ALBERT

Notes: Abstract – Astroblepus ubidiai (Actinopterygii; Siluriformes), which is the only native fish of the highlands of the Province of Imbabura, Ecuador, was abundant in the past in the Imbakucha watershed and adjacent drainages but currently it is restricted to a few isolated refuges. Population viability analysis (PVA) was used to detect critical aspects in the ecology and conservation biology of this unique fish. The annual population growth rate (λ) was estimated for six remnant populations of this Andean catfish using a deterministic matrix population model. Sensitivity and elasticity analyses complemented the PVA by providing constructive insights into vital rates affecting projections and extinction probabilities. Positive population growth rates were found in all the study populations. The high contributions of juvenile survival to the variance of λ and its high elasticity indicated that A. ubidiai population dynamics are highly sensitive to the transition values of this vital rate, which can promptly respond to management or antagonistic perturbations. Allowing fish to survive until the age of first reproduction and permitting the successful reproduction of these individuals will facilitate positive population growth rates, however the very small areas of occupancy, small extent of occurrence and severe fragmentation may still contribute to the extinction risk.

Notes: Abstract –  In past dietary studies kokanee Oncorhynchus nerka were prominent in the diet of Pend Oreille Lake's large piscivores: native bull trout Salvelinus confluentus, cutthroat trout O. clarki and northern pikeminnow Ptychocheilus oregonensis, and introduced lake trout S. namaycush and Kamloops rainbow trout O. mykiss gairdneri. However, kokanee have declined to 10–20% of their former abundance. We therefore initiated this study to understand current predation demands on kokanee and diet overlap among piscivores, using gut content samples and analysis of stable nitrogen (δ15N) and carbon (δ13C) isotopes from the lake's fish and invertebrate community. In gut content samples, kokanee were the main prey item of large [i.e., ≥400 mm total length (TL)] bull and lake trout; a conclusion that was affirmed by stable isotope analysis. Rainbow trout 〉500 mm TL consumed mostly kokanee, thus there was a high degree of diet overlap among large bull, lake and rainbow trout. Small (i.e., 〈400 mm TL) rainbow and cutthroat trout diets overlapped, and were composed mostly of littoral benthic invertebrates. However, gut content and stable isotope analysis did not accord for 400–500 mm TL rainbow trout, small lake trout, and large cutthroat trout. In these instances, a linear mixing model using stable isotope results predicted kokanee consumption for each species, but no kokanee were identified in rainbow or lake trout gut content. Gut content and stable isotope analysis of native northern pikeminnow indicated a diet of mostly littoral benthic invertebrates at smaller (100–150 mm TL) lengths, with kokanee becoming more prominent in the diet of individuals 〉300 mm TL. Percent of kokanee in the diet of northern pikeminnow has declined from a prior study; otherwise piscivore diets have apparently remained unchanged. In this study, judgments as to the feeding of some piscvores, based on gut content alone, would be tenuous because of small sample sizes, but stable isotope analysis provided an efficient means for confirming diets.

Notes: Abstract – Positively phototactic vendace larvae may be vulnerable to enhanced springtime UV levels unless they are able to avoid them. Experimental results, however, suggested that UV avoidance can exist. In this study field data from eight Finnish lakes with different characteristics were analysed. The aim of the study was to determine whether vendace larvae stayed deeper in the water column during sunny than during cloudy periods because thick cloud cover considerably reduces UV irradiance. In addition, avoidance behaviour of larvae was studied in acrylic tubes placed in a lake and under laboratory conditions. The avoidance of high UV-B exposure existed both in the littoral and pelagic zone of the lakes and in laboratory with low UV attenuation. In the lakes with high UV attenuation, avoidance behaviour did not exist. Vendace larvae may use visible light as an indirect indicator of harmful UV-B irradiance.

Notes: Abstract –  The objectives of this study were, first, to assess the usefulness of otolith microstructure analysis to examine winter size-selective mortality of young-of-the-year (YOY) Atlantic salmon and, secondly, to validate various hypotheses relating to the dynamics of two populations with different winter survival. By examining otolith microstructure, we back-calculated body size at hatching and at emergence of YOY salmon sampled in fall 2000 and in early summer 2001 on the Petite Cascapédia River and the Bonaventure River (Québec, Canada). The results of the study did not reveal any size-selective mortality of YOY salmon in the Petite Cascapédia River, while in the Bonaventure River, size-selective mortality of the smaller individuals of the cohort was detected. This case study allowed not only a better comprehension of the population dynamics of those rivers but demonstrated the usefulness of otolith analysis to detect winter size-selective mortality under a natural environment.

Notes: Abstract –  Three sympatric whitefish (Coregonus lavaretus (L.)) forms, one being pelagic and two benthic, segregate available habitat and food resources in subarctic Lake Muddusjärvi, northern Finland. Zooplankton availability in the lake, food composition, diet-overlap and growth of densely rakered (DR) whitefish were examined during June to September to explore the reasons for the small individual size of the pelagic form. DR whitefish used zooplankton as main food item and prey selection followed zooplankton species density proportions in the lake. Zooplankton density and water temperature was highest in July–August. The average lengths of Bosmina spp., Daphnia spp., Calanoida and Cyclopoida in DR whitefish stomach were higher than in zooplankton sample during June–September, except Calanoida in June. Diet-overlap between DR whitefish age groups was high at all months indicating intercohort resource competition. DR whitefish reached sexual maturity at 3 years of age and at the length of 12 cm, after which somatic growth almost ceased. Reason for the small average size and slow growth of DR whitefish were connected to high diet-overlap between age groups and early sexual maturation.

Notes: Abstract –  Along a stream, we investigated whether the abundance of stone loach (Barbatula barbatula, L.) was related to the presence of brown trout (Salmo trutta, L.) and instream habitat variables. First, a field survey was carried out where different habitat variables and the densities of both species were quantified and subjected to principal components analysis. Then the abundance of stone loach was related to the scores of the retained axes (eigenvalues 〉1). The abundance of stone loach was positively correlated to substrate particle size, amount of shade, temperature, discharge and current velocity, but negatively correlated to brown trout abundance. Secondly, a month-long field enclosure experiment in a stream was performed to test for any negative effects of brown trout on stone loach growth. Four treatments were used: intraspecific competition (stone loach at double density), interspecific competition (stone loach + small trout), predation (stone loach + large trout) and a control (stone loach alone). The results showed that large trout tended to have negative effects on final stone loach biomass. The absence of a negative effect of large trout on resource density suggests that nonlethal effects rather than resource competition caused this trend.

Notes: Abstract –  This study aimed to evaluate otter predation on stocked trout. Large hatchery-reared trout (16–30 cm) were stocked into two Danish rivers with different fish populations. Otter diet before and after trout stocking was determined by analysing 685 spraints, collected regularly during the 35-day study period. Fish composition in the rivers before stocking was assessed by electrofishing. In River Trend, a typical trout river, the proportion of trout in the otter diet increased from 8% before stocking to 33% a few days after stocking. Moreover, trout lengths in the diet changed significantly towards the lengths of stocked trout, indicating that newly stocked trout were preferred to wild trout. In River Skals, dominated by cyprinids, there was no change in otter diet after stocking of hatchery trout, i.e., these were ignored by otter. Otter predation should be taken into account together with fish and bird predation, when stocking is used as a measure for conserving endangered salmonid populations.

Notes: Abstract – During 6 November to 24 December 2000, 23 tigerfish [(Hydrocynus vittatus), 30–54 cm] were tagged with radio transmitters in the Zambezi River (Namibia) to record habitat utilisation during low, rising and high water levels. The fish were tracked, on average, every fourth day during 23 November to 18 May. Two movement patterns were detected. Approximately 50% of the fish moved 〈1000 m among tracking surveys, staying within ‘defined’ home ranges. The remaining fish showed consistent site fidelity for periods, with long distance movements (〉1000 m) to new areas among residency periods. Overall, mean distance moved between tracking surveys was 1447 m. Home range size varied among individuals, with a 95% probability of localisation within an average area of 276,978 m2. The fish utilised a mean river stretch of 18,836 m (range = 90–71,840). All the fish were recorded in the main stem, and on average, 95% of the fixes were in the main stem during low water. However, the fish used temporary flooded areas to an increasing extent during the rising and high water period, but did not undertake long-distance migrations into the floodplains. Fish were sometimes near vegetation, but were never recorded into or under vegetation.

Notes: Abstract – The objective was to compare juvenile salmon density in 20 streams throughout the very large River Tana, northern Norway, and to relate variation in density to a suite of environmental factors. Four sampling sites were electrofished in each stream (one at the mouth of the stream and three within the stream) in August and October 2000, 2001, 2002. 0+ salmon parr were absent from seven streams, present at the mouth of 11 streams, and present within only two streams, both of which were probably spawning streams. Older parr migrated upstream into most streams and their highest densities were usually found in streams flowing directly into the spawning habitat in the three largest tributaries of the Tana or the river itself. Juvenile salmon were sparse or absent in streams flowing into smaller tributaries. Most streams with high parr densities were those of dense riparian vegetation that provided terrestrial invertebrates as drift food for the salmon parr, cover for fish, cooler stream temperatures in summer, and food for benthic stream invertebrates that were also a source of food for the parr.

Notes: Abstract – The size structure of a predator population can cause differences in the relative survival of different prey length classes whereby the biggest prey may reach a safe size because of the size-dependent character of predation. In the present study, the diet of European catfish was investigated to examine if catfish feeding can prevent cyprinids from reaching such a size refuge. In the lake studied, catfish was stocked for biomanipulation purposes to reduce unwanted roach and bream populations. Crayfish and roach were the most important prey items of catfish. If only species composition in the diet was considered, no clear changes were recorded in relation to catfish size. However, the length of roach as prey significantly increased with catfish length. Catfish were significantly larger than the other piscivorous fish in the lake, but took relatively smaller roach in comparison with similar-sized pike or pikeperch. Nevertheless, because of the high mean length of catfish, roach cannot reach a size refuge. For unknown reasons, the expected and intended predation on bream was not observed. Catfish took smaller prey than could be expected from mouth gape data. By extending the relationship between catfish as predator and roach as prey beyond the predator length range currently found in the lake, it could be shown that even catfish of 150 cm length will probably feed upon only 65% of all available bream length classes. Therefore, stocking with catfish cannot prevent a size refuge for the bream.

Notes: Abstract –  We examine patterns in fish species assemblages in the Toxaway and Horsepasture rivers, two high elevation streams in North Carolina, USA. This region is noted for extreme topographical relief, high cumulative annual rainfall and many rare and endemic plants and animals. The study area encompasses a portion of the Blue Ridge Escarpment and the associated Brevard Fault Zone. We hypothesise that major waterfalls and cascade complexes have acted to limit invasion and colonisation by fishes from downstream. This hypothesis is supported by longitudinal fish assemblage patterns in our study streams. Fish species richness in Toxaway River increased from 4 to 23 between Lake Toxaway and Lake Jocassee, a distance of 10 river km. We found similar discontinuities in neighbouring Horsepasture River and Bearwallow Creek. We found no instances of species replacement along this elevation gradient, and the trend in increased diversity downstream showed discontinuities coincident with sharp elevation breaks. With regard to theories posited to explain community formation in headwater stream fish communities (especially in those characterised by high topographical relief), we suggest coloniser ‘access’ may be more important than other factors including competitive interactions.

