bluuebunny/crossref_metadata_2025 huggingface dataset:
A cytosolic factor that inhibits KATP channels expressed in Xenopus oocytes by impairing Mg‐nucleotide activation by SUR1
Authors: Tammaro Paolo , Ashcroft Frances M.
Published: February 2009

ATP‐sensitive K+ (KATP) channels couple cell metabolism to cell electrical activity. Wild‐type (Kir6.2/SUR1) KATP channels heterologously expressed in Xenopus oocytes give rise to very small inward currents in cell‐attached patches. A large increase in the current is observed on patch excision into zero ATP solution. This is presumably due to loss of intracellular ATP leading to unblock of KATP channels. In contrast, channels containing Kir6.2 mutations associated with reduced ATP‐sensitivity display non‐zero cell‐attached currents. Unexpectedly, these cell‐attached currents are significantly smaller (by ∼40%) than those observed when excised patches are exposed to physiological ATP concentrations (1–10 mm). Cramming the patch back into the oocyte cytoplasm restores mutant KATP current amplitude to that measured in the cell‐attached mode. This implies that the magnitude of the cell‐attached current is regulated not only by intracellular ATP but also by another cytoplasmic factor/s. This factor seems to require the nucleotide‐binding domains of SUR1 to be effective. Thus a mutant Kir6.2 (Kir6.2ΔC‐I296L) expressed in the absence of SUR1 exhibited currents of similar magnitude in cell‐attached patches as in inside‐out patches exposed to 10 mm MgATP. Similar results were found when Kir6.2‐I296L was coexpressed with an SUR1 mutant that is insensitive to MgADP or MgATP activation. This suggests the oocyte contains a cytoplasmic factor that reduces nucleotide binding/hydrolysis at the NBDs of SUR1. In conclusion, our results reveal a novel regulatory mechanism for the KATP channel. This was not evident for wild‐type channels because of their high sensitivity to block by ATP.
Functional maturation of the exocytotic machinery at gerbil hair cell ribbon synapses
Authors: Johnson Stuart L. , Franz Christoph , Knipper Marlies , Marcotti Walter
Published: February 2009

Auditory afferent fibre activity in mammals relies on neurotransmission at hair cell ribbon synapses. Developmental changes in the Ca2+ sensitivity of the synaptic machinery allow inner hair cells (IHCs), the primary auditory receptors, to encode Ca2+ action potentials (APs) during pre‐hearing stages and graded receptor potentials in adult animals. However, little is known about the time course of these changes or whether the kinetic properties of exocytosis differ as a function of IHC position along the immature cochlea. Furthermore, the role of afferent transmission in outer hair cells (OHCs) is not understood. Calcium currents and exocytosis (measured as membrane capacitance changes: ΔCm) were measured with whole‐cell recordings from immature gerbil hair cells using near‐physiological conditions. The kinetics, vesicle pool depletion and Ca2+ coupling of exocytosis were similar in apical and basal immature IHCs. This could indicate that possible differences in AP activity along the immature cochlea do not require synaptic specialization. Neurotransmission in IHCs became mature from postnatal day 20 (P20), although changes in its Ca2+ dependence occurred at P9–P12 in basal and P12–P15 in apical cells. OHCs showed a smaller ΔCm than IHCs that was reflected by fewer active zones in OHCs. Otoferlin, the proposed Ca2+ sensor in cochlear hair cells, was similarly distributed in both cell types despite the high‐order exocytotic Ca2+ dependence in IHCs and the near‐linear relation in OHCs. The results presented here provide a comprehensive study of the function and development of hair cell ribbon synapses.
Head and neck control varies with perturbation acceleration but not jerk: implications for whiplash injuries
Authors: Siegmund Gunter P. , Blouin Jean‐Sébastien
Published: February 2009

Recent studies have proposed that a high rate of acceleration onset, i.e. high jerk, during a low‐speed vehicle collision increases the risk of whiplash injury by triggering inappropriate muscle responses and/or increasing peak head acceleration. Our goal was to test these proposed mechanisms at realistic jerk levels and then to determine how collision jerk affects the potential for whiplash injuries. Twenty‐three seated volunteers (8 F, 15 M) were exposed to multiple experiments involving perturbations simulating the onset of a vehicle collision in eyes open and eyes closed conditions. In the first experiment, subjects experienced five forward and five rearward perturbations to look for the inappropriate muscle responses and ‘floppy’ head kinematics previously attributed to high jerk perturbations. In the second experiment, we independently varied the jerk (∼125 to 3 000 m s−3) and acceleration (∼0.65 to 2.6 g) of the perturbation to assess their effect on the electromyographic (EMG) responses of the sternocleidomastoid (SCM), scalene (SCAL) and cervical paraspinal (PARA) muscles and the kinematic responses of the head and neck. In the first experiment, we found neither inappropriate muscle responses nor floppy head kinematics when subjects had their eyes open, but observed two subjects with floppy head kinematics with eyes closed. In the second experiment, we found that about 70% of the variations in the SCM and SCAL responses and about 95% of the variations in head/neck kinematics were explained by changes in perturbation acceleration in both the eyes open and eyes closed conditions. Less than 2% of the variation in the muscle and kinematic responses was explained by changes in perturbation jerk and, where significant, response amplitudes diminished with increasing jerk. Based on these findings, collision jerk appears to have little or no role in the genesis of whiplash injuries in low‐speed vehicle crashes.
Tibialis anterior stretch reflex in early stance is suppressed by repetitive transcranial magnetic stimulation
Authors: Zuur Abraham T. , Christensen Mark S. , Sinkjær Thomas , Grey Michael J. , Nielsen Jens Bo
Published: February 2009

