Chorionicity and Psychomotor Development From Infancy to Childhood: The Japan Environment and Children's Study.

Twins lag behind singletons in their early psychomotor development, but little is known about how chorionicity affects this difference. We compared early psychomotor development in singletons, monochorionic (MC) twins and dichorionic (DC) twins. Our longitudinal data from the Japan Environment and Children's Study (JECS; see Appendix) included 98,042 singletons, 577 MC twins and 1051 DC twins representing the general Japanese population. Chorionicity was evaluated by ultrasound images and complemented by postnatal pathological examinations. Five domains of psychomotor development were evaluated at 6 time points from 6 months to 3 years of age using the Ages and Stages Questionnaires (ASQ-3). The data were analyzed using linear regression models. Twins lagged behind singletons in all areas of psychomotor development during infancy. This gap decreased over time but was still noticeable at 3 years of age. More than half of this difference was attributed to twins having lower birth weight and being born earlier in gestation. MC twins showed slightly delayed development compared to DC twins, but this difference was minor compared to the overall gap between twins and singletons. Twins delay singletons in their early psychomotor development, and this delay is not specific to MC twinning.

Determinants of double product: a cross-sectional study of urban residents in Japan.

BACKGROUND: The current study aimed to investigate the determinants of high double product (DP) by evaluating the association between resting DP, which is calculated as systolic blood pressure (SBP) multiplied by heart rate (HR), and blood test results and lifestyle factors. METHODS: This research included 973 participants in the baseline survey of the KOBE study, which included a cohort of urban residents. The possible DP determinants were identified by examining the association between lifestyle factors and laboratory findings and DP by analyzing covariance adjusted for sex and age. Logistic regression analysis was performed with high DP (SBP × HR ≥ 9145 mmHg beats/min or quintile according to sex) as outcome and DP determinants as independent variables. RESULTS: Age, hematocrit, and gamma-glutamyl transferase (log) level were positively associated with a high DP in both men and women. In addition, a high DP was positively associated with Homeostatic Model Assessment for Insulin Resistance score in women alone. Meanwhile, the amount of exercise was negatively associated with a high DP in men alone. CONCLUSIONS: High DP values at rest were associated with insulin resistance, gamma-glutamyl transferase, and the amount of exercise in participants without underlying disease.

[Determinants of salt taste threshold among urban residents: the KOBE study].

Objectives　Though having a high salt taste threshold has been associated with hypertension, its exact determinants remains unclear. This study aimed to identify the determinants of salt taste threshold in a community-based population and to determine the relationship between salt taste thresholds and the simultaneous presence of multiple determinants.Methods　Of the 1,117 participants of the baseline survey of the Kobe study, a cohort study of healthy urban residents, aged 40-74 years, with no history of cancer or cardiovascular diseases, nor undergoing treatment for hypertension, diabetes, or dyslipidemia, was conducted. Among them, 1,116 underwent the salt taste threshold test, and urine samples were collected to determine their estimated salt intake. The salt taste threshold test was carried out using SALSAVE®, with a salt taste threshold of 0.6% defined as normal, and that of 0.8% or more defined as high. A binomial logistic regression model was used, with high salt taste threshold as the objective variable, and life and family status, education, smoking and alcohol drinking status, intake status of salt dried fish, stress indicators, and daily salt intake (estimated from the urine sample) as the explanatory variables. A binomial logistic regression analysis was conducted, through multivariate analysis using the forced entry method, with factors influencing salt taste threshold as explanatory variables, and salt taste threshold (normal/high) as the objective variable. This analysis was performed excluding the urinary sodium-to-potassium ratio to account for multicollinearity with the estimated daily salt intake.Results　The mean age was 60.9±9.0 years for men, and 58.0±8.7 years for women. The salt taste threshold was normal in 80.9% (n=903) of the participants (73.6% [n=251] men and 84.1% [n=652] women), and high in 19.1% (n=213) of the participants (26.3% [n=90] men and 15.9% [n=123] women). Multivariate analysis revealed that smoking habits were significantly associated with a higher salt taste threshold, with an odds ratio (95% confidence interval) of 2.51 (1.33-4.74) for all participants. The odds ratio for a high salt taste threshold was 1.45 (1.03-2.03) for the top 25% estimated daily salt intake group, showing a significant association with a high salt taste threshold. In the analysis by sex, smoking habits were associated with higher salt taste thresholds, while an association with estimated daily salt intake was observed only in men.Conclusion　Smoking status and estimated daily salt intake were associated with higher salt taste thresholds in healthy urban residents.

