bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential expression, localization and activity of two alternatively spliced isoforms of human APC regulator CDH1
Authors: ZHOU Yuan , CHING Yick-Pang , NG Raymond W. M. , JIN Dong-Yan
Published: August 2003

The timely destruction of key regulators through ubiquitin-mediated proteolysis ensures the orderly progression of the cell cycle. The APC (anaphase-promoting complex) is a major component of this degradation machinery and its activation is required for the execution of critical events. Recent studies have just begun to reveal the complex control of the APC through a regulatory network involving WD40 repeat proteins CDC20 and CDH1. In the present paper, we report on the identification and characterization of human CDH1β, a novel alternatively spliced isoform of CDH1. Both CDH1α and CDH1β can bind to the APC and stimulate the degradation of cyclin B1, but they are differentially expressed in human tissues and cells. CDH1α contains a nuclear localization signal which is absent in CDH1β. Intracellularly, CDH1α appears in the nucleus whereas CDH1β is a predominantly cytoplasmic protein. The forced overexpression of CDH1α in cultured cells correlates with the reduction of nuclear cyclin A, but the steady-state amount of cyclin A does not change noticeably in CDH1β-overexpressed cells. In Xenopus embryos, ectopic overexpression of human CDH1α, but not of CDH1β, induces cell-cycle arrest during the first G1 phase at the mid-blastula transition. Taken together, our findings document the differential expression, subcellular localization and cell-cycle-regulatory activity of human CDH1 isoforms.
Nitration of endogenous para-hydroxyphenylacetic acid and the metabolism of nitrotyrosine
Authors: MANI Ali R. , PANNALA Ananth S. , ORIE Nelson N. , OLLOSSON Richard , HARRY David , RICE-EVANS Catherine A. , MOORE Kevin P.
Published: August 2003

Reactive nitrogen species, such as peroxynitrite, can nitrate tyrosine in proteins to form nitrotyrosine. Nitrotyrosine is metabolized to 3-nitro-4-hydroxyphenylacetic acid (NHPA), which is excreted in the urine. This has led to the notion that measurement of urinary NHPA may provide a time-integrated index of nitrotyrosine formation in vivo. However, it is not known whether NHPA is derived exclusively from metabolism of nitrotyrosine, or whether it can be formed by nitration of circulating para-hydroxyphenylacetic acid (PHPA), a metabolite of tyrosine. In the present study, we have developed a gas chromatography MS assay for NHPA and PHPA to determine whether or not NHPA can be formed directly by nitration of PHPA. Following the injection of nitrotyrosine, 0.5±0.16% of injected dose was recovered unchanged as nitrotyrosine, and 4.3±0.2% as NHPA in the urine. To determine whether or not NHPA could be formed by the nitration of PHPA, deuterium-labelled PHPA ([2H6]PHPA) was injected, and the formation of deuterated NHPA ([2H5]NHPA) was measured. Of the infused [2H6]PHPA, 78±2% was recovered in the urine unchanged, and approx. 0.23% was recovered as [2H5]NHPA. Since the plasma concentration of PHPA is markedly higher than free nitrotyrosine (approx. 400-fold), the nitration of high-circulating endogenous PHPA to form NHPA becomes very significant and accounts for the majority of NHPA excreted in urine. This is the first study to demonstrate that NHPA can be formed by nitration of PHPA in vivo, and that this is the major route for its formation.
Response of yeast to the regulated expression of proteins in the Bcl-2 family
Authors: POLČIC Peter , FORTE Michael
Published: August 2003

The mechanisms by which pro-apoptotic members of the Bcl-2 family of proteins promote the release of mitochondrial factors like cytochrome c, subsequently activating the apoptotic cascade, or by which anti-apoptotic family members block this release, are still not understood. When expressed in yeast, Bcl-2 family members act directly upon conserved mitochondrial components that correspond to their apoptotic substrates in mammalian cells. Here we describe a system in which the levels of representative pro- and anti-apoptotic members of the Bcl-2 family can be regulated independently in yeast. Using this system, we have focused on the action of the anti-apoptotic family member Bcl-xL, and have defined the quantitative relationships that underlie the antagonistic action of this protein on the lethal consequences of expression of the pro-apoptotic family member Bax. This system has also allowed us to demonstrate biochemically that Bcl-xL has two actions at the level of the mitochondrion. Bcl-xL is able to inhibit the stable integration of Bax into mitochondrial membranes, as well as hinder the action of Bax that does become stably integrated into these membranes. Taken together, our results suggest that both the functional and biochemical actions of Bcl-xL may be based on the ability of this molecule to disrupt the interaction of Bax with a resident mitochondrial target that is required for Bax action. Finally, we confirm that VDAC (voltage-dependent anion channel) is not required for the functional responses observed following the expression of either pro- or anti-apoptotic members of the Bcl-2 family.
Distinct regulation of cytosolic phospholipase A2 phosphorylation, translocation, proteolysis and activation by tumour necrosis factor-receptor subtypes
Authors: JUPP Orla J. , VANDENABEELE Peter , MacEWAN David J.
Published: August 2003

