bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vivo Interactions between Toxin-Antitoxin Proteins Epsilon and Zeta of Streptococcal Plasmid pSM19035 in
Saccharomyces cerevisiae
Authors: Zielenkiewicz Urszula , Kowalewska Magdalena , Kaczor Celina , Cegłowski Piotr
Published: April 2009

The widespread prokaryotic toxin-antitoxin (TA) systems involve conditional interaction between two TA proteins. The interaction between the Epsilon and Zeta proteins, constituting the TA system of plasmid pSM19035 from
Streptococcus pyogenes
, was detected in vivo using a yeast two-hybrid system. As we showed using
Saccharomyces cerevisiae
, the Zeta toxin hybrid gene also exerts its toxic effects in a dose-dependent manner in eukaryotic cells. Analysis of mutant proteins in the two-hybrid system demonstrated that the N-terminal part of Zeta and the N-terminal region of Epsilon are involved in the interaction. The N-terminal region of the Zeta protein and its ATP/GTP binding motif were found to be responsible for the toxicity.
Elevated Mutation Frequency in Surviving Populations of Carbon-Starved
rpoS
-Deficient
Pseudomonas putida
Is Caused by Reduced Expression of Superoxide Dismutase and Catalase
Authors: Tarassova Kairi , Tegova Radi , Tover Andres , Teras Riho , Tark Mariliis , Saumaa Signe , Kivisaar Maia
Published: April 2009

RpoS is a bacterial sigma factor of RNA polymerase which is involved in the expression of a large number of genes to facilitate survival under starvation conditions and other stresses. The results of our study demonstrate that the frequency of emergence of base substitution mutants is significantly increased in long-term-starved populations of
rpoS
-deficient
Pseudomonas putida
cells. The increasing effect of the lack of RpoS on the mutation frequency became apparent in both a plasmid-based test system measuring Phe
+
reversion and a chromosomal
rpoB
system detecting rifampin-resistant mutants. The elevated mutation frequency coincided with the death of about 95% of the cells in a population of
rpoS
-deficient
P
.
putida
. Artificial overexpression of superoxide dismutase or catalase in the
rpoS
-deficient strain restored the survival of cells and resulted in a decline in the mutation frequency. This indicated that, compared to wild-type bacteria,
rpoS
-deficient cells are less protected against damage caused by reactive oxygen species. 7,8-Dihydro-8-oxoguanine (GO) is known to be one of the most stable and frequent base modifications caused by oxygen radical attack on DNA. However, the spectrum of base substitution mutations characterized in
rpoS
-deficient
P
.
putida
was different from that in bacteria lacking the GO repair system: it was broader and more similar to that identified in the wild-type strain. Interestingly, the formation of large deletions was also accompanied by a lack of RpoS. Thus, the accumulation of DNA damage other than GO elevates the frequency of mutation in these bacteria. It is known that oxidative damage of proteins and membrane components, but not that of DNA, is a major reason for the death of cells. Since the increased mutation frequency was associated with a decline in the viability of bacteria, we suppose that the elevation of the mutation frequency in the surviving population of carbon-starved
rpoS
-deficient
P
.
putida
may be caused both by oxidative damage of DNA and enzymes involved in DNA replication and repair fidelity.
InEscherichia coli, MreB and FtsZ Direct the Synthesis of Lateral Cell Wall via Independent Pathways That Require PBP 2
Authors: Varma Archana , Young Kevin D.
Published: April 2009

InEscherichia coli, the cytoplasmic proteins MreB and FtsZ play crucial roles in ensuring that new muropeptide subunits are inserted into the cell wall in a spatially correct way during elongation and division. In particular, to retain a constant diameter and overall shape, new material must be inserted into the wall uniformly around the cell's perimeter. Current thinking is that MreB accomplishes this feat through intermediary proteins that tether peptidoglycan synthases to the outer face of the inner membrane. We tested this idea inE. coliby using add-carboxypeptidase mutant that accumulates pentapeptides in its peptidoglycan, allowing us to visualize new muropeptide incorporation. Surprisingly, inhibiting MreB with the antibiotic A22 did not result in uneven insertion of new wall, although the cells bulged and lost their rod shapes. Instead, uneven (clustered) incorporation occurred only if MreB and FtsZ were inactivated simultaneously, providing the first evidence inE. colithat FtsZ can direct murein incorporation into the lateral cell wall independently of MreB. Inhibiting penicillin binding protein 2 (PBP 2) alone produced the same clustered phenotype, implying that MreB and FtsZ tether peptidoglycan synthases via a common mechanism that includes PBP 2. However, cell shape was determined only by the presence or absence of MreB and not by the even distribution of new wall material as directed by FtsZ.
Preparation of steroid sulfamates and their interaction with GABAA receptor
Authors: Kapras Vojtěch , Šťastná Eva , Chodounská Hana , Pouzar Vladimír , Krištofíková Zdena
Published: April 2009

