Preparation and Characterization of a Silk Fibroin/Polyurethane Fiber Blend Membrane Containing Actinomycin X2 with Excellent Mechanical Properties and Enhanced Antibacterial Activities.

Development of suitable antimicrobial biomaterials for hygienic wound dressing and healing is an important requirement for medical application. Durable mechanical properties increase the application range of biomaterial in different environmental and biological conditions. Due to the inherent brittleness of silk fibroin (SF), polyurethane fiber (PUF) was used to modify SF containing actinomycin X2 (Ac.X2) to prepare silk fibroin@actinomycin X2 /polyurethane fiber (ASF/PUF) blend membranes. The ASF/PUF blend membrane was developed by solution casting method. Incorporation of PUF improved the flexibility of material and introduction of Ac.X2 has increased antibacterial activity of materials. Excellent mechanical properties (tensile strength up to 25.7 MPa and elongation at break up to 946.5 %) of 50 % SF+50 % PUF blend membrane were proved by tensile testing machine. FT-IR spectra, TGA, contact angle and DMA were tested to prove the blend membrane's physico-chemical characteristics. ASF/PUF blend membrane displayed satisfactory antibacterial activity against S. aureus, and the cytotoxicity tests showed that the blend membrane has better biosafety compared to directly applied Ac.X2 in soluble form. These results suggest that the modification of SF through PUF for development of flexible antibacterial membranes has great potential application value in the field of silk-like material fabrication.

Actinomycin-X2-Immobilized Silk Fibroin Film with Enhanced Antimicrobial and Wound Healing Activities.

Actinomycin is a family of chromogenic lactone peptides that differ in their peptide portions of the molecule. An antimicrobial peptide, actinomycin X2 (Ac.X2), was produced through the fermentation of a Streptomyces cyaneofuscatus strain. Immobilization of Ac.X2 onto a prepared silk fibroin (SF) film was done through a carbodiimide reaction. The physical properties of immobilized Ac.X2 (antimicrobial films, AMFs) were analyzed by ATR-FTIR, SEM, AFM, and WCA. The findings from an in vitro study showed that AMFs had a more broad-spectrum antibacterial activity against both S. aureus and E. coli compared with free Ac.X2, which showed no apparent strong effect against E. coli. These AMFs showed a suitable degradation rate, good hemocompatibility, and reduced cytotoxicity in the biocompatibility assay. The results of in vivo bacterially infected wound healing experiments indicated that wound inflammation was prevented by AMFs, which promoted wound repair and improved the wound microenvironment. This study revealed that Ac.X2 transformation is a potential candidate for skin wound healing.

Actinomycin X2, an Antimicrobial Depsipeptide from Marine-Derived Streptomyces cyaneofuscatus Applied as a Good Natural Dye for Silk Fabric.

Actinomycins as clinical medicine have been extensively studied, while few investigations were conducted to discover the feasibility of actinomycins as antimicrobial natural dye contributing to the medical value of the functional fabrics. This study was focused on the application of actinomycin X2 (Ac.X2), a peptide pigment cultured from marine-derived Streptomyces cyaneofuscatus, in the dyeing and finishing of silk fabric. The dyeing potential of Ac.X2 with silk vs. cotton fabrics was assessed. As a result, the silk fabric exhibited greater uptake and color fastness with Ac.X2. Through Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses, some changes of chemical property for the dyed fabric and Ac.X2 were studied. The silk fabric dyed with Ac.X2 exhibited good UV protection ability. The antibacterial properties of dyed and finished silk were also evaluated, which exhibited over 90% antibacterial activity even after 20 washing cycles. In addition, the brine shrimp assay was conducted to evaluate the general toxicity of the tested fabric, and the results indicated that the dyed silk fabrics had a good biological safety property.

Chemical and Biological Study of Novel Aplysiatoxin Derivatives from the Marine Cyanobacterium Lyngbya sp.