The hormonally regulated Ca2+-dependent enzyme, cytosolic phospholipase A2 (cPLA2) is activated by a range of inflammatory stimuli. Tumour necrosis factor-α (TNF) is one of the first known stimuli for cPLA2 but it is not known whether both TNF receptor subtypes are involved in activating the lipase. In the present study, we show for the first time that both type I 55 kDa TNFR (TNFR1) and type II 75 kDa TNFR (TNFR2) stimulate cPLA2 enzyme, but with distinct signalling mechanisms. TNFR1 activates mitogen-activated protein kinase (MAPK) and p38MAPK. TNFR1 then phosphorylates and activates cPLA2 in a MAPK-dependent fashion. Furthermore, TNFR1 causes the translocation and caspase-dependent proteolysis of cPLA2 as part of its activation profile. TNFR2, on the other hand, does not cause the phosphorylation of cPLA2 as it does not activate MAPK or p38MAPK, but instead activates cPLA2 by causing its translocation to plasma membrane and perinuclear subcellular regions. TNFR2 activation causes a delayed, slight increase in [Ca2+]i of <50 nM that may contribute towards the translocation and activation of cPLA2. Therefore both TNF receptor subtypes play a role in cPLA2 activation, but by means of separate signal-transduction pathways.
Identification of a novel Nrf2-regulated antioxidant response element (ARE) in the mouse NAD(P)H:quinone oxidoreductase 1 gene: reassessment of the ARE consensus sequence
Authors: NIOI Paul , McMAHON Michael , ITOH Ken , YAMAMOTO Masayuki , HAYES John D.
Published: August 2003

NQO1 [NAD(P)H:quinone oxidoreductase 1] has an integral role in cellular responses to oxidative stress. The expression of NQO1 is up-regulated in the mouse following challenge with electrophilic chemicals, in an Nrf2 (NF-E2 p45-related factor 2)-dependent fashion, but the molecular basis for this observation remains unexplained. Through characterization of the murine nqo1 5′-upstream region, we now show that Nrf2 regulates this gene directly via an ARE (antioxidant response element) that lies within a 24 bp region spanning nt −444 to −421. A comprehensive mutation study of this ARE revealed that it does not conform to the currently accepted ARE consensus sequence [(5′-TMAnnRTGAYnnnGCRwwww-3′, with essential nucleotides shown in capitals); two cytosine residues (shown in bold in the following sequence) that have been designated ‘n’ previously because they were thought to be redundant (5′-gagTcACaGTgAGtCggCAaaatt-3′) have now been found to be essential for enhancer activity; two guanines (also shown in bold) previously regarded as essential for ARE function (5′-gagTcACaGTgAGtCggCAaaatt-3′) have proven to be dispensable]. Examination of wild-type and nrf2−/− mouse embryonic fibroblasts demonstrated that Nrf2 is essential for both constitutive expression of NQO1 and its induction by sulphoraphane. Electrophoretic mobility-shift and chromatin immunoprecipitation assays revealed that Nrf2 associates, in low amounts, with the nqo1 ARE under constitutive conditions, and following sulphoraphane challenge of cells, Nrf2 is recruited to the ARE in substantially greater quantities, as a heterodimer with the small Maf (musculoaponeurotic fibrosarcoma virus) protein, MafK. Also, MafK was found to bind the nqo1 ARE in an Nrf2-independent fashion, and may contribute to transcriptional repression of the oxidoreductase gene. These findings allow a model for transcriptional control of nqo1 through the ARE to be proposed. Furthermore, our results indicate that distinct AREs have differential sequence requirements, and a universally applicable consensus sequence cannot be derived.
Specific gravity and vertical distribution of sprat eggs in the Baltic Sea
Authors: Nissling A. , Müller A. , Hinrichsen H.‐H.
Published: August 2003

During peak spawning of sprat Sprattus sprattus in the Baltic Sea in May–June egg specific gravity averaged ±s.d. 1·00858 ± 0·00116 g cm−3 but was significantly higher in the beginning and significantly lower towards the end of the spawning season. A close relationship was found between egg diameter and egg specific gravity (r2 = 0·71). This relationship, however, changed during the spawning season indicating that some other factor was involved causing the decrease in specific gravity during the spawning period. The vertical egg distribution changed during the spawning season: eggs were distributed mainly in the deep layers early in the season, occurred in and above the permanent halocline during peak spawning, and above the halocline towards the end of the spawning season. Consequently, poor oxygen conditions in the deep layers and low temperatures in layers between the halocline and the developing thermocline may affect egg development. Thus, opportunities for egg development vary over the spawning season and among spawning areas, and depending on frequency of saline water inflows into the Baltic Sea and severity of winters, between years.
Ciliated cells on the surface of embryos of Scyliorhinus canicula
Authors: Nokhbatolfoghahai M. , Downie J. R.
Published: August 2003

Monociliated surface cells were found for the first time in an elasmobranch and were common on embryos of Scyliorhinus canicula. They occurred mainly near the anterior end, until Ballard stage 30, but disappeared soon thereafter. The functions of surface ciliated cells suggested in other embryos (e.g. surface currents in lungfishes and amphibians, and determination of left–right patterns in amniotes) seem unlikely in elasmobranchs.
The role of life history in the relationship between population dynamics and environmental variability in two Mediterranean stream fishes
Authors: Magalhães M. F. , Schlosser I. J. , Collares‐Pereira M. J.
Published: August 2003

