The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Phillip A Newmark - One of the best experts on this subject based on the ideXlab platform.
-
region specific regulation of stem cell driven regeneration in Tapeworms
eLife, 2019Co-Authors: Tania Rozario, Edward B Quinn, Jianbin Wang, Richard E Davis, Phillip A NewmarkAbstract:Many worms have remarkable abilities to regrow and repair their bodies. The parasitic Tapeworms, for example, can reach lengths of several meters and grow much more quickly than tissues in humans and other complex animals. This growth allows Tapeworms to counteract the continual loss of the segments that make up their bodies, known as proglottids – a process that happens throughout their lives. The capacity to regenerate thousands of lost body segments and maintain an overall body length suggests that Tapeworms have groups of stem cells in their body which can grow and divide to produce the new body parts. Yet, regeneration in Tapeworms has not been closely studied. Rozario et al. have now examined Hymenolepsis diminuta, the rat tapeworm, and identified the neck of the tapeworm as crucial for its ability to regrow lost body segments. Further analysis identified two genes, zmym3 and pogzl, that are essential for cell division during tapeworm growth. However, Rozario et al. showed that these genes are active elsewhere in the worm’s body and that it is the conditions found specifically in the tapeworm’s neck that create the right environment for stem cells to enable regeneration of new segments. Tapeworms provide a valuable example for studying the growth of stem cells and these findings highlight the important role that the cells’ surroundings play in driving stem cell activity. These findings could also lead to new insights into how stem cells behave in other animals and could potentially lead to new approaches to prevent or treat tapeworm infections.
-
region specific regulation of stem cell driven regeneration in Tapeworms
bioRxiv, 2018Co-Authors: Tania Rozario, Edward B Quinn, Jianbin Wang, Richard E Davis, Phillip A NewmarkAbstract:Tapeworms grow at rates that rival all metazoan tissues, including during embryonic and neoplastic growth. For example, the rat intestinal tapeworm, Hymenolepis diminuta , produces up to 2,200 proglottids (segments), increasing in length up to 3,400 fold, and weight up to 1.8 million fold within the first 15 days of infection. Tapeworms also regenerate: they shed large parts of their body, releasing their embryos to continue their life cycle, yet are able to continuously replenish proglottids and maintain an equilibrium length. Such remarkable growth and regeneration are fueled by adult somatic stem cells, which have yet to be characterized molecularly. Using H. diminuta as a laboratory model, we find that regeneration is limited to the tapeworm neck, making this tissue a prime source to identify stem cell genes. Using transcriptomic analyses and RNA interference (RNAi), we characterize and functionally validate the first molecular regulators of tapeworm growth and regeneration. However, we find no evidence that stem cells are restricted to the regeneration-competent neck. Instead, we find that lethally irradiated Tapeworms can be rescued from death when cells from both regeneration-competent and regeneration-incompetent regions are transplanted into the neck. Furthermore, the persistence of regenerative ability over time requires signal(s) from the head, even though the head itself cannot regenerate and the head is not necessary for initial regeneration. Together, the head and neck tissue provide a microenvironment that regulates stem cells to enable region-specific regeneration in this tapeworm.
-
A confocal microscopy-based atlas of tissue architecture in the tapeworm Hymenolepis diminuta.
Experimental Parasitology, 2015Co-Authors: Tania Rozario, Phillip A NewmarkAbstract:Abstract Tapeworms are pervasive and globally distributed parasites that infect millions of humans and livestock every year, and are the causative agents of two of the 17 neglected tropical diseases prioritized by the World Health Organization. Studies of tapeworm biology and pathology are often encumbered by the complex life cycles of disease-relevant tapeworm species that infect hosts such as foxes, dogs, cattle, pigs, and humans. Thus, studies of laboratory models can help overcome the practical, ethical, and cost-related difficulties faced by tapeworm parasitologists. The rat intestinal tapeworm Hymenolepis diminuta is easily reared in the laboratory and has the potential to enable modern molecular-based experiments that will greatly contribute to our understanding of multiple aspects of tapeworm biology, such as growth and reproduction. As part of our efforts to develop molecular tools for experiments on H. diminuta , we have characterized a battery of lectins, antibodies, and common stains that label different tapeworm tissues and organ structures. Using confocal microscopy, we have assembled an “atlas” of H. diminuta organ architecture that will be a useful resource for helminthologists. The methodologies we describe will facilitate characterization of loss-of-function perturbations using H. diminuta . This toolkit will enable a greater understanding of fundamental tapeworm biology that may elucidate new therapeutic targets toward the eradication of these parasites.
