PGI Locus Research Articles

Eutrophication‐driven eco‐evolutionary dynamics indicated by differences in stoichiometric traits among populations of Daphnia pulicaria

Abstract Microevolution can have consequences at higher levels of ecological organization. Although divergence among populations can be rapid and driven by anthropogenic changes to the environment, the ecological relevance of evolution induced by human activities remains poorly understood. A frequent way in which human activities drive microevolution is the increase in supply of nutrients such as phosphorus (P) that are required for fitness‐relevant traits such as growth and reproduction. Because higher P concentrations decrease P‐use efficiency and feeding rate in heterotrophic consumers such as Daphnia, we hypothesized that such adjustments should alter consumer–resource dynamics. We examined how cultural eutrophication in temperate lakes causes trait variation in the grazer Daphnia pulicaria. We tested for variation in Daphnia traits and genetic variation in the metabolic enzyme phosphoglucose isomerase (Pgi) which are each known to respond to eutrophication. We then examined the impact of this variation on consumer–resource dynamics using a combination of experiments and a multi‐lake survey. We found that Daphnia from hypereutrophic lakes responded to experimental hypereutrophic conditions with increased growth rates and fecundity when raised on P‐fertilized seston, but had reduced performance on P‐poor seston relative to eutrophic source Daphnia. These results suggest that Daphnia may face a trade‐off in performance at low versus excess P that may be mediated in part by genetic variation at the Pgi locus. The variation observed in laboratory growth experiments scaled up to Daphnia populations in both mesocosm experiments and among lakes. In both the mesocosm experiment and in the lake survey, Daphnia from hypereutrophic source lakes reached high biomass while phytoplankton biomass also remained high. Given the prevalence and rapid eutrophication of freshwater ecosystems worldwide, these results indicate that considering the potential effects of evolutionary change in ecosystem models could be useful in forecasting the effects of anthropogenic environmental change on pivotal ecosystem services.

Genetic structure of the populations of Dactylorhiza ochroleuca and D. incarnata (Orchidaceae) in the area of their joint growth in Russia and Belarus

We carried out an allozyme analysis to investigate polymorphism and genetic structure of the populations of D. incarnata and D. ochroleuca in regions of their joint growth in Russia and Belarus. We found that D. ochroleuca individuals in the populations of the Urals and Siberia, which are distant fragments from the main range of the species, do not differ significantly from individuals within the main part of the area (Belarus) on the basis of the allelic composition of eight gene loci. We revealed that D. ochroleuca and D. incarnata are differentiated by different alleles of the GDH locus. Thus, we established a genetic marker suitable to distinguish these closely related taxa. In addition to the GDH locus, D. ochroleuca and D. incarnata in the places of their joint growth, differ in the allelic structure of the PGI and NADHD loci. D. incarnata from the Urals and Siberia were polymorphic for both loci, and individuals from Belarus were polymorphic for one locus (PGI). In contrast, all D. ochroleuca individuals growing in sympatric populations with polymorphic D. incarnata were homozygous for the same alleles. Thus, comparison of the genetic structure of D. ochroleuca and D. incarnata points to the existence of a genetic isolation and a functioning isolation mechanism even under conditions of their joint growth. We found that the GDH locus in D. incarnata is polymorphic only in populations which grow together with D. ochroleuca, with exception a few examples. Thus, we conclude that variability of the GDH locus in D. incarnata is associated with hybridization with D. ochroleuca.

Allopolyploid speciation in Siberian Dactylorhiza (Orchidaceae, Orchidoideae)

Morphological and allozyme analyses of Siberian dactylorchids have revealed the presence of a new, previously undescribed allopolyploid that is described here as species new to science. The genetic constitution as revealed by allozyme analysis of this species confirms that its parents are the diploid Siberian D. fuchsii and D. incarnata, and it is 2n=80, representing the first such count from the Asiatic Russia. In most literature surveys of Siberia, the new species has been identified as D. baltica, which is different in the allele composition of the pgi locus. Morphologically, both allotetraploids are similar; D. sibirica is distinguishable due to the absence of spots on the leaves and a narrower lip with narrower lateral lobes. A brief summary of Dactylorhiza allopolyploids from Siberia (Russia) is presented.

