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| Trends in reported suicide rates were analysed for the ages 5-24 years in 21 selected European countries in 1970-74 and 1980-84. In children the precision of the rates was found to be low though there appeared to be a trend to increased suicide in boys. In adolescent and young adult males, however, there was a definite increase in suicide over the period studied, and this was much more marked than in females, in whom the rates had declined in eight countries. The Belgian situation was investigated in detail. Increases were most pronounced in 20-24 year-old males. Around 1981, about half of youth suicides were committed by firearms and medicaments, and these methods showed the largest increases in risk. The estimated under-reporting error diminished with increasing age and over the past ten years. It was larger in females, but did not bias the trends substantially. On the aggregated level, youth suicide was found most strongly associated with indicators of anomie and social isolation. The relevance of these findings in the search for determinants and for preventive strategies is discussed. | description |
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| Moens, G F, Haenen, W, Van de Voorde, H | authors |
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| Height and social class in middle-aged British men. | name |
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| A study of 7735 middle-aged British men drawn from general practices in twenty-four towns shows that there has been a progressive increase in mean height in the men who were born between 1919 and 1939. This is true for both manual and non-manual classes, but the mean heights of the two groups are significantly different and remain widely separated over this period of time. Manual workers lag twenty years behind non-manual workers in their attained height. Data from other studies indicate that this social class difference in adult height is still present in those born up to 1960. The variation in mean height between the twenty-four towns is less marked than the variation in mean height between the social classes. After social class and age have been taken into account, a "town effect" on height is still present. If height is accepted as an indicator of socio-economic circumstances in childhood, then there is a difference in adult height between social class groups in Great Britain which does not appear to be diminishing. | description |
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| Walker, M, Shaper, A G, Wannamethee, G | authors |
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| Risk factors in chronic obstructive pulmonary malfunction and "chronic bronchitis" symptoms in Beijing district: a joint study between Japan and China. | name |
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| A cross sectional study of risk factors in respiratory diseases was carried out in August 1986, in Beijing, China. Inhabitants greater than or equal to 40 years old were selected at random from a rural area, a residential area and an industrial area, using a two stage sampling method. The analysis presented here is based on the sample population of adults who (1) were prepared to be interviewed, using the British Medical Research Council's questionnaire translated into Chinese (n = 3423) and (2) had lung function measurements at the same time (n = 3373). Obstructive lung disease was defined as forced expiratory volume in 1s (FEV1) less than 68% of forced vital capacity (FVC). Seven variables were considered as potential risk factors or confounding factors: area of residence, sex, age, cigarette smoking, history of respiratory disease, socio-economic status and familial component. A modified binary variable regression method developed by Feldstein was used for the adjustment of rate ratios. The adjusted prevalence of obstructive lung disease was highest in the rural area and lowest in the residential area(s). An increase in age, cigarette smoking, low socio-economic status and positive history of respiratory diseases were associated with significantly higher rates of impaired pulmonary function. The other measured factors did not appear to be related to impaired pulmonary function. | description |
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| Yamaguchi, S, Kano, K, Shimojo, N, Sano, K, Xu, X P, Watanabe, H, Kameyama, M, Santamaria, M J, Liu, S J, Wang, L H | authors |
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| Increased obstetric activity: a new meaning to "induced labour"? | name |
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| This study examines the possible reasons for increased obstetric activity in Denmark over the past 25 years. Since 1960 there has been a substantial increase in the average number of hospital admissions (from 10 to 32 per 100 deliveries), in deliveries diagnosed as complicated (from 15 to 49%), and above all in major interventions at delivery (from 4 to 22%). In spite of this increase in activity there is no evidence that the postwar trend of decreasing perinatal mortality has been further improved during the period of study. It seems possible that the rising level of activity is the result of increasing availability of new technology, decreasing numbers of deliveries and unchanged obstetric staffing levels, with an increased tendency to diagnose and intervene in "at risk" pregnancies. There is a need to determine how the current level of obstetric activity has arisen. Since there is evidence for an increased expectation of intervention by pregnant women, the theory of supplier induced demand may be among the leading contenders to be tested. | description |
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| Vallgårda, S | authors |
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| Sexual behaviour of young people and the risk of HIV infection. | name |