M C Romano - One of the best experts on this subject based on the ideXlab platform.
-
the synthesis of steroids by taenia crassiceps wfu cysticerci and Tapeworms is related to the developmental stages of the parasites
General and Comparative Endocrinology, 2017Co-Authors: J M Patriciogomez, R A Valdez, A Veloz, L Aguilarvega, R Zurabian, M C RomanoAbstract:Abstract Taeniids Tapeworms are hermaphroditic helminths that gradually develop testis and ovaries in their reproductive units. The larval stage of the Tapeworms named cysticercus is a vesicle that contains the scolex and proliferates asexually in the abdominal cavity of mice. Once in the host, they evaginate, attach to the gut and develop into an adult organism, the tapeworm. We have previously reported reported that T. crassiceps ORF and solium cysticerci transform steroid precursors to androgens and estrogens. Taenia crassiceps WFU cysticerci can also synthesize corticosteroids. The aim of the present work is to investigate the relationship between steroid synthesis ability and the developmental stage of the parasite T. crassiceps WFU. To this purpose, cysticerci were obtained from the abdominal cavity of female mice, manually separated in invaginated (IC) and evaginated parasites (EC) and preincubated for 24 h in DMEM plus antibiotics/antimycotics. Next step consisted in incubation for different periods in the fresh media added with tritiated androstenedione (3H-A4) or progesterone (3H-P4) and incubated for different periods. Taenia crassiceps WFU Tapeworms were recovered from the intestine of golden hamsters that had been orally infected with cysticerci. The worms were pre-cultured in DMEM plus FBS and antibiotics, and then incubated without FBS for different time periods, in the presence of 3H-A4 or 3H-P4. At the end of the experiments the media from cysticerci and Tapeworms were analyzed by thin layer chromatography. Results showed that testosterone synthesis was significantly higher in the evaginated cysticerci and increased with time in culture. The invaginated and evaginated cysticerci also synthesized small quantities of 17s-estradiol (E2) and estrone. The evaginated cysticerci synthesized twice more 3H-deoxycorticosterone (3H-DOC) than the invaginated parasites, the production increased significantly with time in culture. Taenia crassiceps WFU Tapeworms synthesized significant quantities of 3H-testosterone and small amounts of estrone after only 3 h of culture in the presence of 3H-A4. The Tapeworms also transformed 3H-P4 to 3H-DOC and increased its synthesis after 24 h in culture. In summary, our data show the pathways that T. crassiceps WFU cysticerci use to synthesize sexual steroids in both larval developmental stages and reveals the steroidogenic capacity of the Tapeworms.
