Biology subjects

Hlavacova, J.

Publications and source records attributed to Hlavacova, J..

3 recordsLinked to original sources

bioRxiv2021

Presence of Toxoplasma gondii tissue cysts in human semen

Toxoplasma gondii is a widely prevalent protozoan parasite in human populations. This parasite is thought to be primarily transmitted through undercooked meat and contamination by cat feces. Here, we demonstrate that Toxoplasma gondii cysts can be found within human semen, thus suggesting a potential for sexual transmission. We visualized Toxoplasma gondii cysts in ejaculates of immune-competent and latently infected human volunteers. We confirmed the encystment by probing transcription of a bradyzoite-specific gene in these structures. These observations extend previous observations of the parasite in semen of several non-human host species, including rats, dogs, and sheep. Toxoplasma gondii infection is a clinically significant infection, in view of its high prevalence, its purported role in neuropsychiatric disorders such as schizophrenia, as well as in the more serious form of congenital toxoplasmosis. Our demonstration of intact Toxoplasma gondii cysts in the ejaculate supports the possibility of sexual transmission of the parasite and provides an impetus for further investigations. ImportanceToxoplasma gondii is recognized as one of the five infections that can harm fetal health. There is also emerging evidence that toxoplasmosis is related to the development of neuropsychiatric disorders. In this context, the current report includes visual evidence of Toxoplasma gondii cyst presence in the semen of human males. It is thus plausible that this clinically significant infection can be sexually transmitted. The existence of sexual transmission in a population, and its relative importance vis-a-vis other transmission routes, remains undetermined. These possibilities are of acute relevance to human health in the context of sexual health and pregnancy management.

microbiology↗

bioRxiv2019

Increased calcidiol level in redhaired people: Could redheadedness be an adaptation to temperate climate?

About 1-2% of European population are redhaired, meaning they synthesize more pheomelanin than eumelanin, the main melanin pigment. Several mutations could be responsible for this phenotype. It has been suggested that corresponding mutations spread in Europe due to a founder effect shaped either by a relaxation of selection for dark, UV-protective phenotypes or by sexual selection in favor of rare phenotypes. In our study, we investigated the levels of vitamin D precursor calcidiol and folic acid in the blood serum of 73 redhaired and 130 non-redhaired individuals. In redhaired individuals, we found higher calcidiol concentrations and approximately the same folic acid concentrations as in non-redhaired subjects. Calcidiol concentrations correlated with the intensity of hair redness measured by two spectrophotometric methods and estimated by participants themselves and by independent observers. In non-redhaired individuals, calcidiol levels covaried with the amount of sun exposure and intensity of suntan while in redhaired individuals, this was not the case. It suggests that increased calcidiol levels in redhaired individuals are due to differences in physiology rather than in behavior. We also found that folic acid levels increased with age and the intensity of baldness and decreased with the frequency of visiting tanning salons. Our results suggest that the redhaired phenotype could be an evolutionary adaptation for sufficient photosynthesis of provitamin D in conditions of low intensity of UV-B radiation in central and northern parts of Europe.

evolutionary biology↗

bioRxiv2017

Effects of latent toxoplasmosis on olfactory functions of men and women

The prevalence of toxoplasmosis is higher in schizophrenics than in the general population. It has been suggested that certain symptoms of schizophrenia, including changes in olfactory functions, are in fact symptoms of toxoplasmosis that can be easily detected in schizophrenics only due to the increased prevalence of toxoplasmosis in this population. Schizophrenics have impaired identification of odors and lower sensitivity of odor detection. Here we searched for differences in olfactory functions between 62 infected and 61 noninfected non-schizophrenic subjects. The infected men scored better in the standard odor-identification test. The infected women rated all smells as more intensive while the infected men rated nearly all smells as less intensive. Infected women rated the pleasantness of the smell of undiluted cat urine as higher than the non-infected women and the opposite was true for the men (the opposite direction shifts in men and women were described earlier for highly diluted cat urine). Toxoplasmosis had no effect on the rated pleasantness of the smell of other stimuli. Our results suggest that latent toxoplasmosis is associated with changes in the olfactory functions in humans; however, the observed changes differ from those observed in schizophrenics.\n\nKey findingsO_LIInfected men but not women show better odor identification ability than the non-infected controls.\nC_LIO_LIThe infected women rated all smells as more and men as less intensive than the controls.\nC_LIO_LIThe infected women rated smell of cat urine as more and men as less pleasurable than the controls.\nC_LIO_LIToxoplasmosis had no effect on the rated pleasantness of the smell of other stimuli.\nC_LIO_LIWe found no new evidence for the toxoplasmosis hypothesis of schizophrenia.\nC_LI

animal behavior and cognition↗