Notes: Abstract –  The timing of the smolt migration of Atlantic salmon, Salmo salar L., was investigated during 1972–2002 in the Simojoki, a river flowing into the northern Baltic Sea. The onset of the smolt run was positively correlated with the river water temperature; a rise in water temperature above 10 °C being the main proximate environmental triggering factor. There was also a weaker correlation between the decreasing river discharge in the spring and the onset of the smolt migration. The duration of the main run was shorter in the years when the onset of the smolt run was delayed. No differences were found in the onset timing or in the duration of the smolt run between wild smolts and semi-wild smolts released into the river as parr. A polynomial equation fitted to the annual data on the survival of Carlin-tagged wild smolts and the sea surface temperature (SST) in June off the river mouth appeared to follow a dome-shaped pattern. Survival was lower in cold early summers (SST 〈9 °C) than in those with an average SST (9–11.9 °C), and lower again, although not significantly, in warm early summers (SST ≥12 °C). Too low and probably also too a high water temperature in early summer could thus be one of the underlying reasons for the fluctuations observed in postsmolt survival in the Baltic Sea.

Notes: Abstract –  Hatchery-reared Florida largemouth bass, Micropterus salmoides floridanus, feed on inert pellet food while their wild counterparts capture elusive prey. Differences in levels of prey elusivity often mandate the use of alternate methods of prey capture. This study examines whether elusivity-based variation in prey capture translates to a phenotypic change during skull development, and if this change results in a functional difference in the feeding mechanism. The developmental pattern of the skull was conserved between hatchery and wild bass until 80–99 mm TL. At this point, wild bass quickly developed morphological changes of the jaw apparatus including a more fusiform head and elongated jaw structures. Natural development in hatchery bass, however, was retarded at this size. Post-release, the skulls of hatchery fish converged towards those of wild bass by 135 mm TL. Despite variation in skull development, no theoretical advantage in food capture was found between these two groups.

Notes: Abstract –  Spatial and temporal variation of species–environment relationships were evaluated for shallow-margin and deep-water fish assemblages in the Brazos River, a large floodplain river in Texas, USA. Total variation among the deep-water assemblages (11 species, 86% turnover across gill net samples) was greater than for shallow-margins (38 species, 64% turnover across seine samples). For both shallow-margin and deep-water assemblages, variation was greater among sites than between winter and summer seasons. Shallow-margin assemblage structure was related to depth, velocity and substrate, whereas for deep-water assemblages river discharge, temperature and velocity were important. Season itself accounted for little of the variation among either shallow (6.7%) or deep-water (2.3%) assemblages. Overall temporal patterns of shallow-margin samples appeared to show responses to juvenile recruitment, spates and migration of coastal fishes, whereas for deep-water samples, patterns related to use of reproductive habitats, juvenile recruitment and seasonal activity levels. Brazos River assemblages were less variable overall in comparison with studies along similar length of reach in headwater streams and wadeable rivers. The residual variation in species distribution (54% for shallow-margin and 67% for deepwater) that was not explained by instream variables and season suggests a greater influence of biotic interactions in rivers, particularly those across the spatially dynamic interface of main channel habitats and shallow river margins.

Notes: Abstract –  Juvenile salmon density was related to invertebrate density in 13 streams within the River Tana, northern Norway. There were only small, nonsignificant, differences in benthic density between streams with and without juvenile salmon. All streams with a high density of juvenile salmon had low benthic densities at the stream mouth. Juvenile salmon were not found, or were in very low densities, in streams where the benthic density at the stream mouth was as high or higher than that in the stream. A multiple regression model showed that parr density was related negatively to benthic density at the stream mouth, water velocity and pH, and positively to benthic density within the stream and the proportion of the substratum covered by moss. The amount of overhanging cover in the different streams explained 93% of the variation in the drift density of terrestrial invertebrates in August. The highest densities of juvenile salmon were found in streams with riparian vegetation, and were thus associated with an abundant supply of drift food, especially terrestrial invertebrates.

Notes: Abstract –  An essential innovation in aquatic biodiversity research would be a robust approach to accurately predict species’ potential distributions. In this paper, I conduct an analysis to test the efficacy of ecological niche modelling for predicting fish species’ potential distributions using an artificial-intelligence algorithm, the Genetic Algorithm for Rule-Set Prediction (GARP). Models of species’ ecological niches are developed using GARP, and projected onto geography to predict species distributions. To test the validity of this approach, I used freshwater fish distribution data for twelve fish species occurring in Kansas. These taxa were chosen to represent phylogenetic, distribution, and habit diversity. I subset these data by omitting half of the counties from model building, and test models using the omitted counties. Models were tested using Receiver Operating Characteristic (ROC) analyses. Of the species tested, all were statistically significant with the models showing excellent predictive ability. Omission errors across taxa ranged from 0 to 17%. This inferential capacity opens doors to many synthetic analyses based on primary point-occurrence data.

Notes: Abstract –  Over a 3-year period we examined variability in physical habitat structure and species richness, abundance and assemblage composition of fishes in 13 habitat patches in the Bernecei stream, Hungary. Principal component analysis of habitat structure data from patches elucidated a riffle-run-pool habitat gradient across patches. Temporal habitat variability increased significantly from riffle to pool patches. Fish assemblage characteristics displayed relatively continuous change over the habitat gradient and were relatively stable within patches. Assemblage structure properties (e.g., species richness) displayed different responses to the habitat gradient and to within-patch habitat variability. In general, pool patches had more diverse assemblages and greater within-patch assemblage variability than riffle patches. However, within-patch dynamics were largely determined by the population dynamics of a habitat generalist (i.e., minnow). Broad scale environmental variability (i.e., a catastrophic 100-year flood) also appeared to affect within-patch fish assemblage characteristics. Our results demonstrate that fish assemblage structure is influenced by physical variability (i.e., both floods and spatio-temporal habitat variability) within the Bernecei stream.

Notes: Abstract – We tested the effects of a pollution gradient on the survival and energetic responses of Atlantic salmon fry stocked in Onondaga Creek, a historic but highly polluted nursery stream. A relatively unperturbed reference stream provided similar physical and thermal gradients that co-varied longitudinally with the pollution gradient in Onondaga Creek, and macroinvertebrate communities provided indices of water quality degradation. Survival, cohort biomass, instantaneous growth rate and growth index of Atlantic salmon were inverse functions of water quality in the perturbed stream. Generally, survival and energetic parameters of Atlantic salmon responded differently to longitudinal gradients in the two streams, indicating that water quality, rather than habitat variation, exerted the strongest control over salmon. Effects were more pronounced during the early summer, possibly because tolerance to such perturbations increases with age or body size. Energetics-related parameters were more sensitive to water quality than were survival-related parameters, indicating that sub-lethal effects of pollution may be detected and quantified by examining energy balances of individuals.

Notes: Abstract – Structural complexity offered by submerged macrophytes was shown to have fundamental effects on interactions between fish and their prey. However, less information is available for littoral reed (Phragmites spp.) stands. A previous field study found juvenile roach and perch to coexist within the reed stands. It was suggested that reed serves mainly as refuge against littoral piscivores, such that coexistence of perch and roach in the reed was externally forced. Several hypotheses were raised to explain why roach nevertheless showed good growth performance. Three of the hypotheses were tested experimentally. In particular, we were interested in how the confinement of fish to one of the reed or open water habitats alters feeding and growth patterns of juvenile age-1 perch and roach. Fish were stocked separately into littoral enclosures for a 3-week period in densities which had been found in the surrounding lake. Development of zooplankton and macroinvertebrate biomasses was observed by sampling the enclosures three times over the experimental period. Individual consumption of prey groups by the fish was calculated with a bioenergetics model, and was compared with prey group biomass in the enclosure treatments. The confinement of fish to one littoral habitat had clear effects on diet composition and growth rates. Roach fed less zooplankton and partially switched to macroinvertebrates in the reed enclosures when compared with the open water treatments, and consequently their growth rates were lower in the reed. Perch preferred macroinvertebrates in both habitats, without any difference in growth rates between the habitats. Effects of fish predation on both zooplankton and macroinvertebrate biomass were low in open water and reed enclosures. Daily consumption rates were only in a few cases higher than 40% of the available biomass of the respective prey group, but mainly were below 10% of available biomass. Therefore, we argue that both the diel horizontal migrations of roach and the relatively low consumption rate of fish when compared with the available resource biomass allow the coexistence of juvenile roach and perch in littoral reed stands.

Notes: Abstract –  The otolith composition of age 0+ Allis shad (Alosa alosa) captured in two rivers in the Gironde system in south-west France, the Dordogne and the Garonne, was analysed to establish the natal origin of the fish. Inductively coupled plasma mass spectrometry analyses were used to take measurements of 15 isotopes, among which Co, Fe, Sr and Rb were the most important elements in the discrimination process. It was possible to reclassify each sampled fish into its natal river basin (Garonne or Dordogne) with a high degree of accuracy. Linear discriminant analysis correctly reclassified 91.1% of the Garonne samples and 87.8% of the Dordogne samples (mean success in reclassification in 20 runs ± 1 SD: 89.21 ± 8.6%). Artificial neural networks correctly reclassified 90.1% of the Garonne samples and 81.2% of the Dordogne samples (mean success in reclassification after 1000 training cycles ±1 SD: 85.6 ± 9.1%). Using these tools the present results show that it is possible to assign a natal origin to juvenile shad that hatched in the Dordogne–Garonne basin based on the trace elements in the otolith.

Notes: Abstract – We analysed the movements of the growing yellow phase using a long-term mark–recapture programme on European eels in a small catchment (the Frémur, France). The results showed that of the yellow eels (〉200 mm) recaptured, more than 90% were recaptured at the original marking site over a long period before the silvering metamorphosis and downstream migration. We conclude that yellow European eels 〉200 mm may adopt a sedentary lifestyle in freshwater area, especially in small catchment.

Notes: Abstract –  Life-history variation in perch (Perca fluviatilis L.), with special emphasis on age and size at maturity in females, was studied in five lakes in Northern Sweden, differing in perch size distribution and relative predator abundance. Age at maturity was negatively correlated with size of young-of-the-year perch in the end of their first growth season. Length at maturity was positively correlated with L∞ (asymptotic length when age is close to infinity) and negatively correlated with K (growth rate coefficient) from von Bertalanffy growth model. Relative predator abundance was negatively correlated with minimum size at maturity. However, predation was probably more important in its effect on growth, with a high predation leading to a decrease in population density, decreased food competition, and as a consequence, higher growth rates. Instantaneous mortality rates did not affect maturation patterns when comparing across the five lakes. Age and size at maturity in the perch populations studied here seemed to be mainly influenced by factors affecting growth.

Notes: Abstract –  Serious impacts by nonindigenous species often occur via predation. The magnitude of impact is expected to be closely tied to the invading species niche breadth. For predatory impacts, diet breadth should be particularly important. We examined the relationship between a species foraging behaviour and its invasiveness and impact by comparing the feeding behaviour of four Gambusia species, two invasive and of high impact and two noninvasive. Individual feeding rates, feeding preferences, and diet breadths were tested across three prey items in a sequence of four laboratory feeding trials. Invasive Gambusia consistently fed at higher rates, but no species differences were found in feeding preferences or diet breadth. All Gambusia preferred Daphnia, avoided Lirceus, and consumed Drosophila in proportion to their availability. Female size affected most feeding variables. Larger fish consumed more prey per unit time and were able to incorporate larger prey items into their diets, thus increasing diet breadth.

