Ripon College

Independent Component Analysis (ICA) is a blind-source separation method, meaning that it takes in a recording with multiple sensors and attempts to unmix it into the original sources. For example, suppose there are 4 people (sources) speaking in a room with 4 microphones (sensors), then ICA unmixes the recording from the 4 microphones to give tracks of the individual people called ICA components. ICA is currently used to decompose a variety of signals with many sensors, including fMRI and EEG data. However, its use in interpreting data with fewer sensors, such as the local field potential (LFP), is limited because of concerns about how it handles over-complete data (data with more sources than sensors). While there has been some success in enhancing ICA so that it can extract more sources than sensors, we focus on how ICA handles over-complete data. In this paper, we show that ICA consistently bins sources with similar spatial maps together when there are 3 sinusoidal sources and 2 sensors.

The analysis of mixtures of amino acid stereoisomersis a classicchallenge in bioorganic chemistry and organic synthesis. Chemicalderivatization with Marfey’s reagent, 1-fluoro-2,4-dinitrophenyl-5-l-alanine amide, is frequently employed as chromatographic separationof the resulting diastereomers enables convenient assignment of d/l-configuration and determination of enantiomericratio. However, it is often challenging to resolve Cβ-epimericdiastereomers of noncanonical amino acids after treating with Marfey’sreagent. This report describes the effectiveness of alternative chiralderivatization reagents. We demonstrate that the Cβ epimersof l-phenylserine and other β-hydroxy noncanonical l-amino acids are more easily separated when the traditionalMarfey’s reagent is substituted by a proline analogue or the d-enantiomers of several other Marfey’s reagents. Additionally,in many cases achiral Sanger’s reagent, 1-fluoro-2,4-dinitrobenzene,was found to produce the largest separation of β-diastereomers.The “mixed Marfey’s reaction” protocol is established,which allows for screening multiple Marfey’s reagents withina single reaction. This method was applied to the challenging caseof resolving the methyl–ethyl Cβ stereocenter of l-isoleucine (Ile), providing accurate quantification of mixturesof l-Ile and l-allo-Ile. This strategyis applicable to a range of noncanonical amino acids and suggeststhat commercially available d-Marfey’s analogues orachiral Sanger’s reagent will provide enhanced separation withoutsynthesis of more complex derivatizing agents.

Abstract Rotifers are aquatic micrometazoans with a variety of feeding styles and dietary preferences. The morphology of their digestive tracts is well known, but there are few details on the structure of any organs. Here we use transmission electron microscopy and fluorescence microscopy to investigate the stomach of Epiphanes clavulata, which is unusual in its possession of 6 diverticula that are absent in other taxa. We focus on this region to determine whether these diverticula are exocrine and potentially homologous to gastric glands, which are the main digestive organs of rotifers, but absent in this species. Results reveal that the stomach is cellular and that all cells are ciliated, nucleated, and contain abundant phagosomes and lipid droplets. The stomach appears to play 2 major roles: intracellular digestion as evidenced by the presence of caveolae and phagosomes and lipid biogenesis and storage as evidenced by accumulation of large lipid droplets. The 6 diverticula are syncytial extensions of individual stomach cells and contain 1 to several nuclei, many mitochondria, autophagic vesicles, ribosomes, and inclusion bodies. The rough endoplasmic reticulum is abundant and associated with small electron-dense droplets enclosed in a phospholipid monolayer, suggesting they contain lipids; however, the absence of discernable staining with a neutral lipid dye confounds a more specific identification of their contents. There is no evidence to suggest the diverticula are homologous to gastric glands nor do they play an obvious role in digestion; instead, they may function as a secondary site of lipid biogenesis and storage.

Enzymes are renowned for their catalytic efficiency and selectivity, but many classical transformations in organic synthesis have no biocatalytic counterpart. Aldolases are prodigious C-C bond-forming enzymes, but their reactivity has only been extended past activated carbonyl electrophiles in special cases. To probe the mechanistic origins of this limitation, we use a pair of aldolases whose activity is dependent on pyridoxal phosphate. Our results reveal how aldolases are limited by kinetically favourable proton transfer with solvent, which undermines aldol addition into ketones. We show how a transaldolase can circumvent this limitation, enabling efficient addition into unactivated ketones. The resulting products are highly sought non-canonical amino acids with side chains that contain chiral tertiary alcohols. Mechanistic analysis reveals that transaldolase activity is an intrinsic feature of pyridoxal phosphate chemistry and identifies principles for extending aldolase catalysis beyond its previous limits to enable convergent, enantioselective C-C bond formation from simple starting materials.

Anxiety disorders are more prevalent in females than males, in part due to the change in ovarian hormones during the late luteal phase of the menstrual cycle. Estradiol and progesterone (E+P) peak in the luteal phase before dropping rapidly in the late luteal phase. This drop is associated with increased anxiety, and E+P may decrease anxiety. It is important to find a way to counteract the negative symptoms associated with ovarian hormone changes. Omega-3 fatty acid supplementation has been found to decrease anxiety-like behavior in male rats, but the effects on anxiety-like behavior in females are unknown. To determine the effect of omegas and E+P on anxiety-like behavior in female rats, we observed two trials of the elevated plus maze (EPM) and light-dark box after omega-3 fatty acid and E+P treatments. There was a decrease in time spent and crosses in the open arm of the EPM and the light side of the light-dark box across trials and no effect of omega-3 fatty acids or E+P. Further research into the potential interaction of omega-3 fatty acids and E+P is needed.

