bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential detection of dual traps improves the spatial resolution of optical tweezers
Authors: Moffitt Jeffrey R. , Chemla Yann R. , Izhaky David , Bustamante Carlos
Published: June 2006

The drive toward more sensitive single-molecule manipulation techniques has led to the recent development of optical tweezers capable of resolving the motions of biological systems at the subnanometer level, approaching the fundamental limit set by Brownian fluctuations. One successful approach has been the dual-trap optical tweezers, in which the system of study is held at both ends by microspheres in two separate optical traps. We present here a theoretical description of the Brownian limit on the spatial resolution of such systems and verify these predictions by direct measurement in a Brownian noise-limited dual-trap optical tweezers. We find that by detecting the positions of both trapped microspheres, correlations in their motions can be exploited to maximize the resolving power of the instrument. Remarkably, we show that the spatial resolution of dual optical traps with dual-trap detection is always superior to that of more traditional, single-trap designs, despite the added Brownian noise of the second trapped microsphere.
Myc
is a Notch1 transcriptional target and a requisite for Notch1-induced mammary tumorigenesis in mice
Authors: Klinakis Apostolos , Szabolcs Matthias , Politi Katerina , Kiaris Hippokratis , Artavanis-Tsakonas Spyros , Efstratiadis Argiris
Published: June 2006

To explore the potential involvement of aberrant Notch1 signaling in breast cancer pathogenesis, we have used a transgenic mouse model. In these animals, mouse mammary tumor virus LTR-driven expression of the constitutively active intracellular domain of the Notch1 receptor (N1
IC
) causes development of lactation-dependent mammary tumors that regress upon gland involution but progress to nonregressing, invasive adenocarcinomas in subsequent pregnancies. Up-regulation of
Myc
in these tumors prompted a genetic investigation of a potential Notch1/Myc functional relationship in breast carcinogenesis. Conditional ablation of
Myc
in the mammary epithelium prevented the induction of regressing N1
IC
neoplasms and also reduced the incidence of nonregressing carcinomas, which developed with significantly increased latency. Molecular analyses revealed that both the mouse and human
Myc
genes are direct transcriptional targets of N1
IC
acting through its downstream Cbf1 transcriptional effector. Consistent with this mechanistic link, Notch1 and Myc expression is positively correlated by immunostaining in 38% of examined human breast carcinomas.
Mutation of the
atrophin2
gene in the zebrafish disrupts signaling by fibroblast growth factor during development of the inner ear
Authors: Asai Yukako , Chan Dylan K. , Starr Catherine J. , Kappler James A. , Kollmar Richard , Hudspeth A. J.
Published: June 2006

The development of the vertebrate inner ear depends on the precise expression of fibroblast growth factors. In a mutagenesis screen for zebrafish with abnormalities of inner-ear development and behavior, we isolated a mutant line,
ru622
, whose phenotypic characteristics resembled those of null mutants for the gene encoding fibroblast growth factor 8 (Fgf8): an inconsistent startle response, circular swimming, fused otoliths, and abnormal semicircular canals. Positional cloning disclosed that the mutant gene encodes the transcriptional corepressor Atrophin2. Both the Fgf8 protein and zebrafish “similar expression to
fgf
genes” protein (Sef), an antagonist of fibroblast growth factors induced by Fgf8 itself, were found to be overexpressed in
ru622
mutants. We therefore hypothesized that an excess of Sef eliminates Fgf8 signals and produces an
fgf8
null phenotype in
ru622
mutants. In support of this idea, we could rescue larvae whose
atrophin2
expression had been diminished with morpholinos by reducing the expression of Sef as well. We propose that Atrophin2 plays a role in the feedback regulation of Fgf8 signaling. When mutation of the
atrophin2
gene results in the overexpression of both Fgf8 and Sef, the excessive Sef inhibits Fgf8 signaling. The resultant imbalance of Fgf8 and Sef signals then underlies the abnormal aural development observed in
ru622
.
Differential synergy of Notch and T cell receptor signaling determines αβ versus γδ lineage fate
Authors: Garbe Annette I. , Krueger Andreas , Gounari Fotini , Zúñiga-Pflücker Juan Carlos , von Boehmer Harald
Published: June 2006

Thymic precursors expressing the pre–T cell receptor (TCR), the γδTCR, or the αβTCR can all enter the CD4+8+ αβ lineage, albeit with different efficacy. Here it is shown that proliferation and differentiation of precursors with the different TCRs into αβ lineage cells require Notch signaling at the DN3 stage of thymic development. At the DN4 stage, Notch signaling still significantly contributes to the generation of αβ T cells. In particular, in αβ lineage commitment, the pre-TCR synergizes more efficiently with Notch signals than the other two TCRs, whereas γδTCR-expressing cells can survive and expand in the absence of Notch signals, even though Notch signaling enhances their proliferation. These observations suggest a new model of αβ versus γδ lineage choice in which lineage fate is determined by the extent of synergy between TCR and Notch signaling and in which the evolutionarily recent advent of the cell-autonomously signaling pre-TCR increased the efficacy of αβ T cell generation.
Yersinia pseudotuberculosis disseminates directly from a replicating bacterial pool in the intestine
Authors: Barnes Penelope D. , Bergman Molly A. , Mecsas Joan , Isberg Ralph R.
Published: June 2006

