Dominant effects of litter substrate quality on the difference between leaf and root decomposition process above- and belowground

Initial decomposition rates, changes in organic chemical components (acid-insoluble fraction, holocellulose, polyphenols, soluble carbohydrates) and nutrient dynamics (K, Mg, Ca, P, N) were examined for fine roots and leaves of Japanese cypress (Chamaecyparis obtusa). Litterbag experiments designed to evaluate the relative effects of litter type and position of litter supply in the soil were carried out, considering that root and leaf litter typically occupy different locations and have different substrate qualities. Litterbags of roots and leaves were placed at two positions (on the soil surface and in the humus layer), and collected every 3 months over one year. The mass loss rate and N release were slower during root decomposition in the humus layer than during leaf decomposition on the soil surface. These differences between root and leaf decomposition were mainly caused by the litter type, and the effect of the position on decomposition was relatively small. Root litter was less influenced by position related effects, such as differences in humidity, than leaf litter, and this recalcitrant trait to environmental effects may be responsible for the slower mass loss rate and N release in root decomposition. The results of the present study suggest that fine roots are persistent in the soil and serve an important role in N retention in forest ecosystems because of their litter substrate quality.     

Different combinations of protein ingredients in carp diets for reducing phosphorus loading

ABSTRACT: This study was conducted to gather data on the reduction of environmental phosphorus (P) loading through the formulation of carp diets with different combinations of protein ingredients. Five experimental diets were formulated by substituting fishmeal (FM; 10–20%) with alternative protein sources such as meat meal (MM; 5–15%), blood meal (BM; 5–7%), and defatted soybean meal (dSBM; 6–10%). The control diet used was a commercial carp diet selected based on earlier experiments. Each diet was fed to duplicate groups of juvenile carp three times a day, until satiation for 12 weeks. Feed performance was proportional to the increase in dietary FM levels. Phosphorus absorption ranged between 41.6% and 52.0% among the experimental groups and was 42.6% for the control group, but there were no marked differences in nitrogen (N) absorption rates. Phosphorus retention ranged from 31.4% to 35.7% for the test diets, whereas N retention increased proportionally with dietary FM levels and ranged from 34.7% to 41.7%. The P and N retention values of the control diet were 27.6% and 41.2%, respectively. The total P loading (T-P) increased at the higher FM levels (9.1–10.7 kg/t production), whereas lower FM levels produced higher total N loading (T-N, 34.6–43.1 kg/t production), the figures for the control being 13.9 T-P kg/t production and 35.6 T-N kg/t production. These results indicate that the reduction of FM levels to 10–20% by replacing it with MM, BM, and dSBM in carp diets was effective in reducing the loading of P and N.     

Gene dropping analysis of founder contributions in a closed Japanese black cattle population

Gene dropping simulation was applied to Japanese Black cattle population in Hyogo prefecture, to examine the survivals of alleles originated from founder animals. In the analysis, unique alleles were assigned to founders, and the genotypes of all descendants along the actual pedigree were generated through Monte Carlo simulation following Mendelian segregation rules. By replicating this process 10 000 times, the distribution of frequencies of alleles from each founder was estimated. From the distribution, several quantities useful for the management of genetic diversity, such as the probability of allele extinction and the probability of alleles surviving at a critically low frequency were derived. The materials used were 68 781 animals born in 1955–1998 and their pedigree records traced back to the population in 1937 or before. The expected number of alleles retained in the population drastically decreased during the analyzed period, and reached to 57.9 in the population of 1998, which was only 3.3% of the total number of alleles assigned to founders. Detailed analysis of major founders with relatively high genetic contributions to the current population revealed that alleles from most of the major founders are now at high risk of future extinction. These results strongly suggest that for the management of genetic diversity, the genetic contributions of founders are not fully informative, and emphasize the importance of the detection of live animals having founder alleles with high extinction possibilities.     

Effects of silviculture treatments in a hurricane-damaged forest on carbon storage and emissions in central Hokkaido,Japan

Hurricanes cause abrupt carbon reduction in forests, but silviculture treatment can be an effective means of quickly regenerating and restoring hurricane-damaged sites. This study assessed how silviculture treatments affect carbon balance after hurricane damage in central Hokkaido, Japan. We examined carbon storage in trees and underground vegetation as well as carbon emissions from silviculture operations in 25-year-old stands, where scarification and plantation occurred just after hurricane damage. The amount of carbon stored varied according to silviculture treatment. Among three scarification treatments, a scarified depth of 0 cm (understory vegetation removal) led to the largest amount of carbon stored (64.7 t·ha-1 C). Among four plantation treatments, the largest amount of carbon was stored in a Larix hybrid (L. gmelinii var. japonica × L. kaempferi) plantation (80.3 t·ha-1 C). The plantation of Abies sachalinensis was not successful at accumulating carbon (40.5·ha-1 C). The amount of carbon emitted from silviculture operations was 0.05-0.14 t·ha-1 C, and it marginally affected the net carbon balance of the silviculture project. Results indicate that silviculture treatments should beperformed in an appropriate way to effectively recover the ability of carbon sequestration in hurricane-damaged forests.     

Isolation and characterization of microorganisms capable of hydrolysing the herbicide mefenacet

Three strains—Nocardioides sp. MFC-A, Rhodococcus rhodochrous MFC-B, and Stenotrophomonas sp. MFC-C—were newly isolated from rice soil or bark compost as microorganisms capable of cometabolically degrading mefenacet (2-benzothiazol-2-yloxy-N-methyl-acetanilide). Several other species belonging to the genera Nocardioides, Rhodococcus, and Stenotrophomonas were also capable of degrading mefenacet, suggesting that the ability is not specific to these isolates, but common at least in these genera. N-methylaniline and 2-benzothiazoloxy acetic acid were identified as the metabolites by liquid chromatography-mass spectrometry. Besides mefenacet, the isolates could degrade one or more other amide pesticides, such as flutolanil, mepronil, metolachlor, and pretilachlor. These results indicate that the strains Nocardioides sp. MFC-A, Rhodococcus rhodochrous MFC-B, and Stenotrophomonas sp. MFC-C degrade mefenacet via hydrolysis of the amide bond, but their substrate specificities differ.     

Expression and properties of two types of protein kinase C: alternative splicing from a single gene

Two complementary DNA's, encoding the complete sequences of 671 and 673 amino acids for subspecies of rat brain protein kinase C, were expressed in COS 7 cells. The complementary DNA sequence analysis predicted that the two enzymes are derived from different ways of splicing and differ from each other only in the short ranges of their carboxyl-terminal regions. Both enzymes showed typical characteristics of protein kinase C that responded to Ca2+, phospholipid, and diacylglycerol. The enzymes showed practically identical physical and kinetic properties and were indistinguishable from one of the several subspecies of protein kinase C that occurs in rat brain but not in untransfected COS 7 cells. Partial analysis of the genomic structure confirmed that these two subspecies of protein kinase C resulted indeed from alternative splicing of a single gene.