Characteristics of the temperature coefficient, Q 10, for the respiration of non-photosynthetic organs and soils of forest ecosystems

The temperature coefficient, Q ₁₀ (fractional change in rate with a 10°C increase in temperature) describes the temperature sensitivity of soils, roots, and stems, as well as their possible performance in global warming processes. It is also a necessary parameter for the estimation of total CO₂ efflux from each element. A number of studies have focused on Q ₁₀ values to date; however, their conclusions are not universal and do not always agree. A review of these reported Q ₁₀ values therefore becomes necessary and important for a global understanding of the temperature sensitivity of different forest types and elements. The aims of our present paper are, first, to find the frequency distribution pattern of soils, roots, and stems (branches) and compare their temperature sensitivity; then, to find the Q ₁₀ differences between conifer and deciduous tree species and the effect of methodology on Q ₁₀ values; finally we want to give a perspective on future Q ₁₀-related studies. We found that most Q ₁₀ values of each element were concentrated in a relatively narrow range despite a total data distribution over quite a wide range. For soil respiration, the median Q ₁₀ value was 2.74 and the center of the frequency distribution was between 2.0 and 2.5 with a percentage of 23%. Most of the data (>80%) were within the range from 1.0 to 4.0. The median Q ₁₀ value for root respiration was 2.40 and the center of the frequency distribution was from 2.5 to 3.0 with a percentage of 33%. Most of the results (>80%) ranged from 1.0 to 3.0. For stem respiration, the median Q ₁₀ value was 1.91 and the frequency distribution was concentrated between 1.5 and 2.0. Over 90% of the data ranged from 1.0 to 3.0. Obvious differences in Q ₁₀ value were found between different elements, stem < root < soil including root < soil excluding root. The differences between woody organisms of stems, roots, and soils excluding roots were statistically significant (p<0.05), indicating that heterotrophic respiration from microorganism activity may be more sensitive to global warming. The duration of the period with leaves slightly affects the temperature sensitivity of woody organisms since the Q ₁₀ values for root and stem of coniferous evergreen trees did not differ significantly from deciduous trees (p>0.10). CO₂ analytical methods (soda lime absorption method, IRGA (Infra-read gas analysis), and chromatograph analysis) and root separation methods (excised root and trenched box) slightly affected the Q ₁₀ values of soil and root respiration (p>0.10), but an in vitro measurement of stem respiration yielded a significantly higher Q ₁₀ value than an in vivo method (p<0.05). In general, although the Q ₁₀ values of non-photosynthetic organisms stayed within a relatively conservative range, considerable variation between and within elements were still detectable. Accordingly, attention should be paid to the quantitative estimation of total CO₂ efflux by Q ₁₀-related models. In future studies, the biochemical factors and the environmental and biological factors controlling respiration should be emphasized for precise estimation of total CO₂ efflux. The difficulty is how to clarify the underlying mechanism for fluctuations of Q ₁₀ values for one specific habitat and element (e.g. temperature acclimation or adaptation of Q ₁₀ values) and then allow the Q ₁₀ values to be more conservative for representation of temperature sensitivity in global warming processes. __________ Translated from Acta Phytoecologica Sinica, 2005, 29(4) [译自:植物生态学报, 2005, 29 (4)]     

Glycation and phosphorylation of beta-lactoglobulin by dry-heating: effect on protein structure and some properties

Beta-lactoglobulin (beta-Lg) was glycated with maltopentaose and subsequently phosphorylated by dry-heating in the presence of pyrophosphate to investigate the structural and functional properties of phosphorylated beta-Lg. The circular dichroism spectra showed that the change of the secondary structure in the beta-Lg molecule by glycation and subsequent phosphorylation was small. The differential scanning calorimetry thermograms of beta-Lg showed that the denaturation temperature of the most stable domain was only slightly affected, whereas the retinol-binding activity of beta-Lg was somewhat reduced by glycation and subsequent phosphorylation. These results indicated that the conformational changes of the beta-Lg molecule by glycation and subsequent phosphorylation were mild. The anti-beta-Lg antibody response was somewhat reduced by glycation, but significant changes were not observed by phosphorylation. Although the stability of beta-Lg against heat-induced insolubility was improved by glycation alone, it was further enhanced by phosphorylation. The calcium phosphate solubilizing ability of beta-Lg was enhanced by phosphorylation following glycation.     