Since 1970s, aplysiatoxins (ATXs), a class of biologically active dermatoxins, were identified from the marine mollusk Stylocheilus longicauda, whilst further research indicated that ATXs were originally metabolized by cyanobacteria. So far, there have been 45 aplysiatoxin derivatives discovered from marine cyanobacteria with various geographies. Recently, we isolated two neo-debromoaplysiatoxins, neo-debromoaplysiatoxin G (1) and neo-debromoaplysiatoxin H (2) from the cyanobacterium Lyngbya sp. collected from the South China Sea. The freeze-dried cyanobacterium was extracted with liquid-liquid extraction of organic solvents, and then was subjected to multiple chromatographies to yield neo-debromoaplysiatoxin G (1) (3.6 mg) and neo-debromoaplysiatoxin H (2) (4.3 mg). They were elucidated with spectroscopic methods. Moreover, the brine shrimp toxicity of the aplysiatoxin derivatives representing differential structural classifications indicated that the debromoaplysiatoxin was the most toxic compound (half inhibitory concentration (IC50) value = 0.34 ± 0.036 µM). While neo-aplysiatoxins (neo-ATXs) did not exhibit apparent brine shrimp toxicity, but showed potent blocking action against potassium channel Kv1.5, likewise, compounds 1 and 2 with IC50 values of 1.79 ± 0.22 µM and 1.46 ± 0.14 µM, respectively. Therefore, much of the current knowledge suggests the ATXs with different structure modifications may modulate multiple cellular signaling processes in animal systems leading to the harmful effects on public health.

Interactive effect of nitrogen source and high CO2 concentration on the growth of the dinoflagellate Alexandrium tamarense and its toxicity to zebrafish (Danio rerio) embryos.

The effects and interactive effects of different nitrogen (N) sources (ammonium, nitrate, and urea) and carbon dioxide (CO2) concentrations were investigated on Alexandrium tamarense, a harmful marine dinoflagellate, by measuring its growth (µ), extracellular carbonic anhydrase (CA), and its toxicity to zebrafish (Danio rerio) embryo. The µ and CA were influenced more strongly by CO2 concentrations rather than by N sources; significant effects of CO2 on µ and CA were observed under low CO2 concentration (LC) conditions compared to high CO2 concentration (HC) conditions. The ammonium and nitrate media under LC conditions had the maximum µ and CA, which was inhibited under HC conditions. The embryotoxic effects were influenced more strongly by the N sources than by CO2 concentrations, thus excluding the lower deformation in urea under HC conditions. Moreover, the antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione S-transferase (GST), and catalase (CAT) were detected in normal (untreated) zebrafish embryos, and among them, the level of SOD was the highest. In summary, this study provides a clear insight for understanding the effects and interactive effects of N sources and CO2 concentrations on the growth and toxicity of harmful dinoflagellates.

The dinoflagellate Akashiwo sanguinea will benefit from future climate change: The interactive effects of ocean acidification, warming and high irradiance on photophysiology and hemolytic activity.

Due to global climate change, marine phytoplankton will likely experience low pH (ocean acidification), high temperatures and high irradiance in the future. Here, this work report the results of a batch culture experiment conducted to study the interactive effects of elevated CO2, increased temperature and high irradiance on the harmful dinoflagellate Akashiwo sanguinea, isolated at Dongtou Island, Eastern China Sea. The A. sanguinea cells were acclimated in high CO2 condition for about three months before testing the responses of cells to a full factorial matrix experimentation during a 7-day period. This study measured the variation in physiological parameters and hemolytic activity in 8 treatments, representing full factorial combinations of 2 levels each of exposure to CO2 (400 and 1000µatm), temperature (20 and 28°C) and irradiance (50 and 200µmol photons m-2s-1). Sustained growth of A. sanguinea occurred in all treatments, but high CO2 (HC) stimulated faster growth than low CO2 (LC). The pigments (chlorophyll a and carotenoid) decreased in all HC treatments. The quantum yield (Fv/Fm) declined slightly in all high-temperature (HT) treatments. High irradiance (HL) induced the accumulation of ultraviolet-absorbing compounds (UVabc) irrespective of temperature and CO2. The hemolytic activity in the LC treatments, however, declined when exposed to HT and HL, but HC alleviated the adverse effects of HT and HL on hemolytic activity. All HC and HL conditions and the combinations of high temperature*high light (HTHL) and high CO2*high temperature*high light (HCHTHL) positively affected the growth in comparison to the low CO2*low temperature*low light (LCLTLL) treatment. High temperature (HT), high light (HL) and a combination of HT*HL, however, negatively impacted hemolytic activity. CO2 was the main factor that affected the growth and hemolytic activity. There were no significant interactive effects of CO2*temperature*irradiance on growth, pigment, Fv/Fm or hemolytic activity, but there were effects on Pm, α, and Ek. If these results are extrapolated to the natural environment, it can be hypothesized that A. sanguinea cells will benefit from the combination of ocean acidification, warming, and high irradiance that are likely to occur under future climate change. It is assumed that faster growth and higher hemolytic activity and UVabc of this species will occur under future conditions compared with those the current CO2 (400µatm) and temperature (20°C) conditions.

