bluuebunny/crossref_metadata_2025 huggingface dataset:
Groundwater irrigation and phosphogypsum application: their influence on soil properties and pasture production in northern Victoria
Authors: Burrow D. P. , Surapaneni A.
Published: March 2004

Saline–sodic irrigation water [ECiw = 0.1, 0.8, 2.5, 4.5, 7.5 dS/m, SARiw = 3, 5, 11, 17, 29 (mmolc/L)0.5] was applied to lucerne plots over 1991–95 followed by further irrigation [ECiw = 0.1, 0.8, 4.5 dS/m, SARiw = 3, 5, 17 (mmolc/L)0.5] of perennial pasture in 1997–99 with and without added phosphogypsum (PG = 0, 5 t/ha; May 1998). The later irrigation treatments and PG did not decrease exchangeable sodium percentage (ESP) in the B horizon nor alter bulk soil physical properties. Microaggregate stability to wetting decreased with increasing�residual sodicity and decreasing soil electrolyte concentration. The stability of topsoil aggregates was explained by higher organic carbon content while subsoil aggregate instability was related to higher clay content and higher ESP. Pasture yield decreased by 2 t/ha with an associated increase in soil ESP from 9 to 15%. Pasture yield was highest for ECiw = 0.8 dS/m and this treatment marginally increased N uptake in leaves. Higher yields for this treatment could not be readily explained by soil physico–chemical measurements.
Overview of the irrigated dairy industry in Australia
Authors: Bethune M. , Armstrong D. P.
Published: March 2004

The irrigated dairy industry is an important rural industry and confers significant social and economic benefits to Australia. The future prosperity of irrigated dairying will depend on the efficient use of water resources to overcome: (i) limited irrigation water availability, (ii) rising farm production costs, and (iii) the potential negative impacts of irrigation on the environment. This paper overviews the importance of the irrigated dairy industry to Australia, the production system, industry trends and some of the main challenges facing the industry.
Abrogation of ventricular arrhythmias in a model of ischemia and reperfusion by targeting myocardial calcium cycling
Authors: del Monte Federica , Lebeche Djamel , Guerrero J. Luis , Tsuji Tsuyoshi , Doye Angelia A. , Gwathmey Judith K. , Hajjar Roger J.
Published: March 2004

Abnormal intracellular Ca
2+
cycling plays an important role in cardiac dysfunction and ventricular arrhythmias in the setting of heart failure and transient cardiac ischemia followed by reperfusion (I/R). We hypothesized that overexpression of the sarcoplasmic reticulum Ca
2+
ATPase pump (SERCA2a) may improve both contractile dysfunction and ventricular arrhythmias. Continuous ECG recordings were obtained in 46 conscious rats after adenoviral gene transfer of either SERCA2a or the reporter gene β-galactosidase (βgal) or parvalbumin (PV), as early as 48 h before and 48 h after 30 min ligation of the left anterior descending artery by using an implantable telemetry system. Sham-operated animals were used for comparison for hemodynamic measurements, whereas within-animal baseline was used for electrocardiographic and echocardiographic parameters. All episodes of nonsustained ventricular tachycardia (VT) and ventricular fibrillation (VF) were counted, and their durations were summed by telemetry. I/R decreased regional cardiac wall thickening as well as the maximal rate of left ventricular pressure rise (+dP/dt) and ventricular pressure fall (–dP/dt). SERCA2a restored regional wall thickening and +dP/dt and –dP/dt to levels seen preoperatively. Regional-wall motion and anterior-wall thickening were improved in the SERCA2a animals, as assessed by echocardiography and piezoelectric crystals. To assess whether these effects are SERCA2a specific, we overexpressed a skeletal-muscle protein, PV, to examine whether Ca
2+
buffering alone can mitigate ventricular arrhythmias. During the first hour after I/R, the rate of nonsustained VT plus VF was 16 ± 5 episodes per h (
n
= 6) in the Ad.βgal group, 22 ± 6 in the Ad.PV group, and 4 ± 2(
n
= 6,
P
< 0.01) in the Ad.SERCA2a group. The decrease in VT plus VF in the Ad.SERCA2a group was consistent throughout the 48 h of monitoring. These results show that improving intracellular Ca
2+
handling by overexpression of SERCA2a restores contractile function and reduces ventricular arrhythmias during I/R.
Tumor necrosis factor receptor 1-mediated signaling is required for skin cancer development induced by NF-κB inhibition
Authors: Lind Maria H. , Rozell Björn , Wallin Robert P. A. , van Hogerlinden Max , Ljunggren Hans-Gustaf , Toftgård Rune , Sur Inderpreet
Published: March 2004

NF-κB signaling plays an important role in skin development and epidermal growth control. Moreover, inhibition of NF-κB signaling in murine epidermal keratinocytes
in vivo
, by expression of a keratin 5 (K5)-directed superrepressor form of inhibitor of NF-κB (IκBα), results in an inflammatory response characterized by a massive dermal infiltration of neutrophils, epidermal hyperplasia, and a rapid development of aneuploid squamous cell carcinomas (SCC). We now show that by crossing
K5-I
κ
B
α mice onto a tumor necrosis factor receptor 1(
Tnfr1
)-null background, both the inflammatory and the tumorigenic responses are blocked. The specificity of the block is illustrated by the fact that
K5-I
κ
B
α mice lacking the IL-1 receptor type 1 (Il1r1) develop inflammation and squamous cell carcinomas. Reconstitution of lethally irradiated
K5-I
κ
B
α/
Tnfr1
-/-
mice with
Tnfr1
+/-
bone-marrow does not induce the inflammatory or the tumorigenic phenotype, indicating a critical dependence on Tnfr1-mediated signaling in skin cells or nonimmune cells. Our results suggest a critical role of local Tnfr1-mediated signaling and associated inflammatory response cooperating with repressed keratinocyte NF-κB signaling in driving skin cancer development.
Long-term reinfection of the human genome by endogenous retroviruses
Authors: Belshaw Robert , Pereira Vini , Katzourakis Aris , Talbot Gillian , Pačes Jan , Burt Austin , Tristem Michael
Published: March 2004