Dissemination of Yersinia pseudotuberculosis within mice after oral inoculation was analyzed. Y. pseudotuberculosis translocated to organs such as the liver and spleen shortly after oral inoculation, but was quickly cleared. In contrast, a second temporally distinct bacterial translocation event resulted in successful hepatosplenic replication of the bacteria. Replicating pools of bacteria could be established in these organs in mouse mutants that lacked Peyer's patches. These animals frequently had sterile mesenteric lymph nodes, a finding consistent with translocation taking place independently of regional lymph node colonization. In further contradiction to accepted models for dissemination of enteropathogens, clonal analysis revealed that bacteria causing disease in the spleen and liver of C57BL/6J mice were derived from populations located outside the intestinal lymph nodes. Replication of bacteria in the intestine before translocation appeared critical for dissemination, as transient selective suppression by streptomycin of bacterial growth in the intestine delayed dissemination of Y. pseudotuberculosis. These results collectively indicate that hepatosplenic colonization appears intimately connected with the ability of Y. pseudotuberculosis to successfully establish replication in the intestinal lumen and does not result from ordered spread leading from the intestine to regional lymph nodes before dissemination.
Photosensitivity of 20GeO2 : 80SiO2hydrogen-loaded and non-hydrogen-loaded thin films
Authors: Rajni  , Pita K , Ho Charles K F , Swee Chuan Tjin , Chan Hin Kam
Published: June 2006

Photosensitive materials offer great potential for passive and active optical devices in communication, data manipulation and storage. We prepared photosensitive germanosilicate (20GeO2 : 80SiO2) inorganic thin films by the sol–gel method. These films were annealed at various temperatures in the range of 700–900 °C. The films annealed at 900 °C were found to be fully densified and were porous when annealed below 900 °C. The UV KrF laser (248 nm) has been used to induce refractive index change (Δn). We have studied the Fourier transform infra-red (FTIR) spectroscopy and the refractive index changes of the hydrogen-loaded and as-deposited samples before and after UV illumination. For the porous samples, the −OH absorption band around 3400 cm−1increases with hydrogen-loading and decreases with UV radiation. The hydrogen-loading has induced absorption around 500–600 cm−1for all our samples (both porous and dense samples) and that indicates the formation of Si–H bonds. The Si–H absorption bands disappeared after UV illumination. We observed the high Δnof about 0.0094 for the as-deposited dense film annealed at 900 °C and value enhanced to 0.0096 after H2-loading. For our samples, the large induced refractive index change is explained in terms of the formation of the oxygen related defects upon UV exposure. This is related to the induced absorption band around 620–740 cm−1in the FTIR spectra.
The effect of age on referral to and use of specialist palliative care services in adult cancer patients: a systematic review
Authors: Burt Jenni , Raine Rosalind
Published: June 2006

Objective: to investigate variations in the use of specialist palliative care (SPC) services for adult cancer patients, in relation to age.

Design: systematic review of studies examining use of or referral to SPC services in adult cancer patients.

Search strategy and selection criteria: six electronic databases (Medline, Embase, Web of Science, HMIC, SIGLE and AgeInfo) were searched for studies published between 1966 and March 2005, and references in the articles identified were also examined. Inclusion criteria were all studies which provided data on age in relation to use of or referral to SPC. Two reviewers independently selected studies, extracted data and assessed methodological quality according to defined criteria.

Main outcome measures: use of or referral to SPC services, determined from all sources of report (patient, informal carer, health care professional, health care records).

Results: 14 studies were identified. All reported a statistically significant lower use of SPC among older cancer patients (65 and above or older) at a univariate level [crude odds ratios ranged from 0.33 (0.15–0.72) to 0.82 (0.80–0.82)]. However, there were important methodological weaknesses in all of the studies identified; most crucially, studies failed to consider variations in use in relation to need for SPC.

Conclusions: there is some evidence that older people are less likely to be referred to, or to use, SPC. These findings require confirmation in studies using prospectively collected data which control for patient’s need for SPC.
Animal‐Assisted Activity at A. Meyer Children′s Hospital: A Pilot Study
Authors: Caprilli Simona , Messeri Andrea
Published: June 2006

The authors systematically studied the introduction of animal‐assisted activity into a children′s hospital in Italy. This pilot study examined the reactions of children, their parents and the hospital staff and the hospital‐wide infection rate before and after the introduction of animals. The SAM (self‐assessment manikin), three behavioral scales, analysis of children′s graphic productions, a parent questionnaire and a staff questionnaire were used to evaluate the effectiveness of the intervention. The children′s participation was calculated. The analysis of the hospital infection rate was completed independently by the Hospital Infections Committee. The authors found that the presence of infections in the wards did not increase and the number of children at the meetings with pets in the wards was high (138 children). The study also found that the presence of animals produced some beneficial effects on children: a better perception of the environment and a good interaction with dogs. All parents were in favor of pets in the hospital, and 94% thought that this activity could benefit the child, as did the medical staff, although the staff needed more information about safety. The introduction of pets into the pediatric wards in an Italian children′s hospital was a positive event because of the participation of hospitalized patients, the satisfaction expressed by both parents and medical staff, and the fact that the hospital infection rate did not change and no new infections developed after the introduction of dogs.
The State of the Art of Traditional Arab Herbal Medicine in the Eastern Region of the Mediterranean: A Review
Authors: Azaizeh Hassan , Saad Bashar , Khalil Khalid , Said Omar
Published: June 2006