Complete mitochondrial genome and the phylogenetic position of the Borneo leg skate Sinobatis borneensis (Rajiformes: Anacanthobatidae).

In this study, the complete mitochondrial genome of the Borneo leg skate Sinobatis borneensis (Rajiformes, Anacanthobatidae) was determined. It had circular molecules (16,701 bp), consisting of 37 genes with a typical gene order in vertebrate mitogenome. In the whole mitogenome, there were 28 bp short intergenic and 31 bp overlaps, respectively, located in 12 and 7 gene junctions. The nucleotide composition was 31.1% A, 26.0% C, 13.9% G and 29.1% T. Two start codons (GTG and ATG) and two stop codons (TAG, TAA/T) were used in the protein-coding genes. The 22 tRNA genes ranged from 66 bp (tRNA-Cys) to 75 bp (tRNA-Leu1 and tRNA-Lys). The phylogenetic result showed that S. borneensis was clustered with the Atlantoraja castelnaui and Pavoraja nitida.

Complete mitochondrial genome and the phylogenetic position of the Leadhued skate Notoraja tobitukai (Rajiformes: Arhynchobatidae).

In this study, the complete mitochondrial genome of the Leadhued skate Notoraja tobitukai (Rajiformes: Arhynchobatidae) was determined. It was a circular molecule (16, 799 bp), consisted of 37 genes with a typical gene order in vertebrate mitogenome. In the whole mitogenome, there were 24 bp short intergenic and 26 bp overlaps. The nucleotide composition was 32.3% A, 22.6% C, 13.1% G and 32.0% T. Two start codons (GTG and ATG) and two stop codons (TAG, TAA/T--) were used in the protein-coding genes. The 22 tRNA genes ranged from 65 bp (tRNA-Cys) to 75 bp (tRNA-Leu1). The phylogenetic result showed that N. tobitukai was clustered with the Pavoraja nitida.

The phylogenomic position of the smalleye whip ray Himantura microphthalma (Myliobatiformes: Dasyatidae) inferred from the mitochondrial genome.

In this study, the complete mitochondrial genome of the smalleye whip ray Himantura microphthalma was first determined. The total length of the complete mitogenome is 17,636 bp, consisted of 37 genes with a typical gene order in vertebrate mitogenome. A total of 63 bp short intergenic spaces and 25 bp overlaps were found between 17 and 6 gene junctions. The overall base composition is 31.2% A, 29.2% T, 26.4% C, and 13.2% G. Two start codons (GTG and ATG) as well as two stop codons (TAG and TAA/T) were used in protein-coding genes. The phylogenetic result suggests that H. microphthalma should be assigned to the genus Dasyatis.

Complete mitochondrial genome and the phylogenetic position of the Leadhued skate Notoraja tobitukai (Rajiformes: Arhynchobatidae).

