Genetics of growth rate variation in bivalves: aneuploidy and heterozygosity effects in a Crassostrea gigas family

Genome ◽  
1992 ◽  
Vol 35 (1) ◽  
pp. 39-45 ◽  
Author(s):  
C. Thiriot-Quiévreux ◽  
G. H. Pogson ◽  
E. Zouros
Keyword(s):  
Growth Rate ◽  
Shell Length ◽  
Chromosome Complement ◽  
Significant Negative Correlation ◽  
Rate Variation ◽  
Chromosome Loss ◽  
The Pacific ◽  
Marine Bivalves ◽  
Two Factors ◽  
Allozyme Loci

Enzyme homozygosity and somatic aneuploidy are both known to adversely affect juvenile growth rate in marine bivalves. We have examined the joint effects of these two factors by scoring genotypes at nine segregating allozyme loci and counting the numbers of chromosomes lost in 30 cells in each of 83 full sibs of the Pacific oyster. A highly significant negative correlation was observed between the number of chromosomes missing and shell length in full sibs of the same age. No relationship was seen, however, between allozyme heterozygosity and either shell length or chromosome loss, nor was there any difference in the distribution of aneuploidy among genotypes at any given enzyme locus. Thus, the effects of homozygosity and aneuploidy on growth rate appear to have different genetic bases. Even in the most aneuploid oysters, more than half the cells examined had a complete chromosome complement of 2n = 20. This eliminates somatic aneuploidy as an explanation for the excess of enzyme homozygosity frequently observed in populations of marine molluscs. Significant deviations from Mendelian expectations, favoring homozygotes at some loci and heterozygotes at others, were recorded at eight of the nine allozyme loci, but these occurred independently of the aneuploidy observed. Our results suggest that within families a much larger component of variation in growth rate is due to aneuploidy than to allozyme genotype, but this conclusion cannot, at present, be extended to natural populations.Key words: aneuploidy, heterozygosity, growth rate, oysters.

scholarly journals Allozyme and RFLP heterozygosities as correlates of growth rate in the scallop Placopecten magellanicus: a test of the associative overdominance hypothesis.

Genetics ◽  
1994 ◽  
Vol 137 (1) ◽  
pp. 221-231 ◽  
Author(s):  
G H Pogson ◽  
E Zouros
Keyword(s):  
Growth Rate ◽  
Placopecten Magellanicus ◽  
Functional Differences ◽  
Enzyme Loci ◽  
Length Polymorphisms ◽  
Marine Bivalves ◽  
Causative Agents ◽  
Recessive Genes ◽  
Positive Correlations ◽  
Allozyme Loci

Abstract Several studies have reported positive correlations between the degree of enzyme heterozygosity and fitness-related traits. Notable among these are the correlations between heterozygosity and growth rate in marine bivalves. Whether the correlation is the result of intrinsic functional differences between enzyme variants at the electrophoretic loci scored or arises from non-random genotypic associations between these loci and others segregating for deleterious recessive genes (the associative overdominance hypothesis) is a matter of continuing debate. A prediction of the associative overdominance hypothesis, not shared by explanations that treat the enzyme loci as causative agents of the correlation, is that the correlation is not specific to the type of genetic marker used. We have tested this prediction by scoring heterozygosity at single locus nuclear restriction fragment length polymorphisms (RFLPs) in a cohort of juvenile scallops (Placopecten magellanicus) in which growth rate was known to be positively correlated with an individual's degree of allozyme heterozygosity. A total of 222 individuals were scored for their genotypes at seven allozyme loci, two nonspecific protein loci of unknown function and eight nuclear RFLPs detected by anonymous cDNA probes. In contrast to the enzyme loci, no correlation was observed between growth rate and the degree of heterozygosity at the DNA markers. Furthermore, there was no relationship between the magnitude of heterozygote deficiency at a locus and its effect on the correlation. The differences observed between the effects of allozyme and RFLP heterozygosity on growth rate provide evidence against the associative overdominance hypothesis, but a strong case against this explanation must await corroboration from similar studies in different species.

