Sex ratio and gamete size across eastern North America in Dictyostelium discoideum, a social amoeba with three sexes

Theory indicates that numbers of mating types should tend towards infinity or remain at two. The social amoeba, Dictyostelium discoideum, however, has three mating types. It is therefore a mystery how this species has broken the threshold of two mating types, but has not increased towards a much higher number. Frequency-dependent selection on rare types in combination with isogamy, a form of reproduction involving gametes similar in size, could explain the evolution of multiple mating types in this system. Other factors, such as drift, may be preventing the evolution of more than three. We first looked for evidence of isogamy by measuring gamete size associated with each type. We found no evidence of size dissimilarities between gametes. We then looked for evidence of balancing selection, by examining mating type distributions in natural populations and comparing genetic differentiation at the mating type locus to that at more neutral loci. We found that mating type frequency varied among the three populations we examined, with only one of the three showing an even sex ratio, which does not support balancing selection. However, we found more population structure at neutral loci than the mating type locus, suggesting that the three mating types are indeed maintained at intermediate frequencies by balancing selection. Overall, the data are consistent with balancing selection acting on D. discoideum mating types, but with a sufficiently weak rare sex advantage to allow for drift, a potential explanation for why these amoebae have only three mating types

Editorial: Advances in the Understanding of the Commensal Eukaryota and Viruses of the Herbivore Gut

Herbivores play an important role in the survival of humanity, contributing food and textiles, as well as social and economic value. For decades, optimizing the productivity, health, welfare, and environmental footprint of herbivorous animals, particularly ruminant livestock, has been the subject of an extensive, global research effort. Much of this research effort has focused on the herbivore gut. The specialized nature of the herbivore digestive tract and its resident microbes enables the breakdown of highly fibrous plant materials, which are unable to be utilized by omnivores and carnivores. In recent years, the bacteria and methanogenic archaea have been the major focus of research efforts, with the other gut microbes being understudied in comparison

Assessment of the Accuracy of High-Throughput Sequencing of the ITS1 Region of Neocallimastigomycota for Community Composition Analysis

Anaerobic fungi (Neocallimastigomycota) are common inhabitants of the digestive tract of large mammalian herbivores, where they make an important contribution to plant biomass degradation. The internal transcribed spacer 1 (ITS1) region is currently the molecular marker of choice for anaerobic fungal community analysis, despite its known size polymorphism and heterogeneity. The aim of this study was to assess the accuracy of high-throughput sequencing of the ITS1 region of anaerobic fungi for community composition analysis. To this end, full-length ITS1 clone libraries from five pure cultures, representing the ITS1 region size range, were Sanger sequenced to generate a reference dataset. Barcoded amplicons of the same five pure cultures, and four different mock communities derived from them, were then sequenced using Illumina HiSeq. The resulting sequences were then assessed in relation to either the reference dataset (for the pure cultures) or the corresponding theoretical mock communities. Annotation of sequences obtained from individual pure cultures was not always consistent at the clade or genus level, irrespective of whether data from clone libraries or high-throughput sequencing were analyzed. The detection limit of the high-throughput sequencing method appeared to be influenced by factors other than the parameters used during data processing, as some taxa with theoretical values >0.6% were not detected in the mock communities. The high number of PCR cycles used was considered to be a potential explanation for this observation. Accuracy of two of the four mock communities was limited, and this was speculated to be due to preferential amplification of smaller sized ITS1 regions. If this is true, then this is predicted to be an issue with only six of the 32 named anaerobic fungal clades. Whilst high-throughput sequencing of the ITS1 region from anaerobic fungi can be used for environmental sample analysis, we conclude that the accuracy of the method is influenced by sample community composition. Furthermore, ambiguity in the annotation of sequences within pure cultures due to ITS1 heterogeneity reinforces the limitations of the ITS1 region for the taxonomic assignment of anaerobic fungi. In order to overcome these issues, there is a need to develop an alternative taxonomic marker for anaerobic fungi.</p

Cut-lengths of perennial ryegrass leaf-blades influences in vitro fermentation by the anaerobic fungus neocallimastix frontalis

Anaerobic fungi in the gut of domesticated and wild mammalian herbivores play a key role in the host’s ability to utilize plant biomass. Due to their highly effective ability to enzymatically degrade lignocellulose, anaerobic fungi are biotechnologically interesting. Numerous factors have been shown to affect the ability of anaerobic fungi to break down plant biomass. However, methods to reduce the non-productive lag time in batch cultures and the effect of leaf-blade cut-length and condition on the fungal fermentation are not known. Therefore, experimentation using a novel gas production approach with pre-grown, axenic cultures of Neocallimastix frontalis was performed using both fresh and air-dried perennial ryegrass leaf-blades of different cut-lengths. The methodology adopted removed the lag-phase and demonstrated the digestion of un-autoclaved leaf-blades. Fermentation of leaf-blades of 4.0 cm cut-length produced 18.4% more gas yet retained 11.2% more apparent DM relative to 0.5 cm cut-length leaf-blades. Drying did not affect fermentation by N. frontalis, although an interaction between drying and leaf-blade cut-length was noted. Removal of the lag phase and the use of un-autoclaved substrates are important when considering the biotechnological potential of anaerobic fungi. A hypothesis based upon sporulation at cut surfaces is proposed to describe the experimental results

