bluuebunny/crossref_metadata_2025 huggingface dataset:
Sea warming and fish distribution: the case of the small pelagic fish, Sardinella aurita, in the western Mediterranean
Authors: SABATÉS ANA , MARTÍN PALOMA , LLORET JOSEP , RAYA VANESA
Published: September 2006

This study analyses the temporal and spatial changes in abundance and distribution of the warm water species round sardinella (Sardinella aurita) in the western Mediterranean over the last decades in relation to sea water temperature. In the western Mediterranean basin (1950–2003), a significant positive relationship was found between round sardinella landings and temperature anomalies. Along a latitudinal gradient off the Mediterranean Iberian coast (1989–2004), a gradual increase in species abundance was observed from south to north, with a certain time lag going northwards, associated with the increase in sea water temperature. The abundance of round sardinella in the two warmest and southernmost areas was positively and significantly correlated with sea surface temperature registered during the start of gonad maturation the previous year. In addition, the positive relationship established between water temperature and abundance of round sardinella in the coldest and northernmost study area demonstrates that there is a temperature limit for the distribution of this species in the western Mediterranean. In addition, this study analyses round sardinella larvae distribution and abundance in the summers of 2003 and 2004, and conducts a comparison with the situation 20 years ago (summer 1983). Results show a marked increase in larval abundance during the last decades and the present appearance of larvae in the northernmost study areas, where they did not occur 20 years ago. This indicates the successful reproduction of round sardinella in the northern part of the Mediterranean, where the species has expanded, confirming its establishment in the area.
Effects of microflora on the neonatal development of gut mucosal T cells and myeloid cells in the mouse
Authors: Williams Amanda M. , Probert Christopher S. J. , Stepankova Renata , Tlaskalova‐Hogenova Helena , Phillips Anne , Bland Paul W.
Published: September 2006

Colonization with commensal flora in very early life may profoundly influence intestinal lymphoid development and bias later immune responses. We defined gut‐homing T cell phenotypes and the influence of flora on intestinal immune development in mice. Intestinal T cells were phenotyped and quantified in conventional (CV), germfree (GF) and conventionalized germfree (GF/CV) neonatal mice by immunohistochemistry. Mucosal adressin cell adhesion molecule 1 (MAdCAM‐1) was expressed by mucosal vessels at birth in CV and GF mice and was more prevalent in CV than GF small intestine, but was distributed similarly and did not change with age. Less MAdCAM‐1 was expressed in the colon; its distribution became restricted after weaning, with no difference between CV and GF mice. CD3+β7+ cells were present in similar numbers in CV and GF intestine at birth. They were CD62L– in CV mice and were accompanied by further CD3+β7+CD62L– T cells as development progressed, but in GF and GF/CV intestine they expressed CD62L and numbers did not change. IEL numbers increased at weaning in CV mice in both small and large intestine, but showed delayed development in GF intestine. Macrophages were present at high levels from birth in GF intestine, but dendritic cells did not develop until day 16. Thus, fetus‐derived T cells seed the intestinal lamina propria before birth via β–MadCAM interactions. Their activation status depends on the microbiological status of the dam, and without a commensal flora they remain naive. We propose that these cells regulate antigen responsiveness of the developing mucosal T cell pool.
Dendritic cells, but not macrophages or B cells, activate major histocompatibility complex class II‐restricted CD4+ T cells upon immune‐complex uptake in vivo
Authors: De Jong Judith M. H. , Schuurhuis Danita H. , Ioan‐Facsinay Andreea , Welling Mick M. , Camps Marcel G. M. , Van Der Voort Ellen I. H. , Huizinga Tom W. J. , Ossendorp Ferry , Verbeek J. Sjef , Toes René E. M.
Published: September 2006

Professional antigen‐presenting cells (APC) are able to process and present exogenous antigen leading to the activation of T cells. Antigen–immunoglobulin (Ig)G complexes (IC) are much more efficiently processed and presented than soluble antigen. Dendritic cells (DC) are known for their ability to take up and process immune complex (IC) via FcγR, and they have been shown to play a crucial role in IC‐processing onto major histocompatibility complex (MHC) class I as they contain a specialized cross‐presenting transport system required for MHC class I antigen‐processing. However, the MHC class II‐antigen‐processing pathway is distinct. Therefore various other professional APC, like macrophages and B cells, all displaying FcγR, are thought to present IC‐delivered antigen in MHC class II. Nonetheless, the relative contribution of these APC in IC‐facilitated antigen‐presentation for MHC class II in vivo is not known. Here we show that, in mice, both macrophages and DC, but not B cells, efficiently capture IC. However, only DC, but not macrophages, efficiently activate antigen‐specific MHC class II restricted CD4+ T cells. These results indicate that mainly DC and not other professional APC, despite expressing FcγR and MHC class II, contribute significantly to IC‐facilitated T cell activation in vivo under steady‐state conditions.
The strength of the chemotactic response to a CCR5 binding chemokine is determined by the level of cell surface CCR5 density
Authors: Desmetz Caroline , Lin Yea‐Lih , Mettling Clément , Portalès Pierre , Rabesandratana Herisoa , Clot Jacques , Corbeau Pierre
Published: September 2006

