MiR-129 is involved in the occurrence of uterine fibroid through inhibiting TET1.

OBJECTIVE: To detect the expressions of micro ribonucleic acid (miR)-129 and its target gene in uterine fibroid tissues and to investigate the role of miR-129 in the occurrence of uterine fibroid. PATIENTS AND METHODS: The expressions of miR-129 and its target gene ten-eleven translocation 1 (TET1) were detected via quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Dual-luciferase reporter gene and Western blotting were used to verify the regulatory relation between miR-129 and target gene. The effects of miR-129 on the proliferation, apoptosis, cycle and extracellular matrix (ECM) of uterine fibroid cells were investigated via transfection with miR-129 mimics and TET1 small-interfering RNA (siRNA). RESULTS: MiR-129 was lowly expressed in uterine fibroid. The expression of miR-129 was regulated by sex hormones. The highly expressed miR-129 promoted apoptosis and inhibited proliferation through reducing the low expression of TET1. At the same time, miR-129 affected the accumulation of ECM. CONCLUSIONS: The expression of miR-129 in uterine fibroid is lower, and the proliferation capacity of tumor cells is enhanced, thus promoting the occurrence and development of uterine fibroid.

Phoretic dispersal of armored scale crawlers (Hemiptera: Diaspididae).

Dispersal and colonization of new areas by armored scale insects (Hemiptera: Diaspididae) is achieved by mobile first-instar nymphs, called crawlers. Few studies have considered the actual mechanisms by which crawlers disperse, and although crawlers are capable of actively wandering over short distances (generally < 1 m), their dispersal over longer distances has been thought to be wind-mediated. Here, we present evidence of a potentially more important means of dispersal over longer distances (> 1 m). We first confirmed that crawlers of four species of Diaspididae [Abgrallaspis aguacatae Evans, Watson & Miller; Hemiberlesia lataniae (Signoret); Aspidiotus nerii Bouché; and Diaspidiotus perniciosus (Comstock)] have four hairs on the end of each of their legs and that each of these hairs ends in a suction cup-like structure, reminiscent of the attachment structures possessed by phoretic mites. In a controlled environment, using crawlers of A. nerii, we then showed that the crawlers use these structures to attach themselves to three different insect species [Musca domestica L., Cryptolaemus montrouzieri Mulsant and Linepithema humile (Mayr)] and can effectively be moved phoretically by these insects. Crawlers can remain attached to flying insects for considerable periods of time, suggesting that this may be an important means of dispersal for armored scale insects. The importance of phoresy for diaspidid dispersal in the field remains to be determined.

High levels of exotic armored scales on imported avocados raise concerns regarding USDA-APHIS' phytosanitary risk assessment.

Between 1914 and 2007, a quarantine protected California avocado, Persea americana Mill., groves from pests that might be introduced into the state along with fresh, imported avocados. Soon after Mexican avocados were first allowed entry on 1 February 2007, live specimens of several species of armored scales (Hemiptera: Diaspididae) not believed to be present in California were detected on 'Hass' avocados entering the state from Mexico. Initially, the California Department of Food and Agriculture (CDFA) prevented avocados infested with these scales from entering the state or required that they be fumigated with an approved treatment such as methyl bromide. After a Science Advisory Panel meeting in May 2007, U.S. Department of Agriculture-Animal and Plant Health Inspection Service (USDA-APHIS) reaffirmed its position that armored scales on shipments of fruit for consumption (including avocados) pose a "low risk" for pest establishment. In compliance with APHIS protocols, as of 18 July 2007, CDFA altered its policy to allow shipments of scale-infested avocados into the state without treatment. Here, we report on sampling Mexican avocados over an 8-mo period, September 2007-April 2008. An estimated 67 million Mexican Hass avocados entered California over this period. Based on samples from 140 trucks containing approximately 15.6% of this volume of fruit, we estimate that approximately 47.6 million live, sessile armored scales and an additional 20.1 million live eggs and crawlers were imported. We found eight probable species of armored scales in the samples, seven of these are not believed to occur in California; 89.3% of the live scales were Abgrallaspis aguacatae Evans, Watson and Miller, a recently described species. In contrast to the USDA-APHIS opinion, we believe the volume of shipments and levels of live scales they contain present a significant risk to California's US$300 million avocado industry and to other crops that might become infested by one or more of these exotic species.

