Radical remodeling of the Y chromosome in a recent radiation of malaria mosquitoes

Y chromosomes control essential male functions in many species, including sex determination and fertility. However, because of obstacles posed by repeat-rich heterochromatin, knowledge of Y chromosome sequences is limited to a handful of model organisms, constraining our understanding of Y biology across the tree of life. Here, we leverage long single-molecule sequencing to determine the content and structure of the nonrecombining Y chromosome of the primary African malaria mosquito, Anopheles gambiae. We find that the An. gambiae Y consists almost entirely of a few massively amplified, tandemly arrayed repeats, some of which can recombine with similar repeats on the X chromosome. Sex-specific genome resequencing in a recent species radiation, the An. gambiae complex, revealed rapid sequence turnover within An. gambiae and among species. Exploiting 52 sex-specific An. gambiae RNA-Seq datasets representing all developmental stages, we identified a small repertoire of Y-linked genes that lack X gametologs and are not Y-linked in any other species except An. gambiae, with the notable exception of YG2, a candidate male-determining gene. YG2 is the only gene conserved and exclusive to the Y in all species examined, yet sequence similarity to YG2 is not detectable in the genome of a more distant mosquito relative, suggesting rapid evolution of Y chromosome genes in this highly dynamic genus of malaria vectors. The extensive characterization of the An. gambiae Y provides a long-awaited foundation for studying male mosquito biology, and will inform novel mosquito control strategies based on the manipulation of Y chromosomes

Rapid evolution of female-biased genes among four species of Anopheles

Understanding how phenotypic differences between males and females arise from the sex-biased expression of nearly identical genomes can reveal important insights into the biology and evolution of a species. Among Anopheles mosquito species, these phenotypic differences include vectorial capacity, as it is only females that blood feed and thus transmit human malaria. Here, we use RNA-seq data from multiple tissues of four vector species spanning the Anopheles phylogeny to explore the genomic and evolutionary properties of sex-biased genes. We find that, in these mosquitoes, in contrast to what has been found in many other organisms, female-biased genes are more rapidly evolving in sequence, expression, and genic turnover than male-biased genes. Our results suggest that this atypical pattern may be due to the combination of sex-specific life history challenges encountered by females, such as blood feeding. Furthermore, female propensity to mate only once in nature in male swarms likely diminishes sexual selection of post-reproductive traits related to sperm competition among males. We also develop a comparative framework to systematically explore tissue- and sex-specific splicing to document its conservation throughout the genus and identify a set of candidate genes for future functional analyses of sex-specific isoform usage. Finally, our data reveal that the deficit of male-biased genes on the X Chromosomes in Anopheles is a conserved feature in this genus and can be directly attributed to chromosome-wide transcriptional regulation that de-masculinizes the X in male reproductive tissues

Radical remodeling of the Y chromosome in a recent radiation of malaria mosquitoes

Y chromosomes control essential male functions in many species, including sex determination and fertility. However, because of obstacles posed by repeat-rich heterochromatin, knowledge of Y chromosome sequences is limited to a handful of model organisms, constraining our understanding of Y biology across the tree of life. Here, we leverage long single-molecule sequencing to determine the content and structure of the nonrecombining Y chromosome of the primary African malaria mosquito, Anopheles gambiae. We find that the An. gambiae Y consists almost entirely of a few massively amplified, tandemly arrayed repeats, some of which can recombine with similar repeats on the X chromosome. Sex-specific genome resequencing in a recent species radiation, the An. gambiae complex, revealed rapid sequence turnover within An. gambiae and among species. Exploiting 52 sex-specific An. gambiae RNA-Seq datasets representing all developmental stages, we identified a small repertoire of Y-linked genes that lack X gametologs and are not Y-linked in any other species except An. gambiae, with the notable exception of YG2, a candidate male-determining gene. YG2 is the only gene conserved and exclusive to the Y in all species examined, yet sequence similarity to YG2 is not detectable in the genome of a more distant mosquito relative, suggesting rapid evolution of Y chromosome genes in this highly dynamic genus of malaria vectors. The extensive characterization of the An. gambiae Y provides a long-awaited foundation for studying male mosquito biology, and will inform novel mosquito control strategies based on the manipulation of Y chromosomes

Embrace experimentation in biosecurity governance.

