Open AccessJournal Article
ON THE STUDY TO THE LIFE-CYCLE OF A RARE "KOUGAIBIRU" : BIPALIUM PENNSYLVANICUM : Behavior Biology and Ecology
N. Makino,Y. Shirasawa +1 more
TLDR
It seems that conjugation occurred from April to June in the Mikumarikyo stream and from May toJune in the Momijidani-gawa stream, so that sexual reproduction probably occurred near the peak of the population density.Abstract:
ABSTRACT. Studies were completed on the natural population density of Paramecium bursaria syngen 1 and on the life cycle stages to which the individuals belonged. Green paramecia were collected from two streams once every 20 days for over one year: 413 individuals on 26 collection dates in Mikumarikyo stream and 83 individuals on 23 collection dates in Momijidani-gawa stream. Individuals in nature did not maintain at a steady density but fluctuated greatly depending on the month. It seems that conjugation occurred from April to June in the Mikumarikyo stream and from May to June in the Momijidani-gawa stream. The appearance of individuals with mating ability might be related closely to increasing population so that sexual reproduction probably occurred near the peak of the population density. The 413 individuals from Mikumarikyo stream were examined to determine their position within the life cycle; 309 (74%) were immature, 55 (13%) were adolescent, and 49 (12%) were mature. No senile individuals were observed. The fraction of individuals with mating ability was generally less than 30% at any collection. Four mating types were observed occurring with about equal frequencies in mature individuals. The results show the frequencies of the recessive genes for mating types (a and b) are higher than for dominant genes (A and B). Of 83 individuals from Momijidani-gawa stream, 44 (52%) were immature, 21 (25%) were adolescent, and 18 (21%) were mature. Again, no senile individuals were observed. Because only two mating types were found, II and III (genotypes aaB- and aabb), it seems possible that the dominant gene A was rare or absent in the Momijidani-gawa population.read more
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Distribution of mating type alleles in the wheat pathogen Mycosphaerella graminicola over spatial scales from lesions to continents.
TL;DR: Though the absolute frequencies of the two mating types sometimes varied for different sampling units within the same spatial scale in the hierarchy, none of the differences were statistically significant from the null hypothesis of equal frequencies for theTwo mating types.
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Sergio L. Vargas,Carolina A. Ponce,Walter T. Hughes,Ann E. Wakefield,Weitz Jc,Sergio Donoso,Ana V. Ulloa,Patricio Madrid,Stephen J. Gould,Juan J. Latorre,Ricardo Avila,Samuel Benveniste,Miriam Gallo,José Belletti,René Lopez +14 more
TL;DR: JoseBelletti et al. as discussed by the authors provided histological evidence that primary pneumocystis carinii infection is associated with sudden infant death syndrome (SIDS) in 161 additional SIDS cases, 47 (35.1%) of 134 infants from Chile and 4 (14.8%) of 27 infants from Oxford, United Kingdom.
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Sex in Ciliates
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TL;DR: The existence of genetic variety affecting phenotype represents the presupposition for selection to operate and then for evolution to accomplish.
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Ecological Genetics of Tetrahymena thermophila: Mating Types, i-Antigens, Multiple Alleles and Epistasis
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TL;DR: Crosses among whole‐genome homozygotes derived from Pennsylvania isolates reveal a spectrum genotypes with mating type alleles resembling traditional A (IV‐ and VII‐) and B(I‐) categories and numerous variants of the cell surface immobilization antigen are found in addition to the previously described i‐antigens, suggesting that i‐ag play an important, but as yet unknown, ecological role related to the occurrence of frequent conjugation.
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References
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Journal ArticleDOI
The ecology of marine microbenthos IV. Structure and function of the benthic ecosystem, its chemical and physical factors and the microfauna commuities with special reference to the ciliated protozoa
TL;DR: It is demonstrated that the microfaunal communities can be correlated with the oxidation-reduction properties of sediments and with their mechanical composition and that the endproducts of anaerobic decomposition are of large trophic significance to the sediment ecosystem through the activity of cherno- and photoautotrophic bacteria.
Journal ArticleDOI
Distribution of mating type alleles in the wheat pathogen Mycosphaerella graminicola over spatial scales from lesions to continents.
TL;DR: Though the absolute frequencies of the two mating types sometimes varied for different sampling units within the same spatial scale in the hierarchy, none of the differences were statistically significant from the null hypothesis of equal frequencies for theTwo mating types.
Journal ArticleDOI
Association of Primary Pneumocystis carinii Infection and Sudden Infant Death Syndrome
Sergio L. Vargas,Carolina A. Ponce,Walter T. Hughes,Ann E. Wakefield,Weitz Jc,Sergio Donoso,Ana V. Ulloa,Patricio Madrid,Stephen J. Gould,Juan J. Latorre,Ricardo Avila,Samuel Benveniste,Miriam Gallo,José Belletti,René Lopez +14 more
TL;DR: JoseBelletti et al. as discussed by the authors provided histological evidence that primary pneumocystis carinii infection is associated with sudden infant death syndrome (SIDS) in 161 additional SIDS cases, 47 (35.1%) of 134 infants from Chile and 4 (14.8%) of 27 infants from Oxford, United Kingdom.
Book ChapterDOI
Sex in Ciliates
Fernando Dini,Dennis Nyberg +1 more
TL;DR: The existence of genetic variety affecting phenotype represents the presupposition for selection to operate and then for evolution to accomplish.
Journal ArticleDOI
The genic control of mating types in paramecium bursaria
Richard W. Siegel,L. L. Larison +1 more
TL;DR: It is demonstrated that the four complementary mating types long recognized for variety 1 are determined by specific combinations of complementary genes at two unlinked loci, which supports the two-gene hypothesis without ambiguity.