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PubMed2005

Delayed resistance to transgenic cotton in pink bollworm.

Transgenic crops producing Bacillus thuringiensis (Bt) toxins kill some key insect pests and thus can reduce reliance on insecticides. Widespread planting of such Bt crops increased concerns that their usefulness would be cut short by rapid evolution of resistance to Bt toxins by pests. Pink bollworm (Pectinophora gossypiella) is a major pest that has experienced intense selection for resistance to Bt cotton in Arizona since 1997. We monitored pink bollworm resistance to Bt toxin for 8 years with laboratory bioassays of strains derived annually from 10-17 cotton fields statewide. Bioassay results show no net increase from 1997 to 2004 in the mean frequency of pink bollworm resistance to Bt toxin. A synthesis of experimental and modeling results suggests that this delay in resistance can be explained by refuges of cotton without Bt toxin, recessive inheritance of resistance, incomplete resistance, and fitness costs associated with resistance.

Animals↗
PubMed2006

The cotton fiber zinc-binding domain of cellulose synthase A1 from Gossypium hirsutum displays rapid turnover in vitro and in vivo.

Little is known about the assembly and turnover of cellulose synthase complexes commonly called rosettes. Recent work indicates that rosette assembly could involve the dimerization of CesA (cellulose synthase catalytic subunit) proteins regulated by the redox state of the CesA zinc-binding domain (ZnBD). Several studies in the 1980s led to the suggestion that synthase complexes may have very short half-lives in vivo, but no recent work has directly addressed this issue. In the present work, we show that the half-life of cotton fiber GhCesA1 protein is <30 min in vivo, far less than the average membrane protein. We also show that the reduced monomer of GhCesA1 ZnBD is rapidly degraded when exposed to cotton fiber extracts, whereas the oxidized dimer is resistant to degradation. Low rates of degradation activity were detected in vitro by using extracts from fibers harvested during primary cell-wall formation, but activity increased markedly during transition to secondary cell-wall synthesis. In vitro degradation of reduced GhCesA1 ZnBD is inhibited by proteosome inhibitor MG132 and also by E64 and EGTA, suggesting that proteolysis is initiated by cysteine protease activity rather than the proteosome. We used a yeast two-hybrid system to identify a putative cotton fiber metallothionein and to confirm it as a protein that could interact with the GhCesA1 ZnBD. A model is proposed wherein active cellulose synthase complexes contain CesA proteins in dimerized form, and turnover and degradation of the complexes are mediated through reductive zinc insertion by metallothionein and subsequent proteolysis involving a cysteine protease.

Biochemistry↗
PubMed1999

Duplicated genes evolve independently after polyploid formation in cotton.

Of the many processes that generate gene duplications, polyploidy is unique in that entire genomes are duplicated. This process has been important in the evolution of many eukaryotic groups, and it occurs with high frequency in plants. Recent evidence suggests that polyploidization may be accompanied by rapid genomic changes, but the evolutionary fate of discrete loci recently doubled by polyploidy (homoeologues) has not been studied. Here we use locus-specific isolation techniques with comparative mapping to characterize the evolution of homoeologous loci in allopolyploid cotton (Gossypium hirsutum) and in species representing its diploid progenitors. We isolated and sequenced 16 loci from both genomes of the allopolyploid, from both progenitor diploid genomes and appropriate outgroups. Phylogenetic analysis of the resulting 73.5 kb of sequence data demonstrated that for all 16 loci (14.7 kb/genome), the topology expected from organismal history was recovered. In contrast to observations involving repetitive DNAs in cotton, there was no evidence of interaction among duplicated genes in the allopolyploid. Polyploidy was not accompanied by an obvious increase in mutations indicative of pseudogene formation. Additionally, differences in rates of divergence among homoeologues in polyploids and orthologues in diploids were indistinguishable across loci, with significant rate deviation restricted to two putative pseudogenes. Our results indicate that most duplicated genes in allopolyploid cotton evolve independently of each other and at the same rate as those of their diploid progenitors. These indications of genic stasis accompanying polyploidization provide a sharp contrast to recent examples of rapid genomic evolution in allopolyploids.

Biological Evolution↗
PubMed1976

Plant trash in linters and willowed picker: materials used in the cotton garnetting industry.

First cut linters and willowed picker, used in cotton garnetting, were examined for content of cotton bract an other plant trash. Bract was found to be a minimal contaminant of the trash of first cut linters. A significant amount of bract (about 9% of the trash) was present in willowed picker. Cotton seed hulls, a valuable oil mill by product, contained an insignificant amount of bract trash.

