Browsing by Subject "polymorphism"

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  • Peris Tamayo, Ana-Maria; Devineau, Olivier; Praebel, Kim; Kahilainen, Kimmo K.; ostbye, Kjartan (2020)
    Adaptive radiation is the diversification of species to different ecological niches and has repeatedly occurred in different salmonid fish of postglacial lakes. In Lake Tinnsjoen, one of the largest and deepest lakes in Norway, the salmonid fish, Arctic charr (Salvelinus alpinus(L.)), has likely radiated within 9,700 years after deglaciation into ecologically and genetically segregated Piscivore, Planktivore, Dwarf, and Abyssal morphs in the pelagial, littoral, shallow-moderate profundal, and deep-profundal habitats. We compared trait variation in the size of the head, the eye and olfactory organs, as well as the volumes of five brain regions of these four Arctic charr morphs. We hypothesised that specific habitat characteristics have promoted divergent body, head, and brain sizes related to utilized depth differing in environmental constraints (e.g., light, oxygen, pressure, temperature, and food quality). The most important ecomorphological variables differentiating morphs were eye area, habitat, and number of lamellae. The Abyssal morph living in the deepest areas of the lake had the smallest brain region volumes, head, and eye size. Comparing the olfactory bulb with the optic tectum in size, it was larger in the Abyssal morph than in the Piscivore morph. The Piscivore and Planktivore morphs that use more illuminated habitats have the largest optic tectum volume, followed by the Dwarf. The observed differences in body size and sensory capacities in terms of vision and olfaction in shallow and deepwater morphs likely relates to foraging and mating habitats in Lake Tinnsjoen. Further seasonal and experimental studies of brain volume in polymorphic species are needed to test the role of plasticity and adaptive evolution behind the observed differences.
  • Sharma, Himanshu; Hyvönen, Jaakko; Poczai, Péter (2020)
    Premise Plant invasions are increasing globally, and extensive study of the genetic background of the source and invading populations is needed to understand such biological processes. For this reason, chloroplast microsatellite markers were identified to explore the genetic diversity of the noxious weed Ambrosia trifida (Asteraceae). Methods and Results The complete chloroplast genome of A. trifida was mined for microsatellite loci, and 15 novel chloroplast primers were identified to assess the genetic diversity of 49 Ambrosia samples. The number of alleles amplified ranged from two to six, with an average of 3.2 alleles per locus. Shannon's information index varied from 0.305 and 1.467, expected heterozygosity ranged from 0.178 to 0.645, and the polymorphism information content value ranged from 0.211 to 0.675 (average 0.428). The cross-species transferability of the 15 microsatellite loci was also evaluated in four related Ambrosia species (A. artemisiifolia, A. maritima, A. psilostachya, and A. tenuifolia). Conclusions The novel chloroplast microsatellite markers developed in the current study demonstrate substantial cross-species transferability and will be helpful in future genetic diversity studies of A. trifida and related species.
  • Briolat, Emmanuelle S; Burdfield-Steel, Emily R; Paul, Sarah C; Rönkä, Katja Helena; Seymore, Brett M; Stankowich, Theodore; Stuckert, Adam M M (2019)
    Aposematic theory has historically predicted that predators should select for warning signals to converge on a single form, as a result of frequency-dependent learning. However, widespread variation in warning signals is observed across closely related species, populations and, most problematically for evolutionary biologists, among individuals in the same population. Recent research has yielded an increased awareness of this diversity, challenging the paradigm of signal monomorphy in aposematic animals. Here we provide a comprehensive synthesis of these disparate lines of investigation, identifying within them three broad classes of explanation for variation in aposematic warning signals: genetic mechanisms, differences among predators and predator behaviour, and alternative selection pressures upon the signal. The mechanisms producing warning coloration are also important. Detailed studies of the genetic basis of warning signals in some species, most notably Heliconius butterflies, are beginning to shed light on the genetic architecture facilitating or limiting key processes such as the evolution and maintenance of polymorphisms, hybridisation, and speciation. Work on predator behaviour is changing our perception of the predator community as a single homogenous selective agent, emphasising the dynamic nature of predator-prey interactions. Predator variability in a range of factors (e.g. perceptual abilities, tolerance to chemical defences, and individual motivation), suggests that the role of predators is more complicated than previously appreciated. With complex selection regimes at work, polytypisms and polymorphisms may even occur in Mullerian mimicry systems. Meanwhile, phenotypes are often multifunctional, and thus subject to additional biotic and abiotic selection pressures. Some of these selective pressures, primarily sexual selection and thermoregulation, have received considerable attention, while others, such as disease risk and parental effects, offer promising avenues to explore. As well as reviewing the existing evidence from both empirical studies and theoretical modelling, we highlight hypotheses that could benefit from further investigation in aposematic species. Finally by collating known instances of variation in warning signals, we provide a valuable resource for understanding the taxonomic spread of diversity in aposematic signalling and with which to direct future research. A greater appreciation of the extent of variation in aposematic species, and of the selective pressures and constraints which contribute to this once-paradoxical phenomenon, yields a new perspective for the field of aposematic signalling.
