Colour polymorphism and genetic variation in Idotea baltica populations from the Adriatic Sea and Baltic Sea

Phenotypic and genetic variation was studied in two of the four European subspecies of the marine isopod Idotea baltica; the Mediterranean I. b. basteri and the Baltic I. b. baltica. Spatial and temporal patterns of colour polymorphism were analysed in northern Adriatic and western Baltic Sea populations. Pronounced differences in phenotype composition were observed between populations of both subspecies as seen in the distribution of various colour variants bilineata, lineata, flavafusca and several combined forms). Compared with Adriatic samples, western Baltic Sea populations show higher phenotypic diversity. To obtain an estimate of the degree of genetic divergence between the subspecies, 12 gene-enzyme systems were investigated electrophoretically. The results obtained indicate a relatively high level of genetic variation; I. b. basteri from the nothern Adriatic tends to be more polymorphic and more heterozygous than I. b. baltica from the western Baltic. Both subspecies share identical electrophoretic mobilities of the homologous enzyme proteins examined; however, in allelic composition they exhibit significant differences at approximately half the number of loci scored. The genetic distance (Nei's D) measured at the subspecific level was 0.04. Amounts and geographical patterns of variation, observed both in colour phenotype and electrophoretic variation, are considered.     

Genetic diversity of four esterase loci in natural populations of Hordeum spontaneum C. Koch from Jordan

Summary The diversity of four esterase loci was studied electrophoretically in 690 individual spikes representing 12 populations of wild barley (Hordeum spontaneum C. Koch.) collected from central, peripheral and marginal regions of its distribution in Jordan. A minimum of 6, 10, 5 and 5 alleles were observed at the Est-1, Est-2, Est-4 and Est-5 loci, respectively. Est-2 and Est-4 were the most diverse loci (H_c=0.53±0.05 and 0.46±0.07, respectively). Est-5 was intermediate (H_c=0.33+0.07) and Est-1 was the lowest (H_c=0.22±0.04). Polymorphism was highest in the central populations (H_e=0.52±0.04), followed by the peripheral (H_e=0.40±0.05) and the marginal (H_e=0.22±0.05) populations. Average allelic diversity between (G_st=0.49) and within (H_s=0.51) populations reflects a high allelic differentiation among these populations. Log-linear analyses revealed that four two-locus terms and two three-locus terms were significantly associated (P<0.05). Geographical distances between populations were not significantly correlated with Nei's genetic similarity index (r=0.16; P<0.19). It is postulated that diversifying selection is a major factor in the population genetic differentiation of these esterase loci.     

Isozyme expression in F1 hybrids between carp and goldfish

Interspecific genetic differences in malate dehydrogenase (MDH), lactate dehydrogenase (LDH), superoxide dismutase (SOD), and esterase (EST) isozymes in carp (Cyprinus carpio) and goldfish (Carassius auratus) were used to examine the allelic expressions in the hybrid between these species. A unique liver SOD and muscle LDH phenotype unambiguously identifies all presumed hybrid individuals. There was no evidence of F₂ or backcross phenotypes in hybrid individuals. Liver MDH and EST phenotypes in hybrids show a preferential expression of goldfish isozymes. Variation in the levels of carp liver MDH isozymes may result from the polymorphism of a regulatory mutation affecting isozyme expression, leading to gene silencing after duplication.This work was supported through NSERC (Canada) grants to James P. Bogart and John F. Leatherland.     

High level of variation at Abies alba chloroplast microsatellite loci in Europe

Based on two polymorphic chloroplast microsatellites that had been previously identified and sequence characterized in the genus Abies, genetic variation was studied in a total of 714 individuals from 17 European silver fir (Abies alba Mill.) populations distributed all over the natural range. We found eight and 18 different length variants at each locus, respectively, which combined into 90 different haplotypes. Genetic distances between most populations were high and significant. There is also evidence for spatial organization of the distribution of haplotypes, as shown by permutation tests, which demonstrate that genetic distances increase with spatial distances. A large heterogeneity in levels of diversity across populations was observed. Furthermore, there is good congruence in the levels of allelic richness of the two loci across populations. The present organization of levels of allelic richness across the range of the species is likely to have been shaped by the distribution of refugia during the last glaciation and the subsequent recolonization processes.     

