Characterization of the heterooligomeric red-type rubisco activase from red algae

The key photosynthetic CO2 fixing enzyme Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) is prone to be inhibited by its own substrate RuBP and other sugar phosphates. In diverse organisms, various molecular chaperones termed the Rubisco activases have been recruited to remodel inhibited Rubisco complexes leading to the release of the inhibitors. Although red-type Rubiscos are a potential target in plant biotechnology to enhancing photosynthetic efficiency, their regulation is poorly studied. Here we biochemically characterized the two red-type Rubisco activase isoforms encoded by the thermophilic red algae Cyanidioschyzon merolae, as well as a homologue found in α-cyanobacteria. The individual algal isoforms are inactive in isolation, but when mixed form a functional hetero-oligomeric activase. Mutagenesis of key functional motifs indicates that ATP hydrolysis of the subunits is highly coordinated and that the nuclear-genome encoded isoform is more critical for activase function than the plastid-genome encoded counterpart. Our findings also suggest broad substrate compatibility among red-type Rubisco activases.​Doctor of Philosophy (SBS

Impact of hepatitis C remission on glycemic control in patients with type 2 diabetes mellitus: primary care outpatient experience

Chronic hepatitis C (CHC) is associated with a higher risk of developing type 2 diabetes mellitus (DM). In patients with preexisting type 2 DM, CHC often worsens glycemic control. With direct-acting antivirals (DAAs)-based treatment regimens for CHC, nearly all patients achieve sustained virologic response (SVR). There is limited literature demonstrating improvement in the glycemic index of patients with DM following the eradication of hepatitis C virus (HCV) with DAA. Thus, it is reasonable to hypothesize that early treatment of CHC and optimal glycemic control in these patients could prevent chronic complications of diabetes and worsening of liver disease. We performed a retrospective cohort study examining whether HCV eradication with DAAs leads to improved glycemic index in patients with DM and the feasibility of safely and successfully offering such care at a primary care physician/providers (PCP) office

Characterization of the heterooligomeric red-type rubisco activase from red algae

The photosynthetic CO2-fixing enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) is inhibited by nonproductive binding of its substrate ribulose-1,5-bisphosphate (RuBP) and other sugar phosphates. Reactivation requires ATP-hydrolysis–powered remodeling of the inhibited complexes by diverse molecular chaperones known as rubisco activases (Rcas). Eukaryotic phytoplankton of the red plastid lineage contain so-called red-type rubiscos, some of which have been shown to possess superior kinetic properties to green-type rubiscos found in higher plants. These organisms are known to encode multiple homologs of CbbX, the α-proteobacterial red-type activase. Here we show that the gene products of two cbbX genes encoded by the nuclear and plastid genomes of the red algae Cyanidioschyzon merolae are nonfunctional in isolation, but together form a thermostable heterooligomeric Rca that can use both α-proteobacterial and red algal-inhibited rubisco complexes as a substrate. The mechanism of rubisco activation appears conserved between the bacterial and the algal systems and involves threading of the rubisco large subunit C terminus. Whereas binding of the allosteric regulator RuBP induces oligomeric transitions to the bacterial activase, it merely enhances the kinetics of ATP hydrolysis in the algal enzyme. Mutational analysis of nuclear and plastid isoforms demonstrates strong coordination between the subunits and implicates the nuclear-encoded subunit as being functionally dominant. The plastid-encoded subunit may be catalytically inert. Efforts to enhance crop photosynthesis by transplanting red algal rubiscos with enhanced kinetics will need to take into account the requirement for a compatible Rca.MOE (Min. of Education, S’pore)Accepted versio

Hybridization alters spontaneous mutation rates in a parent-of-origin-dependent fashion in Arabidopsis

Over 70 years ago, increased spontaneous mutation rates were observed in Drosophila spp. hybrids, but the genetic basis of this phenomenon is not well understood. The model plant Arabidopsis (Arabidopsis thaliana) offers unique opportunities to study the types of mutations induced upon hybridization and the frequency of their occurrence. Understanding the mutational effects of hybridization is important, as many crop plants are grown as hybrids. Besides, hybridization is important for speciation and its effects on genome integrity could be critical, as chromosomal rearrangements can lead to reproductive isolation. We examined the rates of hybridization-induced point and frameshift mutations as well as homologous recombination events in intraspecific Arabidopsis hybrids using a set of transgenic mutation detector lines that carry mutated or truncated versions of a reporter gene. We found that hybridization alters the frequency of different kinds of mutations. In general, Columbia (Col) × Cape Verde Islands and Col × C24 hybrid progeny had decreased T→G and T→A transversion rates but an increased C→T transition rate. Significant changes in frameshift mutation rates were also observed in some hybrids. In Col × C24 hybrids, there is a trend for increased homologous recombination rates, except for the hybrids from one line, while in Col × Cape Verde Islands hybrids, this rate is decreased. The overall genetic distance of the parents had no influence on mutation rates in the progeny, as closely related accessions on occasion displayed higher mutation rates than accessions that are separated farther apart. However, reciprocal hybrids had significantly different mutation rates, suggesting parent-of-origin-dependent effects on the mutation frequency

Current commercial dPCR platforms: technology and market review

Digital polymerase chain reaction (dPCR) technology has provided a new technique for molecular diagnostics, with superior advantages, such as higher sensitivity, precision, and specificity over quantitative real-time PCRs (qPCR). Eight companies have offered commercial dPCR instruments: Fluidigm Corporation, Bio-Rad, RainDance Technologies, Life Technologies, Qiagen, JN MedSys Clarity, Optolane, and Stilla Technologies Naica. This paper discusses the working principle of each offered dPCR device and compares the associated: technical aspects, usability, costs, and current applications of each dPCR device. Lastly, up-and-coming dPCR technologies are also presented, as anticipation of how the dPCR device landscape may likely morph in the next few years. © 2022 Informa UK Limited, trading as Taylor & Francis Group