The 3-hydroxyacyl-ACP dehydratase of mitochondrial fatty acid synthesis in Trypanosoma brucei

The trypanosomatid parasite Trypanosoma brucei synthesizes fatty acids in the mitochondrion using the type II fatty acid synthesis (FAS) machinery. When mitochondrial FAS was characterized in T. brucei, all of the enzymatic components were identified based on their homology to yeast mitochondrial FAS enzymes, except for 3-hydroxyacyl-ACP dehydratase. Here we describe the characterization of T. brucei mitochondrial 3-hydroxyacyl-ACP dehydratase (TbHTD2), which was identified by its similarity to the human mitochondrial dehydratase. TbHTD2 can rescue the respiratory deficient phenotype of the yeast knock-out strain and restore the lipoic acid content, is localized in the mitochondrion and exhibits hydratase 2 activity.     

Persistent joint swelling and Borrelia-specific antibodies in Borrelia garinii-infected mice after eradication of vegetative spirochetes with antibiotic treatment

We wanted to study the pathogenesis and the long-term manifestations of Borrelia garinii infection in SJL and C3H/He mice. We report here that B. garinii A218 causes a persisting infection in these mouse strains. Mice infected with intracutaneous inoculation of B. garinii at 4-5 weeks of age developed a disseminated infection and joint swelling within 2 weeks of inoculation and remained infected with joint symptoms until the end of follow-ups of up to 52 weeks. Treatment with ceftriaxone or ampicillin at 18 or 44 weeks of infection did not affect the joint swelling during the follow-ups of 19 and 8 weeks, respectively. However, B. garinii could not be cultured from any of the post mortem tissue samples of the treated mice, whereas the spirochete grew from samples of all untreated infected animals. Borrelia-specific IgG antibodies were detectable after 2 weeks of infection, and in late infection, all mice had high anti-borrelia IgG levels. Antibiotic treatment had no effect on antibody levels. Histology showed only slight changes in the joints of the infected mice with occasional lymphocyte infiltration, synovial proliferation and slight involvement of the Achilles' tendon. No difference was seen in the findings between ceftriaxone-treated and untreated mice. The results suggest that the presence of vegetative spirochetes is no prerequisite for persisting joint symptoms and elevated anti-borrelia IgG levels in these B. garinii-infected mice.     

Species immigration, extinction and turnover of vascular plants in boreal lakes

Dictated by limited resource availability for land acquisition, a central question in conservation biology is the ability of areas of different size to maintain species diversity. The selected reserves should not only be species rich at the moment, but should also maintain species diversity in the long run. We used two sets of data on vascular plant species in boreal lakes collected in 1933/34 and 1996 to test the relationships between lake area and the extinction, immigration and turnover rates of the species. Moreover, we investigated, whether the number of species in 1933/34 or water connection between lakes was related to extinction, immigration and turnover rates of species. We found that lake area or shoreline length was not correlated with immigration or turnover rate. But extinction rate was slightly negatively correlated with shoreline length. The original number of species was positively related to the number of species extinctions and to the absolute turnover rate in the lakes, which indicates that species richness does not create stability in these communities. Species number was not correlated with immigration rate. Upstream water connections in the lakes did not affect immigration, extinction or turnover rates. We conclude that length of the shoreline is a better measure of suitable area for water plants than the lake area, and that because the correlation between shoreline length and extinction rate was slight, also small lakes can be valuable for conservation.     

Plasma progesterone concentration depends on sampling site in pigs

The objective of this study was to examine a possible difference in progesterone concentrations between the systemic venous blood and the caudal vena cava in early pregnant gilts. Nineteen crossbred pregnant gilts were offered three different regimens of feeding to examine influence of feeding on the secretion pattern of progesterone. The groups were high (H-H), low (L-L) and low-high (L-H) receiving 3.6, 1.8 and 1.8/3.6 kg/day, respectively. Catheters were placed in a jugular vein and the caudal vena cava (to sample ovarian secretion) on day 19 of pregnancy. Two consecutive samples taken at 30-min intervals were collected four times a day for 5 days (days 20-24). In addition, three gilts were simultaneously sampled from both catheters at 30-min intervals for 12 h on day 22. Progesterone concentration was significantly lower in the jugular vein compared with the caudal vena cava in all three feeding groups (P<0.001). An indication of episodic pattern of progesterone production occurred in plasma collected from the caudal vena cava, but not from the jugular vein. Dietary intake did not cause a profound effect on plasma progesterone concentrations during days 20-24 of gestation. It seemed that ovarian progesterone was released into the vena cava in an episodic pattern and there were implications that these episodes were temporally associated with LH pulses.     

Microbial growth inside insulated external walls as an indoor air biocontamination source

The association between moisture-related microbial growth (mesophilic fungi and bacteria) within insulated exterior walls and microbial concentrations in the indoor air was studied. The studied apartment buildings with precast concrete external walls were situated in a subarctic zone. Actinomycetes in the insulation layer were found to have increased concentrations in the indoor air. The moisture content of the indoor air significantly affected all measurable airborne concentrations.     

