Age-related trends in red spruce foliar plasticity in relation to declining productivity

Phenotypic plasticity in needle morphology with increasing tree size and age was investigated by comparing four age classes of red spruce (Picea rubens Sarg.) ranging from juvenile (3-12 years old) to mature (over 100 years old). With increase in tree age there were significant increases in leaf mass per unit area (LMA), mesophyll and vascular bundle area as a percentage of total needle cross-sectional area, and stomatal density. Within the vascular bundle, both xylem cross-sectional area and tracheid lumen area increased significantly, whereas air space as a percentage of total cross-sectional area decreased. These morphological changes were associated with a significant decrease in photosynthetic capacity and stomatal conductance, and an increase in (13)C enrichment. Although both photosynthetic capacity and whole-tree conductance decreased significantly between age classes 3 and 12 years, they did not differ between age classes 53 and 127 years, even though needle (13)C enrichment was significantly greater in the 127-year age class. Thus there appear to be compensatory mechanisms that maintain photosynthetic capacity as trees increase in size and vascular complexity, which in red spruce and other species, may affect leaf hydraulic conductance. Although increased LMA may contribute to reduced photosynthetic capacity in red spruce, similar relationships are not seen in other conifers.     

饲料对动物胃肠道完整性的影响

所有活动物均需定期采食饲料,饲料是一种复杂的物质,含有成千上万种不同分子及多种相关微生物。因此,饲料与其摄食者之间有明显互作,从而影响基于营养的动物健康（NbH）。饲料与动物的互作至少表现在3方面：维持胃肠完整性、支持免疫系统、调控氧化应激和疾病。     

采食量与动物健康评价

适当摄取营养素和营养调节剂对动物基于健康的营养策略（NbH）有重要作用。从生产和科学的角度来说,人们期望在与采食相关的产品生产周期内,用常规方法评价和监控动物健康,以验证该策略（NbH）是否恰当。现实中采食量系通过常规法测定,而对动物健康的测定和评价比较复杂,且尚未见实用的常规评价程序。     

Evaluation and comparison of the health status of Atlantic bottlenose dolphins from the Indian River Lagoon, Florida, and Charleston, South Carolina

OBJECTIVE: To conduct health assessments and compare outcomes in 2 populations of Atlantic bottlenose dolphins. Design-Repeated cross-sectional study. ANIMALS: 171 Atlantic bottlenose dolphins. PROCEDURES: During June and August of 2003 through 2005, 89 dolphins from the Indian River Lagoon (IRL), Florida, and 82 dolphins from estuarine waters near Charleston, SC, were evaluated. A panel of 5 marine mammal veterinarians classified dolphins as clinically normal, possibly diseased, or definitely diseased on the basis of results of physical and ultrasonographic examinations, hematologic and serum biochemical analyses, and cytologic and microbiologic evaluations of gastric contents and swab specimens. RESULTS: Prevalence of dolphins classified as definitely diseased did not differ significantly between the IRL (32%) and Charleston (20%) sites. Proportions of dolphins classified as possibly diseased also did not differ. Lobomycosis was diagnosed in 9 dolphins from the IRL but in none of the dolphins from Charleston. Proportions of dolphins with orogenital papillomas did not differ significantly between the IRL (12%) and Charleston (7%) sites. From 2003 through 2005, the proportion classified as definitely diseased tripled among dolphins from the Charleston site but did not increase significantly among dolphins from the IRL. Dolphins from the Charleston site were more likely to have leukocytosis, lymphocytosis, and low serum concentrations of total protein and total J-globulins than were dolphins from the IRL. CONCLUSIONS AND CLINICAL RELEVANCE: High prevalences of diseased dolphins were identified at both sites; however, the host or environmental factors that contributed to the various abnormalities detected are unknown.     

Late‐season photosynthetic rate and senescence were associated with grain yield in winter wheat of diverse origins

