scholarly journals THE FLICKER RESPONSE CONTOURS FOR GENETICALLY RELATED FISHES. II

1939 ◽  
Vol 22 (4) ◽  
pp. 463-485 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
F1 Hybrids ◽  
Genetic Constitution ◽  
Rational Analysis ◽  
Organic System ◽  
Rods And Cones ◽  
Flicker Response ◽  
Physical Organization ◽  
Biological Performance ◽  
Intermediate Value ◽  
Invariant Properties

The flicker response contour has been determined for several species and types of the teleosts Xiphophorus (X.) and Platypoecilius (P.) under the same conditions. The curve (F vs. log Im) is the same for representatives of each generic type, but is different for the two genera. Its duplex nature is analyzable in each instance by application of the probability integral equation to the rod and cone constituent parts. The parameters of this function provide rational measures of invariant properties of the curves, which have specific values according to the genetic constitution of the animal. The F1 hybrids (H'') of X. montezuma x P. variatus show dominance of the X. properties with respect to cone Fmax. and σ' log I, but an intermediate value of the abscissa of inflection (τ'). The rod segment shows dominance of σ' log I from P., but an intermediate value of Fmax. and of τ'. The composite flicker curve involves the operation of two distinct assemblages of excitable elements, differing quantitatively but not qualitatively in physicochemical organization, probably only secondarily related to the histological differentiation of rods and cones because almost certainly of central nervous locus, but following different rules in hereditary determination, and therefore necessarily different in physical organization. The interpretation of the diverse behavior of the three parameters of the probability summation is discussed, particularly in relation to the physical significance of these parameters as revealed by their quantitative relations to temperature, retinal area, and light time fraction in the flash cycle, and to their interrelations in producing the decline of rod effects at higher intensities. It is stressed that in general the properties of the parameters of a chosen interpretive analytical function must be shown experimentally to possess the physical properties implied by the equation selected before the equation can be regarded as describing those invariant properties of the organic system concerned upon which alone can deduction of the nature of the system proceed. The importance of genetic procedures in furthering demonstration that the biological performance considered in any particular case exhibits constitutionally invariant features provides a potentially powerful instrument in such rational analysis.

scholarly journals TEMPERATURE AND CRITICAL ILLUMINATION FOR REACTION TO FLICKERING LIGHT

1939 ◽  
Vol 23 (2) ◽  
pp. 143-163 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
Arrhenius Equation ◽  
Temperature Characteristic ◽  
F1 Hybrids ◽  
Intergeneric Cross ◽  
Chemical Mechanisms ◽  
Rods And Cones ◽  
Flicker Response ◽  
Chemical Factors ◽  
Different Shapes ◽  
Critical Intensity

For the teleosts Xiphophorus montezuma, Platypoecilius maculatus, and their F1 hybrids the temperature characteristics (µ in Arrhenius' equation) are the same for the shift of the low intensity and the high intensity segments of the respective and different flicker response contours (critical intensity I as a function of flash frequency F, with light time fraction constant, at 50 per cent). The value of µ is 12,500 calories or a very little less, over the range 12.5 to 36°. This shows that 1/I can be understood as a measure of excitability, with F fixed, and that the excitability is governed by the velocity of a chemical process common to both the classes of elements represented in the duplex performance curve (rods and cones). It is accordingly illegitimate to assume that the different shapes of the rod and cone branches of the curves are determined by differences in the chemical mechanisms of excitability. It is also forbidden to assume that the differing form constants for the homologous segments in the curves for two forms (X. and P.) are the reflections of a difference in the chemical factors of primary excitability. These differences are determined by statistical factors of the distribution of excitabilities among the elements implicated in the sensory effect vs. intensity function, and are independent of temperature and of the temperature characteristic. It must be concluded that the physicochemical nature of the excitatory process cannot be deduced from the shape of the performance contour. The form constants (σ'log I and Fmax.) for F vs. log I are specifically heritable in F1, although µ is here the same as for X. and P. In an intergeneric cross one cannot in general expect Mendelian simplicity of segregation in subsequent generations, and in the present case we find that F2 individuals are indistinguishable from F1, both as regards F vs. log I and as regards the variation of I within a group of 17 individuals. The result in F2 definitely shows, however, that certain specific statistical form constants for the F-log I contour are transmissible in inheritance. It is pointed out that there thus is provided an instance in which statistical (distribution) factors in performance characteristics involving the summating properties of assemblages of cellular units are heritable in a simple manner without the implication of detectable differences in chemical organization of the units involved. This has an important bearing upon the logic of the theory of the gene.

