About a transmissible influence through several generations in a clone of the rotifer notommata copeus EHR

Over ten years, the individuals of an orthoclone of Notommata copeus gradually lost their sensitivity to photoperiod. This loss is transmissible but reversible in three generations. It is endogenous but not chromosomal. The hypothesis is forwarded that it is induced by external factors, and quite possibly crowding.     

Expression of wild-type GBSS transgenes in the off-spring of partially and fully complementedamylose-free transformants of potato

Theamylose-free (amf) potato mutant can easily be complemented through introduction of the wild-type gene coding for granule-bound starch synthase (GBSS). After iodine staining the starch of theamf mutant is red whereas that of the wild type and the complementedamf mutant is blue. The level of complementation of selected transformants and their sexual off-spring after backcrossing withamf was investigated using sporophytic tuber cells and gametophytic microspore cells. Two diploid and two tetraploid transformants with full complementation demonstrated the expected segregation patterns of 1:1 (one active insert) or 3:1 (two independently segregating active inserts) in the microspores and in the F1 offspring based on staining of tubers. All expected genotypes in the F1 generation were found, based on microspore segregation patterns of the individual F1 plants. Two transformants with partial complementation (mixed phenotypes) were investigated. One of them, B1, was tetraploid and duplex for the GBSS insert, which had originated through mitotic doubling of the transformed diploid cells. In the F1 generation three phenotypic classes were found:amf, fully complemented and partially complemented. The latter two classes exist independently of a simplex or duplex gene status. The second transformant with partial complementation, B10, appeared to have a complex molecular composition. One cluster of five transgenes caused the partial complementation. Fully and partially complemented phenotypic classes were found after crossing B10 with theamf mutant. Indications were found that the ploidy level of the tissue in which the genes were introduced and expressed played an important role. Firstly, partial complementation was found after transformation of the diploid and not of the tetraploidamf genotypes. Secondly, the level of complementation was higher in tissue with lower ploidy levels, as illustrated by the colour of the starch inin vitro tubers (2x–4x cells) versus field-grown tubers (16x–64x).     

Five Misunderstandings About Cultural Evolution

Recent debates about memetics have revealed some widespread misunderstandings about Darwinian approaches to cultural evolution. Drawing from these debates, this paper disputes five common claims: (1) mental representations are rarely discrete, and therefore models that assume discrete, gene-like particles (i.e., replicators) are useless; (2) replicators are necessary for cumulative, adaptive evolution; (3) content-dependent psychological biases are the only important processes that affect the spread of cultural representations; (4) the “cultural fitness” of a mental representation can be inferred from its successful transmission; and (5) selective forces only matter if the sources of variation are random. We close by sketching the outlines of a unified evolutionary science of culture.

Uniparental mitochondrial DNA inheritance is not affected in Ustilago maydis Δatg11 mutants blocked in mitophagy

Background

Maternal or uniparental inheritance (UPI) of mitochondria is generally observed in sexual eukaryotes, however, the underlying mechanisms are diverse and largely unknown. Recently, based on the use of mutants blocked in autophagy, it has been demonstrated that autophagy is required for strict maternal inheritance in the nematode Caenorhabditis elegans. Uniparental mitochondrial DNA (mtDNA) inheritance has been well documented for numerous fungal species, and in particular, has been shown to be genetically governed by the mating-type loci in the isogamous species Cryptococcus neoformans, Phycomyces blakesleeanus and Ustilago maydis. Previously, we have shown that the a2 mating-type locus gene lga2 is decisive for UPI during sexual development of U. maydis. In axenic culture, conditional overexpression of lga2 triggers efficient loss of mtDNA as well as mitophagy. To assess a functional relationship, we have investigated UPI in U. maydis Δatg11 mutants, which are blocked in mitophagy.

Results

This study has revealed that Δatg11 mutants are not affected in pathogenic development and this has allowed us to analyse UPI under comparable developmental conditions between mating-compatible wild-type and mutant strain combinations. Explicitly, we have examined two independent strain combinations that gave rise to different efficiencies of UPI. We demonstrate that in both cases UPI is atg11-independent, providing evidence that mitophagy is not critical for UPI in U. maydis, even under conditions of strict UPI.