Notes: Abstract –  Predicting species distributions has important implications for the conservation and management of freshwater fishes, particularly in areas such as the Great Plains, USA where human impacts have resulted in extirpations and declines for numerous native species. There are a number of statistical approaches for constructing distributional models; the accuracy of each is likely dependent on the nature of the environmental gradients, species responses to those gradients and the spatial extent of the modelling. Thus, it is important to compare multiple approaches across species and habitats to identify the most effective modelling approach. Using geographical information system (GIS) derived characteristics of stream segments as predictors, we tested the model performance of three methodologies – linear discriminant function analysis, classification trees and artificial neural networks (ANN) – for predicting the occurrence of 38 fish species in a Great Plains river basin. Results showed that all approaches predicted species occurrences with relatively high success. ANN generally were the best models, in that they generated the most significant models (35 of 38 species) and most accurately predicted species presence for the greatest number of species (average correct classification = 81.1%). The importance of GIS variables for predicting stream fish occurrences varied among species and modelling techniques, but were generally strong predictors of species distributions, including the federally endangered Topeka shiner Notropis topeka. In summary, predictive models should be viewed as both competitive and complementary methodologies for establishing quantitative linkages between fish species and their environment. Our study demonstrates the potential utility of such an approach for guiding conservation efforts for stream fishes of the Great Plains, USA.

Notes: Abstract –  Based on the analysis of 17 successive year-classes, this investigation attempted to identify the factors determining year-to-year variation in population size of the stream-living juveniles of Lake Hald-dwelling brown trout Salmo trutta L. Population size appeared to be influenced chiefly by annual recruitment that in turn, was determined by stream discharge and temperature. These patterns matched those previously highlighted for a resident population located 〉2500 km apart and emphasised the importance of environmental (climatic) variability as a major regulating agent of population size in stream brown trout. However, distinctly shaped recruitment–discharge relationships between the two populations suggested different mechanisms in response to environmental variability and thus to persist in time.

Notes: Abstract –  In lake Krokavatn, 1236 m a.s.l., only six strong year-classes of brown trout appeared during the period 1970–2003. Eleven year-classes were missing during the same period. The observed recruitment failure depended significantly on the accumulated snow depth in April, whereas the mean August temperature in the year of birth was significant for the appearance of strong year-classes. Size of the young-of-the-year (YOY) trout at onset of the winter seemed to be crucial for survival. Also little snow and low temperatures during the winter may have led to recruitment failure, as small nursery streams may freeze completely under such conditions, as happened during the winter of 1995/1996. Thus, the recruitment to brown trout populations in western high mountain areas of Norway seemed to be strongly affected by accumulated snow depth and summer temperatures. A climate change with more winter precipitation, as predicted for the present century, may therefore be detrimental to recruitment. However, warmer summers may increase recruitment to levels that lead to overpopulation, but also to establishment of brown trout populations at higher elevations than today.

Notes: Abstract –  We measured growth of pike larvae (Esox lucius) fed with freshwater and brackish-water zooplankton by monitoring larval wet weight during 18 days. The fish food was analysed for species composition, carbon, nitrogen and fatty acids. Further, we analysed fish larval faecal pellet production. Larval weight was significantly higher in fresh water than in brackish water with natural zooplankton as food. Growth, given as wet weight, showed a significant relationship with zooplankton (〉100 μm) food carbon and highly unsaturated fatty acids, 20:5ω3, 22:6ω3, ω6 fatty acids and the ω3/ω6 fatty acid ratio. Phytoplankton fatty acids (10–50 μm), such as polyunsaturated fatty acids, 20:5ω3, 22:6ω3 and the ω3 fatty acids also correlated strongly with the wet weight of pike larvae. We demonstrated that several factors impact on pike larval growth.

Notes: Abstract –  Atlantic salmon (Salmo salar) was once native to Lake Ontario, however, its numbers rapidly declined following colonisation by Europeans and the species was extirpated by 1896. Government agencies surrounding Lake Ontario are currently undertaking a variety of studies to assess the feasibility of reintroducing Atlantic salmon. We released hatchery-reared adult Atlantic salmon into a Lake Ontario tributary to examine spawning interactions between this species and fall-spawning exotic salmonids found in the same stream. Chinook salmon, coho salmon and brown trout were observed interacting with spawning Atlantic salmon in nearly one-quarter of our observation bouts, with chinook salmon interacting most frequently. Whereas a previous investigation found that chinook salmon caused elevated agonistic behaviour and general activity by spawning Atlantic salmon, the present study found that interspecific courtship was the most common form of exotic interaction with spawning Atlantic salmon. In particular, we observed precocial male Chinook salmon courting female Atlantic salmon and defending the female against approach by male Atlantic salmon. We discuss the potential implications of these interactions on the Lake Ontario Atlantic salmon reintroduction programme.

Notes: Abstract –  Genetic data on archaeological specimens provide complementary information for addressing questions on distribution and migration of fishes over long time scales. In this study DNA was extracted from common bream bones (N = 4), dated c. 6000–1000 bp, and a 172 bp fragment of mitochondrial cytochrome b gene has been sequenced. The obtained sequences differed from homologous sequences of breams living contemporarily (N = 4), inhabiting the same geographical areas as ‘ancient’ fish. None of ancient mitochondrial haplotype was found in fish living at present. Our results suggest that fish vicariance could be affected also by other than glacial retreat historical events, and the mechanisms that influenced present distribution of freshwater fishes are still unclear.

Notes: Abstract –  Predation risk allocation hypothesis predicts that a prey's response to predator depends on prey's previous experience on predator. Here we tested whether the group of three perch respond differentially to pike, predator of perch, depending on the timing of high constant (HC) and high unpredictable (HU) risk periods within low constant risk periods in short-term (10 h) experiments, and whether the response is stronger during a HU risk period than during a HC risk period. Perch clearly erected the dorsal fin in response to predation risk treatments (pike odour only, odour and visible pike). Decrease in activity and increase in shoaling behaviour were observed mainly during high risk periods. However, the perch's responses to pike did not differ statistically between periods of various levels of predation risk or depending on the timing of high risk situations within constant low risk periods, and thus, suggesting that perch respond mainly to changes in the current predation risk.

Notes: Abstract –  The longitudinal distribution of fish assemblages across a large west European river basin, the Garonne river (south-west France) were investigated using a self-organising map. This nonlinear statistical method was employed to classify sampling sites according to their species composition. We found three main nested patterns in an aggregated hierarchy: a replacement and succession of species along a gradient without defined boundaries, four main zones of fish assemblages and an upstream-downstream shift of fish communities. We suggest that fish assemblages are too complex to be identified with a single species as in the zonation model, and that the diversity patterns found might be part of the same ecological process influencing fish assemblages on different spatial scales. Thus, discrepancies in the analysis of longitudinal patterns of fish communities in streams may have been basically a matter of local conditions and of conceptual perception.

Notes: Abstract – Complex interactions between fish predators and their prey have been found in structurally complex habitats built by submerged macrophytes. In contrast, the role of comparably structured littoral reed stands in shaping biotic interactions has not been investigated. We hypothesised that reed stands may be a valuable feeding habitat for juvenile fish, and that perch and roach may segregate along the spatial and dietary niche dimensions between reed and open water habitats. In contrast, the protection effect of reed against predators was assumed to be rather low because of the lower plant volume infested in reed when compared with submerged macrophytes. We analysed biomass and growth of juvenile (age 0 and age 1) perch and roach in littoral reed habitats and in open water habitats in front of the reed in the shallow Lake Müggelsee over 4 months in 2000. Sampling was conducted by point-abundance electrofishing over the full diel cycle (day, dusk, night, dawn). Zooplankton and benthos biomasses were determined in both habitats as well, and habitat-specific diet of fish was assessed during day and night. Roach were more frequent than perch in both habitats. Food of roach included a higher proportion of zooplankton, whereas perch fed more on macroinvertebrates. Overall, diet overlap between the fish groups was high. Diel distribution of fish did not follow the expectations of habitat segregation between perch and roach. Instead, the function of reed as refuge habitat against littoral piscivores (mainly birds) may have caused the strong daytime preference for reed in almost all fish groups, which was partly upset by roach at night. The higher behavioural plasticity of roach may explain their good performance even under the conditions of high structural complexity.

Notes: Abstract –  Leatherside chub (Snyderichthyes copei Jordan & Gilbert) comprises two lineages (northern and southern) whose centres of geographical range differ by about 3° latitude corresponding to about 30% shorter growing season and about 2 °C lower mean temperature during the growing season. We document patterns of variation in size-at-age among populations of leatherside chub in nature, and we test for variation in intrinsic growth rate of juvenile chub in a common-environment experiment to determine if lineages exhibit different intrinsic growth rates. Northern leatherside chubs at ages 1–3 were about 15% shorter in length compared with southern populations. Variation in hatching date or age at maturity could not account for differences in growth and body size, suggesting that temperature-specific intrinsic growth rates differed among populations. Based on a common environment experiment, we found that reaction norms for temperature-specific growth in length and mass were crossed. At the lower temperature, individuals from the north exhibited higher intrinsic growth in length, and at the higher temperature individuals from the south exhibited higher intrinsic growth in mass. Crossing reaction norms for temperature-specific intrinsic growth rates support a model of local adaptation to thermal regime.

Notes: Abstract – Although homing behaviour has been observed in juvenile Atlantic salmon, brown trout and resident cutthroat trout, this behaviour has not been well studied in juvenile Pacific salmon. We examined the site fidelity and homing behaviour of juvenile coho salmon (Oncorhynchus kisutch) by marking and relocating them within an off-channel habitat. Over 80% of displaced fish returned to the area from which they were originally collected. The proportion of fish that returned to the original location did not vary significantly among three sampling dates. However, we found that this proportion decreased over time in a brackish lagoon when we statistically analysed the data reported by Day (1966). Our results suggest that juvenile coho salmon exhibit strong site fidelity and are able to return to their home ranges after displacement. These behaviours are likely to be important for the winter survival of juvenile coho salmon.

Notes: Abstract – This study documents substantial small-scale spatial variation in age and size at maturity of brown trout (Salmo trutta) found either in allopatry (above major waterfalls) or in sympatry (below waterfalls) with the Alpine bullhead (Cottus poecilopus) in forest streams in south-east Norway. Within two streams, female brown trout above waterfalls tended to delay the onset of sexual maturity, as compared with females from neighbouring sites below the waterfalls. Four additional streams were represented with either an allopatric or a sympatric site. There was considerable variation in age and size at maturity among these streams, but no consistent difference between allopatric and sympatric sites. It is suggested that the spatial variation in maturity responses is influenced by local opportunities for growth, and possibly also survival. Earlier studies in these streams have linked spatial variation in brown trout behaviour and demography to the presence or absence of the Alpine bullhead.

Notes: Abstract –  Allozyme genetics (34 loci) is studied in up to 1010 European trout (Salmo trutta) from the Rhine, Meuse, Weser, Elbe and Danube river systems in Central Europe. Population samples from single collection sites, chiefly small streams (GCG = 0.2126), rather than the divergence of the trout from Atlantic and Danubian drainages (GSG = 0.0711), contributed to the overall gene diversity of GST = 0.2824. Sea trout (n = 164) and brown trout (n = 767) in Atlantic rivers adhere to the same biogeographical stock, but anadromous trout from the Rhine and the Elbe display more genetic cohesion than resident brown trout from the Rhine system alone. Strayers from the Elbe could have founded the recently re-established sea trout population of the Rhine, after a few decades of absence or precarious rarity. Migrants may even connect the Rhine and Elbe stocks by ongoing gene flow. A release–recapture study confirms that all trout in the Rhine belong to one partly migratory population network: Six of 2400 juvenile sea trout released into a tributary of the Rhine were later recorded as emigrants to the Rhine delta, against three of 1600 released brown trout. One migrant had entered the open North Sea, but the other dispersers were recorded in fresh waters of the Rhine delta (Ijsselmeer, Amstelmeer). Stocking presumably elevated both heterozygosity and fixation indices of brown trout, but this effect is subtle within the range of the Atlantic population group. Improved sea trout management in the Rhine, and modifications to brown trout stocking in the upper Danubian area are recommended.