Esterase Polymorphism in Meloidogyne konaensis

The continual detection of a slow (I1) esterase band in greenhouse cultures of Meloidogyne konaensis isolated from the field led to a hypothesis that the nematode may be polymorphic for esterase. A survey of coffee fields demonstrated at least four esterase phenotypes were present in Meloidogyne recovered. An F1 phenotype predominated (60% of the females), but an I1 phenotype was also common (30% of samples). A series of greenhouse and laboratory experiments were undertaken to understand this polymorphism. Esterase phenotype was not affected by development at 22º, 25º, or 33 ºC on tomato. Two different esterase phenotypes (I1 and F1-I1) were detected after M. konaensis was grown on tomato for several generations, even in single-egg-mass lines derived from an F1 female. Three isolates of M. konaensis differing in esterase phenotype (F1, I1, and F1-I1) did not differ morphologically but did differ in their parasitic ability. Only the F1 isolate parasitized Coffea arabica. The F1-I1 isolate had greater reproduction on Lycopersicon esculentum and Cucumis sativus than either the I1 or F1 isolate. The mechanism of the development of the polymorphism has yet to be determined. However, the F1 esterase may be useful as a marker for future research on parasitism of coffee by M. konaensis.     

Genotyping an ALAD polymorphism with real-time PCR in two populations from the Iberian Peninsula

Lead-induced toxicity varies among individuals partly because of genetic differences in their susceptibility to the metal’s effects. One genetic polymorphism associated with lead toxicity is a G-to-C transversion at position 177 in the coding region of delta-aminolevulinic acid dehydratase (ALAD), originating from two codominant alleles (ALAD1 and ALAD2). We examined the distribution of this single nucleotide polymorphism in two populations from the Iberian Peninsula. Genomic DNA was extracted from whole blood, and a real-time PCR assay was designed to determine ALAD polymorphic distribution. The distribution of MspI polymorphism was similar in the two populations studied, and allelic frequencies were comparable to those obtained in other studies of Caucasians. Further studies are needed to assess fully the functional significance of this polymorphism and its influence on the toxicokinetics of lead.     

ESTERASE PHENOTYPES IN NATURAL POPULATIONS OF CULEX PIPIENS PALLENS (DIPTERA: CULICIDAE) AND THEIR VARIATIONS UNDER INSECTICIDE SELECTION*

Abstract Three populations of Culex pipiens pallens Coquillett, from Hangzhou, Linhai and Jinhua, were determined for their probability of resistant esterase phenotypes. Further, each population was selected with dipterex, chlorpyrifos, temephos and malathion at a given dose of 60%‐70% mortality and was determined for the variation of resistant esterase phenotypes in its offspring. The results indicated that esterase B₁ phenotype was dominant in three populations although different natural populations have a different probability distribution of esterase B phenotypes. Insecticide selection showed that various esterase loci seemed to have different selective advantages under different insecticide pressures. The esterase B₁ phenotype was selected under temephos, and the esterase B₂ phenotype was selected under dipterex and chlorpyrifos. Except for the esterase B₁ phenotype, the heterozygote of B₁/B₂ phenotypes was detected under malathion pressure. These results are discussed in relation to the selective advantages of esterase genes to OP pressure and mosquito control strategies.     

Characterization of six microsatellite loci in the mangrove cricket Apteronemobius asahinai

The mangrove cricket Apteronemobius asahinai is endemic to mangrove forest floors in China, Southeast Asia and the Ryukyu archipelago (Amamiohsima, Okinawa, Miyako, Ishigaki and Iriomote Islands) of Japan. We developed six polymorphic microsatellite markers for the mangrove cricket from genomic DNA libraries enriched for CA, GA, AAG and ATG motifs. The M13‐tailed primer method was used in the process of screening of amplification and polymorphism of primers. A total of 64 specimens from two populations (one from Okinawa and the other from Iriomote) were genotyped for allelic diversity. The average number of alleles per locus was 4.67 and 6.67 for Okinawa and Iriomote populations, respectively. A significant genetic differentiation was detected between the two populations (pairwise F_ST 0.2404). These polymorphic microsatellite loci will be useful in ongoing studies of the population genetic structure of the mangrove cricket including several populations in the Ryukyu archipelago.     

