Size Polymorphism Research Articles

Development of an affordable typing method for Meyerozyma guilliermondii using microsatellite markers

Despite previously published methods, there is still a lack of rapid and affordable methods for genotyping the Meyerozyma guilliermondii yeast species. The development of microsatellite markers is a useful genotyping method in several yeast species. Using the Tandem Repeat Finder Software, a total of 19 microsatellite motifs (di-, tri-, and tetra- repetition) were found in silico in seven of the nine scaffolds published so far. Primer pairs were designed for all of them, although only four were used in this work. All microsatellite amplifications showed size polymorphism, and the results were identical when repeated. The combination of three microsatellite markers (sc15F/R, sc32 F/R and sc72 F/R) produced a different pattern for each of the Type Culture Collection strains of M. guilliermondii used to optimize the method. The three primer pairs can be used in the same PCR reaction, which reduces costs, in tandem with the fluorescent labeling of only the forward primer in each primer pair. Microsatellite typing was applied on 40 more M. guilliermondii strains. The results showed that no pattern is repeated between the different environmental niches. Four M. guilliermondii strains were only amplified with primer pair sc32 F/R, and subsequently identified as Meyerozyma caribbica by Taq I-RFLP of the 5.8S ITS rDNA. Most out-group species gave negative results even for physiologically similarly species such as Debaryomyces hansenii. The microsatellite markers used in this work were stable over time, which enables their use as a traceability tool.

Lipoprotein(a) and apolipoprotein(a) in polycystic ovary syndrome.

Levels of lipoprotein(a), Lp(a), an independent risk factor for cardiovascular disease (CVD), are affected by sex hormones. Women with polycystic ovary syndrome (PCOS) have elevated androgen levels and are at increased CVD risk. We investigated the impact of PCOS-related hormonal imbalance on Lp(a) levels in relation to apo(a) gene size polymorphism, a major regulator of Lp(a) level. Cross-sectional. Forty-one Caucasian women with PCOS based on the NIH criteria. (1) Apo(a) gene size polymorphism measured as Kringle (K) 4 repeat number; (2) total plasma Lp(a) level; (3) allele-specific apo(a) level assessing the amount of Lp(a) carried by an individual apo(a) allele/isoform; and (4) sex hormone levels. The mean age was 32 ± 6 years, and the mean BMI was 35 ± 8 with 66% of women classified as obese (BMI >30 kg/m2 ). LDL cholesterol was borderline high (3·37 mmol/l), and HDL cholesterol was low (1·06 mmol/l). The distribution of Lp(a) level was skewed towards lower levels with a median level of 22·1 nmol/l (IQR: 6·2-66·5 nmol/l). Lp(a) levels were not correlated with age, body weight or BMI. The median allele-specific apo(a) level was 10·6 nmol/l (IQR: 3·1-31·2 nmol/l), and the median apo(a) size was 27 (IQR: 23-30) K4 repeats. Allele-specific apo(a) levels were significantly and inversely correlated with K4 repeats (r = -0·298, P = 0·007). Neither Lp(a) nor allele-specific apo(a) levels were significantly associated with testosterone or dehydroepiandrosterone sulphate levels. The apo(a) genetic variability remains the major regulator of plasma Lp(a) levels in women with PCOS.

No Response to Bidirectional Size-Based Selection in the Rotifer Brachionus rotundiformis

Although rotifers have been considered the best feeding option for several species of fishes in aquaculture, they are sometimes larger than appropriate for the early larval stage of some marine fishes. Thus, we aimed to determine whether size-based selection of the parents could affect the average body size of their progeny in two clonal populations of the rotifer Brachionus rotundiformis. From each of the clones, 20 individuals were bi-directionally selected toward both smaller and larger sizes and each individualbased selection was conducted for 10 consecutive generations. The results showed that although there were sometimes differences in mean body size between parents and their progeny, no directional trend was observed in all selected lines of both clones. We demonstrated that artificial selection in a rotifer stock cannot lead to an expected size range although they appear to exhibit a large degree of body size polymorphism.

