Low pH avoidance by crayfish (Orconectes virilis): evidence for sensory conditioning

1985 ◽  
Vol 63 (2) ◽  
pp. 258-262 ◽  
Author(s):  
R. L. France
Keyword(s):  
Reference Population ◽  
Low Ph ◽  
Behavioral Modification ◽  
Orconectes Virilis ◽  
Reference Lake ◽  
Two Populations ◽  
Avoidance Responses

Avoidance responses of crayfish (Orconectes virilis) to low pH were tested for individuals from two populations, one inhabiting a reference lake and one from a lake experimentally acidified over a 5-year period to a mean summer epilimnetic pH of 5.3. Adult and yearling crayfish from the reference population displayed a strong avoidance of potentially lethal water of pH 4.5 and below. However, there was no avoidance demonstrated to water above pH 5.0, which is known to seriously impair reproduction of this species. Animals from the acidified lake had noticeably reduced avoidance, significant at only pH 4.0, with no behavioral modification occurring above pH 4.5.

scholarly journals The superiority of multi-trait models with genotype-by-environment interactions in a limited number of environments for genomic prediction in pigs

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Hailiang Song ◽  
Qin Zhang ◽  
Xiangdong Ding
Keyword(s):  
Genomic Prediction ◽  
Production Systems ◽  
Genetic Correlations ◽  
Reproductive Traits ◽  
Reference Population ◽  
Linear Unbiased Prediction ◽  
Genotype By Environment ◽  
Best Linear Unbiased ◽  
Effect Estimation ◽  
Two Populations

Abstract Background Different production systems and climates could lead to genotype-by-environment (G × E) interactions between populations, and the inclusion of G × E interactions is becoming essential in breeding decisions. The objective of this study was to investigate the performance of multi-trait models in genomic prediction in a limited number of environments with G × E interactions. Results In total, 2,688 and 1,384 individuals with growth and reproduction phenotypes, respectively, from two Yorkshire pig populations with similar genetic backgrounds were genotyped with the PorcineSNP80 panel. Single- and multi-trait models with genomic best linear unbiased prediction (GBLUP) and BayesC π were implemented to investigate their genomic prediction abilities with 20 replicates of five-fold cross-validation. Our results regarding between-environment genetic correlations of growth and reproductive traits (ranging from 0.618 to 0.723) indicated the existence of G × E interactions between these two Yorkshire pig populations. For single-trait models, genomic prediction with GBLUP was only 1.1% more accurate on average in the combined population than in single populations, and no significant improvements were obtained by BayesC π for most traits. In addition, single-trait models with either GBLUP or BayesC π produced greater bias for the combined population than for single populations. However, multi-trait models with GBLUP and BayesC π better accommodated G × E interactions, yielding 2.2% – 3.8% and 1.0% – 2.5% higher prediction accuracies for growth and reproductive traits, respectively, compared to those for single-trait models of single populations and the combined population. The multi-trait models also yielded lower bias and larger gains in the case of a small reference population. The smaller improvement in prediction accuracy and larger bias obtained by the single-trait models in the combined population was mainly due to the low consistency of linkage disequilibrium between the two populations, which also caused the BayesC π method to always produce the largest standard error in marker effect estimation for the combined population. Conclusions In conclusion, our findings confirmed that directly combining populations to enlarge the reference population is not efficient in improving the accuracy of genomic prediction in the presence of G × E interactions, while multi-trait models perform better in a limited number of environments with G × E interactions.

scholarly journals Assessing accuracy of imputation in Gyr breed using different SNP panels

Genome ◽  
2021 ◽  
Author(s):  
Alejandra Maria Toro Ospina ◽  
Ignacio Aguilar ◽  
Matheus Henrique Vargas de Oliveira ◽  
Luiz eduardo Cruz dos Santos Correia ◽  
Anibal Eugenio Vercesi Filho ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Bos Taurus ◽  
Imputation Accuracy ◽  
Bos Indicus ◽  
Principal Component ◽  
Reference Population ◽  
Medium Density ◽  
Genomic Relationship ◽  
Snp Panels ◽  
Two Populations