ChubSqualius torgalensisand naseChondrostoma lusitanicum, in a Mediterranean stream, showed important differences in life‐history traits and population dynamics. Both species reached mean maturity at age 2 years. Chub lived up to age 5 years, spawned in March to June, grew at a maximum rate of 0·59 mm mm−1 year−1and showed a low reproductive allocation, with fecundity and egg size increasing with body size. Nase lived up to age 4 years, spawned in January to April, grew at a maximum rate of 0·46 mm mm−1 year−1and showed a high reproductive allocation, with egg size independent of body size. Both chub and nase showed moderate fluctuations in population size during 1991–1998, but differed in factors driving density at age. Density of age 1 year juvenile chub decreased following severe summer droughts and proportionate survival prevailed thereafter. Density of age 2 year adult nase decreased following severe spring floods, but neither environmental nor parental stock effects were detected for juveniles and older fishes. The results illustrated the interplay between life history and environmental variability in driving fish population dynamics, with impacts of both summer droughts and spring floods being contingent on species‐specific patterns of spawning and reproductive investment.
Ontogeny of intestinal motility in correlation to neuronal development in zebrafish embryos and larvae
Authors: Holmberg A. , Schwerte T. , Fritsche R. , Pelster B. , Holmgren S.
Published: August 2003

For the first time, spontaneous intestinal activity was demonstrated and quantified before the onset of exogenous feeding in zebrafish Danio rerio embryos and larvae in vivo, using digital motion analysis. At 3 days post fertilization (dpf), erratic and spontaneous contraction waves were observed in the gut. Later (4–7 dpf), more distinct contraction patterns were distinguished, and anterograde and retrograde contraction waves projecting anally and orally along the intestine, respectively, as well as local rectal contraction waves could be identified and quantified. The frequency of both anterograde intestinal and local rectal contractions increased significantly during the first days of development. There was a tendency towards shorter anterograde contraction waves in the first dpf stage investigated, but the velocity of the waves did not differ significantly between the different dpf stages. The presence of developing neurones in the gut of zebrafish was established using immunohistochemistry, staining for a suite of marker proteins (Hu C/D, HNK‐1 and acetylated tubulin). Structural neurones were present in the developing gut from the first dpf stage investigated (2 dpf). In conclusion, during the period (3–7 dpf) when erratic contraction waves turn into a more organized pattern of motility there is also a pronounced development of the innervation, suggesting a correlation in time of the development of gut motility and its neuronal control.
The role of olfaction in the behavioural and physiological responses to conspecific skin extract in Brycon cephalus
Authors: Ide L. M. , Urbinati E. C. , Hoffmann A.
Published: August 2003

A behavioural alarm reaction was shown by 78% of the non‐operated juvenile matrinxãBrycon cephalus exposed to a conspecific skin extract, whereas the other 22% did not change their behaviour. The main reaction (72% of those reacting) consisted of a brief initial phase (2 min) of dashing or very rapid swimming followed by a long‐lasting period of immobility (up to 30 min). The second most frequent behaviour (22% of the reacting fish) was immobility, with the animals becoming motionless immediately after exposure to the conspecific skin extract, for periods ranging from 5 to 30 min. Only one animal slowed its swimming activity. The responses, evaluated by the number of times the animal crossed the grid in the rear of the aquarium, were significantly lower when compared to the baseline swimming activity. Histological examination of matrinxã epidermis revealed the existence of club cells. Complete sectioning of the olfactory tracts as well as bilateral sections of the olfactory sub‐tracts (medial or lateral), stopped the alarm reaction, confirming the importance of olfaction in the ability to recognize the chemical stimulus. Despite the behavioural responses, no variation was detected in blood glucose or cortisol levels, a result that is discussed in terms of the intensity of the disturbance caused by the alarm substance.
Correlates of reproductive success in a wild population of Hippocampus whitei
Authors: Vincent A. C. J. , Giles B. G.
Published: August 2003

An analysis of 27 broods born in situ to wild male seahorses Hippocampus whitei, with known partners, showed that female size was the key determinant of the number of young released by the male. There was also an apparent decline in both the number of young per brood, and the size of those young, over the breeding season. The size of the brood and of the young may be more proximate indicators of reproductive success in seahorses than in other fishes, because they can be measured at the time of release, here 20–22 days after fertilization, after which survival is presumed to be relatively higher than in other species. The best model, however, explained <40% of the brood size.
Reproductive behaviour of sneaker males of the peacock blenny
Authors: Gonçalves D. , Fagundes T. , Oliveira R.
Published: August 2003

In the peacock blenny Salaria pavo small sneaker males tried to steal ‘fertilizations’ at most in two different nests of large nesting males throughout the breeding season and spent most of their time associated with a particular nest. Sneakers did not associate with ripe females. As nesting males were the limiting reproductive resource in this population due to the scarcity of appropriate nest sites, sneakers were likely to maximize their chances of achieving parasitic fertilization of eggs by associating with successful nests.
Population structure, growth and reproduction of roughhead grenadier on the Flemish Cap and Flemish Pass
Authors: Murua H.
Published: August 2003

Roughhead grenadier Macrourus berglax were collected during the Flemish Cap bottom survey (1991–2001, NAFO division 3M, depth of 200–720 m) and on commercial vessels (1998–2000, NAFO divisions 3L, M and N, depth of 700–1700 m). The abundance of roughhead grenadier, as well as their average size, increased with depth. Age and length composition of the catches showed clear differences between the sexes. The proportion of males in the catch declined in the larger length classes and there were no males in the largest length classes (25 cm). There were differences in the growth trajectories of the two sexes; both sexes grew similarly up to 9 years, but the male growth was slower thereafter. The pre‐anal fin length at first maturity (LPA50) for roughhead grenadier females was 28·5 cm, whilst the age at 50% maturity was 15–16 years. Individual total fecundity varied between 8522 and 61 844 oocytes. Macrourus berglax had a prolonged life cycle and multi‐aged population structure, with differences in growth and mortality between males and females, slow maturation and low fecundity.
Behavioural and morphological differences between lake and river populations of Salaria fluviatilis
Authors: Neat F. C. , Lengkeek W. , Westerbeek E. P. , Laarhoven B. , Videler J. J.
Published: August 2003

