Chloroplasts require glutathione reductase to balance reactive oxygen species and maintain efficient photosynthesis

Thiol‐based redox‐regulation is vital for coordinating chloroplast functions depending on illumination and has been throroughly investigated for thioredoxin‐dependent processes. In parallel, glutathione reductase (GR) maintains a highly reduced glutathione pool, enabling glutathione‐mediated redox buffering. Yet, how the redox cascades of the thioredoxin and glutathione redox machineries integrate metabolic regulation and detoxification of reactive oxygen species remains largely unresolved because null mutants of plastid/mitochondrial GR are embryo‐lethal in Arabidopsis thaliana. To investigate whether maintaining a highly reducing stromal glutathione redox potential (E_GSH) via GR is necessary for functional photosynthesis and plant growth, we created knockout lines of the homologous enzyme in the model moss Physcomitrella patens. In these viable mutant lines, we found decreasing photosynthetic performance and plant growth with increasing light intensities, whereas ascorbate and zeaxanthin/antheraxanthin levels were elevated. By in vivo monitoring stromal E_GSH dynamics, we show that stromal E_GSH is highly reducing in wild‐type and clearly responsive to light, whereas an absence of GR leads to a partial glutathione oxidation, which is not rescued by light. By metabolic labelling, we reveal changing protein abundances in the GR knockout plants, pinpointing the adjustment of chloroplast proteostasis and the induction of plastid protein repair and degradation machineries. Our results indicate that the plastid thioredoxin system is not a functional backup for the plastid glutathione redox systems, whereas GR plays a critical role in maintaining efficient photosynthesis.     

Description of the first species of Pseudoendorchis (Cestoda: Proteocephalidae) with uniloculate suckers from the pimelodid catfish Megalonema platycephalum,with comments on the taxonomic importance of the terminal vagina

Systematic Parasitology - The proteocephalid genus Pseudoendorchis (Cestoda: Onchoproteocephalidea) has recently been proposed to accommodate seven species/species-level lineages of tapeworm...     

Characterizing the movements and habitat use of two fish species of concern in a regulated ecosystem

Hydrobiologia - In freshwater ecosystems in the northwest United States, the distribution and movements of fish between their essential habitats are particularly impacted by the presence of...     

The value and meaning attached to genetic relatedness among Australian sperm donors

While in the context of western societies sperm is attributed with a wide range of meanings, in the context of assisted reproduction it has increasingly been treated as an alienable commodity. Yet despite attempts by medical professionals to encourage a disconnect between donors and their sperm, the latter continues in many instances to operate as a synecdoche for the former. This can be seen, for example, both in donor-conceived children's desire to know their donor and in donors' investments in the use of their sperm. This paper explores the latter example by providing a discourse analysis of the narratives of 30 Australian sperm donors, with a focus on how they accounted for the value and meaning of their sperm. Three broad themes are discussed: sperm as a marker of genetic legacy, responsibility for sperm as genetic material, and sperm as a “gift” to others. The implications of these understandings of sperm among donors are discussed in relation to outcomes for all parties involved in donor conception, and suggestions are made for recognizing the investments that donors may have in their sperm.