Endogenous retrovirus (ERV) families are derived from their exogenous counterparts by means of a process of germ-line infection and proliferation within the host genome. Several families in the human and mouse genomes now consist of many hundreds of elements and, although several candidates have been proposed, the mechanism behind this proliferation has remained uncertain. To investigate this mechanism, we reconstructed the ratio of nonsynonymous to synonymous changes and the acquisition of stop codons during the evolution of the human ERV family HERV-K(HML2). We show that all genes, including the
env
gene, which is necessary only for movement between cells, have been under continuous purifying selection. This finding strongly suggests that the proliferation of this family has been almost entirely due to germ-line reinfection, rather than retrotransposition in
cis
or complementation in
trans
, and that an infectious pool of endogenous retroviruses has persisted within the primate lineage throughout the past 30 million years. Because many elements within this pool would have been unfixed, it is possible that the HERV-K(HML2) family still contains infectious elements at present, despite their apparent absence in the human genome sequence. Analysis of the
env
gene of eight other HERV families indicated that reinfection is likely to be the most common mechanism by which endogenous retroviruses proliferate in their hosts.
Distinct transcriptional programs in thymocytes responding to T cell receptor, Notch, and positive selection signals
Authors: Huang Yina H. , Li Dongling , Winoto Astar , Robey Ellen A.
Published: March 2004

T cell antigen receptor (TCR) signaling is necessary but not sufficient to promote the positive selection of CD4+CD8+thymocytes into CD4+or CD8+mature T cells. Notch signaling has also been implicated as a potential regulator of both CD4/CD8 T cell development and TCR signaling. However, the relationship between positive selection, TCR signaling, and Notch remains unclear. Here we use DNA microarray analysis to compare gene expression changes in CD4+CD8+double-positive thymocytes undergoing positive selection, TCR stimulation, and Notch activation. We find that the genes induced during positive selection can be resolved into two distinct sets. One set, which we term “TCR-induced,” is also induced byin vitroTCR stimulation and contains a large proportion of transcription factors. A second set, which we term “positive-selection-induced,” is not induced byin vitroTCR simulation and contains a large proportion of genes involved in signal transduction pathways. Genes induced by Notch activity overlap substantially with genes induced during positive selection. We also find that Notch activity potentiates the effects of TCR stimulation on gene expression. These results help to identify TCR- and positive-selection-specific transcriptional events and help to clarify the relationship between positive selection and Notch.
Oleic acid levels regulated by glycerolipid metabolism modulate defense gene expression in
Arabidopsis
Authors: Kachroo Aardra , Venugopal Srivathsa C. , Lapchyk Ludmila , Falcone Deane , Hildebrand David , Kachroo Pradeep
Published: March 2004

Stearoyl-acyl-carrier-protein-desaturase-mediated conversion of stearic acid (18:0) to oleic acid (18:1) is a key step, which regulates levels of unsaturated fatty acids in cells. We previously showed that stearoyl-acyl-carrier-protein-desaturase mutants
ssi2
/
fab2
carrying a loss-of-function mutation in the plastidial glycerol-3-phosphate (G3P) acyltransferase (
act1
) have elevated 18:1 levels and are restored in their altered defense signaling. Because G3P is required for the acylation of 18:1 by G3P acyltransferase, it was predicted that reduction of G3P levels should increase 18:1 levels and thereby revert
ssi2
-triggered phenotypes. Here we show that a mutation in G3P dehydrogenase restores both salicylic acid- and jasmonic acid-mediated phenotypes of
ssi2
plants. The G3P dehydrogenase gene was identified by map-based cloning of the
ssi2
suppressor mutant
rdc8
(
gly1-3
) and confirmed by epistatic analysis of
ssi2
with
gly1-1
. Restoration of
ssi2
-triggered phenotypes by the
gly1-3
mutation was age-dependent and correlated with the levels of 18:1. Regeneration of G3P pools by glycerol application in
ssi2
and
ssi2 gly1-3
plants caused a marked reduction in the 18:1 levels, which rendered these plants hypersensitive to glycerol. This hypersensitivity in
ssi2
was rescued by the
act1
mutation. Furthermore, overexpression of the
ACT1
gene resulted in enhanced sensitivity to glycerol. Glycerol application also lowered the 18:1 content in
SSI2
plants and converted these into
ssi2
-mimics. Our results show that 18:1 levels in plastids are regulated by means of acylation with G3P, and a balance between G3P and 18:1 is critical for the regulation of salicylic acid- and jasmonic acid-mediated signaling pathways.
The Fall and Rise of Organising in a Blue-Collar Union
Authors: Griffin Gerard , Moors Rosetta
Published: March 2004

This paper analyses the introduction of the organising philosophy into the largest branch of a national, blue-collar, manufacturing union. It outlines the initial adoption of this philosophy and examines the reasons for the failure of this innovation. Some five years later, a second, more successful attempt to introduce the organising model was made. The factors determining this success are analysed in the paper presented here and comparisons are made with the earlier failed attempt. The paper argues that the level of commitment and zeal of the unions’ leadership was the crucial factor in determining the extent and culture of organising.
Australian Workplace Agreements: An Employer Response
Authors: Gollan Paul J.
Published: March 2004

