Histamine-releasing factor in severe asthma and rhinovirus-associated asthma exacerbation.

BACKGROUND: Histamine-releasing factor (HRF) is implicated in allergic diseases. We previously showed its pathogenic role in murine models of asthma. OBJECTIVE: We aim to present data analysis from 3 separate human samples (sera samples from asthmatic patients, nasal washings from rhinovirus [RV]-infected individuals, and sera samples from patients with RV-induced asthma exacerbation) and 1 mouse sample to investigate correlates of HRF function in asthma and virus-induced asthma exacerbations. METHODS: Total IgE and HRF-reactive IgE/IgG as well as HRF in sera from patients with mild/moderate asthma or severe asthma (SA) and healthy controls (HCs) were quantified by ELISA. HRF secretion in culture media from RV-infected adenovirus-12 SV40 hybrid virus transformed human bronchial epithelial cells and in nasal washings from experimentally RV-infected subjects was analyzed by Western blotting. HRF-reactive IgE/IgG levels in longitudinal serum samples from patients with asthma exacerbations were also quantified. RESULTS: HRF-reactive IgE and total IgE levels were higher in patients with SA than in HCs, whereas HRF-reactive IgG (and IgG1) level was lower in asthmatic patients versus HCs. In comparison with HRF-reactive IgElow asthmatic patients, HRF-reactive IgEhigh asthmatic patients had a tendency to release more tryptase and prostaglandin D2 on anti-IgE stimulation of bronchoalveolar lavage cells. RV infection induced HRF secretion from adenovirus-12 SV40 hybrid virus transformed bronchial epithelial cells, and intranasal RV infection of human subjects induced increased HRF secretion in nasal washes. Asthmatic patients had higher levels of HRF-reactive IgE at the time of asthma exacerbations associated with RV infection, compared with those after the resolution. This phenomenon was not seen in asthma exacerbations without viral infections. CONCLUSIONS: HRF-reactive IgE is higher in patients with SA. RV infection induces HRF secretion from respiratory epithelial cells both in vitro and in vivo. These results suggest the role of HRF in asthma severity and RV-induced asthma exacerbation.

Cooperative Regulation of the Mucosal Mast Cell-Specific Protease Genes Mcpt1 and Mcpt2 by GATA and Smad Transcription Factors.

Mouse mast cell proteases (mMCP)-1 and -2 are specifically expressed in mucosal mast cells (MCs). However, the transcriptional regulation mechanism of the Mcpt1 and Mcpt2 genes induced in mucosal MCs is largely unknown. In the current study, we found that TGF-ß stimulation drastically induced upregulation of Mcpt1 and Mcpt2 mRNA in mouse bone marrow-derived MCs (BMMCs). TGF-ß-induced expression of Mcpt1 and Mcpt2 was markedly suppressed by transfection with small interfering RNA targeting Smad2 or Smad4 and moderately reduced by Smad3 small interfering RNA. We next examined the roles of the hematopoietic cell-specific transcription factors GATA1 and GATA2 in the expression of Mcpt1 and Mcpt2 and demonstrated that knockdown of GATA1 and GATA2 reduced the mRNA levels of Mcpt1 and Mcpt2 in BMMCs. The recruitment of GATA2 and acetylation of histone H4 of the highly conserved GATA-Smad motifs, which were localized in the distal regions of the Mcpt1 and Mcpt2 genes, were markedly increased by TGF-ß stimulation, whereas the level of GATA2 binding to the proximal GATA motif was not affected by TGF-ß. A reporter assay showed that TGF-ß stimulation upregulated GATA2-mediated transactivation activity in a GATA-Smad motif-dependent manner. We also observed that GATA2 and Smad4 interacted in TGF-ß-stimulated BMMCs via immunoprecipitation and Western blotting analysis. Taken together, these results demonstrate that TGF-ß induced mMCP-1 and -2 expression by accelerating the recruitment of GATA2 to the proximal regions of the Mcpt1 and Mcpt2 genes in mucosal MCs.

Phospholipase C-ß3 regulates FcɛRI-mediated mast cell activation by recruiting the protein phosphatase SHP-1.