Sulfamoyl chloride was used for the preparation of 3α- and 3β-sulfamates of steroids: 20-oxo-5α-pregnan-3α-yl sulfamate (4), 20-oxo-5α-pregnan-3β-yl sulfamate (5), 20-oxo-5β-pregnan-3α-yl sulfamate (7), and 20-oxo-5β-pregnan-3β-yl sulfamate (9) from the corresponding 3α- and 3β-alcohols. Sulfur trioxide–pyridine complex was employed for the preparation of 20-oxo-5α-pregnan-3α-yl pyridinium sulfate (10). The specific steroid binding was detected by the decrease of the specific [35S]-tert-butylbicyclo[2.2.2]phosphorothionate binding after application of the tested compounds.
Morphometric and Electrophoretic Approaches to Discrimination of Capelin (Mallotus villosus) Populations in the Estuary and Gulf of St. Lawrence
Authors: Roby D. , Lambert J. D. , Sévigny J. M.
Published: April 2009

The degree of differentiation between capelin (Mallotus villosus) populations in the Estuary and Gulf of St. Lawrence was evaluated using conventional and truss morphometric analyses together with electrophoretic analyses of protein-coding loci. Samples of spawning fish were collected in the same year at eight sites across NAFO divisions 4R, 4S, and 4T. While the results of conventional morphometric analyses were not conclusive, truss and electrophoretic analyses differentiated the sampled sites along an east–west axis. Two samples (one from the Southern Gulf and the other from the Northeastern Gulf) did not follow this trend. Processes are suggested to explain this pattern. Variations in allelic frequencies among age-classes of fish have been observed in some samples and may be attributed to selective environmental pressures. This could explain the apparent population differentiation observed, although the distribution of the alleles revealed a high gene flow.
Responses of Stream Periphyton and Benthic Insects to Increases in Dissolved Inorganic Phosphorus in a Mesocosm
Authors: Mundie J. H. , Simpson K. S. , Perrin C. J.
Published: April 2009

Responses of stream periphytic algae and benthic insects to increases in dissolved inorganic phosphorus (P) were assessed in a streamside mesocosm. Controls and treatments were colonized continuously in summer by biota from the stream. P was maintained in the treatments at 10 μg∙L−1, [Formula: see text] times the concentration in the controls. In the treatments the biomass of chlorophyll a reached 3.5 times that of the controls, accompanied by an increase in Cyanophyta relative to diatoms. No difference was detectable in the numbers of insects drifting from controls and treatments. Numbers of individuals emerging (> 40 species) from the treatments over 7 wk were 2.2 times those from the controls. In both controls and treatments, 77% or more of emerging insects were Chironomidae. After week 7 the density of benthic insects in the treatments, determined without size selection, was 1.75 times that of the controls; size distributions in treatments and controls were similar. Addition of P, therefore, increased the food of insects and resulted in a doubling of their survival to emergence.
Growth, Parr–Smolt Transformation, and Changes in Growth Hormone of Atlantic Salmon (Salmo salar) Reared under Different Photoperiods
Authors: Stefansson Sigurd O. , Bjömsson Björn Th. , Hansen Tom , Haux Carl , Taranger G. Lasse , Saunders Richard L.
Published: April 2009

Potential 1+ smolts of Atlantic salmon (Salmo salar) were reared under three light regimes: simulated natural photoperiod (LDN), continuous light (LD24:0), or a combination of continuous, low-intensity background light and a superimposed simulated natural photoperiod (dual photoperiod, LDD). Growth rate in freshwater was enhanced by LD24:0 and LDD, and changes associated with smoking (increased salinity tolerance, reduced condition coefficient) were advanced under LD24:0. Plasma growth hormone levels were initially high on LD24:0 and LDD whereas on LDN, plasma growth hormone levels increased gradually from February through April. Overall GH levels were negatively correlated with condition coefficient during the final stages of smoking. After 16 mo in seawater, there were no significant size differences among the groups. The incidence of sexual maturation as postsmolts was higher in the LD24:0 and LDD groups whereas the incidence of grilsing was higher in LDN. Results demonstrate the significant influence of photoperiod on growth and smoking in Atlantic salmon. An abrupt increase to continuous light in winter may be sufficient to advance important aspects of the parr–smolt transformation. Dual photoperiod may be a way to combine the increased growth rate observed under continuous light and the normal parr–smolt transformation associated with natural photoperiod.
Analysis of Nonlinearity Effects in Expected-Value Parameterizations of the von Bertalanffy Equation
Authors: Cerrato Robert M.
Published: April 2009

Using curvature measures, this study provides direction on exploiting the full potential of two expected-value parameterizations of the von Bertalanffy equation in reducing nonlinearity effects. This study also examines the relationship between the curvature measures and characteristics of growth data for these parameterizations. Empirical analysis of a diverse set of growth data suggests that, on average, a threefold reduction in the maximum parameter effects curvature can be achieved by simply defining one parameter as the expected mean size of an intermediate age-class, rather than as the oldest age-class in the sample. It is also found that samples in which there are proportionally more size measurements in the younger age-classes relative to the older age-classes tend to have lower nonlinearity effects. Results can be applied to existing growth data which would otherwise yield unacceptably biased and nonnormal parameter estimates and to reduce the effort required in producing accurate confidence regions.
Assessing the impact of Sampling Error on Model-Based Management Advice: Comparison of Equilibrium Yield per Recruit Variance Estimators
Authors: Pelletier Dominique , Gros Philippe
Published: April 2009

