The genetic balance between varying population size and selective neutrality

This note extends to an arbitrary offspring distribution the generalized model for random fluctuation of allele frequency, where population size is permitted to fluctuate randomly from generation to generation. Martingale methods analogous to those of Seneta (1974) and Heyde and Seneta (1975) are applied to discuss conditions for Pr(Y(1–Y)>0)>0, where Y is the (almost sure) limiting frequency of one allele. An overlapping generation study of the same phenomenon has recently been made by Heyde (1981).     

The distribution of transferrin and hemoglobin types in families of Suffolk and Targhee sheep1

Transferrin and hemoglobin types were determined for 2133 sheep (Suffolks, Targhees, and Suffolk × Targhee crossbreds) and gene frequencies were calculated. Analysis of ratios of hemoglobin types revealed a significant excess of lambs of hemoglobin B/B type in some matings. For transferrins, there was a deficiency of homozygotes for Tf^B in offspring of matings of Tf^B heterozygotes inter se.     

Transferrin: Evidence for two common subtypes of the TfC allele

Summary Evidence is presented for an extended polymorphism of human transferrin (Tf). Three common phenotypes were observed among Tf^C individuals after isoelectric focusing of sera on polyacrylamide gels. They are explained in terms of two subtypes of the Tf^c allele, tentatively designated Tf^C1 and Tf^C2. The distribution of the phenotypes Tf C1, C2-1, and C2 provides a good fit to the Hardy-Weinberg equation. In our population sample (n=942) the following frequencies were calculated: Tf^C1=0.8195, Tf^C2=0.1720, Tf^B2=0.0064, Tf^B1–2=0.0016, and Tf^D1=0.0005. Family studies (n=112) indicate an autosomal codominant way of inheritance. The observed subheterogeneity is detectable in purified transferrin after isofocusing and subsequent immunofixation. The subtypes are still present after treatment of sera with neuraminidase.     

Human transferrin (Tf) and group-specific component (Gc) subtypes in Tunisia

Summary Simultaneous subtyping of two genetic markers—group-specific component (Gc) and transferrin (Tf)—by electrofocusing enabled us to compute the following gene frequencies for the Tunisian population: Gc ^IS .0.525; Gc ^IF , 0.260; Gc ², 0.215; Tf ^CI , 0.770; Tf ^C2 , 0.215; Tf ^D1 , 0.015.The frequencies of Tf ^D , Tf ^C2 , and Gc ¹ are higher than those found in Caucasoid populations and can be explained by Negroid contribution. A selective advantage related to the metabolic role of this vitamin D-binding protein does not seem very likely for any particular Gc type or subtype. It is postulated that the differences in the frequencies of the Gc alleles might be related to selective advantage for genes belonging to other genetic systems originally closely linked to either Gc ¹ or to Gc ² alleles.This work was supported in part by the Faculté de Pharmacie et de Médecine Dentaire of Monastir and by a grant from the Ambassade de France in Tunisia     

mir-320b rs755613466 T>C and mir-27a rs780199251 G>A polymorphisms and the risk of IVF failure in Kurdish women

In vitro fertilization failure is not only the cause of despair among couples and individuals undergoing the treatment, it has also been contributing to the impediment of assistive reproductive technologies’ development. MicroRNAs (miRNAs) have been linked to significant events in the reproduction course. The identification of miRNA polymorphisms may provide a good lead for the potential of diagnosis and treatment of unidentified in vitro fertilization (IVF) failure causes. The aim of our study is to explore the association between miRNA polymorphisms (mir-320b T>C and mir-27a G?>A) and IVF failure. Our case–control study consisted of 200 Kurdish women in total, 100 with IVF failure and the other 100 control who have had at least two successful pregnancies and no history of pregnancy loss, we used tetra amplification refractory mutation system PCR to identify the polymorphisms within the groups. The TT genotype of mir-320b was found more frequently in IVF failure patients when compared to the healthy women (OR 8.07, CI 2.18–29.78, P?=?0.001) and T allele was more present in the case group (OR 1.83, CI 91.04–2.12, P?=?0.034), however mir-27a seemed to show no association with IVF failure in regards to genotype and allele frequencies. The difference in genotype and allele frequencies of mir-320b of the two groups may indicate that it has an effect on the target mRNAs and alter the implantation of embryo during IVF cycles.

