bluuebunny/crossref_metadata_2025 huggingface dataset:
Mutational analyses of RB and BRCA2 as candidate tumour suppressor genes in parathyroid carcinoma
Authors: Shattuck Trisha M. , Kim Teresa S. , Costa Jessica , Yandell David W. , Imanishi Yasuo , Palanisamy Nallasivam , Gaz Randall D. , Shoback Dolores , Clark Orlo H. , Monchik John M. , Wierman Margaret E. , Hollenberg Anthony , Tojo Katsuyoshi , Chaganti R. S. K. , Arnold Andrew
Published: July 2003

objective Strong evidence indicates that at least one key tumour suppressor gene important for the development of malignant parathyroid tumours is located on chromosome 13, but the critical target gene remains unknown. Importantly, the region of acquired DNA loss includes two established tumour suppressor genes, the retinoblastoma gene, RB (RB1) and BRCA2. Resolution of whether RB or BRCA2 is the critical 13q tumour suppressor gene in parathyroid cancer requires analysis of these genes’ sequences for intragenic inactivating mutations. Therefore, RB and BRCA2 were analysed in a group of parathyroid carcinomas in which mutations of these genes should be most readily detectable.

patients and design Six parathyroid carcinomas from four patients which showed loss of heterozygosity (LOH) at the RB locus and/or 13q loss by comparative genomic hybridazation (CGH) were selected from a CGH/LOH‐screened panel of 16 carcinoma specimens from 10 patients. These tumours were examined for mutations by direct sequencing of the complete 27‐exon coding region, intron–exon boundaries and promoter of RB. The 26 coding exons and intron–exon boundaries of BRCA2 were also directly sequenced in seven parathyroid carcinomas with loss in the BRCA2 region.

results No microdeletions, insertions, or point mutations were detected in either RB or BRCA2 in any of the carcinomas.

conclusion The absence of tumour‐specific somatic mutations in RB and BRCA2 suggests that they are unlikely to act as classic tumour suppressor genes in the pathogenesis of parathyroid carcinomas. While decreased expression of these genes might contribute to parathyroid carcinomatosis in a secondary fashion and 13q loss warrants further study as a diagnostic marker for parathyroid carcinoma, the putative 13q tumour suppressor awaits identification.
The effect of body weight and weight loss on thyroid volume and function in obese women
Authors: Sari Ramazan , Balci Mustafa Kemal , Altunbas Hasan , Karayalcin Umit
Published: July 2003

objective Thyroid volume and thyroid function may vary in obese and nonobese women. It is not known whether weight loss could affect thyroid volume and function in obese subjects.

patients and methods The study population consisted of 98 premenopausal euthyroid obese [body mass index (BMI) = 30 kg/m2] women (mean age 40·5 ± 11·4 years) and 31 nonobese (BMI < 25 kg/m2) women (mean age 38·6 ± 12·9 years). Weight, height, BMI, waist circumference, body fat percentage and fat weight of all subjects were measured. Thyroid function and thyroid ultrasonography were performed at baseline and after 6 months of obesity treatment. Subgroup analysis was done according to weight loss.

results Thyroid volume (P = 0·021) and TSH concentration (P = 0·047) were higher; free T3 (P < 0·001) and free T4 concentrations (P = 0·045) were lower in obese women; however, all were still in the normal range. There was a positive correlation between thyroid volume and body weight (r = 0·319, P = 0·002), BMI (r = 0·504, P < 0·001), body fat percentage (r = 0·375, P = 0·001), body fat weight (r = 0·309, P = 0·01) and waist circumference (r = 0·386, P = 0·004). There was a positive correlation between TSH concentration and body weight (r = 0·227, P = 0·042) and body fat weight (r = 0·268, P = 0·038). After 6 months of obesity treatment, thyroid volume (P = 0·008) and TSH concentration (P = 0·006) decreased only in obese women who lost > 10% body weight. There was a positive correlation between the changes of thyroid volume and the change of body weight (r = 0·341, P = 0·009) and the change of body fat weight (r = 0·406, P = 0·013).

conclusions Our study suggests that thyroid volume and function may vary in obese women in association with body weight and fat mass; > 10% weight loss may affect thyroid volume and function, which however, is clinically insignificant.
ACE DD genotype: an independent predisposition factor to venous thromboembolism
Authors: Fatini C. , Gensini F. , Sticchi E. , Battaglini B. , Prisco D. , Fedi S. , Brunelli T. , Marcucci R. , Conti A. A. , Gensini G. F. , Abbate R.
Published: July 2003

Background The renin angiotensin system affects haemostasis through different mechanisms; data on the possible role of angiotensin‐converting enzyme I/D polymorphism in the pathogenesis of deep venous thrombosis are conflicting, and no information is available regarding the A1166C polymorphism of the angiotensin type 1 receptor gene. In order to investigate this issue, angiotensin‐converting enzyme and AT1R polymorphisms were genotyped in 336 consecutive venous thromboembolism patients and 378 controls.

Materials and methods Haemostasis‐related risk factors have been evaluated by routine tests. Factor V Leiden, Factor II (G20210A), angiotensin‐converting enzyme (I/D), and angiotensin type 1 receptor (A1166C) polymorphisms have been identified by molecular analysis.

