Localization of secreted ferritin (FER2) in the embryos of the tick Haemaphysalis longicornis.

Despite the absence of a blood meal, embryogenesis involves many processes that require nutrients and other essential elements, including iron. Due to the lack of an external source of these nutrients, these requirements are acquired maternally. Because of the toxic nature of iron, they are transferred through iron transport molecules such as secreted ferritin (FER2). Here we tried to follow the trail of the FER2 through indirect immunofluorescence, and we observed an apparent shift of FER2 from the germ layer at the early part of development to the appendages during the late stage of embryogenesis. FER2 is also found in the middle part of the legs of the embryo. The apparent movement not only sheds light on iron processing events during embryogenesis but also indirectly guides organogenesis in the tick.

Chromosome-Level Genome Sequence of Aspergillus puulaauensis MK2, a Fungus Isolated from a Dead Hard Tick.

Aspergillus puulaauensis strain MK2 was isolated from a dead hard tick (Haemaphysalis longicornis). Here, we determined the chromosome-level genome sequence of A. puulaauensis MK2.

Expression analysis of glutathione S-transferases and ferritins during the embryogenesis of the tick Haemaphysalis longicornis.

In the tick life cycle, embryogenesis is the only stage of development wherein no blood meal is required. Nevertheless, even in the absence of a blood meal, which is the source of nutrients as well as the ferrous iron and heme that could cause oxidative stress in ticks, malondialdehyde (MDA) has been reported to increase during this period. Additionally, the knockdown of some oxidative stress-related molecules such as ferritin has resulted in abnormal eggs and embryonic death. Here, we investigate the gene and protein expression profiles of the identified glutathione S-transferases (GSTs) and ferritins (Fers) of the tick H. longicornis during embryogenesis through quantitative reverse transcription polymerase chain reaction (RT-qPCR) and Western blotting, respectively. We also confirm the lipid peroxidation and ferrous iron concentration level using a thiobarbituric acid reactive substances (TBARS) assay. Finally, we attempt to correlate these findings with the events occurring by establishing a staging process in H. longicornis embryos. Lipid peroxidation increased during the course of embryogenesis, as does the amount of GST proteins. On the other hand, the GST genes have high expression at the 1st day post-oviposition, during the early stage of embryogenesis and at day 10 during the period wherein the germ band is observable. Fer gene expression also starts to increase at day 10 and peaks at day 15. In the ferritin proteins, only the secretory ferritin (Fer2) is detected and constitutively expressed during embryogenesis. Events occurring during embryogenesis, such as energy production and iron metabolism for cellular proliferation and differentiation cause oxidative stress in the embryo. To counteract oxidative stress, it is possible that the embryo may utilize oxidative stress-related molecules such as GSTs and Fer2, which could be either maternally or embryo-derived.

Transcriptional regulation of the rainbow trout CYP19a gene by FTZ-F1 homologue.

In rainbow trout, there are at least two CYP19 genes (CYP19a and CYP19b). They encode distinct P450arom isozymes that are differentially expressed in the ovary and brain. To understand the transcriptional regulation of the rainbow trout CYP19a (rtCYP19a) gene in the ovary, we isolated its 5'-flanking region. The presence of potential FTZ-F1-binding sites prompted us to isolate the cDNA encoding a rainbow trout FTZ-F1 homologue (rtFTZ-F1) and analyze its effect on the rtCYP19a gene transcriptional activity. RT-PCR analysis showed overlapping expression of the rtCYP19a and rtFTZ-F1 genes in the ovary. Transient transfection studies in Chinese hamster ovary-derived CHO-K1 cells revealed that the region from -247 to -105, which contains three potential FTZ-F1-binding sites, was required for rtFTZ-F1-mediated transcriptional activation of the rtCYP19a gene. Among the three potential binding sites, the two from -150 to -142 and from -118 to -110 showed strong affinities for rtFTZ-F1 in gel shift assays, and base substitutions in either site almost abolished the transcriptional activation by rtFTZ-F1. Taken together, these results demonstrate that rtFTZ-F1 plays an important role in the transcriptional regulation of the rtCYP19a gene in the ovary.