bluuebunny/crossref_metadata_2025 huggingface dataset:
Richards Plant Growth Model
Authors: Gregorczyk A.
Published: April 2008

In this paper, the Richards function in the form y(t) = A(I +be−kt)1/(1‐m) was used to precisely analyze plant growth. The first, second and third derivative formulae of the above function were given. A new parameter, G12= f(m) was derived, enabling the calculation of the coordinates of critical points which mark the principal growth phases. The coefficients of Richards model describing the dry matter accumulation in buckwheat plants were numerically calculated. The growth curve, growth rate curve and the growth acceleration curve were also drawn, A high usefulness of approximation of the growth process of buckwheat plants by means of Richards function was confirmed statistically.
Characterization of a Novel RING Finger Gene OsRFP1, which is Induced by Ethylene, Salicylic Acid and Blast Fungus Infection in Rice
Authors: Zhou Shanyue , Zhao Wensheng , Li Hui , Guo Zejian , Peng You‐Liang
Published: April 2008

OsRFP1, a C3H2C3‐type zinc finger gene, was isolated through screening a blast‐induced rice cDNA library. The full‐length cDNA of the OsRFP1 gene is 1393 bp with an open reading frame (ORF) encoding 302 amino acid residues. The deduced amino acid sequence of OsRFP1 contains an N‐terminal Pfam:zf‐CHY domain and a C‐terminal C3H2C3‐type RING signature. OsRFP1 was found localizing in the nucleus based on the fluorescence emitted by OsRFP1‐GFP fusion protein expressed in onion epidermal cells. GAL4 DNA‐binding vector pBD‐containing OsRFP1 could activate expression of the reporter genes of His/Ade/LacZ in yeast strain AH109 indicating that OsRFP1 has the transcriptional activation activity. RNA blot analysis showed that expression of the OsRFP1 gene was significantly induced by ethylene (ET), salicylic acid (SA) and blast fungus infection. Together, these results indicate that the OsRFP1 may function as a transcriptional regulator in ET‐dependent signal pathway in plant defense.
THE EPITHELIAL BRUSH BORDER Na+/H+ EXCHANGER NHE3 ASSOCIATES WITH THE ACTIN CYTOSKELETON BY BINDING TO EZRIN DIRECTLY AND VIA PDZ DOMAIN‐CONTAINING Na+/H+ EXCHANGER REGULATORY FACTOR (NHERF) PROTEINS
Authors: Cha Boyoung , Donowitz Mark
Published: April 2008

The Na+/H+ exchanger NHE3 associates with the actin cytoskeleton by binding ezrin both directly and indirectly. Both types of interaction are necessary for acute regulation of NHE3. Most acute regulation of NHE3 occurs by changes in trafficking via effects on exocytosis and/or endocytosis. However, NHE3 activity can also be regulated without changing the surface expression of NHE3 (change in turnover number).

A positive amino acid cluster in the a‐helical juxtamembrane region in the COOH‐terminus of NHE3 (amino acids K516, R520 and R527) is necessary for binding to the protein 4.1, ezrin, radixin, moesin (FERM) domain III of ezrin. Direct binding of NHE3 to ezrin is necessary for many aspects of basal trafficking, including basal exocytosis, delivery from the synthetic pathway and movement of NHE3 in the brush border (BB), which probably contributes to endocytosis over a prolonged period of time.

In addition, NHE3 binds indirectly to ezrin. The PDZ domain‐containing proteins Na+/H+ exchanger regulatory factor (NHERF) 1 and NHERF2, as intermediates in linking NHE3 to ezrin, are necessary for many aspects of NHE3 regulation. The binding of NHERF–ezrin/radixin/moesin to NHE3 occurs in the cytosolic domain of NHE3 between amino acids 475 and 689. This NHERF binding is involved in the formation of the NHE3 complex and restricts NHE3 mobility in the BB. However, it is dynamic; for example, changing in some cases of signalling. Furthermore, NHERF binding is necessary for lysophosphatidic acid stimulation of NHE3 and inhibition of NHE3 by Ca2+, cAMP and cGMP.
INDICATORS OF DEHYDRATION AND HAEMOCONCENTRATION ARE ASSOCIATED WITH THE PREVALENCE AND SEVERITY OF CORONARY ARTERY DISEASE
Authors: Rasouli Mehdi , Kiasari Asadollah Mohseni , Arab Shahin
Published: April 2008

The vascular endothelium is injured by blood flow abnormalities exacerbated by different risk factors, including markers of haemoconcentration. The aim of the present study was to assess the association between markers of haemoconcentration and dehydration and the prevalence and severity of coronary artery disease (CAD).

Subjects in the present study (189 men and 126 women) were classified as either CAD cases or controls according to the results of coronary angiography. The severity of CAD was scored on the basis of the number and the extent of lesions on coronary arteries. Serum electrolytes, osmolality and haematological parameters were measured.

Compared with control subjects, patient with CAD had increased levels of serum osmolality, calculated osmolality, tonicity, sodium, glucose and blood urea nitrogen (BUN). Significant differences were also observed in the haematocrit and haemoglobin concentration, but not in erythrocyte counts and total serum protein. On multiple logistic regression analysis adjusting for major risk factors, serum osmolality, glucose and BUN exhibited significant associations with CAD, but the correlations were lessened by diabetes. Analysis using anova showed a significant correlation between serum osmolality, sodium, glucose and BUN and the severity of CAD. The area under the receiver operating characteristic curves, as a relative measure of the test's efficiency, was the highest and significant for serum osmolality, BUN and glucose.

