Serendipitous discovery and X-ray structure of a human phosphate binding apolipoprotein

We report the serendipitous discovery of a human plasma phosphate binding protein (HPBP). This 38 kDa protein is copurified with the enzyme paraoxonase. Its X-ray structure is similar to the prokaryotic phosphate solute binding proteins (SBPs) associated with ATP binding cassette transmembrane transporters, though phosphate-SBPs have never been characterized or predicted from nucleic acid databases in eukaryotes. However, HPBP belongs to the family of ubiquitous eukaryotic proteins named DING, meaning that phosphate-SBPs are also widespread in eukaryotes. The systematic absence of complete genes for eukaryotic phosphate-SBP from databases is intriguing, but the astonishing 90% sequence conservation between genes belonging to evolutionary distant species suggests that the corresponding proteins play an important function. HPBP is the only known transporter capable of binding phosphate ions in human plasma and may become a new predictor of or a potential therapeutic agent for phosphate-related diseases such as atherosclerosis.     

Floral morphogenesis in Anagallis: Scanning-electron-micrograph sequences from individual growing meristems before,during, and after the transition to flowering

Non-destructive scanning electron microscopy allows one to visualize changing patterns of individual cells during epidermal development in single meristems. Cell growth and division can be followed in parallel with morphogenesis. The method is applied here to the shoot apex of Anagallis arvensis L. before, during, and after floral transition. Phyllotaxis is decussate; photoperiodic induction of the plant leads to the production of a flower in the axil of each leaf. As seen from above, the recently formed oval vegetative dome is bounded on its slightly longer sides by creases of adjacent leaf bases. The rounded ends of the dome are bounded by connecting tissue, horizontal bands of node cells between the opposed leaf bases. The major growth axis runs parallel to the leaf bases. While slow-growing at the dome center, this axis extends at its periphery to form a new leaf above each band of connecting tissue. Connecting tissue then forms between the new leaves and a new dome is defined at 90° to the former. The growth axis then changes by 90°. This is the vegetative cycle. The first observed departure from vegetative growth is that the connecting tissue becomes longer relative to the leaf creases. Presumably because of this, the major growth axis does not change in the usual way. Extension on the dome continues between the older leaves until the axis typically buckles a second time, on each side, to form a second crease parallel to the new leaf-base crease. The tissue between these two creases becomes the flower primordium. The second crease also delimits the side of a new apical dome with the major axis and growth direction altered by 90°. During this inflorescence cycle the connecting tissue is relatively longer than before. Much activity is common to both cycles. It is concluded that the complex geometrical features of the inflorescence cycle may result from a change in a biophysical boundary condition involving dome geometry, rather than a comprehensive revision of apical morphogenesis.Abbreviation SEM scanning electron microscopy, micrograph Use of the SEM facility of Professor G. Goffinet, Institute of Zoology, University of Liège, is greatly appreciated. We thank Dr. R. Jacques, C.N.R.S., Le Phytotron, Gif-sur-Yvette, France, for providing the experimental material, and Mr. Philippe Ongena for expert photography. Support was from grants from the U.S. Department of Agriculture and National Science Foundation as well as from the Fonds National de la Recherche Scientifique, Fonds de la Recherche Fondamentale et Collective, and the Action de Recherche Concertée of Belgium.     

Resumption of cellular activity induced by cytokinin and gibberellin treatments in tomato flowers targeted for abortion in unfavorable light conditions

Mitotic activity and nuclear DNA synthesis in tomato ( Lycopersicon esculentum Mill., cv. King plus) flowers targeted for abortion under unfavorable light conditions are completely stopped 6 days after macroscopic appearance of the inflorescence. Ovular cells are arrested at the G₁ (80%) and G₂ (20%) stages of the cell cycle. Exogenous applications of a mixture of N⁶-benzyladenine (BA) and gibberellins A₄₊₇ (GA) directly on the inflorescence may prevent its failure. Nuclear DNA synthesis and mitoses resume in ovules of the flower 16 to 20 h after the BA+GA treatment. When applied alone, BA and GA are able to mimic the effect of the mixture upon the progression of ovular cells through their cycle. Sporogenesis processes are also set in motion by the exogenous plant growth regulators. The mechanism of action of cytokinins and gibberellins in the control of floral development is discussed.     

Protective efficacy of a whole cell pertussis vaccine

A trial of the efficacy of a plain whole cell pertussis vaccine was conducted in Sweden. In this non-blinded trial 525 infants aged 2 months who were born on days with an even number received three doses of vaccine one month apart and 615 infants of the same age who were born on days with an odd number were enrolled as controls. During the 18 months of follow up there were 55 cases of pertussis. The attack rate was 1·5% (8/525) among the vaccinated children and 7·6% (47/615) among the unvaccinated children (p<0·001). The estimated efficacy of the vaccine was 80% (95% confidence interval 58 to 90).The estimated efficacy of pertussis vaccine was similar to that observed in British trials over 30 years ago.     

Growth changes in the shoot apex of Sinapis alba during transition to flowering

The aim of the work was to report morphological changes whichoccur in the shoot apex during the morphogenetic switch to floweringin the model long day (LD) plant, Sinapis alba. During the floraltransition induced by 1 LD the growth rate of all componentsof the shoot apex is modified profoundly. The earliest changes,detected at 24 h after start of LD, include a decrease in plastochronduration and an increase of growth of leaf primordia. One daylater, the meristem dome starts to increase in volume, apicalinternodes have an increased height and there is a precociousoutgrowth of axillary meristems. All these changes precede initiationof flower primordia, which starts at about 60 h after the startof LD. Later changes include meristem doming, a decrease inthe plastochron ratio and a shift to a more complex phyllotaxis.All the changes, except the decreased plastochron ratio, arecharacteristics of an apex with an increased tempo of growth.The stimulation of longitudinal growth (height of apical intemodes)is more marked and occurs earlier than the reduction of radialgrowth (plastochron ratio). Key words: Axillary meristem, internode growth, leaf growth, plastochron ratio, plastochron duration     

EEG Mu Rhythm in Typical and Atypical Development

Electroencephalography (EEG) is an effective, efficient, and noninvasive method of assessing and recording brain activity. Given the excellent temporal resolution, EEG can be used to examine the neural response related to specific behaviors, states, or external stimuli. An example of this utility is the assessment of the mirror neuron system (MNS) in humans through the examination of the EEG mu rhythm. The EEG mu rhythm, oscillatory activity in the 8-12 Hz frequency range recorded from centrally located electrodes, is suppressed when an individual executes, or simply observes, goal directed actions. As such, it has been proposed to reflect activity of the MNS. It has been theorized that dysfunction in the mirror neuron system (MNS) plays a contributing role in the social deficits of autism spectrum disorder (ASD). The MNS can then be noninvasively examined in clinical populations by using EEG mu rhythm attenuation as an index for its activity. The described protocol provides an avenue to examine social cognitive functions theoretically linked to the MNS in individuals with typical and atypical development, such as ASD.