bluuebunny/crossref_metadata_2025 huggingface dataset:
Disparate maturation adaptations to size-dependent mortality
Authors: Gårdmark Anna , Dieckmann Ulf
Published: May 2006

Body size is an important determinant of resource use, fecundity and mortality risk. Evolution of maturation size in response to size-dependent selection is thus a fundamental part of life-history theory. Increased mortality among small individuals has previously been predicted to cause larger maturation size, whereas increased mortality among large individuals is expected to have the opposite effect. Here we use a continuously size-structured model to demonstrate that, contrary to these widespread expectations, increased mortality among small individuals can have three alternative effects: maturation size may increase, decrease or become evolutionarily bistable. We show that such complex responses must be reckoned with whenever mortality is size-dependent, growth is indeterminate, reproduction impairs growth and fecundity increases with size. Predicting adaptive responses to altered size-dependent mortality is thus inherently difficult, since, as demonstrated here, such mortality cannot only reverse the direction of adaptation, but also cause abrupt shifts in evolutionarily stable maturation sizes.
Differences in cue use and spatial memory in men and women
Authors: Jones Catherine M , Healy Susan D
Published: May 2006

Men and women differ in their ability to solve spatial problems. There are two possible proximate explanations for this: (i) men and women differ in the kind (and value) of information they use and/or (ii) their cognitive abilities differ with respect to spatial problems. Using a simple computerized task which could be solved either by choosing an object based on what it looked like, or by its location, we found that the women relied on the object's visual features to solve the task, while the men used both visual and location information. There were no differences between the sexes in memory for the visual features of the objects, but women were poorer than men at remembering the locations of objects.
Host heterogeneity dominates West Nile virus transmission
Authors: Marm Kilpatrick A , Daszak Peter , Jones Matthew J , Marra Peter P , Kramer Laura D
Published: May 2006

Heterogeneity in host populations and communities can have large effects on the transmission and control of a pathogen. In extreme cases, a few individuals give rise to the majority of secondary infections, which have been termed super spreading events. Here, we show that transmission of West Nile virus (WNV) is dominated by extreme heterogeneity in the host community, resulting in highly inflated reproductive ratios. A single relatively uncommon avian species, American robin (
Turdus migratorius
), appeared to be responsible for the majority of WNV-infectious mosquitoes and acted as the species equivalent of a super spreader for this multi-host pathogen. Crows were also highly preferred by mosquitoes at some sites, while house sparrows were significantly avoided. Nonetheless, due to their relative rarity, corvids (crows and jays) were relatively unimportant in WNV amplification. These results challenge current beliefs about the role of certain avian species in WNV amplification and demonstrate the importance of determining contact rates between vectors and host species to understand pathogen transmission dynamics.
Facial and bodily correlates of family background
Authors: Boothroyd Lynda G , Perrett David I
Published: May 2006

It has been suggested that absence of the father during early childhood has long-reaching effects on reproductive strategy and development of offspring. This paper reports two studies designed to investigate the physical characteristics of daughters associated with father absence. Study 1 used a facial averaging method to produce composite images of faces of women whose parents separated during their childhood (who were ‘father absent’), women whose parents remained together, but had poor quality relationships and women whose parents were together and had good quality relationships. Images were then rated by male and female judges. Father absence and poor parental relationships were associated with apparent facial masculinity and reduced attractiveness in daughters. Poor parental relationships were also associated with reduced apparent health. Study 2 compared family background with body measurements and found that father absence or a poor quality relationship between parents were associated with body masculinity (high waist-to-hip ratio) and increased weight-for-height and adiposity. These results highlight the possibility of physical masculinization being associated with purported father absence ‘effects’.
Incipient speciation through niche expansion: an example from the Arctic charr in a subarctic lake
Authors: Knudsen Rune , Klemetsen Anders , Amundsen Per-Arne , Hermansen Bjørn
Published: May 2006

Two reproductive isolated morphs of Arctic charr (Salvelinus alpinus), termed profundal and littoral charr according to their different spawning habitats, co-occur in the postglacial lake Fjellfrøsvatn in North Norway. All profundal charr live in deep water their entire life and have a maximum size of 14 cm, while the littoral charr grow to 40 cm. Some small and young littoral charr move to the profundal zone in an ontogenetic habitat shift in the ice-free season and the rest of the population remains in epilimnic waters. The two morphs had different diet niches in the profundal zone: the profundal charr ate typical soft-bottom prey (chironomid larvae, pea mussels and benthic copepods), while the young littoral charr mainly consumed crustacean zooplankton. In four other lakes without a profundal morph (i.e. monomorphic populations), young charr also performed ontogenetic habitat shifts to the profundal zone and fed on zooplankton. The profundal morph of Fjellfrøsvatn therefore utilize a food resource niche that neither the littoral morph nor comparable monomorphic populations exploit. This suggests that intraspecific resource competition has driven incipient ecological speciation of the profundal charr of Fjellfrøsvatn. The exploitation of the soft-bottom resources by the profundal charr supports earlier experimental findings that the profundal morph is genetically different in trophic behaviour and morphology. The sympatric ecological divergence within the profundal habitat is possible because unexploited food resources (soft-bottom profundal prey) are available. Apparently, this represents a case of incipient segregation by expansion to new resource types (niche invasion), and not by subdivision of one broad ancestral niche.
A fresh look at the fossil evidence for early Archaean cellular life
Authors: Brasier Martin , McLoughlin Nicola , Green Owen , Wacey David
Published: May 2006

