bluuebunny/crossref_metadata_2025 huggingface dataset:
Suppression of T-Lymphocyte Activation and Chemotaxis by the Adenylate Cyclase Toxin ofBordetella pertussis
Authors: Paccani Silvia Rossi , Molin Federica Dal , Benagiano Marisa , Ladant Daniel , D'Elios Mario M. , Montecucco Cesare , Baldari Cosima T.
Published: April 2008

The adenylate cyclase toxin (CyaA) released byBordetella pertussisis an essential virulence factor for colonization of the host. This toxin inhibits migration and activation of phagocytes, thereby preventing bacterial killing. In addition, CyaA interferes with the initiation of adaptive immunity by misdirecting dendritic cell differentiation to a suppressive rather than stimulatory phenotype. Here we show that CyaA directly affects adaptive responses by catalyzing cyclic AMP (cAMP) production in peripheral blood lymphocytes. Treatment with CyaA resulted in profound impairment of T-lymphocyte activation and chemotaxis. These effects resulted from inhibition of T-cell antigen receptor and chemokine receptor signaling via a cAMP/protein kinase A (PKA)-dependent pathway. A comparison of the activities of CyaA on T-cell and macrophage activation and migration revealed that the biological effects of the toxin were paralleled by inhibition of the activation of mitogen-activated protein (MAP) kinases, highlighting the conclusion that the ubiquitous and evolutionarily conserved MAP kinase modules are common targets of the PKA-mediated immunosuppressant activities of CyaA and underlining the potential of cAMP-elevating toxins as a means of evasion of immunity by bacterial pathogens.
Significant Role for
ladC
in Initiation of
Legionella pneumophila
Infection
Authors: Newton Hayley J. , Sansom Fiona M. , Dao Jenny , Cazalet Christel , Bruggemann Holger , Albert-Weissenberger Christiane , Buchrieser Carmen , Cianciotto Nicholas P. , Hartland Elizabeth L.
Published: April 2008

Previously, we identified
ladC
in a cohort of genes that were present in
Legionella pneumophila
but absent in other
Legionella
species. Here we constructed a
ladC
mutant of
L. pneumophila
and assessed its ability to replicate in mammalian cell lines and
Acanthamoeba castellanii
. The
ladC
mutant was recovered in significantly lower numbers than wild-type
L. pneumophila
at early time points, which was reversed upon transcomplementation with
ladC
but not
ladC
N430A/R434A
, encoding a putative catalytically inactive derivative of the protein. In fact, complementation of
ladC
::Km with
ladC
N430A/R434A
resulted in a severe replication defect within human and amoeba cell models of infection, which did not follow a typical dominant negative phenotype. Using differential immunofluorescence staining to distinguish adherent from intracellular bacteria, we found that the
ladC
mutant exhibited a 10-fold reduction in adherence to THP-1 macrophages but no difference in uptake by THP-1 cells. When tested in vivo in A/J mice, the competitive index of the
ladC
mutant dropped fivefold over 72 h, indicating a significant attenuation compared to wild-type
L. pneumophila
. Although localization of LadC to the bacterial inner membrane suggested that the protein may be involved in signaling pathways that regulate virulence gene expression, microarray analysis indicated that
ladC
does not influence the transcriptional profile of
L. pneumophila
in vitro or during
A. castellanii
infection. Although the mechanism by which LadC modulates the initial interaction between the bacterium and host cell remains unclear, we have established that LadC plays an important role in
L. pneumophila
infection.
The Tick Salivary Protein Salp15 Inhibits the Killing of Serum-Sensitive
Borrelia burgdorferi
Sensu Lato Isolates
Authors: Schuijt Tim J. , Hovius Joppe W. R. , van Burgel Nathalie D. , Ramamoorthi Nandhini , Fikrig Erol , van Dam Alje P.
Published: April 2008

Borrelia burgdorferi
, the agent of Lyme disease, is transmitted by ticks. During transmission from the tick to the host, spirochetes are delivered with tick saliva, which contains the salivary protein Salp15. Salp15 has been shown to protect spirochetes against
B. burgdorferi
-specific antibodies. We now show that Salp15 from both
Ixodes ricinus
and
Ixodes scapularis
protects serum-sensitive isolates of
Borrelia burgdorferi
sensu lato against complement-mediated killing.
I. ricinus
Salp15 showed strong protective effects compared to those of
I. scapularis
Salp15. Deposition of terminal C5b to C9 (one molecule each of C5b, C6, C7, and C8 and one or more molecules of C9) complement complexes, part of the membrane attack complex, on the surface of
B. burgdorferi
was inhibited in the presence of Salp15. In the presence of normal human serum, serum-sensitive
Borrelia burgdorferi
requires protection against complement-mediated killing, which is provided, at least in part, by the binding to the tick salivary protein Salp15.
The Inositol Phosphatase SHIP Controls
Salmonella enterica
Serovar Typhimurium Infection In Vivo
Authors: Bishop Jennifer L. , Sly Laura M. , Krystal Gerald , Finlay B. Brett
Published: April 2008