Diversity, ecology, and evolution in Phycomyces

The fungal genus Phycomyces (Mucoromycotina, Mucorales) has been revised by examining 96 strains, received from established collections or newly isolated from different environments. Morphology, sexuality, DNA sequences, and population structure clearly identify the genus and set it apart from other Mucorales. The size of the spores, the sexual interactions, the sequences of genes sexM and sexP that determine sexual identity, and the DNA for ribosomal RNAs validate the species Phycomyces blakesleeanus and Phycomyces nitens and the family Phycomycetaceae. Isolates from the same sample of biomass often differ in spore size, sex, DNA sequences, and restriction-length polymorphisms. The widest diversity was found in similar environments in three of the Canary Islands, implying a failure to disperse rapidly over the sea. All strains have apparently functional sexM and sexP genes and all but some strains of P. nitens complete the sexual cycle in the laboratory. The genetic diversity of P. blakesleeanus strains provides evidence for geographical clustering. Various sequence comparisons, including the newly isolated genes sexM and sexP of P. nitens and Blakeslea trispora, clarify phylogenetic relationships in the Mucorales and recommend the sex genes for the study of speciation.

Molecular sex identification of red panda (Ailurus fulgens) suitable for noninvasive genetic studies

Molecular sexing of wild animals is feasible with differential amplification of X- and Y-homologous regions of various genes. We present a simple and robust technique for sex identification of red panda suitable for noninvasive studies based on sex-specific fragment size polymorphism in amelogenin (AMEL) gene. Sequence analysis of AMELX and AMELY revealed an 18-bp deletion in Y fragment which was used to differentially amplify 217 bp of X and 199 bp of Y fragments. The designed primer pair is very sensitive and exhibits polymerase chain reaction (PCR) success rates of 89 and 78 % at 0.1 and 0.01 ng template DNA concentrations, respectively. Further, we amplified poor quality faecal DNA with 94 % success rate and average dropout rate of 15.6 %. In silico analysis shows that these primers can also be used to identify sex of a sympatric species, giant panda.

Genetic population structure of the commercially most important demersal fish in the Southwest Atlantic: The whitemouth croaker (Micropogonias furnieri)

The whitemouth croaker (Micropogonias furnieri) is the main fish species of the demersal fisheries along the Atlantic coast of South America. There has been much debate regarding the number of stocks of this heavily exploited fish off the Brazilian coast between latitudes 23°S and 33°S. Analyses of morphometric and meristic data suggest that two stocks exist in that area, but this conclusion was not supported by genetic studies. Here, we used polymorphic nuclear loci (microsatellite and intron size polymorphisms) to compare samples of M. furnieri collected between Rio de Janeiro (23°02′S) and Chuí (33°41′S), as well as samples from much further north, along the coast of Bragança at Pará State (1°03′S). Our data demonstrate the existence of three distinct stocks of the species in Brazil: one in North Brazil (Bragança – Pará State), as previously suggested; and two previously not detected genetically: one between 23°S and 29°S; and another south of parallel 29°S. These findings indicate that the fisheries of the three areas should be managed as distinct stocks.

Sex identification in four leporid species (Lepus corsicanus, Lepus europaeus, Lepus timidus and Lepus capensis mediterraneus)

The sexes of mammals can be determined routinely by polymerase chain reaction (PCR) amplification of Y chromosome fragments or coamplification of homologous fragments from both sex chromosomes, which have distinct size polymorphism or Y-specific restriction sites. In juvenile leporid individual sex identification from morphological traits is not always reliable. Here we designed specific dye-labelled primers to amplify a SRY fragment together with a portion of the Transferrin gene. With a simple approach using double peaks in the electropherogram, upon direct sequencing of PCR products from males and females, we demonstrate the methodology’s utility by the application to different leporid species (Lepus corsicanus, Lepus europaeus, Lepus timidus and Lepus capensis mediterraneus).