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| A survey of 16-21 year old people in Somerset was undertaken to find out about their sexual behaviour prior to mounting a local education campaign on AIDS. A representative sample of 400 people, using quota sampling in 40 randomly selected electoral wards, completed a schedule structured part self administered questionnaire. Of these, 371 (92%) considered themselves heterosexual. Nearly half (47%) of the 16 year olds had engaged in sexual intercourse, rising to 89% by the age of 21. Mean frequency of sexual intercourse among the sexually active is 62 per year. The frequency of partner change decreases with increasing age for non-virgins from 2.1 for 16 year olds to 1.5 partner changes per year for 21 year olds (mean frequency 1.7 per year, ie, a new partner every 7 months). This level of sexual activity could eventually give rise to HIV prevalence rates similar to those found in Africa, i.e., 15-100 HIV antibody positive per 1000. | description |
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| Bowie, C, Ford, N | authors |
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| A prospective study of some aetiological factors in limb reduction defects in Sweden. | name |
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| Two groups of infants with limb reduction defects were studied: all such infants born in Sweden 1983-1986, and infants with severe reduction deformities born in 1973-1981. Data on the use of oral contraceptives, intrauterine devices, and drugs, and on maternal smoking were retrieved from information collected in early pregnancy as a part of routine maternity health service records. It was not possible to substantiate the association, described repeatedly in the literature, between limb reduction defects and the use of oral contraceptives just before or in early pregnancy. Various explanations for this discrepancy are discussed. An association with maternal diabetes was seen but not with drugs used for thyroid disease. A weak and statistically non-significant association with maternal smoking was found for severe limb reduction defects. | description |
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| Källén, B | authors |
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| Risk factors for breast cancer by mode of diagnosis: some results from a breast cancer screening study. | name |
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| We have investigated factors affecting the probability that a woman with breast cancer participating in a mammographic screening programme will be diagnosed by the screen. Data from a large American case-control study, with subjects drawn from women participating in an annual screening programme, were used. During the screening programme, 409 cases were identified, the mode of diagnosis being screen detection for 331 and interval detection for 78. No significant relationships were found between mode of diagnosis and age, age at menarche, oral contraceptive use, age at first live birth, age at menopause or history of maternal breast cancer. There was a non-significant trend for particular mammographic patterns to be associated with interval detection. However relative risk of breast cancer and probability of interval detection were observed to increase about the time of the menopause. These results suggest that the 3 yearly mammography programme being introduced in the UK might be improved if an extra examination was included around the time of the menopause. | description |
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| Whitehead, J, Cooper, J | authors |
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| The use of hormonal replacement therapy and the risk of stroke and myocardial infarction in women. | name |
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| To determine whether there is an association between the use of hormonal replacement therapy (HRT) and the risk of stroke and myocardial infarction (MI). | description |
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| Thompson, S G, Meade, T W, Greenberg, G | authors |
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| Apparent effect of immune serum globulin prophylaxis in the military on viral hepatitis incidence in the civilian population in Israel. | name |
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| Since 1969, extensive use of immune serum globulin in the Israel Defence Force for prophylaxis against hepatitis A virus (HAV) infection has produced a sharp decline in the incidence of the disease. However, it is not clear whether this policy has affected the susceptibility of Israeli adults to HAV infection. In this study, we examined the effect of the immunisation policy on the incidence of hepatitis A virus infection in the civilian population in the 15-44 year age group, which includes all those who have completed compulsory military service since vaccination was introduced. The incidence of viral hepatitis in the Jewish civilian population aged 15-44 increased by approximately 50% 3-4 years after the implementation of the immunisation policy. This rise was not seen in the non-Jewish population of the same age nor among Jews aged 45-64. These findings strongly suggest that the immunisation policy in the military prevents both clinical and sub-clinical disease, but has had the effect of producing more susceptible people at an older age in the civilian population. | description |
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| Green, M S, Block, C | authors |
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| Skinfold thickness, body mass index and ischaemic heart disease. | name |
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| To determine the relationship between obesity and subsequent incidence of ischaemic heart disease (IHD). | description |