  • Kokko, Hanna; Jennions, Michael D; Houde, Anne (2007)
    The diversity of sexual traits favoured by females is enormous and, curiously, includes preferences for males with rare or novel phenotypes. We modelled the evolution of a preference for rarity that yielded two surprising results. First, a Fisherian 'sexy son' effect can boost female preferences to a frequency well above that predicted by mutation-selection balance, even if there are significant mortality costs for females. Preferences do not reach fixation, however, as they are subject to frequency-dependent selection: if choosy females are too common, then rare genotypes in one generation become common, and thus unattractive, in the offspring generation. Nevertheless, even at relatively low frequency, preferences maintain polymorphism in male traits. The second unexpected result is that the preferences can evolve to much higher frequencies if choice is hindered, such that females cannot always express their preferences. Our results emphasize the need to consider feedback where preferences determine the dynamics of male genotypes and vice versa. They also highlight the similarity between the arbitrariness of behavioural norms in models of social evolution with punishment (the so-called 'folk theorem') and the diversity of sexual traits that can be preferred simply because deviating from the norm produces unattractive offspring and is, in this sense, 'punished'.
  • Said, M. Abdullah; Yeung, Ming Wai; van de Vegte, Yordi J.; Benjamins, Jan Walter; Dullaart, Robin P. F.; Ruotsalainen, Sanni; Ripatti, Samuli; Natarajan, Pradeep; Juarez-Orozco, Luis Eduardo; Verweij, Niek; van der Harst, P. (2021)
    Objective: Lipoprotein(a) (Lp[a]) is associated with coronary artery disease (CAD) but also to LDL (low-density lipoprotein) cholesterol. The genetic architecture of Lp(a) remains incompletely understood, as well as its independence of LDL cholesterol in its association to CAD. We investigated the genetic determinants of Lp(a) concentrations in a large prospective multiethnic cohort. We tested the association for potential causality between genetically determined higher Lp(a) concentrations and CAD using a multivariable Mendelian randomization strategy. Approach and Results: We studied 371 212 participants of the UK Biobank with available Lp(a) and genome-wide genetic data. Genome-wide association analyses confirmed 2 known and identified 37 novel loci (P Conclusions: This study supports an LDL cholesterol-independent causal link between Lp(a) and CAD. A rare missense variant in the LPA gene locus appears to be protective in people with the Lp(a) increasing variant of rs10455872. In the search for therapeutic targets of Lp(a), future work should focus on understanding the functional consequences of this missense variant.
  • Amiryousefi, Ali; Hyvönen, Jaakko; Poczai, Péter (2018)
    PREMISE OF THE STUDY: To accurately design plant genetic studies, the information content of utilized markers and primers must be calculated. Plant genotyping studies should take into account the efficiency of each marker system by calculating different parameters to find the optimal combination of primers. This can be problematic because there are currently no easily accessible applications that can be used to calculate multiple indices together. METHODS AND RESULTS: The program Online Marker Efficiency Calculator (iMEC) was developed using R for the simple computation of seven polymorphism indices (heterozygosity index, polymorphism information content, discriminating power, effective multiplex ratio, marker index, arithmetic mean heterozygosity, and resolving power). These indices are based on dominant and codominant DNA fingerprinting markers, thus allowing comparison and selection of optimal genetic markers for a given data set. CONCLUSIONS: iMEC simplifies the calculation of diverse indices for the marker of choice to better enable researchers to measure polymorphism information for individual markers.
