Penicillin-binding proteins 4 and 5 of Haemophilus influenzae are involved in cell wall incorporation

Abstract Permeabilized cells of Haemophilus influenzae incorporate wall precursors into murein material in an ampicillin-sensitive reaction. In resistant transformants that contain the low antibiotic affinity penicillin-binding proteins (PBPs) 4 and 5, the sensitivity of this incorporation reaction to ampicillin is proportionally lower, suggesting a catalytic role for these proteins in wall synthesis. We conclude that, analogous to the reaction in Escherichia coli , PBPs 4 and 5 of H. influenzae have transpeptidase activity.     

Natural incorporation of mercury in bone

Mercury (Hg) is a highly toxic element that causes bone defects and malformations. Structure and surface analyses using quantitative x-ray diffraction using the Rietveld method, High-Resolution Transmission Electron Microscopy and nanodiffraction analyses, and Fourier-Transformed Infrared spectroscopy showed that bone enriched naturally with Hg (≤ 2.3 %) contained Hg₃PO₄ [(Hg₂)₃(PO₄)₂] and HgO. Bone [mostly as apatite, verified as carboxyapatite Ca₁₀(PO₄)₄(CO₃)₃(OH)₂(s)] and cinnabar (HgS) dissolved releasing Hg⁺ (existing as dimer Hg₂²⁺) and PO₄³⁻, both of which became immobilized as (Hg₂)₃(PO₄)₂. Besides, released Hg²⁺ became oxidized to form HgO. The outcome of this work is novel, provided that only a handful of stable compounds of Hg₂²⁺ are found in nature.     

The transient and constitutive inflammatory signaling in tumorigenesis

Comment on: Rokavec M, et al. Mol Cell 2012; 45:777-89.     

Semiparametric Regression in Size-Biased Sampling

Summary .  Size-biased sampling arises when a positive-valued outcome variable is sampled with selection probability proportional to its size. In this article, we propose a semiparametric linear regression model to analyze size-biased outcomes. In our proposed model, the regression parameters of covariates are of major interest, while the distribution of random errors is unspecified. Under the proposed model, we discover that regression parameters are invariant regardless of size-biased sampling. Following this invariance property, we develop a simple estimation procedure for inferences. Our proposed methods are evaluated in simulation studies and applied to two real data analyses.     

Regeneration of Triticum aestivum apical explants after microinjection of germ line progenitor cells with DNA

A highly efficient method of regenerating fertile, phenotypically normal plants from shoot apex cultures of T. aestivum was developed. The hypodermal layer (L2) of the vegetative apex containing germ line precursor cells could be located with bright field microscopy and targeted for microinjection. Fluorescently labelled dextrans were used as markers to develop a microinjection procedure which did not disrupt nuclear or cytoplasmic structure. This procedure was used to inject plasmid DNA into L2 cells. Capillary microinjection did not shear the plasmid DNA and delivery of DNA was confirmed by polymerase chain reaction analysis of DNA isolated from injected apices. The significance of these findings in relation to the development of cereal transformation systems will be discussed.     

Influence of feeding schedules on the chronobiology of renin activity,urinary electrolytes and blood pressure in dogs

The contribution of the renin–angiotensin–aldosterone system (RAAS) to the development of congestive heart failure (CHF) and hypertension (HT) has long been recognized. Medications that are commonly used in the course of CHF and HT are most often given with morning food for the sake of convenience and therapeutic compliance. However, biological rhythms and their responsiveness to environmental clues such as food intake may noticeably impact the effectiveness of drugs used in the management of cardiovascular disorders. Only sparse information about the effect of feeding schedules on the biology of the RAAS and blood pressure (BP) is presently available. Two studies were designed to explore the chronobiology of renin activity (RA), BP, renal sodium (U_Na,fe) and potassium (U_K,fe) handling in relation to meal timing in dogs. In a first experiment (Study a), blood and urinary samples for measurement of RA, U_Na,fe and U_K,fe were drawn from 18 healthy beagle dogs fed a normal-sodium diet at either 07:00, 13:00 or 19:00?h. In a second experiment (Study b), BP was recorded continuously from six healthy, telemetered beagle dogs fed a similar diet at 07:00, or 19:00?h. Data were collected throughout 24-h time periods, and analyzed by means of nonlinear mixed-effects models. Differences between the geometric means of early versus late time after feeding observations were further compared using parametric statistics. In agreement with our previous investigations, the results indicate that RA, U_Na,fe, U_K,fe, systolic, and diastolic BP oscillate with a circadian periodicity in dogs fed a regular diet at 07:00?h. A cosine model with a fixed 24-h period was found to fit the variations of RA, U_K,fe and BP well, whereas cyclic changes in U_Na,fe were best characterized by means of a combined cosine and surge model, reflecting a postprandial sodium excretion followed by a monotonous decay. Our data show that feeding time has a marked influence on the chronobiology of the renin cascade, urinary electrolytes, and BP. Introducing a 6- or 12-h delay in the dogs’ feeding schedule caused a shift of similar magnitude (05:06 and 12:32?h for Studies a and b, respectively) in the rhythm of these biomarkers. In all study groups, RA and BP exhibited a marked fall just after food intake. The drop in RA is consistent with sodium and water-induced body fluid expansion, while the reduction of BP could be related to the decreased activity of renin and the secretion of vasodilatory gut peptides. An approximately 1.5-fold (1.2–1.6-fold) change between the average early and late time after feeding observations was found for RA (p?<?0.0001), U_Na,fe (p?<?0.01) and U_K,fe (p?<?0.05). Postprandial variations in BP, albeit small (ca. 10?mmHg), were statistically significant (p?<?0.01) and supported by the model-based analysis.

