Cytogenetic relationships among Citrullus species in comparison with some genera of the tribe Benincaseae (Cucurbitaceae) as inferred from rDNA distribution patterns.

BACKGROUND: Comparative mapping of 5S and 45S rDNA by fluorescent in situ hybridization (FISH) technique is an excellent tool to determine cytogenetic relationships among closely related species. RESULTS: In this study, the number and position of 5S and 45S rDNA loci in all Citrullus species and subspecies were determined. The cultivated watermelon (C. lanatus subsp. vulgaris), C. lanatus subsp. mucosospermus, C. colocynthis and C. naudinianus (or Acanthosicyos naudinianus) had two 45S rDNA loci and one 5S rDNA locus which was located syntenic to one of the 45S rDNA loci. C. ecirrhosus and C. lanatus subsp. lanatus had one 45S rDNA locus and two 5S rDNA loci, each located on a different chromosome. C. rehmii had one 5S and one 45S rDNA locus positioned on different chromosomes. The distribution of 5S and 45S rDNA in several species belonging to other genera in Benincaseae tribe was also investigated. The distribution pattern of rDNAs showed a great difference among these species. CONCLUSIONS: The present study confirmed evolutionary closeness among cultivated watermelon (C. lanatus subsp. vulgaris), C. lanatus subsp. mucosospermus and C. colocynthis. Our result also supported that C. lanatus subsp. lanatus was not a wild form of the cultivated watermelon instead was a separate crop species. In addition, present cytogenetic analysis suggested that A. naudinianus was more closely related to Cucumis than to Citrullus or Acanthosicyos, but with a unique position and may be a link bridge between the Citrullus and the Cucumis.

Morphine preconditioning confers cardioprotection in doxorubicin-induced failing rat hearts via ERK/GSK-3ß pathway independent of PI3K/Akt.

Preconditioning against myocardial ischemia-reperfusion (I/R) injury can be suppressed in some pathological conditions. This study was designed to investigate whether morphine preconditioning (MPC) exerts cardioprotection in doxorubicin (DOX)-induced heart failure in rats and the mechanisms involved. Phosphatidylinositol-3 kinase/protein kinase B (PI3K/Akt), extracellular signal-regulated kinase (ERK) and glycogen synthase kinase (GSK)-3ß pathways were examined. Normal and DOX-induced failing rat hearts were subjected to I/R injury using a Langendorff perfusion system with or without MPC or ischemic preconditioning (IPC). The PI3K inhibitor (wortmannin) or ERK inhibitor (PD98059) was infused before MPC. In normal hearts, both MPC and IPC significantly reduced infarct size and the rise in lactate dehydrogenase (LDH) level caused by I/R injury. Pretreatment with wortmannin or PD98059 abrogated the protective effects of MPC and suppressed the phosphorylation of Akt, ERK and GSK-3ß. In failing rat hearts, however, MPC retained its cardioprotection while IPC did not. This protective effect was abolished by PD98059 but not wortmannin. MPC increased the level of p-ERK rather than p-Akt. The phosphorylation of GSK-3ß induced by MPC was reversed by PD98059 only. IPC did not elevate the expression of p-ERK, p-Akt and p-GSK-3ß in failing rat hearts. We conclude that MPC is cardioprotective in rats with DOX-induced heart failure while IPC is not. The effect of MPC appears to be mediated via the ERK/GSK-3ß pathway independent of PI3K/Akt.