bluuebunny/crossref_metadata_2025 huggingface dataset:
Fascicle nutrient and biomass responses of young loblolly pine to control of woody and herbaceous competitors
Authors: Zutter B R , Miller J H , Allen H L , Zedaker S M , Edwards M B , Newbold R A
Published: April 2011

Individual fascicle mass and foliar nutrient content and concentration of young loblolly pine (Pinus taeda L.) were evaluated on 13 locations of a regionwide competition study in the southeastern United States. The study included a factorial combination of two levels of herbaceous weed control treatment (none, treated) and two levels of woody treatment (none, treated) following site preparation. At pine age 2 years, herbaceous treatment (HT) and woody treatment (WT) had a positive effect on individual fascicle biomass and content of N, P, and K at nearly all and at least half of the locations, respectively. In general, these effects mirrored responses noted for seedling diameter and height. N concentration increased and P concentration decreased at about half of the locations, while Ca and Mg concentrations decreased on nearly all locations with HT. By age 6 years, effects of HT and WT on fascicle mass and nutrient concentrations and contents became neutral or more neutral across the locations. This is attributed in part to the greater nutrient demand of larger crop pines and associated competition components. A notable exception from neutral effects at age 6, typically occurring on sites with high levels of woody vegetation, was the positive response in K concentration or content and negative response in Ca and Mg concentrations with WT.
Patterns and controls of ecosystem function in longleaf pine - wiregrass savannas. II. Nitrogen dynamics
Authors: Wilson Carlos A , Mitchell Robert J , Hendricks Joseph J , Boring Lindsay R
Published: April 2011

The productivity of many temperate forests is nitrogen limited. Controls on N availability are particularly important in fire-maintained ecosystems such as longleaf pine - wiregrass (Pinus palustris Mill. - Aristida stricta Michx.) forests of the Coastal Plain of the southeastern United States, where periodic burning can result in substantial N losses. This study quantifies variation in net N mineralization across a complex ecological gradient for longleaf pine - wiregrass forests, from dry sandhills to wet-mesic sites adjacent to wetlands, for the first year after burning. Net N mineralization was consistently higher for the xeric site and declined as soil moisture status increased. Higher N availability was primarily due to higher rates of net nitrification in these plots, suggesting possible substrate-induced influences. Temperature was positively related to net N mineralization, while percent soil moisture was inversely correlated to net N mineralization. The greater N availability on dry sites may reflect greater quality organic matter inputs resulting from a significant hardwood (Quercus laevis Walt. predominately) component, and (or) it may reflect microclimate differences (warmer soil) that accelerate decomposition of detritus in soil.
Plant community responses to mechanical site preparation in northern interior British Columbia
Authors: Haeussler Sybille , Bedford Lorne , Boateng Jacob O , MacKinnon Andy
Published: April 2011

Ten-year response of plant communities to disk trenching, plowing, rotoclearing and windrow burning was studied on two contrasting sites to address concerns that mechanical site preparation reduces structural and species diversity. Cover and height of all species on randomly located subplots within 0.05- to 0.075-ha treatment plots were used to develop indices of volume, structural diversity, and species diversity; to ordinate the plots; and to correlate species diversity with crop-tree performance. At both sites, community response was strongly influenced by the severity of site preparation. On a boreal site dominated by willow (Salix L. spp.), green alder (Alnus crispa (Ait.) Pursh ssp. crispa) and trembling aspen (Populus tremuloides Michx.), site preparation increased structural diversity and had little effect on species diversity. High-severity treatments increased non-native species abundance 10- to 16-fold while only marginally enhancing growth of planted white spruce (Picea glauca (Moench) Voss) over medium-severity treatments. On a nutrient-poor sub-boreal site, species diversity declined with increasing treatment severity and with increasing lodgepole pine (Pinus contorta var. latifolia Engelm.) stem volume. Velvet-leaved blueberry (Vaccinium myrtilloides Michx.) was highly sensitive to mechanical disturbance. Moderate mechanical treatments appear to improve conifer performance while causing little change to plant communities, but high severity treatments can cause substantial change.
Genetic diversity and population structure of Korean alder (Alnus japonica; Betulaceae)
Authors: Huh Man Kyu
Published: April 2011

The genetic diversity and population genetic structure of Alnus japonica (Thunb.) Steudel in Korea were studied and compared with those of alder from Canada. Nineteen of the 25 loci studied (76.0%) showed detectable polymorphism. The mean genetic diversity within populations was 0.207, which was higher than that for two Canadian alder species (Alnus rugosa (Du Roi) Spreng. and Alnus crispa (Ait.) Pursh). Analysis of fixation indices, calculated for all polymorphic loci in each population, showed a substantial deficiency of heterozygotes relative to Hardy-Weinberg expectations. The mean population differentiation value of A. japonica in Korea (GST = 0.095) is similar to those of A. rugosa in Canada (GST = 0.052). These low values of GST in two countries, reflecting little spatial genetic differentiation, may indicate extensive gene flow (via pollen and (or) seeds) and (or) recent colonization.
Effects of weed control, fertilization, and soil cultivation on the growth of Pinus radiata at midrotation in Canterbury, New Zealand
Authors: Mason E G , Milne P G
Published: April 2011

