bluuebunny/crossref_metadata_2025_split huggingface dataset:
Population biology and stock assessment of Pristipomoides filamentosus on the Mahe Plateau, Seychelles
Authors: Mees C. C. 
Published: April 2005

The population of P. filamentosus around the periphery of the Mahe Plateau was studied using data derived from commercial handline fishing operations between November 1989 and December 1990. Sex ratio was close to one. Fork length was in the range 25.6–79.8 cm: at first sexual maturity, 36–38 cm for females and 40–42 cm for males. Spawning occurred from October to April peaking between February and April and in November.The length (f.l., cm)–weight (kg) relationship was W=0.00005353 ×f.l.2.7004. The von Bertalanffy growth parameters, estimated from length frequency data, were K=0.2875 and Linf=81.7 cm. Mortality rates, estimated from length converted catch curve analysis, were Z=0.811, F=0.277 with M=0.534 derived from Pauly's empirical formula. Jones' length cohort analysis gave an estimate of F= 0.294 for the fully exploited part of the stock, and a density of 2.59 t km−2 for the periphery of the plateau from 75 to 150 m depth. The Lesley constant catchability model, applied to the results of intensive fishing around isolated banks, derived a mean density estimate of 2.99t km−2. The sustainable yield was estimated to be 233–268 tonnes per annum and the catch in 1990 was 200 tonnes.
Effects of experimental seismic shock on vasoactivity of arteries, integrity of the vascular endothelium and on primary stress hormones of the Atlantic salmon
Authors: Sverdrup A. , Kjellsby E. , Krüger P. G. , Fløysand R. , Knudsen F. R. , Enger P. S. , Serck‐Hanssen G. , Helle K. B. 
Published: April 2005

The postulated harmful effects of underwater detonations of explosives on the vascular endothelium in farmed Atlantic salmon were assessed under controlled conditions. Acclimated salmon were exposed to a series of 10 underwater explosions over 70 min, each of ≃2 MPa in pressure amplitude, in a laboratory tank. No mortality occurred immediately or during the subsequent 7 days of observation. The response to each of the 10 detonations was cessation of swimming for a few minutes and failure to express a flight reaction.Structurally, the vascular endothelium of the ventral aorta (VA) and the coeliaco mesenteric artery (CMA) revealed signs of injury within the first 30 min after the experimental shock. In contrast to vessels from the controls, the injury was further aggravated by the mounting procedure for tension recording. The endothelial impairment was temporary, persisting throughout the first days while being restored after 1 week.Functionally, the cholinergic and adrenergic vasoconstrictor responses in the CMA were markedly reduced during the first day after the shock. These responses were similar to those observed in the endothelium probed CMA of controls. The loss of structural integrity and the reduced functional responses indicated a temporary impairment of the vascular endothelium in response to this experimental simulation of a seismic shock.The primary stress hormones, adrenaline and cortisol, were not immediately elevated in plasma, but revealed different patterns of delayed increases. The head kidney content of catecholamines was not altered by the acoustic shock, while the atrial uptake of both calecholamines declined progressively during the 48 h of observation. Plasma chloride was not affected.
Differences in digestion and absorption of dietary protein in Atlantic salmon (Salmo salar) with genetically different trypsin isozymes
Authors: Torrissen K. R. , Lied E. , Espe M. 
Published: April 2005

Digestion and absorption of dietary protein were studied through facilitation of amino acid in the plasma and white muscle after a single feeding. The comparison was made between Atlantic salmon with and without trypsin isozyme TRP‐2*92. Higher absorption of dietary protein was associated with the presence of the isozyme, as the post‐prandial total levels of free amino acids (FAA) in both plasma and white muscle were significantly higher in salmon with the isozyme than those in salmon without it. Higher digestion rate of the dietary protein in salmon carrying the isozyme was indicated by faster elevation of essential FAA in the plasma and of overall FAA in their white muscle. Other indications which suggest differences in nitrogen metabolism between salmon with and without the isozyme were the observations of significant differences in (a) the levels of lysine, hydroxyproline, alanine, aspartic acid, β‐alanine, threonine, valine and a nitrogen‐containing compound taurine in plasma, and (b) the levels of alanine, glutamic acid, glycine and anserine in white muscle.Trypsin activity in the pyloric caeca showed less response to feeding than that in the intestine, but it may have consequence for growth as its activity was significantly higher in growing fish than in non‐growing fish.
Numbers of muscle nuclei and myosatellite cell nuclei in red and white axial muscle during growth of the carp (Cyprinus carpio)
Authors: Koumans J. T. M. , Akster H. A. , Witkam A. , Osse J. W. M. 
Published: April 2005

