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PubMed2000

Induced plant defense responses against chewing insects. Ethylene signaling reduces resistance of Arabidopsis against Egyptian cotton worm but not diamondback moth.

The induction of plant defenses by insect feeding is regulated via multiple signaling cascades. One of them, ethylene signaling, increases susceptibility of Arabidopsis to the generalist herbivore Egyptian cotton worm (Spodoptera littoralis; Lepidoptera: Noctuidae). The hookless1 mutation, which affects a downstream component of ethylene signaling, conferred resistance to Egyptian cotton worm as compared with wild-type plants. Likewise, ein2, a mutant in a central component of the ethylene signaling pathway, caused enhanced resistance to Egyptian cotton worm that was similar in magnitude to hookless1. Moreover, pretreatment of plants with ethephon (2-chloroethanephosphonic acid), a chemical that releases ethylene, elevated plant susceptibility to Egyptian cotton worm. By contrast, these mutations in the ethylene-signaling pathway had no detectable effects on diamondback moth (Plutella xylostella) feeding. It is surprising that this is not due to nonactivation of defense signaling, because diamondback moth does induce genes that relate to wound-response pathways. Of these wound-related genes, jasmonic acid regulates a novel beta-glucosidase 1 (BGL1), whereas ethylene controls a putative calcium-binding elongation factor hand protein. These results suggest that a specialist insect herbivore triggers general wound-response pathways in Arabidopsis but, unlike a generalist herbivore, does not react to ethylene-mediated physiological changes.

Adaptation, Physiological↗
PubMed1972

The relationship of the peroxidative indoleacetic Acid oxidase system to in vivo ethylene synthesis in cotton.

Since peroxidase and manganese have been implicated in both auxin destruction and ethylene production, the effect of auxins and high tissue levels of manganese on the peroxidative indoleacetic acid oxidase system and the internal level of ethylene was determined in cotton (Gossypium hirsutum L. cv. Watson GL-7). The highest level of manganese tested produced manganese toxicity symptoms, including necrotic lesions, accompanied by an increase in internal ethylene levels at about 15 days after treatment initiation. Statistically significant increases in indoleacetic acid oxidase and peroxidase activity were first observed 2 days later and were paralleled by tissue manganese levels above 7.4 milligrams per gram dry weight and internal ethylene levels of 0.77 microliters per liter air. Eight hours after application of 2,4-dichlorophenoxyacetic acid or indoleacetic acid, the internal levels of ethylene were increased to above 6.6 microliters per liter air in cotton plants, and levels of this magnitude were maintained for a 72-hour period of observation. Modification of peroxidase and indoleacetic acid oxidase activity in auxintreated plants definitely occurred well after the elevation of internal ethylene levels. While ethylene levels and indoleacetic acid oxidase activity were increased by both experimental approaches, the earlier appearance of increased ethylene indicates that the peroxidative indoleacetic acid oxidase system in cotton is not involved in ethylene synthesis or that this enzyme is not the rate-limiting factor when ethylene synthesis is increased. Ethylene, as well as auxin destruction, may be involved in some of the long term plant responses to toxic levels of manganese. The findings also suggest that auxin-induced ethylene may play a role in the elevation of peroxidase and indoleacetic acid oxidase activity eventually seen in extracts of plants treated with auxins. The data support the assumption that the enzymatic portion of the indoleacetic acid oxidase system in cotton is a peroxidase.

Journal Article↗
PubMed1983

Ultrastructural and chemical evidence that the cell wall of green cotton fiber is suberized.

Green cotton (Gossypium hirsutum L.) fibers were shown by electron microscopy to have numerous thin concentric rings around the lumen of the cell. These rings possessed a lamellar fine structure characteristic of suberin. LiA1D(4) depolymerization and gas chromatography-mass spectrometry analysis showed the presence of a suberin polymer in the green cotton with the major aliphatic monomers being omega-hydroxydocosanoic acid (70%) and docosanedoic acid (25%). Ordinary white cotton was shown by chemical and ultrastructural examination to be encircled by a thin cuticular polymer containing less than 0.5% of the aliphatic components found in green cotton.

