Horizontal maps of echo power in the lower stratosphere using the MU radar

International audienceIn recent works, zenithal and azimuthal angle variations of echo power measured by VHF Stratosphere-Troposphere (ST) radars have been analyzed in detail using different radar multi-beam configurations. It was found that the azimuthal angle corresponding to maximum echo power is closely related to the direction of the horizontal wind shear. These properties indicate that local wind shear affects the tilt of the scatterers. Moreover, horizontal maps of echo power collected using a large set of beams steered pulse-to-pulse up to 40 degrees off zenith revealed that the power distribution pattern in the troposphere is often skewed. In this work, a three-dimensional description of echo power variations up to 24 degrees off zenith is shown for measurements in the lower stratosphere (i.e. up to approximately 20km) using a "sequential multi-beam" (SMB) configuration. Such a description was not possible above the tropopause with classical multi-beam configurations because of the loss of radar sensitivity due to the limited integration time by the use of a large number of beams. This work attempts to complete previous descriptions of the phenomenon by some observations in the lower stratosphere discussed in association with complementary balloon measurements. Key words. Meteorology and atmospheric dynamics (turbulence) – Radio Science (remote sensing

An oral delivery system for controlling white spot syndrome virus infection in shrimp using transgenic microalgae

White spot disease (WSD) is a longstanding and serious viral disease of various shrimp species that has caused high mortality rates for many decades. Currently, there is no practical method to control this disease. Therefore, we have explored the development of a novel vaccine-based method to control this disease using transgenic algae. During infection by white spot syndrome virus (WSSV), the interaction between viral envelope proteins and cell surface protein receptors on target cells is the key step of viral entry and replication. Hence, transgenic lines of the green microalga Chlamydomonas reinhardtii harbouring a WSSV VP28 viral envelope protein were created as an oral delivery system for vaccinating shrimp. Two separate transplastomic lines containing wild-type and codon optimized gene sequences for VP28 were evaluated for recombinant protein levels. Only the codon optimized line gave rise to detectable VP28 in western blot analysis, which demonstrated that optimization for chloroplast codon bias improved the efficiency of expression and that the gene design produced a favourable RNA secondary structure with suitable free energy for translation. In addition, bile salt and acid tolerance tests demonstrated that this transgenic Chlamydomonas can tolerate mildly acidic (pH 5.0) conditions and 0.30% bile salts. These features indicated that algal cells are suitable for delivering viral antigens through a shrimp's digestive system. In WSSV infection experiments, the highest survival rate (87%) was recorded in shrimps fed with the codon optimized VP28 line mixed into their feed, indicating that this line could be employed in the control of WSSV spread in shrimp populations. This algal strategy offers a new, efficient, fast and less labour-intensive method for the control of other diseases in aquatic animals through oral delivery

Characterization of Promoter Activities of Four Different Japanese Flounder Promoters in Transgenic Zebrafish

An important consideration in transgenic research is the choice of promoter for regulating the expression of a foreign gene. In this study several tissue-specific and inducible promoters derived from Japanese flounder Paralichthys olivaceus were identified, and their promoter activity was examined in transgenic zebrafish. The 5′ flanking regions of the Japanese flounder complement component C3, gelatinase B, keratin, and tumor necrosis factor (TNF) genes were linked to green fluorescence protein (GFP) as a reporter gene. The promoter regulatory constructs were introduced into fertilized zebrafish eggs. As a result we obtained several stable transgenic zebrafish that displayed green fluorescence in different tissues. Complement component C3 promoter regulated GFP expression in liver, and gelatinase B promoter regulated it in the pectoral fin and gills. Keratin promoter regulated GFP expression in skin and liver. TNF gene promoter regulated GFP expression in the pharynx and heart. TNF promoter had lipoplysaccharide-inducible activity, such that when transgenic embryos were immersed lipopolysaccharide, GFP expression increased in the epithelial tissues. These 4 promoters regulated the expression of GFP in different patterns in transgenic zebrafish