Life Cycle of \u3ci\u3eIsoperla Lata\u3c/i\u3e (Plecoptera: Perlodidae) in a Central Wisconsin Trout Stream

Monthly qualitative samples of Isoperla lata Frison were made from January 1992 to June 1993 in Ripley Creek, a small second order trout stream in Lincoln County Wisconsin. Additional collecting and an in-stream hatching experiment were conducted in 1994. This species exhibited an S1 (slow) univoltine life cycle. Emergence was synchronous and occurred in late April through early May when stream temperatures in the field were approximately 9-14° C and laboratory stream temperatures were 7-17° C. Laboratory longevity was 2-25 (x = 18.2 ± 4.51) days for males and 7-39 (x = 21.7 ± 5.35) days for females. Mean fecundity of dissected females was 322 ± 122 eggs/female. Females did not deposit egg masses in the laboratory until being held together with males inside modified screened plastic containers. Field-collected females did not have eggs. The egg shape was ovoid and circular in cross section. Mature eggs were light brown and measured 371.7 ± 12.6 mm and 260.7 ± 10.2 mm in length and width respectively. Eggs required a 40-46 day in-stream incubation period and first instar nymphs hatched syn- chronously over a two day period when stream temperature reached 20°C. Nymphal growth was nearly exponential from June to January and then declined until emergence. The greatest growth increment occurred between June and October and the average maximum size attained occurred in February. Males and females had approximately 18 and 19 instars respectively. Nymphs were primarily carnivorous throughout development and fed on larval Chironomidae, Ephemeroptera, and Plecoptera

The changes in chemical composition during development of the bovine nuchal ligament

Whole bovine nuchal ligaments, or portions thereof (in the case of commercially valuable animals), were obtained from 45 animals (28 fetal and 17 postnatal) ranging in age from 110 days of gestation to 10 yr. Insoluble elastin was quantitatively prepared from the fresh ligaments by extraction with hot alkali and by a combination of multiple extractions with alkaline buffer and then repeated autoclaving. When adult samples were examined, the yields of insoluble residue by these two methods were very similar, but with young fetal samples the second method gave significantly higher values, because of incomplete purification of the elastin residue. The changes in the concentration of collagen, alkali-insoluble elastin, and DNA have been examined. DNA concentration, and, thus, cell population density, fell progressively during the fetal period of development, to reach a steady value soon after birth. Collagen appeared in appreciable quantities before elastin, but its concentration was rapidly halved at about the time of birth. Insoluble elastin concentration was low until the end of the 7th fetal month, at which time it began to rise rapidly. The rate of increase in elastin concentration remained high throughout the next 10–12 wk, by which time the adult value had been reached. Quantitative studies, on the basis of the whole ligament, showed that the total cell content rises to a maximum at birth, but falls soon after to a level about half that at birth. Total collagen production and elastin deposition continue at a steady, maximal rate over the interval from 235 days of gestation to the end of the 1st postnatal month. It is concluded that the immediate postnatal period would be the most favorable phase in which to attempt the isolation of the soluble precursor elastin

Modelling the effects of the infectious environment on pig growth and intake

Sub-clinical disease can have large effects on animal production with significant economic consequences. Animal health and welfare are increasingly important criteria in animal production, and the removal of antibiotic growth promoters has added pressure on production systems. No general model has yet been proposed for predicting the growth and performance of animals exposed to pathogens. A robust framework for predicting growth during health and disease may assist in the design of nutritional, environmental and genetic management strategies. A core part of any animal growth model is how it predicts the partitioning of dietary protein and energy to protein and lipid retention for different genotypes at different degrees of maturity. Solutions proposed in the literature to the partitioning problem were described in detail and criticised in relation to their scope, generality and economy of parameters (Chapter 1). They all raised the issue, often implicitly, of the factors that affect the net marginal efficiency of using absorbed dietary protein for protein retention. Partitioning rules that withstood qualitative criticisms were then tested against literature data and a general quantitative partitioning rule was concluded for that had two key parameters: the maximum marginal efficiency of protein retention and the energy to protein ratio at which the maximum efficiency is achieved (Chapter 2). A general rule was identified which was able to predict protein retention for both protein and energy limiting diets in healthy animals. In Chapter 3 a general model was developed for predicting effects of sub-clinical pathogen challenges of different doses and virulence on the intake of animals. Pathogen induced anorexia is the major consequence on hosts during the course of infection. The model was for the period from recognition of a pathogen through to acquisition and subsequent expression of immunity. It is crucial to define the pathogen challenge (in terms of dose and virulence) and the degree of resistance of different hosts, when comparing their responses in RFI. There is no general agreement on the consequences of pathogen challenges, other than anorexia, that need to be included in a predictive framework of growth. In Chapter 4 literature data was reviewed for different kinds of pathogen challenges of a range of hosts to identify reductions in growth beyond that caused by anorexia: these were host, dose and time dependent. In only some instances did anorexia fully explain the reductions in growth. Solutions were needed for describing the protein costs of innate and acquired immune responses and repair of damaged tissues. Increased energy requirements depended on immune responses, repair of damage and fever. In Chapter 5 a framework was proposed that predicts the performance of different genotypes (in terms of growth potential and disease resistance) when challenged by different doses of pathogens and given access to different foods. The model predicts amino acid and energy requirements due to growth and immune responses, and a partitioning rule was developed for partitioning scarce resources between growth and immune responses. Predictions can be made on the performance of different animal genotypes when they are given access to different quality foods and exposed to pathogens. The development of the model and its predictions, together with future testing, may contribute significantly towards our understanding of nutrition and genotype interactions during exposure to pathogens