     

Distribution of transferrin phenotypes in selected troops of Kenya baboons

The distribution of transferrin alleles in a group of common baboons, Papio cynocephalus of East Africa, was determined after starch gel electrophoresis of plasma and autoradiography of electrophoretograms. Three alleles, Tf^A, Tf^B, and Tf^C, were found, in agreement with results previously reported. The frequencies of these alleles are Tf^A = 0.276, Tf^B = 0.515, Tf^c = 0.209. The difference between the frequencies reported here and those reported by Buettner-Janusch (1963 Folia Primat., 1: 73–87) for the same species (Tf^A = 0.205, Tf^B = 0.332, Tf^c = 0.463) is significant. Transferrin of P. cynocephalus contains four residues of sialic acid per molecule of transferrin, as determined by electrophoresis and autoradiography of plasma treated with neuraminidase.     

Chronotype distribution in professional rugby players: Evidence for the environment hypothesis?

Individual sport athletes have been shown to comprise unusually high proportions of morning-types (MTs) coupled with a higher prevalence of the morningness-associated PERIOD3 variable number tandem repeat (VNTR) allele, PER3⁵. The degree to which type of sport selected is influenced by either chronotype or genotype, or the extent to which sporting environment contributes to chronotype is unclear. The aim of this study was to assess chronotype and PER3 VNTR polymorphism frequencies in team sport players and non-athletic controls. South African male Super Rugby players (RUG, n = 120) and a control population of males with habitually low levels of physical activity (defined as exercise no more than twice a week; CON, n = 117) took part in this study. Participants completed the Horne–Östberg morningness–eveningness questionnaire to determine chronotype and donated buccal cell or blood samples from which PER3 VNTR genotype was established. There were more MTs in the RUG (47%) than CON group (23%, p < 0.001), more evening-types in the CON group (18%) compared to the RUG group (3%, p < 0.001), but no differences in PER3 VNTR genotype (p = 0.619) or allele (p = 0.758) frequencies. In both groups, more people carried the PER3⁴ allele (RUG: 63%, CON: 62%). Chronotype was associated with genotype in the CON (p = 0.004) but not the RUG group (p = 0.895). Unlike the individual sport endurance athletes previously studied in whom the PER3⁵ allele predominated, the PER3 VNTR genotype distribution in these team sport players was similar to that of the general population. We hypothesise that the absence of any chronotype–genotype relationship in these rugby players is because their diurnal preference is shifted towards morningness through habitual athletic behaviour.     

Evolution of variance in offspring number: The effects of population size and migration

It was shown by Gillespie [1974. Am. Nat. 108, 145–151], that if two genotypes produce the same average number of offspring on but have a different variance associated within each generation, the genotype with a lower variance will have a higher effective fitness. Specifically, the effective fitness is {ei65-1}, where w is the mean fitness, {ei65-2} is the variance in offspring number, and N is the total population size. The model also predicts that if a strategy has a higher arithmetic mean fitness and a higher variance than the competitor, the outcome of selection will depend on the population size (with larger population sizes favoring the highvariance, high-mean genotype). This suggests that for metapopulation sizes favoring the high-variance, high-mean genotype). This suggests that for metapopulations with large numbers of (relatively) small demes, a strategy with lower variance and lower mean may be favored if the migration rate is low while higher migration rates (consistent with a larger effective population size) favor the opposite strategy. Individual-based simulation confirms that this is indeed the case for an island model of migration, though the effect of migration differs greatly depending on whether migration precedes or follows selection. It is noted in the appendix that while Gillespie [1974. Am. Nat. 108, 145–151] does seem to be heuristically accurate, it is not clear that the definition of effective fitness follows from his derivation.     

