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Morphometric study of Middle Pleistocene arvalis-like voles from the localities Ozerne 2, Morozivka 2 (Odesa Oblast), and Medzhybizh 1 (Khmelnitsky Oblast) confirms the close phylogenetic relations between Microtus nivaloides and M. agrestis. The time of the first appearance of M. agrestis was different in Central and Eastern Europe, Western Europe, and the Northern Black Sea region. The replacement of M. nivaloides with M. agrestis corresponds to phyletic speciation with different rates of the process within different parts of the (future) species range. Appearance of M. agrestis in Central Europe (Kozi Grzbiet) precedes the appearance of this species in Western Europe. Later, at the beginning of the Zavadivka stage, the species appears in the northern part of Eastern Europe. Then, in the second part of the Zavadivka stage of the Middle Pleistocene, the transition occurs in Ukraine (the Middle Southern Bug area). It is possible that the process of the replacement of M. nivaloides with M. agrestis in the south, in the Northern Black Sea region, was even more impeded. The Azov region was beyond the area of this transition, although it was the part of the range of M. nivaloides. An important factor that slowed down the emergence of M. agrestis in the south of Ukraine could be the positive correlation between body size and increasing water demand of M. agrestis with the increase of temperature. Here, in the southern periphery of the species range, a small form of M. agrestis existed during dry climatic stages. Some specimens of M. agrestis from Medzhybizh 1 were below the low limit of size variation of any recent population of the species. Further expansion to the south and to the east, towards more arid climatic conditions, could have led to further decrease in size in order to optimise water metabolism, which would conflict with other demands, such as competitive success and thermoregulation, and, respectively, could become non-adaptive. Fossil samples with morphology intermediate between M. nivaloides and M. agrestis (Morozivka 2) show that the processes of phyletic evolution rather than expansion is the most probable scenario of the appearance of M. agrestis in the territory of Ukraine.

We present a case of a 17-year-old male with recurrent hair twirling resulting in patchy alopecia, who improved dramatically on N-acetylcysteine (NAC). Trichotillomania is characterized by repetitive hair pulling, twisting, or twirling and can vary from a mild habit to an impulse-control disorder. Standard treatment for pediatric trichotillomania includes cognitive behavioral therapy or medical therapy with selective serotonin reuptake inhibitors. NAC is a more recently utilized, safe, and well-tolerated over-the-counter supplement with some evidence of benefit for habitual skin and hair disorders. For this patient, we recommended 600 mg twice daily, increasing to 1200 mg twice daily as tolerated. After 6 months, our patient reported decreased desire to twirl his hair and his hair had almost completely regrown. Pediatricians who see patients with trichotillomania or other habitual disorders can consider treating these patients with NAC given its potential benefits and favorable side effect profile.

Cone photoreceptors in teleost fish are organized in precise, crystalline arrays in the epithelial plane of the retina. In zebrafish, four distinct morphological/spectral cone types occupy specific, invariant positions within a regular lattice. The cone lattice is aligned orthogonal and parallel to circumference of the retinal hemisphere: it emerges as cones generated in a germinal zone at the retinal periphery are incorporated as single-cell columns into the cone lattice. Genetic disruption of the transcription factor Tbx2b eliminates most of the cone subtype maximally sensitive to ultraviolet (UV) wavelengths and also perturbs the long-range organization of the cone lattice. In the tbx2b mutant, the other three cone types (red, green, and blue cones) are specified in the correct proportion, differentiate normally, and acquire normal, planar polarized adhesive interactions mediated by Crumbs 2a and Crumbs 2b. Quantitative image analysis of cell adjacency revealed that the cones in the tbx2b mutant primarily have two nearest neighbors and align in single-cell-wide column fragments that are separated by rod photoreceptors. Some UV cones differentiate at the dorsal retinal margin in the tbx2b mutant, although they are severely dysmorphic and are eventually eliminated. Incorporating loss of UV cones during formation of cone columns at the margin into our previously published mathematical model of zebrafish cone mosaic formation (which uses bidirectional interactions between planar cell polarity proteins and anisotropic mechanical stresses in the plane of the retinal epithelium to generate regular columns of cones parallel to the margin) reproduces many features of the pattern disruptions seen in the tbx2b mutant.