ONTOGENY AND STRUCTURE OF CONIFEROUS SIEVE CELLS

Studies of the secondary phloem of 6 species of conifers revealed that mature sieve-cell protoplasts contain internal strands which are derived ontogenetically from slime bodies of immature cells. These strands, each measuring about 0.3 μ in diameter, traverse the cell and run from cell to cell through sieve-area pores. Coniferous sieve cells have much in common—both ontogenetically and structurally—with dicotyledonous sieve-tube members.     

Biological control of Pythium aphanidermatum in cucumber with a combined application of Lysobacter enzymogenes strain 3.1T8 and chitosan

Pythium aphanidermatum (Edson) Fitzp., causing root and crown rot in cucumber, was successfully managed by Lysobacter enzymogenes strain 3.1T8. Greenhouse experiments were performed with cucumber plants grown in rockwool blocks up to 5 weeks with a recirculated nutrient solution. Application of L. enzymogenes 3.1T8 in combination with chitosan (the deacetylated derivative of chitin) reduced the number of diseased plants by 50–100% in four independent experiments relative to the Pythium control. Application of chitosan or the bacterial inoculant alone was not effective. Washed bacterial cells plus chitosan inhibited Pythium-induced disease, but the supernatant without bacterial cells combined with chitosan was not effective. The most effective and convenient type of commercially available chitosan was selected. Chitosan disappeared from the hydroponic system within 24 h after application, which we attribute to enzyme expression of L. enzymogenes 3.1T8 induced by the exposure to chitosan. Plate counts of the nutrient solution on a general bacterial medium showed the dominance of the inoculated strain, and an increased bacterial population growing on chitin and chitosan as single carbon source. The population density of L. enzymogenes 3.1T8 on the cucumber roots was investigated with a strain specific real-time TaqMan PCR. Highest chitosan concentrations applied (0.1 and 0.03 g/plant) resulted in the highest numbers of L. enzymogenes 3.1T8 present on roots; i.e. 10⁸–10⁹ cells/g root. Substantially higher numbers of bacterial cells were observed by scanning electron microscopy after application of chitosan; no morphological or other qualitative differences were found. The results indicate that addition of chitosan enhanced the biocontrol efficacy of L. enzymogenes 3.1T8; either chitosan serves as C- and N-source for the antagonist, induces antagonistic gene expression, or both.     

White adipose tissue reference network: a knowledge resource for exploring health-relevant relations

Optimal health is maintained by interaction of multiple intrinsic and environmental factors at different levels of complexity—from molecular, to physiological, to social. Understanding and quantification of these interactions will aid design of successful health interventions. We introduce the reference network concept as a platform for multi-level exploration of biological relations relevant for metabolic health, by integration and mining of biological interactions derived from public resources and context-specific experimental data. A White Adipose Tissue Health Reference Network (WATRefNet) was constructed as a resource for discovery and prioritization of mechanism-based biomarkers for white adipose tissue (WAT) health status and the effect of food and drug compounds on WAT health status. The WATRefNet (6,797 nodes and 32,171 edges) is based on (1) experimental data obtained from 10 studies addressing different adiposity states, (2) seven public knowledge bases of molecular interactions, (3) expert’s definitions of five physiologically relevant processes key to WAT health, namely WAT expandability, Oxidative capacity, Metabolic state, Oxidative stress and Tissue inflammation, and (4) a collection of relevant biomarkers of these processes identified by BIOCLAIMS (http://bioclaims.uib.es). The WATRefNet comprehends multiple layers of biological complexity as it contains various types of nodes and edges that represent different biological levels and interactions. We have validated the reference network by showing overrepresentation with anti-obesity drug targets, pathology-associated genes and differentially expressed genes from an external disease model dataset. The resulting network has been used to extract subnetworks specific to the above-mentioned expert-defined physiological processes. Each of these process-specific signatures represents a mechanistically supported composite biomarker for assessing and quantifying the effect of interventions on a physiological aspect that determines WAT health status. Following this principle, five anti-diabetic drug interventions and one diet intervention were scored for the match of their expression signature to the five biomarker signatures derived from the WATRefNet. This confirmed previous observations of successful intervention by dietary lifestyle and revealed WAT-specific effects of drug interventions. The WATRefNet represents a sustainable knowledge resource for extraction of relevant relationships such as mechanisms of action, nutrient intervention targets and biomarkers and for assessment of health effects for support of health claims made on food products.

