Background: Many historical buildings in Iran need to be protected. In many of these buildings, wood is used as a structural element in features such as beam, pile, roof and floor systems. For this purpose, the architectural features of a historical building located in Gorgan (Northern part of Iran) and characterisation of faults, in addition to identification of wood species were conducted. Stress wave nondestructive testing (NDT) was used and wave speed (WS) was measured in tested members to evaluate the decay situation of major wooden beams of building frames and roof truss. After obtaining data related to WS, time of wave transition (TWT) was calculated and compared with control time. Structural elements were characterized in comparison with control time and classified according to decay severity.
Results:The results showed that local hardwood species were used for construction of this building. Furthermore, in some parts of the building, there were severely defected structures, thus highlighting the importance of safety. Moreover, WS strongly depended on the types of faults.
Conclusion:Due to high relative humidity of climate, wood structures are exposed to faults in the northern region of Iran. However, their general appearance is adequate and acceptable. For better decision making, the TWT should be accompanied by more investigation into the types of defects.
Beet curly top Iran Virus (BCTIV) is a yield-limiting geminivirus belonging to the becurtovirus genus. The genome organization of BCTIV is unique in a way that the complementary strand of BCTIV resembles mastreviruses, whereas the virion strand organization is close to curtoviruses. Geminiviruses are known to avoid the plant defense system by suppressing the RNA interference mechanisms both at the transcriptional gene silencing (TGS) and post-transcriptional gene silencing (PTGS) level. Multiple geminivirus genes have been identified as viral suppressors of RNA silencing (VSR) but the genes underlying VSR activity remain elusive in becurtoviruses. We performed an unbiased screen on each individual BCTIV gene for VSR activity based on three different PTGS experimental setups with transient silencing inducers on stably GFP-expressing Nicotiana benthamiana (16C) and on transiently GFP expressing wild-type Nicotiana benthamiana (WT). We found that only V2 and Rep were able to suppress specific PTGS mechanisms. BCTIV-V2 could suppress S-PTGS more efficiently than BCTIV-Rep when there is transient GFP expression. However, Rep but not V2 could suppress S-PTGS when GFP is only stably expressed by 16C. Furthermore, neither V2 nor Rep could suppress local PTGS induced by inverted repeat targeting GFP (GFP-IR) when GFP is only stably expressed by 16C. Nevertheless, Rep suppressed the systemic silencing induced by GFP-IR in 16C plants. BCTIV-Rep inhibits silencing by mitigating sRNA production, whereas BCTIV-V2 does not alter sRNA, suggesting that Rep and V2 have distinct modes of action. Further characterization of BCTIV-Rep by deletional mutagenesis implicated that multiple domains are required for silencing suppressor activity of Rep. This is the first study revealing the genes responsible for silencing suppression in a becurtovirus and implicating their mode of action.
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