Plant and fungal gene expression coupled with stable isotope labeling provide novel information on sulfur uptake and metabolism in orchid mycorrhizal protocorms.

Orchid mycorrhiza (OM) represents an unusual symbiosis between plants and fungi because in all orchid species carbon is provided to the host plant by the mycorrhizal fungus at least during the early stages of orchid development, named a protocorm. In addition to carbon, orchid mycorrhizal fungi provide the host plant with essential nutrients such as phosphorus and nitrogen. In mycorrhizal protocorms, nutrients transfer occurs in plant cells colonized by the intracellular fungal coils, or pelotons. Whereas the transfer of these vital nutrients to the orchid protocorm in the OM symbiosis has been already investigated, there is currently no information on the transfer of sulfur (S). Here, we used ultra-high spatial resolution secondary ion mass spectrometry (SIMS) as well as targeted gene expression studies and laser microdissection to decipher S metabolism and transfer in the model system formed by the Mediterranean orchid Serapias vomeracea and the mycorrhizal fungus Tulasnella calospora. We revealed that the fungal partner is actively involved in S supply to the host plant, and expression of plant and fungal genes involved in S uptake and metabolism, both in the symbiotic and asymbiotic partners, suggest that S transfer most likely occurs as reduced organic forms. Thus, this study provides original information about the regulation of S metabolism in OM protocorms, adding a piece of the puzzle on the nutritional framework in OM symbiosis.

Differential root and cell regulation of maize aquaporins by the arbuscular mycorrhizal symbiosis highlights its role in plant water relations.

This study aims to elucidate if the regulation of plant aquaporins by the arbuscular mycorrhizal (AM) symbiosis occurs only in roots or cells colonized by the fungus or at whole root system. Maize plants were cultivated in a split-root system, with half of the root system inoculated with the AM fungus and the other half uninoculated. Plant growth and hydraulic parameters were measured and aquaporin gene expression was determined in each root fraction and in microdissected cells. Under well-watered conditions, the non-colonized root fractions of AM plants grew more than the colonized root fraction. Total osmotic and hydrostatic root hydraulic conductivities (Lo and Lpr) were higher in AM plants than in non-mycorrhizal plants. The expression of most maize aquaporin genes analysed was different in the mycorrhizal root fraction than in the non-mycorrhizal root fraction of AM plants. At the cellular level, differential aquaporin expression in AM-colonized cells and in uncolonized cells was also observed. Results indicate the existence of both, local and systemic regulation of plant aquaporins by the AM symbiosis and suggest that such regulation is related to the availability of water taken up by fungal hyphae in each root fraction and to the plant need of water mobilization.

Placental Protein 13: Vasomodulatory Effects on Human Uterine Arteries and Potential Implications for Preeclampsia.

Placental protein 13 (PP13) exhibits a plasma concentration that increases gradually during normal gestation, a process that is disrupted in preeclampsia, which is characterized by elevated vascular resistance, reduced utero-placental blood flow, and intrauterine growth restriction. This study investigated PP13's role in vascular tone regulation and its molecular mechanisms. Uterine and subcutaneous arteries, isolated from both pregnant and non-pregnant women, were precontracted with the thromboxane analogue U46619 and exposed to PP13 using pressurized myography. The molecular mechanisms were further investigated, using specific inhibitors for nitric oxide synthase (L-NAME+LNNA at 10-4 M) and guanylate cyclase (ODQ at 10-5 M). The results showed that PP13 induced vasodilation in uterine arteries, but not in subcutaneous arteries. Additionally, PP13 counteracted U46619-induced vasoconstriction, which is particularly pronounced in pregnancy. Further investigation revealed that PP13's mechanism of action is dependent on the activation of the nitric oxide-cGMP pathway. This study provides novel insights into the vasomodulatory effects of PP13 on human uterine arteries, underscoring its potential role in regulating utero-placental blood flow. These findings suggest that PP13 may be a promising candidate for improving utero-placental blood flow in conditions such as preeclampsia. Further research and clinical studies are warranted to validate PP13's efficacy and safety as a therapeutic agent for managing preeclampsia.

Integration of fungal transcriptomics and metabolomics provides insights into the early interaction between the ORM fungus Tulasnella sp. and the orchid Serapias vomeracea seeds.

In nature, germination of orchid seeds and early plant development rely on a symbiotic association with orchid mycorrhizal (ORM) fungi. These fungi provide the host with the necessary nutrients and facilitate the transition from embryos to protocorms. Despite recent advances in omics technologies, our understanding of this symbiosis remains limited, particularly during the initial stages of the interaction. To address this gap, we employed transcriptomics and metabolomics to investigate the early responses occurring in the mycorrhizal fungus Tulasnella sp. isolate SV6 when co-cultivated with orchid seeds of Serapias vomeracea. The integration of data from gene expression and metabolite profiling revealed the activation of some fungal signalling pathways before the establishment of the symbiosis. Prior to seed contact, an indole-related metabolite was produced by the fungus, and significant changes in the fungal lipid profile occurred throughout the symbiotic process. Additionally, the expression of plant cell wall-degrading enzymes (PCWDEs) was observed during the pre-symbiotic stage, as the fungus approached the seeds, along with changes in amino acid metabolism. Thus, the dual-omics approach employed in this study yielded novel insights into the symbiotic relationship between orchids and ORM fungi and suggest that the ORM fungus responds to the presence of the orchid seeds prior to contact.

Safety and efficacy of caplacizumab in a case of thrombotic thrombocytopenic purpura in the postpartum period.

Thrombotic thrombocytopenic purpura (TTP) is a rare and life-threatening disease for which pregnancy and the postpartum period represent risk factors. Here, we present the case of a 39-year-old woman at the 31st week of gestation, who presented with cutaneous haemorrhagic symptoms. The complete blood count showed anaemia, thrombocytopenia, increase in haemolysis indices and undetectable ADAMTS13 activity. Acquired TTP was diagnosed, and she started daily plasma exchange (PEX) and methylprednisolone. After 5 days, an emergency caesarean section was performed with success because of pathologic cardiotocographic findings. After 7 days of PEX, the patient showed an initial laboratoristic improvement; unfortunately, 3 days later, she had a recurrence of disease and started daily PEX, caplacizumab and steroid, obtaining a haematological improvement. No literature data about caplacizumab use in pregnant or breastfeeding patients are available. In the present study, we describe that caplacizumab in the postpartum period could be well tolerated and effective.