Effect of Calea serrata Less. n-hexane extract on acetylcholinesterase of larvae ticks and brain Wistar rats

The stem bark of Acacia oxyphylla Graham ex Bentham is used as an anthelmintic by the natives of Mizoram (North-East India). Therefore, the aim of the study was to assess the effect of the active compound isolated from A. oxyphylla on the tegument of adult Raillietina echinobothrida and Ascaridia galli. The test parasites R. echinobothrida and A. galli were incubated in physiological buffered saline containing 0.0005, 0.001, 0.05, 0.1 and 1mg/ml of the isolated compound. The alterations in the tegument of the parasites post paralysis were examined using electron microscopes. The compound reduced the cestode's motility soon after incubation, but did not induce paralysis in the nematodes till about 11-14 h at highest concentration. The compound caused extensive digestion of cestode tegument as evident by electron microscopy. Disorganization of muscle bundles, loss of cell-cell contact, extreme vacuolization and oedema were some of the changes observed. Loss of cellular organelles combined with distortion of those present was markedly noted throughout the parasite tissue. Deformation and disorganization of epicuticle, disruption of mitochondrial and nuclear membrane were also observed in nematode exposed to the active compound of the plant. Substantial structural deformities in the treated parasites are indicative of an efficient vermicidal activity of the isolated compound against cestodes and nematodes.     

Evaluation of the factors affecting direct polarization solid state 31P-NMR spectroscopy of bulk soils

³¹P‐NMR spectroscopy on bulk soils is a powerful tool for the identification of the different phosphorus forms in soils and for the evaluation of the dynamics of soil P. Up to now the majority of the papers dealt with liquid state ³¹P‐NMR spectroscopy on soluble soil organic substances. Only few papers were addressed to the study of the different phosphorus forms directly in bulk soils. In the present paper, some organic and inorganic phosphates of known structures, which are likely to be present in soil systems, were studied by direct polarization (DP) magic angle spinning (MAS) ³¹P‐NMR spectroscopy in order to understand the electronic factors responsible for chemical shifts of the phosphorus (P) nucleus and to serve as guidelines to assign P resonances in soil spectra. Number of hydrating water molecules, type of counter‐cation, degree of covalence, and spatial conformation of P in phosphate structures were found to affect signal positions in ³¹P‐NMR spectra. Both hydrating water and increase in degree of covalence of the X‐O‐P bonds (X=H, Na) enhanced the electronic density (E_D) around P, thereby producing up‐field shifts in ³¹P‐NMR spectra. The exchange of the Na⁺ counter‐cation with NH₄⁺ resulted in an increase of the cation potential (P_C) that is a measure of the cation polarizing power, and induced a down‐field shift of P signals, due to a corresponding reduction in E_D around the P nucleus. Both NMR down‐ and up‐field shifts were observed in organic phosphates, and were dependent on the spatial orientation of the phosphate groups that may have been fixed anisotropically in the solid state. Based on the factors that influence P chemical shifts for standard phosphates, attempts to assign ³¹P‐NMR signals in the spectra of five different unperturbed bulk soils were made.     

Use of two different dietary energy and protein contents to define nutritive requirements of lactating buffalo cows

Two total mixed rations, differing in energy and protein concentrations (diet A: 6.1 MJ/kg DM of NE(l), 112.5 g/kg DM of metabolizable protein, MP, and 101.7 g of protein digestible at the intestinal level, PDI, vs. diet B: 6.4 MJ, 95.1 g of MP, 78.9 g of PDI) were administered ad libitum for 1 year to two groups of 12 buffaloes in which the partial monthly turnover of animals allowed the lactation stage to be maintained close to 160 days. The diets were formulated to obtain, with a daily intake of about 15.5 kg of DM, a balanced energy supply but an excess of protein (diet A); the opposite occurred with diet B. The average dry matter intake recorded during the trial was 14.5 kg for diet A and 15.0 kg for diet B. Milk production was similar for both groups (7.94 kg vs. 7.95 kg). The diet with a higher protein concentration brought about a significant increase in protein, casein and non-protein nitrogen contents in the milk. A significant increase in milk fat percentage was observed when the animals were fed the diet with a higher energy concentration. The serum urea concentration (8.62 mm/l) of buffaloes fed diet A was outside the physiological range for lactating buffaloes. The energy and protein conversion efficiencies for milk production were more favourable when their supplies were balanced: 3.58 MJ of NE(l)/kg of FPCM for diet A; 2.50 g of MP or 2.07 g of PDI/g of protein milk for diet B. Moreover, when the requirements were satisfied, greater energy or protein supplies failed to induce significant changes in milk yield and quality. Finally, regarding the great differences between estimated MP requirements and those recorded during the trial, the authors suggest that the equations used in the CPM-Dairy software, formulated for dairy cows, are not applicable in buffaloes.     