  • FinnGen Rheumatology Clinical Expe; Palomaki, Antti; Palotie, Aarno; Koskela, Jukka; Eklund, Kari K.; Pirinen, Matti; Ripatti, Samuli; Laitinen, Tarja; Mars, Nina (2021)
    Objectives To estimate lifetime risk of developing rheumatoid arthritis-associated interstitial lung disease (RA-ILD) with respect to the strongest known risk factor for pulmonary fibrosis, a MUC5B promoter variant. Methods FinnGen is a collection of epidemiological cohorts and hospital biobank samples, integrating genetic data with up to 50 years of follow-up within nationwide registries in Finland. Patients with RA and ILD were identified from the Finnish national hospital discharge, medication reimbursement and cause-of-death registries. We estimated lifetime risks of ILD by age 80 with respect to the common variant rs35705950, a MUC5B promoter variant. Results Out of 293 972 individuals, 1965 (0.7%) developed ILD by age 80. Among all individuals in the dataset, MUC5B increased the risk of ILD with a HR of 2.44 (95% CI: 2.22 to 2.68). Out of 6869 patients diagnosed with RA, 247 (3.6%) developed ILD. In patients with RA, MUC5B was a strong risk factor of ILD with a HR similar to the full dataset (HR: 2.27, 95% CI: 1.75 to 2.95). In patients with RA, lifetime risks of ILD were 16.8% (95% CI: 13.1% to 20.2%) for MUC5B carriers and 6.1% (95% CI: 5.0% to 7.2%) for MUC5B non-carriers. The difference between risks started to emerge at age 65, with a higher risk among men. Conclusion Our findings provide estimates of lifetime risk of RA-ILD based on MUC5B mutation carrier status, demonstrating the potential of genomics for risk stratification of RA-ILD.
  • Jokela, M.; Vartio, A.; Paulin, L.; Fyhrquist-Vanni, N.; Donner, K. (Company of Biologists, 2003)
    Absorbance spectra were measured by microspectrophotometry in retinal rods of sand gobies (Pomatoschistus minutus) from four allopatric populations (Baltic Sea, Swedish west coast, English Channel and Adriatic Sea). Mean (± S.E.M.) wavelengths of maximum absorbance (max) were 508.3±0.5 nm, 505.4±0.2 nm, 506.2±0.3 nm and 503.0±0.3 nm, respectively. Pairwise comparison between the populations (post-ANOVA Scheffe's test) shows that each of the max differences, except that between the Swedish west coast and the English Channel, is statistically significant (P<0.05). The shapes of the absorbance spectra indicated that the pigments were A1 rhodopsins with no measurable admixture of the A2 chromophore. Thus, the differences indicate polymorphism in the protein part (opsin) of the pigment. Convolution of A1 templates for max values 508.3 nm and 503.0 nm with quantum spectra of the downwelling light at two locations at the south-west coast of Finland indicated that a 13-19% improvement in quantum catch would accrue in the Baltic environment from the 5.3 nm red-shift of the rod pigment of Baltic compared with Adriatic sand gobies.
  • Chen, Sam Li-Sheng; Fann, Jean Ching-Yuan; Sipeky, Csilla; Yang, Teng-Kai; Chiu, Sherry Yueh-Hsia; Yen, Amy Ming-Fang; Laitinen, Virpi; Tammela, Teuvo L. J.; Stenman, Ulf-Håkan; Auvinen, Anssi; Schleutker, Johanna; Chen, Hsiu-Hsi (2019)
    Purpose:Combined information on single nucleotide polymorphisms and prostate specific antigen offers opportunities to improve the performance of screening by risk stratification. We aimed to predict the risk of prostate cancer based on prostate specific antigen together with single nucleotide polymorphism information.Materials and Methods:We performed a prospective study of 20,575 men with prostate specific antigen testing and 4,967 with a polygenic risk score for prostate cancer based on 66 single nucleotide polymorphisms from the Finnish population based screening trial of prostate cancer and 5,269 samples of 7 single nucleotide polymorphisms from the Finnish prostate cancer DNA study. A Bayesian predictive model was built to estimate the risk of prostate cancer by sequentially combining genetic information with prostate specific antigen compared with prostate specific antigen alone in study subjects limited to those with prostate specific antigen 4 ng/ml or above.Results:The posterior odds of prostate cancer based on 7 single nucleotide polymorphisms together with the prostate specific antigen level ranged from 3.7 at 4 ng/ml, 14.2 at 6 and 40.7 at 8 to 98.2 at 10 ng/ml. The ROC AUC was elevated to 88.8% (95% CI 88.6-89.1) for prostate specific antigen combined with the risk score based on 7 single nucleotide polymorphisms compared with 70.1% (95% CI 69.6-70.7) for prostate specific antigen alone. It was further escalated to 96.7% (95% CI 96.5-96.9) when all prostate cancer susceptibility polygenes were combined.Conclusions:Expedient use of multiple genetic variants together with information on prostate specific antigen levels better predicts the risk of prostate cancer than prostate specific antigen alone and allows for higher prostate specific antigen cutoffs. Combined information also provides a basis for risk stratification which can be used to optimize the performance of prostate cancer screening.