Notes: Abstract –  Understanding factors related to the occurrence of species across multiple spatial and temporal scales is critical to the conservation and management of native fishes, especially for those species at the edge of their natural distribution. We used the concept of hierarchical faunal filters to provide a framework for investigating the influence of habitat characteristics and nonnative piscivores on the occurrence of 10 native fishes in streams of the North Platte River watershed in Wyoming. Three faunal filters were developed for each species: (i) large-scale biogeographic, (ii) local abiotic, and (iii) biotic. The large-scale biogeographic filter, composed of elevation and stream-size thresholds, was used to determine the boundaries within which each species might be expected to occur. Then, a local abiotic filter (i.e., habitat associations), developed using binary logistic-regression analysis, estimated the probability of occurrence of each species from features such as maximum depth, substrate composition, submergent aquatic vegetation, woody debris, and channel morphology (e.g., amount of pool habitat). Lastly, a biotic faunal filter was developed using binary logistic regression to estimate the probability of occurrence of each species relative to the abundance of nonnative piscivores in a reach. Conceptualising fish assemblages within a framework of hierarchical faunal filters is simple and logical, helps direct conservation and management activities, and provides important information on the ecology of fishes in the western Great Plains of North America.

Notes: Abstract.  Historical accounts of the work of J. J. Thomson find a contradiction in his work. On the one hand, he is presented as a Maxwellian theoretical physicist dealing with a typically Victorian entity, the ether. On the other hand, the analysis of his experimental work at the Cavendish seems to have little connection with his mathematical work. In this paper, I discuss the metaphysical views of J. J. Thomson, and argue that his deep belief in the ultimate continuity of matter can be seen to give a framework to both his theoretical and his experimental work. His metaphysical beliefs were not in the least shaken by the discovery of discrete phenomena and entities, not even by his suggestion of the existence of corpuscles later known as electrons. His formation in Cambridge, together with some ideas that he acquired in his youth at Owens College, Manchester, are the key to understanding his metaphysics and the role it plays in his scientific work.

Notes: Abstract.  Ptolemy provides two explanations of the origin of his highly precise planetary mean motions in the Almagest, asserting in one set of passages that they were obtained directly from analysis of pairs of observations widely spaced in time, but in another passage that they were derived from period relations expressed as corrections to the well-known Babylonian Goal-Year periods. We show that the latter account is true. Moreover, while some of these period relations may have themselves been calibrated through the observations that Ptolemy cites, those for Mercury and Saturn can be shown to have had a different origin.

Notes: Mathew Chandrankunnel, Philosophy of Physics, reviewed by Helge KraghDanian Hu, China and Albert Einstein: The Reception of the Physicist and His Theory in China, 1917-1979, reviewed by Helge Kragh

Notes: The Saros cycle of 223 synodic months played an important role in Late Babylonian astronomy. It was used to predict the dates of future eclipse possibilities together with the times of those eclipses and underpinned the development of mathematical lunar theories. The excess length of the Saros over a whole number of days varies due to solar and lunar anomaly between about 6 and 9 h. We here investigate two functions which model the length of the Saros found in Babylonian sources: a simple zigzag function with an 18-year period presented on the tablet BM 45861 and a function which varies with the month of the year constructed from rules found on the important procedure text TU 11. These functions are shown to model nature very well and to be closely related. We further conclude that these functions are the likely source of the Saros lengths used to calculate the times of predicted eclipses and were probably known by at latest the mid-sixth-century BC.

Notes: Abstract.  In 1768, Kant published a short essay in which he inquired into the possibility of determining the directionality of space. Kant's central argument invokes the strategy that if one were to demonstrate directionality, then the relational view of space that Leibniz propounded would be refuted. This paper has been considered a major turning point in Kant's philosophical development towards his critical philosophy of transcendental idealism. I demonstrate that in this study, Kant came very close to the modern concept of symmetry. His novel construction of incongruent counterpart (inkongruentes Gegenstück) contains elements essential to the modern notion of symmetry. However, Kant does not consider the incongruent counterparts, which he designates as ‘Right’ and ‘Left’, symmetric; rather, he holds the French encyclopaedist view that symmetry is a kind of balance. This study convinced Kant that the solution to the problem of the nature of space lies not in mathematics but in metaphysics. He was wrong in this conclusion, at least with respect to symmetry. The solution was found within the framework of mathematics, that is, solid geometry. In 1794, Legendre recast the traditional encyclopaedist concept of symmetry by calling a certain property of polyhedra symmetrical. The view of Kant is contrasted with that of Legendre by comparing their usages of mirror image as an aid for understanding. While in both cases mirror images are not considered illusions—perhaps for the first time in the history of mirror reflections—the differences are substantial, highlighting the limitation of Kant's position and the great potential of Legendre's new concept of symmetry.

Notes: Abstract.  In modern discourse about the history of science, it seems to be widely accepted that at the end of the nineteenth century, Germany was one of the leading countries in the production of science. In the past, historians of science tried to trace back a specific ‘German style’ of science that—in combination with other factors—determined this German dominance around 1900, especially in the life sciences. Considering the theoretical concept of ‘national styles’, it has to be kept in mind that around 1900, contemporaries already proclaimed ‘national styles’ of science as representations of national identity. Thus, the question arises as to how far existing historiographical conceptions of national styles may include earlier claims and prejudices. Careful reconstructions of contemporary discourses on national styles and inquiries into the ‘stylisation’ of a dominant, successful ‘German style’ are necessary. One of the contemporary critics of a ‘German style’ of science was the physiologist Jacques Loeb (1859–1924), who emigrated to the USA in 1891. Loeb corresponded regularly with the physicist and philosopher Ernst Mach (1838–1916). Ernst Mach can be considered Loeb's intellectual father with whom he corresponded about strategic, philosophical, and epistemological questions. Using the Loeb–Mach correspondence, the aim of the paper is to reconstruct Loeb's conception of a ‘German style’ of science and its differences to an ‘American style’. Changes in his views are discussed as well as the roots of his views and some of their consequences. Finally, Loeb's ideas on national styles and his working profiles before and after his emigration are compared to historiographical analyses of ‘American’ or ‘German’ styles of science around 1900.

Notes: Books reviewed: 

 Giovanni Dondi, Tractatus Astrarii (Geneva: Librairie Droz, 2003). Translation and critical edition by Emmanuel Poulle. 468 pp. hc. ISBN 2-600-00810-1.Bodil Branner; Jesper Lützen (eds.), Caspar Wessel: On the Analytical Representation of Direction (Copenhagen: The Royal Danish Academy of Sciences and Letters, 1999). 143 pp. pb. DKK 500. ISBN 87-7876-158-1.Jesper Luuml;tzen (ed.), Around Caspar Wessel and the Geometric Representation of Complex Numbers (Copenhagen: The Royal Danish Academy of Sciences and Letters, 2001). 293 pp. pb. DKK 300. ISBN 87-7876-236-7.Frank A.J.L. James (ed.), ‘The Common Purposes of Life’: Science and society at the Royal Institution of Great Britain (Aldershot: Ashgate, 2002). 472 pp. £55. hc. ISBN 7546-0960-X.Anastasios Brenner, Les origines françaises de la philosophie des sciences (Paris: Presses Universitaires de France, 2003). 224 pp. ISBN 2-13-053150-4.David Knight, Science and Spirituality: The Volatile Connection (London: Routledge,2003). 230 pp. pb. £18.99. ISBN 0-415-25769-7.Sungook Hong, Wireless: From Marconi's Black Box to the Audion (Cambridge, Mass.: MIT Press, 2001). 248 pp. hc. $34.95 / £23.50. ISBN 0-262-08298-5.Peter J. Ramberg, Chemical Structure, Spatial Arrangement: The Early History of Stereochemistry, 1874-1914 (London: Ashgate, 2003). 424 pp. hc. £57.50. ISBN 0-7546-0397-0.Jean-François Stoffel, Le phénoménalisme problématique de Pierre Duhem, Brussels (Académie royale de Belgique) 2002. 392 pp. Eur. 32 pb. ISBN 2-8031-0190-4.Rienk Vermij, The Calvinist Copernicans:The Reception of the New Astronomy in the Dutch Republic, 1575-1750 (Amsterdam: Koninklijke Nederlandse Akademie van Wetenschappen, 2002). 433 pp. hc. EUR 49. ISBN 90-6984-340-4.Alois Kernbauer (ed.), Die ‘klinische Chemie’ Jahre 1850. Johann Florian Heller Bericht über seine Studienreise in die deutschen Länder, in die Schweiz, nach Frankreich und Belgien im Jahre 1850 (Stuttgart: Franz Steiner Verlag, 2002). 192 pp. EUR 34. ISBN 3-515-08122-4.Ursula Klein, Experiments, Models, Paper Tools. Cultures of Organic Chemistry in the Nineteenth Century (Stanford: Stanford University Press, 2003). xi+305 pp. hc. ISBN 0-8047-4359-2.

Notes: Abstract.  One of the mathematical topics examined in the Old Babylonian period consisted of calculating the size of a reed which was used to measure either a longitude or the perimeter of a rectangle or trapezium. These subjects were solved, probably, applying the geometric construction called completing the square. In this paper, we analyse the problem texts on the tablets AO 6770 (5), Str 368, VAT 7532, and VAT 7535.

Notes: Abstract.  The present paper offers strong evidence that there was a particularly advanced, for the era, sense and application of geometry in the prehistoric civilization of the island of Thera (Santorini), Greece, ca. 1650 BC. First, by applying an original method, it is demonstrated that specific shapes, depicted on so far unpublished wall paintings initially decorating the third floor of Xeste 3, correspond to advanced geometric configurations with remarkable accuracy. Thus, it is shown that there are configurations corresponding to linear spiral prototypes, others matching elliptical prototypes and sets of points lying on isogonal lines that are radii of regular polygons with 48, 32, and 24 angles. Subsequently, it is shown that the use of geometric archetypes for drawing played a prominent role in the Late Bronze Age Thera civilization. In fact, it is demonstrated that celebrated wall paintings have border lines that impressively match a limited number of linear (Archimedes’) spirals, hyperbolas, and ellipses in a piecewise manner. This practically excludes the probability that these wall paintings were drawn by freehand, while, on the contrary, it strongly suggests that they were mainly drawn by means of geometric stencils.

Notes: Abstract.  Heron's Dioptra 35 is the unique witness of an ancient mathematical procedure for finding the great arc distance between two cities using methods of ancient spherical astronomy and simultaneous observations of a lunar eclipse. This paper provides a new study of the text, with mathematical and historical commentary. I argue that Heron's account is a summary of some longer work of mathematical astronomy or geography, which made extensive use of the analemma, an ancient model of the celestial sphere. Heron's text can be used to show the utility of the analemma model, both as a theoretical device and as a computational tool.

Notes: The family of Deg proteases is present in nearly all organisms from bacteria to higher plants. This family consists of ATP-independent serine endopeptidases with a catalytic domain of trypsin type and up to three PDZ domains, involved in protein–protein interactions. Sixteen deg genes (originally named degP1–16) were found in Arabidopsis thaliana, and the chloroplast location was predicted or experimentally proven for seven proteins. The cyanobacterium Synechocystis sp. PCC6803 contains three Deg homologues, HtrA (DegP), HhoA (DegQ) and HhoB (DegS), but their number can vary between one and six in other photosynthetic Prokaryota. Interestingly, all of these proteases are evolutionarily more closely related within one species than proteases with the same names present in other organisms. This means that Deg proteases from A. thaliana are not necessarily the closest relatives of cyanobacterial DegP. Therefore, we propose to change the misleading original name ‘DegP’ to ‘Deg’ for A. thaliana enzymes. Here, we summarize the expression, location and functions of Deg proteases from cyanobacteria and chloroplasts of higher plants, with special emphasis on their role in the photosystem II (PSII) repair cycle under light stress conditions.

