STUDIES ON PLAQUE VARIANTS OF COXSACKIEVIRUS B5 BY BURST ANALYSES

1967 ◽  
Vol 13 (2) ◽  
pp. 167-172
Author(s):  
Jack Konowalchuk ◽  
Joan I. Speirs
Keyword(s):  
Cell Lines ◽  
Large Population ◽  
Small Population ◽  
Monkey Kidney ◽  
Large Plaque ◽  
Parent Culture ◽  
Normal Monkey ◽  
Small Pool ◽  
Selection For ◽  
Section Analysis

Propagation of coxsackievirus B5 on cell lines revealed two variants, one that yields small plaques and is stable and another that is large but variable in size. Multiple-burst studies on the large-plaque pool showed the existence of two different population sections. Analysis of a sample from a plaque belonging to the small population section showed a progeny of small plaques while a similar analysis from a plaque in the large population section produced plaques of varying size but whose mean plaque diameter resembled that of the parent culture. Repeated selection for smallness from plaques in the large population section resulted in small plaques and a shift from the large to the small population section. Analysis of the small pool virus on monkey kidney monolayers revealed the presence of a few typical monkey kidney plaques which differed from normal monkey kidney plaques by producing only small plaques on HEp-2 monolayers.

Derivation of Haploid Neural Stem Cell Lines by Selection for a Pax6-GFP Reporter

2018 ◽  
Vol 27 (7) ◽  
pp. 479-487 ◽  
Author(s):  
Qian Gao ◽  
Wenhao Zhang ◽  
Lifang Ma ◽  
Xu Li ◽  
Haisong Wang ◽  
...  
Keyword(s):  
Stem Cell ◽  
Neural Stem Cell ◽  
Cell Lines ◽  
Gfp Reporter ◽  
Selection For ◽  
Stem Cell Lines

scholarly journals Choosing Mutation and Crossover Ratios for Genetic Algorithms—A Review with a New Dynamic Approach

Information ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 390 ◽  
Author(s):  
Ahmad Hassanat ◽  
Khalid Almohammadi ◽  
Esra’a Alkafaween ◽  
Eman Abunawas ◽  
Awni Hammouri ◽  
...  
Keyword(s):  
Population Size ◽  
Optimization Problems ◽  
Large Population ◽  
Small Population ◽  
Mutation Rates ◽  
Mutation Operators ◽  
Tuning Methods ◽  
Two Parameters ◽  
The Impact ◽  
Crossover And Mutation

Genetic algorithm (GA) is an artificial intelligence search method that uses the process of evolution and natural selection theory and is under the umbrella of evolutionary computing algorithm. It is an efficient tool for solving optimization problems. Integration among (GA) parameters is vital for successful (GA) search. Such parameters include mutation and crossover rates in addition to population that are important issues in (GA). However, each operator of GA has a special and different influence. The impact of these factors is influenced by their probabilities; it is difficult to predefine specific ratios for each parameter, particularly, mutation and crossover operators. This paper reviews various methods for choosing mutation and crossover ratios in GAs. Next, we define new deterministic control approaches for crossover and mutation rates, namely Dynamic Decreasing of high mutation ratio/dynamic increasing of low crossover ratio (DHM/ILC), and Dynamic Increasing of Low Mutation/Dynamic Decreasing of High Crossover (ILM/DHC). The dynamic nature of the proposed methods allows the ratios of both crossover and mutation operators to be changed linearly during the search progress, where (DHM/ILC) starts with 100% ratio for mutations, and 0% for crossovers. Both mutation and crossover ratios start to decrease and increase, respectively. By the end of the search process, the ratios will be 0% for mutations and 100% for crossovers. (ILM/DHC) worked the same but the other way around. The proposed approach was compared with two parameters tuning methods (predefined), namely fifty-fifty crossover/mutation ratios, and the most common approach that uses static ratios such as (0.03) mutation rates and (0.9) crossover rates. The experiments were conducted on ten Traveling Salesman Problems (TSP). The experiments showed the effectiveness of the proposed (DHM/ILC) when dealing with small population size, while the proposed (ILM/DHC) was found to be more effective when using large population size. In fact, both proposed dynamic methods outperformed the predefined methods compared in most cases tested.

Anisakine Nematodes in Fresh Commercial Fish From Waters Along the Washington, Oregon and California Coasts

1979 ◽  
Vol 42 (5) ◽  
pp. 380-384 ◽  
Author(s):  
BETTY JUNE MYERS
Keyword(s):  
Definitive Host ◽  
Lower Incidence ◽  
Large Population ◽  
Small Population ◽  
Marine Fisheries ◽  
Commercial Fish ◽  
Fresh Fish ◽  
Fish Hosts

Two thousand and seventy four fresh fish representing 24 genera and 43 species were purchased from commercial marine fisheries in Washington, Oregon and California. They were examined for anisakine nematodes by dissection, candling or digestion of the muscle and elution of the viscera. Thirty thousand and thirty-two anisakine nematodes were recovered from the fish examined; however, no anisakine nematodes were recovered from the shellfish examined. Both Anisakis sp. and Phocanema sp., which are considered pathogens for human consumers of raw or semiraw fish, were encountered. Of the anisakines. Anisakis sp. larvae were found in a greater number of the fish hosts examined than Phocanema sp. larvae, which were found in fewer fish hosts and at lower incidence. The higher incidence of Anisakis sp. larvae was probably due to the large population of whales, the host in which this species reaches maturity. The lower incidence of Phocanema sp. larvae is a reflection of the small population of seals, the definitive host for this species.

scholarly journals The effects of inbreeding and artificial selection on reproductive fitness

1962 ◽  
Vol 3 (1) ◽  
pp. 110-138 ◽  
Author(s):  
B. D. H. Latter ◽  
Alan Robertson
Keyword(s):  
Artificial Selection ◽  
Large Population ◽  
Theoretical Models ◽  
Base Population ◽  
Selected Lines ◽  
Index Method ◽  
Competitive Index ◽  
Sib Mating ◽  
Selection For ◽  
Rate Of Decline

The competitive-index method of measurement of over all fitness in Drosophila has been used to measure the effect of inbreeding and of artificial selection for metric characters in a large population of Drosophila melanogaster. The technique itself was examined in detail with particular reference to its repeatability and to the effect on it of the modification of various environmental variables.With continued full-sib mating the decline in the competitive index was very rapid (it was reduced to a half by a single generation of full-sib mating) and there were no indications that interactions between deleterious genes at different loci were important in determining the rate of decline of fitness as inbreeding increased. Other unselected lines with ten pairs of parents in each generation were carried to serve as a control for the lines under artificial selection. At the same theoretical degree of inbreeding the control lines had a much higher average fitness than the lines produced by continued full-sib mating.From the base population lines were selected in both directions for abdominal bristles, sternopleural bristles and for wing length, there being two replicates in all cases. Four control lines were kept with the same number of parents as the selected lines. In all cases the selected lines declined in fitness below the value for the base population. However, in three of the lines the fitness was not significantly below the value for the control lines. The effect of artificial selection on fitness was asymmetrical, the decline being greater with down selection for all characters.The relevance of these results to various theoretical models is discussed. If the variation in these characters is actively maintained in the base population by the selection of heterozygotes then the results are consistent with an average selection disadvantage of homozygotes relative to heterozygotes of about 0·5%.

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