Electronic supplementary material

The online version of this article (doi:10.1007/s12263-014-0439-x) contains supplementary material, which is available to authorized users.     

Bcl-2 family member Bfl-1/A1 sequesters truncated bid to inhibit is collaboration with pro-apoptotic Bak or Bax

Following caspase-8 mediated cleavage, a carboxyl-terminal fragment of the BH3 domain-only Bcl-2 family member Bid transmits the apoptotic signal from death receptors to mitochondria. In a screen for possible regulators of Bid, we defined Bfl-1/A1 as a potent Bid interacting protein. Bfl-1 is an anti-apoptotic Bcl-2 family member, whose preferential expression in hematopoietic cells and endothelium is controlled by inflammatory stimuli. Its mechanism of action is unknown. We find that Bfl-1 associates with both full-length Bid and truncated (t)Bid, via the Bid BH3 domain. Cellular expression of Bfl-1 confers protection against CD95- and Trail receptor-induced cytochrome c release. In vitro assays, using purified mitochondria and recombinant proteins, demonstrate that Bfl-1 binds full-length Bid, but does not interfere with its processing by caspase-8, or with its mitochondrial association. Confocal microscopy supports that Bfl-1, which at least in part constitutively localizes to mitochondria, does not impede tBid translocation. However, Bfl-1 remains tightly and selectively bound to tBid and blocks collaboration between tBid and Bax or Bak in the plane of the mitochondrial membrane, thereby preventing mitochondrial apoptotic activation. Lack of demonstrable interaction between Bfl-1 and Bak or Bax in the mitochondrial membrane suggests that Bfl-1 generally prevents the formation of a pro-apoptotic complex by sequestering BH3 domain-only proteins.     

Vector integration in triple R gene transformants and the clustered inheritance of resistance against potato late blight

Genetic transformation with resistance (R) genes is expected to enhance resistance durability against pathogens, especially for potato, a vegetatively propagated crop with tetrasomic inheritance and a long-term breeding program. In this study, 128 potato transformants were analysed for the presence of vector T-DNA genes, borders and backbone sequences. They were harvested after transformation using a construct containing neomycin phosphotransferase II (nptII) and three R genes against potato late blight (Phytophthora infestans). Our analysis revealed that 45 % of the R gene-containing transformants possessed a low T-DNA copy number, without the integration of vector backbone and borders. The integration of vector backbone sequences was characterized using eight genes, and backbone gene tetA was selected for the early prediction of plants with backbone sequence integration. Three transformants, two plants harbouring one T-DNA copy and one plant harbouring three T-DNA copies, were crossed with susceptible cv. Katahdin. Based on our results, we conclude that all four T-DNA genes were inherited as one cluster and segregated in a Mendelian fashion. The three T-DNA inserts from the transformant harbouring three T-DNA copies were statistically proven to be un-linked and inherited into the offspring plants independently. All of the R genes were functionally expressed in the offspring plants as in their parental transformants. This functional gene stacking has important implications towards achieving more durable resistance against potato late blight.     

