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PubMed2004

Contaminant exposure and effects in red-winged blackbirds inhabiting stormwater retention ponds.

Stormwater wetlands are created to retain water from storms and snow melt to reduce sediment, nutrient, and contaminant pollution of natural waterways in metropolitan areas. However, they are often a source of attractive habitat to wetland-associated wildlife. In this study of 12 stormwater wetlands and a larger, older reference site, elevated concentrations of zinc and copper were found in sediments and carcasses of 8-day-old red-winged blackbird (Agelaius phoeniceus) nestlings inhabiting stormwater sites. Although nesting success in the stormwater wetlands was comparable to national averages, sediment zinc concentrations correlated with clutch size, hatching success, fledgling success, and Mayfield nest success, suggesting that the nestlings may have been stressed and impaired by elevated zinc. This stress may have been direct on the nestlings or indirect through effects on the availability of food organisms.

Animals↗
PubMed2001

[Posterior uveitis: sarcoidosis or tuberculosis].

PURPOSE: To demonstrate the difficulties of the differential diagnosis between tuberculosis and sarcoidosis as the cause of posterior uveitis. CASE REPORTS: A 56-year-old woman suffered from bilateral anterior uveitis, snow-ball like infiltrates in the vitreous, and peripheral retinochoroidal granulomas with marked exudation shown in fluorescein angiography. Angiotensin-converting enzyme, as a marker of sarcoidosis, was elevated; the tuberculin test, however, was negative. Chest X-ray revealed an infiltrate and numerous smaller granulomas. The presumptive diagnosis was sarcoidosis. Surprisingly, in the biopsy of the pulmonal lesion tubercle bacilli were detected by Ziehl-Neelsen staining. Thus, a diagnosis of pulmonal and also retinochoroidal tuberculosis was made. After tuberculostatic therapy the choroidal lesions healed off. In a second case, a 30-year-old man suffered from bilateral panuveitis with candle wax exudates near the retinal vessels. Chest X-ray revealed lymphomas in the hilus, and the lymph node biopsy showed granulomas with epitheloid cells, indicating sarcoidosis. Detection of mycobacterium tuberculosis by culture or histological criteria was negative. Only in the PCR was mycobacterium tuberculosis DNA detectable. Tuberculostatic therapy had no benefit. Under therapy with steroids, however, pulmonal and ophthalmologic findings rapidly disappeared. CONCLUSION: The difficult differential diagnosis between sarcoidosis and tuberculosis cannot always be made by laboratory tests or diagnostic imaging alone. Clinical manifestations, including response to therapy, are essential.

Adult↗
PubMed2002

Fallout radiocesium in an Antarctic region: deposition history, activity densities and vertical transport in soils.

To improve the knowledge about the (137)Cs spatial distribution and vertical migration in soils of the Southern Hemisphere, the total areal activity density and the vertical transport parameters of this radionuclide were measured in an Antarctic region. For this purpose vegetation and incremental soil samples were collected at 21 representative sites located at 4 islands of the South Shetland Archipelago: King George, Robert, Greenwich and Snow (62-63 degrees S and 58-62 degrees W). The total (137)Cs activity density varied considerably from 118 to 662 Bq m(-2) (median 384 Bq m(-2), reference date 1995), with a high percentage of the total activity retained in the vegetation cover (5-98% in moss, 3-20% in lichen and 4-12% in grass). At most sites, the maximum activity density in soil was observed in the top layer from where it decreased continuously. To evaluate the transport parameters of (137)Cs from the activity-depth profiles, the classical convection-diffusion model was used based on the time-course of the annual deposition density of (137)Cs at the studied region. The values for the diffusion coefficient D(s) (median 0.043 cm(2) year(-1)) and the convection velocity v(s) (median -0.012 cm year(-1)) of radiocesium observed under a polar climate are small compared to the transport parameters determined in temperate zones. The data also indicate that at these sites the convectional transport of (137)Cs is almost negligible compared to the transport by diffusion. The high vulnerability of the Antarctic soils to (137)Cs deposition, as a consequence of its very slow transport due to the extreme climatic conditions at these latitudes, has been confirmed.