A rapid plantar flexion perturbation in the early stance phase of walking elicits a large stretch reflex in tibialis anterior (TA). In this study we use repetitive transcranial magnetic stimulation (rTMS) to test if this response is mediated through a transcortical pathway. TA stretch reflexes were elicited in the early stance phase of the step cycle during treadmill walking. Twenty minutes of 1 Hz rTMS at 115% resting motor threshold (MTr) significantly decreased (P < 0.05) the magnitude of the later component of the reflex at a latency of ∼100 ms up to 25 min after the rTMS. Control experiments in which stretch reflexes were elicited during sitting showed no effect on the spinally mediated short and medium latency stretch reflexes (SLR and MLR) while the long latency stretch reflex (LLR) and the motor‐evoked potential (MEP) showed a significant decrease 10 min after 115% MTr rTMS. This study demonstrates that 1 Hz rTMS applied to the leg area of the motor cortex can suppress the long latency TA stretch reflex during sitting and in the stance phase of walking. These results are in line with the hypothesis that the later component of the TA stretch reflex in the stance phase of walking is mediated by a transcortical pathway. An alternative explanation for the observed results is that the reflex is mediated by subcortical structures that are affected by the rTMS. This study also shows that rTMS may be used to study the neural control of walking.
Mutations in the Nonstructural Protein 3A Confer Resistance to the Novel Enterovirus Replication Inhibitor TTP-8307
Authors: De Palma Armando M. , Thibaut Hendrik Jan , van der Linden Lonneke , Lanke Kjerstin , Heggermont Ward , Ireland Stephen , Andrews Robert , Arimilli Murty , Al-Tel Taleb H. , De Clercq Erik , van Kuppeveld Frank , Neyts Johan
Published: February 2009

A novel compound, TTP-8307, was identified as a potent inhibitor of the replication of several rhino- and enteroviruses. TTP-8307 inhibits viral RNA synthesis in a dose-dependent manner, without affecting polyprotein synthesis and/or processing. Drug-resistant variants of coxsackievirus B3 were all shown to carry at least one amino acid mutation in the nonstructural protein 3A. In particular, three mutations located in a nonstructured region preceding the hydrophobic domain (V45A, I54F, and H57Y) appeared to contribute to the drug-resistant phenotype. This region has previously been identified as a hot sport for mutations that resulted in resistance to enviroxime, the sole 3A-targeting enterovirus inhibitor reported thus far. This was corroborated by the fact that TTP-8307 and enviroxime proved cross-resistant. It is hypothesized that TTP-8307 and enviroxime disrupt proper interactions of 3A(B) with other viral or cellular proteins that are required for efficient replication.
Early Postpartum Pharmacokinetics of Lopinavir Initiated Intrapartum in Thai Women
Authors: Cressey Tim R. , Van Dyke Russell , Jourdain Gonzague , Puthanakit Thanyawee , Roongpisuthipong Anuvat , Achalapong Jullapong , Yuthavisuthi Prapap , Prommas Sinart , Chotivanich Nantasak , Maupin Robert , Smith Elizabeth , Shapiro David E. , Mirochnick Mark
Published: February 2009

Lopinavir (LPV) exposure is reduced during the third trimester of pregnancy. We report the pharmacokinetics of standard LPV-ritonavir dosing (400/100 mg twice daily) in the immediate and early postpartum period when initiated during labor. In 16 human immunodeficiency virus-infected Thai women, the median (range) LPV area under the concentration-time curve and maximum and minimum concentrations in plasma were 99.7 (66.1 to 180.5) μg·h/ml, 11.2 (8.0 to 17.5) μg/ml, and 4.6 (1.7 to 12.5) μg/ml, respectively, at 41 (12 to 74) h after delivery. All of the women attained adequate LPV levels through 30 days postpartum. No serious adverse events were reported.
Cleavage of
Escherichia coli
Cytotoxic Necrotizing Factor 1 Is Required for Full Biologic Activity
Authors: Knust Zeynep , Blumenthal Britta , Aktories Klaus , Schmidt Gudula
Published: February 2009

Cytotoxic necrotizing factor 1 (CNF1) is a protein toxin produced by pathogenic
Escherichia coli
strains. CNF1 constitutively activates small GTPases of the Rho family by deamidation of a glutamine, which is crucial for GTP hydrolysis. The toxin is taken up into mammalian cells by receptor-mediated endocytosis and is delivered from late endosomes into the cytosol. Here, we show that an approximately 55-kDa fragment of CNF1, which contains the catalytic domain and an additional part of the toxin, is present in the cytosol. The processing of this fragment requires an acidic pH and insertion of the toxin into the endosomal membrane. We define the cleavage site region as the region located between amino acids 532 and 544 of CNF1. The data provide insight into the complex mechanism of uptake of bacterial toxins into mammalian cells.
Role of LecA and LecB Lectins in
Pseudomonas aeruginosa
-Induced Lung Injury and Effect of Carbohydrate Ligands
Authors: Chemani Chanez , Imberty Anne , de Bentzmann Sophie , Pierre Maud , Wimmerová Michaela , Guery Benoît P. , Faure Karine
Published: February 2009