Three populations (one from a river and two from lakes) of Salaria fluviatilis, the only exclusively freshwater representative of the Blenniidae, showed significant differences in reproductive behaviour and morphology. Breeding males and females were significantly larger at maturity in the river than the two lake populations. The two lake populations, however, showed the greatest degree of morphological difference, the river population being intermediate. The mating system of each population could be described as resource‐based and promiscuous with parasitic ‘sneaker’ males that released sperm in the nests of other males. During spawning, males from the river population released sperm significantly more often than the lake populations. This was paralleled by a greater investment in sperm as measured by relative testis mass in the river population. This was interpreted as the need to counteract the loss of sperm during fertilization as a result of the strong flow in the river. Thus some of the patterns of trait variance fitted predictions of adaptations. Other traits, however, varied randomly across populations suggesting change through genetic drift.
First record of Grammicolepis brachiusculus in Portuguese waters
Authors: Vasconcelos P. , Santos M. N. , Gaspar M. B.
Published: August 2003

Morphometric and meristic characteristics of a specimen of Grammicolepis brachiusculus Poey caught off the Algarve coast, southern Portugal, are reported. This is the first record of this benthopelagic species in Portuguese waters (including Madeira and Azores Archipelagos) and its fifth finding in the north‐eastern Atlantic.
Direct yolk sac volume manipulation of zebrafish embryos and the relationship between offspring size and yolk sac volume
Authors: Jardine D. , Litvak M. K.
Published: August 2003

Through direct manipulation of yolk sac volume (Vy), in the zebrafish Danio rerio, Vy and offspring size was positively correlated and the relationship was independent of geographical location, parental size or age and, most importantly, parental genetic factors. Larval survivorship, under a non‐feeding regime and up until hatch, was not significantly affected by the manipulation. Decreased Vy significantly decreased maximum standard length (LS), maximum body surface area (AB), time to yolk sac absorption, LS and AB at yolk sac absorption, and the LS and AB at starvation. The methodology of Vy adjustment will be useful for the studies of the interaction between early life‐history traits and offspring size, egg quality variables and early vertebrate development.
Effects of growth hormone transgenesis on metabolic rate, exercise performance and hypoxia tolerance in tilapia hybrids
Authors: McKenzie D. J. , Martínez R. , Morales A. , Acosta J. , Morales R. , Taylor E. W. , Steffensen J. F. , Estrada M. P.
Published: August 2003

Swimming respirometry was employed to compare inactive metabolic rate (Rr), maximum metabolic rate (Rmax), resultant aerobic scope and maximum sustainable (critical) swimming speed (Ucrit), in growth hormone transgenic (GHT) and wild‐type (W) tilapia Oreochromis sp. hybrids. Although the Rr of GHT tilapia was significantly (58%) higher than their W conspecifics, there were no significant differences in their net aerobic scope because GHT tilapia exhibited a compensatory increase in Rmax that was equal to their net increase in Rr. As a consequence, the two groups had the same Ucrit. The GHT and W tilapia also exhibited the same capacity to regulate oxygen uptake during progressive hypoxia, despite the fact that the GHT fish were defending a higher demand for O2. The results indicate that ectopic expression of GH raises metabolic rate in tilapia, but the fish compensate for this metabolic load and preserve such physiological determinants of fitness as aerobic scope, swimming performance and tolerance of hypoxia.
Dietary segregation among large catfishes of the Apure and Arauca Rivers, Venezuela
Authors: Barbarino Duque A. , Winemiller K. O.
Published: August 2003

Relative abundance, population size structure and diet composition and similarity were examined over 5 years for the nine most abundant catfish (Siluriformes) species captured in the Apure‐Arauca River fishery centred around San Fernando de Apure, Venezuela, the largest freshwater fishery in the Orinoco River Basin. Based on size classes obtained by the fishery, all nine catfishes were almost entirely piscivorous. Four species that are entirely restricted to main channels of the largest rivers (Brachyplatystoma flavicans, Brachyplatystoma jurunse, Brachyplatystoma vaillanti and Goslinia platynema) fed predominantly on weakly electric knifefishes (Gymnotiformes) and had high pair‐wise dietary overlap. The other five species (Ageniosus brevifilis, Phractocephalus hemioliopterus, Pinirampus pirinampu, Pseudoplatystomafasciatum and Pseudoplatystoma tigrinum) occurred in a range of channel and off‐channel habitats and were observed to feed on a variety of characiform, siluriform and gymnotiform prey. Diet overlap also was high among these habitat‐unrestricted species, but overlap between the channel‐restricted and unrestricted species was low. Within each of the two groups, species were divided into approximately equally sized subgroups based on differences in body size distributions. The two most morphologically similar species, P. fasciatum and P. tigrinum, further subdivided prey based on the vertical stratum occupied by prey species (benthic v. midwater). The two most morphologically dissimilar, channel‐restricted species, B. juruense and G. platynema, also diverged in frequency of consumption of benthic and midwater prey.
Variation in the diet of the Patagonian toothfish with size, depth and season around the Falkland Islands
Authors: Arkhipkin A. , Brickle P. , Laptikhovsky V.
Published: August 2003

