Soil compaction and forest floor removal reduced microbial biomass and enzyme activities in a boreal aspen forest soil

Soil enzymes are linked to microbial functions and nutrient cycling in forest ecosystems and are considered sensitive to soil disturbances. We investigated the effects of severe soil compaction and whole-tree harvesting plus forest floor removal (referred to as FFR below, compared with stem-only harvesting) on available N, microbial biomass C (MBC), microbial biomass N (MBN), and microbial biomass P (MBP), and dehydrogenase, protease, and phosphatase activities in the forest floor and 0–10 cm mineral soil in a boreal aspen (Populus tremuloides Michx.) forest soil near Dawson Creek, British Columbia, Canada. In the forest floor, no soil compaction effects were observed for any of the soil microbial or enzyme activity parameters measured. In the mineral soil, compaction reduced available N, MBP, and acid phosphatase by 53, 47, and 48%, respectively, when forest floor was intact, and protease and alkaline phosphatase activities by 28 and 27%, respectively, regardless of FFR. Forest floor removal reduced available P, MBC, MBN, and protease and alkaline phosphatase activities by 38, 46, 49, 25, and 45%, respectively, regardless of soil compaction, and available N, MBP, and acid phosphatase activity by 52, 50, and 39%, respectively, in the noncompacted soil. Neither soil compaction nor FFR affected dehydrogenase activities. Reductions in microbial biomass and protease and phosphatase activities after compaction and FFR likely led to the reduced N and P availabilities in the soil. Our results indicate that microbial biomass and enzyme activities were sensitive to soil compaction and FFR and that such disturbances had negative consequences for forest soil N and P cycling and fertility.     

Influence of non-cellulose structural carbohydrate composition on plant material decomposition in soil

The C mineralisation pattern during the early stage of decomposition of plant materials is largely determined by their content of different carbohydrates. This study investigated whether detailed plant analysis could provide a better prediction of C mineralisation during decomposition than proximate analysis [neutral detergent solution (NDF)/acid detergent solution (ADF)]. The detailed analysis included sugars, fructans, starch, pectin, cellulose, lignin and organic N. To determine whether differences in decomposition rate were related to differences in hemicellulose composition, the analysis particularly emphasised the concentrations of arabinose and xylose in hemicelluloses. Carbon dioxide evolution was monitored hourly in soil amended with ten different plant materials. Principal component and regression analysis showed that C mineralisation during day 1 was closely related to free sugars, fructans and soluble organic N components (R ² = 0.83). The sum of non-cellulose structural carbohydrates (intermediate NDF/ADF fraction) was not related to C mineralisation between days 1 and 9. In contrast, a model including starch and protein in addition to the non-cellulose structural carbohydrates, with the hemicelluloses replaced by arabinose and xylose, showed a strong relationship with evolved CO₂ (R ² = 0.87). Carbon mineralisation between days 9 and 34 was better explained by xylan, cellulose and lignin (R ² = 0.72) than by lignocellulose in the ADF fraction. Our results indicated that proximate analyses were not sufficient to explain differences in decomposition. To predict C mineralisation from the range of plant materials studied, we propose a minimum set of analyses comprising total N, free sugars, starch, arabinose, xylan, cellulose and lignin.     

Leaching characteristics of homologues of benzalkonium chloride from wood treated with ammoniacal copper quaternary wood preservative

In Japan, ammoniacal copper quaternary wood preservatives type-1 (ACQ-1), which contains copper and benzalkonium chloride as its active ingredients, is among the most widely used wood preservatives in the pressure treatment of wood. Benzalkonium chloride (BAC) in commercial ACQ-1 products mainly comprises C12 and C14 homologues. In the present study, the leaching characteristics of these BAC homologues were investigated using the heartwood and sapwood portions of Japanese cedar, Japanese larch, and Sakhalin fir treated with ACQ-1 and 1% monoethanolamine (MEA) solution containing equimolar amounts of homologues. Distilled water (DW) and artificial seawater (SW) were used as leaching media. Consequently, it was observed that the leaching rate of the C12 homologue tended to be higher than that of the C14 homologue in DW. The leaching of C12 homologues was accelerated by using SW, resulting in a significantly higher leaching rate than the C14 homologue using SW. It was thought that the difference in the hydrophobicities based on alkyl chain lengths resulted in these phenomena. However, when the heartwood portion of Japanese larch was treated with the homologues in MEA, the leaching rate of the C14 homologue was significantly higher than that of the C12 homologue.     

Water absorption of boron-treated and heat-modified wood

Heat treatments change the chemical and physical properties of wood and dimensional stability and hygroscopicity are affected as a result of modifications of wood cell components. This study evaluated the water absorption of wood specimens treated with boron compounds followed by heat treatment. Sugi (Cryptomeria japonica D. Don) sapwood specimens treated with either boric acid (BA) or disodium octoborate tetrahydrate (DOT) solutions were heat-modified at either 180° or 220°C for 2 or 4 h. Carbohydrate composition and water absorption of the specimens were then measured and compared with those of untreated and unheated specimens. Wood carbohydrates were significantly degraded in the specimens after heat treatment. The heat treatment evidently decreased the water absorption and the heat-modified specimens absorbed less water than unheated specimens. The higher the treatment temperature and the longer the treatment time, the lower the amount of absorbed water. The boron-treated and heat-modified specimens, however, showed increased water absorption due to the hygroscopic properties of BA and DOT.     

