bluuebunny/crossref_metadata_2025 huggingface dataset:
Cyclophilin A-Dependent Restriction of Human Immunodeficiency Virus Type 1 Capsid Mutants for Infection of Nondividing Cells
Authors: Qi Mingli , Yang Ruifeng , Aiken Christopher
Published: October 2008

Among retroviruses, lentiviruses are unusual in their ability to efficiently infect both dividing and nondividing cells, such as activated T cells and macrophages, respectively. Recent studies implicate the viral capsid protein (CA) as a key determinant of cell-cycle-independent infection by human immunodeficiency virus type 1 (HIV-1). We investigated the effects of the host cell protein cyclophilin A (CypA), which binds to HIV-1 CA, on HIV-1 infection of nondividing cells. The HIV-1 CA mutants A92E, T54A, and R132K were impaired for infection of aphidicolin-arrested HeLa cells, but not HOS cells. The mutants synthesized normal quantities of two-long-terminal-repeat circles in arrested HeLa cells, indicating that the mutant preintegration complexes can enter the nuclei of both dividing and nondividing cells. The impaired infectivity of the CA mutants on both dividing and nondividing HeLa cells was relieved by either pharmacological or genetic disruption of the CypA-CA interaction or by RNA interference-mediated depletion of CypA expression in target cells. A second-site suppressor of the CypA-restricted phenotype also restored the ability of CypA-restricted HIV-1 mutants to infect growth-arrested HeLa cells. These results indicate that CypA-restricted mutants are specifically impaired at a step between nuclear import and integration in nondividing HeLa cells. This study reveals a novel target cell-specific restriction of HIV-1 CA mutants in nondividing cells that is dependent on CypA-CA interactions.
Engineering Viable Foot-and-Mouth Disease Viruses with Increased Thermostability as a Step in the Development of Improved Vaccines
Authors: Mateo Roberto , Luna Eva , Rincón Verónica , Mateu Mauricio G.
Published: October 2008

We have rationally engineered foot-and-mouth disease virus to increase its stability against thermal dissociation into subunits without disrupting the many biological functions needed for its infectivity. Amino acid side chains located near the capsid intersubunit interfaces and either predicted or found to be dispensable for infectivity were replaced by others that could establish new disulfide bonds or electrostatic interactions between subunits. Two engineered viruses were normally infectious, genetically stable, and antigenically indistinguishable from the natural virus but showed substantially increased stability against irreversible dissociation. Electrostatic interactions mediated this stabilizing effect. For foot-and-mouth disease virus and other viruses, some evidence had suggested that an increase in virion stability could be linked to an impairment of infectivity. The results of the present study show, in fact, that virion thermostability against dissociation into subunits may not be selectively constrained by functional requirements for infectivity. The thermostable viruses obtained, and others similarly engineered, could be used for the production, using current procedures, of foot-and-mouth disease vaccines that are less dependent on a faultless cold chain. In addition, introduction of those stabilizing mutations in empty (nucleic acid-free) capsids could facilitate the production of infection-risk-free vaccines against the disease, one of the economically most important animal diseases worldwide.
Identification of a Residue in Hepatitis C Virus E2 Glycoprotein That Determines Scavenger Receptor BI and CD81 Receptor Dependency and Sensitivity to Neutralizing Antibodies
Authors: Grove Joe , Nielsen Søren , Zhong Jin , Bassendine Margaret F. , Drummer Heidi E. , Balfe Peter , McKeating Jane A.
Published: October 2008

Hepatitis C virus (HCV) infection is dependent on at least three coreceptors: CD81, scavenger receptor BI (SR-BI), and claudin-1. The mechanism of how these molecules coordinate HCV entry is unknown. In this study we demonstrate that a cell culture-adapted JFH-1 mutant, with an amino acid change in E2 at position 451 (G451R), has a reduced dependency on SR-BI. This altered receptor dependency is accompanied by an increased sensitivity to neutralization by soluble CD81 and enhanced binding of recombinant E2 to cell surface-expressed and soluble CD81. Fractionation of HCV by density gradient centrifugation allows the analysis of particle-lipoprotein associations. The cell culture-adapted mutation alters the relationship between particle density and infectivity, with the peak infectivity occurring at higher density than the parental virus. No association was observed between particle density and SR-BI or CD81 coreceptor dependence. JFH-1 G451R is highly sensitive to neutralization by gp-specific antibodies, suggesting increased epitope exposure at the virion surface. Finally, an association was observed between JFH-1 particle density and sensitivity to neutralizing antibodies (NAbs), suggesting that lipoprotein association reduces the sensitivity of particles to NAbs. In summary, mutation of E2 at position 451 alters the relationship between particle density and infectivity, disrupts coreceptor dependence, and increases virion sensitivity to receptor mimics and NAbs. Our data suggest that a balanced interplay between HCV particles, lipoprotein components, and viral receptors allows the evasion of host immune responses.
The N-Terminal Region of an Entomopoxvirus Fusolin Is Essential for the Enhancement of Peroral Infection, whereas the C-Terminal Region Is Eliminated in Digestive Juice
Authors: Takemoto Yutaka , Mitsuhashi Wataru , Murakami Ritsuko , Konishi Hirosato , Miyamoto Kazuhisa
Published: October 2008