The rock record provides us with unique evidence for testing models as to when and where cellular life first appeared on Earth. Its study, however, requires caution. The biogenicity of stromatolites and ‘microfossils’ older than 3.0 Gyr should not be accepted without critical analysis of morphospace and context, using multiple modern techniques, plus rejection of alternative non-biological (null) hypotheses. The previous view that the co-occurrence of biology-like morphology and carbonaceous chemistry in ancient, microfossil-like objects is a presumptive indicator of biogenicity is not enough. As with the famous Martian microfossils, we need to ask not ‘what do these structures remind us of?’, but ‘what are these structures?’ Earth's oldest putative ‘microfossil’ assemblages within 3.4–3.5 Gyr carbonaceous cherts, such as the Apex Chert, are likewise self-organizing structures that do not pass tests for biogenicity.

There is a preservational paradox in the fossil record prior toca2.7 Gyr: suitable rocks (e.g. isotopically light carbonaceous cherts) are widely present, but signals of life are enigmatic and hard to decipher. One new approach includes detailed mapping of well-preserved sandstone grains in theca3.4 Gyr Strelley Pool Chert. These can contain endolithic microtubes showing syngenicity, grain selectivity and several levels of geochemical processing. Preliminary studies invite comparison with a class of ambient inclusion trails of putative microbial origin and with the activities of modern anaerobic proteobacteria and volcanic glass euendoliths.
Gene expression analysis using human cancer xenografts to identify novel predictive marker genes for the efficacy of 5‐fluorouracil‐based drugs
Authors: Ooyama Akio , Takechi Teiji , Toda Etsuko , Nagase Hideki , Okayama Yoshihiro , Kitazato Kenji , Sugimoto Yoshikazu , Oka Toshinori , Fukushima Masakazu
Published: May 2006

The development of a diagnostic method for predicting the therapeutic efficacy or toxicity of anticancer drugs is a critical issue. We carried out a gene expression analysis to identify genes whose expression profiles were correlated with the sensitivity of 30 human tumor xenografts to 5‐fluorouracil (5‐FU)‐based drugs (tegafur + uracil [UFT], tegafur + gimeracil + oteracil [S‐1], 5′‐deoxy‐5‐fluorouridine [5′‐DFUR], and N4‐pentyloxycarbonyl‐5′‐deoxy‐5‐fluorocytidine [capecitabine]), as well as three other drugs (cisplatin [CDDP], irinotecan hydrochloride [CPT‐11], and paclitaxel) that have different modes of action. In the present study, we focused especially on the fluoropyrimidines. The efficacy of all anticancer drugs was assayed using human tumor xenografts in nude mice. The mRNA expression profile of each of these xenografts was analyzed using a Human Focus array. Correlation analysis between the gene expression profiles and the chemosensitivities of seven drugs identified 39 genes whose expression levels were correlated significantly with multidrug sensitivity, and we suggest that the angiogenic pathway plays a pivotal role in resistance to fluoropyrimidines. Furthermore, many genes showing specific correlations with each drug were also identified. Among the candidate genes associated with 5‐FU resistance, the dihydropyrimidine dehydrogenase mRNA expression profiles of the tumors showed a significant negative correlation with chemosensitivity to all of the 5‐FU based drugs except for S‐1. Therefore, the administration of S‐1 might be an effective strategy for the treatment of high dihydropyrimidine dehydrogenase‐expressing tumors. The results of the present study may enhance the prediction of tumor response to anticancer drugs and contribute to the development of tailor‐made chemotherapy. (Cancer Sci 2006; 97: 510 – 522)
Management of Chinese patients on warfarin therapy in two models of anticoagulation service – a prospective randomized trial
Authors: Chan Fredric W. H. , Wong Raymond S. M. , Lau Wing‐Hung , Chan Thomas Y. K. , Cheng Gregory , You Joyce H. S.
Published: May 2006

Aim

To compare the treatment outcomes of a clinical pharmacist‐managed anticoagulation service with physician‐managed service in Chinese patients.

Methods

A prospective, randomized clinical trial was conducted at the anticoagulation clinic of a teaching hospital in Hong Kong. Patients aged ≥ 18 years who would required warfarin therapy for at least 3 months were recruited. Patients were randomized to the pharmacist‐managed or physician‐managed group. Primary clinical outcome was assessed by the percentage of patient time spent within the target international normalized ratio (INR) range. The incidence of major thromboembolic events (TEs) and major bleeding was assessed as secondary clinical outcomes. The cost per patient per month (cPPPM) was calculated and patient satisfaction was assessed by patient satisfaction questionnaire (PSQ)‐18.

