A key role for floral scent in a wasp-pollination system in Eucomis (Hyacinthaceae).

BACKGROUND AND AIMS: Floral scent may play a key role as a selective attractant in plants with specialized pollination systems, particularly in cases where floral morphology does not function as a filter of flower visitors. The pollination systems of two African Eucomis species (E. autumnalis and E. comosa) were investigated and a test was made of the importance of scent and visual cues as floral attractants. METHODS AND KEY RESULTS: Visitor observations showed that E. autumnalis and E. comosa are visited primarily by pompilid wasps belonging to the genus Hemipepsis. These wasps carry considerably more Eucomis pollen and are more active on flowers than other visiting insects. Furthermore, experiments involving virgin flowers showed that these insects are capable of depositing pollen on the stigmas of E. autumnalis, and, in the case of E. comosa, pollen deposited during a single visit is sufficient to result in seed set. Experimental hand-pollinations showed that both species are genetically self-incompatible and thus reliant on pollinators for seed set. Choice experiments conducted in the field and laboratory with E. autumnalis demonstrated that pompilid wasps are attracted to flowers primarily by scent and not visual cues. Measurement of spectral reflectance by flower petals showed that flowers are cryptically coloured and are similar to the background vegetation. Analysis of headspace scent samples using coupled gas chromatography-mass spectrometry revealed that E. autumnalis and E. comosa scents are dominated by aromatic and monoterpene compounds. One hundred and four volatile compounds were identified in the floral scent of E. autumnalis and 83 in the floral scent of E. comosa, of which 57 were common to the scents of both species. CONCLUSIONS: This study showed that E. autumnalis and E. comosa are specialized for pollination by pompilid wasps in the genus Hemipepsis and achieve specialization through cryptic colouring and the use of scent as a selective floral attractant.

Type VIII collagen: heterotrimeric chain association.

Two chains, alpha1(VIII) and alpha2(VIII), have been described for type VIII collagen. Early work suggested that these chains were present in a 2:1 ratio, although recent work has shown that homotrimers can form and predominate in some tissues. In order to address the question of whether the alpha1(VIII) and alpha2(VIII) chains could co-polymerise we made a shortened alpha1(VIII) chain and expressed this with full length alpha2(VIII) chain in an in vitro translation system supplemented with semi-permeabilised cells. Heterotrimers containing either two or one alpha2(VIII) were evident. Interestingly, a point mutation in the NC1 domain of the alpha1(VIII) chain abrogated trimer formation. In addition we were able to demonstrate chain association of the alpha1(X) chain of type X collagen with the shortened alpha1(VIII) chain. Variations in chain association were seen when altered ratios of message were used. These results demonstrate the importance of the NC1 domain in chain association and suggest that gene expression regulates the composition and function of type VIII collagen by varying chain composition.

An 'affinity' method for preparing polypeptides enriched in the collagen-associated Ehrlich chromogen.

The collagen-associated compound which reacts at room temperature with acid dimethylaminobenzaldehyde (Ehrlichs reagent) also reacts in acid with aryl-diazonium reagents. We have developed a convenient method for isolating polypeptides associated with the Ehrlich chromogen from collagen digests utilizing diazotized arylamino-cellulose supports. These peptides, in which the Ehrlich chromogen is 'labeled' with yellow diazo color, constitute less than 0.5% of the collagen, and have amino acid patterns similar to those around the cross link regions. The chromogen is not identical with pyridinoline, also thought to be a polyvalent cross link.

Evaluation of a small-scale method for the extraction of the K88 antigen from enterotoxigenic Escherichia coli.

A small-scale method for the extraction of the K88 major fimbrial subunit from enterotoxigenic Escherichia coli (ETEC) based on heat extraction has been developed. Variation in the buffer composition, time and temperature of extraction had negligible effect on the subsequent SDS-PAGE profile. There was, however, a correlation between the pH of the extraction buffer and the ensuing amount of K88 released. Reduction of the pH from 7 to 4 reduced by six-fold the amount of K88 released from the cells. We suggest that the relative stability of the K88 fimbriae at acid pH may influence the site of infection by ETEC in the intestine.

An intervention study with husband and wife carers of older people with a psychiatric illness.

BACKGROUND: Individual packages of care were devised for spouses of older people with psychiatric illness. METHOD: Randomised controlled trial with blind follow up. Intervention group members were offered multidisciplinary packages while controls received no extra help. Both groups were reassessed 12-14 weeks later. The initial control group then received intervention; both were reassessed at 24-28 weeks. RESULTS: Although no significant differences emerged in group mean scores for affective illness or social difficulties, carers who were mentally ill at outset improved significantly. CONCLUSION: Interventions targeted at caregiving spouses with affective disorder are acceptable and efficacious. LIMITATION: It was impossible to compare treatment with no treatment.

The squalestatins, novel inhibitors of squalene synthase produced by a species of Phoma. I. Taxonomy, fermentation, isolation, physico-chemical properties and biological activity.

During the screening of fungi for inhibitors of squalene synthase, Phoma sp. C2932 was found to produce three structurally related novel inhibitors. These compounds, designated the squalestatins, exhibited potent activity against both mammalian (rat liver) and fungal (Candida albicans) squalene synthase. Furthermore, they also had broad spectrum in vitro antifungal activity.

Isolation and characterisation of an antifungal antibiotic (GR135402) with protein synthesis inhibition.

A novel antifungal antibiotic GR135402 has been isolated from a fermentation broth of Graphium putredinis which inhibited protein synthesis in Candida albicans but not rabbit reticulocytes. The spectrum of activity included C. albicans and Cryptococcus neoformans but not some other Candida species or Aspergillus species. Therapeutic efficacy in a mouse model of systemic candidosis was attained following parenteral dosing.

Will the minimum become an optimum? PREPP: mandatory study leave for nurses.

This, the first in a series of articles on issues surrounding PREPP, looks at the recommendation that nurses complete a minimum of five days study leave every three years. The series aims to raise issues to help practitioners focus their thoughts before responding to the UKCC.

Equipment for moving and handling patients.

Choosing the correct equipment for moving and handling patients is essential to prevent injuries among health-care staff and patients' carers. It is vital, however, that a thorough needs and risk assessment is undertaken before equipment is purchased.