Seaweed attachment to bedrock: biophysical evidence for a new geophycology paradigm.

Seaweeds are amongst the most obvious and ecologically important components of rocky shore communities worldwide but until now little has been known about the processes involved in their attachment. This multidisciplinary study investigated for the first time the interactions between marine macroalgal holdfasts and their underlying substrata, requiring the development of specialized sample preparation techniques to maintain the structural integrity of the holdfast-bedrock interface. Transmitted plane polarized light microscopy, scanning electron microscopy with energy dispersive spectroscopy and structured light illumination microscopy were used in the examination of the interface between Ascophyllum nodosum (Fucales, Heterokontophyta) and crustose red algae Lithothamnion sp. (Corallinales, Rhodophyta) on granite and limestone substrates. The new evidence presented here represents a paradigm shift in the way we view seaweed attachment because results show that the holdfasts exploit the physical characteristics of the rock-forming minerals in order to penetrate the bedrock and thus facilitate the attachment process. Mineral cleavage planes together with intercrystalline and intracrystalline boundaries and fractures provide penetration pathways for the holdfast tissue. This process causes disaggregation of rock-forming minerals to depths <10 mm and therefore assists in the bioerosion of coastal bedrock. It is concluded that seaweeds are able to cause weathering of natural rock and the term 'geophycology' is introduced to describe seaweed-bedrock interactions, including seaweed-induced weathering.

A convenient method for 3-pyrroline synthesis.

[reaction: see text]. The synthesis of a range of 3-pyrrolines has been achieved from primary amine starting materials using a two-step alkylation/alkylidene carbene CH-insertion reaction sequence. We have shown that insertion into a range of CH-bond types is possible, and the formation of nitrogen-bearing quaternary stereocenters is a relatively facile process. The insertion reaction occurs with >95% retention of stereochemistry, but the presence of protecting groups on nitrogen is generally deleterious to the cyclization process.

The use of community nurses for home peritoneal dialysis: is it cost-effective?

In the late 1970s, continuous ambulatory peritoneal dialysis was first introduced as a mode of treatment for patients with end-stage renal disease. Since that time many patients, themselves or with the help of family members, have routinely performed the therapy at home. There are now 2935 home peritoneal dialysis patients in Canada (36% of the total dialysis population). Today, however, the average patient on dialysis is likely to be older and have other complicating illnesses; moreover, patients may live alone, or have family members who are working. Over the past three years, through the use of innovative assistive devices and strong educational links with community nursing agencies, we have been able to manage peritoneal dialysis patients with complex needs in the home. We performed a retrospective analysis of 18 patients, with severe comorbid conditions, who were managed in the home with the help of community nurses. We will show that this is an economic, efficient, and effective method of caring for home dialysis patients with severe disabilities. Home care agencies need our support so that they can continue to help us manage the complex peritoneal dialysis patient in the 1990s.