Results

One hundred and forty‐one patients were recruited at the anticoagulation clinic and 137 patients completed the study. Patients in the pharmacist‐managed group (n = 68) were in the target INR 64% of patient time vs. 59% in the physician‐managed group (n = 69) (P < 0.001). There was no significant difference in incidence of major TEs or bleeding. The cPPPM in the pharmacist‐managed group (US$76 ± 95) (£43 ± 53) was lower than in the physician‐managed group (US$98 ± 158) (£55 ± 89) (P < 0.001). The PSQ‐18 score of the pharmacist‐managed group (3.8 ± 0.2) was higher than that of the physician‐managed group (3.6 ± 0.3) (P < 0.001).

Conclusion

The pharmacist‐managed anticoagulation service was more effective and less costly than the physician‐managed service in achieving target anticoagulation control for Chinese patients on warfarin therapy.
Variability in non‐nucleoside reverse transcriptase and protease inhibitor concentrations among HIV‐infected adults in routine clinical practice
Authors: Moltó José , Blanco Asunción , Miranda Cristina , Miranda José , Puig Jordi , Valle Marta , DelaVarga Meritxell , Fumaz Carmina R. , Barbanoj Manuel José , Clotet Bonaventura
Published: May 2006

What is already known about this subject

The concentration of protease and non‐nucleoside reverse transcriptase inhibtors in plasma has been related to both efficacy and toxicity.

Most antiretroviral concentration data come from selected populations of patients undergoing therapeutic drug monitoring programmes, which may overestimate interindividual variability.

What this study adds

Our study has demonstrated the large interindividual variability in antiretroviral drug concentrations in an unselected population of patients during routine clinical practice.

These results may provide interesting information to clinicians for the management of antiretroviral therapy in HIV‐infected patients.

Aims

The objective of this study was to assess interindividual variability in trough concentrations of plasma of non‐nucleoside reverse transcriptase inhibitors (NNRTI) and protease inhibitors (PI) among HIV‐infected adults in a routine outpatient setting.

Methods

One hundred and seventeen patients who attended our clinic for routine blood tests, and who were receiving antiretroviral therapy which included NNRTI or PI were studied. Patients were not informed that drug concentrations were going to be measured until blood sampling. The times of the last antiretroviral dose and of blood sampling were recorded. Drug concentrations were considered optimal if they were above the proposed minimum effective value. In addition, efavirenz, nevirapine and atazanavir concentrations were considered potentially toxic if they were > 4.0 mg l−1, > 6.0 mg l−1 and > 0.85 mg l−1, respectively.

Results

Overall, interindividual variability of NNRTI and PI concentrations in plasma was approximately 50%, and only 68.4% of the patients had drug concentrations within the proposed therapeutic range. Poor adherence explained only 35% of subtherapeutic drug concentrations.

Conclusion

Interindividual variability in trough concentrations of NNRTI and PI among HIV‐infected adults is large in routine clinical practice, with drug concentrations being outside the therapeutic window in a significant proportion of patients. These findings provide further evidence that therapeutic drug monitoring may be useful to guide antiretroviral therapy in clinical practice.
A survey of the fauna of streams on Mount Elgon, East Africa, with special reference to the Simuliidae (Diptera)
Authors: WILLIAMS T. R. , HYNES H. B. N.
Published: May 2006

The stream fauna of Mt Elgon is described from collections taken during a 6‐week visit. Collections were mainly made on the cultivated slopes below the belt of montane forest, and although stations were concentrated on the western sides of the mountain sufficient were worked elsewhere to show that there was little or no geographical variation of the fauna.

The streams are physically diverse but faunistically rather uniform, with a few genera dominating the fauna throughout the entire range of altitude investigated. Most of the other taxa showed evidence of altitudinal limitation which may be attri‐buted to the pronounced temperature gradients of the mountain's streams.

As the species of Simuliidae and adult Elminthidae could be reliably distinguished their distributions were studied in greater detail. The Simuliidae showed a pronounced zonation of species, the majority being confined to narrow ranges of altitude below the forest margin. Factors considered to influence their distribution were principally altitude (temperature), current speed and, to a lesser extent, stream size. The influence of these factors on the distribution of adult Elminthids was less marked, although all species showed at least an upper or a lower limit of altitude, and more than half the commoner species a preference for a particular stream type.

Taxonomic knowledge of African freshwater faunas allows few groups to be identified beyond the genus, and with this limitation the Elgon stream fauna is found to differ in only minor respects from the faunas of other highland areas in Central Africa.
The determination of mineralization losses in correlation with the estimation of net primary production with the oxygen method and chemical inhibitors
Authors: GOLTERMAN H. L.
Published: May 2006

In samples of eutrophic lake water incubated during a few days with dinitrophenol it was found that the decrease of particulate‐carbon was about equal to the decrease of the particulate‐nitrogen (in %) and was lower than the simultaneous O2‐consumption. The measured mineralization appeared to be strongly temperature‐dependent and nearly stopped at 3°C. These facts suggest that the mineralization of the particulate material is caused by a bacterial process and not only by respiration. It means, that only part of the O2 consumption in darkness (overnight) should be subtracted from the net algal production in the light to estimate the net daily production. Further, it could be demonstrated with samples incubated with DCMU that the oxygen consumption in hght bottles is larger than in the dark bottle. The two effects work in the same direction as they both increase the results of the calculation of daily primary production from the field observations.
The chemical hydrology of the River Oshun, Western State, Nigeria
Authors: EGBORGE AUSTIN B.M.
Published: May 2006

The changes in the chemistry of the waters of a small river before and immediately after it has been dammed are reported here.

