bluuebunny/crossref_metadata_2025 huggingface dataset:
Severely impaired neuromuscular synaptic transmission causes muscle weakness in the Cacna1a‐mutant mouse rolling Nagoya
Authors: Kaja Simon , Van De Ven Rob C. G. , Van Dijk J. Gert , Verschuuren Jan J. G. M. , Arahata Kiichi , Frants Rune R. , Ferrari Michel D. , Van Den Maagdenberg Arn M. J. M. , Plomp Jaap J.
Published: April 2007

The ataxic mouse rolling Nagoya (RN) carries a missense mutation in the Cacna1a gene, encoding the pore‐forming subunit of neuronal Cav2.1 (P/Q‐type) Ca2+ channels. Besides being the predominant type of Cav channel in the cerebellum, Cav2.1 channels mediate acetylcholine (ACh) release at the peripheral neuromuscular junction (NMJ). Therefore, Cav2.1 dysfunction induced by the RN mutation may disturb ACh release at the NMJ. The dysfunction may resemble the situation in Lambert–Eaton myasthenic syndrome (LEMS), in which autoantibodies target Cav2.1 channels at NMJs, inducing severely reduced ACh release and resulting in muscle weakness. We tested neuromuscular function of RN mice and characterized transmitter release properties at their NMJs in diaphragm, soleus and flexor digitorum brevis muscles. Clinical muscle weakness and fatigue were demonstrated using repetitive nerve‐stimulation electromyography, grip strength testing and an inverted grid hanging test. Muscle contraction experiments showed a compromised safety factor of neuromuscular transmission. In ex vivo electrophysiological experiments we found severely impaired ACh release. Compared to wild‐type, RN NMJs had 50–75% lower nerve stimulation‐evoked transmitter release, explaining the observed muscle weakness. Surprisingly, the reduction in evoked release was accompanied by an ∼ 3‐fold increase in spontaneous ACh release. This synaptic phenotype suggests a complex effect of the RN mutation on different functional Cav2.1 channel parameters, presumably with a positive shift in activation potential as a prevailing feature. Taken together, our studies indicate that the gait abnormality of RN mice is due to a combination of ataxia and muscle weakness and that RN models aspects of the NMJ dysfunction in LEMS.
A quantitative trait locus on chromosome 18 is a critical determinant of excitotoxic cell death susceptibility
Authors: Lorenzana Ariana , Chancer Zackary , Schauwecker P. Elyse
Published: April 2007

C57BL/6J (B6) and FVB/NJ (FVB) mice are phenotypically distinct in their susceptibility to seizure‐induced cell death after kainate administration. Previous studies using quantitative trait loci (QTLs) mapping established that the distal region of mouse chromosome 18 contains a gene(s) that is probably responsible for the difference in seizure‐induced cell death susceptibility between two inbred strains, B6 and FVB, that are relatively resistant and susceptible, respectively, to seizure‐induced cell death. The genetic locus has been mapped to a ∼12‐centimorgan region of chromosome 18, designated as seizure‐induced cell death 1 (Sicd1). In order to confirm the Sicd1 QTL, we have developed congenic mouse strains containing the relevant donor segment from the resistant B6 strain on the susceptible FVB background, also referred to as the FVB.B6‐Sicd1 congenic strain. Congenic and FVB littermate controls were tested in a seizure‐induced cell death paradigm. The presence of B6 chromosome 18 alleles on an FVB genetic background conferred protection against seizure‐induced cell death, as compared with FVB littermate controls. To further localize the Sicd1 QTL, new congenic lines carrying overlapping intervals of the B6 segment were created [interval‐specific congenic lines (ISCLs)‐1–4] and assessed for seizure‐induced cell death phenotype. All of the ISCLs exhibited reduced cell death associated with the B6 phenotype, as compared with the parental FVB strain. The most dramatic of these, ISCL‐4, showed a nearly four‐fold reduction in the extent of seizure‐induced cell death. This suggests that ISCL‐4 contains the putative gene(s) of the Sicd1 QTL.
Chronic liver failure in rats impairs glutamatergic synaptic transmission and long‐term potentiation in hippocampus and learning ability
Authors: Monfort Pilar , Erceg Slaven , Piedrafita Blanca , Llansola Marta , Felipo Vicente
Published: April 2007

Cognitive function is impaired in patients with liver disease by unknown mechanisms. Long‐term potentiation (LTP) in the hippocampus is considered the basis of some forms of learning and memory. The aims of this work were to assess (i) whether chronic liver failure impairs hippocampal LTP; (ii) if this impairment may be due to alterations in glutamatergic neurotransmission, and (iii) if impairment of LTP is associated with reduced learning ability. It is shown that liver failure in Wistar rats induces the following alterations in the hippocampus; (i) alters the phosphorylation of NMDA and AMPA receptors; (ii) reduces the expression of NMDA and AMPA receptors in membranes, (iii) reduces the magnitude of excitatory postsynaptic potentials (EPSPs) induced by activation of NMDA or AMPA receptors, and (iv) impairs NMDA receptor‐dependent LTP. Liver failure also impairs learning of the Morris water maze task. Impairment of glutamatergic synaptic transmission and NMDA receptor‐mediated responses may be involved in the alterations of cognitive function in patients with liver disease.
Event‐related potentials reflect heterogeneity of developmental prosopagnosia
Authors: Minnebusch Denise A. , Suchan Boris , Ramon Meike , Daum Irene
Published: April 2007