scholarly journals THE FLICKER RESPONSE CONTOUR FOR THE GECKO (ROD RETINA)

1939 ◽  
Vol 22 (5) ◽  
pp. 555-566 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
Visual Performance ◽  
Histological Evidence ◽  
Rods And Cones ◽  
Flicker Response ◽  
Intensity Range ◽  
Probability Integral ◽  
Equivalent Conditions

The flicker response contour for the gecko Sphaerodactylus (retina with only rods) agrees in all essential respects (intensity range, shape) with that for the turtle Pseudemys (cone retina), as determined under equivalent conditions with the same apparatus. With experimentally determined correction for the expansion of the iris at the very lowest intensities, the F - log I contour for the gecko is a simple probability integral. Its maximum F is lower than that for other animals; this means simply a smaller number of available sensory elements. The quantitative parallelism in the magnitudes of the intensities at the inflection of F - log I and the shape constants for rod and cone animals show that assumptions from comparative histological evidence concerning the properties of rods and cones in relation to visual performance may be quite misleading.

scholarly journals FLICKER RESPONSE CONTOURS FOR THE SPARROW, AND THE THEORY OF THE AVIAN PECTEN

1944 ◽  
Vol 27 (4) ◽  
pp. 315-324 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
Zebra Finch ◽  
House Sparrow ◽  
Passer Domesticus ◽  
Rods And Cones ◽  
Flicker Response ◽  
Analytical Separation

The flicker contour for the house sparrow Passer domesticus is duplex, corresponding to the presence of both rods and cones in the retina. The presence of the pecten brings about changes in the "cone" part of the contour when the light-time in the flash cycle is varied. These changes are of the same sort as those we have already described for the visually simplex zebra finch, and for man provided with an artificial "pecten shadow." The changes are such as to greatly enhance flicker acuity for small dark-times (moving stripe technique). The form of the scotopic part of the duplex contour (also as in the case with man) gives no evidence that rod excitation is specifically influenced by the presence of the pecten. The changing integration of "rod" and "cone" effects as the light-time fraction is altered provides another means of testing the theory used for the analytical separation of the two components of the duplex flicker contour.

scholarly journals STUDIES ON NORMAL AND IMMUNE LYMPHOCYTE TRANSFER REACTIONS IN GUINEA PIGS, WITH SPECIAL REFERENCE TO THE CELLULAR CONTRIBUTION OF THE HOST

1972 ◽  
Vol 136 (6) ◽  
pp. 1545-1563 ◽  
Author(s):  
Siraik Zakarian ◽  
R. E. Billingham
Keyword(s):  
Guinea Pigs ◽  
Significant Proportion ◽  
Intradermal Injection ◽  
Lymphoid Cells ◽  
Delayed Hypersensitivity ◽  
F1 Hybrids ◽  
Genetic Constitution ◽  
F1 Hybrid ◽  
Immune Lymphocyte ◽  
Lymphocyte Transfer