The SH2 domain-containing inositol 5′-phosphatase, SHIP, negatively regulates various hematopoietic cell functions and is critical for maintaining immune homeostasis. However, whether SHIP plays a role in controlling bacterial infections in vivo remains unknown.
Salmonella enterica
causes human salmonellosis, a disease that ranges in severity from mild gastroenteritis to severe systemic illness, resulting in significant morbidity and mortality worldwide. The susceptibility of
ship
+/+
and
ship
−/−
mice and bone marrow-derived macrophages to
S. enterica
serovar Typhimurium infection was compared.
ship
−/−
mice displayed an increased susceptibility to both oral and intraperitoneal serovar Typhimurium infection and had significantly higher bacterial loads in intestinal and systemic sites than
ship
+/+
mice, indicating a role for SHIP in the gut-associated and systemic pathogenesis of serovar Typhimurium in vivo. Cytokine analysis of serum from orally infected mice showed that
ship
−/−
mice produce lower levels of Th1 cytokines than do
ship
+/+
animals at 2 days postinfection, and in vitro analysis of supernatants taken from infected bone marrow-derived macrophages derived to mimic the in vivo ship
−/−
alternatively activated (M2) macrophage phenotype correlated with these data. M2 macrophages were the predominant population in vivo in both oral and intraperitoneal infections, since tissue macrophages within the small intestine and peritoneal macrophages from
ship
−/−
mice showed elevated levels of the M2 macrophage markers Ym1 and Arginase 1 compared to
ship
+/+
cells. Based on these data, we propose that M2 macrophage skewing in
ship
−/−
mice contributes to ineffective clearance of
Salmonella
in vivo.
tRNA Modification by GidA/MnmE Is Necessary forStreptococcus pyogenesVirulence: a New Strategy To Make Live Attenuated Strains
Authors: Cho Kyu Hong , Caparon Michael G.
Published: April 2008

Studies directed at vaccine development and mucosal immunity againstStreptococcus pyogeneswould benefit from the availability of live attenuated strains. Our approach for production of candidate live attenuated strains was to identify mutations that did not alter growth in vitro and did not alter the overall complement of virulence factors produced but did result in reduced levels of expression of multiple secreted virulence factors. A global reduction but not elimination of expression would likely lead to attenuation while maximizing the number of antigenic targets available for stimulation of immunity. Adaptation of Tn5-based transposome mutagenesis toS. pyogeneswith initial screening for reduced expression of the SpeB protease resulted in identification of mutations ingidA, which encodes an enzyme involved in tRNA modification. Reduced SpeB expression was due to delayed onset ofspeBtranscription resulting from reduced translation efficiency of the message for RopB, a transcriptional activator. Overall, GidA−mutants had a nearly normal global transcription profile but expressed significantly reduced levels of multiple virulence factors due to impaired translation efficiencies. A translation defect was supported by the observation that mutants lacking MnmE, which functions in the same tRNA modification pathway as GidA, phenocopied GidA deficiency. The mutants stimulated a cytokine response in cultured macrophages identical to that in the wild type, with the exception of reduced levels of tumor necrosis factor alpha and interleukin-23. Significantly, GidA−mutants were highly attenuated in the murine ulcer model of soft tissue infection. These characteristics suggest that GidA pathway tRNA modification mutants are attractive candidates for further evaluation as live attenuated strains.
Reference intervals of common serum analytes of Hong Kong Chinese
Authors: Chan A O K , Lee K C , Leung J N S , Shek C C
Published: April 2008

Aim:

Setting up reference intervals from the local service populations is one of the major responsibilities of clinical laboratories. Yet, this task is difficult to achieve because it is costly and time consuming when compared with validating reference intervals from assay manufacturers.

Methods:

Following the recommendations of the International Federation of Clinical Chemistry, healthy local Chinese adults were recruited to set up reference intervals for common serum analytes. Statistical methods recommended by the National Committee for Clinical Laboratory Standards were used for defining the reference limits.

Results:

Data from 335 subjects were analysed. The reference intervals set up were broadly similar to those provided by the assay manufacturer, except for sodium and potassium. Glomerular filtration rate was estimated by the modification of diet in renal disease equation, with or without modification for Chinese. Body mass index had a significant impact on serum urate and alanine aminotransferase levels.

Conclusion:

Reference intervals of common serum analytes have been set up for the local Chinese population. A good example of quality laboratory service has also been set up to provide clinicians with reliable reference intervals that they can confidently rely on for the diagnosis and management of patients.
Population tobacco control interventions and their effects on social inequalities in smoking: systematic review
Authors: Thomas S , Fayter D , Misso K , Ogilvie D , Petticrew M , Sowden A , Whitehead M , Worthy G
Published: April 2008

Objective:

To assess the effects of population tobacco control interventions on social inequalities in smoking.

Data sources:

Medical, nursing, psychological, social science and grey literature databases, bibliographies, hand-searches and contact with authors.

Study selection:

Studies were included (n = 84) if they reported the effects of any population-level tobacco control intervention on smoking behaviour or attitudes in individuals or groups with different demographic or socioeconomic characteristics.

Data extraction:

Data extraction and quality assessment for each study were conducted by one reviewer and checked by a second.

Data synthesis:

Data were synthesised using graphical (“harvest plot”) and narrative methods. No strong evidence of differential effects was found for smoking restrictions in workplaces and public places, although those in higher occupational groups may be more likely to change their attitudes or behaviour. Smoking restrictions in schools may be more effective in girls. Restrictions on sales to minors may be more effective in girls and younger children. Increasing the price of tobacco products may be more effective in reducing smoking among lower-income adults and those in manual occupations, although there was also some evidence to suggest that adults with higher levels of education may be more price-sensitive. Young people aged under 25 are also affected by price increases, with some evidence that boys and non-white young people may be more sensitive to price.

