bluuebunny/crossref_metadata_2025 huggingface dataset:
Blocking
S
-adenosylmethionine synthesis in yeast allows selenomethionine incorporation and multiwavelength anomalous dispersion phasing
Authors: Malkowski Michael G. , Quartley Erin , Friedman Alan E. , Babulski Julie , Kon Yoshiko , Wolfley Jennifer , Said Meriem , Luft Joseph R. , Phizicky Eric M. , DeTitta George T. , Grayhack Elizabeth J.
Published: April 2007

Saccharomyces cerevisiae
is an ideal host from which to obtain high levels of posttranslationally modified eukaryotic proteins for x-ray crystallography. However, extensive replacement of methionine by selenomethionine for anomalous dispersion phasing has proven intractable in yeast. We report a general method to incorporate selenomethionine into proteins expressed in yeast based on manipulation of the appropriate metabolic pathways.
sam1
−
sam2
−
mutants, in which the conversion of methionine to
S
-adenosylmethionine is blocked, exhibit reduced selenomethionine toxicity compared with wild-type yeast, increased production of protein during growth in selenomethionine, and efficient replacement of methionine by selenomethionine, based on quantitative mass spectrometry and x-ray crystallography. The structure of yeast tryptophanyl-tRNA synthetase was solved to 1.8 Å by using multiwavelength anomalous dispersion phasing with protein that was expressed and purified from the
sam1
−
sam2
−
strain grown in selenomethionine. Six of eight selenium residues were located in the structure.
Absence of dopamine D2 receptors unmasks an inhibitory control over the brain circuitries activated by cocaine
Authors: Welter Marc , Vallone Daniela , Samad Tarek A. , Meziane Hamid , Usiello Alessandro , Borrelli Emiliana
Published: April 2007

Cocaine is a psychostimulant and a drug widely abused by humans. Cocaine elicits its effects primarily by blocking the activity of the dopamine (DA) transporter, leading to elevated levels of extracellular DA in areas receiving dopaminergic innervation, with the consequent activation of DA receptors. Cocaine, however, also elevates other neurotransmitter levels, leading to a general activation of interconnected brain circuitries. Studies aimed at unraveling the molecular mechanisms underlying the effects of cocaine have shown a leading role of DA D1 receptors in the cascade of cellular events elicited by this drug. In this study, we have analyzed the acute response to cocaine in animals deleted for the expression of DA D2 receptors (D2R), an inhibitor of DA signaling. Importantly, we show that although D1 receptor-mediated functions are preserved and even enhanced in D2R−/− mutants, the behavioral response to acute cocaine administration is severely altered. In addition, c-fos response to acute cocaine administration, in contrast to wild-type mice, is absent in D2R−/− mutants. Our findings show that the absence of D2R, very likely through a presynaptic mechanism, uncovers an inhibitory signaling pathway normally masked by the activity of this receptor on brain circuitries engaged by abused drugs.
Microfossil evidence for pre-Columbian maize dispersals in the neotropics from San Andrés, Tabasco, Mexico
Authors: Pohl Mary E. D. , Piperno Dolores R. , Pope Kevin O. , Jones John G.
Published: April 2007

The history of maize (
Zea mays
L.) is one of the most debated topics in New World archaeology. Molecular and genetic studies indicate that maize domestication took place in tropical southwest Mexico. Although archaeological evidence for the evolution of maize from its wild ancestor teosinte has yet to be found in that poorly studied region, other research combining paleoecology and archaeology is documenting the nature and timing of maize domestication and dispersals. Here we report a phytolith analysis of sediments from San Andrés, Tabasco, that confirms the spread of maize cultivation to the tropical Mexican Gulf Coast >7,000 years ago (≈7,300 calendar years before present). We review the different methods used in sampling, identifying, and dating fossil maize remains and compare their strengths and weaknesses. Finally, we examine how San Andrés amplifies the present evidence for widespread maize dispersals into Central and South America. Multiple data sets from many sites indicate that maize was brought under cultivation and domesticated and had spread rapidly out of its domestication cradle in tropical southwest Mexico by the eighth millennium before the present.
Replication fitness determines high virulence of influenza A virus in mice carrying functional
Mx1
resistance gene
Authors: Grimm Daniel , Staeheli Peter , Hufbauer Martin , Koerner Iris , Martínez-Sobrido Luis , Solórzano Alicia , García-Sastre Adolfo , Haller Otto , Kochs Georg
Published: April 2007

The IFN-induced resistance factor Mx1 is a critical component of innate immunity against influenza A viruses (FLUAV) in mice. Animals carrying a wild-type
Mx1
gene (
Mx1
+/+
) differ from regular laboratory mice (
Mx1
−/−
) in that they are highly resistant to infection with standard FLUAV strains. We identified an extraordinary variant of the FLUAV strain, A/PR/8/34 (H1N1) (designated hvPR8), which is unusually virulent in
Mx1
+/+
mice. hvPR8 was well controlled in
Mx1
+/+
but not
Mx1
−/−
mice provided that the animals were treated with IFN before infection, indicating that hvPR8 exhibits normal sensitivity to growth restriction by Mx1. hvPR8 multiplied much faster than standard PR8 early in infection because of highly efficient viral gene expression in infected cells. Studies with reassortant viruses containing defined genome segments of both hvPR8 and standard PR8 demonstrated that the HA, neuraminidase, and polymerase genes of hvPR8 all contributed to virulence, indicating that efficient host cell entry and early gene expression renders hvPR8 highly pathogenic. These results reveal a surprisingly simple concept of how influenza viruses may gain virulence and illustrate that high speed of virus growth can outcompete the antiviral response of the infected host.
A fossil brain from the Cretaceous of European Russia and avian sensory evolution
Authors: Kurochkin Evgeny N , Dyke Gareth J , Saveliev Sergei V , Pervushov Evgeny M , Popov Evgeny V
Published: April 2007