Historical and current studies indicate that the Eastern region of the Mediterranean has been distinguished from other regions by a rich inventory of complementary alternative medicine (CAM), in particular herbal medicine. Data collected from several surveys and studies indicate that there is a flourishing and well‐developed trade of herbs. These surveys also reveal that 200–250 herbs are used in treating human diseases and are sold or traded in market places in the Mediterranean region or internationally. In addition, some of these herbs are rare or even endangered species. In regard to the status of the know‐how of herbalists, unfortunately, herbal medicine in our region is mostly prescribed by ethnopharmacologists symptomatically—based on signs and symptoms alone, rather than as a result of a full understanding of the underlying disease. In some cases, herbs used today may not even correspond to the plants described originally in the old literature, as the former are cultivated from herbs that went through different breeding procedures throughout several centuries. This article presents a systematic review of both the state of the art of traditional Arab herbal medicine and the status of the know‐how of Arab herbalists.
Julia's Gift: The Social Life of Scores,c.1830
Authors: Davies James
Published: June 2006

This article addresses a subject long overlooked by students and scholarship – the musical annual. Emerging in London in 1829, this was an enormously popular brand of commercial publication conventionally produced for holiday sales. One particular copy – given as a present to an 11-year-old girl that year – proves a useful starting point from which to interrogate these items as a whole. Several avenues of inquiry suggest themselves: ideas of gift exchange and commerce, histories of the role such music played in adolescent upbringing and pianism, accounts of period notions of ‘the fair sex’, and considerations of the relation between authenticity and deception in annual poetics. In the end, the author attempts to recuperate some enigma or aura for the musical score -not by appealing to some allusive or metaphysical ‘work-content’ immanent in the text, but by exploring the sense in which these volumes were and are souvenirs – perhaps remote from traditional intellectual concerns, but redolent of a bygone and elusive ‘social life’.
Musicians on Television: Visible, Audible and Ignored
Authors: Negus Keith
Published: June 2006

This article focuses on the prominent anxieties generated by television broadcasts of musicians from the 1930s onwards. It explores three specific issues: first, a concern that television images of performing musicians are detrimental to the experience of music; second, negative judgments about the consequences of television sound quality; and, third, fears that musical value is undermined by the distracted character of television reception. Focusing on these particular points, the article also raises a series of more profound questions about how various strategies of looking and listening influence our understanding of music.
A systems view of haloarchaeal strategies to withstand stress from transition metals
Authors: Kaur Amardeep , Pan Min , Meislin Megan , Facciotti Marc T. , El-Gewely Raafat , Baliga Nitin S.
Published: June 2006

Given that transition metals are essential cofactors in central biological processes, misallocation of the wrong metal ion to a metalloprotein can have resounding and often detrimental effects on diverse aspects of cellular physiology. Therefore, in an attempt to characterize unique and shared responses to chemically similar metals, we have reconstructed physiological behaviors of Halobacterium NRC-1, an archaeal halophile, in sublethal levels of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II). Over 20% of all genes responded transiently within minutes of exposure to Fe(II), perhaps reflecting immediate large-scale physiological adjustments to maintain homeostasis. At steady state, each transition metal induced growth arrest, attempts to minimize oxidative stress, toxic ion scavenging, increased protein turnover and DNA repair, and modulation of active ion transport. While several of these constitute generalized stress responses, up-regulation of active efflux of Co(II), Ni(II), Cu(II), and Zn(II), down-regulation of Mn(II) uptake and up-regulation of Fe(II) chelation, confer resistance to the respective metals. We have synthesized all of these discoveries into a unified systems-level model to provide an integrated perspective of responses to six transition metals with emphasis on experimentally verified regulatory mechanisms. Finally, through comparisons across global transcriptional responses to different metals, we provide insights into putative in vivo metal selectivity of metalloregulatory proteins and demonstrate that a systems approach can help rapidly unravel novel metabolic potential and regulatory programs of poorly studied organisms.
Suz12 binds to silenced regions of the genome in a cell-type-specific manner
Authors: Squazzo Sharon L. , O’Geen Henriette , Komashko Vitalina M. , Krig Sheryl R. , Jin Victor X. , Jang Sung-wook , Margueron Raphael , Reinberg Danny , Green Roland , Farnham Peggy J.
Published: June 2006

Suz12 is a component of the Polycomb group complexes 2, 3, and 4 (PRC 2/3/4). These complexes are critical for proper embryonic development, but very few target genes have been identified in either mouse or human cells. Using a variety of ChIP-chip approaches, we have identified a large set of Suz12 target genes in five different human and mouse cell lines. Interestingly, we found that Suz12 target promoters are cell type specific, with transcription factors and homeobox proteins predominating in embryonal cells and glycoproteins and immunoglobulin-related proteins predominating in adult tumors. We have also characterized the localization of other components of the PRC complex with Suz12 and investigated the overall relationship between Suz12 binding and markers of active versus inactive chromatin, using both promoter arrays and custom tiling arrays. Surprisingly, we find that the PRC complexes can be localized to discrete binding sites or spread through large regions of the mouse and human genomes. Finally, we have shown that some Suz12 target genes are bound by OCT4 in embryonal cells and suggest that OCT4 maintains stem cell self-renewal, in part, by recruiting PRC complexes to certain genes that promote differentiation.
Silencing the Flavonoid Pathway in Medicago truncatula Inhibits Root Nodule Formation and Prevents Auxin Transport Regulation by Rhizobia
Authors: Wasson Anton P. , Pellerone Flavia I. , Mathesius Ulrike
Published: June 2006

