Overexpression of polyphosphate kinase gene (ppk) increases bioinsecticide production by Bacillus thuringiensis

Polyphosphate (polyP), synthesized by polyP kinase (PPK) using the terminal phosphate of ATP as substrate, performs important functions in every living cell. The present work reports on the relationship between polyP metabolism and bioinsecticide production in Bacillus thuringiensis subsp. israelensis (Bti). The ppk gene of Bti was cloned into vector pHT315 and the effect of its overexpression on endotoxin production was determined. Endotoxin production by the recombinant strain was found to be consistently higher than that by the wild type strain and the strain that carried the empty plasmid. The toxicity of the recombinant mutant strain (LC₅₀ 5.8 ± 0.6 ng ml^?1) against late 2nd instar Culex quinquefasciatus was about 7.7 times higher than that of Bti (LC₅₀ 44.9 ± 7 ng ml^?1). To our knowledge this is the first reported study which relates polyP metabolism with bioinsecticide biosynthesis.     

Further investigation of the mechanism of <Emphasis Type="Italic">Vitreoscilla</Emphasis> hemoglobin (VHb) protection from oxidative stress in <Emphasis Type="Italic">Escherichia coli</Emphasis>

In Escherichia coli, Vitreoscilla hemoglobin (VHb) protects against oxidative stress, perhaps, in part, by oxidizing OxyR. Here this protection, specifically VHb-associated effects on superoxide dismutase (SOD) and catalase levels, was examined. Exponential or stationary phase cultures of SOD⁺ or SOD⁻ E. coli strains with or without VHb and oxyR antisense were treated with 2 mM hydrogen peroxide without sublethal peroxide induction, and compared to untreated control cultures. The hydrogen peroxide treatment was toxic to both SOD⁺ and SOD⁻ cells, but much more to SOD⁻ cells; expression of VHb in SOD⁺ strains enhanced this toxicity. In contrast, the presence of VHb was generally associated in the SOD⁺ background with a modest increase in SOD activity that was not greatly affected by oxyR antisense or peroxide treatment. In both SOD⁺ and SOD⁻ backgrounds, VHb was associated with higher catalase activity both in the presence and absence of peroxide. Contrary to its stimulatory effects in stationary phase, in exponential phase oxyR antisense generally decreased VHb levels.     

Dopamine and octopamine influence avoidance learning of honey bees in a place preference assay

Biogenic amines are widely characterized in pathways evaluating reward and punishment, resulting in appropriate aversive or appetitive responses of vertebrates and invertebrates. We utilized the honey bee model and a newly developed spatial avoidance conditioning assay to probe effects of biogenic amines octopamine (OA) and dopamine (DA) on avoidance learning. In this new protocol non-harnessed bees associate a spatial color cue with mild electric shock punishment. After a number of experiences with color and shock the bees no longer enter the compartment associated with punishment. Intrinsic aspects of avoidance conditioning are associated with natural behavior of bees such as punishment (lack of food, explosive pollination mechanisms, danger of predation, heat, etc.) and their association to floral traits or other spatial cues during foraging. The results show that DA reduces the punishment received whereas octopamine OA increases the punishment received. These effects are dose-dependent and specific to the acquisition phase of training. The effects during acquisition are specific as shown in experiments using the antagonists Pimozide and Mianserin for DA and OA receptors, respectively. This study demonstrates the integrative role of biogenic amines in aversive learning in the honey bee as modeled in a novel non-appetitive avoidance learning assay.     

Production of methionine γ- lyase in recombinant Citrobacter freundii bearing the hemoglobin gene

The production of antileukemic enzyme methionine γ-lyase (MGL) in distinctly related bacteria, Citrobacter freundii and in their recombinants expressing the Vitresocilla hemoglobin (VHb) has been studied. This study concerns the potential of Citrobacter freundii expressing the Vitreoscilla hemoglobin gene (vgb) for the methionine γ- liyase production. Methionine γ- liyase production by Citrobacter freundii and its vgb(-) and vgb(+) bearing recombinant strain was studied in shake-flasks under 200 rpm agitation, culture medium and 30 °C in a time-course manner. The vgb(+) and especially the carbon type had a dramatic effect on methionine γ- liyase production. The vgb(+) strain of C. freundii had about 2-fold and 3.1-fold higher levels of MGL than the host and vgb(-) strain, respectively.     

The effect of recombinant human erythropoietin on serum selenium levels in hemodialysis patients

Successful results in the treatment of anemia, one of the main complications of chronic renal failure, can be achieved by the use of recombinant human erythropoietin (RhEPO), which is available almost fifteen years in clinics. On the other hand, as both chronic renal failure and maintenance hemodialysis reduce the levels of trace elements, this study was designed to evaluate the interaction potential of RhEPO with serum concentrations of selenium (Se) during four months. Thirty one adult hemodialysis outpatients participated in the study. Ten of them, not on any drug therapy to interact with RhEPO, recruited as “Control Group”, and the remainder, on RhEPO therapy, as “RhEPO Group”. Blood was drawn from the Control Group at the beginning of the study, and from the RhEPO Group at every month for four months. Serum erythropoietin levels were measured by a radioimmunoassay method and Se status by a spectrofluorometric method. It was found that Se levels were not affected by RhEPO treatment during 3 months of therapy, while an increase was seen on the fourth month. The observation indicates that the increase in serum Se levels would be significant in longer than three-month RhEPO treatment.     