We have shown that the intensity of expression of the C‐C chemokine receptor CCR5 at the single CD4+ cell level strongly determines the efficiency of its function as a coreceptor for human immunodeficiency virus type 1. By analogy, we examined if the number of CCR5 molecules at the cell surface might determine its chemotactic response to CCR5 ligands. To test this hypothesis, we measured by flow cytometry the migration of primary human T cells towards the CCR5‐binding chemokine CCL5 in vitro. First, we observed a dose‐dependent blockage of this migration exerted by an anti‐CCR5 monoclonal antibody. Second, we sorted peripheral blood mononuclear cells into five subpopulations expressing various cell surface CCR5 densities, and observed a correlation between the intensity of migration towards CCL5 and the level of CCR5 expression on these subpopulations. Third, we transduced CCR5+ peripheral blood mononuclear cells with the CCR5 gene, and observed that the CCR5 over‐expression induced an over‐migration towards CCL5. Finally, we observed in healthy donors a correlation between the chemotactic response of peripheral blood CD8+ T cell to CCL5 and their level of surface CCR5 expression. T‐cell surface CCR5 density, which is constant over time for a given individual, but varies drastically among individuals, might therefore be an important personal determinant of T‐cell migration in many biological situations where CCR5‐binding chemokines play a role, such as graft rejection, T helper 1‐mediated auto‐immune diseases, and infectious diseases involving CCR5. Moreover, our data highlight the therapeutic potential of CCR5 antagonists in these situations.
The inflammation‐associated Salmonella SopA is a HECT‐like E3 ubiquitin ligase
Authors: Zhang Ying , Higashide Wendy M. , McCormick Beth A. , Chen Jue , Zhou Daoguo
Published: September 2006

Salmonella translocate a group of type III effectors into the host cells to induce entry, promote survival and cause intestinal inflammation. Although the biochemical and cellular mechanisms of how bacterial effectors function inside host cells remain largely unknown, studies have indicated that a likely strategy is to exploit host cellular pathways through functional mimicry. We report here that SopA, a Salmonella type III effector, mimics the mammalian HECT E3 ubiquitin ligase. SopA preferentially uses the host UbcH5a, UbcH5c and UbcH7 as E2s, which are involved in inflammation. Both the wild‐type SopA and the mutant SopAC753S were expressed and translocated at similar levels during the infection of HeLa cells. A Salmonella strain expressing a catalytically incompetent SopAC753S mutant had reduced Salmonella‐induced polymorphonuclear leukocytes transepithelial migration. We speculate that SopA ubiquitinate bacterial/host proteins involved in Salmonella‐induced intestinal inflammation.
Positive regulation of Bacillus subtilis ackA by CodY and CcpA: establishing a potential hierarchy in carbon flow
Authors: Shivers Robert P. , Dineen Sean S. , Sonenshein Abraham L.
Published: September 2006

Conversion of pyruvate to acetate via the phosphotransacetylase‐acetate kinase pathway generates ATP and is a major overflow pathway under conditions of carbon and nitrogen excess. In Bacillus subtilis, this pathway is positively regulated by CcpA, a global regulator of carbon metabolism genes. Transcription of the acetate kinase gene (ackA) proved to be activated as well by a second global regulatory protein, CodY. Expression of an ackA–lacZ fusion was reduced in a codY mutant strain. CodY was found to bind in vitro to two sites in the ackA promoter region and to stimulate ackA transcription in a run‐off transcription assay. This is the first known case of direct positive regulation by CodY. CodY and CcpA were found to bind to neighbouring sites and their effects were additive both in vivo and in vitro. Surprisingly, positive regulation by CodY, unlike repression, responded primarily to only one type of effector molecule. That is, branched‐chain amino acids (BCAAs) served as more potent co‐activators of CodY‐dependent ackA transcription than did GTP. Given the roles of CcpA and CodY in regulating genes whose products determine the metabolic fate of pyruvate, these two proteins may act together to mediate a hierarchical conversion of pyruvate to its many potential products.
Differentiation between electron transport sensing and proton motive force sensing by the Aer and Tsr receptors for aerotaxis
Authors: Edwards Jessica C. , Johnson Mark S. , Taylor Barry L.
Published: September 2006

Aerotaxis (oxygen‐seeking) behaviour in Escherichia coli is a response to changes in the electron transport system and not oxygen per se. Because changes in proton motive force (PMF) are coupled to respiratory electron transport, it is difficult to differentiate between PMF, electron transport or redox, all primary candidates for the signal sensed by the aerotaxis receptors, Aer and Tsr. We constructed electron transport mutants that produced different respiratory H+/e– stoichiometries. These strains expressed binary combinations of one NADH dehydrogenase and one quinol oxidase. We then introduced either an aer or tsr mutation into each mutant to create two sets of electron transport mutants. In vivo H+/e– ratios for strains grown in glycerol medium ranged from 1.46 ± 0.18–3.04 ± 0.47, but rates of respiration and growth were similar. The PMF jump in response to oxygen was proportional to the H+/e– ratio in each set of mutants (r2 = 0.986–0.996). The length of Tsr‐mediated aerotaxis responses increased with the PMF jump (r2 = 0.988), but Aer‐mediated responses did not correlate with either PMF changes (r2 = 0.297) or the rate of electron transport (r2 = 0.066). Aer‐mediated responses were linked to NADH dehydrogenase I, although there was no absolute requirement. The data indicate that Tsr responds to changes in PMF, but strong Aer responses to oxygen are associated with redox changes in NADH dehydrogenase I.
Transcriptional regulation of the Pseudomonas aeruginosa type III secretion system
Authors: Yahr Timothy L. , Wolfgang Matthew C.
Published: September 2006