JP-3 gene polymorphism in a healthy population of Serbia and Montenegro

Expansions of CTG repeats inJP-3 gene are associated with a phenotype similar to Huntington disease. These expansions are the cause of Huntington disease like-2 (HDL-2) phenotype. CTG repeats inJP-3 gene are polymorphic in healthy population. Analyses of CTG repeat polymorphism ofJP-3 gene in various healthy populations could help in estimating the population at risk for developing HDL-2. CTG repeat polymorphism ofJP-3 gene was analysed in healthy population of Serbia and Montenegro. Study included 198 unrelated subjects. Analyses ofJP-3 locus were performed using PCR and sequencing. Six differentJP-3 alleles were obtained and they were in the range of 11 to 18 CTG repeats showing a bimodal distribution, with peaks at 14 and 16. Results show that the distribution ofJP-3 alleles in population of Serbia and Montenegro is consistent with distributions in other analysed populations. The absence of alleles with more then 18 CTG repeats suggests that HDL-2 is very rare in the populations of Serbia and Montenegro.     

LEAF ISOZYMES AS GENETIC MARKERS IN DATE PALMS

The date palm (Phoenix dactylifera L.) is a long-lived, dioecious, arborescent monocotyledon which must be propagated vegetatively by offshoots to maintain clones. An extensive breeding program begun in 1948 at Indio, California, to obtain superior lines has resulted in the production of several seedling populations of known parents. These were used to study the genetic control of isozymes of alcohol dehydrogenase, esterase, glutamate oxaloacetate transaminase, phosphoglucose isomerase and phosphoglucose mutase from leaf tissue. The five enzyme systems are specified by seven polymorphic genes with 14 alleles. Additional polymorphism was found in two other species of Phoenix. Twenty-six female and 20 male date palm cvs. were genotyped to provide, insofar as is known, the first single-gene markers for the date palm and perhaps for any arborescent monocotyledon.     

Genetic Diversity in Natural Populations of Arabidopsis thaliana (L.) Heynh. from Karelia

The genetic structure of ten natural populations of Arabidopsis thaliana (L.) Heynh. at eight isozyme loci was studied. The populations were located in the northern part of the species range, 200 km from the north to the south along the Onega Lake coast in Karelia. Considerable genetic diversity (P _99% = 43.7, H _obs = 0.003) was revealed that is not typical of populations of self-pollinating plant species. A direct correlation between the proportion of polymorphic loci and geographical latitude was shown (r = 0.68; P < 0.05). It is suggested that a high polymorphism level in Karelian Arabidopsis thaliana (L.) populations increasing from the south to the north is due to extreme environmental conditions in the northern part of the species range. The distribution of genetic diversity within and between populations is typical of self-pollinating species: the larger part of the total diversity resides among populations (G _ST = 0.583).     

Phylogeographic structure,demographic history and morph composition in a colour polymorphic lizard

In polymorphic species, population divergence in morph composition and frequency has the potential to promote speciation. We assessed the relationship between geographic variation in male throat colour polymorphism and phylogeographic structure in the tawny dragon lizard, Ctenophorus decresii. We identified four genetically distinct lineages, corresponding to two polymorphic lineages in the Northern Flinders Ranges and Southern Flinders Ranges/Olary Ranges regions respectively, and a monomorphic lineage in the Mt Lofty Ranges/Kangaroo Island region. The degree of divergence between these three lineages was consistent with isolation to multiple refugia during Pleistocene glacial cycles, whereas a fourth, deeply divergent (at the interspecific level) and monomorphic lineage was restricted to western New South Wales. The same four morphs occurred in both polymorphic lineages, although populations exhibited considerable variation in the frequency of morphs. By contrast, male throat coloration in the monomorphic lineages differed from each other and from the polymorphic lineages. Our results suggest that colour polymorphism has evolved once in the C. decresii species complex, with subsequent loss of polymorphism in the Mt Lofty Ranges/Kangaroo Island lineage. However, an equally parsimonious scenario, that polymorphism arose independently twice within C. decresii, could not be ruled out. We also detected evidence of a narrow contact zone with limited genotypic admixture between the polymorphic Olary Ranges and monomorphic Mt Lofty Ranges regions, yet no individuals of intermediate colour phenotype. Such genetic divergence and evidence for barriers to gene flow between lineages suggest incipient speciation between populations that differ in morph composition.     