The results indicate that some of the markers of dehydration and haemoconcentration are associated significantly with the prevalence and severity of CAD, but the independence of these correlations is questioned. These markers may play a role in the pathogenesis of atherosclerosis.
HYPERHOMOCYSTEINAEMIA‐INDUCED CARDIOVASCULAR CHANGES IN RATS
Authors: Resstel Leonardo BM , De Andrade Claudia R , Haddad Renato , Eberlin Marcos N , De Oliveira Ana M , Corrêa Fernando MA
Published: April 2008

Increased plasma homocysteine content and increased blood pressure are independently associated with higher cardiovascular risks. The present study was designed to determine the effects of hyperhomocysteinaemia (HHcys) on the activity of the cardiovascular system in rats.

Using male Wistar rats, the effect of moderate HHcys, induced by treating rats with dl‐homocysteine thiolactone (DL‐HT; 1 g/kg per day) for 15 days, on arterial blood pressure, heart rate, baroreflex and vascular reactivity was determined.

Hyperhomocysteinaemia was observed after 15 days of treatment. Baseline arterial blood pressure and heart rate values of HHcys animals were significantly increased after 15 days of treatment. Plasma homocysteine and cardiovascular parameters returned to control values after termination of treatment. Baroreflex gain was significantly enhanced in HHcys rats. The pressor effect of an i.v. infusion of phenylephrine (50 mg/kg per mL) was decreased in HHcys rats and returned to control values after washout of DL‐HT. Hypotensive responses to i.v. infusions of sodium nitroprusside (70 mg/kg per mL) or acetylcholine (10 mg/kg per mL) were increased in HHcys animals and returned to control values after washout of DL‐HT. The increase in resting arterial blood pressure associated with the moderate HHcys was reversed by treatment with the b1‐adrenoceptor antagonist atenolol, suggesting that HHcys‐related hypertension is related to increase in cardiac sympathetic activity.

The present study showed significantly increased arterial blood pressure, heart rate and baroreflex activity in the early phase of moderate HHcys. In addition, HHcys was associated with alterations of vascular responsiveness to pressor and depressor agents, as well as increased cardiac sympathetic activity. The fact that cardiovascular changes observed in HHcys were reversed after DL‐HT washout indicate that moderate HHcys evokes cardiovascular changes.
INTRAPERITONEAL GLYCEROL INDUCES OXIDATIVE STRESS IN RAT KIDNEY
Authors: Rieger Elenara , Rech Virginia C , Feksa Luciane R , Wannmacher Clovis MD
Published: April 2008

Glycerol has been used for the treatment of intracranial hypertension, cerebral oedema and glaucoma. Experimentally, intramuscular administration of hypertonic glycerol solution is used to produce acute renal failure. In this model, glycerol causes rhabdomyolysis and myoglobinuria, resulting in the development of renal injury. The pathogenesis is thought to involve vascular congestion, the formation of casts and oxidative stress. However, the effect of glycerol itself independent of rhabdomyolysis has not been investigated. Therefore, the aim of the present study was to investigate the effects of i.p. glycerol on some biochemical and oxidative stress parameters in the kidney of young rats.

Rats received 10 mL/kg, i.p., hypertonic glycerol solution (50% v/v) or saline (NaCl 0.85 g%) followed by 24 h water deprivation. Twenty‐four hours after the administration of glycerol, rats were killed. Creatinine levels and the activity of creatine kinase (CK) and lactate dehydrogenase (LDH) were determined in the plasma. In addition, CK, pyruvate kinase and LDH activity and oxidative stress parameters (free radical formation, lipid peroxidation and protein carbonylation) were measured in renal tissue.

Glycerol did not alter plasma CK activity and increased plasma creatinine levels, suggesting renal insufficiency and the absence of rhabdomyolysis. Renal CK and pyruvate kinase activity was decreased, suggesting diminution of energy homeostasis in the kidney. Plasma and renal LDH activity was decreased, whereas the formation of free radicals, lipid peroxidation and protein carbonylation were increased, suggesting oxidative stress.

These results are similar to those described after the intramuscular administration of glycerol. Therefore, it is possible that glycerol may provoke renal lesions by mechanisms other than those induced by rhabdomyolysis.
TISSUE‐ AND FIBRE‐SPECIFIC MODIFICATIONS OF INSULIN‐SIGNALLING MOLECULES IN CARDIAC AND SKELETAL MUSCLE OF DIABETIC RATS
Authors: Ekladous Demiana , Mehdi Mohamad Z , Costa Myriam , Srivastava Ashok K , Chiasson Jean‐Louis , Coderre Lise
Published: April 2008

Levels of insulin‐signalling molecules are altered in streptozotocin (STZ)‐induced diabetes, a model of Type 1 diabetes. However, the tissue‐specific regulation of these changes and the effect of insulin supplementation on signalling molecule protein levels have not been well characterized.

In the present study, we evaluated the level of proximal insulin‐signalling intermediates in the heart and in red and white gastrocnemius muscles of 2 week diabetic rats and diabetic rats supplemented with insulin.

Diabetes augmented levels of the insulin receptor and the p85 regulatory subunit of phosphatidylinositol 3‐kinase in the red gastrocnemius, but not in the white gastrocnemius or the heart. Furthermore, diabetes reduced insulin receptor substrate‐1 levels in both the red and white gastrocnemius, but not in the heart. Examination of the levels and basal activities of distal insulin‐signalling intermediates (protein kinase B (PKB)/Akt, extracellular signal‐regulated kinase (ERK) 1/2, p38 mitogen‐activated protein kinase (MAPK)) also failed to reveal a specific pattern in these changes. Thus, diabetes reduced basal ERK1/2 and PKB/Akt phosphorylation in the heart and white gastrocnemius, respectively, whereas it augmented basal p38 MAPK activity in the red gastrocnemius. Insulin supplementation normalized the levels and activities of some but not all proteins.

