Complex regulation of the TIR1/AFB family of auxin receptors.

Auxin regulates most aspects of plant growth and development. The hormone is perceived by the TIR1/AFB family of F-box proteins acting in concert with the Aux/IAA transcriptional repressors. Arabidopsis plants that lack members of the TIR1/AFB family are auxin resistant and display a variety of growth defects. However, little is known about the functional differences between individual members of the family. Phylogenetic studies reveal that the TIR1/AFB proteins are conserved across land plant lineages and fall into four clades. Three of these subgroups emerged before separation of angiosperms and gymnosperms whereas the last emerged before the monocot-eudicot split. This evolutionary history suggests that the members of each clade have distinct functions. To explore this possibility in Arabidopsis, we have analyzed a range of mutant genotypes, generated promoter swap transgenic lines, and performed in vitro binding assays between individual TIR1/AFB and Aux/IAA proteins. Our results indicate that the TIR1/AFB proteins have distinct biochemical activities and that TIR1 and AFB2 are the dominant auxin receptors in the seedling root. Further, we demonstrate that TIR1, AFB2, and AFB3, but not AFB1 exhibit significant posttranscriptional regulation. The microRNA miR393 is expressed in a pattern complementary to that of the auxin receptors and appears to regulate TIR1/AFB expression. However our data suggest that this regulation is complex. Our results suggest that differences between members of the auxin receptor family may contribute to the complexity of auxin response.

Strong association between west african rainfall and u.s. Landfall of intense hurricanes.

Intense hurricanes occurred much more frequently during the period spanning the late 1940s through the late 1960s than during the 1970s and 1980s, except for 1988 and 1989. Seasonal and multidecadal variations of intense hurricane activity are closely linked to seasonal and multidecadal variations of summer rainfall amounts in the Western Sahel region of West Africa. The multidecadal nature of West African precipitation variations and their association with variations of intense Atlantic hurricane activity can be observed in data going back nearly a century. The apparent recent breaking of the 18-year Sahel drought during 1988 and 1989 suggests that the incidence of intense hurricanes making landfall on the U.S. coast and in the Caribbean basin will likely increase during the 1990s and early years of the 21st century to levels of activity notably greater than were observed during the 1970s and 1980s.

The recent increase in Atlantic hurricane activity: causes and implications.

The years 1995 to 2000 experienced the highest level of North Atlantic hurricane activity in the reliable record. Compared with the generally low activity of the previous 24 years (1971 to 1994), the past 6 years have seen a doubling of overall activity for the whole basin, a 2.5-fold increase in major hurricanes (>/=50 meters per second), and a fivefold increase in hurricanes affecting the Caribbean. The greater activity results from simultaneous increases in North Atlantic sea-surface temperatures and decreases in vertical wind shear. Because these changes exhibit a multidecadal time scale, the present high level of hurricane activity is likely to persist for an additional approximately 10 to 40 years. The shift in climate calls for a reevaluation of preparedness and mitigation strategies.

Interactions of the COP9 signalosome with the E3 ubiquitin ligase SCFTIRI in mediating auxin response.

The COP9 signalosome is an evolutionary conserved multiprotein complex of unknown function that acts as a negative regulator of photomorphogenic seedling development in Arabidopsis. Here, we show that plants with reduced COP9 signalosome levels had decreased auxin response similar to loss-of-function mutants of the E3 ubiquitin ligase SCFTIR1. Furthermore, we found that the COP9 signalosome and SCFTIR1 interacted in vivo and that the COP9 signalosome was required for efficient degradation of PSIAA6, a candidate substrate of SCFTIR1. Thus, the COP9 signalosome may play an important role in mediating E3 ubiquitin ligase-mediated responses.

Function of the ubiquitin-proteasome pathway in auxin response.

The plant hormone auxin regulates many aspects of growth and development. Despite the importance of this hormone, the molecular basis for auxin action has remained elusive. Recent advances using molecular genetics in Arabidopsis have begun to elucidate the mechanisms involved in auxin signaling. These results suggest that protein degradation by the ubiquitin pathway has a central role in auxin response.

Isolation and analysis of the yeast TEA1 gene, which encodes a zinc cluster Ty enhancer-binding protein.