Results We documented a significant association between angiotensin‐converting enzyme DD genotype and venous thromboembolism (OR = 2·19 95%CI 1·51–3·17 adjusted for acquired and haemostasis‐related risk factors, P < 0·0001); in patients with haemostasis‐related risk factors, angiotensin‐converting enzyme DD genotype modified the risk of venous thromboembolism in hyperhomocysteinaemic and Factor V Leiden patients and was associated with the risk of recurrent venous thromboembolism (OR = 1·83 95%CI 1·06–3·17 P = 0·03). In patients without haemostasis‐related risk factors the angiotensin‐converting enzyme DD genotype was still an independent predictor of venous thromboembolism (OR = 3·29 95%CI 2·17–4·98 adjusted for acquired risk factors, P < 0·0001). No significant association between the angiotensin type 1 receptor CC genotype and venous thromboembolism was found.

Conclusions This study shows that angiotensin‐converting enzyme DD genotype represents a susceptibility marker of thrombosis in subjects apparently without predisposing factors and traditional thrombophilic alterations, and increases the risk of venous thromboembolism in subjects in whom a thrombogenic condition occurs. Moreover, angiotensin‐converting enzyme DD genotype may be considered a new predisposing factor to venous thromboembolism recurrence.
Metalloproteinases 2 and 9 are increased in plasma of patients with heart failure
Authors: Altieri P. , Brunelli C. , Garibaldi S. , Nicolino A. , Ubaldi S. , Spallarossa P. , Olivotti L. , Rossettin P. , Barsotti A. , Ghigliotti G.
Published: July 2003

Background Progression of heart failure is associated with interstitial changes in the heart and in areas distant from the heart. Enhanced expression of metalloproteinases 2 and 9 and of metalloproteinases tissue inhibitors 1 and 2 have been found in ventricular tissue of patients with heart failure. Our aim was to determine whether increased activity of metalloproteinase‐2, metalloproteinase‐9 and of metalloproteinases tissue inhibitor‐1 and metalloproteinases tissue inhibitor‐2 were also present in plasma of patients with heart failure.

Design Levels of metalloproteinase‐2, metalloproteinase‐9 and of metalloproteinase tissue inhibitor‐1 and metalloproteinases tissue inhibitor‐2 were measured in venous blood of 51 patients with heart failure, and were compared with levels of 52 control subjects. Samples collected from patients and control subjects were assayed for gelatinolytic activity (zymography) and for protein levels.

Results Compared with the control subjects, the patients with heart failure had a significant increase in activity levels (mean ± SE, ng mL−1) of prometalloproteinase‐9 (95·1 ± 11·2 and 38·9 ± 4·5*), activ. metalloproteinase‐9 (18·4 ± 2·5 and 10·9 ± 1·3*), and of prometalloproteinase‐2 (571·4 ± 26·1 and 456·8 ± 21·1*) (respectively: patients and control sub jects; *P < 0·05). Metalloproteinases tissue inhibitor‐1, but not metalloproteinases tissue inhibitor‐2 protein values were higher in the patients. Among the patients, clinical status and New York Heart Association (NYHA) class did not correlate with the metalloproteinase concentrations. Positive correlations with left ventricular volumes, and negative correlations with lipid values were obtained for prometalloproteinase‐2; positive correlations with total number of white cells and neutrophils were obtained for prometalloproteinase‐9; and positive correlations with lactate dehydrogenase, serum fibrinogen, aspartate transaminases were found for activ. metalloproteinase‐9.

Conclusions Regardless of the clinical phase of heart failure, elevated levels of activity and of circulating metalloproteinase protein levels suggest the presence of persistent extracellular remodeling in patients with heart failure.
Immunoglobulin light chains modulate polymorphonuclear leucocyte apoptosis
Authors: Cohen G. , Rudnicki M. , Deicher R. , Hörl W. H.
Published: July 2003

Background Apoptosis of polymorphonuclear leucocytes (PMNLs) is important for the resolution of inflammation. Recently, we demonstrated that glucose‐modified proteins increase PMNL apoptosis. No protein factors in sera of uraemic patients attenuating PMNL apoptosis have been identified to date.

Materials and methods We tested the influence of commercially available monoclonal immunoglobulin light chains (IgLCs) from multiple myeloma patients and polyclonal IgLCs isolated from haemodialysis patients, previously shown to modulate PMNL functions and to contribute to their prestimulation, on PMNL apoptosis. We detected morphological changes, DNA strand breaks and the loss of DNA content.

Results All three apoptosis assays showed that κ and λ type IgLCs increase the percentage of viable PMNLs by inhibiting apoptosis in a concentration‐dependent manner. The effect of IgLCs was abolished by specific antibodies. Addition of genistein abolished the reduction of PMNL apoptosis by IgLCs, suggesting that IgLCs exert their effect via tyrosine phosphorylation. Furthermore, we showed that the inhibition of caspase‐3 activity is involved in the decrease of PMNL apoptosis.

Conclusion In concentrations present in sera of uraemic patients IgLCs could interfere with the normal resolution of inflammation and thereby contribute to the chronic inflammatory state found in end‐stage renal disease patients.
Diagnosis of diabetic autonomic neuropathy: a multivariate approach
Authors: Diem P. , Laederach‐Hofmann K. , Navarro X. , Mueller B. , Kennedy W. R. , Robertson R. P.
Published: July 2003

Aim/hypothesis In the diagnosis of diabetic autonomic neuropathy (DAN) various autonomic tests are used. We took a novel statistical approach to find a combination of autonomic tests that best separates normal controls from patients with DAN.

