Assessment of various standard fish diets on gut microbiome of platyfish Xiphophorus maculatus.

Diet is an external factor that affects the physiological baseline of research animals. It can shape gut microbiome, which can impact the host. As a result, dietary variation can challenge experimental reproducibility and data integration across studies when not appropriately considered. To control for diet-induced variation, reference diets have been developed for common biomedical models. However, such reference diets have not yet been developed for nontraditional model organisms, such as Xiphophorus species. In this study, we compared two diets designed for zebrafish, a commercial zebrafish diet (Gemma and GEM), and a proposed zebrafish reference diet developed by the Watts laboratory at the University of Alabama at Birmingham (WAT) to the Xiphophorus Genetic Stock Center custom diet (CON) to evaluate the influence of diet on the Xiphophorus gut microbiome. Xiphophorus maculatus were fed the three diets from 2 to 6 months of age. Feces were collected and the gut microbiome was assessed using 16S rRNA sequencing every month. We observed substantial diet-driven variation in the gut microbiome. Our results indicate that diets developed specifically for zebrafish can affect the gut microbiome composition and may not be optimal for Xiphophorus.

Plasmodium falciparum signal peptide peptidase cleaves malaria heat shock protein 101 (HSP101). Implications for gametocytogenesis.

Previously we described the identification of a Plasmodium falciparum signal peptide peptidase (PfSPP) functioning at the blood stage of malaria infection. Our studies also demonstrated that mammalian SPP inhibitors prevent malaria parasite growth at the late-ring/early trophozoite stage of intra-erythrocytic development. Consistent with its role in development, we tested the hypothesis that PfSPP functions at the endoplasmic reticulum of P.falciparum where it cleaves membrane-bound signal peptides generated following the enzyme activity of signal peptidase. The localization of PfSPP to the endoplasmic reticulum was confirmed by immunofluorescence microscopy and immunogold electron microscopy. Biochemical analysis indicated the existence of monomer and dimer forms of PfSPP in the parasite lysate. A comprehensive bioinformatics screen identified several candidate PfSPP substrates in the parasite genome. Using an established transfection based in vivo luminescence assay, malaria heat shock protein 101 (HSP101) was identified as a substrate of PfSPP, and partial inhibition of PfSPP correlated with the emergence of gametocytes. This finding unveils the first known substrate of PfSPP, and provides new perspectives for the function of intra-membrane proteolysis at the erythrocyte stage of malaria parasite life cycle.

Challenges Faced by U.S. Veterinary Technicians in the Workplace During COVID-19.

During COVID-19, the demand for veterinary technicians increased due to increased animal care appointments booked, decreased worker productivity, pandemic-related staffing shortages, and adapted methods of care delivery. Research has been conducted to assess the effect of the COVID-19 pandemic on educators and human healthcare workers, but there is a lack of literature on veterinary technicians, the animal healthcare equivalent of nurses. The objective of our study was to evaluate how COVID-19 affected veterinary technicians. We distributed an electronic researcher-developed survey-based instrument to veterinary technicians working in the U.S. during COVID-19. We received 1,132 usable responses. Descriptive statistics were analyzed using SPSS 26.0. Our respondents were overwhelmingly female (97%) and mostly employed full-time (87%) in a companion animal practice (61%). A majority of respondents reported COVID-19 had a large effect (45%) or completely dominated the work (12%) at their practice. While 52% of respondents felt their efforts during COVID-19 were appreciated, only 43% agreed or strongly agreed their hours were manageable. Support staff availability was completely or barely adequate for 42% of respondents and personal protective equipment was mostly or completely adequate for 60% of respondents. The greatest professional challenges during COVID-19 were being treated worse by animal owners and difficulty communicating with clients (53 and 16% of respondents, respectively). There have been few efforts to document the professional environment experienced by veterinary technicians during COVID-19. This is critical as pre-pandemic data indicate veterinary technicians are high-risk for professional burnout and COVID-19 placed additional burdens on essential workers.

Assessment of Various Standard Fish Diets on Growth and Fecundity of Platyfish (Xiphophorus maculatus) and Medaka (Oryzias latipes).