Genome re-sequencing, SNP analysis, and genetic mapping of the parental lines of a commercial F1 hybrid cultivar of Chinese cabbage.

The genome-wide characterization of single nucleotide polymorphism (SNP) between cultivars or between inbred lines contributes to the creation of genetic markers that are important for plant breeding. Functional markers derived from polymorphisms within genes that affect phenotypic variation are especially valuable in plant breeding. Here, we report on the genome re-sequencing and analysis of the two parental inbred lines of the commercial F1 hybrid Chinese cabbage cultivar "W77". Through the genome-wide identification and classification of the SNPs and indels present in each parental line, we identified about 1,500 putative non-functional genes in each parent. We designed cleaved amplified polymorphic sequence (CAPS) markers using specific mutations found at Eco RI restriction sites in the parental lines and confirmed their Mendelian segregation by constructing a linkage map using 96 F2 plants derived from the F1 hybrid cultivar, "W77". Our results and data will be a useful genomic resource for future studies of gene function and metagenomic studies in Chinese cabbage.

Comparison of transcriptome profiles by Fusarium oxysporum inoculation between Fusarium yellows resistant and susceptible lines in Brassica rapa L.

KEY MESSAGE: Resistant and susceptible lines in Brassica rapa have different immune responses against Fusarium oxysporum inoculation. Fusarium yellows caused by Fusarium oxysporum f. sp. conglutinans (Foc) is an important disease of Brassicaceae; however, the mechanism of how host plants respond to Foc is still unknown. By comparing with and without Foc inoculation in both resistant and susceptible lines of Chinese cabbage (Brassica rapa var. pekinensis), we identified differentially expressed genes (DEGs) between the bulked inoculated (6, 12, 24, and 72 h after inoculation (HAI)) and non-inoculated samples. Most of the DEGs were up-regulated by Foc inoculation. Quantitative real-time RT-PCR showed that most up-regulated genes increased their expression levels from 24 HAI. An independent transcriptome analysis at 24 and 72 HAI was performed in resistant and susceptible lines. GO analysis using up-regulated genes at 24 HAI indicated that Foc inoculation activated systemic acquired resistance (SAR) in resistant lines and tryptophan biosynthetic process and responses to chitin and ethylene in susceptible lines. By contrast, GO analysis using up-regulated genes at 72 HAI showed the overrepresentation of some categories for the defense response in susceptible lines but not in the resistant lines. We also compared DEGs between B. rapa and Arabidopsis thaliana after F. oxysporum inoculation at the same time point, and identified genes related to defense response that were up-regulated in the resistant lines of Chinese cabbage and A. thaliana. Particular genes that changed expression levels overlapped between the two species, suggesting that they are candidates for genes involved in the resistance mechanisms against F. oxysporum.

Outcomes in ischemic and hemorrhagic stroke patients with cancer: The Japan Stroke Data Bank.