A genetic screen for mutants that affect the activity of internal regulatory sequences of Ty retrotransposons led to the identification of a new gene encoding a DNA-binding protein that interacts with the downstream enhancer-like region of Ty1 elements. The TEA1 (Ty enhancer activator) gene sequence predicts a protein of 86.9 kDa whose N terminus contains a zinc cluster and dimerization motif typical of the Gal4-type family of DNA-binding proteins. The C terminus encodes an acidic domain with a net negative charge of -10 and the ability to mediate transcriptional activation. Like other zinc cluster proteins, purified Tea1 was found to bind to a partially palindromic CGGNxCCG repeat motif located in the Ty1 enhancer region. The Ty1 Tea1 binding site has a spacing of 10 and is located near binding sites for the DNA-binding proteins Rap1 and Mcm1. Analysis of the phenotype of tea1 deletion mutants confirmed that the TEA1 gene is required for activation from the internal Ty1 enhancer characterized in this study and makes a modest contribution to normal Ty1 levels in the cell. Hence, Tea1, like Rap1, is a member of a small family of downstream activators in Saccharomyces cerevisiae. Further analysis of the Tea1 protein and its interactions may provide insight into the mechanism of downstream activation in yeast cells.

Role of Saccharomyces cerevisiae Rap1 protein in Ty1 and Ty1-mediated transcription.

Binding sites for the transcription factor Rap1 are widespread in the yeast genome. With respect to many, but not all, genes, Rap1p has an apparent activation function. Whether Rap1 is itself a transcriptional activator, or whether it is in some way required for activation by additional factors, is not clear. We have identified a previously unrecognized Rap1p binding site in the internal regulatory region of Ty1 elements. We demonstrate that this site is capable of binding Rap1 in vitro and that, in vivo, Rap1p plays an important regulatory role in Ty1 and Ty1-mediated adjacent gene expression. Our data suggest that in Ty1 elements, maximal levels of RAP1-mediated activation depend on the formation of a complex with Mcm1, an independent DNA-binding protein that functions in transcription as well as in DNA replication, and with a third factor, IBF, previously identified as a binding activity with a site situated between the Rap1p and Mcm1p binding sites in this region of Ty1 elements.

Assessment of the design and performance of the Sage syringe pump model 341A, with particular reference to its accuracy and stability.

Consideration of the timing circuitry employed in the Sage pump model 341A indicates that the pump's performance will be strongly affected by component tolerances, and our measurements have confirmed this impression. Thus, delivered flow rates may deviate considerably from those indicated on the calibration chart; our instrument was about 10% slow at all settings. For many applications it will be necessary to carry out a full calibration procedure, which should be repeated following any repairs to the electronic circuitry. The pump also suffered from drift at certain settings because an inappropriate component had been used in the timing circuitry. These findings will also apply to the Sage pump models 240A and 242A, which employ similar timing circuitry to the 341A. When precautions are taken to overcome these problems, the pump's performance is satisfactory for both clinical use and some laboratory applications.

A vaporizer controller.

A Cyprane Enfluratec 3 vaporizer has been modified so that it can be operated under computer control. Details are given of construction and of safety precautions employed.

Oxford Optronix MPM 3S: a clinical assessment of a microvascular perfusion monitor.

The Oxford Optronix MPM 3S is a new microvascular perfusion monitor which is promoted as a device for use in the operating theatre. It uses a semiconductor laser diode and applies the Doppler principle to derive a semi-quantitative estimation of microvascular flow. We assessed this instrument with eight healthy volunteers who each performed eight different orthostatic arm manoeuvres while forearm skin blood flow was monitored. The different manoeuvres caused statistically significant changes in the instrument's reading which generally were consistent with expected changes in blood flow. The monitor also was assessed in the theatre environment with four anaesthetized patients. It proved easy to use, and was not subject to electrical interference from other equipment including short-wave diathermy. The major practical limitation of the technique is the semi-quantitative nature of the measurement. The instrument appears to have potential clinical uses in plastic and vascular surgery.

Formal operations, the imaginary audience and the personal fable.

One hundred twenty-nine 6th, 8th, 10th/11th, and 12th graders were administered Enright, Lapsley, and Shukla's Adolescent Egocentrism Scale (AES) and How Is Your Logic?, a Piagetian-based, group-administered, written test of cognitive development. A series of ANOVAs on four scales of the AES (imaginary audience, personal fable, self-in-general, nonsocial) provided partial support for Inhelder and Piaget's, and Elkind's views that adolescent egocentrism is a function of beginning formal operations. Discussion focused on the difficulty of assessing the true thoughts/feelings of persons who are worried how they will appear to others.

A critical appraisal of a rapid radiographic method of determining total lung capacity.

We have demonstrated that the total lung capacities of normal caucasian adults, can be satisfactorily estimated by means of a regression equation derived from a single set of three measurements taken from a specially exposed plain X-ray film of the chest. However, these equations differ from those found by workers who have studied patients with lung disease. It is concluded from this that different regression equations are to be expected for normal and diseased lungs, and that, the appropriate equation will depend not only on the presence of disease, but also on its type and severity. It is also concluded that the rapid radiographic method of estimating total lung capacity can make little contribution to the diagnostic assessment of lung disease. However, the regression equations appropriate to particular ethnic groups could be used to measure TLC in normal subjects rapidly and inexpensively in places where specialised respiratory equipment and trained personnel are lacking.