Antarctic Regions↗
PubMed2005

Fructan:fructan 1-fructosyltransferase, a key enzyme for biosynthesis of graminan oligomers in hardened wheat.

Fructans play important roles not only as a carbon source for survival under persistent snow cover but also as agents that protect against various stresses in overwintering plants. Complex fructans having both beta-(2,1)- and beta-(2,6)-linked fructosyl units accumulate in wheat (Triticum aestivum L.) during cold hardening. We detected fructan: fructan 1-fructosyltransferase (1-FFT; EC 2.4.1.100) activity for catalyzing the formation and extension of beta-(2,1)-linked fructans in hardened wheat tissues, cloned cDNAs (wft3 and wft4) of 1-FFT, and analyzed the enzymatic properties of a wft3 recombinant protein (Wft3m) produced by yeast. Wft3m transferred beta-(2,1)-linked fructosyl units to phlein, an extension of sucrose through beta-(2,6)-linked fructosyl units, as well as to inulin, an extension of sucrose through beta-(2,1)-linked fructosyl units, but could not efficiently synthesize long inulin oligomers. Incubation of a mixture of Wft3m and another recombinant protein of wheat, sucrose:fructan 6-fructosyltransferase (6-SFT), with sucrose and 1-kestotriose produced fructans similar to those that accumulated in hardened wheat tissues. The results demonstrate that 1-FFT produces branches of beta-(2,1)-linked fructosyl units to phlein and graminan oligomers synthesized by 6-SFT and contributes to accumulation of fructans containing beta-(2,1)- and beta-(2,6)-linked fructosyl units. In combination with sucrose:sucrose 1-fructosyltransferase (1-SST; EC 2.4.1.99) and 6-SFT, 1-FFT is necessary for fructan synthesis in hardened wheat.

Amino Acid Sequence↗
PubMed2002

Mechanisms promoting higher growth rate in arctic than in temperate shorebirds.

We compared prefledging growth, energy expenditure, and time budgets in the arctic-breeding red knot (Calidris canutus) to those in temperate shorebirds, to investigate how arctic chicks achieve a high growth rate despite energetic difficulties associated with precocial development in a cold climate. Growth rate of knot chicks was very high compared to other, mainly temperate, shorebirds of their size, but strongly correlated with weather-induced and seasonal variation in availability of invertebrate prey. Red knot chicks sought less parental brooding and foraged more at the same mass and temperature than chicks of three temperate shorebird species studied in The Netherlands. Fast growth and high muscular activity in the cold tundra environment led to high energy expenditure, as measured using doubly labelled water: total metabolised energy over the 18-day prefledging period was 89% above an allometric prediction, and among the highest values reported for birds. A comparative simulation model based on our observations and data for temperate shorebird chicks showed that several factors combine to enable red knots to meet these high energy requirements: (1) the greater cold-hardiness of red knot chicks increases time available for foraging; (2) their fast growth further shortens the period in which chicks depend on brooding; and (3) the 24-h daylight increases potential foraging time, though knots apparently did not make full use of this. These mechanisms buffer the loss of foraging time due to increased need for brooding at arctic temperatures, but not enough to satisfy the high energy requirements without invoking (4) a higher foraging intake rate as an explanation. Since surface-active arthropods were not more abundant in our arctic study site than in a temperate grassland, this may be due to easier detection or capture of prey in the tundra. The model also suggested that the cold-hardiness of red knot chicks is critical in allowing them sufficient feeding time during the first week of life. Chicks hatched just after the peak of prey abundance in mid-July, but their food requirements were maximal at older ages, when arthropods were already declining. Snow cover early in the season prevented a better temporal match between chick energy requirements and food availability, and this may enforce selection for rapid growth.

