Localized bleaching in Hawaii causes tissue loss and a reduction in the number of gametes in <Emphasis Type="Italic">Porites compressa</Emphasis>

Localized bleaching (a discrete white area on the coral) was observed in one of the main framework-building corals in Hawaii, Porites compressa. This study aimed to determine the degree of virulence of the lesion. We investigated the whole-colony effects by following disease progression through time and examining the effect of localized bleaching on coral fecundity. After two months, 35 of 42 (83.3%) individually tagged colonies affected by localized bleaching showed tissue loss and partial colony mortality. Histological slides of healthy P. compressa and samples from colonies showing signs of localized bleaching were compared showing that affected colonies had a significant reduction (almost 50%) in gamete development, egg numbers, and egg size in the affected tissue. The observed localized bleaching results in both partial colony mortality and a reduced number of gametes and was termed Porites Bleaching with Tissue Loss (PBTL).     

U-2012: An improved Lowry protein assay, insensitive to sample color, offering reagent stability and enhanced sensitivity

Traditional colorimetric protein assays such as Biuret, Lowry, and modified Lowry (U-1988) are unsuitable for colored biological samples. Here we describe an improved Lowry protein assay (U-2012), which utilizes stable reagents and offers enhanced sensitivity over the U-1988 assay. U-2012 circumvents interference from colored pigments and other substances (for example sugars) bound to perchloric acid (PCA) precipitated proteins by hydrogen peroxide (H2O2) induced oxidation at 50°C. Unused hydrogen peroxide is neutralized with sodium pyruvate before protein estimation for a stable end color. The U-2012 assay is carried out on the PCA precipitated protein pellet after neutralization (with Na2CO3 plus NaOH), solubilization (in Triton-NaCl), decolorization (by H2O2) and pyruvate treatment. Protein contents in red wine and homogenates of beetroot and blueberry are calculated from standard curves established for various proteins and generated using a rectangular hyperbola with parameters estimated with Microsoft Excel's Solver add-in. The U-2012 protein assay represents an improvement over U-1988 and gives a more accurate estimation of protein content.     

Satb1 ablation alters temporal expression of immediate early genes and reduces dendritic spine density during postnatal brain development

Complex behaviors, such as learning and memory, are associated with rapid changes in gene expression of neurons and subsequent formation of new synaptic connections. However, how external signals are processed to drive specific changes in gene expression is largely unknown. We found that the genome organizer protein Satb1 is highly expressed in mature neurons, primarily in the cerebral cortex, dentate hilus, and amygdala. In Satb1-null mice, cortical layer morphology was normal. However, in postnatal Satb1-null cortical pyramidal neurons, we found a substantial decrease in the density of dendritic spines, which play critical roles in synaptic transmission and plasticity. Further, we found that in the cerebral cortex, Satb1 binds to genomic loci of multiple immediate early genes (IEGs) (Fos, Fosb, Egr1, Egr2, Arc, and Bdnf) and other key neuronal genes, many of which have been implicated in synaptic plasticity. Loss of Satb1 resulted in greatly alters timing and expression levels of these IEGs during early postnatal cerebral cortical development and also upon stimulation in cortical organotypic cultures. These data indicate that Satb1 is required for proper temporal dynamics of IEG expression. Based on these findings, we propose that Satb1 plays a critical role in cortical neurons to facilitate neuronal plasticity.     

Evidence of Yersinia pestis DNA from fleas in an endemic plague area of Zambia

Background

Study protocols involving experimental animals often require the monitoring of different parameters not only in anesthetized, but also in free moving animals. Most animal research involves small rodents, in which continuously monitoring parameters such as temperature and heart rate is very stressful for the awake animals or simply not possible. Aim of the underlying study was to monitor heart rate, temperature and activity and to assess inflammation in the heart, lungs, liver and kidney in the early postoperative phase after experimental cardiopulmonary bypass involving 45 min of deep hypothermic circulatory arrest in rats. Besides continuous monitoring of heart rate, temperature and behavioural activity, the main focus was on avoiding uncontrolled death of an animal in the early postoperative phase in order to harvest relevant organs before autolysis would render them unsuitable for the assessment of inflammation.

Findings

We therefore set up a telemetry-based system (Data Science International, DSI?) that continuously monitored the rat's temperature, heart rate and activity in their cages. The data collection using telemetry was combined with an analysis software (Microsoft excel?), a webmail application (GMX) and a text message-service. Whenever an animal's heart rate dropped below the pre-defined threshold of 150 beats per minute (bpm), a notification in the form of a text message was automatically sent to the experimenter's mobile phone. With a positive predictive value of 93.1% and a negative predictive value of 90.5%, the designed surveillance and alarm system proved a reliable and inexpensive tool to avoid uncontrolled death in order to minimize suffering and harvest relevant organs before autolysis would set in.

Conclusions

This combination of a telemetry-based system and software tools provided us with a reliable notification system of imminent death. The system's high positive predictive value helped to avoid uncontrolled death and facilitated timely organ harvesting. Additionally we were able to markedly reduce the drop out rate of experimental animals, and therefore the total number of animals used in our study. This system can be easily adapted to different study designs and prove a helpful tool to relieve stress and more importantly help to reduce animal numbers.     

Constraints on Salt Marsh Development Following Managed Coastal Realignment: Dispersal Limitation or Environmental Tolerance?