In conclusion, the results of the present study demonstrate that adaptation to STZ‐induced diabetes varies among skeletal muscle fibre types and the heart, emphasizing the complex tissue‐specific responses to diabetes.
A COMPARISON OF THE PHARMACOLOGICAL PROPERTIES OF RECOMBINANT HUMAN AND RAT α1β2γ2L GABAA RECEPTORS IN XENOPUS OOCYTES
Authors: Rahman Mozibur , Borra Vijaya B , Isaksson Monica , Johansson Inga‐Maj , Ragagnin Gianna , Bäckström Torbjörn , Wang Ming‐De
Published: April 2008

In the present study, we compared the pharmacology, particularly neurosteroid modulation of the GABAA receptor, between human and rat a1b2g2L GABAA receptors and between human receptors containing the long (L) and short (S) forms of the g2‐subunit.

We observed that maximum responses to GABA were significantly higher with the human a1b2g2L receptor compared with the rat receptor. In terms of neurosteroid modulation, increases in the EC15 response to GABA induced by 3a‐OH‐5b‐pregnan‐20‐one (3a5bP), 5a‐androstane‐3a,17b‐diol (3a5aADL) and 5a‐pregnane‐3a,20b‐diol (3a5a‐diol) were significantly greater for the rat compared with the human receptor. Responses to 30 mmol/L GABA were inhibited by 3b‐OH‐5a‐pregnan‐20‐one (UC1010) and 5b‐pregnan‐3b,20(R)‐diol (UC1020) to a greater degree for human and rat receptors, respectively. Responses to GABA + 3a5aTHDOC were inhibited by 5a‐pregnan‐3b,20(S)‐diol (UC1019) and pregnenolone sulphate to a greater degree for human and rat receptors, respectively.

The GABA dose–response curves for human a1b2g2S and a1b2g2L receptors were identical. However, the maximum GABA‐evoked current, the direct gating effect of pentobarbital and the allosteric potentiation of the GABA EC15 response by 3a5aTHDOC and 3a5bP were significantly higher with a1b2g2S than a1b2g2L receptors. Inhibition of the response to 30 mmol/L GABA by UC1010 and UC1020 was greater for a1b2g2L and a1b2g2S receptors, respectively. Inhibition of responses to 3a5aTHDOC + GABA by UC1019 and UC1010 was significantly higher for a1b2g2L receptors.

In conclusion, the site of activation by GABA and neurosteroid modulation differ between human and rat a1b2g2L receptors, as well as between human receptors containing the L and S splice variants of the g2‐subunit.
THE CGP7930 ANALOGUE 2,6‐DI‐TERT‐BUTYL‐4‐(3‐HYDROXY‐2‐SPIROPENTYLPROPYL)‐PHENOL (BSPP) POTENTIATES BACLOFEN ACTION AT GABAB AUTORECEPTORS
Authors: Parker David AS , Marino Victor , Ong Jennifer , Puspawati Ni Made , Prager Rolf H
Published: April 2008

The pharmacological actions of 2,6‐di‐tert‐butyl‐4‐(3‐hydroxy‐2‐spiropentylpropyl)‐phenol (BSPP), a putative presynaptic GABAB receptor modulator, were examined in electrically stimulated rat neocortical brain slices preloaded with [3H]‐GABA or [3H]‐glutamic acid.

At 10 mmol/L, BSPP inhibited the release of [3H]‐GABA in the presence of baclofen, but not that of [3H]‐glutamic acid. This effect was sensitive to the GABAB receptor antagonist (+)‐(S)‐5,5‐dimethylmorpholinyl‐2‐acetic acid (Sch 50911).

Alone, BSPP had no effect on the release of [3H]‐GABA or [3H]‐glutamic acid.

It is concluded that BSPP selectively potentiates the action of baclofen at GABAB autoreceptors, but not heteroreceptors and may be a useful ligand to discriminate between presynaptic GABAB receptor subtypes.
POST‐RESISTANCE EXERCISE HYPOTENSION IN SPONTANEOUSLY HYPERTENSIVE RATS IS MEDIATED BY NITRIC OXIDE
Authors: Lizardo JHF , Silveira EAA , Vassallo DV , Oliveira EM
Published: April 2008

Postexercise hypotension (PEH) plays an important role in the non‐pharmacological treatment of hypertension. It is characterized by a decrease in blood pressure (BP) after a single bout of exercise in relation to pre‐exercise levels.

The present study investigated the effect of a single session of resistance exercise, as well as the effect of nitric oxide (NO) and the autonomic nervous system (ANS), in PEH in spontaneously hypertensive rats (SHR).

Catheters were inserted into the left carotid artery and left jugular vein of male SHR (n = 37) for the purpose of measuring BP or heart rate (HR) and drug or vehicle administration, respectively. Haemodynamic measurements were made before and after acute resistance exercise. The roles of NO and the ANS were investigated by using NG‐nitro‐l‐arginine methyl ester (l‐NAME; 15 mg/kg, i.v.) and hexamethonium (20 mg/kg, i.v.) after a session of acute resistance exercise.

Acute resistance exercise promoted a pronounced reduction in systolic and diastolic BP (–37 ± 1 and –8 ± 1 mmHg, respectively; P < 0.05), which was suppressed after treatment with l‐NAME. The reduction in systolic BP caused by exercise (–37 ± 1 mmHg) was not altered by the administration of hexamethonium (–38 ± 2 mmHg; P > 0.05). After exercise, the decrease in diastolic BP was greater with hexamethonium (–26 ± 1 mmHg; P < 0.05) compared with the decrease caused by exercise alone.