Adaptation, Physiological↗
PubMed2003

Landscape effects on temporal and spatial properties of vole population fluctuations.

Populations of northern small rodents have previously been observed to fluctuate in spatial synchrony over distances ranging from tens to hundreds of kilometers between sites. It has been suggested that this phenomenon is caused by common environmental perturbations, mobile predators or dispersal movements. However, very little focus has been given to how the physical properties of the geographic area over which synchrony occurs, such as landscape composition and climate, affect spatial population dynamics. This study reports on the spatial and temporal properties of vole population fluctuations in two areas of western Finland: one composed of large interconnected areas of agricultural farmland interspersed by forests and the other highly dominated by forest areas, containing more isolated patches of agricultural land. Furthermore, the more agricultural area exhibits somewhat milder winters with less snow than the forested area. We found the amplitude of vole cycles to be essentially the same in the two areas, suggesting that the relative amount of predation on small rodents by generalist versus specialist predators is similar in both areas. No seasonal differences in the timing of synchronization were observable for Microtus voles, whereas bank vole populations in field habitats appeared to become synchronized primarily during winter. Microtus populations in field habitats exhibited smaller spatial variation and a higher degree of synchrony in the more continuous agricultural landscape than in the forest-dominated landscape. We suggest that this inter-areal difference is due to differences in the degree of inter-patch connectivity, with predators and dispersal acting as the primary synchronizing agents. Bank vole populations in field habitats were more synchronized within the forest-dominated landscape, most likely reflecting the suitability of the inter-patch matrix and the possibility of dispersal. Our study clearly indicates that landscape composition needs to be taken into account when describing the spatial properties of small rodent population dynamics.

Analysis of Variance↗
PubMed2003

Winter warming facilitates range expansion: cold tolerance of the butterfly Atalopedes campestris.

Our ability to predict ecological and evolutionary responses to climate change requires an understanding of the mechanistic links between climate and range limits. The warming trend over the past half-century has generated numerous opportunities to develop much-needed case studies of these links. Species that are only limited by climatic factors are likely to shift range quickly during periods of warming. Such species directly impact recipient communities and indicate trends that will become more widespread. Because minimum temperature (T (min)) is rising at twice the rate of maximum temperature, species with this range-limiting factor may be especially responsive to global warming. In this study, I test the hypothesis that rising T (min) has directly affected the range of a skipper butterfly. Atalopedes campestris has moved northward rapidly this century, recently colonizing eastern Washington where January T (min) has risen 3 degrees C in 50 years. The results show that: 1. A. campestris' range lies completely within the -4 degrees C January average minimum isotherm, and that recently colonized areas were below this threshold earlier this century. 2. In acute cold stress experiments, -4 to -7 degrees C proved to be a critical thermal limit: median supercooling point was -6.3 degrees C, and minimum lethal temperature (LT50 with 12-h exposure) was -5.7 degrees C. 3. In chronic cold stress experiments, survivorship declined sharply in diurnally fluctuating thermal regimes typical of the current range edge. High mortality occurred under constant 0 degrees C conditions as well as in fluctuating regimes, implying that thermal insulation from snow would not protect A. campestris. 4. There was no evidence of evolution in cold tolerance at the range margin, despite strong selection. Thus, winter warming was apparently a prerequisite for the range expansion. Characteristics of this species that seem to be associated with its rapid response are that it is an opportunistic species, it is not habitat or dispersal limited, and it is constrained by T (min).

Acclimatization↗
PubMed2003

Ecological constraints on extra-pair paternity in the bluethroat.