Pre‐impoundment investigations reveal the paucity of nutrient salts which became slightly more concentrated in the Ientic environment created after the closure of the dam. Also, the fluctuations in the chemistry of the waters were influenced by a number of physical factors notably water level, current velocity and temperature.

Deoxygenation of the usually oxygen‐undersaturated river waters was not observed after the closure of the Asejire dam built across the River Oshun.
Suspended organic matter in fast‐flowing streams in Scotland
Authors: EGGLISHAW HENRY J. , SHACKLEY P. E.
Published: May 2006

1. Samples of suspended microscopic particles were collected from a small stream (Shelligan Burn) over a distance of 3–6 km, in conditions of low and high flow, and from a longer stream (River Almond) over a distance of 27 km during average flow.

2. In the low‐flow conditions in the Shelligan Burn the commonest material was non‐cellular detritus, with living diatoms, all originating from the bed of the stream, as the only other relatively abundant component. The concentration of some species of diatoms varied considerably in the course of the stream, others were more evenly distributed. Zoospores of Chlorophyceae were In much higher concentration in one short stretch of the stream, whereas filaments of the same group were fairly evenly distributed. Backwaters contained lower concentrations of certain components, presumably due to local sedimentation in the decreasing rate of flow. No clear differ‐ences were found between samples from pool stations and those from nearby riffles. A sample from the mouth of a small tributary contained more of certain materials originating from its denser bankside vegetation, and less moss because of its sparse‐ness on the unstable bed. Its diatom flora was different from that of the main stream, having fewer of the epilithic and epiphytic species but more of the mud‐surface ones. As there was no significant downstream increase in the volume of flow the absolute abundance of particles was relative to their concentration.

3. In one flood condition in the same stream there was a downstream increase in the concentration of suspended monocotyledenous tissue and non‐cellular detritus. The absolute abundance of detritus at the most downstream station was at least forty‐five times greater than it was in the low‐flow conditions.

4. In the River Almond the commonest materials in suspension were again non‐cellular detritus and diatom cells. There was a distinct downstream increase in the concentration of the diatoms and also of Chlorophyceae. The volume of flow increased downstream so that between the most upstream and downstream stations tbe absolute abundance of diatoms increased 100 times and Chlorophyceae increased 1000 times.
Aquatic macrophytes as limnological indicators
Authors: SEDDON B.
Published: May 2006

Species of submersed and floating‐leaved aquatic macrophytes have been place in a series based on their patterns of occurrence in an ordination of floristic lists. Two chemical parameters from lake water analyses are correlated with the species assemblage in individual lakes and trophic categories are defined on the quantitative chemical characteristics of lake waters. The range and limiting tolerance of solute content for many aquatic species are described and related to these trophic categories. Restiction towards eutrophic conditions is considered as an obligate relatinship reflecting physiological demands. Some dystrophic and oligotrophic species are shown to have wide tolerance and are thought to be excluded from sites of higher trophic status by competition rather than physiological limitation.
The vertical distribution of some ciliated Protozoa in the plankton of a eutrophic pond during summer stratification
Authors: GOULDER R.
Published: May 2006

The vertical distribution of some ciliated Protozoa in the plankton of a pond in north‐west England was investigated during August 1971. At this time, when the pond was stratified with an oxygen dificient hypolimnion, ciliates were counted at 10‐cm depth intervals every 5 h over 25 h. The most common species (Loxodes magnus and L. striatus) were confined to the hypolimnion; there was no diurnal migration into the epilimnion.

Earlier work had shown that Loxodes species require oxygen; it is therefore possible that these ciliates, which inhabited the oxygen dificient hypolimnion, migratedvertically, from time to time, to an oxygen supply at the boundary with the well‐oxygenated epilimnion. To test this, Loxodes populations were confined in cellophane tubese both in the hypolimnion (at 3 m) and epilimnion (0.5 m) for 12 and 24 h (earlier trials had shown that the tubes were not markedly toxic). The ciliates died at both depths, and in a further experiment when Loxodes were confined at 3 m and 0.5 m and sampled at 5‐h intervals up to 25 h it was found that they survived longer in the hypolimnion. It is suggested that ciliatees confined at 3 m died because they were unable to migrate vertically to an oxygen supply, while those at 0.5 m died because some other adverse factor was operating in the eiplimnion. Laboratory experiments showed that Loxodes died inn water in which phytoplankton photosynthesis took place and it is suggested that side effects of photosynthesis in the epilimnion (e.g. a rise in pH) caused the death of ciliates exposed at 0.5 m.
The variability in numbers of perch Perca fluviatilis L. caught in traps
Authors: BAGENAL T. B.
Published: May 2006