In conclusion, the timing of food intake appears to be pivotal to the circadian organization of the renin cascade and BP. This synchronizing effect could be mediated by feeding-related signals, such as dietary sodium, capable of entraining circadian oscillators downstream of the master, light–dark-adjusted pacemaker in the suprachiasmatic nucleus.     

Scale sensitivity of synthetic long‐term vegetation time series derived through overlay of short‐term field records

Questions: Is change in cover of dominant species driving the velocity of succession or is it species turnover (1)? Is the length of the time‐step chosen in sampling affecting our recognition of the long‐term rate of change (2)1 Location: 74 permanent plots located in the Swiss National Park, SE Switzerland, ca. 1900 m a.s.l. Methods: We superimpose several time‐series from permanent plots to one single series solely based on compositional dissimilarity. As shown earlier (Wildi & Schütz 2000) this results in a synthetic series covering about 400 to 650 yr length. Continuous power transformation of cover‐percentage scores is used to test if the dominance or the presence‐absence of species is governing secondary succession from pasture to forest. The effect of time step length is tested by sub‐samples of the time series. Results: Altering the weight of presence‐absence versus dominance of species affects the emerging time frame, while altering time step length is uncritical. Where species turnover is fast, different performance scales yield similar results. When cover change in dominant species prevails, the solutions vary considerably. Ordinations reveal that the synthetic time series seek for shortest paths of the temporal pattern whereas in the real system longer lasting alternatives exist. Conclusions: Superimposing time series differs from the classical space‐for‐time substitution approach. It is a computation‐based method to investigate temporal patterns of hundreds of years fitting between direct monitoring (usually limited to decades) and the analysis of proxy‐data (for time spans of thousands of years and more).     

Second-harmonic generation from organic molecules incorporated in sol-gel matrices

Orientation of optically nonlinear organic molecules inside sol-gel matrices upon application of an external D.C. electrical field is demonstrated for the first time. The quadratic nonlinear response of silicon oxide or transition metal oxide based gels containing organic molecules has been determined from Electric Field Induced Second Harmonic (EFISH) measurements. Large concentrations of Optically Nonlinear Organic Molecules (ONOM) have been either incorporated inside the macromolecular network or chemically bonded to the oxide backbone of the gels. These results demonstrate the feasibility of permanently poled doped sol-gel matrices. Moreover, EFISH measurements performed on organic molecules appear to be a useful tool for monitoring the changes occurring during sol-gel transformations.     

Advances in alternative DNA delivery techniques

This review describes recent advances in alternative DNA-delivery techniques with particular emphasis on silicon carbide fibers, intact tissue electroporation, electrophoresis and microinjection. The advantages/disadvantages of each method along with a historical overview and theory of practice are discussed.     

Autogenous growth factor production by reticuloendotheliosis virus-transformed hematopoietic cells

Reticuloendotheliosis virus strain T (REV-T)-transformed cells gave rise spontaneously to variants which secrete a factor that forms a distinct visible ring of precipitation (halo) surrounding colonies grown in soft agar. An Mr 15,000 protein was produced at higher levels by halo variants than by nonhalo-producing cells. An assay designed to detect the formation of precipitates enabled purification of an Mr 15,000 protein, p15, from serum-free medium conditioned by the growth of REV-T-transformed hematopoietic cells. Fractions enriched in p15 permitted the growth of REV-T-transformed cells under conditions where they normally failed to proliferate.