The mating system of the bluethroat (Luscinia s. svecica) involves a high level of sperm competition, and consequently a high frequency of extra-pair paternity (EPP). There is considerable variation in the frequency of EPP. Over the course of ten study years in a population in Norway, the frequency has fluctuated between 7% and 33% of young, and 8% and 76% of broods. In this paper, we address the issue of whether ecological factors can explain some of the variation in EPP between years and broods. Factors include breeding density, breeding synchrony and two meteorological variables (ambient temperature and precipitation) during the period of peak female fertility. There were no significant relationships between annual averages of the four variables and the annual level of EPP, but the statistical power of these tests was low, due to a restricted sample (n=10 years). Focussing on individual broods, none of the factors had significant effects when including all broods in the analyses (including those with zero EPP). When limiting the analyses to broods with one or more extra-pair offspring, morning temperature had a significant effect on the frequency of EPP. When the temperature was low during the peak of the fertile period, EPP occurred less frequently. Male extra-pair behaviour was not generally constrained by synchrony between the fertile periods of the social mate and the extra-pair mate, but for a subgroup of males ("unattractive males") there appeared to be a trade-off between mate guarding and pursuing extra-pair copulations. Our results indicate that ecological conditions have no influence on whether or not a brood will contain extra-pair offspring, but when EPP does occur, its frequency is influenced by air temperature. Possibly, there is a causal relationship between weather conditions and the frequency of extra-pair encounters in this species. The breeding season is initiated at a phenologically early stage, when large parts of the territories are still covered with snow, and cold weather conditions may force the birds to devote most of their time to maintenance and thereby constrain sexual activities.

Animals↗
PubMed2005

Global application of stable hydrogen and oxygen isotopes to wildlife forensics.

Stable isotopes are being increasingly used in wildlife forensics as means of determining the origin and movement of animals. The heavy isotope content of precipitated water and snow (deltaD(p), delta(18)O(p)) varies widely and systematically across the globe, providing a label that is incorporated through diet into animal tissue. As a result, these isotopes are potentially ideal tracers of geographic origin. The hydrogen and oxygen isotope tracer method has excellent potential where (1) spatial variation of precipitation isotopes exist, and (2) strong, mechanistic relationships link precipitation and isotope ratios in biological tissue. Here, we present a method for interpolation of precipitation isotope values and use it to create global basemaps of growing-season (GS) and mean annual (MA) deltaD(p) and delta(18)O(p). The use of these maps for forensic application is demonstrated using previously published isotope data for bird feathers (deltaD(f)) in North America and Europe. The precipitation maps show that the greatest potential for applying hydrogen and oxygen isotope forensics exists in mid- to high-latitude continental regions, where strong spatial isotope gradients exist. We demonstrate that deltaD(f)/deltaD(p) relationships have significant predictive power both in North America and Europe, and show how zones of confidence for the assignment of origin can be described using these predictive relationships. Our analysis focuses on wildlife forensics, but the maps and approaches presented here will be equally applicable to criminal forensic studies involving biological materials. These maps are available in GIS format at http://www.waterisotopes.org.

Animals↗
PubMed2006

Coupling between carbon cycling and climate in a high-elevation, subalpine forest: a model-data fusion analysis.

Fundamental questions exist about the effects of climate on terrestrial net ecosystem CO(2) exchange (NEE), despite a rapidly growing body of flux observations. One strategy to clarify ecosystem climate-carbon interactions is to partition NEE into its component fluxes, gross ecosystem CO(2) exchange (GEE) and ecosystem respiration (R (E)), and evaluate the responses to climate of each component flux. We separated observed NEE into optimized estimates of GEE and R (E) using an ecosystem process model combined with 6 years of continuous flux data from the Niwot Ridge AmeriFlux site. In order to gain further insight into the processes underlying NEE, we partitioned R (E) into its components: heterotrophic (R (H)) and autotrophic (R (A)) respiration. We were successful in separating GEE and R (E), but less successful in accurately partitioning R (E) into R (A) and R (H). Our failure in the latter was due to a lack of adequate contrasts in the assimilated data set to distinguish between R (A) and R (H). We performed most model runs at a twice-daily time step. Optimizing on daily-aggregated data severely degraded the model's ability to separate GEE and R (E). However, we gained little benefit from using a half-hourly time step. The model-data fusion showed that most of the interannual variability in NEE was due to variability in GEE, and not R (E). In contrast to several previous studies in other ecosystems, we found that longer growing seasons at Niwot Ridge were correlated with less net CO(2) uptake, due to a decrease of available snow-melt water during the late springtime photosynthetic period. Warmer springtime temperatures resulted in increased net CO(2) uptake only if adequate moisture was available; when warmer springtime conditions led into mid-summer drought, the annual net uptake declined.

