Embryonic development times of entomostracan zooplankton from Lake le Roux (Orange River, South Africa), and their possible relationships to seasonal succession

Hydrobiologia ◽  
1985 ◽  
Vol 127 (1) ◽  
pp. 17-26 ◽  
Author(s):  
R. C. Hart
Keyword(s):  
South Africa ◽  
Embryonic Development ◽  
Seasonal Succession ◽  
Development Times

Population Dynamics of Limnetic Cladocera in a Beaver Pond

1975 ◽  
Vol 32 (3) ◽  
pp. 341-346 ◽  
Author(s):  
Judith K. Kwik ◽  
John C. H. Carter
Keyword(s):  
Population Dynamics ◽  
Embryonic Development ◽  
Carrying Capacity ◽  
Sampling Errors ◽  
Beaver Pond ◽  
Bosmina Longirostris ◽  
Georgian Bay ◽  
Development Times ◽  
Different Temperatures ◽  
Ceriodaphnia Quadrangula

In a small, shallow, predation free beaver pond near Georgian Bay, Ontario Ceriodaphnia quadrangula was monacmic and Daphnia ambigua and Bosmina longirostris triacmic. Each species peaked and declined rapidly, presumably overshooting the carrying capacity of a food limited environment. Embryonic development times of each species at different temperatures was determined in the laboratory and fitted with Bĕlahrádek’s function. Calculated instantaneous rates of birth and death were normal for D. ambigua and C. quadrangula but too low to account for the rapid fluctuations in numbers of B. longirostris, suggesting occasional gross sampling errors. Bosmina longirostris may periodically abandon the limnoplankton for a benthic existence thus avoiding capture.

Temperature-dependent development in Pseudocalanus species

1989 ◽  
Vol 67 (3) ◽  
pp. 559-564 ◽  
Author(s):  
I. A. McLaren ◽  
J.-M. Sévigny ◽  
C. J. Corkett
Keyword(s):  
Embryonic Development ◽  
Residual Variance ◽  
Temperature Dependent ◽  
Species Ranges ◽  
Dependent Development ◽  
Development Times ◽  
Body Sizes ◽  
The Times ◽  
Environmental Temperatures

The duration of embryonic development and that of well-fed older stages were determined for Pseudocalanus acuspes, P. minutus, P. moultoni, and P. newmani. Excluding abnormal individuals, the times for older stages were lognormally distributed, with similar variances among species, stages, and temperatures. Some residual variance occurred among families reared together. Copepod rearings should take these sources of variance into account. Development times (D) were described well by Bělehrádek's temperature (T) function, D = a(T − α)−b, with b = 2.05 for all species from previous studies, and α and a fitted for embryonic development. Only a needed to be fitted for older stages (i.e., "equiproportional" development). Relative times to given stages at all temperatures (i.e., relative values of a) were similar in three species, but P. minutus deviated from this pattern. Values of α were directly related to presumed environmental temperatures in the species' ranges. Values of a were directly related to egg and body sizes of the different species. The temperature functions can be used to predict the lengths of the generations in these four species in nature when food is adequate.

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

Live Confocal Analysis of Fertilization and Early Development

2001 ◽  
Vol 7 (S2) ◽  
pp. 1012-1013
Author(s):  
Uyen Tram ◽  
William Sullivan
Keyword(s):  
Drosophila Melanogaster ◽  
Embryonic Development ◽  
Real Time ◽  
Early Development ◽  
Fluorescent Probes ◽  
Primary Defect ◽  
Fluorescent Analysis ◽  
Dynamic Event ◽  
Enormous Amount ◽  
Fluorescent Studies

Embryonic development is a dynamic event and is best studied in live animals in real time. Much of our knowledge of the early events of embryogenesis, however, comes from immunofluourescent analysis of fixed embryos. While these studies provide an enormous amount of information about the organization of different structures during development, they can give only a static glimpse of a very dynamic event. More recently real-time fluorescent studies of living embryos have become much more routine and have given new insights to how different structures and organelles (chromosomes, centrosomes, cytoskeleton, etc.) are coordinately regulated. This is in large part due to the development of commercially available fluorescent probes, GFP technology, and newly developed sensitive fluorescent microscopes. For example, live confocal fluorescent analysis proved essential in determining the primary defect in mutations that disrupt early nuclear divisions in Drosophila melanogaster. For organisms in which GPF transgenics is not available, fluorescent probes that label DNA, microtubules, and actin are available for microinjection.

Combining Professional Interests and Travel: People to People Citizen Ambassador Program

2011 ◽  
Vol 1 (2) ◽  
pp. 47-54
Author(s):  
Alex Johnson ◽  
Amanda Hitchins
Keyword(s):  
South Africa ◽  
Health Education ◽  
Communication Disorders ◽  
Social Conditions ◽  
Speech Language Pathologists ◽  
Exchange Program

Abstract This article summarizes a series of trips sponsored by People to People, a professional exchange program. The trips described in this report were led by the first author of this article and include trips to South Africa, Russia, Vietnam and Cambodia, and Israel. Each of these trips included delegations of 25 to 50 speech-language pathologists and audiologists who participated in professional visits to learn of the health, education, and social conditions in each country. Additionally, opportunities to meet with communication disorders professionals, students, and persons with speech, language, or hearing disabilities were included. People to People, partnered with the American Speech-Language-Hearing Association (ASHA), provides a meaningful and interesting way to learn and travel with colleagues.

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