Using guinea pigs of strains 2 and 13 and their F1 hybrids as experimental subjects, various lines of evidence have been obtained that in this species, as in all others tested, the only significant cellular antigens with which donor lymphocytes engage when normal and immune lymphocyte reactions are incited are radiosensitive leukocytes. Constitutive cells of the skin are unimportant. (a) The intensities of these reactions in irradiated subjects are dependent upon the peripheral leukocyte concentration. When this falls below a certain threshold no reactions are incitable. (b) Highly leukopenic animals are capable of developing immune lymphocyte transfer (ILT) reactions if normal lymphoid cells of their own genetic constitution are mixed with the putative attacking donor cells, as "supplementing antigen," before inoculation. (c) Radiation-chimeric strain 13 animals having F1 hybrid leukocytes in their bloodstream give typical ILT reactions when challenged intradermally with strain 13 anti-2 node cells. Exposure of strain 2 animals to 600 R does not prevent their becoming actively immunized if, 24 hr later, they are injected intradermally with strain 13 lymphocytes. However, this sensitization, revealed by the host's capacity to give delayed hypersensitivity reactions, wanes as leukopenia progresses. On the basis of this and other findings it is argued that the flare-up stage of the NLT reaction in preirradiated hosts is mainly an expression of host sensitivity against the transferred alien cells. Two unexpected observations have been made in the course of this study: (a) F1 hybrid animals developed what appeared to be a strong delayed hypersensitivity after intradermal inoculation with parental strain lymphoid cells or antigenic extracts prepared from them. (b) If strain 13 guinea pigs which had been sensitized against strain 2 tissue antigens by intradermal injection of lymphocytes 7 days beforehand were inoculated intravenously with strain 2 antigenic extract a significant proportion of the animals developed severe delayed necrotizing reactions, recall flares, at some or all of the healed skin inoculation sites.

scholarly journals REACTION TO VISUAL FLICKER IN THE NEWT TRITURUS

1940 ◽  
Vol 23 (6) ◽  
pp. 667-676 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
Fresh Water ◽  
Response Curve ◽  
Integral Form ◽  
Quantitative Structure ◽  
Rods And Cones ◽  
Flicker Response ◽  
Probability Integral ◽  
Cone Curve ◽  
Critical Intensity

The flicker response curve for the newt Triturus viridescens (water phase) has much the same quantitative structure as that found with various fresh-water teleosts at the same temperature (21.5°). The variability of critical intensity and of critical flash frequency likewise follows the same rules. The cone portion of the F - log I curve is much more widely spread, however. This, and the rather low maximum to which the rod curve rises, produce a considerable overlapping of the two parts additively fused. In addition, and to an extent which differs in various individuals, there is apparent a slight departure from the probability integral form of the cone curve. Reasons are given for considering that this is possibly connected with the role of an additional (small) number of (perhaps temporary, or developmental) retinal elements in addition to the typical rods and cones.

scholarly journals Some invariant properties of a geographically structured finite population: distribution of heterozygotes under irreversible mutation

1972 ◽  
Vol 20 (2) ◽  
pp. 141-148 ◽  
Author(s):  
Takeo Maruyama
Keyword(s):  
Population Size ◽  
Total Population ◽  
Finite Population ◽  
Population Distribution ◽  
Mutant Gene ◽  
Selective Advantage ◽  
Genetic Constitution ◽  
Special Cases ◽  
And Migration ◽  
Invariant Properties

SUMMARYIt is shown that the distribution of the sum of heterozygotes, due to mutant gene(s), that appear in a finite population is invariant under geographical structure, provided that the mutant gene has additive effect on fitness and migration does not change the genetic constitution as a whole population. The expected number of heterozygotes is 2N when Ns = 0 and gradually rises to 4N as Ns increases provided s remains small, where N = the total population size and s = selective advantage of a mutant gene. The distribution of the heterozygosity summed over those generations in which the gene frequency in the entire population is specified, is also shown to be invariant. In the case of a neutral mutant, the density is equal to 4(1 − Y) where Y is the frequency of the mutant in the whole population, and in the selectively advantageous case, it is approximately equal to a constant function 4, provided that the population size times selection coefficient is sufficiently large. These quantities conditional on the fixation of the mutant are shown to be invariant and some special cases are obtained explicitly.

