Electric field-induced lateral mobility of photosystem I in the photosynthetic membrane: A study by electrophotoluminescence

Electrophoretic movement of photosystem I (PS I) along the photosynthetic membrane of hypotonically swollen thylakoid vesicles was studied by analyzing the electric field-stimulated delayed luminescence (electrophotoluminescence) emitted from PS I. The electrophoretic mobility was inferred from the differences in electrophotoluminescence (EPL) of the photosynthetic vesicles in presence and absence of trains of low amplitude (<80 V/cm) prepulses of 1 ms duration at 4 ms spacing. The average apparent electric mobility, determined from the time course of EPL increase on one hemisphere or its decrease on the other one, as function of prepulse length and intensity was of the order of 3 · 10^-5 cm²V^-1s^-1. The assymetric distribution of the PS I reached a steady state when the diffusional, electrostatic, and elastic forces balanced the electrophoretic driving force. A lateral diffusion coefficient of ~5 · 10^-9 cm²s^-1 was found for the PS I complex from the diffusional relaxation after cessation of the electric field pulse train. Experimental conditions such as concentration, temperature, and viscosity of the aqueous solution were not critical for the effect. Between 23 and 150 electron charges per moving particle were estimated from the measured electrophoretic mobility.     

Characteristics of children presenting with chest pain to a pediatric emergency department.

Chest pain among children is a common complaint in primary care practice. However, the demographic features and treatment of such patients are controversial. We distributed a questionnaire to 336 consecutive patients with a complaint of chest pain seen during 1 year at an urban pediatric emergency department. Such visits represented 0.6% of all emergency encounters; the male:female ratio was 1.0. Physical examination was done in 325 patients. Chest-wall pain was the most common diagnosis (in 28% of cases). Other causes included pulmonary (in 19%), minor traumatic (in 15%), idiopathic (in 12%) and psychogenic (in 5%); miscellaneous causes (in 21%) most often indicated pain referred from the upper respiratory tract and the abdomen. The most common physical finding was chest tenderness (in 41% of cases). Investigations included chest radiography (in 50% of cases), electrocardiography (in 18%) and determination of the hemoglobin concentration and of the leukocyte count (in 13%); the results were rarely positive. Only eight patients (2%) required admission to hospital, and there were no cases of myocardial ischemia. The findings suggest that health care costs may be reduced by more judicious use of investigations. We conclude that chest pain is an uncommon and usually benign complaint in the pediatric emergency department. Most causes are evident on careful physical examination.     

Distal deletion of the long arm of chromosome number 1 (q43-->qter) associated with severe mental retardation and a nonspecific dysmorphic syndrome.

A 6 8/12-year-old girl with severe mental retardation, multiple congenital malformations and a de novo distal deletion of the long arm of chromosome 1 [del 1 (q43-->qter)] is here described. A review of the reported patients does not allow to distinguish different phenotypes related to distal deletion 1q42 and/or 1q43.     

Effect of copper sulfate on experimental atherosclerosis

Serum copper concentration increases significantly (p<0.01) in rats with experimental atherosclerosis compared to a control group. The serum zinc, the zinc, and copper concentration in abdominal aorta and in liver decreases significantly (p<0.05) compared to the control group. Administration of copper sulfate for 100 d in these animals induces a significant increase of serum copper (p<0.01), decrease of serum cholesterol (p<0.05) and increase of liver copper concentration as compared with the group fed only a high cholesterol diet. In the aorta of these animals the copper concentration increases and edema and lipid infiltration are considerably less than in the group of animals fed only a high lipid diet.     

