Genetic variability of proteins from plasma membranes and cytosols of mouse organs

The genetic variability of membrane proteins (structure-bound proteins) and cytosol proteins (water-soluble proteins) was investigated in two inbred strains of the mouse, C57BL/6J and DBA/2J. Membrane proteins and cytosol were isolated from the brain and liver of the mouse. The proteins were separated by two-dimensional electrophoresis. A high number of genetic variant proteins (brain, 30; liver, 72) was found in the cytosol. Most of these variants represented changes in the amount of proteins. Electrophoretic mobility changes occurred only in about 1% (brain, 6; liver, 9) of all protein spots of a two-dimensional pattern. In contrast to the cytosol proteins, no genetic variation was detected among the membrane proteins, not even for the quantitative characteristics of the protein spots. The results obtained for the two classes of proteins suggest that the degree of variability in the amount of proteins is related to the degree of variability in the structure of proteins.     

Population genetics of Anastrepha fraterculus (Diptera,Tephritidae) in different hosts: Genetic differentiation and heterozygosity

An allozymic survey of 11 populations of Anastrepha fraterculus Wied. (Diptera, Tephritidae) in 8 different hosts from the same orchard revealed very small levels of genetic distance (D = 0.002±0.001) between hosts. The data thus provide no evidence for host-dependent genetic differentiation. Low values of heterozygosity were observed (H = 0.050±0.28) and 6 loci out of 11 were monomorphic. Biological attributes of the species, such as its polyphagic regime, multivoltine pattern of reproduction, and seasonal changes in population size, are discussed in an attempt to explain the low variability.     

Genetic variability and population structure of grey wolf (<Emphasis Type="Italic">Canis lupus</Emphasis>) in Serbia

Results of previous morphometric and genetic analyses of grey wolf (Canis lupus L.) population from Serbia indicated different patterns of population subdivision. In order to explore population structure, level of genetic variability, genetic drift, inbreeding and signals of bottleneck for grey wolves from Serbia, we applied highly polymorphic genetic markers (microsatellites). Obtained data are valuable in determination of conservation units and creation of appropriate management plans. We have amplified 18 highly polymorphic microsatellites, in a total sample of 75 grey wolves, from different localities across Serbia and multilocus genotypes were analyzed using appropriate software. Observed values of the basic genetic parameters (H_O = 0.69; H_E = 0.75) indicated moderate level of genetic variability, similar to genetic variability in other populations belonging to the Dinaric-Balkan population of grey wolf. In STRUCTURE analysis, although ΔK was estimated to be at first peak K = 2, and second peak K = 4, CLUMPAK analyses showed that there’s no structuring for any of assumed K, and therefore the population of grey wolf from Serbia may be considered as one continuous population and treated as one conservation unit in future management plans. Signals of bottleneck haven’t been observed (Wilcoxon test two phase mutation model p = 0.247; and stepwise mutation model p = 0.815).     

Heritability of dominant–aggressive behaviour in English Cocker Spaniels

A total of 51 seven-week-old English Cocker Spaniel puppies were measured for dominant–aggressive behaviour using the Campbell Test. The dogs consisted of a F₁ full sibs and half sibs from matings of 4 sires with 10 dams. The purpose of this study was to determine if the variability observed in this behavioural characteristic has an additive genetic component and if so, to estimate heritability (h²). Coat colour and sex were examined as fixed effects.

According to the results of the study: (1) there are highly significant differences between sexes; with males being more dominant than females, regardless of coat colour; (2) there are highly significant differences in aggressive behaviour depending on coat colour with greater to lesser dominance found in golden, black and particolour coats in that order; (3) there is no interaction between sex and colour when exhibiting greater or lesser dominance; (4) heritability, estimated on sire components, is , indicating that the variability observed in dominant–aggressive behaviour is in part due to genetic factors; and (5) heritability estimated on dam components is , which implies that the maternal effect (genetic and environmental) is an important factor in this type of behaviour.