Journal Article↗
PubMed1985

Accumulation of heat shock proteins in field-grown cotton.

Cotton (Gossypium hirsutum L.) plants grown under field water deficits exhibited an 80 to 85% reduction in leaf area index, plant height, and dry matter accumulation compared with irrigated controls. Midday photosynthetic rates of dryland plants decreased 2-fold, and canopy temperatures increased to 40 degrees C at 80 days after planting compared with canopy temperatures of 30 degrees C for irrigated plants. Leaves from dryland plants which had exhibited canopy temperatures of 40 degrees C for several weeks accumulated stainable levels of polypeptides with apparent molecular weights of 100, 94, 89, 75, 60, 58, 37, and 21 kilodaltons. These polypeptides did not accumulate in leaves from irrigated plants.Addition of [(35)S]methionine to leaves of growth chamber-grown cotton plants and subsequent incubation at 40 degrees C for 3 hours radiolabeled polypeptides with molecular weights similar to those that accumulate in dryland cotton leaves. These data suggest that the proteins which accumulate in water-stressed cotton leaves at elevated temperatures (40 degrees C) are heat shock proteins and that these proteins can accumulate to substantial levels in field-stressed plants.

Journal Article↗
PubMed2006

Accumulation of genome-specific transcripts, transcription factors and phytohormonal regulators during early stages of fiber cell development in allotetraploid cotton.

Gene expression during the early stages of fiber cell development and in allopolyploid crops is poorly understood. Here we report computational and expression analyses of 32 789 high-quality ESTs derived from Gossypium hirsutum L. Texas Marker-1 (TM-1) immature ovules (GH_TMO). The ESTs were assembled into 8540 unique sequences including 4036 tentative consensus sequences (TCs) and 4504 singletons, representing approximately 15% of the unique sequences in the cotton EST collection. Compared with approximately 178 000 existing ESTs derived from elongating fibers and non-fiber tissues, GH_TMO ESTs showed a significant increase in the percentage of genes encoding putative transcription factors such as MYB and WRKY and genes encoding predicted proteins involved in auxin, brassinosteroid (BR), gibberellic acid (GA), abscisic acid (ABA) and ethylene signaling pathways. Cotton homologs related to MIXTA, MYB5, GL2 and eight genes in the auxin, BR, GA and ethylene pathways were induced during fiber cell initiation but repressed in the naked seed mutant (N1N1) that is impaired in fiber formation. The data agree with the known roles of MYB and WRKY transcription factors in Arabidopsis leaf trichome development and the well-documented phytohormonal effects on fiber cell development in immature cotton ovules cultured in vitro. Moreover, the phytohormonal pathway-related genes were induced prior to the activation of MYB-like genes, suggesting an important role of phytohormones in cell fate determination. Significantly, AA sub-genome ESTs of all functional classifications including cell-cycle control and transcription factor activity were selectively enriched in G. hirsutum L., an allotetraploid derived from polyploidization between AA and DD genome species, a result consistent with the production of long lint fibers in AA genome species. These results suggest general roles for genome-specific, phytohormonal and transcriptional gene regulation during the early stages of fiber cell development in cotton allopolyploids.

Arabidopsis Proteins↗
PubMed1985

Responsiveness of pineal N-acetyltransferase and melatonin in the cotton rat exposed to either artificial or natural light at night.

In three separate experiments, the effect of acute exposure to either artificial or natural light during darkness of pineal N-acetyltransferase (NAT) activity and melatonin content was studied in the cotton rat (Sigmodon hispidus). The exposure of animals to an artificial-light irradiance of 160,000 microW/cm2 during darkness for either 1 s, 5 s, or 30 min was followed by a precipitous decline in pineal NAT activity and melatonin content when measured at either 15 or 30 min after light onset. When cotton rats were acutely exposed to light at night for 5 s, irradiances of either 3.2, 32, 320, and 3,200 did not suppress either pineal NAT or melatonin 30 min later; however, if the 5-s exposure had an irradiance of either 32,000 or 160,000 microW/cm2, the pineal enzyme activity and indole content were depressed. Moonlight, which had a maximal irradiance of 0.32 microW/cm2, was unable to suppress pineal NAT activity and melatonin content even when the animals were exposed to the moonlight for 30 min. The treatment of cotton rats with either norepinephrine or its agonist, isoproterenol, before their exposure to light at night retarded slightly the suppressive effect of light on the pineal constituents measured. Also, these drug treatments suppressed the pre-exposure levels of both NAT activity and melatonin content in the cotton rat pineal gland.