scholarly journals Evidence of differential chromosome loss in aneuploid karyotypes of the Pacific oyster, Crassostrea gigas

Genome ◽  
2001 ◽  
Vol 44 (4) ◽  
pp. 735-737 ◽  
Author(s):  
A Leitão ◽  
P Boudry ◽  
C Thiriot-Quiévreux
Keyword(s):  
Growth Rate ◽  
Negative Correlation ◽  
Crassostrea Gigas ◽  
Homologous Chromosome ◽  
Pacific Oyster ◽  
Gill Tissue ◽  
Banding Technique ◽  
Chromosome Loss ◽  
The Pacific ◽  
Different Populations

The G-banding technique was performed on aneuploid karyotypes from gill tissue of the Pacific oyster, Crassostrea gigas, to assess whether chromosome losses could be explained by differential chromosomal susceptibility and to clarify the negative correlation between aneuploidy and growth rate previously reported in different populations of this oyster. The study of 95 G-banded aneuploid karyotypes showed that only 4 of the 10 chromosome pairs (viz. 1, 5, 9, and 10) of C. gigas were affected by the loss of one homologous chromosome. Pairs 1, 9, and 10, which were lost in 56, 33, and 44% of cases, respectively, may be considered to be differentially affected. Hypotheses on this differential chromosomal susceptibility are discussed.Key words: aneuploidy, growth, G-banding, karyotype, oyster.

scholarly journals The negative correlation between somatic aneuploidy and growth in the oyster Crassostrea gigas and implications for the effects of induced polyploidization

1996 ◽  
Vol 68 (2) ◽  
pp. 109-116 ◽  
Author(s):  
E. Zouros ◽  
C. Thiriot-Quievreux ◽  
G. Kotoulas
Keyword(s):  
Growth Rate ◽  
Negative Correlation ◽  
Crassostrea Gigas ◽  
Inverse Relationship ◽  
Pacific Oyster ◽  
Chromosome Loss ◽  
Consistent Effect ◽  
The Pacific ◽  
Polyploid Cells ◽  
Recessive Genes

SummaryThis study extends previous observations that chromosome loss in somaticcells of juveniles of the pacific oyster Crassostrea gigas is associated with reduced growth rate. All four studies designed to examine this association (two usingrandom population samples and two using full sibs) produced the same result. This consistent effect appears to be unrelated with the commonly, but not consistently, observed correlation between degree of allozyme heterozygosity and growth. We propose thatthe inverse relationship between aneuploidy and growth is due to the unmasking of deleterious recessive genes caused by ‘progressive haploidization’ of somatic cells. Because unmasking of deleterious recessive genes by random chromosome lossisunlikely in polyploid cells, this hypothesis may also provide an explanation for theobservation that artificially produced polyploid shellfish usually grow at faster rates than normal diploid ones.

ФОРМИРОВАНИЕ ПЕРЕХОДНОГО СЛОЯ ALN НА ТЕМПЛЕЙТАХ 3С-SIC/SI(111) МЕТОДОМ АММИАЧНОЙ МОЛЕКУЛЯРНО-ЛУЧЕВОЙ ЭПИТАКСИИ

2020 ◽  
Vol 96 (3s) ◽  
pp. 148-153
Author(s):  
С.Д. Федотов ◽  
А.В. Бабаев ◽  
В.Н. Стаценко ◽  
К.А. Царик ◽  
В.К. Неволин
Keyword(s):  
Crystal Structure ◽  
Growth Rate ◽  
Low Temperature ◽  
Surface Morphology ◽  
Single Crystal ◽  
Root Mean Square Roughness ◽  
Rate Variation ◽  
Mean Square ◽  
Nucleation Layer ◽  
Low Temperature Epitaxy