Phosphoglucose isomerase (PGI) polymorphism in Sorbus torminalis (L.) Crantz

Dormant buds of individual <em>Sorbus torminalis</em> trees collected from eight Polish populations were tested with horizontal gel electrophoresis according to one locus of PGI enzyme system. Three allozymes of different frequency were identified in each population. Genetic variability based on PGI locus A was high within seven populations (mean Ho=0.602 and mean Pg=0.491). Only one population with A3A3 genotypes was monomorphic, most probably due to intensive vegetative propagation or founder effect. The level of genetic differences among populations based on one variable locus reached GST=0.13.

Relationship of reasons and fears of treatment with outcome in substance using population attending a de-addiction centre.

Background:Substance users approach a treatment facility for a variety of reasons as well as avoid or delay in help seeking due to perceived fears with treatment facilities. Sometimes these factors might be associated with treatment outcomes.Objectives:We studied the relationship of reasons and fears of treatment seeking with treatment outcome in substance users.Materials and Methods:One hundred subjects, attending the Drug Deaddiction and Treatment Centre, PGIMER, were prospectively recruited by purposive sampling. A semistructured proforma was used to gather sociodemographic and clinical data. Reasons of help-seeking and fear questionnaire, social support scale, and PGI locus of control scale were then applied. Followup data were available for 69 patients, which were classified into good or poor outcome based on relapse status.Results:At 6 months followup, 22 patients had relapsed, while 47 patients did not relapse. A higher degree of dysfunction due to substance at baseline was associated with relapsed status at followup. Parents or guardians coming to know about resuming substance and being unemployed for a long time were the reasons associated with relapsed status, while needing to consult a doctor immediately was significantly related to abstinent status at followup. Fear of not being able to meet substance using friends was associated with a poorer outcome in the form of relapse.Conclusions:Reasons for treatment seeking as well as fears related to treatment have significant implications on the clinical outcome of substance abusing patients. Addressing these could help in better patient outcomes.

Diversifying Selection Underlies the Origin of Allozyme Polymorphism at the Phosphoglucose Isomerase Locus in Tigriopus californicus

The marine copepod Tigriopus californicus lives in intertidal rock pools along the Pacific coast, where it exhibits strong, temporally stable population genetic structure. Previous allozyme surveys have found high frequency private alleles among neighboring subpopulations, indicating that there is limited genetic exchange between populations. Here we evaluate the factors responsible for the diversification and maintenance of alleles at the phosphoglucose isomerase (Pgi) locus by evaluating patterns of nucleotide variation underlying previously identified allozyme polymorphism. Copepods were sampled from eleven sites throughout California and Baja California, revealing deep genetic structure among populations as well as genetic variability within populations. Evidence of recombination is limited to the sample from Pescadero and there is no support for linkage disequilibrium across the Pgi locus. Neutrality tests and codon-based models of substitution suggest the action of natural selection due to elevated non-synonymous substitutions at a small number of sites in Pgi. Two sites are identified as the charge-changing residues underlying allozyme polymorphisms in T. californicus. A reanalysis of allozyme variation at several focal populations, spanning a period of 26 years and over 200 generations, shows that Pgi alleles are maintained without notable frequency changes. Our data suggest that diversifying selection accounted for the origin of Pgi allozymes, while McDonald-Kreitman tests and the temporal stability of private allozyme alleles suggests that balancing selection may be involved in the maintenance of amino acid polymorphisms within populations.