Plasma lipoprotein(a) size polymorphism and function: apo(a) subunit size determines galectin-1 recognition and apoB subunit epitope masking

Polymorphism and pathological potential of human plasma lipoprotein(a) [Lp(a)] are determined solely by variation in size of its apo(a) subunit which is linked by a disulfide to an apoB subunit of invariant size. Affinity precipitation of Lp(a) from plasma employing the O-glycan-specific lectin jacalin before electrophoretic removal of adhering LDL was shown to be comprehensive without loss of lipoprotein structure. Isolation of even low abundance Lp(a) molecules by this protocol facilitated study of variations in subunit interactions as a function of Lp(a) size. Affinity of the autologous lectin galectin-1 toward Lp(a) isoforms increased with their size. Since apoB is not a ligand for galectin-1 result suggested apo(a) size as a modulator of Lp(a) adhesion in vivo to vascular cells and macrophages that express this lectin. Result may also explain the inverse relation of Lp(a) size to its rate of release from the galectin-1-rich intracellular compartments. N-Glycans and antigenic epitopes of apoB in Lp(a) were masked from recognition by the lectin concanavalin A and anti-apoB antibody respectively in proportion to the size of apo(a) . Recovery of apoB from masking upon removal of apo(a) alone from Lp(a) by dithiothreitol-mediated reduction was proportional to the size of the leaving apo(a). Since LDL receptors recognize lipoproteins through apoB epitopes results explain the reported lower binding of larger Lp(a) molecules to these receptors.

Disparate independent genetic events disrupt the secondary metabolism gene perA in certain symbiotic Epichloë species.

Peramine is an insect-feeding deterrent produced by Epichloë species in symbiotic association with C3 grasses. The perA gene responsible for peramine synthesis encodes a two-module nonribosomal peptide synthetase. Alleles of perA are found in most Epichloë species; however, peramine is not produced by many perA-containing Epichloë isolates. The genetic basis of these peramine-negative chemotypes is often unknown. Using PCR and DNA sequencing, we analyzed the perA genes from 72 Epichloë isolates and identified causative mutations of perA null alleles. We found nonfunctional perA-ΔR* alleles, which contain a transposon-associated deletion of the perA region encoding the C-terminal reductase domain, are widespread within the Epichloë genus and represent a prevalent mutation found in nonhybrid species. Disparate phylogenies of adjacent A2 and T2 domains indicated that the deletion of the reductase domain (R*) likely occurred once and early in the evolution of the genus, and subsequently there have been several recombinations between those domains. A number of novel point, deletion, and insertion mutations responsible for abolishing peramine production in full-length perA alleles were also identified. The regions encoding the first and second adenylation domains (A1 and A2, respectively) were common sites for such mutations. Using this information, a method was developed to predict peramine chemotypes by combining PCR product size polymorphism analysis with sequencing of the perA adenylation domains.

Lipoprotein(a): when to measure, how to treat?