Two factorial experiments examining effects of weed control, fertilization, and soil cultivation on Pinus radiata D. Don growth were established in the Canterbury region of New Zealand during 1983. The experiments were measured every year for the first 5 years, during which effects of both weed control and fertilization were detected. Midrotation measurements of height and diameter at breast height were taken. Growth in subplot mean height and basal area per unit area over 3 years in one case and 4 years in the other, up to ages 13 and 14, respectively, was analysed. Results showed that the initial time gain due to weed control and fertilization was preserved at midrotation and that there was no continuing divergence between treated and untreated subplots after weed control. There was, however, continuing divergence after fertilization on one site where topsoil had been shifted into heaps during land clearing. Modelling revealed that effects of weed control and fertilization on basal area growth and yield of stands could be represented by the same difference equation with an additive term to represent the effects of treatments. On the other hand an existing regional growth and yield model failed to represent these effects properly.
Improved efficiency of uidA gene transfer in stone pine (Pinus pinea) cotyledons using a modified binary vector
Authors: Humara Jaime M , Marín M Soledad , Parra Francisco , Ordás Ricardo J
Published: April 2011

This paper describes the construction of a binary vector with the uidA-int gene under the control of the promoter and first intron from the maize (Zea mays L.) ubiquitin 1 (Ubi1) gene, aiming at high expression levels of the uidA gene in Pinus pinea L. cotyledons. Transient expression was determined after microparticle bombardment of 1-day-old cotyledons, and data indicated that the new construct performed considerably better than p35SGUSint, which has the uidA-int gene under the control of a CaMV35S promoter. In addition, we have demonstrated that the marker gene uidA from plasmid pBINUbiGUSint is reproducibly transferred from Agrobacterium tumefaciens (E.F. Sm. & Town) Conn, and beta-glucuronidase activity was detected 7 days after inoculation of scraped or sonicated cotyledons. Infection with A. tumefaciens EHA105 pBINUbiGUSint significantly improved results obtained earlier with plasmid p35SGUSint. Further, the application of our protocol reduced the level of the necrotic response that is usually displayed by cotyledons after Agrobacterium infection.
Effects of climate change and nitrogen deposition on the carbon sequestration of a forest ecosystem in the boreal zone
Authors: Mäkipää Raisa , Karjalainen Timo , Pussinen Ari , Kellomäki Seppo
Published: April 2011

Global warming and nitrogen deposition are expected to modify the carbon sequestration of boreal forests, causing feedback to atmospheric CO2 and climate. The objective of this study was to assess the effects of climate change and various N deposition rates on C sequestration of a forest ecosystem. The study uses a gap-type forest model for a managed Scots pine (Pinus sylvestris L.) stand in conditions representing southern Finland. Model computations indicated that, for both current and changed (+4°C and +10% in precipitation) climatic conditions, increased levels of N deposition from 6 to 12 kg·ha-1 per year increased C uptake by 4-6.5%. Total C stock (vegetation, litter, and soil organic matter) was 11% higher for current level of N deposition than without deposition. Changed climate resulted in a 10% higher C stock of the vegetation but 30% lower C stock in the forest soil. Consequently, the total C stock in forests was decreased because of the greater decline in soil C stock. The combined effects of climate change and N deposition decreased the average C stock of forest (over a 100-year rotation period) with annual deposition rates under 12 kg N·ha-1 but slightly increased C stock with deposition of 24 kg N·ha-1.
Assessing the impact of management unit design and adjacency constraints on forestwide spatial conditions and timber revenues
Authors: Borges José G , Hoganson Howard M
Published: April 2011

Spatial considerations in ecosystem management are addressed within the framework of the forest management scheduling adjacency problem. Emphasis is on both the effectiveness of adjacency regulations and the consequences of strategies for management unit design. Four strategies are presented that subdivide stands into maximum-sized harvest units. A dynamic-programming heuristic is used to plan harvest schedules that comply with adjacency constraints over temporal horizons extending up to eight 10-year periods. The impact of stand design and adjacency constraints upon the output of the forest management problem is assessed. Specifically, timber revenues and spatial conditions generated by combining adjacency constraints with alternative strategies are analyzed. Results from test computer runs are discussed for applications in nine scenarios. Results suggest that timber adjacency costs are not overly sensitive to alternative strategies for management unit design that emphasize the generation of specific spatial conditions (e.g., amount of edge and interior space). They further indicate that emphasis on timber production when designing the management units' boundaries substantially reduces adjacency costs. They show that adjacency constraints contribute to maintain spatial heterogeneity and yet may be inadequate for addressing other spatial concerns.
Leaf area prediction models for Tsuga canadensis in Maine
Authors: Kenefic Laura S , Seymour Robert S
Published: April 2011