Pseudomonas aeruginosa
is a frequently encountered pathogen that is involved in acute and chronic lung infections. Lectin-mediated bacterium-cell recognition and adhesion are critical steps in initiating
P. aeruginosa
pathogenesis. This study was designed to evaluate the contributions of LecA and LecB to the pathogenesis of
P. aeruginosa
-mediated acute lung injury. Using an in vitro model with A549 cells and an experimental in vivo murine model of acute lung injury, we compared the parental strain to
lecA
and
lecB
mutants. The effects of both LecA- and Lec B-specific lectin-inhibiting carbohydrates (α-methyl-galactoside and α-methyl-fucoside, respectively) were evaluated. In vitro, the parental strain was associated with increased cytotoxicity and adhesion on A549 cells compared to the
lecA
and
lecB
mutants. In vivo, the
P. aeruginosa
-induced increase in alveolar barrier permeability was reduced with both mutants. The bacterial burden and dissemination were decreased for both mutants compared with the parental strain. Coadministration of specific lectin inhibitors markedly reduced lung injury and mortality. Our results demonstrate that there is a relationship between lectins and the pathogenicity of
P. aeruginosa
. Inhibition of the lectins by specific carbohydrates may provide new therapeutic perspectives.
Generation of High-Titer Neutralizing Antibodies against Botulinum Toxins A, B, and E by DNA Electrotransfer
Authors: Trollet C. , Pereira Y. , Burgain A. , Litzler E. , Mezrahi M. , Seguin J. , Manich M. , Popoff M. R. , Scherman D. , Bigey P.
Published: February 2009

Botulinum neurotoxins are known to be among the most toxic known substances. They produce severe paralysis by preventing the release of acetylcholine at the neuromuscular junction. Thus, new strategies for efficient production of safe and effective anti-botulinum neurotoxin antisera have been a high priority. Here we describe the use of DNA electrotransfer into the skeletal muscle to enhance antiserum titers against botulinum toxin serotypes A, B, and E in mice. We treated animals with codon-optimized plasmid DNA encoding the nontoxic but highly immunogenic C-terminal heavy chain fragment of the toxin. By employing both codon optimization and the electrotransfer procedure, the immune response and corresponding neutralizing antiserum titers were markedly increased. The cellular localization of the antigen and the immunization regimens were also shown to increase neutralizing titers to >100 IU/ml. This study demonstrates that DNA electrotransfer is an effective procedure for raising neutralizing antiserum titers to remarkably high levels.
Differences in Genome Content among
Helicobacter pylori
Isolates from Patients with Gastritis, Duodenal Ulcer, or Gastric Cancer Reveal Novel Disease-Associated Genes
Authors: Romo-González Carolina , Salama Nina R. , Burgeño-Ferreira Juan , Ponce-Castañeda Veronica , Lazcano-Ponce Eduardo , Camorlinga-Ponce Margarita , Torres Javier
Published: February 2009

Helicobacter pylori
establishes a chronic infection in the human stomach, causing gastritis, peptic ulcer, or gastric cancer, and more severe diseases are associated with virulence genes such as the
cag
pathogenicity island (PAI). The aim of this work was to study gene content differences among
H. pylori
strains isolated from patients with different gastroduodenal diseases in a Mexican-Mestizo patient population.
H. pylori
isolates from 10 patients with nonatrophic gastritis, 10 patients with duodenal ulcer, and 9 patients with gastric cancer were studied. Multiple isolates from the same patient were analyzed by randomly amplified polymorphic DNA analysis, and strains with unique patterns were tested using whole-genome microarray-based comparative genomic hybridization (aCGH). We studied 42 isolates and found 1,319 genes present in all isolates, while 341 (20.5%) were variable genes. Among the variable genes, 127 (37%) were distributed within plasticity zones (PZs). The overall number of variable genes present in a given isolate was significantly lower for gastric cancer isolates. Thirty genes were significantly associated with nonatrophic gastritis, duodenal ulcer, or gastric cancer, 14 (46.6%) of which were within PZs and the
cag
PAI. Two genes (HP0674 and JHP0940) were absent in all gastric cancer isolates. Many of the disease-associated genes outside the PZs formed clusters, and some of these genes are regulated in response to acid or other environmental conditions. Validation of candidate genes identified by aCGH in a second patient cohort allowed the identification of novel
H. pylori
genes associated with gastric cancer or duodenal ulcer. These disease-associated genes may serve as biomarkers of the risk for severe gastroduodenal diseases.
T Cells from Lungs and Livers ofFrancisella tularensis-Immune Mice Control the Growth of Intracellular Bacteria
Authors: Collazo Carmen M. , Meierovics Anda I. , De Pascalis Roberto , Wu Terry H. , Lyons C. Rick , Elkins Karen L.
Published: February 2009

Parenteral and respiratory vaccinations with the intracellular bacteriumFrancisella tularensishave been studied using the live vaccine strain (LVS) in a mouse model, and spleen cells from immune mice are often used for immunological studies. However, mechanisms of host immunological responses may be different in nonlymphoid organs that are important sites of infection, such as lung and liver. Using parenteral (intradermal) or respiratory (cloud aerosol) vaccination, here we examine the functions of resulting LVS-immune liver or lung cells, respectively. Surprisingly, LVS was considerably more virulent when administered by cloud aerosol than by intranasal instillation, suggesting method-dependent differences in initial localization and/or dissemination patterns. Only low doses were sublethal, and resolution of sublethal cloud aerosol infection was dependent on gamma interferon (IFN-γ), tumor necrosis factor alpha, and inducible nitric oxide synthase. Nonetheless, survival of cloud aerosol or parenteral infection resulted in the development of a protective immune response against lethal LVS intraperitoneal or aerosol challenge, reflecting development of systemic secondary immunity in both cases. Such immunity was further detected by directly examining the functions of LVS-immune lung or liver lymphocytes in vitro. Lung lymphocytes primed by respiratory infection, as well as liver lymphocytes primed by parenteral infection, clearly controlled in vitro intracellular bacterial growth primarily via mechanisms that were not dependent on IFN-γ activity. Thus, our results indicate functional similarities between immune T cells residing in spleens, livers, and lungs of LVS-immune mice.
Contribution of Flagellin Pattern Recognition to Intestinal Inflammation duringSalmonella entericaSerotype Typhimurium Infection
Authors: Winter Sebastian E. , Thiennimitr Parameth , Nuccio Sean-Paul , Haneda Takeshi , Winter Maria G. , Wilson R. Paul , Russell Joseph M. , Henry Thomas , Tran Quynh T. , Lawhon Sara D. , Gomez Gabriel , Bevins Charles L. , Rüssmann Holger , Monack Denise M. , Adams L. Garry , Bäumler Andreas J.
Published: February 2009