There is considerable political and industrial relations debate in Australia concerning the value and merit of Australian Workplace Agreements (AWAs). However, formalised individual agreements are a relatively new phenomenon in the Australian industrial relations landscape. Consequently, to date, there has been limited assessment of employer strategies and the perceived organisational outcomes involved in making and negotiating such agreements. The paper presented here attempts to fill this gap by reviewing responses from 688 employers who approved AWAs with the Office of the Employment Advocate (OEA) before February 2000. There are a number of issues that can be identified from this exploratory study. AWA employers were likely to be ‘individualistic’ employers with more individual employee consultation and human resource practices. In addition, the majority of AWAs were introduced to change working time arrangements and simplify existing employment arrangements. According to the survey respondents, employers who have drafted AWAs have generally been able to achieve some positive organisational outcomes and they have generally met the objectives of employers. The survey findings showed that the majority of respondents intended to increase their use of AWAs in the future, citing increased flexibility and some suggesting the benefit of all employees being under one type of industrial relations instrument as the primary reasons for their introduction.
Interaction Between Natural Killer and Dendritic Cells: the Role of CD40, CD80 and Major Histocompatibility Complex Class I Molecules in Cytotoxicity Induction and Interferon‐γ Production
Authors: Terrazzano G. , Pisanti S. , Grimaldi S. , Sica M. , Fontana S. , Carbone E. , Zappacosta S. , Ruggiero G.
Published: March 2004

This study focuses on the differential role of CD40 and CD80 costimulatory molecules and major histocompatibility complex class I (MHC‐I) antigens in the regulation of the interplay between dendritic cells (DCs) and interleukin (IL)‐2‐activated human natural killer (NK) lymphocytes. Our data indicate that CD40 and CD80 molecules might play a preferential role in the induction of cytotoxic function but not in the interferon‐γ(IFN‐γ) production by human IL‐2‐activated NK effectors in the presence of autologous and allogeneic DCs. In addition, a critical role of CD94‐dependent MHC‐I recognition in the regulation of both IFN‐γ production and target cell lysis was shown in the functional interaction between NK and DCs.
Interplay Between Superantigens and Immunoreceptors
Authors: Petersson K. , Forsberg G. , Walse B.
Published: March 2004

Superantigens (SAGs) cause a massive T‐cell proliferation by simultaneously binding to major histocompatibility complex (MHC) class II on antigen‐presenting cells and T‐cell receptors (TCRs) on T cells. These T‐cell mitogens can cause disease in host, such as food poisoning or toxic shock. The best characterized groups of SAGs are the bacterial SAGs secreted by Staphylococcus aureus and Streptococcus pyogenes. Despite a common overall three‐dimensional fold of these SAGs, they have been shown to bind to MHC class II in different ways. Recently, it has also been shown that SAGs have individual preferences in their binding to the TCRs. They can interact with various regions of the variable β‐chain of TCRs and at least one SAG seems to bind to the α‐chain of TCRs. In this review, different subclasses of SAGs are classified based upon their binding mode to MHC class II, and models of trimolecular complexes of MHC–SAG–TCR molecules are described in order to reveal and understand the complexity of SAG‐mediated T‐cell activation.
Human Miscarriage is Associated with Increased Number of CD26+ Decidual Lymphocytes
Authors: Sehmsdorf U. S. , Zenclussen A. C. , Arck P. , Hertwig K. , Joachim R. A. , Klapp B. , Hildebrandt M. O.
Published: March 2004

Dipeptidyl peptidase‐IV (DPP‐IV, CD26), a serine protease with broad distribution in mammalian tissues and known activity in serum, participates in T‐cell activation and promotes a Th1‐like cytokine response. Previous data on murine abortion indicate that DPP‐IV may play a critical role in pregnancy failure by inducing a Th1 local response. Here, we investigated the possible participation of DPP‐IV in the onset of human spontaneous abortion (SA).

The systemic (peripheral blood) and local (decidua) percentages of CD4+, CD8+, CD26+ and CD56+ cells as well as the number of Th1 lymphocytes (CCR5+ cells) were assessed in samples from women after SAs (n = 20) and from women with normally progressing pregnancies (NPs) (n = 27) using flow cytometry and immunohistochemistry. We further measured the DPP‐IV activity and concentrations of Th1 (interferon‐γ and tumour necrosis factor‐α), Th2 [interleukin‐4 (IL‐4), IL‐10] and Th3 (transforming growth factor‐β2) cytokines in serum samples.

We could not find any difference in the number of CD4+, CD8+, CD26+, CD26+/CD4+ or CD8+/CD26+ blood cells between NP and SA patients. No differences in the Th1, Th2 or Th3 cytokine levels could be observed between both groups. However, the percentages of decidual CD26+ lymphocytes as well as the number of decidual Th1 cells were significantly higher in SA samples compared to samples from patients with NP.

