921 resultados para Dogs - Reproduction


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Assisted Reproductive Technologies (ART) offer a wide range of techniques that have the potential to augment efforts to conserve and manage endangered amphibians and improve wild and captive population numbers. Gametes and tissues of species nearing endangered or extinct status can be cryopreserved and stored in gene banks, to provide material that can be utilised in the future as ART methods are refined. The Spotted Grass Frog, Limnodynastes tasmaniensis, is an abundant amphibian species in South-Eastern Australia of the family Myobatrachidae, that is suitable for the development of ART systems that can be applied to the threatened and endangered myobatrachid and other amphibian species native to Australia. The aim of this study was to advance the understanding of ovulation, fertilisation and embryo nic development of Lim. tasmaniensis and in vitro manipulations of reproduction and development for use in the development of advanced ART procedures such as intracytoplasmic spermatozoon injection (ICSI), androgenesis and nuclear transfer. Ovulation in amphibians can be induced by protocols utilising natural or synthetic hormones. All protocols tested on Lim. tasmaniensis in this study required two injections and the most effective protocols continued to require a first injection of pituitary extracts to induce ovulation. The second injection was, however, successfully replaced by synthetic chorionic gonadotrophin at a threshold dosage of 100 iu and halved the number of cane toads required to source the pituitaries. A combination of LHRH and Pimozide offered a less effective protocol, that did not require the use of pituitary extracts, and avoided the risk of pathogen transfer associated with unsterilised pituitary extracts. Unfertilised eggs of Lim. tasmaniensis were exposed to media of various osmolalities to determine media effects on eggs and their surrounding jelly layers that might impact on egg viability and fertilisability. Osmolality had no effect upon the egg diameter, however, rapid swelling of the jelly layers occurred within 15 minutes of exposure to various media treatments and plateaued from 30-90 minutes without further expansion. Swelling of the jelly layers was increased in hypotonic media (2.5% SAR, H2O) and minimised in the isotonic media (100% SAR). The optimal conditions for the culture of Lim. tasmaniensis eggs were identified as a holding media of 100% SAR, followed by a medium change to 2.5% SAR at insemination. This sequence of media minimised the rate of swelling of the jelly layers prior to contact with the spermatozoa, and maximised the activation of spermatozoa and eggs throughout fertilisation and embryonic development. Embryos of Lim. tasmaniensis were cultured at four temperatures (13 C, 17 C, 23 C and 29 C), to determine the effect of temperature on cleavage and embryonic development rates. Embryonic development progressed through a sequence of stages that were not altered by changes in temperature. However cleavage rates were affected by changes in temperature as compared with normal embryonic growth at 23 C. Embryonic development was suspended at the lowest temperature (13 C) while embryonic viability was maintained. A moderate decrease in temperature (17 C) slowed cleavage, while the highest temperature (29 C) increased the cleavage rate, but decreased the embryo survival. Rates of embryonic development can be manipulated by changes in temperature and this method can be used to source blastomeres of a specific size/stage at a predetermined age or halt cleavage at specific stages for embryos or embryo derived cells to be included in ART procedures. This study produced the first report of the application of Intracytoplasmic Spermatozoon Injection (ICSI) in an Australian amphibian. Eggs that were activated by microinjection with a single spermatozoon (n=50) formed more deep, but abnormal, cleavage furrows post-injection (18/50, 36%), than surface changes (12/50, 24%). This result is in contrast to eggs injected without a spermatozoon (n=42), where the majority of eggs displayed limited surface changes (36/42, 86%), and few deep, abnormal furrows (3/42, 7%). Three advanced embryos (3/50, 6%) were produced by ICSI that developed to various stages within the culture system. Technical difficulties were encountered that prevented the generation of any metamorphs from ICSI tadpoles. Nevertheless, when these blocks to ICSI are overcome, the ICSI procedure will be both directly useful as an ART procedure in its own right, and the associated refinement of micromanipulation procedures will assist in the development of other ART procedures in Lim. tasmaniensis. A greater understanding of basic reproductive and developmental biology in Lim. tasmaniensis would greatly facilitate refinement of fertilisation by ICSI. Assisted Reproductive Technologies, in conjunction with gene banks may in the future regenerate extinct amphibian species, and assist in the recovery of declining amphibian populations nationally and worldwide.

