Germline organization in Strongyloides nematodes reveals alternative differentiation and regulation mechanisms

Nematodes of the genus Strongyloides are important parasites of vertebrates including man. Currently, little is known about their germline organization or reproductive biology and how this influences their parasitic life strategies. Here, we analyze the structure of the germline in several Strongyloides and closely related species and uncover striking differences in the development, germline organization, and fluid dynamics compared to the model organism Caenorhabditis elegans. With a focus on Strongyloides ratti, we reveal that the proliferation of germ cells is restricted to early and mid-larval development, thus limiting the number of progeny. In order to understand key germline events (specifically germ cell progression and the transcriptional status of the germline), we monitored conserved histone modifications, in particular H3Pser10 and H3K4me3. The evolutionary significance of these events is subsequently highlighted through comparisons with six other nematode species, revealing underlying complexities and variations in the development of the germline among nematodes.

Isolation of Strongyloides venezuelensis from Rattus norvegicus in Kagoshima Prefecture

On 30 August 1984, Strongyloides sp. specimens were isolated from a rat (Rattus norvegicus) trapped at a pig farm in Kiire-cho, Ibusuki-gun, Kagoshima Prefecture. Both anterior and posterior ovaries of parasitic female were spirally coiled. The means of body length and width, esophagus length, and the distances from mouth to vulva and from anus to tail end were 2,493, 34.5, 719.8, 1,682.8 and 54.4 microns respectively. Filariform larvae measured 544.2, 15.6 and 238.5 microns in the means of body length and width, and esophagus length respectively. These measurements of the present Strongyloides species agreed with those described for S. venezuelensis. Infection rate by oral administration of larvae was low, while subcutaneous inoculation and percutaneous exposure to larvae produced high infection rate to rats which discharged many egg in the feces. The present parasite has been passaged through rats (SD strain) in these 8 years. This isolate is designated as the Kagoshima strain of S. venezuelensis.

Cytologic diagnosis of lung cancer. Principles and problems

This diagnostic seminar discusses the current status of the principles and problems of cytology as it is applied to the diagnosis of lung cancer. This discussion is divided into four major parts. Part I presents a discussion of cytopreparatory techniques and cytology of the lung in the absence of cancer. The cytology of benign proliferations which may mimic cancer is emphasized. The role of cytology in the diagnosis of pulmonary infectious organisms is noted. Part II discusses lung cancer as manifested in specimens of sputum, bronchial washings, and bronchial brushings. Part III presents some data on the validity of cytology with respect to role of specimen number and type in lung cancer diagnosis and cell typing in lung cancer. The continued usefulness and importance of multiple specimens of sputum for lung cancer diagnosis are documented. Part IV presents a brief synopsis of fine needle aspiration biopsy of lung cancer.

Strongyloides stercoralis in routine Papanicolaou-stained sputum smears

Three cases are reported in which the initial detection of unsuspected Strongyloides stercoralis infestation was made on Papanicolaou-stained smears of sputum submitted for routine cytopathology. All cases were subsequently confirmed by the examination of stool specimens. A common factor in the three cases was long-term treatment with corticosteroids for chronic respiratory disease. All three patients responded to treatment with antihelminthics. The significance of this parasite is discussed, and its appearance in Papanicolaou-stained smears is described and illustrated.

Cytology, reproduction, and sex determination of Strongyloides ransomi and S. papillosus

Parasitic females of Strongyloides ransomi and Strongyloides papillosus have 4 chromosomes and reproduce exclusively by mitotic (apomictic) parthenogenesis. The free-living generation includes females and males. The females have 2 pairs of chromosomes of unequal size and reproduce by meiotic parthenogenesis following obligatory pseudofertilization (gynogenesis). The males undergo spermatogenesis by the regular meiotic process and have the same chromosomal complement as the females. During prophase I, however, a portion of one homologue of the large bivalent breaks free and subsequently is diminished, as in S. ransomi, or it rejoins the original homologue, as in S. papillosus. This behavior of meiotic chromosomes during spermatogenesis suggests that the karyotype of these species has evolved from a karyotype analogous to that of Strongyloides ratti with 2 pairs of autosomes and a pair of X chromosomes, following fusion of the X chromosome with an autosome and the formation of a Neo-X and a Neo-Y chromosome. The female karyotype of S. ransomi and S. papillosus thus may be 2A + 2 Neo-X. The males are phenotypic males and have the same karyotype as the females, but their functional karyotype may be 2A + Neo-X + Neo-Y.