We determined the percentages of muscle fibie nuclei and satellite nuclei over a growth range of carp (Cyprinus carpio), as the increase in the number of muscle fibre nuclei is an important aspect of the increase in muscle mass, and myosatellite cells are believed to be the source of new muscle fibre nuclei. In white as well as in red axial muscle the percentage of the nuclei present in muscle that are muscle nuclei (muscle fibre nuclei+myosatellite nuclei) remained constant during growth (54 and 32% respectively). The difference in the percentage of non‐muscle nuclei between white and red axial muscle is mainly caused by the higher content of endothelial nuclei in red axial muscle.In white axial muscle the DNA/protein ratio (nucleus/sarcoplasm ratio) decreased between 3 and 15 cm S.l. In red axial muscle we found a continuous decrease in DNA/protein ratio over the entire investigated size range (3–50 cm s.l.). This may be related to a longer occurrence of hyperplasia in red than in white axial muscle.In both fibre types the percentage of muscle nuclei being myosatellite nuclei decreased with increasing length, In white axial muscle it decreased from about 5% in carp of 5 cm s.l. to less than 1% in carp of 20 cm S.L.; for red muscle these values were 11 and 3% respectively.For white axial muscle we calculated that, especially in larger fish, the myosatellite ceils alone cannot account for the increase in the number of muscle fibre nuclei during growth. The percentage of proliferating nuclei in muscle tissue, measured by the uptake of 5‐bromo‐2′‐deoxy‐uridine, is high enough to account for the total increase in nuclei. So indirect evidence is available that another cell type present in the muscle tissue may also be involved in the formation of additional muscle fibre nuclei.
Respiratory‐cardiovascular physiology and chloroethane gill flux in the channel catfish, Ictalurus punctatus
Authors: McKim J. M. , Nichols J. W. , Lien G. J. , Bertelsen S. L. 
Published: April 2005

A fish respirometer‐metabolism chamber was used to obtain in vivo respiratory‐cardiovascular and chloroethane gill flux data on transected channel catfish (Ictalurus punctatus). Methods used for spinal transection, attachment of an oral membrane (respiratory mast), placement and attachment of blood cannulas and urine catheters are described. Respiratory physiology, cardiac output and chemical extraction efficiencies for 1,1,2,2‐tetrachloroethane (TCE), pentachloroethane (PCE), and hexachloroethane (HCE) were determined on 419–990 g catfish. The overall mean values (± s.d.) for ventilation volume (Qv), effective respiratory volume (Qw), oxygen consumption (Vo2 and percentage utilization of oxygen (U) were 17‐3 ±4–71 h−1 kg−1, 9·8±l·71 h−1 kg−1, 71·6±12·5mg h−1 kg−1, and 49± 10%, respectively, while cardiac output calculated via the Fick Method was 2·4±0·61 h−1 kg−1. Additional measurements were made on ventilation rate (Vr), total plasma protein, haematocrit (Hct), and urine volume; while both arterial and venous blood were analysed for pH, oxygen partial pressure (P02), carbon dioxide partial pressure (Pco2), total oxygen (To2), total carbon dioxide (Tco2) and total ammonia (TAMM). Physiological measurements taken at 24 h were not significantly different from those taken at 48 h and indicated no deterioration of the in vivo preparation. All of these values agreed well with literature values on UTitransected channel catfish, except for Hct which was lower for cannulated animals used in this study. Overall, these data provide strong support for the use of transected channel catfish for in vivo collection of physiological and chemical gill flux data.The mean initial chemical extraction efficiencies for TCE, PCE and HCE were 41, 61 and 73%, respectively. Chemical clearances (ClX) for these same three chemicals were 5·9, 9·3 and 10·8 1 h−1 kg−1, respectively. The approximate 1: 1 relationship between effective respiratory volume (Qw) and chemical clearance (Clx) indicated that branchial uptake of PCE and HCE was water flow‐limited. Chemical gill flux observed for channel catfish and chloroethanes was similar to that observed for rainbow trout in previous studies and provided further support for the flow‐limited model of chemical flux across fish gills.
Gonadal development and spawning of female ocean whitefish, Caulolatilus princeps (Pisces: Branchiostegidae) in the Bay of La Paz, B.C.S., Mexico
Authors: Elorduy‐Garay J. F. , Ramirez‐Luna S. 
Published: April 2005