Conclusions:

Population-level tobacco control interventions have the potential to benefit more disadvantaged groups and thereby contribute to reducing health inequalities.
The Petromyzoniformes with Particular Reference to Paired Species
Authors: Potter I. C.
Published: April 2008

The distribution of living lampreys (Petromyzoniformes) is antitropical, a feature almost certainly related to the fact that the ultimate incipient lethal temperature of ammocoetes lies between ~28 and 32 °C. In general, the species that attain the largest body size have the widest distribution. The holarctic species are placed in the Petromyzonidae, while those of the Southern Hemisphere are assigned either to the Geotriidae or Mordaciidae. Reference is made to the techniques used in lamprey systematics, placing particular emphasis on defining the terminology of the components of the dentition and the ways in which body proportions can be measured. Using dentitional characters, the Petromyzonidae can be arranged in a logical sequence from Ichthyomyzon and Petromyzon to either Caspiomyzon or to series consisting either of Eudontomyzon and Tetrapleurodon or the subgenera of Lampeira, i.e. Entosphenus, Lethenteron, and Lampetra. A list is given of the 17 parasitic and 22 nonparasitic lampreys described from the Northern and Southern hemispheres. The evolution of nonparasitic lampreys has involved an extension of larval life and a reduction in the postmetamorphic period, a process which has led to a marked reduction in the size of the mature adults. The more conspicuous differences between nonparasitic and parasitic species start to appear after the onset of metamorphosis. These include the rapid enlargement and maturation of gonads in nonparasitic species. However, significant differences have been found between the larvae of nonparasitic lampreys and those of their parasitic ancestor in such features as the number of oocytes, trunk myomeres, and size at the onset of metamorphosis.Key words: lampreys, life cycles, parasitic, nonparasitic, distribution, dentition, phylogeny, Petromyzonidae, Geotriidae, Mordaciidae
Ecology of Larval and Metamorphosing Lampreys
Authors: Potter I. C.
Published: April 2008

Ammocoetes are relatively sedentary burrowing animals. Movement is related to water discharge, temperature, and season, and occurs predominantly downstream and at night. Growth is asymptotic and seasonal. At the end of larval life, the ammocoete ceases to increase markedly in length and starts to accumulate lipid. Length–frequency curves and data on kidney growth indicate that, in relatively stable and productive sites, ammocoetes of long established populations of the landlocked and anadromous sea lamprey take ~ 5 yr to reach metamorphosing length. Many animals probably enter transformation within a further 3 yr. information from an isolated population in the Big Garlic River and from other tributaries of lakes Superior and Michigan, some of which had been treated with larvicide, shows that the onset of metamorphosis can be highly variable and is apparently related to the growth rates and size of larvae. A short larval life is usually associated with a fast growth rate of ammocoetes, as is sometimes found in rivers where the use of larvicide has reduced population density. The landlocked sea lamprey tends to metamorphose at a longer length and at a greater age than other parasitic lampreys. During metamorphosis, which usually begins in the summer, lampreys maintain length but lose weight as a result of mobilization of lipid. The time between initiation of transformation and onset of feeding is generally 4–10 mo. The downstream migration of metamorphosed animals is nocturnal and is influenced by freshwater discharge. Comparisons are drawn between the sex ratios of sea lampreys in the upper Great Lakes and those of other populations.Key words: ammocoete, habitats, growth, mortality, larvicide, lipid, metamorphosis, migration, sex ratio, Great Lakes
Feeding of Larval Lamprey
Authors: Moore James W. , Mallatt Jon M.
Published: April 2008

The feeding mucus in larval lamprey is produced by the lateral walls of the pharynx and by glandular goblet cells on gill filaments. The mucous complex has 14 lateral branches which move inward to the middle of the pharynx, where they are collected and directed back to the esophagus. Mucus, which is carried by intrapharyngeal ciliary tracts and water currents, fills virtually every space in the pharynx, resulting in high (75%) entrapment efficiency. Based on indirect calculations, algae accounted for only 0.14–1.5% of the gut contents in larvae of European brook lamprey (Lampetra planeri). Although the bacterial film associated with algae, detritus, and sand grains may be an energy source for ammocoetes, suspended bacteria cannot support growth in laboratory experiments. Selective feeding on different species of algae is common among lampreys and is based on three factors: (1) susceptibility to capture in the feeding–respiratory flow differs among particles, (2) filtration of long filaments by the oral cirri, and (3) selective agglutination at the mucous filter. Fragilaria, Cocconeis, and Oscillatoria species are present in relatively low numbers in the gut whereas Navicula species are ingested with greater frequency than they occur in the environment. The size distribution of ingested particles is, in general, independent of the size of the ammocoete. Feeding rate depends on temperature and to a lesser extent, food density. In the laboratory, ammocoetes digest and assimilate only 30–40% of the protein, lipid, and carbohydrate (excluding cellulose) and 6–7% of the cellulose in their food. Therefore, larvae of many species pass large quantities of undigested algae and other food through their guts, particularly at low temperatures.Key words: algae, ammocoetes, assimilation efficiency, bacteria, detritus, feeding, lamprey, mucous complex
Neurophysiology of Lampreys
Authors: Rovainen Carl M.
Published: April 2008