The results suggest that acute resistance exercise has an important hypotensive effect on SHR and that NO plays a crucial role in this response.
The role of testosterone in the pathogenesis of prostate cancer
Authors: Imamoto Takashi , Suzuki Hiroyoshi , Yano Masashi , Kawamura Koji , Kamiya Naoto , Araki Kazuhiro , Komiya Akira , Nihei Naoki , Naya Yukio , Ichikawa Tomohiko
Published: April 2008

Abstract:  Relationships between androgenic hormones and prostatic tissue growth are complex. It is certainly true that the prostate will not develop without androgens and the gland will atrophy if androgen support is withdrawn. The hormonal hypothesis remains one of the most important hypotheses in the etiology of prostate cancer (PCa), and efforts are continuing to improve the understanding of androgen actions in PCa. Although evidence from epidemiological studies of associations between circulating levels of androgens and PCa risk has been inconsistent, the traditional view that higher testosterone (T) levels represent a risk factor for PCa appears to have little evidentiary support. Reinvestigation of the relationship between T and PCa seems important and necessary if a new, clinically and scientifically rewarding concept is to be constructed. The present review considers the metabolism and intraprostatic action of T, epidemiological evidence, and the association between T and PCa risk.
A local signature of LTP‐ and LTD‐like plasticity in human NREM sleep
Authors: Bergmann Til Ole , Mölle Matthias , Marshall Lisa , Kaya‐Yildiz Leval , Born Jan , Roman Siebner Hartwig
Published: April 2008

Paired associative stimulation (PAS) repeatedly pairs electrical nerve stimulation with transcranial magnetic stimulation of the contralateral motor hand area (M1HAND). Depending on the interstimulus interval, PAS can induce a long‐term potentiation (LTP)‐like facilitation or long‐term depression (LTD)‐like suppression of cortical excitability. In three experimental sessions, 12 awake men received PAS of the right median nerve and left M1HAND in the evening before sleep. To optimize the timing of paired stimulation in M1HAND, the interstimulus interval of PAS was adjusted to the individual N20‐latency of the somatosensory evoked potential to induce LTP‐like effects (PASN20+2ms), LTD‐like effects (PASN20−5ms), or no timing‐dependent after‐effects (PAScontrol). Motor‐evoked potentials (MEPs) showed high interindividual variations in the conditioning effects of PASN20+2ms and PASN20−5ms on cortical excitability. However, PAScontrol allowed us to adjust for any unspecific stimulation effects and the MEP increase after PASN20+2ms differed significantly from the MEP decrease after PASN20−5ms. PASN20+2ms and PASN20−5ms also had a differential effect on regional expression of slow waves and slow spindle activity during the first hour of subsequent non‐rapid eye movement (NREM) sleep. At the electrode sites overlying the conditioned M1HAND and the adjacent premotor cortex, local expression of slow spindle activity was significantly correlated with interindividual differences in the efficacy of PASN20+2ms and PASN20−5ms to potentiate or suppress cortical excitability. This correlation indicates that PAS shapes the local regulation of slow sleep spindles during subsequent NREM sleep.
Coincident pre‐ and postsynaptic activity downregulates NKCC1 to hyperpolarize ECl during development
Authors: Balena Trevor , Woodin Melanie A.
Published: April 2008

In the mature CNS, coincident pre‐ and postsynaptic activity decreases the strength of γ‐aminobutyric acid (GABA)A‐mediated inhibition through a Ca2+‐dependent decrease in the activity of the neuron‐specific K+‐Cl– cotransporter KCC2. In the present study we examined whether coincident pre‐ and postsynaptic activity can also modulate immature GABAergic synapses, where the Na+‐K+‐2Cl– (NKCC1) cotransporter maintains a relatively high level of intracellular chloride ([Cl–]i). Dual perforated patch‐clamp recordings were made from cultured hippocampal neurons prepared from embryonic Sprague–Dawley rats. These recordings were used to identify GABAergic synapses where the reversal potential for Cl– (ECl) was hyperpolarized with respect to the action potential threshold but depolarized with respect to the resting membrane potential. At these synapses, repetitive postsynaptic spiking within ± 5 ms of GABAergic synaptic transmission resulted in a hyperpolarizing shift of ECl by 10.03 ± 1.64 mV, increasing the strength of synaptic inhibition. Blocking the inward transport of Cl– by NKCC1 with bumetanide (10 µm) hyperpolarized ECl by 16.14 ± 4.8 mV, and prevented this coincident activity‐induced shift of ECl. The bumetanide‐induced hyperpolarization of ECl occluded furosemide, a K+‐Cl– cotransporter antagonist, from producing further shifts in ECl. Together, this indicates that brief coincident pre‐ and postsynaptic activity strengthens inhibition through a regulation of NKCC1. This study further demonstrates ionic plasticity as a mechanism underlying inhibitory synaptic plasticity.
Differential effects of pro‐BDNF on sensory neurons after sciatic nerve transection in neonatal rats
Authors: Fan Yong‐jun , Wu Linda Lin‐yan , Li Hong‐yun , Wang Yan‐Jiang , Zhou Xin‐Fu
Published: April 2008