Methods Twenty‐four patients with Type‐1 diabetes mellitus considered as having mild to moderate DAN as well as 10 normal, nondiabetic control subjects were analysed, searching for a test or a combination of tests that would optimally discriminate Type‐1 diabetes mellitus from controls. Variations of heart rate during deep breathing (ΔR6) and during a Valsalva manoeuvre (VR), the number of reactive sweat glands on the foot (testing sympathetic sudomotor function), and the response of human pancreatic polypeptide to hypoglycaemia [ln(ΔhPP + 1)] were evaluated.

Results Respective values for respective sensitivity and specificity values were: ΔR6, 96 and 70%; VR, 96 and 60%; sweat gland function, 71 and 90%; and ln(ΔhPP + 1), 71 and 90%. In a multivariate analysis approach a single discriminant function separating patients with Type‐1 diabetes mellitus from nondiabetic controls was generated {Logit P = 288·5 –[14·7 ΔR6]–[26·6 ln(ΔhPP + 1)]}. This function allowed complete separation of patients with Type‐1 diabetes mellitus from normal controls.

Conclusion/interpretation We conclude that the combined determination of ΔR6 and of ln (ΔhPP + 1) optimally separates subjects with parasympathetic impairment from normal subjects. In addition, this combination of tests may serve as a sensitive method for the assessment of DAN.
Do temporal arteritis lesions contain bacterial DNA?
Authors: Renko J. , Kalela A. , Karhunen P. J. , Helin H. , Sillanaukee P. , Nikkari S. , Nikkari S. T.
Published: July 2003

Background Temporal arteritis is a primary vascular inflammatory disease. The aetiology of temporal arteritis is unknown, but the influence of environmental factors such as infections has been suggested.

Materials and methods We used broad‐range PCR, targeting conserved regions of the gene encoding for ribosomal RNA, to detect bacterial DNA in 27 temporal artery biopsies. Five uninvolved temporal arteries were also included. A lung sample of confirmed bacterial pneumonia served as a positive control. Inflammation was examined by histochemistry and light microscopy.

Results The sensitivity of the broad‐range PCR assay was 5·0 fg of DNA. Bacterial DNA sequences were neither detected in 27 temporal arteritis specimens nor in the normal temporal artery samples. However, bacterial DNA was successfully amplified from the lung sample of a subject with pneumonia. In addition, human DNA was amplified by primers for human β‐actin from all clinical specimens, suggesting lack of significant inhibitors of the molecular amplification reaction. Histochemistry showed signs of strong inflammation in the arteritis samples.

Conclusions The lack of detectable amounts of bacterial DNA suggests that viable bacteria do not have a role in chronic stages of temporal arteritis. However, these findings do not rule out the possibility of bacterial degradation products as stimulants of chronic inflammation, or of viable microbes as triggering factors of acute temporal arteritis.
Use of a generalised linear model to test habitat preferences: the example of Zingel asper, an endemic endangered percid of the River Rhône
Authors: Labonne Jacques , Allouche Stephanie , Gaudin Philippe
Published: July 2003

SUMMARY 1. A study of microhabitat preferences was conducted on Zingel asper, an endangered endemic species from the Rhône catchment. A generalised linear model allowed us to test statistically the non‐random habitat selection and the effect of season and site on this habitat selection.

2. The analysis detected significant preferences for the three physical variables considered: water depth, water velocity and substratum size.

3. A seasonal shift in the substratum size preference was found: preference for stones increasing during the spawning season. Depth preference varied between sites, suggesting a possible plasticity in habitat selection.

4. These results suggest that the availability of suitable physical habitat plays a significant role in determining fish distribution in the River Beaume.
Quantitative trait loci conditioning transovarial transmission of La Crosse virus in the eastern treehole mosquito, Ochlerotatus triseriatus
Authors: Graham Douglas H. , Holmes Jennifer L. , Beaty Barry J. , Black William C.
Published: July 2003

Quantitative trait loci (QTL) affecting the ability of the Eastern treehole mosquito, Ochlerotatus triseriatus, to transovarially transmit (TOT) La Crosse virus (LAC) were mapped in an F1 intercross. The Holmen strain of O. triseriatus, previously selected for TOT refractoriness, was crossed to the AIDL strain that had been selected for TOT permissiveness. In P1 and F1 parents and 49 F2 individuals, regions of 10 cDNA loci were analysed with single strand conformation polymorphism (SSCP) analysis to identify and orientate linkage groups. Genotypes were also scored at fifty‐six random amplified polymorphic DNA (RAPD)‐SSCP loci. Twenty‐eight F2 offspring were individually analysed for TOT. Three QTL for TOT were detected with standard interval mapping on chromosomes II and III. Alleles at the three loci contributed additively towards determining the overall TOT rate and cumulatively accounted for ≈ 53% of the phenotypic variance in TOT.
Expression of an Aedes aegypti cation‐chloride cotransporter and its Drosophila homologues
Authors: Filippov V. , Aimanova K. , Gill S. S.
Published: July 2003

Insects maintain haemolymph homeostasis under different environmental conditions by modulating the concentrations of Na+, K+ and Cl– ions. One group of proteins involved in ion transport across cell membranes consists of cation‐chloride cotransporters that form a family of structurally similar proteins. Although much is known about these proteins in mammalian systems, our understanding of them in insects is lacking. The recent sequencing of two insect genomes, Drosophila and Anopheles, enabled us to identify globally members of the family of cation chloride cotransporters in these insects. Using RT‐PCR we monitored the transcription of members of this family in development and in several tissues. Our analyses showed that transcription of these genes differ considerably from the ubiquitously and highly expressed CG5594 gene to the almost silent gene CG31547. Comparison of Drosophila CG12773 and its Aedes homologue AaeCG12773 showed that they have similar transcript expression profiles. Immunohistochemical analysis of AaeCG1277 gene expression revealed that it is highly expressed in the gut of larvae and female adults but not in Malpighian tubules. A more detailed analysis showed that this protein is localized predominantly in the basolateral membrane of these tissues. This expression pattern confirmed the results of RT‐PCR analysis. We also created a mutant for one of the genes, CG10413, in Drosophila using P‐element excision. Analysis of this mutant showed this protein does not appear to be essential for development.
The AmCREB gene is an ortholog of the mammalian CREB/CREM family of transcription factors and encodes several splice variants in the honeybee brain
Authors: Eisenhardt D. , Friedrich A. , Stollhoff N. , Müller U. , Kress H. , Menzel R.
Published: July 2003