Fossils preserving traces of soft anatomy are rare in the fossil record; even rarer is evidence bearing on the size and shape of sense organs that provide us with insights into mode of life. Here, we describe unique fossil preservation of an avian brain from the Volgograd region of European Russia. The brain of this Melovatka bird is similar in shape and morphology to those of known fossil ornithurines (the lineage that includes living birds), such as the marine diving birds
Hesperornis
and
Enaliornis
, but documents a new stage in avian sensory evolution: acute nocturnal vision coupled with well-developed hearing and smell, developed by the Late Cretaceous (
ca
90 Myr ago). This fossil also provides insights into previous ‘bird-like’ brain reconstructions for the most basal avian
Archaeopteryx
—reduction of olfactory lobes (sense of smell) and enlargement of the hindbrain (cerebellum) occurred subsequent to
Archaeopteryx
in avian evolution, closer to the ornithurine lineage that comprises living birds. The Melovatka bird also suggests that brain enlargement in early avians was not correlated with the evolution of powered flight.
Unidirectional prey–predator facilitation: apparent prey enhance predators' foraging success on cryptic prey
Authors: Zhang Yixin , Richardson John S
Published: April 2007

Food availability can strongly affect predator–prey dynamics. When change in habitat condition reduces the availability of one prey type, predators often search for other prey, perhaps in a different habitat. Interactions between behavioural and morphological traits of different prey may influence foraging success of visual predators through trait-mediated indirect interactions (TMIIs), such as prey activity and body coloration. We tested the hypothesis that foraging success of stream-dwelling cutthroat trout (Onchorhyncus clarki) on cryptically coloured, less-active benthic prey (larval mayfly;Paraleptophebiasp.) can be enhanced by the presence of distinctly coloured, active prey (larval stonefly shredder;Despaxia augusta). Cutthroat trout preyed on benthic insects when drifting invertebrates were unavailable. When stonefly larvae were present, the trout ate most of the stoneflies and also consumed a higher proportion of mayflies than under mayfly only treatment. The putative mechanism is that active stonefly larvae supplied visual cues to the predator that alerted trout to the mayfly larvae. Foraging success of visual predators on cryptic prey can be enhanced by distinctly coloured, active benthic taxa through unidirectional facilitation to the predators, which is a functional change of interspecific interaction caused by a third species. This study suggests that prey–predator facilitation through TMIIs can modify species interactions, affecting community dynamics.
Exceptionally preserved North American Paleogene metatherians: adaptations and discovery of a major gap in the opossum fossil record
Authors: Sánchez-Villagra Marcelo , Ladevèze Sandrine , Horovitz Inés , Argot Christine , Hooker Jeremy J , Macrini Thomas E , Martin Thomas , Moore-Fay Scott , de Muizon Christian , Schmelzle Thomas , Asher Robert J
Published: April 2007

A major gap in our knowledge of the evolution of marsupial mammals concerns the Paleogene of the northern continents, a critical time and place to link the early history of metatherians in Asia and North America with the more recent diversification in South America and Australia. We studied new exceptionally well-preserved partial skeletons of the Early Oligocene fossilHerpetotheriumfrom the White River Formation in Wyoming, which allowed us to test the relationships of this taxon and examine its adaptations. Herpetotheriidae, with a fossil record extending from the Cretaceous to the Miocene, has traditionally been allied with opossums (Didelphidae) based on fragmentary material, mainly dentitions. Analysis of the new material reveals that several aspects of the cranial and postcranial anatomy, some of which suggests a terrestrial lifestyle, distinguishHerpetotheriumfrom opossums. We found thatHerpetotheriumis the sister group to the crown group Marsupialia and is not a stem didelphid. Combination of the new palaeontological data with molecular divergence estimates, suggests the presence of a long undocumented gap in the fossil record of opossums extending some 45 Myr from the Early Miocene to the Cretaceous.
Death of an order: a comprehensive molecular phylogenetic study confirms that termites are eusocial cockroaches
Authors: Inward Daegan , Beccaloni George , Eggleton Paul
Published: April 2007