Legumes form symbioses with rhizobia, which initiate the development of a new plant organ, the nodule. Flavonoids have long been hypothesized to regulate nodule development through their action as auxin transport inhibitors, but genetic proof has been missing. To test this hypothesis, we used RNA interference to silence chalcone synthase (CHS), the enzyme that catalyzes the first committed step of the flavonoid pathway, in Medicago truncatula. Agrobacterium rhizogenes transformation was used to create hairy roots that showed strongly reduced CHS transcript levels and reduced levels of flavonoids in silenced roots. Flavonoid-deficient roots were unable to initiate nodules, even though normal root hair curling was observed. Nodule formation and flavonoid accumulation could be rescued by supplementation of plants with the precursor flavonoids naringenin and liquiritigenin. The flavonoid-deficient roots showed increased auxin transport compared with control roots. Inoculation with rhizobia reduced auxin transport in control roots after 24 h, similar to the action of the auxin transport inhibitor N-(1-naphthyl)phthalamic acid (NPA). Rhizobia were unable to reduce auxin transport in flavonoid-deficient roots, even though NPA inhibited auxin transport. Our results present genetic evidence that root flavonoids are necessary for nodule initiation in M. truncatula and suggest that they act as auxin transport regulators.
Cooperative α‐helix unfolding in a protein–DNA complex from hydrogen–deuterium exchange
Authors: Salinas Roberto K. , Diercks Tammo , Kaptein Robert , Boelens Rolf
Published: June 2006

We present experimental evidence for a cooperative unfolding transition of an α‐helix in the lac repressor headpiece bound to a symmetric variant of the lac operator, as inferred from hydrogen–deuterium (H–D) exchange experiments monitored by NMR spectroscopy. In the EX1 limit, observed exchange rates become pH‐independent and exclusively sensitive to local structure fluctuations that expose the amide proton HN to exchange. Close to this regime, we measured decay rates of individual backbone HN signals in D2O, and of their mutual HN–HN NOE by time‐resolved two‐dimensional (2D) NMR experiments. The data revealed correlated exchange at the center of the lac headpiece recognition helix, Val20–Val23, and suggested that the correlation breaks down at Val24, at the C terminus of the helix. A lower degree of correlation was observed for the exchange of Val9 and Ala10 at the center of helix 1, while no correlation was observed for Val38 and Glu39 at the center of helix 3. We conclude that HN exchange in the recognition helix and, to some extent, in helix 1 is a cooperative event involving the unfolding of these helices, whereas the HN exchange in helix 3 is dominated by random local structure fluctuations.
Structural analysis of an “open” form of PBP1B from Streptococcus pneumoniae
Authors: Lovering Andrew L. , De Castro Liza , Lim Daniel , Strynadka Natalie C.J.
Published: June 2006

The class A PBP1b from Streptococcus pneumoniae is responsible for glycosyltransferase and transpeptidase (TP) reactions, forming the peptidoglycan of the bacterial cell wall. The enzyme has been produced in a stable, soluble form and undergoes time‐dependent proteolysis to leave an intact TP domain. Crystals of this TP domain were obtained, diffracting to 2.2 Å resolution, and the structure was solved by using molecular replacement. Analysis of the structure revealed an “open” active site, with important conformational differences to the previously determined “closed” apoenzyme. The active‐site nucleophile, Ser460, is in an orientation that allows for acylation by β‐lactams. Consistent with the productive conformation of the conserved active‐site catalytic residues, adjacent loops show only minor deviation from those of known acyl‐enzyme structures. These findings are discussed in the context of enzyme functionality and the possible conformational sampling of PBP1b between active and inactive states.
Identification of cognate ligands for the Escherichia coli phnD protein product and engineering of a reagentless fluorescent biosensor for phosphonates
Authors: Rizk Shahir S. , Cuneo Matthew J. , Hellinga Homme W.
Published: June 2006

The Escherichia coli phnD gene is hypothesized to code for the periplasmic binding component of a phosphonate uptake system. Here we report the characterization of the phosphonate‐binding properties of the phnD protein product. We find that PhnD exhibits high affinity for 2‐aminoethylphosphonate (5 nM), the most commonly occurring natural phosphonate produced by lower eukaryotes, but also binds several other phosphonates with micromolar affinities. A significant number of man‐made phosphonates, such as insecticides and chemical warfare agents, are chemical threats and environmental pollutants. Consequently, there is an interest in developing methods for the detection and bioremediation of phosphonates. Bacterial periplasmic‐binding proteins have been utilized for developing reagentless biosensors that report analytes by coupling ligand‐binding events to changes in the emission properties of a covalently conjugated environmentally‐sensitive fluorophore. Several PhnD conjugates described here show large changes in fluorescence upon binding to methylphosphonate (MP), with two conjugates exhibiting up to 50% decrease in emission intensity. Since MP is the final degradation product of many nerve agents, these PhnD conjugates can function as components in a biosensor system for chemical warfare agents.
Dissociation of intermolecular disulfide bonds in P22 tailspike protein intermediates in the presence of SDS
Authors: Kim Junghwa , Robinson Anne Skaja
Published: June 2006