Abstract: Lipoprotein(a) [Lp(a)] is one of the most atherogenic lipoproteins consisting of a core low-density lipoprotein particle and the specific glycoprotein apo(a). Apo(a) is homologous to plasminogen yet in contrast exhibits a specific size polymorphism. This polymorphism is due to the fact that the number of kringle-IV (K-IV) repeats ranges between two and approximately 50. Apo(a) is synthesized almost exclusively in the liver, and there is still some discussion regarding whether the assembly of Lp(a) occurs intracellularly or in the circulating blood. The plasma Lp(a) concentration is markedly skewed to the right and extends from <1 mg/dL to more than 200 mg/dL. Up to 90% of the variance of Lp(a) concentrations may be genetically determined and the Lp(a) concentration correlates inversely with the number of K-IV repeats. In the apo(a) promoter there are numerous response elements for transcription factors and nuclear receptors, whereby the HNF4α binding sequence is the most important one. Activation of FXR causes the dissociation of HNF4α from its response element and in turn a significant down regulation of apo(a) transcription. Recent large epidemiological studies document beyond any doubt that Lp(a) is an independent causal risk factor for coronary heart disease and myocardial infarction. Hence, novel approaches to correct elevated Lp(a) are under investigation. Among the established lipid-lowering drugs, only nicotinic acid lowers Lp(a) in a consistent and clinically relevant fashion, and we recently elucidated the molecular mechanism underlying this effect. Novel medicines in clinical trials include CETP inhibitors, PCSK9 antibodies, the MTP inhibitor lomitapide and antisense oligonucleotides. APO(a)Rx ®, an antisense oligonucleotide, which is specifically directed against the mRNA for apo(a), has the strongest effect on Lp(a). It offers the opportunity to examine the impact of selective Lp(a) lowering on clinical events. Lp(a) emerged as an important screening parameter to assess the risk for atherosclerosis. Its quantitation in the clinical laboratory had not been standardized for a long period of time. New commercial methods, in particular enzyme immunoassays with monoclonal antibodies that recognize single epitopes in apo(a), or nephelometric and turbidimetric assays hold the potential to warrant comparable results in different laboratories.

Characterization of 12 Novel Microsatellite Markers of Sogatella furcifera (Hemiptera: Delphacidae) Identified From Next-Generation Sequence Data.

The white-backed planthopper, Sogatella furcifera (Horváth) (Hemiptera: Delphacidae), is a major pest of rice and has long-range migratory behavior in Asia. Microsatellite markers (simple sequence repeats) have been widely used to determine the origins and genetic diversity of insect pests. We identified novel microsatellite loci for S. furcifera samples collected from Laos, Vietnam, and three localities in Bangladesh from next-generation Roche 454 pyrosequencing data. Size polymorphism at 12 microsatellite loci was verified for 40 adult individuals collected from Shinan, South Korea. The average number of alleles per locus was 7.92. The mean values of observed (Ho) and expected heterozygosities (HE) were 0.615 and 0.757, respectively. These new microsatellite markers will be a resource for future ecological genetic studies of S. furcifera samples across more broad geographic regions in Asia and may assist in estimations of genetic differentiation and gene flow among populations for implementation of more effective management strategies to control this serious rice pest.

English

Twenty-one accessions of African nutmeg ( Monodora myristica Gaertn. Dunal), an endangered spice plant, were collected from the South-East and South-South regions of Nigeria and analyzed for genetic diversity using random amplified polymorphic DNA (RAPD) markers. Twenty-one (21) decamer primers were tested out of which 10 that gave reproducible band patterns were selected for the study. A total of 77 bands were generated, ranging from 3 for OPB17 to 13 for OPT07, and were all polymorphic. The mean polymorphic information content ( PIC ) and genetic diversity ( H e ) were 0.673 and 0.697, respectively, indicating high genetic variation among the accessions. Cluster analysis delineated the accessions into four major groups. The maximum similarity index (0.88) based on Dice coefficient was recorded between AGL-01 and CRS-01 while the least (0.13) was between UGA-02 and EKW 01. The derived data was thus able to determine the extent of molecular variation underlying RAPD size polymorphism. Results obtained from this study proved that RAPD could be successfully used as a molecular tool for diversity study in M. myristica . The distributive pattern of genetic variation of M. myristica accessions provides important baseline data for conservation and improvement strategies for this species. Keywords: African nutmeg, random amplified polymorphic DNA (RAPD), genetic variation, polymorphic information content (PIC), similarity index, Monodora myristica African Journal of Biotechnology , Vol 13(42) 4105-4111

Bumblebee size polymorphism and worker response to queen pheromone.