It is concluded that there is an additive genetic, and therefore, hereditary factor for dominant–aggressive behaviour in the English Cocker Spaniel. Some of the fixed factors include: sex (males are dominant over females), coat colour (golden-coated are the more dominant dogs followed by the black-coated and finally by the particolour coat dogs) and the common environmental effect due to litter.     

The level of genetic variability of cells in prolonged suspension culture of Arabidopsis thaliana

The level of heterogeneity and genetic variability of cells in a suspension of Arabidopsis thaliana cultured in vitro for more than seven years was studied. The considerable heterogeneity of the suspension in cell size was shown. As revealed by nuclear DNA cytophotometry, the suspension culture was mixoploid and the amount of DNA in the cells varied from 4 to 16 C. However, PCR with 6 RAPD- and 4 ISSR-primers and their intragroup combinations showed the lowest degree of variability of DNA markers. The genetic distances of clones obtained from a suspension culture of the parent plant were only 1.5%. Differences between the clones were identified with only one pair of 31 primer combinations tested, indicating low level of genetic heterogeneity of the suspension. The results showed that variations in the amount of DNA in the suspension culture cells are not accompanied by significant changes in the DNA sequence.     

Genetic differentiation in the polyploid complex of <Emphasis Type="Italic">Suaeda corniculata</Emphasis> (C.A. Mey.) Bunge in Eastern Siberia

Data on differentiation of the polyploid complex of Suaeda corniculata (C.A. Mey.) Bunge in East Siberia based on variability of morphological characteristics, karyological analysis, and genetic polymorphism in inter simple sequence repeat (ISSR) markers were given for the first time. It was established that the samples studied belonged to three cytotypes: diploids (2n = 2x = 18), tetraploids (2n = 4x = 36) and hexaploids (2n = 6x = 54). The analysis of variability of morphological characteristics by the method of principal coordinates showed division of the samples into three separate groups. On the basis of morphological and molecular-genetic methods, a genetically differentiated diploid population was revealed in Yakutia.     

Genetic variability and structure of an isolated population of <Emphasis Type="Italic">Ambystoma altamirani</Emphasis>, a mole salamander that lives in the mountains of one of the largest urban areas in the world

Amphibians are globally threatened by habitat loss and fragmentation; species within the order Ambystoma are not the exception, as there are 18 species of mole salamanders in México, of which 16 are endemic and all species are under some national or international status of protection. The mole salamander, Ambystoma altamirani is a microendemic species, which is distributed in central México, within the trans-Mexican volcanic belt, and is one of the most threatened species due to habitat destruction and the introduction of exotic species. Nine microsatellite markers were used to determine the genetic structure, genetic variability, effective population size, presence of bottlenecks and inbreeding coefficient of one population of A. altamirani to generate information which might help to protect and conserve this threatened species. We found two genetic subpopulations with significant level of genetic structure (\(F_{\mathrm{ST}}= 0.005\)) and high levels of genetic variability (\(H_{\mathrm{o}}= 0.883\); \(H_{\mathrm{e}}= 0.621\)); we also found a small population size (\(N_{\mathrm{e}} = 8.8\)), the presence of historical (\(M =\) 0.486) and recent bottlenecks under IAM and TPM models, with a low, but significant coefficient of inbreeding (\(F_{\mathrm{IS}} = -\)0.451). This information will help us to raise conservation strategies of this microendemic mole salamander species.     

Variability of nuclear microsatellite loci in the populations of Siberian dwarf pine (<Emphasis Type="Italic">Pinus pumila</Emphasis> (Pallas) Regel) from the Russian part of the range

Variability of nuclear microsatellite loci was examined in Siberian dwarf pine. Six microsatellite loci (RPS2, RPS6, RPS12, RPS124, RPS127, Pc18) demonstrated different polymorphism levels in ten populations of Siberian dwarf pine. The average number of alleles per locus was 4.88, the average observed heterozygosity was 0.465, and the average expected heterozygosity was 0.510. About 13% of total genetic variability was explained by the genetic differences between the populations (F _ST = 0.129). Genetic distances between the examined populations of Pinus pumila inferred from the data on the SSR marker frequencies statistically significantly correlated with the geographical distances between the population samples. The level of genetic variability of the populations from Kamchatka Peninsula was lower than that demonstrated by continental and island populations. The genetic differentiation of the Kamchatka–Magadan and other populations of Siberian dwarf pine observed in our study can be explained in terms of their formation from different Pleistocene refugial centers.     