The nervous system of the lamprey has been appreciated by comparative neuroanatomists for nearly a century as a "prototype" for the brain and spinal cord of higher vertebrates. Only recently have neurophysiologists discovered the practical advantages of the lamprey brain and spinal cord, such as relative simplicity, survival in isolation, and the occurrence of large, visible, nerve cells and axons. During the past 15 yr rapid progress has been made in understanding the basic physiological, pharmacological, and ultrastructural properties of lamprey neurons and the organization of sensory and motor systems. Several types of neurons are now known in considerable detail and include the prominent Müller and Mauthner cells, respiratory and spinal motoneurons, giant interneurons, and sensory dorsal cells. Some of the important subjects for future research include the behavioral responses of adult lampreys to different modes of sensory stimulation, the neural control of feeding, and the changes which occur in the nervous system during metamorphosis.Key words: brain, lamprey, neurophysiology, respiration, spinal cord, swimming
Sea Lamprey (Petromyzon marinus) in Lakes Huron, Michigan, and Superior: History of Invasion and Control, 1936–78
Authors: Smith B. R. , Tibbles J. J.
Published: April 2008

Sea lamprey (Petromyzon marinus) entered the upper three Great Lakes in the late 1930s and began making sharp inroads into the fish stocks by the mid-1940s in lakes Huron and Michigan and the mid-1950s in Lake Superior. The first serious attempts to control the parasite began in 1950 with the installation of mechanical barriers along the United States shore of Lake Huron to block spawning runs. Electrical barriers, developed in 1952, were installed in 132 tributaries of the Great Lakes by 1960, but control measures did not become effective until after 1958, when a selective toxicant — the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) — was used to destroy larval lampreys in streams. In the 21 years, 1958–78, 1223 treatments of tributaries of the upper three lakes with TFM were completed in 334 streams — 91 in Canada and 243 in the United States. Evidence of the success of the control program was soon obvious: first by reduced sea lamprey spawning runs as measured by the numbers of adults taken at electrical barriers; second by significant decreases in the incidence of sea lamprey wounds on lake trout (Salvelinus namaycush); and finally by the excellent responses of major fish stocks to sea lamprey control. All three of the upper lakes have large numbers of lake trout, coho salmon (Oncorhynchus kisutch), chinook salmon (O. tshawytscha), and other salmonids available to the sport fishery and in some areas to the commercial fishing industry. Although the sea lamprey control program has been successful, it is important that emphasis be placed on developing new and innovative methods to reduce the dependence on lampricides. It is expected that a fully integrated program will eventually comprise several methods, including permanent barrier dams on selected streams and the use of sterilants, attractants, repellents, and biological controls, as well as chemical lampricides.Key words: sea lamprey, distribution, abundance, history, predation, integrated controls, Huron, Michigan, Superior
Factors Influencing the Distribution of Sea Lamprey (Petromyzon marinus) in the Great Lakes
Authors: Morman R. H. , Cuddy D. W. , Rugen P. C.
Published: April 2008

The sea lamprey (Petromyzon marinus) is widely distributed in the Great Lakes but it is absent from or scarce in large parts of the watershed. Since 1957, larval sea lampreys have been detected in only 433 (7.5%) of the 5747 streams in the Great Lakes basin. Parasitic-phase sea lampreys range throughout the lakes, wherever suitable host fishes occur, but probably do not inhabit the western and central basins of Lake Erie to any great extent during summer. Many environmental conditions influence the distribution of sea lampreys. Streamflow and water temperature are of major importance in attracting spawning runs to streams. The dispersal of spawning adults within streams is influenced mainly by blockages, water temperature, current, bottom type, and the presence of inland lakes. Water temperature is probably the most important factor affecting the development and survival of embryos. The distribution of larval lampreys is limited primarily by barriers that block adult spawning runs, warm temperatures, low and unstable flows, hard stream bottom, and pollution; nonetheless, larvae have been found in a wide range of habitats exhibiting these conditions. Interconnecting waterways and attachment to fishes and boats are considered major factors in the lake movements of parasitic-phase lampreys.Key words: sea lamprey, Petromyzon marinus; Great Lakes, geographic distribution, influences, movement, spawning, larvae, parasitic, control
Changes in the Distribution of Native Lampreys in Lake Superior Tributaries in Response to Sea Lamprey (Petromyzon marinus) Control, 1953–77
Authors: Schuldt R. J. , Goold R.
Published: April 2008

Populations of three species of lampreys, American brook lamprey (Lampetra lamottei), northern brook lamprey (Ichthyomyzon fossor), and silver lamprey (I. unicuspis), endemic to the Lake Superior drainage basin have declined since chemical control of the sea lamprey (Petromyzon marinus) was begun; 64% (103 of 162) of the streams inhabited by endemic species have required treatment. The parasitic silver lamprey was most adversely affected by lampricide applications. Though 4278 were captured at 35 of 55 Lake Superior barriers in 1959, a total of 91 were reported in only nine tributaries and the St. Marys River from 1973 to 1977. American brook lampreys were least affected by chemical control and have disappeared from 6 of 42 treated streams which they inhabited. Ichthyomyzon larvae are no longer found in 41 of 81 treated streams they once inhabited, though few larvae were found in many of these streams. Several factors affected the vulnerability of native lampreys to chemicals. Nonparasitic lampreys, especially American brook lampreys, inhabited headwater areas which were often not invaded by sea lampreys, but silver lampreys spawned in lower reaches and their entire stream distribution was exposed to the effects of the lampricide. Differences in fecundity of lampreys also affected their recovery after chemical treatments.Key words: Ichthyomyzon fossor, ichthyomyzon unicuspis, Lampetra lamottei, streams, distribution, habitat, temperature, fecundity, survival, TFM
Effects of Control of the Sea Lamprey (Petromyzon marinus) on Migratory and Resident Fish Populations
Authors: Dahl F. H. , McDonald R. B.
Published: April 2008

