Maintenance mechanism of polymorphism at the α-Gpdh locus in Drosophila melanogaster

Polymorphism at the alpha-Gpdh locus was studied in Drosophila melanogaster. Using two different lines, one marked by the F allele (FF line) another by the S allele (SS line), four populations were initiated, two in which the initial frequency of F was 0.1 and two in which it was 0.9. They have been observed for 34 generations. From the fifth generation on, the equilibrium frequency in the four cages was about 0.60. Viability has been measured during the evolution of te populations while F frequencies changed and recombinations between the FF and SS lines occurred. It has been evaluated in synthetic populations built with different frequencies: (1) from the original FF and SS lines and (2) from FF and SS lines extracted after 34 generations of joint evolution. In all three cases, the FF viability depended on the frequency of the F allele. The similarity of the three linear regressions implies that alpha-Gpdh locus or other closely linked loci is the target of the selection in the populations analyzed here.     

Haptoglobin subtypes in Norway and a review of HP subtypes in various populations.

Isofocusing and immunoblotting of reduced serum samples identify the common haptoglobin alpha-chain variants 1S, 1F, 2FS, 2SS, 2FF, 3, as well as several rare alpha- and beta-chain variants. The gene frequencies found in 6,668 unrelated persons involved in Norwegian paternity cases were: HP*1S: 0.22, HP*1F: 0.16, HP*2FS: 0.58, HP*2SS: 0.04, HP*2FF: 0.004, HP*3: 0.0004, other HP* alpha variants: 0.0004, HP* beta variants: 0.0008. The corresponding gene frequencies in 153 unrelated Norwegian Saamis (Lapps) were: HP*1S: 0.19, HP*1F: 0.07, HP*2FS: 0.70, HP*2SS: 0.04. Norwegians and Norwegian Saamis differed both in phenotype and allele distribution. An earlier Norwegian population study has shown a lower HP*1 frequency in the north than in the south. This regional difference in haptoglobin gene distribution was reflected in the present material as a lower 1F frequency, indicating a Saamish influence in northern Norway. Furthermore, the relatively low 2FF frequency in the north coincides with the lack of observed 2FF genes in the Saamish population. Non-Scandinavians involved in Norwegian paternity cases did not differ from the rest of the material. A review of published haptoglobin gene frequencies shows the 1F frequency to be a good indicator of ethnic origin, and that 2FF and 2SS frequency determinations may also be valuable in genetic population studies.     

Polymorphisms of the haptoglobin peptide chains in Pyrenean populations.

This study has analyzed the haptoglobin genotype frequencies in over 900 samples from populations living on the Northern slopes of the Pyrenees. The results emphasize the importance of systematically determining the frequencies of the Hp1S, Hp1F, Hp2SS, Hp2FF, Hp2FS alleles. Hp1S was the predominant allele, the HpIS/Hp1 distribution varying between .5 and .69 as in most European populations. Hp2 alleles were observed in low frequency with differences in geographically distinct samples. Pyrenean populations in the western zones (Basques and Baronnies) were found to contain the Hp2FF allele while those in eastern regions, the Hp2SS allele. We have speculated that Hp2SS is as old as the Hp2FF, arising from southern Mediterranean areas, and suggest that Pyrenean groups have different origins.     

Involvement of interaction between viral VP466 and host tropomyosin proteins in virus infection in shrimp

The C3 component of complement has different roles in kidney disease and its local production in donor kidney may affect allograft function and rejection after organ transplantation. A single base substitution in c3 gene (rs2230199), defines two common allelic variants with different mobility on gel electrophoresis: S (Slow) and F (Fast). In order to evaluate the effect of this polymorphism on acute renal allograft rejection, one hundred samples of donor and recipients were collected and genotyping was done by PCR-RFLP method. The allelic frequencies were: C3S=0.791, C3F=0.209. There was no significant association between recipient's genotype and acute rejection (p value<0.05). No correlation between donor genotype and acute rejection was also present. Patients were divided into four groups, according to the recipient and donor genotypes: SS recipients and FS or FF donor, SS recipient and donor, FF or FS recipient and SS donor and FS or FF recipient and donor. There was no significant difference in rate of acute rejection between groups. Although the results didn't find any association between C3 complement polymorphisms and acute allograft rejection, there was no acute rejection in FS or FF donors and SS recipient group.     

