Self seeks like: many humans choose their dog pets following rules used for assortative mating

Theoretical and experimental studies suggest that mating and pair formation are not likely to be random. Assortative mating, characterized as self seeking like, seems to be widely practiced in nature. Experimental evidence for it is strong among humans seeking a mate. Assortative mating increases the probability of finding a genetically similar mate, without fomenting inbreeding, achieving assortative mating without hindering the working of other mate-selection strategies that aim to maximize the search for good genes, optimizing the working of sex in evolutionary terms. Self seeking like seems to be a behavioural inborn trait among humans, and here we present evidence that the same behavioural mechanism seems to be at work when humans choose a pet. We show that in a significant proportion of human–pet pairs, sampled in pet beauty contests, the partners show much higher facial resemblances than can be expected by random pair formation.     

An evaluation of the suitability of the European suspension test to reflect in vitro activity of antiseptics against clinically significant organisms

The effectiveness of four antiseptics representing soluble phenolics (Dettol), Quaternary Ammonium Compounds (QAC) (Dettol Hospital Concentrate: DHC), mixed QAC/chlorhexidine (Hibicet Hospital Concentrate: HHC) and povidone iodine (Betadine) was assessed using the proposed phase 2 step 1 European Suspension test. The in vitro activity of the antiseptics against two of the proposed challenge strains, i.e. Staphylococcus aureus and Pseudomonas aeruginosa, was compared with that of 14 problematic clinical isolates of bacteria from a range of genera, including some multiple antibiotic resistant strains, and a clinical isolate of Candida albicans. In addition to the 5 min contact time recommended in the European test, a 1 min time was included. All four products, at their recommended use dilutions and a contact time of 5 min, achieved a Microbicidal Effect (ME) log reduction of at least 5 against the majority of organisms. Differences in activity between products were more pronounced and therefore the tests more discriminatory, when the contact time was reduced to 1 min. The clinical strains were not overtly more resistant to antiseptics than the standard test strains, suggesting that the CEN test strains mimic the antiseptic susceptibility of clinical isolates.     

Developments from analysis of variance through to generalized linear models and beyond

The collaborations between statisticians and biologists during the 100 years since AAB was founded have led to a very impressive list of statistical techniques, whose use now goes well beyond agriculture and biology. One example is the maximum likelihood methodology for probit analysis, arising from the collaboration between Sir Ronald Fisher and Chester Bliss. Others include analysis of variance, design of experiments, generalized linear models and the residual, or restricted, maximum likelihood (REML) algorithm for fitting unbalanced linear mixed models.     

A rapid purification procedure and computer-assisted sulfide ion selective electrode assay for O-acetylserine sulfhydrylase from Salmonella typhimurium

An improved method for purifying O-acetylserine sulfhydrylase from Salmonella typhimurium is described as well as a new computer-controlled assay making use of the sulfide ion selective electrode. The purification method uses gradient elution from Q-Sepharose Fast Flow and phenyl-Sepharose columns to give 75 mg (50% yield) of the enzyme starting from 300 g of starting material in 3 days. The sulfide electrode assay makes use of sulfide and calomel electrodes attached to a signal buffer which serves as an impedance match. The output of the signal buffer is linked in parallel to a strip chart recorder and a Keithley Model 575 data acquisition and control system. The system 575 is interfaced to a Packard-Bell AT computer. In addition, two BASIC computer programs have been written to convert potential measured by the electrode to sulfide concentration and to convert the time course data to rates.     

The use of immobilized lectins in the separation of Staphylococcus aureus, Escherichia coli, Listeria and Salmonella spp. from pure cultures and foods

Lectins from Helix pomatia, Canavalia ensiformis, Agaricus bisporus and Triticum vulgaris agglutinated cultures of Staphylococcus aureus, Escherichia coli, Listeria and Salmonella spp. This agglutination was specific as it was inhibited (except with A. bisporus lectin) by the competing sugar substrates. The ability of three of these lectins, immobilized on a variety of supports, to separate these micro-organisms from pure cultures was investigated. Immobilization of the lectins on magnetic microspheres was the most effective method. Immobilized T. vulgaris lectin bound 87–100% of cells from cultures of L. monocytogenes , 80–100% of Staph. aureus , 33–45% of Salmonella spp. and 42–77% of E. coli. The A. bisporus lectin bound 31–63% of cells in cultures of L. monocytogenes , 83% of Staph. aureus but only 3–5% of the salmonella cells. Similarly H. pomatia lectin bound >92% of Staph. aureus and 64% of L. monocytogenes cells but was poor at binding the Gram-negative organisms. This preference for binding Gram-positive organisms was confirmed when mixed cultures were studied. The T. vulgaris lectin was effective in removing L. monocytogenes (43%) and Staph. aureus (26%) from diluted milk and Salmonella (31–54%) from raw egg. Agaricus bisporus lectin removed L. monocytogenes from undiluted milk (10–47%) or ground beef (32–50%).     

