Analysis of gas exchange of Merkus pine populations by the optimality approach

We hypothesized that northern and northeastern Thai populations of Merkus pine (Pinus merkusii Jungh. et de Vriese), which differ in the duration of their grass stage and which originate from slightly different climates in terms of water availability, differ in their gas exchange characteristics. We compared CO(2) exchange response to irradiance, diurnal regulation of leaf conductance within a 10-day period and structural properties among the populations. We used a model, which is based on the concept of optimal stomatal regulation, to analyze CO(2) exchange and transpiration rates. The two geographical groups did not differ in CO(2) exchange response to irradiance, diurnal transpiration, or water use. Mean stomatal length was significantly greater in the northeastern population than in the northern populations, but stomatal frequency did not differ among populations. First-year shoot growth and dry matter production, allocation of nitrogen to needles and root:shoot ratios were similar in the two geographical groups. Genotypic variation in the duration of the grass stage was not reflected in variation in gas exchange, indicating that the grass stage is an adaptation to more site-specific conditions. The modeled response of CO(2) exchange rates to irradiance fitted well the rates measured under laboratory conditions. The transpiration model, which utilized maximum leaf conductance and other parameters derived from the CO(2) exchange measurements, also fitted well the transpiration rates measured in a greenhouse under changing environmental conditions.     

Sensitivity of Crops to Increased Ultraviolet Radiation in Northern Growing Conditions

Crops growing at high latitudes are adapted to low intensities of solar ultraviolet B radiation (UV-B). As a result of destruction of stratospheric ozone layer especially at the Polar Regions of the globe, the intensity of UV-B is projected to increase at high latitudes. In order to find out the consequences of increased UV-B on crops, the sensitivity of different varieties of barley, wheat, oats, clover, timothy, meadow fescue, tall fescue and potato was tested in Jokioinen, Finland. The experiment was conducted in the field, under natural light, with a continuous 30 % increase in UV-B. Both increased UV-B and the control with slightly increased UV-A radiation affected the number of lateral shoots in cereals, and the specific leaf area and the content of phenolic substances in grasses. The effects varied according to plant variety and time of growing season. However, no visible damage, nor changes in biomass and yield production were found in any of the crops. Long-term effects on, e.g. genetic stability and germination of crop seed remain to be studied.     

Quality and production trait genetics of farmed European whitefish, Coregonus lavaretus

We present here phenotypic and genetic parameters for the major quality and production traits of farmed European whitefish. A total of 70 families were produced by mating each of 45 sires to an average of 1.6 dams and each of the 52 dams to an average of 1.3 sires. A total of 2,100 individuals were recorded for survival, and 507 individuals for growth and quality-related traits. The 4 major results were as follows: first, all traits exhibited nonzero heritabilities except for fillet gaping and fillet protein%. The heritabilities for the production traits were harvest weight (0.42 ± 0.10), gutted weight (0.40 ± 0.10), fillet weight (0.36 ± 0.09), maturity score (0.27 ± 0.11, on liability scale), survival (0.19 ± 0.05, on liability scale), carcass% (0.14 ± 0.07), and fillet% (0.11 ± 0.06). The heritabilities for the quality traits were condition factor (0.49 ± 0.10), fillet lipid% (0.37 ± 0.10), muscle texture (0.30 ± 0.09), Distell lipid reading (0.26 ± 0.09), fillet lightness (0.16 ± 0.07), fillet gaping (0.04 ± 0.06), and fillet protein% (0.04 ± 0.06). Second, the quality traits that were significantly genetically correlated with each other were all related to lipid deposition. Increasing fillet lipid% (an undesired change in whitefish) was genetically related to desired lighter fillet color [genetic correlation (r(G)) = 0.70 ± 0.22] and to undesired greater condition factor (0.39 ± 0.17). None of the other genetic correlations between condition factor, fillet lipid%, muscle texture, fillet lightness, fillet gaping, and fillet protein% were significant. Third, BW and gutted weight were genetically related to the quality traits that were genetically related to lipid deposition. Increasing harvest weight was genetically related to high fillet lipid% (r(G) = 0.59 ± 0.14), lighter fillet color (0.61 ± 0.25), and to greater condition factor (0.60 ± 0.12). All other genetic correlations of harvest weights with the quality traits were nonsignificant, indicating that rapid growth was not genetically related to gaping and softer flesh. Fourth, none of the genetic correlations of carcass%, fillet%, maturity, and survival with the quality traits were significant, implying weak genetic integration between the traits. Yet, marginally significant genetic correlations were found for fillet lipid% with maturity score (r(G) = -0.46 ± 0.24) and survival (0.36 ± 0.19). These results provide the genetic basis for assessing the potential to improve product quality via selective breeding.     