Heterosis associated with DOPA-oxidase dimorphism in Culex pipiens

1. Isozyme phenotypes were used to deduce genotypes at a dimorphic DOPA-oxidase locus in a laboratory population of Culex pipiens. The frequencies of homozygotes and heterozygotes at the inception and termination of laboratory colonization were compared. 2. Co-dominant alleles F and S condition the fast and slow isozymes (allozymes) respectively at this enzyme locus. 3. The expected and observed ratios of heterozygotes (FS) to homozygotes (FF and SS) were 50:50 and 64:36 respectively for 50 pairs of parents. 4. The observed and statistically significant excess of heterozygotes is taken as evidence of heterosis and the heterotic maintenance of enzyme dimorphism at this locus.     

Biochemical homeostasis of the heterozygote at the lysozyme locus in Japanese Quail

The egg-white lysozyme in the Japanese quail shows electrophoretic polymorphism, there being two allelic forms (F and S). The proportions of the three phenotypes (FF, FS and SS) in three different populations agree with the expected values of the Hardy-Weinberg law in panmictic equilibrium. In the three populations examined the proportions of heterozygotes are close to the maximal expected value. The pH optima of the two homozygotes are different. Maintenance of this polymorphism is explained on the basis of Haldane's concept of the heterozygote advantage by biochemical homeostasis.     

Genetic polymorphism of C3 in the Veneto population, Italy

The distribution of C3 phenotypes in the population of Veneto was investigated by electrophoresis on agarose gel. In our sample (n = 810) the three common phenotypes C3 SS, C3 FF and C3 FS and a further phenotype, C3 S-VF, were observed. The following gene frequencies could be calculated: C3S = 0.8068, C3F = 0.1926 and C3V = 0.0006. These frequencies have been compared with those found in other populations. The analysis of 21 mother-child pairs was in agreement with an autosomal codominant inheritance.     

Variation in amount of enzyme protein in natural populations

Among strains of Drosophila melanogaster each derived from a single fertilized female taken from natural populations, there is variation in both alcohol dehydrogenase (ADH) activity and the amount of ADH protein. The correlation between ADH activity and number of molecules over all strains examined is 0.87 or 0.96 in late third instar larvae depending on whether the substrate is 2-propanol or ethanol. With respect to the two common electrophoretic allozymic forms, F and S, segregating in these populations, the FF strains on the whole have higher ADH activities and numbers of ADH molecules than the SS strains. Over all strains examined, enzyme extracts from FF strains have a mean catalytic efficiency per enzyme molecule higher than that of enzyme extracts from SS strains when ethanol is the substrate, and much higher when 2-propanol is the substrate. One FF strain had an ADH activity/ADH protein ratio characteristic of SS strains.     

The investigation of allele and genotype frequencies of human C3 (rs2230199) in south Iranian population

The complement system is an important mediator of natural and acquired immunity. The complement system genes coding complement proteins have polymorphisms. Hereditary deficiencies of this system predispose to autoimmune conditions such as age-dependent macular degeneration or impairment of immunity against microorganisms. When different populations are compared, the frequency of complement polymorphism shows a very marked geographical distribution. The frequency of the functional polymorphism rs2230199 (Arg80Gly; C > G) in the C3 gene was determined in population from south of Iran (n = 200), using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). One hundred thirty-eight persons (69 %) were homozygous for C allele (CC or SS); fifty-six person (28 %) heterozygote GC (FS) and six people were homozygous for G allele (GG or FF) (3 %). The allele frequency was 82 % for C3S and 18 % for C3F. A distribution of C3C allele frequency in our population is different from the reports of Asians (100 %); Indians (90-98 %); African-American (93 %); Africans (99 %) and south Brazilian (97 %). However, this finding is similar with the findings Caucasian (80-82 %) ( http://www.ncbi.nlm.nih.gov/SNP ); Americans (80 %); Pushtoon, Hazaras, Osbek and Tajik ethnic groups in Afghanistan (88-90 %) and Tunisian population (84 %). Our study confirmed significant inter-ethnic differences in C3 (rs2230199) frequencies between south Iranians and other ethnic groups. The analysis of genetic variation in complement genes is a tool to provide new insights into the evolution of the human immune system.     