The assessment offish stocks often relies on data estimated from complex sampling schemes. For instance, catch and weight-at-age estimates result from sampling commercial landings. This paper studies the propagation of sampling error in catches in an equilibrium yield per recruit model. The covariance matrix of catch estimators is calculated for a given design using sampling theory. The impact of this uncertainty on estimated yield per recruit is assessed by three techniques: the delta method, trials from a multinormal distribution of catches (Gaussian approximation), and bootstrap. The comparison of results leads to the following conclusions, (i) For the model studied, the delta method probably overestimates the variance of the response, (ii) Gaussian approximation and bootstrap give similar values. As the latter is free of approximation and of restrictive assumptions, this suggests that the yield model chosen is to some extent insensitive to the distributional form of catch estimators, (iii) Bootstrap is the method of choice, provided that resampling accurately mimics the whole complexity of the original sampling design. If resampling is not properly achieved, variances could be severely underestimated.
Meristic and Morphometric Variation between the Endangered Acadian Whitefish, Coregonus huntsmani, and the Lake Whitefish, Coregonus clupeaformis, in the Canadian Maritime Provinces and the State of Maine, USA
Authors: Edge Thomas A. , McAllister Don E. , Qadri Sami U.
Published: April 2009

Principal component and discriminant function analyses of morphological variation between whitefish populations from the Canadian Maritime Provinces and the State of Maine, USA, clearly distinguished the Acadian whitefish, Coregonus huntsmani, from the lake whitefish species complex, Coregonus clupeaformis. Ten meristic and 44 morphometric characters were examined and the species were best discriminated by number of vertebrae (>97% separation) and mouth shape. Acadian whitefish had a terminal mouth and 64–67 [Formula: see text] vertebrae, while lake whitefish had a subterminal mouth and 58–64 [Formula: see text] vertebrae. Acadian whitefish were also characterized by having more lateral line scales (88–100, [Formula: see text] than lake whitefish (63–95, [Formula: see text], a shorter adipose to caudal fin length, a smaller adipose fin, and a longer pelvic axillary process than lake whitefish. Considerable morphological variation was found between lake whitefish populations examined although there was no morphological basis to recognize any lake whitefish population as taxonomically distinct. The Acadian whitefish has morphological characteristics of both subgenera Leucichthys and Coregonus; it could be important for understanding the evolution of coregonine fishes and its imminent extinction would represent a serious loss of genetic diversity.
Importance of Threshold Length and Photoperiod for the Development of Bimodal Length–Frequency Distribution in Atlantic Salmon (Salmo salar)
Authors: Skilbrei Ove T.
Published: April 2009

Juveniles of 0 + Atlantic salmon (Salmo salar) were graded in narrow length intervals to test the hypothesis that a threshold length determines the segregation into bimodal length–frequency distributions. In the experiment, 1350 juveniles of an initial length of 70–80 mm were held under different light and temperature conditions. Distinct decreases in temperature for short or long periods did not influence the degree of bimodal segregation and temperature did not, thus, seem to be a winter stimulus for segregation in fish of this size. Transfer of fish from continuous light to natural photoperiod was followed by a segregation in growth rates into lower and upper mode fish. Upper mode fish developed smolt appearance the following spring. Under continuous light the bimodality was weak or absent and these fish did not develop morphological characteristics typical of smolts. It is concluded that the individual decision to enter the upper mode and undergo silvering the following spring is strongly dependent on the length of the fish at the time of the winter light stimulus. Fish smaller than a threshold length of about 75 mm reduce their growth rate in response to the natural photoperiod, while fish above this size enter the upper length–frequency mode.
Feeding Habits of Northeast Atlantic Harp Seals (Phoca groenlandica) along the Summer Ice Edge of the Barents Sea
Authors: Lydersen Christian , Angantyr Lars Anker , Wiig Øystein , Øritsland Torger
Published: April 2009

Stomachs from 58 harp seals (Phoca groenlandica) from the northern part of the Barents Sea were collected between August 20 and September 5, 1987. Fifty-six of the stomachs contained identifiable remains. The amphipod Parathemisto libellula was the most common food item, found in 98% of the seal stomachs and constituting 57.9% of the total volume. Fish were the second most important prey group, with Arctic cod (Boreogadus saida) as the dominant species followed by Nybelin's sculpin (Triglops nybelini) and Greenland halibut (Reinhardtius hippoglossoides). Decapods, mainly Pandalus borealis, were also common as prey of harp seals. No sex- or age-related differences in choice of food were found. From knowledge of the depths at locations where seals were collected and the presence of fresh benthic fishes in the seal stomachs, it is assumed that harp seals could forage at depths below 300 m.
Bénéfices à court terme des mouvements anadromes saisonniers pour une population d'omble de fontaine (Salvelinus fontinalis) du Nouveau Québec
Authors: Doyon Jean-François , Hudon Christiane , Morin Roderick , Whoriskey Jr. F. G.
Published: April 2009

