Human endothelial cell adhesiveness for neutrophils, induced by Escherichia coli lipopolysaccharide in vitro, is inhibited by Bacteroides fragilis lipopolysaccharide

Recent studies in vitro have demonstrated that LPS from Gram-negative bacteria are capable of inducing endothelial cells to express a cell surface property that promotes the adherence of neutrophils (polymorphonuclear cells, PMN). We have investigated the effects of LPS from Bacteroides fragilis, an organism documented to have little toxicity in vivo, on the induction of this property in human endothelial cells. Monolayers of cultured human umbilical vein endothelial cells (HUVE) exhibited no increase in adhesiveness for 51Cr-radiolabeled PMN after 4 h of exposure to B. fragilis LPS from 1 ng to 10 micrograms/ml. Escherichia coli LPS elicited a dose-dependent enhancement of HUVE adhesiveness for PMN over the same concentration range, reaching a maximum of 49.4 +/- 6.6% at 10 micrograms/ml. Like E. coli LPS, B. fragilis LPS converted chromogenic substrate in the Limulus amebocyte lysate assay, and was directly cytotoxic to bovine aortic endothelial cells. Both B. fragilis LPS activities required doses two-to-three log-fold higher than for E. coli LPS. In addition, we found that B. fragilis LPS inhibited the induction of HUVE adhesiveness for PMN by E. coli LPS. This inhibition was also dose-dependent, becoming maximal (greater than 80%) when B. fragilis LPS was in 10- to 20-fold excess. Tumor necrosis factor and IL-1, two monokines which also elicit HUVE adhesiveness for PMN, were not inhibited by B. fragilis LPS, suggesting a mechanism of HUVE activation by LPS which is signal-specific, and which recognizes specificities of LPS structure.     

Sequencing and analysis of an Irish human genome

Background

Recent studies generating complete human sequences from Asian, African and European subgroups have revealed population-specific variation and disease susceptibility loci. Here, choosing a DNA sample from a population of interest due to its relative geographical isolation and genetic impact on further populations, we extend the above studies through the generation of 11-fold coverage of the first Irish human genome sequence.

Results

Using sequence data from a branch of the European ancestral tree as yet unsequenced, we identify variants that may be specific to this population. Through comparisons with HapMap and previous genetic association studies, we identified novel disease-associated variants, including a novel nonsense variant putatively associated with inflammatory bowel disease. We describe a novel method for improving SNP calling accuracy at low genome coverage using haplotype information. This analysis has implications for future re-sequencing studies and validates the imputation of Irish haplotypes using data from the current Human Genome Diversity Cell Line Panel (HGDP-CEPH). Finally, we identify gene duplication events as constituting significant targets of recent positive selection in the human lineage.

Conclusions

Our findings show that there remains utility in generating whole genome sequences to illustrate both general principles and reveal specific instances of human biology. With increasing access to low cost sequencing we would predict that even armed with the resources of a small research group a number of similar initiatives geared towards answering specific biological questions will emerge.     

Increased bone calcium following endurance exercise in the mature female rat

In order to determine the effects of exercise on the calcium status of selected axial and appendicular bones of mature rats, female Sprague-Dawley rats (8-9 mo.) were divided into three groups including, two months (E2, n = 8) or four months (E4, n = 9) of exercise, and four month sedentary controls (S, n = 10). Exercise consisted of treadmill running for 1 hr/day, 5 days/wk at a speed of 14.1 m/min and 8 degrees elevation. After sacrifice all femurs, tibia/fibula complexes, ribs (T7), and vertebrae (T7) were excised, cleaned, weighed and measured for length and volume. After freeze-drying and bone hydrolysis in 5N HCl, total bone calcium contents and concentrations were determined spectrophotometrically. The acid soluble, appendicular bone calcium contents of the E4 group were significantly greater than S for the femur and tibia respectively: E4 = 159.78 +/- 3.44 mg (mean +/- SEM), 129.46 +/- 4.87 mg; S = 140.03 +/- 5.04 mg, 110.40 +/- 4.71 mg. Bone calcium concentration (mg/g dry bone) also was significantly greater in the tibia/fibulas, ribs and vertebrae of the E4 group than the S group. With respect to other training-induced effects, the oxygen carrying capacity of the blood, as well as the heart and lung DNA and protein concentrations did not change after four months of exercise training. Within four months, moderate exercise can increase the calcium deposition in the bones of mature, female rats.     

