[Molluscicidal activity of the secondary metabolites from Streptomyces nigrogriseolus XD 2-7 against Oncomelania hupensis and its preliminary mechanisms of molluscicidal actions].

OBJECTIVE: To evaluate the storage stability of metabolites from actinomycetes Streptomyces nigrogriseolus XD 2-7 and the mollcuscicidal activity against Oncomelania hupensis in the laboratory, and to preliminarily explore the mechanisms of the molluscicidal activity. METHODS: The fermentation supernatant of S. nigrogriseolus XD 2-7 was prepared and stored at -20, 4 °C and 28 °C without light for 10 d; then, the molluscicidal effect was tested against O. hupensis following immersion for 72 h. The fermentation supernatant was boiled in a 100 °C water bath for 30 min and recovered to room temperature, and then the molluscicidal effect was tested against O. hupensis following immersion for 72 h. The pH values of the fermentation supernatant were adjusted to 4.0, 6.0 and 9.0 with concentrated hydrochloric acid and sodium hydroxide, and the fermentation supernatant was stilled at room temperature for 12 h, with its pH adjusted to 7.0; then, the molluscicidal effect was tested against O. hupensis following immersion for 72 h. The fermentation product of S. nigrogriseolus XD 2-7was isolated and purified four times with macroporous resin, silica gel and octadecylsilane bonded silica gel. The final products were prepared into solutions at concentrations of 10.00, 5.00, 2.50, 1.25 mg/L and 0.63 mg/L, and the molluscicidal effect of the final productswas tested against O. hupensis following immersion for 72 h, while dechlorination water served as blank controls, and 0.10 mg/L niclosamide served as positive control. The adenosine triphosphate (ATP) and adenosine diphosphate (ADP) levels were measured in in O. hupensis soft tissues using high performance liquid chromatography (HPLC) following exposure to the final purified fermentation products of S. nigrogriseolus XD 2-7. RESULTS: After the fermentation supernatant of S. nigrogriseolus XD 2-7 was placed at -20, 4 °C and 28 °C without light for 10 d, immersion in the stock solution and solutions at 10- and 50-fold dilutions for 72 h resulted in a 100% (30/30) O. hupensis mortality. Following boiling at 100 °C for 30 min, immersion in the stock solution and solutions at 10- and 50-fold dilutions for 72 h resulted in a 100.00% (30/30) O. hupensis mortality. Following storage at pH values of 4.0 and 6.0 for 12 h, immersion in the fermentation supernatant of S. nigrogriseolus XD 2-7 for 72 h resulted in a 100.00% (30/30) O. hupensis mortality, and following storage at a pH value of 9.0 for 12 h, immersion in the fermentation supernatant of S. nigrogriseolus XD 2-7 for 72 h resulted in a 33.33% (10/30) O. hupensis mortality (χ2 = 30.000, P < 0.05). The minimum concentration of the final purified fermentation products of S. nigrogriseolus XD 2-7 was 1.25 mg/L for achieving a 100% (30/30) O. hupensis mortality. The ATP level was significantly lower in O. hupensis soft tissues exposed to 0.10 mg/L and 1.00 mg/L of the final purified fermentation products of S. nigrogriseolus XD 2-7 than in controls (F = 7.274, P < 0.05), while no significant difference was detected in the ADP level between the treatment group and controls (F = 2.485, P > 0.05). CONCLUSIONS: The active mollcuscicidal ingredients of the S. nigrogriseolus XD 2-7 metabolites are maintained stably at -20, 4 °C and 28 °C for 10 d, and are heat and acid resistant but not alkali resistant. The metabolites from S. nigrogriseolus XD 2-7 may cause energy metabolism disorders in O. hupensis, leading to O. hupensis death.

Comparison of the Different Preservative Methods for Refractive Lenticules following SMILE.