The spindles of
Anomala cuprea
entomopoxvirus (AncuEPV), which are composed of glycoprotein fusolin, are known to enhance the peroral infectivity of AncuEPV itself and of nucleopolyhedroviruses. This has been demonstrated to involve the disruption of intestinal peritrophic membrane (PM), composed of chitin matrix, glycosaminoglycans, and proteins. To identify essential and nonessential regions for this enhancement activity, AncuEPV fusolin and its deletion mutants were expressed in Sf21 cells using a baculovirus system, and their enhancement abilities were analyzed. The recombinant fusolin enhanced the peroral infectivity of
Bombyx mori
nucleopolyhedrovirus up to 320-fold and facilitated the infection of host insect with AncuEPV. Deletion mutagenesis revealed that the N-terminal region (amino acids 1 to 253), a possible chitin-binding domain, is essential for the enhancement of infection, whereas the C-terminal region is entirely dispensable. The glycosylation-defective mutants N191Q, whose Asn
191
is replaced with Gln, and ΔSIG, whose signal peptide is deleted, showed considerably reduced and abolished enhancing activities, respectively, indicating that the carbohydrate chain is important in the enhancing activity. Interestingly, the C-terminal dispensable region was digested by a serine protease(s) in insect digestive juice. Moreover, both the N-terminal conserved region and the carbohydrate chain were necessary not only for chitin binding but also for stability in digestive juice. A triple amino acid replacement mutant, IHE (Ile-His-Glu
161
to Ala-Ala-Ala), was stable in digestive juice and had chitin-binding ability but did not retain its enhancing activity. These results suggest that the enhancement of infectivity involves more than the tolerance to digestive juice and chitin-binding ability.
Proteomic Analysis Reveals Selective Impediment of Neuronal Remodeling upon Borna Disease Virus Infection
Authors: Suberbielle Elsa , Stella Alexandre , Pont Frédéric , Monnet Céline , Mouton Emmanuelle , Lamouroux Lucile , Monsarrat Bernard , Gonzalez-Dunia Daniel
Published: October 2008

The neurotropic virus Borna disease virus (BDV) persists in the central nervous systems of a wide variety of vertebrates and causes behavioral disorders. BDV represents an intriguing example of a virus whose persistence in neurons leads to altered brain function in the absence of overt cytolysis and inflammation. The bases of BDV-induced behavioral impairment remain largely unknown. To better characterize the neuronal response to BDV infection, we compared the proteomes of primary cultures of cortical neurons with and without BDV infection. We used two-dimensional liquid chromatography fractionation, followed by protein identification by nanoliquid chromatography-tandem mass spectrometry. This analysis revealed distinct changes in proteins implicated in neurotransmission, neurogenesis, cytoskeleton dynamics, and the regulation of gene expression and chromatin remodeling. We also demonstrated the selective interference of BDV with processes related to the adaptative response of neurons, i.e., defects in proteins regulating synaptic function, global rigidification of the cytoskeleton network, and altered expression of transcriptional and translational repressors. Thus, this work provides a global view of the neuronal changes induced by BDV infection together with new clues to understand the mechanisms underlying the selective interference with neuronal plasticity and remodeling that characterizes BDV persistence.
The Effect of γ-Al2O3, TiO2 and ZrO2 Supports on Hydrodesulfurization Activity of Transition-Metal Sulfides
Authors: Kaluža Luděk , Zdražil Miroslav
Published: October 2008

The transition metals V, Cr, Mn, Fe, Co, Ni, Mo, Ru, Rh, Pd, W, Re, Os, Ir and Pt were deposited from aqueous solutions of their salts onto conventional γ-Al2O3 and unconventional TiO2 and ZrO2 supports by vacuum impregnation and characterized in their sulfided form by a model reaction of benzothiophene hydrodesulfurization. It was found that the TiO2 and ZrO2 supports influenced predominantly positively the resulting activity of relatively low-active metals (V, Cr, Mn, Fe, Co, Ni, Mo, Ru, W and Os), whereas the highly active metals (Rh, Pd, Ir, Pt and Re) were influenced slightly negatively or not at all by those supports compared with the γ-Al2O3-supported system. A significant effect of the supports on the hydrodesulfurization-activity ranking of the transition-metal sulfides studied was ascertained.
Reactions of Doubly Tucked-In Permethyltitanocene with tert-Butanol and Propargyl Alcohol. The Crystal Structures of Unusual Hydrolytic Byproducts
Authors: Pinkas Jiří , Gyepes Róbert , Císařová Ivana , Štěpnička Petr , Horáček Michal , Kubišta Jiří , Varga Vojtech , Mach Karel
Published: October 2008

Reactions of double tucked-in permethyltitanocene [Ti{η3:η4-C5Me3(CH2)2}(η5-C5Me5)] (1) with tert-butanol or propargyl alcohol in toluene proceeded sluggishly even with excess of the alcohol and at elevated temperature. The alcoholysis of 1 with tert-butanol afforded [Ti(η5-C5Me5)(Ot-Bu)3] (3) as the major product and Ti(Ot-Bu)4 as the minor one. The other product of the alcoholysis was pentamethylcyclopentadiene. The only isolated crystalline product was the very minor hydrolytic byproduct [{TiIII(η5-C5Me5)2}(μ-O){TiIV(Ot-Bu)3}] (2). The alcoholysis of 1 containing traces of LiI with HOCH2C≡CH, containing apparently more water than t-BuOH, gave an inseparable mixture of oily products from which several crystals of an unintended hydrolytic byproduct [{Ti(η5-C5Me5)(OCH2C≡CH)(μ-O)}3LiI] (4) were isolated. X-ray crystal structures of 2 and 4 were determined.
Hydrodesulfurization of Different Feeds on CoMo/Al2O3 Catalyst Prepared Using Cobalt Heteropolyoxomolybdate
Authors: Spojakina Alla , Jirátová Květuše , Novák Václav , Palcheva Radostina , Kaluža Luděk
Published: October 2008