The transcription factor CREB (cAMP response element binding protein) is required for the switch from short‐term to long‐term synaptic plasticity and from short‐term to long‐term memory. Its activity is regulated by the cAMP‐dependent signalling cascade, which has been shown to play a crucial role in the honeybee's long‐term memory formation. To elucidate the role of the CREB in honeybee memory formation we analysed a CREB‐homologous gene, AmCREB, which is expressed as several transcripts in the honeybee brain. Eight transcripts have been identified (AmCREB 1–8) that are generated by alternate splicing. One antibody generated against a subset of these variants reveals a cytosolic localization in the mushroom body α‐lobes, the glomeruli of the antennal lobes, the protocerebral lobes, the central complex and in the optical lobes.
Transcriptome analysis of the cowpea weevil bruchid: identification of putative proteinases and α‐amylases associated with food breakdown
Authors: Pedra J. H. F. , Brandt A. , Westerman R. , Lobo N. , Li H.‐M. , Romero‐Severson J. , Murdock L. L. , Pittendrigh B. R.
Published: July 2003

We describe here the first systematic work to discover insect genes involved in food breakdown using a cDNA library enriched for gut‐expressed transcripts from Callosobruchus maculatus. A total of 1056 clones were screened for cDNA insert‐containing plasmids, and 503 nonredundant open reading frames were discovered. Twenty‐three inferred genes potentially involved in digestive processes in cowpea weevil were identified, including proteinases and amylases. The predicted catalytic sites were identified in the inferred cysteine and aspartic acid proteinases, and in α‐amylases. Transcriptome analysis of the cowpea bruchid will potentially permit gene discovery in other beetles, an insect order of major economic and ecological importance that is poorly represented in genomic databases.
Effects of refuge availability on the population dynamics ofTriatoma infestansin central Argentina
Authors: Cecere Maria C. , Canale Delmi M. , Gürtler Ricardo E.
Published: July 2003

As part of research on the control and mathematical modelling of transmission of Chagas disease, we tested the joint effects of refuge quantity and quality on the population dynamics ofTriatoma infestansin 12 experimental huts under natural climatic conditions in central Argentina.

The 2‐year trial involved three types of huts that mimicked rural houses, with a gradient of refuges determined by the type of thatched roof and whether the walls were plastered or not. Each treatment comprised three replicate huts and one control hut, each of which was a closed population that housed a chicken at night and was colonized with five virgin female and three maleT. infestansin mid‐summer. The replicate huts were dismantled monthly to count the number of live and deadT. infestansby stage and to mark the emerged insects. Control huts were dismantled only at the end of the first and second year to count the bugs.

The mean abundance of liveT. infestanswas significantly greater in huts with maximum (final mean 1834; range 337–3630 bugs) rather than intermediate (final mean 383; range 71–692 bugs) or minimum refuges (final mean 103; range 0–103 bugs). The bug populations under minimum refuges returned to baseline levels at 1 year post‐colonization and two populations went extinct.

Apparent female fecundity was affected significantly by refuge availability and time. Survival of the founder females until 1 year post‐colonization successively decreased from 20% to 7% and 0% in huts ranging from maximum to minimum refuges. The basic reproduction number Rosteadily decreased from 3·91 to 2·36–0·25 bugs per female bug in maximum to minimum refuge huts, respectively.

Synthesis and applications. Population persistence, growth rate and the maximum number ofT. infestansthat a hut may support depend on the physical structure for a fixed number of chickens, in agreement with the available experimental and field evidence. Environmental management measures, such as plastering of walls and wire‐fencing corrals, aimed at reducing the availability of refuges and oviposition sites may exert a strong adverse impact on the population dynamics ofT. infestans.
Foraging by bats in cleared, thinned and unharvested boreal forest
Authors: Patriquin Krista J. , Barclay Robert M. R.
Published: July 2003

Modern silvicultural methods employ various styles of selective harvesting in addition to traditional clear‐cutting. This can create a mosaic of patches with different tree densities that may influence habitat use by foraging bats. Use of forest patches may also vary among bat species due to variation in their manoeuvrability. Apart from studies investigating use of clear‐cuts, few have tested for differences in use of forest patches by bats, or for differences among bat species.

We investigated the influence of various harvesting regimes, which created forest patches of different tree densities, on habitat selection by foraging bats in the boreal mixed‐wood forest of Alberta, Canada. We also tested for variation in habitat selection among species related to differences in body size and wing morphology.

Over two summers we assessed habitat use by bats using ultrasonic detectors to count the echolocation passes of foraging bats. We measured activity in three forest types and four tree densities, ranging from intact (unharvested) forests to clear‐cuts.