INTRODUCTION: Data on the impact of malignancy on outcomes in patients with stroke, especially hemorrhagic stroke, are limited. We aimed to clarify the association between cancer and outcomes for each stroke type (ischemic/hemorrhagic) using a hospital-based multicenter stroke registration database. PATIENTS AND METHODS: Study participants were adult patients within 7 days of the onset of ischemic stroke (IS) or hemorrhagic stroke (HS) between 2000 and 2020 in the Japan Stroke Data Bank (JSDB). The patients were categorized into two groups according to whether they had a history of cancer. Outcomes included good functional outcomes, representing a modified Rankin Scale score of 0-2 at discharge and in-hospital mortality. RESULTS: Of the 203,983 patients analyzed in this substudy, 152,591 (women, 39.9 %; median age, 75 years) had IS, and 51,392 (48.6 %; 69 years) had HS. Of these, 6409 IS (4.2 %) and 1560 HS (3.0 %) patients had any cancer. IS patients with cancer had a lower frequency of good functional outcomes (47.5 % vs. 56.3 %; adjusted odds ratio [aOR] 0.85, 95 % confidence interval [CI] 0.79-0.91) and a higher incidence of in-hospital mortality (6.7 % vs. 4.5 %; aOR 1.59, 95 % CI 1.41-1.80) than those without cancer. HS patients with cancer showed a lower frequency of good functional outcome (24.9 % vs. 35.7 %; aOR 0.88, 95 % CI 0.78-0.99) and higher incidence of in-hospital mortality (20.1 % vs. 16.0 %; aOR 1.26, 95 % CI 1.04-1.52) than those without cancer. CONCLUSIONS: Both IS and HS patients with cancer had significantly lower good functional outcomes and more in-hospital mortality.

Stroke severity and outcomes in patients with intracerebral hemorrhage on anticoagulants and antiplatelet agents: An analysis from the Japan Stroke Data Bank.

BACKGROUND AND AIM: Some patients with intracerebral hemorrhage are on antithrombotic agents at the time of the event and these may worsen outcome, but the relative risk of different oral anticoagulants and antiplatelet agents is uncertain. We determined associations between pre-onset intake of antithrombotic agents and initial stroke severity, and outcomes, in patients with intracerebral hemorrhage. METHODS: Patients with intracerebral hemorrhage admitted within 24 h after onset between January 2017 and December 2020 and recruited to the Japan Stroke Data Bank, a hospital-based multicenter prospective registry, were included. Enrolled patients were classified into four groups based on the type of antithrombotic agents being used on admission. The outcomes were the National Institutes of Health Stroke Scale (NIHSS) score on admission and modified Rankin Scale (mRS) of 5-6 at discharge. RESULTS: Of a total 9810 patients with intracerebral hemorrhage (4267 females; mean age = 70 ± 15 years), 77.1% were classified into the no-antithrombotic group, 13.2% into the antiplatelet group, 4.0% into the warfarin group, and 5.8% into the direct oral anticoagulant (DOAC) group. Median (interquartile range) NIHSS score on admission was 12 (5-22), 13 (5-26), 15 (5-30), and 13 (6-24), respectively, in the four groups. In multivariable analysis, the prestroke warfarin use was associated with higher NIHSS score (adjusted incidence rate ratio = 1.09 (95% confidence interval (CI) = 1.06-1.13), with the no-antithrombotic group as the reference), but the antiplatelet group (1.00 (95% CI = 0.98-1.02)) and DOAC group (0.98 (95% CI = 0.95-1.01)) were not. The rate of mRS 5-6 at discharge was 30.8%, 41.9%, 48.6%, and 41.5%, respectively, in the four groups. In multivariable analysis, prestroke warfarin use was associated with mRS 5-6 (adjusted odds ratio = 1.90 (95% CI = 1.28-2.81), with the no-antithrombotic group as the reference), but the antiplatelet group (1.12 (95% CI = 0.91-1.37)) and DOAC group (1.25 (95% CI = 0.88-1.77)) were not. CONCLUSION: Patients who were taking warfarin prior to intracerebral hemorrhage onset suffered more severe intracerebral hemorrhage as evidenced by higher admission NIHSS and higher discharge mRS. In contrast, no increase in severity was seen with antiplatelet agents.

Prenatal exposure to selenium, mercury, and manganese during pregnancy and allergic diseases in early childhood: The Japan Environment and Children's study.