Type III secretion systems (T3SS) function by translocating effector proteins into eukaryotic host cells and are important for the virulence of many Gram‐negative bacterial pathogens. Although the secretion and translocation machineries are highly conserved between different species, each pathogen translocates a unique set of effectors that subvert normal host cell physiology to promote pathogenesis. The uniqueness of each pathogen is further reflected in the diversity of mechanisms used to regulate T3SS gene expression. Pseudomonas aeruginosa utilizes a complex set of signalling pathways to modulate T3SS expression in response to extracellular and intracellular cues. Whereas some pathways are dedicated solely to regulating the T3SS, others co‐ordinately regulate expression of the T3SS with multiple virulence functions on a global scale. Emerging regulatory themes include coupling of T3SS transcription with type III secretory activity, global regulatory control through modulation of cAMP biosynthesis, repression by a variety of stresses, involvement of multiple two component regulatory systems, and an inverse relationship between T3SS expression and multicellular behaviour. Factors controlling activation of T3SS expression likely contribute to the environmental survival of the organism and to the pathogenesis of acute P. aeruginosa infections. Conversely, active repression of the T3SS might contribute to the persistence of chronic infections.
Impact of a communication programme on female genital cutting in eastern Nigeria
Authors: Babalola Stella , Brasington Angela , Agbasimalo Ada , Helland Anna , Nwanguma Edith , Onah Nkechi
Published: September 2006

Objectives  This study describes a female genital cutting (FGC) elimination communication programme in Enugu State and assesses its impact in changing relevant knowledge, attitudes and behavioural intentions.

Methods  The FGC programme combined a community mobilization component with targeted advocacy and mass media activities. Data for assessing the impact of the programme derived from baseline and follow‐up surveys in three intervention local government areas (LGA) in Enugu State and three comparison LGAs in Ebonyi State. An ideation model of behaviour change guided the analyses of the impact of the programme on personal advocacy for FGC, perceived self‐efficacy to refuse pressure to perform FGC, perceived social support for FGC discontinuation, perceived benefits of FGC, perceived health complications of FGC and intention not to perform FGC on daughters. The analytical methods include comparing change in pertinent outcome variables from baseline to follow‐up in the two study states and using logistic regression on follow‐up data for the intervention state to assess the link between programme exposure and the relevant outcome indicators.

Results  The data show that while the pertinent ideational factors and the intention not to perform FGC either worsened or remained stagnant in Ebonyi State, they improved significantly in Enugu State. The logistic regression results show that programme exposure is associated with the expected improvements in all the pertinent indicators.

Conclusion  The multimedia communication programme has been effective in changing FGC‐related attitudes and promoting the intention not to perform FGC.
A double‐blind randomized controlled trial of antenatal mebendazole to reduce low birthweight in a hookworm‐endemic area of Peru
Authors: Larocque Renée , Casapia Martin , Gotuzzo Eduardo , MacLean J. Dick , Soto Julio C. , Rahme Elham , Gyorkos Theresa W.
Published: September 2006

Objective  To assess the effect on birthweight of antenatal mebendazole plus iron vs. placebo plus iron in a highly hookworm‐endemic area.

Methods  Double‐blind, randomized controlled trial set in rural and peri‐urban communities in the Peruvian Amazon region. A total of 1042 second trimester pregnant women between the ages of 18 and 44 years were recruited from April to November 2003, and followed to July 2004. Women were randomly assigned to receive either mebendazole (500 mg single dose) plus iron supplements (60 mg elemental iron daily) or placebo plus iron supplements. The primary outcome was mean infant birthweight and secondary measures included proportion of low birthweight babies and maternal anaemia.

Results  The prevalence of hookworm infection was 47.5%. There were no differences between intervention groups in mean birthweight (3104 g vs. 3090 g, P = 0.629), proportion of low birthweight (<2500 g; 8.1%vs. 8.7%, P = 0.755) or maternal anaemia in the third trimester [33.0% (158/479) vs. 32.3% (152/471), P = 0.815]. However, the proportion of very low birthweight (<1500 g) was significantly lower in the mebendazole group [0% (0/479) vs. 1.5% (7/471), P = 0.007].

Conclusions  This trial provides additional evidence for the use of anthelmintics, over and above iron supplementation, within antenatal care programmes in hookworm‐endemic areas. Benefits of de‐worming may be higher in countries not having an antenatal iron supplementation programme or where intensity of hookworm infections is higher.

Keywords mebendazole , pregnant women , hookworm , birthweight , anaemia , randomized‐controlled trial
Artesunate + amodiaquine and artesunate + sulphadoxine–pyrimethamine for treatment of uncomplicated malaria in Democratic Republic of Congo: a clinical trial with determination of sulphadoxine and pyrimethamine‐resistant haplotypes
Authors: Swarthout T. D. , Van Den Broek I. V. , Kayembe G. , Montgomery J. , Pota H. , Roper C.
Published: September 2006