Pedigreed crosses to estimate recessive virulence allele frequencies in natural populations of gall midges

Monitoring changes in rare, recessive allele frequencies in natural populations can be accomplished using pedigreed individuals sampled from these populations. A pedigree keeps track of and limits the mating of sampled individuals, to preserve information about the genotype of the sampled individual in the phenotypes of its descendents. To estimate allele frequencies in a natural population using pedigreed crosses, four relations must be specified: (1) a method to determine whether the pedigreed line carries the desired allele; (2) a method to estimate the phenotypic frequency of the trait among the pedigreed lines and a credibility limit for the estimate; (3) the genetic relation between the phenotype frequency among the lines and the allele frequency in the natural population; and (4) a method to estimate the probability that the first method did not detect the trait, assuming that the allele was present in the sampled individual. Knowledge about the segregation patterns of the allele enables specification of (3) and (4). Bayesian statistics were used to estimate the phenotypic frequency of the trait among the pedigreed lines. The method determining whether the pedigreed line carries the desired allele will vary with the species and trait of concern. We focused on monitoring of vGm1, a recessive autosomal allele, and vGm2, a recessive sex‐linked allele, which provide virulence against certain rice resistance genes in rice gall midge, Orseolia oryzae (Wood‐Mason) (Diptera: Cecidomyiidae). We show how three pedigrees can be used to estimate these allele frequencies. An F₁ field screen challenges the F₁ offspring of sampled individuals on the rice differentials. A P₁ test‐cross mates the sampled individual with a homozygous lab colony for the allele of interest, and evaluates their offspring on the rice differentials. A conditional F₁ test‐cross takes the offspring from pedigrees that were negative in an F₁ field screen, and test‐crosses these offspring with the homozygous laboratory colony. We also indicate how to test for independent assortment when a double (or multiple) homozygote laboratory colony is used in a test‐cross, how to test for differences among samples, and how to pool data to produce a single estimate based on a larger number of pedigreed lines. These methods may encourage the development of a variety of pedigreed monitoring strategies that could improve and prolong the use of scarce plant resistance alleles in rice and other plants.     

Transferrin (Tf) subtyping on agarose: A new technique for isoelectric focusing

Summary Isoelectric focusing (IEF) of the serum protein transferrin (Tf) on polyacrylamide gels has been found to be a useful tool in population genetics and forensic medicine. Three autosomal codominant alleles can be subtyped from the Tf ^C allele, Tf ^C1, Tf^C2, and Tf ^C3. In this report the authors describe the use of agarose as an alternative technique for Tf subtyping. The method is faster, easier to perform and eliminates the use of toxic chemicals used with polyacrylamide gels. Results of subtyping for the three alleles Tf ^C1, Tf^C2, and Tf ^C3 are described for a population of U.S. whites (n=392) and U.S. blacks (n=194).     

