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RNA-binding proteins regulate cell fate decisions during nervous system development. The Msi family of RNA-binding proteins is expressed in multipotential neural progenitors, and is required for maintaining cells in a proliferative state. We demonstrate that Msi-1's ability to regulate progenitor maintenance is through the translational inhibition of the cyclin-dependent kinase inhibitor p21WAF-1. Msi-1 ectopic expression increases the proliferation rate and the capacity to regulate p21WAF-1 protein expression, independent of p53. The 3' untranslated region (UTR) of the native p21(WAF-1) mRNA contains a Msi-1 consensus-binding site that permits Msi-1 to directly repress the translation of p21WAF-1 protein. Reduction of Msi-1 through antisense leads to aberrant p21WAF-1 expression, which significantly impairs neural differentiation. A double knockdown for p21WAF-1 and Msi-1 rescues the production of mature MAP+ neurons. Our results further elucidate the symbiotic relationship between cell cycle withdrawal and the onset of differentiation in the developing nervous system, as well as increasing the understanding of the influence that RNA-binding proteins serve in regulating these processes.

Bacterial motility was recognized 300 years ago. Throughout this history, research into motility has led to advances in microbiology and physics. Thirty years ago, this union helped to make run and tumble chemotaxis the paradigm for bacterial movement. This review highlights how this paradigm has expanded and changed, and emphasizes the following points. The absolute magnitude of swimming speed is ecologically important because it helps determine vulnerability to Brownian motion, sensitivity to gradients, the type of receptors used and the cost of moving, with some bacteria moving at 1 mm s(-1). High costs for high speeds are offset by the benefit of resource translocation across submillimetre redox and other environmental gradients. Much of environmental chemotaxis appears adapted to respond to gradients of micrometres, rather than migrations of centimetres. In such gradients, control of ion pumps is particularly important. Motility, at least in the ocean, is highly intermittent and the speed is variable within a run. Subtleties in flagellar physics provide a variety of reorientation mechanisms. Finally, while careful physical analysis has contributed to our current understanding of bacterial movement, tactic bacteria are increasingly widely used as experimental and theoretical model systems in physics.

Diatom frustules have been used for the first time as templates for the fabrication of gold nanostructures; high-precision replicas featuring complex three-dimensional gold nanostructures from the nano- to the microscale were achieved.

A simple procedure for fabrication of gold films with nanorod arrays is described. The method is based on thermal evaporation of gold onto a porous alumina (PA) membrane used as a template. The gold films were obtained after removing the template and characterized using scanning electron microscopy, atomic force microscopy and ultraviolet-visible spectrophotometry. The prepared gold films are composed of arrays of sharp (<20 nm at apex) rod-shaped gold nanostructures. These structures closely follow the organization and distribution of pores of the PA template. The length of the gold nanostructures is estimated to range from 300 nm to more than 1000 nm. It was found that their length is influenced by the size of the pores in the PA and the temperature of the PA during gold evaporation. Spectrophotometric characterization shows that the prepared gold films exhibit a surface plasmon resonance absorption peak located between 525 and 540 nm.

Understanding the molecular events that govern neural progenitor lineage commitment, mitotic arrest, and differentiation into functional progeny are germane to our understanding of neocortical development. Members of the family of bone morphogenetic proteins (BMPs) play pivotal roles in regulating neural differentiation and apoptosis during neurogenesis through combined actions involving Smad and TAK1 activation. We demonstrate that BMP signaling is required for the induction of apoptosis of neural progenitors and that NRAGE is a mandatory component of the signaling cascade. NRAGE possesses the ability to bind and function with the TAK1-TAB1-XIAP complex facilitating the activation of p38. Disruption of NRAGE or any other member of the noncanonical signaling cascaded is sufficient to block p38 activation and thus the proapoptotic signals generated through BMP exposure. The function of NRAGE is independent of Smad signaling, but the introduction of a dominant-negative Smad5 also rescues neural progenitor apoptosis, suggesting that both canonical and noncanonical pathways can converge and regulate BMP-mediated apoptosis. Collectively, these results establish NRAGE as an integral component in BMP signaling and clarify its role during neural progenitor development.