Представлены результаты изучения морфологии поверхности и структуры слоев AlN, сформированных аммиачной МЛЭ на темплейтах 3C-SiC/Si(111) on-axis- и 4° off-axis-разориентации. Опробован технологический режим низкотемпературной эпитаксии зародышевого слоя AlN на поверхности 3C-SiC(111). Среднеквадратичная шероховатость поверхности (5 х 5 мкм) слоев AlN толщиной 150 ± 50 нм составила 2,5-3,5 нм на темплейтах 3C-SiC/Si(111) on-axis и 3,3-3,5 нм на 4° off-axis. Показано уменьшение шероховатости смачивающего слоя AlN при изменении скорости роста. Получены монокристаллические слои AlN(0002) со значениями FWHM (ω-геометрия) 1,4-1,6°. The paper presents the surface morphology and crystal structure of AlN layers formed by ammonia MBE on 3C-SiC/Si(111) on-axis and 4° off-axis disorientation. It offers the technological approach of low-temperature epitaxy of the AlN nucleation layer on the 3C-SiC (111) surface. Root mean square roughness (5 х 5 |xm) of AlN layers with thickness of 150 ± 50 nm was 2,5-3,5 nm onto on-axis templates and 3.3-3.5 nm onto 4° off-axis. It appears that the RMS roughness of the AlN surface is changing with the growth rate variation. Single-crystal AlN(0002) layers with FWHM values (ω-geometry) of 1.4-1.6° have been obtained.

Disentangling the role of competition, light interception, and functional traits in tree growth rate variation in South Asian tropical moist forests

2021 ◽  
Vol 483 ◽  
pp. 118908
Author(s):  
Mizanur Rahman ◽  
Masum Billah ◽  
Md Obydur Rahman ◽  
Debit Datta ◽  
Muhammad Ahsanuzzaman ◽  
...  
Keyword(s):  
Growth Rate ◽  
Functional Traits ◽  
South Asian ◽  
Tree Growth ◽  
Light Interception ◽  
Rate Variation ◽  
Tree Growth Rate

scholarly journals Effect of genotype, age of hens and K/k allele on eggshell quality

2011 ◽  
Vol 56 (No. 5) ◽  
pp. 242-249 ◽  
Author(s):  
Z. Ledvinka ◽  
L. Zita ◽  
M. Hubený ◽  
E. Tůmová ◽  
M. Tyller ◽  
...  
Keyword(s):  
Growth Rate ◽  
Egg Production ◽  
Statistical Significance ◽  
Live Weight ◽  
Shape Index ◽  
Feed Mixture ◽  
Eggshell Quality ◽  
Feather Growth ◽  
Two Factors ◽  
The Relationship

We assessed the influence of the particular genotype, age of layers, feather growth-rate gene, and their mutual interactions on selected indicators of eggshell quality in six groups of hens of the laying type Dominant. The following genotypes were examined in the experiment: Barred Plymouth Rock, Dominant BPR 951 (K) strain, slow-feathering; Barred Plymouth Rock, Dominant BPR 901 (k) strain, fast-feathering; Blue Plymouth Rock, Dominant BLPR 954 (K) strain, slow-feathering; Blue Plymouth Rock, Dominant BLPR 894 (k) strain, fast-feathering; crossbreds of the above strains in the F<sub>1</sub> generation Dominant D 107 blue (K), slow-feathering and Dominant D 107 blue (k), fast-feathering. The layers were fed a feed mixture NP1 (16.64 % CP) from the 20<sup>th</sup> week of age and a feed mixture NP2 (15.02% CP) from the 42<sup>nd</sup> week. Husbandry conditions met the regular requirements of laying hens. Egg production and live weight of hens were monitored for the duration of the experiment (12 months). Eggshell quality was examined at the layers' age of 27, 35 and 56 weeks. The average hen-day egg production for the duration of the experiment (12 months) was not significantly influenced by the particular genotype or the feather growth-rate gene. The varying representation of the feather growth-rate gene significantly (P &le; 0.001) influenced the live weight; similarly, the relationship between the genotype and the representation of K/k alleles was significant. The average egg weight was influenced statistically significantly (P &le; 0.001) by the age of hens, their genotype (P &le; 0.05), feather growth-rate gene (P &le; 0.001), and the relationship between the age and genotype (P &le; 0.001). The age of hens, genotype, and the interaction of these two factors affected the egg shape index, as did the incidence of the feather growth-rate gene within the population (with a statistical significance of P &le; 0.001). The age, genotype and the feather growth-rate gene incidence within the population also significantly affected the eggshell quality indicators. In the eggshell to egg ratio, eggshell thickness and strength, an interaction was determined between the age of hens and their particular genotype. The eggshell colour was also significantly (P &le; 0.001) affected by hens' age, genotype (P &le; 0.001), as well as by the feather growth-rate gene (P &le; 0.001). No significant interaction between the age and the genotype was found for this indicator.

