Trypanosoma cruzi heat-shock protein-70 kDa,alone or fused to the parasite KMP11 antigen,induces functional maturation of murine dendritic cells

We analyse the effect of Trypanosoma cruzi heat-shock protein-70 (HSP70) on the maturation of murine dendritic cells (DC)generated from bone marrow precursor cells. The results obtained show that HSP70, both alone and fused to the KMP11 antigen, as well as a HSP70 fragment, is capable of maturing murine DC. Mature DC have enhanced expression of IL12, TNF-alpha cytokines, costimulation molecules and activation markers, showing a clear increase in the allostimulatory capacity. These findings suggest that T. cruzi HSP70 may be a very useful vehicle for developing DC-based immunoprophylaxis and therapy against infections.     

A comparison of two culture media for the recovery of thermophilic campylobacters in broiler farm samples

A study to evaluate the performance of two different brands of media (Oxoid, Basingstoke, UK, and Mast Diagnostics, Merseyside, UK) for the isolation of thermophilic campylobacters from a range of broiler farm samples was undertaken. Oxoid media performed significantly better than the Mast formulations with overall Campylobacter recovery rates of 46% and 30.5%, respectively, observed from 213 samples tested (p< or =0.05). Consistently higher recoveries of campylobacters were observed from all samples when the results using both types of media were combined.     

Components of spatial patterning in a serpentine grassland

We analyzed the components of spatial patterning in species abundance in a diverse grassland dominated by early season, annual forbs. Species abundance, soil depth and gopher disturbances were measured by means of a nested spatial design on two 8m×20m plots that differed in the amount of larger scale variability in soil depth. Species distributions at the scale of the 10cm×10cm quadrat were highly clumped, with a decline in clumping with mean abundance. Even with the effect of abundance on clumping removed, species showed differences in the degree of clumping and these differences were consistent between the two plots. The abundance of the species and the frequency of disturbance correlated weakly to moderately with soil depth. Semivariance analyses indicated that the most common species all showed complex spatial patterning at a range of scales. Some of this variation corresponded to patterns of soil depth variation and patterns of gopher disturbance; however, a large amount of the spatial patterning in species abundance remains unexplained.     

In vivo analysis of cohesin architecture using FRET in the budding yeast Saccharomyces cerevisiae

Cohesion between sister chromatids in eukaryotes is mediated by the evolutionarily conserved cohesin complex. Cohesin forms a proteinaceous ring, large enough to trap pairs of replicated sister chromatids. The circumference consists of the Smc1 and Smc3 subunits, while Scc1 is thought to close the ring by bridging the Smc (structural maintenance of chromosomes) ATPase head domains. Little is known about two additional subunits, Scc3 and Pds5, and about possible conformational changes of the complex during the cell cycle. We have employed fluorescence resonance energy transfer (FRET) to analyse interactions within the cohesin complex in live budding yeast. These experiments reveal an unexpected geometry of Scc1 at the Smc heads, and suggest that Pds5 plays a role at the Smc hinge on the opposite side of the ring. Key subunit interactions, including close proximity of the two ATPase heads, are constitutive throughout the cell cycle. This depicts cohesin as a stable molecular machine undergoing only transient conformational changes during binding and dissociation from chromosomes. Using FRET, we did not observe interactions between more than one cohesin complex in vivo.     

Trail-Following Behaviour in the Malacophagous Larvae of the Aquatic Sciomyzid Flies <Emphasis Type="Italic">Sepedon spinipes spinipes</Emphasis> and <Emphasis Type="Italic">Dictya montana</Emphasis>

The ability of neonate larvae of the aquatic sciomyzids, Sepedon spinipes spinipes (Scopoli) and Dictya montana Steyskal (Diptera), to follow snail mucus trails was assessed using filter paper Y-mazes. On finding a mucus trail, larval behaviour of both species switched from unstimulated to stimulated searching behaviour, the latter being characterised by an increase in larval velocity and the frequency of lateral head taps. When fresh mucus trails were used, all of the neonates displayed a positive response and followed the mucus trail into the experimental arm. In addition, for S. s. spinipes and D. montana 80.00% and 86.67% of larvae respectively exhibited a strong response and followed the trail to its end. The stimulatory substance (s), however, appears to become inactive with time and after 45 minutes none of the tested larvae reached the trail end. These results are discussed in relation to the ability of aquatic species to forage outside of water for prey and the implications for their use in the biological control of nuisance snails.     