Abstract We investigated whether bacterial motility and chemotaxis in the ocean enables bacteria to approach and follow microscopic, moving, point sources of nutrients. The turbulent nature of the ocean combined with the imprecision of run and tumble chemotaxis has led to the assumption that marine bacteria cannot cluster around microscopic point sources. Recent work, however, shows that marine bacteria use a run and reverse strategy. We examine the ability of marine bacteria that use run and reverse chemotaxis to respond to and follow a moving point source. The addition of the 6 mum in diameter motile algae Pavlova lutheri to cultures of the marine bacteria Pseudoalteromonas haloplanktis and Shewanella putrefaciens revealed bacterial tracking individual free-swimming algae. The marine bacteria travelled at up to 445 mum s(-1) when tracking, up to 237 mum s(-1) when not tracking and up to 126 mum s(-1) in cultures without the algae. Tracking maintained bacteria within one run length of an alga. The bacteria appeared able to steer, consecutively turning up to 12 times toward the motile algae. They recovered from the occasional incorrect turn to continue moving around the swimming alga, indicating that marine bacteria can track moving point sources and form transient phyto-bacterial associations. Our analysis suggests tracking increases nutrient uptake by bringing cells into regions of high nutrient concentrations and by increased advection from high speeds. This result describes what is, apparently, one of the tightest spatial and temporal links between free-living primary and secondary producers in planktonic ecosystems.

Abstract To better understand the trigger for and use of motility in marine bacterial chemotaxis, specific (amino acids) chemical stimuli were used to test the effect on bacterial speed and reorientation. An assay system was developed to analyse bacterial behavioural responses to point-like nutrient sources (beads 10-40 mum). The marine bacteria Pseudoalteromonas haloplanktis, Shewanella putrefaciens, Deleya marina, the enteric bacterium Escherichia coli and an enriched assemblage of marine bacteria were used in the assay. E. coli responded to the amino acids (e.g. serine, leucine) in this assay in a manner similar to the classical capillary plating method, and accumulated near the attractants using biased random walks and maximum speeds of less than 30 mum s(-1). The marine bacteria travelled more than 100 mum s(-1) and reversed direction instead of randomly tumbling to reorientate. Marine bacteria also showed different chemotactic responses. The enriched marine community and P. haloplanktis were repelled by serine while leucine was an attractant for all three marine isolates. More importantly marine bacteria formed band specific distances (>20 mum) away from individual beads. The bands were composed of free-swimming bacteria rather than bacteria attached to the beads or chamber surfaces. The bands' formation time (25-180 s) and width (5-20 mum) varied depending on the bacterial strains and attractant. This variation in chemotactic responses by the marine isolates may reflect adaptations to specific ecological niches of bacterioplankton in the ocean. However, band forming ability by marine bacteria has still only been reported in experimental studies, nutrient coupling between nutrient sources and bands of chemotactic marine bacteria have yet to be detected in the natural environment. The fragility of the bands, a clear association between free-swimming bacteria and nutrient, indicates the difficulty and potentially sets limits for finding microzones of bacteria around particles in the open ocean.

The influence of body size on the energetic cost of movement is well studied in animals but has been rarely investigated in bacteria. Here, I calculate the cost of four chemotactic strategies for different-sized bacteria by adding the costs of their locomotion and reorientation. Size differences of 0.1 microm result in 100,000-fold changes in the energetic cost of chemotaxis. The exact cost for any given size is a nonlinear function of flagella length, the minimum speed necessary to detect and respond to a signal, and the gradient of the signal. These parameters are interlinked in such a way that body size and strategy are tightly coupled to particular environmental gradients, offering avenues for explaining and exploring diversity and competition. The analysis here has implications beyond bacteria. Power-law regression through the minimum costs of transport for different kinds of chemotaxis has the same slope as that for swimming animals, suggesting a universal allometric equation for all swimming organisms.