Event‐related potential (ERP) studies of developmental prosopagnosia (DP) are rare. Previous ERP investigations have reported smaller N170 amplitude differences between faces and objects in at least three prosopagnosics. The present study is based on a combination of behavioural and electrophysiological assessment of face processing. The aim was to investigate the face‐specifity of the N170 in both healthy subjects and a group of DP individuals (N = 4), using famous and nonfamous faces, caricatures and houses as stimuli. All prosopagnosic subjects showed impairments in recognition of famous faces, memory for faces and learning new faces in behavioural assessment. In healthy subjects the largest effects were found at parieto‐occipital electrode positions (PO7 and PO8), along with a familiarity effect at these electrode positions. Thus, parieto‐occipital areas appear to play an important role in face processing. Three prosopagnosics showed reliable N170 amplitude differences between faces and nonface stimuli, whereas one DP individual showed significantly reduced amplitude differences between faces and nonface objects. The behavioural and electrophysiological data support the idea that DP reflects a heterogeneous impairment and that face processing deficits are not necessarily correlated with a lack of face‐specific N170.
Preservation of visual cortical function following retinal pigment epithelium transplantation in the RCS rat using optical imaging techniques
Authors: Gias Carlos , Jones Myles , Keegan David , Adamson Peter , Greenwood John , Lund Ray , Martindale John , Johnston David , Berwick Jason , Mayhew John , Coffey Peter
Published: April 2007

The aim of this study was to determine the extent of cortical functional preservation following retinal pigment epithelium (RPE) transplantation in the Royal College of Surgeons (RCS) rat using single‐wavelength optical imaging and spectroscopy. The cortical responses to visual stimulation in transplanted rats at 6 months post‐transplantation were compared with those from age‐matched untreated dystrophic and non‐dystrophic rats. Our results show that cortical responses were evoked in non‐dystrophic rats to both luminance changes and pattern stimulation, whereas no response was found in untreated dystrophic animals to any of the visual stimuli tested. In contrast, a cortical response was elicited in most of the transplanted rats to luminance changes and in many of those a response was also evoked to pattern stimulation. Although the transplanted rats did not respond to high spatial frequency information we found evidence of preservation in the cortical processing of luminance changes and low spatial frequency stimulation. Anatomical sections of transplanted rat retinas confirmed the capacity of RPE transplantation to rescue photoreceptors. Good correlation was found between photoreceptor survival and the extent of cortical function preservation determined with optical imaging techniques. This study determined the efficacy of RPE transplantation to preserve visual cortical processing and established optical imaging as a powerful technique for its assessment.
Valproate robustly increases Sp transcription factor‐mediated expression of the dopamine transporter gene within dopamine cells
Authors: Wang Jun , Michelhaugh Sharon K. , Bannon Michael J.
Published: April 2007

Several lines of evidence suggest that valproate, a drug used in the treatment of mania and bipolar disorders, epilepsies, and addictions, may modulate dopamine transporter (DAT) function, yet the effects of valproate on DAT gene expression have not been directly assessed. Utilizing a human dopaminergic cell line and rat midbrain dopamine (DA) neurons in organotypic culture, we found that valproate increased endogenous DAT gene expression in a concentration‐ and time‐dependent manner. Given previous data demonstrating that members of the specificity protein (Sp) family of transcription factors are strong trans‐activators of DAT gene transcription, we investigated the Sp‐dependence of valproate effects. Valproate‐induced transcription of a DAT reporter construct was significantly attenuated by coexpression of a dominant negative form of Sp, mutation of a Sp‐responsive cis‐element, or expression in a Sp‐null cellular background (SL‐2 cells). Valproate significantly altered Sp protein abundance in both dopaminergic model systems employed. In summary, valproate treatment significantly increased DAT gene expression in a Sp transcription factor‐dependent manner. Some of valproate's therapeutic effects may involve activation of DAT gene expression.
Wheel running following spinal cord injury improves locomotor recovery and stimulates serotonergic fiber growth
Authors: Engesser‐Cesar Christie , Ichiyama Ronaldo M. , Nefas Amber L. , Hill Mary Ann , Edgerton V. Reggie , Cotman Carl W. , Anderson Aileen J.
Published: April 2007

Exercise, through manual step training, robotic step training or voluntary wheel running, is emerging as a promising therapy after spinal cord injury (SCI). Animal models provide a tool to investigate the mechanisms by which physical activity influences recovery from SCI. In the present study, we extend previous experiments showing improved recovery after SCI with both pre‐ and post‐injury running in a flat‐surface running wheel and investigate mechanisms of recovery. We tested a clinically relevant model using post‐injury wheel running, in which we provided mice with access to wheels either 3 days or 7 days/week. Open field behavior, observed for 15 weeks following moderate T9 contusion injury, showed a significant linear increase in locomotor improvements across groups, sedentary, 3‐day runners and 7‐day runners. Kinematic analysis of treadmill walking revealed that both wheel‐running groups, 3 and 7 days/week, improved stepping ability compared with sedentary controls. Stereological quantification of neuron number in the injured segment of the spinal cord revealed no differences between the groups. However, stereological quantification of serotonin immunostaining using isotropic virtual planes showed increases in serotonin fiber length caudal to the lesion in the running groups. These observations suggest that improvement in function may be related to changes in serotonin fibers immediately caudal to the injury epicenter.
Recombinant human erythropoietin suppresses symptom onset and progression of G93A‐SOD1 mouse model of ALS by preventing motor neuron death and inflammation
Authors: Koh Seong‐Ho , Kim Youngchul , Kim Hyun Young , Won Cho Goang , Kim Kyung Sook , Kim Seung H.
Published: April 2007