Amino acid fluctuations in young and old orange trees and their influence on glassy-winged sharpshooter (Homalodisca vitripennis) population densities.

The glassy-winged sharpshooter (GWSS) is an invasive insect pest in California that proliferated in citrus while incorporating many other plant species in its host range. Field studies were conducted from September 2002 to September 2003 in adjacent young and old orange groves to determine the influence of amino acid concentrations in the xylem fluid on relative densities of the xylophagous GWSS. Beginning in early September 2002, higher densities of adult GWSS were observed on young compared to old trees. This difference became increasingly pronounced through late October in conjunction with increasing concentrations of essential amino acids in xylem fluid of the young trees. Greater densities of adult GWSS remained on young trees through early February 2003. Thereafter, the population crashed unexpectedly, leaving only negligible numbers of GWSS on either young or old trees. Mean concentrations of the essential amino acids for insect growth and development were higher in young compared to old trees. Besides these essential amino acids, asparagine, serine, glutamine, and tyrosine were also significantly higher in young trees during the September-February period when GWSS was present. The pattern of elevated amino acid concentrations in young trees continued through the entire year irrespective of the presence or absence of GWSS. Principal component analysis followed by factor analysis revealed three factors for young or old orange trees that accounted for 81.6 and 78.9% of the total variation in the young and old tree analyses, respectively. Various groups of amino acids in different factors displayed peak or elevated levels in young trees corresponding to the increased densities of GWSS. The potential roles of these amino acids in GWSS host selection are discussed.

Effect of host plant Xylem fluid on growth, aggregation, and attachment of Xylella fastidiosa.

In the Temecula Valley of California the proximity of citrus groves to vineyards influences the incidence and severity of Pierce's disease (PD) in grapes, a disease caused by the gram-negative bacterium, Xylella fastidiosa. Although the glassy-winged sharpshooter (GWSS), the major insect vector of the bacterium, feeds on and moves back and forth between citrus groves and vineyards, there are no visible symptoms of disease caused by X fastidiosa in citrus. Previous evidences suggested that while grapevines are susceptible to the PD strain of X. fastidiosa, citrus trees are resistant or tolerant but could be a reservoir to harbor the pathogen for the GWSS acquisition. We investigated the mechanisms of host plant resistance/susceptibility by examining the in vitro effect of xylem fluid from grapefruit, orange, lemon, and grape on the growth, aggregation, and attachment of a X. fastidiosa strain isolated from grape. Our results revealed that xylem fluid from grapefruit, orange, and lemon trees caused the bacterial cells to form aggregations of large whitish clumps, whereas the xylem fluid from grape vines created a visible thick biofilm. The densities of X. fastidiosa cells in grapefruit xylem fluid treatment were significantly higher at 6, 8, and 9 d postinoculation compared with those in grape xylem fluid treatment. The cell densities of X. fastidiosa cultures in orange or lemon xylem fluid were generally lower than those in grape xylem fluid treatment, whereas citrus xylem fluid significantly inhibited X. fastidiosa biofilm formation compared to grape xylem fluid.

Phenology and demography of Homalodisca coagulata (Hemiptera: Cicadellidae) in southern California citrus and implications for management.