Microsatellite markers reveal high allelic variation in natural populations of Cryptomeria japonica near refugial areas of the last glacial period

Using 11 microsatellite markers, we investigated the allelic variation and genetic structure of Cryptomeria japonica, across most of its natural distribution. The markers displayed high levels of polymorphism (average gene diversity=0.77, average number of alleles=24.0), in sharp contrast to the lower levels of polymorphism found in allozyme and cleaved amplified polymorphic sequence markers in previous studies. Little genetic differentiation was found among populations (F_ST=0.028, P<0.001), probably because the species is wind-pollinated and long-lived. No clear relationship between Neis genetic distances and geographical locations of the populations were found using the principal coordinate and unweighted pair-group method with arithmetic averaging analyses. The lack of such trends might be due partly to microsatellite homoplasy arising from mutation blurring the genealogical record. However, there was a trend towards high allelic diversity in five populations (Ashitaka, Ashiu, Oki-Island, Yakushima-Island-1 and -2), which are very close to, or in, refugial areas of the last glacial period as defined by Tsukada based on pollen analysis data and current climatic divisions. We postulate that these refugial populations might have been less affected by genetic drift than the other populations due to their relatively large size.     

Intraspecific Genetic and Morphological Variation in Earthworm <Emphasis Type="Italic">Eisenia foetida</Emphasis> (Sav.)

Polyacrylamide gel electrophoresis was used to study the allelic frequency distribution of four polymorphic loci (Pox, Lap, Pgm, and Odh) in 22 samples of Eisenia foetida (Sav.) from distant parts of the range: European Russia, Ukraine, Kazakhstan, and Kyrgyzstan. A hierarchical population structure was demonstrated for this species: local populations were integrated into spatial groups. Statistical analysis of morphological variation did not support assignment of any taxa rank to the spatial groups recognized on the basis of biochemical and genetic characters.__________Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 4, 2005, pp. 442–447.Original Russian Text Copyright © 2005 by Bolotetskii, Kodolova.     

Genetic diversity of Artemisia populations in central and north Saudi Arabia based on morphological variation and RAPD polymorphism

The analysis of morphological variation and RAPD polymorphism distinguished populations of A. herba alba from populations of A. judaica and A. monosperma. Higher morphological diversity is found in A. herba alba compared to the other two species, but molecular data derived from RAPD polymorphism also indicated that A. herba alba is more polymorphic than the other two species. However, RAPD fingerprinting also indicated sharp polymorphism among populations of both A. judaica and A. monosperma. Geographic and local ecological variations related to elevation of the sites of the examined populations may be regarded to have played a role in the genetic diversity of the examined populations of Artemisia species in the study area. The results are important for future plans for sustainable conservation of medicinal plants in Saudi Arabia. However, extensive sampling of the examined Artemisia species populations is required, and more regional data should be obtained from other distribution areas.     

不同地理种群尖音库蚊复组抗性动态和遗传多样性

通过生物测定、蛋白质电泳和等位酶分析等方法对5个不同地区的尖音库蚊复组蚊虫Culex pipiens complex的抗性水平、种群中非特异性酯酶基因表型分布和种群遗传多样性进行了研究。不同地理种群的抗性检测结果表明：5个种群分别对敌敌畏、对硫磷、氯菊酯和溴氰菊酯的抗性较高,对残杀威、巴沙和胺菊酯的抗性较低;朝阳种群对敌敌畏抗性最高（55.7倍）,武汉种群次之;佛山种群对氯菊酯和溴氰菊酯的抗性比率高达123倍和23.9倍。酯酶电泳结果显示：5个种群间酯酶多态性存在差异,广州和佛山两个库蚊种群酯酶表型多态性最高,有B1,A2-B2,A8-B8,A9-B9,B10和A11-B11等6种酯酶表型,提示高活性酯酶是主要的抗性机制。群体遗传学研究表明：每位点平均等位基因数（A）为2.76,平均多态位点百分率（P）为64.45％,平均预期杂合度（He）为0.1943,种群间遗传分化系数（Fst）值为0.10,平均基因流(Nm)＝2.57,说明5个种群有较丰富的遗传多样性,种群内遗传多样性高于种群之间。据此推测,种群间可以通过迁徙等方式进行基因交流,使得遗传结构、抗性水平朝一致性方向变化。本研究对我国尖音库蚊复组蚊虫的综合治理有一定指导意义。     

Allozyme variability in an invasive drosophilid,Zaprionus indianus (Diptera: Drosophilidae): comparison of a recently introduced Brazilian population with Old World populations