Phosphoglucose isomerase genotype effects on life history depend on latitude and food stress

Summary1.Phosphoglucose isomerase (Pgi) genotypes differ in life‐history traits and shifts in their frequencies are thought to contribute to latitudinal gradients in life history. Yet, it is unstudied whether the life‐history effects of Pgi are invariant across latitudes. Further, while genetic variation at the Pgi locus is thought to be maintained by genotype‐by‐environment interactions and by life‐history trade‐offs involving resource allocation, the effects of food stress on Pgi genotype effects are largely unstudied.2.We compared Pgi allozyme genotype effects on life history between northern and southern populations of the damselfly Ischnura elegans in a common garden experiment where we manipulated food stress.3.Pgi genotypes differed in larval development time and body mass, but neither in larval growth rates nor in adult life span.4.The effect of the Pgi genotype on larval development time differed between latitudes, suggesting interactions with the latitude‐specific genetic background and/or maternal effects. Pgi genotype effects on both development time and body mass were dependent on food stress and indicated a trade‐off between both fitness‐related traits associated with the Pgi gene.5.The newly identified interaction between the Pgi genotype and latitude, the poorly studied Pgi genotype‐by‐food stress interactions and the observed life‐history trade‐offs associated with the Pgi genotypes can all potentially contribute to maintaining genetic variation at the Pgi locus and to latitudinal patterns in life history. Both types of interactions may also explain the poorly understood differences in the Pgi genotype effects on life history among studies of the same species.

Reasons for Help-Seeking and Associated Fears in Subjects with Substance Dependence

Background:Patients seek treatment for substance use disorders because of certain reasons that they consider significant and important, but on the other hand, they do have various fears or apprehensions about the treatment, which act as barriers for treatment-seeking. In this study, we aim to assess their reasons for seeking treatment, the associated fears about treatment, their social support and locus of control, and also to find the relationship among these variables.Materials and Methods:One hundred subjects attending the Drug Deaddiction and Treatment Center, Postgraduate Institute of Medical Education and Research (PGIMER) were prospectively recruited, with purposive sampling from 15 June to 14 July, 2011. The sociodemographic and clinical variables were ascertained through a semi-structured performa. The PGI Locus of Control Scale, Social Support Scale, and Reasons of Help-seeking and Fear Questionnaire were applied.Results:The common reasons for seeking treatment were — having become a habitual user, taking substance for a long time, and a need to take it every day. The common fears about treatment were the fear of disappointing others, loss of secrecy of substance use, and being considered a failure in life. The locus of control was primarily internal. Certain reasons like taking substance for a long time, feeling ill, and feeling sad were associated with a lower social support. Social support was not associated with the locus of control. The most affected areas of impairment were finance and health.Conclusions:Certain reasons and fears regarding treatment are more common than others. It is important to look into reasons and fears that are related to better treatment outcomes.

Genetic structure and bottleneck studies at the malate dehydrogenase and phosphoglucoisomerase (Glucose-6-phosphate isomerase) gene loci of neem (Azadirachta indica)

Genetic structure of the neem at the malate dehydrogenase and phosphoglucoisomerase (glucose-6-phosphate isomerase) gene loci wasstudied in a total of 192 seedlings raised from seeds collected from eleven maternal plants. Both loci were polymorphic and the mean number of alleles per locus was 5.05 + 0.54. Mean observed was 0.902 + 1.4. Levene’s and Nei’s expected heterozygosities were 0.804 + 0.02 and 0.801 + 0.02, respectively. Wright’s fixation index Fis estimates were negative for all the six alleles for the Mdh locus while for the Pgi locus the estimate was positive for two of the alleles. Analysis of molecular variance (AMOVA) indicated that 17.8 per cent of the total genetic diversity resided among families. The results showed that there was low level of population structure in the neem sample studied at the Mdh and Pgi gene loci and that the 11 families approximate a single panmictic unit. A normal ‘L’ shaped distribution of mode-shift test and three heterozygote excess tests suggested that there was no recent bottleneck in the population of neem at the two enzyme gene loci.

Biosystematics of the aphid genus Cryptomyzus (Hornoptera, Aphididae): an electrophoretic analysis

The aphid genus Crypromyzus was studied using starch. el electrophoresis in order to establish differences between the various taxa and to estimate their paylogenetic relationships. A low degree of polymorphism and heterozyosity was observed. Taxa previously assumed to be homogeneous appeared to consist of different tost-secific forms. Polymorphism at the PGI locus was used to assess the degree of isolation. It was founf to range from complete separation to a reduction in gene flow. Three methods of estimating hylogenetic relationships were employed: the UPGMA clustering method using Nei's genetic distance; the Rogers distance together with the distance Wagner method and the independent allele model of Mickevich and Mitter (1981) combined with the Wagner parsimony method. The results of all three methods agree that several of the taxa are closely related but assign different lower branching points to the phylogenetic tree. The independent allele model is discussed in more detail because it is not often applied.