Information from the records of the various agencies on control of the sea lamprey (Petromyzon marinus) was summarized from the early approach to control by mechanical or electrical barriers and chemical toxicants. While fish kill has been an inescapable consequence of the program, information available for migratory species has shown no large-scale detrimental effects. The only reportable instance of damage to a resident stream species has been the near loss of the stonecat (Noturus flavus) from tributaries to the southwest corner of Lake Superior, resulting from chemical treatments. Although no similar occurrences were recognized, available documentation proved inadequate to record long-term effects on these vulnerable species. As long as existing control methods continue, no matter the precautions taken, fish populations will be affected. Whether or not this remains a tenable situation is a question for this symposium and the future.Key words: weirs, chemicals, fish kills, sea lamprey, Petromyzon marinus; Catostomus catostomus, Catostomus commersoni, Noturus flavus, Salvelinus fontinalis
Effects of Sea Lamprey (Petromyzon marinus) Control in the Great Lakes on Aquatic Plants, Invertebrates, and Amphibians
Authors: Gllderhus P. A. , Johnson B. G. H.
Published: April 2008

The chemicals 3-trifluoromethyl-4-nitrophenol (TFM) or a combination of TFM and 2′,5-dichloro-4′-nitrosalicylanilide (Bayer 73) have been used to control the sea lamprey (Petromyzon marinus) in the Great Lakes for about 20 yr. These chemicals cause some mortalities of Oligochaeta and Hirudinea, immature forms of Ephemeroptera (Hexagenia sp.), and certain Trichoptera, Simuliidae, and Amphibia (Necturus sp.). The combination of TFM and Bayer 73 may affect some Pelecypoda and Gastropoda, but its overall effects on invertebrates are probably less than those of TFM alone. Granular Bayer 73 is likely to induce mortalities among oligochaetes, microcrustaceans, chironomids, and pelecypods. No evidence exists that the lampricides have caused the catastrophic decline or disappearance of any species. The overall impact of chemical control of sea lampreys on aquatic communities has been minor compared with the benefits derived.Key words: sea lamprey control, Great Lakes, TFM, Bayer 73, aquatic plants, invertebrates, amphibians
European River Lamprey (Lampetra fluviatilis) Fishing and Lamprey Populations in some Rivers Running into Bothnian Bay, Finland
Authors: Valtonen Tapani
Published: April 2008

The coastal region of Bothnian Bay is now the center of fisheries for European river lamprey Lampetra fluviatilis in Finland. This species has been studied in the Kalajoki and Pyhäjoki rivers and data are also available from the Lestijoki River. In the Kalajoki River in 1977, 30 fishermen operating 70 trap nets and 900 basket traps caught about 134 000 lampreys. Fewer traps were used by a smaller number of fishermen in 1978, but the catch remained the same. In the Pyhäjoki River in 1977, 50 fishermen operating 50 trap nets and 330 basket traps caught 184 000 lampreys. In 1978 fewer traps were used by a smaller number of fishermen and the catch was 93 000 lampreys. Tagging indicated that about 80% of the upstream migrants (estimated at 200 000 in 1977) were being captured in the Kalajoki River, but only about 65% in the Pyhajoki River (estimated at 400 000 – 500 000 in 1977). Reasons for the differences between rivers and years are discussed.Key words: Lampetra fluviatilis, Finland, fishery, rivers
Decline and Recovery of the Lake Superior Gull Island Reef Lake Trout (Salvelinus namaycush) Population and the Role of Sea Lamprey (Petromyzon marinus) Predation
Authors: Swanson Bruce L. , Swedberg Donald V.
Published: April 2008

The Gull Island Reef lake trout (Salvelinus namaycush) population was one of the few in Lake Superior that was not annihilated by the combined effects of excessive fishing and sea lamprey (Petromyzon marinus) predation. Following control of the lamprey in the early 1960s, this population of lake trout began a slow but steady increase in the average age and numbers of lake trout. Total annual mortality rates for spawning lake trout were 32% for age VI fish, 48% for ages VII–VIII, and 75% for ages IX and older. These total mortality rates included a 7.3% exploitation rate u, a 20% natural mortality n, and annual lamprey-induced mortalities of 6% for ages V–VI, 24%, for ages VII–VIII, and 56% for ages IX and older fish. The estimated number of lake trout eggs deposited annually on Gull Island Reef from 1964 to 1979 ranged from 3.3 million eggs in 1965 to 28 million eggs in 1979, with a mean of 9 million eggs per year. At present levels of lamprey predation, the estimated egg to spawning fish return rate on Gull Island Reef is 0.18%.Key words: lake trout, sea lamprey, survival, population structure, egg deposition
Role of Physical Barriers in the Control of Sea Lamprey (Petromyzon marinus)
Authors: Hunn J. B. , Youngs W. D.
Published: April 2008