Smaller, more manoeuvrable, species (Myotisspp.) were less affected by tree density than the larger, less manoeuvrable,Lasionycteris noctivagans. TwoMyotisspp. differed in their habitat use.Myotis lucifugus, an aerial insectivore, preferred to forage along the edge of clear‐cuts, whileM. septentrionalis, a species that gleans prey from surfaces, did not forage in clear‐cuts but preferred intact forest.

The largest species in our study,L. noctivagans, preferred clear‐cuts and avoided intact patches. There were therefore differences in habitat selection by foraging bats among the species in our study area, and these were correlated with size and wing morphology.

Synthesis and applications. Our results suggest that, in the short term, thinning has minimal effect on habitat use by bats. They also indicate that silvicultural methods have different immediate effects on different species of bats that may be obscured if the community is studied as a single entity. Management for forest‐dwelling bats must take such species‐specific effects into consideration. Harvesting that creates a mosaic of patches with different tree densities is likely to satisfy the requirements of more species than a system with less diverse harvesting styles.
Estimation of badger abundance using faecal DNA typing
Authors: Wilson G. J. , Frantz A. C. , Pope L. C. , Roper T. J. , Burke T. A. , Cheeseman C. L. , Delahay R. J.
Published: July 2003

Wildlife management and conservation programmes often require accurate information on population density, but this can be difficult to obtain, particularly when the species in question is nocturnal or cryptic. Badger populations in Britain are of intense management interest because they are a wildlife reservoir host of bovine tuberculosis (TB). Attempts to manage this infection in badgers, whether by population control or vaccination, require reliable methods of estimating population size. In addition, such estimates are also required to support research into badger ecology and TB epidemiology. Currently, the most accurate estimates of local badger population size are obtained from labour‐intensive and time‐consuming mark–recapture studies.

In recent years, DNA has been successfully extracted from the faeces of certain mammals, and used to generate a genetic profile of the defecating individual. Here we report on an application of this technology to estimate badger abundance.

Faecal samples were collected on 10 consecutive days from every freshly deposited dropping at latrine sites close to occupied setts in three badger social groups. Badger DNA was extracted from 89% of samples, and 20 different individuals were reliably identified. The genotypes derived from the faecal samples were compared with those obtained from blood or samples from badgers live trapped at the same setts.

The faecal genotypes from badgers with known trap histories revealed that latrines were used equally by males and females, and by badgers ranging in age from cubs (< 1 year old) to 9 years old. Individual badgers used the latrines on between one and six different nights. Rarefaction analysis produced abundance estimates that closely matched those obtained from live trapping.

Synthesis and applications. Systematic sampling and genetic typing of fresh faeces from badger latrines can provide data that can be used to estimate abundance accurately. This approach requires considerably less human resources than repeated live trapping and mark–recapture. The technique may be valuable for future badger research and management in relation to bovine TB, where accurate estimates of abundance at a local scale are required.
Vegetation dynamics on rangelands: a critique of the current paradigms
Authors: Briske D. D. , Fuhlendorf S. D. , Smeins F. E.
Published: July 2003

Rangeland ecologists have been debating the validity of two current paradigms for the evaluation of vegetation dynamics on rangelands. This debate frequently contrasts the conventional model of continuous and reversible vegetation dynamics (range model) with a more contemporary model that can accommodate discontinuous and non‐reversible vegetation change (state‐and‐transition model).

The range and the state‐and‐transition models are conceptually related to the equilibrium and non‐equilibrium paradigms within ecology, respectively. The methodological dichotomy that has developed between the range and the state‐and‐transition models has fostered the perception that these two ecological paradigms are mutually exclusive. We challenge this perception and contend that both methodologies and their corresponding paradigms are non‐exclusive.

Equilibrium and non‐equilibrium ecosystems are not distinguished on the basis of unique processes or functions, but rather by the evaluation of system dynamics at various temporal and spatial scales. Consequently, ecosystems may express both equilibrium and non‐equilibrium dynamics. This confirms early interpretations that ecosystems are distributed along a continuum from equilibrium to non‐equilibrium states.

Although both equilibrium and non‐equilibrium dynamics occur in numerous ecosystems, the empirical evidence is frequently confounded by (i) uncertainty regarding the appropriate evidence necessary to distinguish between paradigms; (ii) disproportionate responses among vegetation attributes to climate and grazing; (iii) comparisons among systems with varying degrees of managerial involvement; and (iv) the evaluation of vegetation dynamics at various spatial and temporal scales.

Synthesis and applications. This critique supports the conclusion that a paradigm shift has not taken place in rangeland ecology, but rather, the debate has forced a more comprehensive interpretation of vegetation dynamics along the entirety of the equilibrium–non‐equilibrium continuum. Therefore, the rangeland debate should be redirected from the dichotomy between paradigms to one of paradigm integration.
IRE1‐ and HAC1‐independent transcriptional regulation in the unfolded protein response of yeast
Authors: Schröder Martin , Clark Robert , Kaufman Randal J.
Published: July 2003