We undertook a trial of artesunate + amodiaquine (AS + AQ) and artesunate + sulphadoxine–pyrimethamine (AS + SP) in 180 children of age 6–59 months with uncomplicated malaria in Democratic Republic of Congo. Children were randomly allocated to receive 3 days observed treatment of AS + AQ (n = 90) or 3 days of AS + SP (n = 90). Primary efficacy outcomes were 28‐day parasite recurrence rates, and recrudescence rates were adjusted by genotyping to distinguish new infection and recrudescence. In addition, we determined the prevalence of molecular markers of resistance to sulphadoxine and pyrimethamine. Day 28 parasite recurrence rates were 16.9% (14/83; 95% CI: 9.5–26.7) in the AS + AQ group and 34.6% (28/81; 95% CI: 24.3–46.0) in the AS + SP group (P = 0.009). After PCR correction, recrudescence rates were 6.7% (5/74; 95% CI: 2.2–15.1) for AS + AQ and 19.7% (13/66; 95% CI: 10.9–31.3) for AS + SP (P = 0.02). There was no significant difference between the two arms in time to parasite clearance, fever clearance and gametocyte clearance. Parasite genotyping showed high frequencies of dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) molecular SP‐resistance markers, with 57% of the samples showing more than three mutations linked to SP resistance, and 27% with triple‐dhfr/double‐dhps haplotype, confirming that SP treatment failure rates are likely to be high. AS + AQ had significantly higher efficacy than AS + SP. These results contributed to the subsequent change to AS + AQ as first‐line regimen in the country. Efforts to properly implement the new protocol and maintain adherence at acceptable levels should include health staff and patient sensitization. The 6.8% recrudescence rate indicates that AS + AQ should be monitored closely until a more effective artemisinin combination therapy regimen is needed and can be introduced.
Carbohydrate Profiles During Cotton Floral Bud (Square) Development
Authors: Tarpley L. , Sassenrath G. F.
Published: September 2006

Cotton (Gossypium hirsutum) flower's showy corolla expands rapidly, then senesces quickly. Efficient opening of corollas is important for self‐ and cross‐pollination, and indirectly lint yield. Carbohydrate relations are integral to bud water relations and growth, although they are not well understood. Soluble sugars and starch in developing floral buds and flowers of field‐grown cotton plants were analysed. Buds contained significantly more sugar than starch. Sucrose and its hydrolysis products strongly contributed to increased sugars during corolla expansion, and contributed −0.211 MPa to osmotic potential. Water concentration was constant throughout expansion at 860 g kg−1 FW, suggesting sucrose import and hydrolysis are coordinated with other drivers of expansion. Floral sugar content declined sharply during senescence (69 % in 24 h). Although remobilization to other organs could partially explain this decline, we suggest the possibility that most sugar is broken down via respiration, resulting in the production of metabolic water and the significant 7 % increase in floral water concentration during senescence. In summary, imported sucrose and its hydrolysis products increased rapidly during cotton floral bud growth, and supported bud expansion by decreasing the water potential of bud tissue.
Relationship between Carbon Isotope Discrimination, Ash Content and Grain Yield in Wheat in the Peninsular Zone of India
Authors: Misra S. C. , Randive R. , Rao V. S. , Sheshshayee M. S. , Serraj R. , Monneveux P.
Published: September 2006

Carbon isotope discrimination (Δ) and ash content (ma) have been proposed as indirect selection criteria for grain yield in wheat. The associations between Δ, ma and grain yield were found, however, to depend highly on the environmental conditions, the organ sampled and the time of sampling. In this study, carried out in the warm conditions of the Peninsular Zone of India, the relationship between Δ, ma and yield was studied in 30 bread and durum wheat cultivars under residual soil moisture stress (RSMS), post‐anthesis water stress (PAWS) and well‐watered (WW) conditions. Both Δ and ma were analysed in young seedlings (four‐leaf stage), leaves at anthesis and grain at maturity. Ash content was also evaluated in leaves at booting stage and maturity. Grain Δ was lower under PAWS and RSMS than under WW, while seedling and leaf Δ did not significantly differ among water regimes. Grain yield was positively correlated to grain Δ under PAWS and negatively correlated to grain ma under RSMS. A significant positive correlation was noted under RSMS and WW treatments between maLm and grain yield. Ash content in leaf at maturity consequently appears to be a useful indirect selection criterion in environments where Δ does not show any correlation with yield. The results highlight the potential of Δ and ma as indirect selection criteria for wheat yield in the conditions of the Peninsular Zone of India.
Bilateral Testicular Leydig Cells Tumour in a Donkey
Authors: Galofaro V , Rapisarda G , Ferrara G , Marino F
Published: September 2006

Contents

A rare case of a bilateral Leydig cells tumour located in the testis of a 15‐year‐old donkey slaughtered normally is presented. Histologically, the testicular tumour showed neoplastic Leydig cells arranged in solid growth as a pseudoadenomatous packet type. To our knowledge, this is the first bilateral Leydig cells tumour, a neoplasm never reported in the donkey.
Long‐lasting synaptic loss after repeated induction of LTD: independence to the means of LTD induction
Authors: Kamikubo Yuji , Egashira Yoshihiro , Tanaka Tsunehiro , Shinoda Yo , Tominaga‐Yoshino Keiko , Ogura Akihiko
Published: September 2006

