Variations in dark respiration and mitochondrial numbers within needles of Pinus radiata grown in ambient or elevated CO2 partial pressure     

Griffin KL  Anderson OR  Tissue DT  Turnbull MH  Whitehead D 《Tree physiology》2004,24(3):347-353

Within-leaf variations in cell size, mitochondrial numbers and dark respiration rates were compared in the most recently expanded tip, the mid-section and base of needles of Pinus radiata D. Don trees grown for 4 years in open-top chambers at ambient (36 Pa) or elevated (65 Pa) carbon dioxide partial pressure (p(CO2)a). Mitochondrial numbers and respiratory activity varied along the length of the needle, with the highest number of mitochondria per unit cytoplasm and the highest rate of respiration per unit leaf area at the base of the needle. Regardless of the location of the cells (tip, middle or basal sections), needles collected from trees grown in elevated p(CO2)a had nearly twice the number of mitochondria per unit cytoplasm as those grown in ambient p(CO2)a. This stimulation of mitochondrial density by growth at elevated p(CO2)a was greater at the tip of the needle (2.7 times more mitochondria than in needles grown in ambient CO2) than at the base of the needle (1.7 times). The mean size of individual mitochondria was unaffected either by growth at elevated p(CO2)a or by position along the needle. Tree growth at elevated p(CO2)a had a variable effect on respiration per unit leaf area, significantly increasing respiration in the tip of the needles (+25%) and decreasing respiration at the mid-section and base of the needles (-14% and -25%, respectively). Although a simple relationship between respiration per unit leaf area and mitochondrial number per unit cytoplasm was found within each CO2 treatment, the variable effect of growth at elevated p(CO2)a on respiration along the length of the needles indicates that a more complex relationship must determine the association between structure and function in these needles.  相似文献   

Stomatal and non-stomatal limitations to photosynthesis in four tree species in a temperate rainforest dominated by Dacrydium cupressinum in New Zealand     

Tissue DT  Griffin KL  Turnbull MH  Whitehead D 《Tree physiology》2005,25(4):447-456

We assessed the relative limitations to photosynthesis imposed by stomatal and non-stomatal processes in Dacrydium cupressinum Lamb. (Podocarpaceae), which is the dominant species in a native, mixed conifer-broad-leaved rainforest in New Zealand. For comparison, we included three co-occurring broad-leaved tree species (Meterosideros umbellata Cav. (Myrtaceae), Weinmannia racemosa L.f. (Cunoniaceae) and Quintinia acutifolia Kirk (Escalloniaceae)) that differ in phylogeny and in leaf morphology from D. cupressinum. We found that low foliage phosphorus content on an area basis (P(a)) limited light-saturated photosynthesis on an area basis (A(sat)) in Q. acutifolia. Depth in the canopy did not generally affect A(sat) or the relative limitations to A(sat) because of stomatal and non-stomatal constraints, despite reductions in the ratio of foliage mass to area, foliar nitrogen on an area basis (N(a)) and P(a) with depth in the canopy. In the canopy-dominant conifer D. cupressinum, A(sat) was low, consistent with low values of the maximum rate of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation (V(cmax)). In comparison, the A(sat) response of the three broad-leaved tree species was quite variable. Although A(sat) was high in the canopy-dominant M. umbellata, it was low in the sub-canopy trees W. racemosa and Q. acutifolia. Relative stomatal limitation to photosynthesis was more pronounced in W. racemosa (40%) than in the other three species (28-33%). Despite differences in degree, non-stomatal limitation to A(sat) predominated in all tree species.  相似文献   

A genetic map of macadamia based on randomly amplified DNA fingerprinting (RAF) markers     

C.P. Peace  V. Vithanage  C.G.N. Turnbull  B.J. Carroll 《Euphytica》2003,134(1):17-26

The first genetic linkage map of macadamia (Macadamia integrifolia and M. tetraphylla) is presented. The map is based on 56 F₁ progeny of cultivars ‘Keauhou’ and ‘A16’. Eighty-four percent of the 382 markers analysed segregated as Mendelian loci. The two-way pseudo-testcross mapping strategy allowed construction of separate parental cultivar maps. Ninety bridging loci enabled merging of these maps to produce a detailed genetic map of macadamia, 1100 cm in length and spanning 70–80% of the genome. The combined map comprised 24 linkage groups with 265 framework markers: 259 markers from randomly amplified DNA fingerprinting (RAF), five random amplified polymorphic DNA (RAPD), and one sequence-tagged microsatellite site (STMS). The RAF marker system unexpectedly revealed 16 codominant markers, one of them a putative microsatellite locus and exhibiting four distinct alleles in the cross. This molecular study is the most comprehensive examination to date of genetic loci of macadamia, and is a major step towards developing marker-assisted selection for this crop. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Effects of leaf age and tree size on stomatal and mesophyll limitations to photosynthesis in mountain beech (Nothofagus solandrii var. cliffortiodes)     

Whitehead D  Barbour MM  Griffin KL  Turnbull MH  Tissue DT 《Tree physiology》2011,31(9):985-996

