Transnational Dialogues in Afro-Latin American and Afro-Latinx Studies

"Throughout the Americas, a range of societal shifts have advanced the need for a more transnational framework for studying the hemisphere, particularly the population of African descent in Latin America and its diasporic communities. Notably, contemporary Latin America has witnessed an expansion of social movements and policies addressing race, gender, and citizenship. In the U.S., the Midwest has experienced a dramatic increase in Spanish-Caribbean populations – from 33 percent in Pennsylvania to 229 percent in Ohio (Pew Research Center, 2008). Building on the momentum of the Afro-Latin American and Afro-Latinx Studies Initiative (ALALS), funded by a Pitt Seed Project grant in 2018, Transnational Dialogues seeks to expand transnational, transregional, and interdisciplinary research, education, and programming at the core of the ALALS initiative. In addition, established relationships with scholars in the departments of History, Hispanic Languages and Literatures, Administrative and Policy Studies in Education, the Center for Latin American Studies, and Hillman Library, make this a highly collaborative endeavor. Transnational Dialogues addresses all areas of the Plan for Pitt. Seven interrelated programs highlight the four key arenas: personalized and experiential education, curriculum development, professional development, and multidisciplinary collaboration and public engagement. The programs include a major conference, curriculum workshop, working group, and a professional development seminar abroad. These activities center scholarly exchange to foster research, educational excellence, foundational strength, and diversity. The experiential learning and personalized education programs include certificate concentrations, undergraduate summer research, and semester-long internships. Such opportunities promote academic engagement, diversity, inclusion, and global involvement. The overarching project positions the Dietrich School, the School of Education, the University Center for International Studies, and University Library System to engage in broad-scale and global research alliances that advance the mission of the University of Pittsburgh.

Basal Body Positioning Is Controlled by Flagellum Formation in Trypanosoma brucei

To perform their multiple functions, cilia and flagella are precisely positioned at the cell surface by mechanisms that remain poorly understood. The protist Trypanosoma brucei possesses a single flagellum that adheres to the cell body where a specific cytoskeletal structure is localised, the flagellum attachment zone (FAZ). Trypanosomes build a new flagellum whose distal tip is connected to the side of the old flagellum by a discrete structure, the flagella connector. During this process, the basal body of the new flagellum migrates towards the posterior end of the cell. We show that separate inhibition of flagellum assembly, base-to-tip motility or flagella connection leads to reduced basal body migration, demonstrating that the flagellum contributes to its own positioning. We propose a model where pressure applied by movements of the growing new flagellum on the flagella connector leads to a reacting force that in turn contributes to migration of the basal body at the proximal end of the flagellum

A Quantitative 3D Motility Analysis of Trypanosoma brucei by Use of Digital In-line Holographic Microscopy

We present a quantitative 3D analysis of the motility of the blood parasite Trypanosoma brucei. Digital in-line holographic microscopy has been used to track single cells with high temporal and spatial accuracy to obtain quantitative data on their behavior. Comparing bloodstream form and insect form trypanosomes as well as mutant and wildtype cells under varying external conditions we were able to derive a general two-state-run-and-tumble-model for trypanosome motility. Differences in the motility of distinct strains indicate that adaption of the trypanosomes to their natural environments involves a change in their mode of swimming

Giardia Flagellar Motility Is Not Directly Required to Maintain Attachment to Surfaces

Giardia trophozoites attach to the intestinal microvilli (or inert surfaces) using an undefined “suction-based” mechanism, and remain attached during cell division to avoid peristalsis. Flagellar motility is a key factor in Giardia's pathogenesis and colonization of the host small intestine. Specifically, the beating of the ventral flagella, one of four pairs of motile flagella, has been proposed to generate a hydrodynamic force that results in suction-based attachment via the adjacent ventral disc. We aimed to test this prevailing “hydrodynamic model” of attachment mediated by flagellar motility. We defined four distinct stages of attachment by assessing surface contacts of the trophozoite with the substrate during attachment using TIRF microscopy (TIRFM). The lateral crest of the ventral disc forms a continuous perimeter seal with the substrate, a cytological indication that trophozoites are fully attached. Using trophozoites with two types of molecularly engineered defects in flagellar beating, we determined that neither ventral flagellar beating, nor any flagellar beating, is necessary for the maintenance of attachment. Following a morpholino-based knockdown of PF16, a central pair protein, both the beating and morphology of flagella were defective, but trophozoites could still initiate proper surface contacts as seen using TIRFM and could maintain attachment in several biophysical assays. Trophozoites with impaired motility were able to attach as well as motile cells. We also generated a strain with defects in the ventral flagellar waveform by overexpressing a dominant negative form of alpha2-annexin::GFP (D122A, D275A). This dominant negative alpha2-annexin strain could initiate attachment and had only a slight decrease in the ability to withstand normal and shear forces. The time needed for attachment did increase in trophozoites with overall defective flagellar beating, however. Thus while not directly required for attachment, flagellar motility is important for positioning and orienting trophozoites prior to attachment. Drugs affecting flagellar motility may result in lower levels of attachment by indirectly limiting the number of parasites that can position the ventral disc properly against a surface and against peristaltic flow

