Milk production and composition in reindeer (Rangifer tarandus): effect of lactational stage

Milk yield and composition of major milk constituents were measured in captive, nursing reindeer. Registration of milk production was performed during two successive lactations (2001 and 2002). The milk yield was significantly affected by week of lactation (P<0.001) and by individual (P<0.001). The lactation curve had an asymmetrical peak 3 weeks postpartum and the milk yield at peak lactation was 983 g/day (range 595-1239). The length of lactation varied from 24 to 26 weeks and average total milk production was 99.5 kg. From peak lactation the milk production decreased linearly (P<0.001) until milk production was terminated. Mean values for content of major milk constituents were 15.5% fat, 9.9% protein and 2.5% lactose. The content of fat and protein increased markedly with the lactation stage (P<0.001), while lactose showed a slight decrease (P<0.001). The milk composition was significantly affected by stage of lactation (P<0.001). There was a marginally significant decrease in protein:fat ratio (P=0.06) as protein was substituted by fat with stage of lactation. The caloric value of the milk averaged 8.7 kJ/g and increased significantly with the stage of lactation (P<0.001). The overall increase in milk gross energy content during lactation was 67.6%. The energy output averaged 7996 kJ/day at peak lactation and decreased significantly during the course of lactation (P=0.002).     

Population Genetic Structure and Conservation of the Lesser White-Fronted GooseAnser erythropus

The lesser white-fronted goose is a sub-Arctic species with a currently fragmented breeding range, which extends from Fennoscandia to easternmost Siberia. The population started to decline at the beginning of the last century and, with a current world population estimate of 25,000 individuals, it is the most threatened of the Palearctic goose species. Of these, only 30–50 pairs breed in Fennoscandia. A fragment of the control region of mtDNA was sequenced from 110 individuals from four breeding, one staging and two wintering areas to study geographic subdivisions and gene flow. Sequences defined 15 mtDNA haplotypes that were assigned to two mtDNA lineages. Both the mtDNA lineages were found from all sampled localities indicating a common ancestry and/or some level of gene flow. Analyses of molecular variance showed significant structuring among populations ( _ST 0.220, P < 0.001). The results presented here together with ecological data indicate that the lesser white-fronted goose is fragmented into three distinctive subpopulations, and thus, the conservation status of the species should be reconsidered.     

Mechanisms of hydrazine toxicity in rat liver investigated by proteomics and multivariate data analysis

A proteomics approach combined with multivariate data analysis was used to examine the hepatotoxic effect of hydrazine in 30 male Sprague Dawley rats, assigned to four treatment groups and two control groups. Liver samples from the individual animals were resolved by two-dimensional differential gel electrophoresis (2-D DIGE) and protein patterns from the 2-D gels were analyzed by principal component analysis (PCA) and partial least squares regression (PLSR). The PCA plot was able to describe the variation in the protein expression related to dose and time, by separation or clustering of different animal groups. PLSR followed by variable selection (Jack-knifing) was used to select proteins that varied significantly in relation to the dose related response of the hydrazine treatment. The 10 up-regulated and 10 down-regulated proteins with highest rank in the PLSR model were identified by mass spectrometry. Hydrazine treatment induced altered expression of proteins related to lipid metabolism, Ca(2+) homeostasis, thyroid hormone pathways and stress response. Several of the identified proteins have not previously been implicated in hydrazine toxicity and may thus be regarded as new potential biomarkers of induced liver toxicity.     

Reactive oxygen species are important mediators of taurine release from skeletal muscle cells

The present study illustrates elements ofthe signal cascades involved in the activation of taurine effluxpathways in myotubes derived from skeletal muscle cells. Exposingprimary skeletal muscle cells, loaded with ¹⁴C-taurine, to1) hypotonic media, 2) the phospholipaseA₂ (PLA₂) activator melittin, 3)anoxia, or 4) lysophosphatidyl choline (LPC) causes anincrease in ¹⁴C-taurine release and a concomitantproduction of reactive oxygen species (ROS). The antioxidants butulatedhydroxy toluene and vitamin E inhibit the taurine efflux after cellswelling, anoxia, and addition of LPC. The muscle cells possess twoseparate taurine efflux pathways, i.e., a swelling- andmelittin-induced pathway that requires 5-lipoxygenase activity foractivation and a LPC-induced pathway. The two pathways aredistinguished by their opposing sensitivity toward the anion channelblocker DIDS and cholesterol. These data provide evidence forPLA₂ products and ROS as key mediators of the signalcascade leading to taurine efflux in muscle.