Salmonella entericaserotype Typhimurium causes acute inflammatory diarrhea in humans. Flagella contribute to intestinal inflammation, but the mechanism remains unclear since most mutations abrogating pattern recognition of flagellin also prevent motility and reduce bacterial invasion. To determine the contribution of flagellin pattern recognition to the generation of innate immune responses, we compared in two animal models a nonmotile, but flagellin-expressing and -secreting serotype Typhimurium strain (flgKmutant) to a nonmotile, non-flagellin-expressing strain (flgK fliC fljBmutant). In vitro, caspase-1 can be activated by cytosolic delivery of flagellin, resulting in release of the interferon gamma inducing factor interleukin-18 (IL-18). Experiments with streptomycin-pretreated caspase-1-deficient mice suggested that induction of gamma interferon expression in the murine cecum early (12 h) after serotype Typhimurium infection was caspase-1 dependent but independent of flagellin pattern recognition. In addition, mRNA levels of the CXC chemokines macrophage inflammatory protein 2 and keratinocyte-derived chemokine were markedly increased early after serotype Typhimurium infection of streptomycin-pretreated wild-type mice regardless of flagellin expression. In contrast, in bovine ligated ileal loops, flagellin pattern recognition contributed to increased mRNA levels of macrophage inflammatory protein 3α and more fluid accumulation at 2 h after infection. Collectively, our data suggest that pattern recognition of flagellin contributes to early innate host responses in the bovine ileal mucosa but not in the murine cecal mucosa.
Stimulation of the Molecule 4-1BB Enhances Host Defense againstListeria monocytogenesInfection in Mice by Inducing Rapid Infiltration and Activation of Neutrophils and Monocytes
Authors: Lee Sang-Chul , Ju Seong-A , Sung Boo-Hee , Heo Sook-Kyoung , Cho Hong Rae , Lee Eun A. , Kim Jung Dae , Lee In Hee , Park Sang-Min , Nguyen Quang Tam , Suh Jae-Hee , Kim Byung-Sam
Published: February 2009

The tumor necrosis factor receptor family molecule 4-1BB (CD137) has diverse roles in adaptive and innate immune responses. However, little is known of its role in bacterial infections. Previously, we showed that 4-1BB-deficient mice have enhanced susceptibility toListeria monocytogenesinfection, and mice pretreated with agonistic anti-4-1BB antibody (3E1) were much more resistant toL. monocytogenesinfection than mice treated with control antibody. In this study, we report that stimulating 4-1BB by administering 3E1 in the early phase ofL. monocytogenesinfection is critical for promoting the survival of mice by inducing rapid infiltration of neutrophils and monocytes intoL. monocytogenes-infected livers. The levels of tumor necrosis factor alpha, interleukin 6, and monocyte chemoattractant protein 1 in the livers of 3E1-treated mice increased as early as 30 min postinfection and peaked by 1 to 2 h, while those in mice treated with control antibody started to increase only at 16 h postinfection. Monocytes and neutrophils from the 3E1-treated mice had higher levels of activation markers, phagocytic activity, and reactive oxygen species than those from control mice. In vitro stimulation of 4-1BB induced the production of the inflammatory cytokines/chemokines of neutrophils, but not those of monocytes. These results suggest that 4-1BB stimulation of neutrophils in the early phase ofL. monocytogenesinfection causes rapid production of inflammatory cytokines/chemokines and that the subsequent infiltration of neutrophils and monocytes is crucial for eliminating the infectingL. monocytogenes.
Immunological Determinants of Clinical Outcome in Peruvian Patients with Tegumentary Leishmaniasis Treated with Pentavalent Antimonials
Authors: Maurer-Cecchini Anne , Decuypere Saskia , Chappuis François , Alexandrenne Coralie , De Doncker Simonne , Boelaert Marleen , Dujardin Jean-Claude , Loutan Louis , Dayer Jean-Michel , Tulliano Gianfranco , Arevalo Jorge , Llanos-Cuentas Alexandro , Chizzolini Carlo
Published: February 2009

