bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of Rubisco by inhibitors in the light
Authors: PARRY M. A. J. , ANDRALOJC P. J. , PARMAR S. , KEYS A. J. , HABASH D. , PAUL M. J. , ALRED R. , QUICK W. P. , SERVAITES J. C. 
Published: November 2003

ABSTRACT2‐carboxy‐D‐arabinitol‐1‐phosphate (CA1P) bound to Rubisco either in leaf extracts or after purification can be displaced by SO42− ions. Thus, treatment of leaf extracts with a buffer containing 200 mol m−3 SO42− displaces any bound CA1P and enables measurement of maximum car‐boxylation potential. In tobacco leaves, the activity following treatment with SO4−2 ions (‘maximal activity’) is greater than the total Rubisco activity. The ratio of the two activities altered in a dynamic way with fluctuations in irradiance. Even in species which do not produce significant amounts of CA1P, the maximal activity greatly exceeded the total activity. Anion exchange separation of components in acid extracts confirmed the absence of CA1P in tobacco leaves harvested above an irradiance of 300 μmol quanta m−2 s−1, but the presence of another inhibitor of Rubisco. These results are consistent with the regulation of Rubisco activity by inhibitors other than CA1P which, like CA1P, can be displaced by SO42− ions.
Striga hermonthica reduces photosynthesis in sorghum: the importance of stomatal limitations and a potential role for ABA?
Authors: FROST D. L. , GURNEY A. L. , PRESS M. C. , SCHOLES J. D. 
Published: November 2003

ABSTRACTWe report the effects of the root hemiparasite Striga hermonthica (Del.) Benth. on the growth and photosynthesis of two cultivars of sorghum: CSH‐1, a susceptible variety, and Ochuti, which shows some tolerance to S. hermonthica in the field. Within 4 d of parasite attachment to the host roots, infected plants of both cultivars were significantly shorter than uninfected controls. At 55 d, infected plants of both cultivars had significantly less shoot and root biomass, and significantly smaller leaf areas than uninfected controls. The dry weight of S. hermonthica attached to host roots was insufficient at this stage to explain the decreased growth in terms of a competing sink for carbon and nitrogen. Leaf chlorophyll and nitrogen per unit area were greater in infected plants of both cultivars compared with control plants. However, whereas photosynthesis and transpiration in young leaves of infected CSH‐1 plants declined with time when compared with controls, the rates in infected Ochuti plants were similar to those in uninfected controls throughout the time course of observation. In both cultivars, a strong correlation was observed between the rate of photosynthesis and stomatal conductance during photosynthetic induction, but infection resulted in a much slower induction than in controls. In CSH‐1 plants, both steady‐state photosynthesis and stomatal conductance were lower than in controls, whereas in leaves of Ochuti steady‐state photosynthesis and stomatal conductance eventually reached the same values as in the control leaves. Results from AlCi analysis and also from determination of 13C isotope discrimination were consistent with a stomatal limitation to photosynthesis in the leaves of Striga‐infected plants. The concentration of the plant growth regulator abscisic acid (ABA) was measured in the xylem sap of infected CSH‐1 plants only, and was found to be twice that of uninfected plants. A possible role of ABA in determining host response to infection by S. hermonthica is discussed.
Kinetics and relative significance of remobilized and current C and N incorporation in leaf and root growth zones of Lolium perenne after defoliation: assessment by 13C and 15N steady‐state labelling
Authors: DE VISSER R. , VIANDEN H. , SCHNYDER H. 
Published: November 2003