Brain‐derived neurotrophic factor (BDNF) plays a critical role in the development of the central and peripheral nervous systems, and also in neuronal survival after injury. The actions of BDNF are mediated by its high‐affinity receptors TrkB and p75NTR. Recent studies have shown that proneurotrophins bind p75NTR and sortilin with high affinity, and trigger apoptosis of neurons in vitro. As proneurotrophins are a dominant form of gene products in developing and adult animals, it is imperative to understand their physiological functions in animals. Here, we showed differential roles of proBDNF in injured and uninjured sensory neurons. proBDNF, p75NTR and sortilin are highly expressed in dorsal root ganglia (DRG) neurons. Recombinant proBDNF induced a dose‐dependent death of PC12 cells and the death activity was completely abolished in the presence of antibodies against the prodomain of BDNF. The exogenous proBDNF enhanced the death of axotomized sensory neurons and the neutralizing antibodies to the prodomain or exogenous sortilin‐extracellular domain‐Fc fusion molecule reduced the death of axotomized sensory neurons. Interestingly, the treatment of neutralizing antibody in vivo increased the number of sensory neurons in the contralateral DRG. We conclude that proBDNF may induce the death of axotomized sensory neurons and suppress neuronal addition in the intact DRG in neonatal rats, and the suppression of endogenous proBDNF may protect neurons after neurotrauma.
Perioperative thromboprophylaxis in children: development of a guideline for management
Authors: JACKSON PHILIP C. , MORGAN JUDITH M.
Published: April 2008

Background:  Venous thromboembolic (VTE) events can occur in children at the time of surgery where a patient has associated prothrombotic risk factors. There is currently little advice available to anesthetists on how to assess the risks and provide prophylaxis.

Aim/Objective:  To increase awareness of thrombosis in the perioperative pediatric patient, and to give some guidance when considering prophylaxis in this group.

Method/Results:  A guideline outlining risk factors for venous thromboembolism in patients presenting for surgery was written as a flowchart. Recommendations for low risk patients was early mobilization and good hydration; for moderate risk patients having major general surgery to include physical prophylaxis where size permits, i.e. elastic stockings and compression devices; for high‐risk patients undergoing major orthopaedic or general surgery to also receive prophylactic low molecular weight heparin enoxaparin 0.5 mg·kg−1 b.d.

Conclusion:  Children with multiple risk factors for VTE should be considered for prophylactic measures when presenting for prolonged major surgery.
Wide genetic diversity of picoplanktonic green algae (Chloroplastida) in the Mediterranean Sea uncovered by a phylum‐biased PCR approach
Authors: Viprey Manon , Guillou Laure , Ferréol Martial , Vaulot Daniel
Published: April 2008

The genetic diversity of picoplanktonic (i.e. cells that can pass through a 3 μm pore‐size filter) green algae was investigated in the Mediterranean Sea in late summer by a culture‐independent approach. Genetic libraries of the 18S rRNA gene were constructed using two different primer sets. The first set is commonly used to amplify the majority of eukaryotic lineages, while the second was composed of a general eukaryotic forward primer and a reverse primer biased towards the phylum Chloroplastida. A total of 3980 partial environmental sequences were obtained: 1668 using the general eukaryotic primer set and 2312 using the Chloroplastida‐biased primer set. Of these sequences, 65 (4%) and 594 (26%) belonged to the Chloroplastida respectively. A 99.5% sequence similarity cut‐off value allowed classification of these 659 Chloroplastida sequences into 74 different operational taxonomic units. A majority of the Chloroplastida sequences (99%) belonged to the prasinophytes. In addition to the seven independent prasinophyte lineages previously described, we discovered two new clades (clades VIII and IX), as well as a significant genetic diversity at the species and subspecies levels, notably among the genera Crustomastix, Dolichomastix and Mamiella (Mamiellales), but also within Pyramimonas and Halosphaera (Pyramimonadales). Such diversity within prasinophytes has not previously been observed by cloning approaches, illustrating the power of using targeted primers for clone library construction. Prasinophyte assemblages differed especially in relation to nutrient levels. Micromonas and Ostreococcus were mainly recovered from mesotrophic areas, whereas Mamiella, Crustomastix and Dolichomastix were mostly detected in oligotrophic surface waters. Within genera such as Ostreococcus or Crustomastix for which several clades were observed, depth seemed to be the main factor controlling differential distribution of genotypes.
A novel, multi‐layered methanotrophic microbial mat system growing on the sediment of the Black Sea
Authors: Krüger Martin , Blumenberg Martin , Kasten Sabine , Wieland Andrea , Känel Layla , Klock Jan‐Hendrik , Michaelis Walter , Seifert Richard
Published: April 2008

A novel microbially diverse type of 1‐ to 5‐cm‐thick mat performing anaerobic oxidation of methane (AOM) and covering several square metres of the seafloor was discovered in the Black Sea at 180 m water depth. Contrary to other AOM‐mat systems of the Black Sea these floating mats are not associated to free gas and are not stabilized by authigenic carbonates. However, supply of methane is ensured by the horizontal orientation of the mats acting as a cover of methane enriched fluids ascending from the underlying sediments. Thorough investigation of their community composition by molecular microbiology and lipid biomarkers, metabolic activities and elemental composition showed that the mats provide a clearly structured system with extracellular polymeric substances (EPS) building the framework of the mats. The top black zone, showing high rates of AOM (15 μmol  gdw−1 day−1), was dominated by ANME‐2, while the following equally active pink layer was dominated by ANME‐1 Archaea. The lowest AOM activity (2 μmol  gdw−1 day−1) and cell numbers were found in the greyish middle part delimited towards the sediment by a second pink, ANME‐1‐dominated and sometimes a black outer layer (ANME‐2). Our work clearly shows that the different microbial populations are established along defined chemical gradients such as methane, sulfate or sulfide.
A pyrene‐degrading consortium from deep‐sea sediment of the West Pacific and its key member Cycloclasticus sp. P1
Authors: Wang Baojiang , Lai Qiliang , Cui Zhisong , Tan Tianfeng , Shao Zongze
Published: April 2008