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| Imeson, J D, Haines, A P, Meade, T W | authors |
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| Aftermath of stroke: an epidemiological study in Melbourne, Australia. | name |
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| A population-based study of the incidence of stroke was carried out in an urban area of Melbourne, Australia. The 508 cases were followed up and the survivors interviewed briefly at three months and in more depth six months after the onset of stroke. Fifty-eight per cent of all subjects had survived to six months, and the strongest prognostic indicator was level of consciousness at time of maximum impairment. By six months, 25% of all cases were independent in self-care and mobile outside the home; of those patients aged under 75 years, suffering a first stroke and retaining full consciousness at the time of maximum impairment, the proportion was 50%. A very imperfect correlation was present between residual physical impairment and return to the full range of prestroke activities. | description |
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| Christie, D | authors |
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| North Hammersmith stroke prevention project. | name |
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| The North Hammersmith stroke prevention project was designed to reduce the number of deaths from stroke in this health district by improving the detection of hypertensive patients and thereafter reducing the default rate from treatment. Starting in May 1979 general practitioners in the district were asked to register hypertensive patients over the age of 40 so that the proportion of such patients in each practice was known and could be compared with the average for all practices. This confidential information was fed back every year to the individual general practitioners so that they could assess their performance. Forty of 44 eligible general practitioners agreed to participate and 29 proceeded to register patients. Over a three year period 1006 patients were registered, representing 4.3% of the project population over the age of 40. Individual practice registration rates ranged from 1.1% to 9.1%. Sixty five per cent of the registered patients were women, 34% of all registrations were in the age group 60-69, 31% in the group 50-59, 12% in the group 40-49, and 23% in the group over 70. The average blood pressure before treatment was 190/111 mm Hg. After one and two years the patients were contacted or their notes examined to ensure that they still receiving treatment. Persistant default from treatment occurred in under 12% over the three year period. | description |
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| Penfold, D, Styles, W M, Bulpitt, C J | authors |
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| The use of cytotoxic plant lectins in cancer therapy. | name |
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| As part of their defense mechanism against herbivores or phytophagous insects, many plant tissues contain lectins. Some of these lectins are potent toxins which kill animal cells by arresting protein synthesis. An attractive strategy for developing specifically cytotoxic chemotherapeutic agents is to link cell type-specific monoclonal antibodies to potent toxins. The plant protein ricin has emerged as the toxin of choice for such constructs. | description |
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| Lord, J M | authors |
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| Synthesis of only two heat shock proteins is required for thermoadaptation in cultured cowpea cells. | name |
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| Cell cultures of a heat sensitive genotype of cowpea (Vigna unguiculata) were adapted to tolerate moderate levels of heat by maintaining cells at 32, 36, and 38 degrees C over many cell generations. Cells adapted to 32 and to 36 degrees C did not produce the typical heat shock proteins (HSP). Cells adapted to 38 degrees C synthesized two new proteins, which appear to be a subset of the HSP. In many temperature sensitive organisms it is thought that HSP confer thermotolerance. However, we hypothesize that specific proteins are associated with heat tolerance in cowpea, other heat tolerant plants (species such as sorghum and millet), and adapted cells which provide them with enhanced heat tolerance. From present data we suggest two proteins (70 and 80 kilodaltons) are strongly associated with heat tolerance and heat adaptation. | description |
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| Heuss-Larosa, K, Mayer, R R, Cherry, J H | authors |
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| Quantification of abscisic Acid in a single maize root. | name |
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| Quantitative analyses of abscisic acid in the elongating zone of a single maize root (Zea mays L. cv LG 11) were performed by gas chromatography-mass spectrometry using negative chemical ion ionization. Data showed that the more abscisic acid, the slower the growth, but a large dispersion of individual values was observed. We assume that abscisic acid is perhaps not correlated only to the growth rate. | description |
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| Reymond, P, Saugy, M, Pilet, P E | authors |
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| Ion-exchange chromatography separates activities synthesizing and degrading fructose 2,6-bisphosphate from C3 and C4 leaves but not from rat liver. | name |
