Identification of growth insensitive to ABA3 (gia3), a Recessive Mutation Affecting ABA Signaling for the Control of Early Post-Germination Growth in Arabidopsis thaliana

The stress phytohormone ABA inhibits the developmental transition taking the mature embryo in the dry seed towards a young seedling. ABA also induces the accumulation of the basic leucine zipper (bZIP) transcription factor ABA-insensitive 5 (ABI5) which, apart from blocking endosperm rupture, also protects the embryo by stimulating the expression of late embryogenesis abundant (LEA) genes that conferred osmotolerance during seed maturation. It is unknown whether ABA recruits additional embryonic pathways to control early seedling growth and fitness. Here we identify gia3 (growth insensitive to ABA3), a recessive locus in Arabidopsis mediating cotyledon cellular maturation and ABA-dependent repression of cotyledon expansion and greening. Microarray studies showed that expression of the essential mid-embryogenesis gene Maternal Embryo Effect 26 (MEE26) is induced by ABA during early seedling growth in wild-type (WT) or abi5 plants but not in gia3 mutants. However, we also show that the GIA3 locus controls ABA-dependent gene expression responses that partially overlap with those controlled by ABI5. Thus, the gia3 locus identifies an additional arm of ABA signaling, distinct from that controlled by ABI5, which recruits MEE26 expression and maintains cotyledon embryonic identity. Fine mapping localized the gia3 locus within a 1 Mb interval of chromosome 3, containing a large DNA insertion of a duplicated region of chromosome 2. It remains unknown at present whether gia3 phenotypes are the result of single or multiple genetic alteration

NADPH oxidase and ROS in kidney growth

Ureteric bud branching and nephrogenesis are performed through large-scale proliferation and apoptosis events during renal development. Reactive oxygen species (ROS), produced by NADPH oxidase, may contribute to cell behaviors, including proliferation and apoptosis. We investigated the role of NADPH oxidase expression and ROS production in developing kidneys. Immunohistochemistry revealed that NADPH oxidase components were expressed on epithelial cells in ureteric bud branches, as well as on immature glomerular cells and epithelial cells in nephrogenic zones. ROS production, detected by dihydroethidium assay, was strongly observed in ureteric bud branches and nephrogenic zones, corresponding with NADPH oxidase localization. Organ culture of E14 kidneys revealed that the inhibition of NADPH oxidase significantly reduced the number of ureteric bud branches and tips, consistent with reduced ROS production. This was associated with reduced expression of phosphorylated ERK1/2 and increased expression of cleaved caspase-3. Organ culture of E18 kidneys showed that the inhibition of NADPH oxidase reduced nephrogenic zone size, accompanied by reduced ROS production, fewer proliferating cell nuclear antigen-positive cells, lower p-ERK1/2 expression, and increased expression of cleaved caspase-3. These results demonstrate that ROS produced by NADPH oxidase might play an important role in ureteric bud branching and nephrogenesis by regulating proliferation and apoptosis

Delayed Follow-up Visits and Thyrotropin Among Patients With Levothyroxine During the COVID-19 Pandemic

Context: The indirect effects of the COVID-19 pandemic on clinical practice have received great attention, but evidence regarding thyroid disease management is lacking. Objective: We aimed to investigate the association between delayed follow-up visits during the pandemic and their serum thyrotropin (TSH) levels among patients being treated with levothyroxine. Methods: This study included 25 361 patients who made a follow-up visit as scheduled (n = 9063) or a delayed follow-up visit ( 4.5 mIU/L, aRR [95% CI] = 1.72 [1.60-1.85]; and TSH > 10 mIU/L, aRR [95% CI] = 2.38 [2.16-2.62]). Conclusion: A delayed follow-up visit during the COVID-19 pandemic was associated with less well-controlled TSH among patients with levothyroxine

The attraction of Tremex apicalis (Hymenoptera, Siricidae, Tremecinae) and its parasitoid Ibalia japonica (Hymenoptera, Ibaliidae) to the fungus Cerrena unicolor

Woodwasps (Hymenoptera: Siricidae) are saproxylic insects and a common forest pest. Siricid woodwasps are classified into two subfamilies: Siricinae and Tremecinae. All known symbiotic fungi of Siricinae are in the genus Amylostereum Boidin while some species of Tremecinae have been observed to have a relationship with the fungus Cerrena unicolor (Bull.) Murrill. Previous studies about the host searching behavior of woodwasps and their parasitoids have focused primarily on the subfamily Siricinae. We analyzed the role of C. unicolor volatiles on the host searching behavior of Tremex apicalis Matsumura (Hymenoptera: Siricidae: Tremecinae) and its parasitoid Ibalia (Tremibalia) japonica Matsumura (Hymenoptera: Ibaliidae). The results of an olfactory response experiment indicated that the females of T. apicalis and its parasitoid find their respective hosts using volatiles from C. unicolor. Using DNA barcode, we identified basidiocarps on the trees infested with T. apicalis. The basidiocarps were all white-rot fungi that cause sapwood decay, including C. unicolor. Two additional species that we identified belonged to genera closely related to C. unicolor. Woodwasp species are known to carry symbiotic fungi in a pair of specialized sacs called mycangia. Notably we found that mycangia-like structures were absent in the abdomens of T. apicalis females. To the best of our knowledge, Xeris spectrum (Linnaeus) (Hymenoptera: Siricidae) is the only reported example of woodwasp species that do not contain symbiotic fungi in their bodies. Our results suggested that: (1) T. apicalis females search for host wood that is already infected with sapwood decaying fungus using volatile compounds; (2) T. apicalis’ female parasitoid also uses volatile compounds from fungus to locate wood that is infested with its potential host

Identification of "gia3", a novel recessive locus mediating ABA-dependent growth arrest responses during seed germination in "Arabidopsis thaliana"

Phytohormone abscisic acid (ABA) inhibits the development of young seedlings including (1) radicle tip emergence and (2) cotyledon expansion. "ABI5" is requiered for (1). But more factors are likely involved. Here I describe a novel recessive mutation, "growth insensitive to ABA 3 (gia3)". Genetic analyses between "gia3" and "abi5" revealed that ABA inhibition was regulated in two steps. The first is the inhibition of (1), where "ABI5" plays a major role; the second is the inhibition of (2), where "GIA3" plays a major role. In the search for "GIA3" pathway targets using microarrays, I found that the expression of a mid-embryogenesis gene "(MEE26)" was induced in an ABA- and "GIA3"- dependent manner. These results uncovered a novel "GIA3" pathway, one phenotypically and molecularly independent from ABI5. By inducing a mid-embryogenesis gene, the "GIA3" pathway is perhaps conferring additional embryonic identities to the seedlings under stress