Path and correlation analysis of perennial ryegrass (Lolium perenne L.) seed yield components

Maximum perennial ryegrass seed production potential is substantially greater than harvested yields with harvested yields representing only 20% of calculated potential. Similar to wheat, maize and other agriculturally important crops, seed yield is highly dependent on a number of interacting seed yield components. This research was performed to apply and describe path analysis of perennial ryegrass seed yield components in relation to harvested seed yields. Utilising extensive yield components which included subdividing reproductive inflorescences into five size categories, path analysis was undertaken assuming a unidirectional causal‐admissible relationship between seed yield components and harvested seed yield in six commercial seed production fields. Both spikelets per inflorescence and florets per spikelet had a significant (p < .05) direct effect on the overall seed yield; however, total path correlation coefficients showed that inflorescence size had the largest positive influence on seed yield via its indirect effects on other seed yield components. Our results will allow seed producers, seed production researchers and plant breeders alike to more efficiently increase harvested seed yield.     

Effects of Bacillus subtilis strains and the prebiotic Previda® on growth,immune parameters and susceptibility to Aeromonas hydrophila infection in Nile tilapia,Oreochromis niloticus

This study was conducted to evaluate the individual and combined effects of long‐term feeding of diets containing two probiotic Bacillus subtilis group strains (Aqua NZ and AP193) and the prebiotic Previda^®, a commercial hemicellulose extract, on growth performance, immune parameters and Aeromonas hydrophila susceptibility of juvenile Nile tilapia, Oreochromis niloticus. Nile tilapia of average weight 7.47 ± 0.11 g were fed diets formulated with the probiotics and/or the prebiotic, or a control diet for 8 weeks and, subsequently, challenged with A. hydrophila by intragastric gavage at a dosage of 3.9 × 10⁷ CFU per fish. Fish attained a mean weight of 59.5 ± 0.99 g at the end of the growth period. Under the conditions of the present trial, none of the diets significantly improved mean per cent weight gain (P = 0.70), thermal growth coefficient (P = 0.88) or feed conversion ratio (P = 0.87) of Nile tilapia. Except for the diet containing the prebiotic Previda^® only (P = 0.17), all other diets resulted in significantly higher fish survival compared to the control (P < 0.05). The combined effect of the prebiotic and probiotic strains emerged as the most important diet with respect to mortality reduction. The mean lysozyme and respiratory burst activities did not show any significant differences between treatments and control (P = 0.14 and 0.32, respectively). Thus, these probiotic strains used in this study have the potential to prevent disease due to A. hydrophila in O. niloticus.     

Elasmobranch pericardial function. 3. The pericardioperitoneal canal in the horn sharkHeterodontus francisci

The pericardial and peritoneal spaces of elasmobranch fishes are connected by the pericardioperitoneal canal (PPC), which allows pericardial fluid to escape when pressures exceed 0.1–0.3 kPA. Using the horn shark (Heterodontus francisci), we tested the hypothesis that the PPC functions to increase cardiac stroke volume by lowering pericardial pressure during activity. We also assessed the role of the PPC during coughing, feeding, or burst swimming and examined the effects of PPC occlusion. Increases in heart size were not prevented following augmented venous return in sharks with undisturbed or occluded PCP, evidence that argues that pericardial fluid loss through the PPC is a cause of increased cardiac stroke volume and not the result. Coughs, feeding, and burst swimming led to discharge of pericardial fluid. Chronic PPC occlusion resulted in an increased pericardial pressure, fluid volume, and frequency of coughing, and a decreased survival time compared to shams. Thus, in the horn shark the PPC likely compensates for constraints that may be imposed by the pericardium, provides a route for pericardial drainage, and regulates cardiac stroke volume during periods of activity.     

Marihuana and memory: acquisition or retrieval?

Two experiments were conducted to determine the means by which marihuana affects human memory. The results of these studies indicated that marihuana did not affect retrieval of information in memory when the method of free recall was used, but did affect recognition processes such that subjects were less able to discriminate between items that had been presented previously and items that had not appeared a short time before. With respect to initial learning, marihuana was shown to affect acquisition processes involved in the storage of information.     