scholarly journals Feed demand behavior in sea bass juveniles: Effects on individual specific growth rate variation and health (inter-individual and inter-group variation)

Aquaculture ◽  
2008 ◽  
Vol 274 (1) ◽  
pp. 87-95 ◽  
Author(s):  
S. Millot ◽  
M.-L. Bégout ◽  
J. Person-Le Ruyet ◽  
G. Breuil ◽  
C. Di-Poï ◽  
...  
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Specific Growth ◽  
Sea Bass ◽  
Rate Variation ◽  
Group Variation

The polarized epithelial phenotype is dominant in hybrids between polarized and unpolarized rat thyroid cell lines

1991 ◽  
Vol 98 (1) ◽  
pp. 65-73
Author(s):  
C. Zurzolo ◽  
R. Gentile ◽  
A. Mascia ◽  
C. Garbi ◽  
C. Polistina ◽  
...  
Keyword(s):  
Cell Polarity ◽  
Chromosome Complement ◽  
Thyroid Cell ◽  
Chromosome Loss ◽  
Epithelial Phenotype ◽  
Membrane Antigens ◽  
Dependent Growth ◽  
Rat Thyroid ◽  
Hybrid Clones ◽  
Specific Membrane

We have studied the expression of cell polarity in hybrids between two rat thyroid epithelial cells: FRT and FRTL-5. FRT cells are polarized but do not express tissue-specific properties, FRTL-5 are unpolarized and express many thyroid-specific genes. A and express many thyroid-specific genes. A pool of 170 hybrid clones and five independent clones were characterized. The chromosome complement was that expected from 1:1 fusion of the parental cells. No chromosome loss was observed for several generations. All hybrids were polarized as judged from: (1) morphology, (2) transepithelial resistance, (3) preferential secretion of several proteins either through the apical (e.g. thyroglobulin) or through the basolateral pole, and (4) basolateral trapping of iodide. On the other hand, the expression of thyroid-specific markers: thyroglobulin synthesis and secretion, trapping of iodide, thyrotropin-dependent growth and expression of specific membrane antigens, were greatly reduced or inhibited in the pool and in the isolated clones. We also found that reduction of thyroglobulin synthesis was correlated with the loss of activity of the trans-acting factor TgTF1. We conclude that cell polarity, a property of FRT cells, is dominant in the hybrids whereas thyroid differentiation is recessive.

Intraracial variation in Phytophthora infestans, and its relationship to different host varieties

1969 ◽  
Vol 47 (6) ◽  
pp. 863-867 ◽  
Author(s):  
Alan Upshall
Keyword(s):  
Growth Rate ◽  
Comparative Study ◽  
Phytophthora Infestans ◽  
Resistant Variety ◽  
Rate Variation ◽  
Low Field

A comparative study of the magnitude of growth rate variation among isolates of Phytophthora infestans (Mont.) de Bary taken from a high and a low field resistant variety of potato has shown it to be greater in the former than in the latter, even though both crops were infected by the same population of the pathogen. Competition between spores, and adaptation to the varieties, are put forward as possible alternative explanations.

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