Characterization of a penta-and an octasaccharide from urine of a patient with juvenile GM1-gangliosidosis.

Two structurally related oligosaccharides have been isolated from the urine of a patient with GM₁-gangliosidosis type 2. The isolation procedure included ultrafiltration, gel chromatography on Sephadex G-25, and preparative paper chromatography. From structural studies including optical rotation, sugar analysis, methylation analysis, and chromium trioxide oxidation, the following structures are deduced:

The octasaccharide has previously been reported to be present in both liver and urine of patients with GM₁-gangliosidosis type 1 and type 2. The pentasaccharide is a new compound and is an integral part of the octasaccharide. The yields of the octasaccharide and pentasaccharide were 17 and 8 mg/liter of urine, respectively. Both compounds are most probably degradation products derived from the core of glycoprotein carbohydrate chains.     

Inferring species boundaries using acoustic and morphological data in the ground cricket genus Gymnogryllus (Orthoptera: Grylloidea: Gryllinae)

An important function of song production by male crickets is to attract conspecific females. These sound signals can be used to infer species boundaries as they can provide indirect evidence for reproductive isolation. However, many studies of orthopteran diversity in South-east Asia are based mainly on morphology and only occasionally acoustics. As such, there is a lack of information on how acoustic data can be congruent with morphological data when used to delineate species. Crickets of the genus Gymnogryllus (Grylloidea, Gryllidae), are such an example. Gymnogryllus are relatively speciose, but their calling songs have not been studied. We collected specimens and calling songs of five Gymnogryllus species from South-east Asia. The acoustic parameters of the calls, along with male tegminal venation and morphology genitalia, were compared. All data types showed congruency in distinguishing G. sylvestris and G. leucostictus from each other and from the other species. Inferring species boundaries for G. angustus, G. malayanus, and G. unexpectus using acoustics and tegminal morphometry proves to be more challenging. While acoustics, tegminal morphometry, and genital morphology are likely to be useful for inferring species of Gymnogryllus from different species groups, greater coverage of taxa is needed to resolve taxonomy of closely related Gymnogryllus.     

Individual and interactive effects of warming and nitrogen supply on CO2 fluxes and carbon allocation in subarctic grassland

Climate warming has been suggested to impact high latitude grasslands severely, potentially causing considerable carbon (C) losses from soil. Warming can also stimulate nitrogen (N) turnover, but it is largely unclear whether and how altered N availability impacts belowground C dynamics. Even less is known about the individual and interactive effects of warming and N availability on the fate of recently photosynthesized C in soil. On a 10-year geothermal warming gradient in Iceland, we studied the effects of soil warming and N addition on CO₂ fluxes and the fate of recently photosynthesized C through CO₂ flux measurements and a ¹³CO₂ pulse-labeling experiment. Under warming, ecosystem respiration exceeded maximum gross primary productivity, causing increased net CO₂ emissions. N addition treatments revealed that, surprisingly, the plants in the warmed soil were N limited, which constrained primary productivity and decreased recently assimilated C in shoots and roots. In soil, microbes were increasingly C limited under warming and increased microbial uptake of recent C. Soil respiration was increased by warming and was fueled by increased belowground inputs and turnover of recently photosynthesized C. Our findings suggest that a decade of warming seemed to have induced a N limitation in plants and a C limitation by soil microbes. This caused a decrease in net ecosystem CO₂ uptake and accelerated the respiratory release of photosynthesized C, which decreased the C sequestration potential of the grassland. Our study highlights the importance of belowground C allocation and C-N interactions in the C dynamics of subarctic ecosystems in a warmer world.     

The reactivity of uronic and aldonic acid derivatives towards trifluoroacetolysis. A new method for specific elimination of reducing 4-O-substituted hexose residues

Trifluoroacetolysis of d-glucuronic acid and methyl α-d-glucopyranosiduronic acid resulted in an initial phase of degradation followed by stabilisation of the compounds as their 6,3-lactones. The methyl ester of methyl 4-O-methyl-α-d-glucopyranosiduronic acid was largely stable towards trifluoroacetolysis. Aldonic acids substituted at O-3 or O-6 were stable towards trifluoroacetolysis because of the formation of γ-lactones. Aldonic acids substituted at O-4, and incapable of forming γ-lactones, were converted into the trifluoroacetylated enol of 3-deoxy-2-hexulosonic acid. Treatment of the 3-deoxy-2-hexulosonic acid with mild base eliminated the substituent at O-4.     