The meaning of postpartum sexual health for women living in Spain : a phenomenological inquiry

Sexual health is a multidimensional phenomenon constructed by personal, social, and cultural factors but continues to be studied with a biomedical approach. During the postpartum period, a woman transitions to mother, as well as partner-to-parent and couple-to-family. There are new realities in life in the postpartum period, including household changes and new responsibilities that can impact the quality of sexual health. This phenomenon is understudied especially in the context of Spain. The purpose of this study was to describe the lived experience of postpartum sexual health among primiparous women giving birth in Catalonia (Spain). This was a phenomenological study with a purposive sample of primiparous women. Data was collected through semi-structured interviews until saturation. Analysis followed Colaizzi's seven-step process with an eighth translation step added to limit cross-cultural threats to validity. Also, the four dimensions of trustworthiness were established through strategies and techniques during data collection and analysis. Ten women were interviewed from which five themes emerged, including: Not feeling ready, inhibiting factors, new reality at home, socio-cultural factors, and the clinician within the health system. Returning to sexual health led women to engage in experiential learning through trial and error. Most participants reported reduced libido, experienced altered body image, and recounted resumption of sexual activity before feeling ready. A common finding was fatigue and feeling overloaded by the demands of the newborn. Partner support was described as essential to returning to a meaningful relationship. Discussions about postpartum sexual health with clinicians were described as taboo, and largely absent from the care model. Evidence-based practices should incorporate the best evidence from research, consider the postpartum sexual health experiences and preferences of the woman, and use clinician expertise in discussions that include the topic of postpartum sexual health to make decisions. As such, human caring practices should be incorporated into clinical guidelines to recognize the preferences of women. Clinicians need to be authentically present, engage in active communication, and individualize their care. More qualitative studies are needed to understand postpartum sexual health in different contexts, cultures, and countries and to identify similarities and differences through meta-synthesis

Segregate or cooperate- a study of the interaction between two species of Dictyostelium

<p>Abstract</p> <p>Background</p> <p>A major challenge for evolutionary biology is explaining altruism, particularly when it involves death of one party and occurs across species. Chimeric fruiting bodies of <it>Dictyostelium discoideum </it>and <it>Dictyostelium purpureum </it>develop from formerly independent amoebae, and some die to help others. Here we examine co-aggregation between <it>D. discoideum </it>and <it>D. purpureum</it>, determine its frequency and which party benefits, and the extent of fair play in contribution to the altruistic caste.</p> <p>Results</p> <p>We mixed cells from both species in equal proportions, and then we analyzed 198 individual fruiting bodies, which always had either a <it>D. discoideum </it>or <it>D. purpureum </it>phenotype (<it>D. discoideum</it>- 98, <it>D. purpureum</it>- 100). Fifty percent of the fruiting bodies that looked like <it>D. discoideum </it>and 22% of the fruiting bodies that looked like <it>D. purpureum </it>were chimeric, though the majority of spores in any given fruiting body belonged to one species (<it>D. discoideum </it>fruiting bodies- 0.85 ± 0.03, <it>D. purpureum </it>fruiting bodies- 0.94 ± 0.02). Clearly, there is species level recognition occurring that keeps the cells mostly separate. The number of fruiting bodies produced with the <it>D. discoideum </it>phenotype increased from 225 ± 32 fruiting bodies when <it>D. discoideum </it>was alone to 486 ± 61 in the mix treatments. However, the number of <it>D. discoideum </it>spores decreased, although not significantly, from 2.75e⁷± 1.29e⁷spores in the controls to 2.06e⁷± 8.33e⁶spores in the mix treatments. <it>D. purpureum </it>fruiting body and spore production decreased from 719 ± 111 fruiting bodies and 5.81e⁷± 1.26e⁷spores in the controls to 394 ± 111 fruiting bodies and 9.75e⁶± 2.25e⁶spores in the mix treatments.</p> <p>Conclusion</p> <p>Both species appear to favor clonality but can cooperate with each other to produce fruiting bodies. Cooperating amoebae are able to make larger fruiting bodies, which are advantageous for migration and dispersal, but both species here suffer a cost in producing fewer spores per fruiting body.</p