Population genetics of <Emphasis Type="Italic">Collisella subrugosa</Emphasis> (Patellogastropoda: Acmaeidae): evidence of two scales of population structure

Marine invertebrate populations usually show high levels of genetic variability that has frequently been associated with spatial and temporal environmental heterogeneity. One of the most heterogeneous marine environments is the intertidal zone, the habitat of Collisella subrugosa, the most widespread and abundant Brazilian limpet. C. subrugosa has planktonic larvae that can disperse over long distances, what can promote gene flow among shores, working against interpopulational differentiation. In this study we investigated the genetic variability and populational substructure of C. subrugosa through analysis of 24 allozyme loci in 14 samples (590 individuals) collected along 2,700 km of the Brazilian coast. The genetic variability was high ( and ), as expected for intertidal species. Genetic differentiation among samples was low (F _ST = 0.03) what may reflect intensive gene flow associated with larval dispersal. However, we detected an isolation-by-distance pattern of population substructure in one sampled region. High levels of heterozygote deficiency were also observed for many loci in each sample. Alternative hypothesis are discussed, and the “breeding groups” is suggested to explain these pattern, indicating the main cause as environmental heterogeneity.     

Genetic structure and inter-generic relationship of closed colony of laboratory rodents based on RAPD markers

Molecular genetic analysis was performed using random amplified polymorphic DNA (RAPD) on three commonly used laboratory bred rodent genera viz. mouse (Mus musculus), rat (Rattus norvegicus) and guinea pig (Cavia porcellus) as sampled from the breeding colony maintained at the Animal Facility, CSIR-Indian Institute of Toxicology Research, Lucknow. In this study, 60 samples, 20 from each genus, were analyzed for evaluation of genetic structure of rodent stocks based on polymorphic bands using RAPD markers. Thirty five random primers were assessed for RAPD analysis. Out of 35, only 20 primers generated a total of 56.88 % polymorphic bands among mice, rats and guinea pigs. The results revealed significantly variant and distinct fingerprint patterns specific to each of the genus. Within-genera analysis, the highest (89.0 %) amount of genetic homogeneity was observed in mice samples and the least (79.3 %) were observed in guinea pig samples. The amount of genetic homogeneity was observed very high within all genera. The average genetic diversity index observed was low (0.045) for mice and high (0.094) for guinea pigs. The inter-generic distances were maximum (0.8775) between mice and guinea pigs; and the minimum (0.5143) between rats and mice. The study proved that the RAPD markers are useful as genetic markers for assessment of genetic structure as well as inter-generic variability assessments.     

Seed protein and isozyme variations in Triticum tauschii (Aegilops squarrosa)

Sixty Triticum tauschii (Aegilops squarrosa, 2n=2x=14, DD) accessions were evaluated for the variability of high-molecular-weight (HMW) glutenins, gliadins and isozymes of seed esterase, -amylase and glucose-phosphate isomerase. Wide variability was observed for HMW-glutenins and gliadins. The implications of unique HMW-glutenin alleles for quality parameters are discussed. Isozyme evaluations indicated more variability for the Est-D ^t 5 locus as compared to the Est-D5 of bread-wheat. The polymorphism for -Amy-D ^t 1 was less than that of -Amy-D1. Similar to the bread-wheat situation, Gpi-D ^t 1 showed no polymorphism. The variability observed with the traits evaluated can be readily observed in T. turgidum x T. tauschii synthetic hexaploids (2n=6x=42, AABBDD) suggesting that T. tauschii accessions may be a rich source for enhancing the genetic variability of T. aestivum cultivars.     