  • Kauppi, P; Lindblad-Toh, K; Sevon, P; Toivonen, H T T; Rioux, J D; Villapakkam, A; Laitinen, L A; Hudson, T J; Kere, J; Laitinen, T (2001)
  • Du, Yajun (Helsingin yliopisto, 2018)
    Narcissus also called daffodil is a popular ornamental plant from Europe. It is known in Finnish gardens since 17th century, but there is no complete study on its genetic diversity. Over hundred years’ cultivation, it could happen the name of some accessions have been lost, localized or incorrectly assigned for a long time. In order to clarify the duplicates and support further genetic resource conservation, breeding program and other potential applications, the genetic diversity analysis of a set of N. poeticus and N. pseudonarcissus accessions was conducted by molecular markers. Genetic distance matrices between accessions were calculated by Dice dissimilarity coefficient and Gower’s dissimilarity coefficient, which was used to do cluster analysis and construct the dendrogram. Dendrograms of microsatellite data and ISSR data were draw by R program and based on unweighted pair group method with arithmetic averages (UPGMA) to visualize genetic distance between accessions. We investigated genetic polymorphism of 3 microsatellite loci and 6 inter-simple sequence repeat (ISSR) loci in 164 accessions of N. poeticus, N. pesudonarcissus, their hybrids and unknown species. Despite 3 microsatellite markers were not specifically developed from N. poeticus or N. pesudonarcissus, they were detected reasonable informativeness with average genetic diversity value (GD) of 0.22 and 36 polymorphic alleles were amplified in this study. As for 6 ISSR markers, we observed more informativeness with higher average GD of 0.3 and 224 polymorphic alleles. According to pairwise similarity of accessions and microsatellite dendrogram, we found 18 groups of samples might be duplicates, 14 pairs of samples might be siblings and 4 pairs of samples could belong to same family. From the analysis of ISSR dendrogram, 51 pairs of samples were considered with close genetic relationship, but only 6 pairs might be duplicates, 44 pairs could be siblings and 1 pair could belong to the same family. Two core collections constructed by CoreFinder software consist of 24 accessions and 18 accessions respectively regarding to microsatellite data and ISSR data.
  • Novakovic, Dunja; Isomäki, Antti; Pleunis, Bibi; Fraser-Miller, Sara J.; Peltonen, Leena Johanna; Laaksonen, Timo; Strachan, Clare Joanna (2018)
    The tendency for crystallization during storage and administration is the most considerable hurdle for poorly water-soluble drugs formulated in the amorphous form. There is a need to better detect often subtle and complex surface crystallization phenomena and understand their influence on the critical quality attribute of dissolution. In this study, the interplay between surface crystallization of the amorphous form during storage and dissolution testing, and its influence on dissolution behavior, is analyzed for the first time with multimodal nonlinear optical imaging (coherent anti-Stokes Raman scattering (CARS) and sum frequency generation (SFG)). Complementary analyses are provided with scanning electron microscopy, X-ray diffraction and infrared and Raman spectroscopies. Amorphous indomethacin tablets were prepared and subjected to two different storage conditions (30 °C/23% RH and 30 °C/75% RH) for various durations and then dissolution testing using a channel flow-through device. Trace levels of surface crystallinity previously imaged with nonlinear optics after 1 or 2 days of storage did not significantly decrease dissolution and supersaturation compared to the freshly prepared amorphous tablets while more extensive crystallization after longer storage times did. Multimodal nonlinear optical imaging of the tablet surfaces after 15 min of dissolution revealed complex crystallization behavior that was affected by both storage condition and time, with up to four crystalline polymorphs simultaneously observed. In addition to the well-known α- and γ-forms, the less reported metastable ε- and η-forms were also observed, with the ε-form being widely observed in samples that had retained significant surface amorphousness during storage. This form was also prepared in the pure form and further characterized. Overall, this study demonstrates the potential value of nonlinear optical imaging, together with more established solid-state analysis methods, to understand complex surface crystallization behavior and its influence on drug dissolution during the development of amorphous drugs and dosage forms.