Acetyltransferases↗
PubMed2025

Polyploidy-mediated variations in glutamate receptor proteins linked to Fusarium wilt resistance in upland cotton.

Cotton production in the US faces a serious threat from Fusarium oxysporum f. sp. vasinfectum race 4 (FOV4), a soil-borne fungus causing Fusarium wilt by infecting the roots and vascular system of susceptible cotton, leading to rapid wilting and death. Here, we investigate genetic mechanisms of resistance to FOV4 in the highly resistant upland cotton genotype "U1" using an early-generation segregating biparental population ("U1" × "CSX8308") with comprehensive genomic resources. Reference-grade genomic assemblies of the parents revealed minor structural variations between "U1" haplotypes, a high degree of collinearity at chromosome synteny and micro-synteny levels, and significant divergence from "CSX8308" with 8.9 million SNPs. QTL analysis identified significant markers on chromosomes D03 and A02 linked to reduced Fusarium wilt severity. Within these regions, two glutamate-receptor-like (GLR) genes showed structural variation and overlapped between translocated segments on A02 and D03, suggesting a rare but important reinforcing effect of parallel evolution between susceptible and resistant genotypes. Transcriptome profiles of "U1" under FOV4 infection reveal activation of calcium-binding proteins and transcription factors regulating plant hormones (ethylene, abscisic acid, jasmonic acid, and salicylic acid), along with enzymes involved in cell wall remodeling and phytoalexin production. Advancing cotton improvement depends on incorporating durable genetic disease resistance into high-yielding, high-quality cultivars.

Fusarium↗
PubMed2000

Use of cotton rats to evaluate the efficacy of antivirals in treatment of measles virus infections.

No practical animal models for the testing of chemotherapeutic or biologic agents identified in cell culture assays as being active against measles virus (MV) are currently available. Cotton rats may serve this purpose. To evaluate this possibility, 5-ethynyl-1-beta-D-ribofuranosylimidazole-4-carboxamide (EICAR) and poly(acrylamidomethyl propanesulfonate) (PAMPS), two compounds that have been reported to inhibit MV in vitro, and ribavirin, an established antiviral drug with MV-inhibitory activity, were evaluated for their antiviral activities against MV and respiratory syncytial virus (RSV) in tissue culture and in hispid cotton rats. A single administration of PAMPS markedly inhibited pulmonary RSV or MV replication (>3 log(10) reduction in pulmonary titer compared to that for controls), but only if this compound was administered intranasally at about the time of virus inoculation. Both EICAR and ribavirin exhibited therapeutic activity against RSV and MV in cotton rats when they were administered parenterally. However, both of these compounds were less effective against MV. On the basis of the pulmonary virus titers on day 4 after virus inoculation, the minimal efficacious dose of EICAR against MV (120 mg/kg of body weight/day when delivered intraperitoneally twice daily) appeared to be three times lower against this virus than that of ribavirin delivered at a similar dose (i.e., 360 mg/kg/day). These findings correlated with those obtained in vitro. The data obtained suggest that cotton rats may indeed be useful for the initial evaluation of the activities of antiviral agents against MV.

Animals↗
PubMed1981

Citric Acid Fermentation by Aspergillus niger on Low Sugar Concentrations and Cotton Waste.

The possible use of cotton waste as a carbohydrate source of citric acid production by Aspergillus niger was examined. No citric acid was produced when A. niger was grown on cotton waste as a sole carbon source. In two-stage fermentations, however, mycelium obtained from surface cultures in cotton waste medium yielded more citric acid when transferred to sucrose-containing media than when directly inoculated to sucrose-containing media. It is concluded that cotton waste can be used for saving sucrose and for increasing yields of citric acid fermentation by A. niger.

Journal Article↗
PubMed1983

Endotoxins in baled cottons and airborne dusts in textile mills in the People's Republic of China.