Each chain of the native trimeric P22 tailspike protein has eight cysteines that are reduced and buried in its hydrophobic core. However, disulfide bonds have been observed in the folding pathway and they are believed to play a critical role in the registration of the three chains. Interestingly, in the presence of sodium dodecyl sulfate (SDS) only monomeric chains, rather than disulfide‐linked oligomers, have been observed from a mixture of folding intermediates. Here we show that when the oligomeric folding intermediates were separated from the monomer by native gel electrophoresis, the reduction of intermolecular disulfide bonds did not occur in the subsequent second‐dimension SDS–gel electrophoresis. This result suggests that when tailspike monomer is present in free solution with SDS, the partially unfolded tailspike monomer can facilitate the reduction of disulfide bonds in the tailspike oligomers.
Fluorescence resonance energy transfer study of subunit exchange in human lens crystallins and congenital cataract crystallin mutants
Authors: Liang Jack J. , Liu Bing‐Fen
Published: June 2006

Lens α‐crystallin is an oligomeric protein with a molecular mass of 500–1000 kDa and a polydispersed assembly. It consists of two types of subunits, αA and αB, each with a molecular mass of 20 kDa. The subunits also form homo‐oligomers in some other tissues and in vitro. Their quaternary structures, which are dynamic and characterized by subunit exchange, have been studied by many techniques, including fluorescence resonance energy transfer (FRET) and mass spectrometry analysis. The proposed mechanism of subunit exchange has been either by dissociation/association of monomeric subunits or by rapid equilibrium between oligomers and suboligomers. To explore the nature of subunit exchange further, we performed additional FRET measurements and analyses using a fluorescent dye‐labeled W9F αA‐crystallin as the acceptor probe and Trp in other crystallins (wild‐type and R116C αA, wild‐type and R120G αB, wild‐type and Q155* βB2) as the donor probe and calculated the transfer efficiency, Förster distance, and average distance between two probes. The results indicate only slight decreased efficiency and increased distance between two probes for the R116C αA and R120G αB mutations despite conformational changes.
Reproductive biology of the milk shark Rhizoprionodon acutus and the bigeye houndshark Iago omanensis in the coastal waters of Oman
Authors: Henderson A. C. , McIlwain J. L. , Al‐Oufi H. S. , Ambu‐Ali A.
Published: June 2006

Female Rhizoprionodon acutus were found to mature between 62 and 74 cm total length (LT) whereas males matured between 63 and 71 cm LT. The LT at 50% maturity was 64·3 cm for females and 64·7 cm for males. Litter size varied from one to six embryos, and was positively correlated with maternal LT. Female embryos outnumbered males by a ratio of 2·3:1. The size at birth was c. 37 cm LT. Full‐term embryos and post‐partum females were observed during all seasons although their occurrence was highest in spring. Spermatozoa were rarely recorded in the oviducal gland, indicating that this species does not store sperm. It was not possible to generate maturity curves for Iago omanensis but it was evident that females matured by the time they reached 35 cm and males were mature by 31 cm LT. This species displayed a clearly defined reproductive cycle with parturition occurring primarily in spring, after a gestation period of c. 1 year. Maximal embryo size was 19 cm LT while maximal litter size was 24 embryos. The oviducal gland appeared to act as a seminal receptacle and it appeared that females may utilize these stores by not mating every year.
Long‐term declines in body size and shifts in run timing of Atlantic salmon in Ireland
Authors: Quinn T. P. , McGinnity P. , Cross T. F.
Published: June 2006

Records extending back from three to seven decades from Atlantic salmon Salmo salar fisheries on the Blackwater, Newport and Owenduff River systems in Ireland, were used to test the hypothesis that there have been progressive declines in size and associated shifts in run timing. They showed identical patterns in four respects: 1) peaks of catch, in spring (March to April) and summer (June to July), 2) the largest fish were caught in the spring, with declines in size over the summer and a slight increase in autumn, 3) marked declines over time in average size and in the proportion of the Atlantic salmon taken in spring and 4) reductions in size in most months at all three sites. Correlations were also detected in average fish mass among the rivers over time (especially the Owenduff and Newport systems), showing a slight rise from the late 1960s until the late 1970s, followed by a steep decline. Data from an electronic counter on the Blackwater showed a reduction in the abundance of early migrants. The early fish were apparently much more vulnerable to fishing than later migrants, so the catch records overstated the abundance of early fish. These long‐term declines in size, which have been noted elsewhere, may be due to other factors in addition to changes in marine productivity. Specifically, reduction in the abundance of large, spring‐running Atlantic salmon may be due to selection resulting from heavy angler exploitation.
Stock structure of Spanish mackerel Scomberomorus commerson along the Australian east coast deduced from parasite data
Authors: Williams R. E. , Lester R. J. G.
Published: June 2006

The parasite fauna of Spanish mackerel Scomberomorus commerson from three regions off eastern Australia was examined for evidence of separate stocks. The abundance of five metacestodes was very similar in all areas suggesting that extensive mixing of the fish occurs along the coast, unlike the situation across northern Australia where large differences have been found between regions. The similarity in abundances of two metacestodes from Townsville fish and south‐east Queensland fish suggests that these two regions have fish with very similar histories. The data lead to the conclusion that the seasonal fishery for Spanish mackerel off south‐east Queensland is based on a random group of fish from the same origin as fish sampled off Townsville and is not a subpopulation that moves south each year.
Structure of the inner ear of bluefin tuna Thunnus thynnus
Authors: Song J. , Mathieu A. , Soper R. F. , Popper A. N.
Published: June 2006

