Mitochondrial dynamics and mitophagy in the 6-hydroxydopamine preclinical model of Parkinson's disease.

We discuss the participation of mitochondrial dynamics and autophagy in the 6-hydroxidopamine-induced Parkinson's disease model. The regulation of dynamic mitochondrial processes such as fusion, fission, and mitophagy has been shown to be an important mechanism controlling cellular fate. An imbalance in mitochondrial dynamics may contribute to both familial and sporadic neurodegenerative diseases including Parkinson's disease. With special attention we address the role of second messengers as the role of reactive oxygen species and the mitochondria as the headquarters of cell death. The role of molecular signaling pathways, for instance, the participation of Dynamin-related protein 1(Drp1), will also be addressed. Furthermore evidence demonstrates the therapeutic potential of small-molecule inhibitors of mitochondrial division in Parkinson's disease. For instance, pharmacological inhibition of Drp1, through treatment with the mitochondrial division inhibitor-1, results in the abrogation of mitochondrial fission and in a decrease of the number of autophagic cells. Deciphering the signaling cascades that underlie mitophagy triggered by 6-OHDA, as well as the mechanisms that determine the selectivity of this response, will help to better understand this process and may have impact on human treatment strategies of Parkinson's disease.

Evolution of octopod sperm I: comparison of nuclear morphogenesis in Eledone and Octopus.

Morphogenesis of the Eledone cirrhosa sperm nucleus, as studied by electron microscopic techniques, is compared with that of Octopus vulgaris. Both species of cephalopods belong to the family Octopodidae. The results indicate that extensive nuclear helicoidization during E. cirrhosa spermiogenesis is brought about by modifications of the function of structural components already present in the late steps of O. vulgaris spermiogenesis. In particular, changes in the regulation of perinuclear microtubule contraction in E. cirrhosa spermatids, as well as a decrease in basicity of protamines, promote nuclear helicoidization. Disulphide bond formation between protamine molecules fixes the completely helicoidal shape of the nucleus in mature sperm of E. cirrhosa.

Evolution of octopod sperm II: comparison of acrosomal morphogenesis in Eledone and Octopus.

The first stages of acrosome development during Eledone cirrhosa spermiogenesis are similar to that in Octopus vulgaris, and comprise the initial elongation of both organelles. However, the acrosome in E. cirrhosa does not continue its elongation as it does in O. vulgaris. Instead, its length remains fixed and it undergoes a process of helicoidization that includes the entire organelle. In each spermatid, helicoidization of the E. cirrhosa acrosome occurs simultaneously with helicoidization of the nucleus. The acrosome is associated with special structures that probably are involved in the helical torsion of the organelle. We propose a hypothesis to explain the evolutionary relationship between the acrosomes of O. vulgaris and E. cirrhosa, particularly as it is influenced by nucleomorphogenesis and microtubular contraction.