The mechanisms linking the immune response to cutaneous and mucosal leishmaniasis (CL and ML, respectively) lesions and the response to treatment are incompletely understood. Our aims were to prospectively assess, by quantitative reverse transcription-PCR, the levels of mRNA for gamma interferon, tumor necrosis factor alpha, interleukin-10 (IL-10), IL-4, and IL-13, as well as the presence of T cells (CD2) and macrophages (CD68), in CL and ML lesions and to follow their changes in response to treatment with pentavalent antimonials. The leishmanin skin test (LST) was performed on all CL and ML patients before treatment. The patient population included individuals living in areas of Peru where the disease is endemic, i.e., 129 with CL and 43 with ML. Compared to CL patients, the LST induration size was larger, the levels of all cytokine mRNAs but IL-10 were higher, T-cell mRNA was similar, and macrophage mRNA was lower in ML patients. The proportion of CL patients with an LST induration size of >8 mm was higher among responders to treatment. In CL, the pretreatment levels of cytokine mRNAs did not discriminate between responders and nonresponders; however, treatment was more often accompanied by a reduction in the levels of T-cell and cytokine mRNAs in responders than in nonresponders. Furthermore, the production of cytokines per T cell and macrophage decreased with treatment but IL-10 production remained high in nonresponders. Overall, these findings point to complex relationships among New World
Leishmania
parasites, skin and mucosal immune responses, and treatment outcome. The persistence of high levels of IL-10 in CL is characteristically associated with a poor response to treatment.
Chronic pelvic pain in women
Authors: Vincent K
Published: February 2009

Chronic pelvic pain is a major public health problem for women throughout the developed world. The complex innervation of the pelvis and the anatomical proximity of pelvic viscera mean this symptom frequently overlaps traditional medical specialties, leading to diagnostic delay and frequently inadequate treatment. Careful history taking and examination can in itself be therapeutic and will likely identify a number of causal and perpetuating factors which should be managed within the context of a multidisciplinary clinic.
Are Age-Structured Models Appropriate for Catch-Effort Data?
Authors: Ludwig Donald , Walters Carl J.
Published: February 2009

Simulated data have been used to evaluate the performance of schemes for estimating optimum fishing effort using a simple stock-production model and R. B. Deriso's age-structured model Even when the data are generated using Deriso's model, the simpler production model generally gives as good or better estimates for the optimal effort. The only exception to this result is when data are provided with unrealistically large contrasts in effort and catch per unit effort over time. The implication of these findings is that simple production models should often be used in stock assessments based on catch/effort data, even when more realistic and structurally correct models are available to the analyst; the best choice depends on how much contrast has occurred in the historical effort and catch per unit effort data, rather than on prior knowledge about which model structure is biologically more realistic.
Responses ofIsonychia bicolorto Alkaline pH: An Evaluation of Survival, Oxygen Consumption, and Chloride Cell Ultrastructure
Authors: Peters Gregory T. , Cherry Donald S. , Cairns Jr. John
Published: February 2009

The toxicity of alkaline pH to the mayfly, Isonychia bicolor, was evaluated in field and laboratory artificial stream bioassays, respiration analyses, and transmission electron microscope studies of chloride cell ultrastructure. In continuous-exposure, 96-h bioassays, field and laboratory LC50 values ranged from pH 9.54 to 10.37, respectively. While intermittent pH bioassays involving 8- or 4-h exposures per day failed to reduce alkaline pH toxicity, 1-h intermittent exposures were less toxic (P < 0.05) than continuous exposures. Acute (4-h) exposures to lethal (pH 11.0) and sublethal (pH 10.0) levels caused reductions (P < 0.05) in oxygen consumption relative to that at pH 8.0. Oxygen consumption at pH 11.0 was greater (P < 0.05) than that at pH 10.0. Coniform chloride cells continuously exposed to pH 11.0 for 96 h accumulated fluid near the porous plate, and these fluid accumulations displaced cytoplasm from the apical region of the cell complexes. Chloride cells intermittently exposed to pH 11.0 (1 h per day for 96 h) appeared similar to those continuously exposed to pH 11.0, indicating that the damaging effects of 1-h exposures exceeded the rehabilitory effects of daily, 23-h recovery periods. Structural recovery (95%) occurred within 8 d following the cessation of intermittent exposure to pH 11.0.
Relationship of Crayfish (Orconectes virilis) Growth to Population Abundance and System Productivity in Small Oligotrophic Lakes in the Experimental Lakes Area, Northwestern Ontario
Authors: France R. L.
Published: February 2009

Crayfish growth in four lakes in the Experimental Lakes Area (ELA) was examined by analysis of size-frequency distributions, molt increment data, and calculation of instantaneous growth and mean size at onset of sexual maturity. Orconectes virilis growth rates at ELA are only 27–38% of those reported for other areas. Growth varied both among study lakes and between years. Higher temperatures and a longer growing season during 1980 increased growth an average of 12% over that of the preceding year. Crayfish growth and maximum size in four to six lakes were significantly correlated with phytoplankton production and chlorophyll a concentration. Growth regulated both the number of age 1 animals attaining sexual maturity and the per capita egg production, and was also directly related to the proportion of mature females that were fertilized. I believe population regulation is mediated through alterations in reproductive capacity that is correlated with system productivity.
Chemistry of Lake Hovvatn, Norway, Following Liming and Reacidification
Authors: Wright Richard F.
Published: February 2009

Hovvatn, a 1-km2, chronically acidified lake in southernmost Norway, was treated with 200 metric tons of powdered limestone in March 1981. An additional 40 metric tons was added to a 0.046-km2pond (Pollen) draining into Hovvatn. At ice-out, pH rose from 4.4 to 6.3 (Hovvatn) and 7.5 (Pollen), Ca and alkalinity increased, and total Al decreased by about 120 μg/L. The amount of limestone dissolved, calculated from the lake Ca budgets, was 50% after 3.5 yr in Hovvatn and 25% in Pollen. A greater fraction dissolved at Hovvatn because the limestone lay in the active surf zone. In Pollen, limestone that was not dissolved at ice-out formed a layer on the sediment surface from which only minimal dissolution occurred. Hovvatn and Pollen reacidified to pH 4.9 and 5.5, respectively, 3 yr after liming. A simple flushing model describes the reacidification of Pollen. In Hovvatn, however, dissolution of additional limestone during the 3.5 yr since liming has considerably slowed reacidification.
Effective Solvents and Extraction Periods Employed in Phytoplankton Carotenoid and Chlorophyll Determinations
Authors: Bowles N. Dean , Paerl Hans W. , Tucker Jane
Published: February 2009