Multifactorial pathogenic mechanisms, including inflammation, attenuated survival signals and enhanced death signals, are involved in amyotrophic lateral sclerosis (ALS). Erythropoietin (EPO) has recently been highlighted as a cytokine with various potent neuroprotective effects, including reduction of inflammation, enhancement of survival signals and prevention of neuronal cell death. This study was undertaken to evaluate the effect of recombinant human EPO (rhEPO) on ALS model mice. We treated 96 ALS model mice with vehicle only, or 1, 2.5 or 5 iµ of rhEPO/g of mouse once every other week after they were 60 days old. The treatment significantly prolonged symptom onset and life span, preserved more motor neurons, enhanced survival signals, and attenuated inflammatory signals in a dose‐dependent manner. These data suggest that treatment with rhEPO represents a potential therapeutic strategy for ALS.
Structural and functional recovery elicited by combined putrescine and aminoguanidine treatment after aspirative lesion of the fimbria–fornix and overlying cortex in the adult rat
Authors: Muller Christophe , Herberth Heike , Cosquer Brigitte , Kelche Christian , Cassel Jean‐Christophe , Schimchowitsch Sarah
Published: April 2007

Damage to the adult CNS often causes permanent deficits. Based on a lesion model of septohippocampal pathway aspiration in the rat, we attempted to promote neuronal cell survival and post‐traumatic recovery by using a pharmalogical treatment combining aminoguanidine and putrescine (AGP). The functional recovery was followed over 15 weeks before morphological analysis. AGP treatment produced a persistent attenuation (∼ 50%) of the lesion‐induced hyperactivity, a reduction (∼ 60%) in the sensorimotor impairments and an improved performance in the water‐maze task which did not, however, rely upon improved memory capabilities. AGP weakened the lesion‐induced decrease in ChAT‐positive neurons in the medial septum and the extent of thalamic retrograde necrosis (by ∼ 30% in each case) and resulted in a partial cholinergic reinnervation of the dentate gyrus. These promising results support the idea that coadministration of putrescine and aminoguanidine might become a potent way to foster structural and functional recovery (or compensation) in the adult mammalian CNS after injury.
Contribution of clinical screening to carrier detection in a large Chinese family with fabry disease due to a novel alpha‐galactosidase A gene deletion
Authors: Ro L.‐S. , Chen C.‐M. , Chang H.‐S. , Lyu R.‐K. , Wu Y.‐R. , Hsu W.‐C. , Lee‐Chen G.‐J.
Published: April 2007

Diagnosis of heterozygous Fabry patients is difficult because of its variable clinical manifestations and overlapping serum α‐galactosidase A (AGA) activity between carriers and non‐carriers. We tried to facilitate diagnosis of heterozygous Fabry patients by detailed clinical examination. We analyzed clinical presentations, biochemical, electrophysiological and genetic characteristics of 16 patients with Fabry disease in a large Chinese family.

Male patients demonstrated significantly higher pain scores, poorer renal function, and higher frequency of hypohidrosis and corpora angiokeratomas than female patients. Interestingly, all the males and females had corneal verticilata by slit lamp examination. However, there was no association of serum AGA activity with renal function or pain symptom scores. The results indicated that detailed ocular and neurological examination might provide an alternative way of detecting heterozygous patients. We also report a novel large deletion spanning across the joint of Alu repetitive elements in introns 1 and 2 with resultant exon 2 deletion in a Chinese family with Fabry disease.
Episodic muscle pain, stiffness, and weakness associated with tubular aggregates and myoedema
Authors: Mahjneh I. , Lamminen A. , Tuominen H.
Published: April 2007

We report a 28‐year‐old man who suffered from episodic muscle pain, stiffness and weakness. His serum creatine kinase (CK) levels were found to be elevated. He presented with slight proximal muscle weakness and calf hypertrophy. Muscle biopsy revealed fiber size variation and tubular aggregates (TA). Muscle magnetic resonance imaging showed areas of edema. Other muscle pathologies known to be associated with TAs or myoedema were ruled out.
Mitofusin 2 gene mutation (R94Q) causing severe early‐onset axonal polyneuropathy (CMT2A)
Authors: Neusch C. , Senderek J. , Eggermann T. , Elolff E. , Bähr M. , Schneider‐Gold C.
Published: April 2007

Charcot‐Marie‐Tooth disease (CMT) has been classified into two types: demyelinating forms (CMT1) and axonal forms (CMT2). Mutations in the CMT2A locus have been linked to the KIF1B and the mitofusin 2 (MFN2) genes. Here, we report a German patient with CMT2 with an underlying spontaneous mutation (c.281G→A) in the MFN2 gene. Clinically, the patient presented with early‐onset CMT that was not associated with additional central nervous system pathology. The disease course was rapidly progressive in the first years and slowed afterwards. We also suggest that single patients with early‐onset axonal polyneuropathies should be screened for MFN2 mutations.
Intracranial dissemination of primary spinal cord anaplastic oligodendroglioma
Authors: Ramirez C. , Delrieu O. , Mineo J.‐F. , Paradot G. , Allaoui M. , Dubois F. , Blond S.
Published: April 2007