Short‐ and long‐lasting synaptic plasticity is assumed to be the cellular basis of short‐ and long‐lasting memory, respectively. However, the cellular consequences leading to the long‐lasting synaptic plasticity, assumed to include the processes of synapse formation and elimination, remain unknown. Using hippocampal slices maintained stably in culture, we found previously that the repeated induction of long‐term potentiation (LTP) triggered a slowly developing long‐lasting enhancement in synaptic transmission strength accompanied by synapse formation, which was separate from LTP itself. We recently reported a phenomenon apparently of a mirror‐image effect. The repeated activations of metabotropic glutamate receptor (mGluR), which induces long‐term depression (LTD), triggered a long‐lasting reduction in synaptic strength accompanied by synapse elimination. To clarify whether the reported long‐lasting effect was specific to the drugs used previously and whether the effect was specific to mGluR‐mediated LTD, we exposed the cultured slices repeatedly to another Group I metabotropic glutamate receptor (mGluR) agonist, an N‐methyl‐d‐aspartate receptor agonist, and a Na+/K+‐pump inhibitor. All these treatments resulted in an equivalent long‐lasting synaptic reduction/elimination when repeated three times, indicating that the repeated LTD induction leads to synapse elimination. The independence of synapse elimination to the means of LTD induction suggests that the signals leading to short‐term plasticity and long‐term plasticity are independent. Detailed inspections in the representative case of mGluR activation revealed that the reduction in synaptic strength developed with a ∼1‐week delay from the decrease in the number of synaptic structures. This synapse elimination should be unique as it is activity‐dependent rather than inactivity‐dependent.
Altered PPARγ expression and activation after transient focal ischemia in rats
Authors: Victor N. A. , Wanderi E. W. , Gamboa J. , Zhao X. , Aronowski J. , Deininger K. , Lust W.D. , Landreth G. E. , Sundararajan S.
Published: September 2006

Stroke is a devastating disease with limited treatment options. Recently, we found that the peroxisome proliferator‐activated receptor‐γ (PPARγ) agonists troglitazone and pioglitazone reduce injury and inflammation in a rat model of transient cerebral ischemia. The mechanism of this protection is unclear, as these agents can act through PPAR‐γ activation or through PPAR‐γ‐independent mechanisms. Therefore, we examined PPAR‐γ expression, DNA binding and transcriptional activity following stroke. In addition, we used a PPAR‐γ antagonist, T0070907, to determine the role of PPAR‐γ during ischemia. Using immunohistochemical techniques and real‐time PCR, we found low levels of PPAR‐γ mRNA and PPAR‐γ immunoreactivity in nonischemic brain; however, PPAR‐γ expression dramatically increased in ischemic neurons, peaking 24 h following middle cerebral artery occlusion. Interestingly, we found that in both vehicle‐ and agonist‐treated brains, DNA binding was reduced in the ischemic hemisphere relative to the contralateral hemisphere. Expression of a PPAR‐γ target gene, lipoprotein lipase, was also reduced in ischemic relative to nonischemic brain. Both DNA binding and lipoprotein lipase expression were increased by the addition of the PPAR‐γ agonist rosiglitazone. Finally, we found that rosiglitazone‐mediated protection after stroke was reversed by the PPAR‐γ antagonist T0070907. Interestingly, infarction size was also increased by T0070907 in the absence of PPAR‐γ agonist, suggesting that endogenous PPAR‐γ ligands may mitigate the effects of cerebral ischemia.
The vasopressin‐induced excitation of hypoglossal and facial motoneurons in young rats is mediated by V1a but not V1b receptors, and is independent of intracellular calcium signalling
Authors: Reymond‐Marron I. , Tribollet E. , Raggenbass M.
Published: September 2006

As a hormone, vasopressin binds to three distinct receptors: V1a and V1b receptors, which induce phospholipase‐Cβ (PLCβ) activation and Ca2+ mobilization; and V2 receptors, which are coupled to adenylyl cyclase. V1a and V1b receptors are also present in neurons. In particular, hypoglossal (XII) and facial (VII) motoneurons are excited following vasopressin‐V1a receptor binding. The aim of the present study was double: (i) to determine whether V1b receptors contribute to the excitatory effect of vasopressin in XII and VII motoneurons; and (ii) to establish whether the action of vasopressin on motoneurons is mediated by Ca2+ signalling. Patch‐clamp recordings were performed in brainstem slices of young rats. Vasopressin depolarized the membrane or generated an inward current. By contrast, [1‐deamino‐4‐cyclohexylalanine] arginine vasopressin (d[Cha4]AVP), a V1b agonist, had no effect. The action of vasopressin was suppressed by Phaa‐d‐Tyr(Et)‐Phe‐Gln‐Asn‐Lys‐Pro‐Arg‐NH2, a V1a antagonist, but not by SSR149415, a V1b antagonist. Thus, the vasopressin‐induced excitation of brainstem motoneurons was exclusively mediated by V1a receptors. Light microscopic autoradiography failed to detect V1b binding sites in the facial nucleus. In motoneurons loaded with GTP‐γ‐S, a non‐hydrolysable analogue of GTP, the effect of vasopressin was suppressed, indicating that neuronal V1a receptors are G‐protein‐coupled. Intracellular Ca2+ chelation suppressed a Ca2+‐activated potassium current, but did not affect the vasopressin‐evoked current. H7 and GF109203, inhibitors of protein kinase C, were without effect on the vasopressin‐induced excitation. U73122 and D609, PLCβ inhibitors, were also without effect. Thus, excitation of brainstem motoneurons by V1a receptor activation is probably mediated by a second messenger distinct from that associated with peripheral V1a receptors.
CA3 NMDA receptors are crucial for rapid and automatic representation of context memory
Authors: Cravens Catherine J. , Vargas‐Pinto Noelia , Christian Kimberly M. , Nakazawa Kazu
Published: September 2006

