Bursaphelenchus fungivorus (Nematoda: Aphelenchida) associated with Orthotomicus erosus (Coleoptera: Scolitydae) in Spain

A survey of the xylophagous insects in the conifer forests, mainly Pinus pinaster woodlands, in Spain was carried out in order to study the phoretic vectors of nematodes of the genus Bursaphelenchus. Fifteen environmental sites were characterized on the bases of altitude, rainfall, temperature and conifer species. Specimens of Orthotomicus erosus (n = 3476) were captured of which 59% carried nematodes under their elytrous, most of them were aphelenchid fungal‐feeding nematodes, but B. fungivorus was found on the beetles from Las Cumbres, Villa Blanca, (Huelva), southern Spain, which represent the first record of O. erosus as vector of a Bursaphelenchus sp. The nematode is characterized by morphometric and biomolecular techniques and distribution and ecology of the insect is discussed.     

The Impact of Hardwood Line-Planting on Tree and Amphibian Diversity in a Secondary Subtropical Wet Forest of Southeast Puerto Rico

The impact on tree and amphibian diversity of line-planting of tropical hardwoods—mahogany (Swietenia macrophylla × S. mahagoni) and mahoe (Hibiscus elatus)—was studied in a secondary subtropical wet forest of Puerto Rico. Common coqui (Eleutherodactylus coqui) and melodious coqui (E. wightmanae) are the most frequent frog species; forest coqui (E. portoricensis) is less abundant. Although relative abundance means were slightly greater in the undisturbed forest and during the wet season, differences were not statistically significant suggesting that line-planting did not significantly affect amphibian diversity. The line-planted areas had a slightly higher, but not statistically significant diversity, richness, and evenness of tree species than the unplanted forest. Multi-response permutation procedure (MRPP) showed statistically significant community composition differences between line-planting and control plot trees (T = ?5.89, A = .86; p < .001). But mean similarity among plots in both the line-planted and control plots was relatively low at less than 50% of shared species, indicating high diversity of vegetation in the overall forest area. Canopy cover by tree species greater than 3 cm in dbh was much higher in the undisturbed forest but this difference may be reduced as the young line-planted hardwoods mature. Forest enrichment through line-planting of valuable timber species in secondary subtropical wet forest does not significantly affect tree diversity.     

Peroxidase-mediated oxidative cross-linking and its potential to modify mechanical properties in water-soluble polysaccharide extracts and cereal grain residues

Analysis of wheat bran and spent grain shows that concentrations of ferulate and diferulates offer considerable scope to modify the cross-linking of feruloylated polysaccharides and hence the mechanical properties of these residues. In solution ferulic acid (FA) can be readily polymerized by horseradish peroxidase, but when esterified to a polysaccharide, the profile of diferulates becomes restricted. This situation also exists in muro and suggests structural constraints may limit the availability of FA for cross-linking. At relatively low polysaccharide concentration, (approximately 3%), steric restrictions were apparent in gels prepared using isolated polysaccharides. Mechanical properties such as swelling also appear to be fixed at these relatively low polysaccharide concentrations. This limits the potential to modify mechanical properties in muro through oxidoreductase activity. To modify mechanical properties such treatments will need to focus on increasing the "flexibility" of the cell wall matrix and the accessibility of enzymes to the cell wall matrix.     

Enzymatic and chemical treatment limits on the controlled solubilization of brewers' spent grain

The enzymatic hydrolysis of brewers' spent grain (BSG) has been investigated through treatment with commercial carbohydrases and proteases. Resultant residues were then chemically fractionated and delignified. Enzymatic treatments released 25-30% of the BSG mass and yielded precursors suitable for subsequent conversion to potentially value-added products. Controlled chemical fractionation selectively solubilized arabinoxylan but with no differences apparent due to prior enzyme treatment. The loss of non-polysaccharide components during alkali treatment suggests the presence of a high proportion of alkali-soluble lignin. Further delignification of the alkali-insoluble residues and further chemical fractionation released the remaining hemicellulose, to yield a residue which was >90% cellulose. Further knowledge of the properties and interaction between BSG polymers will facilitate an improved enzyme-assisted total deconstruction of BSG and hence the exploitation of its biomass.     

Carbohydrate composition in relation to structural stability, compactibility and plasticity of two soils in a long-term experiment

The effects of tillage on soil organic carbon content, carbohydrate content, monosaccharide composition, aggregate stability, compactibility and plasticity were investigated in a field experiment on a gleysol and on a cambisol under winter barley in South-East Scotland. Two long-term treatments (direct drilling and conventional mouldboard ploughing for 22 years) were compared with short-term direct drilling and broadcast sowing plus rotavation for 5 years. Carbohydrate released sequentially to cold water, hot water, 1.0 M HCl and 0.5 M NaOH was determined after hydrolysis as reducing sugar equivalent to glucose in both fresh and air-dried samples. All other measurements were made on dry soils only. About 3% of the soluble carbohydrate was extracted by cold water, 10% by hot water, 12% by HCl and 75% by NaOH from both the dry and fresh soils. The total reducing sugars of the fractions were proportional to the total organic carbon determined by dichromate oxidation or C analysis. Organic carbon and carbohydrates were concentrated near the surface of the direct drilled soil, but were more uniformly distributed with depth in the ploughed soil. The surface soil under direct drilling was more stable, less compactible and had greater plasticity limits than under ploughing. However, particle size distributions were unaffected by tillage so that differences in soil properties were attributed to differences in the quantity and quality of organic matter. Differences in compactibility, structural stability and plasticity limits between depths and tillage treatments correlated with total carbon and with total carbohydrates. The hot water extractable carbohydrate fraction correlated best with aggregate stability and the NaOH fraction correlated best with compactibility and plastic limit. Both fractions were greatest in the long-term direct drilled soil. The hot water fraction had a galactose plus mannose over arabinose plus xylose ratio of 1.0–1.6 in comparison to 0.4–0.7 in the NaOH fraction indicating that the microbial contribution within the hot water-soluble fraction was the greater. The hot-water fraction was likely to contain more exocellular microbial polysaccharides involved in the stabilizing of soil aggregates. The hot-water and NaOH carbohydrate fractions may be good indicators of soil organic matter quality relevant to the preservation of good soil physical conditions.     

Ultrastructural demonstration of mitochondrial calcium overload in myocardial cells from broiler chickens with ascites and induced hypoxia

Two groups of young broiler chickens, namely, naturally occurring field cases of ascites and those with an induced hypoxia, were used in an ultrastructural study to examine the localisation and distribution of intracellular Ca²⁺ in cardiomyocytes. Age-matched healthy flockmates were used to control each group. Deposits of Ca²⁺ were located extensively in the mitochondria, sarcoplasmic reticulum and Golgi apparatus and sometimes in the myocyte and endothelial cell nuclei of both groups of birds. The results suggest that the cells from the hearts of the ascitic broilers may have been exposed to hypoxia since a large proportion of control material showed no Ca²⁺ activity in either mitochondria or nuclei. The presence of a Ca²⁺ overload in the mitochondria of cardiomyocytes from ascitic birds reared at low altitude or sea level suggests that these broilers were suffering from the deleterious effects of chronic hypoxia due to poor or reduced oxygen use.     

Recent records of megalopae of the crab Varuna litterata (Fabr.) entering Natal estuaries

An unusual occurrence Involving the stranding of many thousands of megalopae of the crab Varuna litterata on an outgoing tide is recorded. The locality was sandflats adjacent to the mouth of the Mgobezelenl estuary at Sodwana Bay, Natal, In mid-May 1985. Other records of recent local sightings are Included.