Arginine metabolism in Trichomonas vaginalis infected with Mycoplasma hominis

Both Mycoplasma hominis and Trichomonas vaginalis utilize arginine as an energy source via the arginine dihydrolase (ADH) pathway. It has been previously demonstrated that M. hominis forms a stable intracellular relationship with T. vaginalis; hence, in this study we examined the interaction of two localized ADH pathways by comparing T. vaginalis strain SS22 with the laboratory-generated T. vaginalis strain SS22-MOZ2 infected with M. hominis MOZ2. The presence of M. hominis resulted in an approximately 16-fold increase in intracellular ornithine and a threefold increase in putrescine, compared with control T. vaginalis cultures. No change in the activity of enzymes of the ADH pathway could be demonstrated in SS22-MOZ2 compared with the parent SS22, and the increased production of ornithine could be attributed to the presence of M. hominis. Using metabolic flow analysis it was determined that the elasticity of enzymes of the ADH pathway in SS22-MOZ2 was unchanged compared with the parent SS22; however, the elasticity of ornithine decarboxylase (ODC) in SS22 was small, and it was doubled in SS22-MOZ2 cells. The potential benefit of this relationship to both T. vaginalis and M. hominis is discussed

Protists: Eukaryotic single-celled organisms and the functioning of their organelles

Organelles are membrane bound structures that compartmentalize biochemical and molecular functions. With improved molecular, biochemical and microscopy tools the diversity and function of protistan organelles has increased in recent years, providing a complex panoply of structure/function relationships. This is particularly noticeable with the description of hydrogenosomes, and the diverse array of structures that followed, having hybrid hydrogenosome/mitochondria attributes. These diverse organelles have lost the major, at one time, definitive components of the mitochondrion (tricarboxylic cycle enzymes and cytochromes), however they all contain the machinery for the assembly of Fe-S clusters, which is the single unifying feature they share. The plasticity of organelles, like the mitochondrion, is therefore evident from its ability to lose its identity as an aerobic energy generating powerhouse while retaining key ancestral functions common to both aerobes and anaerobes. It is interesting to note that the apicoplast, a non-photosynthetic plastid that is present in all apicomplexan protozoa, apart from Cryptosporidium and possibly the gregarines, is also the site of Fe-S cluster assembly proteins. It turns out that in Cryptosporidium proteins involved in Fe-S cluster biosynthesis are localized in the mitochondrial remnant organelle termed the mitosome. Hence, different organisms have solved the same problem of packaging a life-requiring set of reactions in different ways, using different ancestral organelles, discarding what is not needed and keeping what is essential. Don’t judge an organelle by its cover, more by the things it does, and always be prepared for surprises

Hydrogenosome-localization of arginine deiminase in <i>Trichomonas vaginalis</i>

The arginine dihydrolase (ADH) pathway has an analogous function to the urea cycle in mitochondria-containing cells, by removing nitrogen from amino acids and generating ATP. Subcellular localization of the ADH pathway enzymes in Trichomonas vaginalis revealed that arginine deiminase (ADI) localizes to the hydrogenosome, a mitochondrion-like organelle of anaerobic protists. However the other enzymes of the ADH pathway, ornithine carbamyltransferase and carbamate kinase localize to the cytosol. Three gene sequences of T. vaginalis ADI (ADI 1–3) were identified in the T. vaginalis genome, all having putative mitochondrial targeting sequences. The ADI sequences were cloned and used to probe T. vaginalis using a carboxyterminal di-hemogglutinin epitope tag which demonstrated co-localization with malic enzyme confirming the hydrogenosome localization of this enzyme

Activities of dl-α-Difluoromethylarginine and Polyamine Analogues against Cryptosporidium parvum Infection in a T-Cell Receptor Alpha-Deficient Mouse Model

The in vivo effectiveness of a series of conformationally restricted polyamine analogues alone and selected members in combination with dl-α-difluoromethylarginine against Cryptosporidium parvum infection in a T-cell receptor alpha-deficient mouse model was tested. Polyamine analogues were selected from the extended bis(ethyl)-sym-homospermidine or bis(ethyl)-spermine backbone having cis or trans double bonds at the center of the molecule. The cis isomers were found to have significantly greater efficacy in both preventing and curing infection in a mouse model than the trans polyamine analogues when tested in a T-cell receptor alpha-deficient mouse model. When tested in combination with dl-α-difluoromethylarginine, the cis-restricted analogues were found to be more effective in preventing oocyst shedding. This study demonstrates the potential of polyamine analogues as anticryptosporidial agents and highlights the presence of multiple points in polyamine synthesis by this parasite that are susceptible to inhibition resulting in growth inhibition

Living with the Virus: Graduate School Students Evaluation of Stressors Related to the Pandemic

The Coronavirus Disease (COVID-19) becomes a global threat in March of 2020. Several countries were on lockdown. It affects health and results in post-traumatic stress disorder (PTSD). During the quarantine and lockdown, the lack of freedom resulted to psychological consequences. In the Philippines, it was March 15, 2020 when the initial COVID-19 was instituted commonly recalled due to lockdown and canceled classes. Filipinos in general and students in particular were worried of their health information including vaccine availability, efficacy, and infection rates. Mental health is impaired by pandemic risks. UNICEF Philippines, then, advocated alternative and continuing learning.&nbsp; The major purpose of this research is to determine graduate students' levels of stress during the COVID-19 outbreak. The descriptive-correlational design was used for the quantitative investigation. The 150 responders are selected at random from Metro Manila master's degree students in the academic year 2022-2023. The adopted questionnaire consists of seven items that are multidimensional scales with psychometric qualities. Using chi-square, the findings revealed that, among demographic profiles, only age showed a significant relationship with the association of global stress. Thus, it can be stated that age is a crucial factor in assessing the global stress of graduate students. COVID-19 is more contagious in adults, reflecting their anxiety and stress during the epidemic