Salt marshes restored through managed coastal realignment (MR) often develop slowly and show persistent differences in vegetation from natural marshes. Development might be constrained by the availability of propagules or poor suitability of the abiotic environment for their establishment. To distinguish between these factors, we compared vegetation colonization and environmental conditions at a salt marsh created by MR at Brancaster, Norfolk, UK, with five reference marshes, varying in age from 30 to circa 6,000 years. After 5 years, plant communities of the MR site remained different from those in mature reference marshes. In contrast, the communities of the youngest reference marsh were not significantly different from mature reference marshes. At the MR site, abundance of perennial and later‐successional species was low and large areas remained unvegetated. These differences are unlikely to be due to dispersal limitation, because 76% of the species from the local species pool colonized the site within 5 years. Although the annuals Salicornia europaea and Suaeda maritima were abundant by year 2, they were not ubiquitous until the end of the study. Tidal elevations of the MR site were suitable for vegetation development, but soil redox potentials were lower than that at the reference sites. Reducing conditions in the MR site appear to be the major cause of vegetation differences from the reference marshes, as they are associated with an abundance of bare ground and a small range of vegetation clusters. Measures to avoid low sediment redox potentials may have a great benefit in some salt marsh restoration projects.     

Carry-over of differential salt tolerance in plants grown from dimorphic seeds of Suaeda splendens

Background and Aims

Halophytic species often show seed dimorphism, where seed morphs produced by a single individual may differ in germination characteristics. Particular morphs are adapted to different windows of opportunity for germination in the seasonally fluctuating and heterogeneous salt-marsh environment. The possibility that plants derived from the two morphs may also differ physiologically has not been investigated previously.

Methods

Experiments were designed to investigate the germination characteristics of black and brown seed morphs of Suaeda splendens, an annual, C₄ shrub of non-tidal, saline steppes. The resulting seedlings were transferred to hydroponic culture to investigate their growth and photosynthetic (PSII photochemistry and gas exchange) responses to salinity.

Key Results

Black seeds germinated at low salinity but were particularly sensitive to increasing salt concentrations, and strongly inhibited by light. Brown seeds were unaffected by light, able to germinate at higher salinities and generally germinated more rapidly. Ungerminated black seeds maintained viability for longer than brown ones, particularly at high salinity. Seedlings derived from both seed morphs grew well at high salinity (400 mol m⁻³ NaCl). However, seedlings derived from brown seeds performed poorly at low salinity, as reflected in relative growth rate, numbers of branches produced, F_v/F_m and net rate of CO₂ assimilation.

Conclusions

The seeds most likely to germinate at high salinity in the Mediterranean summer (brown ones) retain a requirement for higher salinity as seedlings that might be of adaptive value. On the other hand, black seeds, which are likely to delay germination until lower salinity prevails, produce seedlings that are less sensitive to salinity. It is not clear why performance at low salinity, later in the life cycle, might have been sacrificed by the brown seeds, to achieve higher fitness at the germination stage under high salinity. Analyses of adaptive syndromes associated with seed dimorphism may need to take account of differences over the entire life cycle, rather than just at the germination stage.Key words: Chlorophyll fluorescence, germination, growth rate, halophyte, photosynthesis, photosystem II, salt tolerance, seed dimorphism, seed viability, Suaeda splendens     

Machine vision photogrammetry: a technique for measurement of microstructural strain in cortical bone.

Understanding local microstructural deformations and strains in cortical bone may lead to a better understanding of cortical bone damage development, fracture, and remodeling. Traditional experimental techniques for measuring deformation and strain do not allow characterization of these quantities at the microstructural level in cortical bone. This study describes a technique based on digital stereoimaging used to measure the microstructural strain fields in cortical bone. The technique allows the measurement of material surface displacements and strains by comparing images acquired from a specimen at two distinct stress states. The accuracy of the system is investigated by analyzing an undeformed image set; the test image is identical to the reference image but translated by a known pixel amount. An increase in the correlation sub-image train parameter results in an increase in displacement measurement accuracy from 0.049 to 0.012 pixels. Errors in strain calculated from the measured displacement field were between 39 and 564 microstrain depending upon the sub-image train size and applied image displacement. The presence of a microcrack in cortical bone results in local strain at the crack tip reaching 0.030 (30,000 microstrain) and 0.010 (10,000 microstrain) near osteocyte lacunae. It is expected that the use of this technique will allow a greater understanding of bone strength and fracture as well as bone mechanotransduction.     

Scintigraphie à l’OctréoScan® : aspects pratiques. Le point de vue du manipulateur

Evaluation of neuroendocrine tumors extent comprises a somatostatin receptor scintigraphy with OctréoScan^®. This examination begins with the radiopharmaceutical preparation and its quality control (dose, visual appearance, radiochemical purity, pH). The radiopharmaceutical is administered intravenously at a slow rate with respect of the contra-indications and recommendations. The patient's good respect of low residue diet and digestive preparations is essential for a good imaging quality. In addition, the technologist's psychological role (particularly for people suffering from claustrophobia) and adequate procedures must be taken into account. Several days are necessary to perform the examination that comprises whole body and planar (thoracic and abdominal) views, combined SPECT-CT imaging. This hybrid modality using fused images allows a good anatomical localisation of focal areas of increased uptake even in case of faint uptake. Some false-positive can be avoided (colonic stasis, gall bladder). SPECT-CT contribution to the diagnosis is certain.