ABSTRACTThe contribution of pre‐defoliation reserves and current assimilates to leaf and root growth was examined in Lolium perenne L. during regrowth after defoliation. Differential steady‐state labelling with 13C (CO2 with δ13C = ‐0.0281 and ‐0.0088) and 15N (NO3− with 1.0 and 0.368 atom percentage, i.e. δ15N = 1.742 and 0.0052, respectively) was applied for 2 weeks after defoliation. Rapidly growing tissues were isolated, i.e. the basal elongation and maturation zones of the most rapidly expanding leaves and young root tips, with a biomass turnover rate > 1 d−1. C and N weights of the elongation zone showed a transient decline. The dry matter and C concentration in fresh biomass of leaf growth zones transiently decreased by up to 25% 2 d after defoliation, while the N concentration remained constant. This ‘dilution’ of growth zone C indicates a decreased net influx of carbohydrates relative to growth‐related influx of water and N in expanding cells, immediately after defoliation. Recovery of the total C and N weights of the leaf elongation zone coincided with net incorporation of currently absorbed C and N, as shown by the kinetics of δ13C and atom percentage 15N in the growth zones after defoliation. C isotope discrimination (Δ13C) in leaf growth zones was about 23‰, 1–2‰ higher than the Δ in root tips. Δ15N in the leaf and root growth zones was 10±3‰. The leaf elongation zones (at 0–0.03 m from the tiller base) and the distant root tips (about 0.2 m from the base) exhibited similar kinetics of current C and N incorporation. The amount of pre‐defoliation C and N in the growth zones, expressed as a fraction of total C and N, decreased from 1.0 to 0.5 at 3 (C) and 5 (N) d after defoliation, and to 0.1 at 5 (C) and 14 (N) d after defoliation. Thus, the dependence of growth zones on current assimilate supply was significant, and stronger for C than for N. The important roles of current assimilates (as compared to pre‐defoliation reserves) and ‘dilution’ of dry matter in regrowth after defoliation are discussed in relation to the method of labelling and the functional and morphological heterogeneity of shoot tissues.
Detoxification of xenobiotics in plant cells by glutathione conjugation and vacuolar compartmentalization: a fluorescent assay using monochlorobimane
Authors: COLEMAN J. O. D. , RANDALL R. , BLAKE‐KALFF M. M. A. 
Published: November 2003

ABSTRACTMonochlorobimane (BmCl), a non‐fluorescent cell‐per‐meant compound that reacts with glutathione to yield a strong blue fluorescent conjugate bimane‐glutathione (Bm‐SG), was used to trace the glutathione‐dependent detoxification of xenobiotics in plant cells and protoplasts. In BmCl‐labelled cells and protoplasts, fluorescence developed rapidly and was quickly concentrated in the vacuole. The rate of fluorescence development was dependent on the concentration of BmCl and the only metabolite formed was the conjugate Bm‐SG. The formation of Bm‐SG was correlated with a decrease in the amount of intracellular GSH. Compounds which reduced the intracellular levels of GSH severely reduced the formation of Bm‐SG. Bm‐SG was shown to be transported into isolated vacuoles by an ATP‐dependent vana‐date‐sensitive mechanism. Kinetic analysis of cellular Bm‐SG formation implicated both spontaneous conjugation and enzyme catalysis. Our results demonstrate a cellular pathway for xenobiotic detoxification in plants, starting with conjugation to glutathione in the cytoplasm, followed by the transport of the conjugates into the vacuole. This pathway is used to counter the toxic effects of some herbicides and environmental pollutants and overlaps with or parallels the pathway used for the biosynthesis of anthocyanins.
Xylem dysfunction caused by water stress and freezing in two species of co‐occurring chaparral shrubs
Authors: LANGAN S. J. , EWERS F. W. , DAVIS S. D. 
Published: November 2003

ABSTRACTWater transport from the roots to leaves in chaparral shrubs of California occurs through xylem vessels and tracheids. The formation of gas bubbles in xylem can block water transport (gas embolism), leading to shoot dieback. Two environmental factors that cause gas embolism formation in xylem conduits are drought and freezing air temperatures. We compared the differential vulnerabilities of Rhus laurina and Ceanothus megacarpus, co‐dominant shrub species in the coastal regions of the Santa Monica Mountains of southern California, to both water stress‐induced and freezing‐induced embolism of their xylem. Rhus laurina has relatively large xylem vessel diameters, a deep root system, and a large basal burl from which it vigorously resprouts after wildfire or freezing injury. In contrast, Ceanothus megacarpus has small‐diameter vessels, a shallow root system, no basal burl and is a non‐sprouter after shoot removal by wildfire. We found that R. laurina became 50% embolized at a water stress of –3 MPa and 100% embolized by a freeze–thaw cycle at all hydration levels. In contrast, C. megacarpus became 50% embolized at a water stress of –9 MPa and 100% embolized by freeze–thaw events only at water potentials lower than –3 MPa. Reducing thaw rates from 0·8 °C min−1 to 0·08 °C min−1 (the normal thaw rate measured in situ) had no effect on embolism formation in R. laurina but significantly reduced embolism occurrence in well‐hydrated C. megacarpus (embolism reduced from 74 to 35%). These results were consistent with the theory of gas bubble formation and dissolution in xylem sap. They also agree with field observations of differential shoot dieback in these two species after a natural freeze–thaw event in the Santa Monica Mountains.
Is photomorphogenic shade avoidance adaptive? Perspectives from population biology
Authors: SCHMITT J. 
Published: November 2003