The variability in the catch of perch traps set in Windermere over the period 1955–70 has been analysed. Altogether 2690 catches in four series have been treated by analyses of variance after a logarithmic transformation. A representative value of the between traps variance from all sources of variation has been used to estimate the reliability of the mean catches based on different numbers of traps. It is shown that many traps are needed to obtain consistent results.
The variability of the catch from gill nets set for pike Esox lucius L.
Authors: BAGENAL T. B.
Published: May 2006

The variability of the catch of pike Esox lucius L. from gill nets in Windermere over the period 1961–71 has been analysed. Altogether 2952 catches have been treated by analysis of variance after an appropriate transformation. A representative value of the residual between catch variance has been used to estimate the reliability of the means of catches based on different numbers of net settings. It is shown that many settings of gill nets are required to get a reliable mean catch.
A pneumatically‐operated water sampler for close intervals of depth
Authors: HEANEY S. I.
Published: May 2006

A pneumatically‐operated sampler for collecting water samples at close intervals of depth in lakes is described. The sampler uses plastic disposable syringes and may be operated at various depths and at the mud‐water interface. Examples of results obtained with the sampler are given.
Studies on Plover Cove Reservoir, Hong Kong: composition and distribution of the phytoplankton and its relationship to environmental factors
Authors: HODGKISS I. J.
Published: May 2006

Phytoplankton counts and chemical/physical analyses were carried out twice weekly for 2^ years on samples taken from Plover Cove Reservoir, and a description of the variations in species composition and abundance is followed by an analysis of the effects of these environmental factors on algal growth, and their correlation with phytoplankton abundance. In addition, 24‐h surveys were carried out over a 1‐year period in an attempt to evaluate the seasonal, diurnal and vertical distribution patterns ofthe more abundant phytoplankters.

Blue‐green algal blooms were greatest in winter 1967/68 and in autumn 1969; shoreline‐attached diatoms were prevalent in winter 1968/69 and winter 1969/70. The blue‐green algal blooms have been attributed to a high rate of phosphorus and nitrogen supply, and the occurrence of diatoms at such specific times to an increase in light penetration due to the paucity of phytoplankton at these times. Various well‐marked distribution patterns were seen, and the seasonal pattern in the case of Microcystis aeruginosa was shown to be closely correlated with fluctuations in certain chemical parameters, namely. ammonia‐N, nitrate‐N and phosphate concentrations. Predictions have been made concerning future trends in the algal community of the reservoir.
The seasonal and spatial distribution of some benthic ciliated Protozoa in Esthwaite Water
Authors: GOULDER R.
Published: May 2006

From April 1969 to December 1970, oxygen concentrations and other physical and chemical parameters were determined in the bottom water at five sites (depths 14, 12, 8, 5 and 3 m) in Esthwaite Water in the English Lake District. In winter the bottom water at all five sites was oxygenated; while in summer, conditions at the deeper sites became anaerobic and concentrations of sulphide, ammonia and carbon dioxide increased.

During the same period, some benthic ciliated Protozoa were counted at the same five sites. The species considered were Loxodes magnus, L. striatus, Frontonia leucas, Spirostomum minus, S. teres, Stentor coeruleus, S. polymorphus and Caenomorpha medusula and populations were assessed as number of individuals per 01 ml of sediment. It was found that: (1) the most dense populations tended to be at the deeper sites; (2) population maxima generally occurred when the bottom water was oxygenated (except for C. medusula) and; (3) there was, over the 21 months, considerable irregularity in the size and timing of population maxima.

In March‐April 1970, population densities of benthic ciliates, at the five sites, were measured in terms of individuals per cm2 of lake bottom. Population densities decreased with decrease in site depth. The availability of food organisms, turbulence and sediment texture were considered as factors which might control this distribution.
The seasonal variation and distribution of phytoplankton in the River Oshun, Nigeria
Authors: EGBORGE AUSTIN B. M.
Published: May 2006

The seasonal variation in abundance of the phytopiankton groups in the river Oshun before and immediately after the closure of the Asejire dam is described.

The river was dominated by the Bacillariophyceae throughout the period before impoundment but soon after, the Volcocaceae and the Dinophyceae became preponderant at the lake although the diatoms remained dominant at the source. Also, the period of maximum abundance of the diatoms occurred 8 weeks before the other phytoplankton groups attained their maxima in the river.

Correlation coefficient values enumerated by computer revealed the controlling effect of the discharge, transparency and nitrate nitrogen on phytoplankton development in the Oshun.
Ecological studies on Chaoborus (Diptera, Chaoboridae) in Lake George, Uganda
Authors: McGOWAN LESLEY M.
Published: May 2006

(1) Chaoborus anomalus and Chaoborus ceratopogones were found together throughout the year in Lake George, Uganda, the larvae forming 65‐85% by number of the macro‐benthos of the central lake area.

(2) First and second instar larvae were wholly planktonic and third and fourth instar larvae mainly benthic during the day, migrating into the water column at night. A proportion of the third and fourth instar larvae were found in the water column during the day in the centre of the lake where light attenuation was greatest. C. anomalus showed a greater tendency to be benthic than C. ceratopogones.