Studies on red cell carbonic anhydrase types in Korean cattle

Red cell carbonic anhydrase types in Korean cattle were investigated by means of starch gel electrophoresis.
A carbonic anhydrase zone (X) located ahead zone F was found in 12 out of 502 Korean cattle.
The distribution of CA phenotypes in 490 Korean cattle was CA FS type 92 and CA SS type 398. The CA FF type has not yet been recognized in Korean cattle. The gene frequencies were CA^F– 0.094 and CA^F = 0.906. No statistically significant differences were observed between gene frequencies in cattle from six different Korea provinces.     

Genetic polymorphism of haptoglobin subtypes in a Japanese population

Haptoglobin (Hp) subtypes have been determined in the Japanese population by polyacrylamide gel isoelectric focusing followed by immunoblotting and by two-dimensional polyacrylamide gel electrophoresis. In the present study, neuraminidase-treated plasma samples were used for subtyping of Hp, without prior purification. These samples were obtained from 372 unrelated healthy donors. Allelic frequencies were: Hp*1F = 0.0014; Hp*1S+ = 0.2688; Hp*2FF = 0.0000; Hp*2FS = 0.7284, and Hp*2SS = 0.0014. The phenotypic distribution was in good accordance with the Hardy-Weinberg equilibrium.     

Direct and correlated responses to selection for larval ethanol tolerance in Drosophila melanogaster

Ethanol is an important larval resource and toxin for natural Drosophila melanogaster populations, and ethanol tolerance is genetically variable within and among populations. If ethanol‐tolerant genotypes have relatively low fitness in the absence of ethanol, as suggested by the results of an earlier study, genetic variation for ethanol tolerance could be maintained by variation in ethanol levels among breeding sites. I selected for ethanol tolerance in large laboratory populations by maintaining flies on ethanol‐supplemented media. After 90 generations, the populations were compared with control populations in egg‐to‐adult survival and development rate on ethanol‐supplemented and unsupplemented food. When compared on ethanol‐supplemented food, the ethanol‐selected populations had higher survival and faster development than the control populations, but on unsupplemented food, the populations did not differ in either trait. These results give no evidence for a ‘trade‐off’ between the ability to survive and develop rapidly in the presence of ethanol and the ability to do so in its absence. The effect of physiological induction of ethanol tolerance by exposing eggs to ethanol was also investigated; exposing eggs to ethanol strongly increased subsequent larval survival on ethanol‐supplemented food, but did not affect survival on regular food, and slowed development on both ethanol‐supplemented and regular food, partly by delaying egg hatch.     

Diurnal variability of gene arrangement frequencies in Drosophila subobscura populations from two habitats*

The rich inversion polymorphism of chromosomes of Drosophila subobscura varies in association with environmental changes at spatial and temporal level. Due to random factors this might become less regular and this might be the reason that there is little evidence of altitudinal and seasonal, microgeographic and habitat‐related variability. The variability of gene arrangement frequencies over daytime period was investigated in populations of D. subobscura from two ecologically different habitats. According to gene arrangement frequencies and inversion polymorphism parameters populations fit into the existing patterns of regional polymorphism. Even though populations display daytime variability for the frequencies of arrangements of chromosomes U and J, the nonsignificant differences in other arrangement frequencies, as well as data obtained from genetic distances between samples from different times of day, rule out the existence of subpopulations distinguished from each other by diurnal activity within two habitats. Some particular arrangement frequencies vary according to temperature and humidity and some changes appear for different karyotypic combinations between beech and oak habitat, which suggests different adaptive advantages and selective mechanisms. Cluster analysis of gene arrangement frequencies indicates some importance of A chromosome arrangements for diurnal activity and show in dependence to other ecological data that internally fixed daily activity rhythm might exists in D. subobscura. Analysis of light, temperature and humidity factors in relation to the frequency data obtained indicate a choice of different ecological niche in a temporally structured habitat due to behavioural genetic information.     

