A T3 and T7 Recombinant Phage Acquires Efficient Adsorption and a Broader Host Range

It is usually thought that bacteriophage T7 is female specific, while phage T3 can propagate on male and female Escherichia coli. We found that the growth patterns of phages T7M and T3 do not match the above characteristics, instead showing strain dependent male exclusion. Furthermore, a T3/7 hybrid phage exhibits a broader host range relative to that of T3, T7, as well as T7M, and is able to overcome the male exclusion. The T7M sequence closely resembles that of T3. T3/7 is essentially T3 based, but a DNA fragment containing part of the tail fiber gene 17 is replaced by the T7 sequence. T3 displays inferior adsorption to strains tested herein compared to T7. The T3 and T7 recombinant phage carries altered tail fibers and acquires better adsorption efficiency than T3. How phages T3 and T7 recombine was previously unclear. This study is the first to show that recombination can occur accurately within only 8 base-pair homology, where four-way junction structures are identified. Genomic recombination models based on endonuclease I cleavages at equivalent and nonequivalent sites followed by strand annealing are proposed. Retention of pseudo-palindromes can increase recombination frequency for reviving under stress

Salvianolic Acid B in Microemulsion Formulation Provided Sufficient Hydration for Dry Skin and Ameliorated the Severity of Imiquimod-induced Psoriasis-like Dermatitis in Mice

Psoriasis is a chronic inflammatory skin disorder with a pathogenesis involving the interleukin-23/interleukin-17 axis. Salvianolic acid B exerts several pharmacological effects, such as antioxidation, anti-inflammation, and antitumor effects. The anti-psoriatic effects of salvianolic acid B have not been reported. In this study, we aimed to determine the optimum vehicle for salvianolic acid B, investigate its therapeutic effect on psoriatic-like skin conditions, and explore its underlying mechanisms of action. BALB/c mice were administered topical imiquimod to induce psoriasis-like skin and were then randomly assigned to control, vehicle control, salvianolic acid B in vehicles, and 0.25% desoximetasone ointment treatment groups. Barrier function, cytokine expression, histology assessment, and disease severity were evaluated. The results showed that salvianolic acid B-containing microemulsion alleviated disease severity, reduced acanthosis, and inhibited interleukin-23/interleukin-17 (IL-23/IL-17) cytokines, epidermal proliferation, and increased skin hydration. Our study suggests that salvianolic acid B represents a possible new therapeutic drug for the treatment of psoriasis. In addition, such formulation could obtain high therapeutic efficacy in addition to providing sufficient hydration for dry skin

Bone Healing Improvements Using Hyaluronic Acid and Hydroxyapatite/Beta-Tricalcium Phosphate in Combination: An Animal Study

The purpose of this study was to investigate whether the use of HLA as an aqueous binder of hydroxyapatite/beta-tricalcium phosphate (HA-βTCP) particles can reduce the amount of bone graft needed and increase ease of handling in clinical situations. In this study, HA/βTCP was loaded in commercially available crosslinking HLA to form a novel HLA/HA-βTCP composite. Six New Zealand White rabbits (3.0–3.6 kg) were used as test subjects. Four 6 mm defects were prepared in the parietal bone. The defects were filled with the HLA/HA-βTCP composite as well as HA-βTCP particle alone. New bone formation was analyzed by micro-CT and histomorphometry. Our results indicated that even when the HA-βTCP particle numbers were reduced, the regenerative effect on bone remained when the HLA existed. The bone volume density (BV/TV ratio) of HLA/HA-βTCP samples was 1.7 times larger than that of the control sample at week 2. The new bone increasing ratio (NBIR) of HLA/HA-βTCP samples was 1.78 times higher than the control group at week 2. In conclusion, HA-βTCP powder with HLA contributed to bone healing in rabbit calvarial bone defects. The addition of HLA to bone grafts not only promoted osteoconduction but also improved handling characteristics in clinical situations

Structures of four-way junctions in gene <i>17</i> of T3 and T7.

<p>(A) T3 nt 33324–33353 (B) T3 nt 33317–33347 (C) T7 nt 35109–35139 (D) T7 nt 35082–35117. One strand is highlighted in grey; the other is not. Arrows indicate Endo I cutting sites.</p

Efficiency of plating of phages on <i>E. coli</i> female and male strains determined at 37°C.

<p>Efficiency of plating of phages on <i>E. coli</i> female and male strains determined at 37°C.</p

The mechanism of endonucleolytic cleavages at nonequivalent sites and strand annealing (CNSA).

<p>Colors and arrows are the same as those of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030954#pone-0030954-g005" target="_blank">Figure 5</a>. The steps are: 1, production of DSBs by cutting at nonequivalent sites of T3 and T7 DNA; 2, 5′ resections of DSBs of T3 and T7; 3, annealing of the T3 DSBs with the T7 DSB; 4, removal of the nonhomologous nucleotides, filling the gap, and ligation.</p

Structures of four-way junctions in gene <i>18.5</i> of T3 and T7.

<p>(A) T3 nt 35315–35345 or equivalently T7 nt 37094–37124 (B) T7 nt 37163–37188. One of the strands is highlighted in grey. Endo I cutting sites are shown by arrows.</p

Adsorption efficiency (%) of phages on <i>E. coli</i> female and male strains.

<p>Adsorption efficiency (%) of phages on <i>E. coli</i> female and male strains.</p

Alignment of T3 and T7 sequences near the crossover regions seen in the T3/7 phage.

<p>(A) Within gene <i>17</i>. (B) Within gene <i>18.5</i>. Sequences were aligned by ClustalW. The parent phages of the two sides of the crossover region (shown by arrows) are indicated on top of the alignment.</p

Mapping of the T3/7 and T7M DNA.

<p>The genomic DNA was digested by restriction endonucleases, and the fragments were observed by 1% (T3/7) or 0.8% (T7M) agarose gel electrophoresis. M: DNA marker. (A) Digestions of T3/7 DNA. Lane 1, <i>Mbo</i>I; lane 2, <i>Hpa</i>I; lane 3, <i>Nde</i>I; lane 4, <i>Stu</i>I; lane 5, <i>Avr</i>II. The markers are the same for the three slices of gels. (B) Digestion of T7M DNA. Lane 1, <i>Hpa</i>I. (C) Restriction sites in the T3/7 genome. Restriction sites are represented by vertical bars above the DNA. A: The T3 genome (black) and the region replaced by T7 DNA (in grey) in T3/7. The region of recombination is deduced from restriction mapping and sequencing. The two <i>Mbo</i>I sites in T7 that replace the single <i>Mbo</i>I site at T3 nt 34033 are shown by vertical bars. B to E show restriction sites in T3 genome (black); a dot above the bar indicates that the cutting site is present in T3 but not in T3/7. B: <i>Hpa</i>I sites, C: <i>Mbo</i>I sites, D: <i>Nde</i>I sites, E: <i>Avr</i>II cutting positions are indicated by bars, and the single <i>Stu</i>I site is shown by an arrow.</p