The distribution of cofilin and Dnase I in vivo

Actin is the principal component of the cytoskeleton, a structure that can be disassembled and reassem-bled in a matter of seconds in vivo. The state of assembly of actin in vivo is primarily regulated by one ormore actin binding proteins (ABPs). Typically, the actions of ABPs have been studied one by one, however,we propose that multiple ABPs, acting cooperatively, may be involved in the control of actin filament length.Cofilin and DNase I are two ABPs that have previously been demonstrated to form a ternary complex withactin in vitro. This is the first report to demonstrate their co-localisation in vivo, and differences in theirdistributions. Our observations strongly suggest a physiological role for higher order complexes of actin inregulation of cytoskeletal assembly during processes such as cell division.     

A new species of Cytisus Desf. (Fabaceae) from islands off the west coast of Galicia (north-west Iberian Peninsula)

A new species of the section Spartopsis Dumort. of the genus Cytisus Desf. (Fabaceae) is described. The new species, Cytisus insularis , is restricted to the western islands of Galicia (north-west Iberian Peninsula), where it principally colonizes cliffs. A possible recent hybrid origin for these populations is considered but rejected in view of the results of experimental tests of pollen viability and seed germination. Characters permitting discrimination from the most similar taxa are detailed, and possible relationships with the other species of the section are discussed.     

Resource density regulates the foraging investment in higher termite species

1. Resource density can regulate the area that animals use. At low resource density, there is a conflict in terms of balance between costs of foraging and benefits acquired. The foraging of the higher termite Nasutitermes aff. coxipoensis consists of searching throughout trails and a building galleries phase. 2. In this study, a manipulative field experiment was used to test the hypothesis that colonies of N. aff. coxipoensis forage towards a more profitable balance between the establishment of trails and gallery construction at low resource density. 3. The experiment was conducted in north‐eastern Brazil. Seven experimental plots were established with a continuous increase in resource density (sugarcane baits). Entire colonies of N. aff. coxipoensis were transplanted from their original sites to the experimental plot, totalling 35 nests. The number, branches and total length of trails and galleries were quantified. 4. The results show that N. aff. coxipoensis optimises its foraging output, intensifying the establishment of trails at the cost of gallery construction when resource density is low. The number of trails, the number of trail branches and the total length of trails decreased with increasing resource density. Interestingly, at low resource density, the search effort was concentrated on forming longer and a greater number of trails, a small proportion of which were converted into galleries. The opposite relationship was observed at high resource density. 5. These results suggest an optimisation of search efforts during foraging depending on resource density, a mechanism that may help researchers to understand the use of space by higher termite species.     

Callus tissue of Solanum tuberosum L. cultured in the presence of the pyrethroid deltamethrin

The effect of Decis (deltamethrin as active ingredient) on callus tissue of Solanum tuberosum L. cv. Désirée was studied. Decis is an agrochemical currently used on field grown potato plants to control the Colorado beetle, a potato pest. Deltamethrin added to the culture medium interferes with the behaviour of callus tissue. After 5 h of culture, the level of total proteins was higher in treated tissue than in the control, and SDS-PAGE showed that deltamethrin promoted the increase of some soluble proteins. After 24 h and 14 days of culture, the level of total proteins became similar in both treated and control material. This similarity between control and treated tissues, after 14 days of culture, occurred as a result of the treatment with deltamethrin which caused a decrease of soluble proteins, but an increase in insoluble proteins whereas the opposite was observed for control callus. SDS-PAGE of both soluble and insoluble proteins showed that only quantitative dissimilarities occurred. This longer treatment also increased the chlorophyll content. Ultrastructural study of the cells revealed that tissue callus cultured for 14 days in the presence of deltamethrin had plastids containing a more developed membranous system, with a higher number of grana and with more compartments than in control cells. Deltamethrin also promoted the abundance of vesicles associated with dictyosomes. This response of the callus tissue to Decis added to the callus medium parallels the behaviour of potato plants treated with this agrochemical under field conditions (Fidalgo, Santos & Salema, 1993).     

Ontogenesis of internal secretory cells in leaves of Lantana camara (Verbenaceae)

Internal secretory cells may be morphologically indistinguishable from their neighbours except for the presence of secreted material, or they may differ to such an extent that could be classified as secretory idioblasts. Several authors have reported the presence of glandular trichomes secreting essential oil in Verbenaceae, including Lantana . However, none have reported internal secretory cells. Anatomical and histochemical methods applied to Lantana camara leaves revealed the occurrence of internal secretory cells whose ontogenesis and chemical nature are described in this paper. According to leaf developmental analysis, L. camara secretory cells originated from the ground meristem, started to differentiate in the third node leaves, and were actively secreting in the fourth node leaves. The content of the secretory cells was of a lipidic nature, and a terpenoid essence of their secretion was also identified. Based upon differences in size and shape from neighbouring cells and on detection of nonvolatile terpenes, they were confirmed as true internal secretory idioblasts.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 148 , 427–431.