The gluteal fasciocutaneous rotation-advancement flap with V-Y closure in the management of sacral pressure sores

The sacral region is one of the most frequent sites of pressure sore development, and local flaps in the gluteal region are usually preferred when surgical closure is needed. The authors used the gluteal fasciocutaneous rotation-advancement flap with V-Y closure to manage sacral pressure sores in 15 patients. The design was a combination of the classic rotation and V-Y advancement flap patterns. When the wound was closed, the tension at the distal end of the rotation flap was relieved by flap advancement and the combined rotation-advancement action was supported laterally with V-Y closure. A wide skin pedicle was preserved at the inferomedial part of the flap. This pedicle augmented the blood supply to the flap skin and kept the surgical incision small, thus helping to reduce the risk of fecal contamination and associated wound-healing problems. This flap can also be converted to any design of fasciocutaneous or musculocutaneous V-Y advancement flap, should such a change be required. The largest defects that were closed with a unilateral rotation-advancement flap and bilateral rotation-advancement flaps were 12 and 18 cm in diameter, respectively. In 1.5 to 35 months of follow-up, none of the patients developed wound dehiscence or flap necrosis requiring repeated surgery. This technique is simple, can be performed quickly, has minimal associated morbidity, and yields a good outcome.     

Increased expression of angiogenic markers in patients with seasonal allergic rhinitis

BACKGROUND: Increased vascularity due to neo-angiogenesis is an essential part of airway remodelling. Vascular endothelial growth factor (VEGF), CD34 and von Willebrand's factor (FvW) are known angiogenic markers. Angiogenesis and airway remodelling has been documented in asthma but not in allergic rhinitis. OBJECTIVE: We aimed to investigate the presence of increased angiogenesis and its relation to angiogenic molecules, namely VEGF, CD34 and FvW, in endothelial cells of nasal mucosa in patients with seasonal allergic rhinitis (SAR), using three different immunohistochemical analysis methods, namely HSCORE, microvessel density (MVD) and vascular surface density (VSD). The findings in allergic rhinitis were compared with the findings in nasal septal deviation (NSD), which is not associated with increased angiogenesis. METHODS: Twenty patients with symptomatic SAR, who were not under treatment, were enrolled in the study. Ten patients with NSD, who needed surgical therapy, served as the control group. Demographic characteristics did not differ between the two groups. Inferior turbinate biopsy was obtained from SAR patients and control patients, under local anaesthesia and during surgery respectively. All biopsies were evaluated for angiogenesis on the basis of VEGF, CD34 and FvW by two blinded histologists using three immunohistochemical analysis methods (HSCORE, MVD and VSD).Results. HSCORE, estimated on the basis of each staining technique, showed statistically significant differences among the two groups (p=0.002; p=0.045; p=0.016, respectively). Anti-CD34 and anti-VEGF showed higher MVD values in SAR when compared to the controls (p=0.038; p=0,009, respectively). No statistically significant difference was found in Anti-FvW-based MVD between SAR patients and controls (p=0.071). The measurements of VSD for FvW and VEGF from nasal biopsy specimens displayed a statistically significant difference between the two groups (p=0.004; p=0.0001, respectively). However, measurement of VSD for CD-34 was not significantly different between the groups (p=0.086). On the other hand, morphometric data obtained by all three methods did not correlated. CONCLUSION: There are a few studies that have investigated the essential role of angiogenesis in the pathogenesis of allergic rhinitis. We conclude that, increased angiogenesis may be as prominent in patients with allergic rhinitis as in patients with non-allergic nasal pathologies and may play an important role in the remodelling of nasal mucosa of subjects with SAR.     

Colonization history and population differentiation of the Honey Bees (Apis mellifera L.) in Puerto Rico

Honey bees (Apis mellifera L.) are the primary commercial pollinators across the world. The subspecies A. m. scutellata originated in Africa and was introduced to the Americas in 1956. For the last 60 years, it hybridized successfully with European subspecies, previous residents in the area. The result of this hybridization was called Africanized honey bee (AHB). AHB has spread since then, arriving to Puerto Rico (PR) in 1994. The honey bee population on the island acquired a mosaic of features from AHB or the European honey bee (EHB). AHB in Puerto Rico shows a major distinctive characteristic, docile behavior, and is called gentle Africanized honey bees (gAHB). We used 917 SNPs to examine the population structure, genetic differentiation, origin, and history of range expansion and colonization of gAHB in PR. We compared gAHB to populations that span the current distribution of A. mellifera worldwide. The gAHB population is shown to be a single population that differs genetically from the examined populations of AHB. Texas and PR groups are the closest genetically. Our results support the hypothesis that the Texas AHB population is the source of gAHB in Puerto Rico.     

Protein A immunosensor for the detection of immunoglobulin G by impedance spectroscopy

A novel highly sensitive electrochemical impedimetric Protein A immunosensor for the determination of immunoglobulin G (IgG) was developed by immobilization of Protein A within a newly synthesized, and characterized polymer, poly(maleicanhydride-alt-decene-1). TiO₂ nanoparticles (10–30 nm) were synthesized, characterized with X-ray diffraction, transmission electron microscopy and Brunauer–Emmett–Teller surface analysis. The electron transfer between IgG and the poly(maleicanhydride-alt-decene-1)-TiO₂-Protein A is quasireversible with a formal potential of 225 mV vs Ag|AgCl. The response of the poly(maleicanhydride-alt-decene-1)-TiO₂-Protein A immunosensor was proportional to IgG concentration with a correlation coefficient of 0.9963. The detection limit and linear range was 0.57 ng mL^?1 and 0.0062–500 μg mL^?1, respectively. Impedance measurments showed that synthesized TiO₂ nanoparticles have better conducting properties compared with commercial degussa P25 TiO₂ nanoparticles. The nonspecific binding of anti-MBP was 10 %. The label-free impedimetric immunosensor provided a simple and sensitive detection method for the specific determination of IgG in human serum.