-
taenia solium Tapeworms synthesize corticosteroids and sex steroids in vitro
General and Comparative Endocrinology, 2014Co-Authors: R A Valdez, Kaethe Willms, Pedro Jimenez, A Fernandez M Presas, L Aguilar, M C RomanoAbstract:Abstract Cysticercosis is a disease caused by the larval stage of Taenia solium cestodes that belongs to the family Taeniidae that affects a number of hosts including humans. Taeniids Tapeworms are hermaphroditic organisms that have reproductive units called proglottids that gradually mature to develop testis and ovaries. Cysticerci, the larval stage of these parasites synthesize steroids. To our knowledge there is no information about the capacity of T. solium Tapeworms to metabolize progesterone or other precursors to steroid hormones. Therefore, the aim of this paper was to investigate if T. solium Tapeworms were able to transform steroid precursors to corticosteroids and sex steroids. T. solium Tapeworms were recovered from the intestine of golden hamsters that had been orally infected with cysticerci. The worms were cultured in the presence of tritiated progesterone or androstenedione. At the end of the experiments the culture media were analyzed by thin layer chromatography. The experiments described here showed that small amounts of testosterone were synthesized from 3 H-progesterone by complete or segmented Tapeworms whereas the incubation of segmented Tapeworms with 3 H-androstenedione, instead of 3 H-progesterone, improved their capacity to synthesize testosterone. In addition, the incubation of the parasites with 3 H-progesterone yielded corticosteroids, mainly deoxicorticosterone (DOC) and 11-deoxicortisol. In summary, the results described here, demonstrate that T. solium Tapeworms synthesize corticosteroid and sex steroid like metabolites. The capacity of T. solium Tapeworms to synthesize steroid hormones may contribute to the physiological functions of the parasite and also to their interaction with the host.
R A Valdez - One of the best experts on this subject based on the ideXlab platform.
-
the synthesis of steroids by taenia crassiceps wfu cysticerci and Tapeworms is related to the developmental stages of the parasites
General and Comparative Endocrinology, 2017Co-Authors: J M Patriciogomez, R A Valdez, A Veloz, L Aguilarvega, R Zurabian, M C RomanoAbstract:Abstract Taeniids Tapeworms are hermaphroditic helminths that gradually develop testis and ovaries in their reproductive units. The larval stage of the Tapeworms named cysticercus is a vesicle that contains the scolex and proliferates asexually in the abdominal cavity of mice. Once in the host, they evaginate, attach to the gut and develop into an adult organism, the tapeworm. We have previously reported reported that T. crassiceps ORF and solium cysticerci transform steroid precursors to androgens and estrogens. Taenia crassiceps WFU cysticerci can also synthesize corticosteroids. The aim of the present work is to investigate the relationship between steroid synthesis ability and the developmental stage of the parasite T. crassiceps WFU. To this purpose, cysticerci were obtained from the abdominal cavity of female mice, manually separated in invaginated (IC) and evaginated parasites (EC) and preincubated for 24 h in DMEM plus antibiotics/antimycotics. Next step consisted in incubation for different periods in the fresh media added with tritiated androstenedione (3H-A4) or progesterone (3H-P4) and incubated for different periods. Taenia crassiceps WFU Tapeworms were recovered from the intestine of golden hamsters that had been orally infected with cysticerci. The worms were pre-cultured in DMEM plus FBS and antibiotics, and then incubated without FBS for different time periods, in the presence of 3H-A4 or 3H-P4. At the end of the experiments the media from cysticerci and Tapeworms were analyzed by thin layer chromatography. Results showed that testosterone synthesis was significantly higher in the evaginated cysticerci and increased with time in culture. The invaginated and evaginated cysticerci also synthesized small quantities of 17s-estradiol (E2) and estrone. The evaginated cysticerci synthesized twice more 3H-deoxycorticosterone (3H-DOC) than the invaginated parasites, the production increased significantly with time in culture. Taenia crassiceps WFU Tapeworms synthesized significant quantities of 3H-testosterone and small amounts of estrone after only 3 h of culture in the presence of 3H-A4. The Tapeworms also transformed 3H-P4 to 3H-DOC and increased its synthesis after 24 h in culture. In summary, our data show the pathways that T. crassiceps WFU cysticerci use to synthesize sexual steroids in both larval developmental stages and reveals the steroidogenic capacity of the Tapeworms.