Carbon dioxide exchange of larch (Larix gmelinii) cones during development

Larch (Larix gmelinii (Rupr.) Rupr.) cone scales are green, but little is known of their photosynthetic role in cone development or about how they differ in gas exchange characteristics from needle leaves. In contrast to leaf photosynthesis (Pleaf), we found that stomatal regulation of cone photosynthetic rate (Pcone) was marginal because the photosynthetic carbon came from internal recycling of respiratory carbon dioxide (CO2). Photosynthetic recycling of respired CO2 was confirmed by the finding that the intercellular CO2 concentration (Ci) in cone scales was much higher than ambient [CO2]; also, there was a positive correlation between Pcone and Ci, whereas Pleaf was almost constant as Ci varied. Low chlorophyll (Chl) concentration was a limiting factor for Pcone, but not for Pleaf, as indicated by the correlation between Pcone and chlorophyll concentration. Moreover, chlorophyll utilization efficiency (Psat/Chl a+b) for cone scales was lower than that for leaves. In both cones and leaves, nitrogen (N) was positively correlated with photosynthetic capacity (P), but the P/N value was much lower for cones than for leaves. For both organs, the ratio of respiration to N was broadly similar. Although mature cones have no photosynthetic capacity, Pcone of young cones was as high as 5.3 micromol m(-2) s(-1), about 1.26 times the value of Pleaf, and accounted for the refixation of 30-40% of the respiratory CO2 produced by cones, equivalent to the photosynthetic capacity of a bundle of short shoots near each cone. Thus, Pcone may be an important additional source of photosynthate for cones, given the weak assimilating capacity of leaves that are not fully expanded during cone development.     

Seasonal changes of the mineral contents in the rumen of wild Yeso sika deer (Cervus nippon yesoensis)

The rumen contents were collected from 36 wild Yeso sika deer (Cervus nippon yesoensis) captured by deer culling or by hunting in the spring, summer, autumn and winter in Hokkaido, Japan. Botanical classification was conducted, and the contents of mineral (calcium (Ca), phosphorus (P), potassium (K), sodium (Na), iron (Fe), copper (Cu) and zinc (Zn)) were measured. The animals were captured around pastures or fallow field areas in the Kushiro area. The rumen contents consisted of grasses and Sasa sp. leaves regardless of the season. Leaves and bark were ingested in the spring, autumn and winter. The macro‐mineral contents in the rumen showed seasonal changes. In the summer, the Ca, K and P contents were high, and the Na content was low. There were no seasonal changes in the Fe content. The P, Na and Fe contents were higher than the animals' requirements. In a future survey, it is needed to determine the mineral contents of the food ingested by wild Yeso sika deer.     

Temporal dynamic changes in synthesis of chondroitin sulfate isomers in canine articular chondrocyte culture

To investigate temporal dynamic changes in the synthesis of chondroitin 6-sulfate (CS6) and chondroitin 4-sulfate (CS4) in vitro, normal articular cartilage of femoral heads was harvested from three dogs. Chondrocytes were isolated and cultured in alginate microspheres for 21 days. On days 7, 14 and 21, DNA content was quantified by fluorometric assay using Hoechst 33258. On days 14 and 21, proteoglycans were extracted, and the amounts of CS6 and CS4 were quantified after chondroitinase ABC digestion using capillary electrophoresis. The DNA content and amounts of CS6 and CS4 increased during the culture period. The amounts of CS6 and CS4 divided by DNA content revealed that the synthesis of CS6 was more up-regulated than CS4.     

Progressive changes in ophthalmic blood velocities in Beagles with primary open angle glaucoma

