Histone deacetylase HD2 interacts with ERF1 and is involved in longan fruit senescence

Histone deacetylation plays an important role in epigenetic control of gene expression. HD2 is a plant-specific histone deacetylase that is able to mediate transcriptional repression in many biological processes. To investigate the epigenetic and transcriptional mechanisms of longan fruit senescence, one histone deacetylase 2-like gene, DlHD2, and two ethylene-responsive factor-like genes, DlERF1 and DlERF2, were cloned and characterized from longan fruit. Expression of these genes was examined during fruit senescence under different storage conditions. The accumulation of DlHD2 reached a peak at 2 d and 30 d in the fruit stored at 25 °C (room temperature) and 4 °C (low temperature), respectively, or 6 h after the fruit was transferred from 4 °C to 25 °C, when fruit senescence was initiated. However, the DlERF1 transcript accumulated mostly at the later stage of fruit senescence, reaching a peak at 5 d and 35 d in the fruit stored at 25 °C and 4 °C, respectively, or 36 h after the fruit was transferred from low temperature to room temperature. Moreover, application of nitric oxide (NO) delayed fruit senescence, enhanced the expression of DlHD2, but suppressed the expression of DlERF1 and DlERF2. These results indicated a possible interaction between DlHD2 and DlERFs in regulating longan fruit senescence, and the direct interaction between DlHD2 and DlERF1 was confirmed by yeast two-hybrid and bimolecular fluorescence complementation (BiFC) assays. Taken together, the results suggested that DlHD2 may act with DlERF1 to regulate gene expression involved in longan fruit senescence

An atlas of over 90.000 conserved noncoding sequences provides insight into crucifer regulatory regions

Despite the central importance of noncoding DNA to gene regulation and evolution, understanding of the extent of selection on plant noncoding DNA remains limited compared to that of other organisms. Here we report sequencing of genomes from three Brassicaceae species (Leavenworthia alabamica, Sisymbrium irio and Aethionema arabicum) and their joint analysis with six previously sequenced crucifer genomes. Conservation across orthologous bases suggests that at least 17% of the Arabidopsis thaliana genome is under selection, with nearly one-quarter of the sequence under selection lying outside of coding regions. Much of this sequence can be localized to approximately 90,000 conserved noncoding sequences (CNSs) that show evidence of transcriptional and post-transcriptional regulation. Population genomics analyses of two crucifer species, A. thaliana and Capsella grandiflora, confirm that most of the identified CNSs are evolving under medium to strong purifying selection. Overall, these CNSs highlight both similarities and several key differences between the regulatory DNA of plants and other species

Susceptibility of two cambodian population of Aedes aegypti mosquito larvae to temephos during 2001

Two population of Aedes aegypti, i.e Phnom Penh (temephos-treated area) and Kampong Cham (area untreated with temephos) were evaluated for their susceptibility to temephos. Larval bioassays were carried out in accordance with QHO standard methods. Results showed that, when compared with the WHO diagnostic dosage of 0.02 mg/l, the Phnom Penh population was resistant (LC95: 0.034mg/l) whereas that of Kampong Cham was susceptible (LC95: 0.015mg/l). 95% confidence intervals of 0.0298 - 0.0382 and 0.0115 - 0.0193, respectively, did not overlap, indicating that the difference in susceptibility between thw two populations was significant. Resistant of Ae. aegypti to temephos appears to be incipient in Camboida. More studies are reuqired with wider representations of localities

The use of ovitraps baited with hay infusion as a surveillance tool for Aedes aegypti mosquitoes in Cambodia

This study was conducted to test (a) if a modified version of the CDC-enhanced would attract more gravid female Aedes aegypti mosquitoes than standard ovitraps for more frequent monitoring of oviposition activity, and (b) the placement of ovitraps indoors or outdoors affected their performance. Paired ovitraps were placed in 25 strategically houses in Toul Kouk, a village on the outskirts of Phnom Penh, Cambodia's capital city. Each pair consisted of one ovitrap with 10% hay infusion and the other with plain tap water, one pair placed inside each house and the other outside the same house. Collections were made every other day for four weeks. The number of positive ovitraps was recorded and egg counts made. Thirteen collections made over a 4-week period yielded a total of 7758 eggs, of which 5396 were collected in ovitraps with hay infusion. Ovitraps with hay infusion had a higher positivity (weekly range 15.56-54.55%) than ovitraps with plain water (weekly range 6.67 - 34.88%) (t = 4.92; df 12; p 0.5 and t = 0.06; df 12; p >0.5, respectively) or for plain water traps (t= 1.97; df 12; 0.05 < p < 0.1 and t = 1.03; df 12; 0.2 < p < 0.5, respectively). Overall results indicate that, in the study site (a) hay infusion-baited ovitraps are a more sensitive indicator of the presence and numbers of Aedes aegypti than those with plain water and are suitable for frequent monitoring of Aedes aegypti oviposition activity, and (b) the location of ovitraps, indoors or outdoors, does not influence the performance of the traps