We report the first case of a 22‐year‐old man, with a previously neurosurgically treated intramedullary anaplastic oligodendroglioma (World Health Organization grade III), who developed 19 months later two histologically proven intracranial metastases. We support a hypothesis whereby the anaplastic parts of tumors have spread along the spinal cord and brainstem via the cerebrospinal fluid pathways, a process that could be promoted by surgical manipulation, although the relative contribution of the two factors remains speculative.
Plasma lipid peroxidation and progression of disability in multiple sclerosis
Authors: Koch M. , Mostert J. , Arutjunyan A. V. , Stepanov M. , Teelken A. , Heersema D. , De Keyser J.
Published: April 2007

Oxidative stress has been implicated in the pathophysiology of multiple sclerosis (MS), but its relation to disease progression is uncertain. To evaluate the relationship of plasma lipid peroxidation with progression of disability in MS, we measured blood plasma fluorescent lipid peroxidation products (PFLPP) levels in 23 patients with RRMS with a benign course, 32 with secondary progressive MS, 24 with primary progressive MS and 30 healthy controls. None of the patients had a relapse within the previous 3 months. Progression of disability was evaluated during a follow‐up period of 5 years by the Expanded Disability Status Scale (EDSS) and the Multiple Sclerosis Severity Score (MSSS). We found plasma PFLPP levels elevated in patients with MS compared with controls (P < 0.0001), but there was no difference between patients with a benign and progressive disease course. There was no correlation between PFLPP levels and worsening of disability on the EDSS and speed of progression on the MSSS. Our data suggest that there is no relation between the degree of oxidative stress in plasma and progression of disability in MS.
The societal costs of intracerebral hemorrhage in Spain
Authors: Navarrete‐Navarro P. , Hart W. M. , Lopez‐Bastida J. , Christensen M. C.
Published: April 2007

This study estimates the lifetime societal costs associated with incident intracerebral hemorrhage (ICH) in Spain. An epidemiological model of ICH incidence, survival and morbidity was developed using retrospective data from 28 hospitals in Andalusia and published data identified in a systematic literature review. Data on resource utilization and costs were obtained from five hospitals in the Canary Islands, whereas cost of outpatient care, informal care and lost productivity were obtained from standardized questionnaires completed by survivors of ICH. The lifetime societal costs of incident ICH in Spain is estimated at €46 193 per patient. Direct medical costs accounted for 32.7% of lifetime costs, whilst 67.3% were related to indirect costs. One‐third of direct medical costs over the first year were attributable to follow‐up care, including rehabilitation. Indirect costs were dominated by costs of informal care (71.2%). The aggregated lifetime societal costs for the estimated 12 534 Spanish patients with a first‐ever ICH in 2004 was €579 million. ICH implies substantial costs to society primarily due to formal and informal follow‐up care and support needed after hospital discharge. Interventions that offer survival benefits without improving patients’ functional status are likely to further increase the societal costs of ICH.
Microfabrics of UHP metamorphic granites in the Dora Maira Massif, western Alps – no evidence of deformation at great depth
Authors: LENZE A. , STÖCKHERT B.
Published: April 2007

In the Dora Maira Massif, western Alps, essentially undeformed ultrahigh‐pressure (UHP) metamorphic granites (Brossasco granite) are embedded in, and locally grade into, granite gneisses or augengneisses and mylonites. In this study, the quartz microfabrics of the undeformed granites are compared against the augengneisses and mylonites in a representative number of samples from several locations. In the undeformed granites, the fine‐grained quartz aggregates that formed from coesite upon decompression are characterized by a foam structure and random crystallographic orientation. In the deformed granites, the quartz microstructures and the crystallographic preferred orientation (CPO) indicate deformation by dislocation creep. Most of the deformation of the granites (if not all) must have happened at a late stage during exhumation, after transformation of coesite to quartz, at greenschist facies conditions in the middle crust. The deformed granites provide no evidence of deformation during subduction, at (U)HP metamorphic conditions, and in the earlier stages of exhumation. The diameter of internally undeformed slices of continental crust subducted to and exhumed from about 100 km can exceed that of the presently exposed Brossasco granite, i.e. it can be on the kilometre scale.
Grenvillian‐aged orogenesis in the Palaeoproterozoic Gascoyne Complex, Western Australia: 1030–950 Ma reworking of the Proterozoic Capricorn Orogen
Authors: SHEPPARD S. , RASMUSSEN B. , MUHLING J. R. , FARRELL T. R. , FLETCHER I. R.
Published: April 2007

In situ SHRIMP U–Pb geochronology of monazite and xenotime in pelitic schists from the central Gascoyne Complex, Western Australia, shows that greenschist to amphibolite facies metamorphism occurred between c. 1030 and c. 990 Ma. Monazite from an undeformed rare‐element pegmatite from the same belt gives a 207Pb/206Pb age of c. 950 Ma, suggesting that peak metamorphism and deformation was followed by pegmatite intrusion and coeval granite magmatism. Metamorphism in the central Gascoyne Complex was previously interpreted as Barrovian, largely based on the identification of kyanite in peak metamorphic assemblages, and has been attributed to intense crustal shortening and substantial tectonic thickening during Palaeoproterozoic continent–continent collision. However, the stable Al2SiO5 polymorph has been identified in this study as andalusite rather than kyanite, and the prograde assemblages of staurolite–garnet–andalusite–biotite–muscovite–quartz indicate temperatures of 500–550 °C and pressures of 3–4 kbar. These data show that the Palaeoproterozoic Gascoyne Complex underwent an episode of Grenvillian‐aged intracontinental reworking concentrated in a NW–SE striking corridor, during the Edmundian Orogeny. Until now, the Edmundian Orogeny was thought to have involved only reactivation of structures in the Gascoyne Complex, along with deformation and very low‐ to low‐grade metamorphism of Mesoproterozoic cover rocks some time between 1070 and 755 Ma. However, we suggest that it involved regional amphibolite facies metamorphism and deformation, granite magmatism and pegmatite intrusion between c. 1030 and c. 950 Ma. Therefore, the Capricorn Orogen experienced a major phase of tectonic reworking c. 600 Myr later than previously recognized. Our results emphasize the importance of in situ geochronology integrated with petrological studies in order to link the metamorphic history of a terrane with causally related tectonic events.
Growth and Major Nutrient Concentrations in Brassica campestris Supplied with Different NH4+/NO3− Ratios
Authors: Zhang Fu‐Cang , Kang Shao‐Zhong , Li Fu‐Sheng , Zhang Jian‐Hua
Published: April 2007