Our data support the hypothesis that CD26+ decidual lymphocytes with DPP‐IV activity may play a critical role in SAs, as previously suggested in an abortion mice model. This abortive effect may be mediated by enhancing the levels of Th1 abortogenic cytokines only locally.
Immunization of Saimiri sciureus Monkeys with Plasmodium falciparum Merozoite Surface Protein‐3 and Glutamate‐Rich Protein Suggests that Protection is Related to Antibody Levels
Authors: Carvalho L. J. M. , Oliveira S. G. , Theisen M. , Alves F. A. , Andrade M. C. R. , Zanini G. M. , Brígido M. C. O. , Oeuvray C. , Póvoa M. M. , Muniz J. A. P. C. , Druilhe P. , Daniel‐Ribeiro C. T.
Published: March 2004

The immunogenicity and protective efficacy of various antigen‐adjuvant formulations derived either from the merozoite‐surface protein‐3 (MSP‐3) or the glutamate‐rich protein (GLURP) of Plasmodium falciparum were evaluated in Saimiri sciureus monkeys. These proteins were selected for immunogenicity studies based primarily on their capacity of inducing an antibody‐dependent cellular inhibition effect on parasite growth. Some of the S. sciureus monkeys immunized with MSP‐3212−380‐AS02 or GLURP27−500‐alum were able to fully or partially control parasitaemia upon an experimental P. falciparum [Falciparum Uganda Palo Alto (FUP‐SP) strain] blood‐stage infection, and this protection was related to the prechallenge antibody titres induced. The data are indicative that MSP‐3 and GLURP can induce protective immunity against an experimental P. falciparum infection using adjuvants that are acceptable for human use and this should trigger further studies with those new antigens.
Circulating CD4+CD25+ and CD4+CD25– T Cells in Myasthenia Gravis and in Relation to Thymectomy
Authors: Huang Y.‐M. , Pirskanen R. , Giscombe R. , Link H. , Lefvert A.‐K.
Published: March 2004

Studies in experimental animal models of human autoimmune diseases have revealed that CD4+CD25+ T regulatory (Tr) cells are of thymic origin and have potentials in preventing auto‐aggressive immunity. Myasthenia gravis (MG) is the best‐characterized autoimmune disease. Changes in the thymus are found in a majority of patients with MG. Thymectomy has beneficial effects on the disease severity and course in a substantial proportion of MG patients. But the occurrence and characteristics of Tr cells have not yet been defined in MG. We determined the frequencies and properties of circulating CD4+CD25+ versus CD4+CD25– cells in MG patients and healthy controls (HCs), with special focus on the effect of thymectomy on CD4+CD25+ cells. CD4+CD25high cells comprise only about 2% of blood lymphocytes in both MG patients and HCs. Frequencies of CD4+CD25high cells were similar in MG patients irrespective of treatment with thymectomy. CD4+CD25+ cells in both MG patients and HCs are mainly memory T cells and are activated to a greater extent than CD4+CD25– cells, as reflected by high levels of CD45RO and human leucocyte antigen (HLA)‐DR‐positive cells. In both MG patients and HCs, CD4+CD25+ cells also contained a high proportion of CD95‐expressing cells as possible evidence of apoptosis‐proneness. Upon stimulation with anti‐CD3/CD28 monoclonal antibodies, CD4+CD25+ cells responded more vigorously than CD4+CD25– cells in MG, irrespective of treatment with thymectomy, as well as in HCs. Although CD4+CD25– cells are mainly naïve T cells, in non‐thymectomized MG patients, they are activated to a greater extent as reflected by higher expression of HLA‐DR and CD95 on the surface compared to HCs. The data thus show that there is no deficiency of CD4+CD25+ cells in MG, nor is the proportion of CD4+CD25+ cells influenced by thymectomy.
Long‐Term Modulation By Postnatal Oxytocin of the α2‐Adrenoceptor Agonist Binding Sites in Central Autonomic Regions and the Role of Prenatal Stress
Authors: Díaz‐Cabiale Z. , Olausson H. , Sohlström A. , Agnati L. F. , Narváez J. A. , Uvnäs‐Moberg K. , Fuxe K.
Published: March 2004

The aim of this work was to evaluate whether oxytocin administered in male rats subcutaneously early in life in the absence or presence of food restriction during pregnancy has life‐long effects on the α2‐agonist binding sites in the nucleus of the solitarii tract (NTS), in the hypothalamus and the amygdala, as evaluated by quantitative receptor autoradiography. Maternal food restriction alone increased the affinity of the α2‐agonist [3H]UK14.304 binding sites exclusively in the NTS. In offspring from ad libitum fed dams, oxytocin treatment significantly increased the density of α2‐agonist binding sites in the NTS and in the hypothalamus. The Kd value of the α2‐agonist binding sites in the hypothalamus of these rats, but not in the other regions studied, was also significantly increased. In offspring from food‐restricted dams, oxytocin treatment produced a significant increase of the Bmax values in the hypothalamus and the amygdala and the Kd value of the α2‐agonist binding sites in the NTS of these rats also was selectively and significantly increased. These results suggest that a postnatal, oxytocin‐induced increase of regional α2‐adrenoceptor function can be seen in adulthood by a persistent, regionally selective increase in the density of central α2‐adrenoceptor agonist binding sites, in the absence of an affinity change in the NTS. Such a regional increase of α2‐adrenoceptor signalling in adulthood may contribute to the anti‐stress action of postnatal oxytocin. By contrast, after prenatal stress, the potential increase in α2‐adrenoceptor signalling takes place via selective increases of density with no changes of affinity of the α2‐agonist binding sites in the hypothalamus and the amygdala.
Plasma Vasopressin Concentrations and Fos Protein Expression in the Supraoptic Nucleus Following Osmotic Stimulation or Hypovolaemia in the Ovariectomized Rat: Effect of Oestradiol Replacement
Authors: Hartley D. E. , Dickson S. L. , Forsling M. L.
Published: March 2004