-
taenia solium Tapeworms synthesize corticosteroids and sex steroids in vitro
General and Comparative Endocrinology, 2014Co-Authors: R A Valdez, Kaethe Willms, Pedro Jimenez, A Fernandez M Presas, L Aguilar, M C RomanoAbstract:Abstract Cysticercosis is a disease caused by the larval stage of Taenia solium cestodes that belongs to the family Taeniidae that affects a number of hosts including humans. Taeniids Tapeworms are hermaphroditic organisms that have reproductive units called proglottids that gradually mature to develop testis and ovaries. Cysticerci, the larval stage of these parasites synthesize steroids. To our knowledge there is no information about the capacity of T. solium Tapeworms to metabolize progesterone or other precursors to steroid hormones. Therefore, the aim of this paper was to investigate if T. solium Tapeworms were able to transform steroid precursors to corticosteroids and sex steroids. T. solium Tapeworms were recovered from the intestine of golden hamsters that had been orally infected with cysticerci. The worms were cultured in the presence of tritiated progesterone or androstenedione. At the end of the experiments the culture media were analyzed by thin layer chromatography. The experiments described here showed that small amounts of testosterone were synthesized from 3 H-progesterone by complete or segmented Tapeworms whereas the incubation of segmented Tapeworms with 3 H-androstenedione, instead of 3 H-progesterone, improved their capacity to synthesize testosterone. In addition, the incubation of the parasites with 3 H-progesterone yielded corticosteroids, mainly deoxicorticosterone (DOC) and 11-deoxicortisol. In summary, the results described here, demonstrate that T. solium Tapeworms synthesize corticosteroid and sex steroid like metabolites. The capacity of T. solium Tapeworms to synthesize steroid hormones may contribute to the physiological functions of the parasite and also to their interaction with the host.
Kaethe Willms - One of the best experts on this subject based on the ideXlab platform.
-
taenia solium Tapeworms synthesize corticosteroids and sex steroids in vitro
General and Comparative Endocrinology, 2014Co-Authors: R A Valdez, Kaethe Willms, Pedro Jimenez, A Fernandez M Presas, L Aguilar, M C RomanoAbstract:Abstract Cysticercosis is a disease caused by the larval stage of Taenia solium cestodes that belongs to the family Taeniidae that affects a number of hosts including humans. Taeniids Tapeworms are hermaphroditic organisms that have reproductive units called proglottids that gradually mature to develop testis and ovaries. Cysticerci, the larval stage of these parasites synthesize steroids. To our knowledge there is no information about the capacity of T. solium Tapeworms to metabolize progesterone or other precursors to steroid hormones. Therefore, the aim of this paper was to investigate if T. solium Tapeworms were able to transform steroid precursors to corticosteroids and sex steroids. T. solium Tapeworms were recovered from the intestine of golden hamsters that had been orally infected with cysticerci. The worms were cultured in the presence of tritiated progesterone or androstenedione. At the end of the experiments the culture media were analyzed by thin layer chromatography. The experiments described here showed that small amounts of testosterone were synthesized from 3 H-progesterone by complete or segmented Tapeworms whereas the incubation of segmented Tapeworms with 3 H-androstenedione, instead of 3 H-progesterone, improved their capacity to synthesize testosterone. In addition, the incubation of the parasites with 3 H-progesterone yielded corticosteroids, mainly deoxicorticosterone (DOC) and 11-deoxicortisol. In summary, the results described here, demonstrate that T. solium Tapeworms synthesize corticosteroid and sex steroid like metabolites. The capacity of T. solium Tapeworms to synthesize steroid hormones may contribute to the physiological functions of the parasite and also to their interaction with the host.
