Acanthocephalans are a small group of obligate endoparasites. They and rotifers are recently placed in a group called Syndermata. However, phylogenetic relationships within classes of acanthocephalans, and between them and rotifers, have not been well resolved, possibly due to the lack of molecular data suitable for such analysis. In this study, the mitochondrial (mt) genome was sequenced from Pallisentis celatus (Van Cleave, 1928), an acanthocephalan in the class Eoacanthocephala, an intestinal parasite of rice-field eel, Monopterus albus (Zuiew, 1793), in China. The complete mt genome sequence of P. celatus is 13855 bp long, containing 36 genes including 12 protein‑coding genes, 22 transfer RNAs (tRNAs) and 2 ribosomal RNAs (rRNAs) as reported for other acanthocephalan species. All genes are encoded on the same strand and in the same direction. Phylogenetic analysis indicated that acanthocephalans are closely related with a clade containing bdelloids, which then correlates with the clade containing monogononts. The class Eoacanthocephala, containing P. celatus and Paratenuisentis ambiguus (Van Cleave, 1921) was closely related to the Palaeacanthocephala. It is thus indicated that acanthocephalans may be just clustered among groups of rotifers. However, the resolving of phylogenetic relationship among all classes of acanthocephalans and between them and rotifers may require further sampling and more molecular data.
Rye (Secale cereale L.) plants were treated with an ethylene releaser ethephon (2-chloroethylphosphonic acid) in concentration of 4×10-2 M. We studied electron microscopically, if and how chloroplasts interact with well-documented sites of ethylene production/binding, i.e., with endoplasmic reticulum, dictyosomes, mitochondria, plasma membrane, and tonoplast. During the sharp increase of ethylene synthesis in mesophyll cells of rye leaves, the direct local continguity of chloroplast envelope or envelope protrusions with the above mentioned cell compartments was typical. Moreover, a large number and diversity of versatile chloroplast-dictyosome associations were conspicuous, in which both the chloroplast and each cisterna of dictyosome were capable to exo/endocytosis. The dictyosomes were directed towards the chloroplasts, plasma membrane, or tonoplast both with cis-face, trans-face, or with the rim, they could change their direction or shut up the trans-face, developing simultaneously several flexible chains of vesicular dispatches among chloroplasts and some other cell compartments. This reflects interaction of protein/ethylene producing, photosynthesising, DNA containing compartments, and regulated action of lysosomal system. Structural contacts and vesicular transport among compartments of symplastic system equalises concentrations of H+, Ca2+, etc. ions, as well as provide connection with an apoplast. We propose that ethylene functions in plant mesophyll cells are both as intra/intercellular signalling substance and as phytohormone that regulates gene expression in nuclei, chloroplasts, and mitochondria in a complicated synapse-like process and causes programmed death of leaves of the main stalks of rye for the sake of promoted growth of side shoots. and T. Selga, M. Selga.