The unfolded protein response (UPR) is a signalling pathway leading to transcriptional activation of genes that protect cells from accumulation of unfolded proteins in the lumen of the endoplasmic reticulum (ER). In yeast, the only known ER stress signalling pathway originates at the type I transmembrane protein kinase/endoribonuclease Ire1p. Ire1p regulates synthesis of the basic leucine‐zipper (bZIP)‐containing transcription factor Hac1p by controlling splicing of HAC1 mRNA. Only spliced HAC1 mRNA (HAC1i) is translated, and Hac1ip activates transcription of genes that contain a conserved UPR element (UPRE) in their promoters. Here, we demonstrate that in addition to this well‐understood ER stress signalling pathway, a second, IRE1, HAC1 and UPRE‐independent mechanism for transcriptional activation upon ER stress, exists in yeast. A genetic screen identified recessive SIN4 alleles as suppressors of a defective UPR in ire1Δ strains. Elevation of basal transcription in sin4 strains or by tethering the RNA polymerase II holoenzyme with LexAp‐holoenzyme component fusion proteins to a promoter allowed for activation of the promoter by ER stress in an IRE1, HAC1 and UPRE‐independent manner. We propose that this novel second ER‐to‐nucleus signal transduction pathway culminates in core promoter activation (CPA) through stimulation of RNA polymerase II holoenzyme activity. Core promoter activation was observed upon diverse cellular stresses, suggesting it represents a primordial stress‐induced gene activation mechanism.
Recovery of adhesion to chondroitin‐4‐sulphate in Plasmodium falciparum var CSA disruption mutants by antigenically similar PfEMP1 variants
Authors: Andrews Katherine T. , Pirrit Lindsay A. , Przyborski Jude M. , Sanchez Cecilia P. , Sterkers Yvon , Ricken Sigrid , Wickert Hannes , Lépolard Catherine , Avril Marion , Scherf Artur , Gysin Jürg , Lanzer Michael
Published: July 2003

Protection against maternal malaria has been associated with the acquisition of a specific antibody response that prevents adhesion of Plasmodium falciparum‐infected erythrocytes to the glycosaminoglycan chondroitin‐4‐sulphate (CSA), which is present in the placental intervillous space. These antibodies are directed against variant forms of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) that mediate binding to CSA. We have generated insertional disruption mutants of the gene encoding the CSA‐binding phenotype in the P. falciparum clone FCR3 (var CSA) to test the hypothesis that strategies targeting the parasite's determinant for this adhesive phenotype may prevent sequestration of infected erythrocytes in the placenta and hence the development of maternal malaria. The var CSA‐disruption mutants were initially unable to adhere to CSA; however, they could recover the phenotype after repeated selection over CSA. We show that recovery of CSA binding is var CSA independent and mediated by the activation of a novel var variant. Importantly, the corresponding PfEMP1 protein reacts with a monoclonal antibody recognizing the DBL3γ domain of the var CSA gene product, indicating that the DBL3γ CSA‐binding domains are conserved between these PfEMP1‐binding variants. Our data support strategies exploring these conserved epitopes as vaccine candidates against maternal malaria.
Bacterial shape
Authors: Young Kevin D.
Published: July 2003

‘Architecture is the adaptation of form to resist force’.

John Ruskin (1874)

In free‐living eubacteria an external shell of peptidoglycan opposes internal hydrostatic pressure and prevents membrane rupture and death. At the same time, this wall imposes on each cell a shape. Because shape is both stable and heritable, as is the ability of many organisms to execute defined morphological transformations, cells must actively choose from among a large repertoire of available shapes. How they do so has been debated for decades, but recently experiment has begun to catch up with theory. Two discoveries are particularly informative. First, specific protein assemblies, nucleated by FtsZ, MreB or Mbl, appear to act as internal scaffolds that influence cell shape, perhaps by correctly localizing synthetic enzymes. Second, defects in cell shape are correlated with the presence of inappropriately placed, metabolically inert patches of peptidoglycan. When combined with what we know about mutants affecting cellular morphology, these observations suggest that bacteria may fabricate specific shapes by directing the synthesis of two kinds of cell wall: a long‐lived, rigid framework that defines overall topology, and a metabolically plastic peptidoglycan whose shape is directed by internal scaffolds.
The COP9 signalosome is an essential regulator of development in the filamentous fungus Aspergillus nidulans
Authors: Busch Silke , Eckert Sabine E. , Krappmann Sven , Braus Gerhard H.
Published: July 2003

The COP9 signalosome (CSN) is a conserved multiprotein complex involved in regulation of eukaryotic development. The deduced amino acid sequences of two Aspergillus nidulans genes, csnD and csnE, show high identities to the fourth and fifth CSN subunits of higher eukaryotes. The csnD transcript is abundant during vegetative growth as well as development and the corresponding protein accumulates in the nucleus. Strains deleted for either csn gene are viable and show identical mutant phenotypes at conditions that allow development: hyphae appear partly red and contain cells of reduced size. Additionally, light dependence of propagation onset is affected. The Δcsn mutants are capable of initiating the sexual cycle and develop primordia, but maturation to sexual fruit bodies is blocked. This developmental arrest could not be overcome by overexpression of the sexual activator velvet (VEA). We conclude that the COP9 signalosome in A. nidulans is a key regulator of sexual development, and its proposed structural and functional conservation to the CSN of higher eukaryotes enables studies on this regulatory complex in a genetically amenable organism.
Low editing efficiency of GluR2 mRNA is associated with a low relative abundance of ADAR2 mRNA in white matter of normal human brain
Authors: Kawahara Yukio , Ito Kyoko , Sun Hui , Kanazawa Ichiro , Kwak Shin
Published: July 2003