Termites are instantly recognizable mound-builders and house-eaters: their complex social lifestyles have made them incredibly successful throughout the tropics. Although known as ‘white ants’, they are not ants and their relationships with other insects remain unclear. Our molecular phylogenetic analyses, the most comprehensive yet attempted, show that termites are social cockroaches, no longer meriting being classified as a separate order (Isoptera) from the cockroaches (Blattodea). Instead, we propose that they should be treated as a family (Termitidae) of cockroaches. It is surprising to find that a group of wood-feeding cockroaches has evolved full sociality, as other ecologically dominant fully social insects (e.g. ants, social bees and social wasps) have evolved from solitary predatory wasps.
Reconnaissance and latent learning in ants
Authors: Franks Nigel R , Hooper James W , Dornhaus Anna , Aukett Philippa J , Hayward Alexander L , Berghoff Stefanie M
Published: April 2007

We show that ants can reconnoitre their surroundings and in effect plan for the future.
Temnothorax albipennis
colonies use a sophisticated strategy to select a new nest when the need arises. Initially, we presented colonies with a new nest of lower quality than their current one that they could explore for one week without a need to emigrate. We then introduced a second identical low quality new nest and destroyed their old nest so that they had to emigrate. Colonies showed a highly significant preference for the (low quality) novel new nest over the identical but familiar one. In otherwise identical experiments, colonies showed no such discrimination when the choice was between a familiar and an unfamiliar high-quality nest. When, however, either all possible pheromone marks were removed, or landmarks were re-orientated, just before the emigration, the ants chose between identical low-quality new nests at random. These results demonstrate for the first time that ants are capable of assessing and retaining information about the quality of potential new nest sites, probably by using both pheromones and landmark cues, even though this information may only be of strategic value to the colony in the future. They seem capable, therefore, of latent learning and, more explicitly, learning what not to do.
Climatic similarity and biological exchange in the worldwide airline transportation network
Authors: Tatem Andrew J , Hay Simon I
Published: April 2007

Recent increases in the rates of biological invasion and spread of infectious diseases have been linked to the continued expansion of the worldwide airline transportation network (WAN). Here, the global structure of the WAN is analysed in terms of climatic similarity to illuminate the risk of deliberate or accidental movements of climatically sensitive organisms around the world. From over 44 000 flight routes, we show, for each month of an average year, (i) those scheduled routes that link the most spatially distant but climatically similar airports, (ii) the climatically best-connected airports, and (iii) clusters of airports with similar climatic features. The way in which traffic volumes alter these findings is also examined. Climatic similarity across the WAN is skewed (most geographically close airports are climatically similar) but heavy-tailed (there are considerable numbers of geographically distant but climatically similar airports), with climate similarity highest in the June–August period, matching the annual peak in air traffic. Climatically matched, geographically distant airports form subnetworks within the WAN that change throughout the year. Further, the incorporation of passenger and freight traffic data highlight at greater risk of invasion those airports that are climatically well connected by numerous high capacity routes.
Memory for context becomes less specific with time
Authors: Wiltgen Brian J. , Silva Alcino J.
Published: April 2007

Context memories initially require the hippocampus, but over time become independent of this structure. This shift reflects a consolidation process whereby memories are gradually stored in distributed regions of the cortex. The function of this process is thought to be the extraction of statistical regularities and general knowledge from specific experiences. The current study examined this idea in mice by measuring the specificity of context memories during consolidation. In the first experiment, separate groups of animals were trained with a single shock and tested in the training context or a novel environment 1, 14, 28, or 36 d later. We found a systematic increase in generalization over this period. Initially, mice froze more in the training context, but fear of the novel environment grew over time until animals eventually froze an equivalent amount in both contexts. The second experiment demonstrated that the increase in generalization was due to a loss of detailed information about the context and not fear incubation. In this experiment, mice were exposed to the context and then trained with an immediate shock 1 or 36 d later. Animals trained 1 d after exposure acquired robust context fear that did not generalize across environments. In contrast, mice trained 36 d after exposure froze an equivalent amount in the training context and the novel environment. The same profile was observed in H-ras mutants that exhibit enhanced hippocampal plasticity and learning. These results suggest that context memories are specific early after training when they require the hippocampus, and become more general as they are permanently stored in the cortex.
Alteration of cingulate long-term plasticity and behavioral sensitization to inflammation by environmental enrichment
Authors: Shum Fanny W.F. , Wu Long-Jun , Zhao Ming-Gao , Toyoda Hiroki , Xu Hui , Ren Ming , Pinaud Raphael , Ko Shanelle W. , Lee Yong-Seok , Kaang Bong-Kiun , Zhuo Min
Published: April 2007

Exposure to an enriched environment (EE) has been shown to induce cortical plasticity. Considerable amount of research is focused on the effects of EE in the hippocampus; however, effects of EE on other brain regions and the mechanisms involved are not well known. To investigate this, we induced cortical plasticity by placing mice in an EE for one month and measured the effects of EE in the anterior cingulate cortex (ACC). Here, we show that EE enhanced the expression of the plasticity gene,egr-1, in the ACC of EE animals accompanied by enhanced cingulate long-term potentiation (LTP) and decreased cingulate long-term depression (LTD). The increased NMDA receptor NR2B/NR2A subunits current ratio is associated with the plasticity seen in the ACC while total protein levels remain unchanged. Furthermore, behavioral experiments show that these mice exposed to EE demonstrate enhanced responses to acute and long-term inflammation. Our findings suggest that exposure to EE alters physiological properties within the ACC which results in enhanced responses to inflammation.
Cutaneous squamous cell carcinoma: a comprehensive clinicopathologic classification. Part One
Authors: Cassarino David S. , DeRienzo Damian P. , Barr Ronald J.
Published: April 2007