Notes: We examined differences between summer and winter in xanthophyll cycle-dependent energy dissipation and leaf antioxidant systems in needles of the overwintering evergreen Taxus x media cv. Tauntonii (Taunton yew) growing in both sun and shade environments in Saint Paul, Minnesota. During the winter, both sun and shade plants exhibited increases in the capacity for, and utilization of, xanthophyll cycle-dependent thermal energy dissipation. Winter needles showed decreases (sun needles) or no change (shade needles) in superoxide dismutase activity (EC 1.15.1.1), no change in ascorbate peroxidase activity (EC 1.11.1.11) and no change (sun needles) or increases (shade needles) in reduced ascorbate levels. Both sun and shade needles showed large increases in glutathione reductase activity (EC 1.6.4.2) and total glutathione levels during the winter, in addition to increases in levels of α-tocopherol. These results suggest an important photoprotective role during the winter for xanthophyll cycle-dependent energy dissipation and for the antioxidants glutathione and α-tocopherol. They suggest a less important photoprotective function of the enzyme-based water–water cycle in winter acclimation in the seasonally very cold environment of Minnesota.

Notes: Etiolated pea (Pisum sativum L. cv. Alaska) seedlings grown under microgravity conditions in space show automorphosis: bending of epicotyls, inhibition of hook formation and changes in root growth direction. In order to determine the mechanisms of microgravity conditions that induce automorphosis, we used a three-dimensional clinostat and obtained the successful induction of automorphosis-like growth of etiolated pea seedlings. Kinetic studies revealed that epicotyls bent at their basal region towards the clockwise direction far from the cotyledons from the vertical line (0°) (see legend for Fig. 6) at approximately 40° in seedlings grown both at 1 g and in the clinostat within 48 h after watering. Thereafter, epicotyls retained this orientation during growth in the clinostat, whereas those at 1 g changed their growth direction against the gravity vector and exhibited a negative gravitropic response. On the other hand, the plumular hook that had already formed in the embryo axis tended to open continuously by growth at the inner basal portion of the elbow; thus, the plumular hook angle initially increased; this was followed by equal growth on the convex and concave sides at 1 g, resulting in normal hook formation; in contrast, hook formation was inhibited on the clinostat. The automorphosis-like growth and development of etiolated pea seedlings was induced by auxin polar transport inhibitors (9-hydroxyfluorene-9-carboxylic acid, N-(1-naphthyl)phthalamic acid and 2,3,5-triiodobenzoic acid), but not by anti-auxin (p-chlorophenoxyisobutyric acid) at 1 g. An ethylene biosynthesis inhibitor, 1-aminooxyacetic acid, inhibited hook formation at 1 g, and ethylene production of etiolated seedlings was suppressed on the clinostat. Clinorotation on the clinostat strongly reduced the activity of auxin polar transport of epicotyls in etiolated pea seedlings, similar to that observed in space experiments (Ueda J, Miyamoto K, Yuda T, Hoshino T, Fujii S, Mukai C, Kamigaichi S, Aizawa S, Yoshizaki I, Shimazu T, Fukui K (1999) Growth and development, and auxin polar transport in higher plants under microgravity conditions in space: BRIC-AUX on STS-95 space experiment. J Plant Res 112: 487–492). These results suggest that clinorotation on a three-dimensional clinostat is a valuable tool for simulating microgravity conditions, and that automorphosis of etiolated pea seedlings is induced by the inhibition of auxin polar transport and ethylene biosynthesis.

Notes: The effects of silicon application on the drought tolerance of sorghum (Sorghum bicolor (L.) Moench) were investigated for two cultivars differing in drought susceptibility. Silicon application ameliorated the decrease in dry weight under drought stress conditions, but had no effect on dry matter production under wet conditions. Under dry conditions, silicon-applied sorghum had a lower shoot to root (S/R) ratio, indicating the facilitation of root growth and the maintenance of the photosynthetic rate and stomatal conductance at a higher level compared with plants grown without silicon application. The diurnal determination of the transpiration rate indicated that the silicon-applied sorghum could extract a larger amount of water from drier soil and maintain a higher stomatal conductance. Very similar effects of silicon application were observed for both cultivars regardless of their drought susceptibility. These results suggest that silicon application may be useful to improve the drought tolerance of sorghum via the enhancement of water uptake ability.

Notes: Little reliable information exists about the genetic events that control the onset and timing of seed-fill in soybean cotyledons. To identify the genes involved in this process, cDNA libraries were prepared from mRNAs isolated from seeds at 7 and 21 days after flowering (DAF), which represent times just before and after the initiation of seed-fill. For the soybean variety Resnik, which was used for this study, seed-fill and the establishment of an endoreduplicative cell cycle occurred 12–14 DAF. Suppression subtractive hybridization was then applied to identify sequences that were differentially expressed at each of these two developmental stages. False positives in the libraries were reduced by using mirror orientation selection (MOS). The libraries of differentially expressed genes that resulted were analysed and the nucleotide sequences obtained were compared with those in existing databases. Several genes from each library were chosen and their expression profile during seed development was analysed by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) using RNA preparations originating from different seed developmental stages. Candidate genes for control of the stage shift from dividing cells to endoreduplication were identified.

Notes: LLA23, an abscisic acid-, stress- and ripening-induced (ASR) protein, was isolated previously from lily (Lilium longiflorum) pollen. Close examination of the C-terminus of this ASR protein revealed the presence of basic regions reminiscent of a nuclear localization signal (NLS). Fluorescence microscopy studies using green fluorescent protein (GFP) fusion proteins indicated that the bipartite NLS in LLA23 exhibited nuclear localization properties. Accordingly, mutations in the NLS motifs of LLA23 defined two regions, either of which was necessary for partial nuclear targeting and both of which were required for complete nuclear localization. In addition, oligonucleotide-directed mutagenesis identified lysine residues within the NLS necessary for nuclear localization. Immunogold localization confirmed that the protein was located to both the cytoplasm and nucleus of generative and vegetative cells of pollen grains; the generative nuclei showed the highest number of LLA23 labelling. The possible function of ASR proteins in both the cytoplasm and nuclei of pollen grains is discussed.

Notes: Plants grown in an environment of elevated CO2 and temperature often show reduced CO2 assimilation capacity, providing evidence of photosynthetic downregulation. The aim of this study was to analyse the downregulation of photosynthesis in elevated CO2 (700 µmol mol−1) in nodulated alfalfa plants grown at different temperatures (ambient and ambient + 4°C) and water availability regimes in temperature gradient tunnels. When the measurements were taken in growth conditions, a combination of elevated CO2 and temperature enhanced the photosynthetic rate; however, when they were carried out at the same CO2 concentration (350 and 700 µmol mol−1), elevated CO2 induced photosynthetic downregulation, regardless of temperature and drought. Intercellular CO2 concentration measurements revealed that photosynthetic acclimation could not be accounted for by stomatal limitations. Downregulation of plants grown in elevated CO2 was a consequence of decreased carboxylation efficiency as a result of reduced rubisco activity and protein content; in plants grown at ambient temperature, downregulation was also induced by decreased quantum efficiency. The decrease in rubisco activity was associated with carbohydrate accumulation and depleted nitrogen availability. The root nodules were not sufficiently effective to balance the source–sink relation in elevated CO2 treatments and to provide the required nitrogen to counteract photosynthetic acclimation.

Notes: Calreticulin (CRT) is a eukaryotic, highly conserved, Ca2+-binding protein predominantly located in the endoplasmic reticulum (ER) lumen. In addition to being involved in the regulation of cellular Ca2+, calreticulin is a key quality control element during protein folding in the ER lumen. Tobacco (Nicotiana tabacum L.) suspension cells overexpressing a maize CRT (CRT1a) were used here to examine the properties of CRT in growing plant cells with respect to stress exposure. The endogenous CRT gene was induced rapidly after subculturing of the cells to new medium. In accordance, the CRT protein levels increased, peaking at days 3–4. At day 5, when the CRT transcript levels had levelled off, a further increase in endogenous CRT expression was obtained when the cells were treated with excess Ca2+ or the N-linked glycosylation inhibitor tunicamycin. Whereas the response to Ca2+ occurred within 30 min, the induction by tunicamycin took several hours to be established. Transforming tobacco cells with maize CRT1a, under a constitutive mannopine synthase promoter, resulted in a stable level of expressed CRT1a during the growth cycle compared with endogenous CRT. The CRTs showed differences in attached glycans, but both contained the high mannose-rich-type glycans characteristic of ER proteins. In agreement with an ER location, both tobacco CRT and the transgene product CRT1a codistributed with the ER marker NADH cytochrome c reductase after density gradient centrifugation of microsomal fractions from tobacco cells. Increased production of CRT, as was obtained in the transgenic tobacco cell lines, made cells more tolerant than wild-type cells to high Ca2+ during growth. These data suggest that overexpression of CRT1a in plant cells results in a more efficient calcium buffering capacity in the ER.

Notes: Cytokinins are important signalling molecules in plants, and recent studies have begun to shed light on the molecular mechanisms underlying their biosynthesis and response pathways. However, from the time of their discovery, it has been clear that cytokinins interact with other signals to regulate plant growth and development. Herein the interaction of cytokinin with three other signals: light, ethylene, and auxin is discussed. The interaction between light and cytokinin signalling, highlighted by recent analysis of cytokinin signalling mutants is reviewed. A discussion of another aspect of cytokinin cross-talk, its induction of ethylene biosynthesis in etiolated Arabidopsis seedlings, and recent studies that have begun to elucidate the mechanism underlying this regulation is also presented. Finally, there is a brief review of the interaction of auxin and cytokinin, and present novel expression profiling data of Arabidopsis seedlings treated with combinations of these two hormones, which provide insight into this interaction.

Notes: Strains of Arabidopsis thaliana that lack a DNA glycosylase to recognize and remove 7,8-dihydro-8-oxoguanine from their DNA are expected to be compromised in their ability to deal with this highly mutagenic base, which is formed in the presence of reactive oxygen species (ROS). We have identified two strains, one containing a Ds insertion in an exon of the gene that codes for oxoguanine glycosylase and one containing a T-DNA insertion in the gene that codes for formamidopyrimidine glycosylase (both EC 3.2.2.23), and have crossed them to produce the double mutant. The homozygous mutant strains showed no phenotypic difference from the wild type in growth, development or reproductive potential under either normal conditions or conditions known to induce the formation of ROS. The lack of phenotype may be ascribed to the redundant nature of the base excision repair pathway in Arabidopsis. Longer multigenerational studies may be needed to determine the quantitative selective advantage of individual DNA glycosylase genes.

Notes: The plant hormone auxin plays a crucial role in the upstream regulation of many processes, making the study of its action particularly interesting to understand plant development. In this review we will focus on the effects auxin exerts on cell cycle progression, more specifically, during the initiation of lateral roots. Auxin fulfils a dominant role in the initiation of a new lateral root primordium. How this occurs remains largely unknown. Here we try to integrate the classical auxin signalling mechanisms into recent findings on cell cycle regulation. How both signalling cascades are integrated appears to be complex and is far from understood. As a means to solve this problem we suggest the use of a lateral root-inducible system that allows investigation of the early signalling cascades initiated by auxin and leading to cell cycle activation.

