Changes in above- and belowground biomass in early successional tropical secondary forests after shifting cultivation in Sarawak,Malaysia

Uncertainties in the rate of biomass variation with forest ageing in tropical secondary forests, particularly in belowground components, limit the accuracy of carbon pool estimates in tropical regions. We monitored changes in above- and belowground biomass, leaf area index (LAI), and biomass allocation to the leaf component to determine the variation in carbon accumulation rate with forest age after shifting cultivation in Sarawak, Malaysia. Nine plots in a 4-year-old forest and fourteen plots in a 10-year-old forest were monitored for 5 and 7 years, respectively. Forest and plant part biomass were calculated from an allometric equation obtained from the same forest stands. Both above- and belowground biomass increased rapidly during the initial decade after abandonment. In contrast, a much slower rate of biomass accumulation was observed after the initial decade. LAI also increased by approximately double from the 4-year-old to 10-year-old forest, and then gently increased to the 17-year-old forest. We also found that allocation variation in leaf biomass and nitrogen was closely related to the rate of biomass accumulation as a forest aged. During the first decade after abandonment, a high biomass and nitrogen allocation to the leaf component may have allowed for a high rate of biomass accumulation. However, reduction in those allocations to leaf component after the initial decade may have helped to suppress the biomass accumulation rate in older secondary forests. Roots accounted for 14.0–16.1% of total biomass in the 4–17-year-old abandoned secondary forests. We also verified the model predicted values for belowground biomass by Cairns et al. (1997) and Mokany et al. (2006), although both models overestimated the values throughout our data sets by 45–50% in the 10-year-old forest. The low root:shoot ratio in the secondary forests may have caused this overestimation. Therefore, our results suggest that we should modify the models to estimate belowground biomass considering the low root:shoot ratio in tropical secondary forests.     

Unique expression patterns of myosin heavy chain genes in the ductus arteriosus and uterus of rabbits.

In smooth muscle tissue, two smooth muscle myosin heavy chain (MHC) isoforms (SM1, SM2) and two non-muscle MHC isoforms (NMA, NMB) have been identified. The purpose of our study was to clarify whether smooth muscle MHC mRNA expression reflects the physiological and functional state of the muscle. We studied the expression pattern of MHC mRNAs, using the S1-nuclease mapping procedure, in functionally and morphologically changeable organs; the ductus arteriosus (DA) during development (25 and 29 days of gestation, and from 3-day-old neonates) and uteri from virgin, day-10 pregnant (P10) and day-29 pregnant (P29) rabbits. The results demonstrated that SM2 expression was greater in the fetal DA than in the fetal aortic and pulmonary arteries, but that it decreased significantly following closure of DA. In the gravid uterus, SM1 expression was significantly (P<0.05) strong compared to other MHC mRNAs from virgin to P10 rabbits. During pregnancy, NMB expression showed a tendency to increase until P10, and after P10, SM2 expression increased dramatically and NMB expression decreased to give almost a mirror image of the SM2 expression. Smooth muscle type (SM1, SM2) was significantly (P<0.05) strong compared to non-muscle type expression (NMA, NMB) at P29. These data suggest that smooth muscle MHC mRNA, especially SM2 expression reflects the physiological and functional state of the smooth muscle.     

Expression of feline interferon-alpha subtypes in Esherichia coli, and their antiviral activity and animal species specificity

Two kinds of FeIFN-alpha consisting of 166 amino acids (aa) and 171 aa were expressed in Escherichia coli, and the purified proteins were tested for antiviral activity on homologous and heterologous animal cells. Crude FeIFN induced in feline cells revealed antiviral activity on both homologous and heterologous animal cells. In contrast, both types of recombinant FeIFN-alpha revealed antiviral activity only on the feline cells. All of the FeIFN-alpha subtypes showed high activity to vesicular stomatitis virus, and the three species of feline viruses belonging to different families.     

Soil respiration, N2O, and CH4 emissions from an Andisol under conventional-tillage and no-tillage cultivation for 4 years

No-tillage (NT) management is a promising method to sequester soil C and mitigate global warming caused by agricultural activities. Here, we report 4 years of continuous soil respiration rates and weekly nitrous oxide (N₂O) and methane (CH₄) emissions in NT and conventional-tillage (CT) plots in a typical Japanese volcanic soil. Overall, the soil respiration, N₂O emission, and CH₄ uptake decreased significantly in the NT plot. A difference in soil respiration and N₂O emission between the two plots began after the tillage treatment and the incorporation of crop residues and fertilizers, whereas the CH₄ uptake did not vary significantly during the fallow period after the treatments. The N₂O emission was higher from the CT than from the NT plot during the fall. The overall lower CH₄ uptake in the NT than in the CT plot likely resulted from a combination of decreased soil gas diffusivity and higher mineral N content at the soil surface. Higher soil respiration and N₂O emission occurred in the NT plot in the summer of 2003 and were plausibly caused by an increase in the soil moisture content that resulted from lower temperatures during July and August; the higher soil moisture must have accelerated the decomposition of organic matter accumulated in the topsoil. These results indicate that NT management is generally effective for the mitigation of the total GWP by reducing soil respiration and N₂O emission in temperate regions; however, NT management may increase rather than decrease these emissions when fields experience cool summers with frequent rainfall.