BACKGROUND: Prenatal exposure to metallic elements may adversely affect early childhood health. However, more evidence is needed as population-based cohort studies are currently limited. OBJECTIVES: We aimed to examine the associations between prenatal metallic (mercury, selenium, and manganese) exposure and the risk of allergic diseases in early childhood until three years of age. METHODS: The data from 94,794 mother-infant pairs, who participated in the Japan Environment and Children's study, were used in this study. Prenatal metallic element exposure was measured in maternal blood collected during mid-pregnancy. The incidence of atopic dermatitis, food allergies, asthma, and allergic rhinitis during the first three years of life was prospectively investigated using self-reports of physician-diagnosed allergies. A multivariable modified Poisson regression model was used to estimate the cumulative incidence ratio and their 95% confidence intervals of allergic diseases associated with prenatal exposure to mercury, selenium, and manganese. We further evaluated the interaction between mercury and selenium exposures in this association. RESULTS: We confirmed 26,238 cases of childhood allergic diseases: atopic dermatitis, food allergies, asthma, and allergic rhinitis in 9,715 (10.3%), 10,897 (11.5%), and 9,857 (10.4%), 4,630 (4.9%), respectively. No association was found between prenatal mercury or manganese exposure and the risk of allergic diseases. Prenatal selenium exposure was inversely associated with atopic dermatitis, food allergies, allergic rhinitis, and any allergic diseases, but not with asthma. These inverse associations were more pronounced for lower mercury exposures than for higher exposures. CONCLUSIONS: Our findings suggest that prenatal exposure to selenium may be beneficial for reducing the risk of atopic dermatitis, food allergies, allergic rhinitis, and any allergic diseases in early childhood, especially with lower prenatal mercury exposure.

Purpose in life (Ikigai) and employment status in relation to cardiovascular mortality: the Japan Collaborative Cohort Study.

OBJECTIVES: To investigate whether having a purpose in life (Ikigai) is associated with risk of cardiovascular disease (CVD) mortality and whether the association varies by employment status. DESIGN: Prospective cohort study. SETTING: Residents in 45 municipalities, Japan. PARTICIPANTS: 29 517 men and 41 984 women aged 40-79 years, free of CVD and cancer at baseline from 1988 to 1990. PRIMARY OUTCOME MEASURES: CVD mortality. RESULTS: During the median follow-up of 19.1 years, 4680 deaths (2393 men and 2287 women) from total CVD were observed. Greater Ikigai was associated with a lower risk of CVD mortality, and the result was stronger for men than for women. Stratified by employment status, the inverse association was confined to unemployed persons. Among unemployed persons, the multivariable HRs of total CVD were higher for moderate and high versus low levels of Ikigai. Multivariable HRs (95% CIs) were 0.74 (0.57 to 0.97) and 0.69 (0.52 to 0.93), P for trend <0.044, respectively in men, and 0.78 (0.64 to 0.95) and 0.77 (0.61 to 0.97), P for trend=0.039 in women. No association was observed among the employed, including part-time workers, self-employed and homemakers for both men and women. Such an inverse association remained even after excluding early deaths within 5 years from the baseline survey. CONCLUSION: Higher levels of Ikigai were associated with a lower risk of CVD mortality, especially for unemployed men and women.

Physique at Birth and Cardiovascular Disease Risk Factors in Japanese Urban Residents: the KOBE Study.

AIM: This study investigated the relationship between birth physique and cardiovascular risk factors in Japanese urban residents aged 40 years and more. METHODS: A self-administered questionnaire on birth physique was performed among 624 individuals (165 men and 459 women) who participated in the KOBE study. We examined whether self-reported birth physique and available recorded birth weights matched for 72 participants. Then the association between birth physique and risk factors for all participants was examined by gender. Body size at birth in the questionnaire (large, medium, small) was set as an exposure and laboratory values from the baseline survey (2010-2011) were used as outcomes. RESULTS: Mean (standard deviation) recorded birth weight of 72 participants was 3665 (318), 3051 (300), and 2653 (199) g, in the large, medium, and small group, respectively. In the analysis for all participants, odds ratio for having both hypertension and impaired glucose tolerance were significantly higher in the small versus large birth weight group, which was 7.42 (95% CI 1.75-31.50) for men and 4.44 (95% CI 1.14-17.30) for women after adjusting for age, body mass index, smoking/alcohol/exercise habits, and menstrual status in women. Similar results were observed in participants with recorded birth weight. CONCLUSIONS: The present study indicates that individuals with small physique at birth might be at higher risk for hypertension and impaired glucose tolerance in middle age compared to those with large birth weight.