This study characterizes the seasonal anadromous movements of a brook charr population and compares its biological and energetic characteristics with charr spending summer in freshwaters. Downstream movements monitored at a counting fence over 3 yr were most intense in spring but occurred until fall and were positively correlated with rapid increases of water level. The timing of movements varied from year to year. Smaller charr were most subject to being swept downstream compared with freshwater residents, and most trout were concentrated near the mouth of the river. These patterns suggest that the downstream movements of charr in this system are passive. Upstream migrants had a higher condition factor and a lower tissue water content than freshwater residents, indicating that downstream movements result in a faster accumulation of energetic reserves during summer. However, the fortuitous character of anadromous migrations as well as the absence of differences in the biological characteristics (growth, size at maturity, fecundity, egg size) suggests that anadromous and resident fish belong to a single population whose yearly migrant component could be randomly determined.
Effects of Incubation in Oiled Sediment on Emergence of Capelin (Mallotus villosus) Larvae
Authors: Paine Michael D. , Leggett William C. , McRuer Jeff K. , Frank Kenneth T.
Published: April 2009

Capelin (Mallotus villosus) were incubated in oiled sediment (range of initial concentrations 0–400 ppm total hydrocarbons) from the blastula stage to emergence of larvae. Concentrations of individual and total hydrocarbons in the sediment and interstitial water declined by ≈80–90% over the 28-d exposure period. Larvae from oiled sediment emerged ≈0.5–1 d earlier than did control larvae, and the percentage of larvae emerging was greater in the oiled treatments. Yolk length of exposed larvae after emergence was 10% greater than that of controls; head length (a measure of body size) was 1% less. The emergence behaviour of exposed larvae serves as an adaptive response to stress which enables more larvae to leave the contaminated sediment quickly. The yolk and body size effects would probably not affect survival. Therefore, oiled sediment in the tested range would not significantly affect embryos and larvae prior to emergence. Delayed effects on emerged larvae, which are more sensitive than embryos, may be more important.
Acclimation of Rainbow Trout (Oncorhynchus mykiss) to Low Environmental pH Does Not Involve an Activation of the Pituitary-interrenal Axis, but Evokes Adjustments in Branchial Ultrastructure
Authors: Balm P. H. M. , Pottinger T. G.
Published: April 2009

Two strains of rainbow trout (Oncorhynchus mykiss) were exposed to soft water at pH 4.0 for 14 days, after ambient pH was reduced gradually. Several parameters, either indicators of acid stress, or reportedly involved in the adaptive response to low pH, were monitored. No mortality occurred during the exposure period; feeding behavior, haematocrit, and plasma protein levels were not affected. A transient depression of leucocrit was observed. A minor, but significant, hypochloremia and perturbations in plasma glucose levels occurred in acid-exposed fish from one strain only. There was no evidence of activation of the pituitary-interrenal axis in acid-exposed fish. Baseline plasma ACTH and Cortisol levels were indistinguishable from those of control fish, and there was no evidence of sensitization to additional stress in acid-exposed fish, in vitro baseline and ACTH-stimulated Cortisol secretion was not significantly different in the two groups. Ultrastructural evidence indicated an increased turnover rate of chloride cells and leucocyte infiltration in gills of acid-exposed fish. These results suggest that interrenal activation and catastrophic ion loss are not inevitable consequences of exposure of rainbow trout to pH 4.0 and that ultrastructural changes in the gills indicate locally regulated adaptive mechanisms.
Spatial Variation in Food-Limited Growth of Juvenile Greenback Flounder, Rhombosolea tapirina: Evidence from Otolith Daily Increments and Otolith Scaling
Authors: Jenkins Gregory P. , Shaw Megan , Stewart Bryce D.
Published: April 2009

Growth rates of juvenile flounder, Rhombosolea tapirina, determined from daily increment number, and the relationship between otolith and fish sizes (otolith scaling), were compared between two adjacent areas. Swan Bay, Victoria, a sheltered bay with a well-developed seagrass-detrital system, supports higher populations of prey and feeding rates of juvenile flounder than Port Phillip Bay, an area more exposed to waves and tidal currents. Temperature was significantly higher in Swan Bay (though generally less than 1 °C). Growth rates determined from daily increment number were similar within bays, but significantly different between bays. The pooled growth rate for Swan Bay (0.29 mm∙d−1) was significantly higher than for Port Phillip Bay (0.17 mm∙d−1). The same pattern was found for otolith scaling. Most of the variation in growth rates between the two bays was apparently related to food supply. A laboratory experiment indicated that otolith growth rate had a minimum level which was independent of somatic growth rate, and an additional component which was highly correlated with somatic growth rate. This resulted in an exponential decrease in otolith growth per unit somatic growth with increasing somatic growth rate such that variation in otolith scaling would be greatest at low growth rates.
Fitting Surplus Production Models: Comparing Methods and Measuring Uncertainty
Authors: Polacheck Tom , Hilborn Ray , Punt Andre E.
Published: April 2009