Conclusions

Until now, analysis of a role of mitophagy in UPI has not been reported for microbial species. Our study suggests that selective autophagy does not contribute to UPI in U. maydis, but is rather a consequence of selective mtDNA elimination in response to mitochondrial damage.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-015-0358-z) contains supplementary material, which is available to authorized users.     

Property and wealth inequality as cultural niche construction

In contrast to other approaches, evolutionary perspectives on understanding the power and wealth inequalities in human societies view wealth and power not as ends in themselves but as proximate goals that contribute to the ultimate Darwinian goal of achieving reproductive success. The most successful means of achieving it in specific times and places depend on local conditions and these have changed in the course of human history, to such an extent that strategies focused on the maintenance and increase of wealth can even be more successful in reproductive terms than strategies directed at maximizing reproductive success in the short term. This paper argues that a major factor leading to such changes is a shift in the nature of inter-generational wealth transfers from relatively intangible to material property resources and the opportunities these provided for massively increased inequality. This shift can be seen as a process of niche construction related to the increasing importance of fixed and defensible resources in many societies after the end of the last Ice Age. It is suggested that, despite problems of inference, the evidence of the archaeological record can be used to throw light on these processes in specific places and times.     

Inheritance of stomatal conductance in cotton (Gossypium barbadense)

Stomatal conductance in improved Pima cotton cultivars (Gossypium barbadense) has been previously shown to be positively associated with heat resistance and yield potential. In the present study we determined the mode of inheritance of stomatal conductance in crosses of six G. barbadense parents varying in origin, degree of agronomic development and stomatal conductance. Parents included a primitive tropical cotton (B368), two obsolete cultivars (St Vincent V135, Pima 32), one modern commercial line (Pima S-6) and two elite genotypes of the Pima germplasm (P70, P73). These lines showed distinct differences in stomatal conductance, under greenhouse and field conditions. The primitive B368 had the lowest conductance, and the elite lines the highest. Generation means analysis was used to quantify genetic effects in the crosses P70 × St Vincent V135, Pima S-6 × B368, Pima S-6 × Pima 32, P73 × Pima 32 and P73 × Pima S-6. Best-fit models of the inheritance of stomatal conductance varied in complexity from a simple additive-dominance model in the cross P70 × St. Vincent V135 to models displaying digenic epistatic interactions in the remaining crosses. Significant additive mean effects for stomatal conductance were detected in all crosses. Dominance mean effects were significant in the crosses P73 × Pima 32 and P73 × Pima S-6. Broadsense heritability estimates of stomatal conductance were relatively low (0.16–0.44) in all crosses except Pima S-6 × B368 (0.74). Results also show that the mode of inheritance of stomatal conductance is multigenic, and may have maternal as well as nuclear components. Recouping higher stomatal conductance levels from genetically wider crosses appears feasible and could proceed at a moderate rate. Fixing higher levels of stomatal conductance in populations from crosses of elite germplasm may be more difficult because of the presence of dominant mean effects and digenic epistatic interactions.     

Chloroplast DNA inheritance in theStellaria longipes complex (Caryophyllaceae)

Inheritance of chloroplast DNA (cpDNA) was examined in F₁ progenies derived from three crosses and three corresponding reciprocal crosses betweenStellaria porsildii andS. longifolia. Chloroplast DNA restriction fragments were analyzed using methods of nonradioactive digoxigenin-11-dUTP labeling and chemiluminescent detection with Lumi-Phos 530. Distinct interspecific restriction fragment polymorphisms were identified and used to demonstrate the mode of cpDNA inheritance. Mode of cpDNA inheritance differed among crosses. Two crosses in whichS. porsildii, SP2920-21, was the maternal parent exhibited three different types of plastids, maternal, paternal and biparental, among the F₁ hybrids, suggesting a biparental cpDNA inheritance and plastid sorting-out inStellaria.