Several small freshwater fish species are utilized as models for human conditions and disease in biomedical research. Research animal diets are generally tailored to optimize growth, fecundity, and produce healthy research animals. However, a lack of reference diets presents a barrier in comparative studies between aquatic animal models and even among laboratories using the same species. Therefore, the objective of this study was to determine feeding regime and dietary effects on growth and fecundity in two commonly used freshwater fish, platyfish and medaka. From 1 through 6 months of age, platyfish and medaka were fed one of three feeding regime/diets: (1) our custom feeding regime consists of commercial flake food, beef liver paste, and live brine shrimp (CON); (2) a commercially available zebrafish diet, Gemma (GEM); and (3) a laboratory defined reference feeding regime (WAT). Weight, size, brood numbers, and survival rates for both species were measured monthly. Numbers of platyfish fry and hatch rate of medaka embryos were also determined. We observed that custom feeding regime (CON) fed platyfish and medaka grew larger, exhibited a higher survival rate, and had higher fecundity than WAT or GEM fed fish. These observations suggest that diets and regimes designed for zebrafish are not optimal to maintain platyfish or medaka. Thus, base diets, with clearly defined components and regimes, need to be developed with compositions that can be adjusted in a species-specific manner.

Identification, characterization, and comparative genomic distribution of the HERV-K (HML-2) group of human endogenous retroviruses.

BACKGROUND: Integration of retroviral DNA into a germ cell may lead to a provirus that is transmitted vertically to that host's offspring as an endogenous retrovirus (ERV). In humans, ERVs (HERVs) comprise about 8% of the genome, the vast majority of which are truncated and/or highly mutated and no longer encode functional genes. The most recently active retroviruses that integrated into the human germ line are members of the Betaretrovirus-like HERV-K (HML-2) group, many of which contain intact open reading frames (ORFs) in some or all genes, sometimes encoding functional proteins that are expressed in various tissues. Interestingly, this expression is upregulated in many tumors ranging from breast and ovarian tissues to lymphomas and melanomas, as well as schizophrenia, rheumatoid arthritis, and other disorders. RESULTS: No study to date has characterized all HML-2 elements in the genome, an essential step towards determining a possible functional role of HML-2 expression in disease. We present here the most comprehensive and accurate catalog of all full-length and partial HML-2 proviruses, as well as solo LTR elements, within the published human genome to date. Furthermore, we provide evidence for preferential maintenance of proviruses and solo LTR elements on gene-rich chromosomes of the human genome and in proximity to gene regions. CONCLUSIONS: Our analysis has found and corrected several errors in the annotation of HML-2 elements in the human genome, including mislabeling of a newly identified group called HML-11. HML-elements have been implicated in a wide array of diseases, and characterization of these elements will play a fundamental role to understand the relationship between endogenous retrovirus expression and disease.

Identification of a specific region of Plasmodium falciparum EBL-1 that binds to host receptor glycophorin B and inhibits merozoite invasion in human red blood cells.

The malaria parasite Plasmodium falciparum invades human erythrocytes through multiple pathways utilizing several ligand-receptor interactions. These interactions are broadly classified in two groups according to their dependency on sialic acid residues. Here, we focus on the sialic acid-dependent pathway by using purified glycophorins and red blood cells (RBCs) to screen a cDNA phage display library derived from P. falciparum FCR3 strain, a sialic acid-dependent strain. This screen identified several parasite proteins including the erythrocyte-binding ligand-1, EBL-1. The phage cDNA insert encoded the 69-amino acid peptide, termed F2i, which is located within the F2 region of the DBL domain, designated here as D2, of EBL-1. Recombinant D2 and F2i polypeptides bound to purified glycophorins and RBCs, and the F2i peptide was found to interfere with binding of D2 domain to its receptor. Both D2 and F2i polypeptides bound to trypsin-treated but not neuraminidase or chymotrypsin-treated erythrocytes, consistent with known glycophorin B resistance to trypsin, and neither the D2 nor F2i polypeptide bound to glycophorin B-deficient erythrocytes. Importantly, purified D2 and F2i polypeptides partially inhibited merozoite reinvasion in human erythrocytes. Our results show that the host erythrocyte receptor glycophorin B directly interacts with the DBL domain of parasite EBL-1, and the core binding site is contained within the 69 amino acid F2i region (residues 601-669) of the DBL domain. Together, these findings suggest that a recombinant F2i peptide with stabilized structure could provide a protective function at blood stage infection and represents a valuable addition to a multi-subunit vaccine against malaria.