Mysterious microsporidians: springtime outbreaks of disease in Daphnia communities in shallow pond ecosystems.

Parasites can play key roles in ecosystems, especially when they infect common hosts that play important ecological roles. Daphnia are critical grazers in many lentic freshwater ecosystems and typically reach peak densities in early spring. Daphnia have also become prominent model host organisms for the field of disease ecology, although most well-studied parasites infect them in summer or fall. Here, we report field patterns of virulent microsporidian parasites that consistently infect Daphnia in springtime, in a set of seven shallow ponds in Georgia, USA, sampled every 3-4 weeks for 18 months. We detected two distinct parasite taxa, closely matching sequences of Pseudoberwaldia daphniae and Conglomerata obtusa, both infecting all three resident species of Daphnia: D. ambigua, D. laevis, and D. parvula. To our knowledge, neither parasite has been previously reported in any of these host species or anywhere in North America. Infection prevalence peaked consistently in February-May, but the severity of these outbreaks differed substantially among ponds. Moreover, host species differed markedly in terms of their maximum infection prevalence (5% [D. parvula] to 72% [D. laevis]), mean reduction of fecundity when infected (70.6% [D. ambigua] to 99.8% [D. laevis]), mean spore yield (62,000 [D. parvula] to 377,000 [D. laevis] per host), and likelihood of being infected by each parasite. The timing and severity of the outbreaks suggests that these parasites could be impactful members of these shallow freshwater ecosystems, and that the strength of their effects is likely to hinge on the composition of ponds' zooplankton communities.

Fusogen-mediated neuron-neuron fusion disrupts neural circuit connectivity and alters animal behavior.

The 100-y-old neuron doctrine from Ramón y Cajal states that neurons are individual cells, rejecting the process of cell-cell fusion in the normal development and function of the nervous system. However, fusogens-specialized molecules essential and sufficient for the fusion of cells-are expressed in the nervous system of different species under conditions of viral infection, stress, or disease. Despite these findings, whether the expression of fusogens in neurons leads to cell-cell fusion, and, if so, whether this affects neuronal fate, function, and animal behavior, has not been explored. Here, using Caenorhabditis elegans chemosensory neurons as a model system, we provide proof-of-principle that aberrant expression of fusogens in neurons results in neuron-neuron fusion and behavioral impairments. We demonstrate that fusion between chemoattractive neurons does not affect the response to odorants, whereas fusion between chemoattractive and chemorepulsive neurons compromises chemosensation. Moreover, we provide evidence that fused neurons are viable and retain their original specific neuronal fate markers. Finally, analysis of calcium transients reveals that fused neurons become electrically coupled, thereby compromising neural circuit connectivity. Thus, we propose that aberrant expression of fusogens in the nervous system disrupts neuronal individuality, which, in turn, leads to a change in neural circuit connectivity and disruption of normal behavior. Our results expose a previously uncharacterized basis of circuit malfunction, and a possible underlying cause of neurological diseases.

Epidermal control of axonal attachment via ß-spectrin and the GTPase-activating protein TBC-10 prevents axonal degeneration.

Neurons are subjected to strain due to body movement and their location within organs and tissues. However, how they withstand these forces over the lifetime of an organism is still poorly understood. Here, focusing on touch receptor neuron-epidermis interactions using Caenorhabditis elegans as a model system, we show that UNC-70/ß-spectrin and TBC-10, a conserved GTPase-activating protein, function non-cell-autonomously within the epidermis to dynamically maintain attachment of the axon. We reveal that, in response to strain, UNC-70/ß-spectrin and TBC-10 stabilize trans-epidermal hemidesmosome attachment structures which otherwise become lost, causing axonal breakage and degeneration. Furthermore, we show that TBC-10 regulates axonal attachment and maintenance by inactivating RAB-35, and reveal functional conservation of these molecules with their vertebrate orthologs. Finally, we demonstrate that ß-spectrin functions in this context non-cell-autonomously. We propose a model in which mechanically resistant epidermal attachment structures are maintained by UNC-70/ß-spectrin and TBC-10 during movement, preventing axonal detachment and degeneration.