Notes: Since 1995 the role of fungal hypaphorine in plants has been widely investigated and its IAA-antagonist activity recognized. Evidence of competitive antagonism includes organ development, gene expression or molecule–molecule interaction levels. Based on present knowledge, three sites of hypaphorine/IAA competition and subsequent signalling pathways have been hypothesized: the extracellular signalling pathway, the intracellular signalling pathway, and the transmembrane signalling pathway. Hypaphorine with other active indole alkaloids should be regarded as a new class of IAA antagonist finely regulating specific steps of plant growth or development.

Notes: The gene Osl2, which is specifically upregulated during leaf senescence in rice (Oryza sativa L. cv. Tainong 67), was cloned and functionally characterized. The protein coding region of the gene consists of 19 exons encoding 516 amino acids, with a putative mitochondrial targeting sequence and conserved sequence of the pyridoxal 5′-phosphate-binding domain. The recombinant Osl2 fusion protein over-expressed in Escherichia coli displays pyruvate-dependent γ-aminobutyric acid (GABA) transaminase (EC 2.6.1.19) activity. Examination of the expression patterns of the Osl2 gene in rice reveals that Osl2-specific transcripts are induced in the senescing leaves. The temporal profile of Osl2 protein accumulation is correlated with that of pyruvate-dependent GABA transaminase activity in rice leaves, with the highest expression level at the S3 senescent stage. The potential role for GABA transaminase during rice leaf senescence is discussed.

Notes: Brassinosteroids (BRs) play an essential role in plant growth and development, and have been implicated in many physiological responses. However, little is known about the role of BRs in the plant response to oxidative stress. In this study, we identified a novel insertion allele (det2-9) of the DET2 gene in Arabidopsis based on molecular, physiological and genetic approaches. We found that the det2 mutant exhibited an enhanced resistance to oxidative stress. The enhanced oxidative stress resistance in det2 plants was correlated with a constitutive increase in superoxide dismutase (SOD) activity and increased transcript levels of the defence gene catalase (CAT). To our knowledge, these results demonstrate, for the first time, that loss-of-function mutations in the DET2 gene lead to an enhanced oxidative stress resistance in Arabidopsis. A general explanation is that the long-term BR deficiency in the det2 mutant results in a constant in vivo physiological stress that, in turn, activates the constitutive expression of some defence genes and, consequently, the activities of related enzymes.

Notes: In the parasitic plant Striga hermonthica (Del. Benth), asparagine synthesis plays a prominent role in the metabolism of the host-derived nitrogen and in the detoxification process of a steady-state N-excess. Here, we show that asparagine synthetase (EC 6.3.5.4), the primary enzyme involved in asparagine production in plants, is encoded in Striga by a small gene family, with at least two AS genes, including the gene called ShAS related to the small class II Asparagine Synthetase genes. The functionality of ShAS was demonstrated by complementation of an E. coli asn auxotroph mutant and its expression was characterized by semiquantitative RT-PCR. The ShAS expression pattern in plants growing under standard light conditions and in light-grown calli differs from the expression pattern of most plant AS genes since ShAS transcripts accumulated in all the plant organs and this accumulation was not repressed by light. In contrast, ShAS expression was light-induced in mature leaves and in the chlorophyllous calli. The promoter region of ShAS was also sequenced and characterized and displayed various light-responsive, as well as potential sugar-responsive, cis-elements. A correlation between ShAS expression and asparagine synthesis was demonstrated in the illuminated mature leaves by 15N-labelling in vivo experiments. ShAS was also shown to be positively regulated in light-grown calli by C- and N-starvation and was associated with senescence-related protein breakdown. ShAS expression was not repressed by light in haustoria, roots, senescing leaves and inflorescences. These findings show that one or more unknown factors of regulation can override light as the major regulator.

Notes: Two protease activities of pea chloroplasts, one located in the stroma and the other associated to the thylakoid membrane, are described. Both proteases catalyse the endo-proteolytic cleavage of a peptide corresponding to the N-terminal loop and the first turn in helix-B of light-harvesting complex II (Lhcb1 from pea). The stromal protease cleaves preferentially on the carboxy-side of glutamic acid residues. Inhibitor studies indicate that this protease is a serine-type protease. The protease was partially purified and could be correlated to a 95-kDa polypeptide band on SDS-polyacrylamide gels. The 95 kDa protein was partially sequenced and showed similarity to an to an ‘unknown protein’ from A. thaliana (in the NCBI public database) as well as to a glutamyl endopeptidase purified from crude extract of cucumber leaves. It is concluded that the stromal protease is a chloroplast glutamyl endopeptidase (cGEP). The protease localized in the thylakoid membrane, cleaved the peptide at only one site, close to its N terminus. The activity of the thylakoid-associated protease was found to be drastically increased in the presence of the reducing agent 1,4-dithiothreitol. Inhibitor studies suggest that this protease is a cysteine- or serine-type protease. The possible roles of these proteases in the regulation of photosynthetic electron transport and in the chloroplast homeostasis are discussed.

Notes: The effects of salicylic acid (SA) and hydrogen peroxide (H2O2) on freezing tolerance were studied in two potato (Solanum tuberosum) cultivars (Alpha and Atlantic) that differ in cold sensitivity, Alpha being more tolerant to freezing than Atlantic. Lowest freezing survival rates were observed in 4-week-old plants. Freezing treatments consisting of exposure to 6° C for 4 h in the dark were applied 24 h after plants had been transferred from in vitro culture to soil. Catalase activity and H2O2 were estimated at the following harvest points: stage (a) 4-week-old in vitro plants treated with either 0.1 mM SA or 5 mM H2O2; stage (b) as in (a) but 24 h following transfer to soil prior to freezing treatment; stage (c) as in (b) but measured 15 days after a 4-h freezing treatment. The results show that (1) SA induced freezing tolerance in both cultivars; (2) SA inhibited ascorbate peroxidase activities in both cultivars at all harvest points but inhibited catalase activities in only at stage (a); (3) SA induced H2O2 accumulation only in Atlantic at stage (a); (4) H2O2 enhanced shoot catalase activities in Atlantic at stages (a) and (b) whereas this treatment had no effect on shoot catalase activities in Alpha; (5) H2O2 treatment induced freezing tolerance in Atlantic, even though shoot catalase activities were lower than those of the controls following exposure to freezing temperatures. We conclude that SA does not always lead to H2O2 accumulation even though catalase and ascorbate peroxidase activities are decreased as a result of the treatment. Moreover, H2O2 accumulation is not always associated with the induction of freezing tolerance, for example at stage (a) where SA-induced tolerance in Alpha was not accompanied by H2O2 accumulation. H2O2 was able to induce freezing tolerance only in Atlantic, even though H2O2 accumulated in both cultivars following this treatment.

Notes: Wounding, as during excision and preparation of lettuce (Lactuca sativa L.) leaf tissue for salads, induces the synthesis and accumulation of phenolic compounds that participate in subsequent reactions that cause tissue browning. Exposure of excised 5-mm mid-rib segments of romaine lettuce leaf tissue to vapors of mono-carboxylic acids or aqueous solutions of mono-carboxylic acids or their salts inhibited wound-induced phenolic accumulation (WIPA) and subsequent tissue browning. The decline in phenolic content followed a quadratic curve with increasing concentration, reaching a maximum inhibition after 60 min of 74 ± 8% for 50 mM sodium acetate (2 carbons, C2) and 91 ± 4% for 20 mM sodium decanoate (capric acid, C10). Respiration (i.e. carbon dioxide production) was unaffected by concentrations of formic, acetic, or propionic acids that reduced wound-induced phenolic content or that increase ion leakage from the tissue into an isotonic mannitol solution. However, WIPA was suppressed up to 70% at concentrations (20 mM acetate) that did not increase ion leakage over that of water controls. Various acetate salts (i.e. ammonium, calcium, magnesium, and sodium) all produced the same level of inhibition. The effectiveness of the compounds increased with increasing number of carbons in the molecule from 1 to 10, and was unaffected by whether the carbons were a straight chain or branched or whether the treatment was delayed by up to 6 h. The effectiveness of butyrate (C4) in reducing WIPA (27% reduction at 20 mM) was less than that predicted from the response of the two adjacent mono-carboxylates similarly applied: propionate (C3) (62%) and valerate (C5) (73%). It appears that, unlike the n-alcohols, mono-carboxylates are not interfering with the synthesis or propagation of a wound signal but are interfering with subsequent steps in the production and accumulation of wound-induced phenolic compounds.

Notes: The plant-specific insert (PSI) of cypro11 gene-encoding cyprosin, an aspartic proteinase from Cynara cardunculus, has been cloned by polymerase chain reaction (PCR) into a bacterial expression vector. A rearranged form of this PSI in which the N- and C-terminal sequences were permutated to make it more similar to the structural arrangement observed in saposins was also cloned and expressed in the same system. The biological activities of the two purified recombinant proteins were compared to those of human saposins B and C. The proteins showed similar activity to saposin C, i.e. capacity to activate human glucosylceramidase. At a concentration of 5 µM, wild-type PSI, saposin C, and rearranged PSI activated human glucosylceramidase two-, three-, and five-fold, respectively. The Km for 4-methylumbelliferyl β-glucopyranoside was around 7 µM in the presence of any of the three activators (5 µM). The neurotropic activity using NS20Y cells and lipid-binding properties of the plant recombinant proteins were tested. The two plant proteins showed lipid-binding properties similar to those of saposins but did not have any effect on neurite outgrowth. Immunolocalization of PSI showed its expression in protective tissues in flower meristem – protodermis, in C. cardunculus and embryonic root cap and coleorhiza in mature barley grains – as well as husk, pericarp, and the aleurone layer. Possible biological functions suggested for the plant homologue to saposins besides the general activation of enzymes involved in lipid metabolism would be involvement in plant defence.

Notes: Although it has long been recognized that water deficit in plants reduces photosystem (PS) II mRNAs and proteins, the detailed mechanisms behind this have not been thoroughly elucidated. In the present study, effects of water stress in barley leaves on degradation of major PSII mRNA and dissociation and migration of PSII proteins were investigated. The results indicated that (1) the steady-state levels of major PSII mRNAs and proteins declined with increasing water stress, as a consequence of increased degradation; under severe water stress, the half-lives of D1 and D2 proteins decreased from 12–14 h to 7–8 h and the half-lives of psbA and psbD mRNA decreased from above 16 to 6–10 h; (2) monomerization of PSII were increased during water stress. Severe water stress accelerated turnover of PSII and inhibited PSII activities.

Notes: Elevated atmospheric CO2 concentration [CO2] and different levels of nitrogen (N) nutrition can influence the amount of excess excitation energy in photosystem (PS) II and related photosynthetic properties. The interactive effect of two [CO2] levels (ambient: 360 µM M−1 and elevated: 720 µM M−1) and two N levels (high: 700 mg N plant−1 and low: 100 mg N plant−1) on these properties was examined in seedlings of Japanese white birch (Betula platyphylla var. japonica) using simultaneous measurements of gas exchange and chlorophyll fluorescence. Photosynthetic acclimation to elevated [CO2], as indicated by a decline in carboxylation efficiency (CE), was observed in plants grown at elevated [CO2] especially under low N. Elevated [CO2] resulted in a decrease in area-based leaf N content (Narea) irrespective of N treatment. The adverse effect of elevated [CO2] and low N on CE may have been exacerbated by a greater accumulation of leaf sugar and starch contents in these plants leading to a lower electron transport rate (ETR). While these plants also showed higher non-photochemical quenching (NqP) that could offset the reduction in energy dissipation through ETR to some extent, they still have a higher risk of photoinhibition from excessive excitation energy in PSII as indicated by a decrease in photochemical quenching (qP). However, chronic photoinhibition was not observed in plant grown at elevated [CO2] and low N because they showed no difference in Fv/Fm (the maximum photochemical efficiency of PSII) from those grown at ambient [CO2] and low N after an overnight dark adaptation. High levels of NqP in plants grown at elevated [CO2] and low N reflect a near saturation of thermal energy dissipation. This impaired capacity of photoprotection would render these plants more vulnerable to photoinhibition in the event of additional environmental stresses such as drought, low or high temperature.