Three approaches are commonly used to fit surplus production models to observed data: effort-averaging methods; process-error estimators; and observation-error estimators. We compare these approaches using real and simulated data sets, and conclude that they yield substantially different interpretations of productivity. Effort-averaging methods assume the stock is in equilibrium relative to the recent effort; this assumption is rarely satisfied and usually leads to overestimation of potential yield and optimum effort. Effort-averaging methods will almost always produce what appears to be "reasonable" estimates of maximum sustainable yield and optimum effort, and the r2 statistic used to evaluate the goodness of fit can provide an unrealistic illusion of confidence about the parameter estimates obtained. Process-error estimators produce much less reliable estimates than observation-error estimators. The observation-error estimator provides the lowest estimates of maximum sustainable yield and optimum effort and is the least biased and the most precise (shown in Monte-Carlo trials). We suggest that observation-error estimators be used when fitting surplus production models, that effort-averaging methods be abandoned, and that process-error estimators should only be applied if simulation studies and practical experience suggest that they will be superior to observation-error estimators.
Spatial Variation of Crustacean Plankton in Lakes of Different Size
Authors: Patalas K. , Salki A.
Published: April 2009

The patterns of spatial distribution of planktonic crustaceans changed with increasing lake size. Greatest abundances were often found offshore in smaller lakes but nearshore in larger lakes. Interstation similarity of plankton, measured with Jaccard's and Renkonen's indices, was higher in small- to middle-sized lakes and lower in very small and very large lakes, indicating that mechanisms existed at both ends of the size spectrum which prevented plankton from mixing horizontally. The information content of a single central lake sample was evaluated against a lake average from 9–10 stations. To capture at least 80% of the species present, one station was sufficient only in smaller lakes, three to six stations were needed in the smallest and medium-sized lakes, and more than nine stations were needed in the largest lake. The single central station in small- and medium-sized lakes represented average total plankton abundance and dominant species relatively well but underestimated rare species. In larger lakes, lake average plankton was not well characterized by a single station. In Lake Superior, the central station reflected the offshore but not the nearshore community. Neither plankton abundance nor the number of species appeared related to lake size in the series of lakes investigated.
Fish and Benthic Invertebrates: Community Concordance and Community–Environment Relationships
Authors: Jackson Donald A. , Harvey Harold H.
Published: April 2009

Fish and benthic invertebrates from 40 lakes in south-central Ontario showed significantly concordant patterns based on community structure. Fish communities were associated significantly with lake morphological characteristics, but were uncorrelated with water chemistry. Large, deep lakes differed from shallow lakes in their fish species, having richer faunas due to the additional cold-water species. Centrarchid species occurred more frequently in small, shallow lakes than in larger lakes. The invertebrate community was not correlated with lake morphology, but showed a significant association with water chemistry, principally lake pH. A strong contrast in the abundance of Chaoborus and Holopedium existed, but it was unclear whether this was due to a predator–prey relationship or to differences in acid tolerance. Although the lakes showed similar patterns in the composition of both communities, each community was associated with a different set of environmental factors. Biotic processes within and between communities explain this paradox in community–environment relationships. Such biotic interactions may involve direct processes such as fish predation on a particular invertebrate taxon or indirect factors, e.g., where fish limit the abundance of invertebrate predators, thereby limiting the impact of these invertebrate predators.
Copper and Cadmium Binding to Fish Gills: Modification by Dissolved Organic Carbon and Synthetic Ligands
Authors: Playle Richard C. , Dixon D. George , Burnison Kent
Published: April 2009

Adult fathead minnows (Pimephales promelas) were exposed to 17 g Cu∙L−1or 6 g Cd∙L−1for 2 to 3 h in synthetic softwater solutions at pH 6.2 containing either naturally-occurring, freeze-dried dissolved organic carbon (DOC) or synthetic ligands such as EDTA. After exposures, gills were assayed for bound Cu or Cd. As a first approximation, lake of origin or molecular size fraction of DOC did not influence Cu binding to gills, while DOC concentration did. DOC concentrations ≥4.8 mg∙L−1prevented Cu from accumulating on fathead gills. At the relatively low concentrations used, neither Cu nor Cd interfered with binding of the other metal on gills, suggesting different gill binding sites. Cadmium accumulation on gills was more sensitive to increased concentrations of Ca and H+than was Cu. Surprisingly, Cd bound to gills to the same or greater extent than did Cu: for synthetic ligands, Cd binds less well than Cu. This result corroborates previously published observations that Cd, unlike Cu, is taken up at gills through high affinity Ca channels. Accumulation of Cd on fish gills was never associated with14C-labelled EDTA or14C-citrate, indicating that free metal interacts with the gill while metal–ligand complexes usually do not.
Behavioral Responses ofDrunella coloradensis(Ephemeroptera) Nymphs to Short-Term pH Reductions
Authors: Pennuto Christopher M. , deNoyelies Jr. Frank
Published: April 2009

Behavioral responses of Drunella coloradensis nymphs were examined in outdoor experimental stream channels after pH reductions of 1 and 2 pH units below ambient. The severity of pH decline below the ambient of 7.8 influenced the behavior patterns displayed by nymphs. At pH 7.01 (an intermediate pH decline) nymphs sat less frequently and burrowed more than controls. Burrowing behavior frequency returned to control levels and drifting and crawling behaviors increased relative to controls at pH 6.02. Ventilatory behaviors increased with pH decline, but were independent of the severity of acidity increases. These results suggest that individual behaviors may offer a more sensitive indicator of sub-acute stress in aquatic insect communities than population or community monitoring. Behaviors leading to increased activity levels in stream insects may have community-level effects via changes in predator–prey encounter rates or increased susceptibility to passive drift. These potential changes are discussed in reference to monitoring for acidification effects.
Management of the 4WX Atlantic Herring (Clupea harengus) Fishery: An Evaluation of Recent Events
Authors: Stephenson R. L. , Lane D. E. , Aldous D. G. , Nowak R.
Published: April 2009