The objective of this study was to evaluate the accuracy of imputation in a Gyr population using two medium density panels (Bos taurus - Bos indicus) and to test whether the inclusion of the Nellore breed increases the imputation accuracy in the Gyr population. The database consisted of 289 Gyr females from Brazil genotyped with the GGP Bovine LDv4 chip containing 30,000 SNPs and 158 Gyr females from Colombia genotyped with the GGP indicus chip containing 35,000 SNPs. A customized chip was created that contained the information of 9,109 SNPs (9K) to test the imputation accuracy in Gyr populations; 604 Nellore animals with information of LD SNPs tested in the scenarios were included in the reference population. Four scenarios were tested: LD9K_30KGIR, LD9K_35INDGIR, LD9K_30KGIR_NEL and LD9K_35INDGIR_NEL. Principal component analysis (PCA) was computed for the genomic matrix and sample-specific imputation accuracies were calculated using Pearson’s correlation (CS) and the concordance rate (CR) for imputed genotypes. The results of PCA of the Colombian and Brazilian Gyr populations demonstrated the genomic relationship between the two populations. The CS and CR ranged from 0.88 to 0.94 and from 0.93 to 0.96, respectively. Among the scenarios tested, the highest CS (0.94) was observed for the LD9K_30KGIR scenario.However, the variation in SNPs may reduce the imputation accuracy even when the chip of the Bos indicus subspecies is used

Population Collapse of the Crayfish Orconectes virilis in Response to Experimental Whole-Lake Acidification

1989 ◽  
Vol 46 (6) ◽  
pp. 910-922 ◽  
Author(s):  
I. J. Davies
Keyword(s):  
Population Size ◽  
Population Decline ◽  
Fish Predation ◽  
Reference Population ◽  
Lake Acidification ◽  
Orconectes Virilis ◽  
Microsporidian Parasite ◽  
Experimental Lakes Area ◽  
Recruitment Failure ◽  
Northwestern Ontario

A population of Orconectes virilis in Lake 223 at the Experimental Lakes Area, northwestern Ontario, was monitored from 1976 to 1982 during an acidification experiment. O. virilis from nearby Lake 240 served as a reference population. Crayfish abundance remained stable as average epilimnion pH was gradually lowered from 6.49 (1976) to 5.93 (1978). In 1979 (pH 5.64) recruitment of young was poor and the overall population size [Formula: see text] fell from 105 800 to 60 300 animals. The decline continued in the complete absence of recruitment during 1980 (pH 5.59, [Formula: see text] and 1981 (pH 5.02, [Formula: see text]. Few crayfish survived until the spring of 1982. None were present from mid-summer 1982 to fall 1983 (average pH 5.09 to 5.13). Hatchling mortality and some egg loss appeared to have been the causes of recruitment failure. Acidification also produced a noticeable softening in the carapace of all intermoult crayfish. Growth, mortality, behaviour, and the basic reproductive functions of juvenile and adult crayfish did not change in response to acidification. Fish predation and the incidence of a microsporidian parasite apparently contributed little to the population decline.

Decreased Survival and Calcium Uptake by the Crayfish Orconectes virilis in Low pH

1980 ◽  
Vol 37 (3) ◽  
pp. 364-372 ◽  
Author(s):  
D. F. Malley
Keyword(s):  
Acid Rain ◽  
Lake Water ◽  
Calcium Uptake ◽  
Physiological Responses ◽  
Low Ph ◽  
Lake Acidification ◽  
Orconectes Virilis ◽  
Molt Cycle ◽  
Experimental Lakes Area ◽  
Acidification Of Lake

As part of a study of the effects of the experimental whole-lake acidification of Lake 223 in the Experimental Lakes Area on the population of the crayfish Orconectes virilis physiological responses of adults from this population to low pH were examined in the laboratory. Crayfish survived pH 4.0 for 10 d when they were not moulting but suffered mortality when they were in postmolt stages. Postmolt crayfish held at pH 5.0 for 10 d survived but showed slower progression of molt cycle stages and of calcification of the exoskeleton than individuals held at pH 6.0 or in lake water at about pH 6.7. Uptake of Ca++ by postmolt crayfish measured by the use of 45Ca as a tracer was inhibited by pH below 5.75 and ceased altogether below pH 4.0 when these levels of acidity were applied acutely.Key words: Orconectes virilis, crayfish, molt cycle, mortality, pH, calcification, postmolt calcium uptake, acid rain, lake acidification

Effects of Low pH on Survival of Crayfish (Orconectes virilis)

1991 ◽  
Vol 6 (1) ◽  
pp. 87-91 ◽  
Author(s):  
Horst F. Siewert ◽  
John P. Buck
Keyword(s):  
Low Ph ◽  
Orconectes Virilis

Comparative tolerance to low pH of three life stages of the crayfish Orconectes virilis