Over a two-year period, telemedicine was used to deliver training and development services for health, education and welfare staff in two remote towns in South Australia - Roxby Downs and Coober Pedy. Both are mining towns but they have different profiles in terms of the community's mental health needs. The services were provided by the Child and Adolescent Mental Health Services (CAMHS) from the Women's and Children's Hospital in Adelaide, South Australia. The media used were videoconferencing, telephone, video-tapes, the Internet and printed material. During 1998-9, professional staff in the two locations participated in structured videoconferencing seminars that addressed important mental health topics, chosen in response to surveys of the needs of the participants. The videoconferencing sessions were sometimes used to discuss specific patient cases. Each remote town was also supported via videoconferencing by a nominated office of the CAMHS: Roxby Downs by the suburban office at Port Adelaide and Coober Pedy by the office in the industrial town of Port Pirie. This customized support was an important factor in the success of the professional development network.

Most bacteria in the ocean can be motile. Chemotaxis allows bacteria to detect nutrient gradients, and hence motility is believed to serve as a method of approaching sources of food. This picture is well established in a stagnant environment. In the ocean a shear microenvironment is associated with turbulence. This shear flow prevents clustering of bacteria around local nutrient sources if they swim in the commonly assumed "run-and-tumble" strategy. Recent observations, however, indicate a "back-and-forth" swimming behavior for marine bacteria. In a theoretical study we compare the two bacterial swimming strategies in a realistic ocean environment. The "back-and-forth" strategy is found to enable the bacteria to stay close to a nutrient source even under high shear. Furthermore, rotational diffusion driven by thermal noise can significantly enhance the efficiency of this strategy. The superiority of the "back-and-forth" strategy suggests that bacterial motility has a control function rather than an approach function under turbulent conditions.

The rotation of trainee registrars in obstetrics and gynaecology to peripheral centres in South Australia was introduced for the first time in January 1998. A pilot study of the use of telemedicine to maintain the trainees' involvement in the established weekly training sessions conducted at the Women's and Children's Hospital (WCH) was also commenced at the same time. Sessions were problem based and required the trainees to be actively involved throughout. An electronic voting system (EVS) was used by the WCH audience, with the results of all responses being seen at the peripheral centres. Initial evaluation of the EVS as an educational tool was sufficiently positive to justify further studies of its use in this environment. The availability of voting units at the peripheral sites, used in conjunction with the main centre, will provide an exciting opportunity for further research.

The diffusion of telemedicine services in Australia over the last four years has been uneven. Some of the major barriers to the adoption of telemedicine relate to the nature of the industry, including its immaturity, the limited telecommunications infrastructure, the lack of appropriate dialogue between vendors and buyers about solutions required, and the lack of partnerships in the industry. Remuneration is only one barrier. There are, of course, other substantial organizational, financial and attitudinal barriers to the adoption of telemedicine. Further development of telemedicine in Australia will require detailed assessment of these matters.

In 1994, a telemedicine network was established linking the renal unit at The Queen Elizabeth Hospital to three satellite dialysis centres in South Australia. In the first two and a half years of operation, the telemedicine equipment was used on over 6000 occasions. Interviews were conducted with 18 medical, nursing and allied health staff and dialysis patients. The main finding was that the full range of staff, from surgeons and nephrologists to allied health staff and nurses, were able use the technology successfully for clinical purposes. A second finding was that the technology enabled staff to perform a wide range of clinical procedures, from routine outpatient consultations and monitoring infections to making decisions about retrieval or confirming decisions to operate. A third finding was that telemedicine enabled the renal unit to provide improved services in which teams of staff at the different sites cooperated in ways that were not possible before the telemedicine links became available.