Adverse events among medical patients after discharge from hospital

BackgroundAdverse events (AEs) are adverse outcomes caused by medical care. Several studies have indicated that a substantial number of patients experience AEs before or during hospitalization. However, few data describe AEs after hospital discharge. We determined the incidence, severity, preventability and ameliorability of AEs in patients discharged from the general internal medicine service of a Canadian hospital.MethodsAt a multisite Canadian teaching hospital, we prospectively studied patients who were consecutively discharged home or to a seniors'' residence from the general internal medicine service during a 14-week interval in 2002. We used telephone interview and chart review to identify outcomes after discharge. Two physicians independently reviewed each outcome to determine if the patient experienced an AE. The severity, preventability and ameliorability of all AEs were classified.ResultsDuring the study period, outcomes were determined for 328 of the 361 eligible patients, who averaged 71 years of age (interquartile range 54–81 years). After discharge, 76 of the 328 patients experienced at least 1 AE (overall incidence 23%, 95% confidence interval [CI] 19%–28%). The AE severity ranged from symptoms only (68% of the AEs) or symptoms associated with a nonpermanent disability (25%) to permanent disability (3%) or death (3%). The most common AEs were adverse drug events (72%), therapeutic errors (16%) and nosocomial infections (11%). Of the 76 patients, 38 had an AE that was either preventable or ameliorable (overall incidence 12%, 95% CI 9%–16%).InterpretationApproximately one-quarter of patients in our study had an AE after hospital discharge, and half of the AEs were preventable or ameliorable.The Institute of Medicine report Crossing the quality chasm identifies patient safety as a prerequisite to high-quality care.¹ The need to improve safety is highlighted by research showing that hospitalized patients have a high risk of adverse outcomes resulting from treatment. For example, the Harvard Medical Practice Study found that adverse events (AEs) occurred in 3.7% of hospitalized patients.^2,3 Similar studies have found equivalent or greater rates.^4,5,6 Other research has found that AE risk increases with design flaws in the health care system.^7,8,9,10Such flaws may particularly affect patient care immediately after hospital discharge, a period associated with discontinuities in providers and in location of care. Some authors suggest that such “gaps” are important causes of error.¹¹ It is also a time when patients frequently experience extensive changes in health¹² and therapy.¹³ Finally, communication between hospital and community physicians can be inadequate.¹⁴ For these reasons, AEs may be common after discharge. A recent study, by a group that included 1 of us, found that 19% of medical patients discharged from a single teaching hospital in the United States experienced an AE within a month.¹⁵ One-third of these AEs were preventable because they were due to an error. Another third were judged “ameliorable” because their severity could have been reduced with better monitoring or earlier response to the problem.¹⁵That study was important, but it had limitations. It was carried out in a single, very specialized institution, it relied on data available in an electronic medical record, and it had a high rate of loss to follow-up. To address these concerns, we carried out a new study to determine the risk, severity and type of AEs after discharge from 2 campuses of a Canadian teaching hospital.     

Acid survival of Helicobacter pylori: how does urease activity trigger cytoplasmic pH homeostasis?

Helicobacter pylori can survive for several hours at pH 1 in the presence of urea. Under these conditions, the organism maintains its cytoplasmic pH at a value close to neutral. The role of the cytoplasmically located urease enzyme in this process is a matter of debate. We propose that cytoplasmic ammonia generated by the action of urease is protonated by H(+) ions leaking in from the acidic medium and that the NH(4)(+) formed is extruded from the cytoplasm via an as-yet-unidentified transport system. This mechanism is compared with the general mechanism of cytoplasmic pH homeostasis in microorganisms.     

The East Flanders Prospective Twin Survey (EFPTS).

The East Flanders Prospective Twin Survey (EFPTS) is a registry of multiple births in the province of East-Flanders, Belgium. It has several unique features: it is population-based and prospective, with the possibility of long-term follow-up; the twins (and higher order multiple births) are ascertained at birth; basic perinatal data are recorded; chorion type and zygosity are established; and since 1969 placental biopsies have been taken and frozen at -20 degrees C for later determination of genetic markers. The EFPTS is the only large register that includes placental data and allows differentiation of three subtypes of monozygotic (MZ) twins based on the time of the initial zygotic division: the dichorionic-diamnionic pairs (early, before the fourth day after fertilisation), the monochorionic-diamnionic pairs (intermediate, between the fourth and the seventh day post fertilisation), and the monochorionic-monoamnionic pairs (late, after the eight day post fertilisation). This added a new dimension to didymology (the science of twins; delta iota delta upsilon mu omicron zeta = twins): the timing of twinning. Studies can be initiated on primary biases, those originating "in utero". Such studies may throw new light on the controversy over the validity of the classic twin method, the consequences of early embryological events (before and just after implantation of the embryo), the origin of congenital malformations, the sex proportion of multiples, the gene-environment interactions as far as intrauterine environment is concerned, to name but a few.