The developmental stages of the gonads and the spawning season of the ocean whitefish, Caulolatilus princeps, were determined. Gonad maturation is annual, and the spawning season is prolonged, from late autumn to early spring. From November to March, around 80% of the females were in an advanced mode of gonadal development, and in April most gonads were spent. From May to October the gonads were at rest and preparing for the next spawning season.The gonadosomatic index describes the reproductive activity of the species adequately.
Population biology of two helminth parasites of flatfishes from the Atlantic coast of Morocco
Authors: Belghyti D. , Berrada‐rkhami O. , Boy V. , Aguesse P. , Gabrion C. 
Published: April 2005

On the Atlantic Moroccan coast, two species of pleuronectiform fish coexist, wedge sole (Citharus linguatula) a temperate species, and spotted flounder (Dicohgoglossa cuneata) a tropical one. These two species are the definitive host for Bothriocephalus andresi and Acanthocephaloïdes propinquus, respectively. A negative binomial fits the dispersion of B. andresi in the population of C. linguatula. The fish become parasitized between their first and third year, while still immature, with the highest abundances in the third year. After the fish become ichthyopagous, the level of infection drops drastically. We postulate that copepods are the sole source of infection. The presence of B. andresi in both Atlantic and Mediterranean populations of C. linguatula shows that the parasite follows the host during its migration along the Mediterranean coasts.The prevalence of A. propinquus remains above 50% as a consequence of the large numbers of amphipods included in the diet of D. cuneata, regardless of the age of the fish or the season. The amphipods, Phtisica marina and Pariambus typicus are an important food and represent potential intermediate hosts for A. propinquus. The population dynamics of A. propinquus on the Atlantic Moroccan coasts are similar to those observed in parasite populations of Gobius niger in the Gulf of Lion (French Mediterranean). The observation of B. andresi and A. propinquus in both Moroccan Atlantic and Mediterranean fishes highlights the problem of the evolution of these parasite populations during the colonization of the Mediterranean by the hosts.
The effects of temperature acclimation on the oxygen consumption and enzyme activity of red and white muscle fibres isolated from the tropical freshwater fish Oreochromis niloticus
Authors: Mwangangi D. M. , Mutungi G. 
Published: April 2005

The standard oxygen consumption rate and the activities of muscle citrate synthase, creatine phosphokinase and lactate dehydrogenase in the tropical fish Oreochromis niloticus acclimated to either 20.5 ± 0.3° C or 26.5 ± 0 ± 5 ± C for at least 3 months were investigated. The standard oxygen consumption rate of individual fish from the two acclimation temperatures was determined at 20, 25 and 30 ± C. At all experimental temperatures, the standard oxygen consumption rate of fish acclimated to 20.5 ± 0.3° C was significantly higher than that of fish kept at 26.5 ± 0.5 ± C. In both groups smaller individuals had a higher oxygen consumption rate than large ones.Analyses of the activity levels of citrate synthase (CS), creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) in both red and white muscles isolated from fish kept under the two temperature regimes were performed at 26 ± C. The activity of CS in both red and white muscles isolated from the 20.5 ± 0.3° C acclimated fish was significantly higher than that of muscles isolated from the 26.5 ± 0.5 ± C acclimation group. Similarly, the CPK activity in white muscles isolated from fish acclimated to 20.5 ± 0.3 ± C was higher than that of muscles obtained from the 26.5 ± 0.5 ± C acclimation group. However, the CPK activity in red muscles isolated from the two fish groups was not significantly different. The opposite results were obtained for LDH activity. For example, the LDH activity of white muscles isolated from fish acclimated to 26.5 ± 0.5 ± C was significantly higher than that of the same muscles but from the 20.5 ± 0.3 ± C acclimated fish. No differences were observed in the LDH activity of red muscles isolated from the two fish groups.
Comparative internal morphology of deep‐sea eels, with particular emphasis on gonads and gut structure
Authors: Flshelson L. 
Published: April 2005