Populations of Homalodisca coagulata (Say) were sampled from citrus orchards in southern California, USA to characterize and quantify seasonal occurrences of nymphs and adults with the goal of identifying management opportunities through well-timed treatments and/or natural enemy releases. Higher densities of H. coagulata in 2001 contributed to a complete seasonal profile that began in early spring with the emergence of first instar nymphs and their progression through five nymphal instars lasting until mid-August. Adult emergence began in mid-June with peak adult densities attained from mid to late August followed by a gradual decline through autumn. A persistent and significant male bias was observed in the adult sex ratio from the time of first emergence through mid-October in oranges; the same trend was present in lemons, but with more variability. Adult densities gradually declined through the winter months into the following spring before rapidly increasing again in June as the 2002 spring generation of nymphs began emerging as adults. The seasonal timing of nymphs and adults in 2002 was nearly identical to that observed the previous year. Phenology data from both years were incorporated into a stochastic, temperature-dependent model that predicts the occurrences of H. coagulata stages through time. Applications of imidacloprid early in the spring generation of nymphs proved very effective at reducing nymphs and sustaining lower densities of adults through summer.

Influence of seasonal nitrogen nutrition fluctuations in orange and lemon trees on population dynamics of the glassy-winged sharpshooter (Homalodisca coagulata).

The glassy-winged sharpshooter (GWSS) is a xylem feeder that develops conspicuous, year-round populations in many citrus-producing regions of California. Field studies were conducted in a combined lemon and orange orchard to determine the influence of changing amino acid concentrations on relative densities of GWSS. Nineteen protein amino acids were detected in xylem fluid of both lemon and orange trees. Although annual profiles of total and essential amino acids were similar for each citrus species, mean concentrations were consistently higher in lemons than in oranges for most of the year, except for one critical period in late winter-early spring when concentrations were higher in oranges. Principal component analysis followed by factor analysis was performed individually on lemon and orange data sets to identify a reduced number of orthogonal factors composed of amino acids having similar seasonal profiles. Four factors were identified for each citrus species that accounted for 85% and 79% of the total variation in the orange and lemon analyses, respectively. These were then examined with respect to shifts in GWSS numbers that occurred asynchronously in lemons and oranges over the annual population cycle. Three distinctive number shifts were identified that included a peak in adult numbers in lemons during August 2001, significantly higher numbers in lemons relative to oranges during midwinter, and finally an increase in oranges of both adults and nymphs during spring 2002. Various groups of amino acids, i.e., factors, displayed peak annual or elevated levels during the intervals when shifts in GWSS numbers were occurring. Soluble protein levels in oranges and lemons did not correspond to shifting GWSS numbers as certain amino acids. However, soluble protein levels were higher in oranges during late winter/early spring when GWSS adults were sexually active. Potential roles of these amino acids and proteins in GWSS host selection are discussed.

Effect of urea fertilizer application on soluble protein and free amino acid content of cotton petioles in relation to silverleaf whitefly (Bemisia argentifolii) populations.

The impact of urea nitrogen fertilization on silverleaf whitefly, Bemisia argentifolii Bellows & Perring, population dynamics was examined in field-grown cotton (Gossypium hirsutum L.). Five urea nitrogen treatments were tested, consisting of soil applications of 0, 112, 168, and 224 kg nitrogen per hectare, and acombined soil-foliar application of 112:17 kg nitrogen per hectare. A positive response was observed between N application rates and the measured levels of nitrate N in petioles from mature cotton leaves. Similarly, a positive response was observed between N application rates and the numbers of adult and immature whiteflies appearing during population peaks. To determine whether these positive responses were related, we measured the levels of dietary N compounds (proteins and free amino acids) that would be available for insect nutrition in cotton petioles at the different N application rates. Sampling dates and N application treatments affected levels of soluble proteins in cotton petioles, and interactions between sampling dates and treatments were significant. Across all sampling dates, the relationship between N application rates and levels of soluble proteins was linear. Sampling dates also affected levels of total and individual free amino acids. Fertilizer treatments only affected levels of total amino acids, aspartate, asparagine, and arginine plus threonine. Levels of aspartate or asparagine and the N application rates were linearly correlated. No significant correlations were observed between levels of dietary N compounds in cotton petioles and numbers of whiteflies, either adults or immatures, on the cotton plants.

Seasonal population dynamics of the greenhouse whitefly Trialeurodes vaporariorum (Homoptera: Aleyrodidae) on strawberries in Southern California.

