bluuebunny/crossref_metadata_2025_split huggingface dataset:
Complex interactions of light, nutrients and consumer density in a stream periphyton–grazer (tailed frog tadpoles) system
Authors: MALLORY MICHELINE A. , RICHARDSON JOHN S. 
Published: November 2005

Summary

Consumer–resource interactions may be modified by complex environmental interactions. We experimentally manipulated light, nutrients, consumer density (tailed frog tadpoles − Ascaphus truei), and enclosure sizes in two small and steep streams of coastal British Columbia, Canada. We used flow‐through, screened enclosures in situ as experimental units and measured the responses of algae (as chlorophyll a), periphyton (ash‐free dry mass) and growth rates of tailed frog tadpoles using a factorial model design.
Light exerted a strong, positive effect on algae and periphyton production with 30–40% higher biomass over shaded treatments, and a 14% higher relative growth rate of tadpoles. Nutrient additions had little to no effect on any measure, alone or in interaction with other factors. Tadpole growth, algae and periphyton standing crop were significantly reduced along a gradient of increasing consumer density. Enclosure size had a large effect on all three measures.
Algae and periphyton production were under simultaneous top‐down (tadpole grazing) and bottom‐up control (light); however, the relative importance of these effects was stream‐dependent. At Klondike Creek algae and periphyton production was influenced primarily by grazing, and by light levels at Dipper Creek.
Mean growth rate of tadpoles was on average 45% higher at Klondike Creek than at Dipper Creek. Most of the effects of the abiotic treatments and consumer density interacted statistically with stream identity, despite these streams being very similar and < 6 km apart. The strong effect of stream on the outcomes may be a consequence of large temperature differences.
This study demonstrated that light, consumer density, stream, enclosure size and nutrients alone and in combination affected algae and periphyton production, and grazer growth rate. While the interactions between consumer and resources were tightly coupled, the relative importance of the driving factors varied significantly between nearby streams.
Helping enhances multiple components of reproductive success in the cooperatively breeding apostlebird
Authors: WOXVOLD IAIN A. , MAGRATH MICHAEL J. L. 
Published: November 2005

Summary

We examined the influence of helpers on reproductive success in the apostlebird using data gathered over three breeding seasons (116 nests, 34 breeding groups). Initially, annual productivity and individual components of reproductive success were examined in relation to group size (two to 17 birds). The effect of helping per se was then examined in a reduced data set by comparing (a) the predictive power of group size and actual helper numbers, and/or (b) the productivity of groups that changed in size between nests or seasons.
Group size was positively and linearly related to annual fledgling production and the number of offspring that survived to the following season. This was attributed to the presence of helpers, as the number of birds that fed nestlings, but not group size, was significantly related to annual fledging success. Neither group size nor helper number influenced fledgling survival over the subsequent winter.
The probability of re‐nesting after a successful first brood increased with group size. Among double‐brooded groups, the interval between nests was inversely related to group size.
Clutch size increased linearly with group size among groups with two to five birds, but was not related to group size among larger groups. A matched comparison of groups that changed size between years further suggests that clutch size was facultatively adjusted to group size, a phenomenon rarely reported in species with non‐breeding helpers.
Hatching success was not related to group size or the number of birds participating in incubation.
The number of birds provisioning the brood was a better predictor of feeding rate per chick than group size, and was significantly and inversely related to the incidence of nestling starvation. However, there was no relationship between group size and fledgling body mass.
Fledging success per brood increased linearly among groups with three to five members. The only case of pair‐breeding was unsuccessful, suggesting that this species is one of only a few birds that may be obligately cooperative.
We found no evidence that helpers influenced the likelihood of nest predation, or the probability of group members surviving to the following season.
Weather packages: finding the right scale and composition of climate in ecology
Authors: STENSETH NILS CHR. , MYSTERUD ATLE 
Published: November 2005