The ontogenetic and seasonal variations in the feeding spectrum were studied in 756 specimens of the Patagonian toothfish Dissostichus eleginoides (16–159 cm total length, LT) collected on the shelf, continental slope and bathyal waters (67–1960 m, depth range) around the Falkland Islands between April 1999 and August 2002. On the shelf, small toothfish (<40 cm LT) were active predators taking mostly one relatively large prey item at a time (mainly near‐bottom Patagonotothen ramsayi and Loligo gahi). Medium‐size toothfish (40–60 cm LT) fed on the same prey, but the number of prey items increased to 1–2 items per fish. Large toothfish (>60 cm LT) switched their diet to other large pelagic fishes occurring near the bottom (Macruronus magellanicus and Micromesistius australis australis), again taking mostly one prey item at a time. The diet of medium‐size D. eleginoides on the shelf varied seasonally depending on the abundance and migrations of the major prey species. Patagonotothen ramsayi was abundant in the diet throughout the year, whereas L. gahi appeared only from February to October during its offshore seasonal migrations to the depth range of D. eleginoides. During November to January, L. gahi migrated inshore to spawn and disappeared from the toothfish diet, being substituted by M. australis australis which dispersed on the shelf after spawning. After its ontogenetic descent to the lower part of the continental slope (500–1000 m depths), toothfish took less active (than on the shelf) fishes such as Antimora rostrata whilst also feeding on active near‐bottom macrourids and skates. In their deepest habitat (>1000 m depths), toothfish became a typical opportunistic predator, feeding mainly on relatively small and inactive fishes, squids and prawn‐like crustaceans Acanthephyra pelagica and Thymops birsteini. Decrease in hunting activity with depth could be related to a specific adaptation to keep neutral buoyancy by increase of lipid content in white muscles of D. eleginoides with size.
Advanced sexual maturation before marine migration of Anguilla bicolor bicolor and Anguilla marmorata at Réunion Island
Authors: Robinet T. , Sbaihi M. , Guyet S. , Mounaix B. , Dufour S. , Feunteun E.
Published: August 2003

Maturing sub‐adults of two species of anguillid eels (a female Anguilla bicolor bicolor and a male Anguilla marmorata) were collected for the first time at Réunion Island, western Indian Ocean. Both were silver eels, i.e. maturing eels at the onset of their spawning migration, and characterized by advanced sexual maturation that has been only observed in Anguilla dieffenbachii from New Zealand.
Satellite species in lampreys: a worldwide trend for ecological speciation in sympatry?
Authors: Salewski V.
Published: August 2003

Amongst several theories of speciation, sympatric speciation has been the most controversial but it is now widely accepted that populations can become reproductively isolated without being separated geographically. One problem with the acceptance of the theory of sympatric speciation, however, has been the lack of supporting empirical data and it is still believed that geographical isolation is responsible for the majority of speciation events. Here the example of species pairs in lampreys suggests that sympatric speciation in a whole taxonomic group could occur throughout its worldwide range.

Lampreys occur in two ecologically distinct forms: parasitic mostly anadromous species that forage on tissue and body fluids of host fishes, and non‐parasitic forms that, apart from a short adult life when they cease feeding, spend their entire life as filter feeders in the substratum of stream beds. Both forms occur in sympatric species pairs throughout the range of lampreys that occur in Eurasia, North America and Australia and it is widely acknowledged that non‐parasitic forms derive from parasitic forms. The larvae of both forms can be distinguished by their potential fecundity and therefore, it is argued that the mode of life is not a consequence of different ecological conditions. Furthermore, as lampreys prefer to choose mates of similar sizes and fertilization success decreases with increasing difference in body size, there is a strong disruptive selection between the two forms and they are therefore reproductively isolated. Besides theoretical aspects, the similarity of the species pairs, together with their occurrence in sympatry, the occurrence of forms with intermediate characteristics, and examples where speciation might be in progress, hints at the possibility that speciation also occurred in sympatry. The difference between lampreys and other examples of sympatric speciation is that there seems to be a trend towards sympatric speciation events throughout the worldwide range of lampreys which is neither restricted to relatively small localities nor caused by human disturbance. Species pairs in lampreys therefore offer a unique possibility of studying the process of sympatric speciation on a large scale.
Diel changeover in sandbank fish assemblages in a neotropical floodplain river
Authors: Arrington D. A. , Winemiller K. O.
Published: August 2003

Fishes were collected over 7 months (February to June and November to December 1999) from seven sandbanks located on the main channel of the Cinaruco River, Venezuela. Significant shifts in assemblage structure and species richness were documented between diurnal and nocturnal samples. Seine samples standardized for effort yielded 41 604 individual fishes representing seven orders, 25 families, 80 genera and 134 species. Nocturnal samples yielded 68% of the total individuals, and 54% of species were collected exclusively at night. Nocturnal samples were significantly more species rich than their paired diurnal samples, even after rarefaction. Correspondence analysis revealed consistent differences in assemblage structure between diurnal and nocturnal samples probably due to species‐specific habitat use and activity patterns. In spite of the magnitude of seasonal variation in hydrology and habitat availability in the Cinaruco River, species richness and abundance on sandbanks varied relatively little. The study of biological diversity and understanding of patterns of habitat use in a neotropical river were enhanced by nocturnal sampling.
Diet and growth of the endangered Zingel asper in the Durance River
Authors: Cavalli L. , Pech N. , Chappaz R.
Published: August 2003