Indirect estimation of stomach volume of rainbow trout Oncorhynchus mykiss (Walbaum)

The main hypothesis of this study was that if stomach volume is correlated with food intake it can be estimated without laborious and destructive direct measurement. Rainbow trout, Oncorhynchus mykiss (Walbaum), ca. 500–1300 g, were starved for 1, 4, 8 or 16 days at 15°C after which they were fed in excess with dry pellets containing known amounts of X‐ray‐dense markers. Immediately after feeding the fish were killed, X rayed and weighed. Then the stomach was dissected, its contents removed and weighed, and stomach volume was measured. X‐ray plates were developed and feed intake was estimated based on the amount of marker. All measured variables correlated positively with stomach volume. The best fit for linear regression models was obtained for fish starved for 4 days, where stomach content (dry mass) explained 94%, food intake (based on X‐ray measurement) 77% and fish mass 62% of the variation in stomach volume. However, as stomach content measurement can be a lethal, or at least very stressful, event for the fish, the accuracy of food intake measurement (X‐ray) could be increased using multiple regression. In multiple linear regressions, R²‐values varied between 0.79 (16‐day starvation) and 0.91 (1‐day starvation) with food intake and fish mass as explanatory variables for stomach volume. These results indicate that the stomach volume in rainbow trout can be estimated satisfactorily using indirect methods, which are not detrimental to the fish, although feeding history may affect the accuracy of the estimates.     

Feed intake, growth rate and body composition of juvenile Baltic salmon exposed to different constant temperatures

Feed intake, specific growth rate and changes in body composition of age 1+ and 2+ Baltic salmon, Salmo salar L, were studied for fish held under constant temperature conditions. The 1+ fish (60 g) were reared for 6 weeks at 11, 15, 17, 19 or 23 °C and 2+ fish (250 g) were held at 15 °C. Feed intake of 1+ salmon increased from 176 kJ kg-1 day-1 at 11 °C to 275 kJ kg-1 day-1 at 17 °C and decreased to 229 kJ kg-1 day-1 at 23 °C. Specific growth rate increased from 1.18% day-1 at 11 °C to 1.59% day-1 at 15 °C and decreased to 0.56% day-1 at 23 °C. Optimum temperatures for feed intake and growth were estimated at 17.8 °C and 15.6 °C, respectively, and estimated upper thermal limits for feeding and growth were 29.0 °C and 24.1 °C, respectively. Models for feed intake and growth rate in relation to temperature and fish size are presented. The utilization efficiency of ingested energy decreased from 57% at 11 °C to 22% at 23 °C. For all groups of 1+ fish, most (approximately 86%) of the weight gain consisted of water. Lipid deposition accounted for about 52% of the body energy gain irrespective of rearing temperature.     

The effects of soil and air temperature on CO2 exchange and net biomass accumulation in Norway spruce, Scots pine and silver birch seedlings

Soil temperature is proposed to affect the photosynthetic rate and carbon allocation in boreal trees through sink limitation. The aim of this study was to investigate the effect of temperature on CO(2) exchange, biomass partitioning and ectomycorrhizal (ECM) fungi of boreal tree species. We measured carbon allocation, above- and below-ground CO(2) exchange and the species composition of associated ECM fungi in the rhizosphere of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies K.) and silver birch (Betula pendula Roth) seedlings grown in soil maintained at 7-12, 12-15 and 16-22 °C. We found increased root biomass and photosynthetic rate at higher soil temperatures, but simultaneously with photosynthesis rate, higher temperature generally increased soil respiration as well as shoot, and root and rhizosphere respiration. The net CO(2) exchange and seedling biomass did not increase significantly with increasing temperature due to a concomitant increase in carbon assimilation and respiration rates. The 2-month-long growth period in different soil temperatures did not alter the ECM fungi species composition and the below-ground carbon sink strength did not seem to be directly related to ECM biomass and species composition in any of the tree species. Ectomycorrhizal species composition and number of mycorrhiza did not explain the CO(2) exchange results at different temperatures.     

Quantification of alkylresorcinol metabolites in plasma by high-performance liquid chromatography with coulometric electrode array detection

This study presents the optimization and validation of a rapid protocol for quantifying alkyresorcinol (AR) metabolites 3,5-dihydroxybenzoic acid (DHBA) and 3-(3,5-dihydroxyphenyl)-1-propanoic acid (DHPPA) in plasma, using high-performance liquid chromatography (HPLC) coupled with a coulometric electrode array detector. Syringic acid (SyrA) serves as the internal standard. The new method is simple and could be used in large epidemiological studies. The summed AR metabolite concentrations measured in plasma correlate significantly with the summed urinary AR metabolite concentrations (R = 0.613; p < 0.001) and with the summed intact AR (C17:0-C25:0) concentrations in plasma (R = 0.686; p < 0.001). Additional investigation is needed to clarify whether the two plasma AR metabolites are useful as biomarkers of whole-grain intake and helpful in the exploration of the association between whole-grain cereal intake and human diseases.     