Colonizing species often go through genetic bottlenecks when new territories are invaded. The South American continent has been recently colonized by a generalist African drosophilid, Zaprionus indianus, which has become an agricultural pest in Brazil in the last five years. In this paper we used allozyme electrophoresis to estimate levels of genetic differentiation of Z. indianus collected from sites 4 300 km apart in Brazil. We also compared the level of polymorphism of the Brazilian populations with that found in laboratory strains from Africa and Asia, to verify if a significant decrease in gene variability has taken place during the invasion process. The populations were polymorphic for three out of the 11 loci investigated. Genetic distances and F_ST indices among Brazilian populations were small and generally non significant, suggesting a colonization from one single propagule followed by a rapid demographic expansion. Ancestral and old populations from Africa and Asia were slightly more heterozygous than those from Brazil. Compared to other drosophilids, Z. indianus appears to be characterized by a low proportion (25%) of polymorphic loci. We suggest that the propagule introduced to Brazil had a sufficient size to carry almost all the polymorphism from the (unknown) origin population, although not the precise allelic frequencies.     

Domestication does not narrow MHC diversity in Sus scrofa

The Major Histocompatibility Complex (MHC) is a multigene family of outstanding polymorphism. MHC molecules bind antigenic peptides in the peptide-binding region (PBR) that consists of five binding pockets (P). In this study, we compared the genetic diversity of domestic pigs to that of the modern representatives of their wild ancestors, the wild boar, in two MHC loci, the oligomorphic DQA and the polymorphic DRB1. MHC nucleotide polymorphism was compared with the actual functional polymorphism in the PBR and the binding pockets P1, P4, P6, P7, and P9. The analysis of approximately 200 wild boars collected throughout Europe and 120 domestic pigs from four breeds (three pureblood, Pietrain, Leicoma, and Landrace, and one mixed Danbred) revealed that wild boars and domestic pigs share the same levels of nucleotide and amino acid polymorphism, allelic richness, and heterozygosity. Domestication did not appear to act as a bottleneck that would narrow MHC diversity. Although the pattern of polymorphism was uniform between the two loci, the magnitude of polymorphism was different. For both loci, most of the polymorphism was located in the PBR region and the presence of positive selection was supported by a statistically significant excess of nonsynonymous substitutions over synonymous substitutions in the PBR. P4 and P6 were the most polymorphic binding pockets. Functional polymorphism, i.e., the number and the distribution of pocket variants within and among populations, was significantly narrower than genetic polymorphism, indicative of a hierarchical action of selection pressures on MHC loci.     

Polymorphism of esterase 11 in Mus musculus,a further esterase locus on chromosome 8

A further esterase, esterase 11, which exhibits a polymorphism detectable by electrophoresis, has been observed in the house mouse, Mus musculus. In 15 inbred strains and two outbred strains, the ES-11A phenotype has been found, composed of two bands of enzyme activity of greater anodal electrophoretic mobility than the two bands of the ES-11B phenotype found in one inbred strain, one wild stock, and 101 wild mice. In F₁ hybrids (IS/Cam×C57 BL/Gr), the phenotype shown corresponds to a mixture of the two parental phenotypes. In backcrosses, ES-11 segregates as an autosomal gene, designated Es-11, closely linked to Es-2 and Es-5 on chromosome 8.This work was supported by the Medical Research Council.     

Preliminary data on the genetic differentiation of Mytilus desolationis Lamy 1936 and Aulacomya ater regia Powell 1957 (Bivalvia,mytilidae) in the Kerguelen Islands (Terres Australes et Antarctiques Françaises)

Summary Mussel populations in the Kerguelen Islands constitute an excellent model in which to study genetic differentiation, because of the exceptional geographic position of the islands with consequent very low external gene flow, the variety of biotopes that they occupy and their abundance there. Enzyme polymorphism and the electrophoretic variability of some loci have been studied in four populations of Mytilus desolationis Lamy 1936 and in four other populations of Aulacomya ater regia Powell 1957. In both species 67% of the loci were polymorphic. The electrophoretic variability of ACP-2, LAP-1, LAP-2, PGI and PGM in M. desolationis populations, and of ACP-2, LAP-1, LAP-2 and MDH in A. ater regia populations was analyzed by correspondence analysis. For M. desolationis the four populations studied were found to be heterogeneous; four loci contribute clearly to this differentiation. The populations from sheltered and exposed areas were distinguishable on the basis of the allelic frequencies of LAP-1 and LAP-2. The allelic frequencies of PGI and PGM allow further differentiation of the populations. For A. ater regia the four populations studied were distinguishable on the basis of the allele frequencies of ACP-2 and LAP-1 and the differences could not actually be related to their environmental conditions.