Platyhelminths from the South African Clawed Toad, or Platanna (Xenopus laevis)

1973 ◽  
Vol 47 (2) ◽  
pp. 199-235 ◽  
Author(s):  
William Macnae ◽  
Liebe Rock ◽  
Matthew Makowski
Keyword(s):  
Xenopus Laevis ◽  
South African ◽  
Large Scale ◽  
Developmental Stages ◽  
First Year ◽  
Pericardial Cavity ◽  
Large Numbers ◽  
South African Universities ◽  
In Captivity ◽  
Large Scale Survey

Since the discovery by Shapiro and Zwarenstein (1934) that females of Xenopus laevis (Daudin, 1802) respond to hormones present in the urine of pregnant women, this species of amphibian has proved to be a useful experimental animal. It is easily kept in captivity and can be reared through all its developmental stages without difficulty.This species, the clawed toad or platanna, is commonly used in South African Universities as a type for first year dissection. This has given the opportunity to check large numbers of specimens for the more obvious parasites, i.e. those which live in the gallbladder, the urinary bladder, the peritoneal cavity and the pericardial cavity. A similar large scale survey of intraintestinal parasites has not been feasible, although many alimentary canals have been searched for parasites.

scholarly journals Evaluation of Effective and Practical Euthanasia Methods for Larval African Clawed Frogs (Xenopus laevis)

2020 ◽  
Vol 59 (3) ◽  
pp. 269-274
Author(s):  
Ilana A Galex ◽  
Cameron M Gallant ◽  
Nicole D'Avignon ◽  
Lauren M Kuchenbrod ◽  
Craig A Fletcher ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Developmental Stages ◽  
Age Group ◽  
Research Model ◽  
Larval Stages ◽  
Large Numbers ◽  
Guidance Documents ◽  
Stock Solutions ◽  
Tricaine Methanesulfonate ◽  
Tank Water

Larval, or tadpole-stage Xenopus laevis frogs are a popular research model for developmental biology and disease studies. Existing euthanasia guidance documents offer recommendations for both eggs and adult stages, yet do not specifically address the larval stage. Data evaluating effective euthanasia methods for groups of X. laevis tadpoles would therefore be useful. The goal of the current study was to evaluate the efficacy of various immersion euthanasia procedures on tadpoles: tricaine methanesulfonate (MS222) at 6 g/L, eugenol at 800 μL/L and rapid chilling (2 to 4 °C). We also evaluated tadpoles at various developmental stages (NF stages 46, 47 and 49). Tadpoles (n = 70) were exposed to euthanasia solution for 15 min, and controls (n = 40) were placed in housing tank water for 15 min. All animals were then placed in recovery tanks containing housing tank water for 4 h to confirm irreversibility of each agent. Cessation of the heartbeat was assessed at the end of euthanasia solution exposure and at each hour thereafter. We found that immersion in a 6 g/L solution of MS222 resulted in 100% euthanasia of all larval stages tested. Conversely, eugenol produced variable euthanasia rates that were affected by both age group and batches of stock solutions. Rapid chilling was completely ineffective as a euthanasia method in our study. Based on our findings, we recommend MS222 as an effective and practical means of euthanizing large numbers of X. laevis tadpoles.

scholarly journals Human Immunodeficiency Virus Infection Is Associated With Increased Meningococcal Carriage Acquisition Among First-year Students in 2 South African Universities

2020 ◽  
Author(s):  
Susan Meiring ◽  
Cheryl Cohen ◽  
Linda de Gouveia ◽  
Mignon du Plessis ◽  
Karistha Ganesh ◽  
...  
Keyword(s):  
Risk Factors ◽  
University Students ◽  
South African ◽  
Relative Risk Ratio ◽  
First Year ◽  
Adjusted Relative Risk ◽  
Vaccination Programs ◽  
South African Universities ◽  
First Year University ◽  
Carriage Prevalence

Abstract Background Invasive meningococcal disease clusters occur among university students and may reflect higher carriage prevalence among this population. We aimed to measure meningococcal carriage prevalence, acquisition, and risk factors among first-year university students in South Africa. Methods In summer–autumn 2017, after consenting to participate, we collected oropharyngeal swabs and questionnaires on carriage risk factors and tested students for HIV at 2 universities, during registration week (survey 1) and 6–8 weeks later (survey 2). Meningococci were detected by culture and polymerase chain reaction. Results We enrolled 2120 students at registration. Mean age was 18.5 years, 59% (1252/2120) were female and 0.8% (16/1984) had HIV. Seventy-eight percent of students returned for survey 2 (1655/2120). Among the cohort, carriage prevalence was 4.7% (77/1655) at registration, increasing to 7.9% (130/1655) at survey 2: 5.0% (83) acquired new carriage, 2.8% (47) had persistent carriage, 1.8% (30) cleared the initial carriage, and 90.3% (1495) remained carriage free. At both surveys, nongenogroupable meningococci predominated, followed by genogroups Y, B, W, and C. On multinomial analysis, risk factors for carriage acquisition included attending nightclubs (adjusted relative risk ratio [aRRR], 2.1; 95% CI, 1.1–4.0), having intimate kissing partners (aRRR, 1.8; 95% CI, 1.1–2.9) and HIV (aRRR, 5.0; 95% CI, 1.1–24.4). Conclusions Meningococcal carriage among first-year university students increased after 2 months. Sociobehavioral risk factors were associated with increased carriage for all analyses. HIV was associated with carriage acquisition. Until vaccination programs become mandatory in South African universities, data suggest that students with HIV could benefit most from meningococcal vaccination.