HvNax3--a locus controlling shoot sodium exclusion derived from wild barley (Hordeum vulgare ssp. spontaneum).

Previous work identified the wild barley (Hordeum vulgare ssp. spontaneum) accession CPI-71284-48 as being capable of limiting sodium (Na(+)) accumulation in the shoots under saline hydroponic growth conditions. Quantitative trait locus (QTL) analysis using a cross between CPI-71284-48 and a selection of the cultivated barley (H. vulgare ssp. vulgare) cultivar Barque (Barque-73, a moderate Na(+) excluder) attributed the control of the Na(+) exclusion trait from CPI-71284-48 to a single locus on the short arm of chromosome 7H, which was named HvNax3. The locus reduced shoot Na(+) accumulation by 10-25% in plants grown in 150 mM NaCl. Markers generated using colinearity with rice and Brachypodium, together with the analysis of introgression lines and F(2) and F(3) families, enabled HvNax3 to be mapped to a 1.3-cM interval. Genes from the corresponding rice and Brachypodium intervals encode 16 different classes of proteins and include several plausible candidates for HvNax3. The potential of HvNax3 to provide a useful trait contributing to salinity tolerance in cultivated barley is discussed.

Relationship between squamous cell carcinoma antigen and the clinical severity of allergic rhinitis caused by Dermatophagoides farinae and Japanese cedar pollen.

OBJECTIVES: Allergic rhinitis is known to be related to the Th2-type immune response, but no sensitive biomarker of severity yet exists. Serum squamous cell carcinoma antigen (SCCA) is clinically used as a popular tumor biomarker. We have demonstrated that SCCA is related to allergic diseases such as asthma. The purpose of the present study was to clarify the relationship between allergic rhinitis and SCCA, which had not yet been investigated. METHODS: We compared the serum SCCA levels in patients with allergic rhinitis due to Japanese cedar pollen and Dermatophagoides farinae with those in normal subjects. Thereafter, the correlations between the clinical severity of allergic rhinitis and the serum levels of SCCA were investigated. Furthermore, the influence of 8 variables (serum levels of SCCA, immunoglobulin E, eosinophil cationic protein, and eosinophils; age; gender; oral administration of antiallergic or antihistaminic agents; and use of nasal drops) in regard to the severity of allergic rhinitis was studied by a multiple regression analysis. RESULTS: The SCCA levels of the D farinae group were statistically higher than those of the control group, and they correlated with the severity of rhinitis. Among the 8 variables, only the SCCA level was found to be a predictive factor of severity on a multiple regression analysis. No relationship between SCCA level and Japanese cedar pollen allergy was demonstrated. CONCLUSIONS: These results suggest that the serum SCCA level may be a useful biomarker to evaluate the severity of allergic rhinitis caused by D farinae.

Genetics of Clubroot and Fusarium Wilt Disease Resistance in Brassica Vegetables: The Application of Marker Assisted Breeding for Disease Resistance.