Using high-performance liquid chromatography (HPLC), we showed that spectrophotometric determinations of algal lipophilic pigments are often biased by the choice of extraction solvent. Several commonly used extraction solvents and extraction periods were tested on diverse phytoplankton species isolated from the Neuse River, NC. Extraction solvents included 100% acetone, 90% acetone – 10% distilled deionized water (DDW), 50% acetone – 50% methanol, and 90% methanol – 10% DDW. Extraction efficiencies varied significantly among genera. For the diatom Cyclotella meneghiniana, at least three solvents extracted all lipophilic pigments with equal efficiency, but 50:50 acetone–methanol was clearly superior for the chlorophycean Chlorella vulgaris. A host of differences in extraction efficiencies and extraction times were observed when we compared eukaryotic with prokaryotic (blue-green algae) phytoplankton. We were unable to find a single extraction technique that could consistently provide quantitative and uniform pigment yields from diverse phytoplankton communities. Nevertheless, HPLC techniques can be rapidly and routinely employed to determine appropriate extraction protocols for lipophilic pigments of interest in specific aquatic ecosystems.
The Influence of Fish–Zooplankton–Phytoplankton Interactions on the Results of Selenium Toxicity Experiments Within Large Enclosures
Authors: Salki A. , Turner M. , Patalas K. , Rudd J. , Findlay D.
Published: February 2009

The response of zooplankton to sodium selenite at concentrations of 1,10, and 100 μg Se∙L−1was studied using large (100 m3) enclosures in mercury-contaminated Clay Lake, Ontario (50°03′N, 90°30′W). Crustacean community development in treated enclosures exhibited no obvious acute or chronic effects from the range of selenium concentrations applied. Seasonal changes in zooplankton composition, abundance, and reproduction were similar among controls and the 1 and 10μg Se∙L−1enclosures. Differences in species dynamics observed in the 100 μg Se∙L−1enclosure and in a sediment control enclosure were attributable to biotic interactions rather than selenium. Predation appeared to be the dominant factor governing zooplankton community structure in all enclosures. Differences in the number of planktivorous fish among enclosures led to variations in the abundance of predatory Leptodora kindtii, which in turn affected abundances of the small cladoceran Bosmina longirostris.
Energy Flow Between the Pelagic and Benthic Zones: Factors Controlling Particulate Organic Matter Available to an Intertidal Mussel Bed
Authors: Fréchette Marcel , Bourget Edwin
Published: February 2009

Fluctuations and vertical gradients of particulate organic matter (POM, as indicated by chlorophyll a and phaeopigments) concentration over an intertidal mussel bed were studied over fortnightly tidal cycles. Chlorophyll a variations were not associated with wave amplitude, tidal energy, and sigma-t, and phaeopigment concentration was correlated positively with wave amplitude only. Comparison of total pigment concentration in water pumped simultaneously from within 5 cm and from 50 cm above the mussel bed showed significant depletion of POM nearest to the mussel bed throughout the first of the two fortnightly tidal cycles studied. During this period, POM depletion was negatively correlated with current speed, but not with mussel filtration rate, nor with wave energy. During the other period, POM depletion was significant in three of the six semidiurnal tidal cycles studied, and depletion was negatively correlated with wave energy only. Our data indicate that food is often depleted immediately above mussel populations, and that water movement is critical in determining food availability for suspension feeders.
Food-Limited Growth of Mytilus edulis L. in Relation to the Benthic Boundary Layer
Authors: Fréchette Marcel , Bourget Edwin
Published: February 2009

The hypothesis that depletion of organic particles near the sediment limits the growth of benthic suspension feeders was tested. In situ growth of Mytilus edulis L. was significantly depressed at the sediment–water interface, as compared with growth 1.0 m above the mussel bed, in studies at two shore levels. Flesh dry weight was sensitive to treatment effects, but not shell growth. We conclude that mussels from the bed were food limited.
The Distribution and Abundance of Seals in the Canadian High Arctic, 1980–82
Authors: Kingsley M. C. S. , Stirling I. , Calvert W.
Published: February 2009

Surveys of hauled-out ringed seals (Phoca hispida) and bearded seals (Erignathus barbatus) were flown in 1980 and 1981 over Jones Sound, the Sverdrup Basin, the channels between the Parry Islands, the Parry Channel, Prince of Wales Strait, and northern Amundsen Gulf. Part of the survey was flown again in 1982. Ringed seals were most numerous in Barrow Strait and Wellington Channel, their density decreasing westward and northward. Their preferred habitat was annual ice, fast or cracking, of high cover; they avoided deep water. Bearded seals were seen in low numbers in early-opening areas, preferring floe or rotten ice of moderate or low cover over shallow water.
Implications of Fluctuations in Recruitment in Selected Crab Populations
Authors: Jamieson G. S.
Published: February 2009