Objective To measure changes in the ocular and orbital blood flow velocities by color Doppler imaging (CDI) in beagles with primary open angle glaucoma as the disease progressed from early to advanced stages. Methods CDI measurements were performed periodically on 13 glaucomatous Beagles during the nontreated mild, moderate and advanced stages of POAG over the course of 4 years. CDI was performed with the dogs lightly anesthetized (butorphanol 0.1 mg/kg IV, acepromazine maleate 0.02 mg/kg IV, and atropine sulfate 0.05 mg/kg) while the CD transducer was placed directly on the cornea anesthetized with 0.5% tetracaine hydrochloride. Intraocular pressure (IOP) by pneumatonography or TonoPen XL, heart rate and mean arterial blood pressure were measured at the beginning, middle and end of each study. The ophthalmic vessels examined included: external ophthalmic arteries and veins, long and short posterior ciliary arteries, anterior ciliary arteries and veins, primary retinal arteries, and vortex veins. Recordings of each vessel included peak systolic velocity (PSV), end diastolic velocity (EDV) and time averaged velocity (TAV), and when possible the resistive index (RI) and pulsatility index (PI) were computed. Results CDI abnormalities were present before intraocular pressure exceeded the normal range. As the animals aged, and the glaucoma progressed with higher levels of IOP, significant changes occurred in nearly all vessels, and generally included a major increase in RI (P < 0.001) and an increase in the PI (P < 0.001). Mean arterial blood pressure (105 ± 18 mmHg) and heart rate (118 ± 33/min) remained reasonably constant. The IOP gradually increased as the disease progressed (early and normotensive: 19.4 ± 3.9 mmHg; moderate: 29.7 ± 2 mmHg; and advanced: 44.5 ± 6 mmHg). The ocular veins seemed most influenced early on in the disease. Late in the disease, ocular venous blood flow could not be consistently demonstrated. An increase in the PI of ocular veins occurred in the moderately and severely affected glaucomatous Beagles. As the IOP increased, there were trends of increasing resistive index and pulsatility index in most arteries, and periods of marked decreased velocities of the vortex and external ophthalmic veins in severe cases. Conclusion CDI measurements in Beagles with primary open angle glaucoma during the course of 4 years indicate easily measurable and repeatable progressive blood flow abnormalities before the elevation of IOP and, thereafter, with gradually increased levels of IOP.     

Proliferation of canine intervertebral disk chondrocytes in three-dimensional alginate microsphere culture

Proliferation of chondrocytes from nucleus pulposus (NP) and anulus fibrosus (AF) was confirmed in three-dimensional culture using alginate microspheres. Cells isolated from NP and AF were incorporated in microspheres and cultured for 14 days. Round mononuclear cells of 20-25 microm in diameter proliferated and formed aggregates. At day 14, alcian blue positive matrix surrounded the proliferating cells. The cells had cytoplasmic vacuoles stained positively by toluidine blue. On electron microscopy, the cells contained proteoglycan vacuoles and lipid droplets in the cytoplasm and synthesized collagen fibrils and electron dense granules surrounding the cell. These features of the cells were characteristic for chondrocytes. This culture system should be useful to further investigate metabolic activities of intervertebral disk chondrocytes.     

Trans-endothelial and trans-epithelial transfer of lactoferrin into the brain through BBB and BCSFB in adult rats

The transportation of intravenously administered bovine lactoferrin (bLF) into the cerebrospinal fluid (CSF) was immunohistochemically investigated in adult rats. Administered bLF was detected in the vesicular membranes of endothelial cells in cerebral blood vessels 10 min after the infusion. Numerous immunoreactive small vesicles were also detected at the ependymal cells in the choroid plexus. Moreover, the bLF concentration in the CSF was significantly increased at 1-2 hr after the intravenous infusion of bLF (10 or 30 mg/kg). These findings clearly demonstrate that LF is possibly transported into the brain matter even in adult animals.     

Development of novel clubroot resistant rapeseed lines (Brassica napus L.) effective against Japanese field isolates by marker assisted selection

Clubroot is an important disease infectible to cruciferous plants and a major threat to rapeseed production in Japan. However, no clubroot resistant rapeseed cultivars have been released. We surveyed pathotype variation of six isolates collected from rapeseed fields and found they were classified as pathotype groups 2 and 4 using Japanese F₁ Chinese cabbage cultivars. We produced the resynthesized clubroot resistant Brassica napus harboring two resistant loci, Crr1 and Crr2, by interspecific crossing and developed resistant rapeseed lines for southern and northern regions by marker-assisted selection and backcrossing. We improved the DNA marker for erucic acid content to remove linkage drag between Crr1 and high erucic acid content and successfully selected lines with clubroot resistance and zero erucic acid for northern regions. A novel line, ‘Tohoku No. 106’, suitable for southern regions showed stable resistance against all six isolates and high performance in infested fields. We conclude that Crr1 and Crr2 are important genes for CR rapeseed breeding and marker-assisted selection is effective in improving clubroot resistance.     

Analysis of mitochondrial DNA of an endangered beech species,Fagus hayatae Palibin ex Hayata

Mitochondrial DNA restriction fragment length polymorphisms were used to examine cytoplasmic diversity within a relic-like population of Fagus hayatae, located in northern Taiwan. Fifteen trees were surveyed for three restriction endonucleases (BamHI, EcoRI and HindIII) and five mitochondrial gene probes (atpA, atp6, atp9, coxI and coxII). The analysis failed to reveal any polymorphisms, an observation that suggests cytoplasmic uniformity in the F. hayatae population examined. It is also interesting to note that the chondriome type of our F. hayatae samples is very close to that characteristic of F. crenata populations in the southernmost area of Japan.