The genus Brassica contains important vegetable crops, which serve as a source of oil seed, condiments, and forages. However, their production is hampered by various diseases such as clubroot and Fusarium wilt, especially in Brassica vegetables. Soil-borne diseases are difficult to manage by traditional methods. Host resistance is an important tool for minimizing disease and many types of resistance (R) genes have been identified. More than 20 major clubroot (CR) disease-related loci have been identified in Brassica vegetables and several CR-resistant genes have been isolated by map-based cloning. Fusarium wilt resistant genes in Brassica vegetables have also been isolated. These isolated R genes encode the toll-interleukin-1 receptor/nucleotide-binding site/leucine-rice-repeat (TIR-NBS-LRR) protein. DNA markers that are linked with disease resistance allele have been successfully applied to improve disease resistance through marker-assisted selection (MAS). In this review, we focused on the recent status of identifying clubroot and Fusarium wilt R genes and the feasibility of using MAS for developing disease resistance cultivars in Brassica vegetables.

Focal segmental glomerulosclerosis in which urinary protein improved after surgical treatment for acromegaly: a case report.

BACKGROUND: Focal segmental glomerulosclerosis is characterized by partial (segmental) sclerotic lesions in some glomeruli (focal). Primary focal segmental glomerulosclerosis is generally considered resistant to steroid therapy. However, acromegaly is a disease that causes peculiar facial features, body types, and metabolic abnormalities due to the excessive secretion of growth hormone by a pituitary adenoma. Growth hormone has been reported to be involved in glomerular cell growth, mesangial proliferation, and glomerulosclerosis in the kidney. CASE PRESENTATION: We report a case of a Japanese patient with focal segmental glomerulosclerosis in whom decreased urinary protein was observed after surgical treatment for acromegaly. CONCLUSION: The patient's urinary protein improved as the concentration of growth hormone/insulin-like growth factor 1 decreased.

Determination of symptoms associated with hiesho among young females using hie rating surveys.

OBJECTIVE: Hie (cold sensation) is one of the most well-known health complaints in Japan and elsewhere in East Asia. Those who suffer from severe hie are considered to have hiesho (cold disorder). This study was conducted to determine symptoms associated with hie in young females using a survey consisting of the hie scale and hie diary. METHODS: Two hundred and seventy-one participants were included for the analysis. Survey forms were distributed to the participants. Diagnosis of hiesho was determined by using the hie scale. A discriminant score of over -0.38 was considered hiesho. The Short Form-8 Health Survey Standard Version (SF-8) was used to measure health-related quality of life (QOL). The participants were also asked to respond to the questionnaire evaluating 14 physical and emotional symptoms, utilizing a six-level Likert scale item. RESULTS: The 1st factor (hie factor) was correlated with hie (r = 0.546), dry mouth (r = 0.332), lower-extremity edema (r = 0.450), headrushes (r = 0.470), shoulder stiffness (r = 0.311), headrushes with chills (r = 0.726), and fatigue (r = 0.359). Cronbach's α of the 1st factor was 0.748, which indicated reliability between the items. When hie factor was the dependent variable, standardized partial regression coefficient was ß = -0.387 for physical component score (P < 0.001) and ß = -0.243 for mental component score (P < 0.001). CONCLUSION: This study indicated that hiesho symptoms among young female adults were associated with bodily pain and general health perceptions of the SF-8 QOL survey.

Effect of Different Dosages of ST36 Indirect Moxibustion on the Skin Temperature of the Lower Legs and Feet.

Background: Indirect moxibustion (IM) has been previously performed between the spinous process while recording skin temperature of the trunk. However, moxibustion is often applied not only to acupuncture points on the back, but also to points located on the limbs. Thus, there is a need to investigate skin temperature (ST) responses following IM applied to the limbs. Methods: In Experiment 1 (Exp 1), subjects were randomly assigned to three groups: the left IM stimulation, right IM stimulation and control groups. In Experiment 2 (Exp 2), the subjects underwent two experimental sessions consisting of a single stimulation of IM or triple stimulations of IM. The IM stimulation was administered to the ST36 acupuncture point. A thermograph was used to obtain the ST on the lower limbs. Results: In Exp 1, the ST of the lower limbs increased in the stimulation groups whereas there was no increase in the non-stimulation group. In Exp 2, no significant response occurred between the single and triple stimulation of IM groups for all observed sites except for the left ankle ST. Conclusions: Lower limb ST increased following IM application to the ST36 point. No difference was observed between the dosage of the stimulation and ST responses.