Re-examination of the metabolizable energy contents of various rations containing different types and levels of bacterially fermentable substrates in digestibility experiments with growing pigs

Introduction   Feedstuffs with elevated contents of bacterially fermentable substrates (BFS: GFE 1987) offered to pigs have intermediate metabolizable energy (ME) contents compared with feedstuffs mainly composed of starch or hardly fermentable fibre (H adorn et al. 1996a,b). Consequently, BFS-elevated feeds could be used as major components enabling pig fattening rations to obtain the ME values required for feed calculation from tabulated values (DLG 1991) or equations based on nutrient composition (GFE 1996). The main field of application for BFS-elevated feeds is, however, still the feeding of adult, non-lactating sows, with the majority of investigations on fermentation characteristics also being conducted with sows. In fattening pigs a higher accuracy of estimated ME contents is required than in non-lactating sows. Furthermore, the ME values of feeds with elevated BFS contents might be systematically different in sows and fattening pigs because a still incomplete evolution of the fermentative capacity of the hindgut of growing pigs cannot be totally excluded (J entsch et al. 1990). The efficiency of hindgut bacterial protein synthesis might also be different from that being assumed from sow data (e.g. K irchgessner et al. 1989, 1994).
The objective of the present study was to determine the actual ME and BFS contents of rations varying widely in type and level of BFS in three experiments with growing pigs. By comparing these values with those calculated from equations or from tabulated values a re-examination of the currently applied feed evaluation system should be carried out. Furthermore, interactions of BFS with dietary protein reduction were investigated, since in low-protein rations fermentation efficiency might be limited by a lack of nitrogen in the hindgut (M osenthin 1987).     

Activity and metabolism of cyano-oxime derivatives in various strains of Botrytis cinerea

The fungitoxicity of cymoxanil, 4 cyano-oxime analogs (in which the acetylurea group was replaced with various groups: amide, ester, propargyl, and cyanomethyl-amide), and 2 cymoxanil-metabolites was studied against various strains of Botrytis cinerea. The fungicidal effect was measured on germ-tube elongation and mycelial growth. Cymoxanil and the analogs bearing the amide and ester groups showed the best anti-botrytis activity. The strains studied can be classified into 3 groups according to the germ-tube sensitivity to cyano-oximes. These groups fitted well with the 3 phenotypes of sensitivity to cymoxanil previously characterized in our laboratory: CyaS₁ (highly sensitive phenotype); CyaS₂ (moderately sensitive phenotype); and CyaR (tolerant phenotype). The bio-transformations of all the cyano-oximes were monitored in the culture-medium of the different strains using HPLC- and IP-HPTLC-methods. HPLC-studies showed that cymoxanil and the analogs bearing the groups amide and ester were quickly metabolized in the culture-medium of the CyaS₁ strain. Moreover, these studies allowed us to correlate disappearance of these cyano-oximes, to their fungicidal activity towards the CyaS₁ strain. This suggests that cyano-oximes and particularly cymoxanil are probably activated in a fungitoxic compound. IP-HPTLC-studies strengthened the precedent results and allowed us to correlate disappearance of cyano-oximes studied with appearance of two acids metabolites of hydrolysis. These metabolites could be the actual active-principles.     

Skills across the Urban–Rural Hierarchy

This paper examines the vertical and horizontal dimensions of human capital across regions within the U.S., ranging from densely populated city centers to isolated and sparsely populated rural areas. To do so, we classify detailed geographic areas into categories along the entire urban–rural hierarchy. An occupation‐based cluster analysis is then used to complement the conventional measure of human capital, based on college attainment, by measuring the types of skills available in the regional workforce. We find that differences in human capital across the urban–rural hierarchy are related to both the types of work performed in urban and rural areas and that a higher share of college‐educated workers is present in urban areas regardless of the skills typically required to perform the job.     

Quality assessment and quantitative analysis of flavonoids from tea samples of different origins by HPLC-DAD-ESI-MS

Components of green tea ( Camellia sinensis) have been of considerable interest in recent years because of their potential utility as pharmaceutical agents, particularly for their antioxidant and anticarcinogenic activity. Responding to the increasing scientific validation of numerous health benefits of tea, a comprehensive approach was adopted to carry out analysis for the quality assessment of flavonoids in tea samples of different origins. For this purpose, extraction, separation, and mass spectrometric parameters were optimized. Extraction methods evaluated include reflux extraction, a modified accelerated solvent extraction (ASE), namely, Aquasolv extraction, and microwave-assisted extraction (MAE) using different percentages of solvents. Separation was performed by a specifically developed reversed phase high-performance liquid chromatography (RP-HPLC) method using different C18 and C8 stationary phases. Optimization of extraction techniques clearly proved the performance of MAE, which delivered highest yields in a very short time. Additionally, the comparison with Aquasolv extraction provided new insights, as variations in quantified amounts of target compounds between the extracts could be explained on the basis of thermal degradation and epimerization phenomena. Especially the epimerization phenomenon for catechin/epicatechin oligomers, that is, of procyanidins P 2 and P 3, was observed for the first time. Finally, an optimized extraction and separation system was used for qualitative and quantitative investigations of compounds from different green tea samples from Ceylon (cultivated under biologically controlled conditions), Japan, India, and China as well as from one black tea sample from India.