The Atlantic herring (Clupea harengus) fishery of the Scotian Shelf and Bay of Fundy regions of Canada (NAFO Divisions 4W and 4X) is pursued with multiple gear types including traps, gill nets and purse seines, which have evolved in importance over time with changing market emphasis. It was one of the first commercial fisheries to be regulated by limited entry (since 1970), and in 1972 it was the first to come under nationally allocated annual total allowable catch (TAC) limits. In 1976 an individual vessel quota scheme for purse seiners was established and operated jointly by the regulator and the harvesting sector. That initiative formed the basis of the 1983 10-Year Management Plan for 4WX herring that is reviewed and evaluated in this paper. The Plan, while not expressly achieving its original goals, and not fully realizing the implicit benefits of an individual transferable quota (ITQ) system, has contributed to the continuation of consensus management of this, the only large Atlantic herring fishery which has not suffered a major collapse. The development of successful management plans in the future must deal explicitly with ongoing problems of unstable markets for herring products and under-reporting of catches.
Sustained colonization of the black fly Simulium decorum Walker (Diptera: Simuliidae)
Authors: Simmons K. R. , Edman J. D.
Published: April 2009

The black fly Simulium decorum Walker has been colonized for 16 generations (18 months) using an inexpensive larval rearing system. More than 90% of the females are induced with simulated twilight to oviposit on floating cork substrates. Eggs on corks have been successfully stored for up to 2 months at 0.5–1.5 °C. Female survival averages 87% for 4 days at 22 °C and 90–95% relative humidity. Mating in aspirator tubes results in nearly 100% insemination, whereas a cage mating trial resulted in only 26% insemination. Under crowded conditions where larvae are underfed, emerging males are smaller and mature fewer eggs. Though autogenous, nulliparous females readily blood feed on humans but do not mature additional eggs.
The feeding behaviour of Florometra serratissima (Echinodermata: Crinoidea)
Authors: Byrne M. , Fontaine A. R.
Published: April 2009

The feeding behaviour of the comatulid crinoid Florometra serratissima (A. H. Clark) was studied at two sites around Vancouver Island. It appears to inhabit areas where currents are slight. The arms are held in a cone posture during slack water but in mild currents they orient to form a partial arm fan.Tube foot behaviour was observed in situ and in aquaria. The podia arise in groups of three, each podium of the triplet exhibiting a characteristic behaviour related to its role in feeding. The primary podia are typically held extended; they initiate the mechanism of particle capture, secrete mucous threads, and are sensory. The secondary podia, attached to the lappet for much of their length, scoop to collect particles and perhaps mucous threads. The tertiary podia manipulate material in the food grooves. Lappet action appears to aid particle collection through scraping along the primary podia.These feeding activities are compared with those reported for Antedon bifida (Pennant) and other crinoids.
Territories and territorial defense in juvenile brook charr, Salvelinus fontinalis (Pisces: Salmonidae)
Authors: McNicol Richard E. , Noakes David L. G.
Published: April 2009

The typical territory defended by juvenile brook charr (Salvelinus fontinalis) in a laboratory stream tank was cordate in shape, with the resident stationed at the downstream end facing into the current. Responses by the resident were less aggressive toward intruders at increasing distance from the resident's station. Chases predominated immediately around the station, charges were more frequent further away, and lateral displays were most frequent at the territory perimeter. Defense of the anterior (upstream) area tended to be more aggressive, with equal numbers of charge and chase interactions, while laterally less aggressive and presumably less costly (energetically) charges predominated. These details of territory structure and defense agree with the predictions of an hypothesis of the territory as an economically defensible resource.
Survie in vitro et post mortem des gametes de truite fario (Salmo trutta fario)
Authors: Billard R. , Marcel Jacqueline , Matei D.
Published: April 2009

Post mortem continuation of fertility of the gametes in the trout Salmo trutta fario has been investigated in order to gather more information on the possibility of using ova and sperm from genitors killed accidentally. The percentage of eggs fertilized at 200 day-degrees was used as a measure of the fertility of the gametes left post mortem in the genital tracts of animals kept at 4 °C after killing, in air or water; the measures were compared with those of gametes kept in vitro, at 4 °C also. Gametes taken periodically from live fish during the experiment were used as controls.Gametes kept in the body of killed genitors survive only a few hours and show a significant drop after 12 h and 6–8 h for sperm and live respectively, with no detectable difference between fish kept in water or in air. Gametes kept in vitro maintain their fertility at 51–90% after 72 h (control = 96%) and at 80% after 14 days (control = 97%) for ova and sperm respectively. The fertilizing capacity of control sperm taken from live fish did not vary throughout the experiment.[Journal translation]
Limb regeneration in adult amphibia
Authors: Scadding Steven R.
Published: April 2009