Summary

Animals are affected by local weather variables such as temperature, rainfall and snow. However, large‐scale climate indices such as the North Atlantic Oscillation (NAO) often outperform local weather variables when it comes to explain climate‐related variation in life history traits or animal numbers.
In a recent paper, Hallet et al. (2004, Nature, 430, 71–75) document convincingly why this may happen. In this perspective, we identify from the literature three mechanisms why this is so: (1) the time window; (2) the spatial window; and (3) the weather composition component of climate.
Such an understanding may be used to derive even better ‘weather packages’ than the NAO.
Root herbivore effects on above‐ground herbivore, parasitoid and hyperparasitoid performance via changes in plant quality
Authors: SOLER ROXINA , BEZEMER T. MARTIJN , VAN DER PUTTEN WIM H. , VET LOUISE E. M. , HARVEY JEFFREY A. 
Published: November 2005

Summary

Plants and insects are part of a complex multitrophic environment, in which they closely interact. However, most of the studies have been focused mainly on bi‐tritrophic above‐ground subsystems, hindering our understanding of the processes that affect multitrophic interactions in a more realistic framework.
We studied whether root herbivory by the fly Delia radicum can influence the development of the leaf feeder Pieris brassicae, its parasitoid Cotesia glomerata and its hyperparasitoid Lysibia nana, through changes in primary and secondary plant compounds.
In the presence of root herbivory, the development time of the leaf herbivore and the parasitoid significantly increased, and the adult size of the parasitoid and the hyperparasitoid were significantly reduced. The effects were stronger at low root fly densities than at high densities.
Higher glucosinolate (sinigrin) levels were recorded in plants exposed to below‐ground herbivory, suggesting that the reduced performance of the above‐ground insects was via reduced plant quality. Sinigrin contents were highest in plants exposed to low root fly densities, intermediate in plants exposed to high root fly densities and lowest in plants that were not exposed to root herbivory.
Our results show, for the first time, that root herbivory via changes in plant quality can reduce the performance of an above‐ground multitrophic level food chain. This underlines the importance of integrating a broader range of above‐ and below‐ground organisms to facilitate a better understanding of complex multitrophic interactions and interrelationships.
Rapid response of macroinvertebrates to drainage management of shallow connected lakes
Authors: VAN DE MEUTTER FRANK , STOKS ROBBY , DE MEESTER LUC 
Published: November 2005

Summary

Shallow lakes throughout the world are subject to drainage, either for fish harvesting or lake restoration. Lake drainage of fish lakes is known to improve macrophyte and zooplankton diversity, but the effect on the macroinvertebrate community is poorly known.
In the present study, we investigated temporal trends in the macroinvertebrate community following drainage of six shallow connected lakes. Diversity increased for all macroinvertebrates (family level). Recolonization of the lakes occurred within the first year after the drainage and was supplemented with a set of species that were previously rare or did not occur in the lakes. Changes in the abiotic conditions of the lakes were small and transient, except for the decline in fish. The rapid recolonization by the species occurring before drainage is attributed to the high connectivity of our system. The appearance of supplementary species may relate to lowered fish predation, suggesting that fish were a dominant factor in shaping the communities.
Synthesis and applications. Lake drainage has a positive effect on the diversity and richness of macroinvertebrates in shallow connected lakes. This positive effect may be due to a decline in fish predation following lake drainage in combination with a high rate of recolonization among others via connections to non‐drained lakes. Lake drainage, therefore, is probably the most cost‐effective lake restoration tool in shallow connected lakes. Other restoration tools may be preferable in isolated lakes where recolonization is constrained.
Fully automated intensity compensation for confocal microscopic images
Authors: WU H.‐X. , JI L. 
Published: November 2005

