Genotypic and Phenotypic Assessment of Hyaluronidase among Type Strains of a Select Group of Staphylococcal Species

Hyaluronidases degrade hyaluronic acid, a major polysaccharide of the extracellular matrix of tissues, and are considered important for virulence in a number of Gram-positive and -negative bacteria. The purpose of the present study was to determine the prevalence of hyaluronidase among clinical strains of Staphylococcus aureus and among other Staphylococcus species. Spent media and chromosomal DNA were assessed for hyaluronidase activity and the absence or presence of a hyaluronidase gene (hysA) by Southern analysis, respectively. All S. aureus strains examined exhibited at least one hybridizing band (half of the strains exhibited two or more hybridizing bands) when probed for hysA and all but three of these strains produced hyaluronidase. In contrast, none of the type strains of 19 other species exhibited either hyaluronidase activity or hybridizing bands when probed for hysA. These data support the hypothesis that among members of the Staphylococcus genus only strains of S. aureus possess the enzyme hyaluronidase. This would suggest that hyaluronidase represents yet another potential virulence factor employed by S. aureus to cause disease and may represent a diagnostically important characteristic for distinguishing S. aureus from other members of this genus

Impact of Diet and Quality Grade on Shelf Life of Beef Steaks

Steers were fed a diet containing dry rolled corn, steam flaked corn, dry rolled corn with 30% dried distillers grains, or steam flaked corn with 30% dried distillers grains. Strip loins from upper 2/3 Choice and Select- grade carcasses were obtained to evaluate the effects of diet and quality grade on shelf life characteristics. Strip loins were aged for 2, 9, 16, or 23 days. Results suggest that steaks from cattle fed steam flaked corn (with or without dried distillers grains) and from cattle fed dried distillers grains (regardless of corn type) had higher levels of many unsaturated fatty acids, more discoloration, and greater lipid oxidation compared to the dry rolled corn treatments or the no dried distillers grains treatments, respectively. Feeding of dry rolled corn or diets without dried distillers grains maintained red color better during retail display. Choice- grade steaks had significantly higher levels of unsaturated fatty acids like 18:2 and total polyunsaturated fatty acids than Select- grade steaks but did not diff er in color stability or oxidation. These data indicate the longest shelf life will occur when cattle are fed diets containing dry rolled corn (versus steam flaked corn) or without dried distillers grains (versus with dried distillers grains) and that both steam flaked corn and distillers grains have a negative impact on shelf life. Quality grade did not affect color stability

Impact of Grazing Management Strategies on Carbon Sequestration in a Semi-Arid Rangeland, USA

The effects of 12 years of grazing management strategies on carbon (C) distribution and sequestration were assessed on a semi-arid mixed-grass prairie in Wyoming, USA. Five grazing treatments were evaluated: non-grazed exclosures; continuous, season-long grazing at a light (22 steer-days ha-1) stocking rate; and, rotationally-deferred, short-duration rotation, and continuous, season-long grazing, all three at a heavy stocking rate (59 steer-days ha-1). Non-grazed exclosures exhibited a large buildup of dead plant material (72% of total aboveground plant matter) and forb biomass represented a large component (35%) of the plant community. Stocking rate, but not grazing strategy, changed plant community composition and decreased surface litter. Light grazing decreased forbs and increased cool-season mid-grasses, resulting in a highly diversified plant community and the highest total production of grasses. Heavy grazing increased warm-season grasses at the expense of the cool-season grasses, which decreased total forage production and opportunity for early season grazing. Compared to the exclosures, all grazing treatments resulted in significantly higher levels of C (6000-9000 kg ha-1) in the surface 15 cm of the soil. Higher levels of soil C with grazing are likely the result of faster litter decomposition and recycling, and redistribution of C within the 0-60 cm plant-soil system. Grazing at an appropriate stocking rate had beneficial effects on plant composition, forage production, and soil C sequestration. Without grazing, deterioration of the plant-soil system is indicated

Toward a model of multiple paths to language learning: response to commentaries

Language learning, while seemingly effortless for young learners, is a complex process involving many interacting pieces, both within the child and in their language-learning environments, which can result in unique language learning trajectories and outcomes. How does the brain adjust to or accommodate the myriad variations that occur during this developmental process. How does it adapt and change over time? In our review, we proposed that the timing, quantity, and quality of children's early language experiences, particularly during an early sensitive period for the acquisition of phonology, shape the establishment of neural phonological representations that are used to establish and support phonological working memory (PWM). The efficiency of the PWM system in turn, we argued, influences the acquisition and processing of more complex aspects of language. In brief, we proposed that experience modulates later language outcomes through its early effects on PWM. We supported this claim by reviewing research from several unique groups of language learners who experience delayed exposure to language (children with cochlear implants [CI] or internationally adopted [IA] children, and children with either impoverished [signing deaf children with hearing parents)] or enriched [bilingual] early language experiences). By comparing PWM and language outcomes in these groups, we sought to highlight general patterns in language development that emerge based on variation in early language exposure. Moving forward, we also proposed that the language acquisition patterns in these groups, and others, can be used to understand how variability in early language input might affect the neural systems supporting language development and how this might affect language learning itself