ABSTRACTPhotomorphogenic shade avoidance responses provide an ideal model system for integrating genetic, physiological and population biology approaches to the study of adaptive plasticity. The adaptive plasticity hypothesis predicts that shade avoidance phenotypes induced by low ratios of red to far‐red light (R:FR) will have high relative fitness in dense stands, but will suffer a fitness disadvantage at low density. Experiments with transgenic and mutant plants in which photomorphogenic genes are disabled, as well as phenotype manipulation by means of altered R:FR, strongly support the shade avoidance hypothesis. The observation of photomorphogenic ecotypes in different selective environments also suggests that the shade avoidance response has undergone adaptive evolution. Quantitative genetic variation in R:FR sensitivity has been detected in wild populations, indicating that the evolutionary potential exists for response to natural selection. However, evolutionary response may be constrained by genetic correlations among developmentally linked traits. Therefore it cannot be assumed that an observed suite of photomorphogenic responses represents an adaptive optimum for every trait.
The COP9 complex: a link between photomorphogenesis and general developmental regulation?
Authors: CHAMOVITZ D. A. , DENG X.‐W. 
Published: November 2003

ABSTRACTLight signals perceived by photoreceptors are transduced into the nucleus to regulate gene expression and development. The COP9 protein complex localized in the nucleus has a central role in modulating light‐regulated development, and may have a role in regulating development in general in all organisms. This review considers recent advances in the study of the COP9 complex and its sub‐units in plant and animal systems, and discusses the possible functional implications.
Signal transduction in the photocontrol of chalcone synthase gene expression*
Authors: SCHÄFER E. , KUNKEL T. , FROHNMEYER H. 
Published: November 2003

ABSTRACTThe photocontrol of chalcone synthase gene expression was studied by means of promoter analyses, in vitro systems, photoreceptor mutants and microinjections, and pharmacological approaches. A 52 bp element of the promoter is necessary and sufficient to transfer light regulation. Chalcone synthase expression is primarily under the control of phyA and blue/UV photo receptors; the latter are functional even in the absence of phyA and phyB. Phytochromes seem to be soluble proteins and, within seconds of irradiation, light‐dependent phosphorrylations were observed in membrane‐depleted cytosol preparations, indicating very early processes of signal transduction. Microinjection and pharmacological experiments reveal that, in the phyA pathway, heterotrimeric G‐proteins, cGMP and a genistein‐sensitive protein kinase are involved, whereas the UV pathway includes several trimeric G‐proteins and Ca/calmodulin‐dependent steps.
Gibberellins, brassinosteroids and light‐regulated development
Authors: CHORY J. , LI J. 
Published: November 2003

ABSTRACTThe regulation of plant development by light requires the action of several well‐studied plant hormones. However, the mechanism by which light and hormones affect identical developmental responses remains unclear. Recently, studies of mutants altered in light signal perception or transduction have suggested a role for gibberellins and brassinosteroids in light‐regulated development. For instance, mutants in the major light‐stable phytochrome from several plant species exhibit altered responsiveness to, or metabolism of, gibberellins. In contrast, mutants that develop as light‐grown plants in the absence of light have implicated a role for brassinosteroids in the control of cell elongation, the expression of photoregulated genes, and the promotion of apical dominance, leaf senescence and male fertility. Future studies should help elucidate whether light and hormones independently affect these developmental responses or whether hormones are involved in the sequence of events initiated by excitation of photoreceptors.
Immunohistochemical analysis of procathepsin L and cathepsin B in cutaneous Kaposi's sarcoma
Authors: Thewes Matthias , Engst Reinhard , Jürgens Maren , Borelli Siegfried 
Published: November 2003

