Endoplasmic reticulum localized TMEM33 domain-containing protein is crucial for all life cycle stages of the malaria parasite

Endoplasmic reticulum (ER) plays a pivotal role in the regulation of stress responses in multiple eukaryotic cells. However, little is known about the effector mechanisms that regulate stress responses in ER of the malaria parasite. Herein, we aimed to identify the importance of a transmembrane protein 33 (TMEM33)-domain-containing protein in life cycle of the rodent malaria parasite Plasmodium berghei. TMEM33 is an ER membrane-resident protein that is involved in regulating stress responses in various eukaryotic cells. A C-terminal tagged TMEM33 was localized in the ER throughout the blood and mosquito stages of development. Targeted deletion of TMEM33 confirmed its importance for asexual blood stages and ookinete development, in addition to its essential role for sporozoite infectivity in the mammalian host. Pilot scale analysis shows that the loss of TMEM33 results in the initiation of ER stress response and induction of autophagy. Our findings conclude an important role of TMEM33 in the development of all life cycle stages of the malaria parasite, which indicates its potential as an antimalarial target.

A Candidate Bacterial-Type Amino Acid Decarboxylase Is Essential for Male Gamete Exflagellation and Mosquito Transmission of the Malaria Parasite

A frequent side effect of chemotherapy against malaria parasite blood infections is a dramatic induction of the sexual blood stages, thereby enhancing the risk of future malaria transmissions. The polyamine biosynthesis pathway has been suggested as a candidate target for transmission-blocking anti-malarial drug development. Herein, we describe the role of a bacterial-type amino acid decarboxylase (AAD) in the life cycle of the malaria model parasite Plasmodium yoelii. Hallmarks of AAD include a conserved catalytic lysine residue and high-level homology to arginine/lysine/ornithine decarboxylases of pathogenic bacteria. By targeted gene deletion, we show that AAD plays an essential role in the exflagellation of microgametes, resulting in complete absence of sporozoites in the mosquito vector. These data highlight the central role of the biosysthesis of polyamines in the final steps of male gamete sexual development of the malaria parasite and, hence, onward transmission to mosquitoes.

Genetic disruption of nucleoside transporter 4 reveals its critical roles in malaria parasite sporozoite functions

All protozoan parasites are lacking the pathway to synthesize purines de novo and therefore they depend on their host cells to provide purines. A number of highly conserved nucleoside transporter (NT) proteins are encoded in malaria parasite genomes, of which NT1 is characterized in Plasmodium falciparum and P. yoelii as a plasma membrane protein that is responsible for salvage of purines from the host, and NT2 is an endoplasmic membrane NT protein. Whereas NT3 is only present in primate malaria parasites, little is known about NT4, which is conserved in all malaria parasite species. Herein, we targeted NT4 gene for deletion in P. berghei. NT4 knockout parasites developed normally as blood stages, ookinetes and formed oocysts with sporozoites compared with wild-type (WT) P. berghei ANKA parasites. However, nt4(-) sporozoites showed significantly decreased egress from oocysts to hemolymph, significant reduction of colonization of the salivary glands, and complete abolishment of infection of the mammalian host by salivary gland and hemolymph sporozoites. Therefore, we identify NT4 as a NT that is important, not for replication and growth, but for sporozoite infectivity functions.

Phenotypic Analysis of Rodent Malaria Parasite Asexual and Sexual Blood Stages and Mosquito Stages

Recent advances in genetics and systems biology technologies have promoted our understanding of the biology of malaria parasites on the molecular level. However, effective malaria parasite targets for vaccine and chemotherapy development are still limited. This is largely due to the unavailability of relevant and practical in vivo infection models for human Plasmodium species, most notably for P. falciparum and P. vivax. Therefore, rodent malaria species have been extensively used as practical alternative in vivo models for malaria vaccine, drug targeting, immune response, and functional characterization studies of conserved Plasmodiumspp. genes. Indeed, rodent malaria models have proven to be invaluable, especially for exploring mosquito transmission and liver stage biology, and were indispensable for immunological studies. However, there are discrepancies in the methods used to evaluate the phenotypes of transgenic and wild-type asexual and sexual blood-stage parasites. Examples of these discrepancies are the choice of an intravenous vs. intraperitoneal infection of rodents with blood-stage parasites and the evaluation of male gamete exflagellation. Herein, we detail standardized experimental methods to evaluate the phenotypes of asexual and sexual blood stages in transgenic parasites expressing reporter-gene or wild-type rodent malaria parasite species. We also detail the methods to evaluate the phenotypes of malaria parasite mosquito stages (gametes, ookinetes, oocysts, and sporozoites) inside Anopheles mosquito vectors. These methods are detailed and simplified here for the lethal and non-lethal strains of P. berghei and P. yoelii but can also be applied with some adjustments to P. chabaudi and P. vinckei rodent malaria species.