Exploring the prevalence and diversity of pollen carried by four species of migratory Old World warbler (Sylvioidea) on arrival in the UK

Capsule Pollen encrusted around the bill of migrating warblers can reveal marked differences in foraging ecology between bird species. Aims To examine patterns of the prevalence and diversity of pollen in four species of warbler, and explore the potential of pollen to act as an indicator of recent foraging behaviour. Methods By isolating pollen from bill encrustations using laboratory palynological techniques and identification by light microscopy, we examined variation in the prevalence of the five most common pollen taxa, and variation in pollen assemblages in four species of warbler arriving on the south coast of England. Results All samples contained abundant pollen, with 19 floral taxa identified. Sylvia warblers tended to carry Prunus and Citrus pollen, while Phylloscopus warblers mainly carried Eucalyptus pollen. Pollen assemblages varied markedly between bird species. Conclusion Commercial and garden flowering trees are an important resource for migrating warblers. Pollen may be such a valuable resource that flowering plants might be included in the conservation management of stopover sites. The use of pollen to resolve migratory routes may be problematic however, requiring detailed knowledge of both the distribution and flowering phenology of plants en route

Quality Effects on Beef from Cattle Fed High-Protein Corn Distillers Grains and Other Ethanol By-Products

The objective of this study was to evaluate the effects of feeding high protein corn distillers grains on fresh beef quality. Steers were fed one of five diets, either a corn control, high protein distillers grains plus solubles, dry distillers grains plus solubles, wet distillers grains plus solubles, or bran plus solubles diet. Strip loins were aged for 2, 9, or 23 days and placed under retail display conditions for 0 or 7 days. Dietary treatment had no effect on tenderness within each aging period. There were also no differences between treatments for proximate composition, free calcium in the muscle, and sarcomere length. Results suggest that feeding high protein distillers grains decreases color stability and increases lipid oxidation when compared to corn diets leading to reduced shelf life

Solving non-uniqueness in agglomerative hierarchical clustering using multidendrograms

In agglomerative hierarchical clustering, pair-group methods suffer from a problem of non-uniqueness when two or more distances between different clusters coincide during the amalgamation process. The traditional approach for solving this drawback has been to take any arbitrary criterion in order to break ties between distances, which results in different hierarchical classifications depending on the criterion followed. In this article we propose a variable-group algorithm that consists in grouping more than two clusters at the same time when ties occur. We give a tree representation for the results of the algorithm, which we call a multidendrogram, as well as a generalization of the Lance and Williams' formula which enables the implementation of the algorithm in a recursive way.Comment: Free Software for Agglomerative Hierarchical Clustering using Multidendrograms available at http://deim.urv.cat/~sgomez/multidendrograms.ph

Impact of Myoglobin Oxygenation State on Color Stability of Frozen Beef Steaks

The objective of this study was to determine the impacts of myoglobin oxygenation level and frozen storage duration on frozen beef color. Strip loins were wet- aged for 4 or 20 days and were fabricated into steaks that were assigned a myoglobin oxygenation level (highly oxygenated, lowly oxygenated, or deoxymyoglobin) and packaging film (impermeable or permeable). Steaks were then frozen for 0, 2, 4, or 6 months of storage and analyzed for various beef color measurements. Highly oxygenated steaks had greater a* values (redness) and percent oxymyoglobin compared to the other treatments. Frozen storage beyond 4 months and oxygen impermeable packaging tended to have detrimental effects on beef color. Highly oxygenated steaks that are aged for 4 d displayed superior red color for extended storage with few undesirable effects

The Relationship of Liver Abscess Scores and Early Postmortem Meat Tenderness

Acidosis is one of the most common nutritional disorders found in commercial feedlots. Cattle diets with high concentrations of starch can cause rapid production of acids in the rumen, disrupting microbial fermentation, causing liver abscess formation, and lowering livestock performance. This study was conducted to evaluate the relationship between the occurrence of liver abscesses and beef tenderness early postmortem. Results showed numerically lesser shear force values (greater tenderness) in loins from animals without liver abscesses, however, this was not statistically significant for slice shear force or Warner- Bratzler shear force. Although the effects of liver abscess occurrence in relation to meat quality are still unclear, results from this study provide a conceptual foundation for additional research to be explored on meat quality