Independence of genetic geographical variation between photoperiodic diapause, circadian eclosion rhythm, and Thr-Gly repeat region of the period gene in Drosophila littoralis

Drosophila littoralis is a latitudinally widespread European species of the Drosophila virilis group. The species has ample genetic variation in photoperiodism (adult diapause) and circadian rhythmicity (pupal eclosion rhythm), with adaptive latitudinal clines in both of them. The possible common genetic basis between the variability of photoperiodism and circadian rhythms was studied by a long-term crossing experiment. A northern strain (65 degrees N) having long critical day length (CDL = 19.9 h) for diapause, early phase of the entrained rhythm in LD 3:21 (psi(LD3:21) = 12.3 h), and short period (tau= 18.8 h) of the free-running rhythm for the eclosion rhythm was crossed with a southern strain (42 degrees N) having short CDL (12.4 h), late eclosion phase (psi(LD3:21) = 20.2 h), and long period (tau= 22.8 h). After 54 generations, including free recombination, artificial selection, and genetic drift, a novel strain resulted, having even more "southern" diapause and more "northern" eclosion rhythm characteristics than found in any of the geographical strains. The observed complete separation of eclosion rhythm characteristics from photoperiodism is a new finding in D. littoralis; in earlier studies followed for 16 generations, the changes had been mostly parallel. Evidently, the genes controlling the variability of the eclosion rhythm and photoperiodism in D. littoralis are different but closely linked. To test for the possible gene loci underlying the observed geographical variability, the period gene was studied in 10 strains covering all the known clock variability in D. littoralis. The authors sequenced the most suspected Thr-Gly region, which is known to take part in the adaptive clock variability in Drosophila melanogaster. No coding differences were found in the strains, showing that this region is not included in the adaptive clock variability in D. littoralis.     

Population genetic structure of wild-growing ginseng (Planax ginseng C. A. Meyer) assessed using AFLP markers

Genetic variability in ten populations of wild-growing ginseng was assessed using AFLP markers with the application of fragment analysis on a genetic analyzer. The variation indices were high in the populations (P = 55.68%; H(S) = 0.1891) and for the species (P = 99.65%; H(S) = 0.2857). Considerable and statistically significant population differentiation was demonstrated (theta = 0.363; Bayesian approach, "full model"; F(ST) = 0.36, AMOVA). The results of AMOVA and Bayesian analysis indicate that 64.46% of variability is found within the populations. Mantel test showed no correlation between the genetic and geographic distances among the populations (r = -0.174; P = 0.817). Hierarchical AMOVA and analysis of genetic relationships based on Euclidean distances (NJ, PCoA, and MST) identified two divergent population groups of ginseng. Low gene flow between these groups (N(m) = 0.4) suggests their demographic independence. In accordance to the concept of evolutionary significant units (ESU), these population groups, in terms of the strategy and tactics for conservation and management of natural resources, should be treated as management units (MUs). The MS tree topology suggests recolonization of southern Sikhote-Alin by ginseng along two directions, from south and west.     

Bryophyte diaspore bank: a genetic memory? Genetic structure and genetic diversity of surface populations and diaspore bank in the liverwort Mannia fragrans (Aytoniaceae)

Propagule banks are assumed to be able to store considerable genetic variability. Bryophyte populations are expected to rely more heavily on stored propagules than those of seed plants due to the vulnerability of the haploid gametophyte. This reliance has important implications for the genetic structure and evolutionary potential of surface populations. A liverwort, Mannia fragrans, was used to test whether the bryophyte diaspore bank functions as a "genetic memory." If a diaspore bank is capable of conserving genetic variability over generations, the levels of genetic diversity in the soil are expected to be similar or higher than at the surface. Surface and diaspore bank constituents of two populations of M. fragrans were investigated. Genetic structure and diversity measured as unbiased heterozygosity were analyzed using three ISSR markers. Similar genetic diversities were found in the soil (H(s) = 0.067) and at the surface (H(s)= 0.082). However, more haplotypes and specific haplotype lineages were present in soil samples. The results suggest that the bryophyte diaspore bank has an important role in accumulating genetic variability over generations and seasons. It is postulated that the role of the diaspore bank as a "genetic memory" is especially important in species of temporarily available habitats that have long-lived spores and genetically variable populations.     