Abstract Background The expression of the proteinases cathepsins L and B are induced in tumors by malignant transformation, growth factors, and tumor promoters suggesting they play an important role in tumor invasion and metastasis. Methods By immunohistochemistry, procathepsin L and cathepsin B were studied in patients with Kaposi's sarcoma (KS). Formalin‐fixed and paraffin‐embedded tissues from 29 cases of KS (AIDS‐associated KS, n= 24; non‐AIDS‐associated KS, n= 5) were immunolabeled with the polyclonal antibody directed against procathepsin L and the antisera directed against cathepsin B. Results Normal epidermis, eccrine sweat glands, and hair follicle expressed both cathepsins. We also found a positive staining for procathepsin L in normal blood vessels. In both “angiomatous” and “fibroblastic” lesions of KS no expression of these enzymes was observed. Conclusions These findings support the hypothesis of a benign autochthonous origin of the lesions, such as a hyperplasia.
Onchocerciasis: clinical presentation and host parasite interactions in patients of Southern Sudan
Authors: Stingl Peter 
Published: November 2003

Abstract Background Onchocerciasis, an infection by the filarial nematode Onchoverca volvulus, is widely distributed in tropical Africa and of great dermatologic interest. This study analyses the dermatologic presentation and tries to determine the correlations between clinical disease and host parasite interactions in onchocerciasis patients of the Southern Sudan. Methods We performed clinical and histopathologic investigations in patients with onchocerciasis in the Wau District, Bahr el Ghazal Province, Southern Sudan. As well as a detailed clinical skin examination, skin biopsies were taken, processed, and Investigated for type and degree of host tissue response. Parasitologic, clinical, and histopathologic findings were evaluated. Results Onchocerciasis appears with a variety of severe skin lesions. Central is a pruritic rash. Long‐standing cases develop extensive pigmentary changes and impressive signs of skin tissue exhaustion. Cellular host tissue responses to degenerating skin microfilariae seem to play a key role in the development of skin pathology. The degree of host response appears to be inversely proportional to the host's microfilarial load. Conclusions Onchocerciasis represents a health problem of great dermatologic importance in Southern Sudan. The study results demonstrate clinical variations in onchocerciasis and provide support for the existence of a disease spectrum.
An outbreak of paederus dermatitis in a suburban hospital in Sri Lanka
Authors: Kamaladasa Satheeka D. , Perera W.D.H. , Weeratunge L. 
Published: November 2003

Abstract Background In a modern hospital built recently in Sri Lanka the staff members on night shifts and some patients in the open wards were known to be affected by an acute vesicating dermatitis. The study was carried out to identify the cause of the dermatitis and recommend preventive measures. Methods Members of the hospital staff and patients who developed an acute vesicating dermatitis over a period of 2 years were studied using a questionnaire. The clinical features, relationship to night shifts and the month of occurrence were noted. Insects were caught at night on several occasions and identified. Lesions were reproduced in volunteers. Results Out of a total of 124 patients studied, 108 were members of the hospital staff and it was noted that they had all been on night shifts within 2 days prior to the onset of the lesions. The insect caught belongs to class Coleoptera, family Staphylinidae, genus Paederus, and species fuscipes. The incidence was seasonal with clustering of cases seen to occur twice a year. Conclusions This IS an outbreak of dermatltls due to Paederus fusicipes. Awareness of the condition and its clinical features will prevent misdiagnosis and the simple preventive measures suggested are based on the behavioral pattern of this nocturnal beetle.
A distinctive vesiculopustular eruption associated with hepatobiliary disease
Authors: Magro Cynthia M. , Crowson A. Neil 
Published: November 2003

Abstract Background Cutaneous manifestations of hepatobiliary disease may be a clue to the clinical diagnosis. We encountered a form of vesiculopustular eruption in five patients with hepatobiliary disease. A similar eruption has been described in the setting of ulcerative colitis, and has received the designation of vesiculopustular pyoderma gangrenosum. Methods Skin biopsy specimens were examined by conventional histopathologic methods and, in three cases, fresh tissue was available for direct immunofluorescence examination. A diagnosis of hepatobiliary disease was known in three of the patients and in the other two it was established by the skin biopsies. Results All skin biopsies of the five patients showed a neutrophilic dermatosis that had two morphologies. One was characterised by superficial neutrophilic dermolysis with subepidermal bulla formation and the other by a nonulcerating destructive suppurative folliculitis and perifollicular neutrophilic dermolysis. Both were frequently accompanied by a neutrophilic and lymphotic eccrine hidradermitis and a Sweet's syndrome‐like vascular reaction. The lesions were held to represent a novel vesiculopustuiar eruption with features reminiscent of pyoderma gangrenosum. Conclusions We propose the term vesiculopustular eruption of hepatobiliary disease for this distinctive clinicopathologic entity, which bears a strong histologic resemblance to pyoderma gangrenosum. Patients with a known hepatopathy who present with necrotizing vesicles and pustules may have such an eruption. The onset may be the first clue to or herald an exacerbation of underlying liver disease.
Colchicine as a novel therapeutic agent in chronic bullous dermatosis of childhood
Authors: Banodkar Degamber D. , Al‐Suwaid Abdul Raouf 
Published: November 2003