Quantification of hypoxic regions distant from occlusions in cerebral penetrating arteriole trees

The microvasculature plays a key role in oxygen transport in the mammalian brain. Despite the close coupling between cerebral vascular geometry and local oxygen demand, recent experiments have reported that microvascular occlusions can lead to unexpected distant tissue hypoxia and infarction. To better understand the spatial correlation between the hypoxic regions and the occlusion sites, we used both in vivo experiments and in silico simulations to investigate the effects of occlusions in cerebral penetrating arteriole trees on tissue hypoxia. In a rat model of microembolisation, 25 μm microspheres were injected through the carotid artery to occlude penetrating arterioles. In representative models of human cortical columns, the penetrating arterioles were occluded by simulating the transport of microspheres of the same size and the oxygen transport was simulated using a Green’s function method. The locations of microspheres and hypoxic regions were segmented, and two novel distance analyses were implemented to study their spatial correlation. The distant hypoxic regions were found to be present in both experiments and simulations, and mainly due to the hypoperfusion in the region downstream of the occlusion site. Furthermore, a reasonable agreement for the spatial correlation between hypoxic regions and occlusion sites is shown between experiments and simulations, which indicates the good applicability of in silico models in understanding the response of cerebral blood flow and oxygen transport to microemboli.     

Microbial 16S rRNA Ion Tag and community metagenome sequencing using the Ion Torrent (PGM) Platform

Here we demonstrate a cost effective and scalable microbial ecology sequencing platform using the Ion Torrent Personal Genome Machine (PGM). We assessed both PCR amplified 16S rRNA and shotgun metagenomic approaches and generated 100,000+ to 1,000,000+ reads using 'post-light' based sequencing technology within different sized semi-conductor chips. Further development of Golay barcoded Ion Tags allowed multiplex analyses of microbial communities with substantially reduced costs compared with platforms such as 454/GS-FLX. Using these protocols we assessed the bacterial and archaeal dynamics within covered anaerobic digesters used to treat piggery wastes. Analysis of these sequence data showed that these novel methanogenic waste treatment systems are dominated by bacterial taxa, in particular Clostridium, Synergistia and Bacteroides that were maintained as a stable community over extended time periods. Archaeal community dynamics were more stochastic with the key methanogenic taxa more difficult to resolve, principally due to the poor congruence seen between community structures generated either by nested PCR or metagenomic approaches for archaeal analyses. Our results show that for microbial community structure and function analyses, the PGM platform provides a low cost, scalable and high throughput solution for both Tag sequencing and metagenomic analyses.     

Ikaros isoform x is selectively expressed in myeloid differentiation

The Ikaros gene is alternately spliced to generate multiple DNA-binding and nonbinding isoforms that have been implicated as regulators of hematopoiesis, particularly in the lymphoid lineages. Although early reports of Ikaros mutant mice focused on lymphoid defects, these mice also show significant myeloid, erythroid, and stem cell defects. However, the specific Ikaros proteins expressed in these cells have not been determined. We recently described Ikaros-x (Ikx), a new Ikaros isoform that is the predominant Ikaros protein in normal human hematopoietic cells. In this study, we report that the Ikx protein is selectively expressed in human myeloid lineage cells, while Ik1 predominates in the lymphoid and erythroid lineages. Both Ik1 and Ikx proteins are expressed in early human hematopoietic cells (Lin(-)CD34(+)). Under culture conditions that promote specific lineage differentiation, Ikx is up-regulated during myeloid differentiation but down-regulated during lymphoid differentiation from human Lin(-)CD34(+) cells. We show that Ikx and other novel Ikaros splice variants identified in human studies are also expressed in murine bone marrow. In mice, as in humans, the Ikx protein is selectively expressed in the myeloid lineage. Our studies suggest that Ikaros proteins function in myeloid, as well as lymphoid, differentiation and that specific Ikaros isoforms may play a role in regulating lineage commitment decisions in mice and humans.