Selective role of the DNA helicase Mcm5 in BMP retrograde signaling during Drosophila neuronal differentiation

The MCM2-7 complex is a highly conserved hetero-hexameric protein complex, critical for DNA unwinding at the replicative fork during DNA replication. Overexpression or mutation in MCM2-7 genes is linked to and may drive several cancer types in humans. In mice, mutations in MCM2-7 genes result in growth retardation and mortality. All six MCM2-7 genes are also expressed in the developing mouse CNS, but their role in the CNS is not clear. Here, we use the central nervous system (CNS) of Drosophila melanogaster to begin addressing the role of the MCM complex during development, focusing on the specification of a well-studied neuropeptide expressing neuron: the Tv4/FMRFa neuron. In a search for genes involved in the specification of the Tv4/FMRFa neuron we identified Mcm5 and find that it plays a highly specific role in the specification of the Tv4/FMRFa neuron. We find that other components of the MCM2-7 complex phenocopies Mcm5, indicating that the role of Mcm5 in neuronal subtype specification involves the MCM2-7 complex. Surprisingly, we find no evidence of reduced progenitor proliferation, and instead find that Mcm5 is required for the expression of the type I BMP receptor Tkv, which is critical for the FMRFa expression. These results suggest that the MCM2-7 complex may play roles during CNS development outside of its well-established role during DNA replication.

The MCM2-7 complex plays a critical role in the DNA replication allowing cells to progress throughout the cell cycle and divide. Overexpression or mutation in MCM2-7 genes is linked to and may drive several cancer types in humans. While MCM2-7 complex is widely expressed in the central nervous system (CNS) during development, its role is not yet clear. Here, we use the CNS of Drosophila melanogaster to address the role of the MCM complex, focusing on the specification of a well-studied neuropeptide expressing neuron: the Tv4/FMRFa neuron. We identified that Mcm5 plays a highly specific role in the specification of this neuron, and it involves other components of the MCM2-7 complex. Despite the described importance of this complex on DNA replication, we find no evidence of reduced progenitor proliferation, and instead we find that Mcm5 is required for the expression of the type I BMP receptor Tkv, which is critical for the specification of the Tv4/FMRFa neuron. These results suggest that the MCM2-7 complex may play roles during CNS development outside of its well-established role during DNA replication.

Using experience-based codesign to coproduce aphasia rehabilitation services: study protocol

INTRODUCTION

Aphasia is an impairment of language that occurs in 30%-40% of stroke survivors. This often chronic condition results in poor outcomes for the individual with aphasia and their family. Long-term aphasia management is limited, with few people receiving sufficient services by 6-12 months postonset. We present a protocol for the development of coproduced aphasia service elements. We will use experience-based codesign (EBCD), an approach that enables service users and providers to collaboratively develop services and care pathways. Drawing on the experiences of people with aphasia, their families and clinicians we will establish priorities for the development of new services and later work together to codesign them.

METHODS AND ANALYSIS

This research will be coproduced with people with aphasia (n=30-60), their families (n=30-60) and speech pathologists (n=30-60) in Queensland, Australia, using EBCD. A consumer advisory committee will provide oversight and advice throughout the research. In phase 1, we will use semistructured interviews and the nominal group technique to explore experiences and unmet needs in aphasia rehabilitation. Data will be analysed using thematic analysis and the resulting themes will be prioritised in multistakeholder focus groups. Outcomes of phase 1 will inform future research (phase 2) to codesign services. Financial costs and participant experiences of EBCD will be measured.

ETHICS AND DISSEMINATION

Human Research Ethics Committee approval for phase 1 has been obtained (HREC/2020/QRBW/61368). Results will be reported in peer-reviewed journal articles, presented at relevant conferences and, following EBCD suggested best practice, fed back to participants and community members at a celebratory event at completion of the project. The inclusion of service users in all stages of research will facilitate an integrated approach to knowledge translation. A summary of research findings will be made available to participating sites.

Cytochrome c Reductase is a Key Enzyme Involved in the Extracellular Electron Transfer Pathway towards Transition Metal Complexes in Pseudomonas Putida

Mediator-based extracellular electron transfer (EET) pathways can balance the redox metabolism of microbes. However, such electro-biosynthesis processes are constrained by the unknown underlying EET mechanisms. In this paper, Pseudomonas putida was studied to systematically investigate its EET pathway to transition metal complexes (i. e., [Fe(CN)6 ]3-/4- and [Co(bpy)3 ]3+/2+ ; bpy=2,2'-bipyridyl) under anaerobic conditions. Comparative proteomics showed the aerobic respiratory components were upregulated in a bioelectrochemical system without oxygen, suggesting their potential contribution to EET. Further tests found inhibiting cytochrome c oxidase activity by NaN3 and NADH dehydrogenase by rotenone did not significantly change the current output. However, the EET pathway was completely blocked, while cytochrome c reductase activity was inhibited by antimycin A. Although it cannot be excluded that cytochrome c and the periplasmic subunit of cytochrome c oxidase donate electrons to the transition metal complexes, these results strongly demonstrate that cytochrome c reductase is a key complex for the EET pathway.

Effect of elevated carbon dioxide concentration on growth, productivity and glyphosate response of parthenium weed (Parthenium hysterophorus L.)

BACKGROUND

The rise in atmospheric CO2 has huge impacts on the biology and management of invasive weed species such as Parthenium hysterophorus. This study evaluated the effect of ambient (400 ppm) and elevated (700 ppm) CO2 concentrations on P. hysterophorus growth, reproductive output and response to glyphosate applied at several doses including the recommended dose (800 g a.e. ha-1 ).

RESULTS

The plants in control treatment (no herbicide) grew taller (41%), produced a larger number of leaves (13%) and flowers (39%), and higher dry biomass (34%) at elevated CO2 as compared to the ambient CO2 . Glyphosate caused significant reduction in chlorophyll content of P. hysterophorus plants grown at both CO2 concentrations in a dose-dependent manner. The percentage herbicide injury was relatively less at elevated CO2 as compared to the ambient CO2 at 7 and 14 days after glyphosate application but it was almost similar at 21 days after application. This shows that elevated CO2 might have slowed the translocation of glyphosate initially, but most plants were killed eventually close to 21 days after application. The survival rate was higher under elevated as compared to the ambient CO2 at recommended and lower doses of glyphosate. There was a negligible difference between the two CO2 concentrations for the plant dry biomass reduction over the control treatment.

CONCLUSIONS

P. hysterophorus growth and reproductive potential (indicated by number of flowers) improved significantly by CO2 enrichment but there was little effect on the overall efficacy of glyphosate applied to control this species. © 2019 Society of Chemical Industry.