This paper reports a histological analysis of limb regeneration capacity in 20 species of amphibians. These data, along with a survey of other species reported in the literature, are used as a basis for the following generalizations. (1) Limb regeneration in the amphibians is not an all-or-none process, but regenerative capacity covers a continuum from normal regeneration to total absence of regenerative ability. (2) In adult anurans, regenerative outgrowth is common in discoglossids and pipids, occurs frequently in hylids, rarely in ranids, and has never been reported in bufonids. In the anurans, there is no correlation between size and regenerative capacity. (3) In the urodeles, limb regeneration capacity is correlated with size. Urodele species with a mean snout–vent length over 100 mm regenerate heteromorphically or not at all. Those under 75 mm regenerate consistently normally. Those species of intermediate size give variable responses to limb amputation, and may regenerate normally, heteromorphically, or not at all. Hypotheses that might explain differences in regenerative ability are discussed.
Morphology and ultrastructure of an intertergal pheromone gland in the abdomen of the pine sawfly Neodiprion sertifer (Insecta, Hymenoptera): a potential source of sex pheromones
Authors: Hallberg Eric , Löfqvist Jan
Published: April 2009

An abdominal intertergal gland of the sawfly Neodiprion sertifer was found in both sexes of the sawfly N. sertifer, which is in contrast with Diprion similis, in which the gland is known only from the female. The gland lies laterally on each side of tergite II in the fat body between the tergite wall and trachea and opens into the fold of the arthrodial membrane between tergites II and III. The emission of secretion from the gland is controlled by a muscle opening the gland duct. Expansion of the lateral trachea probably forces the secretion out of the gland's lumen.The intertergal gland is a typical insect epidermal pheromone gland formed by three cell types: glandular, ductule, and hypodermal cells. The glandular cells have microvilli-lined cavities surrounded by numerous mitochondria. From these cavities arise ductules, surrounded by ductule cells, merging into other ductules that open into the lumen of the gland. The hypodermal cells underlie the cuticular walls of the lumen. This scheme is now well-known from many insect species as typical of epidermal pheromone glands with a draining duct. Finally, the possible function of the intertergal gland's secretion is discussed.
Acoustical signals related to reproduction in the spinulosus species group of Bufo (Amphibia, Bufonidae)
Authors: Penna Mario V. , Veloso Alberto M.
Published: April 2009

Species of the spinulosus group of Bufo, B. chilensis, B. atacamensis, and B. spinulosus, do not emit a mating call during their reproductive activity. A release call is emitted by clasped males and the acoustic component of this signal produces rejection of the clasping male. Temporal and spectral analysis shows that these signals are species specific and therefore a useful complement in taxonomic diagnosis of these species. The release call is also emitted by B. spinulosus without contact with other individuals. This suggests that the signal is also a distance-recognition mechanism. During amplexus, B. chilensis and B. atacamensis emit vocalizations not reported for another Bufo species. Its significance has not been established and can represent a release-call modification during a particular physiological state of the animal. Interspecific variation of vocalizations in the spinulosus group is evidence to support the speciation model proposed for the group. Bufo spinulosus has the most divergent signal. Bufo chilensis and B. atacamensis are more related species and their evolutionary divergence is a later event in the radiation of the genus.
Forestry maps as an information source for description of moose winter yards
Authors: Proulx Gilbert , Joyal Robert
Published: April 2009

One hundred and twenty-one moose (Alces alces) winter yards were located in February 1975 in La Vérendrye Fish and Game Reserve, Quebec. At this time of winter, they occupied a mean area of 0.44 km2. The yards were established on various slopes or on mountain tops without preference to a particular exposure. This habitat is situated on gentle slopes of less than 11% inclination, and at an altitude less than 46 m above bodies of water considered as components of summer habitats. Discriminant analysis showed that the habitat used by moose differs from unused sites only by a lack of bodies of water and shade-intolerant stands. The typical winter yard corresponds to a mosaic of mature and disturbed stands varying in structure and age and provides both cover and food. It is dominated by white birch (Betula papyrifera) associated with conifers. Forestry maps alone cannot identify all parameters for a suitable site but coupled with topographic maps they can, for some years, localise potential sites to be protected from logging.
Role of prostaglandins in amphibian limb regeneration
Authors: Scadding Steven R.
Published: April 2009

Following limb amputation in the newt (Notophthalmus viridescens), the animals were given daily intraperitoneal injections of 0.1 or 1.0 mg of either indomethacin or acetylsalicylic acid. This had no observable influence on the rate or extent of limb regeneration or the histological appearance of the regenerating limb when compared with controls. Following limb amputation in toads (Bufo americanus), the limb stumps were injected daily for the first 15 days after amputation with 5 μg of either prostaglandin E1 or prostaglandin E2. Neither of these treatments had any observed effect on subsequent wound healing of the limbs when compared with controls. These observations suggest that prostaglandins do not play a major role in control of amphibian limb regeneration.
Dollfusnema amphisbaenia n.gen., n.sp. (Nematoda: Cosmocercinae) from the lizard Leposternon phocaena (Amphisbaenia) of Brazil
Authors: Baker M. R.
Published: April 2009