Byssinosis↗
PubMedDate not supplied

Acute experimental pulmonary responses to cardroom cotton dust.

Laboratory rabbits were exposed for 60 min to aerosols of dry cardroom cotton dust 4 days/wk (Tuesday through Friday) for 15 consecutive weeks. As a parameter of pulmonary pathophysiology, arterial blood gases were monitored with time after challenge. Post-exposure blood gas analyses at 1 hr showed progressive decreases in arterial oxygen tension, with concommitant increases in arterial carbon dioxide tension and the alveolar-arterial oxygen gradient. These responses appeared to result from acute reversible airway obstruction which caused unequal gas distribution and ventilation-perfusion inequalities. When a group of proven responder rabbits was challenged with cardroom cotton dust which was first treated in a manner which paralleled the preparation of medical grade cotton, only minor decreases in arterial oxygen tension were observed. The data suggest that some, as yet undefined, agent(s) which was removed by the treatment was responsible for inciting the observed pathophysiology.

Animals↗
PubMedDate not supplied

Source and function of keto elaidic acids from lungs of cotton workers.

A series of cytotoxic oxygenated derivatives of oleic acid, 8-oxo-9, 9-oxo-10, 10-oxo-8-, and 11-oxo-9 trans octadecenoic acid, uniquely found at post-mortem in airway cells of cotton workers, were synthesized and shown to be cytotoxic, i.e., inhibitory of growth for several cell lines, including HL-60 and U-937 promyelocytes and Eagle's KB carcinoma cells. At microM concentrations, the 8- and 11- keto acids: are chemokinetic for human neutrophils; activate production of O2-. and H2O2; stimulate promyelocytes in culture to differentiate into neutrophils; and increase diglyceride metabolism in inflammatory cells. These results indicate that these four monooxygenated fatty acids, which are found in airways of cotton workers and initiate both inflammation and differentiation in vitro, may be etiologic in the abnormal differentiation and inflammation seen in small airways of cotton workers. This abnormal differentiation in bronchi may result from altered diglyceride metabolism with resultant activation of phosphoprotein kinase C initiated by the keto fatty acids.

Cells, Cultured↗
PubMed2001

Evaluation of myelotoxicity in cotton rats (Sigmodon hispidus) exposed to environmental contaminants. II. Myelotoxicity associated with petroleum industrial wastes.

Various chemical mixtures exist in soil contaminated with petrochemical wastes, yet no comprehensive assessment of their impact on terrestrial ecosystems has been conducted. The purpose of this study was to evaluate hematotoxicity risks to wild populations of cotton rats (Sigmodon hispidus) residing in habitats previously contaminated by petroleum industrial wastes. Resident cotton rats were monitored on nine contaminated sites and nine ecologically matched reference sites in Oklahoma. The possible toxicological interactions of petrochemical wastes on bone marrow was investigated by using the assay of colony formation of granulocyte-macrophage progenitor cells. There was a consistent significant 21 to 39% decrease in the number of colony-forming units of granulocyte-macrophage (CFU-GM) in cotton rats from petrochemical-contaminated sites compared to matched reference sites, with no marked changes in hematological or histopathological parameters. These results suggest that bone-marrow progenitor cell culture is a sensitive indicator for the assessment of ecotoxicity risks associated with petrochemical wastes that are generated by the oil refining industry. Long-term exposure to hazardous wastes associated with the petroleum industry may represent a subtle risk to the hematopoietic system in humans.

Animals↗
PubMed2000

Monitoring of pesticide residues in a cotton crop soil.

This paper reports on the residues of methyl parathion (O,O-dimethyl O-4-nitrophenyl phosphorothioate), trifluralin (alpha, alpha, alpha-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), endosulfan [(1, 4, 5, 6, 7, 7-hexachloro-8, 9, 10-trinorborn-5-en-2, 3-ylenebismethylene) sulfite] and dimethoate (O, O-dimethyl S-methylcarbamoylmethyl phosphorodithioate) in a cotton crop soil. Soil samples (0-15 cm) were collected at different periods from the cotton crop farm and subjected to Soxhlet extraction. The extracted material was analysed after clean-up by a HP5890 II gas chromatograph equipped with a 63Ni electron-capture detector (ECD-63Ni) and fitted with a 25 m x 0.2 mm i.d. fused silica capillary column [Ultra-2 (5% phenylmethyl polysiloxane)]. The recoveries of the pesticide residues from the spiked control soil were determined after Soxhlet extraction and C18 cartridges clean-up by using radiotracer techniques with the corresponding 14C-pesticides. The results show that in the cotton crop soil the pesticide residues under study were present in the range of 0.1 to 0.4 mg.kg-1. Endosulfan was found to be rapidly degraded in the soil and formed a sulfate metabolite.