Queen pheromones are chemical signals produced by reproductive individuals in social insect colonies. In many species they are key to the maintenance of reproductive division of labor, with workers beginning to reproduce individually once the queen pheromone disappears. Recently, a queen pheromone that negatively affects worker fecundity was discovered in the bumblebee Bombus terrestris, presenting an exciting opportunity for comparisons with analogous queen pheromones in independently-evolved eusocial lineages such as honey bees, ants, wasps and termites. I set out to replicate this discovery and verify its reproducibility. Using blind, controlled experiments, I found that n-pentacosane (C25) does indeed negatively affect worker ovary development. Moreover, the pheromone affects both large and small workers, and applies to workers from large, mature colonies as well as young colonies. Given that C25 is readily available and that bumblebees are popular study organisms, I hope that this replication will encourage other researchers to tackle the many research questions enabled by the discovery of a queen pheromone.

Molecular surveillance of pvdhfr, pvdhps, and pvmdr-1 mutations in Plasmodium vivax isolates from Yunnan and Anhui provinces of China

BackgroundPlasmodium vivax is the predominant species of human malaria parasites present in China. Although sulphadoxine-pyrimethamine (SP) and chloroquine (CQ) have been widely used for malaria treatment in China, the resistance profiles of these drugs are not available. Analysis of dihydrofolate reductase (dhfr), dihydropteroate synthase (dhps), and multidrug resistance (mdr-1) gene mutations in P. vivax isolates is a valuable molecular approach for mapping resistance to SP and CQ. This study investigates the prevalence of pvdhfr, pvdhps, and pvmdr-1 of P. vivax clinical isolates from China and provides baseline molecular epidemiologic data on SP- and CQ-associated resistance in P. vivax.MethodsPlasmodium vivax clinical isolates were collected from two malaria-endemic regions of China, subtropical (Xishuangbanna, Yunnan province) and temperate (Bozhou, Anhui province), from 2009 to 2012. All isolates were analysed for single nucleotide polymorphism haplotypes in pvdhfr, pvdhps, and pvmdr-1 using direct DNA sequencing.ResultsIn pvdhfr, 15% of Xishuangbanna isolates carried wild-type (WT) allele, whereas the majority of isolates carried mutant genes with substitutions at five codons. Eight mutant haplotypes of pvdhfr were detected, while limited polymorphism of pvdhfr was found in Bozhou isolates. A size polymorphism was present in pvdhfr, with the three-repeat type being the most predominate in both Xishuangbanna (79%) and Bozhou (97%) isolates. In pvdhps, mutations at four codons were detected in Xishuangbanna isolates leading to six haplotypes, including WT allele, single-mutation, double-mutation, and triple-mutation alleles. All Bozhou isolates carried WT pvhdps. In pvmdr-1, isolates from Xishuangbanna carried mutations at codons Y976F and F1076L, whereas all isolates from Bozhou had only a single mutation at codon F1076L.ConclusionsPlasmodium vivax isolates from subtropical and temperate zones of China are shown to have dramatically different frequencies and patterns of mutations in pvdhfr, pvdhps, and pvmdr-1. Whereas P. vivax populations in subtropical China are highly resistant to SP and CQ, those in the temperate zone may still be susceptible to SP and CQ. This information is useful for establishing treatment policy and provides a baseline for molecular surveillance of drug-resistant P. vivax in these areas.Electronic supplementary materialThe online version of this article (doi:10.1186/1475-2875-13-346) contains supplementary material, which is available to authorized users.

Gender based disruptive selection maintains body size polymorphism in Drosophila melanogaster.

Darwinian fitness in holometabolous insects like the fruit fly Drosophila melanogaster is reported to be positively correlated with body size. If large individuals in a population have higher fitness, then one would expect directional selection to operate leading to uniformly large individuals. However, size polymorphism persists in nature and needs further probing. We assessed the effect of body size on some of the fitness and fitness-related traits in replicate populations of genotypically large, genotypically small and phenotypically small D. melanogaster flies. In this study, the time taken to attain reproductive maturity and copulation duration were independent of fly size. Fecundity and longevity of large females were significantly higher when they partnered genotypically small males than when they were with genotypically larger or phenotypically small males. The increased female longevity when in association with genotypically small males was not due to selective early death of males that would release the female partner from presumed cost of persistent courtship. On the contrary, the genotypically as well as phenotypically small males had significantly higher longevity than large males. The virility of the genotypically small males was not significantly different from that of genotypically large males. Our results clearly show that selection on body size operates in the opposite direction (disruptive selection) for the two genders, thus explaining the persistence of size polymorphisms in the holometabolous insect, Drosophila melanogaster.

