A new genus and species of the Syllidae (Annelida, Polychaeta) from south India

A syllid species new to science is described from intertidal sandy sediments on the cast coast of India, for which a new genus is erected: Psammosyllis aliceae gen. et sp.n. Incorporation into either the Eusyllinae or the Exogoninae is unresolved, because it possesses characters of both of these poorly defined subfamilies.     

Sinohesione genitaliphora gen. et sp. n. (Polychaeta, Hesionidae), an interstitial annelid with unique dimorphous external genital organs

A new hesionid. Sinohesione genitaliphora gen. et sp. n., is described from intertidal sandy sediments of Hainan Island, China. It differs from hitherto known hesionids by the presence of external genital organs in both sexes. In the males there is one pair of sae-like appendages, each bearing a tube-shaped penis, on chaetiger 10. In the females the paired sae-shaped organs are situated on chaetiger 12. Reconstructions of semi- and ultrathin sections show that a long, heavily coiled sperm duct opens at the tip of each penis. The duct opens with a ciliated funnel into a seminal vesicle in chaetiger 9. Prominent gland cells surround the sperm duct for the most part. The female genital organs each have two openings; one of which leads to a blind ending seminal receptacle. The other is the external pore of a ciliated oviduct that originates as an open funnel in the coelom of chaetiger 10. The functional and phylogenetic significance of these structures is discussed.     

Osmocytosis and Vacuolar Fragmentation in Guard Cell Protoplasts: Their Relevance to Osmotically-lnduced Volume Changes in Guard Cells

Guard cell protoplasts were prepared from young leaves of peaplants. Under hypertonic conditions they shrink and large numbersof endocytotic (‘osmocytotic’) vacuoles are formedby invagination of the plasma membrane. In thin section theseare indistinguishable from other small vacuoles (‘mini-vacuoles’)which are formed by fragmentation of the large central vacuole.However, the two types of vacuole can be individually recognizedby labelling the central vacuole with neutral red and by performingthe osmotic shrinkage with fluorochromes such as Lucifer Yellow-CHor Cascade Blue present in the extracellular medium. Osmocytoticvacuoles do not fuse with the plasma membrane nor with the mini-vacuolesduring a subsequent swelling phase. After several hours, osmocytosedLucifer Yellow gradually leaks out of the endocytotic vacuoleswhen protoplasts are returned to hypotonic conditions. Thisleakage is not prevented by probenecid at concentrations (20–50mmol m^–3) which do not give rise to pathological changesin protoplast ultrastructure. In order to determine the relevanceof these observations to the situation in planta, intact guardcells in epidermal strips were first allowed to accumulate neutralred in their vacuoles and then subjected to osmotic shrinkagein the presence of external Lucifer Yellow. Osmocytotic vacuoleswere not formed, although the production of mini-vacuoles wasfrequently observed. Key words: Guard cell protoplasts, fluid phase markers, Pisum sativum, probenecid, osmocytosis, shrinkage-swelling cycles     

Role of Copper Binding, Absorption, and Translocation in Copper Tolerance of Agrostis gigantea Roth

The capacity of roots to accumulate and retain copper was examinedin two clones of Agrostis gigantea which differ in their toleranceto excess copper. Root elongation growth in the non-tolerantclone was completely inhibited by 16 mmol m^–3 Cu whereas40 mmol m^–3 was required for inhibition in the tolerantclone. The amount of readily exchangeable copper was greaterin roots of the tolerant clone than in the non-tolerant clone.The higher capacity for binding copper did not prevent the entryof copper into the cells of intact or excised roots of the tolerantclone. Roots of both clones contained similar amounts of copperafter removal of the readily exchangeable fraction. More copperwas translocated to the shoots of the tolerant than the non-tolerantclone. The explanation of copper tolerance in Agrostis giganteamust be sought in areas other than those of differences in grosscopper absorption and retention by roots.