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Traffic safety studies demand more than what current micro-simulation models can provide as they presume that all drivers of motor vehicles exhibit safe behaviours. Several car-following models are used in various micro-simulation models. This research compares the mainstream car following models’ capabilities of emulating precise driver behaviour parameters such as headways and Time to Collisions. The comparison firstly illustrates which model is more robust in the metric reproduction. Secondly, the study conducted a series of sensitivity tests to further explore the behaviour of each model. Based on the outcome of these two steps exploration of the models, a modified structure and parameters adjustment for each car-following model is proposed to simulate more realistic vehicle movements, particularly headways and Time to Collision, below a certain critical threshold. NGSIM vehicle trajectory data is used to evaluate the modified models performance to assess critical safety events within traffic flow. The simulation tests outcomes indicate that the proposed modified models produce better frequency of critical Time to Collision than the generic models, while the improvement on the headway is not significant. The outcome of this paper facilitates traffic safety assessment using microscopic simulation.

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Purpose - Critical scholarship on work-life balance (WLB) and its associated practices maintains that workplace flexibility is more than a quasi-functionalist response to contemporary problems faced by individuals, families or organisations. Beginning with Fleetwood’s contention that WLB discourses have become "detached" from their associated practices, this paper explores how workplace practices support or challenge dominant WLB discourses evident in socio-cultural, political and organisational sources. Design/methodology/approach - We analyse individual and group interview transcripts derived from 122 white-collar employees in two different organisational contexts (one public, one private) in the construction industry in Australia. Findings - Four major themes were identified in the data which illustrate discourse practice gaps. First, the demands facing this particular industry/ sector were framed as heightened and unique. Second, productivity was prioritised, dominating employees’ care-giving and lifestyle concerns. Third, employees’ caring responsibilities were communicated as personal and individual choices. Fourth, commitment and efficiency were judged on the basis of presence in the workplace. Research limitations/implications - Even in industries that have embraced WLB, workplace practices legitimate and reinforce the status quo, and maintain a gap between the promises of WLB and its potential to ameliorate conflict and assist workers to span the boundaries of paid work and other life domains. Originality/value - While the practices demonstrated in the research are focused on one industry, the study provides a critical analysis of how the contextually-influenced meaning of WLB is constructed, created and contested in these workplaces and the effects it produces.

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Animals are often used as ‘evidence’ of marine pollution. Take for instance the ubiquitous images of miserable oil-soaked marine birds following high profile oil spills such as the Exxon Valdez, Pacific Adventurer and Deepwater Horizon incidents or the images of bloated floating fish carcasses which are used to signal the presence of toxic pollutants. In recent years waste discharges from vessels have come under increased public and regulatory scrutiny both in Australia and around the world. International, regional, national and local restrictions are becoming more stringent for high profile marine pollutants such as oil as well as previously overlooked vessel-sourced pollutants such as sewage. Drawing upon media reports and recreational boater responses to government attempts to regulate the discharge of sewage from recreational vessels, this paper considers the important role played by animals in constructions of marine pollution by sewage and attributions of blame for this pollution. Specifically, this study found that recreational boat owners disputed claims their sewage management practices posed an environmental threat arguing that the sewage discharged was readily and eagerly consumed by fish in the receiving environment. Boat owners also argued that increased levels of bacteria which indicate the presence of faeces within the marine environment could be directly attributed to the excrement of marine mammals and birds or were the result of dog faeces being washed through municipal storm water systems rather than the result of vessel discharges. By contrast the contamination of oysters was provided as evidence of sewage pollution by other stakeholders.

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Software development settings provide a great opportunity for CSCW researchers to study collaborative work. In this paper, we explore a specific work practice called bug reproduction that is a part of the software bug-fixing process. Bug re-production is a highly collaborative process by which software developers attempt to locally replicate the ‘environment’ within which a bug was originally encountered. Customers, who encounter bugs in their everyday use of systems, play an important role in bug reproduction as they provide useful information to developers, in the form of steps for reproduction, software screenshots, trace logs, and other ways to describe a problem. Bug reproduction, however, poses major hurdles in software maintenance as it is often challenging to replicate the contextual aspects that are at play at the customers’ end. To study the bug reproduction process from a human-centered perspective, we carried out an ethnographic study at a multinational engineering company. Using semi-structured interviews, a questionnaire and half-a-day observation of sixteen software developers working on different software maintenance projects, we studied bug reproduction. In this pa-per, we present a holistic view of bug reproduction practices from a real-world set-ting and discuss implications for designing tools to address the challenges developers face during bug reproduction.