Two general categories of crab fisheries exist, shallow-water, nearshore fisheries (e.g. Cancer, Callinectes) and deepwater, offshore fisheries (e.g. Paralithodes, Chionoecetes). Species in the former category are managed typically in a passive manner with no annual restriction of catch on the basis of population abundance, whereas species in the latter category tend to be managed actively through annual catch quotas. Active management of fisheries requires regular resource surveys and provides the most comprehensive data base for recruitment study. Recruitment fluctuations in crab populations are analyzed by considering (1) production of progeny from perceived parent populations, (2) mechanisms which determine magnitude of progeny return to fishery grounds, and (3) factors that determine survival of juveniles. It is concluded that year-class strength at recruitment can be established at any preceding life stage and that while one life stage may appear more critical than others for a given population in a given year, this is unlikely to be the case in future years or apply to different populations. There is little evidence that recruitment magnitude in crab populations has been influenced by past resource management. Management has not stabilized landings in any fishery over the long term, and environmental variables seem to be the major factor influencing recruitment level. The need for prediction of future fishery performance is greatest in actively managed fisheries, with short-term economic benefits and socially acceptable exploitation, not control of recruitment, being the most likely achievement of management.
Problems and Perspectives Regarding Recruitment of Spiny Lobsters, Panulirus argus, to the South Florida Fishery
Authors: Lyons William G.
Published: February 2009

Inappropriate minimum size, illegal harvest, fishery-induced juvenile growth retardation and mortality, and excessive effort have reduced reproductive contributions and depressed yield-per-recruit in the overcapitalized south Florida spiny lobster (Panulirus argus) fishery. Measures recommended to improve yield-per-recruit are as follows: increase minimum legal size to 85–90 mm carapace length; require escape gaps in traps; eliminate possession of sublegal lobsters aboard vessels; prohibit harvest in nurseries; reduce fishing effort; improve enforcement of fishery regulations; and initiate programs to educate fishermen regarding impacts of fishery practices. International management is recommended to assure larval recruitment among Pan-Caribbean stocks.
La répartition horizontale et verticale des larves de homard (Homarus americanus) autour des îles de la Madeleine, golfe du Saint-Laurent
Authors: Hudon Christiane , Fradette Pierre , Legendre Pierre
Published: February 2009

Thirty-nine stations localized around the eastern tip of the Îles de la Madeleine, in two lagoons, and in the baie de Plaisance were sampled using plankton net tows during the summers of 1978, 1980, and 1981. The horizontal and vertical distributions of each of the four larval stages of Homarus americanus were assessed from sets of surface tows using simple neuston and meter nets (1978 and 1980) as well as a three-compartment plankton net (1981). Most of the stage I larval production takes place in the northeast and southeast regions. However, the abundance of stage IV larvae is low in the southeast and almost nil in the northeast. By contrast, the baie de Plaisance harbors very few stage I larvae, but a very high proportion of stage III and IV larvae. The periods of first appearance and maximum abundance are also out of phase for the three regions, occurring in the northeast before the southeast and the baie de Plaisance. These results suggest that the general pattern of abundance of larvae is driven by the current regime, flushing the larvae around the Pointe de l'Est and concentrating them in the baie de Plaisance following a gyre. On a smaller scale, 12 stations arranged in a 3 × 4 grid in the baie de Plaisance were sampled for 12 wk in the summer of 1980. The first three larval stages show a strongly aggregated distribution and are most frequent at the mouth of the bay. Conversely, stage IV larvae are found more frequently in the shore stations and inside the bay. There is a significant correlation between stage IV larval abundance and the distance to rocky bottoms favorable to benthic life. The vertical distribution of larvae at two stations (1981) shows that only the stage I larvae have a vertical distribution related to light intensity, being found in highest abundance in the surface layer (0–0.8 m) at dusk and dawn. Stage I larvae were uniformly distributed between 0 and 1.6 m during the day and down to 2.4 m at night. Stage II, III, and IV larvae were always found near the surface.
Swimming Ability of Larval American Lobsters, Homarus americanus, in Flowing Water
Authors: Ennis G. P.
Published: February 2009

The swimming capacity of American lobster, Homarus americanus, larvae in flowing water was observed in a screened-off portion of a flow tank. At a flow rate of 2 cm∙s−1, stage I–III larvae were swimming for 46–74% of the observations during the first 5 min but this ranged from 0 to 28% toward the end of a 30-min period. At higher flow rates, however, very few of these larvae were able to continue swimming longer than 5 min. Newly molted stage IV larvae displayed substantially improved swimming ability compared with earlier stages. At 2 cm∙s−1, these larvae were swimming for 40–48% of the observations over the 30-min period, although at higher flow rates their capacity to continue swimming was also limited and few were observed swimming longer than 10 min. Older stage IV larvae were more capable swimmers than newly molted stage IV larvae and displayed a capacity to continue swimming over the 30-min observation period at flow rates up to 9 cm∙s−1. In flowing water, the frequency of orientation in the upstream direction for larvae that were swimming was higher than for control larvae. For stage IV larvae especially, this frequency was higher at the higher flow rates. The observations demonstrate the presence of a rheotactic response in all larval stages of the American lobster. The response is relatively weak in stages I–III but strong in stage IV.
Migratory Movements of Ovigerous Lobsters, Homarus americanus, Tagged off Grand Manan, Eastern Canada
Authors: Campbell Alan
Published: February 2009