CoMo/Al2O3 catalyst prepared by impregnation of alumina support with cobalt heteropolyoxomolybdate was tested in hydrodesulfurization (HDS) of thiophene, 1-benzothiophene, or light gas oil under various reaction conditions and reactor arrangements. Its physicochemical properties are also examined. The obtained data are compared with those of two industrial HDS catalysts.
Modification of Co-Mn-Al Mixed Oxide with Promoters and Their Effect on Properties and Activity in VOC Total Oxidation
Authors: Mikulová Zuzana , Jirátová Květuše , Klempa Jan , Kovanda František
Published: October 2008

The activity and selectivity of the Co-Mn-Al mixed oxide catalyst modified with promoters (Pt, Pd, K and La) in total oxidation of volatile organic compounds (toluene and ethanol) were studied. The promoters were introduced at the stage of coprecipitation of a layered double hydroxide (LDH) precursor or impregnation of the mixed oxide obtained by LDH precursor calcination. In total oxidation of toluene, the most active Co-Mn-Al catalysts were those containing low amounts of potassium regardless of the mode of modification, while in total oxidation of ethanol the catalyst impregnated with a higher potassium concentration (3 wt.%) was the most active. Introduction of Pt and Pd in an amount of 0.5 or 0.1 wt.% into the Co-Mn-Al mixed oxide did not improve its catalytic activity. The impregnation method appears to be a more effective mode for preparation of active catalysts than the method using an addition of promoters at the stage of coprecipitation of the LDH precursor. Undesirable reaction intermediate (benzene) was formed when toluene oxidation was carried out over lanthanum- or palladium-containing catalysts. In total oxidation of ethanol, a number of reaction intermediates were produced acetaldehyde being the main one. The catalysts modified at the stage of LDH precursor coprecipitation exhibited a better selectivity (i.e., a lower acetaldehyde formation) than those modified by impregnation. The best results were obtained with the Co-Mn-Al mixed oxide catalyst modified with potassium.
Future Refining Catalysis - Introduction of Biomass Feedstocks
Authors: Kubička David
Published: October 2008

Refining catalysis has been developing over many years to satisfy the demand for high-quality and environmentally-acceptable automotive fuels. Biomass-derived feedstocks have been recently introduced into refineries posing thus new challenges for refining processes and catalysis. The manuscript focuses on three prominent biomass-derived feedstocks: triglycerides, bio-oils and Fischer-Tropsch products from gasified biomass. Due to high oxygen content in biomass feedstocks, deoxygenation processes play an important role in upgrading of these feedstocks. Thus, first peculiarities of deoxygenation are discussed in detail in the context of hydrotreatment processes. Different possibilities of triglycerides and bio-oils deoxygenation including their coprocessing with crude-oil-derived fractions are described. Since biomass-to-liquid processes are very important for the conversion of general biomass into liquid products, the second part deals with the aspects of biomass conversion to synthesis gas, Fischer-Tropsch synthesis and introduction of new co-catalysts.
Bis(μ-carboxylato)dienerhodium(I) Complexes - Synthesis, Characterization and Catalytic Activity
Authors: Zedník Jiří , Sedláček Jan , Svoboda Jan , Vohlídal Jiří , Bondarev Dmitrij , Císařová Ivana
Published: October 2008

Dinuclear rhodium(I) η2:η2-cycloocta-1,5-diene (series a) and η2:η2-norborna-2,5-diene (series b) complexes with μ-RCOO- ligands, where R is linear C21H43 (complexes 1a, 1b), CH2CMe3 (2a, 2b), 1-adamantyl (3a, 3b) and benzyl (4a, 4b), have been prepared and characterized by spectroscopic methods. Structures of complexes 2b, 3a and 4a were determined by X-ray diffraction analysis. Complexes prepared show low to moderate catalytic activity in polymerization of phenylacetylene in THF giving high-cis-transoid polymers, but they show only oligomerization activity in dichloromethane.
Treatment of chronic ocular hypotony with intraocular application of sodium hyaluronate
Authors: Küçükerdönmez C , Beutel J , Bartz-Schmidt K U , Gelisken F
Published: October 2008

Aim:

The aim of the study was to report the functional and morphological outcome of intraocular injection of sodium hyaluronate for treatment of chronic ocular hypotony (COH).

Methods:

We reviewed the digital chart records of patients with COH who had received one or more injections of intravitreal or intracameral sodium hyaluronate (1.4% or 2.3%). The changes in the best corrected visual acuity (BCVA) and intraocular pressure (IOP) after treatment were recorded.

Results:

Thirty-two eyes of 32 patients with a mean age of 56.8 years were analysed. Previous vitreoretinal surgery had been performed on all eyes for either ocular-penetrating trauma (six eyes), chronic uveitis (six eyes), full macular translocation (five eyes) or retinal detachment (15 eyes). Mean follow-up time after the first intraocular injection was 29.7 months. BCVA (logMAR) at the baseline and the last follow-up visit were 1.84 (SE 0.65) and 1.82 (SE 0.72), respectively (p = 0.87). The mean IOP at the baseline increased from 2.28 (SE 0.27) mmHg to 7.12 (SE 1.03) mmHg at the last visit (p<0.001). At the final follow-up, 20 eyes (62.5%) had an IOP higher than 5 mmHg and 24 eyes (75%) had an unchanged or improved BCVA.