scholarly journals Comparative transcriptome analysis of inbred lines and contrasting hybrids reveals overdominance mediate early biomass vigor in hybrid cotton

2019 ◽  
Author(s):  
Kashif Shahzad ◽  
Xuexian Zhang ◽  
Liping Guo ◽  
Tingxiang Qi ◽  
Huini Tang ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Transcriptome Analysis ◽  
Molecular Mechanisms ◽  
Expression Patterns ◽  
F1 Hybrids ◽  
Pcr Analysis ◽  
Genetic Constitution ◽  
Comparative Transcriptome ◽  
Comparative Transcriptome Analysis ◽  
Extracellular Region

Abstract Background: Heterosis breeding is the most useful method for yield increment around the globe. Heterosis is an intriguing process to develop superior offspring to either parent in the desired character. The biomass vigor produced during seedling emergence stage has a direct influence on yield heterosis in plants. Unfortunately, the genetic basis of early biomass vigor in hybrid cotton is poorly understood. Results: Three stable performing F1 hybrids varying in yield heterosis named as high, medium and low hybrids with their inbred parents were used in this study. Phenotypically, these hybrids established noticeable biomass heterosis during the early stage of seedling growth in the field. Transcriptome analysis of root and leaf revealed that hybrids showed many differentially expressed genes (DEGs) relative to their parents, while the comparison of inbred parents showed limited number of DEGs indicating similarity in their genetic constitution. Further analysis indicated that expression patterns of most DEGs were overdominant in both tissues of hybrids. According to GO results, functions of overdominance genes in leaf were enriched for chloroplast, membrane, and protein binding, whereas functions of overdominance genes in root were enriched for plasma membrane, extracellular region, and responses to stress. We found that several genes of circadian rhythm pathway related to LATE ELONGATED HYPOCOTYL (LHY) showed downregulated overdominant expressions in both tissues of hybrids. In addition to circadian rhythm, several leaf genes related to Aux/IAA regulation and many root genes involved in peroxidase activity also showed overdominant expressions in hybrids. Twelve genes involved in circadian rhythm plant were selected to perform qRT-PCR analysis to confirm the accuracy of RNA-seq results. Conclusions: Through genome-wide comparative transcriptome analysis, we strongly predict that overdominance at gene expression level plays a pivotal role in early biomass vigor of hybrids. The combinational contribution of circadian rhythm and other metabolic processes may be controlled vigorous growth in hybrids. Our result provides an important foundation for dissecting molecular mechanisms of biomass vigor in hybrid cotton.

A Rational Analysis of Constructed Preference

2014 ◽  
Author(s):  
Shlomi Sher ◽  
Johannes Muller-Trede ◽  
Craig R. M. McKenzie
Keyword(s):  
Rational Analysis

TUMOURS OF THE HYPOPHYSIS AND THE THYROID IN MICE

1955 ◽  
Vol 18 (4) ◽  
pp. 445 ◽  
Author(s):  
O. Mühlbock
Keyword(s):  
Thyroid Gland ◽  
Radioactive Iodine ◽  
Thyroid Tissue ◽  
Prolonged Treatment ◽  
Genetic Constitution ◽  
Thiouracil Derivatives

SUMMARY Hypophyseal tumours in mice develop after prolonged treatment with oestrogens, after injection of radioactive iodine in doses which destroy the thyroid tissue and after prolonged treatment with thiouracil-derivatives. The tumours of the hypophysis only occur in certain strains of mice and hence the genetic constitution is of importance. The origin of this difference between strains has hitherto remained completely obscure. The hypophyseal tumours in mice seen following administration of oestrogens and those observed after destruction of the thyroid gland are morphologically similar. They consist of cells staining blue to varying degrees, and they may thus be termed amphophile tumours. The possible mechanism of development of the hypophyseal tumours has been discussed.

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