RESUMEN
A 278-bp region upstream of the beet curly top virus-SpCT (BCTV-SpCT) C2/C3 genes is necessary for promoter activity and exhibits significant sequence similarity to AL2/3 promoter sequences in tomato golden mosaic virus (TGMV). Maximal expression of the downstream C2/3 genes in BCTV-SpCT requires the presence of the C1 protein, which is supported by observations that mutation of the initiator codon for C1 results in decreased C2/C3 expression. This is similar to TGMV and cabbage leaf curl virus, where AL1 is required for maximal AL2/3 expression. Together, these data suggest a common strategy for complementary-sense gene regulation amongst curtoviruses and begomoviruses.
Asunto(s)
Begomovirus/genética , Geminiviridae/genética , Regulación Viral de la Expresión Génica/genética , Begomovirus/metabolismo , Sitios de Unión/genética , Geminiviridae/metabolismo , Regiones Promotoras Genéticas/genética , Proteínas Virales/genéticaRESUMEN
Conventional activated-sludge (AS) technologies are deficient for nutrient removal because they require specific floc characteristics. Therefore, the encapsulated AS with polyvinyl alcohol (PVA) will favor floc's formation that removes nutrients. The applied method was based on monitoring the removal of organic matter and nutrients (NH4+, NO3-, NO2-, PO43-) from synthetic domestic wastewater using laboratory-scale AS. The experimental reactors were operated at 8 h as optimized Hydraulic Retention Time (HRT). The sludge characteristics evaluation was carried out through the Sludge Volumetric Index (SVI), Food/Microorganism ratio (F/M), and Mixed Liquor Volatile Suspended Solids (MLVSS). Other specific floc characteristics, such as zeta potential and effective diameter were also evaluated. The results showed that the encapsulated AS with PVA favors nitrogen and phosphorous removal up to 35% but it did not improve organic matter removal. In addition, encapsulated AS with PVA has the characteristics of filamentous sludge (F/M: 0.7 g COD g-1 MLVSS d-1) with good settleability conditions (SVI: 43 mL g-1 MLSVS h-1) and low zeta potential (ZP: -0.9 mV), which favors its separation from the liquid phase. In conclusion, the encapsulation of AS with PVA improves nutrient removal by improving floc characteristics.