(3) Planktonic larvae were distributed in dense patches thought to be cohorts resulting from oviposition by swarms of adult females. The maximum density of planktonic larvae recorded was 31.7 × 102/m2 column. Third and fourth instar larvae were more evenly distributed in the benthos of the central lake area, the maximum density recorded was 79.9×102/m2.

(4) First and second instar larvae occurred mainly in the inshore regions, very few were found in the centre of the lake. Oviposition is likely to take place inshore. The patches of planktonic larvae were not stationary. Dispersal of larvae away from the shore may be active or may result from complex oscillations of the water mass produced by storms. In C. ceratopogones the floating egg batches could he carried away from the north shore by currents produced by inflows and prevailing winds.

(5) Adults of C. ceratopogones were more numerous during the rainy seasons than during the dry seasons. A similar, though less marked seasonality was found in the occurrence of C. anomalus adults. The biomass of benthic larvae of C. ceratopo‐gones was estimated at 387.0 mg C/m2 in the dry season, June 1970, and 130 0 mg C/m2 in the rainy season, October 1970. That of C. anomalus was constant at 241.7 and 254.3 mg C/m2 in June and October, 1970 respectively.

(6) No difference was found in the horizontal distribution of the larvae, or in the size and weight attained by the various stages.

(7) Interspecific differences were found in the mean number of eggs per adult female (309, C. anomalus and 224, C. ceratopogones); in the nature ofthe egg batches; n i the morphology of the larval mouthparts and pharyngeal sphincters, as well as i n the vertical distribution of the larvae and seasonal occurrence of the adults. On the basis of these differences the co‐existing species are thought not to be competing for the same resources.
The spatial distribution of desmids in lakes in northern Minnesota, U.S.A.
Authors: BLAND R. D. , BROOK A. J.
Published: May 2006

As a result of studies in certain lakes in northern Minnesota it has been found that the spatial distribution of desmids in them depends especially on the following factors: the constitution, abundance and distribution of the lakes' submerged aquatic flora and the morphometry and consequent patterns of their water circulation. The study has also shown a positive relationship between the size of desmid cells present in the plankton and the extent of water circulation. The latter factor may determine the composition and hence the diversity of lake phytoplankton.
The riddle of the dual expression of IgM and IgD
Authors: Geisberger Roland , Lamers Marinus , Achatz Gernot
Published: May 2006

Signalling through the B cell antigen receptor (BCR) is required for peripheral B lymphocyte maturation, maintenance, activation and silencing. In mature B cells, the antigen receptor normally consists of two isotypes, membrane IgM and IgD (mIgM, mIgD). Although the signals initiated from both isotypes differ in kinetics and intensity, in vivo, the BCR of either isotype seems to be able to compensate for the loss of the other, reflected by the mild phenotypes of mice deficient for mIgM or mIgD. Thus, it is still unclear why mature B cells need expression of mIgD in addition to mIgM. In the current review we suggest that the view that IgD has a simpIy definable function centred around the basic signalling function should be replaced by the assumption that IgD fine tunes humoral responses, modulates B cell selection and homeostasis and thus shapes the B cell repertoire, defining IgD to be a key modulator of the humoral immune response.
Reflections on issues of power in packaged software selection
Authors: Howcroft Debra , Light Ben
Published: May 2006

Abstract.  The adoption of packaged software is becoming increasingly common in a variety of organizations and much of the packaged software literature presents this as a straightforward, linear process based on rationalistic evaluation. This paper applies the framework of power relations developed by Markus and Bjørn‐Andersen to a longitudinal study concerning the adoption of a customer relationship management package in a small organization. This is used to highlight both overt and covert power issues within the selection and procurement of the product and illustrate the interplay of power between senior management, information technology (IT) managers, IT vendors and consultants and end‐users. The paper contributes to the growing body of literature on packaged software and also to our understanding of how power is deeply embedded within the surrounding processes.
Population dynamics in wild boar Sus scrofa: ecology, elasticity of growth rate and implications for the management of pulsed resource consumers
Authors: BIEBER CLAUDIA , RUF THOMAS
Published: May 2006

In terrestrial ecosystems many species show large population fluctuations caused by pulsed resources, such as mast seeding. A prime example of a mammal strongly affected by mast seeding of trees is the wild boar Sus scrofa, a species that has become a pest in many parts of the world. We investigated the population dynamics of wild boar to assist the development of effective management strategies for this species and possibly for other pulsed resource consumers.

We analysed published vital rates of wild boar using Leslie matrix projection models and elasticity analysis. Models were based on vital rates of animals under poor, intermediate and good environmental conditions, which represent combinations of differences in food availability (particularly mast of beech Fagus sylvatica and/or oak Quercus spp.) and winter climate.

Interestingly, we observed a crossover in the ranking of elasticities (e; the relative impact of each vital rate on population growth rate λ) when comparing different conditions. While the elasticity of λ to adult survival was highest in poor environments [e(Padult) = 0·36, e(Pjuvenile) = 0·22], the elasticity of λ to juvenile survival was highest under good conditions [e(Padult) = 0·16, e(Pjuvenile) = 0·28]. Thus juvenile survival becomes increasingly important for population growth as habitat conditions improve.