Tsuga canadensis (L.) Carr. (eastern hemlock) is a common species throughout the Acadian forest. Studies of leaf area and growth efficiency in this forest type have been limited by the lack of equations to predict leaf area of this species. We found that sapwood area was an effective leaf area surrogate in T. canadensis, though adding crown length to the sapwood equations improved model performance. Prediction bias was observed at the upper end of our data for the best sapwood equation. Sapwood area at crown base did not predict leaf area as well as sapwood area at breast height. Equations using crown length or crown volume alone were the least effective of all models tested. Models using stem cross-sectional area inside the bark or tree basal area with a modified live crown ratio produced results comparable with those of the best sapwood-based model and were unbiased across the range of our data. There findings verify the value of nonsapwood-based approaches to T. canadensis leaf area prediction.
Windthrow following four harvest treatments in an Engelmann spruce - subalpine fir forest in southern interior British Columbia, Canada
Authors: Huggard David J , Klenner Walt , Vyse Alan
Published: April 2011

We used transect surveys at a large-scale experimental site at Sicamous Creek, B.C., to measure the effects of five treatments on windthrow: 10-ha clearcuts, arrays of 1-ha patch cuts, arrays of 0.1-ha patch cuts, individual-tree selection cuts, and uncut controls. We also examined edge effects and conditions predisposing trees to windthrow. Windthrow of subalpine fir (Abies lasiocarpa (Hook.) Nutt.) in the 2.7 years following harvesting increased from 0.6% of basal area per year in uncut forest to 0.8-1.8% per year in harvested treatments, with highest rates in individual tree selection units and lowest rates in 0.1-ha patch-cut arrays. Engelmann spruce (Picea engelmannii Parry ex Engelm.) showed similar patterns of windthrow but lower rates (0.2-0.7% of basal area per year in harvested treatments). Windthrow was concentrated near north and east edges of 1-ha and 10-ha openings but was dispersed throughout the more uniform treatments. Windthrown trees did not differ from random trees in diameter but had lower height/diameter ratios, probably reflecting the greater windthrow observed in subxeric sites on complex, elevated topography. The rates and distribution of windthrow in different harvest treatments have implications for ecological processes, salvage, long-term windthrow potential, and mitigation possibilities.
Modeling trends with annual survey data
Authors: Van Deusen Paul C
Published: April 2011

Flexible models are proposed for assessing trend in annual forest survey data with increasing levels of generality. The models can be fit to the data using a mixed estimator and compared using the Akaike or Schwarz information criterion. The models also provide smoothed estimates of annual means.
Heartwood decay resistance by vertical and radial position in Douglas-fir trees from a young stand
Authors: Gartner Barbara L , Morrell Jeffrey J , Freitag Camille M , Spicer Rachel
Published: April 2011

Heartwood durability of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) was studied as a function of vertical and radial position in boles of trees with a wide range of leaf area/sapwood area ratios. Six 34-year-old trees were harvested from each of three plots established 14 years before: very dense, thinned, and thinned and fertilized. Heartwood samples from three radial positions and five heights were incubated with the decay fungus Postia placenta (Fr.) M. Larsen et Lombard. There were no significant differences in wood mass loss (decay resistance) by vertical or radial position. One could expect that trees with high leaf area/sapwood area could have the carbon to produce heartwood that is more resistant to decay than trees with lower leaf area/sapwood area. However, we found no relationship between leaf area above node 20, sapwood area there, or their ratio, and the decay resistance of outer heartwood at that node. These results suggest that, for young Douglas-fir trees, heartwood durability does not vary with position in the bole or with environments that alter the tree's balance of sapwood and leaf area. We suggest that young stands may thus be robust with respect to the effect of silvicultural regimes on heartwood durability.
Height growth and vertical development of an old-growthPseudotsuga-Tsugaforest in southwestern Washington State, U.S.A.
Authors: Ishii Hiroaki , Reynolds Joel H , Ford E David , Shaw David C
Published: April 2011

A detailed analysis of diameter-height relationships was applied to an old-growth Pseudotsuga menziesii (Mirb.) Franco var. menziesii - Tsuga heterophylla (Raf.) Sarg. forest in southwestern Washington State, U.S.A., to predict future development of vertical stratification among tree species. Differences among species in relative abundance and size structure resulted in diameter-height regressions of varying certainty and stability. Damage and shading had negative impacts on predicted heights and estimates of maximum attainable height (Hmax) in all species. However, species varied as to the main causes and size dependency of damage in relation to tree height. Current height-growth rates of the upper canopy species declined with increasing tree height, reaching minimum values near the predicted Hmax. The future development of the forest canopy would involve a slow invasion of the upper canopy by Tsuga heterophylla and Thuja plicata Donn ex D. Don, as P. menziesii are near their maximum attainable height, and Abies amabilis Dougl. ex Forbes and Taxus brevifolia Nutt. are restricted to the middle to lower canopy. However, if current height-growth rates continue, P. menziesii should maintain its dominant status in the upper canopy for at least another century.
Susceptibility of lodgepole pine stands to the mountain pine beetle: testing of a rating system
Authors: Shore T L , Safranyik L , Lemieux J P
Published: April 2011

A system for rating the susceptibility of lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) stands to the mountain pine beetle (Dendroctonus ponderosae Hopkins) was field tested in 38 stands in the Cariboo forest region of British Columbia in a retrospective study. A linear relationship was defined between the percentage of basal area killed by the mountain pine beetle and the susceptibility indices for the sample stands. The system was further tested using an independent data set of 41 stands from across southern British Columbia. Forty of the 41 stands fell within the 95% prediction interval of the original model data for stand susceptibility. This study provides validation for a susceptibility rating model described in 1992. The regression model and associated confidence interval also provide a useful tool for landscape level loss predictions due to the mountain pine beetle.
Spatial simulation of forest succession and timber harvesting using LANDIS
Authors: Gustafson Eric J , Shifley Stephen R , Mladenoff David J , Nimerfro Kevin K , He Hong S
Published: April 2011

