Ghrelin is present in teeth

Ghrelin belongs to the family of a gut-brain hormone that promotes food intake and controls energy balance. Recently, it has also been shown to regulate bone formation directly. Dental tissue shares several functional, developmental and anatomical similarities with bone, and in the present study we have investigated the presence of ghrelin in 44 human teeth using immunocytochemistry and radioimmunoassay. Both methods showed that the hormone is present in canines and molars, mainly in the odontoblasts but also in the pulp. Ghrelin could potentially play interesting physiological roles in teeth.     

Miniaturized lensless imaging systems for cell and microorganism visualization in point-of-care testing

Low-cost, robust, and user-friendly diagnostic capabilities at the point-of-care (POC) are critical for treating infectious diseases and preventing their spread in developing countries. Recent advances in micro- and nanoscale technologies have enabled the merger of optical and fluidic technologies (optofluidics) paving the way for cost-effective lensless imaging and diagnosis for POC testing in resource-limited settings. Applications of the emerging lensless imaging technologies include detecting and counting cells of interest, which allows rapid and affordable diagnostic decisions. This review presents the advances in lensless imaging and diagnostic systems, and their potential clinical applications in developing countries. The emerging technologies are reviewed from a POC perspective considering cost effectiveness, portability, sensitivity, throughput and ease of use for resource-limited settings.     

Cloning and Expression of the Vitreoscilla Hemoglobin Gene in Enterobacter Aerogenes: Effect on Cell Growth and Oxygen Uptake

The hemoglobins found in unicellular organisms show a great deal of chemical reactivity, protecting cells against oxidative stress, and hence have been implicated in a wider variety of potential functions than those traditionally associated with animal and plant hemoglobins. There are well-documented studies showing that bacteria expressing Vitreoscilla hemoglobin (VHb), the first prokaryotic hemoglobin characterized, have better growth and oxygen uptake rates than their VHb counterparts. Here, the expression of VHb, its effect on the growth and antioxidant enzyme status of cells under different culture conditions was studied by cloning the complete regulatory and coding sequences (vgb) for VHb in Enterobacter aerogenes. Contrary to what has been reported for Escherichia coli, the expression of vgb in E.aerogenes decreased several fold under 10% of atmospheric oxygen (2% oxygen) and its growth was not greatly improved by the presence of VHb. Measured either as viable cells or total cell mass, untransformed E. aerogenes grew better than the recombinant strains. At the late exponential phase, however, the vgb-bearing strain was determined to have a higher cell number and total cell mass than the strain bearing only the plasmid vector with no vgb insert. The VHb expressing strain also had an oxygen uptake rate several fold higher than its counterparts. Given that oxidative stress may occur upon elevated oxygen exposure and be balanced by the action of antioxi-dative compounds, the level of antioxidative response of E. aerogenes expressing VHb was also studied. The VHb expressing strain had substantially (1.5–2.6-fold) higher catalase activity than strains not expressing VHb. Both VHb+ and VHb- strains, however, showed similar levels of superoxide dismutase activity. The activity of both enzymes was also growth phase dependent. Stationary phase cells of all strains showed 2–5-fold higher activity for these enzymes than cells at the exponential phase.     

Enhanced production of acetoin and butanediol in recombinant Enterobacter aerogenes carrying Vitreoscilla hemoglobin gene

Microbial production of butanediol and acetoin has received increasing interest because of their diverse potential practical uses. Although both products are fermentative in nature, their optimal production requires a low level of oxygen. In this study, the use of a recombinant oxygen uptake system on production of these metabolites was investigated. Enterobacter aerogenes was transformed with a pUC8-based plasmid carrying the gene (vgb) encoding Vitreoscilla (bacterial) hemoglobin (VHb). The presence of vgb and production of VHb by this strain resulted in an increase in viability from 72 to 96 h in culture, but no overall increase in cell mass. Accumulation of the fermentation products acetoin and butanediol were enhanced (up to 83%) by the presence of vgb/VHb. This vgb/VHb related effect appears to be due to an increase of flux through the acetoin/butanediol pathway, but not at the expense of acid production.     

Cell growth and oxygen uptake of Escherichia coli and Pseudomonas aeruginosa are differently effected by the genetically engineered Vitreoscilla hemoglobin gene

Vitreoscilla hemoglobin is a good oxygen trapping agent and its presence in genetically engineered Escherichia coli helps this bacterium to grow better. Here, the potential use of this hemoglobin, for improving the growth and the oxygen transfer properties of Pseudomonas aeruginosa as well as Escherichia coli, was investigated. To stably maintain it in both bacteria, a broad-host range cosmid vector (pHG1), containing the entire coding sequence for Vitreoscilla hemoglobin gene and its native promoter on a 2.3 kb fragment, was constructed. Though at different levels, both bacteria produced hemoglobin and while the oxygen uptake rates of vgb-bearing strains were 2-3-fold greater than that of non-vgb-bearing strains in both bacteria, the growth advantage afforded by the presence of Vitreoscilla hemoglobin was somewhat varied. As an alternative to the traditional method of the improvement of oxygen transfer properties of the environment in which cells are grown, the genetic manipulation applied here improved the oxygen utilization properties of cells themselves.     