Conclusions:

Stabilisation of the IOP and vision in some eyes with COH following vitreoretinal surgery can be achieved with intraocular injection of sodium hyaluronate. Large case-series and long-term follow-up are necessary to confirm the beneficial role of intraocular sodium hyaluronate injections in such eyes.
Corticosteroids for bacterial corneal ulcers
Authors: Srinivasan M , Lalitha P , Mahalakshmi R , Prajna N V , Mascarenhas J , Chidambaram J D , Lee S , Hong K C , Zegans M , Glidden D V , McLeod S , Whitcher J P , Lietman T M , Acharya N R
Published: October 2008

Aims:

The aim of the study was to conduct a preliminary clinical trial to assess whether adjunctive topical corticosteroids improve outcomes in bacterial keratitis and, if no difference was found, to determine the feasibility and sample size necessary for conducting a larger trial to answer this question.

Methods:

In this single centre, double-masked clinical trial, 42 patients with culture-confirmed bacterial keratitis at Aravind Eye Hospital in India were randomised to receive either topical prednisolone phosphate or placebo. All patients received topical moxifloxacin. The primary outcome was best spectacle-corrected visual acuity (BSCVA) at 3 months, adjusting for enrolment BSCVA and arm. Other pre-specified outcomes included re-epithelialisation time, infiltrate/scar size and adverse events.

Results:

Compared with placebo, patients in the steroid group re-epithelialised more slowly (hazard ratio 0.47, 95% CI 0.23 to 0.94). There was no significant difference in BSCVA or infiltrate/scar size at 3 weeks or 3 months. To have 80% power to detect a two-line difference in acuity, 360 cases would be required.

Conclusions:

Although corticosteroid treatment resulted in a statistically significant delay in re-epithelialisation, this did not translate to a significant difference in visual acuity, infiltrate/scar size or adverse events. To assess the effect of steroids on acuity, a larger trial is warranted and feasible.

Trial registration number:

NCT00324168
Early neurological deterioration in acute ischaemic stroke: predictors, mechanisms and management
Authors: Thanvi B , Treadwell S , Robinson T
Published: October 2008

Early neurological deterioration (END) in acute ischaemic stroke is a common event. The underlying mechanisms are heterogeneous. The clinical predictors of END include severity of the initial stroke, large vessel occlusion, diabetes mellitus, hypotension, and atrial fibrillation. Serial observations and detailed assessment by the trained staff in specialised stroke units are key to the successful management of these patients. Advances in brain and vascular imaging have provided insight into the underlying mechanisms, enabling clinicians to use preventative and therapeutic interventions specifically targeted at them, though several questions still remain unanswered. END has potentially serious consequences on the short term (morbidity and death) and long term (recovery from stroke) outcomes for the patient. Therefore, attempts to prevent and treat END should be made promptly and aggressively.
Phasic characteristics of inspiratory crackles of bacterial and atypical pneumonia
Authors: Norisue Y , Tokuda Y , Koizumi M , Kishaba T , Miyagi S
Published: October 2008

Background

No known physical findings are available to differentiate between bacterial pneumonia (BP) and atypical pneumonia (AP) in patients with community-acquired pneumonia (CAP).

Objective

To evaluate the possible differences in phasic characteristics of inspiratory crackles between BP and AP in patients with CAP.

Methods

Retrospective chart reviews were conducted to obtain phasic characteristics of inspiratory crackles (early, early-to-mid, late and pan-inspiratory crackles) in AP and BP groups in a community teaching hospital in Japan (n = 183).

Results

100 patients with BP and 83 patients with AP were evaluated. Patients with BP were significantly more likely to present with pan-inspiratory crackles (49 (49.0) vs 5 (6.0); p<0.0001), whereas patients with AP were more likely to present with late inspiratory crackles (28 (33.7) vs 9 (9.0); p<0.0001) (mean (SD)). Among pneumonia patients with audible crackles, the sensitivity and specificity of pan-inspiratory crackles for BP were 83.1% and 85.7%, respectively, and the sensitivity and specificity of late inspiratory crackles for AP were 80.0% and 84.7%, respectively.

Discussion

In patients with CAP and audible crackles, phasic characteristics of inspiratory crackles may be used to distinguish AP from BP. Prospective studies are needed to confirm these findings.
Acute thyroiditis due to septic emboli derived from infective endocarditis
Authors: Cabizuca C A , Bulzico D A , de Almeida M H , Conceição F L , Vaisman M
Published: October 2008

Acute infectious thyroiditis is a rare condition of the thyroid gland, most often arising in children with congenital conditions connecting the thyroid directly to the oropharynx, such as a piriform fistula or thyroglossal duct. We report a case of acute thyroiditis due to septic emboli derived from infective endocarditis.
Lake Use by Wild Anadromous Atlantic Salmon,Salmo salar, as an Index of Subsequent Adult Abundance
Authors: Ryan P. M.
Published: October 2008

Atlantic salmon, Salmo salar, were censused each spring and fall for 5 or 6 yr in two lakes at the headwaters of the Gander River, Newfoundland. Density, biomass, and age varied seasonally and annually, ranging from 5.2 to 78.7 fish∙ha−1, 0.2 to 3.4 kg∙ha−1, and 1 to 7 yr, respectively. Seasonal changes in age composition were used to calculate net numbers and ages of fish moving into and out of the lakes. Population sizes typically increased from fall to spring as young fish moved into the lakes from downstream spawning areas and decreased from spring to fall as older fish moved downstream. The calculated net number of spring to fall emigrants over 6 yr was positively correlated (r = 0.835) with adult abundance (catch per unit effort) in the recreational fishery 1 yr later. The varying modal age of these emigrants was identical to the modal freshwater age of returning adults in each of four comparable years. Censusing of young Atlantic salmon in standing waters can be used to monitor smolt production and assist in prediction of the subsequent abundance of sea-run adults.
Effects of Temperature and Food Quality on Growth and Development of a Mayfly,Leptophlebia intermedia
Authors: Sweeney Bernard W. , Vannote Robin L. , Dodds Peter J.
Published: October 2008