The precision with which motile heterotrophic bacteria could position themselves in microbial mats was determined. This required the development of a technique to view motile bacteria in situ. This was successfully achieved by replacing a 1-cm-diameter minicore from the mat sediment with 210- to 300-(mu)m-diameter glass beads or sieved agar. After allowing 3 days for regrowth of the mat into the transparent medium, a cross section showed that bacteria formed a layer as thin as 30 to 40 (mu)m at a depth of 500 (mu)m below the surface. Bacterial concentrations in this microlamination were 20 times above background. Mean speeds were 200 (mu)m s(sup-1) inside and 60 (mu)m s(sup-1) outside the microlamination. The percentages of bacteria turning per 30 s were 93% inside and 10% outside the microlamination. Artificial chemical gradients were unsuccessful in stimulating microlamination formation or in eliciting the same extent of speed and turning responses. The significance of the results is that it is now possible to microscopically examine sedimentary bacteria in situ. Our first examination indicates that some bacteria form chemotactic microlaminations by increasing their turning frequency. This behavior is opposite that described in the enteric-based model of chemotactic movement, in which positive chemotaxis is achieved by decreasing the turning frequency.

Seawater enrichments of marine bacteria clustered in 20- to 50-(mu)m-wide bands near air-water interfaces. The cells within the band travelled at up to 212 (mu)m s(sup-1) and at an average speed of 163 (mu)m s(sup-1). Mean cell speeds peaked mid-run at 187 (mu)m s(sup-1). At the end of the run, bacteria reversed direction rather than randomly reorienting. The duration of the stops during reversal was estimated at 18 ms, six to seven times shorter than that found in enteric bacteria. Cells hundreds of micrometers from the band travelled at half the speed of the bacteria in the band. The fastest isolate from the seawater enrichment was identified as Shewanella putrefaciens and had an average speed of 100 (mu)m s(sup-1) in culture. Air-water interfaces produced no clustering or speed changes in isolates derived from enrichments. Salinity and pH, however, both influenced speed. The speed and reversal times of the seawater enrichments indicate that the bacteria in them are better adapted for clustering around small point sources of nutrients than are either enteric or cultured marine bacteria.

We carried out a longitudinal survey to evaluate the users' attitudes to the introduction of telemedicine into the dialysis units of a renal ward in South Australia. The first questionnaire was distributed to all members of staff involved with the introduction of the system. There were 44 responses (80%). Staff were fairly positive about the telemedicine system, and felt that it was easy to use and reliable. They also clearly felt that the confidentiality and privacy offered by the system in an open ward were unsatisfactory. A second questionnaire was distributed to all staff about six months later and there were 40 responses (66%). Of these, 22 could be matched with the responses from the first survey (a response rate of 50% from the first sample). There were no significant differences in the staff members' feelings between the two surveys, except in two cases: there were significant changes in staff opinion about the degree of confidentiality (P < 0.05) and privacy (P < 0.01) offered by the system, with attitudes becoming more positive in each case. The results indicate the need for dialogue with users, in order to address their concerns regarding the system and practical difficulties. This study highlights the importance of planning, effort, cooperation and an appropriate culture within a renal unit in order for telemedicine to be accepted.

Natural communities of marine bacteria, an isolate (FMB-Bf3) from one marine community, and Escherichia coli were examined by video microscopy for the magnitude and uniformity of their speed. Natural communities formed tight microswarms that showed higher speeds (mean = 230 microns s-1) than did E. coli (15 microns s-1) or FMB-Bf3 (mean = 62 microns s-1). Outside the microswarms, the marine bacteria slowed to 45 microns s-1. Between turns, in mid run, and while travelling in straight lines, the natural-community bacteria accelerated up to 1,450 microns s-2 while the cultured bacteria showed maximum accelerations of 70 and 166 microns s-2. The frequency distribution of speed change for the marine bacteria was skewed towards a few large negative accelerations and a range of positive accelerations. The general pattern was one of relatively slow increases in speed followed by abrupt declines. The results indicate that the mechanical generation and energetic maintenance, as well as the environmental function, of bacterial motility need reappraisal. We conclude that the standard bacterial motility parameters of low and uniform speed, derived from culture-based studies, are not necessarily applicable to marine bacterial communities.