The ionotropic glutamate receptor (GluR) subunits GluR2, GluR5 and GluR6 are subject to RNA editing at their Q/R sites, resulting in significant alterations in the channel properties of the receptors. RNA editing at the Q/R site of GluRs is both developmentally and regionally regulated. Here we provide the first quantitative measurements of both mRNAs of the GluR subunits and mRNAs of the RNA editing enzymes ADAR1–ADAR3 in a comparison of the efficiency of editing at the Q/R site with the expression levels of ADAR mRNA in human brain. We demonstrate that the Q/R site of GluRs in white matter is edited significantly less than in grey matter. In addition, by means of quantitative reverse transcription‐polymerase chain reaction methods, we demonstrate that the relative abundance of ADAR2 mRNA to GluR2 mRNA is significantly lower in white matter than in grey matter and that the GluR2 Q/R site editing decreased only when the ratio of ADAR2 mRNA (not that of ADAR1 mRNA) to GluR2 mRNA dropped below a threshold (20 × 10−3). These results suggest that Q/R site of GluRs editing is regulated in a regional, and hence presumably cell‐specific, manner and that the GluR2 Q/R site editing is critically regulated by ADAR2 in human brain.
Different α2 adrenoceptor subtypes control noradrenaline release and cell firing in the locus coeruleus of wildtype and monoamine oxidase‐A knockout mice
Authors: Owesson Catarina Å. , Seif Isabelle , McLaughlin Daniel P. , Stamford Jonathan A.
Published: July 2003

In this study, we investigated which subtype(s) of α2‐adrenoceptor control stimulated noradrenaline (NA) release and noradrenergic cell firing in the locus coeruleus (LC) of monoamine oxidase‐A knockout (MAO‐A KO) and C3H/HeJ wildtype mice. On short stimulus trains (10 pulses, 200 Hz), the α2 agonist dexmedetomidine (10 nm) reduced NA efflux by 78 ± 8% and 51 ± 8% in wildtype and MAO‐A KO mice, respectively. In both strains, BRL 44408 (100 nm) and ARC 239 (100 nm) each partially blocked the effect of dexmedetomidine. In MAO‐A KO mice, BRL 44408 (100 nm) increased evoked NA efflux on short trains while ARC 239 (100 nm) had no effect. The two antagonists in combination increased NA efflux (by 81 ± 34%, P < 0.001), significantly more than by BRL 44408 alone. Conversely, in wildtype mice, the α2‐adrenoceptor antagonists did not significantly increase LC NA efflux. On long stimuli (30 pulses, 10 Hz), NA efflux was increased by BRL 44408 (P < 0.001) but not by ARC 239. The effect of BRL 44408 was significantly greater in MAO‐A KO than wildtype mice (208 ± 43% vs. 113 ± 31% increase, P < 0.001). When we examined noradrenergic cell firing, we found that dexmedetomidine inhibited LC cell firing in both strains with comparable EC50 values (2–5 nm), although Emax was significantly lower in MAO‐A KO mice (P < 0.001). The agonist effect was antagonized by BRL 44408 (P < 0.001) in wildtype but not in MAO‐A KO mice, with a pKB of 7.75. ARC 239 had no effect on the agonist response in either strain. A combination of the antagonists was no more effective than BRL 44408 alone (in wildtypes) and had no effect in MAO‐A KO mice. Neither BRL 44408 nor ARC 239 affected basal LC cell firing in wildtype or MAO‐A KO mice. Collectively, these results suggest that, analogous to other monoamine cell groups, there are differences in the autoreceptor populations controlling NA efflux and LC cell firing and that important differences exist between MAO‐A KO and wildtype mice
Differential display implicates cyclophilin A in adult cortical plasticity
Authors: Arckens Lutgarde , Van der Gucht Estel , Van den Bergh Gert , Massie Ann , Leysen Inge , Vandenbussche E. , Eysel Ulf T. , Huybrechts Roger , Vandesande Frans
Published: July 2003

Removal of retinal input from a restricted region of adult cat visual cortex leads to a substantial reorganization of the retinotopy within the sensory‐deprived cortical zone. Little is known about the molecular mechanisms underlying this reorganization. We used differential mRNA display (DDRT‐PCR) to compare gene expression patterns between normal control and reorganizing visual cortex (area 17–18), 3 days after induction of central retinal lesions. Systematic screening revealed a decrease in the mRNA encoding cyclophilin A in lesion‐affected cortex. In situ hybridization and competitive PCR confirmed the decreased cyclophilin A mRNA levels in reorganizing cortex and extended this finding to longer postlesion survival times as well. Western blotting and immunocytochemistry extended these data to the protein level. In situ hybridization and immunocytochemistry further demonstrated that cyclophilin A mRNA and protein are present in neurons. To exclude the possibility that differences in neuronal activity per se can induce alterations in cyclophilin A mRNA and protein expression, we analyzed cyclophilin A expression in the dorsal lateral geniculate nucleus (dLGN) of retinally lesioned cats and in area 17 and the dLGN of isolated hemisphere cats. In these control experiments cyclophilin A mRNA and protein were distributed as in normal control subjects indicating that the decreased cyclophilin A levels, as observed in sensory‐deprived area 17 of retinal lesion cats, are not merely a reflection of changes in neuronal activity. Instead our findings identify cyclophilin A, classically considered a housekeeping gene, as a gene with a brain plasticity‐related expression in the central nervous system.
Identification of a novel alternative splicing isoform of human amyloid precursor protein gene, APP639
Authors: Tang Ke , Wang Chen , Shen Chengyong , Sheng Shuli , Ravid Rivka , Jing Naihe
Published: July 2003