The ears of five large bluefin tuna Thunnus thynnus were examined by light and scanning electron microscopy (SEM). The gross structure of the ear is similar to that in other fishes. The ears, however, appear to be held more rigidly in place than in other species through the presence of an extensive connective tissue between the membranous ear and the surrounding bone. Moreover, unlike other fishes, the semicircular canals and otolithic end organs have thick cartilaginous walls and there is a dense matrix surrounding the otoliths rather than a more watery fluid found in other species. SEM revealed that the saccular epithelium has a ‘standard’ hair cell orientation pattern. The hair cell orientation patterns in the lagena and utricle resemble those found in most other fishes. Ciliary bundle density and length vary in different epithelial regions and each ear had >2 × 106 sensory cells. The morphological results support the hypothesis that bluefin tuna probably do not detect sounds to much over 1000 Hz (if that high) and that only very loud anthropogenic sounds have the potential to affect hearing in this species.
Temporal stability of sea louse Lepeophtheirus salmonis Krøyer populations on Atlantic salmon Salmo salar L. of wild, farm and hybrid parentage
Authors: Glover K. A. , Skaala Ø.
Published: June 2006

Atlantic salmon salmo salar smolts of wild, hybrid and farmed parentage were individually tagged then reared in a sea cage for 8 months. The fish were sampled three times during this period. On all occasions, farmed Atlantic salmon displayed the highest abundance and density of sea lice Lepeophtheirus salmonis, whilst no significant differences were observed between hybrid and wild Atlantic salmon. Percentage variation between the lowest and highest infected groups was as high as 175 and 144% for L. salmonis abundance and density respectively (sample 2). The temporal stability of interindividual sea lice infection levels was investigated pair‐wise between samples using correlation (sample 1 v. 2, 1 v. 3 and 2 v. 3). When calculated using sea louse abundance, correlations ranged from r2 = 0·11, P < 0·01 to r2 = 0·39, P < 0·001, but, when the effects of fish size were controlled for by converting abundance to density, all correlations were < r2 = 0·1. Therefore, these data indicate that a fish‘s relative infection level in one sample was a weak predictor of its relative infection level in another sample. This suggests that identification of individual Atlantic salmon that display reduced susceptibility to sea lice, may be problematic.
Changes in salmon smolt ages in the Welsh River Dee over a 66 year period
Authors: Cragg‐Hine D. , Bradley D. C. , Hendry K.
Published: June 2006

Analysis of Atlantic salmon Salmo salar scales from the River Dee in Wales between 1937 and 2002 revealed a marked increase in the proportion of 1 + year smolts from c. 5% in the period to 1949, to almost 40% in the decade to 2002. Due to regulation flows post‐1964 over the period of change the Dee became colder during the period April to October, indicating that factors other than climate change are likely to be involved.
Histology and carbohydrate histochemistry of the alimentary canal in the rainbow trout Oncorhynchus mykiss
Authors: Marchetti L. , Capacchietti M. , Sabbieti M. G. , Accili D. , Materazzi G. , Menghi G.
Published: June 2006

A histological and histochemical analyses were carried out on the entire alimentary canal of the rainbow trout Oncorhynchus mykiss. In particular the oesophageal region showed presence of terminal β‐D‐galactose(1–3)‐N‐acetylgalactosamine and α‐N‐acetylgalactosamine. In the anterior and posterior regions of the stomach, lining epithelium and gastric pits exhibited the presence of β‐gal and α‐GalNAc. In addition sialoglycoconjugates having sialic acid–β–galactose(1–3)‐N‐acetylgalactosamine and sialic acid‐N‐acetylgalactosamine as terminal tri‐ and di‐saccharides, were demonstrated. In proximal and distal intestine goblet cells showed the presence of sialoglyconjugates, having sialic acid‐β‐gal(1–3)‐GalNAc and sialic acid‐GalNAc as terminal sequences, belonging to N‐linked chains. In the enterocytes of the entire intestine, terminal GlcNAc, α‐Gal, α‐fucose were found.
Migratory behaviour of wild and farmed Atlantic salmon (Salmo salar) during spawning
Authors: ØKland F. , Heggberget T. G. , Jonsson B.
Published: June 2006

Migratory behaviour at spawning of wild and newly‐escaped farmed Atlantic salmon was analysed by radio telemetry in the River Alta, North Norway. Spawning areas were located by aerial surveys. Farmed females moved significantly more than wild females (P <0.01). There was no such difference between the two groups of males. About 83% of the wild fish stayed within identified spawning areas for 1 day or longer. The corresponding figure for farmed salmon was only 43% (P <0.05). Wild salmon stayed 8.1 days inside spawning areas and farmed salmon 5.2 days. The present results suggest that escaped farmed salmon had reduced spawning success compared with wild fish.
The occurrence of metacercariae of Bucephaloides gracilescens (Digenea: Gasterostomata) in an intermediate host, the four‐bearded rockling, Enchelyopus cimbrius (Gadidae)
Authors: Karlsbakk E.
Published: June 2006