SummaryOne well‐recognized problem in three‐dimensional (3D) confocal microscopic images is that the intensities in deeper slices are generally weaker than those in shallower slices. The loss of intensity with depth hampers both qualitative observation and quantitative measurement of specimens. Two major types of methods exist to compensate for this intensity loss: the first is based on the geometrical optics inside the specimen, and the second applies an empirical parametric intensity decay function (IDF) of depth. A common feature shared by both methods is that they are parameter‐dependent. However, for the optics‐based method there are as yet no fully automated parameter‐setting approaches; and for the IDF method the traditional profile‐fitting approach cannot provide proper parameters if the presumed IDF model does not match the experimental intensity–depth profile of the 3D image. In this paper, we propose a novel maximum‐entropy (ME) approach to fully automated parameter‐setting. In principle the ME approach is suitable for any compensation method as long as it is parameter‐dependent. The basic assumption is that without intensity loss an ideal 3D image should be generally homogeneous with respect to depth and this axial homogeneity can be represented by the entropy of a normalized intensity–depth profile. Experiments on real confocal images showed that such a profile was consistent with visual evaluation of axial intensity homogeneity and that the ME approach could provide proper parameters for both compensation methods mentioned above. Moreover, for the IDF method, experiments on both real and simulated data showed that the ME approach could provide more precise parameters than with traditional profile‐fitting. The Appendix provides a proof that under certain conditions the global maximization of the profile‐entropy is guaranteed.
In vivo assessment of emphysema in mice by high resolution X‐ray microtomography
Authors: POSTNOV A. A. , MEURRENS K. , WEILER H. , VAN DYCK D. , XU H. , TERPSTRA P. , DE CLERCK N. M. 
Published: November 2005

AbstractHigh resolution X‐ray microtomography (micro‐CT) was used for the detection of emphysema in live mice. Emphysema was induced in C57BL/6 J mice by intratracheal instillation of different amounts of porcine pancreatic elastase. This emphysema could be clearly detected by micro‐CT seven weeks post‐treatment: analysis of the whole data set of virtual cross‐sections showed the presence of a dose‐dependent level of emphysema.
Genotypic difference in canopy diffusive conductance measured by a new remote‐sensing method and its association with the difference in rice yield potential
Authors: HORIE TAKESHI , MATSUURA SHOJI , TAKAI TOSHIYUKI , KUWASAKI KOUHEI , OHSUMI AKIHIRO , SHIRAIWA TATSUHIKO 
Published: November 2005

ABSTRACTThere have been few practical ways of measuring physiological determinants of rice yield. Rapid evaluation of yield determination traits may expedite breeding of high‐yielding rice. Here, we report a new remote‐sensing technique for the evaluation of canopy ecophysiological status under field conditions developed based on simultaneous measurements of sunlit and suddenly shaded canopy temperatures. This technique has the advantage of instantaneous estimation of aerodynamic resistance (ra) and canopy diffusive resistance (rc) without measuring wind velocity. Canopy diffusive conductance (1 / rc) estimated by the remote sensing method was closely related to leaf stomatal conductance (gs) measured with a portable gas exchange system. This result supported the validity of this new method for quantitative estimation of canopy physiological characteristics. Significant genotypic differences were obtained in canopy–air temperature difference (Tc − Ta), rc and 1 / rc during the 2‐week period preceding full heading for two years, and 1 / rc was highly correlated with crop growth rate (CGR), which was closely related to the final yield. These results suggest that 1 / rc can be an effective criterion for the selection of high‐yielding rice genotypes, and the remote sensing technique proposed here can be a powerful tool for the rapid evaluation of 1 / rc under field conditions.
Growth and gonad production of the sea urchin Hemicentrotus pulcherrimus in the fucoid bed and algal turf in northern Japan
Authors: Agatsuma Yukio , Nakabayashi Nobuyasu , Miura Nobuaki , Taniguchi Kazuya 
Published: November 2005

AbstractTo clarify the differences in the growth and gonad size of the sea urchin Hemicentrotus pulcherrimus among algal sere, the study was conducted in June and July, and September 1998 at three fucoid beds in Oga and at three algal turfs in Hachimori, Akita Prefecture in northern Japan. The most rapid growth was observed in a large perennial fucoid bed at the climax stage. Growth in a small perennial Chondrus ocellatus‐dominated bed in algal turfs in the seral stage was then high. The slowest growth was observed in the small perennial Dictyopteris divaricata‐ and Laurencia spp.‐dominated beds which are known to possess chemicals which act as feeding deterrents against the sea urchins. The gonad index (gonad wet weight × 100/body wet weight) at a fucoid bed was high where standing crops exceeded 3 kg·m−2. The gonad index in the Laurencia bed was lower than those at fucoid beds. These results suggest that growth and gonad production are affected by algal sere and differ among species of small perennial algae in the seral stage with or without chemical defense.
Ecological implications of biomass and morphotype variations of bacterioplankton: an example in a coastal zone of the Northern Adriatic Sea (Mediterranean)
Authors: La Ferla Rosabruna , Leonardi Marcella 
Published: November 2005