Mast cells are major effectors in high-affinity IgE receptor (FcɛRI)-dependent allergic reactions. Here we show that phospholipase C (PLC)-ß3 is crucial for FcɛRI-mediated mast cell activation. Plcb3(-/-) mice showed blunted FcɛRI-dependent late-phase, but not acute, anaphylactic responses and airway inflammation. Accordingly, FcɛRI stimulation of Plcb3(-/-) mast cells exhibited reduced cytokine production but normal degranulation. Reduced cytokine production in Plcb3(-/-) cells could be accounted for by increased activity of the negative regulatory Src family kinase Lyn and reduced activities of the positive regulatory protein kinases MAPKs. Mechanistically, PLC-ß3 constitutively interacts with FcɛRI, Lyn, and SHP-1 (protein phosphatase). SHP-1 probably recognizes its substrates Lyn and MAPKs via the recently described kinase tyrosine-based inhibitory motif, KTIM. Consistent with PLC-ß3- and SHP-1-mediated repression of Lyn activity by dephosphorylation at Tyr396, FcɛRI-mediated phenotypes were similar in Plcb3(-/-) and SHP-1 mutant mast cells. Thus, we have defined a PLC-ß3- and SHP-1-mediated signaling pathway for FcɛRI-mediated cytokine production.

Defective natural killer cell activity in a mouse model of eczema herpeticum.

BACKGROUND: Patients with atopic dermatitis (AD) are susceptible to several viruses, including herpes simplex virus (HSV). Some patients experience 1 or more episodes of a severe skin infection caused by HSV termed eczema herpeticum (EH). There are numerous mouse models of AD, but no established model exists for EH. OBJECTIVE: We sought to establish and characterize a mouse model of EH. METHODS: We infected AD-like skin lesions with HSV1 to induce severe skin lesions in a dermatitis-prone mouse strain of NC/Nga. Gene expression was investigated by using a microarray and quantitative PCR; antibody titers were measured by means of ELISA; and natural killer (NK) cell, cytotoxic T-cell, regulatory T-cell, and follicular helper T-cell populations were evaluated by using flow cytometry. The role of NK cells in HSV1-induced development of severe skin lesions was examined by means of depletion and adoptive transfer. RESULTS: Inoculation of HSV1 induced severe erosive skin lesions in eczematous mice, which had an impaired skin barrier, but milder lesions in small numbers of normal mice. Eczematous mice exhibited lower NK cell activity but similar cytotoxic T-cell activity and humoral immune responses compared with normal mice. The role of NK cells in controlling HSV1-induced skin lesions was demonstrated by experiments depleting or transferring NK cells. CONCLUSION: A murine model of EH with an impaired skin barrier was established in this study. We demonstrated a critical role of defective NK activities in the development of HSV1-induced severe skin lesions in eczematous mice.

The FcRß- and γ-ITAMs play crucial but distinct roles in the full activation of mast cells induced by IgEκ and Protein L.

Previous studies suggested that Protein L (PpL), the bacterial Ig-binding protein, activates mast cells. PpL presumably performs the activation by interacting with membrane-bound IgEκ, but the underlying mechanisms behind the process remain unclear. In the current study, we found that cell-surface FcεRI expression is a critical factor participant in PpL-mediated full activation of murine mast cells, which includes cytokine production, the degranulation response, and leukotriene C(4) (LTC(4)) release, and that engagement of the FcεRI with IgEκ and PpL is enough to induce tyrosine phosphorylation of ITAM in the FcRß- and γ-signaling subunits. Introduction of mutations in two canonical tyrosine residues (Y47F/Y58F) of the FcRγ-ITAM completely abolished the above-mentioned mast cell functions, with the exception of LTC(4) release. Importantly, the FcRß-ITAM acts as a signal transducer that is responsible for LTC(4) release independently of the FcRγ-ITAM. Taken together, our results suggest crucial and distinct functions for the FcRß- and γ-ITAMs in the FcεRI-dependent full activation of mast cells induced by IgEκ and PpL.

Ileal Crohn's Disease Exhibits Reduced Activity of Phospholipase C-ß3-Dependent Wnt/ß-Catenin Signaling Pathway.

