibitor of the MAPK pathway inhibitor, PD98059, being ineffective. Taken together, these data reveal that the survival properties of both IGF‐1 and BDNF against serum deprivation are mediated by the activation of the PI3K/Akt, but not the MAPK, pathway in hippocampal neurons.
Anticonvulsant action of hippocampal dopamine and serotonin is independently mediated by D2 and 5‐HT1A receptors
Authors: Clinckers Ralph , Smolders Ilse , Meurs Alfred , Ebinger Guy , Michotte Yvette 
Published: March 2006

AbstractThe present microdialysis study evaluated the anticonvulsant activity of extracellular hippocampal dopamine (DA) and serotonin (5‐HT) with concomitant assessment of the possible mutual interactions between these monoamines. The anticonvulsant effects of intrahippocampally applied DA and 5‐HT concentrations were evaluated against pilocarpine‐induced seizures in conscious rats. DA or 5‐HT perfusions protected the rats from limbic seizures as long as extracellular DA or 5‐HT concentrations ranged, respectively, between 70–400% and 80–350% increases compared with the baseline levels. Co‐perfusion with the selective D2 blocker remoxipride or the selective 5‐HT1A blocker WAY‐100635 clearly abolished all anticonvulsant effects. These anticonvulsant effects were mediated independently since no mutual 5‐HT and DA interactions were observed as long as extracellular DA and 5‐HT levels remained within these protective ranges. Simultaneous D2 and 5‐HT1A receptor blockade significantly aggravated pilocarpine‐induced seizures. High extracellular DA (> 1000% increases) or 5‐HT (> 900% increases) concentrations also worsened seizure outcome. The latter proconvulsive effects were associated with significant increases in extracellular glutamate (Glu) and mutual increases in extracellular monoamines. Our results suggest that, within a certain concentration range, DA and 5‐HT contribute independently to the prevention of hippocampal epileptogenesis via, respectively, D2 and 5‐HT1A receptor activation.
NAAG peptidase inhibition reduces locomotor activity and some stereotypes in the PCP model of schizophrenia via group II mGluR
Authors: Olszewski Rafal T. , Bukhari Noreen , Zhou Jia , Kozikowski Alan P. , Wroblewski Jarda T. , Shamimi‐Noori Susan , Wroblewska Barbara , Bzdega Tomasz , Vicini Stefano , Barton Franca B. , Neale Joseph H. 
Published: March 2006

AbstractPhencyclidine (PCP) administration elicits positive and negative symptoms that resemble those of schizophrenia and is widely accepted as a model for the study of this human disorder. Group II metabotropic glutamate receptor (mGluR) agonists have been reported to reduce the behavioral and neurochemical effects of PCP. The peptide neurotransmitter, N‐acetylaspartylglutamate (NAAG), is a selective group II agonist. We synthesized and characterized a urea‐based NAAG analogue, ZJ43. This novel compound is a potent inhibitor of enzymes, glutamate carboxypeptidase II (Ki = 0.8 nm) and III (Ki = 23 nm) that deactivate NAAG following synaptic release. ZJ43 (100 µm) does not directly interact with NMDA receptors or metabotropic glutamate receptors. Administration of ZJ43 significantly reduced PCP‐induced motor activation, falling while walking, stereotypic circling behavior, and head movements. To test the hypothesis that this effect of ZJ43 was mediated by increasing the activation of mGluR3 via increased levels of extracellular NAAG, the group II mGluR selective antagonist LY341495 was co‐administered with ZJ43 prior to PCP treatment. This antagonist completely reversed the effects of ZJ43. Additionally, LY341495 alone increased PCP‐induced motor activity and head movements suggesting that normal levels of NAAG act to moderate the effect of PCP on motor activation via a group II mGluR. These data support the view that NAAG peptidase inhibitors may represent a new therapeutic approach to some of the components of schizophrenia that are modeled by PCP.
Neurotrophin‐3 and a CREB‐mediated signaling pathway regulate Bcl‐2 expression in oligodendrocyte progenitor cells
Authors: Saini Harsimran S. , Gorse Karen M. , Boxer Linda M. , Sato‐Bigbee Carmen 
Published: March 2006

AbstractOur previous results suggested that the transcription factor CREB mediates the actions of neuroligands and growth factor signals that coupled to different signaling pathways may play different roles along oligodendrocyte (OLG) development. We showed before that CREB phosphorylation in OLG progenitors is up‐regulated by neurotrophin‐3 (NT‐3); and moreover CREB is required for NT‐3 to stimulate the proliferation of these cells. We now show that treatment of OLG progenitors with NT‐3 is also accompanied by an increase in the levels of the anti‐apoptotic protein Bcl‐2. Interestingly, the presence of a putative CREB binding site (CRE) in the Bcl‐2 gene raised the possibility that CREB could also be involved in regulating Bcl‐2 expression in the OLGs. Supporting this hypothesis, the NT‐3 dependent increase in Bcl‐2 levels is abolished by inhibition of CREB expression. In addition, transient transfection experiments using various regions of the Bcl‐2 promoter and mutation of the CRE site indicate a direct role of CREB in regulating Bcl‐2 gene activity in response to NT‐3. Furthermore, protein‐DNA binding assays show that the CREB protein from freshly isolated OLGs indeed binds to the Bcl‐2 promoter CRE. Together with our previous results, these observations suggest that CREB may play an important role in linking proliferation and survival pathways in the OLG progenitors.
Distinct aggregation and cell death patterns among different types of primary neurons induced by mutant huntingtin protein
Authors: Tagawa Kazuhiko , Hoshino Masataka , Okuda Tomohiro , Ueda Hiroko , Hayashi Hiroshi , Engemann Sabine , Okado Haruo , Ichikawa Masumi , Wanker Erich E. , Okazawa Hitoshi 
Published: March 2006

