The CBF gene family in hexaploid wheat and its relationship to the phylogenetic complexity of cereal CBFs

Most temperate plants tolerate both chilling and freezing temperatures whereas many species from tropical regions suffer chilling injury when exposed to temperatures slightly above freezing. Cold acclimation induces the expression of cold-regulated genes needed to protect plants against freezing stress. This induction is mediated, in part, by the CBF transcription factor family. To understand the evolution and function of this family in cereals, we identified and characterized 15 different CBF genes from hexaploid wheat. Our analyses reveal that wheat species, T. aestivum and T. monococcum, may contain up to 25 different CBF genes, and that Poaceae CBFs can be classified into 10 groups that share a common phylogenetic origin and similar structural characteristics. Six of these groups (IIIc, IIId, IVa, IVb, IVc and IVd) are found only in the Pooideae suggesting they represent the CBF response machinery that evolved recently during colonization of temperate habitats. Expression studies reveal that five of the Pooideae-specific groups display higher constitutive and low temperature inducible expression in the winter cultivar, and a diurnal regulation pattern during growth at warm temperature. The higher constitutive and inducible expression within these CBF groups is an inherited trait that may play a predominant role in the superior low temperature tolerance capacity of winter cultivars and possibly be a basis of genetic variability in freezing tolerance within the Pooideae subfamily

Role of respirators in controlling the spread of novel coronavirus (COVID-19) amongst dental healthcare providers: A review

During the ongoing COVID-19 pandemic, health care professionals are at the forefront of managing the highly infectious corona virus. As the most common route of transmission is via aerosols and droplet inhalation, it is critical for health care workers to have the correct personal protective equipment (PPE) including gowns, masks, and goggles. Surgical masks are not effective in preventing the influenza and SARS, so they are unlikely to be able to resist contaminated aerosols form entering the respiratory system. Therefore, it is vital to use respirators which have been proven to offer better protection against droplets, aerosols and fluid penetration and which form a tight seal around the mouth and nose. Various types of respirators are used in healthcare settings, such as half-mask filtering facepiece respirators (FFRs) and powered air-purifying respirators (PAPRs). The most commonly used FFR is the N95 disposable respirator, which is tight fitting and has a 95% or above particle filtering efficiency for a median particle size of 0.3 micrometer. This review discusses respirators, their purpose, typs, clinical efficiency and proper donning and doffing techniques

Differential Mechanisms to Induce Dehydration Tolerance by Abscisic Acid and Sucrose in Spathoglottis plicata (Orchidaceae) protocorms

Abscisic acid (ABA) and sucrose are known to induce dehydration tolerance of in vitro plant cells and tissues. The present study reports the presence of different mechanisms by which sucrose and ABA improve dehydration tolerance of Spathoglottis plicata (orchid) protocorms. Orchid protocorms were generated aseptically from seeds on Murashig and Skoog medium, and then treated for 7 d in medium containing 10 mg L−1 ABA and/or 10% (w/v) sucrose. Dehydration tolerance of protocorms was determined at ∼25 °C under various drying conditions at relative humidity from 7 to 93%. The actual rate of water loss (i.e. drying rate) was determined using the rate constant of tissue water loss during drying according to the first-order kinetics. Drying rate affected dehydration tolerance. ABA treatment reduced drying rate and increased dehydration tolerance of protocorms at all relative humidity values tested. However, when compared on the basis of actual drying rates, there was no difference in dehydration tolerance between control and ABA-treated protocorms, suggesting that ABA-induced tolerance was correlated with the drying rate reduction. Sucrose treatment was more effective than ABA treatment for the induction of dehydration tolerance. Interestingly, sucrose only slightly affected drying rate. ABA treatment significantly enhanced the synthesis of dehydrin, whereas sucrose treatment primarily resulted in sucrose accumulation. Sucrose treatment also affected protein turnover during drying, causing a significant decrease in protein content in protocorms. Slow drying promoted the degradation of high molecular weight proteins and enhanced the synthesis of low molecular weight dehydrin. The data suggest that different physiological mechanisms are probably involved in the induction of dehydration tolerance by ABA and sucrose treatment