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  • 11
    Electronic Resource
    Electronic Resource
    Seasonal changes in xanthophyll cycle-dependent energy dissipation in Yucca glauca Nuttall (1998)
    Oxford, UK : Blackwell Science Ltd, UK
    Plant, cell & environment 21 (1998), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The evergreen species Yucca glauca was characterized at the end of September and following exposure to low temperatures at the end of November. In November the diurnal pattern of xanthophyll cycle-dependent energy dissipation was altered such that this thermal dissipation process was engaged at a high level throughout the day, whereas in September it only became engaged when leaves received direct sunlight. An analysis of the diurnal partitioning of the absorbed excitation energy into photochemistry versus thermal dissipation suggested that a smaller fraction of that energy was utilized in photochemistry and a greater fraction was dissipated thermally at the end of November compared to September. Lower ratios of Chl a/b and β-carotene/xanthophylls both suggested a decrease in the ratio of reaction centre plus core antenna proteins compared to light-harvesting proteins, and a lower leaf chlorophyll content suggested a decrease in light-harvesting capacity in November versus September. Thus adjustments to the photosynthetic apparatus occurred on several levels in response to the increase in excess excitation energy that Y. glauca experienced during the onset of winter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1998.00283.x
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  • 12
    Electronic Resource
    Electronic Resource
    Internal and external photoprotection in developing leaves of the CAM plant Cotyledon orbiculata (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 20 (1997), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Leaves of the CAM plant Cotyledon orbiculata produced a dense epidermal wax which decreased the absorption of light, possibly functioning as an external photoprotective mechanism (Robinson et al. 1993). However, developing leaves did not accumulate wax until after 21 d with full wax coating not achieved until at least 35 d. In addition, young leaves had lower rates of electron transport than mature leaves. Leaf development therefore occurs at higher incident PFD than that experienced by the mature leaves, and, for young leaves, can lead to an increase in the proportion of light energy which is excess to requirements and must be dissipated non-photochemically. Changes in the photosynthetic capacity, PSII efficiency, rate of energy dissipation, and the content of chlorophyll (Chi), carotenoids, wax and anthocyanins were followed in developing leaves of C. orbiculata in an attempt to elucidate the relative importance of the various photoprotective mechanisms during leaf ontogeny. The largest pools of xanthophyll cycle pigments (on a Chi basis) were found in the waxless, young leaves and were correlated with greater levels of energy dissipation activity. The importance of xanthophyll cycle-dependent energy dissipation in young C. orbiculata leaves prior to development of a reflective wax covering, and full photosynthetic capacity which for CAM plants includes appreciable nocturnal acid accumulation, is discussed. Also, we consider the possibility that anthocyanin pigments in the upper and lower epidermis may increase reflectivity and act as external photoprotectants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1997.00078.x
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  • 13
    Electronic Resource
    Electronic Resource
    Nocturnally retained zeaxanthin does not remain engaged in a state primed for energy dissipation during the summer in two Yucca species growing in the Mojave Desert (2002)
    Oxford, UK : Blackwell Science, Ltd
    Plant, cell & environment 25 (2002), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Differently oriented leaves of Yucca schidigera and Yucca brevifolia were characterized in the Mojave Desert with respect to photosystem II and xanthophyll cycle activity during three different seasons, including the hot and dry summer, the relatively cold winter, and the mild spring season. Photosynthetic utilization of a high percentage of the light absorbed in PSII was observed in all leaves only during the spring, whereas very high levels of photoprotective, thermal energy dissipation were employed both in the summer and the winter season in all exposed leaves of both species. Both during the summer and the winter season, when energy dissipation levels were high diurnally, xanthophyll cycle pools (relative to either Chl or other carotenoids) were higher relative to the spring, and a nocturnal retention of high levels of zeaxanthin and antheraxanthin (Z + A) occurred in all exposed leaves of both species. Although this nocturnal retention of Z + A was associated with nocturnal maintenance of a low PSII efficiency (Fv/Fm) on a cold winter night, pre-dawn Fv/Fm was high in (Z + A)-retaining leaves following a warm summer night. This indicates nocturnal engagement of Z + A in a state primed for energy dissipation throughout the cold winter night – while high levels of retained Z + A were not engaged for energy dissipation prior to sunrise on a warm summer morning. Possible mechanisms for a lack of sustained engagement of retained Z + A for energy dissipation at elevated temperatures are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.0016-8025.2001.00803.x
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  • 14
    Electronic Resource
    Electronic Resource