1984 ◽  
Vol 62 (12) ◽  
pp. 2360-2363 ◽  
Author(s):  
R. L. France
Keyword(s):  
Life Cycle ◽  
Acid Stress ◽  
Low Ph ◽  
Stage Iii ◽  
Life Stages ◽  
Orconectes Virilis ◽  
Old Adults ◽  
Population Extinction ◽  
Life Cycle Stages

The response of three life cycle stages of Orconectes virilis to acidification was investigated in the laboratory. Chronic lethality tests revealed that compared with 2-week-old stage III hatchlings, 2.5-month-old juveniles were seven times more tolerant to acid but only one-twentieth as tolerant as 2- to 3-year-old adults. Juvenile crayfish recovered following exposure to acid stress (pH < 3.5). Comparison of laboratory survival results with data from the literature concerning the magnitude and duration of chemical fluctuations indicates that lentic populations of O. virilis are not likely to decline as a result of episodic acid events. Nevertheless, gradual acidification of a lake to an average annual pH below 5.5 could result in eventual population extinction as a result of mortality of the young.

scholarly journals MODELLING MORTALITY FOR PENSION SCHEMES

2017 ◽  
Vol 47 (2) ◽  
pp. 601-629 ◽  
Author(s):  
Andrew Hunt ◽  
David Blake
Keyword(s):  
Population Data ◽  
Reference Population ◽  
Mortality Rates ◽  
Pension Scheme ◽  
Basis Risk ◽  
Stochastic Mortality ◽  
Pension Schemes ◽  
Stochastic Mortality Models ◽  
Mortality Models ◽  
Two Populations

AbstractFor many pension schemes, a shortage of data limits their ability to use sophisticated stochastic mortality models to assess and manage their exposure to longevity risk. In this study, we develop a mortality model designed for such pension schemes, which compares the evolution of mortality rates in a sub-population with that observed in a larger reference population. We apply this approach to data from the CMI Self-Administered Pension Scheme study, using U.K. population data as a reference. We then use the approach to investigate the potential differences in the evolution of mortality rates between these two populations and find that, in many practical situations, basis risk is much less of a problem than is commonly believed.

Relationship between golgi apparatus and axonal reticulum in sympathetic ganglion cells

1978 ◽  
Vol 36 (2) ◽  
pp. 598-599
Author(s):  
J. Quatacker ◽  
W. De Potter
Keyword(s):  
Golgi Apparatus ◽  
Sympathetic Ganglion ◽  
Phosphotungstic Acid ◽  
Ganglion Cells ◽  
Low Ph ◽  
Dense Core ◽  
Dense Core Vesicles ◽  
Large Dense Core Vesicles ◽  
Cervical Ganglia ◽  
Axoplasmic Reticulum

Mucopolysaccharides have been demonstrated biochemically in catecholamine-containing subcellular particles in different rat, cat and ox tissues. As catecholamine-containing granules seem to arise from the Golgi apparatus and some also from the axoplasmic reticulum we examined wether carbohydrate macromolecules could be detected in the small and large dense core vesicles and in structures related to them. To this purpose superior cervical ganglia and irises from rabbit and cat and coeliac ganglia and their axons from dog were subjected to the chromaffin reaction to show the distribution of catecholamine-containing granules. Some material was also embedded in glycolmethacrylate (GMA) and stained with phosphotungstic acid (PTA) at low pH for the detection of carbohydrate macromolecules.The chromaffin reaction in the perikarya reveals mainly large dense core vesicles, but in the axon hillock, the axons and the terminals, the small dense core vesicles are more prominent. In the axons the small granules are sometimes seen inside a reticular network (fig. 1).

Comparison of Principal Component Solutions in Two Populations

Methodology ◽  
2016 ◽  
Vol 12 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Gregor Sočan
Keyword(s):  
Simulation Study ◽  
Principal Components ◽  
Common Factor ◽  
Principal Component ◽  
Component Model ◽  
Bootstrap Procedure ◽  
Factor Loadings ◽  
Component Loadings ◽  
Principal Component Model ◽  
Two Populations

Abstract. When principal component solutions are compared across two groups, a question arises whether the extracted components have the same interpretation in both populations. The problem can be approached by testing null hypotheses stating that the congruence coefficients between pairs of vectors of component loadings are equal to 1. Chan, Leung, Chan, Ho, and Yung (1999) proposed a bootstrap procedure for testing the hypothesis of perfect congruence between vectors of common factor loadings. We demonstrate that the procedure by Chan et al. is both theoretically and empirically inadequate for the application on principal components. We propose a modification of their procedure, which constructs the resampling space according to the characteristics of the principal component model. The results of a simulation study show satisfactory empirical properties of the modified procedure.

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