Annual monitoring of the apron Zingel asper in the Durance River, a tributary of the Rhône in which the fish is endemic, indicated its narrow diet range. Three types of prey made up the basic diet: Diptera (Simulidae and Chironomidae), mainly in winter, and Ephemeroptera (Baetidae) and Trichoptera (Hydropsychidae), during the rest of the year. Although some potential prey (Coleoptera and Gammaridae) were present in the substratum, they were not found in the stomach contents of the apron. In spring specific food items (Heptageneidae) appeared to be actively searched for as indicated by stomach contents. This period coincided with the renewal of growth. More than 80% of the annual occurred before the beginning of autumn.
Cryopreservation of sperm in Brazilian migratory fish conservation
Authors: Carolsfeld J. , Godinho H. P. , Zaniboni Filho E. , Harvey B. J.
Published: August 2003

Simple, effective protocols for cryopreserving milt of five Brazilian migratory characids (Brycon orbignyanus, Prochilodus lineatus, Piaractus mesopotamicus, Salminus maxillosus and Leporinus elongatus) and one Brazilian migratory catfish (Pseudoplatystoma corruscans) are described. Milt was frozen and stored in dry shippers immediately after collection, making the procedure practical for use in the field. A diluent of 5% glucose, 10% dimethyl sulphoxide and 10% egg yolk was effective for all of the characid species, and a diluent of 10% methanol and 15% powdered milk was effective for P. corruscans. Milt was thawed in an ambient temperature water bath (28–30° C). Activation of thawed milt was effective with either saline (0·9 or 0·45% NaCl) or bicarbonate (1% NaHCO3). Fertilization rates with frozen milt varied between 49 and 300% of the control. Application of the technology for increasing genetic diversity in hatchery programmes for enhancement, mitigation or conservation breeding is discussed, as is its application in aquaculture. Inappropriate use of the technology can threaten wild biodiversity and appropriate legislation and education may be required for its responsible use.
Morphology and reproduction of the cavefish Trichomycterus chaberti and the related epigean Trichomycterus cf. barbouri
Authors: Pouilly M. , Miranda G.
Published: August 2003

Hypogean and epigean populations of Trichomycterus catfishes inhabit streams from different environments (cave, headwater, canyon and valley) in the Torotoro National Park in the Andes, Bolivia. A significant reduction in the diameter of the eyes and in the surface area of the mesencephalon was observed in subterranean populations, along with an increase in the surface area of the telencephalon. Contrary to expectations, the barbel did not appear to be longer in hypogean populations. The observed pattern of modification of the other variables (pigmentation, eye asymmetry, surface area of the cerebellum and rhombencephalon, fecundity and egg diameter) corresponded to a gradient of values from valley to canyon, headwater and subterranean populations. This result argues not for a simple distinction between epigean and hypogean populations but for an adaptation to an environmental gradient of constraints in which caves correspond to an extreme situation.
Effects of administration of somatostatin‐14 and immunoneutralization of somatostatin on endocrine and growth responses in rainbow trout
Authors: Peterson B. C. , Simpson P. R. , Cain K. D. , Hardy R. H. , Schelling G. T. , Ott T. L.
Published: August 2003

Injection of somatostatin‐14 (SS‐14) at 5 ng g−1 body mass (BM) into rainbow trout Oncorhynchus mykiss decreased (P < 0·05, cubic, r2 = 0·54) levels of growth hormone (GH) (1·5 ± 0·9 ng ml−1v. 6·6 ± 0·6 ng ml−1) over time when compared to controls. Somatostatin‐14 at 50 ng g−1 BM also decreased (P = 0·064, quadratic; r2 = 0·30) levels of GH (3·6 ± 2·1 ng ml−1v. 6·6 ± 0·6 ng ml−1) over time compared to controls. In a second study, passive immunization against SS‐14 (1 : 25 dose) increased (P = 0·10, cubic, r2 = 0·12) levels of GH (11·0 ± 4·8 ng ml−1v. 5·2 ± 1·4 ng ml−1) over time. Passively immunizing against SS‐14 (1 : 50 dose) increased (P < 0·05, cubic, r2 = 0·10) levels of GH (8·2 ± 2·3 ng ml−1v. 5·2 ± 1·4 ng ml−1) over time compared to controls. Overall, in the active immunization study there was no difference (P > 0·10) in specific growth rate (G) or feed conversion ratio (FCR) between the three treatment groups during the 9 weeks of the study. Only four of the fish immunized against SS‐14, however, developed antibody titres against SS. Compared to controls, these fish exhibited a G of 0·89 ± 0·09 v. 0·56 ± 0·09% per 3 weeks and FCR of 0·80 ± 0·04 v. 1·20 ± 0·05 g g−1. In SS‐14 immunized fish, levels of GH decreased (P < 0·05) by day 63 while levels of insulin like growth factor‐I (IGF‐I) increased (P < 0·05) by day 42 and 63. These results indicate the hypothalamic hormone SS‐14 regulates GH secretion similarly in rainbow trout as it does in mammals. Active immunization against SS‐14 could improve growth performance in rainbow trout but enhanced G and FCR is dependent upon generation of antibody titres.
Molecular identification and characterization of rat Abcc1 cDNA: existence of two splicing variants and species difference in drug‐resistance profile
Authors: Takayanagi Shin‐ichiro , Ishikawa Toshihisa
Published: August 2003