Crohn's disease is a chronic, debilitating, inflammatory bowel disease. Here, we report a critical role of phospholipase C-ß3 (PLC-ß3) in intestinal homeostasis. In PLC-ß3-deficient mice, exposure to oral dextran sodium sulfate induced lethality and severe inflammation in the small intestine. The lethality was due to PLC-ß3 deficiency in multiple non-hematopoietic cell types. PLC-ß3 deficiency resulted in reduced Wnt/ß-catenin signaling, which is essential for homeostasis and the regeneration of the intestinal epithelium. PLC-ß3 regulated the Wnt/ß-catenin pathway in small intestinal epithelial cells (IECs) at transcriptional, epigenetic, and, potentially, protein-protein interaction levels. PLC-ß3-deficient IECs were unable to respond to stimulation by R-spondin 1, an enhancer of Wnt/ß-catenin signaling. Reduced expression of PLC-ß3 and its signature genes was found in biopsies of patients with ileal Crohn's disease. PLC-ß regulation of Wnt signaling was evolutionally conserved in Drosophila. Our data indicate that a reduction in PLC-ß3-mediated Wnt/ß-catenin signaling contributes to the pathogenesis of ileal Crohn's disease.

Developmental changes in excitation-contraction mechanisms of the mouse ventricular myocardium as revealed by functional and confocal imaging analyses.

Developmental changes in excitation-contraction mechanisms were examined in the ventricular myocardium from fetal, neonatal, and 1-, 2-, and 4-week-old mice. In isolated tissue, the negative inotropic effect of nifedipine decreased, while that of ryanodine increased with age. Action potential duration decreased with age, especially during the late fetal period. In ventricular cardiomyocytes, fluorescence imaging revealed that the sarcoplasmic reticulum increases progressively during pre- and postnatal development. t-Tubules were absent in the fetus and neonate, were observed only in the subsarcolemmal region at 1 week after birth, and were present throughout the cytoplasm at 2 and 4 weeks after birth. The amplitude of Ca(2+) transients, as well as its ryanodine-sensitive component, increased with age. In the neonate and 1-week-old mice, Ca(2+) at the cell center showed slower rise than the subsarcolemmal region, but in 2- and 4-week-old mice, Ca(2+) increased simultaneously across the entire width of the cell. These results suggest that in the mouse ventricular myocardium, the shortening of the action potential during the late fetal period and the development of t-tubule-sarcoplasmic reticulum coupling during the second postnatal week largely contribute to the developmental increase in the dependence of contraction on sarcoplasmic reticulum function.

A novel role for the transcription factor HIF-1α in the formation of mast cell extracellular traps.

MCs (mast cells) are critical components of the host innate immune defence against bacterial pathogens, providing a variety of intra- and extra-cellular antimicrobial functions. In the present study we show, for the first time, that the transcriptional regulator HIF-1α (hypoxia-inducible factor-1α) mediates the extracellular antimicrobial activity of human and murine MCs by increasing the formation of MCETs (MC extracellular traps).

JNK1 controls mast cell degranulation and IL-1{beta} production in inflammatory arthritis.

Rheumatoid arthritis (RA) is a chronic inflammatory disease marked by bone and cartilage destruction. Current biologic therapies are beneficial in only a portion of patients; hence small molecules targeting key pathogenic signaling cascades represent alternative therapeutic strategies. Here we show that c-Jun N-terminal kinase (JNK) 1, but not JNK2, is critical for joint swelling and destruction in a serum transfer model of arthritis. The proinflammatory function of JNK1 requires bone marrow-derived cells, particularly mast cells. Without JNK1, mast cells fail to degranulate efficiently and release less IL-1ß after stimulation via Fcγ receptors (FcγRs). Pharmacologic JNK inhibition effectively prevents arthritis onset and abrogates joint swelling in established disease. Hence, JNK1 controls mast cell degranulation and FcγR-triggered IL-1ß production, in addition to regulating cytokine and matrix metalloproteinase biosynthesis, and is an attractive therapeutic target in inflammatory arthritis.

Regulation of Syk activity by antiviral adaptor MAVS in FcεRI signaling pathway.