Our analysis of empirical beech mast records gave some indication of an increase of full masts over the last few decades. Modelling different beech mast scenarios showed that an increase in full mast frequency will lead to a rapid increase in λ. The availability of alternative food resources, namely agricultural crops, may also contribute to an expansion of wild boar populations.

Synthesis and applications. We suggest that, whenever possible, management strategies should be based on separate elasticity analyses for different environmental conditions, especially for species dependent on pulsed resources. For wild boar we suggest the following principal management strategies to stop further population increases: (i) supplementary feeding should be strictly avoided; (ii) under good environmental conditions, reducing juvenile survival will have the largest effect on λ, whereas strong hunting pressure on adult females will lead to most effective population control in years with poor conditions.
Designing occupancy studies: general advice and allocating survey effort
Authors: MACKENZIE DARRYL I. , ROYLE J. ANDREW
Published: May 2006

The fraction of sampling units in a landscape where a target species is present (occupancy) is an extensively used concept in ecology. Yet in many applications the species will not always be detected in a sampling unit even when present, resulting in biased estimates of occupancy. Given that sampling units are surveyed repeatedly within a relatively short timeframe, a number of similar methods have now been developed to provide unbiased occupancy estimates. However, practical guidance on the efficient design of occupancy studies has been lacking.

In this paper we comment on a number of general issues related to designing occupancy studies, including the need for clear objectives that are explicitly linked to science or management, selection of sampling units, timing of repeat surveys and allocation of survey effort. Advice on the number of repeat surveys per sampling unit is considered in terms of the variance of the occupancy estimator, for three possible study designs.

We recommend that sampling units should be surveyed a minimum of three times when detection probability is high (> 0·5 survey−1), unless a removal design is used.

We found that an optimal removal design will generally be the most efficient, but we suggest it may be less robust to assumption violations than a standard design.

Our results suggest that for a rare species it is more efficient to survey more sampling units less intensively, while for a common species fewer sampling units should be surveyed more intensively.

Synthesis and applications. Reliable inferences can only result from quality data. To make the best use of logistical resources, study objectives must be clearly defined; sampling units must be selected, and repeated surveys timed appropriately; and a sufficient number of repeated surveys must be conducted. Failure to do so may compromise the integrity of the study. The guidance given here on study design issues is particularly applicable to studies of species occurrence and distribution, habitat selection and modelling, metapopulation studies and monitoring programmes.
Maternal origin of a novel C‐terminal truncation mutation in CDKL5 causing a severe atypical form of Rett syndrome
Authors: Nectoux J , Heron D , Tallot M , Chelly J , Bienvenu T
Published: May 2006

The CDKL5 gene has been implicated in infantile spasms and more recently in a Rett syndrome‐like phenotype. We report a case of a young girl presenting generalized convulsions at 10 days of life. Subsequent mutation analysis by denaturing high‐performance liquid chromatography of MECP2 and CDKL5 genes revealed heterozygosity for a c.47_48insAGG insertion in exon 1 of MECP2 and heterozygosity for a new nonsense mutation p.Q834X and a new missense variant p.V999M in the CDKL5 gene. Co‐segregation analysis showed that the nonsense mutation was a de novo mutation and that the insertion and the missense variant were also found in the asymptomatic mother. In the absence of skewed X inactivation in the mother, it is likely that these last two variants are not pathogenic. Reverse transcription‐polymerase chain reaction from lymphoblastoid cells of the patient showed only the transcript without the nonsense and missense variations suggesting decreased stability of mature mRNA by nonsense‐mediated decay. These data also suggest an occurrence of the de novo mutation in maternal germ line cells. Moreover, this report reinforces the observation that the CDKL5 phenotype overlaps with Rett syndrome and that CDKL5 gene analysis is recommended in females with a seizure disorder commencing in the first weeks of life.
Use of cytokine polymorphisms and Epstein–Barr virus viral load to predict development of post‐transplant lymphoproliferative disorder in paediatric liver transplant recipients
Authors: Lee Timothy C. , Savoldo Barbara , Barshes Neal R. , Rooney Cliona M. , Heslop Helen E. , Gee Adrian P. , Caldwell Yvette , Scott Jaymee D. , Goss John A.
Published: May 2006

Abstract:  Objective:  Currently there are no tests to accurately identify paediatric liver transplant patients at risk for post‐transplant lymphoproliferative disorder (PTLD). Herein we describe the use of cytokine polymorphisms and real‐time quantitative polymerase chain reaction (qPCR) Epstein–Barr virus (EBV) viral load to identify patients at risk for PTLD development.

Methods:  Between 2001 and 2004, approximately 1047 patient samples were collected for qPCR for EBV in 59 patients. EBV viral load was reported in three groups: low EBV (<4 000 copies/μg DNA), high EBV/no PTLD (>4000 copies/μg DNA) and biopsy‐proven PTLD. All 59 patients also had cytokine polymorphism genotyping performed for six cytokine polymorphisms (transforming growth factor (TGF)‐β, tumor necrosis factor (TNF)‐α, interleukins (IL)‐6, IL‐10, IL‐2, and interferon (IFN)‐γ) from DNA isolated from peripheral blood mononuclear cells. Positive predictive value (PPV) and negative predictive value (NPV) were calculated using qPCR and cytokine polymorphism results. Data are reported as a mean±standard error of the mean.