The human ABCC1 gene, a member of the ATP‐binding cassette transporter super‐family, plays a critical role in conferring cancer cell resistance to chemotherapeutic drugs. In the present study, we have cloned the full‐length cDNA of rat Abcc1 and evaluated its significance in drug resistance. Analysis using the currently available genome database revealed that the rat Abcc1 gene is located on rat chromosome 13 and consists of at least 30 exons. The rat Abcc1 cDNA cloned from the spleen was 4981‐bp long, within which two additional splicing variants were discovered. The rat Abcc1 gene is expressed in a wide variety of organs, with the highest expression being observed in the spleen. Human embryonic kidney 293 cells were transfected with the rat Abcc1/pcDNA3.1 vector to stably express rat Abcc1. Overexpression of rat Abcc1 elicited high resistance to etoposide. In contrast to the hitherto known drug‐resistance profile of human ABCC1, rat Abcc1 did not significantly confer cellular resistance to anthracyclins or Vinca alkaloids. Our results strongly suggest that there is a significant species difference between human ABCC1 and rat Abcc1 in their contribution to the drug‐resistance profile.
Andrographolide, a potential cancer therapeutic agent isolated from Andrographis paniculata
Authors: Rajagopal Sriram , Kumar R. Ajaya , Deevi Dhanvanthri S. , Satyanarayana Chitkala , Rajagopalan R.
Published: August 2003

Andrographis paniculata plant extract is known to possess a variety of pharmacological activities. Andrographolide, the major constituent of the extract is implicated towards its pharmacological activity. We studied the cellular processes and targets modulated by andrographolide treatment in human cancer and immune cells. Andrographolide treatment inhibited the in vitro proliferation of different tumor cell lines, representing various types of cancers. The compound exerts direct anticancer activity on cancer cells by cell‐cycle arrest at G0/G1 phase through induction of cell‐cycle inhibitory protein p27 and decreased expression of cyclin‐dependent kinase 4 (CDK4). Immunostimulatory activity of andrographolide is evidenced by increased proliferation of lymphocytes and production of interleukin‐2. Andrographolide also enhanced the tumor necrosis factor‐α production and CD marker expression, resulting in increased cytotoxic activity of lymphocytes against cancer cells, which may contribute for its indirect anticancer activity. The in vivo anticancer activity of the compound is further substantiated against B16F0 melanoma syngenic and HT‐29 xenograft models. These results suggest that andrographolide is an interesting pharmacophore with anticancer and immunomodulatory activities and hence has the potential for being developed as a cancer therapeutic agent.
Predictors of beer advertising awareness among eighth graders
Authors: Collins Rebecca L. , Schell Terry , Ellickson Phyllis L. , McCaffrey Daniel
Published: August 2003

Aims  To identify correlates of beer advertising awareness among adolescents at an age when most initiate use of alcohol.

Design  We conducted a cross‐sectional analysis of an in‐school survey about alcohol advertising. Structural equation modeling was used to test for independent predictors of a latent beer advertising awareness construct, separately among boys and girls.

Setting  Twenty middle schools in South Dakota, USA participated during their spring semester.

Participants  A total of 1530 eighth graders.

Measurements  A latent advertisement awareness variable was derived based on recognition of six masked beer advertisements, knowledge of beer brands and knowledge of beer slogans. Tested predictors included measures of exposure to alcohol advertising in various venues, social norms regarding drinking, drinking beliefs and behavior and gender.

Findings  Adolescents with greater exposure to advertisements in magazines, at sporting and music events and on television were more advertisement aware than those with less exposure, as were teens who watch more TV, pay attention to beer advertisements and know adults who drink. Beer advertisement awareness was dramatically higher among boys, and was associated with drinking only among boys.

Conclusions  Each of a variety of advertising venues appears to influence independently the extent to which beer advertising is incorporated into an adolescent's cognitive world. Boys are more likely to be aware of and remember beer marketing, and may be more likely to drink as a result of this awareness than girls.
Perfusate composition influences nitric oxide homeostasis in rat juxtamedullary afferent arterioles
Authors: Pittner J. , Wolgast M. , Persson A. E. G.
Published: August 2003

Aim: Vascular diameters in isolated juxtamedullary nephron preparations perfused with cell‐free solutions differ from those perfused with blood. In the present study, the effects of the albumin content of the perfusate on the afferent arteriolar diameter and endothelial nitric oxide were investigated in the isolated juxtamedullary nephron preparation perfused with Krebs–Ringer–bicarbonate buffer containing albumin in different concentrations.

Methods: The endothelium was loaded with DAF‐FM DA, a nitric oxide‐sensitive fluoroprobe. Perfusion was maintained either with 4% (control group), 10 or 20% albumin in the perfusate or with l‐NAME (10−4 m) added to the perfusate. Fluorescent images were obtained and stored for evaluation of DAF‐FM fluorescence and vascular diameters (in mid‐afferent arterioles) immediately before perfusate change and every 15 min thereafter, for a 2‐h period.

Results: Increasing the albumin concentration resulted in a decrease in fluorescence. The most rapid decline of fluorescence was obtained following l‐NAME administration (relative fluorescence after 2 h: 4% albumin 92.4 ± 5.3%; 10% albumin 79.5 ± 4.2%; 20% albumin 66.2 ± 2.6%; l‐NAME 55.4 ± 3.0%; mean ± SD, n = 5). A dose‐dependent constriction of the afferent arterioles was observed (normalized diameter: 4% albumin 99.8 ± 3.0%; 10% albumin 80.3 ± 3.3%; 20% albumin 74.3 ± 3.2%; l‐NAME 70.6 ± 3.5%).