Dimethoate↗
PubMed1980

Absorption and metabolism of the chiral isomers of fonofos in the corn and cotton plant.

Root absorption of chiral phenyl-35S-fonofos in cotton and corn plants revealed stereoselective differences between the two enantiomers. (S)p-Fonofos was absorbed at a faster initial rate and to a greater extent than the (R)p enantiomer in both plant species. Approximately 40% and 62% of the applied radioactivity was absorbed into the cotton plant 12 hr after application of (R)p- and (S)p-fonofos, respectively. In the corn plant, approximately 25% and 63% of the applied (R)p- and (S)p-fonofos was absorbed in the first 12 hrs. Little qualitative or quantitative difference in plant translocation between fonofos enantiomers was observed. (R)p-fonofos was found to be metabolized to a greater extent than the (S)p enantiomer in both cotton and corn plants.

Absorption↗
PubMed2003

Ecotoxicological risks associated with land treatment of petrochemical wastes. I. Residual soil contamination and bioaccumulation by cotton rats (Sigmodon hispidus).

Petrochemical waste contains both organic and inorganic contaminants that can pollute soil and may pose significant ecological risks to wildlife. Petrochemical waste typically is disposed of in land treatment units, which are widespread throughout Oklahoma and the United States. Few studies have been conducted evaluating possible toxicity risks to terrestrial organisms residing on these units. In this study, the extent of soil contamination with fluoride (F), metals, and organic hydrocarbons, the bioaccumulation of F and metals in cotton rats (Sigmodon hispidus), the relationship between contaminants in soil and in tissues of cotton rats, and the level of potentially toxic polycyclic aromatic hydrocarbons (PAHs) in soil were determined on land treatment units. Over a 2-yr period, cotton rats and soils were collected and analyzed from 5 land treatment and matched reference units. The number of land treatment units with soil metal contamination (in parentheses) included: Cr, Cu, Pb (5). Al, As, Ni, Sr, Zn (4). Ba (3). and Cd, V (2). The number of land treatment units with soil PAH contamination (in parentheses) were naphthalene, phenanthrene, benzo[g,h,i]perylene (3). acenaphthene, anthracene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[a]pyrene, indeno[1,2,3-c,d]pyrene, dibenz[a,h]anthracene (2). and acenaphthylene, fluorene, fluoranthene, benzo[k]fluoranthene (1). Total PAH and total petroleum hydrocarbons (TPH) were elevated at all five land treatment units. Mean sums of benzo[a]pyrene (BaP) equivalents (BaPequiv ) were not affected on

Animals↗
PubMed1986

Interactions of a water extract of cotton bract with dog isolated airway smooth muscle.

The inhalation of cotton dust by cotton-mill workers causes byssinosis, a disease characterized by chest tightness and other symptoms indicative of bronchoconstriction. In the present study the dog isolated trachealis smooth muscle preparation was employed to examine the ability of a crude, water extract of cotton bracts (CBE) to (1) cause contractile responses mediated by receptors, (2) modify responses of the tissue to a number of excitatory and inhibitory agents, and (3) alter responsiveness of the preparations to electrical field stimulation mediated by intrinsic cholinergic, excitatory nerves and adrenergic, inhibitory nerves. CBE evoked contraction of the tissues by an action that did not involve muscarinic, histamine, or 5-hydroxytryptamine receptors. The maximum tissue responses to exogenous histamine, 5-hydroxytryptamine, and isoproterenol were enhanced significantly in the presence of CBE, while those to KCl and methacholine were unaffected. The sensitivities (EC50 values) of the tissues to these agents were not, however, altered by CBE. Contractions induced by cholinergic nerve stimulation were increased in the presence of CBE, via a mechanism that appears, at present, to result from a prejunctional facilitation of acetycholine release. Relaxations to adrenergic nerve stimulation were not affected by CBE. Results suggest that, in addition to its direct, contractile activity, CBE can alter indirectly the responsiveness of the tissue to a number of endogenous mediator substances. Intrinsic, cholinergic excitatory nerves may be a target for the acute action of CBE as well.

Animals↗
PubMed1988

3-Hydroxymyristic acid as a measure of endotoxin in cotton lint and dust.

