Serum Fructosamine Levels in Dairy Cows Related to Metabolic Status in Early Lactation

Serum levels of fructosamine were assayed in 57 samples from 23 Norwegian Red Cattle dairy cows in early lactation. The animals were assigned to a 22 factorial feeding experiment. The groups differed in energy and protein supply. All samples were collected before morning feeding. The relationship between fructosamine levels and the plasma concentrations of glucose, acetoacetate, free fatty acids, total cholesterol, lipoproteins, triglycerides, total proteins, progesterone and to weight and energy balance was studied. The overall mean fructosamine level was 1.41 ± 0.20 mmol/1 ranging from 0.92–1.92 mmol/1. Significant relationships were recorded between fructosamine and the concentrations of glucose, acetoacetate, free fatty acids, triglyceride, total cholesterol and energy and weight balance. Free fatty acids and cholesterol showed the best correlation with fructosamine (rs =–0.67 and 0.70, respectively, p < 0.001). The levels of fructosamine increased significantly between 2 and 4 weeks and between 4 and 8 weeks after calving. Animals with a weight gain during 3 weeks prior to fructosamine measurement had higher fructosamine levels than those showing a weight loss (<–7 kg/week) (p < 0.05). The results indicate that serum fructosamine levels in cows may be of interest as an indicator of metabolic status in the early stages of lactation.     

A Novel Regulatory Locus of Phosphorylation in the C Terminus of the Potassium Chloride Cotransporter KCC2 That Interferes with N-Ethylmaleimide or Staurosporine-mediated Activation

The neuron-specific cation chloride cotransporter KCC2 plays a crucial role in hyperpolarizing synaptic inhibition. Transporter dysfunction is associated with various neurological disorders, raising interest in regulatory mechanisms. Phosphorylation has been identified as a key regulatory process. Here, we retrieved experimentally observed phosphorylation sites of KCC2 from public databases and report on the systematic analysis of six phosphorylated serines, Ser²⁵, Ser²⁶, Ser⁹³⁷, Ser¹⁰²², Ser¹⁰²⁵, and Ser¹⁰²⁶. Alanine or aspartate substitutions of these residues were analyzed in HEK-293 cells. All mutants were expressed in a pattern similar to wild-type KCC2 (KCC2^WT). Tl⁺ flux measurements demonstrated unchanged transport activity for Ser²⁵, Ser²⁶, Ser¹⁰²², Ser¹⁰²⁵, and Ser¹⁰²⁶ mutants. In contrast, KCC2^S937D, mimicking phosphorylation, resulted in a significant up-regulation of transport activity. Aspartate substitution of Thr⁹³⁴, a neighboring putative phosphorylation site, resulted in a comparable increase in KCC2 transport activity. Both KCC2^T934D and KCC2^S937D mutants were inhibited by the kinase inhibitor staurosporine and by N-ethylmaleimide, whereas KCC2^WT, KCC2^T934A, and KCC2^S937A were activated. The inverse staurosporine effect on aspartate versus alanine substitutions reveals a cross-talk between different phosphorylation sites of KCC2. Immunoblot and cell surface labeling experiments detected no alterations in total abundance or surface expression of KCC2^T934D and KCC2^S937D compared with KCC2^WT. These data reveal kinetic regulation of transport activity by these residues. In summary, our data identify a novel key regulatory phosphorylation site of KCC2 and a functional interaction between different conformation-changing post-translational modifications. The action of pharmacological agents aimed to modulate KCC2 activity for therapeutic benefit might therefore be highly context-specific.     