Mesophyll conductance, g(m), was estimated from measurements of stomatal conductance to carbon dioxide transfer, g(s), photosynthesis, A, and chlorophyll fluorescence for Year 0 (current-year) and Year 1 (1-year-old) fully sunlit leaves from short (2 m tall, 10-year-old) and tall (15 m tall, 120-year-old) Nothofagus solandrii var. cliffortiodes trees growing in adjacent stands. Rates of photosynthesis at saturating irradiance and ambient CO(2) partial pressure, A(satQ), were 25% lower and maximum rates of carboxylation, V(cmax), were 44% lower in Year 1 leaves compared with Year 0 leaves across both tree sizes. Although g(s) and g(m) were not significantly different between Year 0 and Year 1 leaves and g(s) was not significantly different between tree heights, g(m) was significantly (19%) lower for leaves on tall trees compared with leaves on short trees. Overall, V(cmax) was 60% higher when expressed on the basis of CO(2) partial pressure at the chloroplasts, C(c), compared with V(cmax) on the basis of intercellular CO(2) partial pressure, C(i), but this varied with leaf age and tree size. To interpret the relative stomatal and mesophyll limitations to photosynthesis, we used a model of carbon isotopic composition for whole leaves incorporating g(m) effects to generate a surface of 'operating values' of A over the growing season for all leaf classes. Our analysis showed that A was slightly higher for leaves on short compared with tall trees, but lower g(m) apparently reduced actual A substantially compared with A(satQ). Our findings showed that lower rates of photosynthesis in Year 1 leaves compared with Year 0 leaves were attributable more to increased biochemical limitation to photosynthesis in Year 1 leaves than differences in g(m). However, lower A in leaves on tall trees compared with those on short trees could be attributed in part to lower g(m) and higher stomatal, L(s), and mesophyll, L(m), limitations to photosynthesis, consistent with steeper hydraulic gradients in tall trees.  相似文献   

Long-term trends in stream chemistry and biology in North-East Scotland: Evidence for recovery     

C. Soulsby  D. Turnbull  S. J. Langan  R. Owen  D. Hirst 《Water, air, and soil pollution》1995,85(2):689-694

Since 1983 stream chemistry and macroinvertebrate ecology were monitored in ten streams draining the eastern Cairngorms. All streams have exhibited a decline in sulphate concentrations in response to reduced acid deposition; in the more acidic systems this has been reflected by a parallel increase in acid neutralizing capacity (ANC). In some streams this coincides with an increase in the abundance of acid-sensitive mayflies which may provide evidence for biological recovery. In the most chronically acidified systems no increased abundance has been observed despite significant increases in ANC. This suggests that further reductions in deposition and sufficient time for a reversal of soil acidification is required before any biotic recovery occurs.  相似文献   

Chemistry. Getting the farm out of pharma for heparin production     

Turnbull JE 《Science (New York, N.Y.)》2011,334(6055):462-463

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Communication education in veterinary in the United Kingdom and Ireland: the NUVACS project coupled to progressive individual school endeavors     

Gray CA  Blaxter AC  Johnston PA  Latham CE  May S  Phillips CA  Turnbull N  Yamagishi B 《Journal of veterinary medical education》2006,33(1):85-92

This article reports on the coordination of communications skills training in veterinary schools in the United Kingdom and Ireland and describes the progress and status of training that is occurring in six of these schools.  相似文献   

Assessment of the impact of resistant and susceptible canola on Plasmodiophora brassicae inoculum potential     

S. F. Hwang  H. U. Ahmed  Q. Zhou  S. E. Strelkov  B. D. Gossen  G. Peng  G. D. Turnbull 《Plant pathology》2012,61(5):945-952

The impact on clubroot severity of growing susceptible canola or mixtures of resistant and susceptible canola genotypes was examined. Bioassays revealed greater clubroot severity and incidence, and reduced plant height, where 100% of a susceptible cultivar had been grown. A higher proportion of susceptible plants within a resistant canola crop increased root hair and secondary infections. Regression analysis of root hair infection and the amount of Plasmodiophora brassicae DNA (as determined by quantitative PCR) revealed strong linear relationships between the two parameters. The linear relationships between root hair infection and P. brassicae DNA were stronger for the resistant cultivar than for the susceptible cultivar when regression analysis was conducted by cultivar over the sampling dates. In conclusion, the cropping of a resistant cultivar reduced clubroot severity, while the presence of susceptible volunteer canola increased inoculum potential. Quantitative PCR was a reliable tool for the quantification of root hair infection.  相似文献   

A New Year''s Message from our President          下载免费PDF全文

W. Turnbull 《The Canadian veterinary journal. La revue veterinaire canadienne》1962,3(1):1-2

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Genomic comparison of virulent and non‐virulent Streptococcus agalactiae in fish          下载免费PDF全文

C M J Delannoy  R N Zadoks  M Crumlish  D Rodgers  F A Lainson  H W Ferguson  J Turnbull  M C Fontaine 《Journal of fish diseases》2016,39(1):13-29

Streptococcus agalactiae infections in fish are predominantly caused by beta‐haemolytic strains of clonal complex (CC) 7, notably its namesake sequence type (ST) 7, or by non‐haemolytic strains of CC552, including the globally distributed ST260. In contrast, CC23, including its namesake ST23, has been associated with a wide homeothermic and poikilothermic host range, but never with fish. The aim of this study was to determine whether ST23 is virulent in fish and to identify genomic markers of fish adaptation of S. agalactiae. Intraperitoneal challenge of Nile tilapia, Oreochromis niloticus (Linnaeus), showed that ST260 is lethal at doses down to 10² cfu per fish, whereas ST23 does not cause disease at 10⁷ cfu per fish. Comparison of the genome sequence of ST260 and ST23 with those of strains derived from fish, cattle and humans revealed the presence of genomic elements that are unique to subpopulations of S. agalactiae that have the ability to infect fish (CC7 and CC552). These loci occurred in clusters exhibiting typical signatures of mobile genetic elements. PCR‐based screening of a collection of isolates from multiple host species confirmed the association of selected genes with fish‐derived strains. Several fish‐associated genes encode proteins that potentially provide fitness in the aquatic environment.  相似文献