Mechanical and electromechanical barriers played a significant role in the initial attempts to control sea lamprey (Petromyzon marinus) populations in the upper Great Lakes. More recently electromechanical weirs have been used to assess the relative abundance of spawning-run sea lampreys in Lake Superior. Development of an integrated control approach to sea lamprey control has stimulated an ongoing research program to define structural and/or velocity criteria that can be used to design barrier dams that block spawning runs of sea lamprey.Key words: sea lamprey, Petromyzon marinus; physical barriers, burst swimming speed, barrier dam criteria
Sea Lamprey (Petromyzon marinus) Control — Where to From Here? Report of the SLIS Control Theory Task Force
Authors: Lamsa A. K. , Rovainen C. M. , Kolenosky D. P. , Hanson L. H.
Published: April 2008

Sea lamprey (Petromyzon marinus) control with selective toxicants has reduced sea lamprey abundance in the Great Lakes to levels which permit survival of desirable fish species, but development of alternate and supplemental control methods is essential since chemicals cannot be used indefinitely. The Task Force addressed hypotheses which relate to regulation of sea lamprey numbers during different life history stages and why sea lampreys appear to affect fish stocks differently in various bodies of water. Examination of the information about the various factors that control sea lamprey abundance, both natural and man-made, permitted the Task Force to develop several hypotheses and to indicate areas where additional emphasis or research could produce new or supplementary control methods. Efforts to develop an integrated program of sea lamprey control should be accelerated by development of present promising areas as well as expansion in new directions. Sea lampreys when compared with teleosts exhibit many features of a prototype vertebrate and some unique specializations. Physiological, biochemical, or behavioral differences between lampreys and teleosts may be exploitable for developing control techniques specific to sea lampreys.Key words: sea lamprey, Great Lakes, population control, barrier dams, integrated pest management, buffer species, physiology, teleosts
Cadmium in Sea Scallop (Placopecten magellanicus) Tissues from Clean and Contaminated Areas
Authors: Uthe J. F. , Chou C. L.
Published: April 2008

Over 90% of the total cadmium in the soft tissues of sea scallops (Placopecten magellanicus) was in the digestive gland with less than 1% in the adductor muscle. The amount of cadmium in the digestive gland was significantly related to shell height. Shell height was superior to age as an independent (predictor) variable due to difficulties in ageing scallops. Based on these relationships, scallops of approximately 100 mm shell height were selected to study interregional differences. Neither cadmium concentration nor burden could be used to identify contaminated areas. The ratio of digestive gland cadmium to that in the adductor muscle was lowest for scallops from Chaleur Bay, which had received substantial anthropogenic cadmium input, and for scallops that had been starved for approximately 14 mo. We suggest that the high tissue cadmium levels in scallops from Georges Bank and Browns Bank are not due to contamination from anthropogenic or natural sources but rather reflect feeding and the nutritional inadequacy of the diets. Conversely, the high levels of cadmium input to Chaleur Bay were not reflected in high tissue concentrations or burdens in scallops.
Acclimation to Copper by Rainbow Trout,Salmo gairdneri: Biochemistry
Authors: Laurén Darrel Jon , McDonald D. G.
Published: April 2008

Whole body, gill, and liver copper uptake, gill Na+-K+-ATPase specific activity, and gill and liver acid-soluble thiols (AST), glutathione, and cysteine of rainbow trout (Salmo gairdneri) were measured during 28 d of exposure to 55 μg copper∙L−1. Na+-K+-ATPase specific activity was inhibited by 33% within 24 h of copper exposure, but this was compensated by a significant increase in microsomal protein so that the total Na+-K+-ATPase activity per milligram of gill tissue returned to normal by day 14. There was no accumulation of copper and no increase in AST, glutathione, or cysteine in the gill. However, after 7 d of exposure, hepatic AST and glutathione had increased by about 2 times, and a sulfhydryl-rich, acid-soluble protein, tentatively identified as metallothionein, increased by 2.8 times. Copper accumulation was highest in the liver, but other tissues also accumulated copper.
Decomposition of Seston in the Hyolimnion
Authors: Cornett R. J. , Rigler F. H.
Published: April 2008

In 12 lakes a significant fraction of the hypolimnetic oxygen deficit was produced by the respiration of seston in the hypolimnetic water column. Mean summer seston respiration rates ranged between 4 and 80 mg O2∙m−3∙d−1. Rates of seston respiration were proportional to the in situ water temperature and to the concentration of Chlorophyll a. The amount of oxygen consumed in the water column and the fraction of the total oxygen deficit produced by sestonic respiration were correlated with the amount of phosphorus sedimented from the epilimnion. Fifteen to 66% of the total oxygen consumption occurred in the water column of the hypolimnion. Seston respiration was a larger proportion of the total respiration in the hypolimnion of lakes with a thick hypolimnion than in lakes with a shallow hypolimnetic water column.
Effect of Changes in Zooplankton on Orthophosphate Dynamics of Natural Phytoplankton Communities
Authors: McCauley Edward , Kalff Jacob
Published: April 2008

Replicate algal communities were isolated from Lake Memphremagog (Quebec–Vermont) in large–volume enclosures, and the abundance of herbivores was changed in them to produce a gradient of herbivore biomass among enclosures. The performance of the phytoplankton and their phosphorus uptake was observed in response to these different levels of crustacean Zooplankton biomass. In general, reducing Zooplankton biomass did not lead to phosphorus-deficient algal communities. Seven field experiments were done in 1979, 1980, and 1981 Only two of these experiments produced algal communities in which the cycling rate of orthophosphate per unit algal biomass was modified by reduction of crustacean Zooplankton biomass.
Simplified Version of the Ampoule–Persulfate Method for Determination of Dissolved Organic Carbon
Authors: McDowell William H. , Cole Jonathan J. , Driscoll Charles T.
Published: April 2008