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| Fructose-6-phosphate,2-kinase and fructose-2,6-bisphosphatase were separated on the basis of charge from leaves of C3 (spinach, lettuce, and pea) and C4 (sorghum and amaranthus) plants but not from rat liver--a tissue known to contain a bifunctional enzyme with both activities. [2-32P]Fructose 2,6-bisphosphate binding experiments also suggest that the major forms of these activities reside on different proteins in leaves. | description |
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| Macdonald, F D, Chou, Q, Buchanan, B B, Buchanan, B B | authors |
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| Contiguous organization of nitrogenase genes in a heterocystous cyanobacterium. | name |
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| The organization of the three structural nitrogen fixation (nif) genes that encode nitrogenase (nif K and nif D) and nitrogenase reductase (nif H) have been examined in a number of cyanobacteria. Hybridization of Anabaena 7120 nif gene probes to restriction endonuclease-digested genomic DNA has shown (a) that cyanobacteria incapable of N(2) fixation have no regions of DNA with significant homology to the three nif probes, (b) that Pseudanabaena sp., a nonheterocystous cyanobacterium, has a contiguous nif KDH gene cluster, and (c) that in contrast with other heterocystous cyanobacteria, Fischerella sp. has a contiguous nif KDH gene cluster. | description |
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| Saville, B, Straus, N, Coleman, J R | authors |
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| Inhibition of na/h antiport activity in sugar beet tonoplast by analogs of amiloride. | name |
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| The effects of amiloride and a series of amiloride analogs have been tested on the Na(+)/H(+) antiport activity in intact vacuoles and tonoplast vesicles isolated from sugar beet cell suspension cultures. There is a competitive interaction between amiloride analogs and sodium. Substitution of one or both H-atoms of the 5-amino group of amiloride (apparent K(i) about 150 micromolar) resulted in a 3- to 200-fold increase in inhibitory potency of the antiport activity. | description |
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| Blumwald, E, Cragoe, E J, Poole, R J | authors |
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| Transient Induction of Phenylalanine Ammonia-Lyase and 4-Coumarate: CoA Ligase mRNAs in Potato Leaves Infected with Virulent or Avirulent Races of Phytophthora infestans. | name |
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| Infection of potato leaves with the fungal pathogen Phytophthora infestans (Pi) resulted in the rapid stimulation of phenylpropanoid metabolism. Increases in the activities of several mRNAs, including those encoding phenylalanine ammonia-lyase (PAL) and 4-coumarate:CoA ligase (4CL), were detectable within a few hours postinoculation, as demonstrated by two-dimensional gel electrophoresis of proteins synthesized in vitro. This effect was closely mimicked by application of Pi culture filtrate through cut leaf stems. PAL and 4CL mRNA activities were also rapidly and transiently induced in potato cell suspension cultures by treatments with Pi culture filtrate or arachidonic acid. This induction was exploited to generate cDNA probes complementary to PAL and 4CL mRNAs. Blot hybridizations using these probes revealed almost immediate, transient and coordinate increases in the transcription rates and subsequent changes in the amounts of PAL and 4CL mRNAs in leaves treated with Pi culture filtrate. Similar changes in the mRNA amounts were found in infected leaves of potato cultivars carrying resistance genes R1 (cv Datura) or R4 (cv Isola), independent of whether a virulent or an avirulent Pi pathotype was used for inoculation. These results are discussed in relation to recent cytological observations with the same potato cultivars and Pi pathotypes. | description |
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| Fritzemeier, K H, Cretin, C, Kombrink, E, Rohwer, F, Taylor, J, Scheel, D, Hahlbrock, K | authors |
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| Changes in the level of free and ester indol-3yl-acetic Acid in growing maize roots. | name |
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| The levels of free and ester-linked indole-3-acetic acid (IAA) in different parts of the maize root were measured using gas chromatography-mass spectrometry (selected ion monitoring). In roots of 2-day-old plants, the distribution of free and ester IAA differed both along the root and between stele and cortex. The levels of IAA and IAA esters were then measured in whole roots and in the elongation zone using roots of different ages. The level of ester IAA decreased steadily with time. In contrast, the level of free IAA in the elongation zone was found to increase after a few days of culture at which time the rate of root growth was decreasing. | description |
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| Saugy, M, Pilet, P E | authors |
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| Regulation by Phospholipids and Kinetic Studies of Plant Membrane-Bound UDP-Glucose Sterol beta-d-Glucosyl Transferase. | name |
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| Solubilization and partial purification of the microsomal UDP-glucose sterol glucosyl transferase activity from maize coleoptiles by chromatography on DEAE-cellulose resulted in a highly delipidated (>95%) and inactive enzymic preparation. Addition of sterols revealed part of the activity and subsequent addition of phospholipids further increased the activity. Negatively charged phospholipids were shown to be by far the best activators. The purification step also produced the elimination of two interfering microsomal enzymic activities: UDPase and steryl glucoside acyl transferase. The removal of these two enzymic activities was a prerequisite for kinetic studies including product-inhibition studies, since the substrates of these two latter enzymes are the products of UDPG-SGTase activity. The results of the kinetic studies strongly suggest an ordered bi-bi mechanism for the glucosylation of sterols. Finally the effect of different phospholipids on the kinetic parameters of the reaction was studied. Both phosphatidylcholine and phosphatidylglycerol significantly decrease K(m-sterol) (and not K(m-UDPglucose)) and increase the reaction V(max). The decrease of K(m-sterol) is similar with both phospholipids whereas the increase of V(max) is much greater with phosphatidylglycerol than with phosphatidylcholine. | description |