Variabilidade genética em algumas criações comerciais brasileiras de escargots (Helix aspersa, Müller, 1774)

Descreveram-se os marcadores isoenzimáticos e estimou-se a variabilidade genética de 20 subpopulações brasileiras de escargots (Helix aspersa). O estudo dos oito locos foi feito por eletroforese em gel de amido, em amostras com 30 indivíduos cada, obtidas em criatórios dos estados de Santa Catarina, São Paulo e Rio de Janeiro (uma, duas e 17 amostras, respectivamente). Observou-se polimorfismo nos locos das enzimas LAP, 6-PGD, PEP 2, PEP 1 e MDH, com três alelos nos três primeiros locos e dois nos demais. Os locos da ME, da SOD e da PGI apresentaram-se monomórficos. As freqüências gênicas de sete amostras ajustaram-se ao modelo de Hardy-Weinberg (P<0,05), e as de outras seis amostras ajustaram-se ao modelo de Wright (P<0,05), indicando que elas estão submetidas a diferentes regimes reprodutivos. Os desvios da panmixia para toda a população (F IT ) e dentro das subpopulações (F IS) não foram significativos (P³0,05). O desvio entre as subpopulações (F ST=0,0485) foi significativo (P<0,05) e apontou pequena diferenciação entre elas. As estimativas de diversidade total (Ht), entre subpopulações (Dst) e dentro das subpopulações (Hs), indicaram que a diversidade genética é reduzida e sua maior parte encontra-se dentro das subpopulações, sugerindo uma base genética estreita para essa população. As distâncias genéticas também foram pequenas, não permitindo a construção de um dendrograma.

Allozyme genotypes and tolerance to copper stress in Hediste diversicolor (Polychaeta: Nereididae)

This study analysed the occurrence of genotypic shifts in laboratory populations of Hediste diversicolor (Polychaeta: Nereididae) exposed to copper stress. Specimens of H. diversicolor were collected at three sites, up to 10 km apart, in the estuarine area of the Pialassa lagoons (North Adriatic Sea, Italy) and were used in acute toxicity tests. Specimens were assigned to copper exposure (0.34 mg/l Cu 2+) or control conditions. Each combination of Treatment and Site was replicated in two tanks containing 35 specimens of H. diversicolor. The genotypic structure of both dead and survived specimens was analysed by allozyme electrophoresis at six loci (ALD, FH, HBDH LDH, PGI, SDH). Under copper exposure, specimens with the genotypes ALD 100/100 and PGI 102/102 had significantly lower mortalities than other genotypes Results were consistent across the three sites, suggesting that, under laboratory conditions, effects of copper stress on H. diversicolor is related to individual genotypes at ALD and PGI loci.

Allozyme variation at a PGI locus in differently aged populations of Moehringia trinervia (Caryophyllaceae) in a successional area

We studied genetic effects of the colonisation process during primary succession by analysing allozyme variation at a PGI locus in differently aged populations of Moehringia trinervia, which is a selfing annual with low dispersal ability. The populations studied come from islands and shores created in the 1880s by a drop in the water table of a Swedish lake and from old parts of a large island and of the mainland. The population age is known from five vegetation analyses over a century. We have also analysed the genetic composition of M. trinervia derived from seeds in the soil. Mainland populations had a higher genetic diversity than island populations that were little differentiated and differed genetically from the mainland populations. There was no temporal trend in the distribution of genetic variation on the new islands. The presence of alleles in the extant populations was associated with the proportion of that allele in the seed bank, indicating a main recruitment from the seed bank and not by repeated immigrations. We suggest that some of the new islands were colonised by a few early founders from the mainland. Later colonisation has occurred between adjacent islands, which preserves the founder effect and could explain the uniform, low genetic variation in the island populations.