In the present study, we investigated whether growth and main nutrient ion concentrations of cabbage (Brassica campestris L.) could be increased when plants were subjected to different NH4+/NO3− ratios. Cabbage seedlings were grown in a greenhouse in nutrient solutions with five NH4+/NO3− ratios (1:0; 0.75:0.25; 0.5:0.5; 0.25:0.75; and 0:1). The results showed that cabbage growth was reduced by 87% when the proportion of NH4+‐N in the nutrient solution was more than 75% compared with a ratio NH4+/NO3− of 0.5:0.5 35 d after transplanting, suggesting a possible toxicity due to the accumulation of a large amount of free ammonia in the leaves. When the NH4+/NO3− ratio was 0.5:0.5, fresh seedling weight, root length, and H2PO4− (P), K+, Ca2+, and Mg2+ concentrations were all higher than those in plants grown under other NH4+/NO3− ratios. The nitrate concentration in the leaves was the lowest in plants grown at 0.5: 0.5 NH4+/NO3−. The present results indicate that an appropriate NH4+/NO3− ratio improves the absorption of other nutrients and maintains a suitable proportion of N assimilation and storage that should benefit plant growth and the quality of cabbage as a vegetable.
Sap Flow of Populus euphratica in a Desert Riparian Forest in an Extreme Arid Region During the Growing Season
Authors: Si Jian‐Hua , Feng Qi , Zhang Xiao‐You , Chang Zong‐Qiang , Su Yong‐Hong , Xi Hai‐Yang
Published: April 2007

In the present study, the heat pulse technique was applied to investigate the stem sap flow of Populus euphratica in a desert riparian forest in an extreme arid region from April to October 2003 and from May to October 2004. The experimental sites were in Qidaoqiao (101°10′ E, 41°59′ N) and Bayantaolai farm (101°14′ E, 42°01′ N) in Ejina county, in the low reaches of the Heihe River, China. The results indicated that the diurnal change in the velocity of sap flow showed minor fluctuations. At night, the rising of sap flow could be observed in the main tree species because of root pressure. During the growing season, the maximum average velocity was observed in July, followed by August, and the same velocity was observed in September and May; the minimum velocity was observed in October. The transpiration from June to August during the growing season accounted for approximately 70% of the annual total transpiration. The sap flow velocity of P. euphratica trees of different ages could be arranged in the order: 15 yr > 25 yr > 50 yr. Sap flow velocity was closely related to changes in micrometeorological factors, with average sap flow velocity showing a significant linear correlation with net radiation, air temperature and relative humidity.
Studies on Temporal and Spatial Variations of Phytoplankton in Lake Chaohu
Authors: Deng Dao‐Gui , Xie Ping , Zhou Qiong , Yang Hua , Guo Long‐Gen
Published: April 2007

Temporal and spatial variations of the phytoplankton assemblage in Lake Chaohu, a large shallow eutrophic lake in China, were studied from September 2002 to August 2003. A total of 191 phytoplankton species was identified, among which Chlorophytes (101) ranked the first, followed by Cyanophytes (46) and Bacillariophytes (28). On average over the entire lake, the maximum total algal biomass appeared in June (19.70 mg/L) with a minimum (5.05 mg/ L) in November. In terms of annual mean biomass, cyanobacteria contributed 45.43% to total algal biomass, followed by Chlorophytes (27.14%), and Bacillariophytes (20.6%). When nitrate (NO3‐N) and ammonium (NH4‐N) concentrations dropped in spring, fixing‐nitrogen cyanobacterium (Anabaena) developed quickly and ranked the first in terms of biomass in summer. It is likely that dominance of zooplanktivorous fish and small crustacean zooplankton favored the development of the inedible filamentous or colony forming cyanobacteria. The persistent dominance of cyanobacteria throughout all seasons may indicate a new tendency of the response of phytoplankton to eutrophication in Lake Chaohu.
Leaflet Movement of Robinia pseudoacacia in Response to a Changing Light Environment
Authors: Liu Cheng‐Cheng , Welham Clive V. J. , Zhang Xian‐Qiang , Wang Ren‐Qing
Published: April 2007

