Sexual reproduction allows transposable elements (TEs) to proliferate, leading to rapid divergence between populations and species. A significant outcome of divergence in the TE landscape is evident in hybrid dysgenic syndromes, a strong form of genomic incompatibility that can arise when (TE) family abundance differs between two parents. When TEs inherited from the father are absent in the mother's genome, TEs can become activated in the progeny, causing germline damage and sterility. Studies in Drosophila indicate that dysgenesis can occur when TEs inherited paternally are not matched with a pool of corresponding TE silencing PIWI-interacting RNAs (piRNAs) provisioned by the female germline. Using the D. virilis syndrome of hybrid dysgenesis as a model, we characterize the effects that divergence in TE profile between parents has on offspring. Overall, we show that divergence in the TE landscape is associated with persisting differences in germline TE expression when comparing genetically identical females of reciprocal crosses and these differences are transmitted to the next generation. Moreover, chronic and persisting TE expression coincides with increased levels of genic piRNAs associated with reduced gene expression. Combined with these effects, we further demonstrate that gene expression is idiosyncratically influenced by differences in the genic piRNA profile of the parents that arise though polymorphic TE insertions. Overall, these results support a model in which early germline events in dysgenesis establish a chronic, stable state of both TE and gene expression in the germline that is maintained through adulthood and transmitted to the next generation. This work demonstrates that divergence in the TE profile is associated with diverse piRNA-mediated transgenerational effects on gene expression within populations.

Throughout animals, embryonic cells must ultimately organize into polarized epithelial layers that provide the structural basis for gastrulation or subsequent developmental events [1]. Precisely how this primary epithelium maintains continuous integrity during rapid and repeated cell divisions has never been directly addressed, particularly in cases where early cleavages are driven in synchrony. Representing the early-branching non-bilaterian phylum Cnidaria, embryos of the sea anemone Nematostella vectensis undergo rapid synchronous cell divisions and ultimately give rise to a diploblastic epithelial body plan after gastrulation [2, 3]. Here, using live imaging of apical polarity proteins in Nematostella embryos, we demonstrate that cell polarity is established by the four-cell stage and then reiteratively lost during subsequent mitoses, correlating with transient adhesion disengagement and dramatic deformations of embryonic morphology. Intriguingly, the re-establishment of polarity and adhesion during each interphase is associated with a process of whole-embryo compaction analogous to that observed in mammals [4-7]. Because similar protein dynamics are observed in dividing epithelial cells in Drosophila melanogaster, we propose that cell-cycle-coupled oscillations in apical polarity may be conserved throughout Metazoa.

While dietary triggers have been investigated in acne and other inflammatory follicular dermatoses, there is a paucity of data on diet and hidradenitis suppurativa (HS). We sought to identify exacerbating and alleviating foods in HS patients. An anonymous survey was distributed via HS Facebook support groups and in person at HS specialty clinics. Participants were asked to select all that apply from a list to indicate

was difficult in the present case; melanotrichoblastoma with seborrheic keratosis was finally diagnosed on the basis of the pathological findings. Although pathological findings are the gold standard for the diagnosis of melanotrichoblastoma, we believe that dermoscopic features might help in the diagnosis of melanotrichoblastoma even in cases of coexistence with seborrheic keratosis.

No abstract