The set points for vasopressin release in response to increasing plasma osmolality and hypovolaemia alter with reproductive status. Here, we studied stimulated vasopressin release following ovariectomy and oestrogen replacement, neuronal activity being measured in terms of immediate early gene expression. Observations were carried out on three groups of female Sprague‐Dawley rats. The first group were ovariectomized. The second group were given a subcutaneous oestrogen implant (20 µg/ml oestradiol‐17β) at the time of ovariectomy. The final group were left intact and observations performed at oestrus. Two weeks after ovariectomy, vascular cannulae were implanted under anaesthesia and at least 48 h allowed for recovery before hormone release was stimulated by infusion of 1.5 m NaCl for 90 min, or hypovolaemia induced by the removal of 10 mg/kg body weight taken in 1‐ml aliquots. Blood pressure was monitored, and blood samples were taken for determination of packed cell volume and plasma vasopressin and osmolality. After a minimum of 48 h, the challenge was repeated, the rats anaesthetized, and perfused with 4% paraformaldehyde. Brain sections were processed for immunocytochemical detection of Fos protein. Vasopressin release in response to both stimuli was reduced in ovariectomized compared to intact rats and the response could be substantially restored by oestradiol replacement. The number of Fos positive cells in the supraoptic nucleus of oestrogen‐replaced rats was significantly higher than in the ovariectomized group and not statistically different from the intact group.
DAMGO Suppresses Both Excitatory and Inhibitory Synaptic Transmission in Supraoptic Neurones of Mouse Hypothalamic Slice Preparations
Authors: Honda E. , Ono K. , Inenaga K.
Published: March 2004

Opioid effects on synaptic transmission in the mouse supraoptic nucleus (SON) were investigated using whole‐cell, patch‐clamp techniques. The µ‐opioid receptor agonist, [d‐Ala2, N‐Me‐Phe4, Gly5‐ol]‐enkephalin (DAMGO) decreased the amplitude of both evoked excitatory postsynaptic currents (eEPSCs) and inhibitory postsynaptic currents (eIPSCs), and also decreased the frequency of both miniature EPSCs and IPSCs without effect on the amplitude. The selective µ‐opioid receptor antagonist, d‐Phe‐Cys‐Tyr‐D‐Trp‐Orn‐Thr‐Pen‐Thr‐NH2, and the nonselective antagonist naloxone, antagonized these inhibitory effects. The application of DAMGO suppressed the amplitude of both the first and second evoked postsynaptic currents with a paired‐pulse stimulus protocol, but increased the paired‐pulse ratios (second ePSC/first ePSC). DAMGO induced neither inward nor outward currents, and had no significant changes in either glutamate‐ or GABA‐induced currents. When compared with the relatively selective κ‐ and δ‐opioid receptor agonists dynorphin and [D‐Pen2, D‐Pen5]‐enkephalin, DAMGO showed the most potent inhibitory effects on evoked and miniature postsynaptic currents. Taken together, these results imply that DAMGO strongly suppresses the release of glutamate and GABA via µ‐opioid receptors in the mouse SON, and support the involvement of presynaptic regulation by opioids in the control of magnocellular neurosecretory neurones.
Intracellular Calcium Increase and Somatodendritic Vasopressin Release by Vasopressin Receptor Agonists in the Rat Supraoptic Nucleus: Involvement of Multiple Intracellular Transduction Signals
Authors: Sabatier N. , Shibuya I. , Dayanithi G.
Published: March 2004

Vasopressin neurones of the supraoptic nucleus are autoregulated by vasopressin released from their soma and dendrites. Vasopressin binds to specific autoreceptors to trigger an influx of Ca2+, and this response involves both phospholipase C (PLC) and adenylate cyclase (AC) pathways that, in the periphery, are activated by V1 (V1a and V1b)‐ and V2‐type receptors. To investigate the pathways involved in the [Ca2+]i response, [Ca2+]i measurements were made on freshly dissociated neurones using Fura‐2 microspectrofluorimetry, and vasopressin release was measured from isolated supraoptic nuclei. The [Ca2+]i increase and vasopressin release induced by the V1a agonist were strongly inhibited by a PLC blocker, an IP3 receptor antagonist, and a PKC blocker. An AC inhibitor did not affect the V1a response, while PKA inhibitors significantly reduced the V1a‐induced [Ca2+]i and release responses. The [Ca2+]i increase and vasopressin release elicited by the V2 agonist were attenuated not only by AC pathway blockers, but also by PLC inhibitors. Surprisingly, the V1b agonist showed no [Ca2+]i or vasopressin release response. In conclusion, the V1a agonist activates both PLC and AC pathway, confirming the functional expression of a V1a vasopressin receptor on vasopressin neurones. The V2 agonist activation of both PLC and AC pathways could result from an action on the PLC‐linked unknown receptor, and/or the AC‐linked dual angiotensin II‐vasopressin receptor.
Leptin‐Mediated Effects of Undernutrition or Fasting on Luteinizing Hormone and Growth Hormone Secretion in Ovariectomized Ewes Depend on the Duration of Metabolic Perturbation
Authors: Henry B. A. , Goding J. W. , Tilbrook A. J. , Dunshea F. R. , Blache D. , Clarke I. J.
Published: March 2004