Density of mushroom body synaptic complexes limits intraspecies brain miniaturization in highly polymorphic leaf-cutting ant workers.

Hymenoptera possess voluminous mushroom bodies (MBs), brain centres associated with sensory integration, learning and memory. The mushroom body input region (calyx) is organized in distinct synaptic complexes (microglomeruli, MG) that can be quantified to analyse body size-related phenotypic plasticity of synaptic microcircuits in these small brains. Leaf-cutting ant workers (Atta vollenweideri) exhibit an enormous size polymorphism, which makes them outstanding to investigate neuronal adaptations underlying division of labour and brain miniaturization. We particularly asked how size-related division of labour in polymorphic workers is reflected in volume and total numbers of MG in olfactory calyx subregions. Whole brains of mini, media and large workers were immunolabelled with anti-synapsin antibodies, and mushroom body volumes as well as densities and absolute numbers of MG were determined by confocal imaging and three-dimensional analyses. The total brain volume and absolute volumes of olfactory mushroom body subdivisions were positively correlated with head widths, but mini workers had significantly larger MB to total brain ratios. Interestingly, the density of olfactory MG was remarkably independent from worker size. Consequently, absolute numbers of olfactory MG still were approximately three times higher in large compared with mini workers. The results show that the maximum packing density of synaptic microcircuits may represent a species-specific limit to brain miniaturization.

IMP-HRM: an automated pipeline for high throughput SNP marker resource development for molecular breeding in orphan crops

Orphan crops have played a major role in daily diet, health nourishment, economy and livelihood of marginal farmers in under developed and developing world. For various reasons, the majority of these crops including finger millet and tef in cereals; lentil, cowpea and groundnut in legumes; cassava and yam in root crops; have remained neglected and underutilized. With little or no investment these ‘orphan’ crops have lagged far behind in developing genomic resources and are deprived of the application of advanced molecular breeding approaches for their rapid improvement. Single nucleotide polymorphisms, multiple nucleotide polymorphisms, insertions/deletions (indels) and size polymorphisms are important tools for developing rich molecular marker resources. Cataloguing and use of intron based polymorphism have also been demonstrated for applications in molecular breeding. Currently the process of predicting putative introns and designing flanking primers for their amplification requires multiple computer programs and a high level of human intervention. We automated this process by developing intron mapping pipeline (IMP) which allows the generation of large primer sets with minimal human intervention and greater efficiency. Since IMP can take advantage of the highly conserved nature of the introns flanking sequences across a wide range of species, any available model plant genome can be used to predict intron boundaries in related orphan crop species. IMP combined with high resolution melt analysis demonstrated potential for high throughput polymorphism discovery, validation and molecular marker development platform which can generate genomic resources rapidly in orphan species.

First cytogenetic characterization of the giant Amazonian catfishBrachyplatystoma filamentosum(Siluriformes, Pimelodidae)