Solitary splenic metastasis of squamous cell carcinoma of the uterine cervix: a case report and review of the literature

A 45-year-old patient presented with complaints of vaginal bleeding and pelvic pain. Fractioned probe curettage was performed and reported as Stage IIa, grade 3, squamous cell carcinoma of the uterine cervix. The patient underwent radical hysterectomy type III, bilateral salpingo-oophorectomy, omentectomy, appendectomy, and pelvic para-aortic lymph node dissection according to our clinical protocol. Adjuvant radiation therapy was planned. A splenic mass of 8 cm in diameter was revealed on computed tomography at the end of the third year of the disease-free follow-up period. Fine needle aspiration biopsy was performed and reported as metastatic carcinoma correlated to the previous cervical cancer. Debulking surgery was performed. The patient died one year after the second surgical operation. Spleen metastasis in patients with squamous cell carcinoma of the uterine cervix is exceedingly rare. Nonetheless we recommend screening of all intra-abdominal organs including the spleen as a rare metastastic site in follow-up examination protocols.

Spontaneous missed abortion caused by Ascaris lumbricoides

In this report, a case of spontaneous missed abortion caused by Ascaris lumbricoides is presented and data from the literature are reviewed, A 26-year-old pregnant woman was presented with abnormal genital bleeding, abdominal pain.

Oncocytic mucoepidermoid carcinoma of the parotid gland: report of a case with DNA ploidy analysis and review of the literature

A 44-year-old female presented with a painful mass in the left parotid gland. Histologic examination revealed the characteristic picture of oncocytic mucoepidermoid carcinoma (OMEC) composed mainly of sheets of oncocytic cells with uniform nuclei and eosinophilic cytoplasm, focally smaller epidermoid cells surrounding poorly formed glandular spaces, and a few cystic structures lined by well-differentiated mucous cells with intracytoplasmic mucin. Immunohistochemical staining with antimitochondrial antibody showed granular cytoplasmic positivity in oncocytic cells. The resulting histogram for DNA ploidy analysis was of diploid type. OMEC of the parotid gland is a recently described rare neoplasm. Only six cases have been previously reported in the literature. For an accurate approach in the management of patients, OMEC should be considered in the differential diagnosis of oncocytic lesions of the parotid gland, most of which are benign.

Biliary atresia splenic malformation syndrome--is it a result of embryonically midline rotational defects? A case report

The authors present a case of biliary atresia splenic malformation (BASM) syndrome in a 34-week gestational age boy who died shortly after birth. Autopsy results showed polysplenia, short pancreas, extrahepatic biliary atresia, heterotaxy of liver, tracheoesophageal and duodenal atresia, right lung hypoplasia, cardiac defects with tetralogy of Fallot, axial skeletal defects, and minor genitourinary disorders. Additional histopathologic findings were congenital hepatic fibrosis and bronchopulmonary dysplasia. The authors consider that the abnormalities of this case are possibly a unique combination. Midline defects, which are the most notable features of the presented case, may be closely related to pathogenesis of BASM syndrome.

Blastomatous tumor with teratoid features of nasal cavity: report of a case and review of the literature

A case of blastomatous tumor with teratoid features is presented. The polypoid mass was observed in the left nasal cavity of a 72-year-old man. Histologically, the lesion was composed of neuroepithelial cells with blastomatous appearance, cystic squamous nests filled with keratin materials, many mucous glands, complex tubular and glandular structures with edematous fibroblastic stroma. Sinonasal neoplasms including teratoid components and immature neuroepithelium are exceedingly rare. We suggest that the term 'immature teratoma' is more suitable than blastoma or blastomatous tumor when there is no carcinomatous or sarcomatous component besides the immature neuroepithelium and teratoid elements.