Phylloclade development in the Asparagaceae: an example of homoeosis

Phylloclades are traditionally defined as flattened, determinate, leaf-like stems primarily on the basis of their axillary position. However, because the literature is replete with controversy over the morphological interpretation of these organs, a study of phylloclade development in comparison with leaf and stem development was undertaken in four closely related species of the Asparagaceae: Ruscus aculeatus, Danae racemosa, Semele androgyna and Asparagus densiflorus. Results reveal a continuum in phylloclade development from very leaf-like forms, such as those of Danae, via the more intermediate types of Ruscus, to the gradually more shootlike forms of Semele and Asparagus. This continuum results from a differential expression of stem (or shoot) and leaf characteristics in an axillary position. When stem (or shoot) and leaf features are combined, as in the fertile phylloclade of Ruscus, an intermediate organ is formed. Phylloclades are a form of evolutionary novelty that exemplifies the phenomenon of homoeosis, which is the transference of features from one organ to another. Developmentally, this means that leaf features are expressed by the axillary meristem.     

Genetic variability among root voles (Microtus oeconomus) from different geographic regions: populations can be distinguished by DNA fingerprinting

Genetic variability among root voles (Microtus oeconomus [Pallas, 1776]) originating from two distantly separate regions of Norway (Valdres and Finnmark) was studied by DNA fingerprinting using the probes 33.15, 33.6 and M13. All three probes revealed polymorphic, although relatively simple, patterns. DNA fingerprint banding patterns were clearly diagnostic of the animals' region of origin. Notably, Valdres animals display a high molecular-weight cluster of bands not found in Finnmark, reflective of the isolation, and possibly an indication of separate colonization events, of the two groups. On the local level in Finnmark, bands associating with a specific trap site were observed in trappings on consecutive years. Comparisons of Finnmark animals taken at three trap sites at approximately 10 km intervals show a gradient of genetic similarity. Captive bred siblings were also compared, yielding average values significantly higher than those seen from same-site comparisons. We suggest that the sensitivity provided by DNA fingerprinting with multi-locus minisatellite probes is appropriate for population genetic studies in M. oeconomus. Also, because band-sharing correlates to spacing in M. oeconomus, we propose that DNA fingerprinting may be used to study dispersal, recruitment and other population processes in this and possibly other rodent species.     

Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism

Aescin in phosphate buffer reduced, to some extent, the production of ¹⁴CO₂ from uniformly labelled glucose in mycelia of Ophiobolus graminis and Neurospora crassa, whereas aescin in succinate buffer had no effect. The enzymatic hydrolysis of sucrose was, however, severely affected, no production of ¹⁴CO₂ from labelled sucrose being found after treatment of mycelia of O. graminis with 100 mg/l of aescin and N. crassa with 300 mg/l for 90 and 300 min, respectively. In Aspergillus niger the production of ¹⁴CO₂ from glucose or sucrose was not affected. The ATPase in whole cells and isolated plasma membranes was not inhibited by the aescin treatment, on the contrary, the ATPase in whole cells of N. crassa was somewhat stimulated.     

Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism 6. The Effect of Aescin on Fungi with Reduced Sterol Contents

The amount of sterols in the mycelia of Ophiobolus gra-minis and Neurospora crassa was reduced by cultivating the fungi in the presence of inhibitors of the sterol synthesis. The hypocholesteraemic compounds β-diethylaminoethyl-(2.2-diphenylpentanoate) hydrochloride (SK & F 525-A) and 2.2-diphenyl -1 -(β- dimethylaminoethoxy)pentane hydrocchloride (SK & F 3301-A) were particularly effective in reducing the sterol contents. At the same time, the growth yield was reduced. Aescin had a reduced inhibitory effect on the radial growth of the mycelia with decreased sterol contents, the leakage of UV-absorbing substances and K⁺ ions was reduced to small amounts, and the inhibition of the K⁺ uptake was nullified.     

Attachment forces of pea aphids (Acyrthosiphon pisum) on different legume species

1. Sympatric populations of insects adapted to different host plants are good model systems not only to study how they adapt to the chemistry of their food plant, but also to investigate whether morphological modifications evolved enabling them to live successfully on a certain plant species. 2. The pea aphid, Acyrthosiphon pisum (Harris) encompasses at least 11 genetically distinct sympatric host races, each showing a preference for a certain legume species. The leaflet surfaces of these legumes differ considerably in their wax coverage. 3. It was investigated whether the attachment structures of three pea aphid genotypes from different host races are adapted to the different surface properties of their host plants and whether they show differences in their attachment ability on the respective host and non‐host plants. 4. The surface morphology of plants and aphid tarsi was examined using SEM (scanning electron microscopy). The ability of the aphids to walk on specific surfaces was tested using traction force measurements. 5. The presence of wax blooms on the leaflets lowers the aphids' attachment ability considerably and diminishes their subsequent attachment on ‘neutral’ surfaces like glass. The pea aphid host races differ in their ability to walk on certain surfaces. However, the genotype from the adapted aphid host race was not necessarily the one with the best walking performance on their host plant. All aphids, regardless of the original host plant, were most efficient on the neutral control surface glass. The general host plant Vicia faba was the plant with the most favourable surface for all aphid host races.     

Revision of the Eastern Asian genera Ambrostoma Motschulsky and Parambrostoma Chen (Coleoptera: Chrysomelidae: Chrysomelinae)

The leaf beetle genera Ambrostoma Motschulsky, 1860 and Parambrostoma Chen, 1934 have been revised and now include 14 species. Two new species from Nepal are described, Parambrostoma kippenbergi sp.n. and P. medvedevi sp.n. Three new synonymies are established: Ambrostoma rugosopunctatum Chen = Ambrostoma (Parambrostoma) laosensis Kimoto & Gressitt, syn.n. , Ambrostoma rugosopunctatum Chen = Ambrostoma daccordii Medvedev, syn.n., Ambrostoma fortunei (Baly) = Ambrostoma quadriimpressum chusanica Gruev, syn.n . One species was transferred from Chrysomela Linnaeus to Ambrostoma Motschulsky: A. superbum (Thunberg), comb.n . All the species now included are described and illustrated. Microcomputer tomography was applied for the first time in a study on chrysomelid beetles. A cladistic analysis based on morphological characters of adults was conducted to reconstruct the intergeneric and interspecific phylogeny of Ambrostoma and Parambrostoma. The results show that the monophyly of both genera is well supported. Ambrostoma is widespread in East Asia, whereas Parambrostoma is restricted to the southern slope of the Himalayas, where a relatively recent and modest speciation took place.