In this study, the complete mitochondrial genome of the Leadhued skate Notoraja tobitukai (Rajiformes: Arhynchobatidae) was determined. It was a circle molecular (16, 799 bp), consisted of 37 genes with a typical gene order in vertebrate mitogenome. In the whole mitogenome, there were 24 bp short intergenic and 26 bp overlaps. The nucleotide composition was 32.3% A, 22.6% C, 13.1% G and 32.0% T. Two start codons (GTG and ATG) and two stop codons (TAG, TAA/T) were used in the protein-coding genes. The 22 tRNA genes ranged from 65 bp (tRNA-Cys) to 75 bp (tRNA-Leu1). The phylogenetic result showed that N. tobitukai was clustered with the Pavoraja nitida.

Complete mitochondrial genome and the phylogenetic position of the graceful catshark Proscyllium habereri (Carcharhiniformes: Proscylliidae).

In this study, the complete mitogenome of Proscyllium habereri (Carcharhiniformes: Proscylliidae) is first determined. It is 16,708 bp in length, containing 37 genes with typical order to that of most other vertebrates. Its overall base composition of the H-strand is A 30.9%; C 23.7%; G 14.2%; T 31.2%. Two start codons (ATG and GTG) and two stop codons (TAG and TAA/T) are found in the protein-coding genes. The 22 tRNA genes range from 67 bp (tRNA-Cys, tRNA-Ser2) to 75 bp (tRNA-Leu1). The phylogenetic result showed that P. habereri was clustered to Pseudotriakis microdon.

Complete mitochondrial genome and the phylogenetic position of the Bowmouth guitarfish Rhina ancylostoma (Rajiformes, Rhinobatidae).

In this study, the complete mitochondrial genome of the Bowmouth guitarfish Rhina ancylostoma (Rajiformes, Rhinobatidae) was first determined. The total length of this circle DNA was 17 217 bp, consisted of 37 genes with a typical gene order in vertebrate mitogenome. It had 42 bp short intergenic spaces and 40 bp overlaps. The nucleotide composition in R. ancylostoma was as follows: A, 33.0%; C, 25.1%; G, 12.6% and T, 29.3%. Two start codons (GTG and ATG) and two stop codons (TAG and TAA/T) were used in the protein-coding genes. The 22 tRNA genes were ranged from 67 bp (tRNA-Ser2) to 75 bp (tRNA-Leu1). The phylogenetic result showed that R. ancylostoma was clustered with the Rhinobatos.

Complete mitochondrial genome and the phylogenetic position of the Jenkins whipray Himantura jenkinsii (Myliobatiformes, Dasyatidae).

We determined the complete mitochondrial genome of the Jenkins whipray Himantura jenkinsii. The total length of the mitogenome was 17, 670 bp, consisted of 37 genes with typical gene order in vertebrate mitogenome. The nucleotide composition was: 30.5% A, 29.1% T, 26.5% C and 13.9% G. It had 70 bp short intergenic spaces and 22 bp overlaps. Two start codons (GTG and ATG) and two stop codons (TAG and TAA/T) were used in the protein-coding genes. The 22 tRNA genes were ranged from 67 bp (tRNA-Ser2) to 75 bp (tRNA-Leu1). The phylogenetic result showed that H. jenkinsii was clustered with the Hortle's whipray H. hortlei.

Complete mitochondrial genome and the phylogenetic position of the White-spotted guitarfish Rhynchobatus australiae (Rajiformes, Rhinobatidae).

We first determined the complete mitochondrial genome of the White-spotted guitarfish Rhynchobatus australiae (Rajiformes, Rhinobatidae). The complete mitogenome was 16,804 bp, with a base composition of 32.3% A, 27.5% T, 26.9% C and 13.3% G, containing 13 protein-coding genes, two rRNAs, 22 tRNAs and a control region (D-loop). It had 35 bp short intergenic spaces and 39 bp overlaps between genes. The gene order and composition of R. australiae was similar to most other fishes. The codon usage followed the typical vertebrate mitochondrial pattern (ATG or GTG for start codon and TAA or T for stop codon). The phylogenetic result showed that R. australiae was clustered with the Rhinobatos.