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The objective of the research was to determine the optimal location and method of attachment for accelerometer-based motion sensors, and to validate their ability to differentiate rest and increases in speed in healthy dogs moving on a treadmill. Two accelerometers were placed on a harness between the scapulae of dogs with one in a pouch and one directly attached to the harness. Two additional accelerometers were placed (pouched and not pouched) ventrally on the dog's collar. Data were recorded in 1. s epochs with dogs moving in stages lasting 3. min each on a treadmill: (1) at rest, lateral recumbency, (2) treadmill at 0% slope, 3. km/h, (3) treadmill at 0% slope, 5. km/h, (4) treadmill at 0% slope, 7. km/h, (5) treadmill at 5% slope, 5. km/h, and; (6) treadmill at 5% slope, 7. km/h. Only the harness with the accelerometer in a pouch along the dorsal midline yielded statistically significant increases (P< 0.05) in vector magnitude as walking speed of the dogs increased (5-7. km/h) while on the treadmill. Statistically significant increases in vector magnitude were detected in the dogs as the walking speed increased from 5 to 7. km/h, however, changes in vector magnitude were not detected when activity intensity was increased as a result of walking up a 5% grade. Accelerometers are a valid and objective tool able to discriminate between and monitor different levels of activity in dogs in terms of speed of movement but not in energy expenditure that occurs with movement up hill.

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Purpose This paper describes the implementation and evaluation of an intervention aimed at increasing the dog-walking behaviour of residents from a community of approximately 60,000. This intervention was a sub strategy of the 10 000 Steps Rockhampton project – a community intervention aimed at decreasing sedentary behaviour in the adult population. Methods Brochures and posters were developed that promoted dog walking as a means to improve both human and canine health. The brochures were distributed by the local council to over 8 000 homes with the annual dog-renewal registrations. Results Evaluation of the intervention included a telephone survey of a randomly selected sample of Rockhampton residents (n=420) four-months post intervention. Although 63.6% of participants reported that owning a dog increased their physical activity levels, 40% of dog-owners did not walk their dog at all in the last week. The outcome evaluation of the intervention showed that 20.2% of dog-owners recalled receiving the brochure. Overall 15.3% of respondents with a dog in their household reported an increase in their physical activity levels since the intervention, 8.4% reported a decrease. Conclusions The intervention was an innovative and cost-effective way to tap into a section of the population that can benefit from engaging in regular walking behaviour. It was also a unique and useful way to engage local council in physical activity health promotion as part of a larger ongoing community-wide intervention.

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Genetic factors contribute to risk of many common diseases affecting reproduction and fertility. In recent years, methods for genome-wide association studies(GWAS) have revolutionized gene discovery forcommontraits and diseases. Results of GWAS are documented in the Catalog of Published Genome-Wide Association Studies at the National Human Genome Research Institute and report over 70 publications for 32 traits and diseases associated with reproduction. These include endometriosis, uterine fibroids, age at menarche and age at menopause. Results that pass appropriate stringent levels of significance are generally well replicated in independent studies. Examples of genetic variation affecting twinning rate, infertility, endometriosis and age at menarche demonstrate that the spectrum of disease-related variants for reproductive traits is similar to most other common diseases.GWAS 'hits' provide novel insights into biological pathways and the translational value of these studies lies in discovery of novel gene targets for biomarkers, drug development and greater understanding of environmental factors contributing to disease risk. Results also show that genetic data can help define sub-types of disease and co-morbidity with other traits and diseases. To date, many studies on reproductive traits have used relatively small samples. Future genetic marker studies in large samples with detailed phenotypic and clinical information will yield new insights into disease risk, disease classification and co-morbidity for many diseases associated with reproduction and infertility.

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In stark contrast to its horticultural origins, modern genetics is an extremely technology-driven field. Almost all the major advances in the field over the past 20 years have followed technological developments that have permitted change in study designs. The development of PCR in the 1980s led to RFLP mapping of monogenic diseases. The development of fluorescent-tagged genotyping methods led to linkage mapping approaches for common diseases that dominated the 1990s. The development of microarray SNP genotyping has led to the genome-wide association study era of the new millennium. And now the development of next-generation sequencing technologies is about to open up a new era of gene-mapping, enabling many potential new study designs. This review aims to present the strengths and weaknesses of the current approaches, and present some new ideas about gene-mapping approaches that are likely to advance our knowledge of the genes involved in heritable bone traits such as bone mineral density (BMD) and fracture.