Modulation of DNA single-strand breaks by intracellular glutathione in human lung cells exposed to asbestos fibers

We investigated the role of glutathione and nitric oxide synthase (NOS) in fiber-induced cell and DNA toxicity using alkaline (pH 13) single-cell gel electrophoresis (the Comet assay). Transformed cultured human pleural mesothelial (MeT-5A) cells and alveolar epithelial cells (A549) were exposed to crocidolite asbestos fibers (1-10 microg/cm(2)) in the presence of buthionine sulfoximine (BSO) or L-arginine-methyl ester (L-NAME). BSO inhibits gamma-glutamylcysteine synthetase (gamma-GCS) and causes glutathione depletion, and L-NAME inhibits nitric oxide generation. Studies were also conducted to assess the expression of the heavy and light subunits of gamma-GCS in human pleural mesothelium and bronchial epithelium in vivo and the induction of inducible NOS (iNOS) by asbestos fibers. Asbestos fibers caused DNA single-strand breaks, and the process was significantly enhanced by BSO (69% compared to the non-treated cells). A549 cells had a 3.5-fold glutathione content compared to MeT-5A cells, which was consistent with the higher resistance of these cells against oxidants and fibers. Flow cytometry of iNOS showed no change of iNOS by the fibers in either cell type in vitro. L-NAME had no effects on the DNA single-strand breaks in the Comet assay, either. Studies on lung biopsies showed that the immunoreactivities of both gamma-GCS subunits were very low in healthy human mesothelium in vivo. We conclude that glutathione may play an essential role in protecting intact cells against fiber-induced oxidative DNA alterations, and low gamma-GCS reactivity in pleural mesothelium may be associated with the high sensitivity of mesothelial cells to fiber-induced toxicity.     

Hot spots, indicator taxa, complementarity and optimal networks of taiga

If hot spots for different taxa coincide, priority-setting surveys in a region could be carried out more cheaply by focusing on indicator taxa. Several previous studies show that hot spots of different taxa rarely coincide. However, in tropical areas indicator taxa may be used in selecting complementary networks to represent biodiversity as a whole. We studied beetles (Coleoptera), Heteroptera, polypores or bracket fungi (Polyporaceae) and vascular plants of old growth boreal taiga forests. Optimal networks for Heteroptera maximized the high overall species richness of beetles and vascular plants, but these networks were least favourable options for polypores. Polypores are an important group indicating the conservation value of old growth taiga forests. Random selection provided a better option. Thus, certain groups may function as good indicators for maximizing the overall species richness of some taxonomic groups, but all taxa should be examined separately.     

Microbial Growth Inside Insulated External Walls as an Indoor Air Biocontamination Source

The association between moisture-related microbial growth (mesophilic fungi and bacteria) within insulated exterior walls and microbial concentrations in the indoor air was studied. The studied apartment buildings with precast concrete external walls were situated in a subarctic zone. Actinomycetes in the insulation layer were found to have increased concentrations in the indoor air. The moisture content of the indoor air significantly affected all measurable airborne concentrations.     

Molecular phylogeny and proposed classification of the simian picornaviruses.

The simian picornaviruses were isolated from various primate tissues during the development of general tissue culture methods in the 1950s to 1970s or from specimens derived from primates used in biomedical research. Twenty simian picornavirus serotypes are recognized, and all are presently classified within the Enterovirus genus. To determine the phylogenetic relationships among all of the simian picornaviruses and to evaluate their classification, we have determined complete VP1 sequences for 19 of the 20 serotypes. Phylogenetic analysis showed that A13, SV19, SV26, SV35, SV43, and SV46 are members of human enterovirus species A, a group that contains enterovirus 71 and 11 of the coxsackie A viruses. SA5 is a member of human enterovirus species B, which contains the echoviruses, coxsackie B viruses, coxsackievirus A9, and enterovirus 69. SV6, N125, and N203 are related to one another and, more distantly, to species A human enteroviruses, but could not be definitely assigned to a species. SV4 and SV28 are closely related to one another and to A-2 plaque virus, but distinct from other enteroviruses, suggesting that these simian viruses are members of a new enterovirus species. SV2, SV16, SV18, SV42, SV44, SV45, and SV49 are related to one another but distinct from viruses in all other picornavirus genera, suggesting that they may comprise a previously unknown genus in Picornaviridae. Several simian virus VP1 sequences (N125 and N203; SV4 and SV28; SV19, SV26, and SV35; SV18 and SV44; SV16, SV42, and SV45) are greater than 75% identical to one another (and/or greater than 85% amino acid identity), suggesting that the true number of distinct serotypes among the viruses surveyed is less than 20.