We aimed to determine the importance of leptin in the regulation of luteinizing hormone (LH) and growth hormone (GH) secretion in ovariectomized (OVX) ewes. Lean and fat sheep were produced by dietary manipulation over 8 months and were then fasted for 32 h. Plasma concentrations of glucose, insulin and leptin were higher in the fat group. Fasting decreased plasma concentrations of glucose and insulin and increased concentrations of nonesterified fatty acids (NEFA) in fat and lean ewes, but leptin concentrations were reduced in the fat group only. Plasma GH concentrations were higher in the lean group and LH concentrations were lower; there was no effect of fasting. These data suggested that long‐term changes in plasma leptin concentrations might affect LH and GH secretion, but acute changes with fasting had no effect. OVX ewes of normal body weight were fasted for 72 h with or without intracerebroventricular (i.c.v.) infusion of leptin (4 µg/h), achieving similar metabolic effects to the 32 h fast. The 72‐h fast increased LH pulse amplitude, mean GH and cortisol concentrations, but these changes were corrected towards normal by leptin treatment. Thus, leptin could attenuate fasting‐induced alterations in the secretion of LH, GH and cortisol. Finally, we food‐restricted OVX ewes for 4 months (lean), leading to a 20‐kg reduction in body weight. Plasma concentrations of leptin and insulin were decreased, and plasma GH concentrations increased, but there was no effect on plasma concentrations of LH, glucose or NEFA. Icv infusion of leptin did not affect any endocrine or metabolic parameter in these ewes. In summary, maintenance of a lean or fat condition for a prolonged period (8 months) or an extended fasting (72 h) can affect LH and GH secretion, but short‐term food restriction (4 months) affected only GH secretion and short‐term fasting (32 h) had no effect on either LH or GH secretion. This is in spite of altered plasma leptin concentrations in all circumstances studied. Although leptin treatment can restore plasma concentrations of LH, GH and cortisol towards normal in sheep fasted for 72 h, some other factor(s) must signal to the brain to cause shifts in neuroendocrine function in other conditions where nutritional/metabolic status is altered.
Acute Carbon Dioxide Exposure in Healthy Adults: Evaluation of a Novel Means of Investigating the Stress Response
Authors: Kaye J. , Buchanan F. , Kendrick A. , Johnson P. , Lowry C. , Bailey J. , Nutt D. , Lightman S.
Published: March 2004

Acute hypercapnia was studied to assess its potential as a noninvasive and simple test for evoking neuroendocrine, cardiovascular and psychological responses to stress in man. A single breath of four concentrations of carbon dioxide (CO2), 5%, 25%, 35% and 50%, was administered to nine healthy volunteers in a randomized, single‐blind fashion. Although no adverse effects occurred, most subjects were unable to take a full inspired vital capacity breath of 50% CO2. In response to the remaining exposures, subjective and somatic symptoms of anxiety increased in a dose‐dependent manner. Unlike 5% and 25% CO2, 35% CO2stimulated significant adrenocorticotropic hormone and noradrenaline release at 2 min and cortisol and prolactin release at 15 min following inhalation. This same dose also provoked a significant bradycardia that was followed by an acute pressor response. No significant habituation of psychological, hypothalamic‐pituitary‐adrenal (HPA) or cardiovascular responses following 35% CO2was seen when this dose was repeated after 1 week. A single breath of 35% CO2safely and reliably produced sympathetic and HPA axis activation and should prove a useful addition to currently available laboratory tests of the human stress response.
Androgen Inhibits, While Oestrogen Enhances, Restraint‐Induced Activation of Neuropeptide Neurones in the Paraventricular Nucleus of the Hypothalamus
Authors: Lund T. D. , Munson D. J. , Haldy M. E. , Handa R. J.
Published: March 2004

The hormonal response to stress is enhanced by oestrogen but inhibited by androgens. To determine underlying changes in activity of neuropeptide neurones in the paraventricular nucleus of the hypothalamus (PVN), we examined the effect of oestrogen and androgen treatment on restraint‐induced c‐fos mRNA, corticotropin‐releasing hormone (CRH) heteronuclear RNA, and arginine vasopressin hnRNA expression in the PVN. Male rats were gonadectomized and injected with oestradiol benzoate (EB) or dihydrotestosterone propionate (DHTP; s.c., daily for 4 days). Rats were stressed by restraint for 10 min or 30 min before killing. Other rats were stressed for 30 min and then returned to their home cage for 20 min before killing. Corticosterone and adrenocorticotropic hormone responses to restraint stress were significantly greater in EB‐treated rats and lower in DHTP‐treated rats at the 30‐min timepoint compared to controls. c‐fos mRNA increases following stress were augmented by EB but inhibited by DHTP. CRH hnRNA expression increased significantly in the PVN in response to restraint stress, and this increase was augmented by EB treatment, but decreased by DHTP treatment. Vasopressin hnRNA expression was also increased in response to stress, and this increase was attenuated by DHTP. These findings indicate that gonadal hormones influence the reactivity of the hypothalamic‐pituitary adrenal axis to stress.
Roles of Corticotropin‐Releasing Factor, Neuropeptide Y and Corticosterone in the Regulation of Food Intake In Xenopus laevis
Authors: Crespi E. J. , Vaudry H. , Denver R. J.
Published: March 2004

In mammals, hypothalamic control of food intake involves counterregulation of appetite by anorexigenic peptides such as corticotropin‐releasing factor (CRF), and orexigenic peptides such as neuropeptide Y (NPY). Glucocorticoids also stimulate food intake by inhibiting CRF while facilitating NPY actions. To gain a better understanding of the diversity and evolution of neuroendocrine feeding controls in vertebrates, we analysed the effects of CRF, NPY and glucocorticoids on food intake in juvenile Xenopus laevis. We also analysed brain CRF and NPY mRNA content and plasma corticosterone concentrations in relation to nutritional state. Intracerebroventricular (i.c.v.) injection of ovine CRF suppressed food intake while CRF receptor antagonist αhelical CRF(9–41) significantly increased food intake relative to uninjected and placebo controls. By contrast, i.c.v. injection of frog NPY and short‐term corticosterone treatment increased food intake. Semi‐quantitative reverse transcription‐polymerase chain reaction analyses showed that CRF and NPY mRNA fluctuated with food intake in the brain region containing the mid‐posterior hypothalamus, pretectum, and optic tectum: CRF mRNA decreased 6 h after a meal and remained low through 31 days of food deprivation; NPY mRNA content also decreased 6 h after a meal, but increased to prefeeding levels by 24 h. Plasma corticosterone concentration increased 6 h after a meal, returned to prefeeding levels by 24 h, and did not change with prolonged food deprivation. This postprandial increase in plasma corticosterone may be related to the subsequent increase in plasma glucose and body water content that occurs 24 h postfeeding. Overall, our data support the conclusion that, similar to other vertebrates, CRF is anorexigenic while NPY is orexigenic in X. laevis, and CRF secretion modulates food intake in the absence of stress by exerting an inhibitory tone on appetite. Furthermore, the stress axis is activated in response to food intake, but in contrast to mammals and birds is not activated during periods of food deprivation.
Modelling the Pituitary Response to Luteinizing Hormone‐Releasing Hormone
Authors: Scullion S. , Brown D. , Leng G.
Published: March 2004