Dollfusnema amphisbaenia n.gen., n.sp. is distinguished from all other genera in the Cosmocercinae by the possession of cuticular interlabia between the cephalic lips. These structures are similar to the interlabia and cordons observed commonly in the superfamily Heterakoidea and this provides an additional argument that the Heterakoidea may have evolved from primitive cosmocercoids such as the Cosmocercinae.
Comment: The blunting of Occam's Razor, or to hell with parsimony
Authors: Holsinger Kent E.
Published: April 2009

The principle of parsimony is a useful methodological tool in the choice between competing hypotheses if the hypotheses are of equal explanatory power. Its use is defended by the discussion of several examples, and a recent objection to its use is shown to be the result of a misinterpretation of the principle.
Male aggression and the population dynamics of the vole, Microtus townsendii
Authors: Gipps J. H. W. , Taitt M. J. , Krebs C. J. , Dundjerski Z.
Published: April 2009

Male behaviour was manipulated by drug and hormone implants in field populations of Microtus townsendii on Westham Island near Vancouver, B.C. Small (≤45 g) males in one population were made precociously aggressive by subcutaneous Silastic capsules of testosterone. Large (≥46 g) males in another population were made less aggressive with implants of scopolamine HBr. Experiments were conducted over a 9-week period that coincided with a spring decline in population size and repeated for a 6-week period during the summer breeding season.A population with dummy implants indicated that neither the process of implantation nor the initial dose of either chemical affected survival of implanted voles. The rate of spring decline in male numbers was significantly lower in a scopolamine (passive large male) population than in control populations. Female breeding started earlier and more females bred in the scopolamine population than in the control populations during the first experimental period; however, this did not lead to significant differences in recruitment. Thus, although there were detectable demographic differences between scopolamine and control populations during the first experiment, they were not as pronounced as had been predicted. We conclude that male spacing behaviour alone is not sufficient to control the demography of Microtus townsendii populations.
The interaction of rearing temperature and food supply on the life history of two species of Simuliidae (Diptera)
Authors: Colbo M. H. , Porter G. N.
Published: April 2009

The effect of rearing the preimaginal stages of Simulium vittatum and Simulium verecundum at 15, 20, and 25 °C and at four feeding rates was examined. The results showed that flies reared on all diets were larger at the coolest temperature. The decrease in size in S. vittatum between 20 and 15 °C and 25 and 20 °C was not proportional, with the decrease in size being very much larger with a temperature increase from 20 to 25 °C. This was reflected in the fecundity of the autogenous females. The changes in development times were, however, almost proportional. With S. verecundum size changes approached a proportional change but the development times did not, being markedly elongated at 15 °C. Therefore the nature of the effect of temperature changes can not be predicted from one species of simuliid to another. An examination of growth in relation to quantity of food availability and temperature indicated that the quantity of food required for maximum growth increased exponentially with increasing temperature.
Influence de la riboflavine sur les besoins globaux en vitamines hydrosolubles chez le puceron du pois, Acyrthosiphon pisum
Authors: Boisvert J. M. , Auclair J. L.
Published: April 2009

The effects of different concentrations of riboflavin and that of total water-soluble vitamins in the nutrition of biotypes Saint-Jean and Ile-aux-Coudres of the pea aphid, Acyrthosiphon pisum (Harris), were determined with chemically defined diets. Omission of riboflavin in the diet resulted in a significant increase in growth, reproduction, survival and ingestion rates of the two biotypes. Aphid performance was progressively and significantly improved when the total concentration of 10 vitamins, in the absence of riboflavin, was increased from 0 to 115.6 and 231.1 mg/100 mL of diet; the aphids performed poorly when such increases were accompanied by an increase in riboflavin. Finally, a doubling in the total concentration of the 10 other dietary vitamins (i.e. to 462.2 mg/100 mL), in the absence of riboflavin, resulted in a slightly lowered performance by aphids, whereas, in the presence of riboflavin, aphid performance was significantly reduced. These results indicate that a substantial decrease in dietary riboflavin, or even its omission, and keeping the overall content of the 10 other vitamins to 231.1 mg/100 mL significantly improved the rearing of the two biotypes on such diets over at least two or three successive generations.
Comparaison de différentes méthodes de détermination de l'âge individuel chez le vison (Mustela vison Schreiber)
Authors: Pascal M. , Delattre P.
Published: April 2009

The relationship between lens weights and age was determined using 322 farm minks of known age. Twenty-seven of these animals were used in the histological study of the mandibular bone, the femoral diaphysis, the cementum and dentine of M1 and the canine tooth. The weight of the lenses represents a good age indicator until 1.5 years. In older animals counting the resting or adhesive line (L.A.C., ligne d'arrêt de croissance) of the acellular cementum in the region of the M1 constitutes the best criterion for determining the individual age. The period of L.A.C. deposition is indicated more accurately.
Larval stages of the lake chub, Couesius plumbeus
Authors: Fuiman Lee A. , Baker Joan P.
Published: April 2009

Three collections of Couesius plumbeus eggs were laboratory reared. Larvae were described with emphasis on external morphology. They were characterized by (1) 25 to 30 preanal myomeres, (2) a diagonal row of melanophores across the surface of the breast, and (3) a concentration of melanophores on the distal hypaxial portion of the caudal peduncle. Larval characteristics were compared with those of its breeding associate Rhinichthys cataractae and other sympatic cyprinids which have similarly high preanal myomere counts.