Trees on networks: resolving statistical patterns of phylogenetic similarities among interacting proteins

Background  

Phylogenies capture the evolutionary ancestry linking extant species. Correlations and similarities among a set of species are mediated by and need to be understood in terms of the phylogenic tree. In a similar way it has been argued that biological networks also induce correlations among sets of interacting genes or their protein products.     

Evaluation of two communication tools,slideshow and theater,to improve participants’ understanding of a clinical trial in the informed consent procedure on Pemba Island,Tanzania

BackgroundClinical trial participants are required to sign an informed consent form (ICF). However, information is lacking on the most effective methods to convey trial relevant information prior to inviting participants to sign the ICF, being particularly pertinent in low-income countries. A previous study on Pemba Island, Tanzania, found that a verbal information session (IS) was significantly better than providing an ICF alone. However, knowledge gaps remained. Building on these findings, we investigated the effect of adding a slideshow or a theater to the IS in the informed consent procedure of an anthelminthic clinical trial.Methodology/principal findingsA total of 604 caregivers were randomized into the control group that only received an ICF (n = 150) or an ICF plus one of three intervention strategies: (i) verbal IS (n = 135), (ii) verbal IS with a slideshow (n = 174) or (iii) verbal IS followed by a theater (n = 145). All modes of information covered the same key messages. Participants’ understanding was assessed using a semi-structured questionnaire. The mean score of caregivers in the control group (ICF only) was 4.41 (standard deviation = 1.47). Caregivers attending the IS alone were more knowledgeable than those in the control group (estimated difference in mean scores: 2.40, 95% confidence interval (CI) 1.95 to 2.86, p < 0.01). However, there was no evidence of an improvement compared to the IS only when participants attended a slideshow (0.09, 95% CI -0.53 to 0.35, p = 0.68) or a theater (0.28, 95% CI -0.27 to 0.82, p = 0.32). Three out of 10 key messages remained largely misunderstood, regardless of the mode of information group.Conclusions/significanceOur study confirmed that, in this setting, an ICF alone was not sufficient to convey clinical trial-related information. An IS was beneficial, however, additional theater and slideshows did not further improve understanding. Future research should explore methods to improve communication between study teams and participants for different key messages, study types and settings.     

Nonlinear increase of elongation rate of actin filaments with actin monomer concentration

The nonlinear increase of the elongation rate of actin filaments above the critical monomer concentration was investigated by nucleated polymerization of actin. Significant deviations from linearity were observed when actin was polymerized in the presence of magnesium ions. When magnesium ions were replaced by potassium or calcium ions, no deviations from linearity could be detected. The nonlinearity was analyzed by two simple assembly mechanisms. In the first model, if the ATP hydrolysis by polymeric actin is approximately as fast as the incorporation of monomers into filaments, terminal subunits of lengthening filaments are expected to carry to some extent ADP. As ADP-containing subunits dissociate from the ends of actin filaments faster than ATP-containing subunits, the rate of elongation of actin filaments would be nonlinearly correlated with the monomer concentration. In the second model (conformational change model), actin monomers and filament subunits were assumed to occur in two conformations. The association and dissociation rates of actin molecules in the two conformations were thought to be different. The equilibrium distribution between the two conformations was assumed to be different for monomers and filament subunits. The ATP hydrolysis was thought to lag behind polymerization and conformational change. As under the experimental conditions the rate of ATP hydrolysis by polymeric actin was independent of the concentration of filament ends, the observed nonlinear increase of the rate of elongation with the monomer concentration above the critical monomer concentration was unlikely to be caused by ATP hydrolysis at the terminal subunits. The conformational change model turned out to be the simplest assembly mechanism by which all available experimental data could be explained.     

南瓜雌蕊与自花及远缘花粉的相互作用

南瓜柱头表面经去垢剂、蛋白酶及Con A处理后花粉不能萌发或花粉管生长受阻,Con A能专一地与柱头表面结合。柱头块加入培养液可促进花粉萌发。不同的远缘花粉授粉后在雌蕊不同部位受阻。在成熟南瓜雌蕊提取液中检测到血凝活性,凝集素可能参与雌蕊对远缘花粉的抑制。     

Urinary excretion of immunoreactive prostaglandin E: A circadian rhythm and the effect of posture

The excretion of urinary immunoreactive prostaglandin E (iPGE), sodium, potassium, creatinine and volume was studied in 4 hr collections in normal women at normal activity. iPGE exhibited a circadian rhythm with an amplitude of 29% and peak excretion at 4:55 P.M. There were also significant circadian rhythms for sodium, potassium, creatinine, and volume, all peaking in late afternoon. There were no significant changes either in the total excretion or in the circadian rhythms of iPGE, potassium, or creatinine excretion when the subjects remained in bed for an entire day while the circadian rhythms of sodium and volume were significantly modified in amplitude and phase, respectively. Urinary aldosterone excretion decreased significantly when the subjects were at bed rest. iPGE excretion increased 33% when subjects were first recumbent and then erect for consecutive 4 hr periods on the same day (but when subjects were erect 1 day for a 4 hr period, iPGE excretion was lower by 32% than for the same 4 hr period the preceding day when they were recumbent). These data indicate that: 1) the sympathetic nervous system and renin-angiotensin-aldosterone system do not affect the circadian rhythm of urinary iPGE, and 2) short-term experiments of prostaglandin E excretion must be designed to avoid misleading results due to the circadian rhythm.