The pituitary response to luteinizing hormone‐releasing hormone (LHRH) is steroid‐dependent and varies throughout the reproductive cycle, but the rapid rise in pituitary sensitivity on the day of the ovulation‐inducing LH surge is due to a ‘self‐priming’ effect of exposure to LHRH that results in a potentiation of pituitary responsiveness 35–40 min later. The expression of this effect is itself steroid‐dependent, and is most marked on pro‐oestrus. Here, a model of LHRH‐induced LH release was developed to incorporate the changes in pituitary sensitivity observed throughout the reproductive cycle. LH release is based on the Law of Mass Action, and a component related to self‐priming is included in the model, incorporating the delay between initial exposure and potentiation of responsiveness and an upper maximum to the achievable level of priming. Where possible, model parameters were obtained from biological values, otherwise they were optimized to fit an experiment performed in vivo. These parameters were then used to test the model against other experimental data obtained both in vivo and in vitro. The model provided a good fit to the in vivo data but the in vitro experimental data required a change in one parameter, the upper limit of priming. We conclude that this model of the pituitary release mechanism can simulate the changes in pituitary responsiveness throughout the reproductive cycle. We suggest that substitution of this model in a previous model of the LHRH pulse generator could allow more appropriate tests of the LHRH pulse generator model.
Effects of ethanol preservation on otolith microchemistry
Authors: Hedges K. J. , Ludsin S. A. , Fryer B. J.
Published: March 2004

Solution‐based inductively coupled plasma‐mass spectrometry was used to examine the effects of exposure time to ethanol (0, 1, 3, 9, 27 and 81 days) and ethanol quality (ACS‐v. HPLC‐grade) on strontium (Sr) and barium (Ba) concentrations in sagittal otoliths of hatchery‐raised and wild‐caught young‐of‐the‐year walleye Stizostedion vitreum. No effect of either attribute on Sr and Ba concentrations were detected, indicating that metabolically inert elements that replace calcium in the calcium carbonate matrix (e.g. Sr and Ba) are not influenced by storage in 95% ethanol.
Temperature effects on anaesthesia with clove oil in six temperate‐zone fishes
Authors: Hoskonen P. , Pirhonen J.
Published: March 2004

The potential use of clove oil (eugenol) as an anaesthetic for Atlantic salmon Salmo salar, brown trout Salmo trutta, rainbow trout Oncorhynchus mykiss, whitefish Coregonus lavaretus, perch Perca fluviatilis and roach Rutilus rutilus was examined at 5, 10, 15 and 20° C using three anaesthetic concentrations (varying from 20 to 200 mg l−1) at each temperature. Substantial species differences in sensitivity to clove oil were observed, even amongst congeners, and there may be some disadvantages (slow recovery and possibly mortality) with using clove oil for 0+ year whitefish and at low temperatures for perch and roach.
Electrofishing‐induced cardiac disturbance and injury in rainbow trout
Authors: Schreer J. F. , Cooke S. J. , Connors K. B.
Published: March 2004

Cardiac output (CO), heart rate (HR) and stroke volume (SV) were monitored in rainbow trout Oncorhynchus mykiss electroshocked (pulsed DC) with various voltage, frequency, pulse width and shock duration settings. Additionally, behavioural recovery times and internal haemorrhaging were examined. During electroshock, heart function became erratic and typically ceased for much of the event (cardiac arrest). Following electroshock, CO increased almost entirely due to an increase in SV. Cardiac function generally returned to resting levels within 2–3 h. Behaviourally, recovery was much more rapid, typically taking only a few minutes for fish to regain equilibrium and to begin swimming normally, and only rarely was >1 h. Internal injury ranged from 0 to 7 cm2 of haemorrhaging along the spine and surrounding musculature, although only 4% of the fish had corresponding damage to the vertebrae. Comparisons across the various electrofisher settings indicate that response and injury are highly variable, but generally increased with more intense settings. Higher frequencies and voltages appear to most negatively affect behavioural recovery and injury while longer shock durations increased the length of cardiac arrest and the duration of cardiac recovery. Because of the variability in results and small sample sizes, however, the strongest conclusion that can be drawn from this work is that electrofishing, regardless of the settings, has a considerable negative impact on rainbow trout that is often not apparent externally. Additionally, this study has shown how electrofishing directly effects fish physiologically through impairment of cardiac function. Studies examining the physiological and behavioural response of fishes and subsequent recovery will be necessary for the development of electrofishing guidelines which minimize the disturbance to fishes.
Functional groups of lagoon fish species in Languedoc Roussillon, southern France
Authors: Dumay O. , Tari P. S. , Tomasini J. A. , Mouillot D.
Published: March 2004