A pyrene‐degrading bacterial consortium was obtained from deep‐sea sediments of the Pacific Ocean. The consortium degraded many kinds of polycyclic aromatic hydrocarbons (PAHs), including naphthalene, phenanthrene, pyrene, acenaphthene, fluorene, anthracene, fluoranthene, 2‐methylnaphthalene and 2,6‐dimethylnaphthalene, but it did not grow with chrysene and benzo[α]pyrene. With methods of plate cultivation and polymerase chain reaction–denaturing gradient gel electrophoresis (PCR‐DGGE), 72 bacteria belonging to 22 genera were detected from this consortium. Among the detected bacteria, the following genera frequently occurred: Flavobacterium, Cycloclasticus, Novosphingobium, Halomonas, Achromobacter, Roseovarius and Alcanivorax. The first two genera showed the strongest bands in denaturing gradient gel electrophoresis (DGGE) profiles and appeared in all PAH treatments. By now, only one isolate designated P1 was confirmed to be a pyrene degrader. It was identified to be Cycloclasticus spirillensus (100%). Although P1 can degrade pyrene independently, other bacteria, such as Novosphingobium sp. (Band 14), Halomonas sp. (Band 16) and an unidentified bacterium (Band 35), were involved in pyrene degradation in some way; they persist in the consortium in the test of dilution to extinction if only the consortium was motivated with pyrene. However, the secondary most important member Flavobacterium sp. evaded from the community at high dilutions. As a key member of the consortium, P1 distinguished itself by both cell morphology and carbon source range among the isolates of this genus. Based on intermediate analyses of pyrene degradation, P1 was supposed to take an upper pathway different from that previously reported. Together with the results of obtained genes from P1 homology with those responsible for naphthalene degradation, its degradation to pyrene is supposed to adopt another set of genes unique to presently detected. Summarily, an efficient pyrene‐degrading consortium was obtained from the Pacific Ocean sediment, in which Cycloclasticus bacterium played a key role. This is the first report to exploit the diversity of pyrene‐degrading bacteria in oceanic environments.
Distribution of aerobic anoxygenic phototrophs in temperate freshwater systems
Authors: Mašín Michal , Nedoma Jiří , Pechar Libor , Koblížek Michal
Published: April 2008

The presence of aerobic anoxygenic phototrophs (AAPs) was recently reported from various marine environments; however, there is little information regarding their distribution in fresh waters. We surveyed a number of freshwater systems in central Europe, by infra‐red fluorometry, infra‐red epifluorescence microscopy, fluorescence emission spectroscopy and pigment analyses. AAPs were found to be abundant in several oligotrophic and mesotrophic lakes (50–400 ng of bacteriochlorophyll a l−1, 10–80% of bacterial biomass), while in more eutrophized water bodies they represented a negligible part of the total microbial community (< 1%). The observed freshwater AAPs were morphologically diverse and different from previously observed marine species. Under temperate European climatic conditions, AAP populations undergo strong seasonal changes in terms of both abundance and species composition, with the maximum biomass in summer and the minimum in winter. In the mountain lakes Čertovo and Plešné, AAPs contributed more than one half of total bacterial biomass during their summer maximum. These results show that photoheterotrophic bacteria represent an important part of the microbial community in many freshwater systems.
Use of the rotating wall vessel technology to study the effect of shear stress on growth behaviour of Pseudomonas aeruginosa PA01
Authors: Crabbé Aurélie , De Boever Patrick , Van Houdt Rob , Moors Hugo , Mergeay Max , Cornelis Pierre
Published: April 2008

The biofilm phenotype of Pseudomonas aeruginosa enables this opportunistic pathogen to develop resistance to the immune system and antimicrobial agents. Pseudomonas aeruginosa biofilms are generated under varying levels of shear stress, depending on the infection site. In the lung mucus of cystic fibrosis (CF) patients, P. aeruginosa forms matrix‐enclosed microcolonies which cause chronic infections representing the major cause of mortality in CF patients. The lung mucus of CF patients is probably characterized by low fluid shear as the main shear‐causing factor, i.e. mucociliary clearance, is absent. In this study, the influence of fluid shear on the growth behaviour of P. aeruginosa PA01 was investigated using a low‐shear suspension culture device, the rotating wall vessel (RWV). Cultivation in low shear induced a self‐aggregating phenotype of P. aeruginosa PA01, resulting in the formation of biofilms in suspension similar to what has been described in CF mucus. The addition of a ceramic bead to the culture medium in the RWV created a higher‐shear condition which led to the formation of surface‐attached rather than suspension biofilms. In low‐shear culture conditions, a significant increase of the rhl N‐butanoyl‐l‐homoserine lactone (C4‐HSL) directed quorum sensing (QS) system, and the psl polysaccharide synthetic locus was demonstrated using gene expression analysis. Accordingly, the low‐shear condition induced a higher production of rhamnolipids, which is controlled by the C4‐HSL QS‐system and is known to play a role in CF lung pathology. These results indicate that fluid shear has an impact on the growth phenotype of P. aeruginosa which might play a role in CF lung infections caused by this bacterium.
Ecological biogeography of cephalopod molluscs in the Atlantic Ocean: historical and contemporary causes of coastal diversity patterns
Authors: Rosa Rui , Dierssen Heidi M. , Gonzalez Liliana , Seibel Brad A.
Published: April 2008

Aim  One of the most recognized ecological paradigms on earth is the increase in species richness from the poles towards the equator. Here we undertake a comprehensive survey of the latitudinal gradients of species richness (LGSR) of coastal cephalopod fauna in the western (WA) and eastern margins (EA) of the Atlantic Ocean, and test climate and non‐climate theories to explain the variation in diversity.

Location  The coastal Atlantic Ocean.