Larval development, adult size, and fecundity of Leptophlebia intermedia were assessed in response to rearing on five diets (hickory, white ash, red oak, chestnut oak, and American beech leaves) at each of three temperature regimes (ambient White Clay Creek temperatures (WCC) and 3 and 6°C above WCC). Developmental time was shortened about 40–50 d by elevating creek temperatures 6 °C, but varied only about 20–30 d over the range of diets for any given temperature. Adult size was influenced more by diet than temperature. Adult female weights differed among diets by about 1.5 mg for any given temperature regime. In contrast, female weights varied by only about 0.6 mg among temperatures for any given diet. The proportion of total female weight allocated to eggs increased with adult size and ranged from 0.12 to 0.45 depending on diet and temperature. In general, hickory and white ash diets consistently yielded the highest survival and largest adults, while the highest mortality and poorest growth occurred on the red oak and American beech diets.
Influence of Dietary Protein and Lipid on Apparent Heat Increment of Rainbow Trout,Salmo gairdneri
Authors: LeGrow S. M. , Beamish F. W. H.
Published: October 2008

Oxygen uptake attributable to apparent heat increment (AHI) in rainbow trout, Salmo gairdneri (10–15 g), induced to swim at [Formula: see text] was influenced by dietary energy intake and diet composition. Twelve balanced diets were tested, with protein levels of [Formula: see text], 40, 48 and 60% and lipid levels of [Formula: see text], 15, and 23% factorally combined. Diets supplying 34% protein and 23% lipid (protein to energy ratio of 94.3 mg∙kcal−1) resulted in the lowest AHI of all diets tested, indicating most efficient utilization of dietary protein. At a dietary lipid level of 23%, dietary protein levels lower than 34% may result in a further reduction in AHI. Duration of elevated metabolism following feeding was independent of dietary protein and lipid level, as well as dietary energy intake. AHI of rainbow trout represented the equivalent of 15–24% of the digestible energy intake, depending on diet composition. A reduction in dietary protein with a concomitant increase in dietary lipid in the formulation of feeds for aquaculture purposes could enhance growth efficiency by reducing the energy expenditure for AHI.
Sexual Differentiation and Use of Hormones to Control Sex in Yellow Perch (Perca flavescens)
Authors: Malison Jeffrey A. , Kayes Terrence B. , Best Cody D. , Amundson Clyde H. , Wentworth Bernard C.
Published: October 2008

Morphological and histologial studies demonstrated that estrogens and androgens affect sexual differentiation and can be used to control the phenotypic sex of yellow perch (Perca flavescens). Normal perch larvae of 5–10 mm total length (TL) had paired gonads with no sex-distinguishing features. In normal 16 mm TL perch, the gonads of females had fused into a single sac-shaped organ, while in males the gonads remained paired. Oogenesis had begun in most females of 35 mm TL. Spermatogenesis in males and vitellogenesis in females were first observed at 85 mm TL. Treatment (for 84 d) of perch (initially 20–35 mm TL) with estradiol-17β at 15–120 μg/g diet induced complete germ cell sex inversion in most males. Similar treatment with 17α-methyltestosterone at 1.5 to 60 μg/g diet induced spermatogenesis and the formation of ovotestes in females. Sperm collected from such ovotestes fertilized normal ova, and the resultant offspring were all female. Our findings indicate that in yellow perch: (1) differentiation of the somatic elements of the gonads precedes gametogenesis, (2) gametogenesis begins earlier in females than in males, (3) the attainment of a specific minimum body size (80–100 mm TL) is important to the initial onset of vitellogenesis and spermatogenesis, (4) both estrogens and androgens are probably involved in mediating sexual differentiation of germinal tissues and (5) females are the homogametic sex.
Pathogenesis of Experimental Edwardsiella ictaluri Infections in Channel Catfish (Icta lurus punctatus)
Authors: Shotts E. B. , Blazer V. S. , Waltman W. D.
Published: October 2008

The lesions observed in channel catfish (Ictalurus punctatus) as a consequence of exposure to Edwardsiella ictaluri via gut and water were studied. Channel catfish fingerlings were exposed to 1010 bacterial cells via the gut and placed in tanks with unexposed fish. Both groups of fish were sampled periodically over a 35-day period. The gut-exposed fish exhibited gross signs of a systemic infection within 2 wk. Enteritis, hepatitis, interstitial nephritis, and myositis, all of which began as acute reactions and developed into chronic lesions, were observed histologically. Some of the contact fish developed systemic infections beginning in the intestine, thus demonstrating horizontal transmission. However, only contact fish developed the characteristic "hole in the head" lesion, which began in the olfactory sac and progressed to a granulomatous meningioencephalitis. These results indicate that both gut and nares are sites of primary infection in natural outbreaks of E. ictaluri.
Identifying the Stock–Recruitment Relationship for Age-Structured Populations Using Time-Invariant Matched Linear Filters
Authors: Welch David W.
Published: October 2008