Anatomic and cytological studies of some 110 species of deep‐sea eels of among others the families Congridae, Colocongridae, Heterenchelyidae, Synaphobranchidae, Nettastomatidae, Nemichthyidae, Serrivomeridae, revealed a very high diversity in the visceral organs, especially gonads, guts and kidneys and their relation to the anal opening.The ovaries of various species were either monocyclic, producing eggs periodically, or polycyclic with frequent egg production. Some testes showed synchronous and others asynchronous sperm production. In some of the families, such as Heterenchelyidae, all the gonads are situated post‐anally, in the tail, whereas in Congridae the extent of penetration varies in the different genera, indicating that this family is an artificial one. As some gonads of a few species were found to harbour gametes of the two sexes, the possible occurrence of hermaphroditism is discussed. Melanization of gut was observed in numerous species produced by the penetration of pigmented tissue between the muscle layers of the gut wall or between these and the gut epithelium, this differing between various taxa and in young and adult specimens. The melanization of gut or parts of gut prevent slight (emitted by the swallowed bioluminescent prey) from being seen outside, and in this way protects the eel from predation. Pigmentation also occurs in the kidneys and other explanations for melanization are therefore discussed. In numerous species the gut, kidney and gas chamber partially penetrate into the tail, and as with the gonads, these characters can also be used on eel taxonomy.
CO2and O3effects on host plant preferences of the forest tent caterpillar (Malacosoma disstria)
Authors: Agrell Jep , Kopper Brian , McDonald Evan P. , Lindroth Richard L. 
Published: April 2005

AbstractElevated levels of CO2and O3affect plant growth and phytochemistry, which in turn can alter physiological performance of associated herbivores. Little is known, however, about how generalist insect herbivores respondbehaviorallyto CO2‐ and O3‐mediated changes in their host plants. This research examined the effects of elevated CO2and O3levels on host plant preferences and consumption of forest tent caterpillar (FTC,Malacosoma disstriaHbn.) larvae. Dual choice feeding assays were performed with foliage from birch (Betula papyriferaMarsh.) and aspen (Populus tremuloidesMichx., genotypes 216 and 259). Trees were grown at the Aspen Free Air CO2Enrichment (FACE) facility near Rhinelander, WI, USA, and had been exposed to ambient or elevated concentrations of CO2and/or O3. Levels of nutritional and secondary compounds were quantified through phytochemical analyses. The results showed that elevated O3levels increased FTC larval preferences for birch compared with aspen, whereas elevated CO2levels had the opposite effect. In assays with the two aspen genotypes, addition of both CO2and O3caused a shift in feeding preferences from genotype 259 to genotype 216. Consumption was unaffected by experimental treatments in assays comparing aspen and birch, but were increased for larvae given high O3foliage in the aspen genotype assays. Elevated levels of CO2and O3altered tree phytochemistry, but did not explain shifts in feeding preferences. The results demonstrate that increased levels of CO2and O3can alter insect host plant preferences both between and within tree species. Also, consequences of altered host quality (e.g., compensatory consumption) may be buffered by partial host shifts in situations when alternative plant species are available. Environmentally induced changes in host plant preferences may have the potential to alter the distribution of herbivory across plant genotypes and species, as well as competitive interactions among them.
Variable sensitivity of plant communities in Iceland to experimental warming
Authors: Jónsdóttir Ingibjörg S. , Magnússon Borgthór , Gudmundsson Jón , Elmarsdóttir Ásrún , Hjartarson Hreinn 
Published: April 2005

AbstractFacing an increased threat of rapid climate change in cold‐climate regions, it is important to understand the sensitivity of plant communities both in terms of degree and direction of community change. We studied responses to 3–5 years of moderate experimental warming by open‐top chambers in two widespread but contrasting tundra communities in Iceland. In a species‐poor and nutrient‐deficient moss heath, dominated by Racomitrium lanuginosum, mean daily air temperatures at surface were 1–2°C higher in the warmed plots than the controls whereas soil temperatures tended to be lower in the warmed plots throughout the season. In a species‐rich dwarf shrub heath on relatively rich soils at a cooler site, dominated by Betula nana and R. lanuginosum, temperature changes were in the same direction although more moderate. In the moss heath, there were no detectable community changes while significant changes were detected in the dwarf shrub heath: the abundance of deciduous and evergreen dwarf shrubs significantly increased (>50%), bryophytes decreased (18%) and canopy height increased (100%). Contrary to some other studies of tundra communities, we detected no changes in species richness or other diversity measures in either community and the abundance of lichens did not change. It is concluded that the sensitivity of Icelandic tundra communities to climate warming varies greatly depending on initial conditions in terms of species diversity, dominant species, soil and climatic conditions as well as land‐use history.
Ambient ultraviolet radiation in the Arctic reduces root biomass and alters microbial community composition but has no effects on microbial biomass
Authors: Rinnan R. , Keinänen M. M. , Kasurinen A. , Asikainen J. , Kekki T. K. , Holopainen T. , Ro‐Poulsen H. , Mikkelsen T. N. , Michelsen A. 
Published: April 2005