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| Ullmann, P, Bouvier-Navé, P, Benveniste, P | authors |
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| Subcellular Localization of Amines and Activities of Their Biosynthetic Enzymes in p-Fluorophenylalanine Resistant and Wild-Type Tobacco Cell Cultures. | name |
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| Three levels of free amines and the activities of their biosynthetic enzymes were measured in subcellular fractions of two cell lines of Nicotiana tabacum L. cv Xanthi. The TX4 cell line, a p-fluorophenylalanine resistant culture which accumulates high levels of cinnamoylamides, was compared to the wild-type culture TX1. In cells harvested on day 6 of the growth cycle, nearly all free putrescine, spermidine, and tyramine was found in the supernatant fraction of both cell lines. Although a consistent portion of ornithine decarboxylase activity was detected in the nuclear-enriched fractions of TX1 and TX4, the largest levels of activity were in the supernatants of both lines. In TX1, arginine decarboxylase activity was low relative to that of ornithine decarboxylase, but, in the TX4 line arginine decarboxylase levels in the cytosol were substantially elevated. Tyrosine decarboxylase was not detected in 6-day-old TX1 cells, but significant amounts of activity were measured in the 1000g and supernatant fractions of TX4. S-Adenosylmethionine decarboxylase activity was low in both cell lines and was located predominantly in the supernatant. | description |
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| Walker, M A, Ellis, B E, Chapple, C C, Dumbroff, E B | authors |
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| Free amino Acid content and metabolic activities of setting and aborting soybean ovaries. | name |
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| Fruits of soybean (Glycine max [L.] Merr.) that are destined to abscise shortly after anthesis grow more slowly than fruits that will be retained. In this work, amino acid composition, protein metabolism, and nucleic acid metabolism were studied in setting and abscising soybean ovaries from anthesis to 6 days after anthesis to provide additional evidence of chemical processes associated with abscission. Principal free amino acids were asparagine, aspartic acid, glutamic acid, serine, and glutamine. Percent aspartate and glutamate declined as the ovaries grew, with aspartate declining more in abscising and glutamate more in setting ovaries. Percent glutamate was positively correlated to percent abscission throughout the period. Proline, serine, and leucine were positively correlated to abscission from 0 to 2 days after anthesis, whereas significant negative correlations were observed at these ages for ethanolamine and arginine. (75)Se fed as selenate and (14)C fed as sucrose, glycine, and alanine were readily incorporated into soluble and insoluble proteins in a 24-hour in vitro incubation. Radioactivity of total proteins, expressed on a perovary basis, was negatively correlated with percent abscission and positively correlated with ovary weight. [(14)C]Glutamine and serine followed the opposite pattern, with greater protein labeling in abscising than in setting ovaries. When data were expressed as disintegrations per minute per milligram ovary fresh weight, protein labeling from alanine was seen to be significantly greater in abscising ovaries at anthesis and throughout the sampling period. Nucleic acid labeling from uridine was highly correlated to ovary weight; labeling from thymidine was greater in setting than abscising ovaries at anthesis and in abscising ovaries at later stages of development. It is concluded that abscising ovaries can continue amino acid metabolism almost up to the date of separation from the raceme, and that the involvement of alanine, glutamine, aspartate, glutamate, and other amino acids in soybean flower abortion deserves further study. | description |
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| Ghiasi, H, Paech, C, Dybing, C D | authors |
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| Plant Morphological and Biochemical Responses to Field Water Deficits: III. Effect of Foliage Temperature on the Potential Activity of Glutathione Reductase. | name |
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| Activity of glutathione reductase has been related to stress tolerance; however, these enzyme assays are generally conducted at 25 degrees C. Foliage temperature varies greatly in the field in response to soil water availability and ambient conditions and this may affect enzyme response. This study was conducted to determine the effect of changing foliage temperature on glutathione reductase activity of wheat under field conditions. Wheat leaf glutathione reductase was purified and the temperature response of the enzyme was determined at 2.5 degrees C intervals between 12.5 and 45 degrees C. These data, in conjunction with continuous measurements of field-grown wheat foliage temperatures, were used to compare the temperature-related changes in potential glutathione reductase activities in water stressed and control plants. Assuming saturating substrate levels, the results indicate that early in the season the daily potential enzyme activity of the irrigated and stressed plants could never have reached the daily activity predicted from the 25 degrees C (room temperature) measurements. Later in the season, the daily potential activity of the irrigated plants was lower, and the daily potential activity of the stressed plants was higher, than the activities predicted from the 25 degrees C determinations. These results suggest that a better understanding of the regulation of plant metabolism will be obtained by linking continuous temperature measurements of plant foliage with enzyme responses to temperature. | description |