Theory is introduced which permits the identification and removal of part of the environmental (density-independent) noise influencing the recruitment to age-structured populations. The biological assumptions under which this noise may be safely removed from the recruitment data without distorting the analysis of the density-dependent dynamics are outlined, and the permissible level of filtering is shown to depend on the age structure of the population in question. As examples of the method, filters were designed and applied to stock–recruitment data available for 16 commercially exploited marine fish populations. A substantial improvement is demonstrated in the statistical precision with which the stock–recruitment relationship can be defined, with standard errors on parameter estimates frequently decreasing by a factor of 2 or 3 after filtering. In general, use of filtering theory should allow a more precise definition of the nature of the stock–recruitment relationship in essentially all age-structured populations.
Biogeographic Influences on Fish Species Composition of Northern Wisconsin Lakes with Applications for Lake Acidification Studies
Authors: Rahel Frank J.
Published: October 2008

Species–area relations, used to predict the number of fish populations lost in acidified lakes, may overestimate the number of extinctions if regression equations developed from unacidified (high-alkalinity) lakes are used to predict the number of species previously present in acidified (low-alkalinity) lakes. In 100 northern Wisconsin lakes, the species–area regression for alkaline lakes (>10 mg/L as CaCO3) had a higher intercept and greater slope than the regression for low-alkalinity, but unacidified lakes. Thus, low-alkalinity lakes had fewer species than alkaline lakes, and added species at a slower rate as lake size increased. Biogeographic factors (lake size, alkalinity, isolation from other water bodies) strongly influenced fish community composition. Small lake size appeared to exclude species requiring wave-washed, rocky substrates and species preferring cool, well-oxygenated water; such habitat is limited in small lakes. Low alkalinity and associated chemical conditions (e.g. low pH) limited the occurrence of many cyprinids and some percids (genus Etheostoma). Lake isolation (no inlet and outlet streams) appeared to have a limited effect on species composition. An exception was the reduced occurrence, in lakes without tributary streams, of species that spawn in flowing water. Fish distributions among Wisconsin lakes provide a test of habitat requirements proposed for other geographic regions.
Optimal Stock Size and Harvest Rate in Multistage Life History Models
Authors: Moussalli Elie , Hilborn Ray
Published: October 2008

If the life history of a population consists of a sequence of density-dependent stages linked by density-independent survival rates, and if the density-dependent stages take the form of the Beverton–Holt stock and recruitment curve, then a single Beverton–Holt curve will describe the entire life history. The relationship between the parameters of any stage in the life history and the optimal harvest rate and optimal stock size is analyzed. Increasing survival rates will always increase the optimal harvest rate, but may increase or decrease the optimal stock size. Increasing the habitat capacity will increase the optimal stock size and leave the optimal harvest rate unaffected. An example of changing freshwater survival rates by Salmonid Enhancement is shown, as is an example of changing ocean survival rate. As we acquire a better understanding of the determinants of survival and habitat capacity, we should adjust harvest rates and stock size as the environment changes.
Light and Nutrient Effects on the Relative Biomass of Blue-Green Algae in Lake Phytoplankton
Authors: Smith Val H.
Published: October 2008

The factors determining the relative biomass of blue-green algae during the growing season were studied using data from 22 lakes worldwide. Multiple linear regression analyses suggest that total nitrogen (TN), total phosphorus (TP), and light (as estimated from Secchi disc transparency and the depth of the mixed layer) interact to determine the relative biomass of planktonic blue-green algae. At a fixed TN: TP ratio, blue-green relative biomass increases as light availability decreases. At a fixed light level, blue-green relative biomass also increases as the TN: TP ratio decreases. Both effects are consistent with current knowledge of algal physiology, and with a recently proposed theoretical framework for algal community structure.
Analyzing Catch–Effort Data Allowing for Randomness in the Catching Process
Authors: Reed William J.
Published: October 2008

For many fisheries the only reliable data is a (bivariate) time series of catches and efforts. Most existing methods of analyzing such data implicitly assume that the main source of randomness is in the dynamics of the population, while ignoring randomness in the catching process. The assumption of a deterministic catch production function (usually of the Schaefer form C = qEX) must be contrary to the experience of almost everyone who has ever gone fishing. In this paper a stochastic catch model coupled with a deterministic dynamic model is used in the analysis of catch–effort data and shown to give very plausible results. Estimates (with confidence intervais) of catchability, maximum sustainable yield, and other dynamic model parameters are obtained numerically by the method of maximum likelihood. The incorporation of stochastic dynamics with the stochastic catch model is difficult.
Ecological Significance of the Ctenophore Pleurobrachia pileus off Southwestern Nova Scotia
Authors: Frank Kenneth T.
Published: October 2008

The population dynamics and quantitative feeding ecology of the ctenophore (Pleurobrachia pileus) were investigated in the spring of 1983 and 1984 on Browns Bank, southwestern Scotian Shelf. In both years, large crustacean Zooplankton (>1050 μm) were the dominant item in the diet of Pleurobrachia among all sizes captured (range = 5–21 mm diameter) averaging 70% by weight of the total prey consumed. The daily ration of Pleurobrachia was strongly size dependent increasing from 2.6 mg dry wt./d at a body size of 6 mm to 8.5 mg/d at 12 mm. At the population level, daily consumption of crustacean zooplankton during 1983 and 1984 averaged 8.8% (range = 0.2–28%) and 0.7% (range = 0.2–2%) of the prey standing stock, respectively. This difference was consistent with the observation that there was 28% less zooplankton, on average, during 1983 relative to 1984 at the same time and location. An abnormal spring peak in ctenophore abundance was evident in 1983, but not in 1984, that consisted of large, mature individuals at average densities in excess of 1/m3. Ctenophore abundance during spring of 1984 averaged 0.1/m3 Increased overwintering survival of ctenophores resulting from anomalously high sea surface temperatures (SST) appears to have been responsible for the exceptional spring abundance of Pleurobrachia on Browns Bank during 1983. Over 50% of the variation in a 10-yr time series of spring Pleurobrachia abundance for the southwest Nova Scotia region was explained by SST conditions prevailing during January to April. I suggest that the extremely low levels of haddock (Melanogrammus aeglefinus) larvae produced on Browns Bank during the spring of 1983 resulted from food shortages induced by severe depredation of zooplankton by Pleurobrachia.
Activity Differences influencing Food Selection in the Marine FishPomatoschistus microps
Authors: Magnhagen Carin
Published: October 2008