Dependence of the output of a halothane vaporizer on thymol concentration.

The effect of thymol accumulation inside a Fluotec 3 vaporizer on the concentration of halothane delivered by the vaporizer was investigated. The vaporizer output was reduced progressively as the thymol concentration increased, but the reduction was less than that predicted by Raoult's Law. A reduction of 5% in output required an increase in thymol concentration of a factor of 650 compared to the concentration in fresh halothane, while a reduction of 10% required a 1100-fold increase in thymol concentration. The equilibration of the thymol from the wicks throughout the vaporizing chamber was very slow after the vaporizer was drained and filled with fresh halothane; the half-time was 2.7 days.

A static calibration method for the gas chromatographic determination of per cent concentrations of volatile anaesthetic agents.

A method is described for preparing static standards of per cent concentrations of volatile anaesthetic agents, that is designed to minimize adsorptive losses in the container used for the standards. The extent to which this aim has been realized was investigated for atmospheres of halothane, enflurane and isoflurane, both by monitoring the relative concentration within the container over a period of 30 min after the standard was prepared, and by measuring the absolute concentration of the volatile agents. Gas chromatography was used for both sets of measurements, with liquid standards being used for the absolute measurements. No discernible loss of volatile agent occurred over the 30-min period, and the measured concentrations agreed closely with the predicted values. The standard mixtures prepared by the method were suitable for calibrating a gas chromatograph, and allowed accurate determinations of volatile anaesthetics to be made. The relative standard error of the predicted concentration for a single standard mixture was less than 0.5%, and the calibration accuracy could be further improved by taking the mean chromatograph response to several standard mixtures prepared in succession.

Occupational exposure to nitrous oxide in four hospitals.

Diffusive samplers were used to measure the exposure of the anaesthetist, anaesthetic assistant and circulating nurse to nitrous oxide in every operating theatre of four Glasgow hospitals. Each theatre was surveyed over 1 or 2 weeks; samples were taken during every operating session. The exposures were in general surprisingly high. The anaesthetist's exposure was greater than ppm on about half the occasions. The study underlines the need for theatre ventilation systems and scavenging equipment to be properly maintained and for scavenging facilities to be used effectively. It is concluded that regular monitoring of staff exposures is required to check the effectiveness of antipollution measures.

Tax Equity and Fiscal Responsibility Act of 1982: an incentive to improve productivity in health care.

The productivity incentives of TEFRA are compared, using a sample that includes ten patients, four on Medicare and the remainder being either private pay patients or patients covered by commercial insurance. The effect of a ten percent increase or decrease in productivity on Medicare reimbursement before and after TEFRA is examined.

Characteristics of bacteria isolated by the anaerobic roll-tube method from cheeses and ground beef.

In this study the methods of Hungate were used to quantitate the anaerobic bacteria present in commercially available ground beef, cheddar cheese, and German hand cheese. Of 235 anaerobic roll-tube isolates from ground beef and German hand cheese, all were facultative anaerobes. Of 213 anaerobic roll-tube isolates from cheddar cheese, 91% were facultative anaerobes and 9% were obligate anaerobes. Using results of biochemical tests, 14 or the 17 obligately anaerobic isolates from cheddar cheese were Propionibacterium acnes, two were strains of Propionibacterium that could not be speciated, and one was tentatively identified as a strain of Streptococcus evolutus. Obligate anaerobes were estimated to be present in the cheddar cheese at a level of about 10(6)/g. The possible significance of these levels of P. acnes in nonsterile foods is discussed.

Metastatic Crohn's disease.

Metastatic Crohn's disease is a term used to describe a granulomatous reaction occurring in flexures, and separated from the affected areas of the gastro-intestinal tract by normal skin. Previous reports refer to such lesions affecting the groins, the male genitalia, a flexure on the anterior abdominal wall of an obese patient, and submammary regions. A further case, in which the retro-auricular areas are involved, is presented.

Calibration atmosphere generator for operating theatre pollution studies. A system for the controlled production of trace concentrations of inhalation anaesthetics.

The design and performance of an apparatus for producing accurately known trace concentrations of anaesthetic agents in air is described. The generator was constructed to facilitate the testing and calibration of equipment used in measuring the personal exposure of operating theatre staff to waste anaesthetic gases, and operates on the principle of the controlled injection of the pure anaesthetic agent into a diluting air stream. It is compact, simple to construct and easy to operate. Furthermore, it has a short stabilization time and can provide a wide range of predetermined concentrations with very good repeatability. It appears to be considerably more flexible than systems which have been described previously and should be of interest to groups involved in monitoring pollution in the operating theatre.