Abstract: Cutaneous squamous cell carcinoma (SCC) includes many subtypes with widely varying clinical behaviors, ranging from indolent to aggressive tumors with significant metastatic potential. However, the tendency for pathologists and clinicians alike is to refer to all squamoid neoplasms as generic SCC. No definitive, comprehensive clinicopathological system dividing cutaneous SCCs into categories based upon their aggressiveness has yet been promulgated. Therefore, we have proposed the following based upon the malignant potential of SCC variants, separating them into categories of low (≤2% metastatic rate), intermediate (3–10%), high (greater than 10%), and indeterminate behavior. Low‐risk SCCs include SCC arising in actinic keratosis, HPV‐associated SCC, tricholemmal carcinoma, and spindle cell SCC (unassociated with radiation). Intermediate‐risk SCCs include adenoid (acantholytic) SCC, intraepidermal epithelioma with invasion, and lymphoepithelioma‐like carcinoma of the skin. High‐risk subtypes includede novoSCC, SCC arising in association with predisposing factors (radiation, burn scars, and immunosuppression), invasive Bowen's disease, adenosquamous carcinoma, and malignant proliferating pilar tumors. The indeterminate category includes signet ring cell SCC, follicular SCC, papillary SCC, SCC arising in adnexal cysts, squamoid eccrine ductal carcinoma, and clear‐cell SCC. Subclassification of SCC into these risk‐based categories, along with enumeration of other factors including tumor size, differentiation, depth of invasion, and perineural invasion will provide prognostically relevant information and facilitate the most optimal treatment for patients.
Acclimation to humic substances prevents whole body sodium loss and stimulates branchial calcium uptake capacity in cardinal tetras Paracheirodon axelrodi (Schultz) subjected to extremely low pH
Authors: Matsuo A. Y. O. , Val A. L.
Published: April 2007

Kinetics of sodium (Na+) and calcium (Ca2+) uptake were studied in cardinal tetras Paracheirodon axelrodi acclimated to humic substances (HS, 35 mg C l−1) and low pH (pH 3·72), parallel to analysis of whole body Na+ and Ca2+ content. This species had a high uptake capacity (Jmax) for both Na+ and Ca2+ in soft, ion‐poor water. The affinity constant (Km) did not vary significantly among treatments for either Na+ or Ca2+. Jmax Na+ increased 30% in fish acclimated to HS for 5 weeks. Acclimation to low pH had no effect on Jmax Na+ but this treatment was associated with a 32% decrease on whole body Na+ content, suggesting that fish were unable to compensate for the increased Na+ loss induced by extreme acidity. Exposure of fish to HS + low pH, the treatment most closely approximating to the conditions experienced by the species in its native environment, resulted in an increase in whole body Na+ by 31% relative to acclimation to low pH alone. Jmax Ca2+ in cardinal tetras was high relative to that documented in other freshwater species acclimated to soft water (Jmax= 30 nmol g−1 h−1). Prolonged exposure of fish to pH 3·72 inhibited Jmax Ca2+ by 53%, although whole body Ca2+ content remained unchanged relative to control. Acclimation of fish to HS + low pH resulted in an increase of Jmax Ca2+ by 166% relative to low pH alone. Collectively, these results suggest that HS protect cardinal tetras acclimated to soft, acidic waters by preventing excessive Na+ loss (as indicated by whole body Na+ content) and by stimulating Ca2+ uptake (as indicated by increased Jmax Ca2+) to ensure proper homeostasis.
Deep‐water chaunacid and lophiid anglerfishes (Pisces: Lophiiformes) off the south‐eastern United States
Authors: Caruso J. H. , Ross S. W. , Sulak K. J. , Sedberry G. R.
Published: April 2007

Recent research cruises to deep (80–910 m) reef habitats off the south‐eastern U.S. and in the northern Gulf of Mexico have provided new information on the diagnostic characteristics, behaviours, colour patterns in life, bottom associations, distributions and maximum sizes of species of the anglerfish genera Chaunax, Lophiodes and Sladenia. Chaunax stigmaeus occurred much further south than previously known (Blake Plateau off South Carolina), and all C. stigmaeus observed were found associated with dense beds of dead coral (Lophelia pertusa) rubble or on broken hard bottom. In contrast, Chaunax suttkusi was found on soft bottoms. Chaunax stigmaeus and C. suttkusi appear to be sympatric over a major portion of their ranges. Because knowledge of pigmentation in live or freshly caught Chaunax is critical to distinguish some members of the genus, changes in the colouration of C. suttkusi were noted and documented photographically immediately after death and after fixation. The yellow spots found on some, but not all specimens, temporarily disappeared completely after death, but they reappeared after fixation, slowly disappearing thereafter along with other carotenoid pigments. Lophiodes beroe and Lophiodes monodi were collected for the first time off the Atlantic coast of the U.S., being previously known only from the Gulf of Mexico, Caribbean Sea and the northern coast of South America. For both species (L. beroe and L. monodi), the collections included the two largest known representatives of the species (400 and 325 mm standard length, respectively). Lophiodes beroe commonly occurred on L. pertusa rubble, and seemed to prefer this habitat. Occupying such a habitat that is deep and difficult to sample probably explains how this common species escaped detection. Only a single L. monodi was collected or observed, so this species appears to be uncommon in this geographic area or at least so on coral rubble habitat. Detailed aspects of the colour patterns of both species were noted. In particular, L. beroe displayed a characteristic pattern of white patches in life that were not apparent after death. The first photographic documentation of the colour pattern in life and of the pharyngeal pigmentation of Lophiodes reticulatus is provided. The third known specimen of Sladenia shaefersi, and the first to be taken in U.S. waters was collected from coral rubble near the base of a steep 200 m scarp on the Blake Plateau.
Sex differentiation and aspects of gametogenesis in shortnose sturgeonAcipenser brevirostrumLesueur
Authors: Flynn S. R. , Benfey T. J.
Published: April 2007