Altitude↗
PubMed2006

Climate change has only a minor impact on nutrient resorption parameters in a high-latitude peatland.

Nutrient resorption from senescing plant tissues is an important determinant of the fitness of plant populations in nutrient-poor ecosystems, because it makes plants less dependent on current nutrient uptake. Moreover, it can have significant "afterlife" effects through its impact on litter chemistry and litter decomposability. Little is known about the effects of climate change on nutrient resorption. We studied the effects of climate change treatments (including winter snow addition, and spring and/or summer warming) on nutrient resorption of four dominant species in a nutrient-poor subarctic peatland. These species were Betula nana (woody deciduous), Vaccinium uliginosum (woody deciduous), Calamagrostis lapponica (graminoid) and Rubus chamaemorus (forb). After five years of treatments both mature and senesced leaf N concentrations showed a small but significant overall reduction in response to the climate treatments. However, the effects were species-specific. For example, in the controls the N concentration in senesced leaves of Calamagrostis (3.0+/-0.2 mg N g(-1)) was about four times lower than for Rubus (11.2+/-0.2 mg N g(-1)). There were no significant treatment effects on N resorption efficiency (% of the N pool in mature leaves that is resorbed during senescence). The nitrogen resorption efficiency of Calamagrostis (about 80%) was higher than in the other three species (about 60%). Thus, climate change has only a minor impact on nutrient resorption parameters. However, given the substantial interspecific differences in these parameters, substantial changes in plant-soil feedbacks may be expected as a result of the observed changes in the species composition of high-latitude vegetation. These changes are species-specific and thus difficult to predict.

Analysis of Variance↗
PubMed2002

Changes in wind regime around a nickel-copper smelter at Monchegorsk, northwestern Russia.

Wind stress may significantly change plant damage by aerial pollutants. However, almost no information exists on pollution-induced changes in wind regime around the strong emission sources. Wind speed, measured in industrial barrens adjacent to the nickel-copper smelter at Monchegorsk (Kola Peninsula, NW Russia), was two to three times as high as in the slightly polluted and nearly unpolluted forests. The ratio between the maximum wind velocity within 30 s and the average velocity of that time interval showed no temporal variation, thus characterising the wind regime. This ratio was highest in unpolluted forests, suggesting the predominance of gusty winds; in industrial barrens the maximum wind speed was only slightly higher than the average value. Since topography did not explain the spatial variation in wind regime, I conclude that my data represent the first direct evidence for distinct changes in wind regime caused by pollution-induced habitat deterioration. The results suggest that initial (partly pollution-induced) forest disturbance causes secondary effects (like increased snow evaporation, followed by soil freezing and plant damage) that may enhance further disturbance in a positive feedback fashion.

Air Pollutants, Occupational↗
PubMed2003

West-east contrast of phenology and climate in northern Asia revealed using a remotely sensed vegetation index.

