Notes on African species of the genus Anisopappus Hook. & Arn. (Asteraceae)

Two new species of the genus Anisopappus Hook. & Arn. (Asteraceae) are described: A. athanasioides Paiva & Ortiz, from Angola, and A. pseudopinnaididus Ortiz & Paiva, from Namibia. The morphological variability of the A. chinensis-A. africanus complex is studied and two new combinations are proposed: A. chinensis subsp. africanus (Hook, fil.) Ortiz & Paiva and A. chinensis subsp. lobatus (Wild) Ortiz & Paiva.     

Alkylation Treatment of the Mexican Axolotl: An Approach to the Isolation of New Mutations

SYNOPSIS. Most of the known mutants of the axolotl were uncoveredby R. R. Humphrey through inbreeding laboratory stock or wildanimals imported from Mexico. All are spontaneous in origin.We believe that chemical mutagenesis may be useful for increasingboth the frequency and variety of new mutations. For our experiments,we have chosen the alkylating agent ethyl methanesulfonate (EMS),because its mode of action is reasonably well understood. Thoughwe were unable to establish a lethal dose of EMS by intraperitonealinjection, we were successful when we administered the compounddirectly in the water. In the weeks immediately after treatment,females administered sublethal doses did not ovulate, exceptin response to large injections of follicle stimulating hormone.Recovery took several months. Treated males showed more normalperformance, in terms of courtship and the number of spermatophoresproduced. At low doses, and short intervals after treatment,embryos from spawnings with treated males survived nearly aswell as controls. Survival reached a minimum about a month afterthe male had been treated, then improved again. This depressionand recovery may be correlated with the stage of sperm maturationat the time of treatment. Treatment of mature sperm from spermatophoresaffected only their ability to fertilize eggs in an artificialinsemination; fertile eggs developed normally. The most promisingprocedure would, therefore, seem to be treatment of the male.Following mutagenesis, we propose that gynogenesis be used toaid in the rapid identification of new recessive mutations.     

Investigations of Phlebotomus perniciosus sand flies in rural Spain reveal strongly aggregated and gender‐specific spatial distributions and advocate use of light‐attraction traps

The spatial and temporal distribution of Phlebotomus perniciosus (Diptera: Psychodidae) (Newstead, 1911), the sand fly vector of pathogens of public and animal health importance, was investigated in a high sand fly density rural area in Spain using light‐attraction and sticky‐interception traps. Traps were placed inside animal buildings and outside at increasing distance from animals. A total of 8506 sand flies were collected, 87% with light traps. Species frequency differed between trap types. The abundance of P. perniciosus decreased exponentially with increasing distance to animals and, while females were most common in the animal enclosure, males predominated in adjoining storage places. Increasing CO₂ concentration had an additional positive effect on female abundance only. Both male and female density increased with rising temperature, and there was some indication that females were more active than males at higher relative humidity. The study confirms that P. perniciosus aggregates around animal premises, although male and female distributions differ and should be analysed separately to account for biological and behavioural differences. This provides further evidence that light traps offer an accurate estimation of the relative spatial and temporal abundance of P. perniciosus, conferring an added value for the study of this species and the risk of pathogen transmission.     

A Novel Opioid Mechanism Seems to Modulate Phagocytosis in Tetrahymena

ABSTRACT. We have previously reported that a β-endorphin-like substance inhibits phagocytosis in Tetrahymena perhaps by a mu-like opioid receptor. We now report a further characterization of the elements involved in the signal transduction mechanism of this opioid. Affinity chromatography followed by immunoblots of both intracellular extracts and extracellular medium reveal the presence of two main proteins of 64 and 75 kDa. These molecular weights are much higher than that of any known opioid peptide or precursor protein and suggest that we may be dealing with either a novel opioid or with proteins that by chance cross-react with anti-β-endorphin antibody. Nevertheless, when the biological activity of these proteins was tested it was found that they had an effect similar to that of mammalian β-endorphin, namely inhibition of phagocytosis by a naloxone-reversible mechanism. We have probed a size-selected Tetrahymena library with a pro-opiomelanocortin probe and have obtained several positive clones; the sequencing of their inserts should establish whether we are dealing with a bona fide member of the opioid family. Another aspect we have been studying is the G-proteins which appear to be involved in the modulation of phagocytosis. We have found, by means of Western blotting (using an antibody against the conserved GTP-binding region of the α-subunit), two bands of 51 and 59 kDa; no α-subunit of 59 kDa had been reported previously and may represent a novel G-protein. In spite of these differences, the opioid signal transduction mechanism appears to remarkably resemble that present in more complex organisms.     

Two new species of the genus Dicoma (Asteraceae) from Somalia

Two new species, Dicoma gillettii and Dicoma scoparia (Asteraceae), both from Somalia, are described and illustrated. The differences between the new species and related taxa are listed.     

Biogenic Amines Stimulate Regeneration of Cilia in Tetrahymena thermophila1

ABSTRACT Serotonin and catecholamines affect the regeneration of cilia in Tetrahymena thermophila in a dose-dependent manner: micromolar concentrations are stimulatory, whereas millimolar concentrations have little or no effect. This conclusion is based on motility measurements in regenerating cells and on ciliary counts in scanning electron micrographs. In addition, the recognition mechanism for each hormone appears to be specific and independent. Our results suggest an evolutionary link with hormonal mechanisms in multicellular eukaryotes.     

N-Acetyl-Glucosaminidase Activity during Limb Regeneration in the Adult Newt

N-Acetyl-glucosaminidase activity was measured during the first 25 days of limb regeneration. It was found that the enzyme is present in the normal limb. Following amputation a significant drop was obtained at day 3. A significant increase in enzyme activity was found at day 5 followed by a second drop by day 10. For days 12–15 a second peak of enzyme activity was detected, followed by a third drop; by day 25, normal levels of enzyme activity were detected. Histochemical localization of the enzyme in tissue samples showing enzyme activity as detected biochemically (days 5 and 17 of regeneration) gave negative results. However, enzyme activity was found in the incubation medium, indicating that the enzyme is released from the cells. The peaks of enzyme activity coincide with the stages of limb regeneration where a high degree of tissue demolition and cell lysis occurs. The latter are important events in the regeneration process, cell dedifferentiation, and blastema formation.     

Changes in malathion and pyrethroid resistance after cypermethrin selection of Culex quinquefasciatus field populations of Cuba

Abstract. Use. of the organophosphorus insecticide malathion for mosquito control in Cuba, for 7 years up to 1986, selected elevated non-specific esterase and altered acetylcholinesterase (AChE) resistance mechanisms in Culex quinquefasciatus. In central Havana space-spraying of malathion was replaced by the pyrethroid cypermethrin in 1987: alternate cycles of malathion and cypermethrin were applied in some of the more rural areas of Havana district during 1987-91. Consequently, populations of Cx quinquefasciatus in the central area of Havana developed resistance to cypermethrin, but there is no evidence of pyrethroid resistance in the outlying areas. Malathion resistance levels declined significantly after 1986, measured both by bioassay and the frequency of the elevated esterase resistance mechanism, and then stabilized with no measurable decline during 1990 in any of the populations tested. These populations had less than 10% frequency of susceptible homozygotes for both the esterase and AChE resistance mechanisms, indicating that organophosphate resistance is still prevalent in Cuban Cx quinquefasciatus. These two mechanisms appear to be in linkage equilibrium, suggesting that current selection for double resistance is not strong. In the central Havana region, pirimiphos-methyl, an organophosphorus insecticide unaffected by the two common malathion resistance mechanisms, is now being used in a resistance management strategy designed to avoid pyrethroid resistance spreading.