Shortnose sturgeonAcipenser brevirostrumgonad samples were collected from industry‐reared fish and wild broodstock at various developmental stages to elucidate patterns of gonadal differentiation and maturation. Genital ridges, containing germ cells, were present in 26 day‐old fish and distinct gonads were present by day 54. Sturgeon gonads are known to consist of two tissue types (adipose and gametogenic) and both were present at 72 day. Anatomical differentiation of gonads occurred by 6 months and was advanced by 15 months. Ovaries had distinct lamellae while testes remained non‐lamellate. Gonial proliferation had occurred by 15 months, but the cells were not identifiable as spermatogonia or oogonia. Small white ‘pinhead’ oocytes were macroscopically visible in ovaries as early as 36 months. At 43 months ovaries were clearly organized, with some areas containing only immature oocytes and other containing oocytes apparently developing as cohorts. Individual fish showed considerable variation: the level of development remained unchanged at 84 months in some females, while others showed clear progression towards sexual maturation at 48 months. Sperm cells were present in males as early as 52 months. Advanced development of ovarian follicles was observed only in biopsies of re‐conditioned broodstock of wild origin. In the year before spawning, the most advanced oocytes became pigmented, the chorion thickened, the nucleus (germinal vesicle) migrated towards the micropyle complex at the animal pole, and ovulation occurred in May under appropriate environmental conditions.
Stock and parental effects on embryonic and early larval development of winter flounder Pseudopleuronectes americanus (Walbaum)
Authors: Butts I. A. E. , Litvak M. K.
Published: April 2007

A hierarchical breeding design was used to determine if winter flounder Pseudopleuronectes americanus embryos and yolk‐sac larvae sired by Georges Bank males developed and grew larger than fish sired by Passamaquoddy Bay males, and to examine parental contributions to variations in fertilization success, time to 50% hatch, hatch success and larval morphological development. Significant stock effects were detected for time to hatch and larval development. Eggs fertilized by Passamaquoddy Bay males reached 50% hatch significantly earlier than eggs fertilized by Georges Bank males. Larvae sired by Georges Bank males were significantly larger during larval development for four of the six traits measured at 12 days post‐hatch: head depth, jaw length, myotome height and body area. Embryo and larval development were strongly influenced by maternal contributions; there were significant maternal variance components for the majority of the variables measured. Paternal variance components were significant for fertilization success, time to hatch, larval jaw length and larval head depth, however, they acted principally through parental interactions. This information has important implications for the long‐term sustainable development of winter flounder for aquaculture purposes as well as for understanding winter flounder genetic variation in the wild.
Impact of flood on distribution of bathypelagic perch fry layer along the longitudinal profile of large canyon‐shaped reservoir
Authors: ČEch M. , Kubečka J. , Frouzová J. , Draštík V. , Kratochvíl M. , Jarošík J.
Published: April 2007

Previous studies have shown that under normal spring conditions, the layer of bathypelagic perchPerca fluviatilisfry (BPF) is equally distributed along most of the longitudinal profile of reservoirs. In the first half of June 2004, local flooding entering the large canyon‐shaped Orlík Reservoir (Czech Republic) completely flushed out the existing fry community from the 31 km long riverine part of the reservoir. The pelagic zone in this reach was then recolonized by cyprinid (mainly roachRutilus rutilusand breamAbramis brama) fry being of either littoral or riverine origin. Subsequently, the BPF layer was recorded only in the 22 km long lacustrine part of the reservoir. In the upper reach of this part where, due to the sudden increase in volume, the water current slowed down rapidly and fry originating from both riverine and central parts of the reservoir gathered in high numbers, two distinct BPF layers were observed. During mid‐day, the upper BPF layer, created predominantly by shoaling fishes (abundance >126 000 individuals ha−1), occurred between 6 and 10 m. A second, lower BPF layer, created by non‐shoaling fishes exclusively (30 000 individuals ha−1), was recorded between 12 and 17 m depth. Both upper and lower BPF layer were composed of perch (69·6 and 66·8% in abundance respectively) and zanderSander lucioperca(29·8 and 28·6% in abundance respectively). In the lower BPF layer, ruffeGymnocephalus cernuusalso contributed considerably to the fry assemblage (4·0% in abundance). Perch from the upper BPF layer (mean 25·1 mm total length,LT) did not differ in size from perch from the lower BPF layer (mean 25·0 mmLT). Similarly, zander from the upper BPF layer (mean 27·2 mmLT) were almost the same size as those from the lower BPF layer (mean 26·9 mmLT). Perch from both BPF layers, however, were noticeably smaller than zander. The results from acoustic survey and complementary net catches suggest that no epipelagic perch fry were found in the reservoir where thermal stratification had been destroyed by flooding and windy weather.
Rediscovery of Anthias salmopunctatus Lubbock & Edwards, 1981, with comments on its natural history and conservation
Authors: Luiz O. J. , Joyeux J.‐C. , Gasparini J. L.
Published: April 2007