Chemical aids to drying seeds of beans (Phaseolus vulgaris) before harvest

The effects on seed moisture content of seven different chemical formulations applied to bean (Phaseolus vulgaris) crops in two successive years were observed. Those containing bipyridyl herbicides caused the biggest effects. In 1974, diquat (0–59 kg a.i. ha^-1), applied to a French bean crop cv. Processor 26 days before harvest, decreased seed moisture content by 98 mg g^_1 dry weight below a control value of 438 mg g^_1. In 1975, diquat applied at the same rate to a navy bean crop cv. Seafarer 16 days before harvest, decreased seed moisture content by 123 mg g^_1 below a control value of 364 mg g^_1. Diquat applied at a lower rate (0–3 kg a.i. ha^-J) caused a decrease of 79 mg g^_1 and paraquat decreased seed moisture by 147 mg g^_1. In both years smaller effects were observed for dimexan (15 kg a.i. ha^-1) which decreased seed moisture content by 32 mg g^-1 in 1974 and 72 mg g^_1 in 1975 and for ethephon (1-0 kg a.i. ha^-1) which caused decreases of 78 mg g^_1 in 1974 and 31 mg g^_1 in 1975. In 1975, metham-sodium (70 kg a.i. ha^-1) a soil sterilant, proved almost as effective as the bipyridyls, decreasing moisture content by 105 mg g^_1. Trimming the roots mechanically reduced seed moisture by 67 mg g^_1. Other chemical treatments, tried in 1975 only, were less effective and decreased seed moisture content by 31–60 mg g^_1. These were Wiltz-65 (pentanoic and hexanoic acids, 14-6 kg a.i. ha^-1), N252 (dihydro-dimethyl-dithiin tetroxide, 0–56 kg a.i. ha^-1) and an application of diquat (0–3 kg a.i. ha^-1) to plants treated 10 days before with ethephon (1-0 kg a.i. ha^-1)- In addition to the effects on seed moisture content, all treatments decreased seed yield. The largest decreases were caused by diquat and were attributable mainly to effects on mean seed weight. The paper concludes with an economic analysis which shows that at present prices chemical drying of beans in the field is not worthwhile because the yield loss nullifies any savings in drying costs.     

Assessment of the FAM174A 11G allele as a risk allele for equine metabolic syndrome

An 11G nucleotide repeat in the 3′ UTR of FAM174A was recently postulated as a risk allele with a dominant mode of inheritance for equine metabolic syndrome (EMS) and laminitis status in Arabian horses. The objective of this project was to evaluate this hypothesis in a large and diverse across-breed population. A total of 301 ponies, 292 Morgans, 64 Arabians, 49 Tennessee Walking Horses and 59 Quarter Horses were genotyped for six observed G repeat alleles in the FAM174A 3′ UTR. Phenotype data included laminitis status, baseline insulin, glucose, non-esterified fatty acids, triglycerides, adiponectin, leptin, ACTH, insulin and glucose post oral sugar test, and two proxies for insulin resistance. The 11G allele frequencies were 18.8, 6.9, 1.8, 0.2 and 0.0% in the Arabians, Tennessee Walkers, ponies, Morgans and Quarter Horses respectively. Association analyses between FAM174A genotype and EMS phenotypes, and between allele count and EMS phenotypes, identified no statistically significant associations. When a dominant effect for the 11G allele was evaluated, a statistically significant association with adiponectin levels was identified in the ponies, and pairwise comparisons revealed that the estimated marginal means were higher in ponies with the 11G allele vs. alternative alleles (i.e. the allele had a protective effect). In conclusion, our data do not support the FAM174A 11G allele as a risk allele for EMS in our studied breeds.     

Allozyme variation among natural populations of Holopedium gibberum (Crustacea; Cladocera)

• 1 Holopedium gibberum, from twenty lakes in Rhode Island and Maine, were examined for allozyme variation at five loci to determine the pattern and degree of generic variation among sites and the genetic structure within individual lakes.
• 2 There were significant differences in allele frequencies among sites. Most populations were fixed for a particular allele at each locus. Only five lakes had polymorphic populations.
• 3 Polymorphic populations showed significant deviation from expected Hardy-Weinberg genotype frequencies. In each case, there was an excess of homozygotes.
• 4 Two lakes were examined for intra-lake allele frequency differences. In one lake there were no differences. The other lake exhibited significant allele frequency differences between stations at the north and south ends of the lake.
• 5 Populations were examined for the frequency distribution of composite genotypes over three loci. Most populations were dominated by one or two genotypes.
• 6 The results suggest sporadic sexual recruitment and a high degree of genetic isolation among these populations of H. gibberum. In these respects they resemble the permanent pond populations of Daphnia magna examined by Hebert (1974a).