AbstractThis study had the objective of quantifying the variability in abundance, cell volume, morphology and C content of a natural bacterioplankton community in a coastal zone of the North Adriatic Sea during two periods (February and June) of two consequent years (1996 and 1997). We used epifluorescence microscopy with Acridine Orange staining procedures and a microphotographic technique. Low variability in bacterial abundance (range 0.3–3.1 × 105 cells ml−1) occurred between summer and winter periods. Conversely, the cell volume and the calculated carbon content changed greatly with warm and cold periods (ranges: 0.015–0.303 μm3 and 5.83–42.17 fg C cell−1, respectively). Elongated bacteria were dominant while coccoid cells prevailed only in February 1997. Biomass showed high variability (range 0.12–10.21 μg C l−1) whilst the abundance did not show noticeable differences among the sampling periods. As a consequence, quantification of bacterial biomass based solely on cell abundance must be considered with caution because the true biomass could depend on variability in cell volumes and morphotypes.
Hydrozoa (Cnidaria) symbiotic with Porifera: a review
Authors: Puce S. , Calcinai B. , Bavestrello G. , Cerrano C. , Gravili C. , Boero F. 
Published: November 2005

AbstractMany hydroids are symbiotic with other organisms. Sponges, because of their complex canal system and their filter‐feeding activity inducing a continuous water flow, are used by numerous species as either exclusive or facultative substrata. The associated hydroid fauna thriving on or inside sponges shows a wide range of relationships with their hosts. Hydroids may be simply epibiotic on sponges, their stolons running on the host surface. Alternatively, the stolons may grow inside the sponge body, the polyps emerging from the sponge surface, having also the possibility of retraction inside the sponge tissue. Finally, stolons and branches may develop deeply inside the sponge body, producing a skeletal network for sponge growth. This paper reviews the described relationships of hydrozoans symbiotic with sponges and reports new observations.
Isolation and characterization of novel testis‐specific genes from mouse pachytene spermatocyte‐enriched cDNA library
Authors: IJIRI TAKASHI W , NAGASE TAKAHIRO , MATSUDA YOICHI 
Published: November 2005

Background and Aims:  Isolation and analysis of spermatogenesis‐specific genes provide important information for elucidating the mechanisms of human infertility. The aim of the present study was to suggest an effective strategy for the comprehensive isolation of novel genes associated with spermatogenesis in mice.Methods:  To isolate novel testis‐specific genes associated with meiosis in mice, we constructed a mouse pachytene spermatocyte‐enriched cDNA library by the centrifugal elutriation method, and sequenced 120 cDNA clones isolated from the cDNA library. A basic local alignment search tool (BLAST) search was carried out on the cDNA clones to find novel genes and then a detailed expression analysis was carried out by Northern blot hybridization and in situ hybridization.Results:  Of the 120 cDNA clones, 35 clones (29%) were novel and 18 clones (15%) were expressed only in the testis. The expression patterns of seven novel testis‐specific clones were examined on the testis sections. Three clones were expressed in spermatocytes and other germ cells, and two clones were exclusively expressed in spermatocytes. Amino acid sequences of seven novel testis‐specific clones were deduced from their nucleotide sequences, suggesting that two of them contain known functional repeat structures.Conclusions:  This method provides a powerful strategy to isolate novel testis‐specific genes efficiently. (Reprod Med Biol 2005; 4: 231–237)
Analysis of the first genome fragment from the marine sponge‐associated, novel candidate phylum Poribacteria by environmental genomics
Authors: Fieseler Lars , Quaiser Achim , Schleper Christa , Hentschel Ute 
Published: November 2005