"It's Awful When We Get It Wrong": An Exploratory Qualitative Study of Vocational Rehabilitation Counselors' Perspectives on Suicide.

Despite the high prevalence of suicide among people with disabilities, little research has explored suicide in the context of the vocational rehabilitation (VR) system. We analyzed the responses of 27 VR counselors who responded to an open-ended qualitative prompt regarding their experiences with suicide training and competency. Key themes included a desire for more training on suicide and the experience of seeking and receiving suicide training and experience outside of VR. Responses also underscored the heavy emotional impact of working with suicidal clients, especially when one feels unprepared to do so. These results suggest that it is important to provide VR counselors with resources and training for addressing suicide in their client populations.

Examining the Contributions of Disability to Suicidality in the Context of Depression Symptoms and Other Sociodemographic Factors.

We examined the contribution of disability status to suicidality when accounting for depression and sociodemographic risk factors in 438 American adults, 82 (18.7%) of whom identified as having disabilities. Participants with disabilities had significantly higher depression scores and were more likely to be unemployed and unpartnered, all of which were also associated with increased suicidality. However, disability remained a significant predictor of suicidality even when depression and sociodemographic risk factors were accounted for in a linear regression. Other significant predictors of suicidality in this regression were female gender, depression symptoms, and family and friend suicide history; identifying as a member of a religion was a significant protective factor against suicidality. Our findings suggest that the contribution of disability to suicidality goes beyond that which can be explained by increased depression symptoms and sociodemographic vulnerability.

"I Honestly Would Not Have Known What to Do": An Exploratory Study of Perspectives on Client Suicide Among Vocational Rehabilitation Support Staff.

Despite the high prevalence of suicide both overall and among people with disabilities in particular, little research has explored suicide in the context of the vocational rehabilitation (VR) system or in counseling support staff in general. We analyzed the responses of 14 VR support staff who responded to an open-ended qualitative prompt regarding their experiences with suicide training and competency. Key themes included a perceived lack of and desire for more training regarding suicide, seeking and receiving suicide training outside of VR, and a perceived lack of resources for working with suicidal clients. Responses also underscored the heavy emotional impact of working with these clients, especially when one feels unprepared to do so. These results suggest that it is important to provide VR support staff with resources and training for addressing suicide in their client populations.

Differential expression of MUC4, GPR110 and IL2RA defines two groups of CRLF2-rearranged acute lymphoblastic leukemia patients with distinct secondary lesions.

CRLF2-rearrangements (CRLF2-r) occur frequently in Ph-like B-ALL, a high-risk ALL sub-type characterized by a signaling profile similar to Ph + ALL, however accumulating evidence indicates genetic heterogeneity within CRLF2-r ALL. We performed thorough genomic characterization of 35 CRLF2-r cases (P2RY8-CRLF2 n = 18; IGH-CRLF2 n = 17). Activating JAK2 mutations were present in 34% of patients, and a CRLF2-F232C mutation was identified in an additional 17%. IKZF1 deletions were detected in 63% of cases. The majority of patients (26/35) classified as Ph-like, and these were characterized by significantly higher levels of MUC4, GPR110 and IL2RA/CD25. In addition, Ph-like CRLF2-r samples were significantly enriched for IKZF1 deletions, JAK2/CRLF2 mutations and increased expression of JAK/STAT target genes (CISH, SOCS1), suggesting that mutation-driven CRLF2/JAK2 activation is more frequent in this sub-group. Less is known about the genomics of CRLF2-r cases lacking JAK2-pathway mutations, but KRAS/NRAS mutations were identified in 4/9 non-Ph-like samples. This work highlights the heterogeneity of secondary lesions which may arise and influence intracellular-pathway activation in CRLF2-r patients, and importantly presents distinct therapeutic targets within a group of patients harboring identical primary translocations, for whom efficient directed therapies are currently lacking.