Female preferences for single and combined traits in computer animated stickleback males

In many animal species, males have more than one secondary sexual character. Apart from theoretical considerations about the evolution of multiple traits, there are almost no empirical studies on female mate choice decisions based on combinations of traits as opposed to decisions based on single traits. Because three-spined sticklebacks are exceptionally well suited to be tested with computer animation technique, which itself fills the gap of adequate test paradigms for multiple traits, we tested female sticklebacks for their preferences for both single and combined male traits. We used virtual stickleback males that differed either in red throat coloration, courtship intensity, body size, or in combinations of these traits. The virtual male with increased redness was found to be preferred by females, whereas the male courting more intensely was not. The tests for combinations of traits revealed the more pronounced female preferences, the more traits were available to the females to judge male qualit

Courting virtual rivals increase ejaculate size in sticklebacks ( Gasterosteus aculeatus )

Sperm competition occurs when sperm of two or more males compete to fertilize a given set of eggs. Game-theory models of sperm competition predict that males, which face an increased risk of sperm competition, will invest more sperm in a mating. In the pair-spawning three-spined stickleback (Gasterosteus aculeatus), males attempt to steal fertilizations (i.e. to sneak) when they are in the courting phase, but not when they are parental. The behaviour of neighbouring males may therefore indicate the risk of sperm competition. We visually confronted males before spawning with computer animations of the same virtual stickleback showing two different behaviours: either courting (high risk of sperm competition) or brood-caring (low risk of sperm competition). We show that males invest significantly more sperm (absolutely and relatively with respect to available sperm in the testes) after the courting stimulus. The relative investment ratio between the courting and the brood-caring treatment was on average 1.75. Three-spined sticklebacks thus seem to assess the risk of sperm competition by the behaviour of neighbours and to adjust their ejaculate accordingly. This result suggests that the evolutionary force of sperm competition has led to precise mechanisms of future risk assessmen

Identification of the galactosyltransferase of Cryptococcus neoformans involved in the biosynthesis of basidiomycete-type glycosylinositolphosphoceramide

The pathogenic fungus Cryptococcus neoformans synthesizes a complex family of glycosylinositolphosphoceramide (GIPC) structures. These glycosphingolipids (GSLs) consist of mannosylinositolphosphoceramide (MIPC) extended by β1-6-linked galactose, a unique structure that has to date only been identified in basidiomycetes. Further extension by up to five mannose residues and a branching xylose has been described. In this study, we identified and determined the gene structure of the enzyme Ggt1, which catalyzes the transfer of a galactose residue to MIPC. Deletion of the gene in C. neoformans resulted in complete loss of GIPCs containing galactose, a phenotype that could be restored by the episomal expression of Ggt1 in the deletion mutant. The entire annotated open reading frame, encoding a C-terminal GT31 galactosyltransferase domain and a large N-terminal domain of unknown function, was required for complementation. Notably, this gene does not encode a predicted signal sequence or transmembrane domain. The demonstration that Ggt1 is responsible for the transfer of a galactose residue to a GSL thus raises questions regarding the topology of this biosynthetic pathway and the function of the N-terminal domain. Phylogenetic analysis of the GGT1 gene shows conservation in hetero- and homobasidiomycetes but no homologs in ascomycetes or outside of the fungal kingdo

Female preferences for single and combined traits in computer animated stickleback males

In many animal species, males have more than one secondary sexual character. Apart from theoretical considerations about the evolution of multiple traits, there are almost no empirical studies on female mate choice decisions based on combinations of traits as opposed to decisions based on single traits. Because three-spined sticklebacks are exceptionally well suited to be tested with computer animation technique, which itself fills the gap of adequate test paradigms for multiple traits, we tested female sticklebacks for their preferences for both single and combined male traits. We used virtual stickleback males that differed either in red throat coloration, courtship intensity, body size, or in combinations of these traits. The virtual male with increased redness was found to be preferred by females, whereas the male courting more intensely was not. The tests for combinations of traits revealed the more pronounced female preferences, the more traits were available to the females to judge male quality

Targeted Gene Silencing in the Model Mushroom Coprinopsis cinerea (Coprinus cinereus) by Expression of Homologous Hairpin RNAs

The ink cap Coprinopsis cinerea is a model organism for studying fruiting body (mushroom) formation in homobasidiomycetes. Mutant screens and expression studies have implicated a number of genes in this developmental process. Functional analysis of these genes, however, is hampered by the lack of reliable reverse genetics tools for C. cinerea. Here, we report the applicability of gene targeting by RNA silencing for this organism. Efficient silencing of both an introduced GFP expression cassette and the endogenous cgl1 and cgl2 isogenes was achieved by expression of homologous hairpin RNAs. In latter case, silencing was the result of a hairpin construct containing solely cgl2 sequences, demonstrating the possibility of simultaneous silencing of whole gene families by a single construct. Expression of the hairpin RNAs reduced the mRNA levels of the target genes by at least 90%, as determined by quantitative real-time PCR. The reduced mRNA levels were accompanied by cytosine methylation of transcribed and nontranscribed DNA at both silencing and target loci in the case of constitutive high-level expression of the hairpin RNA but not in the case of transient expression. These results suggest the presence of both posttranscriptional and transcriptional gene silencing mechanisms in C. cinerea and demonstrate the applicability of targeted gene silencing as a powerful reverse genetics approach in this organism