Single cell RNA sequencing uncovers cellular developmental sequences and novel potential intercellular communications in embryonic kidney

Kidney development requires the coordinated growth and differentiation of multiple cells. Despite recent single cell profiles in nephrogenesis research, tools for data analysis are rapidly developing, and offer an opportunity to gain additional insight into kidney development. In this study, single-cell RNA sequencing data obtained from embryonic mouse kidney were re-analyzed. Manifold learning based on partition-based graph-abstraction coordinated cells, reflecting their expected lineage relationships. Consequently, the coordination in combination with ForceAtlas2 enabled the inference of parietal epithelial cells of Bowman’s capsule and the inference of cells involved in the developmental process from the S-shaped body to each nephron segment. RNA velocity suggested developmental sequences of proximal tubules and podocytes. In combination with a Markov chain algorithm, RNA velocity suggested the self-renewal processes of nephron progenitors. NicheNet analyses suggested that not only cells belonging to ureteric bud and stroma, but also endothelial cells, macrophages, and pericytes may contribute to the differentiation of cells from nephron progenitors. Organ culture of embryonic mouse kidney demonstrated that nerve growth factor, one of the nephrogenesis-related factors inferred by NicheNet, contributed to mitochondrial biogenesis in developing distal tubules. These approaches suggested previously unrecognized aspects of the underlying mechanisms for kidney development.

Validation of a Backswing Developmental Sequence for the Overarm Throw for Force

Background: Roberton’s movement components are used to assess fundamental motor skills as segmental developmental sequences. In 1991, Haywood, Williams and VanSant determined that original developmental sequences proposed for the backswing levels of the overarm throw did not encompass all ages. Their study of older throwers identified two new qualitatively different levels, with half the participants categorized at two new levels. This investigation extended the initial validation across a wider age range. Method: Two hundred and twenty-eight primary, high school, university students, and adults were instructed to make five throws for maximum force using their dominant hand. Throws were recorded with side and rear cameras synchronized for analysis. Prelongitudinal screening was used to analyze the Haywood et al. revisions of the Langendorfer developmental sequence. Results: Five of the six levels of Haywood’s sequence were suitable for assessing throwers 8 years of age through to adulthood. More study is needed of one less advanced pattern. Lower level throws corresponded to lower velocities; higher level throws were faster, suggesting the sequence was properly ordered. More males than females were classified at higher levels, demonstrating typical gender differences. Discussion: The categories hypothesized for the backswing action of the overarm throw were valid descriptors of differences observed across ages, from childhood to adulthood. Additional study of Levels 3 and 4 is warranted to clarify their order.

Developmental sequences for observing and assessing forceful kicking

While football/soccer is the most influential sport in the world, it is surprising that developmental sequences of forceful kicking have not been adequately described and validated in the literature. The purpose of this study was to explore potential developmental sequences for forceful kicking using a prelongitudinal screening method. Data were derived from videotapes of 255 children (girls n = 138, boys: n = 117), ages 4–11 years. Seven potential component sequences in their respective developmental order were initially proposed based on biomechanical and motor developmental principles. Each participant was digitally videoed performing five kicks with maximal effort. Trained research staff coded the initial seven components for each kick and the mode of each participant’s five kicks was used for data analysis. Component level probability curves for each component sequence across age were evaluated using the threshold based generalized partial credit model (Muraki, 1992) within the item response theory framework. As developmental theory would indicate, component levels generally increased with age for most components. Six component ordinal sequence progressions met model requirements (Rel = 0.88, item fit; p > 0.05). Ordinal levels for two components ( Knee action and Follow-through) were altered based on initial empirical model structure fit and the Ball contact component was removed based on a lack of model fit. This study provides sufficient cross-sectional evidence for six component developmental sequences that adequately describe the development of kicking using cross-sectional data. Longitudinal data are required to provide further developmental validation for these sequences.

A processability approach to the development of case in L2 Icelandic

This article presents the findings of a study on the development of case assignment in Icelandic as a second language within the context of Processability Theory (PT) and compares them with previous PT studies on the development of case in L2 German, Russian, and Serbian. We argue that initially, learners are only able to appropriately mark subjects and objects in canonical positions (e.g., subjnom v objacc ). Later they are also able to mark arguments with the appropriate case in sentences that deviate from canonical word order (e.g., objacc/dat v subjnom ). In order to examine the case development in L2 Icelandic, 148 learners were asked to fill in the blanks of sentences with missing core arguments. Our results replicate for the most part the previous findings for L2 German, Russian, and Serbian. As such, the present study adds to the typological plausibility of PT as a framework that predicts and explains developmental sequences.