Diets of female and male Pomatoschistus microps during the reproductive period (May–July) differed. Males ate less but used a wider range of prey species than did females. While males guard the eggs and therefore are tied to a nest during the breeding season, females have a higher mobility which leads to a higher prey encounter rate and hence a higher food selectivity than in males. After reproduction the differences between the sexes in food intake and diet disappeared. In laboratory experiments the fish were less active in aquaria with a high prey density than in those with a low density. A decrease in food selectivity with an increasing prey density can thus be due to a decrease in the activity of the fish. At a high prey density, P. microps may benefit from having a low activity and taking unselectively the prey items in its vicinity. The advantages could be reduced detectability by predators and decreased energy expenditure due to locomotion.
Histological Changes in Cultured Lake Trout, Salvelinus namaycush, Subjected to Cumulative Loading in a Water Reuse System
Authors: Meade James W. , Herman Roger Lee
Published: October 2008

Lake trout (Salvelinus namaycush), 16 cm long, were reared 8 wk in five serial reuse units, resulting in cumulative loadings of 1.5–7.5 kg fish∙L−1∙min−1. Although mean un-ionized ammonia concentrations in the highest loading levels were less than 10% of those often considered as safe for culture of rainbow trout (Salmo gairdneri), lake trout reared at the higher loading levels showed dilation of glomerular capillaries, a condition that persisted after cumulative loading conditions were removed, and gill epithelial hyperplasia and hypertrophy. We observed lamellar telangiectasis caused by sampling technique. We conclude that parameters other than ammonia concentrations are significant factors in branchial irritation.
Acclimation-Induced Change in Toxicity of Aluminum to Rainbow Trout (Salmo gairdneri)
Authors: Orr P. L , Bradley R. W. , Sprague J. B. , Hutchinson N. J.
Published: October 2008

When a group of rainbow trout (Salmo gairdneri) fingerlings was exposed to 87 μg Al/L for 1 and 2 wk, their threshold lethal concentration (LC50) increased to about 1.8 times the control LC50 of 175 μg Al/L. Raising sublethal exposure to 154 μg/L during the third week resulted in a similar ratio of 1.7 between LC50s of previously exposed and control fish. Thus, prior exposures of 0.5 and 0.9 of the control LC50 resulted in about the same increase in tolerance. The magnitude of the increase was similar to those reported in the literature for other metals. Such acclimation could assist in the survival of fish during spring and autumn surges of aluminum and other metals in surface waters acidified by atmospheric deposition of oxides of sulfur and nitrogen; those environmental changes in aluminum concentration parallel the concentrations used in this research. Experimental water simulated an acid lake with pH of 5.1–5.3 and total hardness of 11 mg/L.
Environmental Control of Green Sea Urchin,Strongylocentrotus droebachiensis, Spawning in the St. Lawrence Estuary
Authors: Starr Michel , Himmelman John H. , Therriault Jean-Claude
Published: October 2008

Environmental factors and spawning of the green sea urchin, Strongylocentrotus droebachiensis, were examined during 1983 and 1984 in the St. Lawrence Estuary. In both years, spawning occurred in June, which contrasts sharply with the February to early May spawnings reported for other locations. This difference does not appear to be related to temperature, but to the much delayed spring increase of phytoplankton in the Estuary. In both 1983 and 1984, sea urchin spawning coincided with the first marked and sustained increase in phytoplankton abundance (chlorophyll a levels of 1–2 mg∙m−3for > 3 d) which took place about 2 wk before the main spring bloom; this first increase coincided with a sharp increase in salinity resulting from a decrease in freshwater runoff. Sea urchin spawned later in 1983 than in 1984. This difference did not appear to be related to either a critical temperature level or short-term temperature fluctuations; however, it did coincide with a greater freshwater runoff and a consequently delayed seasonal increase in salinity and phytoplankton. We hypothesize that onset of the phytoplankton bloom initiates spawning; freshwater runoff may indirectly determine the time of spawning by controlling when the bloom will occur.
In situ Bioassays of Brook Trout (Salvelinus fontinalis) and Blacknose Dace (Rhinichthys atratulus) in Adirondack Streams Affected by Episodic Acidification
Authors: Simonin Howard A. , Kretser Walter A. , Bath Dale W. , Olson Mark , Gallagher James
Published: October 2008