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| Burke, J J, Hatfield, J L | authors |
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| Glycine-Glomus-Rhizobium Symbiosis : VI. Photosynthesis in Nodulated, Mycorrhizal, or N- and P-Fertilized Soybean Plants. | name |
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| Soybean (Glycine max [L.] Merr. cv Hobbit) plants were grown in a growth chamber for 56 days in a phosphorus- and nitrogen-deficient soil and were colonized by the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus mosseae (Nicol. & Gerd) Gerd. and Trappe and Rhizobium japonicum strain USDA 136, or by either organism alone, or by neither. Non-VAM plants received supplemental phosphorus and nonnodulated plants supplemental nitrogen to achieve the same rate of growth in all treatments. Plants of all four treatments had the same (P > 0.05) dry weights at harvest, but VAM plants had higher rates of CO(2) exchange (CER, P < 0.05) and lower leaf P concentrations (P < 0.01). Leaf nitrogen concentrations were lower in nodulated than in nitrogen-supplemented plants (P < 0.01) while starch concentrations were higher (P < 0.01). There was a significant negative relationship between nitrogen and starch (r = -0.989). Statistical evaluation of the data showed that some parameters (CER, leaf area and phosphorus content) were associated with phosphorus nutrition (or the presence of the VAM fungus), others (leaf fresh weight and root dry weight) with nitrogen nutrition (or the presence of Rhizobium), and some (leaf nitrogen and starch content) by both factors. The development of microsymbiont structures and nodule activity were significantly lower in the tripartite association than in plants colonized by one endophyte only. The findings suggest that endophyte effects go beyond those of simple nutrition and associated source-sink relationships. | description |
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| Brown, M S, Bethlenfalvay, G J | authors |
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| Involvement of superoxide radical in extracellular ferric reduction by iron-deficient bean roots. | name |
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| The recent proposal of Tipton and Thowsen (Plant Physiol 79: 432-435) that iron-deficient plants reduce ferric chelates in cell walls by a system dependent on the leakage of malate from root cells was tested. Results are presented showing that this mechanism could not be responsible for the high rates of ferric reduction shown by roots of iron-deficient bean (Phaseolus vulgaris L. var Prélude) plants. The role of O(2) in the reduction of ferric chelates by roots of iron-deficient bean plants was also tested. The rate of Fe(III) reduction was the same in the presence and in the absence of O(2). However, in the presence of O(2) the reaction was partially inhibited by superoxide dismutase (SOD), which indicates a role for the superoxide radical, O(2) ([unk]), as a facultative intermediate electron carrier. The inhibition by SOD increased with substrate pH and with decrease in concentration of the ferrous scavenger bathophenanthroline-disulfonate. The results are consistent with a mechanism for transmembrane electron transport in which a flavin or quinone is the final electron carrier in the plasma membrane. The results are discussed in relation to the ecological importance that O(2) ([unk]) may have in the acquisition of ferric iron by dicotyledonous plants. | description |
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| Cakmak, I, van de Wetering, D A, Marschner, H, Bienfait, H F | authors |
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| Alteration of Gene Expression during the Induction of Freezing Tolerance in Brassica napus Suspension Cultures. | name |
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| Brassica napus suspension-cultured cells can be hardened to a lethal temperature for 50% of the sample of -20 degrees C in eight days at room temperature with abscisic acid. During the induction of freezing tolerance, changes were observed in the electrophoretic pattern of [(35)S]methionine labeled polypeptides. In hardening cells, a 20 kilodalton polypeptide was induced on day 2 and its level increased during hardening. The induction of freezing tolerance with nonmaximal hardening regimens also resulted in increases in the 20 kilodalton polypeptide. The 20 kilodalton polypeptide was associated with a membrane fraction enriched in endoplasmic reticulum and was resolved as a single spot by two-dimensional electrophoresis. In vitro translation of mRNA indicate alteration of gene expression during abscisic acid induction of freezing tolerance. The new mRNA encodes a 20 kilodalton polypeptide associated with increased freezing tolerance induced by either abscisic acid or high sucrose. A 20 kilodalton polypeptide was also translated by mRNA isolated from cold-hardened B. napus plants. | description |
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| Johnson-Flanagan, A M, Singh, J | authors |
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| Orientation of electron transport activities in the membrane of intact glyoxysomes isolated from castor bean endosperm. | name |