The greenhouse whitefly, Trialeurodes vaporariorum (Westwood), has recently become a major insect pest of strawberries in Southern California. The population dynamics of this pest were monitored over 2 yr in six commercial strawberry fields near the coastal communities of Oxnard and Ventura under two crop-production regimes, summer- and fall-planted strawberries. Adult whitefly numbers generally peaked during the February through May period for fall-planted strawberries and during the October through November period for summer-planted strawberries. Population densities varied greatly among fields within each regime and the differences were likely caused by surrounding alternate host crops.

Cross-talk between the signal pathways for pathogen-induced systemic acquired resistance and grazing-induced insect resistance.

Reducing phenylpropanoid biosynthesis in transgenic tobacco compromises systemic acquired resistance (SAR) to tobacco mosaic virus, while increasing phenylpropanoid biosynthesis enhances SAR. Surprisingly, transgenic tobacco plants compromised in SAR exhibit more effective grazing-induced systemic resistance to larvae of Heliothis virescens, whereas induced insect resistance is compromised in transgenic plants with elevated phenylpropanoid levels. Levels of the phenylpropanoid-derived signal salicylic acid are directly correlated with overall phenylpropanoid biosynthesis in this series of transgenic plants. Moreover, while pathogen-induced SAR is almost completely compromised in salicylic acid-deficient plants expressing the bacterial nahG salicylate hydroxylase gene, these plants show enhanced grazing-induced insect resistance compared to wild-type. Hence, suppression of grazing-induced insect resistance is mediated at least in part by salicylic acid and likely reflects salicylic acid inhibition of the synthesis and action of the wound signal jasmonic acid. We propose that the dual functions of salicylic acid contribute to a signal poise which constrains constitutive expression of disease and insect resistance mechanisms, and reciprocally switches their selective activation.

Inverse relationship between systemic resistance of plants to microorganisms and to insect herbivory.

Pre-inoculation of plants with a pathogen that induces necrosis leads to the development of systemic acquired resistance (SAR) to subsequent pathogen attack [1]. The phenylpropanoid-derived compound salicylic acid (SA) is necessary for the full expression of both local resistance and SAR [2] [3]. A separate signaling pathway involving jasmonic acid (JA) is involved in systemic responses to wounding and insect herbivory [4] [5]. There is evidence both supporting and opposing the idea of cross-protection against microbial pathogens and insect herbivores [6] [7]. This is a controversial area because pharmacological experiments point to negative cross-talk between responses to systemic pathogens and responses to wounding [8] [9] [10], although this has not been demonstrated functionally in vivo. Here, we report that reducing phenylpropanoid biosynthesis by silencing the expression of phenylalanine ammonialyase (PAL) reduces SAR to tobacco mosaic virus (TMV), whereas overexpression of PAL enhances SAR. Tobacco plants with reduced SAR exhibited more effective grazing-induced systemic resistance to larvae of Heliothis virescens, but larval resistance was reduced in plants with elevated phenylpropanoid levels. Furthermore, genetic modification of components involved in phenylpropanoid synthesis revealed an inverse relationship between SA and JA levels. These results demonstrate phenylpropanoid-mediated cross-talk in vivo between microbially induced and herbivore-induced pathways of systemic resistance.

Foliar oxidative stress and insect herbivory: Primary compounds, secondary metabolites, and reactive oxygen species as components of induced resistance.

