Evidence of Efficient Transovarial Transmission of Culex Flavivirus by Culex pipiens (Diptera: Culicidae)

This study determined the transovarial transmission (TOT) potential and tissue tropisms of Culex flavivirus (CxFV), an insect-specific flavivirus, in Culex pipiens (L.). Several hundred mosquito egg rafts were collected in the field, transferred to the insectaries, reared to the fourth larval instar, and identified using morphological characteristics. Cx. pipiens were reared to adults, allowed to oviposit in individual containers, and tested for CxFV RNA by reverse transcription-polymerase chain reaction (RT-PCR) and nucleotide sequencing. Eighteen CxFV RNA-positive females were identified from 26 females that oviposited viable egg rafts. Thirty F1 adults from each positive female were individually tested by RT-PCR for CxFV RNA. Viral RNA was detected in 526 of 540 progeny, and thus, the filial infection rate was 97.4%. Because all 18 positive females produced infected offspring, the TOT prevalence was 100%. These data indicated that efficient TOT of CxFV occurs in nature. To define the tissue tropisms of CxFV, different tissues (salivary glands, ovaries, testes, head, fat bodies, and midguts) were removed from the remainder of the F1 and tested by RT-PCR for CxFV RNA. Viral RNA was detected in all tissues. Additionally, uninfected laboratory-colonized Cx. pipiens were infected with CxFV by needle inoculation, and ovaries were collected at 4, 6, 8, and 12 d postinoculation and tested for CxFV RNA by RT-PCR. Viral RNA was detected at all time points, demonstrating that CxFV infects the ovaries as early as 4 d postinoculation. Surprisingly, however, we were unable to demonstrate transovarial transmission despite the presence of viral RNA in the ovaries. Nevertheless, the experiments performed with field-infected Cx. pipiens demonstrate that TOT is an efficient mechanism by which CxFV is maintained in mosquitoes in nature

Structure and nonlinear optical studies of Au nanoparticles embedded in lead lanthanum borate glass

Metal nanoparticles of gold in various proportions were prepared by melt-quenching technique without any assistance of reducing agent. X-ray absorption near edge structure analysis shows that measurements at the Au L3 edge were made on lanthanum lead borate doped with gold. X-ray absorption near edge structure shows that the oxidation state of Au and the analysis show the presence of gold nanoparticles. Electron microscopy and energy dispersive absorption X-ray spectroscopy confirm the size of Au nanoparticle inside the lead lanthanum borate glass. Nonlinear optical studies of Au doped oxide glass are performed using nanosecond laser pulse excitation. Z-scan experiments with 532 nm wave-length pulses are used to excite glass samples which show that optical limiting effect of these as-prepared glasses doped with Au nanoparticle was also studied. © 2014 Elsevier B.V. All rights reserved