Rotifers possess complex morphologies despite their microscopic size and simple appearance. Part of this complexity is hidden in the structure of their organs, which may be cellular or syncytial. Surprisingly, organs that are cellular in one taxon can be syncytial in another. Pedal glands are widespread across Rotifera and function in substrate attachment and/or egg brooding. These glands are normally absent in Asplanchna, which lack feet and toes that function as outlets for pedal glandular secretions in other rotifers. Here, we describe the ultrastructure of a pedal gland that is singular and syncytial in Asplanchna aff. herricki, but is normally paired and cellular in all other rotifers. Asplanchna aff. herricki has a single large pedal gland that is active and secretory; it has a bipartite, binucleate, syncytial body and a cytosol filled with rough endoplasmic reticulum, Golgi, and several types of secretory vesicles. The most abundant vesicle type is large and contains a spherical electron-dense secretion that appears to be produced through homotypic fusion of condensing vesicles produced by the Golgi. The vesicles appear to undergo a phase transition from condensed to decondensed along their pathway toward the gland lumen. Decondensation changes the contents to a mucin-like matrix that is eventually exocytosed in a "kiss-and-run" fashion with the plasma membrane of the gland lumen. Exocytosed mucus enters the gland lumen and exits through an epithelial duct that is an extension of the syncytial integument. This results in mucus that extends from the rotifer as a long string as the animal swims through the water. The function of this mucus is unknown, but we speculate it may function in temporary attachment, prey capture, or floatation.

ABSTRACT Genus Pompholyx Gosse, 1851 (Rotifera; Monogononta; Testudinellidae) comprises three species described from freshwater plankton around the globe. Here we describe a new species of Pompholyx collected from a freshwater pond in Massachusetts, USA. The new species resembles its congeners with respect to the following characters: paired eyespots; a dorsally arched lorica with a dorsal occipital convexity behind the corona; lateral flared and rounded lorica surfaces; a ventral surface bearing an occipital concavity posterior of the mouth; a unique egg-gland system; and the absence of a foot. However, P. faciemlarva sp. n. differs from its congeners in possessing a transverse furrow on both the dorsal and ventral surfaces of the lorica. While the trophi of P. faciemlarva sp. n. generally resemble those of other species of Testudinellidae, they do have a symmetrical pattern of unci teeth (17/17) that differs from Pompholyx sulcata (17–20/18–21, right/left), the only other species in the genus with well-described trophi. The description of this new species enhances the floristic richness of freshwater in North America. http://www.zoobank.org/urn:lsid:zoobank.org:pub:C3C18F25-673E-45E4-BFD6-0D17B694E02B

All species of Flosculariidae (Rotifera; Monogononta; Gnesiotrocha; Flosculariaceae) possess a flexible integument; they are termed illoricate. But species of four genera (Beauchampia, Floscularia, Limnias, and Ptygura) possess a distinctive hardened region on the dorsal side of their anterior end, which unfortunately has received little attention beyond the species level. In our work we study the ultrastructure of these hardened regions. In Beauchampia, Limnias, and some species of Ptygura the hardened zone takes the form of a dorsal plate (hereafter DP) with or without additional protruding processes. The DP has the shape of a ~50 µm diameter disc enfolding the anterior dorsal region of the animal, with a perimetral inward fold, smooth surface, and pores. The DP of Limnias ceratophylli shows three main ultrastructural differences from the rest of the body: (1) type of glycocalyx, (2) absence of small mounds on its surface, and (3) presence of broad cisternae at the base of the pores. In Floscularia and some Ptygura the hardened structures are reduced to a pair of dorsal projections protecting the dorsal antenna: i.e., lacking a full DP. These structures deserve attention because their adaptive importance has not been studied. Here we augment those observations with other characters: i.e., presence/absence of a birefringent body in late-stage embryos and morphology of their trophi and corona. Our goal was to provide information to help develop better taxonomy, as well as advance our understanding of the evolution of sessile taxa in general and of the potentially polyphyletic Ptygura genus in particular.

The demand for computing talent is at an all-time high, but not everyone feels equally welcome or has equal access to pursue opportunities in technology fields. Women, non-binary, Black, Hispanic/Latino/a/x, and first-generation students are the least likely to have access to paid undergraduate internships that lead to job opportunities in technology companies. This experience report discusses two programs designed to address the lack of internships among historically excluded populations: a microinternship program and a career program. We present data showing the role that each program played in creating professional pathways for racially diverse undergraduate women and non-binary students. Both programs prepare these undergraduates for professional environments by exposing them to tech careers and developing their social capital through professional networking. Quantitative and qualitative data were collected as well as summer employment plans to evaluate the effectiveness of the program. We present the short-and longterm impact of each program on students' career interests and sense of belonging in computing. A summary of lessons learned from implementing each program are also shared for stakeholders interested in designing similar programs.