Proximate mechanisms of the differences in reproductive success of males bearing different alleles of Pgdh – a gene involved in a sexual conflict in bulb mite

Enzyme polymorphism in phosphogluconate dehydrogenase (Pgdh) is a striking example of single gene polymorphism involved in sexual conflict in bulb mite Rhizoglyphus robini. Males homozygous for the S Pgdh allele were shown to achieve higher reproductive success than FF homozygous males, while negatively influencing fecundity of their female partners. Here, we investigate proximate mechanisms responsible for the increased reproductive success of SS males and find that the S allele is associated with shorter time until copulation, higher copulation frequency and increased sperm production. We also show that Pgdh alleles are probably codominant, with SS males gaining the highest reproductive success, FF males – the lowest – and FS‐heterozygous males taking an intermediate position in all fitness parameters differentiating males of different genotypes. Additionally, we confirm the negative effect that S‐bearing males impose on the fecundity of females they mate with, showing a clear pattern of interlocus sexual conflict. We discuss that this effect is probably associated with increased copulation frequency. Whereas, contrary to what we have predicted, the S allele does not cause increased general male mobility, we speculate that the S allele‐bearing males are more efficient in forcing copulation and/or detecting females.     

中国广州人备解素因子B遗传多态现象

本文应用高压琼脂糖电泳,继以免疫固定技术,对259名居住在广州市无亲缘关系的健康成年人进行了BF多态性分析。除了SS、FS、FF和SS07外,还观察到2种罕见杂合型,暂命名为SSGI和SFG2。计算出的基因频率分别为:FB~*S∶0.8668,BF~*F∶0.11979 BF~*S07∶0.0077,BF~*SG1∶0.0019,BF~*FG2∶0.0039。家系调查证实BF FG2确系一独立的变异型,并显示常染色体共显性遗传方式。     

Polymorphism at the REF(2)P Locus in DROSOPHILA MELANOGASTER: Preliminary Experiments concerning the Selection Mechanisms Involved in Its Maintenance

It has been shown previously that a polymorphism for two alleles of the ref(2)P locus is a regular feature of French natural populations of Drosophila melanogaster and that this is maintained in laboratory populations raised in cages. In this paper, an experimental population and egg-collection experiments are reported. Differential survival of the three genotypes would be the main factor leading to the equilibrium frequencies, working only in drastic conditions of larval competition.     

Measuring Selection Coefficients Affecting the Alcohol Dehydrogenase Polymorphism in DROSOPHILA MELANOGASTER

This paper describes a perturbation experiment on the frequency of the F and S Alcohol dehydrogenase (Adh) alleles of D. melanogaster. Fifty-four iso-female lines set up from three wild populations and with initial F frequencies of either 0.25, 0.50 or 0.75 were maintained on standard laboratory food medium at 22 degrees. At generations 4, 12 and 20 the lines were again scored for Adh gene frequencies. Maximum likelihood procedures were used to estimate selection coefficients for the Adh genotypes. An analysis of deviance was used to compare the coefficients against expectations under the hypotheses of neutrality and of constant values for the three base populations, and for the three initial gene frequency classes. Highly-significant departures from neutrality were observed; over all 54 lines, the set of relative fitnesses for S/S:F/S:F/F was estimated as 1.00:1.08:1.08. In addition, there were significant differences between lines in the outcome of selection which were not attributable to differences between base populations or initial F frequencies. These residual between-line differences, as well as some between-generation, within-line differences are discussed in terms of linkage disequilibria with background genes and electrophoretically cryptic variation at the Adh locus.     