    Rapid changes in xanthophyll cycle-dependent energy dissipation and photosystem II efficiency in two vines, Stephania japonica and Smilax australis, growing in the understory of an open Eucalyptus forest (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 22 (1999), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Leaves of Stephania japonica and Smilax australis were characterized in situ on the coast of north-eastern New South Wales, Australia, where they were growing naturally in three different light environments: deep shade, in the understory of an open Eucalyptus forest where they received frequent sunflecks of high intensity, and in an exposed site receiving full sunlight. In deep shade the xanthophyll cycle remained epoxidized during the day and the vast majority of absorbed light was utilized for photosynthesis. In the exposed site both deepoxidation and epoxidation of the xanthophyll cycle and changes in the level of xanthophyll-dependent thermal energy dissipation largely tracked the diurnal changes in photon flux density (PFD). In the understory the xanthophyll cycle became largely deepoxidized to zeaxanthin and antheraxanthin upon exposure of the leaves to the first high intensity sunfleck and this high level of deepoxidation was maintained throughout the day both during and between subsequent sunflecks. In contrast, thermal energy dissipation activity, and the efficiency of photosystem II, fluctuated rapidly in response to the changes in incident PFD. These findings suggest a fine level of control over the engagement of zeaxanthin and antheraxanthin in energy dissipation activity, presumably through rapid changes in thylakoid acidification, such that they became rapidly engaged for photoprotection during the sunflecks and rapidly disengaged upon return to low light when continued engagement might limit carbon gain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1999.00369.x
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  • 15
    Electronic Resource
    Electronic Resource
    Acclimation of leaf carotenoid composition and ascorbate levels to gradients in the light environment within an Australian rainforest (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 19 (1996), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The influence of the growth photon flux density (PFD) on the size and composition of the carotenoid pool and the size of the reduced ascorbate pool was determined across a light gradient from the forest floor to the canopy and the forest edge of a sub-tropical rainforest in New South Wales, Australia. Nineteen plant species (most collected from multiple sites) representing a broad taxonomic range consistently possessed larger total carotenoid pools when found growing in more exposed sites. There was a significant positive correlation between β-carotene content and growth PFD and a significant negative correlation between α-carotene content and growth PFD. Neoxanthin content exhibited no significant trend while the trend in lutein content varied with mode of expression. The pigments of the xanthophyll cycle (violaxanthin, antheraxanthin and zeaxanthin) exhibited the most pronounced response to growth PFD; they comprised a much greater portion of the total carotenoid pool in high light-acclimated plants. The pool of reduced ascorbate was also several-fold greater in high light-acclimated plants. These acclimatory changes in carotenoid and ascorbate content are consistent with a need for a greater capacity to dissipate excessive absorbed light energy in high light-acclimated plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1996.tb00215.x
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  • 16
    Electronic Resource
    Electronic Resource
    Plant diversity effects on herbage production and compositional changes in New Zealand hill country pastures (2004)
    Oxford, UK : Blackwell Science Ltd
    Grass and forage science 59 (2004), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A small-plot field experiment on grazed hill country pastures in the North Island of New Zealand was conducted to examine the productivity and compositional characteristics of swards in response to variation in pasture species diversity. The balanced incomplete factorial design incorporated variation in location, slope, soil fertility and combinations of eight plant functional groups (C4 grasses, annual grasses, annual legumes, perennial C3 grasses, perennial legumes, perennial forbs, ryegrass and browntop). Net herbage accumulation and botanical composition were measured at 18 months (spring) and 24 months (autumn) after oversowing following application of a systemic herbicide. Analysis of variance indicated a significant positive relationship between the number of functional groups sown and herbage accumulation of the sown species in spring, but not with total herbage accumulation. Regression analysis showed that herbage accumulation was also affected by the identity of the functional groups. However, the statistical models indicated that pasture productivity was most strongly influenced by site factors. There was a significant negative relationship between both the number and herbage accumulation of unsown species and the number of functional groups sown, indicating a positive relationship between diversity and resistance to invasion by unsown species. A comparison of the vegetation between the plots before and after oversowing showed that those more diverse prior to sowing returned to their initial composition more rapidly, evidence that diverse vegetation was more resilient in the face of disturbance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.2004.00402.x
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  • 17
    Electronic Resource
    Electronic Resource
    Disproportionate fetal growth and raised IgE concentration in adult life (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 24 (1994), S. 0 
    Details