Background: Mast cells are the major effector cell type for IgE-mediated allergic reactions. Recent studies revealed a role for mast cells in orchestrating the host response to viral infections. Objective: We studied the relationship between FcεRI (high-affinity IgE receptor) and RIG-I-like receptor (RLR)-mediated antiviral signaling pathways. Methods: Mast cells (BMMCs) were cultured from bone marrow cells from mice deficient in MAVS or other RLR signaling molecules. MAVS expression was restored by retroviral transduction of MAVS-deficient BMMCs. These cells were stimulated with IgE and antigen and their activation (degranulation and cytokine production/secretion) was quantified. FcεRI-mediated signaling events such as protein phosphorylation and Ca2+ flux were analyzed by western blotting and enzyme assays. WT and mutant mice as well as mast cell-deficient KitW-sh/W-sh mice engrafted with BMMCs were subjected to passive cutaneous anaphylaxis. Results: Unexpectedly, we found that mast cells devoid of the adaptor molecule MAVS exhibit dramatically increased cytokine production upon FcεRI stimulation, despite near-normal degranulation. Consistent with these observations, MAVS inhibited tyrosine phosphorylation, thus catalytic activity of Syk kinase, the key signaling molecule for FcεRI-mediated mast cell activation. By contrast, mast cells deficient in RIG-I, MDA5 or IRF3, which are antiviral receptor and signaling molecules upstream or downstream of MAVS, exhibited reduced or normal mast cell activation. MAVS-deficient mice showed enhanced late-phase responses in passive cutaneous anaphylaxis. Conclusion: This study demonstrates that the adaptor MAVS in the RLR innate immune pathway uniquely intersects with the adaptive immune FcεRI signaling pathway.

Immunomodulatory contribution of mast cells to the regenerative biomaterial microenvironment.

Bioactive immunomodulatory biomaterials have shown promise for influencing the immune response to promote tissue repair and regeneration. Macrophages and T cells have been associated with this response; however, other immune cell types have been traditionally overlooked. In this study, we investigated the role of mast cells in the regulation of the immune response to decellularized biomaterial scaffolds using a subcutaneous implant model. In mast cell-deficient mice, there was dysregulation of the expected M1 to M2 macrophage transition typically induced by the biomaterial scaffold. Polarization progression deviated in a sex-specific manner with an early transition to an M2 profile in female mice, while the male response was unable to properly transition past a pro-inflammatory M1 state. Both were reversed with adoptive mast cell transfer. Further investigation of the later-stage immune response in male mice determined a greater sustained pro-inflammatory gene expression profile, including the IL-1 cytokine family, IL-6, alarmins, and chemokines. These results highlight mast cells as another important cell type that influences the immune response to pro-regenerative biomaterials.

Lyn- and PLC-beta3-dependent regulation of SHP-1 phosphorylation controls Stat5 activity and myelomonocytic leukemia-like disease.

Hyperactivation of the transcription factor Stat5 leads to various leukemias. Stat5 activity is regulated by the protein phosphatase SHP-1 in a phospholipase C (PLC)-ß3-dependent manner. Thus, PLC-ß3-deficient mice develop myeloproliferative neoplasm, like Lyn (Src family kinase)- deficient mice. Here we show that Lyn/PLC-ß3 doubly deficient lyn(-/-);PLC-ß3(-/-) mice develop a Stat5-dependent, fatal myelodysplastic/myeloproliferative neoplasm, similar to human chronic myelomonocytic leukemia (CMML). In hematopoietic stem cells of lyn(-/-);PLC-ß3(-/-) mice that cause the CMML-like disease, phosphorylation of SHP-1 at Tyr(536) and Tyr(564) is abrogated, resulting in reduced phosphatase activity and constitutive activation of Stat5. Furthermore, SHP-1 phosphorylation at Tyr(564) by Lyn is indispensable for maximal phosphatase activity and for suppression of the CMML-like disease in these mice. On the other hand, Tyr(536) in SHP-1 can be phosphorylated by Lyn and another kinase(s) and is necessary for efficient interaction with Stat5. Therefore, we identify a novel Lyn/PLC-ß3-mediated regulatory mechanism of SHP-1 and Stat5 activities.

A minor catalytic activity of Src family kinases is sufficient for maximal activation of mast cells via the high-affinity IgE receptor.

Src family kinases (SFK) are critical for initiating and regulating the response of mast cells activated by engagement of the high-affinity IgE receptor, FcepsilonRI. Lyn is the predominant SFK in mast cells and has been ascribed both positive and negative roles in regulating mast cell activation. We analyzed the mast cell phenotype of WeeB, a recently described mouse mutant that expresses a Lyn protein with profoundly reduced catalytic activity. Surprisingly, we found that this residual activity is sufficient for wild-type levels of cytokine production and degranulation in bone marrow-derived mast cells after low-intensity stimulation with anti-IgE. High-intensity stimulation of lyn(-/-) bone marrow-derived mast cells with highly multivalent Ag resulted in enhanced cytokine production as previously reported, and WeeB cells displayed an intermediate phenotype. Under this latter condition, SFK inhibition using PP2 increased cytokine production in wild-type and WeeB but not lyn(-/-) cells, resulting in substantially higher levels in the PP2-treated WeeB than in lyn(-/-) cells. Restoration of wild-type and WeeB lyn alleles in lyn(-/-) cells generated activation phenotypes similar to those in nontransduced wild-type and WeeB cells, respectively, whereas a kinase-dead allele resulted in a phenotype similar to that of empty-vector-transduced cells. These data indicate that inhibition of Lyn and/or SFK activity can result in higher levels of mast cell activation than simple deletion of lyn and that only near-complete inhibition of Lyn can impair its positive regulatory functions. Furthermore, the data suggest that both positive and negative regulatory functions of Lyn are predominantly carried out by its catalytic activity and not an adaptor function.