Diurnal and nocturnal leaflet movement of black locust (Robinia pseudoacacia L.) was investigated under three light schemes: 100% natural irradiance, 50% shading, and 90% shading. Changes in leaf mid‐vein angle were described by measurements of two planes: (i) β, the angle formed by the bottom of the petiolule and its relation to the horizontal plane; and (ii) θ, the angle between the petiolule and the main leaflet vein. The two highest light regimens had a significant effect on β. Variation in β tends to make the leaflet more erect, thereby minimizing any negative impact of high irradiance on leaf lamina. Light‐dark rhythms induced variation in θ (termed nyctinastic movement). Nyctinastic movement is important during the low light levels experienced by leaflets in early morning and late afternoon. At low light levels, the leaflet stopped nyctinastic movement and θ was fixed at an angle that may have enabled the leaf lamina to maximize light interception. After the light‐dark cycle was reestablished, nyctinastic movement was restored. Taken together, our results suggest that irradiance induces variation in β leading to diurnal leaflet movement (diaheliotropism), whereas the light‐dark cycle influences θ, which results in nocturnal leaflet movement. Both angles are important for describing patterns of leaf movement in R. pseudocacia.
Prasinoxanthin‐constaining Prasinophyceae Discovered in Jiaozhou Bay, China
Authors: Yu Zhi‐Gang , Deng Chun‐Mei , Yao Peng , Zhen Yu , Qian Shu‐Ben
Published: April 2007

The class Prasinophyceae (Chlorophyta) contains some photosynthetic eukaryotic ultraplankton species characterized by containing prasinoxanthin. The existence and abundance of these organisms can be estimated by the diagnostic pigment. We detected the unique pigments of prasinoxanthin‐containing Prasinophyceae in Jiaozhou Bay, China using high performance liquid chromatography (HPLC). This was the first finding of this kind in Chinese seas. Using the ratio of prasinoxanthin to chlorophyll a, the abundance of prasinoxanthin‐containing Prasinophyceae has been calculated. The average contribution of prasinoxanthin‐containing Prasinophyceae to the chlorophyll a pool was 8.5% and 17.0% in May and August 2004 in Jiaozhou Bay, and the maximums were 25.9% and 36.3%. Size fractionated pigment analysis suggested that more than 80% of prasinoxanthin were in the fraction of 2‐20 μm. According to the results of pigment and morphological analysis, the possible genera of prasinoxanthin‐containing Prasinophyceae and the reasons for causing this high abundant phytoplankton in Jiaozhou Bay were discussed. This kind of phytoplankton can not be discovered in traditional biological investigation, but its contribution to the coastal ecosystem is significant enough to be studied further.
Endopeptidase Isoenzyme Characteristics in Cucumis sativus Leaves During Dark‐induced Senescence
Authors: Zhang Peng , Wang Fei , Zhang Lie‐Feng , Rui Qi , Xu Lang‐Lai
Published: April 2007

The changes and characteristics of endopeptidase (EP) isoenzymes in cucumber (Cucumis sativus L.) leaves during dark‐induced senescence were investigated by activity staining after gradient‐polyacrylamide gel electrophoresis (G‐PAGE) containing co‐polymerized gelatin as substrate. The results showed that both the chlorophyll and the protein contents of leaves were decreased, and the protein degradation was correlated with the increase of proteolytic activity during the course of leaf senescence. Meanwhile, nine cucumber endopeptidases isoenzymes (CEP) with 140, 120, 106, 94, 76, 55, 46, 39 and 35 kDa molecular weights were detected. Four of these, CEP2, 3, 4 and CEP9 appeared all the time, but the changes of the activity were different during incubation. Another four CEPs (CEP5, 6, 7 and CEP8) whose activities increased with dark‐induced time were only detected in senescent leaves. Furthermore, the biochemical properties of these nine CEP were also characterized. All the CEPs had high activities from 35 °C to 45 °C, and the optimum temperature was found to be 40 °C. However, the activities of CEPs were not detected below 25 °C or over 60 °C. The activity bands appeared at a wide range of pH from 5.0 to 9.0, but the optimum pH was found at 7.0. No CEPs were detected at pH 4 or pH 10. By inhibition analysis we concluded that CEP2, 3, 4 and CEP9 were serine endopeptidases and CEP6 was a kind of cysteine protease. It is suggested that serine endopeptidases might play a major role in cucumber leaf senescence, and for the first time, six senescence‐related endopeptidases (CEP1, 5, 6, 7, 8 and 9) were found in cucumber leaves.
Novel Evidence for a Reversible Dissociation of Light‐harvesting Complex II from Photosystem II Reaction Center Complex Induced by Saturating Light Illumination in Soybean Leaves
Authors: Liao Yi , Xu Da‐Quan
Published: April 2007

After saturating light illumination for 3 h the potential photochemical efficiency of photosystem II (PSII) (Fv/Fm, the ratio of variable to maximal fluorescence) decreased markedly and recovered basically to the level before saturating light illumination after dark recovery for 3 h in both soybean and wheat leaves, indicating that the decline in Fv/Fm is a reversible down‐regulation. Also, the saturating light illumination led to significant decreases in the low temperature (77 K) chlorophyll fluorescence parameters F685 (chlorophyll a fluorescence peaked at 685 nm) and F685/F735 (F735, chlorophyll a fluorescence peaked at 735 nm) in soybean leaves but not in wheat leaves. Moreover, trypsin (a protease) treatment resulted in a remarkable decrease in the amounts of PsbS protein (a nuclear gene psbS‐encoded 22 kDa protein) in the thylakoids from saturating light‐illuminated (SI), but not in those from dark‐adapted (DT) and dark‐recovered (DRT) soybean leaves. However, the treatment did not cause such a decrease in amounts of the PsbS protein in the thylakoids from saturating light‐illuminated wheat leaves. These results support the conclusion that saturating light illumination induces a reversible dissociation of some light‐harvesting complex II (LHCII) from PSII reaction center complex in soybean leaf but not in wheat leaf.
Effects of Local Nitrogen Supply on Water Uptake of Bean Plants in a Split Root System
Authors: Guo Shiwei , Shen Qirong , Brueck Holger
Published: April 2007