Volunteer Science

2016 ◽  
Vol 79 (4) ◽  
pp. 376-396 ◽  
Author(s):  
Jason Radford ◽  
Andy Pilny ◽  
Ashley Reichelmann ◽  
Brian Keegan ◽  
Brooke Foucault Welles ◽  
...  
Keyword(s):  
Large Scale ◽  
Effective Means ◽  
Cost Effective ◽  
Social Psychological ◽  
Timely Manner ◽  
Online Laboratory ◽  
Large Numbers ◽  
Large Scale Survey ◽  
Online Methods ◽  
Psychological Experiments

Experimental research in traditional laboratories comes at a significant logistic and financial cost while drawing data from demographically narrow populations. The growth of online methods of research has resulted in effective means for social psychologists to collect large-scale survey-based data in a cost-effective and timely manner. However, the same advancement has not occurred for social psychologists who rely on experimentation as their primary method of data collection. The aim of this article is to provide an overview of one online laboratory for conducting experiments, Volunteer Science, and report the results of six studies that test canonical behaviors commonly captured in social psychological experiments. Our results show that the online laboratory is capable of performing a variety of studies with large numbers of diverse volunteers. We advocate for the use of the online laboratory as a valid and cost-effective way to perform social psychological experiments with large numbers of diverse subjects.

scholarly journals To Save Lives: The Ethical Precedent set by South Africa’s Leadership during Lockdown

Phronimon ◽  
2021 ◽  
Vol 21 ◽  
Author(s):  
David Anthony Pittaway
Keyword(s):  
South Africa ◽  
South African ◽  
Precautionary Principle ◽  
Large Scale ◽  
Epidemiological Data ◽  
Decision Making Process ◽  
Government Interventions ◽  
The Precautionary Principle ◽  
Large Numbers

None of the lockdown decisions made by governments in response to the Covid-19 pandemic can be considered to be self-evident outcomes of objective data. Executive members of each nation’s government considered the particular pandemic circumstances that they deemed to be important and relevant, and decisions were made based on limited epidemiological data in combination with a variety of contingent socio-political and economic variables. These kinds of decisions fall partly into the philosophical category of ethics, and they can be summarised under the umbrella question: What should we do? The precautionary principle must have played a large role in the decision-making process, considering the conspicuous lack of reliable data on which to base decisions. In this article, I turn to South Africa as a case study, and I tease out some of the precautionary factors that may have, in part, driven many major decisions prior to and during the South African lockdown. I argue that if the precautionary principle can be used as part of the justification for large-scale government interventions to save an unknown number of lives, then consistent use of the principle should warrant concerted responses by government to a variety of potential threats and problems in South Africa. I also argue that for government’s focus on saving lives to be consistent, preventative action in response to phenomena that take worryingly large numbers of lives annually, is necessary.

The Workhouse Populations of Lancashire in 1881

2011 ◽  
pp. 37-65
Author(s):  
Andy Gritt ◽  
Peter Park
Keyword(s):  
Large Scale ◽  
Poor Law ◽  
Industrial Region ◽  
Large Numbers ◽  
Elderly Males ◽  
Working Age ◽  
Local Relief ◽  
Large Scale Survey

This article investigates the characteristics of the workhouse populations in Lancashire in 1881. The analysis is based on the snapshot view provided by the 1881 census and, despite the limitations of such an approach, this large-scale survey reveals significant variations in the experience of poverty and local relief policies in a largely industrial region that had been at the forefront of the anti-poor law movement. The workhouse populations are shown to be diverse, and contrast markedly with pauper populations previously studied. Lancashire's Poor Law Unions are divided into three types: conurbation, urban industrial and rural. These three groups appear to represent three different patterns of workhouse residency. The workhouse populations in rural Lancashire are broadly similar to those discussed elsewhere, being dominated by elderly males. However, urban industrial workhouse populations contained large numbers of adults of working age and the absence of children from workhouses in the conurbation is particularly striking.

scholarly journals The Effect of Captivity upon the Reproductive Cycle of the South African Clawed Toad (Xenopus laevis)

1935 ◽  
Vol 12 (4) ◽  
pp. 306-314
Author(s):  
S. S. ALEXANDER ◽  
C. W. BELLERBY
Keyword(s):  
Xenopus Laevis ◽  
South African ◽  
Reproductive Cycle ◽  
Food Supply ◽  
Cape Town ◽  
The South ◽  
Natural Conditions ◽  
Ovarian Growth ◽  
In Captivity ◽  
Developmental Condition

1. The South African clawed toad (Xenopus laevis) can be maintained in captivity in a healthy condition provided that it is adequately fed. 2. No atrophic changes are found to occur in the ovary as reported by Zwarenstein and Shapiro for animals kept in captivity in Cape Town. 3. The developmental condition of the ovary depends directly upon the amount of food available. 4. The normal periods of ovarian growth and retrogression which occur in the toad under natural conditions can be explained on the basis of fluctuation in food supply.