On hits and being hit on: error management theory,signal detection theory,and the male sexual overperception bias

Although Error Management Theory (EMT) can explain male sexual overperception, more advanced Signal Detection Theory (SDT) analyses can identify sensitivity and bias separately. An SDT analysis of perceptions of relatively clear interest/disinterest signals (Study 1) found that sensitivity to sexual interest/disinterest signals drove participants' perceptions, rather than an overall bias to perceive sexual interest. Cues of interest were generally underperceived, while sensitivity and accuracy were uniformly high. EMT analysis also found overall sexual interest underperception, but with men slightly overperceiving interest relative to women. These discrepant results were due to EMT using difference scores, which obscure baseline perceptions for men and women. Individual differences in life history strategy, mating strategy, and mate value did not affect sensitivity or bias. Study 2 largely replicated these results using more ambivalent scenarios, except EMT analyses found men's misperception to be significantly larger than women's, despite being closer to pre-rated communication levels. These results show that sexual communication may be more nuanced than previously thought, and that an SDT analysis is more appropriate for such data.     

Conditional lethal mutants of the kilB determinant of broad host range plasmid RK2

We have examined the relationship of kilB to the other known determinants which map in the 14'-22' region of RK2. These are trfA, which encodes a diffusible replication function, and tra3, which specifies a function required for plasmid transmissibility. We found that, in addition to kilB, both tra3 and trfA functions are expressed by the cloned 14'-22' region of RK2. Four temperature-sensitive mutants of kilB were isolated by in vitro mutagenesis of the cloned segment. At 42 degrees C these mutant plasmids can be maintained in Escherichia coli cells which lack a korB+ helper plasmid. At 30 degrees C the helper plasmid is required. Our analysis of these mutants revealed that kilB function is distinct from those of trfA and tra3. One mutant plasmid was temperature-sensitive for maintenance of an RK2 ori plasmid, but this phenotype was shown to be independent of the KilB(ts) phenotype. Thus, kilB appears to be a separate new locus in this portion of the RK2 genome. In addition, these mutants allowed us to test for the existence of an essential replication determinant (trfB) in the 50.4'-56.4' region of RK2. Our results demonstrate that this region is non-essential for replication from the RK2 ori in E. coli. We propose an alternative hypothesis to explain the role of the RK2 trfB region for plasmid maintenance in E. coli.     

Common ancestry between IncN conjugal transfer genes and macromolecular export systems of plant and animal pathogens

The DNA sequence of a cluster of pKM101 conjugal transfer genes was determined and aligned with the genetic map of the plasmid. Eighteen genes were identified, at least eight and probably 11 of which are required for efficient conjugation. These tra genes are homologous to and colinear with genes found in the virB operon of Agrobacterium tumefaciens TI plasmids. Seven pKM101 tra genes are also homologous to ptl genes of Bordetella pertussis, which direct the export of pertussis toxin. We used TnphoA to construct translational fusions between pKM101 genes and the Escherichia coli phoA gene, which encodes alkaline phosphatase, and provide evidence that at least 11 of the 18 genes are either fully or partially exported from the cytoplasm.     

Reproductive traits of the freshwater oyster Etheria elliptica (Bivalvia: Etheriidae) in the Pendjari River,Benin: implications for conservation

The African freshwater oyster Etheria elliptica, which is of great economic importance throughout the continent, is facing overharvesting in many fisheries in West Africa. Its reproductive traits (sex ratio, size at sexual maturity, oocyte diameter and fecundity) were studied at four stations located along the Pendjari River, northern Benin, in April 2013. Histological techniques were implemented to identify sex and gonad development stages. Oocyte sizes were measured based on the histological images and mean oocyte diameter was 38 µm. Fecundity, estimated by counting the developing eggs, averaged 106 724 eggs and increased significantly with shell size. The average sex ratio was approximately 1:1. Hermaphrodites were rare. Males reached sexual maturity at 57.6 mm dorsoventral height, earlier than females at 64.7 mm. The majority of the oyster specimens were in ripe-spawning stages, indicating that reproductive activities partly took place towards the end of the dry season. Both mature and immature individuals were subjected to harvesting at all the investigated fishing sites. The mean size of exploited oysters was 60.6 mm, lower than the size of females at maturity. Management strategies must enforce the minimum size of 65 mm required for harvesting, particularly in open access sites where juveniles are mostly harvested.