A series of samples consisting of purified cellulose, purified cellulose spiked with endotoxin, and cotton lint and dust samples from the Human Panel Acute Exposure Studies at Clemson, South Carolina, were extracted with pyrogen-free water and with phenol-water. Phenacyl esters of the dried, hydrolyzed extract were prepared and chromatographed on a high performance liquid chromatograph. A peak assigned to the phenacyl ester of 3-hydroxymyristic acid appears in the chromatograms of extracts of celluloses that have been spiked with endotoxins and not in those of unspiked celluloses. This peak also appears in the extracts of cotton lint from samples that cause the greatest decrement in lung function in the Clemson human exposure studies. The area of this peak increases with increasing amounts of endotoxin and may serve as a measure of endotoxin concentration in cotton lint and dust, at least when fairly high levels of endotoxin (0.50 micrograms or greater) are present. The effect of extraction method on the determined amount of endotoxin is discussed.

Cellulose↗
PubMed2001

Insecticide residues in cotton crop soil.

Dimethoate, monocrotophos, triazophos, deltamethrin, cypermethrin and endosulfan were applied to a cotton crop soil located at Nurpur village, Punjab, India. The insecticides were applied sequentially at recommended dosages in cotton fields by foliar application in 1995, 1996 and 1998. Soil samples were collected from the cotton crop farms and extracted with acetone. The extracted material was analysed by a gas liquid chromatograph (GLC) equipped with an 63Ni electron-capture detector (ECD-63Ni). Recovery data was obtained by fortifying soil with insecticide. The average recoveries from the fortified soil samples were 76-92% for organophosphorous compounds and 90-98% for synthetic pyrethroids and organochlorines. The results showed that the insecticide residues under study were present in the range of 1.16 to 41.97 ng g(-1) d.wt.soil. The pattern of dissipation of the insecticides used was similar for the duration of the crop. Half lives of the insecticides ranged from 7 to 22 days. Except endosulfan none of the other insecticides used were leached below 15 cm. Endosulfan was found to be rapidly degraded in the soil and formed a sulfate metabolite. Persistence and dissipation pattern in soils with history of exposure to the insecticide compared to non-history soils were similar.

Chromatography, Gas↗
PubMed2004

Variable resistance to palivizumab in cotton rats by respiratory syncytial virus mutants.

BACKGROUND: Palivizumab (PZ) is the only monoclonal antibody in use against a human infectious disease. PZ is given as prophylaxis against infection with respiratory syncytial virus (RSV). An RSV escape mutant, MP4, has been shown to resist PZ prophylaxis in cotton rats. METHODS: To further define the potential of RSV to resist prophylaxis, additional PZ-resistant viruses were selected in cell culture and were tested for susceptibility to PZ in cotton rats. RESULTS: Mutant MS412 had an A-->C mutation at nucleotide position 827 in the F gene, resulting in an amino acid change from Lys to Gln at position 272. Mutant F212 had an A-->T mutation at position 816, leading to an amino acid change from Asn to Ile at position 268. In vitro, F212 had impaired growth kinetics. In cell culture, F212 was partially and MS412 was completely resistant to PZ neutralization. A single prophylactic dose of 15 mg/kg PZ protected cotton rats from infection with F212 but not with MS412. CONCLUSION: Both in vitro and in vivo, individual RSV PZ escape mutants varied in their susceptibility to PZ. Mutations associated with resistance to PZ did not always result in failure of PZ prophylaxis.

Amino Acid Substitution↗
PubMed1997

Immunoprophylaxis of group B respiratory syncytial virus infection in cotton rats.

Two antigenic groups of respiratory syncytial virus (RSV) have been identified: A (RSV/A) and B (RSV/B). Topical administration of human IgG screened for high titers of antibody to RSV/A (RSVIg) is protective against RSV/A infection in the cotton rat model. The study attempted to determine if topical RSVIg would also be protective against RSV/B. Cotton rats were pretreated intranasally with RSVIg or with monospecific antiserum obtained from animals previously infected with RSV/A or RSV/B (day 0), challenged intranasally with RSV/A or RSV/B (day 1), and sacrificed for virus titration (day 5). Cotton rat antiserum to RSV/B protected against RSV/A and RSV/B, while antiserum to RSV/A protected only against RSV/A. RSVIg, although prepared on the basis of activity against RSV/A, was also protective against RSV/B.

Animals↗
PubMed1992

A study of the performance and comparability of the sampling response to cotton dust of work area and personal sampling techniques.