Bulk cotton samples and airborne vertical elutriated cotton dusts were obtained from textile mills in Shanghai, People's Republic of China. Analysis of endotoxin contents revealed that baled cottons which were grown in different countries varied in endotoxin contamination. The two textile mills, which operated at similar overall airborne dust levels, differed markedly in the levels of airborne endotoxins. The data suggest that the biological activity or "toxicity" of airborne cotton dusts may not be correlated directly with gravimetric dust levels.

Air Pollutants, Occupational↗
PubMed1994

Introduction of a Lepidopteran-Specific Insecticidal Crystal Protein Gene of Bacillus thuringiensis subsp. kurstaki by Conjugal Transfer into a Bacillus megaterium Strain That Persists in the Cotton Phyllosphere.

A lepidopteran toxin gene of the entomopathogen Bacillus thuringiensis subsp. kurstaki HD-1 was introduced into a cotton leaf-colonizing Bacillus megaterium strain, RS1, by conjugal transfer. Rifampin- and nalidixic acid-resistant colonies obtained after cell mating were screened for crystal production by microscopy. A transcipient, B. megaterium RS1-43, was selected by this procedure. Southern blot hybridization with both total DNA and HindIII-digested DNA of the transcipient showed positive signals with a cryIA-specific probe, suggesting the transfer of the lepidopteran-specific cryIA(a) gene. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis confirmed the presence of the 134-kDa toxic crystal protein specific to lepidopteran larvae in the transcipient. Survival studies with cultures of the transcipient at both vegetative and postvegetative growth stages on cotton, under field conditions, suggested that the bacterium persisted on the leaf surfaces for more than 28 days, with a gradual decline in the population level with time, while the donor, B. thuringiensis subsp. kurstaki, disappeared completely after 7 days following inoculation. An in situ differential crystal-staining technique indicated the production of crystals by the transcipient on cotton leaf surfaces for about 30 days. Leaf bioassays of cotton plants inoculated with a single spray of the transcipient showed 75- to 96% mortality to the first-instar larvae of Heliothis armigera up to 21 days, and this single spray conferred total protection to the plants for about 30 days by causing an antifeeding effect on the remaining larvae.

Journal Article↗
PubMed2004

VdNEP, an elicitor from Verticillium dahliae, induces cotton plant wilting.

Verticillium wilt is a vascular disease of cotton. The causal fungus, Verticillium dahliae, secretes elicitors in culture. We have generated approximately 1,000 5'-terminal expressed sequence tags (ESTs) from a cultured mycelium of V. dahliae. A number of ESTs were found to encode proteins harboring putative signal peptides for secretion, and their cDNAs were isolated. Heterologous expression led to the identification of a protein with elicitor activities. This protein, named V. dahliae necrosis- and ethylene-inducing protein (VdNEP), is composed of 233 amino acids and has high sequence identities with fungal necrosis- and ethylene-inducing proteins. Infiltration of the bacterially expressed His-VdNEP into Nicotiana benthamiana leaves resulted in necrotic lesion formation. In Arabidopsis thaliana, the fusion protein also triggered production of reactive oxygen species and induced the expression of PR genes. When added into suspension cultured cells of cotton (Gossypium arboreum), the fusion protein elicited the biosynthesis of gossypol and related sesquiterpene phytoalexins at low concentrations, and it induced cell death at higher concentrations. On cotton cotyledons and leaves, His-VdNEP induced dehydration and wilting, similar to symptoms caused by a crude preparation of V. dahliae elicitors. Northern blotting showed a low level of VdNEP expression in the mycelium during culture. These data suggest that VdNEP is a wilt-inducing factor and that it participates in cotton-V. dahliae interactions.

Arabidopsis↗
PubMed1987

Effectiveness of topically administered neutralizing antibodies in experimental immunotherapy of respiratory syncytial virus infection in cotton rats.