Ten functional traits of fish species were related to habitat, diet or food acquisition, to propose a classification of 21 lagoon fishes into 10 functional groups. The selection of traits was based on their functional interest and the ease of measurement. Some groups were taxonomically related containing species belonging to the same genus, e.g. Syngnathus, Atherina or Pomatochistus. Species with a flat body shape constituted another group and three species (Anguilla anguilla, Gambusia affinis and Callionymus pusillus) formed individual groups. These results could be used to constitute functional units and to simplify such complex ecosystems and their interactions.
Micropogonias undulatus(L.), another exotic arrival in European waters
Authors: Stevens M. , Rappé G. , Maes J. , Van Asten B. , Ollevier F.
Published: March 2004

Two living specimens of the Atlantic croaker Micropogonias undulatus have been caught during recent years in Belgian waters (Southern Bight of the North Sea): one in August 1998 as a by‐catch of the commercial shrimp fishery in coastal waters, another in October 2001 on a tidal flat in the brackish part of the Scheldt Estuary. These represent the first records of this north‐west Atlantic species in European waters, and their occurrence is likely to be due to transportation in ship ballast water.
Responses of the northern anchovy to the dynamics of the pelagic environment: identification of fish behaviours that may leave the population under risk of overexploitation
Authors: Robinson C. J.
Published: March 2004

Northern anchovy Engraulis mordax, in an upwelling area off the west coast of Baja California, Mexico, had several strategies in response to chlorophyll a distribution and availability. When the pigment was scarce, northern anchovies practically disappeared from the area and they returned to coastal waters when it was abundant. The fish gathered in specific areas where low turbulence mixing and high concentrations of chlorophyll a existed. The northern anchovies, responding to food concentration in a stable environment, were probably vulnerable to overexploitation because they were highly concentrated. More than 80% of the total fish density, estimated by acoustics, was recorded in a reduced area. Northern anchovies may have been vulnerable to the purse‐seiner fleet because they were swimming at shallow depth; they were close to shore not far from the fleet's base and they were concentrated in an area where several fishing boats could catch them. Studying the responses of shoaling fishes to fluctuation in the pelagic environment, with the intention of identifying behaviours that may leave the stock highly vulnerable to fishing, may help guide their management.
Stepping stone gene flow in an estuarine‐dwelling sparid from south‐east Australia
Authors: Burridge C. P. , Hurt A. C. , Farrington L. W. , Coutin P. C. , Austin C. M.
Published: March 2004

Allozyme and mitochondrial DNA variation was surveyed in Acanthopagrus butcheri to examine the pattern of gene flow among estuaries in south‐east Australia. Allozymes distinguished two peripheral estuaries from the remaining six, although the pattern of genetic variation could owe more to selection than reproductive isolation, and overall structure was small (θ = 0·012). In contrast, mitochondrial DNA revealed a high degree of genetic structure (θ = 0·263), and a significant relationship with geographic isolation. Consequently, contemporary gene flow mostly between adjacent estuaries, consistent with a one‐dimensional stepping stone model, is evident in south‐east Australia. The data indicate that management of A. butcheri within the study range should be conducted at the scale of individual or geographically proximate estuaries.
Characterization of TCDD‐induced craniofacial malformations and retardation of zebrafish growth
Authors: Hill A. , Howard V. , Cossins A.
Published: March 2004

The documented 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD)‐induced effects on zebrafish Danio rerio including craniofacial malformations and a general retardation of growth, were further characterized in the present study. A significant decrease in total body length and the length of each bone in the upper and lower jaw was identified in exposed larvae from an exposure concentration of 30 ng l−1 TCDD. This study is the first quantitative evidence for the effects of TCDD on the upper jaw and also demonstrates that TCDD‐induced craniofacial malformations and retardation of growth are very sensitive endpoints of dioxin toxicity.
Phylogenetic position of Salmo(Platysalmo)platycephalus Behnke 1968 from south‐central Turkey, evidenced by genetic data
Authors: Sušnik S. , Schöffmann J. , Snoj A.
Published: March 2004

To determine whether the current classification of the flathead trout Salmo (Platysalmo) platycephalus, endemic to the upper reaches of the Zamanti River system, Turkey, based solely on morphology, is in congruence with molecular phylogeny, the nucleotide sequence variation in mitochondrial (control region and cytochrome b gene) and nuclear (internal transcribed spacer of rRNA genes) DNA for the flathead trout and various representatives of the genus Salmo was studied. On the basis of pair‐wise genetic distance estimates, the highest differences were found to exist between the flathead trout and S. salar, S. ohridana and S. obtusirostris, whereas the differences between the flathead trout and S. trutta were minimal. All the analyses performed firmly positioned the flathead trout within the Adriatic phylogeographic lineage of S. trutta; however, the exact position of the flathead trout within the Adriatic cluster was irresolvable. Accordingly, classifying the flathead trout as a subgenus of Salmo is unjustifiable and its reclassification in a lower taxonomic category is suggested by the present study.
Pacific halibut chronology of bomb radiocarbon in otoliths from 1944 to 1981 and a validation of ageing methods
Authors: Piner K. R. , Wischniowski S. G.
Published: March 2004

Pacific halibut Hippoglossus stenolepis of known age were used to create a reference chronology of radiocarbon levels for the years 1944–1981. Levels of radiocarbon in Pacific halibut otoliths pre‐1958 were among the lowest reported to date, but radiocarbon levels increased dramatically post‐1960. Subsequently, this reference chronology was used to validate ages determined using the standard break and burn and surface ageing technique. These older fish were collected at a later date but were born during this period of rapidly increasing radiocarbon levels. Otolith cores were compared to the reference chronology based upon the presumed birth year determined from annulus counts and year of capture. The ages derived from both break and burn and surface ageing methods were determined to be accurate.