Absence of single-locus complementary sex determination in the braconid wasps Asobara tabida and Alysia manducator

In species with single-locus complementary sex determination (sl-CSD), sex is determined by multiple alleles at a single locus. In the haplodiploid Hymenoptera, sl-CSD results in females, if individuals are heterozygous at the sex locus, and in males, if individuals are hemizygous (haploid males) or homozygous (diploid males). Several hymenopteran species have been shown to have sl-CSD, but in several others sl-CSD is absent and the phylogenetic distribution remains unclear. In the family Braconidae, all four species tested so far were shown to possess sl-CSD. In this study, inbreeding experiments were used to test for the presence of sl-CSD in two species belonging to a subfamily of the Braconidae, Asobara tabida and Alysia manducator (Alysiinae). In both species inbreeding experiments showed no difference in brood size or sex ratio compared to the (outbred) control group. Furthermore, the sex ratios found in the inbreeding treatment differed significantly from the sex ratios expected under sl-CSD. Therefore, we conclude that sl-CSD is absent in these species. This study is the first to show the lack of sl-CSD in species of the Braconidae family and that hymenopteran sex-determining mechanisms can vary, even within a family.

About females and males: continuity and discontinuity in flies

Through the decades of relentless and dedicated studies in Drosophila melanogaster, the pathway that governs sexual development has been elucidated in great detail and has become a paradigm in understanding fundamental cell-fate decisions. However, recent phylogenetic studies show that the molecular strategy used in Drosophila deviates in some important aspects from those found in other dipteran flies and suggest that the Drosophila pathway is likely to be a derivative of a simpler and more common principle. In this essay, I will discuss the evolutionary plasticity of the sex-determining pathway based on studies in the common housefly, Musca domestica. Diversification appears to primarily arise from subtle differences in the regulation of the key switch gene transformer at the top of the pathway. On the basis of these findings I propose a new idea on how the Drosophila pathway may have evolved from a more archetypal system such as in M. domestica. In essence, the arrival of an X counting mechanism mediated by Sex-lethal to compensate for X linked gene dose differences set the stage for an intimate coupling of the two pathways. Its precedent recruitment to the dosage compensation pathway allowed for an intervention in the regulation of transformer where it gradually and eventually' completely substituted for a need of transformer autoregulation

Alternative patterns of sex chromosome differentiation in Aedes aegypti (L).

BACKGROUND: Some populations of West African Aedes aegypti, the dengue and zika vector, are reproductively incompatible; our earlier study showed that divergence and rearrangements of genes on chromosome 1, which bears the sex locus (M), may be involved. We also previously described a proposed cryptic subspecies SenAae (PK10, Senegal) that had many more high inter-sex FST genes on chromosome 1 than did Ae.aegypti aegypti (Aaa, Pai Lom, Thailand). The current work more thoroughly explores the significance of those findings. RESULTS: Intersex standardized variance (FST) of single nucleotide polymorphisms (SNPs) was characterized from genomic exome capture libraries of both sexes in representative natural populations of Aaa and SenAae. Our goal was to identify SNPs that varied in frequency between males and females, and most were expected to occur on chromosome 1. Use of the assembled AaegL4 reference alleviated the previous problem of unmapped genes. Because the M locus gene nix was not captured and not present in AaegL4, the male-determining locus, per se, was not explored. Sex-associated genes were those with FST values ≥ 0.100 and/or with increased expected heterozygosity (H exp , one-sided T-test, p < 0.05) in males. There were 85 genes common to both collections with high inter-sex FST values; all genes but one were located on chromosome 1. Aaa showed the expected cluster of high inter-sex FST genes proximal to the M locus, whereas SenAae had inter-sex FST genes along the length of chromosome 1. In addition, the Aaa M-locus proximal region showed increased H exp levels in males, whereas SenAae did not. In SenAae, chromosomal rearrangements and subsequent suppressed recombination may have accelerated X-Y differentiation. CONCLUSIONS: The evidence presented here is consistent with differential evolution of proto-Y chromosomes in Aaa and SenAae

Sex Determination:Why So Many Ways of Doing It?

Sexual reproduction is an ancient feature of life on earth, and the familiar X and Y chromosomes in humans and other model species have led to the impression that sex determination mechanisms are old and conserved. In fact, males and females are determined by diverse mechanisms that evolve rapidly in many taxa. Yet this diversity in primary sex-determining signals is coupled with conserved molecular pathways that trigger male or female development. Conflicting selection on different parts of the genome and on the two sexes may drive many of these transitions, but few systems with rapid turnover of sex determination mechanisms have been rigorously studied. Here we survey our current understanding of how and why sex determination evolves in animals and plants and identify important gaps in our knowledge that present exciting research opportunities to characterize the evolutionary forces and molecular pathways underlying the evolution of sex determination

ZigBee Device Verification for Securing Industrial Control and Building Automation Systems

Improved wireless ZigBee network security provides a means to mitigate malicious network activity due to unauthorized devices. Security enhancement using RF-based features can augment conventional bit-level security approaches that are solely based on the MAC addresses of ZigBee devices. This paper presents a device identity verification process using RF fingerprints from like-model CC2420 2.4 GHz ZigBee device transmissions in operational indoor scenarios involving line-of-sight and through-wall propagation channels, as well as an anechoic chamber representing near-ideal conditions. A trained multiple discriminant analysis model was generated using normalized multivariate Gaussian test statistics from authorized network devices. Authorized device classification and ID verification were assessed using pre-classification Kolmogorov-Smirnov (KS) feature ranking and post-classification generalized relevance learning vector quantization improved (GRLVQI) relevance ranking. A true verification rate greater than 90% and a false verification rate less than 10% were obtained when assessing authorized device IDs. When additional rogue devices were introduced that attempted to gain unauthorized network access by spoofing the bit-level credentials of authorized devices, the KS-test feature set achieved a true verification rate greater than 90% and a rogue reject rate greater than 90% in 29 of 36 rogue scenarios while the GRLVQI feature set was successful in 28 of 36 scenarios. Abstract © Springe

ZigBee Device Verification for Securing Industrial Control and Building Automation Systems

Improved wireless ZigBee network security provides a means to mitigate malicious network activity due to unauthorized devices. Security enhancement using RF-based features can augment conventional bit-level security approaches that are solely based on the MAC addresses of ZigBee devices. This paper presents a device identity verification process using RF fingerprints from like-model CC2420 2.4 GHz ZigBee device transmissions in operational indoor scenarios involving line-of-sight and through-wall propagation channels, as well as an anechoic chamber representing near-ideal conditions. A trained multiple discriminant analysis model was generated using normalized multivariate Gaussian test statistics from authorized network devices. Authorized device classification and ID verification were assessed using pre-classification Kolmogorov-Smirnov (KS) feature ranking and post-classification generalized relevance learning vector quantization improved (GRLVQI) relevance ranking. A true verification rate greater than 90% and a false verification rate less than 10% were obtained when assessing authorized device IDs. When additional rogue devices were introduced that attempted to gain unauthorized network access by spoofing the bit-level credentials of authorized devices, the KS-test feature set achieved a true verification rate greater than 90% and a rogue reject rate greater than 90% in 29 of 36 rogue scenarios while the GRLVQI feature set was successful in 28 of 36 scenarios. Abstract © Springe