A total of 2139 ovigerous lobsters, Homarus americanus, were tagged and egg development recorded off Grand Manan, eastern Canada, during 1982–83. Recaptures during August 1982 to January 1984 totaled 1877, representing 1046 individuals including 457 that were captured 2–10 times. The single recapture data indicate that the majority (75%) of the lobsters moved < 15 km. Use of distance moved information from single recaptures of lobsters at liberty for long periods can be misleading, since exact distance moved between tag release–recapture points usually is unknown. Multiple recapture and depth at recapture data gave more information on the movements of the lobsters. Many lobsters showed seasonal shallow-deep migrations of > 20 km with recaptures in shallow (< 20 m) water during summer–fall and in deep (> 200 m) water during winter–spring. Many ovigerous females returned to the Grand Manan area the following summer. A few (7%) moved north > 30 km into the Bay of Fundy and south as much as 322 km along the coastline of Maine. Examination of the multiple recapture data between months indicated positive correlations between change in depth, distance moved, and water temperature. The seasonal depth migrations of ovigerous lobsters appear to be associated with maximizing temperatures which provide sufficient degree-days for completion of egg development. Also, hatching eggs in relatively warm shallow waters may confer a survival advantage for pelagic lobster larvae by decreasing development time to the benthic stage.
Evidence of Migration and Homing of Lobsters (Homarus americanus) on the Scotian Shelf
Authors: Pezzack D. S. , Duggan D. R.
Published: February 2009

In the Browns Bank region of the Scotian Shelf between June 1982 and December 1983, 6285 tagged lobsters (Homarus americanus) were released. Of the 2486 lobsters recaptured, 361 were recaptured more than once. Eight lobsters released in late May to mid-July were recaptured the following spring and summer, with at least one intervening recapture in the fall–winter period. Five of the eight lobsters showed homing tendencies. Two lobsters made long-distance (> 200 km) return migrations, three made short (50–100 km) return migrations, and three moved long distances but did not return. One lobster at large 6 mo and four at large 22–34 mo made long-distance return migrations, moving over 200 km and returning to within 9–42 km of the initial release site. The data indicate that some lobsters undertake long-distance return migration, which returns the lobsters to specific sections of the Shelf.
Settlement of Spiny Lobster, Panulirus argus, Pueruli in South Florida: An Evaluation from Two Perspectives
Authors: Marx J. M.
Published: February 2009

Settlement of spiny lobster, Panulirus argus, pueruli occurs year-round in south Florida, but seasonal trends are not consistent. Recruitment peaks are common in spring but sometimes occur in other seasons. Postsettlement dynamics of seasonal settlement classes must be determined to establish a relationship between puerulus abundance and subsequent fishery yield. Pueruli settle in various shallow-water habitats, including masses of the red alga Laurencia, algal-covered mangrove roots, and colonies of the bryozoan, Bugula. Settlement habitats of 0.04–2 ha can produce 1906–3913 juveniles (20 mm carapace length) annually. Management must protect these critical habitats to assure productivity of the spiny lobster fishery.
Movements of the Spiny LobsterPanulirus argusin South Florida
Authors: Gregory Jr. Douglas R. , Labisky Ronald F.
Published: February 2009

Long-distance movements of the spiny lobster Panulirus argus were studied in two Gulf of Mexico habitats (Shallows, Mid-depth) and three Atlantic Ocean habitats (Shallows, Patch Reef, and Deep Reef) in the lower Florida Keys during the mid-1970's. Of 6062 spiny lobsters tagged and released at the five sites between June 1975 and August 1976, 465 of the 771 (13%) lobsters recovered yielded usable movement data. Eighty percent of the tags were recovered within the first 3 mo of the 8 mo commercial fishing season (July 26 – March 31). Directions and rates of movements differed significantly (P < 0.05) among sites. Movements from Gulf sites were generally oriented to the west and southwest, toward the Atlantic offshore reefs, at mean displacement velocities of 0.57 km/d (Mid-depth) and 0.24 km/d (Shallows). Movements of lobsters from the Atlantic sites were principally eastward and westward, parallel to the reef line and island chain, at mean displacement velocities of 0.02 km/d (Deep Reef) and 0.05 km/d (Shallows, Patch Reef). The more directed movements of spiny lobsters from Gulf sites may reflect a migration from nursery grounds to the Atlantic reefs, which not only constitute the primary spawning habitat but also exhibit a more stable winter environment than the shallow Gulf. Movements of spiny lobsters within Atlantic waters reflect localized random onshore–offshore dispersal patterns typical within reef environments.
Multiple Fertilization and Consecutive Spawning in Large American Lobsters, Homarus americanus
Authors: Waddy S. L. , Aiken D. E.
Published: February 2009

Large female American lobsters, Homarus americanus (> 120 mm carapace length), maintained at nearshore Bay of Fundy temperatures often spawn twice without an intervening molt (consecutive spawning). Consecutive spawning occurs in two forms: successive-year (spawning in two successive summers, a molt in the first and fourth years) and alternate-year (spawning in alternate summers, a molt in the first and fifth years). In both types, females often are able to fertilize the two successive broods with the sperm from a single insemination (multiple fertilization). Twenty of 21 large females that were held for up to 13 yr displayed one of these types of consecutive spawning. Consecutive spawning and multiple fertilization enable large lobsters to spawn more frequently over the long term than their smaller counterparts. This, combined with the logarithmic relationship between body size and numbers of eggs produced, means that very large lobsters have a much greater relative fecundity than previously thought.
Epizootic Infestations by Nemertean Brood Parasites on Commercially Important Crustaceans
Authors: Wickham Daniel E.
Published: February 2009

Historical literature presenting quantitative information on the interaction between nemertean brood parasites of crustaceans and their hosts is reviewed and compared with recent detailed studies on epizootics of these parasites. Observations over the last century demonstrate that nemertean infestations on most host species are of low intensity and result in relatively low levels of host brood mortality. Epizootics discovered in the last decade on certain host species have resulted in extensive egg loss in many important commercial crustacean stocks. The data at hand suggest that epizootics are primarily restricted to commercially exploited species of decapods. One implication of this is that human exploitation affects natural host–parasite balance.