An experimental infection model for the heteroecious spiruid nematode Tetrameres americana (Cram 1927) was developed. The cockroach Blattella germanica (L.) and the locust Locusta migratoria (L.) were found to serve as intermediate hosts for the parasite. T. americana larvae developed to full maturity in these intermediate hosts and were infective to young Lohman Brown chickens after 32 days in the cockroach and 28 days in the locust. The maximum length of the larvae was reached in the insects at 28-30 degrees C after 10-15 days, at which time the larvae measured up to 2.2 mm. The parasite did not develop in the cockroach Periplaneta americana (L.), the woodlouse Oniscus asellus (L.), or the pupal stage of the giant mealworm Zophobas morio (Fabricius). Trials in which chickens were infected directly without an intermediate host failed. Infection of 24 chickens with a dosage of 100 larvae was followed by weekly post-mortems until day 48 post-infection (p.i.) and used to describe the development of T. americana. The average establishment rate (%) and the average worm burden varied from 16.5 to 30.8. The total numbers of parasites recovered ranged from 9 to 40. During mating, in the first 2 weeks p.i. females and males were equally abundant, whereas from day 20 p.i. twice as many females were recovered. From day 13 p.i. the females average length fluctuated between 2.6 and 3.7 mm, whereas they reached their maximum width of 2.4 mm on day 48 p.i. Males reached their full length after 27 days p.i. and measured up to 6.7 mm.

Collapsin response mediator proteins (CRMPs) have been implicated in signaling of axonal guidance, including semaphorins. We have previously identified a unique member of this gene family, CRMP-associated molecule CRAM (CRMP-5), which is phylogenetically divergent from the other four CRMPs. In this study, we have examined the distribution and function of CRAM in developing neurons. Immunohistochemical analysis showed accumulation of CRAM in the filopodia of growth cones. Experiments using cytochalasin D indicated that filopodial localization of CRAM was independent of filamentous actin. Overexpression of CRAM in neuronal cells significantly promoted filopodial growth and led to the formation of supernumerary growth cones, which acquired resistance to semaphorin-3A stimulation. Finally, knockdown of CRAM by using RNA interference blocked filopodial formation and revealed an aberrant morphology of growth cones. We propose that CRAM regulates filopodial dynamics and growth cone development, thereby restricting the response of growth cone to repulsive guidance cues.

Myriadenolide is a diterpene that we have recently isolated from the extract of Alomia myriadenia (Asteraceae). Here we show for the first time that myriadenolide has caspase-dependent cytotoxic activity against human leukemia cells from both lymphocytic (Jurkat) and monocytic (THP-1) lineages, because preincubation of Jurkat or THP-1 cells with the broad-spectrum caspase inhibitor z-VAD-fmk completely abrogated cell death. Moreover, the mitochondrial pathway is implicated as mitochondrial depolarization and caspase-9 and caspase-3 activation were observed. Interestingly, caspase-8 and cleavage of the proapoptotic member of the Bcl-2 family BID was also observed during apoptosis induced by myriadenolide, suggesting a role for the caspase-8/BID pathway. However, interference with Fas or TNFR1 signaling did not interfere with apoptosis in our experimental system. Furthermore, pretreatment of cells with the caspase-3 inhibitor DEVD-fmk completely blocked the activation of caspase-8, suggesting that the activation of the caspase-8/BID pathway is part of an amplification loop initiated by caspase-3. Taken together, our results indicate myriadenolide as a novel candidate for the treatment of hematological malignancies.

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