Dendritic cell immunoreceptor drives atopic dermatitis by modulating oxidized CaMKII-involved mast cell activation.

Allergens have been identified as potential triggers in patients with atopic dermatitis (AD). Patients with AD are highly sensitive to cockroach allergen. The underlying mechanism, however, remains undetermined. Here, we established a cockroach allergen-induced AD-like mouse model, and we demonstrate that repeated exposure to cockroach allergen led to aggravated mouse skin inflammation, characterized by increased type 2 immunity, type 2 innate lymphoid cells (ILC2s), and mast cells. Increased mast cells were also observed in patients with AD. Mast cell-deficient mice (KitW-sh/W-sh) showed diminished skin inflammation, suggesting that mast cells are required in allergen-induced skin inflammation. Furthermore, DC immunoreceptor (DCIR) is upregulated in skin mast cells of patients with AD and mediates allergen binding and uptake. DCIR-/- mice or reconstituted KitW-sh/W-sh mice with DCIR-/- mast cells showed a significant reduction in AD-like inflammation. Both in vitro and in vivo analyses demonstrate that DCIR-/- mast cells had reduced IgE-mediated mast cell activation and passive cutaneous anaphylaxis. Mechanistically, DCIR regulates allergen-induced IgE-mediated mast cell ROS generation and oxidation of calmodulin kinase II (ox-CaMKII). ROS-resistant CaMKII (MM-VVδ) prevents allergen-induced mast cell activation and inflammatory mediator release. Our study reveals a DCIR/ROS/CaMKII axis that controls allergen-induced mast cell activation and AD-like inflammation.

Regulation of myeloproliferation and M2 macrophage programming in mice by Lyn/Hck, SHIP, and Stat5.

The proliferation and differentiation of hematopoietic stem cells (HSCs) is finely regulated by extrinsic and intrinsic factors via various signaling pathways. Here we have shown that, similar to mice deficient in the lipid phosphatase SHIP, loss of 2 Src family kinases, Lyn and Hck, profoundly affects HSC differentiation, producing hematopoietic progenitors with increased proliferation, reduced apoptosis, growth factor-independent survival, and skewed differentiation toward M2 macrophages. This phenotype culminates in a Stat5-dependent myeloproliferative disease that is accompanied by M2 macrophage infiltration of the lung. Expression of a membrane-bound form of SHIP in HSCs lacking both Lyn and Hck restored normal hematopoiesis and prevented myeloproliferation. In vitro and in vivo studies suggested the involvement of autocrine and/or paracrine production of IL-3 and GM-CSF in the increased proliferation and myeloid differentiation of HSCs. Thus, this study has defined a myeloproliferative transformation-sensitive signaling pathway, composed of Lyn/Hck, SHIP, autocrine/paracrine cytokines, and Stat5, that regulates HSC differentiation and M2 macrophage programming.

Murine bone marrow-derived mast cells express chemoattractant receptor-homologous molecule expressed on T-helper class 2 cells (CRTh2).

Mast cells are bone marrow-derived effector cells that can initiate inflammatory responses to infectious organisms or allergens by releasing a multitude of pro-inflammatory factors including prostaglandin (PG) D(2). We demonstrate that primary murine bone marrow-derived mast cells (BMMCs) express the PGD(2) receptor; chemoattractant receptor-homologous molecule expressed on T(h) class 2 cells (CRT(h)2). Activation of CRT(h)2 on BMMC by PGD(2) or the CRT(h)2-specific agonist, 13,14-dihydro-15-keto-prostaglandin D(2) (DK-PGD(2)), resulted in signaling response including Ca(2+) mobilization and phosphorylation of the p42/p44 extracellular signal-regulated kinases (ERKs) kinases. Phosphorylation of the ERKs could be blocked by pertussis toxin, as well as a small molecule antagonist of CRT(h)2, Compound A. Activation of CRT(h)2 on BMMC also resulted in the up-regulation of CD23 and CD30 on the cell surface, as well as CD62L shedding. Finally, PGD(2) and DK-PGD(2) induced the migration of BMMC in vitro and in vivo in response to an intra-dermal DK-PGD(2) injection. Both these processes were inhibited by the CRT(h)2 antagonist. These results raise the possibility that the functional consequences of the PGD(2)-CRT(h)2 interaction on mast cells may be relevant in allergic inflammation.

