Post-Synthetic Reduction of Pectin Methylesterification Causes Morphological Abnormalities and Alterations to Stress Response in Arabidopsis thaliana.

Pectin is a critical component of the plant cell wall, supporting wall biomechanics and contributing to cell wall signaling in response to stress. The plant cell carefully regulates pectin methylesterification with endogenous pectin methylesterases (PMEs) and their inhibitors (PMEIs) to promote growth and protect against pathogens. We expressed Aspergillus nidulans pectin methylesterase (AnPME) in Arabidopsis thaliana plants to determine the impacts of methylesterification status on pectin function. Plants expressing AnPME had a roughly 50% reduction in methylester content compared with control plants. AnPME plants displayed a severe dwarf phenotype, including small, bushy rosettes and shorter roots. This phenotype was caused by a reduction in cell elongation. Cell wall composition was altered in AnPME plants, with significantly more arabinose and significantly less galacturonic acid, suggesting that plants actively monitor and compensate for altered pectin content. Cell walls of AnPME plants were more readily degraded by polygalacturonase (PG) alone but were less susceptible to treatment with a mixture of PG and PME. AnPME plants were insensitive to osmotic stress, and their susceptibility to Botrytis cinerea was comparable to wild type plants despite their compromised cell walls. This is likely due to upregulated expression of defense response genes observed in AnPME plants. These results demonstrate the importance of pectin in both normal growth and development, and in response to biotic and abiotic stresses.

Vertical Infestation Profile of Aedes in Selected Urban High-Rise Residences in Malaysia.

Dengue is placing huge burdens on the Malaysian healthcare system as well as the economy. With the expansion in the number of high-rise residential buildings, particularly in the urban centers, the flight range and behavior of Aedes mosquitoes may be altered in this habitat type. In this study, we aimed to expand the understanding of the vertical distribution and dispersal of Aedes in nine selected high-rise residences in Kuala Lumpur, Selangor, and Johor using ovitraps as the sampling method. We discovered that Ae. aegypti is the predominant species in all study sites. Both Ae. aegypti and Ae. albopictus are most abundant within the first three levels and could be found up to level 21 (approximately 61.1-63.0 m). Pearson correlation analyses exhibited negative correlations in eight out of nine study sites between the ovitrap indexes (OIs) within each floor level, suggesting that Aedes density decreased as the building level increased. Our findings provide information to the public health authorities on 'hot spot' floors for effective suppression of dengue transmission.

Semi-field evaluation of the bio-efficacy of two different deltamethrin formulations against Aedes species in an outdoor residual spraying study.

In recent decades, dengue incidence has trended upward worldwide causing urgent needs for new or modified vector control methods. We modified the existing indoor residual spraying (IRS) method by applying insecticide on the outer walls of building structures in an outdoor residual spraying (ORS) study. A semi-field study was conducted to investigate the bio-efficacy of two different deltamethrin formulations: K-Othrine® Polyzone, new polymer-enhanced deltamethrin formulated as a suspension concentrate (SC-PE), and K-Othrine® WG 250, traditional deltamethrin formulated as water dispersible granule (WG). The residual bio-efficacy of deltamethrin SC-PE was compared to deltamethrin WG on finished cement surfaces applied to the outer walls at the Institute for Medical Research (IMR), Malaysia. Standard WHO cone wall bioassays were adapted to evaluate the effective duration of action of these deltamethrin formulations against susceptible laboratory-reared and wild, free-flying Aedes aegypti and Ae. albopictus. Analyses of bioassay results showed that deltamethrin SC-PE 30 mg/m2 has improved longevity in comparison to deltamethrin WG 30 mg/m2. Deltamethrin SC-PE 30 mg/m2 was effective until week 17 (producing > 80% mortality), surpassing deltamethrin WG 30 mg/m2 which only lasted until week 10. This was supported by post-hoc test analyses which demonstrated that deltamethrin SC-PE 30 mg/m2 produced the highest mean of mortality in laboratory-reared Aedes species and the wild Ae. albopictus. However, the effective duration of action of deltamethrin SC-PE (17 weeks) was less than the recommended period by WHO (6 months) but was reasonable given that the spraying was undertaken outdoor. This preliminary data could be of use for the deployment of locally adapted ORS operation in controlling dengue.