AbstractAggregation of disease proteins is believed to be a central event in the pathology of polyglutamine diseases, whereas the relationship between aggregation and neuronal death remains controversial. We investigated this question by expressing mutant huntingtin (htt) with a defective adenovirus in different types of neurons prepared from rat cerebral cortex, striatum or cerebellum. The distribution pattern of inclusions is not identical among different types of primary neurons. On day 2 after infection, cytoplasmic inclusions are dominant in cortical and striatal neurons, whereas at day 4 the ratio of nuclear inclusions overtakes that of cytoplasmic inclusions. Meanwhile, nuclear inclusions are always predominantly present in cerebellar neurons. The percentage of inclusion‐positive cells is highest in cerebellar neurons, whereas mutant htt induces cell death most remarkably in cortical neurons. As our system uses htt exon 1 protein and thus aggregation occurs independently from cleavage of the full‐length htt, our observations indicate that the aggregation process is distinct among different neurons. Most of the neurons containing intracellular (either nuclear or cytoplasmic) aggregates are viable. Our findings suggest that the process of mutant htt aggregation rather than the resulting inclusion body is critical for neuronal cell death.
AMPA receptor activation, but not the accumulation of endogenous extracellular glutamate, induces paralysis and motor neuron death in rat spinal cord in vivo
Authors: Corona Juan Carlos , Tapia Ricardo 
Published: March 2006

AbstractThe mechanisms of motor neuron (MN) degeneration in amyotrophic lateral sclerosis (ALS) are unknown, but glutamate‐mediated excitotoxicity may be involved. To examine directly this idea in vivo, we have used microdialysis in the rat lumbar spinal cord and showed that four‐ to fivefold increases in the concentration of endogenous extracellular glutamate during at least 1 h, by perfusion with the glutamate transport inhibitor l‐2,4‐trans‐pyrrolidine‐dicarboxylate, elicited no motor alterations or MN damage. Stimulation of glutamate release with 4‐aminopyridine induced transitory ipsilateral hindlimb muscular twitches but no MN damage. In contrast, perfusion of α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazole propionate (AMPA) did not modify glutamate levels but produced intense muscular spasms, followed by ipsilateral permanent hindlimb paralysis and a remarkable loss of MNs. These effects of AMPA were prevented by co‐perfusion with the AMPA receptor antagonist 2,3‐dihydroxy‐6‐nitro‐7‐sulfamoyl‐benzo(F)quinoxaline. Perfusion with NMDA or kainate produced no motor effects or MN damage. Thus, the elevation of endogenous extracellular glutamate in vivo due to blockade of its transport is innocuous for spinal MNs. Because this resistance is observed under the same experimental conditions in which MNs are highly vulnerable to AMPA, these results indicate that excitotoxicity due to this mechanism might not be an important factor in the pathogenesis of ALS.
Mutation of Trp84 and Asp313 of the dopamine transporter reveals similar mode of binding interaction for GBR12909 and benztropine as opposed to cocaine
Authors: Chen Nianhang , Zhen Juan , Reith Maarten E. A. 
Published: March 2006

AbstractThe different psychomotor‐stimulant effects of cocaine, GBR12909, and benztropine may partially stem from their different molecular actions on the dopamine transporter (DAT). To explore this possibility, we examined binding of these inhibitors to mutated DATs with altered Na+dependence of DAT activities and with enhanced binding of a cocaine analog, [3H]2β‐carbomethoxy‐3β‐(4‐fluorophenyl)tropane (CFT). In [3H]CFT competition assays with intact cells, the mutation‐induced change in the ability of Na+to enhance the apparent affinity of CFT, cocaine, GBR12909, and benztropine was inhibitor‐independent. Thus, for the four inhibitors, the curve of [Na+] versus apparent ligand affinity was steeper at W84L compared with wild type, shallower at D313N, and flat at W84LD313N. At each mutant, the apparent affinity of CFT and cocaine was enhanced regardless of whether Na+was present. However, the apparent affinity of GBR12909 and benztropine for W84L was reduced in the absence of Na+but near normal in the presence of 130 mmNa+, and that for D313N and W84LD313N was barely changed. At the single mutants, the alterations in Na+dependence and apparent affinity of the four inhibitors were comparable between [3H]CFT competition assays and [3H]dopamine uptake inhibition assays. These results demonstrate that DAT inhibitors producing different behavioral profiles can respond in an opposite way when residues of the DAT protein are mutated. For GBR12909 and benztropine, their cocaine‐like changes in Na+dependence suggest that they prefer a DAT state similar to that for cocaine. However, their cocaine‐unlike changes in apparent affinity argue that they, likely via their diphenylmethoxy moiety, share DAT binding epitopes that are different from those for cocaine.