SummaryThe novel candidate phylum Poribacteria is specifically associated with several marine demosponge genera. Because no representatives of Poribacteria have been cultivated, an environmental genomic approach was used to gain insights into genomic properties and possibly physiological/functional features of this elusive candidate division. In a large‐insert library harbouring an estimated 1.1 Gb of microbial community DNA from Aplysina aerophoba, a Poribacteria‐positive 16S rRNA gene locus was identified. Sequencing and sequence annotation of the 39 kb size insert revealed 27 open reading frames (ORFs) and two genes for stable RNAs. The fragment exhibited an overall G+C content of 50.5% and a coding density of 86.1%. The 16S rRNA gene was unlinked from a conventional rrn operon. Its flanking regions did not show any synteny to other 16S rRNA encoding loci from microorganisms with unlinked rrn operons. Two of the predicted hypothetical proteins were highly similar to homologues from Rhodopirellula baltica. Furthermore, a novel kind of molybdenum containing oxidoreductase was predicted as well as a series of eight ORFs encoding for unusual transporters, channel or pore forming proteins. This environmental genomics approach provides, for the first time, genomic and, by inference, functional information on the so far uncultivated, sponge‐associated candidate division Poribacteria.
Replicability of dominant bacterial populations after long‐term surfactant‐enrichment in lab‐scale activated sludge
Authors: Lozada Mariana , Figuerola Eva L. M. , Itria Raúl F. , Erijman Leonardo 
Published: November 2005

SummaryBacterial communities were examined in replicate lab‐scale activated sludge reactors after a period of several months of enrichment with non‐ionic nonylphenol ethoxylate (NPE) surfactants. Four sequential batch reactors were fed with synthetic sewage, two of which received additionally NPE. Small subunit rDNA‐derived denaturing gel gradient electrophoresis (DGGE) profiles and 16S rDNA clone libraries were dominated by clones of Gammaproteobacteria class. Sequences of the other codominant rDNA phylotypes observed only in DGGE from NPE‐amended reactors were, respectively, associated with the Group III of the Acidobacteria phylum. Intriguingly, 16S rRNA content from abundant Gammaproteobacteria cells was unexpectedly low. In addition to Acidobacteria, rRNA‐derived DGGE profiles were dominated by members of the order Burkholderiales (of the Betaproteobacteria) and of the genus Sphingomonas (a member of the Alphaproteobacteria). Specific oligonucleotide probes for the selected ribotypes were designed and applied for quantitative real time polymerase chain reaction and fluorescence in situ hybridization, confirming their dominance in treated reactors. The parallel abundance of unique phylotypes in replicate reactors implies a distinctive selection of dominant organisms, which are better adapted to specialized niches in the highly selective environment.
Quantitative reverse transcription polymerase chain reaction analysis of Vibrio cholerae cells entering the viable but non‐culturable state and starvation in response to cold shock
Authors: González‐Escalona Narjol , Fey Axel , Höfle Manfred G. , Espejo Romilio T. , A. Guzmán Carlos 
Published: November 2005

SummaryWe performed a comparative analysis of the Vibrio cholerae strain El Tor 3083 entering the viable but non‐culturable (VBNC) state and starvation after incubation in artificial seawater (ASW) at 4 and 15°C respectively. To this end, we determined bacterial culturability and membrane integrity, as well as the cellular levels of 16S rRNA and mRNA for the tuf, rpoS and relA genes, which were assessed by real‐time quantitative reverse transcription polymerase chain reaction (Q‐RT‐PCR). Bacterial cells entering the VBNC state showed a 154, 5.1 × 103, 24‐ and 23‐fold reduction in the number of copies of 16S rRNA and mRNA for tuf, rpoS and relA, in comparison to exponentially growing cells. The differences were less striking between cells in the VBNC and starvation states. The mRNA for relA was selectively increased in VBNC cells (3.2‐folds), whereas a 3.9‐fold reduction was observed for 16S rRNA. The obtained results confirmed that key activities of the cellular metabolism (i.e. tuf representing protein synthesis, and relA or rpoS stress response) were still detected in bacteria entering the VBNC state and starvation. These data suggest that the new Q‐RT‐PCR methodology, based on the selected RNA targets, could be successfully exploited for the identification (rRNA) of V. cholerae and assessment of its metabolic activity (tuf, rpoS, relA mRNA) in environmental samples.