Extraction of items identifying hiesho (cold disorder) and their utility in young males and females.

OBJECTIVE: Hie (cold sensation) is one of the most common health complaints in Japan. Those who suffer from severe hie are considered as having hiesho (cold disorder). However, exact hiesho symptoms have not been defined clearly and the decision as to whether a person suffers from hiesho is subjective and based on self-awareness. The study was conducted in attempt to develop a standardized hiesho diagnostic scale. METHODS: Subjects comprised 1 146 students. From the self-awareness of hiesho symptoms, males and females were divided into hiesho and non-hiesho groups. Physical, behavioral and adaptive characteristics were compared using the 24-item questionnaire (four-grade survey) and indicators for hiesho symptoms were extracted. Based on the scores, a receiver operating characteristic curve was drawn for the total ordinal scale score of the extracted items in relation to the presence and absence of hiesho symptoms, and an optimal cutoff value was determined. RESULTS: The self-awareness of having hiesho was found in 23.2% males and in 55.6% females. The sensitivity was 84.5% for males and 83.3% for females in the hiesho groups, and the specificity was 86.0% for males and 85.2% for females in the non-hiesho groups. CONCLUSION: A questionnaire consisting of the extracted items may be useful to identify hiesho in young males and females with a high level of accuracy.

Lack of adaptation to a new host in a generalist herbivore: implications for host plant resistance to twospotted spider mites in cotton.

BACKGROUND: The twospotted spider mite (Tetranychus urticae Koch) is an important pest of cotton. This pest has a broad host range, but when changing between hosts an initial decline in fitness often occurs. This is usually followed by an increase in fitness after rapid adaptation to the new host, usually within five generations. RESULTS: The generality of this adaptive response was tested by assessing elements of fitness when mites were reared on a host to which they were adapted (Gossypium hirsutum L. cv. Sicot 71) or on a new host, Gossypium arboreum L. (accession BM13H). In a first experiment, mites reared on the new host for ten generations showed declining immature survival compared with those reared on the adapted host. In a second experiment, the intrinsic capacity for increase of mites cultured on the new host for six generations was significantly lower than that of mites cultured on the adapted host for six generations and then transferred to the new host. Hence, exposure to the new host for six or ten generations resulted in declining fitness. CONCLUSION: This 'negative adaptation' indicates robust antibiosis traits in G. arboreum accession BM13H, which therefore have value in developing mite-resistant G. hirsutum cultivars.

Jasmonic acid is associated with resistance to twospotted spider mites in diploid cotton (Gossypium arboreum).

The twospotted spider mite (Tetranychus urticae Koch) is capable of dramatically reducing the yield of cotton crops and is often difficult and expensive to control. This study investigated and compared two important plant hormones, jasmonic acid (JA) and salicylic acid (SA), as constitutive and/or induced defence response components in a mite susceptible commercial cotton cultivar, Sicot 71 (Gossypium hirsutum L.) and a resistant diploid cotton BM13H (Gossypium arboreum L.). Foliar application of JA and methyl jasmonate (MeJA) reduced the mite population and leaf damage but application of other potential elicitors, SA and methyl salicylate (MeSA) did not. The concentrations of JA and SA in leaf tissues of induced and non-induced Sicot 71 and BM13H were quantified by liquid chromatography coupled to electrospray ionisation tandem mass spectrometry (LC-ESI-MS/MS). The JA content was constitutively higher in BM13H than Sicot 71 and also highly induced by mite infestation in BM13H but not in Sicot 71. However, SA was not significantly induced in either BM13H or Sicot 71. The expression levels of JA related genes, LOX, AOS and OPR were measured by quantitative PCR and elevated expression levels of JA related genes were detected in mite-infested BM13H. Therefore, JA and MeJA were implicated as key biochemical components in both the constitutive and induced defence responses of BM13H to spider mites.