We must rethink and test assumptions about relationships among biological research, security, and societ

Brivaracetam as add-on treatment in patients with post-stroke epilepsy: real-world data from the BRIVAracetam add-on First Italian netwoRk Study (BRIVAFIRST)

Objective: Post-stroke epilepsy (PSE) is one of the most common causes of acquired epilepsy and accounts for about 10-15% of all newly diagnosed epilepsy cases. However, evidence about the clinical profile of antiseizure medications in the PSE setting is currently limited. Brivaracetam (BRV) is a rationally developed compound characterized by high-affinity binding to synaptic vesicle protein 2A. The aim of this study was to assess the 12-month effectiveness and tolerability of adjunctive BRV in patients with PSE treated in a real-world setting. Methods: This was a subgroup analysis of patients with PSE included in the BRIVAracetam add-on First Italian netwoRk Study (BRIVAFIRST). The BRIVAFIRST was a 12-month retrospective, multicentre study including adult patients prescribed adjunctive BRV. Effectiveness outcomes included the rates of seizure response (≥50% reduction in baseline seizure frequency), seizure-freedom, and treatment discontinuation. Safety and tolerability outcomes included the rate of treatment discontinuation due to adverse events (AEs) and the incidence of AEs. Results: Patients with PSE included in the BRIVAFIRST were 75 and had a median age of 57 (interquartile range, 42-66) years. The median daily doses of BRV at 3, 6, and 12 months from starting treatment were 100 (100-150) mg, 125 (100-200) mg and 100 (100-200) mg, respectively. At 12 months, 32 (42.7%) patients had a reduction in their baseline seizure frequency by at least 50%, and the seizure freedom rates was 26/75 (34.7%). During the 1-year study period, 10 (13.3%) patients discontinued BRV. The reasons of treatment withdrawal were insufficient efficacy in 6 (8.0%) patients and poor tolerability in 4 (5.3%) patients. Adverse events were reported by 13 (20.3%) patients and were rated as mild in 84.6% and moderate in 15.4% of cases. Significance: Adjunctive BRV was efficacious and generally well-tolerated when used in patients with PSE in clinical practice. Adjunctive BRV can be a suitable therapeutic option for patients with PSE

Adjunctive Brivaracetam in Older Patients with Focal Seizures: Evidence from the BRIVAracetam add‑on First Italian netwoRk Study (BRIVAFIRST)

BACKGROUND: The management of epilepsy in older adults has become part of daily practice because of an aging population. Older patients with epilepsy represent a distinct and more vulnerable clinical group as compared with younger patients, and they are generally under-represented in randomized placebo-controlled trials. Real-world studies can therefore be a useful complement to characterize the drug's profile. Brivaracetam is a rationally developed compound characterized by high-affinity binding to synaptic vesicle protein 2A and approved as adjunctive therapy for focal seizures in adults with epilepsy. OBJECTIVE: The aim of this study was to assess the 12-month effectiveness and tolerability of adjunctive brivaracetam in older patients (≥65 years of age) with epilepsy treated in a real-world setting. METHODS: The BRIVAFIRST (BRIVAracetam add-on First Italian netwoRk STudy) was a 12-month retrospective multicenter study including adult patients prescribed adjunctive brivaracetam. Effectiveness outcomes included the rates of seizure response (≥50% reduction in baseline seizure frequency), seizure freedom, and treatment discontinuation. Safety and tolerability outcomes included the rate of treatment discontinuation due to adverse events and the incidence of adverse events. Data were compared for patients aged ≥65 years of age ('older') vs those aged <65 years ('younger'). RESULTS: There were 1029 patients with focal epilepsy included in the study, of whom 111 (10.8%) were aged ≥65 years. The median daily dose of brivaracetam at 3 months was 100 [interquartile range, 100-175] mg in the older group and 100 [100-200] mg in the younger group (p = 0.036); it was 150 [100-200] mg in both groups either at 6 months (p = 0.095) or 12 months (p = 0.140). At 12 months, 49 (44.1%) older and 334 (36.4%) younger patients had a reduction in their baseline seizure frequency by at least 50% (p = 0.110), and the seizure freedom rates were 35/111 (31.5%) and 134/918 (14.6%) in older and younger groups, respectively (p < 0.001). During the 1-year study period, 20 (18.0%) patients in the older group and 245 (26.7%) patients in the younger group discontinued brivaracetam (p = 0.048). Treatment withdrawal because of insufficient efficacy was less common in older than younger patients [older: n = 7 (6.3%), younger: n = 152 (16.6%); p = 0.005]. Adverse events were reported by 24.2% of older patients and 30.8% of younger patients (p = 0.185); the most common adverse events were somnolence, nervousness and/or agitation, vertigo, and fatigue in both study groups. CONCLUSIONS: Adjunctive brivaracetam was efficacious, had good tolerability, and no new or unexpected safety signals emerged when used to treat older patients with uncontrolled focal seizures in clinical practice. Adjunctive brivaracetam can be a suitable therapeutic option in this special population