A simplified method for the determination of dissolved organic carbon is based upon the ampoule–persulfate wet digestion procedure. The modification proposed involves use of a continuous stream of sparging gas (technical grade oxygen) during the ampoule sealing process to minimize entry of combustion products from the sealing flame. The method provides reliable results with a minimum of training and equipment compared with other methods of sealing ampoules. Further, the proposed method is inexpensive, relatively simple, and compares favorably with costly, automated analysis of dissolved organic carbon.
Periphyton in Lakes of Different Trophy
Authors: Cattaneo Antonella
Published: April 2008

In a study of 10 lakes in the Eastern Townships (Quebec) periphyton biomass correlated less well with total P (TP) concentration in the water than did phytoplankton biomass. The relationship with TP was improved somewhat when periphyton biomass was estimated as cell volume rather than as chlorophyll or organic material. When the community was divided among various groups according to taxa, life form, and size, only the biomasses of greens, filamentous algae, and algae exceeding 10 000 μm3 were correlated with TP. The biomass of the smaller algae, which are more readily grazed by benthos, was about the same in all lakes whereas nuisance forms increased significantly with P enrichment. At more eutrophic sites, maximal periphyton biomasses were observed in midsummer, coinciding with peak recreational use of lakes, whereas at the other sites, maxima appeared earlier in the season.
Relation between Aiming and Catch Success in Larval Fishes
Authors: Drost Maarten R.
Published: April 2008

The actual attack of prey by common carp (Cyprinus carpio) and northern pike (Esox lucius) larvae, lasting 5–20 ms, was described using high-speed cinematography showing synchronous lateral and ventral views. The accuracy of aiming at the prey was measured. A model comparing the ratio mouth radius/aiming inaccuracy to catch success of stationary prey accurately predicted catch success for larval carp feeding on Artemia nauplii and for larval pike feeding on Daphnia. The increase in catch success during ontogeny was caused by an increase in the ratio mouth radius/aiming inaccuracy. Maximal suction velocity in the water flow created by pike larvae (14 mm standard length) was 0.84 m/s, much higher than the escape velocities of even calanoid copepods. Nevertheless, even Daphnia could sometimes escape the suction flow by jumping away. The relative importance of aiming and speed of attack on catch success depended on prey species. Prey size seemed unimportant in determining catch success.
Sedimentation Rates and Sediment Core Profiles of 238U and 232Th Decay Chain Radionuclides in a Lake Affected by Uranium Mining and Milling
Authors: McKee P. M. , Snodgrass W. J. , Hart D. R. , Duthie H. C. , McAndrews J. H. , Keller W.
Published: April 2008

Radionuclide concentration profiles in sediment cores from three deep basins of Quirke Lake, Ontario, showed enrichment in the surficial layers related to the period of uranium mining in the watershed, based on sedimentation rates determined from a milling-related pH decline indicated by fossil diatoms. Recent sedimentation rates are 96 ± 7 to 185 ± 14 g∙m−2∙yr−1. 210Pb profiles could not be used to determine sedimentation rates due to loadings of 226Ra and 210Ph from mining and milling activities. Profiles of 238U and 232Th decay chain radionuclides showed an enrichment of 1–3 orders of magnitude in surficial sediments relative to background in deeper sediments. Radionudide levels in surficial sediments exceeded those reported in lake sediments in uncontaminated systems and, for some radionuclides, approached or equalled levels in sediments contaminated with uranium and radium refining residues. Radionudide activity ratios in the surficial layers of the Quirke Lake cores and in downstream sediments demonstrated the relative mobilities of the elements in the watershed. Net sediment loading rates for radionuclides in the three basins were 130–230 mg∙m−2∙yr−1 for U, 340–4000 Bq∙m−2∙yr−1 for other members of the 238U decay chain, and 210–530 Bq∙m−2∙yr−1 for 232Th and 228Th.
Evaluating Potential Sources of Mortality for Larval Bloater (Coregonus hoyi): Starvation and Vulnerability to Predation
Authors: Rice James A. , Crowder Larry B. , Binkowski Fred P.
Published: April 2008

We evaluated the relative importance of starvation and predation as potential sources of mortality for larval bloater (Coregonus hoyi) in the laboratory. Fifty percent of starved bloater larvae survived 25 d after hatching; some individuals survived 35–40 d. Bloater larvae did not exhibit a point of no return, but length and weight after 30 d were inversely related to the delay in first feeding. Bloaters were swimming about half of the time within 1 h after hatching and almost continuously after 6 h. Twenty-one days after hatching, starved larvae were still swimming continuously at 0.9 cm∙s−1; fed larvae swam more than four times faster. Bloater larvae up to 30 d old were captured with about 80% success by 95- and 135-mm bloaters and 100-mm alewives (Alosa pseudoharengus). Susceptibility to predators generally decreased with increasing size, and starved larvae were more susceptible than similar sized fed larvae. Because of their swimming ability and resistance to starvation, it seems unlikely that bloater larvae starve to death in nature. However, starvation can contribute to mortality, as reduced growth and swimming capabilities may result in increased or prolonged susceptibility to predation.
Nutrient Limitation of Phytoplankton Growth in Brackish Coastal Ponds
Authors: Caraco Nina , Tamse Armando , Boutros Osiris , Valiela Ivan
Published: April 2008