The LANDIS model simulates ecological dynamics, including forest succession, disturbance, seed dispersal and establishment, fire and wind disturbance, and their interactions. We describe the addition to LANDIS of capabilities to simulate forest vegetation management, including harvest. Stands (groups of cells) are prioritized for harvest using one of four ranking algorithms that use criteria related to forest management objectives. Cells within a selected stand are harvested according to the species and age cohort removal rules specified in a prescription. These flexible removal rules allow simulation of a wide range of prescriptions such as prescribed burning, thinning, single-tree selection, and clear-cutting. We present a case study of the application of LANDIS to a managed watershed in the Missouri (U.S.A.) Ozark Mountains to illustrate the utility of this approach to simulate succession as a response to forest management and other disturbance. The different cutting practices produced differences in species and size-class composition, average patch sizes (for patches defined by forest type or by size class), and amount of forest edge across the landscape. The capabilities of LANDIS provide a modeling tool to investigate questions of how timber management changes forest composition and spatial pattern, providing insight into ecological response to forest management.
Determinants of tree quality and lumber value in natural uneven-aged southern pine stands
Authors: Prestemon Jeffrey P , Buongiorno Joseph
Published: April 2011

An ordered-probit model was developed to predict tree grade from tree- and stand-level variables, some of which could be changed by management. Applied to uneven-aged mixed loblolly (Pinus taeda L.) - shortleaf pine (Pinus echinata Mill.) stands, the model showed that the grade of pine trees was highly correlated with tree diameter, tree height, and stand basal area, in non-linear fashion. In addition, a tree was more likely to be of high quality if it grew on industry or government forestland, on poorer sites, and in stands that had been partially cut in the past. However, the effects of changes in these variables on the unit value of recovered lumber were small. The exceptions were tree diameter and height, which were the most important indicators of lumber value.
Contributions of coniferous and broad-leaved species to temperate forest carbon uptake: a bottom-up approach
Authors: Catovsky S , Bazzaz F A
Published: April 2011

Changes in forest species composition could influence ecosystem carbon uptake rates. To understand how species differed in their contributions to canopy photosynthesis, we investigated how the dominant coniferous (eastern hemlock, Tsuga canadensis (L.) Carr.) and broad-leaved (northern red oak, Quercus rubra L.; red maple, Acer rubrum L.) species in a central Massachusetts forest differed in canopy carbon uptake rates. We considered what factors influenced in situ leaf-level photosynthesis and then used a bottom-up summation approach to estimate species-specific total canopy carbon uptake rates. Variation in canopy light strongly influenced leaf-level photosynthetic rates: sunlit leaves had significantly higher rates than shaded leaves, and photosynthesis increased with canopy height. Species also differed in leaf-level photosynthetic rates, with the broad-leaved species having up to twofold higher rates than hemlock. Within hemlock, needles older than 2 years had lower photosynthesis than younger needles. Variation in leaf-level photosynthesis scaled up to influence canopy carbon uptake rates. Red oak consistently had the highest canopy photosynthetic rates, while through the season, hemlock's relative contribution to carbon flux increased and that of red maple decreased. Thus, in such mixed forests, future changes in species composition could have substantial impacts on forest carbon dynamics, particularly if red oak is the primary broad-leaved species to expand at the expense of hemlock.
A compatible growth and yield model for the management of mixed tropical rain forest
Authors: Atta-Boateng James , Moser, Jr. John William
Published: April 2011

The lack of appropriate analytical tools to evaluate the impact of forest management policies has hindered the sustainable use of the rain forest. Decisions about the level of forest management and financial investment require accurate predictions of future forest yields. A technique, using hierarchical clustering and canonical discriminant procedures, was developed previously to pool 112 timber species with similar growth increment characteristics into seven groups suitable for the construction of growth and yield models. Compatible growth and yield models were developed for each group by the solution of a system of differential equations expressing the rate of change of ingrowth, mortality, and survival growth components within a forest stand. The solution provides the means to project the status of the timber stand at any future time given some predefined initial stand conditions. The models are useful for inventory updating, allowable annual cut calculations, and management planning for natural or managed stands. They also provide a means to test hypotheses concerning the influence of stand characteristics on increment and to project future product assortments.
Is there too much or too little natural forest in the Atlantic Zone of Costa Rica?
Authors: Bulte Erwin H , Joenje Mark , Jansen Hans GP
Published: April 2011

Deforestation rates in developing countries are often regarded as excessive, despite the lack of a satisfactory economic benchmark to evaluate this claim. This paper provides such a benchmark for a particular region in Costa Rica. The monetary value of the various functions performed by tropical rainforests is estimated and used in a conventional optimal control model to compute the globally optimal natural forest stock in the Atlantic Zone of Costa Rica. The results indicate that the current forest stock is suboptimally large, suggesting that promoting further forest conversion can increase economic welfare. The current stock would be near optimal only when (i) the annual benefits of carbon fixation are extremely high and (ii) the government of Costa Rica would be fully compensated for this positive externality.
Inheritance of resistance to Glomerella cingulata in Populus
Authors: Newcombe George
Published: April 2011