     

Deficient CD4+ T cell priming and regression of CD8+ T cell functionality in virus-infected mice lacking a normal B cell compartment

In this study, we investigate the state of T cell-mediated immunity in B cell-deficient (B(-/-)) mice infected with two strains of lymphocytic choriomeningitis virus known to differ markedly in their capacity to persist. In B(-/-) C57BL mice infected with the more persisting virus, virus-specific CD8(+) T cells are initially generated that are qualitatively similar to those in wild-type mice. However, although cell numbers are well sustained over time, the capacity to produce cytokines is rapidly impaired. In similarly infected B(-/-) BALB/c mice, virus-specific CD8(+) T cells are completely deleted, indicating that host genotype influences the severity of the T cell defect. In B(-/-) C57BL mice infected with the less persisting virus, CD8(+) T cell dysfunction was not as pronounced, although it was clearly present. Most importantly, the appearance of dysfunctional CD8(+) T cells clearly precedes recrudescence of detectable virus, indicating that the T cell defect is not simply a secondary event due to virus buildup resulting from the failure of B(-/-) mice to produce neutralizing Abs. In contrast with CD8(+) T cells, which initially respond almost as in wild-type mice, the priming of virus-specific CD4(+) T cells was markedly impaired in B(-/-) mice infected with either virus strain. Thus, our results indicate that B cells play an important role in antiviral immunity not only as Ab producers, but also in promoting an optimal and sustained T cell response. The T cell defects are likely to contribute to the chronic course of viral infection in B(-/-) mice.     

Hipposin,a histone-derived antimicrobial peptide in Atlantic halibut (Hippoglossus hippoglossus L.)

A novel 51-residue antimicrobial peptide (AMP) from the skin mucus of Atlantic halibut (Hippoglossus hippoglossus L.) was isolated using acid extraction, and cationic exchange and reversed phase chromatography. The complete amino acid sequence of the AMP, termed hipposin, was determined by automated Edman degradation and mass spectrometry to be SGRGKTGGKARAKAKTRSSRAGLQFPVGRVHRLLRKGNYAHRVGAGAPVYL. The N-terminal amino group was acetylated. The theoretical mass of hipposin was calculated to be 5458.4 Da, which was in good agreement with the mass of 5459 Da determined by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). Hipposin was shown to be derived from histone H2A by PCR amplifying the encoding sequences from Atlantic halibut genomic DNA. The peptide showed sequence similarity with the 39-mer AMP buforin I of Asian toad and the 19-mer AMP parasin I of catfish. Fifty of the fifty-one residues in hipposin were identical to the N-terminal region of histone H2A from rainbow trout. Hipposin showed strong antimicrobial activity against several Gram-positive and Gram-negative bacteria and activity could be detected down to hipposin concentrations of 0.3 microM (1.6 microg/ml). Hipposin without N-terminal acetylation was prepared by solid-phase peptide synthesis and shown to have the same antimicrobial activity as the natural acetylated peptide. Thus, hipposin is a new broad-spectrum histone-derived AMP found in the skin mucus of Atlantic halibut.     

The occurrence of aerolysin-positive Aeromonas spp. and their cytotoxicity in Norwegian water sources

Aims:  The aim of the study was to investigate the occurrence of Aeromonas spp. and their aerolysin status in Norwegian natural water sources.
Methods and Results:  Seventy-one samples from 33 Norwegian water sources were examined for the presence of Aeromonas spp. From most of the sample sites, the strains were isolated on blood-ampicillin-agar and Difco Aeromonas agar simultaneously. The majority of the samples (73/77) contained Aeromonas spp., with an average of 35–100 cfu 100 ml^–1. The highest counts were found in faecally-contaminated water. Using PCR, 445 isolates were screened for the presence of aerolysin, and 79% of them were found to be carriers of the aerolysin gene. A selection of the isolated strains was tested on Vero cell cultures and 83% of them showed cytotoxicity.
Conclusions:  There is widespread occurrence of aerolysin-positive cytotoxic Aeromonas spp. in many different Norwegian natural waters, including drinking water sources.
Significance and Impact of the Study:  The widespread occurrence of potentially-pathogenic Aeromonas spp. in the environment demands that these bacteria should not be ignored in drinking water supplies and in the food industry.     

Gliadin T cell epitope selection by tissue transglutaminase in celiac disease. Role of enzyme specificity and pH influence on the transamidation versus deamidation process

Tissue transglutaminase (TG2) can modify proteins by transamidation or deamidation of specific glutamine residues. TG2 has a major role in the pathogenesis of celiac disease as it is both the target of disease-specific autoantibodies and generates deamidated gliadin peptides that are recognized by CD4(+), DQ2-restricted T cells from the celiac lesions. Capillary electrophoresis with fluorescence-labeled gliadin peptides was used to separate and quantify deamidated and transamidated products. In a competition assay, the affinity of TG2 to a set of overlapping gamma-gliadin peptides was measured and compared with their recognition by celiac lesion T cells. Peptides differed considerably in their competition efficiency. Those peptides recognized by intestinal T cell lines showed marked competition indicating them as excellent substrates for TG2. The enzyme fine specificity of TG2 was characterized by synthetic peptide libraries and mass spectrometry. Residues in positions -1, +1, +2, and +3 relative to the targeted glutamine residue influenced the enzyme activity, and proline in position +2 had a particularly positive effect. The characterized sequence specificity of TG2 explained the variation between peptides as TG2 substrates indicating that the enzyme is involved in the selection of gluten T cell epitopes. The enzyme is mainly localized extracellularly in the small intestine where primary amines as substrates for the competing transamidation reaction are present. The deamidation could possibly take place in this compartment as an excess of primary amines did not completely inhibit deamidation of gluten peptides at pH 7.3. However, lowering of the pH decreased the reaction rate of the TG2-catalyzed transamidation, whereas the rate of the deamidation reaction was considerably increased. This suggests that the deamidation of gluten peptides by TG2 more likely takes place in slightly acidic environments.