Nanostructural assembly of cellulose,hemicellulose, and lignin in the middle layer of secondary wall of ginkgo tracheid

Physical, chemical, and biological properties of wood depend largely on the properties of cellulose, noncellulosic polysaccharides, and lignin, and their assembly mode in the cell wall. Information on the assembly mode in the main part of the ginkgo tracheid wall (middle layer of secondary wall, S2) was drawn from the combined results obtained by physical and chemical analyses of the mechanically isolated S2 and by observation under scanning electron microscopy. A schematic model was tentatively proposed as a basic assembly mode of cell wall polymers in the softwood tracheid as follows: a bundle of cellulose microfibrils (CMFs) consisting of about 430 cellulose chains is surrounded by bead-like tubular hemicellulose-lignin modules (HLM), which keep the CMF bundles equidistant from each other. The length of one tubular module along the CMF bundle is about 16 ± 2 nm, and the thickness at its side is about 3–4 nm. In S2, hemicelluloses are distributed in a longitudinal direction along the CMF bundle and in tangential and radial directions perpendicular to the CMF bundle so that they are aligned in the lamellae of tangential and radial directions with regard to the cell wall. One HLM contains about 7000 C₆-C₃ units of lignin, and 4000 hexose and 2000 pentose units of hemicellulose.     

In situ remediation of metal(loid)-contaminated lake sediments with alkali-activated blast furnace slag granule amendment: A field experiment

Journal of Soils and Sediments - Adsorbent amendment to contaminated sediments is one in situ remediation method to decrease the bioaccessibility of pollutants from the sediments. In this work,...     

Methods for treating acid groundwater results and evaluation of long-term tests

Acid groundwater can corrode plumbing systems and solubilize metals in the soil or in the plumbing systems. Since the soluble forms of some metals are toxic, concerns regarding the effects of groundwater acidification on human health have been raised. A number of new methods for treating acidified groundwater have been developed and tested during the last decade. In addition conventional filter devices have been tested and evaluated. Seven methods of in situ alkalization, i.e. treatment of the soil around the well with an alkalizer, have been tested for 1–8 years. These methods involve the application of limestone or slaked lime in the recharge area of the well or in/near the well. Target values set for the tests were: pH>6,5 and alkalinity >60 mg/l. Almost all of these methods have led to improvements in water quality, but in some cases target values were not reached. Most of the treatments have resulted in significant reductions in iron and aluminium contents in drinking water. Eight types of more conventional devices for processing acidified well water have been tested for a couple of years. These de-acidification filters are installed indoors or in some cases inside the well. The majority of them performed well, providing acceptable values of pH and alkalinity under normal water flows. However,after periods of more intense water flushing, some of the filters showed a decreased capacity to neutralize the water. Inexpensive types of equipment, e.g. some of the filters placed inside the well, performed just as well as the more expensive types.     

Decreased nitrogen rates and irrigation effect on celery yield and internal quality

The effect of decreased nitrogen rates (90, 60 and 30 kg N/ha) with and without irrigation on celery yield quantity and internal quality were studied in field experiments in 1993 and 1994. The decreased nitrogen rates reduced yields in both years. In the dry and warm conditions of 1994 nitrogen × irrigation interaction was clearly observed; irrigation increased yield more at higher nitrogen rates than at lower nitrogen rates. In the rainy conditions of 1993 irrigation did not effect the yield level.On the other hand, in both years, decreased nitrogen rates increased dry matter, vitamin C and dietary fiber contents, and nitrogen had a minor effect on total sugar content. In 1994 alpha- and beta carotene and thiamin were also analyzed but nitrogen had no effect on them. Irrigation increased dry matter and total sugar contents at the two lowest nitrogen rates in 1994, but decreased vitamin C contents in both years. There was also slight evidence that irrigation might decrease alpha- and beta-carotene and thiamin contents.     