It is argued that the hippocampus contributes to acquisition of context‐specific memory although neural mechanisms have not been clarified. To evaluate the role of CA3 in context‐specific memory, we developed one‐trial context discrimination tasks to test acquisition and retrieval of contextual memory in CA3 pyramidal cell‐restricted N‐methyl‐d‐aspartate (NMDA) receptor knockout mice. Mutants were unable to discriminate conditioned and no‐shock contexts 3 h after one‐trial avoidance training. These phenotypes were not evident 24 h after one‐trial training or 3 h after multi‐trial training. Following one‐trial contextual fear conditioning, mutants showed a selective deficit in context discrimination during a retention test 3 h after acquisition, although overall freezing levels were similar to those of the control mice. As in the avoidance task, this context discrimination impairment was not observed 24 h after initial conditioning. Interestingly, extending the post‐shock period to 3 min during the one‐trial fear conditioning task eliminated the discrimination deficit observed at the 3 h retention interval. These results suggest that: (i) impaired rapid context discrimination during the recall test is dependent on the duration of post‐shock period during conditioning; (ii) CA3 NMDA receptors are critically involved in rapid and automatic formation of a unified context memory representation from the sensory information; (iii) CA3 NMDA receptors support contextual pattern separation; (iv) fear memory to foot‐shock is acquired without CA3 NMDA receptors. It appears that rapid and automatic context memory representations from one‐time experience are mediated, at least in part, by CA3 NMDA receptors.
Effects of early life stress on adult male aggression and hypothalamic vasopressin and serotonin
Authors: Veenema Alexa H. , Blume Annegret , Niederle Daniela , Buwalda Bauke , Neumann Inga D.
Published: September 2006

Early life stress in humans enhances the risk for psychopathologies, including excessive aggression and violence. In rodents, maternal separation is a potent early life stressor inducing long‐lasting changes in emotional and neuroendocrine responsiveness to stress, associated with depression‐ and anxiety‐like symptoms. However, effects of maternal separation on adult male aggression and underlying neurobiological mechanisms remain unknown. Therefore, we investigated the effects of maternal separation on adult intermale aggression in Wistar rats and on hypothalamic arginine vasopressin (AVP) mRNA expression, and AVP and serotonin (5‐HT) immunoreactivity, as both AVP and 5‐HT have been implicated in stress‐coping and aggression. We showed that maternal separation induced depression‐like behaviour (increased immobility) and higher adrenocorticotropin hormone responses to an acute stressor (forced swimming). Intermale aggression (lateral threat, offensive upright and keep down) was significantly higher in maternally separated rats compared with control rats. AVP mRNA expression and AVP immunoreactivity were higher in the hypothalamic paraventricular and supraoptic nuclei upon resident‐intruder test exposure, whereas 5‐HT immunoreactivity was decreased in the anterior hypothalamus of maternally separated rats. Moreover, 5‐HT immunoreactivity in the anterior hypothalamus and supraoptic nucleus correlated negatively with aggression. These findings show that exposure to early life stress increases adult male aggression in an animal model of maternal separation. Furthermore, the maternal separation‐induced changes in hypothalamic AVP and 5‐HT systems may underlie these behavioural alterations.
Smoking and structural brain deficits: a volumetric MR investigation
Authors: Gallinat Jürgen , Meisenzahl Eva , Jacobsen Leslie K. , Kalus Peter , Bierbrauer Jeffrey , Kienast Thorsten , Witthaus Henning , Leopold Karolina , Seifert Frank , Schubert Florian , Staedtgen Mario
Published: September 2006

Growing evidence from animal studies indicates brain‐damaging properties of nicotine exposure. Investigations in humans found a wide range of functional cerebral effects of nicotine and cigarette smoking, but studies focusing on brain damage are sparse. In 22 smokers and 23 never‐smokers possible differences of the cerebral structures were investigated using magnetic resonance imaging and voxel‐based morphometry. Significantly smaller grey matter volume and lower grey matter density (P = 0.05, corrected) were observed in the frontal regions (anterior cingulate, prefrontal and orbitofrontal cortex), the occipital lobe and the temporal lobe including parahippocampal gyrus, in smokers than in never‐smokers. Group differences of either grey matter volume or grey matter density were also found in the thalamus, cerebellum and substantia nigra, among other regions. Smokers did not show greater volumes than never‐smokers in any cerebral region. Magnitude of lifetime exposure to tobacco smoke (pack‐years) was inversely correlated with volume of frontal and temporal lobes and cerebellum (P = 0.001, uncorrected). The data indicate structural deficits of several cortical and subcortical regions in smokers relative to never‐smokers. The topographic profile of the group differences show some similarities to brain networks known to mediate drug reinforcement, attention and working memory processing. The present findings may explain in part the frequently reported cognitive dysfunctions in chronic cigarette consumers.
Localization of heterotypic gap junctions composed of connexin45 and connexin36 in the rod pathway of the mouse retina
Authors: Dedek Karin , Schultz Konrad , Pieper Mario , Dirks Petra , Maxeiner Stephan , Willecke Klaus , Weiler Reto , Janssen‐Bienhold Ulrike
Published: September 2006