Genetic Variation Within and Among Metal-Tolerant and Non-Tolerant Populations of Armeria maritima (Mill.) Willd. s.l. (Plumbaginaceae) in Central and Northeast Germany

Abstract: Six metal-tolerant populations and sub-populations of Armeria maritima ssp. halleri, ssp. hornburgensis, and ssp. bottendorfensis and two non-tolerant populations of ssp. elongata in Central and Northeast Germany have been analysed using RAPD markers. The populations show very strong genetic differentiation (Φ_ST = 0.46), corresponding gene flow between them is low (N_em = 0.29). A moderate positive correlation between the matrices of genetic and geographical distances was found between the seven populations and sub-populations of central Germany (r = 0.68, p < 0.001). Calculated parameters of genetic variability are molecular variance, percentage of heterozygosity and percentage of polymorphic loci. A significant correlation between population size and parameters of genetic variability was not recognisable. Genetic structure was investigated by an analysis of molecular variance (AMOVA). The studied populations show strong genetic differentiation. Genetic variation within populations ("normal" as well as metalliferous) is higher (53.9 %) than among them (46.1 %). Six hypotheses of possible genetic relatedness between the studied populations have been tested by AMOVA. A data set structure above the populational level is hardly recognisable. It was impossible to combine the populations to edaphic (tolerant and "non-tolerant") or taxonomic groups. A. maritima ssp. halleri of the north Harz mountains and ssp. hornburgensis are clearly separated from a geographical group containing all other populations (across taxonomic and edaphic boundaries). These results are a further indication for a polyphyletic origin of metal-tolerant populations of A. maritima s.l. by multiple colonizations of metalliferous sites from neighbouring populations on non-metalliferous soil.     

Allozymic variation of the endangered killifishAphanius iberus and its application to conservation

Synopsis Genetic differentiation and patterns of variability in the endangered Iberian endemic,Aphanius iberus, were analyzed by allozyme electrophoresis as a valuable database for conservation purposes. Genetic variability values expressed as heterozygosity (H = 0.015–0.097) were close to the values found in other members of Cyprinodontidae (H = 0.012–0.123). Polymorphism values (P = 0.125–0.542) were higher than reported in the literature (P = 0.036–0.150) for Cyprinodontidae. Significant correlation existed between salinity values and genetic variability expressed as heterozygosity (r = – 0.76, p < 0.01) and polymorphism (r = – 0.60, p = 0.04). Low genetic variability values (H = 0.024–0.055, P = 0.125–0.292) were exhibited by populations which inhabit salty lagoons. The highest values were found in populations occurring in marshes and irrigation channels (H = 0.051–0.097, P = 0.250–0.542). Associations among genetic, geographic and ecological parameters were tested using a Mantel test indicated that most of the genetic distances were explained by geographic distances but not by ecological factors, suggesting that isolation by distance could be the main factor explaining the differentiation between sites. According to the genetic distances obtained, two mainA. iberus groups were discernible: the Atlantic and Mediterranean. Genetic distances between both groups (DRogers = 0.179–0.261) were higher than values between recognized species of other cyprinodontids (DRogers = 0.11–0.27). On the basis of genetic distances we have dated the fragmentation of both populations to the Upper Miocene-Pliocene when most of the Mediterranean sea dried up. Subsequently, gene flow between Mediterranean and Atlantic populations was interrupted. The results of our genetic analyses suggested the existence of five operational conservation units (OCUs) forA. iberus. These units are defined as a continuous area limited by geographical boundaries, and inhabited by one or more populations sharing the same genetic pattern.     