Initial studies of the prophylactic effect of parenterally administered respiratory syncytial virus (RSV)-neutralizing antibodies in cotton rats indicated that virus replication in lung tissues was restricted when animals with preexisting antibody titers in serum of 1:100 or more (as measured by plaque reduction) were challenged intranasally with 10(4) PFU of virus. Subsequently, a therapeutic effect of parenterally administered RSV antibodies (present in human gamma globulin) was demonstrated in both cotton rats and owl monkeys. Parenteral inoculation of RSV-infected cotton rats or owl monkeys with purified human immunoglobulin licensed for intravenous administration in humans (IVIG) effected a 10(-1.7) to 10(-2.7) reduction in the level of pulmonary virus at the height of infection. Because of these encouraging results, we examined topical administration of IVIG to determine whether it was also effective and whether it offered an advantage over the parenteral route with regard to simplicity and the dose required for full therapeutic effect. IVIG (0.025 g/kg) administered topically by the intranasal route to anesthetized cotton rats at the height of RSV infection effected a 10(2.2)-fold reduction in viral titers of pulmonary tissues and a complete clearance of detectable virus in 92% of the animals within 24 h. In contrast, 4 g of IVIG per kg was required to produce a comparable therapeutic effect when the material was administered parenterally. Thus, the therapeutic effect of IVIG was 160 times greater by the topical route than by parenteral inoculation.

Administration, Topical↗
PubMed1995

Recombinant type 5 adenoviruses expressing bovine parainfluenza virus type 3 glycoproteins protect Sigmodon hispidus cotton rats from bovine parainfluenza virus type 3 infection.

Cotton rats were used to study the replication and pathogenesis of bovine parainfluenza virus type 3 (bPIV3) and to test the efficacy of the F and HN glycoproteins in modulating infection. In vitro cultures of cotton rat lung cells supported the growth of bPIV3 as shown by virus recovery, immunofluorescence, immunoprecipitation, and syncytium induction. Intranasal (i.n.) inoculation of cotton rats with 10(7) PFU resulted in peak recovery of virus after 2 days (8 x 10(4) PFU/g of lung tissue) and significant bronchiolitis with lymphocyte infiltration 5 to 7 days postinfection. Immunohistochemical staining of lungs and trachea demonstrated that virus antigen-positive cells increased in frequency over the course of infection to a maximum on day 5. Serum antibody responses were evaluated by enzyme-linked immunosorbent assays (ELISA), hemagglutination inhibition (HAI), and serum neutralization (SN). Following a single i.n. inoculation, serum antibody levels were 1/40,960, 1/32, and 1/80, as detected by ELISA, HAI, and SN, respectively. When an intramuscular inoculation of 10(7) PFU was administered 10 days prior to the i.n. inoculation, a secondary response which resulted in an ELISA titer of 1/163,000, an HAI titer of 1/640, and an SN titer of 1/512 was induced. IN inoculation of recombinant adenoviruses type 5 containing the bPIV3 F or HN protein or a combination of the two viruses protected cotton rats from bPIV3 challenge. Protection was evaluated serologically by ELISA, HAI, and SN titers, histopathology, immunohistochemistry, and virus recovery.

Adenoviruses, Human↗
PubMed2003

Attenuated Salmonella enterica serovar Typhi and Shigella flexneri 2a strains mucosally deliver DNA vaccines encoding measles virus hemagglutinin, inducing specific immune responses and protection in cotton rats.

Measles remains a leading cause of child mortality in developing countries. Residual maternal measles antibodies and immunologic immaturity dampen immunogenicity of the current vaccine in young infants. Because cotton rat respiratory tract is susceptible to measles virus (MV) replication after intranasal (i.n.) challenge, this model can be used to assess the efficacy of MV vaccines. Pursuing a new measles vaccine strategy that might be effective in young infants, we used attenuated Salmonella enterica serovar Typhi CVD 908-htrA and Shigella flexneri 2a CVD 1208 vaccines to deliver mucosally to cotton rats eukaryotic expression plasmid pGA3-mH and Sindbis virus-based DNA replicon pMSIN-H encoding MV hemagglutinin (H). The initial i.n. dose-response with bacterial vectors alone identified a well-tolerated dosage (1 x 10(9) to 7 x 10(9) CFU) and a volume (20 micro l) that elicited strong antivector immune responses. Animals immunized i.n. on days 0, 28, and 76 with bacterial vectors carrying DNA plasmids encoding MV H or immunized parenterally with these naked DNA vaccine plasmids developed MV plaque reduction neutralizing antibodies and proliferative responses against MV antigens. In a subsequent experiment of identical design, cotton rats were challenged with wild-type MV 1 month after the third dose of vaccine or placebo. MV titers were significantly reduced in lung tissue of animals immunized with MV DNA vaccines delivered either via bacterial live vectors or parenterally. Since attenuated serovar Typhi and S. flexneri can deliver measles DNA vaccines mucosally in cotton rats, inducing measles immune responses (including neutralizing antibodies) and protection, boosting strategies can now be evaluated in animals primed with MV DNA vaccines.