Genetic and ecological differentiation between the butterfly sisterspecies Colias alfacariensis and Colias hyale

Clear habitat separation between the sister species Colias alfacariensis and C. hyale is shown when occurring sympatrically. Colias hyale is found more often in moist cultivated pastures while Colias alfacariensis is more abundant in dry uncultivated habitat. Out of a total of 16 loci, no diagnostic loci were found between C. alfacariensis and C. hyale, and both species shared most major polymorphisms. Exceptions were the marked differences in allele frequencies at the HK locus and only C. hyale, but not C. alfacariensis was further invariable at the GOT2 locus, which is usually highly polymorphic in the Pieridae. Colias hyale has a significantly lower level of heterozygosity than its sister species C. alfacariensis. In Colias alfacariensis heterozygosity is highest in the Alps and lowest in the low-lying region of Northern France, Both species show high levels of gene flow over a large geographic area. Within C. alfacariensis, but not in C. hyale, the FST value of the PGI locus is significantly different from zero effectively separating the species into populations with high levels of the ’ b’ allele to the west and North, and low levels of the allele in the Alps and Italy. This could point to selection within the PGI locus in line with the well established pattern of selection at the PGI locus in other species of Colias. Glaciations have been an important force in shaping the evolutionary history of European biota, leading to extinction, but also allowing new species to evolve into the newly available land as the ice sheets retreated. The genetic and distributional pattern found between both Colias species suggests that habitat shifts and subsequent adaptation during glaciations could have played an important role in their speciation.

Interpopulation variation in blue mussels,Mytilus edulisL., over short distances

Abstract Allozyme variation was studied on samples of blue mussels from three locations in and around Bergen. After initial studies trying a variety of buffers and electrophoretic conditions, the enzymes PGM and PGI were chosen for measuring intra- and interpopulation variation. Samples were collected from three localities within a maximum distance of about 40 km. High interpopulation variation was observed for distribution of PGM and PGI genotypes and their controlling alleles. It is assumed that selection has differentiated the population at the PGM and PGI loci. There is a significant deviation from the Hardy-Weinberg equilibrium of the PGM * alleles, which may be explained by selection.

Differential siring success of Pgi genotypes in Clarkia Unguiculata (Onagraceae)

Competition among pollen grains for the fertilization of ovules can play an important role in determining the male and female reproductive success of flowering plants. To examine the influence of pollen-donor genotype on male reproductive success, hand-pollinations were conducted on Clarkia unguiculata and the siring success of pollen-donor plants was compared between donors homozygous for different allelomorphs of the allozyme PGI (phosphoglucoisomerase). Donors homozygous for the B allele sired more seeds than C-allele donors. Single-donor crosses indicated that C-donor-sired seeds are aborted more often than are B-donor-sired seeds, suggesting that the B-allele donor's advantage in mixed pollinations was a result of differential abortion. A negative relationship between pollen load and the siring success of B-allele donors implies that pollen from B-allele donors has reduced performance relative to C-allele donors when pollen loads are high. These data demonstrate consistent differences in siring success between individuals homozygous for different alleles at a single locus and suggest that variation at the Pgi locus may be maintained by a post-pollination trade-off.

The use of allozymes and shell morphology to distinguish among sympatric species of the rock oyster Saccostrea in Thailand

Three hundred and fifty-five Saccostrea oysters from 12 sites throughout Thailand were scored for allozyme variation at eight enzyme loci ( Aat-1, Ap, Est-2, Lap, Mdh-1, Mpi, Pgi and Pgm). Allelic variation within Lap, Pgi, Pgm and Mpi loci was concordant. Principle component analysis (PCA) of these four loci identified two principal components (PC1 and PC2) that resolved individuals into three discrete clusters corresponding to different species. Oysters were assigned to different species by diagnostic alleles at Lap, Mpi and Pgi loci, and correct identification confirmed by a comparison of observed genotype frequencies in putative single-species samples with those expected under Hardy–Weinberg equilibrium. We identified one of these species as Saccostrea commercialis, based on identical mobility's at all eight loci to a reference sample of that species from Australia. The other two species we identified as S. cucullata and S. manilai by comparison of relative allozyme mobility's and shell morphology traits with data published for these species. S. commercialis and S. manilai were found in sympatry in coastal and estuarine sites throughout the Gulf of Thailand. S. cucullata was restricted to offshore islets. Ten measurements were made on the shells of a subset of oysters from seven sites. Observations were also made of adductor scar colour and chomata spacing. Principal component analysis of shell morphometrics of ninety oysters identified by allozymes revealed three principal components that varied between species. These reflected variation in overall size, degree of “cupping” of left valve, and relative size of the umbo cavity. The most useful character for species identification was the size of the umbo cavity, which was large in S. cucullata and S. commercialis, but almost non-existent in S. manilai. Mean umbo depths were 1.49 cm for S. cucullata, 0.7 cm for S. commercialis and 0.42 cm for S. manilai. Colour of the adductor scar was also of taxonomic value, with 75% of S. cucullata having black scars, while scars were white or brown in the other two species.