Pollinator functional response and plant population dynamics: Pollinators as a limiting resource

Summary During recent years, much work has focused on which factors limit the reproductive success in plants. Several studies show a strong influence of either resource limitation, pollen limitation or a combined effect of both. The theoretical arguments for resource limitation are abundant, but there has been very little work done concerning the effect of pollinator availability. In this paper we construct a model to study how the reproductive success in plants is influenced by the foraging behaviour of the pollinators. The pollinator population is assumed to have a constant population density. A functional response function for the pollinators is derived. It is similar to a Holling type II functional response. It is shown that, since the pollinators are regulated by factors not included in the model and their capability to pollinate is limited by the functional response, this is sufficient for regulating the plant population. There also exists a threshold condition for the persistence of the plant population that depended on the search rate of the pollinators and the demographic parameters of the plant population. If this threshold condition is not satisfied the plant population cannot persist and will become extinct. If the condition is satisfied the plant population grows until it is limited at the equilibrium mentioned above.     

Can Nitrogen Fertilization Aid Restoration of Mature Tree Productivity in Degraded Dryland Riverine Ecosystems?

Restoration of riparian forest productivity lost as a consequence of flow regulation is a common management goal in dryland riverine ecosystems. In the northern hemisphere, dryland river floodplain trees often include one or another species of Populus, which are fast‐growing, nutrient‐demanding trees. Because the trees are phreatophytic in drylands, and have water needs met in whole or in part by a shallow water table, their productivity may be limited by nitrogen (N) availability, which commonly limits primary productivity in mesic environments. We added 20 g N m^?2 in a 2‐m radius around the base of mature Populus fremontii along each of a regulated and free‐flowing river in semiarid northwest Colorado, USA (total n = 42) in order to test whether growth is constrained by low soil N. Twelve years after fertilization, we collected increment cores from these and matched unfertilized trees and compared radial growth ratios (growth in the 3‐year post‐fertilization period/growth in the 3‐year pre‐fertilization period) in paired t tests. We expected a higher mean ratio in the fertilized trees. No effect from fertilization was detected, nor was a trend evident on either river. An alternative test using analysis of covariance (ANCOVA) produced a similar result. Our results underscore the need for additional assessment of which and to what extent factors other than water control dryland riverine productivity. Positive confirmation of adequate soil nutrients at these and other dryland riparian sites would bolster the argument that flow management is necessary and sufficient to maximize productivity and enhance resilience in affected desert riverine forests.     

In Search of Community: A Quest for Well-Being among Tamil Refugees in Northern Norway

Over the past ten years, Tamil refugees have settled in marginal fishing communities along the Arctic coastline of northern Norway. This article focuses on social aspects of Tamil resettlement and on the refugees' struggle for well-being. Tamils in these communities often experience diffuse aches and pains that are difficult for health workers to diagnose and treat. This article argues for the need to understand such health problems as embedded in social relations as they are experienced and embodied by the Tamils. Case studies are presented emphasizing that Tamils experience being misunderstood as individuals and as whole persons. This article draws a picture of a social context in which Tamils are stretched and pulled in different directions in search of community and individuality. The question emerges how best to understand the process of embodiment, which may transcend the individual body.     

Synthesis of Galβ1-3GlcNAc and Galβ1-3GlcNAcβ-SEt by an enzymatic method comprising the sequential use of β-galactosidases from bovine testes andEscherichia coli

Gal1-3GlcNAc (1) and Gal1-3GlcNAc-SEt (2) were synthesized on a 100 mg scale by the transgalactosylation reaction of bovine testes -galactosidase with lactose as donor andN-acetylglucosamine and GlcNAc-SEt as acceptors. In both cases the product mixtures contained unwanted isomers and were treated with -galactosidase fromEscherichia coli which has a different specificity, under conditions favouring hydrolysis, yielding besides the desired products, monosaccharides and traces of trisaccharides. The products were purified to >95% by gel filtration, with a final yield of 12% of 1 and 17% of 2, based on added acceptor. In a separate experiment Gal1-6GlcNAc-SEt (3) was synthesized by the transglycosylation reaction using -galactosidase fromEscherichia coli. No other isomers were detected. Compound 3 was purified by HPLC.     

The influence of environmental factors on dormancy and duration of egg development in Metrioptera roeseli (Orthoptera: Tettigoniidae)

Summary Developing eggs of Metrioptera roeseli HGB. have an obligate embryonic diapause in stage 23 and a facultative initial diapause in stage 4. Initial diapause is lacking when the ovipositing females are kept at long day photoperiod (LD 16/8), but is induced at LD 14/10 and LD 8/16. When natural light conditions are given in the laboratory, the females mostly lay diapausing eggs from the end of August onwards. In eggs without initial diapause, a larger number of embryos reach a stage, in which the embryonic diapause can be broken by chilling, only at favorable temperature (4 weeks at 24°C or 8 at 18°C) and in contact with water before the first winter. Thus, some individuals of a given population of M. roeseli have an annual, others a biennial life cycle. The variability in the duration of egg development is due to a photoperiodically induced, facultative initial diapause and to a possible quiescence caused by insufficient temperature and/or moisture.