Infections with metacercariae of Bucephaloides gracilescens in the four‐bearded rockling Enchelyopus cimbrius were studied for a year in a Norwegian fjord. The prevalence was at all times high, but abundance showed a marked decline in spring to a low level during summer. A rise in abundance, variance‐to‐mean ratio and frequency of smaller metacercariae in early autumn (August‐September) shows infection to have occurred mainly in autumn. There were no differences in level of infection between host sexes, but a highly significant positive correlation of parasite burden with host length. No influence on the condition factor of the host was revealed, the parasite cysts in the central nervous system are believed to have low pathogenicity. A detailed account of the distribution of metacercarial cysts is given. No support for infection being via the lateral line canals is revealed, cercarial penetration is believed to be through the general surface of the head and through the unpaired fins of the trunk and tail.
Brown troutSalmo truttareleased to support recreational fishing in a Norwegian fjord
Authors: Jonsson N. , Jonsson B. , Aass P. , Hansen L. P.
Published: June 2006

One‐ and two‐year‐old hatchery reared juveniles of seven freshwater resident and anadromous populations of Scandinavian brown trout were released in the outer and inner part of the Oslofjord and in the River Akerselva, flowing through the city of Oslo. Recapture rates were highest (mean 20.3%) for river released fish and lowest for those released in the outer (16.8%) and inner (12.1%) fjord. In general, recapture rate increased with fish size at release (r=0.76). When released in fresh water, most of the recaptures were from fresh water and when released in the fjord, most recaptures were from the fjord. In general, freshwater resident stocks showed a higher degree of freshwater residency than anadromous stocks. However, mean migratory distance was longer for freshwater resident than anadromous fish. Trout moved longer distances at sea when released in the outer than in the inner fjord. Specific growth rate and size at recapture varied among release sites and stocks; they were highest for fish released in the outer fjord and lowest for river‐released trout. There was no consistent difference in sea growth between freshwater resident and anadromous stocks. Estimated total yield was highest for fish released in the outer fjord, whereas there was no significant difference in yields between trout released in the river and the inner Oslofjord.
Behavioural responses of sablefish, Anoplopoma fimbria, to bait odour
Authors: Løkkeborg S. , Olla B. L. , Pearson W. H. , Davis M. W.
Published: June 2006

A behavioural bioassay was used to determine the response threshold to squid extract of sablefish, Anoplopoma fimbria, held at three different feeding regimens. Sablefish responded to the odour of bait by changing swimming activity and turning behaviour. The response threshold to bait odour was influenced by both the amount of food eaten and the duration of food deprivation. The total concentration of amino acids in the bait extract was assumed to determine the response threshold as chemical fractionation studies have shown that this class of compounds is essential for the stimulatory capacities of food extracts. When fed to satiation (9.4% wet body weight) and tested after one day of food deprivation, the mean response threshold to total dissolved free amino acids was 4.4 × 10−8m (range=7.6 × 10−8 to 3.6 × 10−8m). When fed at 1.6‐2.3% wet body weight, the threshold sensitivity had increased to a mean value of 1.8 × 10−10m (range=8.4 × 10−10 to 7.0 × 10−11m) after one day of food deprivation; after four days of deprivation, the sensitivity had increased even further to a mean value of 1.4 × 10−11m (range=1.6 × 10−10 to 1.4 × 10−12m). It was also apparent that the intensity of behavioural responses to the bait odour increased with both stimulus concentration and duration of food deprivation. These results suggest that sablefish intensify their search for prey under increased feeding motivation. The active space of a bait source was estimated from the threshold values obtained. Depending on state of food deprivation, rate of chemical release from the bait and the current velocity, maximum lengths of active space within which sablefish would exhibit food searching responses vary from 10 m to several km. Stock assessment based on catch data from baited gear will need techniques that take into account those factors influencing active space for food searching.
Schooling affects growth in the three‐spined stickleback, Gasterosteus aculeatus
Authors: Peuhkuri Nina , Ranta Esa , Juvonen Sanna‐Kaisa , Lindström Kai
Published: June 2006

Three‐spined stickleback fry (mean length 20 mm, mean weight 14 mg) were reared for 14 days alone and in groups of six in a constant per capita water volume. The fish originated from two habitats (rock‐pools, sea) of different predation pressure. The fry were fed nauplii of Artemia and commercial aquarium fish food ad libitum. Specific growth rates of solitary and schooling fry differed and were also affected by their origin. The specific growth rates of solitary fry from the sea averaged 1.0% day−1 (length) and 6.0% day−1 (weight) and those of solitary rock‐pool fry 1.1 and 6.7%, respectively. For group‐reared fish the corresponding values were 1.2% (length) and 6.6% (weight), and 1.3% (length) and 7.6% (weight). The finding that schooling sticklebacks grow faster than solitary ones implies that grouping enhances fitness in stickleback fry under the conditions of our experiments.
Observations on rodlet cells found in the vascular system and extravascular space of angelfish (Pterophyllum scalare scalare)
Authors: Smith S. A. , Caceci T. , Marei H. E‐S. , El‐Habback H. A.
Published: June 2006