Methods  The diversity and geographical ranges of coastal cephalopods were investigated by means of an exhaustive survey of the primary literature, reports and on‐line data bases. In order to test the productivity, ambient energy and area hypotheses, we investigated the relationship between diversity and net primary production (NPP), sea surface temperature (SST; measure of solar energy input) and continental shelf area, respectively.

Results  LGSR of cephalopod molluscs are present at both Atlantic coasts, but are quite distinct from each other. Historical processes (rise of the Central American Isthmus, formation of ‘Mare Lago’ and glaciations) explained much of the shape and the zenith of LGSR. Contemporary climate and non‐climate variables also each explained over 83% and 50% of the richness variation in WA and EA, respectively, and the best fitted models accounted for > 92% of the variance. By combining latitude with depth a strong Rapoport effect was observed in WA but not in EA.

Main conclusions  Besides the evolutionary history, we demonstrate that the contemporary environmental gradients (SST and NPP), shelf area and extent of coral habitat can predict many of the diversity patterns. The longitudinal difference in Rapoport's bathymetric rule is attributed to western fauna specialization to shallow coral reef habitats and greater ecological tolerance of eastern fauna to upwelling ecosystem dynamics. A combined approach of historical biogeography and species–area–energy theories was essential to fully understand broad‐scale variation in cephalopod biodiversity.
Metabolic and genetic perturbations accompany the modification of galactomannan in seeds of Medicago truncatula expressing mannan synthase from guar (Cyamopsis tetragonoloba L.)
Authors: Naoumkina Marina , Vaghchhipawala Sanchita , Tang Yuhong , Ben Yuxing , Powell Ronald J. , Dixon Richard A.
Published: April 2008

Galactomannan gums are widely used in the food and oil industries, and there is considerable interest in applying biotechnological approaches to improve their physical properties. A mannan synthase from guar (Cyamopsis tetragonoloba) was expressed under the control of a bean β‐phaseolin promoter in transgenic Medicago truncatula. Although the expression of exogenous mannan synthase caused a slight decrease in galactomannan levels in Medicago, the molecular weight and viscosity of the polymer were significantly increased, although the mannose to galactose ratio and degree of polydispersity remained unchanged. At the same time, expression of about 2.8% of the genes was altered significantly in the seeds of transgenic Medicago lines analysed by Affymetrix genome chip, with a particularly striking induction of putative trehalose phosphate synthase genes. Mannan synthase expression also caused large alterations in the levels of a number of sugars and sugar alcohols, suggesting that over‐expression of a processive glycosyltransferase perturbs the mechanisms of sugar sensing and/or homeostasis, possibly involving signalling via trehalose‐6‐phosphate.
THE EFFECTS OF RECENT STRUCTURAL, POLICY AND EXTERNAL SHOCKS TO THE AUSTRALIAN ECONOMY, 1996/97–2001/02
Authors: GIESECKE JAMES
Published: April 2008

The period 1996/97–2001/02 was characterised by rapid economic growth and substantial structural change. This paper analyses this period in detail, relying on results from historical and decomposition simulations with the MONASH model. Changes in the level and composition of economic activity are traced to the effects of a number of government policies, external shocks, and domestic structural changes. The influence of policies such as the GST and tariff reduction proves small, with much of the change in the size and structure of economic activity attributable to technical change.
SOCIALLY OPTIMAL CRIMINAL COURT WAITING TIMES: A PARTIAL INVESTIGATION
Authors: TORRE ANDREW
Published: April 2008

Criminal courts provide a forum for conducting prosecutions with a guilty plea or a trial. Since queues are used as the basis for rationing scarce court facilities delays are inevitable, however courts are invariably criticised as being inefficient as a consequence. This focus on court delay defined as the time elapsing between the listing of the case in the court list and its final disposition is misleading. Rather, attention should be drawn to the considerably longer period between the initiation of proceedings and the conclusion of the case. In the case of defendants not granted bail, this pre‐trial delay confers both costs and benefits on society and this observation can be used to ascertain socially optimal pre‐trial waits.
PROCREATIVE REASONS‐RELEVANCE: ON THE MORAL SIGNIFICANCE OF WHY WE HAVE CHILDREN
Authors: LOTZ MIANNA
Published: April 2008

Advances in reproductive technologies – in particular in genetic screening and selection – have occasioned renewed interest in the moral justifiability of the reasons that motivate the decision to have a child. The capacity to select for desired blood and tissue compatibilities has led to the much discussed ‘saviour sibling’ cases in which parents seek to ‘have one child to save another’. Heightened interest in procreative reasons is to be welcomed, since it prompts a more general philosophical interrogation of the grounds for moral appraisal of reasons‐to‐parent, and of the extent to which such reasons are relevant to the moral assessment of procreation itself. I start by rejecting the idea that we can use a distinction between ‘other‐regarding’ and ‘future‐child‐regarding’ reasons as a basis on which to distinguish good from bad procreative reasons. I then offer and evaluate three potential grounds for elucidating and establishing a relationship between procreative motivation and the rightness/wrongness of procreative conduct: the predictiveness, the verdictiveness, and the expressiveness of procreative reasons.
Developing communities of practice within and outside higher education institutions
Authors: Hodgkinson‐Williams Cheryl , Slay Hannah , Siebörger Ingrid
Published: April 2008