The motility characteristics of natural assemblages of coastal marine bacteria were examined. Initially, less than 10% of the bacteria were motile. A single addition of tryptic soy broth caused an increase in the motile fraction of cells but only after 7 to 12 h. Motility peaked at 15 to 30 h, when more than 80% of cells were motile. These results support the proposal that energy limits motility in the marine environment. Cell speeds changed more than an order of magnitude on timescales of milliseconds and hours. The maximum community speed was 144 (mu)m s(sup-1), and the maximum individual burst velocity was 407 (mu)m s(sup-1). In uniform medium, speed was an inverse function of tryptic soy broth concentration, declining linearly over 0.001 to 1.0%. In media where concentration gradients existed, the mean speed was a function of position in a spatial gradient, changing from 69 to 144 (mu)m s(sup-1) over as little as 15 to 30 (mu)m. The results suggest that marine bacteria are capable of previously undescribed quick shifts in speed that may permit the bacteria to rapidly detect and keep up with positional changes in small nutrient sources. These high speeds and quick shifts may reflect the requirements for useful motility in a turbulent ocean.

A wide variety of naturally occurring bacteria cannot be isolated by classical microbiological methods, hindering study of microbial communities. To partially remove this limitation, a method using optical trapping was developed. It allows for one-step isolation of bacteria from a complex community to a pure culture. The method transfers a single bacterium to sterile culture medium using a non-destructive laser beam. The ease with which a previously unculturable cell was cultured by trapping suggests that competition may limit growth in some natural communities of bacteria.

The Florida Department of Corrections has worked diligently to plan and implement a system of comprehensive institutional and community-based programs. These programs strive to establish a functional, cost-effective continuum of care for incarcerated individuals while providing necessary linkages essential to transferring inmates back into society with the knowledge and social skills necessary to lead a drug-free life. It is believed that a viable working model has been developed that will offer inmate services and, ultimately, afford them the opportunity and appropriate linkages to continue treatment as needed after incarceration.

The influence of Brownian motion on marine bacteria was examined. Due to their small size, marine bacteria rotate up to 1,400 degrees in one second. This rapid rotation makes directional swimming difficult or impossible, as a bacterium may point in a particular direction for only a few tens of milliseconds on average. Some directional movement, however, was found to be possible if swimming speed is sufficiently great, over approximately 100 μm sec(-1). This led to the testable hypothesis that marine bacteria with radiii less than about 0.75 μm should exceed this speed. The result of the increased speed is that marine bacteria may spend in excess of 10% of their total energy budget on movement. This expenditure is 100 times greater than values for enteric bacteria, and indicates that marine bacteria are likely to be immotile below critical size-specific nutrient concentrations.

The velocity, run time, path curvature, and reorientation angle of Chromatium minus were measured as a function of light intensity, temperature, viscosity, osmotic pressure, and hydrogen sulfide concentration. C. minus changed both velocity and run time. Velocity decreased with increasing light intensity in sulfide-depleted cultures and increased in sulfide-replete cultures. The addition of sulfide to cultures grown at low light intensity (10 microeinsteins m-2 s-1) caused mean run times to increase from 10.5 to 20.6 s. The addition of sulfide to cultures grown at high light intensity (100 microeinsteins m-2 s-1) caused mean run times to decrease from 15.3 to 7.7 s. These changes were maintained for up to an hour and indicate that at least some members of the family Chromatiaceae simultaneously modulate velocity and turning frequency for extended periods as part of normal taxis.