There is a lack of studies that have investigated grain yield, its components and photosynthesis in late stages of wheat growth, giving us insufficient understanding of how these factors interact to contribute to yield during this period. As a result, three field experiments were carried out examining 20 winter wheat genotypes of diverse origins under irrigated, terminal drought and dryland conditions in the southern Idaho. Our objective was to evaluate the interaction between post‐anthesis physiological traits, especially leaf‐level photosynthetic capacity, senescence and yield components on grain yield in different moisture regimes. Genotype differences were found in leaf‐level photosynthesis and senescence, canopy temperature depression, grain yield and yield components in each water regime. Grain yield was closely associated with traits related to grain numbers. In all three moisture regimes, positive correlations were observed between grain yield and photosynthesis that were dependent on the timing or physiological growth stage of the photosynthetic measurement: highly significant correlations were found in the mid‐ and late grain filling stages, but no correlations at anthesis. Consistent with these findings, flag leaf senescence at the late grain filling stage was negatively correlated with grain yield and photosynthetic rate (under terminal drought and dryland conditions). These findings provided evidence that grain yield was sink‐limited until the final stages of growth, at which time sustained photosynthesis and delayed senescence were critical in filling grain. Because the trends were consistent in moisture sufficient and deficient conditions, the results suggest that late‐season photosynthesis and delayed leaf senescence are driven by the size of the reproductive carbon sink, which was largely governed by factors affecting grain numbers.     

Introgressive hybridization between native and non‐local steelhead (Oncorhynchus mykiss) of hatchery origin

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Sap flow measurements reveal influence of temperature and stand structure on water use of Eucalyptus regnans forests

We examined water use by maturing Eucalyptus regnans, growing with or without an mid-storey stratum of Acacia spp. (Acacia dealbata or A. melanoxylon), for >180 consecutive days. Study sites were located in the Upper Yarra catchment area in south-eastern Australia. Depending on their contribution to stand basal area, mid-storey Acacia spp. increased total stand water use by up to 30%. Monthly water use in such stands reached more than 640,000 L ha⁻¹ (compared to 545,000 L ha⁻¹ in stands where acacias were absent) in early spring. Water use was curvilinearly related to sapwood area of Acacia spp. and logistically related to sapwood area of E. regnans. Water use of all three species showed a strong relation to daily maximum air temperatures. Distinct and simple relationships provide clear guides to the likely impacts of climate change and forest management on water yield. We compared a traditional up-scaling approach, from individual tree water use to stand water use, to a new approach that incorporates variation in temperature. Development of this approach can lead to greater precision of stand water use estimates – and in turn catchment water yield – under current climate change scenarios, which predict a rise in air temperatures of 0.6–2.5 °C by 2050 for the study area. Our temperature-dependent approach suggests that under conditions of non-limiting water availability, stand water use will rise by 2% for every 0.25 °C increase in maximum air temperatures during winter, and possibly more than that during summer.     

Changes in consumption of sugars by English adolescents over 20 years

OBJECTIVE: Dietary surveys of 11- to 12-year-old Northumbrian children in 1980 and 1990 revealed that consumption of non-milk extrinsic sugars (NMES) was 16-17% of energy intake. This study reports dietary sugars consumption in 2000 and compares it with data collected in 1980 and 1990, using identical methods. DESIGN: A repeat cross-sectional dietary survey of children aged 1-12 years attending the same schools as in the 1980 and 1990 surveys. SETTING: Seven middle schools in south Northumberland. SUBJECTS: All children aged 11-12 years old attending the seven schools. METHOD: Food consumption was recorded using two 3-day diet diaries. Food composition tables were used to calculate energy and nutrient intakes. NMES, and milk and intrinsic sugars were calculated using previously described methods. RESULTS: The numbers of children completing the surveys in 1980, 1990 and 2000 were 405, 379 and 424, respectively; approximately 60-70% of eligible children. Total sugars provided 22% of energy consistently over the three surveys. NMES consumption in 2000 provided 16% of energy compared with 16% in 1980 and 17% in 1990. Sources of NMES changed over the three surveys. NMES from soft drinks doubled from 15 to 31 g day(-1), and from breakfast cereals increased from 2 to 7 g day(-1) over the 20 years. Confectionery and soft drinks provided 61% of NMES. Over 20 years, the proportion of energy from fat decreased by 5% and from starch increased by 4%, creating a welcome tilt in the fat-starch see-saw, without an adverse effect on sugars intake. CONCLUSIONS: Consumption of NMES in 2000 was substantially higher than recommended, and there has been little change over 20 years. Continued and coordinated efforts are required at a national, community and individual level to reduce the intake of NMES.     

Radiation therapy for incompletely excised grade II canine mast cell tumors

Forty-five dogs with incompletely excised grade II mast cell tumors were treated with radiation using a cobalt 60 teletherapy unit (15 fractions of 3.2 Gy for a total of 48 Gy). Twenty-four of the dogs underwent prophylactic regional lymph node irradiation. Three (6.7%) dogs had tumor recurrence, two (4.4%) dogs developed metastasis, and 14 (31%) dogs developed a second cutaneous mast cell tumor. No difference in overall survival rate was observed between the dogs receiving and not receiving prophylactic irradiation of the regional lymph node.