To study the effects of local nitrogen supply on water and nutrient absorption, French bean (Phaseolus vulgaris L.) plants were grown in a split root system. Five treatments supplied with different nitrogen forms were compared: homogeneous nitrate (NN) and homogenous ammonium (AA) supply, spatially separated supply of nitrate and ammonium (NA), half of the root system supplied with N‐free nutrient solution, the other half with either nitrate (N0) or ammonium (A0). The results showed that 10 d after onset of treatments, root dry matter (DM) in the nitrate‐supplied vessels treated with NA was more than two times higher than that in the ammonium‐supplied vessels. Water uptake from the nitrate‐supplied vessels treated with NA was 281% higher than under ammonium supply. In treatments N0 and A0, the local supply of N resulted in clearly higher root DM, and water uptake from the nitrate‐supplied vessels was 82% higher than in the ‐N vessels. However, in A0 plants, water uptake from the ‐N nutrient solution was 129% higher than from the ammonium‐supplied vessels. This indicates a compensatory effect, which resulted in almost identical rates of total water uptake of treatments AA and A0, which had comparable shoot DM and leaf area. Ammonium supply reduced potassium and magnesium absorption. Water uptake was positively correlated with N, Mg and K uptake.
High‐throughput Binary Vectors for Plant Gene Function Analysis
Authors: Lei Zhi‐Yong , Zhao Ping , Cao Min‐Jie , Cui Rong , Chen Xi , Xiong Li‐Zhong , Zhang Qi‐Fa , Oliver David J. , Xiang Cheng‐Bin
Published: April 2007

A series of high‐throughput binary cloning vectors were constructed to facilitate gene function analysis in higher plants. This vector series consists of plasmids designed for plant expression, promoter analysis, gene silencing, and green fluorescent protein fusions for protein localization. These vectors provide for high‐throughput and efficient cloning utilizing sites for λ phage integrase/excisionase. In addition, unique restriction sites are incorporated in a multiple cloning site and enable promoter replacement. The entire vector series are available with complete sequence information and detailed annotations and are freely distributed to the scientific community for non‐commercial uses.
Salt Stress‐induced Programmed Cell Death in Rice Root Tip Cells
Authors: Li Jian‐You , Jiang Ai‐Liang , Zhang Wei
Published: April 2007

Salt stressed rice root tips were used to investigate the changes of reactive oxygen species (ROS) and antioxidant enzymes at the early stages of programmed cell death (PCD). The results indicated that 500 mmol/L NaCl treatment could lead to specific features of PCD in root tips, such as DNA ladder, nuclear condense and deformation, and transferase mediated dUTP nick end labeling positive reaction, which were initiated at 4 h of treatment and progressed thereafter. Cytochrome c release from mitochondria into cytoplasm was also observed, which occurred at 2 h and was earlier than the above nuclear events. In the very early phase of PCD, an immediate burst in hydrogen peroxide and superoxide anion production rate was accompanied by two‐phase changes of superoxide dismutases and ascorbate peroxidase. A short period of increase in the activity was followed by prolonged impairment. Thus, we conclude that salt can induce PCD in rice root tip cells, and propose that in the early phase of rice root tip cell PCD, salt stress‐induced oxidative burst increased the antioxidant enzyme activity, which, in turn, scavenged the ROS and abrogated PCD. Also, when the stress is prolonged, the antioxidant system is damaged and accumulated ROS induces the PCD process, which leads to cytochrome c release and nuclear change.
Interdependence
Authors: Smith Joe , Clark Nigel , Yusoff Kathryn
Published: April 2007

How should we respond to the increasingly dense bundle of economic, cultural and ecological interconnections that span the globe and stretch into the future? What kinds of ethical and public engagements are demanded of researchers who work on global environmental, economic and social issues? The term interdependence may provide a powerful framework for advancing thinking and debate both within academia and among wider publics in relation to these questions. Members of the Open University's Geography Department have been working with partners to build the Interdependence Day project. The project combines research, cultural work, communications and public participation in an attempt to make sense of our responsibilities to people distant in space and time, and to the nonhuman natural world. This article reviews nearly a century of deployments of the term interdependence in political and academic writing, introduces the distinctive work that might be done with the term in the critical social sciences, and outlines the Interdependence Day project.
Memoryscape: How Audio Walks Can Deepen Our Sense of Place by Integrating Art, Oral History and Cultural Geography
Authors: Butler Toby
Published: April 2007

This article is concerned with the history and practice of creating sound walks or ‘memoryscapes’: outdoor trails that use recorded sound and spoken memory played on a personal stereo or mobile media to experience places in new ways. In this relatively new and rapidly evolving field, the author brings together works from music, sound art, oral history and cultural geography as a starting point to understanding how such trails can give us a more sophisticated and nuanced experience of places. He suggests that this might offer some exciting opportunities for practice‐based multimedia research and teaching.
China and Africa: Emerging Challenges to the Geographies of Power
Authors: Mawdsley Emma
Published: April 2007

Over the last few years, China has assiduously pursued stronger economic and diplomatic relations with many Asian, African and Latin American countries. In part, this is fuelled by its extraordinary economic growth, which has led to a boom in domestic resource demand, and the search for profitable markets and investment outlets. China is also seeking diplomatic support in challenging the inequalities of ‘global’ governance. For better and worse, China's rise will lead to changes in the present structures and loci of power in an uneven world. This review article examines one set of China's ‘South–South’ interactions through an historical account of Sino–African relations from 1949 to the present day. It points to the complexity of interactions between diverse Chinese and African actors, a range of opportunities and problems, and the dangers of a defensive response from the West, if based on unreflexive and unsophisticated foreign policy analysis.
The Decline of Inner Suburbs: The New Suburban Gothic in the United States
Authors: Short John Rennie , Hanlon Bernadette , Vicino Thomas J.
Published: April 2007