Animals↗
PubMed2005

Pathogenesis of human metapneumovirus lung infection in BALB/c mice and cotton rats.

Human metapneumovirus (hMPV) is a newly described member of the Paramyxoviridae family causing acute respiratory tract infections, especially in young children. We studied the pathogenesis of this viral infection in two experimental small animal models (BALB/c mice and cotton rats). Significant viral replication in the lungs of both animals was found following an intranasal challenge of 10(8) 50% tissue culture infectious doses (TCID50) and persisted for <2 and <3 weeks in the case of cotton rats and mice, respectively. Peak viral loads were found on day 5 postinfection in both mice (mean of 1.92 x 10(7) TCID50/g lung) and cotton rats (mean of 1.03 x 10(5) TCID50/g). Clinical symptoms consisting of breathing difficulties, ruffled fur, and weight loss were noted in mice only around the time of peak viral replication. Most significant pulmonary inflammatory changes and peak expression of macrophage inflammatory protein 1alpha, gamma interferon, and RANTES occurred at the time of maximal viral replication (day 5) in both models. Cellular infiltration occurred predominantly around and within alveoli and persisted for at least 21 days in mice, whereas it was more limited in time with more peribronchiolitis in cotton rats. Both animal models would be of great value in evaluating different therapeutic agents, as well as vaccine candidates against hMPV.

Animals↗
PubMed2005

The cotton rat provides a novel model to study genital herpes infection and to evaluate preventive strategies.

Prevention of genital herpes and other sexually transmitted infections (STI) is a critical health priority because of the overwhelming impact on women and infants and the epidemiological association with human immunodeficiency virus (HIV)/AIDS. Small animal models are essential for evaluating strategies for prevention or treatment of STI. Neither the murine nor the guinea pig model of genital herpes fully recapitulates human disease. We demonstrate that herpes simplex virus type 2 (HSV-2) readily infects inbred cotton rats (Sigmodon hispidus). Consistent infection does not require pretreatment with medroxyprogesterone, and primary disease resembles that observed in humans. The animals develop genital lesions and fully recover. During primary infection, viral DNA is also detected in liver, lungs, brain, and kidneys. Clinical self-limited recurrences occur spontaneously but may also be induced by dexamethasone. Pretreatment of cotton rats with PRO 2000 gel, a candidate vaginal microbicide being evaluated in clinical trials to prevent HSV and HIV, protects cotton rats from HSV. Together, these studies suggest that the cotton rat may provide an excellent model to study genital herpes and to evaluate preventive strategies.

Animals↗
PubMed1991

Cotton-wool spots and retinal light sensitivity in diabetic retinopathy.

In 14 eyes of 14 patients with diabetic retinopathy the light sensitivity of retinal cotton-wool spots was studied by computerised perimetry, and the visual field data were accurately correlated with the corresponding morphology as seen on fundus photographs and fluorescein angiograms. In 12 of the eyes the examinations were repeated within one year in order to follow changes in retinal light sensitivity during the evolution of the lesions. Retinal cotton-wool spots were in all eyes associated with localised non-arcuate scotomata in the visual field. In four eyes the cotton-wool spots disappeared within three months of the first examination, and in two of these cases the corresponding scotomata disappeared together with the morphological lesions. In eight eyes the cotton-wool spots (and the corresponding scotomata) had not resolved one year after the first examination. The mean blood pressure showed no significant difference between the patients in whom the lesions resolved within three months and the patients in whom the lesions persisted longer.

Diabetic Retinopathy↗