Abstract Background The treatment of chronic bullous dermatosis of childhood (CBDC) so far has been limited to the use of corticosteroids and the sulfa group of drugs, e.g. daspsone and sulfapyridine. Furthermore, the therapy of CBDC cases with associated G6 PD deficiency is restricted only to systemic steroids. Histopathologically CBDC is characterized by the presence of predominantly neutrophilic Infiltration and because it has been proven to exert strong anti‐inflammatory effects through the inhibition of neutrophils, colchicine was mandated for its use in CBDC. Methods To avoid the detrimental side‐effects of the long‐term use of steroids in children, an alternative anti‐inflammatory drug like colchicine was considered. Patients with G6 PD deficiency and those who were not satisfactorily controlled with steroid therapy, and who in addition developed unacceptable side‐effects like cushingoid faces and hypertrichiosis, were treated with the drug. Results Eight patients were given colchicine, five (62.5%) of which showed complete remission within 4–6 weeks of starting the therapy. The remaining three (37.5%) also responded but required adjuvant small doses of steroids to maintain the remissions. The drug was very well tolerated and no side‐effects were observed. ConclusionsColchicine is, therefore, found to be an effective treatment in CBDC and has enhanced our armamentarium of therapeutics for this condition, especially in children with G6 PD deficiency.
Perforating granuloma annulare
Authors: Peñas Pablo F. , Jones‐Caballero María , Fraga Javier , Sánchez‐Pérez Javier , García‐Díez Amaro 
Published: November 2003

Abstract Background Perforating granuloma annulare (PGA) is considered an histologic subtype of granuloma annulare (GA) and it is described as a very rare disease, usually of children, affecting the dorsum of the hands. Mechanisms leading to perforation are unknown. Our experience suggested a different clinical presentation, so we decided to review our patients and the cases published. Methods We present six cases of PGA and review 52 PGA cases reported in the literature. Data regarding sex, age, time of evolution of disease, clinical features, laboratory findings, treatment, and follow‐up were collected. The significance level was determined by the χ2 or Student t test when appropriate. Results The prevalence of PGA could be up to 5% of GA. Pustular‐like lesions can be found in 26% of cases, and scars in 37%; papular, umbilicated, and crusted lesions being the most common finding. While PGA appears as a single lesion in only 9% of cases, and half of the patients are older than 30 years, in GA 50% of cases present as a single lesion and 80% of patients are younger than 30 years. Conclusions PGA is different to GA not only histologically but also clinically. It is a disseminated disease, affecting both children and adults, which is characterized by the presence of multiple papules, most of them umbilicated and/or crusted, and characteristically pustular lesions and scars. Histology suggests that the superficial localization of the necrobiotic granuloma leads to the epidermal perforation. Treatment is disappointing.
Epidemiology of primary cutaneous malignant melanoma in Jordan
Authors: Oumeish Oumeish Youssef 
Published: November 2003

Abstract Background Primary cutaneous malignant melanoma is an uncommon tumor in Jordan compared with other countries. There are no previous comprehensive Jordanian studies on this tumor and proper statistical data on morbidity and incidence are nonexistent. The purpose of this paper was to study the epidemiologic aspects of cutaneous malignant melanoma among Jordanians. Methods Both the clinical and the histopathologic feature of 138 melanoma patients (86 men, median age 56; 52 women, median age 53) seen during the period November 1969‐May 1994 were studied. The analysed data included age, sex, skin type, race, socioeconomic status, exposure to sunlight, trauma, and family history. Results Malignant melanoma was found to be more common in men than women, in the ratio of approximately 2:1, due to the higher exposure of men to sunlight, and occurred more in people with skin types I, II, and III, and less in people with skin types IV and V. The majority of cases were of the superficial spreading variety, followed by the nodular, lentigo maligna, and acrolentiginous melanomas, respectively. Conclusion The incidence of cutaneous malignant melanoma, formerly considered a rare tumor in Jordan, is now recognized to be on the increase. Exposure to sunlight seems to be the most prominent risk factor in the development of this tumor among Jordanians.