After c. 30 years without sighting or capture, Anthias salmopunctatus was rediscovered at the type locality, St Peter and St Paul’s Rocks, Mid‐Atlantic Ridge. To date, the known distribution is restricted to depths varying from 35 to 55 m in vertical drop offs around the perimeter of the islands (c. 400 m). This may be the smallest geographic range known for a marine fish species.
Saltatory search in a lateral line predator
Authors: Bassett D. K. , Carton A. G. , Montgomery J. C.
Published: April 2007

The dwarf scorpionfish Scorpaena papillosa detected the hydrodynamic signals produced by prey with the mechanosensory lateral line. This species displayed a pause and move search pattern that is consistent with a saltatory search. The pause phase of the search cycle was probably used to detect prey because pauses often ended early in order to initiate an approach at prey and prey were detected throughout the search space. The move phase of the search cycle repositioned the fish so that it moved approximately a third of the reactive distance. Move distance was found to be the most important factor in gaining novel search space. Turning was shown to be relatively unimportant in gaining novel search space with a high frequency of low turn angles made by the fish. The dwarf scorpionfish, however, exhibited a spiralling or looping pattern over a search path exhibiting a turn bias towards either the left or right. The dwarf scorpionfish adopted a search behaviour that is consistent with a saltatory search and efficient for lateral line predation.
Predation of perch on vendace larvae: diet composition in an oligotrophic lake and digestion time of the larvae
Authors: Haakana H. , Huuskonen H. , Karjalainen J.
Published: April 2007

The diet of perch Perca fluviatilis was studied to reveal possible predation on vendace Coregonus albula larvae in an oligotrophic lake. Perch diet changed with the size of the fish: small perch ate mainly zooplankton and the diet shifted more to benthic invertebrates and fishes in larger perch. There were also annual and spatial differences in the diet, probably reflecting differences in the availability of prey animals. Perch predation on vendace larvae was only observed in the area with high availability of the larvae. The result suggested strengthened predation when the density of the larvae increases. According to bioenergetics modelling, the perch population increased natural mortality of vendace larvae only marginally. Food intake of spawning female perch was slightly reduced, whereas spawning males fed similarly to non‐spawning males. Hence, the spawning period of perch was only a minor refuge for vendace larvae. Laboratory experiments of perch digestion rate demonstrated that, due to rapid digestion of the small fish larvae, diet sampling interval should not be >2 h in the field.
Measurements of salmonid population performance in relation to habitat in eastern Newfoundland streams
Authors: Cote D.
Published: April 2007

The density, biomass and estimated production of brook trout Salvelinus fontinalis and Atlantic salmon Salmo salar were related to habitat factors in streams of Terra Nova National Park, Newfoundland, Canada. Fish communities at 29 sites (18 brooks; 15 watersheds) were sampled in the summer of 2002, 2003 and 2005. Salmonid density, biomass per unit area and production (derived from biomass and fish size using allometric P:B relationships) were compared with site habitat characteristics (wetted width, lactustrine habitat, per cent riffle habitat, canopy coverage and stream gradient), using an interactive stepwise multiple linear regression. Salmonid biomass (mean: 2·87 g m−2; range: 0·33–10·88 g m−2) and estimated production (mean: 3·05 g m−2 year−1; range: 0·32–10·98 g m−2 year−1) within the study area varied by an order of magnitude, however, habitat variables accounted for much of this variation. Specifically, wetted width and lacustrine area of the tributary played important roles in explaining density, biomass and production. Wetted width was important for all measurements of brook trout and total salmonids while lacustrine area was important for all measurements of Atlantic salmon and played a lesser role in total salmonid biomass. Other factors such as the percentage of riffle habitat, site gradient and canopy coverage provided modest improvements to the fit of some relationships. When models using the same environmental factors were compared, those using production estimates derived from allometric P:B equations in the literature provided improved predictive capability than did those from direct density and biomass estimates. It is proposed that allometric P:B relationships have utility in improving comparisons of stream fish communities, particularly in studies with insufficient resources to measure production directly.
Condition‐dependent reproductive tactics by large and small anadromous male sockeye salmon Oncorhynchus nerka
Authors: Allen C. S. , Rich H. B. , Quinn T. P.
Published: April 2007