A psychosocial study of 'self-immolation' in India.

The phenomenon of self-immolation was studied in 22 young people, mostly students, who had indulged in this act to protest against the decision of the Government of India to enlarge the scope of reservations in jobs and educational institutions. Within a short span of time of arriving at one of the two treatment centres after attempting self-immolation, the subjects were interviewed and assessed on a semi-structured interview schedule to elicit sociodemographic and attitudinal data. The subjects were also rated on the Brief Psychiatric Rating Scale, Pierce's Suicide Intent Scale, the Superego Paranoia Depression Scale, the Hostility and Direction of Hostility Questionnaire, the PGI Locus of Control Scale and the Alienation Scale. All subjects except one were free of manifest psychopathology. The group as a whole had a high score on Pierce's Suicide Intent Scale and displayed internal locus of control orientation. Most were ambitious, aggressive, hostile and felt alienated. The absence of manifest psychopathology sets this group apart from cases of deliberate self-harm arising in the context of psychiatric morbidity. Thwarted ambitions, a sense of alienation and intropunitive hostility can lead to protest which at times becomes altruistic and results in self-immolation.

DNA polymorphism at the Pgi locus of a wild yam, Dioscorea tokoro.

To study the origin and maintenance mechanisms of the PGI allozyme polymorphism of a wild plant, Dioscorea tokoro, DNA sequences of the entire coding region (1701 bp) and two intronic regions (total 2049 bp) of the Pgi gene as well as a part of the Adh gene (590 bp) were analyzed. Two replacement substitutions were revealed to be responsible for the differentiation of three allozymes alleles (Pgi-a, Pgi-b and Pgi-c) that occur in natural population in intermediate frequencies. Interspecific comparison of DNA sequences identified Pgi-b as the oldest allele, from which two other alleles were derived probably within the last 150,000 years. The level of DNA polymorphism at D. tokoro Pgi locus was low. No elevated level of DNA polymorphism was detected in the close vicinity of the two replacement sites differentiating the three allozymes. Departures from the neutral mutation hypothesis were detected by Fu and Li's and MK tests. The observed patterns of DNA polymorphism are explainable by both (1) the neutral mutation hypothesis with an assumption of small effective size of D. tokoro population, and (2) the positive selection hypothesis that the allele frequencies of Pgi-a and Pgi-c have increased in a short time by their selective advantages.

Biochemical‐genetic variation in a wild and a cultured population of the greenshell mussel,Perna canaliculus

Abstract A wild and a cultured greenshell mussel (Perna canaliculus) population were compared for biochemical genetic variation at seven polymorphic and four monomorphic allozyme loci. Significant heterozygote deficiencies were observed for all polymorphic loci (La—1, La—2, Lap, Lgg—1, Lgg— 2, Pgi, and Pgm) for both populations (except the Pgi locus of the wild mussel population). Genotypic disequilibrium was calculated for both populations: genotypic frequencies were significantly non‐random at three pairs of loci among the wild mussels, and significantly non‐random at three different pairs of loci among the cultured mussels. All six pairs of loci which exhibited significant genotypic disequilibrium involved amino‐peptidases, suggesting that these loci form a linkage group, and that neither the Pgi nor the Pgm loci are associated with this group. Exact tests for population differentiation based upon population‐specific allele distributions indicated that four of the polymorphic loci were significantly he...