In natural populations of Populus trichocarpa Torr. & A. Gray, large, concentric leaf lesions caused by Glomerella cingulata (Stonem.) Spaulding & Schrenk only appear in late autumn. In contrast, small, dark lesions associated with crinkling of the leaf lamina have been observed on P. trichocarpa × Populus deltoides Bartr. ex Marsh. hybrid F2 individuals in spring. Inoculation with a monoconidial isolate demonstrated that the two lesion types are not caused by distinct pathotypes of G. cingulata; typical lesions formed on P. trichocarpa and on F2 individuals. Segregation in two related P. trichocarpa × P. deltoides pedigrees demonstrated that resistance is inherited from P. deltoides and conferred by one to several genes. The inoculation study with G. cingulata confirmed that resistance is inherited from P. deltoides. The susceptibility of P. trichocarpa was evident in the study environment of low light intensity and daily misting. The ability of G. cingulata to cause latent infection was tested with forced cuttings from which preformed leaves emerged and displayed diagnostic symptoms. The apparent resistance of P. trichocarpa in nature likely involves such latent infection. It is proposed that G. cingulata can become an early season pathogen of those F2 hybrids deficient in both the polygenic resistance of P. trichocarpa and a major gene for resistance from P. deltoides.
Mutual regularity of spring phenology of some boreal tree species: predicting with other species and phenological models
Authors: Linkosalo Tapio
Published: April 2011

Phenological models constructed from observations of one species are often extrapolated to predict the phenology of other species. In this study, time series of the flowering and bud burst of several boreal zone trees were collected. The observation series were regressed against each other in pairs to test mutual variation. In addition, two models of phenology, one based on chilling requirement, and the other assuming ontogenetic development starting from a signal from the light climate were fitted to the phenological time series. The root mean square error of the regression models forecasting one observation series with another was quite constant for all event pairs, and the smaller the closer in time the events took place. It seems that different plant species react to climate variables in a similar manner, thus the use of the same models for different species and phenomena is justified. The light climate triggered model, albeit more simple, gave estimates that were better than those of the regression models between the events, while the average residuals of the estimates from the chilling triggered model were considerably larger. It was concluded that the chilling requirement component was redundant for prediction accuracy in the spring phenology models of boreal trees.
Establishment and growth in seedlings ofFagus sylvaticaandQuercus robur: influence of interference from herbaceous vegetation
Authors: Löf M
Published: April 2011

The interference from natural vegetation on the establishment and growth in Fagus sylvatica L. and Quercus robur L. was studied on an open site starting from bare soil. Four treatments were applied: herbicide, herbicide plus fertilization, mowing, and untreated control. Seedlings of beech and oak were spring planted side-by-side in two subsequent years and monitored through the 1995, 1996, and 1997 growing seasons. Interference had a strong negative influence on the seedling shoot dry mass, leaf area, relative diameter growth, leaf nitrogen concentration, and leaf water potential and conductance. Oak had a shorter period of transplanting shock, a higher relative growth rate during interference from vegetation, and deeper roots than beech. Therefore, oak is more easily established than beech, which initially may need more intense site preparation. Neither fertilization compared with vegetation control only, nor mowing compared with untreated control, influenced seedling growth. Low soil water potential had a strong influence on seedling growth, although the competing vegetation at the same time reduced light, soil temperature, and the soil nitrogen concentration.
Pulmonary and systemic vascular tissue collagen, growth factor, and cytokine gene expression in the rabbit
Authors: Belik Jaques , Karpinka Brad , Hart David A
Published: April 2011

During development, the vascular wall composition of the pulmonary and systemic capacitance vessels and their intravascular pressure changes. Little is known, however, about the factors controlling vascular collagen gene expression in both circulations during growth and development. The purpose of this study was to compare the developmental changes in collagen, major growth factors, and cytokines gene expression, in order to ascertain whether a circulation specific pattern is present in the rabbit. Fetal, neonatal, and adult rabbit extrapulmonary and aortic tissues were obtained and the mRNA levels for collagen I and III, as well as major growth factors and cytokines, were measured by a semi-quantitative RT-PCR technique. Collagen I, but not collagen III, expression was developmentally regulated in pulmonary vascular and aorta tissues. Collagen I expression was greatest during the fetal and neonatal period (P < 0.01) and higher in the aorta as compared with the pulmonary artery at these ages (P < 0.05). Significant developmental changes in growth factor mRNA levels were observed for TGF-beta, IGF-2, and bFGF (P < 0.01). IGF-2 mRNA levels significantly declined in both arteries from neonatal to adult, but bFGF increased only in the pulmonary artery during this transition. With regards to inducible enzymes, COX-2 mRNA levels changed developmentally, whereas iNOS mRNA levels were similar for both vessels at all ages. When comparing the two vessels, COX-2 transcripts were relatively more abundant in the adult pulmonary artery tissue and fetal aorta, with similar levels in the newborn. We conclude that circulation specific developmental regulation of collagen gene expression is present in the rabbit in a pattern that is unrelated to the intravascular pressure.