Purposes: To (i) evaluate various methods for preserving refractive lenticules (RLs) from myopic eyes following small-incision lenticule extraction (SMILE), in order to (ii) establish a sound, standard storage RL preservative for clinical uses. Methods: In this prospective study, we compared freshly excised post-SMILE RLs (control group) with post-SMILE RLs (experimental group). Experimental group RLs were preserved in one of several preservatives: glycerol, allochroic silicagel desiccant, or Optisol. Following preservation in one of these three media, samples were evaluated by light microscopy (LM), and transmission (TEM) and scanning (SEM) electron microscopy on days-1, -3, -7, and -14. Results: Changes in cellular morphology were observed at all time points. Compared with fresh control-group RLs, there were significant histological changes in RLs preserved in glycerol and allochroic silicagel, but not Optisol. Comparison of the three methods revealed Optisol to be the best, followed by allochroic silica gel desiccant, followed by glycerol. RLs preserved in Optisol maintained the highest degree of viability and integrity. And the RLs viability and collagen density decreased with prolongation of storage time all. Conclusions: Optisol is a midterm corneal storage medium, which can maintain post-SMILE corneal RLs for 14 days, is a feasible and effective method for tissue storage.

Insecticidal efficacy of silica gel with Juniperus oxycedrus ssp. oxycedrus (Pinales: Cupressaceae) essential oil against Sitophilus oryzae (Coleoptera: Curculionidae) and Tribolium confusum (Coleoptera: Tenebrionidae).

Laboratory bioassays were carried out to evaluate the effect of silica gel enhanced with the essential oil (EO) of Juniperus oxycedrus L. ssp. oxycedrus (Pinales: Cupressaceae) (derived from berry specimens from Greece) against adults of Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae). For that purpose, a dry mixture consisting of 500 mg of silica gel that had absorbed 2.18 mg of EO (total weight: 502.18 mg) was tested at three doses; 0.125, 0.250, and 0.5 g/kg of wheat, corresponding to 125, 250, and 500 ppm, respectively, and silica gel alone at 0.5 g/kg of wheat corresponding to 500 ppm, at different exposure intervals (24 and 48 h and 7 and 14 d for S. oryzae; 24 and 48 h and 7, 14, and 21 d for T. confusum). The chemical content of the specific EO was determined by gas chromatography (GC)-mass spectrometry (MS) analyses indicating the presence of 31 constituents with myrcene and germacrene-D being the predominant compounds. The bioactivity results for S. oryzae indicated that 48 h of exposure in wheat resulted in an 82% mortality for treatment with 500 ppm of the enhanced silica gel. For 7 d of exposure, 100 and 98% of S. oryzae adults died when they were treated with 500 and 250 ppm of enhanced silica gel, respectively. At 14 d of exposure, all adults died both at 250 and 500 ppm of enhanced silica gel. At 48 h, 7 and 14 d of exposure significantly less S. oryzae adults died in wheat treated with silica gel alone than at 250 or 500 ppm of enhanced silica gel. In the case of T. confusum, at 7 d of exposure, mortality in wheat treated with silica gel only was significantly higher in comparison to the other treatments. At the 14 d of exposure mortality in wheat treated with 500 ppm of silica gel alone was significantly higher than 125 and 250 ppm of the enhanced silica gel. Similar trends were also noted at 21 d of exposure, indicating that there is no enhancement effect from the addition of the EO. Results herein suggest that the simultaneous use of silica gel and J. oxycedrus ssp. oxycedrus EO enhances significantly its activity against S. oryzae.

Preparation and complex characterization of silica holmium sol-gel monoliths.

Amorphous, sol-gel derived SiO(2) are known to biocompatible and bioresorbable materials. Biodegradable and inert materials containing radioactive isotopes have potential application as delivery vehicles of the beta radiation to the cancer tumors inside the body. Incorporation of holmium in the sol-gel derived SiO(2) could lead to the formation of a biodegradable material which could be used as carrier biomaterial for the radiation of radioactive holmium to the various cancer sites. The homogeneity of the prepared sol-gel silica holmium monoliths was investigated by Back Scattered Electron Imaging of Scanning Electron Microscope equipped with Energy Dispersive X-ray Analysis, X-ray Induced Photoelectron Spectroscopy and Nuclear Magnetic Resonance Spectroscopy. The biodegradation of the monoliths was investigated in Simulated Body Fluid and TRIS (Trizma pre-set Crystals) solution. The results show that by suitable tailoring of the sol-gel processing parameters holmium can be homogeneously incorporated in the silica matrix with a controlled biodegradation rate.