Effects of different supplements on tetraploid black locust (<Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> L.) silage

Preparation of silage is a common method to preserve green forage. It plays an important role in improving forage utilization,     

<Emphasis Type="Italic">Lupinus albus</Emphasis> Conglutin Gamma Modifies the Gene Expressions of Enzymes Involved in Glucose Hepatic Production <Emphasis Type="Italic">In Vivo</Emphasis>

Lupinus albus seeds contain conglutin gamma (Cγ) protein, which exerts a hypoglycemic effect and positively modifies proteins involved in glucose homeostasis. Cγ could potentially be used to manage patients with impaired glucose metabolism, but there remains a need to evaluate its effects on hepatic glucose production. The present study aimed to analyze G6pc, Fbp1, and Pck1 gene expressions in two experimental animal models of impaired glucose metabolism. We also evaluated hepatic and renal tissue integrity following Cγ treatment. To generate an insulin resistance model, male Wistar rats were provided 30% sucrose solution ad libitum for 20 weeks. To generate a type 2 diabetes model (STZ), five-day-old rats were intraperitoneally injected with streptozotocin (150 mg/kg). Each animal model was randomized into three subgroups that received the following oral treatments daily for one week: 0.9% w/v NaCl (vehicle; IR-Ctrl and STZ-Ctrl); metformin 300 mg/kg (IR-Met and STZ-Met); and Cγ 150 mg/kg (IR-Cγ and STZ-Cγ). Biochemical parameters were assessed pre- and post-treatment using colorimetric or enzymatic methods. We also performed histological analysis of hepatic and renal tissue. G6pc, Fbp1, and Pck1 gene expressions were quantified using real-time PCR. No histological changes were observed in any group. Post-treatment G6pc gene expression was decreased in the IR-Cγ and STZ-Cγ groups. Post-treatment Fbp1 and Pck1 gene expressions were reduced in the IR-Cγ group but increased in STZ-Cγ animals. Overall, these findings suggest that Cγ is involved in reducing hepatic glucose production, mainly through G6pc inhibition in impaired glucose metabolism disorders.     

Some Nutritional Characteristics of Enzymatically Resistant Maltodextrin from Cassava (<Emphasis Type="Italic">Manihot esculenta</Emphasis> Crantz) Starch

Cassava (Manihot esculenta Crantz) native starch was treated with pyroconversion and enzymatic hydrolysis to produce a pyrodextrin and an enzyme-resistant maltodextrin. Some nutritional characteristics were quantified for both compounds. Pyroconversion was done using a 160:1 (p/v) starch:HCl ratio, 90 °C temperature and 3 h reaction time. The resulting pyrodextrin contained 46.21% indigestible starch and 78.86% dietary fiber. Thermostable α-amylase (0.01%) was used to hydrolyze the pyrodextrin at 95 °C for 5 min. The resulting resistant maltodextrin contained 24.45% dextrose equivalents, 56.06% indigestible starch and 86.62% dietary fiber. Compared to the cassava native starch, the pyrodextrin exhibited 56% solubility at room temperature and the resistant maltodextrin 100%. The glycemic index value for the resistant maltodextrin was 59% in healthy persons. Its high indigestible starch and dietary fiber contents, as well as its complete solubility, make the resistant maltodextrin a promising ingredient for raising dietary fiber content in a wide range of foods, especially in drinks, dairy products, creams and soups.     

CRISPR-Cas Technology in Plant Science

CRISPR-Cas technology has raised considerable interest among plant scientists, both in basic science and in plant breeding. Presently, the generation of random mutations at a predetermined site of the genome is well mastered, just like the targeted insertion of transgenes, although both remain restricted to species or genotypes amenable for plant transformation. On the other hand, true genome editing, i.e. the deliberate replacement of one or several nucleotides of the genome in a predetermined fashion, is limited to some rather particular examples that generally concern genes allowing positive selection, for example tolerance to herbicides. Therefore, further technological developments are necessary to fully exploit the potential of genome editing in enlarging the gene pool beyond the natural variability available in a given species. In principle, the technology can be applied to any quality related, agronomical or ecological trait, under the condition of upstream knowledge on the genes to be targeted and the precise modifications necessary to improve alleles. Published proof of concepts concern a wide range of agronomical traits, the most frequent being disease resistance, herbicide tolerance and the biochemical composition of harvested products. The regulatory status of the plants obtained by CRISPR-Cas technology raises numerous questions, in particular with regard to the plants that carry in their genomes the punctual modifications caused by the presence of the Cas9 nuclease but not the nuclease itself. Without clarification by the competent authorities, CRISPR-Cas technology would continue to be a powerful tool in functional genomics, but its potential in plant breeding would remain untapped.