In this article, we critically examine transformation and decline in US suburbs. We identify four distinct, chronological phases of development: suburban utopias, suburban conformity, suburban diversity, and suburban dichotomy. An element of this new suburban dichotomy is what we term suburban gothic. We theorize that the forces of an aging housing stock, land‐use planning, and deindustrialization contribute to the divergent realities of US suburbs.
Business Improvement Districts: Policy Origins, Mobile Policies and Urban Liveability
Authors: Ward Kevin
Published: April 2007

This article reviews the trans‐nationalisation of Business Improvement Districts. It outlines the geographical and ideological origins of this much‐heralded approach to downtown governance, and the means through which it has found itself in such diverse settings as Cape Town in South Africa, Kruševac in Serbia and Liverpool in the UK. Analysing the emergence of Business Improvement Districts in terms of the external edges of the state and its internal architecture, on the one hand, and, on the other, in the context of discussions around urban liveability, this article reviews work across geography, planning, political science and sociology. It concludes by arguing that Business Improvement Districts are both interesting in their own right, for what they reveal about contemporary trans‐national trends in urban governance, and for what they what they have to say about wider processes of neoliberal urbanisation.
A block slipping on a sphere with friction: Exact and perturbative solutions
Authors: Prior Tom , Mele E. J.
Published: April 2007

A well studied problem in elementary mechanics is the location of the release point of a particle that slides on the surface of a frictionless sphere when it is released from rest at the top. We generalize this problem to include the effects of sliding friction and solve it by a perturbation expansion in the coefficient of sliding friction and by an exact integration of the equation of motion. A comparison of the two solutions identifies a parameter range where the perturbation series accurately represents the motion of the particle and another range where the perturbative solution fails qualitatively to describe the motion of the particle.
Inertial forces, absolute space, and Mach’s principle: The genesis of relativity
Authors: Newburgh Ronald
Published: April 2007

The cornerstone of Newtonian mechanics is the inertial frame of reference. With this frame we can understand the difference between real and fictitious or pseudo forces and the importance of these two types of forces in Newton’s analysis of his rotating bucket. This analysis was the basis of his belief in absolute space. Mach, who believed strongly in an empiricist view of science, showed that the existence of inertial forces leads to a refutation of absolute space. He replaced absolute space with a frame of reference at rest with respect to the distant fixed stars considered as a rigid system. His principle, which was not expressed explicitly by him, is that the inertia of a body is a consequence of its interaction with all other bodies in the universe. Mach’s refutation of absolute space made Einstein’s general theory of relativity possible. Einstein later abandoned Mach’s principle and found the source of inertia in the nonzero curvature of the space-time metric, a fact that does not diminish the importance of Mach in Einstein’s early thinking.
Altitude measurement for model rocketry
Authors: Caughey David A.
Published: April 2007

The simple, ballistic time-of-flight equation for the maximum altitude of a vertically launched rocket neglects the effects of atmospheric drag. We show that the error introduced by using this equation to estimate the maximum altitude is typically less than 1% because of the effective cancellations of timing errors during the ascent and descent of the rocket.
Conductive Critical Thinking
Authors: Paetkau Mark
Published: April 2007

One of my goals as an instructor is to teach students critical thinking skills. This paper presents an example of a student-led discussion of heat conduction at the first-year level. Heat loss from a human head is calculated using conduction and radiation models. The results of these plausible (but wrong) models of heat transfer contradict what they know from experience (and from what their mothers have told them). What better way to elicit discussion?
Gender in the Physics Classroom
Authors: McCullough Laura
Published: April 2007

Column Editor's note: Laura McCullough teaches physics at the University of Wisconsin—Stout. She has a Ph.D. in science education and conducts physics education research on gender issues in physics. I was impressed with her passion for this issue when I heard her speak at an AAPT session several years ago, and I think you will agree that the insights she shares here can help all of us to ensure equity for all students we teach.
Mycobacterium aviumin the Postgenomic Era
Authors: Turenne Christine Y. , Wallace Richard , Behr Marcel A.
Published: April 2007

The past several years have witnessed an upsurge of genomic data pertaining to theMycobacterium aviumcomplex (MAC). Despite clear advances, problems with the detection of MAC persist, spanning the tests that can be used, samples required for their validation, and the use of appropriate nomenclature. Additionally, the amount of genomic variability documented to date greatly outstrips the functional understanding of epidemiologically different subsets of the organism. In this review, we discuss how postgenomic insights into the MAC have helped to clarify the relationships between MAC organisms, highlighting the distinction between environmental and pathogenic subsets ofM. avium. We discuss the availability of various genetic targets for accurate classification of organisms and how these results provide a framework for future studies of MAC variability. The results of postgenomicM. aviumstudy provide optimism that a functional understanding of these organisms will soon emerge, with genomically defined subsets that are epidemiologically distinct and possess different survival mechanisms for their various niches. Although the status quo has largely been to study differentM. aviumsubsets in isolation, it is expected that attention to the similarities and differences betweenM. aviumorganisms will provide greater insight into their fundamental differences, including their propensity to cause disease.