Ghrelin in plants: what is the function of an appetite hormone in plants?

In the present work, we provide compelling evidence for the expression of a ghrelin-like peptide hormone that has only been associated with animals, in various plant tissues. Ghrelin, the appetite stimulating hormone, has been identified from a number of different species including humans, rat, pig, mouse, gerbil, eel, goldfish, bullfrog and chicken. The study here was conducted using an immunohistochemistry assay to screen whether plants have any ghrelin immunoreactivity. In this respect, Prunus x domestica L. and Marus alba were examined. Immunohistochemistry results showed that there is a strong human ghrelin immunoreactivity substance in the parenchyma cells of these plants. This was entirely unexpected since this hormone was considered to be present solely in animals. Thus, this study is the first to report the presence of a peptide with ghrelin-like activity in plants, a finding that has only been observed in the animal kingdom. RIA analysis confirmed that these plants contain significant amounts of this substance. Furthermore, reverse-phase HPLC analyses of plant extracts showed an elution characteristic of the peptide identical to that of human ghrelin. In general, fruit from both plants had higher levels of the peptide than the vegetative parts.     

Degradation of Benzene,Toluene and Xylene by Pseudomonas aeruginosa Engineered with the Vitreoscilla Hemoglobin Gene

This study concerns the potential use of Pseudomonas aeruginosa expressing the Vitreoscilla hemoglobin gene for the degradation of important harmful aromatic compounds such as benzene, toluene, and xylene (BTX). The use of these compounds by both strains was determined as the production of cell mass (viable cell number) in a minimal medium containing any one of the BTX compounds as the sole carbon and energy source. Furthermore, the BTX degradation capability of both strains was monitored by measuring the production of 3‐methylcatechol, a common intermediate. For the cells of the logarithmic phase, which were grown at high aeration/high agitation or low aeration/low agitation, the engineered strain showed a better growth rate than the host strain. With the benzene in the medium, the recombinant strain exhibited a higher (up to 4‐fold) cell density than the parental wild‐type strain at this phase. In contrast, regarding the cells of the late stationary phase under high aeration/high agitation conditions, the host strain had generally higher viable cell numbers than the recombinant strain. At this phase this difference was, however, less significant under the conditions of low aeration/low agitation. Similarly, in toluene containing medium (at high aeration/high agitation) the recombinant strain showed a higher cell density which was from a 15‐fold to almost one order of magnitude greater than its parental strain during the logarithmic phase where the cell density of P. aeruginosa remained nearly constant. Contrary to the results with benzene and toluene, both strains exhibited similar growth characteristics when they were grown in the presence of xylene. The positive effect of the oxygen uptake by the recombinant system on the BTX metabolizing activity was also apparent in a high accumulation of 3‐methylcatechol in the cultures of the recombinant strain. At certain points of incubation, the hemoglobin expressing strain showed a significantly (p < 0.05) higher 3‐methylcatechol accumulation than the host strain. These results demonstrated the possible potential of the Vitreoscilla hemoglobin as an efficient oxygen uptake system for the bioremediation of some compounds of environmental concern.     

Vitreoscilla hemoglobin renders Enterobacter aerogenes highly susceptible to heavy metals

When expressed in heterologous microorganisms Vitreoscilla hemoglobin (VHb) acts as oxygen storage and causes a higher oxygen uptake. In this study, the effect of this protein on growth, sensitivity and antioxidant properties of Enterobacter aerogenes exposed to metal stress was investigated. The strain expressing VHb was more sensitive to mercury and cadmium as the minimal inhibitory concentration (MIC) for these metals was up to 2-fold lower in this strain than the host and the recombinant strain carrying a comparable plasmid. At lower concentrations than MIC, the metals partially limited growth and caused an inhibition proportional to metal concentration applied. The growth pattern of VHb expressing strain was also distinctly different from other two non-hemoglobin strains. The hemoglobin containing strain showed substantially higher superoxide dismuates (SOD) activity than the non-hemoglobin strains, while catalase levels were similar in all strains. All strains exposed to copper, however, showed similar MIC values, growth patterns, and SOD and catalase levels.     

Effects of simulated acid rain on the pollen germination and pollen tube growth of apple (Malus sylvestris Miller cv. Golden)

The pollens of apple flowers have been treated with simulated acid rain solutions in range of pHs 2.9 to 5.0 in order to determine the threshold proportion values that lead the observed symptoms of detriments of acid rain. Compared to controls (pH 6.5), pollen germination decreased by 41.75% at pH 3.3 and pollen tube elongation decreased by 24.3% at pH 3.4. Acid rain threshold proportion value was around pH 3.3 and 3.4 for apple pollen germination and pollen tube elongation, respectively. Furthermore, pollen tube elongation was determined to be more sensitive to acid rain than pollen germination. The pH values below 3.1 resulted in complete destruction of pollen tubes. Pollen germination entirely stopped at around pH 3.0. Finally, it has been shown that the acid rain has a blocking effect on pollen germination and pollen tube elongation in apple. The conclusion is that not only pH value but also the quantity of acid rain is important factor in germination. The results were found statistically significant through the LSD test at levels of p < 0.05 and p < 0.01.