The primary rod pathway in mammals contains gap junctions between AII amacrine cells and ON cone bipolar cells which relay the rod signal into the cone pathway under scotopic conditions. Two gap junctional proteins, connexin36 (Cx36) and connexin45 (Cx45), appear to play a pivotal role in this pathway because lack of either protein leads to an impairment of visual transmission under scotopic conditions. To investigate whether these connexins form heterotypic gap junctions between ON cone bipolar and AII amacrine cells, we used newly developed Cx45 antibodies and studied the cellular and subcellular distribution of this protein in the mouse retina. Specificity of the Cx45 antibodies was determined, among others, by Western blot and immunostaining of mouse heart, where Cx45 is abundantly expressed. In mouse retina, Cx45 immunosignals were detected in both plexiform layers and the ganglion cell layer. Double staining for Cx45 and Cx36 revealed a partial overlap in the punctate patterns in the ON sublamina of the inner plexiform layer of the retina. We quantified the distributions of these two connexins in the ON sublamina, and detected 30% of the Cx45 signals to be co‐localized with or in close apposition to Cx36 signals. Combining immunostaining and intracellular dye injection revealed an overlap or tight association of Cx36 and Cx45 signals on the terminals of injected AII amacrine and two types of ON cone bipolar cells. Our results provide direct evidence for heterotypic gap junctions composed of Cx36 and Cx45 between AII amacrine and certain types of ON cone bipolar cells.
ERK1/2 but not p38 MAP kinase is essential for the long‐term depression in mouse cerebellar slices
Authors: Ito‐Ishida Aya , Kakegawa Wataru , Yuzaki Michisuke
Published: September 2006

Mitogen‐activated protein kinase (MAPK) cascade is essential for synaptic plasticity and learning. In the hippocampus, three different MAPK subfamilies, extracellular signal‐regulated kinase 1/2 (ERK1/2), p38 MAPK and c‐Jun NH2‐terminal protein kinase (JNK), selectively regulate activity‐dependent glutamate receptor trafficking during long‐term potentiation (LTP), long‐term depression (LTD), and depotentiation after LTP, respectively. Although LTP and LTD at cerebellar parallel fibre (PF)–Purkinje cell synapses are thought to be controlled by glutamate receptor trafficking, the involvement of MAPK subfamilies has not been systemically studied in cerebellar slice preparations. To clarify the role of the MAPK cascade in cerebellar LTD, we performed biochemical and electrophysiological analyses using ICR mouse cerebellar slices. Immunoblot analyses using phosphorylation‐specific antibodies for MAPKs revealed that among the three MAPKs, ERK1/2 was specifically activated by phorbol ester, which could induce LTD in cerebellar slices. In addition, U0126, a specific inhibitor of the MAPK kinase‐ERK1/2 pathway, abrogated the induction of LTD in cerebellar slices, whereas SB203580 and SP600125, specific inhibitors of p38 MAPK and JNK, respectively, had no effect. Although metabotropic glutamate receptor 1 (mGluR1) has been suggested as a possible downstream target of ERK1/2 in cell‐culture preparations, mGluR1‐activated slow excitatory postsynaptic currents (EPSCs) were not affected by U0126 treatment in slices. These findings indicate that unlike hippocampal LTD mediated by p38 MAPK, glutamate receptor trafficking during cerebellar LTD was regulated by a distinct mechanism involving ERK1/2 in slice preparations.
A double dissociation of dorsal and ventral hippocampal function on a learning and memory task mediated by the dorso‐lateral striatum
Authors: McDonald Robert J. , Jones Jana , Richards Blake , Hong Nancy S.
Published: September 2006

The objectives of this research were to further delineate the neural circuits subserving proposed memory‐based behavioural subsystems in the hippocampal formation. These studies were guided by anatomical evidence showing a topographical organization of the hippocampal formation. Briefly, perpendicular to the medial/lateral entorhinal cortex division there is a second system of parallel circuits that separates the dorsal and ventral hippocampus. Recent work from this laboratory has provided evidence that the hippocampus incidentally encodes a context‐specific inhibitory association during acquisition of a visual discrimination task. One question that emerges from this dataset is whether the dorsal or ventral hippocampus makes a unique contribution to this newly described function. Rats with neurotoxic lesions of the dorsal or ventral hippocampus were assessed on the acquisition of the visual discrimination task. Following asymptotic performance they were given reversal training in either the same or a different context from the original training. The results showed that the context‐specific inhibition effect is mediated by a circuit that includes the ventral but not the dorsal hippocampus. Results from a control procedure showed that rats with either dorso‐lateral striatum damage or dorsal hippocampal lesions were impaired on a tactile/spatial discrimination. Taken together, the results represent a double dissociation of learning and memory function between the ventral and dorsal hippocampus. The formation of an incidental inhibitory association was dependent on ventral but not dorsal hippocampal circuitry, and the opposite dependence was found for the spatial component of a tactile/spatial discrimination.
Retinotopic distribution of chromatic responses in human primary visual cortex
Authors: Vanni S. , Henriksson L. , Viikari M. , James A. C.
Published: September 2006

In non‐human primates at least three anatomically and functionally distinct channels convey signals from the retina to the primary visual cortex (V1). Two of these channels, the parvocellular and the koniocellular, are sensitive to chromatic contrasts and form the basis of color vision. In humans, common phylogenetic history with other primates and psychophysical experiments suggest identical retinocortical mechanisms but separate evaluation of the distinct anatomical channels has been difficult because signals are already combined in V1. We studied the spatial distribution of activation to chromatic stimuli along the two opponent chromatic axes in human V1 with multifocal functional magnetic resonance imaging. The signal strength was quantified from three experiments with stimuli up to 20° eccentricity. The hypothesis was that, although the parvo‐ and koniocellular signals are mixed in V1, distinct distributions of signal strength would be evident. We found that whereas different conditions activated the same areas of cortex, indicating that they have identical magnification factors, the responses to red/green stimulation were stronger close to the fovea whereas the blue/yellow responses were much less diminished with increasing eccentricity. Both chromatic axes showed saturating contrast response functions. Our measure directly from human V1 is in line with earlier psychophysical studies suggesting relatively stronger parvocellular channel representation close to the fovea, and more uniform distribution of the koniocellular and achromatic channels. In addition, our study presents a way to rapidly quantify retinotopic signal transmission in distinct retinocortical pathways of individual subjects.
Dendritic excitability and calcium signalling in the mitral cell distal glomerular tuft
Authors: Zhou Zhishang , Xiong Wenhui , Zeng Shaoqun , Xia Andong , Shepherd Gordon M. , Greer Charles A. , Chen Wei R.
Published: September 2006