Altered Mechanical Environment of Bone Cells in an Animal Model of Short- and Long-Term Osteoporosis

Alterations in bone tissue composition during osteoporosis likely disrupt the mechanical environment of bone cells and may thereby initiate a mechanobiological response. It has proved challenging to characterize the mechanical environment of bone cells in vivo, and the mechanical environment of osteoporotic bone cells is not known. The objective of this research is to characterize the local mechanical environment of osteocytes and osteoblasts from healthy and osteoporotic bone in a rat model of osteoporosis. Using a custom-designed micromechanical loading device, we apply strains representative of a range of physical activity (up to 3000 με) to fluorescently stained femur samples from normal and ovariectomized rats. Confocal imaging was simultaneously performed, and digital image correlation techniques were applied to characterize cellular strains. In healthy bone tissue, osteocytes experience higher maximum strains (31,028 ± 4213 με) than osteoblasts (24,921 ± 3,832 με), whereas a larger proportion of the osteoblast experiences strains >10,000 με. Most interestingly, we show that osteoporotic bone cells experience similar or higher maximum strains than healthy bone cells after short durations of estrogen deficiency (5 weeks), and exceeded the osteogenic strain threshold (10,000 με) in a similar or significantly larger proportion of the cell (osteoblast, 12.68% vs. 13.68%; osteocyte, 15.74% vs. 5.37%). However, in long-term estrogen deficiency (34 weeks), there was no significant difference between bone cells in healthy and osteoporotic bone. These results suggest that the mechanical environment of bone cells is altered during early-stage osteoporosis, and that mechanobiological responses act to restore the mechanical environment of the bone tissue after it has been perturbed by ovariectomy.     

STS markers linked to the Rf 1 fertility restorer gene of cotton

Marker-assisted selection (MAS) can accelerate the process of plant breeding, and sequence-tagged site (STS) markers are highly specific for regions of DNA being used for MAS. The objective of this research was to develop STS markers tightly linked with Rf₁, the fertility restoring gene for cytoplasmic male sterility (CMS) in cotton (Gossypium hirsutum L.). Bulked segregant analysis was employed to screen for Rf₁-linked RAPD markers in a backcross population. Four RAPD markers were identified, three of which co-segregated with Rf₁ (UBC147₁₄₀₀, UBC607₅₀₀, and UBC679₇₀₀). Another fragment, UBC169₈₀₀, co-segregated with the previously reported UBC169₇₀₀ in repulsion phase at a distance of 4.5 cM from Rf₁. A marker published by others (UBC659₁₅₀₀) mapped to 2.7 cM from Rf₁ and 1.8 cM from UBC169₈₀₀. Four sets of STS primer pairs were designed based on the RAPD fragment sequences. The primer pairs from the UBC147₁₄₀₀ and UBC607₅₀₀ fragments both amplified a single fragment specific to fertile plants. The UBC679₇₀₀ and UBC659₁₅₀₀ STS primer pairs each amplified one fragment specific to fertile plants and a monomorphic fragment. These four Rf₁-linked STS markers were also present in the Rf₁ donor species G. harknessii (D_2-2). The three primer pairs that produced co-segregating STS markers also amplified fragments from G. trilobum (D₈). However, the D₈ fragment amplified by the UBC147₁₄₀₀ STS primers was larger than that from D_2-2, and G. trilobum does not restore fertility to CMS-D2-2 lines. These STS markers will be useful in the development of restorer parental lines in cotton CMS breeding efforts.     

Identification of the lower baseplate protein as the antireceptor of the temperate lactococcal bacteriophages TP901-1 and Tuc2009

The first step in the infection process of tailed phages is recognition and binding to the host receptor. This interaction is mediated by the phage antireceptor located in the distal tail structure. The temperate Lactococcus lactis phage TP901-1 belongs to the P335 species of the Siphoviridae family, which also includes the related phage Tuc2009. The distal tail structure of TP901-1 is well characterized and contains a double-disk baseplate and a central tail fiber. The structural tail proteins of TP901-1 and Tuc2009 are highly similar, but the phages have different host ranges and must therefore encode different antireceptors. In order to identify the antireceptors of TP901-1 and Tuc2009, a chimeric phage was generated in which the gene encoding the TP901-1 lower baseplate protein (bppL(TP901-1)) was exchanged with the analogous gene (orf53(2009)) of phage Tuc2009. The chimeric phage (TP901-1C) infected the Tuc2009 host strain efficiently and thus displayed an altered host range compared to TP901-1. Genomic analysis and sequencing verified that TP901-1C is a TP901-1 derivative containing the orf53(2009) gene in exchange for bppL(TP901-1); however, a new sequence in the late promoter region was also discovered. Protein analysis confirmed that TP901-1C contains ORF53(2009) and not the lower baseplate protein BppL(TP901-1), and it was concluded that BppL(TP901-1) and ORF53(2009) constitute antireceptor proteins of TP901-1 and Tuc2009, respectively. Electron micrographs revealed altered baseplate morphology of TP901-1C compared to that of the parental phage.