The hydrocephalus inducing gene product, Hydin, positions axonemal central pair microtubules

<p>Abstract</p> <p>Background</p> <p>Impairment of cilia and flagella function underlies a growing number of human genetic diseases. Mutations in <it>hydin </it>in <it>hy3 </it>mice cause lethal communicating hydrocephalus with early onset. Hydin was recently identified as an axonemal protein; however, its function is as yet unknown.</p> <p>Results</p> <p>Here we use RNAi in <it>Trypanosoma brucei </it>to address this issue and demonstrate that loss of Hydin causes slow growth and a loss of cell motility. We show that two separate defects in newly-formed flagellar central pair microtubules underlie the loss of cell motility. At early time-points after RNAi induction, the central pair becomes mispositioned, while at later time points the central pair is lost. While the basal body is unaffected, both defects originate at the basal plate, reflecting a role for TbHydin throughout the length of the central pair.</p> <p>Conclusion</p> <p>Our data provide the first evidence of Hydin's role within the trypanosome axoneme, and reveal central pair anomalies and thus impairment of ependymal ciliary motility as the likely cause of the hydrocephalus observed in the <it>hy3 </it>mouse.</p

A MAP6-Related Protein Is Present in Protozoa and Is Involved in Flagellum Motility

In vertebrates the microtubule-associated proteins MAP6 and MAP6d1 stabilize cold-resistant microtubules. Cilia and flagella have cold-stable microtubules but MAP6 proteins have not been identified in these organelles. Here, we describe TbSAXO as the first MAP6-related protein to be identified in a protozoan, Trypanosoma brucei. Using a heterologous expression system, we show that TbSAXO is a microtubule stabilizing protein. Furthermore we identify the domains of the protein responsible for microtubule binding and stabilizing and show that they share homologies with the microtubule-stabilizing Mn domains of the MAP6 proteins. We demonstrate, in the flagellated parasite, that TbSAXO is an axonemal protein that plays a role in flagellum motility. Lastly we provide evidence that TbSAXO belongs to a group of MAP6-related proteins (SAXO proteins) present only in ciliated or flagellated organisms ranging from protozoa to mammals. We discuss the potential roles of the SAXO proteins in cilia and flagella function

Incidence of Respiratory Syncytial Virus Infection among Hospitalized Adults, 2017-2020

Background: Respiratory syncytial virus (RSV) causes acute respiratory illness (ARI) and triggers exacerbations of cardiopulmonary disease. Estimates of incidence in hospitalized adults range widely, with few data on incidence in adults with comorbidities that increase the risk of severity. We conducted a prospective, population-based, surveillance study to estimate incidence of RSV hospitalization among adults overall and those with specific comorbidities. Methods: Hospitalized adults aged ≥18 years residing in the surveillance area with ≥2 ARI symptoms or exacerbation of underlying cardiopulmonary disease were screened during the 2017–2018, 2018–2019, and 2019–2020 RSV seasons in 3 hospitals in Rochester, New York and New York City. Respiratory specimens were tested for RSV using polymerase chain reaction assays. RSV incidence per 100 000 was adjusted by market share. Results: Active and passive surveillance identified 1099 adults hospitalized with RSV. Annual incidence during 3 seasons ranged from 44.2 to 58.9/100 000. Age-group–specific incidence ranged from 7.7 to 11.9/100 000, 33.5 to 57.5/100 000, and 136.9 to 255.6/100 000 in patients ages 18–49, 50–64, and ≥65 years, respectively. Incidence rates in patients with chronic obstructive pulmonary disease, coronary artery disease, and congestive heart failure were 3–13, 4–7, and 4–33 times, respectively, the incidence in patients without these conditions. Conclusions: We found a high burden of RSV hospitalization in this large prospective study. Notable was the high incidence among older patients and those with cardiac conditions. These data confirm the need for effective vaccines to prevent RSV infection in older and vulnerable adults