-
The key steroidogenic enzyme 3β-hydroxysteroid dehydrogenase in Taenia solium and Taenia crassiceps (WFU)
Parasitology Research, 2008Co-Authors: Ana María Fernández Presas, Kaethe Willms, Ricardo A. Valdez, Marta C. RomanoAbstract:Larval and adult stages of Taenia solium and Taenia crassiceps WFU strain were analyzed by histochemical and biochemical methods to determine the existence of steroid pathways. The presence of the key enzyme 3β-hydroxisteroid-dehydrogenase (3β-HSD) was examined in frozen sections of cysticerci obtained from mice and segments of Tapeworms obtained from the intestine of hamsters. 3β-HSD activity was detected by nitroblue-tetrazolium products after incubation with dehydroepiandrosterone, androstendiol, or pregnenolone. Tapeworm tissues exhibited 3β-HSD activity in the subtegumentary areas of the neck and immature proglottids following incubation with androstendiol, as well as surrounding the testes in mature proglottids. T. solium cysticerci exhibited 3β-HSD activity in the subtegumentary tissues. The synthesis of steroid hormones involving the activity of 3β-HSD was studied in cysticerci or Tapeworms incubated in the presence of tritiated steroid precursors. The culture media were analyzed by thin layer chromatography and showed synthesis of androstendiol, testosterone, and 17β-estradiol by cysticerci, androstendiol, and 17β-estradiol by Tapeworms. The results strongly suggest the activity of 3β-HSD in taeniid parasites that have at least a part of the enzymatic chain required for androgen and estrogen synthesis and that the enzymes are present in the larval stage and from the early strobilar stages to the mature proglottids.
-
Morphology and biochemistry of the pork tapeworm, Taenia solium.
Current Topics in Medicinal Chemistry, 2008Co-Authors: Kaethe WillmsAbstract:: This chapter describes the life cycle, general morphology and ultrastructure of the larval and adult stages of Taenia solium, a parasitic flatworm of humans found in underdeveloped countries. Experimental results describing the role of proteins and glycoproteins in the host-parasite relationship, as well as the various strategies the larval stage has developed to evade the host immune responses are analyzed. Characteristics of the tapeworm attachment site in the hamster intestine and the host inflammatory reaction are reviewed. The general morphology and ultrastructure of the experimental tapeworm is described, with emphasis on muscle fiber distribution, the abundance of cytoplasmic glycogen and its association with gap junctions, the development of testis, structure of mature spermatids and vas efferens. Recent descriptions of T. solium actin, myosin and calreticulin components, metabolic steroid pathways, apoptosis and glucose uptake of Tapeworms in the hamster model are reviewed.
Marta C. Romano - One of the best experts on this subject based on the ideXlab platform.
-
The key steroidogenic enzyme 3β-hydroxysteroid dehydrogenase in Taenia solium and Taenia crassiceps (WFU)
Parasitology Research, 2008Co-Authors: Ana María Fernández Presas, Kaethe Willms, Ricardo A. Valdez, Marta C. RomanoAbstract:Larval and adult stages of Taenia solium and Taenia crassiceps WFU strain were analyzed by histochemical and biochemical methods to determine the existence of steroid pathways. The presence of the key enzyme 3β-hydroxisteroid-dehydrogenase (3β-HSD) was examined in frozen sections of cysticerci obtained from mice and segments of Tapeworms obtained from the intestine of hamsters. 3β-HSD activity was detected by nitroblue-tetrazolium products after incubation with dehydroepiandrosterone, androstendiol, or pregnenolone. Tapeworm tissues exhibited 3β-HSD activity in the subtegumentary areas of the neck and immature proglottids following incubation with androstendiol, as well as surrounding the testes in mature proglottids. T. solium cysticerci exhibited 3β-HSD activity in the subtegumentary tissues. The synthesis of steroid hormones involving the activity of 3β-HSD was studied in cysticerci or Tapeworms incubated in the presence of tritiated steroid precursors. The culture media were analyzed by thin layer chromatography and showed synthesis of androstendiol, testosterone, and 17β-estradiol by cysticerci, androstendiol, and 17β-estradiol by Tapeworms. The results strongly suggest the activity of 3β-HSD in taeniid parasites that have at least a part of the enzymatic chain required for androgen and estrogen synthesis and that the enzymes are present in the larval stage and from the early strobilar stages to the mature proglottids.