Oxidative responses of plants to pathogens and other environmental stresses have received considerable recent attention. We propose that an oxidative response also occurs following attack by herbivores. Our data strongly indicate a shift in the oxidative status of soybean following herbivory by the insectHelicoverpa zea. Herbivory caused significant increases in lipid peroxidation and ·OH radical formation. The activity of several oxidative enzymes including lipoxygenases, peroxidase, diamine oxidase, ascorbate oxidase, and NADH oxidase I increased after herbivory on soybean. The enhanced production of phenolic compounds is indicated by an increase in the activity of phenylalanine ammonia lyase in wounded tissues. On the other hand, the level of soybean foliar antioxidants such as ascorbic acid, total carotenoids, nonprotein thiols, and catalase decreased significantly following herbivory. These results implicate primary compounds (e.g., ascorbic acid, proteins), secondary metabolites (e.g., phenolics), and reactive oxygen species (e.g., hydroxyl radical, hydrogen peroxide) as multiple components of induced resistance. The oxidative changes in the host plant correspond with increased oxidative damage in the midgut of insects feeding on previously wounded plants. Decreases in nonprotein thiols and reduced ascorbic acid occurred in midgut epithelial tissue from insects feeding on wounded plants compared to the insects on control plants. In contrast, midgut hydroperoxides and dehydroascorbic acid concentrations were greater in insects on wounded plants compared to their counterparts on control plants. We conclude that oxidative responses in soybean may have both positive and negative effects upon the host plant: a decrease in herbivory and an increase in oxidative damage to the plant. The salient benefit to the plant, in terms of insect resistance, is the relative balance between these opposing effects.

Induced resistance in soybean toHelicoverpa zea: Role of plant protein quality.

Resistance in soybean toHelicoverpa zea is comprised of both constitutive and inducible factors. In this study, we investigated the induction of resistance byH. zea in both greenhouse and field studies. In a greenhouse experiment, fourth-instarH. zea growth rates were reduced by 39% after 24 hr feeding and by 27% after 48 hr when larvae fed on previously wounded V3 foliage (cv. Forrest) compared with undamaged foliage. In a field study, the weight gain by larvae was more than 52% greater when larvae fed for 72 hr on undamaged R2/R3 soybean plants (cv. Braxton) compared to those that fed on previously wounded plants. A significant component of the induced resistance is due to a decline in the nutritional quality of foliar protein following foliar damage byH. zea. Foliar protein was extracted from damaged and undamaged foliage and incorporated into artificial diets. Larval growth was reduced 26% after four days and 49% after seven days on diets containing protein from damaged plants compared to larvae feeding on foliar protein from undamaged plants. Chemical analyses of protein quality also indicated a decline in quality in damaged plants compared to unwounded plants. Increases in lipoxygenase activity (53%), lipid peroxidation products (20%), and trypsin inhibitor content (34%) were observed in protein from wounded plants. Moreover, a 5.9% loss in free amines and 19% loss in total thiols occurred in protein from wounded plants. Larval feeding causes a significant increase in foliar lipoxygenase activity that varied among genotypes. Lipoxygenase isozymes were measured at pH 5.5, pH 7.0, and pH 8.5 in V3 stage plants of Forrest, Hark, D75-1069, and PI 417061 genotypes. Lipoxygenase activity in each genotype was significantly increased after 72 hr of larval feeding at each pH level tested, with the exception of lipoxygenase isozymes at pH 5.5 in genotype PI 417061. Larval feeding on R2/R3 stage plants (field-grown cv. Braxton) for six days also increased foliar lipoxygenase activity.

Potential role of lipoxygenases in defense against insect herbivory.

The potential role of the plant enzyme lipoxygenase in host resistance against the corn earwormHelicoverpa zea was examined. Lipoxygenase is present in most of the common host plants ofH. zea, with highest activity in the leguminous hosts such as soybean and redbean. Treatment of dietary proteins with linoleic acid and lipoxygenase significantly reduced the nutritive quality of soybean protein and soy foliar protein. Larval growth was reduced from 24 to 63% depending upon treatment. Feeding byH. zea on soybean plants caused damage-induced increases in foliar lipoxygenase and lipid peroxidation products. Larvae feeding on previously wounded plant tissue demonstrated decreased growth rates compared to larvae feeding on unwounded tissue. Midgut epithelium from larvae feeding on wounded tissues showed evidence of oxidative damage as indicated by significant increases in lipid peroxidation products and losses in free primary amines. The potential role of oxidative and nutritional stress as a plant defensive response to herbivory is discussed.