Immunoelectron microscopic analysis of the binding of monoclonal antibodies to molecular variants of human placental alkaline phosphatase

Three monoclonal antibodies with distinct antigenic specificities were examined by electron microscopy for their binding to three common genetic variants (SS, FS, and FF) of human placental alkaline phosphatase. In the reaction with the monoclonal antibody H5, all three variants of human placental alkaline phosphatase preferentially formed circular immune complexes composed of two antibodies and two enzyme molecules. In separate reactions with the F11 and B2 monoclonal antibodies, the SS variant formed circular complexes and the FS variant formed Y-shaped complexes composed of one antibody and two enzyme molecules, whereas the FF variant scarcely reacted. These results confirm immunochemical data showing that H5 binds to both S and F subunits with similar affinities, whereas F11 and B2 bind the S subunit with markedly higher affinity than they do the F subunit. Furthermore, the formation of circular complexes in the reaction of the mixture of the two antibodies, F11 and B2, with FS molecules suggests that these two antibodies bind to different sites on the S subunit. Therefore, the F and S subunits differ from one another at more than one site. This is the first indication that alleles of human placental alkaline phosphatase may result from more than just single point mutations in the gene encoding them.     

An analysis of selection on a colour polymorphism in the northern leopard frog

In this study, we investigated the role of selection in the maintenance of a dorsal colour polymorphism in natural populations of the northern leopard frog, Rana pipiens. We determined genetic structure both spatially and temporally from a suite of putatively neutral molecular markers and tested whether or not the colour locus exhibited patterns of genetic variation that differed from those of the neutral loci. Spatial genetic structure at the colour locus was indistinguishable from structure at neutral loci [95% confidence intervals of F(ST) (neutral) = (0.07, 0.35), F(ST) (colour locus) = 0.114]. In the temporal analysis, we found that the variance among populations in the change in allele frequency at the colour locus (equal to 0.004) lies within the 95% confidence intervals for the variance among populations in changes in allele frequencies at neutral loci. In light of our inability to show evidence for the selective maintenance of the colour polymorphism, we used computer simulations to infer the power of our spatial and temporal techniques to detect selection. The computer simulations showed that although the strength of selection (s) would need to be relatively strong to have been detected by the temporal approach (s = 0.1-0.4, depending on the model tested), the spatial analysis would have detected all but weak selection (s = 0.01-0.04, depending on the model tested). This study illustrates the importance of using a locus comparison approach to detect evidence for selective maintenance before conducting studies to measure the selective mechanisms maintaining a polymorphism.     

Identification and mapping of a major dominant quantitative trait locus controlling seeds per silique as a single Mendelian factor in Brassica napus L.

One putative quantitative trait locus (QTL) for seeds per silique (SS), cqSS.A8, was identified using a double haploid (DH) population in Brassica napus, and near-isogenic lines (NILs; BC(3)F(1)) for cqSS.A8 were developed. However, the flanking markers from cqSS.A8 showed no significant difference using single-marker analysis, even though the frequency distribution of SS in the BC(3)F(1) was bimodal, suggesting that one novel locus existed. In this study, we characterized the effects of this locus in the NILs and used a published linkage map to determine its location. A three-step approach was designed for mapping the locus in the NILs (BC(3)F(2)): (1) determining the individual BC(3)F(2) genotype at the locus using a progeny test; (2) identifying amplified fragment length polymorphism (AFLP) markers linked to the locus using a combination of AFLP and bulked segregant analysis; and (3) determining the location and effects of this locus. QTL analysis in the BC(3)F(2) revealed that this locus explained 85.8 and 55.7 % of phenotypic variance for SS and SL, respectively. Its additive and dominant effects on SS were 6.1 and 5.7, respectively. The locus was validated using a DH population by composite interval mapping and located to linkage group C9 (designated as qSS.C9). Mapping qSS.C9 was undertaken using 230 extremely low-SS plants of a BC(4)F(1) population containing 807 plants. We found that qSS.C9 delimited a 1.005-Mb interval including 218 predicted genes in the reference Brassica rapa (Chiifu-401). These results will greatly facilitate map-based cloning of qSS.C9 and seed yield improvement in rapeseed.