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. A follow-up study was carried out to determine whether either impaired or disproportionate fetal growth are associated with a raised total serum IgE concentration in men and women aged 50 years. The serum IgE concentration was measured in 146 men and 134 women born in Preston (Lancashire, UK) between 1935 and 1943, whose size at birth had been measured in detail.Sixty-two subjects were found to have an IgE concentration above 80 IU/ml. Compared with subjects with a normal IgE on average they had a 0.30 inch larger head circumference at birth (P -0.004) and weighed 5.6 ounces more at birth (P= 0.04). People with a raised and with a normal IgE were of similar crown-heel length at birth, indicating that in utero those with a raised IgE had had disproportionate growth of the head in relation to the trunk and limbs. The prevalence of a raised IgE rose from 14% in subjects whose head circumference at birth was 13 inches or less to 37% in those whose head circumference was more than 14 inches. This association was independent of gestational age at birth and of the mother's pelvic size and parity. It was also independent of adult physique, social class and smoking, and was similar in men and women. In multiple logistic regression analyses odds ratios of a raised IgE rose progressively to more than 4 as head circumference at birth increased from 13 inches or less to more than 14 inches.One possibility is that these associations reflect the long-term effects of sustaining fetal brain growth at the expense of the trunk, in particular the thymus. This may be a consequence of fetal under-nutrition in late gestation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2222.1994.tb00968.x
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  • 18
    Electronic Resource
    Electronic Resource
    Effects on plaque and gingivitis of a chlorhexidine dental gel in the mentally retarded (1977)
    Oxford, UK : Blackwell Publishing Ltd
    Community dentistry and oral epidemiology 5 (1977), S. 0 
    Details
    ISSN: 1600-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The effectiveness of a 1 % chlorhexidine-containing dental gel on dental plaque and gingival health was evaluated over a period of 6 months using a double-blind procedure. One hundred and seventeen mentally retarded subjects aged between 10–17 years resident in an institution were divided into two groups. One group was assigned daily brushing with the 1 % chlorhexidine gel, the other group a placebo quinine sulfate-containing gel. No other form of oral hygiene was used during the experimental period. Assessment of dental plaque accumulation and gingivitis was made at 0, 1, 3, and 6 months. An assessment was also made 2 months after the gel was withdrawn from use and normal toothbrushing procedures resumed. No clinical or statistical advantage was noted in plaque or gingivitis scores in the group receiving chlorhexidine treatment during the 6-month period. This group showed a higher prevalence of tooth staining. It was concluded that periodontal severity and poor oral hygiene exceeded the plaque- and gingivitis-preventing potential of chlorhexidine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0528.1977.tb01000.x
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  • 19
    Electronic Resource
    Electronic Resource
    Damage, recovery and survival of 0-group mulloway, Argyrosomus japonicus, after simulated escape through square mesh (2005)
    Berlin, Germany : Blackwell Verlag GmbH
    Journal of applied ichthyology 21 (2005), S. 0 
    Details
    ISSN: 1439-0426
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A laboratory experiment was carried out to quantify and compare the physical damage (measured as scale loss), recovery and survival of two size categories [small: 48–85 mm total length (TL); large: 78–148 mm TL] of 0-group mulloway, Argyrosomus japonicus, after simulated escape through square-shaped mesh (bar length of 21.5 mm). Regardless of their size, fish that were fatigued to exhaustion and forced through square meshes sustained significantly more (i.e. 〉1.8 times) scale loss than did control fish that were only fatigued. However, the total scale loss incurred was 〈5% and significantly improved 7 days after treatment. Survival rates over a 2-week observation period were 100 and 〉97% for treatment and control fish, respectively. The results support the utility of square mesh for reducing the prawn-trawl fishing mortality of unwanted bycatch.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0426.2004.00598.x
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  • 20
    Electronic Resource
    Electronic Resource
    Trichodina murmanica (Ciliophora) and Gyrodactylus pleuronecti (Monogenea) parasitizing hatchery-reared winter flounder, Pseudopleuronectes americanus (Walbaum): effects on host growth and assessment of parasite interaction (2002)
    Oxford UK : Blackwell Science Ltd.
    Journal of fish diseases 25 (2002), S. 0 
    Details
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Winter flounder, Pseudopleuronectes americanus, caught in Passamaquoddy Bay, New Brunswick, Canada, and held captive under crowded conditions, developed mixed infections of Trichodina murmanica Polyanski, 1955 (Ciliophora) and Gyrodactylus pleuronecti Cone, 1981 (Monogenea). A protocol involving sequential sieving was used to separate the two species of parasites and produce viable experimental baths. Replicate groups of juvenile, hatchery-reared flounder received one of the following treatments: mixed bath of G. pleuronecti and T. murmanica, bath of G. pleuronecti, bath of T. murmanica or parasite-free (controls). The abundance of both parasites correlated negatively with condition factor of the flounder (r=−0.354, P 〈 0.001 for Trichodina; r=–0.205, P 〈 0.05 for Gyrodactylus). During the periods of peak parasite abundance (1–2 weeks postinfection), the effect of the two parasite species was additive, as mean condition factor and the percentage change in weight were significantly lower (ANOVA, P 〈 0.05) among fish with mixed infections compared to single infections or controls. The most common signs of tissue pathology were increased density of epidermal mucous cells on the fins and macrovesicular lipidosis of the hepatocytes. After a significant decline in parasite infrapopulations (3 weeks postinfection), infected fish resumed normal growth, indicating the observed effects were somewhat reversible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2761.2002.00341.x
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