Results:  There were 35 males and 24 females with a mean follow‐up of 34.9 months. EBV viral load had a PPV and NPV of 29 and 95%, respectively. The low IFN‐γ (A/A) polymorphism was found to be present in 4/6 PTLD patients (67%) and only 17/53 (33%) non‐PTLD patients. When the low A/A IFN‐γ polymorphism was combined with EBV viral load for prediction of PTLD, PPV and NPV were 57 and 93%, respectively.

Discussion:  Use of cytokine genotyping in conjunction with qPCR for EBV viral load can significantly improve the predictive value of diagnostic tests for identification of patients at high risk for PTLD.
Polyomavirus‐associated nephropathy: update in diagnosis
Authors: Drachenberg C.B. , Papadimitriou J.C.
Published: May 2006

Abstract: The histological diagnosis of BK or JC polyomavirus allograft nephritis (PVAN) requires evaluation of a renal biopsy with demonstration of the polyomavirus cytopathic changes and confirmation with an ancillary technique such as immunohistochemistry. Three histological patterns of PVAN (A, B, and C) are identified in renal biopsies. Pattern A corresponds to the early disease, whereas patterns B and C identify intermediate and very advanced histological changes, respectively. The histological pattern found in the first biopsy correlates with graft outcome. Because PVAN affects the kidney in a random, multifocal manner, a negative biopsy does not rule out the disease. Patients with BK PVAN characteristically have high levels of BK viruria and viremia. Although the cutoff values of viral loads have not been fully determined, there is general agreement that BK viruria of >107/mL and BK viremia of >104 are typical of patients with a biopsy showing BK PVAN. Prospective evaluation of viruria with urine cytology (decoy cells) and/or quantitative polymerase chain reaction can aid in the identification of patients at risk for developing PVAN. In addition to histological evaluation, viremia has emerged as the most specific test for the diagnosis of BK PVAN. JC PVAN is very infrequent in comparison with BK PVAN, but is also characterized by large viruria (>104). On the other hand, JC viremia appears to be lower, in the order of 103/mL. The inflammatory changes in PVAN need further characterization. Currently, there are no tools to differentiate acute cellular rejection from viral specific T‐cell response.
A prospective cross‐sectional study of BK virus infection in non‐renal solid organ transplant recipients with chronic renal dysfunction
Authors: Barton T.D. , Blumberg E.A. , Doyle A. , Ahya V.N. , Ferrenberg J.M. , Brozena S.C. , Limaye A.P.
Published: May 2006

Abstract: Background: Polyomavirus (primarily BK virus [BKV]) infection is an important cause of chronic renal dysfunction in renal transplant recipients, but its possible contribution to chronic renal dysfunction in non‐renal solid organ transplant (NRSOT) recipients has not been fully explored.

Methods: We performed a prospective, cross‐sectional study of consecutive NRSOT recipients with unexplained chronic renal dysfunction of at least a 3 months duration. Medical records were reviewed, and polymerase chain reaction was used to amplify BKV‐specific sequences from serum and urine samples. The potential associations between various demographic and transplant variables and BKV infection were assessed.

Results: Thirty‐four consecutive NRSOT recipients (23 lung, 8 liver, 2 heart, 1 heart–lung) with chronic renal dysfunction were enrolled at a median of 3.5 years (range 0.3–12.5 years) post transplantation. Five of the 34 (15%) patients had BKV viruria (range 1040–1.8 × 106 copies/mL), but none had BKV viremia. BK viruria was associated with mycophenolate mofetil use (5 of 19 [26%] vs. 0 of 15, P=0.03) and a history of cytomegalovirus disease (3 of 4 [75%] vs. 2 of 30 [7%], P<0.01). However, the mean estimated creatinine clearance was similar in patients with or without BKV viruria (49 vs. 47 mL/min).

Conclusions: BKV viruria was present in a proportion of NRSOT patients with otherwise unexplained chronic renal dysfunction. The possibility that BKV infection might contribute to chronic renal dysfunction in this setting warrants further investigation.
BK virus nephropathy in a heart transplant recipient: case report and review of the literature
Authors: Barber C.E.H. , Hewlett T.J.C. , Geldenhuys L. , Kiberd B.A. , Acott P.D. , Hatchette T.F.
Published: May 2006

Abstract: The human polyomavirus BK virus (BKV) remains latent in the urinary tract and may be reactivated in immunocompromised states. BKV is noted to be the etiologic agent of polyomavirus‐associated nephropathy (PVAN), which is a significant cause of allograft failure in renal transplant patients. Renal dysfunction following non‐renal solid organ transplantation is common and is typically attributed to drug toxicity or patient comorbidities. In this article we describe a case of PVAN in the native kidneys of a heart transplant recipient and review the literature. Although this is only the fourth case reported, BKV nephropathy should be considered in the differential diagnosis of new renal failure following non‐kidney solid organ transplantation, as early diagnosis of PVAN is necessary to prevent irreversible renal damage.