Reproductive tactics, aggression and courtship by large and small (jack) male sockeye salmon Oncorhynchus nerka with ripe females in temporary enclosures depended on the size and behaviour of the competitor, not the size of the focal male. When paired with other jacks or with large but less aggressive males, jacks fought for access to ripe females rather than sneaking, but used sneaking tactics when paired with large, aggressive males. Dominant males of both size groups courted actively and females spawned readily with all combinations of males.
Spawning‐related fungal infection of golden galaxias Galaxias auratus (Galaxiidae)
Authors: Hardie S. A. , Pyecroft S. B. , Barmuta L. A. , White R. W. G.
Published: April 2007

The occurrence of golden galaxias Galaxias auratus with dermal fungal lesions in two populations was effectively modelled by the progression of gonadal stages of development. Skin lesions were found to be characteristic of fungal dermatitis and a Saprolegnia sp. was identified as the causative agent. Infection is probably linked to spawning‐related factors and it is probable that saprolegniasis is associated with seasonal mortality.
Variations in the spawning periodicity of eight fish species in three English lowland rivers over a 6 year period, inferred from 0+ year fish length distributions
Authors: Nunn A. D. , Harvey J. P. , Cowx I. G.
Published: April 2007

The spawning periodicity of eight fish species was investigated in three English lowland rivers over a 6 year period from patterns in 0+ year fish standard length (LS) distributions. A single cohort of 0+ year dace Leuciscus leuciscus, roach Rutilus rutilus and perch Perca fluviatilis was observed each year, suggesting that these species spawned only once annually. By contrast, populations of chub Leuciscus cephalus, bleak Alburnus alburnus, bream Abramis brama, gudgeon Gobio gobio and minnow Phoxinus phoxinus were inferred to spawn on more than one occasion each year. Annual and intercatchment variations occurred in the LS distribution patterns of some of the fish species. In chub, for example, although a minimum of two 0+ year cohorts occurred in all years in the River Trent, ‘multiple’ spawning (either at the individual or population level) was most apparent in 1999, 2003 and 2004. By contrast, ‘multiple’ spawning events were not evident in all years in the Warwickshire Avon and Yorkshire Ouse, with recruitment presumably based upon a single spawning event in some years. There is effectively a trade‐off between early spawning (extended growing season), and the possibility that environmental conditions will impact upon recruitment success, and the potential for reduced overwinter survival of smaller individuals with lower lipid resources from later spawning events. Notwithstanding, fishes as small as 15 mm LS survived the winter in some years, suggesting that progeny from later spawning events may make important contributions to fish recruitment success.
Implications of CO2 fertilization for future climate change in a coupled climate–carbon model
Authors: MATTHEWS H. DAMON
Published: April 2007

The terrestrial carbon cycle plays a critical role in determining levels of atmospheric CO2 that result from anthropogenic carbon emissions. Elevated atmospheric CO2 is thought to stimulate terrestrial carbon uptake, through the process of CO2 fertilization of vegetation productivity. This negative carbon cycle feedback results in reduced atmospheric CO2 growth, and has likely accounted for a substantial portion of the historical terrestrial carbon sink. However, the future strength of CO2 fertilization in response to continued carbon emissions and atmospheric CO2 rise is highly uncertain. In this paper, the ramifications of CO2 fertilization in simulations of future climate change are explored, using an intermediate complexity coupled climate–carbon model. It is shown that the absence of future CO2 fertilization results in substantially higher future CO2 levels in the atmosphere, as this removes the dominant contributor to future terrestrial carbon uptake in the model. As a result, climate changes are larger, though the radiative effect of higher CO2 on surface temperatures in the model is offset by about 30% due to reduced positive dynamic vegetation feedbacks; that is, the removal of CO2 fertilization results in less vegetation expansion in the model, which would otherwise constitute an important positive surface albedo‐temperature feedback. However, the effect of larger climate changes has other important implications for the carbon cycle – notably to further weaken remaining carbon sinks in the model. As a result, positive climate–carbon cycle feedbacks are larger when CO2 fertilization is absent. This creates an interesting synergism of terrestrial carbon cycle feedbacks, whereby positive (climate–carbon cycle) feedbacks are amplified when a negative (CO2 fertilization) feedback is removed.
Case of Staphylococcus schleiferi subspecies coagulans endocarditis and metastatic infection in an immune compromised host
Authors: Kumar D. , Cawley J.J. , Irizarry‐Alvarado J.M. , Alvarez A. , Alvarez S.
Published: April 2007

Abstract: Staphylococcus schleiferi subspecies coagulans is a relatively recently described organism with limited human pathogenicity. Described case reports of infection are primarily limited to canine external otitis with only one reported case of human involvement, localized to a surgical wound infection. Similarities in phenotypic and microbiological characteristics between S. schleiferi subsp. coagulans and S. aureus have resulted in frequent mistakes using common methods of identification. We describe the first case of disseminated human infection with this species, definitively identified using DNA sequencing, and successfully treated with conventional therapy.
Cerebral toxoplasmosis in an allogeneic peripheral stem cell transplant recipient: case report and review of literature
Authors: Cibickova L. , Horacek J. , Prasil P. , Slovacek L. , Kohout A. , Cerovsky V. , Hobza V.
Published: April 2007