In the angelfish (Pterophyllum scalare scalare) numerous rodlet cells were found in the large post‐orbital blood vessel caudal to the eye and in the surrounding extravascular space. Within the vessel the rodlet cells formed striking regular arrays, along the inner aspect of the wall. The rodlets within the cells were positive to PAS but negative to Sudan Black B, Masson's, and the Fuelgen stain. The capsule around the cells was negative for all these stains. These rodlet cells appeared to be traversing the vessel endothelium, and to be pushing the endothelium aside without damaging it. Some discharged their contents into the vessel, but we never observed the release of intact rodlets. The nuclei of rodlet cells in actual contact with the vessel were at the end of the cell more distant from the endothelial wall. Cell‐to‐cell adhesion structures or communications junctions between rodlet cells and the endothelium were not evident. A putative rodlet cell precursor in the extravascular space contained large electron‐dense granules, and extended pseudopodia that contacted nearby rodlet cells. Based on their morphology, tissue distribution, and their behaviour, we conclude that the rodlet cell is an endogeneous teleost cell type, and possibly represents a form of matured granulocyte.
A highly conserved N‐terminal sequence for teleost vitellogenin with potential value to the biochemistry, molecular biology and pathology of vitellogenesis
Authors: Folmar L. C. , Denslow N. D. , Wallace R. A. , LaFleur G. , Gross T. S. , Bonomelli S. , Sullivan C. V.
Published: June 2006

N‐terminal amino acid sequences for vitellogenin (Vtg) from six species of teleost fish (striped bass, mummichog, pinfish, brown bullhead, medaka, yellow perch and the sturgeon) are compared with published N‐terminal Vtg sequences for the lamprey, clawed frog and domestic chicken. Striped bass and mummichog had 100% identical amino acids between positions 7 and 21, while pinfish, brown bullhead, sturgeon, lamprey, Xenopus and chicken had 87%, 93%, 60%, 47%, 47‐60%) for four transcripts and had 40% identical, respectively, with striped bass for the same positions. Partial sequences obtained for medaka and yellow perch were 100% identical between positions 5 to 10. The potential utility of this conserved sequence for studies on the biochemistry, molecular biology and pathology of vitellogenesis is discussed.
The influence of food distribution upon the development of aggressive and competitive behaviour in juvenile chum salmon, Oncorhynchus keta
Authors: Ryer C. H. , Olla B. L.
Published: June 2006

Groups of juvenile chum salmon were reared on food that was either dispersed throughout, or localized in one area of, the rearing tank. Groups receiving localized food displayed more aggression than those receiving dispersed food. This led to differences in growth, with fish reared on localized food having greater individual growth variability, i.e. growth depensation. However, after several months of rearing in these different feeding/social environments, fish reared on dispersed food were just as aggressive when first exposed to localized food as were fish reared on localized food. Furthermore, in competitive contests between fish of the two rearing histories, those reared on dispersed food were just as likely to become dominant as those reared on localized food. These results suggest that the behavioural development of aggressiveness is not amenable to alteration by manipulation of food distribution.
Seawater acclimation of diploid and triploid brook charr (Salvelinus fontinalis), diploid Arctic charr (Salvelinus alpinus), and their diploid and triploid hybrids
Authors: Dumas S. , Audet C. , Blanc J. M. , De La Noüe J.
Published: June 2006

Seawater acclimation of diploid (FF) and triploid (F2F) brook charr Salvelinus fontinalis, diploid (AA) Arctic charr Salvelinus alpinus, and diploid (FA) and triploid (F2A) hybrids between female brook charr and male Arctic charr was investigated. Triploidization of brook charr and the hybrid did not have any effect on the acclimation. Seawater acclimation of the hybrid was achieved during the experimental period and was comparable to that observed in brook charr. Acclimation could not be ascertained in Arctic charr since the level of cortisol, a stress indicator, was still high at the end of the experiment. No relationship between either length or condition factors and plasma osmolality was observed. Elevated plasma cortisol concentrations in Arctic charr and in diploid or triploid hybrids, both in fresh water and sea water, indicate more favourable rearing conditions for brook charr.
Growth, diet and condition of goldsinny on the west coast of Scotland
Authors: Sayer M. D. J. , Gibson R. N. , Atkinson R. J. A.
Published: June 2006

A study of seasonal, locational and sexual variations of growth, diet, somatic condition (Ks), gonadosomatic condition (GSI) and hepatosomatic condition (HSI), of the goldsinny wrasse, Ctenolabrus rupestris, was made on specimens taken from three areas (Millport, Oban and Luing) of the west coast of Scotland from May 1992 to June 1993. Capture throughout the year was by either baited creel or by anaesthetics applied underwater. Male goldsinny of age 1 year and older ranged in total length from 67‐155 mm, total weight 3.8‐58.8 g, and had a maximum age of 14+ years. Females of 1 year and older ranged in total length from 59‐159 mm, total weight 2.4‐65.4 g and had a maximum age of 20+ years. Juvenile (0 +) goldsinny were mostly of indeterminate sex, ranged in total length from 16‐57 mm, and total weight 0.08‐1.97 g. Female growth was slower than that of males for all three locations; growth of male and female goldsinny from Millport was slower than the respective sexes at the other two locations. Length‐weight relationships varied with age and location. There were differences in Ks, GSI, HSI and dietary trends associated with variation in season, sex and location. The implications of this variation are discussed in relation to the management of a sustainable goldsinny fishery.
A rapid method for detecting mitochondrial DNA variation in the brown trout, Salmo trutta
Authors: Hall H. J. , Nawrocki L. W.
Published: June 2006

A method is described for the amplification and restriction digestion of two variable regions of mitochondrial DNA (mtDNA) in the brown trout (Salmo trutta) as a non‐invasive sampling and rapid screening technique for measuring genetic variation in populations.