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Background Today, finding an ideal biomaterial to treat the large bone defects, delayed unions and non-unions remains a challenge for orthopaedic surgeions and researchers. Several studies have been carried out on the subject of bone regeneration, each having its own advantages. The present study has been designed in vivo to evaluate the effects of cellular auto-transplantation of tail vertebrae on healing of experimental critical bone defect in a dog model. Methods Six indigenous breeds of dog with 32 ± 3.6 kg average weight from both sexes (5 males and 1 female) received bilateral critical-sized ulnar segmental defects. After determining the health condition, divided to 2 groups: The Group I were kept as control I (n = 1) while in Group II (experimental group; n = 5) bioactive bone implants were inserted. The defects were implanted with either autogeneic coccygeal bone grafts in dogs with 3-4 cm diaphyseal defects in the ulna. Defects were stabilized with internal plate fixation, and the control defects were not stabilized. Animals were euthanized at 16 weeks and analyzed by histopathology. Results Histological evaluation of this new bone at sixteen weeks postoperatively revealed primarily lamellar bone, with the formation of new cortices and normal-appearing marrow elements. And also reformation cortical compartment and reconstitution of marrow space were observed at the graft-host interface together with graft resorption and necrosis responses. Finally, our data were consistent with the osteoconducting function of the tail autograft. Conclusions Our results suggested that the tail vertebrae autograft seemed to be a new source of autogenous cortical bone in order to supporting segmental long bone defects in dogs. Furthermore, cellular autotransplantation was found to be a successful replacement for the tail vertebrae allograft bone at 3-4 cm segmental defects in the canine mid- ulna. Clinical application using graft expanders or bone autotransplantation should be used carefully and requires further investigation.

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Recolonisation and succession in a multi-species tropical seagrass meadow was examined by creating gaps (50×50 cm) in the meadow and manipulating the supply of sexual and asexual propagules. Measurements of leaf shoot density and estimates of above-ground biomass were conducted monthly to measure recovery of gaps between September 1995 and November 1997. Measurements of the seeds stored in the sediment (seed bank) and horizontal rhizome growth of colonising species were also conducted to determine their role in the recovery process. Asexual colonisation through horizontal rhizome growth from the surrounding meadow was the main mechanism for colonisation of gaps created in the meadow. The seed bank played no role in recolonisation of cleared plots. Total shoot density and above-ground biomass (all species pooled) of cleared plots recovered asexually to the level of the undisturbed controls in 10 and 7 months, respectively. There was some sexual recruitment into cleared plots where asexual colonisation was prevented but seagrass abundance (shoot density and biomass) did not reach the level of unmanipulated controls. Seagrass species did not appear to form seed banks despite some species being capable of producing long-lived seeds. The species composition of cleared plots remained different to the undisturbed controls throughout the 26-month experiment. Syringodium isoetifolium was a rapid asexual coloniser of disturbed plots and remained at higher abundances than in the control treatments for the duration of the study. S. isoetifolium had the fastest horizontal rhizome growth of species asexually colonising cleared plots (6.9 mm day−1). Halophila ovalis was the most successful sexual coloniser but was displaced by asexually colonising species. H. ovalis was the only species observed to produce fruits during the study. Small disturbances in the meadow led to long-term (>2 years) changes in community composition. This study demonstrated that succession in tropical seagrass communities was not a deterministic process. Variations in recovery observed for different tropical seagrass communities highlighted the importance of understanding life history characteristics of species within individual communities to effectively predict their response to disturbance. A reproductive strategy involving clonal growth and production of long-lived, locally dispersed seeds is suggested which may provide an evolutionary advantage to plants growing in tropical environments subject to temporally unpredictable major disturbances such as cyclones

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By quantifying the effects of climatic variability in the sheep grazing lands of north western and western Queensland, the key biological rates of mortality and reproduction can be predicted for sheep. These rates are essential components of a decision support package which can prove a useful management tool for producers, especially if they can easily obtain the necessary predictors. When the sub-models of the GRAZPLAN ruminant biology process model were re-parameterised from Queensland data along with an empirical equation predicting the probability of ewes mating added, the process model predicted the probability of pregnancy well (86% variation explained). Predicting mortality from GRAZPLAN was less successful but an empirical equation based on relative condition of the animal (a measure based on liveweight), pregnancy status and age explained 78% of the variation in mortalities. A crucial predictor in these models was liveweight which is not often recorded on producer properties. Empirical models based on climatic and pasture conditions estimated from the pasture production model GRASP, predicted marking and mortality rates for Mitchell grass (Astrebla sp.) pastures (81% and 63% of the variation explained). These prediction equations were tested against independent data from producer properties and the model successfully validated for Mitchell grass communities.

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Color displays used in image processing systems consist of a refresh memory buffer storing digital image data which are converted into analog signals to display an image by driving the primary color channels (red, green, and blue) of a color television monitor. The color cathode ray tube (CRT) of the monitor is unable to reproduce colors exactly due to phosphor limitations, exponential luminance response of the tube to the applied signal, and limitations imposed by the digital-to-analog conversion. In this paper we describe some computer simulation studies (using the U*V*W* color space) carried out to measure these reproduction errors. Further, a procedure to correct for color reproduction error due to the exponential luminance response (gamma) of the picture tube is proposed, using a video-lookup-table and a higher resolution digital-to-analog converter. It is found, on the basis of computer simulation studies, that the proposed gamma correction scheme is effective and robust with respect to variations in the assumed value of the gamma.