Abstract: We present a patient who underwent allogeneic peripheral stem cell transplantation (PSCT) for chronic myelocytic leukemia. Twenty months after the PSCT he experienced status epilepticus. Magnetic resonance imaging (MRI) revealed a focus in the ventral thalamus–hypothalamus region. Using stereotactic biopsy with histology and specific polymerase chain reaction investigation from brain tissue, cerebral toxoplasmosis was diagnosed and treated with antiparasitic therapy. Early recognition of such serious and potentially lethal disease enabled prompt specific treatment. This case report emphasizes the role of stereotactic biopsy in diagnosis of cerebral toxoplasmosis. Other methods such as MRI are non‐invasive but not sufficiently specific and sensitive.
Rhodococcus lung abscess complicating kidney transplantation: successful management by combination antibiotic therapy
Authors: Tse K.C. , Tang S.C.W. , Chan T.M. , Lai K.N.
Published: April 2007

Abstract: In this report, a renal transplant recipient with Rhodococcus lung abscess is described. A high clinical suspicion and appropriate combination antibiotic therapy obviated the need for surgical intervention and was associated with a good clinical outcome. The optimal regimen of combination antibiotic therapy is discussed.
Additional gas injection after failed macular hole surgery with internal limiting membrane peeling
Authors: Iwase Takeshi , Sugiyama Kazuhisa
Published: April 2007

Abstract

Purpose:  To report the efficacy of additional intravitreal gas injection in eyes where primary failure occurred following apparently successful macular hole surgery.

Methods:  Patients presenting with macular hole underwent a primary surgical procedure consisting of vitrectomy with phacoemulsification and intraocular lens implantation. The internal limiting membrane was stained with indocyanine green and peeled. At the end of this manoeuvre a fluid–gas exchange was performed and the macular hole tamponaded with 20% sulphur hexafluoride. The patients were instructed to assume a face‐down position for 12 h per day until the macular hole closed. In those cases where primary closure was not achieved, an additional quantity of 20% sulphur hexafluoride was injected into the vitreous cavity via a 27‐gauge needle connected to a 5‐mL syringe. The patients were instructed to assume the same position.

Results:  A total of 40 eyes from 40 consecutive patients underwent primary macular hole surgery. The macular hole was not successfully closed in seven eyes and a further gas injection was made in these eyes. This additional procedure led to macular hole closure in all cases within a mean of 4.1 days. Visual acuity improved in all seven eyes, and the final visual outcomes were no worse than those eyes that had successful primary closure.

Conclusions:  Additional gas injection is an effective treatment for eyes with open holes following unsuccessful primary surgery.
Leucocytoclastic vasculitis presenting as bilateral marginal keratitis
Authors: Li Yim James FT , Agarwal Pankaj K , Fern Alasdair
Published: April 2007

Abstract

Leucocytoclastic vasculitis is an immune‐mediated, neutrophil‐induced small vessel disease. Clinically, it presents with cutaneous palpable painless purpuric papules on the extremities. Ocular manifestation reported in the literature is rare and includes peripheral ulcerative keratitis, panuveitis and multifocal retinitis all preceded by cutaneous lesions. Herein a fatal case of leucocytoclastic vasculitis initially presenting with bilateral marginal keratitis without any cutaneous lesions is reported.
In vivo confocal microscopy and polarizing microscopy of the cornea in a patient with nephropathic cystinosis
Authors: Fung Adrian T , Fraser‐Bell Samantha , Ojaimi Elvis , Sutton Gerard
Published: April 2007

Abstract

The clinicopathological and in vivo confocal microscopic characteristics of the corneas from a patient with infantile cystinosis is reported. Crystals were demonstrated in the epithelium and stroma of this patient.
Exploring the physiological effects of double‐cone coil TMS over the medial frontal cortex on the anterior cingulate cortex: an H215O PET study
Authors: Hayward Gail , Mehta Mitul A. , Harmer Catherine , Spinks Terry J. , Grasby Paul M. , Goodwin Guy M.
Published: April 2007

Transcranial magnetic stimulation (TMS) using a double‐cone coil over the medial frontal cortex has the potential to clarify the function of the anterior cingulate cortex (ACC) in cognition, emotion and mood disorders. Following demonstration of disruption of performance on psychological tasks closely linked to cingulate function using this TMS technique, the current study aimed to directly measure the regional distribution of physiological effects of stimulation in the brain with H215O PET. Experiment 1 assessed the effect of increasing numbers of pulse trains of TMS on regional cerebral blood flow (rCBF). Experiment 2 assessed the capacity of medial frontal TMS to modulate brain activity associated with the Stroop task using medial parietal TMS as a control site of stimulation. SPM99 analyses, using the ACC as a region of interest, revealed clusters of increased rCBF during medial frontal TMS in Brodmann area 24 and reduced rCBF in more ventral ACC, the latter occurring in both experiments. In a whole‐brain analysis, striking changes in rCBF were observed distal to the ACC following medial frontal TMS. Although TMS reliably affected Stroop task performance in early trials, there was no interaction between TMS and Stroop condition in rCBF. Our results suggest that medial frontal TMS using the double‐cone coil can affect ACC activity. However, a number of more distal cortical areas were also affected in these experiments. These additional changes may reflect either ‘downstream’ effects of altered cingulate cortex activity or direct effects of the coil.