     

Endothelial Nitric Oxide Synthase Gene Minisatellite Polymorphism in Populations of the Volga–Ural Region and Analysis of Its Association with Myocardial Infarction and Essential Hypertension

The 27-bp tandem repeat polymorphism in intron 4 of the endothelial nitric oxide synthase gene (eNOS) in populations of the Volga–Ural region was studied by means of polymerase chain reaction. In Russians and Tatars, the possible association of this polymorphism with coronary heart disease complicated by either myocardial infarction or by essential hypertension was examined. Russians with essential hypertension associated with hypertrophy of the left ventricle displayed a statistically significant increase of the eNOS4A/Bgenotype and theAallele frequencies along with the decrease of the frequencies of the eNOS4B/Bgenotype and the Ballele. In Tatars survived from myocardial infarction and with the risk of cardiovascular diseases (smoking or burdened heredity), a statistically significant increase of the frequencies of the eNOS4A/Bgenotype and the Aallele was observed. Thus, in Russians the eNOS4A/Bgenotype was associated with the development of essential hypertension, while in Tatars it was associated with the risk of myocardial infarction.     

Association of leptin and leptin receptor gene polymorphisms with systemic lupus erythematosus in a Chinese population

To explore the association of LEP and leptin receptor (LEPR) gene single‐nucleotide polymorphisms (SNPs) with susceptibility to systemic lupus erythematosus (SLE) in a Chinese population. Four LEP SNPs (rs11761556, rs12706832, rs2071045 and rs2167270) and nine LEPR SNPs (rs10749754, rs1137100, rs1137101, rs13306519, rs8179183, rs1805096, rs3790434, rs3806318 and rs7518632) were genotyped in a cohort of 633 patients with SLE and 559 healthy controls. Genotyping of SNPs was performed with improved multiple ligase detection reaction (iMLDR). No significant differences were detected for the distribution of allele and genotype frequencies of all 13 SNPs between patients with SLE and controls. The genotype effects of recessive, dominant and additive models were also analysed, but no significant evidence for association was detected. However, further analysis in patients with SLE showed that the TT genotype and T allele frequencies of the LEP rs2071045 polymorphism were nominally significantly higher in patients with pericarditis (P = 0.012, P = 0.011, respectively). In LEPR, the GA/AA genotype and A allele frequencies of the rs1137100 polymorphism were both nominally associated with photosensitivity in patients with SLE (P = 0.043, P = 0.018, respectively). Moreover, the genotype and allele distribution of rs3806318 were also nominally associated with photosensitivity in patients with SLE (P = 0.013, P = 0.008, respectively). No significant differences in serum leptin levels were observed in patients with SLE with different genotypes. In summary, LEP and LEPR SNPs are not associated with genetic susceptibility to SLE, but may contribute to some specific clinical phenotype of this disease; further studies are necessary to elucidate the exact role of LEP and LEPR genes in the pathogenesis of SLE.     

Studies from the “UWL Helgoland” on the macrobenthic fauna of rocks and boulders in Lübeck Bay (western Baltic Sea)

During a fortnight's saturation mission with the Underwater Laboratory (UWL) Helgoland in May and June 1975, samples of the macrobenthic fauna of rocks and boulders at 15 m depth in the Lübeck Bay were collected from the same area as in October 1974, using a diver-operated suction sampler. Salinity varied from 11.1 to 15.0 S and water temperature from 7.5° C to 11.5° C. Visibility was usually about 3 to 4 m. On average, 10.449 individuals/m² were recorded in 1975 compared to 30.474 individuals/m² in 1974. Two species, the ascidianDendrodoa grossularia and the polychaetePolydora ciliata account for 90.8% of the total number of individuals sampled. Five species (Dendrodoa grossularia, Nereimyra punctata, Neoamphitrite figulus, Asterias rubens, Facelina drummondi) were significantly less abundant than in 1974, while two species and one group of species (Anaitides maculata, Corophium bonelli, Nemertini indet.) were more abundant in 1975. As in 1974, the angle of inclination of the substrate showed no relationship with species composition. In 1974, four motile benthic invertebrates,Nereimyra punctata, Idothea baltica, Diastylis rathkei, andFacelina drummondi were observed swarming. In 1975, onlyI. baltica was observed swarming and the individuals seemed to be less active than in 1974, perhaps related to the lower water temperatures recorded in May and June 1975 compared to those in October 1974.     