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| Intact glyoxysomes were isolated from castor bean endosperm on isometric Percoll gradients. The matrix enzyme, malate dehydrogenase, was 80% latent in the intact glyoxysomes. NADH:ferricyanide and NADH:cytochrome c reductase activities were measured in intact and deliberately broken organelles. The latencies of these redox activities were found to be about half the malate dehydrogenase latency. Incubation of intact organelles with trypsin eliminated NADH:cytochrome c reductase activity, but did not affect NADH:ferricyanide reductase activity. NADH oxidase and transhydrogenase activities were negligible in isolated glyoxysomes. Mersalyl and Cibacron blue 3GA were potent inhibitors of NADH:cytochrome c reductase. Quinacrine, Ca(2+) and Mg(2+) stimulated NADH:cytochrome c reductase activity in intact glyoxysomes. The data suggest that some electron donor sites are on the matrix side and some electron acceptor sites are on the cytosolic side of the membrane. | description |
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| Luster, D G, Donaldson, R P | authors |
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| Mutations in Chlamydomonas reinhardtii Conferring Resistance to the Herbicide Sulfometuron Methyl. | name |
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| Chlamydomonas reinhardtii mutants resistant to the herbicide sulfometuron methyl (SM) were isolated and characterized. Growth of C. reinhardtii is sensitive to inhibition by SM at a concentration of 1 micromolar. Four mutants resistant to 10- to 100-fold higher concentrations were isolated. All possess a form of acetolactate synthase (ALS) whose specific activity in cell extracts is 100- to 1000-fold more resistant to SM than is the specific activity of wild-type enzyme. Only one mutant had abnormally low ALS specific activity in the absence of SM. All mutations were inherited as single lesions in the nuclear genome and were expressed in heterozygous diploids. The mutations in two strains mapped to linkage group IX about 30 centimorgans from streptomycin resistance and on the same side of the centromere, and in genetic crosses between mutants no segregation was observed. Accordingly, all mutations are tentatively assigned to gene smr-1. Herbicide resistance appears to be suitable as a selectable marker for molecular transformation in this organism. | description |
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| Hartnett, M E, Newcomb, J R, Hodson, R C | authors |
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| Reduction State of Q and Nonradiative Energy Dissipation during Photosynthesis in Leaves of a Crassulacean Acid Metabolism Plant, Kalanchoë daigremontiana Hamet et Perr. | name |
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| Fluorescence was measured in leaves of the CAM plant Kalanchoë daigremontiana using a pulse modulation technique at room temperature. During a 12-h light period at 500 micromole photons per square meter per second (400-700 nanometers) in air containing 350 microbar CO(2), the component of fluorescence quenching related to the reduction state of Q, the primary electron transport acceptor of PSII, remained fairly constant and showed that only 20% of Q were in the reduced form. The reduction state was slightly increased at the onset and at the end of the light period. By contrast, the nonphotochemical component of fluorescence quenching which is a measure of the fraction of nonradiative deexcitation underwent marked diurnal changes. Nonradiative energy conversion was low during the phase of most active malic acid decarboxylation in the middle of the light period when uptake of atmospheric CO(2) was negligible, and when internal CO(2) partial pressures were higher than in air; this allowed for high rates of CO(2) reduction in the chloroplasts. Nonradiative energy conversion was high during the early and the late light period when atmospheric CO(2) was taken up and internal CO(2) partial pressures were below air level. Manipulation of the internal CO(2) partial pressure during the late light period by increasing or decreasing the external CO(2) partial pressure to 1710 and 105 microbar, respectively, led to changes in the magnitude of energy dependent fluorescence quenching which were consistent with the relationship between nonradiative energy dissipation and internal CO(2) partial pressure observed during the diurnal cycle. Again, the reduction state of Q was hardly affected by these treatments. Thus, changes in electron transport rate during the diurnal CAM cycle at a given photon flux density lead primarily to alterations in the rate of nonradiative energy dissipation, with the reduction state of Q being maintained at a relatively low and constant level. Conditions are described under which nonphotochemical dissipation of excitation energy reaches a maximum value and the reduction state of Q is increased. | description |
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| Winter, K, Demmig, B | authors |
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| Phytochelatin synthesis and glutathione levels in response to heavy metals in tomato cells. | name |
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| Cell suspension cultures of tomato, Lycopersicon esculentum Mill. cv VFNT-Cherry, produce phytochelatins (poly[gamma-glutamylcysteinyl]glycines) when exposed to cadmium. The synthesis of these peptides is accompanied by a decline in cellular levels of glutathione. Buthionine sulfoximine, an inhibitor of glutathione synthesis, inhibits the sustained production of phytochelatins. However, phytochelatin synthesis can occur in the presence of buthionine sulfoximine provided that sufficient glutathione is available. These results indicate that glutathione is a substrate for phytochelatin synthesis. The protein synthesis inhibitor cycloheximide does not affect the initial production of phytochelatin. | description |