Senile plaques, neurofibrillary tangles and amyloid‐laden cerebral vessels are characteristic features in the brains of individuals with Alzheimer's disease (AD). The principal component of amyloid in senile plaque and amyloid‐laden cerebral vessels is β‐amyloid (Aβ), a peptide proteolytically derived from a large amyloid precursor protein (APP). To date, several alternatively spliced human APP transcripts have been described. Here, we report the identification of a novel alternative splicing isoform of the human APP gene, APP639, which excludes exon 2 as well as exons 7 and 8. RT‐PCR and Southern blot analysis show that APP639 mRNA is expressed in many human fetal tissues. In contrast, the APP639 transcript is hardly detected in the aged human cerebral cortex from both pathologically confirmed sporadic AD cases and nondemented controls. However, APP639 mRNA exists in the adult human liver. Western blot analysis shows that the protein product produced from the APP639 cDNA could be recognized by the APP antibody, and it does lack the exon 2 coding region. These results suggest that APP639, a novel alternative splicing isoform of human APP gene, does exist in human tissues in vivo.
Postsynaptic M1 and M3 receptors are responsible for the muscarinic enhancement of retrograde endocannabinoid signalling in the hippocampus
Authors: Ohno‐Shosaku Takako , Matsui Minoru , Fukudome Yuko , Shosaku Jumpei , Tsubokawa Hiroshi , Taketo Makoto M. , Manabe Toshiya , Kano Masanobu
Published: July 2003

The cholinergic system is crucial for higher brain functions including learning and memory. These functions are mediated primarily by muscarinic acetylcholine receptors (mAChRs) that consist of five subtypes (M1–M5). A recent study suggested a novel role of acetylcholine as a potent enhancer of endocannabinoid signalling that acts retrogradely from postsynaptic to presynaptic neurons. In the present study, we further investigated the mechanisms of this cholinergic effect on endocannabinoid signalling. We made paired whole‐cell recordings from cultured hippocampal neurons, and monitored inhibitory postsynaptic currents (IPSCs). The postsynaptic depolarization induced a transient suppression of IPSCs (DSI), a phenomenon known to involve retrograde signalling by endocannabinoids. The cholinergic agonist carbachol (CCh) markedly enhanced DSI at 0.01–0.3 µm without changing the presynaptic cannabinoid sensitivity. The facilitating effect of CCh on DSI was mimicked by the muscarinic agonist oxotremorine‐M, whereas it was eliminated by the muscarinic antagonist atropine. It was also blocked by a non‐hydrolizable analogue of GDP (GDP‐β‐S) that was applied intracellularly to postsynaptic neurons. The muscarinic enhancement of DSI persisted to a substantial degree in the neurons prepared from M1‐knockout and M3‐knockout mice, but was virtually eliminated in the neurons from M1/M3‐compound‐knockout mice. CCh still enhanced DSI significantly under the blockade of postsynatpic K+ conductance, and did not significantly influence the depolarization‐induced Ca2+ transients. These results indicate that the activation of postsynaptic M1 and M3 receptors facilitates the depolarization‐induced release of endocannabinoids.
Production of new cells in the rat dentate gyrus over the lifespan: relation to cognitive decline
Authors: Bizon J. L. , Gallagher M.
Published: July 2003

The identification of neurogenesis in the dentate gyrus of adult mammals has sparked much interest in a functional role for these new neurons in hippocampal‐dependent cognition. The current investigation used a model of age‐related cognitive decline in rodents to study the relationship between changes in markers of neurogenesis and hippocampal function. New cell production in the granule cell layer was progressively reduced across the lifespan of male Long Evans rats, with a 40% reduction at middle age (13 months) and a reduction in excess of 80% in advanced age (25 months), compared with young mature adults (7 months). These effects of aging were not, however, predictive of cognitive status. In particular, the pronounced decrease in new cell production during aging did not distinguish among rats that varied over a wide range of cognitive abilities.
7‐Hydroxylated epiandrosterone (7‐OH‐EPIA) reduces ischaemia‐induced neuronal damage both in vivo and in vitro
Authors: Pringle Ashley K. , Schmidt Werner , Deans Jackie K. , Wulfert Ernst , Reymann Klaus G. , Sundstrom Lars E.
Published: July 2003

Recent evidence suggests that steroids such as oestradiol reduce ischaemia‐induced neurodegeneration in both in vitro and in vivo models. A cytochrome P450 enzyme termed cyp7b that 7‐hydroxylates many steroids is expressed at high levels in brain, although the role of 7‐hydroxylated steroids is unknown. We have tested the hypothesis that the steroid‐mediated neuroprotection is dependent on the formation of 7‐hydroxy metabolites. Organotypic hippocampal slice cultures were prepared from Wistar rat pups and maintained in vitro for 14 days. Cultures were then exposed to 3 h hypoxia and neuronal damage assessed 24 h later using propidium iodide fluorescence as a marker of cell damage. Neurodegeneration occurred primarily in the CA1 pyramidal cell layer. The steroids oestradiol, dehydroepiandrosterone and epiandrosterone (EPIA) were devoid of neuroprotective efficacy when present at 100 nm pre‐, during and post‐hypoxia. The 7‐hydroxy metabolites of EPIA, 7α‐OH‐EPIA and 7β‐OH‐EPIA significantly reduced neurotoxicity at 100 nm and 10 nm. 7β‐OH‐EPIA was also neuroprotective in two in vivo rat models of cerebral ischaemia: 0.1 mg/kg 7β‐OH‐EPIA significantly reduced hippocampal cell loss in a model of global forebrain ischaemia, whereas 0.03 mg/kg was neuroprotective in a model of focal ischaemia even when administration was delayed until 6 h after the onset of ischaemia. Taken together, these data demonstrate that 7‐hydroxylation of steroids confers neuroprotective efficacy, and that 7β‐OH‐epiandrosterone represents a novel class of neuroprotective compounds with potential for use in acute neurodegenerative diseases.