Dominant and recessive inheritance patterns of diapause in the two-spotted spider mite Tetranychus urticae.

In this study, we investigated the diapause incidence in 3 geographic strains of the two-spotted spider mite Tetranychus urticae (Acari: Tetranychidae). Under diapause-inducing conditions of 12:12 light:dark at 15 degrees C, the diapause incidence was nearly 100% in a strain from northern Japan (Sapporo), whereas it was nearly 0% in 2 strains from southern Japan (Itoman and Takanabe). Reciprocal crosses clearly showed that the nondiapause phenotype is inherited in a completely dominant manner, and no maternal effect was detected. Backcrosses to the Itoman and Takanabe strains suggested that dominant nondiapause alleles control the nondiapause phenotype. To clarify the genetic basis of nondiapause in the northern population, we also established a nondiapausing variant ("selected nondiapause" abbreviated as snd) from the Sapporo strain. Crossing experiments revealed that a single recessive allele is responsible for the nondiapause phenotype. Thus, both dominant and recessive inheritance patterns of diapause were detected in the T. urticae populations studied here.

Short-term Change in Resting Energy Expenditure and Body Compositions in Therapeutic Process for Graves' Disease.

Objective In the medical treatment of Graves' disease, we sometimes encounter patients who gain weight after the onset of the disease. To estimate the energy required during the course of treatment when hyperthyroidism ameliorates, we measured the resting energy expenditure (REE) and body composition in patients with Graves' disease before and during treatment in the short-term. Methods Twenty patients with newly diagnosed Graves' disease were enrolled, and our REE data of 19 healthy volunteers were used. The REE was measured by a metabolic analyzer, and the basal energy expenditure (BEE) was estimated by the Harris-Benedict formula. The body composition, including body weight, fat mass (FM), muscle mass (MM) and lean body mass (LBM), were measured by a multi-frequency body composition analyzer. We tailored the nutritional guidance based on the measured REE. Results Serum thyrotropin levels were significantly increased at three and six months. Serum free thyroxine, free triiodothyronine and REE values were significantly decreased at one, three and six months. The REE/BEE ratio was 1.58±0.28 at the onset and significantly declined to 1.34±0.34, 1.06±0.19 and 1.01±0.16 at 1, 3 and 6 months, respectively. Body weight, MM and LBM significantly increased at three and six months. Conclusion The REE significantly decreased during treatment of Graves' disease. The decline was evident as early as one month after treatment. The REE after treatment was lower than in healthy volunteers, which may lead to weight gain. These data suggest that appropriate nutritional guidance is necessary with short-term treatment before the body weight normalizes in order to prevent an overweight condition and the emergence of metabolic disorders.

Suppression of ovarian development and vitellogenin gene expression in the adult diapause of the two-spotted spider mite Tetranychus urticae.

Tetranychus urticae (Acari: Tetranychidae) possesses a sac-like ovary with characteristic oocytes that protrude from the ovarian surface. In nondiapause females, transparent oocytes became opaque with yolk deposition between days 0 and 1 in the adult stage at 20 degrees C. In diapause females, however, ovarian development ceased at a stage having transparent oocytes without yolk deposition; this stage corresponded to the day-0 stage of the nondiapause females. Four partial fragments of the vitellogenin (Vg) genes of T. urticae were isolated. This is the first report on the Vg genes of mites. The deduced amino acid sequences of these four Vg gene fragments contained the von Willebrand factor D domain and the GLCG motif, which were reported to be the common features of Vg sequences in insects and ticks. Northern blot analysis did not detect Vg mRNA in the diapause adult females of T. urticae. It is, therefore, suggested that diapause mites do not synthesize Vg mRNA and that vitellogenesis is regulated at the transcriptional level in diapause.