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| Scheller, H V, Huang, B, Hatch, E, Goldsbrough, P B | authors |
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| Osmotic adjustment, symplast volume, and nonstomatally mediated water stress inhibition of photosynthesis in wheat. | name |
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| At low water potential (psi(w)), dehydration reduces the symplast volume of leaf tissue. The effect of this reduction on photosynthetic capacity was investigated. The influence of osmotic adjustment on this relationship was also examined. To examine these relationships, comparative studies were undertaken on two wheat cultivars, one that osmotically adjusts in response to water deficits (;Condor'), and one that lacks this capacity (;Capelle Desprez'). During a 9-day stress cycle, when water was withheld from plants grown in a growth chamber, the relative water content of leaves declined by 30% in both cultivars. Leaf osmotic potential (psi(s)) declined to a greater degree in Condor plants. Measuring psi(s) at full turgor indicated that osmotic adjustment occurred in stressed Condor, but not in Capelle plants. Two methods were used to examine the degree of symplast (i.e. protoplast) volume reduction in tissue rapidly equilibrated to increasingly low psi(w). Both techniques gave similar results. With well-watered plants, symplast volume reduction from the maximum (found at high psi(w) for each cultivar) was the same for Condor and Capelle. After a stress cycle, volume was maintained to a greater degree at low psi(w) in Condor leaf tissue than in Capelle. Nonstomatally controlled photosynthesis was inhibited to the same degree at low psi(w) in leaf tissue prepared from well-watered Condor and Capelle plants. However, photosynthetic capacity was maintained to a greater degree at low psi(w) in tissue prepared from stressed Condor plants than in tissue from stressed Capelle plants. Net CO(2) uptake in attached leaves was monitored using an infrared gas analyzer. These studies indicated that in water stressed plants, photosynthesis was 106.5% higher in Condor than Capelle at ambient [CO(2)] and 21.8% higher at elevated external [CO(2)]. The results presented in this report were interpreted as consistent with the hypothesis that there is a causal association between protoplast (and presumably chloroplast) volume reduction at low psi(w) and low psi(w) inhibition of photosynthesis. Also, the data indicate that osmotic adjustment allows for maintenance of relatively greater volume at low psi(w), thus reducing low psi(w) inhibition of chloroplast photosynthetic potential. | description |
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| Gupta, A S, Berkowitz, G A | authors |
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| Bacillus thuringiensis section sign-Endotoxin Expressed in Transgenic Nicotiana tabacum Provides Resistance to Lepidopteran Insects. | name |
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| The crystal proteins, or section sign-endotoxins, of Bacillus thuringiensis are specifically lethal to Lepidopteran insects. We utilized a truncated and modified portion of a cloned crystal protein gene to construct a chimeric gene capable of expression in plant cells. Using an Agrobacterium tumefaciens binary vector system, we then transferred the chimeric toxin gene into tobacco (Nicotiana tabacum cv Havana 425) cells and regenerated recombinant plants. One to several copies per cell of the toxin gene are routinely present in the recombinant plants. Hybridization experiments demonstrated that these plants had a new RNA species of the size expected for the truncated toxin mRNA, and a polypeptide having the mobility expected for the truncated toxin was detected by immunoblotting. Significant variation was found in the levels of toxin-specific RNA expression between different recombinants, but the levels of hybridizing RNA in transformants correlated with the level of toxicity demonstrated against Manduca sexta (tobacco hornworm), and other Lepidopteran insects. The recombinant genes were transmitted to progeny and resistance to insects was maintained, thus demonstrating that the introduction of toxin genes into plants may be a practical method of providing protection against certain insect pests. | description |
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| Barton, K A, Whiteley, H R, Yang, N S | authors |
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| Isolation and characterization of plant genes coding for acetolactate synthase, the target enzyme for two classes of herbicides. | name |
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| Acetolactate synthase (ALS) is the first common enzyme in the biosynthetic pathways to valine, isoleucine, and leucine. It is the target of two structurally unrelated classes of herbicides, the sulfonylureas and the imidazolinones. Genomic clones encoding ALS have been isolated from the higher plants Arabidopsis thaliana and Nicotiana tabacum, using a yeast ALS gene as a heterologous hybridization probe. Clones were positively identified by the homology of their deduced amino acid sequences with those of yeast and bacterial ALS isozymes. The tobacco and Arabidopsis ALS genes have approximately 70% nucleotide homology, and encode mature proteins which are approximately 85% homologous. Little homology is seen between the amino acid sequences of the presumptive N-terminal chloroplast transit peptides. Both plant genes lack introns. The tobacco ALS gene was isolated from a line of tobacco which is resistant to the sulfonylurea herbicides due to an alteration in ALS. The tobacco gene which was isolated codes for an ALS that is sensitive to the herbicides, as assayed by transformation of the gene into sensitive tobacco cells. | description |