In contrast to the enormous variability of Neotropical fish species, genetic information about many groups is not yet available. Chromosomal studies have greatly contributed to the characterization of several species, providing important data on these animals. We performed the first cytogenetic characterization of the Amazonian fish species Brachyplatystoma filamentosum (Pimelodidae), popularly known as “piraíba”. The results revealed a diploid number of 2n = 56 composed of 24 metacentric, 12 submetacentric, and 10 acrocentric chromosomes in both females and males. After silver nitrate treatment (AgNORs) it was possible to visualize the nucleolus organizer region located in the terminal portion of the short arms of subtelocentric chromosome pair 22, presenting size polymorphism. Hybridization with 18S and 5S rDNA probes confirmed the number and location of 18S marks rDNA in pair 22 and differences in the size of signals among homologs. The 5S rDNA genes were localized near the centromere on the short arms of chromosome pair 19. Constitutive heterochromatin (C-bands) were localized predominantly in the terminal regions of the chromosomes, and also occurred in some interstitial and centromeric positions. The chromosomal genetic data obtained in this study contribute to the biological characterization of B. filamentosum, which has economic and ecological importance as the largest freshwater catfish occurring in many rivers of the Amazon and Tocantins-Araguaia basins in Brazil. These results may also be used in to infer relationships among Pimelodidae species.

Simultaneous quantitation and size characterization of apolipoprotein(a) by ultra-performance liquid chromatography/mass spectrometry

Apolipoprotein(a) is a polymorphic glycoprotein covalently bound to apoB100 in Lp(a) particles and has been described to be both atherogenic and prothrombotic, although its exact mechanism of action is not well defined. Apolipoprotein(a) is routinely measured by immunoassays. Unfortunately, the accuracy of the measurement can be affected by the apolipoprotein(a) size (number of kringles) polymorphism in Lp(a) particles. Here we describe an ultra-performance liquid chromatography/mass spectrometry (UPLC/MS) assay that is capable of measuring apolipoprotein(a) concentrations while simultaneously determining the number of kringles present per protein. Plasma samples were diluted and proteins de-lipidated with deoxycholate prior to tryptic digestion. Distinct tryptic peptides from different regions of apolipoprotein(a) were measured to determine both concentration and the number of kringles present per protein. Separation and quantitation of tryptic peptides is carried out at 700 μL/min using a 1.7 µm C18 column (2.1 × 100 mm) coupled to a Thermo Vantage triple quadrupole (QQQ) mass spectrometer with a heated electrospray ionization (HESI) source. This method was compared to established methods for measuring concentration (monoclonal antibody based ELISA) and size (gel-electrophoresis) using 80 plasma samples proved by NWLRL. The slope and r(2) value for the correlation of concentrations were determined to be 0.96 and 0.98, demonstrating excellent agreement of absolute values between the UPLC/MS and ELISA methods. As measured by UPLC/MS, the average kringle number or size is smaller than determined by the electrophoretic method. A single UPLC/MS method was developed capable of measuring apolipoprotein(a) concentration and size (by measuring the number of kringles per protein). This assay passes criteria required for 'fit for purpose' assays including sensitivity, intra and interday reproducibility and freeze/thaw stability. While the agreement between UPLC/MS and ELISA is excellent for concentration and may provide researchers with additional tools for studying apolipoprotein(a), the dissimilarities between UPLC/MS and the electrophoretic method may also be exploited for understanding apolipoprotein(a) structure and function.

Social network analysis resolves temporal dynamics of male dominance relationships

Social organization is often studied through point estimates of individual association or interaction patterns, which does not account for temporal changes in the course of familiarization processes and the establishment of social dominance. Here, we present new insights on short-term temporal dynamics in social organization of mixed-sex groups that have the potential to affect sexual selection patterns. Using the live-bearing Atlantic molly (Poecilia mexicana), a species with pronounced male size polymorphism, we investigated social network dynamics of mixed sex experimental groups consisting of eight females and three different-sized males over a period of 5 days. Analyzing association-based social networks as well as direct measures of spatial proximity, we found that large males tended to monopolize most females, while excluding small- and medium-bodied males from access to females. This effect, however, emerged only gradually over time, and different-sized males had equal access to females on day 1 as well as day 2, though to a lesser extent. In this highly aggressive species with strong social dominance stratifications, the observed temporal dynamics in male-female association patterns may balance the presumed reproductive skew among differentially competitive male phenotypes when social structures are unstable (i.e., when individual turnover rates are moderate to high). Ultimately, our results point toward context-dependent sexual selection arising from temporal shifts in social organization.