Conclusion: We propose that albumin interferes with arteriolar nitric oxide homeostasis, probably by scavenging nitric oxide intra‐luminally. In this respect, albumin acts similarly to red blood cells in the circulation. The magnitude of the scavenging determines the effectiveness of autoregulation in the perfused preglomerular vessels. The scavenging properties of the perfusing fluid are important in setting operating levels of endothelial nitric oxide.
Hemichrome formation observed in human haemoglobin A under various buffer conditions
Authors: Sugawara Y. , Kadono E. , Suzuki A. , Yukuta Y. , Shibasaki Y. , Nishimura N. , Kameyama Y. , Hirota M. , Ishida C. , Higuchi N. , Haramoto K. , Sakai Y. , Soda H.
Published: August 2003

Aim: To observe hemichrome formation in human haemoglobin A under various buffer conditions.

Method: Hemichrome formation of human oxyhaemoglobin A (HbO2) was studied spectrophotometrically in 0.1 m buffer at various temperatures and pH values.

Results: Following autoxidation in ferrous HbO2, it was evident that formation of hemichrome, which tends to precipitate, occurred at various stages during the course of the autoxidation reaction namely at initial, intermediate or final stages, depending on temperature and pH of the solution. By varying temperature of the solution from 35 to 55 °C and pH from 4.5 to 10.5, it is shown here that HbO2 exhibits high susceptibility for hemichrome formation and its occurrence is a function of pH, temperature and progress of autoxidation of HbO2. Unlike HbO2 and its separated haemoglobin chains, monomeric bovine heart myoglobin (MbO2) did not easily form hemichrome.

Conclusion: These findings provide a clue on the crucial role of haemoglobin molecule for senescent cell recognition or homeostasis in the blood circulation.
Validity of the microdialysis technique for experimental in vivo studies of myocardial energy metabolism
Authors: Kavianipour M. , Wikström G. , Ronquist G. , Waldenström A.
Published: August 2003

Objectives: The validity of the microdialysis technique for experimental in vivo studies of myocardial energy metabolism is not known. To address this question interstitial levels of energy‐related metabolites (lactate, adenosine, inosine and hypoxanthine) obtained by the microdialysis technique were compared with corresponding metabolites from myocardial biopsies at given intervals in a porcine heart model using different protocols of ischaemia and reperfusion.

Methods: In an open chest porcine heart model, interstitial levels of energy‐related metabolites were monitored using the microdialysis technique. All animals (n = 23) were subjected to 120‐min pretreatment followed by 40 min of regional ischaemia and 120 min of reperfusion. Tissue biopsies were obtained in the beginning, middle and at the end of the 40‐min ischaemic period and at the end of the reperfusion period. Pretreatment consisted of either rest (group 1, n = 7), or rest for 90 min and one ischaemia/reperfusion (10 + 20 min) cycle (group 2, n = 9), or four ischaemia/reperfusion cycles (10 + 20 min each) (group 3, n = 7).

Results: Interstitial levels of energy‐related metabolites monitored by the microdialysis technique correlated with tissue biopsy levels of lactate (r = 0.90, P < 0.001), adenosine (r = 0.89, P < 0.001), inosine (r = 0.88, P < 0.001) and hypoxanthine (r = 0.91, P < 0.001), respectively, which were obtained by tissue biopsies at given time intervals. These significant correlations were valid regardless of the functional state of the myocardium.

Conclusion: We observed significant correlations between microdialysis probe levels and tissue biopsy levels of energy‐related metabolites in both ischaemic and non‐ischaemic tissue. These data assess the validity of the microdialysis technique (in the current setting) for studying dynamic changes of myocardial energy metabolism.
Non‐linear dependence of interstitial fluid pressure on joint cavity pressure and implications for interstitial resistance in rabbit knee
Authors: Scott D. , Levick J. R. , Miserocchi G.
Published: August 2003

Aims:  Synovium retains lubricating fluid in the joint cavity. Synovial outflow resistance estimated as dPj/d (Pj, joint fluid pressure and trans‐synovial flow) is greater, however, than expected from interstitial glycosaminoglycan concentration. This study investigates whether subsynovial fluid pressure increases with intra‐articular pressure, as this would reduce the estimated resistance estimate.

Methods:  Interstitial fluid pressure (Pif) was measured as a function of distance from the joint cavity in knees of anaesthetized rabbits, using servo‐null pressure‐measuring micropipettes and using an external ‘window’. Joint fluid pressure Pj was either endogenous (−2.4 ± 0.4 cmH2O, mean ± SEM) or held at ∼4, 8 or 15.0 cmH2O by a continuous intra‐articular saline infusion that matched the trans‐synovial interstitial drainage rate.

Results:  At endogenous Pj the peri‐articular Pif was subatmospheric (−1.9 ± 0.3 cmH2O, n = 19). At raised Pj the Pif values became positive. Gradient dPif /dx was ∼20 times steeper across synovium than subsynovium. Pif close to the synovium–subsynovium border () increased as a non‐linear function of Pj to 1.4 ± 0.2 cmH2O (n = 23) at Pj = 4.3 ± 0.1 cmH2O : 2.3 ± 0.2 cmH2O (n = 17) at Pj = 7.6 ± 0.2 cmH2O: and 3.0 ± 0.4 cmH2O (n = 26) at Pj = 15 ± 0.2 cmH2O (P = 0.03, anova).

Conclusions:  Synovial resistivity is ∼20× subsynovial resistivity. The increase in with Pj means that true synovial resistance d()/d is overestimated 1.5× by dPj/d. This narrows but does not eliminate the gap between analysed glycosaminoglycan concentration, 4 mg ml−1, and the net interstitial biopolymer concentration of 11.5 mg ml−1 needed to generate the resistance.