Monoclonal antibodies (MAb) were used to identify platelet membrane molecules that are expressed after platelet activation. Balb/C mice were immunized with fixed thrombin-activated human platelets and their spleen cells were fused with the murine myeloma cell line NS1-Ag4/1. The resulting hybridomas were screened for antibody production against fixed thrombin-activated platelets and fixed resting platelets by flow cytometry. Two MAbs 2C8 (an IgM) and 1E3 (an IgG2a) demonstrated significant binding to fixed thrombin-activated platelets while reacting minimally with fixed resting platelets. The reactivity of 2C8 and 1E3 were compared to MAb's S12 and AC1.2, both of which have known specificity for an alpha-granule membrane protein (GMP-140) expressed on the surface of activated platelets. In radioimmunoprecipitation studies, both 2C8 and 1E3 immunoprecipitated a protein of approximately 140 kDa similar to that precipitated by S12 and AC1.2. Immunodepletion studies, with S12, AC1.2, 1E3, and 2C8 confirm that they all react with the same antigen. 2C8 may recognize the same epitope as S12, whereas 1E3 appears to recognize a different epitope of the same molecule. The use of these MAbs to measure platelet activation in whole blood correlates well with the results of conventional platelet aggregometry.

Archaeomonads are chrysophyte cysts abundant in Weddell Sea sea ice, but they form in the water column in response to conditions that occur in areas where no sea ice is present. The association between archaeomonads and sea ice depends on a particular sequence of oceanographic conditions, beginning with lateral advection followed by vertical harvesting on rising ice crystals. Comparing fossil and modern distributions suggests archaeomonads underwent an ecological transition or expansion in the Early Tertiary Period, from sediment underlying anoxic waters to sediments underlying sea ice.

We have used a technique for the simultaneous measurement of platelet activation and aggregation in whole blood using two-color immunofluorescence and flow cytometry to study the relationship between the release reaction and aggregation. A monoclonal antibody specific for the alpha granule membrane protein GMP-140 was used to measure the release reaction, and a monoclonal antibody specific for platelet membrane glycoprotein Ib (GPIb) was used to identify platelets and platelet aggregates. Aggregates were identified as particles expressing both levels of GPIb and size larger than that of resting single platelets. Anticoagulated whole blood was incubated with platelet agonists. At various times samples of the blood were removed and immediately fixed with paraformaldehyde. Blood that had been anticoagulated with ethylenediamine tetraacetic acid showed progressive release of platelets but little or no aggregation. However, blood anticoagulated with citrate or heparin showed correlated release and aggregation. The degree of aggregation was greater in heparin than in citrate. The expression of GPIb and GMP-140 increased in direct proportion to the size of the aggregates. Aggregates were observed varying in apparent diameter up to approximately 20 microns. During prolonged incubation there was progressive disaggregation of adenosine diphosphate (ADP)-induced aggregates. After disaggregation the proportion of GMP-140 negative single platelets increased, indicating that both released and nonreleased platelets participated in the aggregation. There was little or no disaggregation of phorbol myristate acetate (PMA)-induced aggregates. The relatively small size and reversibility of platelet aggregates that we have observed in whole blood may be relevant to phenomena occurring in vivo and in extracorporeal circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma high-density lipoprotein cholesterol (HDLC) level was measured before and after alcohol abstinence and after resumption of a controlled alcohol dose in 16 marathon runners, 15 joggers, and 13 inactive men. A three-week period of abstinence resulted in a significant decrease in HDLC concentration in the inactive men (49.8 to 41.8 mg/dL). Three weeks of alcohol consumption (1,065 mL of beer per day) produced a significant increase in HDLC level to 50.9 mg/dL. No change in HDLC level was found for the marathon group or the joggers during abstinence or three weeks of alcohol intake. The consumption of alcohol in moderation seems to be associated with increased HDLC levels in inactive men but not in men who engage in regular running or jogging.