The processing of odour information starts at the level of the olfactory glomerulus, where the mitral cell distal dendritic tuft not only receives olfactory nerve sensory input but also generates dendrodendritic output to form complicated glomerular synaptic circuits. Analysing the membrane properties and calcium signalling mechanisms in these tiny dendritic branches is crucial for understanding how the glomerular tuft transmits and processes olfactory signals. With the use of two‐photon Ca2+ imaging in rat olfactory bulb slices, we found that these distal dendritic branches displayed a significantly larger Ca2+ signal than the soma and primary dendrite trunk. A back‐propagating action potential was able to trigger a Ca2+ increase throughout the entire glomerular tuft, indicative of the presence of voltage‐gated Ca2+ conductances in all branches at different levels of ramification. In response to a train of action potentials evoked at 60 Hz from the soma, the tuft Ca2+ signal increased linearly with the number of action potentials, suggesting that these glomerular branches were able to support repetitive penetration of Na+ action potentials. When a strong olfactory nerve excitatory input was paired with an inhibition from mitral cell basal dendrites, a small spike‐like fast prepotential was revealed at both the soma and distal primary dendrite trunk. Corresponding to this fast prepotential was a Ca2+ increase confined locally within the glomerular tuft. In summary, the mitral cell distal dendritic tuft possesses both Na+ and Ca2+ voltage‐dependent conductances which can mediate glomerular Ca2+ responsiveness critical for dendrodendritic output and synaptic plasticity.
Unexpected diversity in populations of the many‐celled magnetotactic prokaryote
Authors: Simmons Sheri L. , Edwards Katrina J.
Published: September 2006

The many‐celled magnetotactic prokaryote (MMP) is an uncultivated, highly motile aggregate of 10–30 cells containing numerous chains of greigite (Fe3S4) magnetosomes. It is unique to marine environments and is abundant in slightly sulfidic sediments of the Little Sippewissett salt marsh (Falmouth, MA). We sequenced 16s rDNA genes from a natural population of MMP and found five lineages separated by at least 5% sequence divergence. Fluorescent in situ hybridization probes for three of these lineages showed significant variation in their relative abundances across a seasonal cycle in marsh productivity. The MMP should therefore be considered a separate genus in the δ‐proteobacteria rather than a single species as previously thought. All cells in each aggregate express identical SSU rRNAs, suggesting that the aggregates are composed of a single MMP phylotype. This observation supports a model of the MMP as comprised of clonal cells which reproduce by binary fission of the aggregate.
Molecular characterization of Vibrio harveyi bacteriophages isolated from aquaculture environments along the coast of India
Authors: Shivu Mockshanath M. , Rajeeva Bettada C. , Girisha Shivani K. , Karunasagar Indrani , Krohne Georg , Karunasagar Iddya
Published: September 2006

Seven bacteriophages specific to Vibrio harveyi, the causative agent of luminous vibriosis in shrimp, were isolated from coastal aquaculture systems like shrimp farms, hatcheries and tidal creeks along the east and west coast of India. All the seven phages were found to have the typical head and tail morphology with double‐stranded DNA as genetic material. Morphologically, six phages were grouped under family Siphoviridae and one under Myoviridae. These phages were further characterized with respect to host range, morphology and structural proteins. Genomic fingerprinting was carried out using restriction fragment length polymorphism (RFLP) and randomly amplified polymorphic DNA (RAPD). Major capsid proteins of all the phages detected by SDS‐PAGE were distinct from one another. All the phages were found to be highly lytic for V. harveyi and had different lytic spectrum for the large number of isolates tested. Six of the seven phages isolated had a broad lytic spectrum and could be potential candidates for biocontrol of V. harveyi in aquaculture systems.
Bank Loan Officers' Perceptions of Business Owners: The Role of Gender
Authors: Wilson Fiona , Carter Sara , Tagg Stephen , Shaw Eleanor , Lam Wing
Published: September 2006

There is a widely held belief that banks may be discriminating against female business owners. This study was designed to explore the perceptions held by bank loan officers of male and female business owners, using Bourdieu's theory of practice and Kelly's personal construct methodology. The research literature might lead to an expectation that the characteristics of the business owners would be relatively homogenous but that men and women business owners would be construed differently (for example women might be seen to lack drive). However, the results demonstrate heterogeneity in the constructs held by bank loan officers, and a particular concern with the character of the business owner. Significant gender differences were observed in only 20 of the 325 constructs elicited from 35 bank loan officers. Female bank loan officers were as likely as male bank loan officers to draw gender distinctions between business owners. Detailed multivariate analyses confirmed no evidence of systematic gender differences in the constructs held by bank loan officers of business owners.