Key words: developmental changes, vascular, collagen, mRNA expression, growth factors.
Direct effects of varying doses of oestradiol on early embryonic development in in vitro culture of rat's two-cell embryos
Authors: Tong Terry YY , Goh Victor HH , Tain Chee Fei , Mok Helen , Tsang Shirley
Published: April 2011

Hyperstimulation in the rat using pregnant mares' serum gonadotrophin (PMSG) has been known to cause death in pre-implantation embryos, as well as enhancement of oestradiol production. This study examines the effect of oestradiol, in levels that are found in hyperstimulated pregnant rats, on pre-implantation embryonic development. Using a simplified in vitro system, 2-cell embryos retrieved from rats on the 2nd day of pregnancy were cultured in rat two-cell embryo culture medium (R2ECM) containing pharmacological doses of oestradiol for 96 h and scored daily in the morning. Three ng·mL-1 oestradiol reduced the incidence of >8-cell embryos to morulae on the 5th day and blastocysts on the 6th day of development. Most embryos were retarded at the lower cell stages on the 5th day and degenerated by the 6th day. None of the blastocysts expanded on the last day of culture. Fifteen ng·mL-1 oestradiol accelerated embryo development on the 3rd day but retarded development on the 4th day, and increased the incidence of degenerated embryos by the 5th and 6th day of development. These results suggest that the elevated oestradiol may constitute a mechanism by which PMSG induces death in pre-implantation rat embryos, possibly via a direct action on the embryos.Key words: culture, embryonic development, oestradiol, rat.
Reduction of the NO-mediated response in the rat aorta by metalloporphyrins
Authors: Vreman Hendrik J , Haenen Guido R MM , Stevenson David K , Bast Aalt
Published: April 2011

Metalloporphyrins (MPs) have been found to affect the production of carbon monoxide (CO) and nitric oxide (NO). Unlike that for CO, little is known about the mechanism of action of MPs on the NO system. We determined the in vitro ability of ferrous protoporphyrin (heme, FePP), zinc protoporphyrin (ZnPP), and bilirubin (BR) to scavenge NO. Heme and ZnPP were studied in the rat aortic ring system for their ability to affect phenylephrine-induced contraction and methacholine-stimulated relaxation. Heme was found to be a good NO scavenger with a ks= 0.53 ± 0.19 x 104M-1·s-1(n = 6). ZnPP and BR did not scavenge NO. Neither heme nor ZnPP treatment affected the phenylephrine response as measured by -logEC50and the maximal effect. However, heme and ZnPP treatments decreased the -logEC50and the maximal effects of methacholine, therefore decreasing vasorelaxation. We conclude that when ZnPP is administered in vivo blood pressure should be carefully monitored.Key words: carbon monoxide, heme, NO scavenger, vasorelaxation, zinc protoporphyrin.
Canadian recommendations underestimate energy needs of women over fifty years as determined by doubly-labelled water
Authors: Kaczkowski Crystal H , Jones Peter JH , Feng Jian Ying , Bayley Henry S
Published: April 2011

Accurate estimations of energy requirements at the population level are crucial because of disease processes associated with energy imbalance. The present objective was to compare energy expenditure with existing Recommended Nutrient Intakes for Canadians (RNIC) and determine whether the RNIC provides a true index of energy requirement in middle-aged and elderly Canadian women. A second objective was to compare energy expenditure and the RNIC to Food and Agriculture Organization, World Health Organization, United Nations University (FAO/WHO/UNU) predictions. Seventy-six women were recruited for the study (67.3 ± 11.5 y, 63 ± 11.7 kg, BMI 24.8 ± 4.4 kg·m-2). The two-point doubly-labelled water (DLW) method was used over 13 days to assess energy expenditure while subjects carried out their routine activities. Subjects were stratified to enable age specific requirements for middle-aged and elderly women. At weight maintenance, energy needs were underestimated using the RNIC (7.1 ± 1.6 MJ·d-1, 1698 ± 391 kcal·d-1) compared to total energy expenditure (10.0 ± 3.2 MJ·d-1, 2395 ± 746 kcal·d-1) as determined by DLW as a whole and for each age group. The RNIC recommendations were lower than the FAO/WHO/UNU estimations even for light activity. Results indicate that mean energy expenditure was 29% greater than the RNIC recommendations created using formulas based on age and weight, whereas the FAO/WHO/ UNU estimations closely approximated energy expenditure based on heavy activity in women 49-79 y and light activity in women over 80 y old. These data suggest a systematic underestimation of Canadian energy recommendations for women.Key words: energy expenditure, doubly-labelled water, energy intake, dietary assessment, humans.
Changes in the regulation of calcium metabolism and bone calcium content during growth in the absence of endogenous prolactin and during hyperprolactinemia: A longitudinal study in male and female Wistar rats
Authors: Piyabhan Pritsana , Krishnamra Nateetip , Limlomwongse Liangchai
Published: April 2011