Notes: SULTR2;1 is a low-affinity sulfate transporter expressed in the vascular tissues of roots and leaves for interorgan transport of sulfate in Arabidopsis thaliana. Transgenic Arabidopsis carrying a fusion gene construct of SULTR2;1 5′-promoter region and β-glucuronidase coding sequence (GUS) demonstrated that within the reproductive tissues, SULTR2;1 is specifically expressed in the bases and veins of siliques and in the funiculus, which connects the seeds and the silique. The antisense suppression of SULTR2;1 mRNA caused decrease of sulfate contents in seeds and of thiol contents both in seeds and leaves, as compared with the wildtype (WT). The effect of antisense suppression of SULTR2;1 on seed sulfur status was determined by introducing a sulfur-indicator construct, p35S::βSRx3:GUS, which drives the expression of GUS reporter under a chimeric cauliflower mosaic virus 35S promoter containing a triplicate repeat of sulfur-responsive promoter region of soybean β-conglycinin β subunit (βSRx3). The mature seeds of F1 plants carrying both the SULTR2;1 antisense and p35S::βSRx3:GUS constructs exhibited significant accumulation of GUS activities on sulfur deficiency, as compared with those carrying only the p35S::βSRx3:GUS construct in the WT background. These results suggested that SULTR2;1 is involved in controlling translocation of sulfate into developing siliques and may modulate the sulfur status of seeds in A. thaliana.

Notes: Changes in the amount and composition of cell wall constituents in response to continuous hypergravity stimuli were studied in wheat (Triticum aestivum L.) coleoptiles. The lengths of coleoptiles grown under hypergravity (300 g) conditions for 2–4 days from germination stage were 60–70% of those of 1 g control. However, the net amounts of hemicellulosic polysaccharides and cellulose in hypergravity-treated coleoptiles increased progressively as much as those in the control coleoptiles. As a result, their contents per unit length of coleoptile largely increased under hypergravity conditions. In the hemicellulose fraction, the amounts of arabinose and xylose, the major components of the fraction, prominently increased in response to hypergravity. When hemicellulosic polysaccharides were separated into neutral and acidic polymers by an anion-exchange column, the amounts of the acidic fraction consisting of (glucurono)arabinoxylans were higher in hypergravity-treated coleoptiles than in control coleoptiles. The amounts of cell wall-bound ferulic acid and diferulic acid (DFA) increased dramatically in both 1 g control and hypergravity-treated coleoptiles. Particularly, the amounts of DFA in hypergravity-treated coleoptiles were significantly higher than those in control coleoptiles during the incubation period. These results suggest that continuous hypergravity increases the rigid network structures via arabinoxylan–hydroxycinnamate cross-links within cell wall architecture in wheat coleoptiles. These structures may have a load-bearing function and contribute to construct the stable cell wall against the gravitational force.

Notes: Carbon isotope ratio of leaf dry matter, δ13C, was measured on species occurring within Baiyin desert community, consisting of valley, slope and ridge microhabitats, and within Shandan desert community, consisting of Gobi desert and seasonal flooded creek microhabitats, in Northwest China. δ13C of C3 species increased with a decrease in soil water availability, suggesting that water-use efficiency (WUE) increased with decreasing soil moisture, whereas for all C4 species, δ13C tended to decrease with decreasing soil water availability, suggesting that WUE also increased with decreasing soil moisture. Above results indicated that water-use pattern was conservative under drought for C4 and C3 plants. In this present study, C4 species' occurrences within different microhabitats were investigated and C4 plants were observed to be absent and/or scarce within relatively lower soil moisture microhabitats, whereas they occurred and/or even had a high abundance within relatively higher soil moisture microhabitats, suggesting limited moisture available was a key factor of limiting C4 distribution in arid region of Northwest China.

Notes: The expression of totipotency in plant protoplasts is a complex developmental phenomenon and is affected by genetic and physiological factors. Polyamines (PAs) are known to be involved in a variety of growth and developmental processes in higher plants, as well as in adaptation to stresses. In this study, we present the homeostatic characteristics of the endogenous PA putrescine (Put), spermidine (Spd), and spermine (Spm) in totipotent (T) and non-totipotent (NT) tobacco protoplasts and in recalcitrant (R) grapevine protoplasts. T-tobacco protoplasts, with high division rates, have the highest level of endogenous PAs. In these protoplasts, the soluble-hydrolyzed fraction predominates and increases, and the insoluble-hydrolyzed fraction also increases, whereas soluble (S) PAs decrease rapidly during culture. The isolation process contributes to the increased Put levels, which are higher in freshly isolated NT-tobacco protoplasts than in T-protoplasts. During culture, total Put predominates over Spd and Spm, and the highest accumulation is found in T-protoplasts. Ornithine decarboxylase and arginase activities both increase in T-protoplasts, whereas arginine decarboxylase activity causes Put accumulation in NT-tobacco protoplasts. R-grapevine protoplasts show a different PA profile, mostly due to the lower PA content, the higher S-fraction, and the higher ratio of Spm to total PAs. The data suggest that the levels and metabolism of the intracellular PAs could be related to the expression of totipotency of plant protoplasts.

Notes: Temperature is one of the abiotic factors limiting growth and productivity of plants. In the present work, the effect of low non-freezing temperature, as inducer of ‘cold acclimation’, was studied in poplar. Actively growing plantlets of Populus tremula × Populus tremuloides cv. Muhs 1 were used, and cold treatment consisted in whole plants exposure to 4°C in controlled conditions. Leaves of cold-treated poplars were shown to be acclimated, as an increase of their freezing tolerance was measured using electrolyte leakage. Chlorophyll fluorescence measurements revealed a decrease in photosystem II efficiency while the pigment contents of leaves did not vary. In contrast, after 1 week of cold exposure, an accumulation of pigments was noted in the stems near the apex of the stressed plants as confirmed by chromatographic analyses. Simultaneously, a rapid accumulation of osmoprotectants, i.e. carbohydrates (measured by spectrometry), and of stress indicators (e.g. putrescine) occurred; changes in protein patterns also arose. Indeed, Western blot studies revealed that the expression of three families of stress-related proteins, i.e. dehydrins, stress protein 1 and heat-shock protein 70, was activated or induced by low temperatures. This study complements a previous work on proteomic and individual carbohydrates and provides insight in the ability of poplar plantlets to cold acclimate and to cope with low temperatures by diverse mechanisms (growth cessation, carbohydrate, pigment, polyamine and protein accumulations) related to stress response or involved in acclimation process.

Notes: The expression and activity of type 1 NAD(P)H dehydrogenase (NDH-1) were investigated in Synechocystis PCC 6803 cells during different growth phases (i.e. lag, logarithmic, stationary and decline phases). The relative amount of NDH-1, estimated by Western blot analysis using antibodies against NdhH, NdhI and NdhK, increased more than two-fold during growth from the lag to the logarithmic phase and then decreased after the logarithmic phase to reach lowest levels after 15 days (decline phase). The activity of light-dependent NADPH oxidation and cyclic electron flow around photosystem I (PSI) changed nearly in parallel with the amount of NdhH, NdhI and NdhK in cells across the growth phases. In contrast, the activity of photosynthetic O2 evolution and respiratory O2 uptake was not significantly different across phases of growth; the fluctuation of the activity at different phases was within 40%. These results suggested that the activity of light-dependent NADPH oxidation and PSI-cyclic electron flow are restricted by the amount of NDH-1 and that other factor(s) are limiting the rates of photosynthesis and respiration.

Notes: Arabidopsis thaliana is, perhaps, the most important model species in modern plant biology. However, the isolation of organelles from leaves of this plant has been difficult. Here, we present two different protocols for the isolation of mitochondria, yielding either highly functional crude mitochondria or highly purified mitochondria. The crude mitochondria were well coupled with the substrates tested (malate + glutamate, glycine and NADH), exhibiting respiratory control ratios of 2.1–3.9. Purified mitochondria with very low levels of chlorophyll contamination were obtained by Percoll gradient centrifugation, yielding 1.2 mg of mitochondrial protein from 50 g of leaves.

Notes: A new technique for generating xylem cavitation and vulnerability curves was evaluated. The centrifugal force was used to lower the negative pressure in a xylem segment and to induce a positive pressure difference between sample's ends. This enabled the determination of sample hydraulic conductance during centrifugation and, hence, its variation with decreasing xylem pressures. The centrifuge technique was compared with standard methods on a large number of species including conifers, diffuse-porous and ring-porous woody angiosperms. A very good agreement was found for coniferous and diffuse-porous species. However, the technique was not appropriate for ring-porous species, probably because many vessels were cut open in the centrifuged xylem segments. The main advantage of this technique is its rapidity, the vulnerability curve of a xylem segment being constructed typically in less than half an hour. This will greatly facilitate the study of xylem cavitation in ecological or genetic researches.

Notes: When grown at a low P supply, Hakea prostrata R.Br. (Proteaceae) develops dense clusters of determinate branch roots, termed ‘proteoid’ or ‘cluster’ roots and accumulates Mn in its leaves. The aim of this study was to vary the production of cluster roots and assess the relationship between Mn uptake and cluster-root mass. We collected native soil from a location inhabited by H. prostrata and amended this with ‘high’ and ‘low’ amounts of insoluble or soluble P. After 14 months, we measured the impact of the treatments on cluster-root development and the [P], [Mn], [Fe], [Zn] and [Cu] in young (expanding) and mature leaves. Dry mass and leaf area increased with increasing P availability in the soil, but growth decreased at the highest soluble [P], which caused symptoms of P toxicity. The [P] in young leaves (1.3–2.7 mg g−1 DM) exceeded that in older leaves (0.28–0.85 mg g−1 DM), except when plants were grown with soluble P (3.2–21 mg g−1 DM). Cluster-root formation was inhibited when leaf [P] increased; [P] in young leaves, rather than that in old leaves, appeared to be the factor that determined the proportion of the root mass invested in cluster roots. Old leaves of all treatments had [Mn] from 90 to 120 µg g−1 DM, except for plants grown at high levels of soluble P, when [Mn] decreased below 30 µg g−1 DM. The [Mn] and [Zn] in old leaves and the [Cu] in young leaves were positively correlated with the fraction of roots invested in cluster roots. These findings support our hypothesis that cluster roots play a significant role in micronutrient acquisition, and also provide an explanation for Mn accumulation in leaves of H. prostrata, and presumably Proteaceae in general.

Notes: The major components of the scent of cut sweet pea flowers (Lathyrus odoratus L. cv Royal Wedding) are (E) and (Z)-ocimene, linalool, nerol, geraniol and phenylacetaldehyde. The aroma is almost exclusively produced by the standard and wing petals, with very little emanating from the keel petals and other floral structures. Only traces of these volatiles were detected in the liquid excreted by glandular trichomes on the surface of the scented petals. Once flowers are cut for display they produce increasing amounts of ethylene which induces wilting after 48 h and petal abscission 24 h later. The rate of linalool and ocimene emission declines over the first 48 h to approximately 10% of that directly after harvest. Ethylene production is not saturating during the first 24 h of vase life and exogenous ethylene further accelerates the senescence processes and loss of fragrance. Addition of the ethylene antagonists 1-methylcyclopropene (1-MCP) and silver thiosulphate (STS) delayed wilting and abscission for several days and similarly inhibits the decline in terpenoid emission.