Acute Effects of Antagonist Stretching on Jump Height and Knee Extension Peak Torque

A great deal of research has shown decrements in force and power following static stretching. There has been little research investigating the acute effects of static stretching of the antagonist on the expression of strength and power. The purpose of this study was to investigate the effects of static stretching of the antagonist muscles on a variety of strength and power measures. Sixteen active males were tested for vertical jump height and isokinetic torque production in a slow knee extension (KES) at 60°/s and a fast knee extension (KEF) at 300°/s. Electromyography was taken during knee extension tests for the vastus lateralis and the biceps femoris muscles. Participants performed these tests in a randomized counterbalanced order with and without prior antagonist stretching. All variables for stretching and non-stretching treatments were compared using paired t tests at an alpha of .05. Paired samples t tests revealed a significant (p = .034) difference between stretch KEF and non-stretch KEF conditions. There was no significant (p \u3e .05) difference between KES stretch and non-stretch conditions. Vertical jump height was significantly (p = .011) higher for the stretching treatment than the non-stretching treatment. Vertical jump power was also significantly higher (p = .005) in the stretch versus the non-stretch condition. Paired samples t test indicated no significant (p \u3e .05) difference between testing conditions for electromyography, represented as a percentage of maximal voluntary contraction (MVC). These results suggest that stretching the antagonist hamstrings prior to high speed isokinetic knee extension increases torque production. It also demonstrated that stretching the hip flexors and dorsi flexors may enhance jump height and power. Practitioners may use this information to acutely enhance strength and power performances

Evaluation of the usefulness of carcass-weight, meat-percentage or identity of pig-producer in future-risk-based meat inspection

In the search for new and risk-based ways of conducting meat inspection, a pilot study was conducted with the amin of investigating whether carcass weight in combination with meat percentage, or producer-identity could be used as indicators for rejection of finisher pig carcasses

The role of sea-level change and marine anoxia in the Frasnian-Famennian (Late Devonian) mass extinction

Johnson et al. (Johnson, J.G., Klapper, G., Sandberg, C.A., 1985. Devonian eustatic fluctuations in Euramerica. Geological Society of America Bulletin 96, 567–587) proposed one of the first explicit links between marine anoxia, transgression and mass extinction for the Frasnian–Famennian (F–F, Late Devonian) mass extinction. This cause-and-effect nexus has been accepted by many but others prefer sea-level fall and cooling as an extinction mechanism. New facies analysis of sections in the USA and Europe (France, Germany, Poland), and comparison with sections known from the literature in Canada, Australia and China reveal several high-frequency relative sea-level changes in the late Frasnian to earliest Famennian extinction interval. A clear signal of major transgression is seen within the Early rhenana Zone (e.g. drowning of the carbonate platform in the western United States). This is the base of transgressive–regressive Cycle IId of the Johnson et al. (Johnson, J.G., Klapper, G., Sandberg, C.A., 1985. Devonian eustatic fluctuations in Euramerica. Geological Society of America Bulletin 96, 567–587) eustatic curve. This was curtailed by regression and sequence boundary generation within the early linguiformis Zone, recorded by hardground and karstification surfaces in sections from Canada to Australia. This major eustatic fall probably terminated platform carbonate deposition over wide areas, especially in western North America. The subsequent transgression in the later linguiformis Zone, recorded by the widespread development of organic-rich shale facies, is also significant because it is associated with the expansion of anoxic deposition, known as the Upper Kellwasser Event. Johnson et al.'s (Johnson, J.G., Klapper, G., Sandberg, C.A., 1985. Devonian eustatic fluctuations in Euramerica. Geological Society of America Bulletin 96, 567–587) original transgression-anoxia–extinction link is thus supported, although some extinction losses of platform carbonate biota during the preceeding regression cannot be ruled out. Conodont faunas suffered major losses during the Upper Kellwasser Event, with deep-water taxa notably affected. This renders unreliable any eustatic analyses utilising changes in conodont biofacies. Claims for a latest Frasnian regression are not supported, and probably reflect poor biostratigraphic dating of the early linguiformis Zone sequence boundary

Subtotal pancreatectomy for cancer: closure of the pancreatic remnant with staplers

This paper presents a 2-year series of 26 consecutive pancreatectomies for periampullary cancer where the pancreatic tail was closed with a stapler in order to avoid complications related to a pancreatico-digestive anastomosis. The follow-up period was 14 months or more. Seven patients developed operative complications. Pancreatic fistulas developed in 3 patients. The fistulas closed spontaneously in 2 of the patients after 2-4 months. Intraabdominal abscesses developed in 4 patients and required surgical drainage. In 1 of these patients, the abscess eroded a large vessel with a fatal outcome resulting in an operative mortality rate of 3.8%. A transient postoperative gastric stasis was observed in seven patients. Postoperative hospital median stay was 27 days (range 10-83 days). Eighteen patients have died after 4-30 months in recurrent disease and seven patients are alive after a follow-up period of 15-29 months. Pancreatic endocrine function seemed well preserved; diabetes mellitus has developed in only one patient. In conclusion, it appears that subtotal pancreatectomy with closure of the pancreatic remnant with staples gives a low morbidity and mortality. Although the conclusion should be tempered by the small number of patients, the results justify continued evaluation of this technique with long-term follow-up