Influence of dietary fat level on feed intake, growth and fat deposition in the whitefish Coregonus lavaretus

Whitefish, Coregonus lavaretus, of initial mean weight 260–265 g were fed either a high-fat or a low-fat diet (dietary fat: 27.5% vs. 12.6%) to examine the influence of dietary fat level on feed intake, growth and patterns of fat deposition. The fish were held at 14.5 °C under a 24L:0D photoperiod, and were fed for 4 h each day. The experiment was run for 11 weeks during which feed intake (three times by X-radiography) and growth were monitored. Samples of fish were taken for body composition analysis at the start and end of the experiment. There were only small differences between dietary treatment groups in feed intake and final body weights, but the body composition of the fish was significantly influenced by the fat content of the diet. The whitefish fed the high-fat diet tended to have higher relative fat contents in the viscera [% fat as mean (SD): 29.6 (9.4)% vs. 22.1 (10.0)%] and carcass [% fat: 12.7 (1.9)% vs. 10.5 (1.3)%] than their counterparts fed the low-fat diet. This resulted in a higher whole-body fat concentration [% fat: 14.0 (1.9)% vs. 11.5 (1.5)%] amongst the fish fed the high-fat diet, and these fish had a higher energy gain than the whitefish fed the low-fat diet. The results confirm that it is possible to manipulate the chemical composition of whitefish by changing dietary composition. © Rapid Science Ltd. 1998     

Comparison of Variable-Number Tandem-Repeat Markers typing and IS1245 Restriction Fragment Length Polymorphism fingerprinting of Mycobacterium avium subsp. hominissuis from human and porcine origins

Background

Animal mycobacterioses are regarded as a potential zoonotic risk and cause economical losses world wide. M. avium subsp. hominissuis is a slow-growing subspecies found in mycobacterial infected humans and pigs and therefore rapid and discriminatory typing methods are needed for epidemiological studies. The genetic similarity of M. avium subsp. hominissuis from human and porcine origins using two different typing methods have not been studied earlier. The objective of this study was to compare the IS1245 RFLP pattern and MIRU-VNTR typing to study the genetic relatedness of M. avium strains isolated from slaughter pigs and humans in Finland with regard to public health aspects.

Methods

A novel PCR-based genotyping method, variable number tandem repeat (VNTR) typing of eight mycobacterial interspersed repetitive units (MIRUs), was evaluated for its ability to characterize Finnish Mycobacterium avium subsp. hominissuis strains isolated from pigs (n = 16) and humans (n = 13) and the results were compared with those obtained by the conventional IS1245 RFLP method.

Results

The MIRU-VNTR results showed a discriminatory index (DI) of 0,92 and the IS1245 RFLP resulted in DI 0,98. The combined DI for both methods was 0,98. The MIRU-VNTR test has the advantages of being simple, reproducible, non-subjective, which makes it suitable for large-scale screening of M. avium strains.

Conclusions

Both typing methods demonstrated a high degree of similarity between the strains of human and porcine origin. The parallel application of the methods adds epidemiological value to the comparison of the strains and their origins. The present approach and results support the hypothesis that there is a common source of M. avium subsp. hominissuis infection for pigs and humans or alternatively one species may be the infective source to the other.     

Linking the gaps between conservation research and conservation management of rare dipterocarps: A case study of Shorea lumutensis

To conserve a rare plant, conservation programs must be guided by the biological attributes of the species. What constitutes the most critical biological information for plant conservation has been the issue of discussion for the last 30 years. Most scientists promote an approach that is either ecological or genetic in emphasis. Ecological and genetic processes will often interact synergistically to influence the population viability and to determine the persistence of populations in the long run. Consequently, conservation management of plant species, in addition to ecological information, requires a robust understanding of underlying genetic processes as well as the variation within and between populations. Conservation has a cost and the resources available for conservation programs are always limited. Therefore, conservation management strategies should not only be scientifically justified but also practical in terms of resource availability. Shorea lumutensis is a rare and endemic dipterocarp in Peninsular Malaysia. A comprehensive research activity was initiated to assess the population ecology and population genetics of S. lumutensis to elucidate specific ecological and genetic requirements and subsequently to set conservation strategies and priorities. This paper is apparently the first attempt at applying both the ecological and genetic approaches into conservation management of a rare dipterocarp. In addition, this paper also attempts to link the gaps between conservation research and conservation management in a realistic manner. It is our hope that this study will serve as a model for the study of other rare dipterocarps which should be given priority for conservation.