Mixed-species plantations of Acacia mangium and Eucalyptus grandis in Brazil: 2: Nitrogen accumulation in the stands and biological N2 fixation

The sustainability of plantation forests is closely dependent on soil nitrogen availability in short-rotation forests established on low-fertility soils. Planting an understorey of nitrogen-fixing trees might be an attractive option for maintaining the N fertility of soils. The development of mono-specific stands of Acacia mangium (100A:0E) and Eucalyptus grandis (0A:100E) was compared with mixed-species plantations, where A. mangium was planted in a mixture at a density of 50% of that of E. grandis (50A:100E). N₂ fixation by A. mangium was quantified in 100A:0E and 50A:100E at age 18 and 30 months by the ¹⁵N natural abundance method and in 50A:100E at age 30 months by the ¹⁵N dilution method. The consistency of results obtained by isotopic methods was checked against observations of nodulation, Specific Acetylene Reduction Activity (SARA), as well as the dynamics of N accumulation within both species. The different tree components (leaves, branches, stems, stumps, coarse roots, medium-sized roots and fine roots) were sampled on 5–10 trees per species for each age. Litter fall was assessed up to 30 months after planting and used to estimate fine root mortality. Higher N concentrations in A. mangium tree components than in E. grandis might be a result of N₂ fixation. However, no evidence of N transfer from A. mangium to E. grandis was found. SARA values were not significantly different in 100A:0E and 50A:100E but the biomass of nodules was 20–30 times higher in 100A:0E than in 50A:100E. At age 18 months, higher δ¹⁵N values found in A. mangium tree components than in E. grandis components prevented reliable estimations of the percentage of N derived from atmospheric fixation (%Ndfa). At age 30 months, %Ndfa estimated by natural abundance and by ¹⁵N dilution amounted to 10–20 and 60%, respectively. The amount of N derived from N₂ fixation in the standing biomass was estimated at 62 kg N ha⁻¹ in 100A:0E and 3 kg N ha⁻¹ in 50A:100E by the ¹⁵N natural abundance method, and 16 kg N ha⁻¹ in 50A:100E by the ¹⁵N dilution method. The total amount of atmospheric N₂ fixed since planting (including fine root mortality and litter fall) was estimated at 66 kg N ha⁻¹ in 100A:0E and 7 kg N ha⁻¹ in 50A:100E by the ¹⁵N natural abundance method, and 31 kg N ha⁻¹ in 50A:100E by the ¹⁵N dilution method. The most reliable estimation of N₂ fixation was likely to be achieved using the ¹⁵N dilution method and sampling the whole plant.     

Cryopreservation of sperm in annual fish Austrolebias minuano (Cyprinodontiformes; Rivulidae)

The effects of the cryoprotectants dimethyl sulfoxide, glycerol and methyl glycol at different concentrations on Austrolebias minuano sperm quality parameters were evaluated in this study. The cellular kinetic parameters, determined using flow cytometry, indicated the best results with the samples cryopreserved with 7.5% methyl glycol. Dimethyl sulfoxide concentrations of 7.5% and glycerol concentrations of 10%, 12.5% and 15% demonstrated the least benefit across all evaluated sperm kinetic parameters. When assessed using flow cytometry, a concentration of 7.5% methyl glycol similarly showed better sperm kinetic parameters than 12.5% dimethyl sulfoxide. We conclude that cryoprotectants, especially methyl glycol, are effective for the preservation of sperm quality in A. minuano. However, high sensitivity of spermatozoa against glycerol was observed in these studies; thus, it is not recommended for cryopreservation purposes.     

Chemical properties of humic matter as related to induction of plant lateral roots

A series of humic matter samples isolated from a soil sequence, different oxisols, size‐fractionated from a vermicompost humic acid and subjected to chemical modifications, were characterized by CPMAS ¹³C‐NMR spectroscopy. The relative signal areas in chemical shift regions of NMR spectra of the four sets of samples were analysed by principal component analysis (PCA). Hierarchical cluster analysis (HCA) was applied to build a classification model, which allowed the recognition of humic matter according to its origin. The relationship between carbon species and biological activity of humic acids, as promoters of lateral root emergence, was obtained by applying PLS multivariate analysis. This showed that lateral root emergence was mostly related to NMR parameters such as the hydrophobicity index (HB/HI) and the 40–110 and 160–200 ppm chemical shift regions (hydrophilic carbon HI), while the content of hydrophobic (HB) carbon in humic samples was negatively correlated with induction of lateral root hair. Our results represent a step further in the structure‐bioactivity relationship of natural humic substances and confirm their role as plant root growth promoters.     

Molecular characterization of compost at increasing stages of maturity. 2. Thermochemolysis-GC-MS and 13C-CPMAS-NMR spectroscopy

Off-line pyrolysis TMAH-GC-MS (thermochemolysis) and solid-state 13C NMR spectroscopy were applied for the direct molecular characterization of composted organic biomasses after 60, 90, and 150 days of maturity. Off-line thermochemolysis of both fresh and mature composts released various lignin-derived molecules, the quantitative measurement of which was used to calculate structural indices related to compost maturity. These indicated that most of the molecular transformation occurred within the first 60 days of the composting process, whereas slighter molecular variations were observed thereafter. Both 13C NMR spectra and offline programs suggested that the process of compost maturity was characterized by a progressive decrease of alkyl components, whereas cellulose polysaccharides appeared to be more resistant and began to be transformed at a later composting period. The main components of the final mature compost were lignocellulosic material and hydrophobic alkyl moieties, in as much as that commonly found in well-humidified organic matter of soils and sediments. The persistence of untransformed lignin-derived products and di- and triterpenoids throughout the maturity period suggested that these molecules are useful markers to both evaluate compost origin and trace its fate in the environment. Thermochemolysis provided the same characterization of molecules either unbound or bound to the compost matrix as that reached by a previously applied sequential chemical fractionation of the same compost materials, thereby indicating that thermochemolysis is a more rapid and equally efficient tool to assess compost molecular quality.