Since endogenous prolactin has been shown to enhance food consumption, calcium absorption, and bone calcium turnover in the pregnant rat, the role of endogenous prolactin in the regulation of calcium metabolism was investigated in 3-day balance studies of female Wistar rats from the age of 3 to 11 weeks. The study was divided into two parts. In part I, calcium metabolism in males and females was compared. In part II, 3-week old female rats were divided into 5 groups: (i) control animals receiving 0.9% NaCl; (ii) animals receiving 6 mg bromocriptine/kg/day (- PRLendogroup); (iii) animals receiving 2.5 mg ovine prolactin/kg/day (+PRLexo); (iv) sham-operated animals receiving 0.9% NaCl, and (v) animals with two extra pituitaries implanted under the renal capsule, receiving 0.9% NaCl (AP group). Results showed that rapid growth occurred between 3 and 6 weeks with maximum fractional calcium absorption and calcium retention at 5 weeks of age in both sexes. The data also showed a physiological significance of endogenous prolactin in enhancing calcium absorption and retention in 5 week old rats. In an absence of prolactin, peak calcium absorption was delayed in 7-week old animals, and vertebral calcium content of 11-week old animals was reduced by 18%. Hyperprolactinemia in the AP group was found to enhance fractional calcium absorption and calcium retention at 7, 9, and 11 weeks and increased the femoral calcium content by 16%. It could be concluded that a physiological role of prolactin is the stimulation of calcium absorption and maintainance of bone calcium content during growth and development.Key words: bone calcium content, calcium absorption, calcium balance, hyperprolactinemia, prolactin.
Glucose disposal by insulin, but not IGF-1, is dependent on the hepatic parasympathetic nerves
Authors: Sadri Parissa , Lautt W Wayne
Published: April 2011

Insulin-like growth factor-1 (IGF-1) has many insulin-like activities, including stimulation of glucose uptake in skeletal muscle. However, those with diabetes or chronic liver disease are insulin resistant but show a normal hypoglycemic response to IGF-1. We have previously shown that insulin sensitivity depends on a hepatic parasympathetic reflex release of a hormone from the liver. The hypothesis was tested that insulin action, but not IGF-1 action, is dependent on the hepatic parasympathetic reflex. Glucose disposal in response to three doses of IGF-1 (25, 100, 200 µg/kg) was determined in rats. IGF-1 at 200 µg/kg had similar effect on glucose disposal as did 50 mU/kg of insulin. Interruption of the hepatic parasympathetic reflex either by surgical ablation of the anterior nerve plexus or by atropine (1.0 mg/kg) resulted in insulin, but not IGF-1, resistance. Sixteen hours of fasting resulted in insulin, but not IGF-1, resistance. In conclusion, insulin, but not IGF-1, triggers the hepatic parasympathetic dependent release of a putative hepatic insulin sensitizing substance (HISS) that stimulates glucose uptake in skeletal muscle.Key words: HISS, RIST, atropine, insulin sensitivity, fasting.
In vitro reactivity of ventral aorta to acetylcholine and noradrenaline in yellow freshwater eel (Anguilla anguillaL.) acclimatized to 10.1 MPa hydrostatic pressure
Authors: Guerrero François , Theron Mickael , Sebert Philippe
Published: April 2011

We examined in vitro vascular reactivity of eels previously acclimatized to 10.1 MPa hydrostatic pressure (HP) for 21 days. The isometric tension developed by ventral aortic rings was measured at atmospheric pressure. Dose-response curves for either acetylcholine (ACh) or noradrenaline (NA), as well as contractions evoked by 80 mM K+, were compared with time-matched experiments conducted on rings obtained from control eels. Results showed that neither the optimal tension nor the maximal force of the K+-evoked contraction were significantly modified, suggesting that acclimatization to high HP did not change the vascular smooth muscle contractile machinery. The dose-response curve to ACh was not significantly changed. Conversely, although NA always relaxed aortic rings, the response of acclimatized eels was significantly reduced over the entire range of the agonist concentration tested (10-8to 10-3M), except for the lowest one (10-9M). The maximal amplitude of the NA-induced relaxation was significantly reduced in aortic rings from acclimatized eels as compared with non-acclimatized samples (339.3 ± 86.5 vs. 744.3 ± 72.1 mg·mg-1dry weight, P < 0.005). Our results suggest that acclimatization to high HP could selectively alter the control of vascular tone by catecholamines.Key words: fish, high pressure, vascular smooth muscle, adrenoceptors, cholinergic receptors.
Intervention du monoxyde d'azote, NO, et de ses dérivés oxydés, particulièrement chez les mammifères
Authors: Ducrocq Claire , Servy Claudine , Cudic Mare , Blanchard Béatrice
Published: April 2011