Effect of Hydrolyzing Enzymes on Wheat Bran Cell Wall Integrity and Protein Solubility

Wheat bran contains good quality protein, but given its location inside aleurone cells, this protein has restricted digestibility. The aim of this work was to liberate and solubilize wheat bran proteins via cell wall degradation by using carbohydrate‐hydrolyzing and proteolytic enzymes without causing extensive protein hydrolysis. Bran incubated with water (without added enzymes) for 16 h increased the solubilized organic nitrogen content from 14.0 to 42.8%. Enzymes with solely carbohydrate‐hydrolyzing activity increased the water‐soluble pentosan and reducing sugar contents but did not significantly increase protein solubilization or protein release from the aleurone cells. Enzymes with proteolytic activity significantly increased the solubilization of protein to 58.2% already at 4 h. Significant protein hydrolysis was detected with a high dosage of protease. However, based on light microscopy, the enzymatic treatment mainly modified the proteins in the subaleurone layer, and it was less effective on proteins inside the aleurone cells. With optimized protease treatment (3 h, 35°C, and 550 nkat/g), effective protein solubilization (>48%) without extensive protein hydrolysis (free amino nitrogen content <45 mg/L) was achieved. In conclusion, intensive solubilization of proteins in the subaleurone layer of wheat bran is possible by using exogenous enzymes with proteolytic activities.     

Inactive fluorescently labeled xylanase as a novel probe for microscopic analysis of arabinoxylan containing cereal cell walls

A new technique to visualize cereal cell walls by fluorescence microscopy was developed. The novel staining technique is based on an inactive fluorescently labeled xylanase binding to arabinoxylan (AX), an important polysaccharide in grain cell walls in terms of the technological and physiological functionalities of grain. The xylanase probe could stain AX in the seed coat, nucellar epidermis, aleurone layer, and starchy endosperm, but not the highly substituted AX of the pericarp layer. The advantage of this new staining technique over the existing immunolabeling techniques is that the staining procedure is clearly faster and less laborious, and uses a smaller probe that can easily be produced by marking a well characterized enzyme with a fluorescent label. In the future, the here proposed technology can be used to develop probes having specificity also for cell wall components other than AX and thus to study plant cell walls further through fluorescence microscopy.     

Milk production and composition in Danish Holstein,Danish Red,and Danish Jersey cows supplemented with saturated or unsaturated fat

The aim of the experiment was to study the response in milk production and composition of substituting barley with either saturated or unsaturated fat in mixed rations (MR) for dairy cows. The experiment included 35 Danish Holstein (DH), 39 Danish Red (DR), and 31 Danish Jersey (DJ) cows from parturition until week 30 of lactation. Cows were ad libitum fed one of the three MR based on maize and grass/clover silage, barley, soybean meal, and dried sugar beet pulp. In the saturated ration (SFA), C16 rich fat substituted barley on dry matter (DM) basis; in the unsaturated ration (UFA), ground rape and linseed (0.74:0.26 ratio) substituted barley on DM basis; and in the control ration (CO), no barley was substituted. Concentrations of crude fat (CF) of total ration DM was 3.03% in CO, and in diets supplemented to intended similar fat levels 5.65% (SFA) and 5.81% (UFA), respectively. Statistical analyses were performed within breed and random regression was used to test for differences between treatment responses throughout lactations.     

Toxoplasmosis and border disease in 54 Swedish sheep flocks. Seroprevalence and incidence during one gestation period.

Serum samples from 704 animals from 54 Swedish sheep flocks were analysed by ELISA twice during 1 breeding season for antibodies to Toxoplasma gondii and border disease virus (BDV). An ELISA, originally developed for the detection of antibodies to bovine viral diarrhoea virus (BVDV) in cattle, was assessed on sheep sera and the results were compared with those obtained in a virus neutralization test. The correlation between the 2 assays proved good. Before breeding, 132 (19%) sheep in 42 flocks had antibodies to T. gondii and 7 (1%) sheep in 5 flocks were seropositive to BDV. During the observation period 4 sheep seroconverted to T. gondii and 13 to BDV, giving an incidence rate of 0.7% and 1.9% respectively. No clinical signs due to the infections were observed. In 5 flocks the frequency of barrenness, abortion or stillbirths exceeded 5%, 5% and 8%, respectively, but there was no evidence that this was attributable to the agents studied. The proportion of BDV-positive flocks was significantly higher among flocks that had been in contact with cattle than among those that had not.