A chromosome-level genome for the nudibranch gastropod Berghia stephanieae helps parse clade-specific gene expression in novel and conserved phenotypes

BACKGROUND

How novel phenotypes originate from conserved genes, processes, and tissues remains a major question in biology. Research that sets out to answer this question often focuses on the conserved genes and processes involved, an approach that explicitly excludes the impact of genetic elements that may be classified as clade-specific, even though many of these genes are known to be important for many novel, or clade-restricted, phenotypes. This is especially true for understudied phyla such as mollusks, where limited genomic and functional biology resources for members of this phylum have long hindered assessments of genetic homology and function. To address this gap, we constructed a chromosome-level genome for the gastropod Berghia stephanieae (Valdés, 2005) to investigate the expression of clade-specific genes across both novel and conserved tissue types in this species.

RESULTS

The final assembled and filtered Berghia genome is comparable to other high-quality mollusk genomes in terms of size (1.05 Gb) and number of predicted genes (24,960 genes) and is highly contiguous. The proportion of upregulated, clade-specific genes varied across tissues, but with no clear trend between the proportion of clade-specific genes and the novelty of the tissue. However, more complex tissue like the brain had the highest total number of upregulated, clade-specific genes, though the ratio of upregulated clade-specific genes to the total number of upregulated genes was low.

CONCLUSIONS

Our results, when combined with previous research on the impact of novel genes on phenotypic evolution, highlight the fact that the complexity of the novel tissue or behavior, the type of novelty, and the developmental timing of evolutionary modifications will all influence how novel and conserved genes interact to generate diversity.

A chromosome-level genome for the nudibranch gastropod Berghia stephanieae helps parse clade-specific gene expression in novel and conserved phenotypes

How novel phenotypes originate from conserved genes, processes, and tissues remains a major question in biology. Research that sets out to answer this question often focuses on the conserved genes and processes involved, an approach that explicitly excludes the impact of genetic elements that may be classified as clade-specific, even though many of these genes are known to be important for many novel, or clade-restricted, phenotypes. This is especially true for understudied phyla such as mollusks, where limited genomic and functional biology resources for members of this phylum has long hindered assessments of genetic homology and function. To address this gap, we constructed a chromosome-level genome for the gastropod Berghia stephanieae (Valdés, 2005) to investigate the expression of clade-specific genes across both novel and conserved tissue types in this species. The final assembled and filtered Berghia genome is comparable to other high quality mollusk genomes in terms of size (1.05 Gb) and number of predicted genes (24,960 genes), and is highly contiguous. The proportion of upregulated, clade-specific genes varied across tissues, but with no clear trend between the proportion of clade-specific genes and the novelty of the tissue. However, more complex tissue like the brain had the highest total number of upregulated, clade-specific genes, though the ratio of upregulated clade-specific genes to the total number of upregulated genes was low. Our results, when combined with previous research on the impact of novel genes on phenotypic evolution, highlight the fact that the complexity of the novel tissue or behavior, the type of novelty, and the developmental timing of evolutionary modifications will all influence how novel and conserved genes interact to generate diversity.

Abnormal coagulation studies associated with levofloxacin. Report of three cases

Complications arising from antibiotic use are of interest to neurosurgeons because many neurosurgical patients are treated for infection. In this report, the authors describe three patients with spine disorders who developed coagulopathies after treatment with levofloxacin, an antibiotic commonly used by neurosurgical services. Three patients with spine disorders developed urinary tract infections (UTIs) for which they received a 3-day course of oral levofloxacin. Subsequently, they demonstrated prolonged prothrombin times and increased international normalized ratios. One of those patients later developed acquired von Willebrand syndrome during surgery. Coagulopathies were successfully corrected preoperatively with parenteral vitamin K. The patient with acquired von Willebrand syndrome required multiple transfusions. There seems to be an association between levofloxacin and coagulation abnormalities in neurosurgical patients treated for UTIs. Neurosurgical services prescribing this common antibiotic should be aware of this problem.

Remote vascular catastrophes after neurovascular interventional therapy for type 4 Ehlers-Danlos Syndrome

Type 4 Ehlers-Danlos Syndrome (EDS 4) is the most malignant form of Ehlers-Danlos Syndrome, often accompanied by neurovasacular complications secondary to vessel dissection or aneurysms. The fragile nature of connective tissue in these patients makes exovascular and endovascular treatment hazardous. We have treated four patients with EDS 4 over the last 8 years by using neuroendovascular procedures. Two of these individuals suffered remote vascular injuries around the time of their procedures and ultimately died. The circumstances surrounding their deaths will make up the body of this report.