Higher education institutions (HEIs) are largely built on the assumption that learning is an individual process best encouraged by explicit teaching that is, on the whole, separated from social engagement with those outside the university community. This perspective has been theoretically challenged by those who argue for a social constructivist learning theory and a more collaborative approach to learning. Information and communication technologies (ICTs) afford lecturers and students an opportunity for extending the boundaries of a learning experience, not merely beyond the lone individual, but beyond the limits of discipline boundaries within a specific university community and beyond the institution into the local community. This paper illustrates how a collaborative effort between lecturers and students from the Computer Science and Education Departments at Rhodes University, teachers from the local community, the provincial Department of Education and a non‐governmental organisation developed into an unfolding virtual and physical community of practice which enabled ICT take‐up in a number of schools in the Grahamstown District, South Africa. This discussion of what has become known as the e‐Yethu project provides an example of how ICTs, underpinned by the insights of social constructivism, the notion of ‘community of practice’ and in particular Hoadley and Kilner's C4P Framework for Communities of Practice, can serve to help HEIs understand ways in which ICTs can provide opportunities for developing collaborative learning within HEIs, and between the HEI and the local community.
Can International Factor Mobility Reduce Wage Inequality in a Dual Economy?*
Authors: Beladi Hamid , Chaudhuri Sarbajit , Yabuuchi Shigemi
Published: April 2008

This paper analyzes the consequences of international factor movements on the skilled–unskilled wage inequality in a dual‐economy set‐up that includes unemployment and three intersectorally mobile factors of production—unskilled labor, skilled labor, and capital. Thus far, theoretical literature on this subject has adopted the full‐employment framework and hence ignored the problem of unemployment. The analysis in this paper reveals that the results crucially depend on the difference in the intersectoral factor intensities between skilled labor and capital. In particular, it demonstrates the existence of a possibility of deterioration in wage inequality following foreign unskilled‐labor inflow.
Economic Integration, Process and Product Innovation, and Relative Skill Demand
Authors: Braun Sebastian
Published: April 2008

The interaction between economic integration, product and process innovation, and relative skill demand is analyzed in a model of international oligopoly. Lower trading barriers increase the degree of foreign competition. The competing enterprises respond by investing more aggressively in lowering marginal costs of production. Moreover, firms reduce the substitutability of their products through additional investment in product innovation. The paper also shows that the relative demand for skilled workers may increase as a result.
THE EFFECT OF URBANIZATION ON LABOR TURNOVER*
Authors: Finney Miles M. , Kohlhase Janet E.
Published: April 2008

ABSTRACT The paper empirically examines labor market matching as a source of urban agglomeration economies. We work from the hypothesis that job turnover leads to tighter labor matches and estimate the relationship between urbanization and the job mobility of young men. Using a panel from the National Longitudinal Survey of Youth, we find evidence that young men change jobs more frequently in their early career if they live in larger or in more educated urban areas. The sensitivity of the results to whether the young men were “movers” or “stayers” suggests the possible endogeneity of location.
SOCIAL NETWORKS AND THE CONVERGENCE OF POPULATION ATTRIBUTES: A GENERALIZATION
Authors: Brueckner Jan K. , Smirnov Oleg
Published: April 2008

ABSTRACT Analysis of social interactions has recently become an important area of economic research, and the focus of researchers in this area has increasingly shifted toward dynamic models. In one recent contribution, Brueckner and Smirnov (2007) analyze the evolution of population attributes in an exceedingly simple model, where an agent's attributes at time t are equal to the average attribute value among his acquaintances. The pattern of acquaintances in the population is determined by the social network, and Brueckner and Smirnov (BS) explore the effect of network characteristics on the convergence of population attributes over time. They show that some simple sufficient conditions on the network structure ensure convergence to a “melting‐pot” equilibrium where attributes are uniform across agents. The present paper provides a generalization of BS's analysis, allowing for a more general form of the rule governing the evolution of population attributes. The analysis shows that BS's previous conclusions continue to hold under this generalization, while also providing a result that can be applied more generally to other models.
SPATIAL COMPETITION, PRICING, AND MARKET POWER IN TRANSPORTATION: A DOMINANT FIRM MODEL*
Authors: Anderson Simon P. , Wilson Wesley W.
Published: April 2008

ABSTRACT Transport firms compete over space. We develop a dominant firm model of transport services wherein one firm (the railroad) has market power, but competes in space with a competitive alternative (truck‐barge). When constrained, the dominant firm prices to “beat the competition”, which impedes efficiency when demand has some elasticity. We extend the basic model in a number of directions that include the relationship between monopoly prices and the generalized concavity of the shipper demand functions, the effects of multiple terminal markets, the role of joint production (fronthaul–backhaul markets), and the effects of capacity constraints.
USING THE SPATIAL DISTRIBUTION OF BIDDERS TO DETECT COLLUSION IN THE MARKETPLACE: EVIDENCE FROM TIMBER AUCTIONS*
Authors: Price Michael K.
Published: April 2008

ABSTRACT This study develops identification strategies utilizing spatial bidding patterns to detect possible collusion in auction markets. The identification strategy is applied to examine bidder behavior using data drawn from nearly 3,000 auctions (over 10,000 individual bids) for cutting rights of standing timber in British Columbia for the period 1996–2000. Results suggest that observed patterns of behavior are inconsistent with a model of perfectly competitive bidding. Further, changes in such patterns across geographic space are remarkably consistent with patterns of decay in the transmission of knowledge reported in previous empirical work on spillovers.
EXCHANGE RATE REGIME AND MONETARY POLICY INDEPENDENCE IN EAST ASIA
Authors: Kim Chang Jin , Lee Jong‐Wha
Published: April 2008

Abstract.  This paper investigates whether the choice of exchange rate regimes influences the sensitivity of domestic interest rates to international interest rates. We empirically analyse this issue in the context of East Asian economies by employing a regime switching model. We find that the sensitivity of local interest rates to international interest rates declined in Korea and Thailand after they adopted floating exchange rate regimes. We also find that Japan, with a floating exchange regime, has greater independence in monetary policy than a pegged economy such as Hong Kong. These empirical findings suggest that exchange rate flexibility provides greater monetary independence.