On the Structure of Intestinal Epithelium of Fasciola Hepatica During in Vitro Cultivation

The normal ultrastructure of the intestinal epithelium of F. hepatica has been described in detail e. g. by Thorsell &amp; Björk- man (1965). However, experimentally produced pathological phenomena of the epithelium have not been investigated, though such studies might yield further information on the physiological function of the epithelial cell. Light and electron microscopy of the intestinal epithelium during in vitro cultivation of the liver fluke does therefore seem to be appropriate. This preliminary report, giving an account of the cultivation procedures, deals only with light microscopy of the cultivated liver flukes.     

rab5 GTPase Regulates Adenovirus Endocytosis

Adenovirus interaction with alphav integrins is important for virus entry. We have examined the effects of adenovirus attachment on intracellular signaling in HeLa cells, with an emphasis on pathways known to be activated following integrin interaction with other ligands. We found no evidence for [Ca(2+)](c)-mediated signaling or for tyrosine phosphorylation of pp125(FAK), p130(CAS), and paxillin. However, adenovirus attachment is known to activate phosphatidylinositol-3 kinase, which in turn may regulate endocytosis via rab5 GTPase. We found that adenovirus uptake was increased by overexpression of wild-type rab5 and decreased by dominant-negative rab5. These results indicate a role for rab5 in adenovirus entry.     

IGF-I, IgA, and IgG responses to bovine colostrum supplementation during training.

This study examined the effect of bovine colostrum (Dynamic colostrum) supplementation on blood and saliva variables (study 1) and the absorption of orally administered human recombinant insulin-like growth factor (IGF)-I (rhIGF-I) labeled with 123I (123I-rhIGF-I) (study 2). In study 1, adult male and female athletes were randomly assigned in a double-blind fashion to either an experimental (Dynamic; n = 19) or a control (Placebo; n = 11) group. The former consumed daily 20 g of Dynamic supplement, and the latter 20 g of maltodextrin during a 2-wk training period. After bovine colostrum supplementation, significant increases were noticed in serum IGF-I (P < 0.01) and saliva IgA (P < 0.01) in Dynamic compared with Placebo. In study 2, gel electrophoresis was carried out in 12 adult subjects with serum samples taken 60 min after ingestion of 123I-rhIGF-I and showed peaks at 0.6 and at 40-90 kDa, with the former inducing 96% and the latter 4% of the total radioactivity. It was concluded that a long-term supplementation of bovine colostrum (Dynamic) increases serum IGF-I and saliva IgA concentration in athletes during training. Absorption data show that ingested 123I-rhIGF-I is fragmented in circulation and that no radioactive IGF-I is eluted at the positions of free, or the IGF, binding proteins, giving no support to the absorption of IGF-I from bovine colostrum.     

Two Improved Methods for Obtaining Axenic Cultures of Cyanobacteria

Scoring the agar plate before incubation under unidirectional light led to a rapid separation of gliding filamentous cyanobacteria from their contaminating bacteria. Twenty strains were purified by the method. Additionally, 13 axenic cyanobacterial strains were isolated from pour plates made after treatment of cyanobacterial cultures in tryptone-yeast extract-glucose broth with cycloserine in darkness to select for obligate photoautotrophs.     

Littoral-pelagial interchange and the decomposition of dissolved organic matter in a polyhumic lake

The small, polyhumic lake, Mekkojärvi (southern Finland), is bordered by a moss vegetation zone (Warnstorfia and Sphagnum species) which provides a habitat-rich and productive environment for many planktonic and periphytic animals. Impacts of moss on the metabolism of bacterioplankton, phytoplankton and zooplankton in polyhumic water were investigated in laboratory throughflow systems. Growing Warnstorfia (together with epiphytic algae and bacteria) suppressed the production of planktonic algae but had no clear effect on leucine uptake, and hence bacterial production, or on the decomposition of humic substances. Phenol uptake and mineralization rates, however, were lower in the littoral water than in the pelagial water. Excretion of organic carbon by Warnstorfia algae or Daphnia longispina (the predominant crustacean in the pelagial water) provided only a minor contribution to bacterial production; therefore, a major contribution had to be from humic substances. A bacterial production efficiency of 31–38% could account for the microbial respiration in the water. The results indicated that bacterial, or detrital matter (originating largely from the littoral zone), could not obviate the need for algal food, and that a great deal of particulate matter in the water was poor or useless food for Daphnia. In all, the bulk of dissolved organic matter in Lake Mekkojärvi was biochemically highly recalcitrant. Our results indicate that humic substances (from watershed or littoral area) which, through bacterial degradation, enter the planktonic food web of the lake are mainly lost through respiration by microorganisms.