AbstractWe assessed the effects of ambient solar ultraviolet (UV) radiation on below‐ground parameters in an arctic heath in north‐eastern Greenland. We hypothesized that the current UV fluxes would reduce root biomass and mycorrhizal colonization and that these changes would lead to lower soil microbial biomass and altered microbial community composition. These hypotheses were tested on cored soil samples from a UV reduction experiment with three filter treatments (Mylar, 60% UV‐B reduction; Lexan, up to 90% UV‐B reduction+UV‐A reduction; UV transparent Teflon, filter control) and an open control treatment in two study sites after 3 years' manipulation. Reduction of both UV‐A and UV‐B radiation caused over 30% increase in the root biomass of Vaccinium uliginosum, which was the dominant plant species. UV reduction had contrasting effects on ericoid mycorrhizal colonization of V. uliginosum roots in the two sites, while it had no clear effects on fungal (ergosterol) or microbial biomass (measured both with fumigation–extraction and quantitative lipid biomarker analysis) in soil. However, principal component analysis of lipid biomarkers (phospholipid and glycolipid fatty acid profiles) showed that microbial community composition was altered by UV reduction. Although the UV responses were slight considering the large dose difference between the treatments (from near‐ambient to up to 90% UV‐B reduction), we cannot rule out the possibility that the recovery of ozone layer would change the below‐ground functioning of arctic ecosystems.
Oiling the key hole
Authors: Lafont Frank , Van Der Goot F. Gisou 
Published: April 2005

SummaryMany bacteria have been found to interact with specialized domains, rich in cholesterol and sphingolipids, of the host plasma membrane, termed lipid rafts. The mechanisms that underlie this interaction are starting to be unravelled. In this issue, Hayward et al. show that early effector proteins secreted by type III secretion harbouring Gram‐negative bacteria are in fact cholesterol‐binding proteins. Combined with other recent findings, this work shows that multiple steps leading to infection by these bacteria depend on raft components: activation of secretion, binding, perforation of the host cell membrane and signalling to trigger bacterial engulfment.
Two acid‐inducible promoters from Lactococcus lactis require the cis‐acting ACiD‐box and the transcription regulator RcfB
Authors: Madsen Søren M. , Hindré Thomas , Le Pennec Jean‐Paul , Israelsen Hans , Dufour Alain 
Published: April 2005

SummaryWe previously characterized three Lactococcus lactis promoters, P170, P1 and P3, which are induced by low pH. Here, we identified a novel 14 bp regulatory DNA region centred at around −41.5 and composed of three tetranucleotide sequences, boxes A, C and D. Boxes A and C contribute to P1 activity, whereas box D and the position of boxes ACD (renamed ACiD‐box) are essential to P1 activity and acid response. We also identified a trans ‐acting protein, RcfB, which is involved in P170 and P1 basal activity and is essential for their pH induction. The regulator belongs to the Crp‐Fnr family of transcription regulators. Overexpression of rcfB resulted in increased β‐galactosidase activities and lantibiotic lacticin 481 production from P170‐ and P1‐controlled genes, respectively, in acid condition. RcfB is thus probably activated when cells encounter an acid environment. rcfB is co‐transcribed with genes encoding an universal stress‐like protein and a multidrug transporter. RcfB plays a role in acid adaptation, as the survival rate of an rcfB mutant after a lethal acid challenge was 130‐fold lower than that of the wild‐type strain, when the bacteria were first grown in acidic medium. The groESL promoter includes a sequence resembling an ACiD‐box and the chaperone GroEL production is partly RcfB dependent in acid condition. Our results suggest that the ACiD‐box could be the DNA target site of RcfB.