Exploring chromosome evolution in 250 million year old groups of dragonflies and damselflies (Insecta:Odonata).

Using recently published chromosome-length genome assemblies of two damselfly species, Ischnura elegans and Platycnemis pennipes, and two dragonfly species, Pantala flavescens and Tanypteryx hageni, we demonstrate that the autosomes of Odonata have undergone few fission, fusion, or inversion events, despite 250 million years of separation. In the four genomes discussed here, our results show that all autosomes have a clear ortholog in the ancestral karyotype. Despite this clear chromosomal orthology, we demonstrate that different factors, including concentration of repeat dynamics, GC content, relative position on the chromosome, and the relative proportion of coding sequence all influence the density of syntenic blocks across chromosomes. However, these factors do not interact to influence synteny the same way in any two pairs of species, nor is any one factor retained in all four species. Furthermore, it was previously unknown whether the micro-chromosomes in Odonata are descended from one ancestral chromosome. Despite structural rearrangements, our evidence suggests that the micro-chromosomes in the sampled Odonata do indeed descend from an ancestral chromosome, and that the micro-chromosome in P. flavescens was lost through fusion with autosomes.

An integrative phylogenomic approach illuminates the evolutionary history of cockroaches and termites (Blattodea).

Phylogenetic relationships among subgroups of cockroaches and termites are still matters of debate. Their divergence times and major phenotypic transitions during evolution are also not yet settled. We addressed these points by combining the first nuclear phylogenomic study of termites and cockroaches with a thorough approach to divergence time analysis, identification of endosymbionts, and reconstruction of ancestral morphological traits and behaviour. Analyses of the phylogenetic relationships within Blattodea robustly confirm previously uncertain hypotheses such as the sister-group relationship between Blaberoidea and remaining Blattodea, and Lamproblatta being the closest relative to the social and wood-feeding Cryptocercus and termites. Consequently, we propose new names for various clades in Blattodea: Cryptocercus + termites = Tutricablattae; Lamproblattidae + Tutricablattae = Kittrickea; and Blattoidea + Corydioidea = Solumblattodea. Our inferred divergence times contradict previous studies by showing that most subgroups of Blattodea evolved in the Cretaceous, reducing the gap between molecular estimates of divergence times and the fossil record. On a phenotypic level, the blattodean ground-plan is for egg packages to be laid directly in a hole while other forms of oviposition, including ovovivipary and vivipary, arose later. Finally, other changes in egg care strategy may have allowed for the adaptation of nest building and other novelties.

Extremely low genetic diversity in a circumpolar dragonfly species, Somatochlora sahlbergi (Insecta: Odonata: Anisoptera).

We present the first empirical treatment of the northernmost breeding dragonfly, Somatochlora sahlbergi. We sequenced populations from United States, Canada, Finland, Sweden and Norway for cytochrome oxidase I (COI) and D2 region of 28s. We found that, despite geographic barriers across its vast arctic range, S. sahlbergi is a single species. Not only does it appear to interbreed across its entire range, there also seems to be almost no variation among European and North American populations in their COI gene fragment (the barcode gene), which is usually extremely variable. We further found that characters thought to be diagnostic for the larvae of S. sahlbergi were absent in our European samples. We review and re-describe the habitat of this species based on new findings from recent field observations. Finally, we report for the first time the likely presence of this species in Japan. We hope our findings will encourage further study of this species and other under-studied insect taxa that inhabit the remote Arctic.

Radial Scar at Percutaneous Breast Biopsy That Does Not Require Surgery.

BACKGROUND: Surgical excision is currently recommended after pathologic radial scar is found on breast core needle biopsy because surgical upgrade to carcinoma is not uncommon. The goal of our study was to identify the true pathologic upgrade rate for a "pure" radial scar, those without associated proliferative lesion, based on indication for biopsy, biopsy type, and needle size. STUDY DESIGN: The pathology database of Continuum Health Partners was searched for the terms radial scar and radial sclerosing lesion, from January 2007 to December 2015. From review of 1,513 pathology reports, 292 cases of core biopsies without malignancy were identified. Age, indication for biopsy, type of biopsy, and excisional pathology were obtained. Data were then analyzed using SPSS. RESULTS: Two hundred nineteen (75%) of the 292 core biopsies showed pure radial scar without associated proliferative lesion, and 161 (74%) of these patients had surgical excision. Only 1 of these patients had disease that was upgraded to ductal carcinoma in situ-a 2-mm focus located 5 mm away from the radial scar biopsy cavity. This patient also had residual calcifications on mammography after the stereotactic biopsy. Six additional malignant upgrades were found in patients who had radial scar associated with atypical ductal hyperplasia (n = 5) or lobular neoplasia (n = 1) on needle biopsy. CONCLUSIONS: Surgical excision is unnecessary when radial scar is found at percutaneous needle biopsy without an associated proliferative lesion. Surgical excision is still indicated when radial scar is associated with atypical ductal hyperplasia or lobular neoplasia.