Notes: The response of superoxide dismutases (SOD, EC1.15.1.1) to chilling-induced oxidative stress in differentially sensitive maize genotypes (Zea mays L) was examined. A native 2D-PAGE system that resolves the maize leaf SOD isoforms has been developed. The chloroplastic SOD activity was resolved into four Cu/Zn SOD isoforms designated SOD1a→d with pI values of 3.9, 4.0, 4.5 and 5.6, respectively. These SODs are located in the stroma and display a higher resistance to hydrogen peroxide inactivation than the cytosol Cu/ZnSODs. They operate as 32 kDa homodimers and have an AT motif at the NH2-terminal, which characterizes the chloroplastic SODs of most species. A light chilling treatment resulted in a rapid increase in the activity of SOD1a and SOD1b. Because this increase was observed in the presence of the protein synthesis inhibitor cycloheximide, it is suggested that short-term regulation of chloroplastic SODs occurs at a post-translational level.

Notes: Leaf tensile strength was measured for the drought-tolerant grass Eragrostis curvula and the desiccation-tolerant grass E. nindensis when fully hydrated, partially dehydrated, naturally air-dried, and flash-dried. Leaf tensile strength increased in intact, air-dried leaves of E. curvula but not for similarly treated leaves of E. nindensis. Examination of leaf cross-sections by light microscopy and histochemical staining for lignins failed to show any significant structural differences between the two species in the hydrated state. When leaves were flash-dried, the tensile strength of E. curvula remained unchanged from leaves dried naturally, while there was a marked increase in the tensile strength of flash-dried leaves of E. nindensis. Proton NMR indicated that the desiccation-tolerant E. nindensis retained mobile water when leaf relative water content was less than 20% if dried naturally but not if flash-dried, whereas no mobile water was detected in leaves of E. curvula when dried either naturally or with flash-drying to below 20% relative water content. This behaviour suggests a fundamental difference in strategy for surviving water loss in vegetative tissues between desiccation-tolerant species and drought-tolerant species.

Notes: Among the longest cell types known in plants, cotton fibers are economically important seed trichomes that provide a unique single-celled model system for studying fundamental biological processes. Functional genomic approaches have served to characterize dynamic changes to the cotton fiber transcriptome in response to developmental signals that control fiber morphogenesis at the level of a single cell. The genetic complexity of the fiber transcriptome is very high and accounts for as much as 45–50% of the genes in the cotton genome. In addition to a large diverse group of constitutively expressed genes, expression profiling of the transcriptome revealed two developmentally regulated stage-specific expression patterns that define rapid cell elongation during primary cell wall (PCW) synthesis relative to secondary cell wall biogenesis. In developing cotton fibers, many fiber genes involved in PCW synthesis and turgor-driven cell expansion are differentially expressed in a manner that parallels the growth rate. Characterization of the cotton fiber transcriptome has immediate applications in agricultural biotechnology and molecular breeding programs geared toward the genetic improvement of yield and fiber quality.

Notes: Variegation in the immutans (im) mutant of Arabidopsis is induced by a nuclear recessive gene. The white leaf sectors of im contain abnormal plastids lacking pigments and organized lamellae, whereas the green leaf sectors possess normal-appearing chloroplasts. IMMUTANS codes for a thylakoid membrane terminal oxidase that functions as a safety valve to dissipate excess energy. Previous studies have shown that the green sectors of im, regardless of illumination conditions, have anatomical adaptations that are reminiscent of acclimation to high-light stress. It has been suggested that these adaptations provide a means of enhancing photosynthesis to feed the white sectors and maximize plant growth. We have utilized Chl fluorescence imaging to better understand these compensatory mechanisms using, as our experimental material, im leaves with predominantly green (img) or predominantly white (imw) tissues. The samples were examined under conditions of normal growth or high-light stress (photoinhibition). Steady-state fluorescence quenching revealed that the green sectors of the imw leaves had lower levels of 1 − qp than the img leaves, and that this was accompanied by increased electron transport rates. In response to short-term high-light exposure, the green sectors of the imw leaves displayed enhanced non-photochemical quenching (NPQ), which correlated with increased xanthophyll pool sizes and increased amounts of several different Lhcb polypeptides and the PsbS protein. In summary, our data show that, compared with primarily green leaves (img), the green sectors of predominantly white leaves (imw) have elevated rates of electron transport and an enhanced NPQ capacity. We conclude that, in the absence of IM, green sectors develop morphological and biochemical adaptations that allow them to maximize photosynthesis to feed the white sectors, and to protect against photodamage.

Notes: The effects of exogenous application of glycinebetaine (GB) (10 mM) on growth, leaf water content, water use efficiency, photosynthetic gas exchange, and photosystem II photochemistry were investigated in maize plants subjected to salt stress (50 and 100 mM NaCl). Salt stress resulted in the decrease in growth and leaf relative water content as well as net photosynthesis and the apparent quantum yield of photosynthesis. Stomatal conductance, evaporation rate, and water use efficiency were decreased in salt-stressed plants. Salt stress also caused a decrease in the actual efficiency of PSII (ΦPSII), the efficiency of excitation energy capture by open PSII reaction centers (Fv′/Fm′), and the coefficients of photochemical quenching (qP) but caused an increase in non-photochemical quenching (NPQ). Salt stress showed no effects on the maximal efficiency of PSII photochemistry (Fv/Fm). On the other hand, in salt-stressed plants, GB application improved growth, leaf water content, net photosynthesis, and the apparent quantum yield of photosynthesis. GB application also increased stomatal conductance, leaf evaporation rate, and water use efficiency. In addition, GB application increased ΦPSII, Fv′/Fm′, and qP but decreased NPQ. However, GB application showed no effects on Fv/Fm. These results suggest that photosynthesis was improved by GB application in salt-stressed plants and such an improvement was associated with an improvement in stomatal conductance and the actual PSII efficiency.

Notes: Methyl salicylate (MeSA) is thought to have a major role in biotic and abiotic stresses by acting as a signal to trigger the oxidative burst, which is needed to activate gene expression in plant stress responses. To assess the potential effects of sustained foliar accumulation of MeSA on plant stress tolerance, the extent of photo- and antioxidant protection, lipid peroxidation and visual leaf area damage were evaluated in MeSA-treated (c. 60 nl l−1 in air) and control holm oak (Quercus ilex L.) plants exposed to heat stress. Control plants showed an increase in foliar MeSA levels up to 1.8 nmol [gDW]−1 as temperature increased and they displayed tolerance to temperatures as high as 45°C, which might be attributed, at least in part, to enhanced xanthophyll de-epoxidation and increases in ascorbate and α-tocopherol. MeSA-treated plants showed a sustained foliar accumulation of this compound, with values ranging from 10 to 23 nmol [gDW]−1 throughout the experiment. These plants showed lower ascorbate and tocopherol levels and higher oxidative damage at 50°C than controls, as indicated by enhanced malondialdehyde levels and leaf area damage and lower maximum efficiency of PSII photochemistry (Fv/Fm ratio). These results demonstrate that a sustained foliar accumulation of MeSA is detrimental to plant function and that it can reduce thermotolerance in holm oak by altering antioxidant defences.

Notes: Grain filling of rice (Oryza sativa L.) is thought to be affected not only by the supply of carbohydrate from source organs, but also by sink activity, including the activities of enzymes related in starch synthesis. To examine the effect of translocated carbohydrate on sink activity, we cultured detached ears (cut 7 days after flowering) in a solution containing sucrose at various concentrations, glutamine and vitamins. Grain weights 16 days after the start of ear culture increased with increasing sucrose concentration up to 50–70 g sucrose l−1, but not above this range, probably because of low water potential. Activities of ADP glucose pyrophosphorylase, soluble starch synthase and sucrose synthase rapidly decreased in grains grown without sucrose, but increased with increasing sucrose concentration up to 50–70 g l−1. Expression of mRNAs for these enzymes and for sucrose transporter was also generally increased by sucrose at 50–70 g l−1. Though there was a good correlation between activity and expression of mRNA for sucrose synthase, the correlation for other enzymes was not very good. Thus, we suggested that the sink activity of grains in rice ears, and therefore the grain filling, was affected by the supply of carbohydrate from source organs, and that it was also owing to factors other than transcriptional regulation.

Notes: The virescent character is a genetic variant in pigmentation characterized by a delay in greening. Seedlings of the virescent mutants v1, v2, v3, v4, v13, v16, v18, v19 and v26 of maize exhibit chlorosis when grown at low temperature. Chlorotic leaves contain plastids that appear to have been arrested at an early stage of development. The results indicated that V16, V2, V3 and V4 loci control early stages of chloroplast development while V1, V13 and V19 may play a role at the end of development. The mutations in the V18 and V26 loci may control an intermediate step. At the pigment level, the virescent mutants of maize differ widely from analogous mutations existing in other plants. The mutations were characterized by a reduced amount of chlorophyll a and b (up to 100 times in v16) and chlorophyll a/b ratio above normal (up to 13.7 in v16). Lutein content was reduced in all mutants (less than 3% in v16 compared to wild type) but v13, while pigments of the xanthophyll cycle were found at higher levels in v1 and v13 (more than 10 and 90%, respectively). The v2, v3, v4, v16 and v18 mutants that are most depleted in β-carotene (36 times less in average than wild type) are also deprived in D1 and D2 polypeptides. Moreover, the v2, v3, v4, v16 and v18 mutants characterized by a lower accumulation in lutein are most depleted of light-harvesting complex II. All mutants possess a functioning, fully reversible, non-photochemical quenching mechanism. This is most developed in the v13 and v19 mutants (φn = 0.48 and 0.44, respectively). These two mutants also have a relatively high primary photochemical yield for photosystem II and a functioning photosystem I (φp = 0.23 and 0.39, respectively). The most interesting mutant is v13 that shows severe chlorosis and possesses the most effective non-photochemical quenching mechanism(s), which is thought to provide protection against excess photon absorption by photosystem II.

Notes: Sink activity of fruits had been suggested to vary depending on transpiration of fruits. In this study, the effect of transpiration on dry matter accumulation was evaluated in tomato (Lycopersicon esculentum Mill.). Fruits of cv. Saturn at 14 days after anthesis were enclosed in chambers and aerated with dried (〈15% RH) or moistened (〉90% RH) air. These treatments did not cause any significant differences in fruit fresh weight, dry weight, percentage of dry matter, and concentration of soluble sugars within 5 days of the treatment, or the import of 14C within 18 h after the application of 14CO2 to the source leaves. However, displacement transducer measurement of each fruit showed a 40% reduction in growth rate in response to exchange of moistened air with dried air. When fruits of cv. Momotaro were exposed to transpiration treatments from the beginning of visible fruit enlargement until the ripening stage, the fruits exhibited 20% reduction in growth and lower accumulation of dry matter at harvest following treatment with dried air. These results suggested that higher transpiration reduced both water accumulation and dry matter accumulation. In contrast, when fruit growth was mechanically restricted by enclosing the fruits in a chamber packed with glass beads, and dried or moistened air was passed through the spaces between the glass beads, fruits exhibited higher dry matter accumulation under dried air treatment conditions. The results show that only under artificial conditions would transpiration of fruits potentially drive carbohydrate transport; it does not serve as a limiting step of carbohydrate transport to tomato fruits under normal circumstances.