Study of the Association between Constitutional Exogenous Obesity and Polymorphism of the Apolipoprotein B Gene

An attempt was made to associate the insertion–deletion (Ins/Del) polymorphism of the apolipoprotein B gene (apoB) with obesity and to identify alleles and genotypes predisposing to this disorder. The apoB Ins/Del allele frequencies observed in the Russian population were similar to those in West European populations and significantly differed from frequencies reported for Asian populations. Patients with obesity did not differ from healthy individuals in allele and genotype frequencies regardless of whether total or sex-stratified samples were compared. Estimation of relative risk for individuals with genotype Ins/Ins did not reveal a significant association between obesity and this genotype. Thus, constitutional exogenous obesity did not prove to be associated with the Ins/Del polymorphism of theapoB gene in the Russian population.     

ABSENCE OF POLLEN DISCOUNTING IN A GENOTYPE OF IPOMOEA PURPUREA EXHIBITING INCREASED SELFING

Throughout southeastern North America, the annual morning glory Ipomoea purpurea exhibits a polymorphism at a locus that influences the intensity of floral pigmentation. Previous studies have shown that when rare, the homozygous white genotype has a greater selfing rate than the homozygous dark genotype. In the absence of pollen discounting (a reduction in transmission of pollen to other plants by genotypes that exhibit increased selfing) and inbreeding depression, this increased selfing rate should favor the white allele. Experiments reported here confirm that the white genotype has elevated selfing rates when rare but indicate pollen discounting is not associated with elevated selfing. Rather, white genotypes contribute more pollen to the outcross pollen pool. The disparity between genotypes in both selfing rates and success at pollen contribution to other plants disappears at intermediate to high frequencies of the white allele. Pollinator movements are consistent with the pattern of selfing. These results suggest that elevated selfing and enhanced success at pollen donation contribute to maintenance of the white allele in natural populations of morning glories.     

tetra: an improved program for population genetic analysis of allotetraploid microsatellite data

Population genetic analysis of allotetraploid microsatellite data has lagged far behind that of diploid data, largely because of an inability to determine allele copy number for partial heterozygotes. tetrasat developed by Markwith et al. (2006) uses an iterative substitution process to account for all probable combinations of allele copy numbers in populations with partial heterozygote samples. However, tetrasat cannot deal with microsatellite data containing more than 15 partial heterozygotes, because of an exponential increase in genotype combinations. tetra can handle the microsatellite data containing infinite partial heterozygotes. In the program tetra, the frequencies of alleles are measured as the probability with which the known alleles occur in unknown allele locations. The Hardy–Weinberg expected heterozygosity and Nei's coefficient of gene differentiation are calculated based on allele frequencies. The mean and standard error of expected heterozygosity are estimated through bootstrap method.     

Distribution and abundance of adult Opomyza florum (Diptera: Opomyzidae) in cereal crops and grassland

From 1971 to 1979 counts were made of the numbers of Opomyza florum adults found in vacuum net samples taken from cereal and grass fields on a 62-km² study area in West Sussex. In 2 years, 1974 and 1975, counts were made of the numbers of adults found in similar samples taken from hedgerow grasses. In all years, numbers of adults were highest in winter wheat crops; relatively few were found in other autumn- or spring-sown cereals or in grass fields. Mean numbers (/m²) in winter wheat in June varied from 33.0 in 1974 to only 0.9 in 1977. In most years, the first adults were found in June in winter wheat; numbers reached a peak in July and then declined rapidly. More adults were usually found in winter wheat crops that followed winter wheat in the rotation than in those following grass. Adults were also more abundant in June in winter wheat crops sown relatively early than in those sown late. The current tendencies towards earlier drilling of winter wheat and to the growth of successive wheat crops could increase the pest status of O. florum.