Mechanism of Zinc absorption in plants: uptake,transport, translocation and accumulation

Zinc (Zn) is an essential micronutrient for plants and animals. Unfortunately, deficiency of Zn in humans has increased on a global scale. The main reason of this micronutrient deficiency is dietary intakes of food with low Zn levels. Adoption of biofortification approaches would result in Zn enrichment of target tissue to a considerable extent. However, there is a basic need to understand Zn absorption mechanisms in plants prior to exploitation of such practical approaches. Zn absorption is a complex physiological trait which is mainly governed by Zn transporters and metal chelators of plant system. Plant growth stage, edaphic factors, season etc. also influence Zn efficiency of particular species. Molecular studies in Zn hyperaccumulators have already demonstrated the participation of specific Zn transporters, vacuolar sequestration and detoxification mechanisms in maintenance of Zn homeostasis. These have been described in detail in present review and provide opportunities for utilization in biofortification programmes. However, issues such as lesser bioavailability of Zn in target organ, uptake of toxic divalent cations (Cd, Ni, Pb, As etc.) along with Zn, sink activity and dilution in Zn concentration in response to sink number etc. in biofortified crops need further investigation. In order to design novel strategy in biofortification programmes, future researches should focus on physiological performance and yield penalties in concerned crop, metabolic load in term of organic acid production and crosstalk of Zn with other mineral nutrients under low and high Zn conditions.     

Using Drugs to Probe the Variability of Trans-Epithelial Airway Resistance

Background

Precision medicine aims to combat the variability of the therapeutic response to a given medicine by delivering the right medicine to the right patient. However, the application of precision medicine is predicated on a prior quantitation of the variance of the reference range of normality. Airway pathophysiology provides a good example due to a very variable first line of defence against airborne assault. Humans differ in their susceptibility to inhaled pollutants and pathogens in part due to the magnitude of trans-epithelial resistance that determines the degree of epithelial penetration to the submucosal space. This initial ‘set-point’ may drive a sentinel event in airway disease pathogenesis. Epithelia differentiated in vitro from airway biopsies are commonly used to model trans-epithelial resistance but the ‘reference range of normality’ remains problematic. We investigated the range of electrophysiological characteristics of human airway epithelia grown at air-liquid interface in vitro from healthy volunteers focusing on the inter- and intra-subject variability both at baseline and after sequential exposure to drugs modulating ion transport.

Methodology/Principal Findings

Brushed nasal airway epithelial cells were differentiated at air-liquid interface generating 137 pseudostratified ciliated epithelia from 18 donors. A positively-skewed baseline range exists for trans-epithelial resistance (Min/Max: 309/2963 Ω·cm²), trans-epithelial voltage (-62.3/-1.8 mV) and calculated equivalent current (-125.0/-3.2 μA/cm²; all non-normal, P<0.001). A minority of healthy humans manifest a dramatic amiloride sensitivity to voltage and trans-epithelial resistance that is further discriminated by prior modulation of cAMP-stimulated chloride transport.

Conclusions/Significance

Healthy epithelia show log-order differences in their ion transport characteristics, likely reflective of their initial set-points of basal trans-epithelial resistance and sodium transport. Our data may guide the choice of the background set point in subjects with airway diseases and frame the reference range for the future delivery of precision airway medicine.     

Bacteriophage immobilized graphene electrodes for impedimetric sensing of bacteria (Staphylococcus arlettae)

Bacteriophages are a class of viruses that specifically infect and replicate within a bacterium. They possess inherent affinity and specificity to the particular bacterial cells. This property of bacteriophages makes them an attractive biorecognition element in the field of biosensor development. In this work, we report the use of an immobilized bacteriophage for the development of a highly sensitive electrochemical sensor for Staphylococcus arlettae, bacteria from the pathogenic family of coagulase-negative staphylococci (CNS). The specific bacteriophages were covalently immobilized on the screen-printed graphene electrodes. Thus, the fabricated bacteriophage biosensor displayed quantitative response for the target bacteria (S. arlettae) for a broad detection range (2.0–2.0 × 10⁶ cfu). A fast response time (2 min), low limit of detection (2 cfu), specificity, and stability over a prolonged period (3 months) are some of the important highlights of the proposed sensor. The practical utility of the developed sensor has been demonstrated by the analysis of S. arlettae in spiked water and apple juice samples.     

Aurora kinase Ipl1 facilitates bilobed distribution of clustered kinetochores to ensure error‐free chromosome segregation in Candida albicans

Candida albicans, an ascomycete, has an ability to switch to diverse morphological forms. While C. albicans is predominatly diploid, it can tolerate aneuploidy as a survival strategy under stress. Aurora kinase B homolog Ipl1 is a critical ploidy regulator that controls microtubule dynamics and chromosome segregation in Saccharomyces cerevisiae. In this study, we show that Ipl1 in C. albicans has a longer activation loop than that of the well‐studied ascomycete S. cerevisiae. Ipl1 localizes to the kinetochores during the G1/S phase and associates with the spindle during mitosis. Ipl1 regulates cell morphogenesis and is required for cell viability. Ipl1 monitors microtubule dynamics which is mediated by separation of spindle pole bodies. While Ipl1 is dispensable for maintaining structural integrity and clustering of kinetochores in C. albicans, it is required for the maintenance of bilobed distribution of clustered kinetochores along the mitotic spindle. Depletion of Ipl1 results in erroneous kinetochore‐microtubule attachments leading to aneuploidy due to which the organism can survive better in the presence of fluconazole. Taking together, we suggest that Ipl1 spatiotemporally ensures bilobed kinetochore distribution to facilitate bipolar spindle assembly crucial for ploidy maintenance in C. albicans.