Synthesis of a 3'-naphthamido-LacNAc fluorescein conjugate with high selectivity and affinity for galectin-3

Described is the synthesis of a fluorescent LacNAc derivative appended with a 3'-deoxy-3'-naphthamido functionality, 2-(fluorescein-5/6-amido)ethyl 3-deoxy-3-(2-naphthamido)-beta-D-galactopyranosyl-(1-->4)-2-acetamido-2-deoxy-beta-D-glucopyranoside, which confers high affinity (Kd 170 nM) and selectivity for galectin-3 via a stacking interaction with Arg144. Its use as a selective and sensitive galectin-3 probe is demonstrated with fluorescence polarization measurements.     

Fatal interactions between Scots pine and Sphagnum mosses in bog ecosystems

In this study, we explore how Sphagnum mosses and Scots pine, Pinus sylvestris , interact on different spatial and temporal scales in a boreal bog ecosystem. We were particularly interested in relationships between the occurrence of Sphagnum- dominated habitats and the occurrence of Scots pines of different age and size.
Juvenile and adult pines occurred in different habitats. While juveniles mainly occurred in Sphagnum- dominated habitats, predominantly with Sphagnum rubellum , adult pines were found in habitats dominated by lichens, or with a sparse vegetation cover. Examination of surface peat cores sampled close to adult pines revealed that almost all pines (97%) had established in a Sphagnum -dominated environment and that the habitat had changed since pine establishment. Scots pine is thus capable of changing and exterminating the Sphagnum -dominated environment preferred for germination and establishment. Pines impede Sphagnum growth and peat accumulation significantly once they have reached a stem diameter of approximately 20 mm. It takes from 30 to 90 yr for a pine to reach that size.
Our results show the importance of interactions between Scots pine and Sphagnum mosses in bog ecosystems. We conclude that interactions between trees and Sphagnum mosses are important driving forces behind the vegetation change that has characterised boreal bogs during the Holocene.     

Intracerebral Dialysis and the Blood-Brain Barrier

Abstract: The aim of the study was to evaluate how implantation of a dialysis probe influences the blood-brain barrier. Leakage of endogenous serum albumin was evaluated by Evans blue/albumin staining and by immunohistochemistry. The passage from blood to dialysate of two substances that normally do not pass into the brain, [³H]inulin and glutamate, was studied 3 and 24 h after insertion of a dialysis probe. Evans blue, given 20 min before rats were killed, was observed around the probe and surrounding brain tissue. Albumin immunoreactivity was seen at considerable distance from the probe with larger spread at 24 h than at 3 h after probe insertion. Glutamate and [³H]inulin were detected in the dialysate with no significant further increase of radioactivity after intracarotid infusion of protamine sulfate that enhances the permeability over the blood-brain barrier. When protamine was followed by infusion of glutamate, the concentrations of taurine increased in the dialysate in four of eight rats. That plasma constituents have access to the brain around the dialysis probe is essential to consider, particularly in studies using substances and drugs that do not pass an intact blood-brain barrier.     

A 5.8 kb deletion removing the entire MNX1 gene in a Norwegian family with Currarino syndrome

Currarino syndrome (CS) is a clinically variable disorder characterized by anorectal, sacral and presacral anomalies. It is associated with loss-of-function mutations in the motor neuron and pancreas homeobox 1 (MNX1) gene. Inheritance is autosomal dominant, expression variable and penetrance incomplete. We describe a Norwegian family with typical CS in which a heterozygous deletion removes the entire MNX1 gene but no other known genes. We also report MNX1 mutations in three other Norwegian families and confirm that the GCC₁₂ repeat (c.373_375[12]) is a normal allelic variant. This work underscores the importance of dosage analysis of MNX1 when Sanger sequencing is negative.     

Crystal structure of a mammalian purple acid phosphatase.

Tartrate-resistant acid phosphatase (TRAP) is a mammalian di-iron- containing enzyme that belongs to the family of purple acid phosphatases (PAP). It is highly expressed in a limited number of tissues, predominantly in bone-resorbing osteoclasts and in macrophages of spleen. We have determined the crystal structure of rat TRAP in complex with a phosphate ion to 2.7 A resolution. The fold resembles that of the catalytic domain of kidney bean purple acid phosphatase (KBPAP), although the sequence similarity is limited to the active site residues. A surface loop near the active site is absent due to proteolysis, leaving the active-site easily accessible from the surrounding solvent. This, we believe, gives a structural explanation for the observed proteolytic activation of TRAP. The current structure was determined at a relatively high pH and without any external reducing agents. It is likely that it represents an oxidized and therefore catalytically inactive form of the enzyme.     

Effects of Food Availability and Predation on a Marine Zooplankton Community — a Study on Copepods in the Baltic Sea

The importance of food resources versus predatory effects in determining the abundance pattern of zooplankton varies over time and space. Here, we evaluate the population dynamics of dominant calanoid copepods (Acartia spp. bifilosa/A. longiremis and Eurytemora affinis) in a reference area and a eutrophied area in the northern Baltic Sea Proper. We base the paper on a combination of statistical analyses of a long term (12 years) data set on population biomass dynamics, laboratory experiments on the feeding biology of these species and literature data of their susceptibility to predation. Overall, copepods were equally abundant at both sites, but Eurytemora was more abundant in the eutrophied area while Acartia spp. dominated in the non-eutrophied reference area. There was, however, no significant difference between the two areas in biomass dynamics (biomass specific rate of change) of the two groups of copepods. However, in spring and early summer the population biomass increased faster for Eurytemora as compared to Acartia spp. This is consistent with our findings from feeding and respiration experiments. Eurytemora exhibited generally higher ingestion rates and had a higher growth efficiency (ratio of ingestion to respiration rates), which suggests an advantage over Acartia spp. when food availability increases. Both species generally showed a rapid population decline starting in late summer, most likely caused by intensive predation by fish and mysid shrimps. In late autumn and winter, biomasses of both genera continued to decrease, but the decline was fastest for Eurytemora. During this period of the year, when the food availability is sparse, Acartia spp. may have an advantage over Eurytemora, as we found that the former ingests a broader size range of food particles and it has also been reported to be able to switch from filter feeding to raptorial feeding. This study shows that dominant copepods in the net-zooplankton community in our study area were structured both by food availability and predation. The relative importance of these effects varied seasonally.     

Atmospheric CO2 elevation has little effect on nitrifying and denitrifying enzyme activity in four European grasslands

The objective of this study was to determine what patterns, if any, existed in the response of nitrifying enzyme activity (NEA), denitrifying enzyme activity (DEA), soil microbial N and soil inorganic N to elevated CO₂ across a broad range of grassland environments. We studied the response of these N pools and microbial activities in four CO₂‐enrichment sites of the MEGARICH project (Managing European Grasslands as a Sustainable Resource in a Changing Climate). CO₂ treatment was studied in factorial combination with a cutting frequency treatment at two sites and with a temperature treatment at one site. Our study showed that microbial biomass N, NEA, DEA and extractable soil [NH₄⁺] and [NO₃^?] were generally not affected by elevated CO₂ in these grassland ecosystems after several years of treatment, nor by cutting frequency or temperature at the sites that included these treatments. Exceptions to this were that DEA and soil [NO₃^?] decreased by 22% and 45%, respectively, at the French site at elevated CO₂. We discuss the possible explanations for this lack of response.