Genetic diversity and population structure of <Emphasis Type="Italic">Taxus cuspidata</Emphasis> Sieb. et Zucc. ex Endl. (Taxaceae) in Russia according to data of the nucleotide polymorphism of intergenic spacers of the chloroplast genome

The genetic diversity and population structure of Taxus cuspidata Sieb. et Zucc. ex Endl. on the Russian part of its range was studied for the first time on the basis of the nucleotide polymorphism of intergenic spacers psbA–trnH, trnL–trnF, and trnS–trnfM of chloroplast DNA. A high level of gene (h = 0.807) and nucleotide (π = 0.0227) diversity was revealed. The data of AMOVA showed that the interpopulation component accounted for 12% of genetic variability (F _ST = 0.12044, P = 0.0000). We revealed 15 haplotypes, four of which were shown to be unique. The presence of common haplotypes in the majority of populations, the absence of phylogenetic structure, and low values or even the absence of nucleotide divergence show that the T. cuspidata populations studied are fragments of the once common ancestor population. Geographical isolation, which resulted from climatic changes in the Pleistocene–Holocene, as well as from human activities, did not produce a significant effect on the genetic structure of the species.     

Allozyme variation among and within eleven Orchis species (fam. Orchidaceae), with special reference to hybridizing aptitude

The electrophoretic variability of nine enzymatic loci was studied in 31 populations of eleven species of the genus Orchis (fam. Orchidaceae). This orchid group shows a higher degree of genetic variability ( ) than reported by Gottlieb (Progr. Phytochem. 7:1–46, 1981) for other outbreeding plant species ( ).Furthermore, the Nei coefficients of genetic identity show a higher biochemical-genetic similarity between species pairs of which we found the hybrids ( ) than between other species pairs ( ). These results seem to indicate a correlation between hybridizing aptitude and degree of genetic similarity. High values could be partially attributed to the presence of a gene flow between two species which, by hybridizing, would join their genetic pools. But they could also indicate that hybridizing species are not well differentiated: the isozyme similarity would reflect a more general similarity of the gene pool that could lead to hybrid formation.     

Strong genetic differentiation of the East-Himalayan <Emphasis Type="Italic">Megacodon stylophorus</Emphasis> (Gentianaceae) detected by Inter-Simple Sequence Repeats (ISSR)

Megacodon stylophorus (Clarke) Smith is a perennial alpine herb endemic to the species-rich eastern Himalayan region. Its populations are locally scattered as isolated patches throughout this region. Genetic variation within and among six populations of this species was assessed using ISSR fingerprinting with 13 primers. High levels of genetic diversity exist within species (P = 69.83%, H_T = 0.1949 and H_sp = 0.3047), while the within-population diversity is low (P = 11.21%, H_E = 0.0532 and H_pop = 0.0792). Extraordinarily high levels of genetic differentiation were detected among populations based on various statistics, including Neis genetic diversity analysis (72.7%), Shannons diversity index (74.01%) and AMOVA (80.70%). That is, populations shared low levels of genetic identity (I = 0.8203 ± 0.0430). This genetic structure was probably due to severe genetic drift of the small-sized patchy populations resulting from postglacial habitat fragmentations. The observed genetic structure of the populations implies that as many populations as possible should be considered for any in situ and ex situ conservation practice on this species.     

Study of electrophoretic variability in Epipactis helleborine (L.) Crantz,E. palustris (L.) Crantz and E. microphylla (Ehrh.) Swartz (fam. Orchidaceae)

Allozymic variation in seven enzymes coded by eight loci was studied in seven populations of terrestrial Epipactis orchids, including four populations of E. helleborine, one population of E. palustris and two of E. microphylla, from Latium (Central Italy).Heterozygosity estimates reveal that E. helleborine (EH) is the most variable species (HET=0.233; P=0.59; A=1.8), followed by E. palustris (EP) (HET=0.085; P=0.29; A=1.3) while E. microphylla (EM) is monomorphic for all the loci examined.It is suggested that the two EM populations examined, with a total lack of genetic variability, could originate from the same genetically impoverished ancestral population. Also the low variability amount of EP can be ascribed to genetic drift, probably due to a founder event.Nei's identity coefficients were also calculated. These show a high similarity in EH (=0.987) and EM (=1.000) populations. Average identity value between EP and EM is 0.289, between EP and EH is 0.336 and between EM and EH is 0.784. These data reveal that E. palustris presents a remarkable genetic, besides geographical and ecological, differentiation.