The phenology of the vegetation covering north Asia (mainly Siberia) and its spatial characterstics were investigated using remotely sensed normalized difference vegetation index (NDVI) data. The analysis used the weekly averaged NDVI over 5 years (1987-1991) using the second-generation weekly global vegetation index dataset (0.144 degrees x 0.144 degrees spatial resolution). In the seasonal NDVI cycle, three phenological events were defined for each pixel: green-up week (NDVI exceeds 0.2), maximum week, and senescence week (NDVI drops below 0.2). Generally there was a west-early/east-late gradient in the three events in north Asia. In the zonal transect between 45 degrees and 50 degrees N, the timing of green-up, maximum, and senescence near 60 degrees E (Kazakh) was about 3.4, 8.7, and 13.4 weeks earlier than near 110 degrees E (Mongolia) respectively. It has been suggested that vegetation near Kazakh only flourishes during a short period when water from snow melt is available from late spring to early summer. In Mongolia, abundant water is available for the vegetation, even in midsummer, because of precipitation. In the 50-60 degrees N zonal transect, the green-up and maximum near 40 degrees E were about 3.8 and 3.9 weeks earlier than near 115 degrees E, respectively. As for the week of senescence, there was no clear west-east trend. This west-to-east phenological gradient was related to the weekly cumulative temperature (over 0 degrees C). Weeks in which the cumalative temperature exceeded 40 degrees C and 140 degrees C had a similar west-east distribution to green-up and maximum NDVI.

Asia↗
PubMed2001

Medium-chain triglyceride-rich enteral nutrition is more effective than low-fat enteral nutrition in rat colitis, but is equal in enteritis.

BACKGROUND: Although enteral nutrition (EN) therapy for Crohn's disease has been confirmed to be as effective as steroid therapy, the precise mechanism responsible for the effects of EN remains unclear, although some of the therapeutic effects of EN are believed to be due to a low dietary fat content. In order to elucidate the influence of fat in EN, it is important to investigate not only the quantity of fat, but also the source of the fat. METHODS: We compared two enteral nutritional formulae: Elental (Ajinomoto) (elemental diet; ED), which contains only 1.5% fat, provided as long-chain triglycerides (LCT), versus Twinline (Snow Brand Milk Products) (TL), which contains a high percentage of fat (20.4%), provided mainly as medium-chain triglycerides (MCT). These formulae were tested on rat enteritis and rat colitis induced by trinitrobenzene sulfonic acid (TNBS). RESULTS: Both ED and TL reduced the manifestations of enteritis. TL had a stronger anti-inflammatory effect than ED for colitis. TL also had nutritional advantages as compared with ED, as shown by the total serum protein in the TL group being significantly higher than that in the ED group. CONCLUSION: The results indicate that intraluminal MCT is suitable as a fat energy source during intestinal inflammation in rats. We suggest that Twinline may be more useful to improve nutritional status and to reduce the mucosal inflammation in rat colitis, but that Twinline is equal in effect to Elental for rat enteritis.

Animals↗
PubMed2003

The Ai project: historical and ecological contexts.

This paper aims to review a long-term research project exploring the chimpanzee mind within historical and ecological contexts. The Ai project began in 1978 and was directly inspired by preceding ape-language studies conducted in Western countries. However, in contrast with the latter, it has focused on the perceptual and cognitive capabilities of chimpanzees rather than communicative skills between humans and chimpanzees. In the original setting, a single chimpanzee faced a computer-controlled apparatus and performed various kinds of matching-to-sample discrimination tasks. Questions regarding the chimpanzee mind can be traced back to Wolfgang Koehler's work in the early part of the 20th century. Yet, Japan has its unique natural and cultural background: it is home to an indigenous primate species, the Japanese snow monkey. This fact has contributed to the emergence of two previous projects in the wild led by the late Kinji Imanishi and his students. First, the Koshima monkey project began in 1948 and became famous for its discovery of the cultural propagation of sweet-potato washing behavior. Second, pioneering work in Africa, starting in 1958, aimed to study great apes in their natural habitat. Thanks to the influence of these intellectual ancestors, the present author also undertook the field study of chimpanzees in the wild, focusing on tool manufacture and use. This work has demonstrated the importance of social and ecological perspectives even for the study of the mind. Combining experimental approaches with a field setting, the Ai project continues to explore cognition and behavior in chimpanzees, while its focus has shifted from the study of a single subject toward that of the community as a whole.