In order to compare and contrast the sampling response to cotton dust of two forms of dust sampling 85 work areas were identified over a 2-year period for investigation in eight Lancashire spinning mills. Three hundred and five work area dust samples were undertaken and 252 personal dust samples were performed. Operatives who spent a minimum of 80% of their working shift in the area in which work area sampling was also performed were selected for personal sampling. Work area dust exposures have recently shown an upward trend, with highest concentrations occurring in the ring spinning room (median 1.15 mg m-3, range 0.82-2.06). Personal dust samples showed a reduction in dust exposures as cotton processing progressed, from a high in the opening room (median value of 6.24 mg m-3, range 1.0-41.5) to a minimum of 1.02 mg m-3 (range 0.30-0.93) in the winding room. The ratio of measured personal sampling dust exposure to work area sampling exposure was used to compare the relative performance of the two techniques. This ratio was highest in the early processes. There was a 7.8-fold difference in measurement between the two techniques in the opening processes, falling to 4.9 in carding and 4.2 in the other card-room processes. However in ring spinning the ratio was only 1.4, suggesting a degree of comparability in the methods at this stage of processing. The value rose to 2.5 for the last stage (winding). Respiratory disease is known to occur predominantly in the early stages of processing (opening and carding) where high dust concentrations are found using the personal technique. These data support the use of personal sampling for setting exposure limits to cotton dust in preference to the current recommended method using work area sampling techniques, which may significantly underestimate dust exposure in the high risk work areas and is outdated.

Dust↗
PubMed2000

Spontaneous ECLomas in cotton rats (Sigmodon hispidus): tumours occurring in hypoacidic/hypergastrinaemic animals with normal parietal cells.

We have identified cotton rats with a high female-predominant occurrence of spontaneous gastric carcinomas localized to the oxyntic mucosa, classified as malignant enterochromaffin-like (ECL) omas. The present study was made to further characterize these ECLomas and surrounding oxyntic mucosa, both morphologically using histochemical and immunohistochemical methods, and for gene expression by northern blot analysis. Among eight female cotton rats, three had an irregularly thickened oxyntic mucosa, increased stomach weight and a high serum gastrin level. Histopathological examination showed adenomatous hyperplasia of the thickened oxyntic mucosa with areas of an invasive neoplastic tumour. Immunohistochemistry, using the general neuroendocrine cell marker chromogranin A (CgA) and the specific ECL cell marker histidine decarboxylase (HDC), showed a considerably increased ECL cell density. These ECL cells displayed active proliferation, with hyperplasia, dysplasia and neoplasia. Parietal cells were not found in the tumour tissue. Parietal cell density was only slightly reduced in the surrounding oxyntic mucosa. The antral mucosa was histopathologically normal with a normal number of gastrin-immunoreactive cells. Likewise, somatostatin-immunoreactive cells did not show any differences in the antral and oxyntic mucosa between rats with pathological and normal oxyntic mucosa. Northern blot analysis revealed increased expression of CgA and HDC mRNA in the thickened oxyntic mucosa, whereas H(+)/K(+) ATPase mRNA was similar in the oxyntic mucosa of those with thickened and normal oxyntic mucosa. Gastrin mRNA in the antral mucosa was high in animals with thickened oxyntic mucosa. Somatostatin mRNA expression was similar in the antral mucosa of control animals and animals with a thickened oxyntic mucosa. We conclude that the spontaneous gastric carcinoma occurring in female cotton rats is an ECLoma developing secondary to hypergastrinaemia due to reduced intragastric pH. The mechanism for reduced acidity is not known, but is not gastric atrophy.

Animals↗
PubMed1991

Vaccination of cotton rats with a chimeric FG glycoprotein of human respiratory syncytial virus induces minimal pulmonary pathology on challenge.

The cotton rat model of human respiratory syncytial virus (RSV) infection was used to study the safety and efficacy of a chimeric FG glycoprotein that was expressed in insect cells using a baculovirus vector. Histologic and virologic examination of vaccinated rat lungs was done after challenge with RSV. When rats were challenged 1 month after vaccination, severe pulmonary inflammation characterized by both a mononuclear and polymorphonuclear cell infiltrate and 30%-40% involvement of lung tissue was observed with a formalin-inactivated RSV vaccine. The FG glycoprotein induced minimal lung inflammation (involving 2%-5% of the lung), while negative controls had 1%-3% lung involvement. Two doses with as little as 20 ng of FG glycoprotein formulated in an aluminum hydroxide adjuvant completely protected the cotton rats from RSV challenge. Thus the chimeric FG glycoprotein is highly immunogenic and induces minimal pulmonary inflammation in the cotton rat model.

Animals↗