Towards learning dialogues as data: researching children's lifeworlds in global cities

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nicola Yelland ◽  
Clare Bartholomaeus
Keyword(s):  
Design Methodology ◽  
Qualitative Method ◽  
Large Scale ◽  
The Other ◽  
After School ◽  
Main Study ◽  
Content Type ◽  
Rights Of The Child ◽  
Large Numbers ◽  
Large Scale Survey

PurposeThe purpose of this article is to contribute to the research methodology literature that arose out of the (new) sociology of childhood and the UN Convention of the Rights of the Child (1989) with regard to conducting ethical research with children rather than on children. In particular, this article reflects on the development of a method (learning dialogues).Design/methodology/approachLearning dialogues were designed to enable children to share their responses to prompts about specific aspects of their lifeworlds. This was one method used to produce the data corpus which also included a large-scale survey, classroom ethnographies and (video) re-enactments of children's lives after school.FindingsThe piloting of the learning dialogues took place in several iterations and a particular form was used for the main study. The original idea and development of the learning dialogues highlights they were both a rich source of data that complemented the other data sources in the study and an activity that children indicated that they enjoyed. The authors discuss the practicalities involved with adapting a qualitative method to different settings and to projects with large numbers of children.Originality/valueThe conceptualisation of the learning dialogues as sources of personal documentation about aspects of children's lifeworlds was unique to this research. In thinking about the learning dialogues as one source of data within a broader project, the research aimed to be more inclusive of all participants in contributing to the findings produced in the project.

Predicting patterns of persistence at a South African university: a decision tree approach

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Vino Paideya ◽  
Annah V. Bengesai
Keyword(s):  
Data Mining ◽  
Decision Tree ◽  
South African ◽  
Large Scale ◽  
Classification Tree ◽  
First Year ◽  
Content Type ◽  
Factors Associated ◽  
Chemistry Major ◽  
Factors Influencing

PurposeThe emerging field of educational data mining provides an opportunity to process large-scale data emerging from higher education institutions (HEIs) into reliable knowledge. The purpose of this paper is to examine factors influencing persistence amongst students enrolled in a Chemistry major at a South African university using enrolment data.Design/methodology/approachThe sample consisted of 511 students registered for a Chemistry major beginning in 2012, 2013 and 2014. Descriptive statistics in counts and percentages and classification (decision) tree methods were used in the analysis.FindingsGraduation from the Chemistry major is likely to occur after 4 years, which is regulation time plus 1 year, whilst departure mainly occurs in the first year of study. Classification tree modelling demonstrated that first year accumulated credits (FYAC), gender, financial aid status and school quintile were the factors associated with persistence. FYAC was the most critical factor.Research limitations/implicationsAlthough this study has many strengths, significantly the use of data mining methods to classify students, some limitations might affect how the results are interpreted. First, the analysis focused on a one-degree major in one institution, which leads to the suspicion that the observed results are discipline or institution-specific. Thus, the findings cannot be generalised to other contexts or disciplines. Second, with so many potential factors influencing student persistence, the analysis presented in this paper, which was limited to the covariates obtained in the institutional dataset the authors used, is by no means exhaustive. There is the possibility that some factors, which are not included in the present analysis, might have more predictive power.Originality/valueGlobally, university administrators are interested in predicting student outcomes and understanding the intricate balance between enrolment and throughput. Thus, whilst the findings from this study have an institutional focus, they resonate with other HEIs and present an alternative and highly visual way of identifying specific combinations of factors associated with persistence. The results from a classification tree model can also classify students at risk and inform the development of interventions that will support them.

scholarly journals News You Can Use

10.28945/3241 ◽  
2008 ◽  
Author(s):  
Kevin Allan Johnston ◽  
Susan Benvenuti
Keyword(s):  
Detailed Analysis ◽  
South African ◽  
Research Study ◽  
Lessons Learned ◽  
First Year ◽  
Large Classes ◽  
Assessment Tasks ◽  
South African Universities ◽  
Career Skills ◽  
Successes And Challenges

It is widely accepted that assessment determines learning: what is learnt, how the learning takes place, the extent to which the learning is retained, and the extent to which that learning can be further developed or applied (Biggs, 2003; Boud, Cohen, & Sampson, 1999; Entwistle & Entwistle, 1997; Rowntree, 1992). This paper examines an assessment intervention undertaken independently by two South African Universities in their first year Information Systems Courses, aimed at improving both the learning of content and the development of academic and career skills, within the constraints of curriculum, large classes and under-preparedness of students. Departing from a similar concept, the two universities designed and implemented the assessment tasks independently, with each experiencing different successes and challenges. Representing a first cycle in an Action Research study, the underlying rationale behind the interventions is presented, together with a detailed analysis of the two case studies and their shared lessons learned from the experience.

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