In situ bioassays were conducted using native Adirondack brook trout (Salvelinus fontinalis) and blacknose dace (Rhinichthys atratulus) in four headwater streams. Conductivity, pH, temperature, and stage height were monitored continuously, and water samples for laboratory analysis were collected during hydrologic episodes. Fish survived well during baseflow conditions, but during periods of spring snowmelt or large precipitation events, survival was poor. Blacknose dace were more sensitive than brook trout, and mortality was best correlated with the log of median inorganic monomeric aluminum (Alim) concentration. Brook trout mortality was best correlated with a two-variable model that included dissolved organic carbon (DOC) and a concentration–duration variable (median Alim during the episode times the duration of the episode). Brook trout mortality was inversely correlated with DOC. Bioassay fish that had been in the streams 15–24 d survived episodes better than fish that had either not become acclimatized or recovered from handling. Duration of exposure to acidic episodes was critical. Extended periods of poor water quality resulted in fish mortality and may be more important to native populations than short acidic episodes.
Feeding, Growth, and Survival of Atlantic Cod (Gadus morhua) Larvae Reared in Replicate Plastic Enclosures
Authors: Otterå Håkon
Published: October 2008

Feeding, growth, and survival of Atlantic cod (Gadus morhua) larvae were examined during their first 2 mo of life. The experiment was carried out in eight plastic enclosures of 10 m3 volume each. Larval cod, at an initial stocking density of 10 larvae/L, were fed rotifers (Brachionus plicatilis) and natural zooplankton collected from the sea. The enclosures replicated well with regard to hydrography, feeding conditions, and larval growth and survival. Larval mortality was low during the first month, with a mean mortality rate (Z) of 0.02/d. Growth, however, was very slow and mortality increased significantly after about 4 wk, possibly due to starvation. Brachionus plicatilis dominated the gut content during the first 3–4 wk. The zooplankton concentration averaged 15–80 rotifers/L during the first 2 wk, which seemed to be insufficient under the present rearing conditions. Most of the larvae were distributed in the upper parts of the rearing enclosures, while rotifers were distributed deeper. This, together with the high larval density, inadequate rotifer enrichment, and low temperature probably amplified the unfavourable feeding conditions.
Year-Class Fluctuations of Vendace (Coregonus albula) in Lake Pyhäjärvi, Southwest Finland, during 1971–90
Authors: Helminen Harri , Auvinen Heikki , Hirvonen Arto , Sarvala Jouko , Toivonen Jorma
Published: October 2008

Many recent studies have stressed density-dependent regulation mechanisms in oscillating vendace (Coregonus albula) populations. Long-term studies on the population dynamics of vendace have been hampered by the difficulty of obtaining reliable estimates of year-class sizes. Data collected from Lake Pyhäjärvi (Southwest Finland) during 1971–91 allowed relatively accurate analysis of vendace abundance changes. In the winters of 1979–91, daily catch statistics were collected from professional fishermen. Species, age, and size composition were analysed from regular catch samples. We estimated the size of the vendace population from the decrease in the CPUE during 10 winters. For the remaining 10 years, estimates were based on the relationship between the numbers of a year-class in autumn and mean individual growth rate. A 2-yr cycle was the most conspicuous feature of the data implying density-dependent regulation. We suggest that in Lake Pyhäjärvi the basic model producing a persistent 2-yr cycle is the asymmetrical food competition between age groups.
A Novel Approach to Evaluate Feeding by Mixed Cyprinid Species in a Chinese Integrated Fish Culture Pond Using Measurements of Chlorophyll Derivatives and Photosynthesis in Gut Contents
Authors: Takamura Noriko , Li Ja-Le , Yang He-Quan , Zhu Xue-Bao , Miura Taizo
Published: October 2008

Chlorophyll derivatives and algal photosynthesis in the guts of five reared cyprinid species were studied to quantify feeding by cyprinids in a Chinese integrated fish culture pond. Pigment analysis identified organic detritus that had been overlooked by microscopic observation. The high ratios of Chl b/Chl a and of pheophorbide a/Chl a were good indicators of herbivory on aquatic plants and zooplanktivory, respectively. High photosynthetic rates in faeces indicated herbivory on phytoplankton. Grass carp (Ctenopharyngodon idella) fed mostly on aquatic plants. Blunt snout bream (Megalobrama amblyocephala) selected plants, but also fed on filamentous algae and zooplankton. Silver carp (Hypophthalmichthys molitrix) fed on phytoplankton most frequently among the five carp species examined, but also utilized zooplankton and amorphous detritus, probably originating from plant fragments. Bighead (Aristichthys nobilis) and crucian carp (Carassius auratus) utilized zooplankton and plant fragments. Planktivorous production in this pond was partly supported by a large amount of plant debris, derived from the faeces of grass-eating cyprinids and nourished by microorganisms in the pond water.
Comparison of Some Life History Characteristics of Pacific Herring (Clupea pallasi) from the Canadian Pacific Ocean and Beaufort Sea
Authors: Tanasichuk R. W. , Kristofferson A. H. , Gillman D. V.
Published: October 2008

We compared several growth and reproductive characteristics of Pacific herring (Clupea pallasi) from the Canadian Pacific Ocean and Beaufort Sea using data for 2310 fish gillnetted in the northern Strait of Georgia or near Tuktoyaktuk, N.W.T., over the 1985 spawning season. Weight-at-age was similar but Beaufort Sea fish were longer-at-age. Total weight-at-length was significantly greater for Strait of Georgia herring because their size-specific ripe ovary weights were 2.1 times greater. We attributed differences in growth and surplus energy allocation to adult instantaneous mortality rates being 1.8 times higher for Strait of Georgia herring. Size-specific ripe egg weight was 30% smaller in Beaufort Sea herring presumably because warmer sea temperatures over the larval period resulted in a higher mortality rate. Weight-specific fecundity was 1.5 times greater in Strait of Georgia fish. Ovarian growth rates near spawning were lower in Beaufort Sea herring because they mature in colder water.