In general, the nutrient most limiting to phytoplankton growth is phosphorus in freshwaters and nitrogen in the sea. We investigated the effect of N and P enrichment to waters from seven brackish, coastal ponds ranging in salinity from 0 to 31 ppt and to nearby coastal seawater (32 ppt). Phytoplankton from the least saline ponds (0–6.5 ppt) responded to P additions, and biomass increased 2–6 times over unenriched controls. Nitrogen additions stimulated phytoplankton growth only in waters from the most saline coastal pond (31 ppt) and seawater. Phytoplankton from ponds of intermediate salinity did not respond when either N or P was added alone but, as in all ponds, increased greatly in biomass when N and P were added in combination. The high salinity at which a switch from P to N limitation occurred could be due to the high N:P loading ratios to these ponds.
Modification of Carbohydrate Metabolism and Liver Vitellogenic Function in Brook Trout (Salvelinus fontinalis) by Exposure to Low pH
Authors: Tam W. H. , Birkett L. , Makaran R. , Payson P. D. , Whitney D. K. , Yu C. K.-C
Published: April 2008

Brook trout (Salvelinus fontinalis), 1+ yr old, were exposed to pH 4.48 from February to December. Compared with control fish maintained at pH 7.34, acid-stressed fish generally had elevated blood glucose levels. Plasma cortisol concentration, measured only in males, was significantly increased in the acid-treated trout up to July. Although somatic growth decreased by about 30% by the end of the experiment, peritoneal fat was unchanged. During the reproductive season, female plasma levels of oestrogen and vitellogenin were the same at both pH levels. When immature fish were implanted with oestradiol-17β and then maintained for 21 d either in pH 7.34 (control) or 4.48, acid-treated fish again showed increased blood glucose levels. Liver weight increased at both pH levels, but liver glycogen was depleted and plasma vitellogenin was significantly increased by exogenous oesterogen only in control fish. It is postulated that before acclimation occurs, acid stress increases cortisol secretion, diverts nutrients normally used for growth to maintain a high blood sugar level, and affects the liver's ability to metabolize carbohydrates and synthesize vitellogenin.
Use of Echosounder Tracings to Estimate the Aboveground Biomass of Submerged Plants in Lakes
Authors: Duarte Carlos M.
Published: April 2008

A method is presented to estimate the aboveground biomass of submerged macrophytes in lakes from echosounder tracings and from the growth form of the dominant species in the stand. The equation is[Formula: see text]where species that reach the surface to flower are categorized as form class 1, short understory species with floating flowers as form class 2, and species with underwater flowers, those lacking flowers, and those that, although able to produce flower, never flower in nature as form class 3. The standard error of the estimates is 421 g fresh wt.∙m−2, a value comparable with the standard error of direct harvest by SCUBA divers. The echosounder-based method is limited to stands growing at depths greater than 70 cm with plants taller than 20 cm.
Optimal Policies for Rehabilitation of Overexploited Fish Stocks Using a Deterministic Model
Authors: Hightower Joseph E. , Grossman Gary D.
Published: April 2008

Traditional fisheries models are of limited use during the transitional period when effort is reduced to permit recovery of an overexploited stock. We used a generalized age-structured model to represent stock dynamics during this transitional period and obtained optimal harvesting policies for three overexploited fish stocks using a first-order gradient procedure. The length of the rehabilitation period was affected by (1) the demographic characteristics of the stock, (2) the historical level of exploitation, and (3) the form of the objective function. When a target stock biomass or spawning stock was specified, rehabilitation was relatively rapid due to the sharp initial reduction in fishing effort. Fishing began earlier in the planning horizon when a target harvest was specified; however, stocks recovered more slowly and fishing effort and harvest did not stabilize at the desired levels as rapidly. Policies for maximizing harvest did not usually result in closure of the fishery; however, fishing effort usually exceeded the desired level and sometimes fluctuated considerably from year to year. Our results should aid in the development of rehabilitation policies tailored to specific fisheries or specific management goals.
Electrophoretic Variation, Regional Differences, and Gene Flow in the Coho Salmon (Oncorhynchus kisutch) of Southern British Colombia
Authors: Wehrhahn C F. , Powell R.
Published: April 2008

Populations of coho salmon (Oncorhynchus kisutch) in southern British Columbia were assayed for genetic variation at 26 enzyme loci. The mean heterozygosity was only 0.25 ± 0.06%. Previously studied wild Oregon cohos had a mean heterozygosity of 1.36 ± 0.37% compared with 0.30 ± 0.09% in Lower Coastal Mainland and 0.13 ± 0.08% in Upper Fraser River fish for the same enzyme loci. A plausible explanation for the very low mean heterozygosity is that British Columbia coho salmon went through an extreme population bottleneck during or after the last ice age. Lower Coastal Mainland salmon are significantly different from the fish of Vancouver Island and can be easily distinguished from Oregon and Capilano Hatchery (Coastal Mainland, B.C.) fish, it should be feasible to determine the relative proportions of different stocks in large oceanic coho salmon samples. The maximum likelihood estimate of the migration rate between spawning populations is 5.8 ± 1.2 breeding adults per generation. This is enough to prevent adaptation to local habitats by small populations of fewer than 100 breeding adults, but it is not high enough to impede selection in large populations of 1000 or more breeding adults.