Nitric oxide (NO) is a natural and stable free radical produced in soil and water by the bacteriological reduction of nitrites and nitrates and in animals by the enzyme oxidation of L-arginine. NO is biosynthesised by finely regulated enzymatic systems called NO-synthases and readily diffuses through tissues. It reacts rapidly with hemoproteins and iron-sulphur centers to form nitrosylated compounds. It oxidises more slowly to form nitrogen oxides that nitrosate thiols into thionitrite. NO is transported in these various forms and released spontaneously or through yet unclear mechanisms into most cells; it also regulates oxygen consumption at the mitochondrial respiratory chain level through interaction with cytochrome oxidase. In the cardiovascular system, NO lowers blood pressure by activating a hemoprotein, the guanylate cyclase present in muscle cells; through such interaction it acts also as a neuromediator and neuromodulator in the nervous system. However, many of NO's roles result from rapid coupling to other radicals; for example, it reacts with the superoxide anion (O2) to form oxoperoxinitrate (ONOO, also known as peroxynitrite). This strong oxidant of metallic centers, thiols, and antioxidants is also able to convert tyrosine to 3-nitrotyrosine and to act upon tyrosine residues contained in proteins. The biological aspects of the roles of NO are presented with particular respect to the rapid interactions of NO with hemoproteins' iron and other radicals. Concurrently, NO oxidation enables nitrosation reactions primarily of thiols but ultimately of nucleic bases. The thionitrite function (R-S-NO) thus formed and the dimerisation and nitration of tyrosine residues are protein post-translational modifications that are being investigated in animals.Key words: nitric oxide, peroxynitrite, nitration, nitrosation, nitrosylation. [Translated by the editors.]
Detection of irradiated spices by different physical techniques
Authors: Chabane S , Pouliquen-Sonaglia I , Raffi J
Published: April 2011

We used thermoluminescence, electron spin resonance, and viscosimetric measurements to establish whether or not a spice had been irradiated. Thermoluminescence, using the 1788 EN official protocol with an alternative method for the extraction of mineral impurities, led to proof of irradiation or proof of no treatment. Electron spin resonance led to different spectrum shapes depending on the chemical composition of the spices; ESR could only be used as proof of irradiation up to several weeks after irradiation, and only for some spices. Viscosimetric measurements carried out on spice suspensions led to a presumption of treatment (or of no treatment) and possibly to proof of irradiation.Key words: irradiation, thermoluminescence, electron spin resonance, viscosimetry, spice.
Behavioural consequences of an 8 Gy total body irradiation in mice: Regulation by interleukin-4
Authors: Meeren Anne Van der , Lebaron-Jacobs Laurence
Published: April 2011

The effects of an 8 Gy γ total body irradiation (TBI) on exploration and locomotion activities as well as temperature were studied in C57BL6/J mice. Survival, body weight, and blood cell counts were also assessed in irradiated mice treated with placebo or interleukin (IL)-4. The efficacy of IL-4 treatment on improvement in exploration activity was evaluated. The study was carried out from 3 h to 30 days following exposure. Our results showed a biphasic response to irradiation concerning the exploration activity of mice. Irradiated mice had reduced activity as early as 3 h after exposure, with recovery of activity within 24 h. The exploration activity again decreased 4 days after irradiation and the recovery occurred slowly after day 17. IL-4 ameliorated the exploration status in mice in both phases. The locomotion activity was studied using a telemetry apparatus. A similar pattern to that of the exploration data was observed, with a minimal activity observed between days 13 and 17. A radiation-induced hypothermia was also noticed over the same time period.Key words: irradiation, behaviour, interleukin-4.
Radiation induced peroxidation of polyunsaturated fatty acids: Recent results on formation of hydroperoxides
Authors: Hauville C , Rémita S , Thérond P , Jore D , Gardès-Albert M
Published: April 2011

Aqueous solutions of linoleic acid were irradiated in air with γ-rays of137Cs. High pressure liquid chromatography (HPLC) was been used to separate and measure the production of hydroperoxides. The results obtained after reverse phase chromatography, associated with a microperoxydase for hydroperoxide detection, indicate the presence of two different hydroperoxides. One type of hydroperoxide was the major product obtained when the initial linoleic concentrations were below the critical micellar concentration (2 mM), and the second type was produced when the concentrations were above 2 mM. A further separation carried out on the second hydroperoxide by direct phase HPLC showed that it contains three compounds, mainly HPODE 9 and 13.Key words: linoleic acid, peroxidation, hydroperoxide, direct phase HPLC, reverse phase HPLC.
Fourier-transform infrared spectroscopy: a pharmacotoxicologic tool for in vivo monitoring radical aggression
Authors: Melin Anne-Marie , Perromat Annie , Deleris Gérard
Published: April 2011

Among the physico-chemical methods that can be used to investigate induced peroxidation in living cells, Fourier transform infrared (FT-IR) spectroscopy appears to be a valuable technique as it is non-destructive and sensitive for monitoring changes in the vibrational spectra of samples. We examined microsomal fractions from rat liver and brain by FT-IR to study the effect of radical aggression induced in vivo by carbon tetrachloride (CCl4). The length of the acyl chains was increased as a consequence of peroxidation induced by the xenobiotic. Moreover, an enhanced level of cholesterol esters and an increase in phospholipids were observed in the liver and the brain, respectively. The conformational structure of the membrane proteins was changed in both the liver and the brain. In the polysaccharide region, we observed an important loss in glucidic structures, such as a decrease in liver glycogen and in some brain glycolipids. These alterations are probably due to the interactions between cells and CCl4and the metabolic changes caused by CCl4. Thus, FT-IR spectroscopy appears to be an useful tool and an accurate means for rapidly investigating the in vivo biochemical alterations induced by CCl4in microsomes, and for correlating them with biochemical and physiological data.Key words: brain, carbon tetrachloride, FT-IR, liver, microsomes.