Adaptation, Psychological↗
PubMed2003

Seasonal pattern of photosynthetic production in a subalpine evergreen herb, Pyrola incarnata.

The seasonal pattern of growth and matter production of Pyrola incarnata, an evergreen herb on the forest floor in subalpine deciduous forests, was analyzed to understand the ecological significance of evergreenness in a subalpine climate with a short growing season and low temperature. Net production was highest under favorable light conditions in spring after the disappearance of snow cover, and 68% of the annual net production was attained before the canopy tree foliage had fully expanded. Most of the photosynthetic production in this period was carried out with over-wintered leaves. This appears to be an advantage of evergreenness. New leaves and inflorescences had developed in the period. Positive net production was maintained under deteriorating light conditions during summer, when 32% of the annual net production occurred. This production was used mainly for growth of fruits and underground organs. The net production of P. incarnata during summer was much higher than that of a related species that inhabits warm-temperate regions, because of its higher photosynthetic activity rather than its lower respiratory losses. The storage of dry matter in leaves and underground organs was not conspicuous. Unlike the warm-temperate species and another subalpine species that inhabits higher altitudes, P. incarnata is not strongly dependent on its reserve matter for the development of new organs.

Biomass↗
PubMed2005

Phylogenomic study of the subfamily Caprinae by cross-species chromosome painting with Chinese muntjac paints.

Chromosomal homologies have been established between the Chinese muntjac (Muntiacus reevesi, MRE, 2n = 46) and five ovine species: wild goat (Capra aegagrus, CAE, 2n = 60), argali (Ovis ammon, OAM, 2n = 56), snow sheep (Ovis nivicola, ONI, 2n = 52), red goral (Naemorhedus cranbrooki, NCR, 2n = 56) and Sumatra serow (Capricornis sumatraensis, CSU, 2n = 48) by chromosome painting with a set of chromosome-specific probes of the Chinese muntjac. In total, twenty-two Chinese muntjac autosomal painting probes detected thirty-five homologous segments in the genome of each species. The chromosome X probe hybridized to the whole X chromosomes of all ovine species while the chromosome Y probe gave no signal. Our results demonstrate that almost all homologous segments defined by comparative painting show a high degree of conservation in G-banding patterns and that each speciation event is accompanied by specific chromosomal rearrangements. The combined analysis of our results and previous cytogenetic and molecular systematic results enables us to map the chromosomal rearrangements onto a phylogenetic tree, thus providing new insights into the karyotypic evolution of these species.

Animals↗
PubMed2006

Characteristics of neuron activity in the honey bee (Apis mellifera L.) in conditions of kynurenine deficiency.

Neuron activity was studied electrophysiologically in the antennal lobes, mushroom bodies, and cervical connective during ontogenesis (days 1, 3, 7, and 25) in snow(laranija) mutant bees, which suffer kynurenine deficiency, and in wild-type bees. Neuron activity recorded from the cervical connective was found to show the greatest dependence on kynurenine content. Mutation in the structural gene for tryptophan oxygenase, the first and key enzyme in the kynurenine pathway for tryptophan metabolism (KPTM) and which leads to kynurenine deficiency, decreased the frequency of neuron spike activity recorded from the cervical connective. This would appear to be associated with a possible deficiency of glutamic acid; it was independent of the deficiency of kynurenic acid and kynurenine, a point subject to further studies. Clear manifestation of the effect of the mutation requires the presence of two mutant alleles in the bee genome (homozygosity). The effect of the mutation, to inhibit neuron activity in the cerebral ganglion, corresponds to the effect seen previously at the behavioral level. Less clear effects were obtained from recordings of neuron activity from the antennal lobes and mushroom bodies. This may be associated with the complexity of the spectrum of biochemical lesions in different parts of the brain resulting from the mutation.

Action Potentials↗