Isolation of early genes expressed in reproductive organs of the dioecious white campion (Silene latifolia) by subtraction cloning using an asexual mutant

The dioecious white campion (Silene latifolia) has been chosen as a working model for sexual development. In this species, sexual dimorphism is achieved through two distinct developmental blocks: inhibition of carpel development in male flowers, and early arrest of anther differentiation in female flowers. The combined advantages of the dioecious system and the availability of a sexual mutant lacking both male and female reproductive organs have been exploited in a molecular subtraction approach using male and asexual flower buds. This resulted in the cloning of 22 cDNA clones expressed in stamens at distinct stages of development. Fourteen of these clones corresponded to genes whose expression was detected in pre-meiotic stamens, a stage of development for which very little information is presently available. Furthermore, the absence of similarities with database sequences for ten clones suggests that they represent novel genes. Functional analysis of each clone will enable their positioning within the reproductive organ developmental pathway(s). In parallel, these clones are being exploited as developmental markers of early differentiation within the flower.     

Progress in cellular engineering of plants: biochemical and genetic assessment of selectable markers from cultured cells

Summary Recent availability of stable and well characterized selectable markers and ability to combine alien genomes parasexually have contributed to the development of molecular biology in higher plants, including gene expression and genetic manipulation.Several types of biochemical mutants (resistant to inhibitory concentrations of aminoacid(s) or aminoacid analogs as well as deficient for enzyme activity) have recently been isolated and characterized biochemically and genetically. Among them, mutants with alterations in the nitrogen and aminoacid metabolism, or in the activity of alcohol dehydrogenases are being used in the development of more efficient techniques of gene transfer.The manipulation of whole genomes by sexual or somatic cell fusion offers new potential in this field, but refinement of transfer techniques is desirable. The new set of selectable markers obtained through advanced cellular technology, as well as our ability to regenerate plants from manipulated cell lines are expected to play a major role in cellular engineering.     

Interstitial deletion (2)(p13p15)

Summary A dysmorphic 5-year-old girl with severe growth and mental deficiency was studied. She presented a de novo interstitial 2p deletion. Karyotype: 46,XX,del(2)(p13p15).     

Role of Interaction and Nucleoside Diphosphate Kinase B in Regulation of the Cystic Fibrosis Transmembrane Conductance Regulator Function by cAMP-Dependent Protein Kinase A

Cystic fibrosis results from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-dependent protein kinase A (PKA) and ATP-regulated chloride channel. Here, we demonstrate that nucleoside diphosphate kinase B (NDPK-B, NM23-H2) forms a functional complex with CFTR. In airway epithelia forskolin/IBMX significantly increases NDPK-B co-localisation with CFTR whereas PKA inhibitors attenuate complex formation. Furthermore, an NDPK-B derived peptide (but not its NDPK-A equivalent) disrupts the NDPK-B/CFTR complex in vitro (19-mers comprising amino acids 36–54 from NDPK-B or NDPK-A). Overlay (Far-Western) and Surface Plasmon Resonance (SPR) analysis both demonstrate that NDPK-B binds CFTR within its first nucleotide binding domain (NBD1, CFTR amino acids 351–727). Analysis of chloride currents reflective of CFTR or outwardly rectifying chloride channels (ORCC, DIDS-sensitive) showed that the 19-mer NDPK-B peptide (but not its NDPK-A equivalent) reduced both chloride conductances. Additionally, the NDPK-B (but not NDPK-A) peptide also attenuated acetylcholine-induced intestinal short circuit currents. In silico analysis of the NBD1/NDPK-B complex reveals an extended interaction surface between the two proteins. This binding zone is also target of the 19-mer NDPK-B peptide, thus confirming its capability to disrupt NDPK-B/CFTR complex. We propose that NDPK-B forms part of the complex that controls chloride currents in epithelia.     

Madelung deformity as a pathognomonic feature of the onycho-osteodysplasia syndrome.

On the occasion of the observation of the Onycho-osteo-dysplasia syndrome (HOOD syndrome--Nail-Patella syndrome) in a 4-generation family we were impressed by the presence of a Madelung deformity in the four examined family members. A critical review of the literature showed that a true Madelung deformity was present in a great number of previously reported patients but that no specific attention was given to this apparently important symptom.