The problem of the acts duration measurement in relation to the “focal-animal” technique of behavioral recording

The focal-animal technique assumes the continuous recording of the behavior of an individual during a certain time interval. The length of this interval (sampling unit) can be problematic when estimating the duration of behavioral acts. Two acts from the behavioral repertoire of the ant Leptothorax fuenteiwere focused on in this work at different ranges of temporal scales. Analyzing these acts we show the possibility of existence of a sampling artifact, in such a way that the estimates of the durations of the acts would be forced to depend upon the length of the sampling unit that is being used.     

Phosphorylated intermediate of the ATPase of plant plasma membranes

A partially purified preparation of the plant plasma membrane ATPase was phosphorylated when incubated with [gamma-32P]ATP. The phosphoprotein formed has the characteristics of an enzyme intermediate because of its rapidity of phosphorylation and dephosphorylation. The sensitivity of the phosphoenzyme bond to alkaline pH and to hydroxylamine indicates that it is an acylphosphate. Both the ATPase activity and the phosphorylation of the enzyme exhibited an apparent Km value of 0.3 mM ATP. When the phosphorylated enzyme was analyzed by electrophoresis in sodium dodecyl sulfate, only one major band with a molecular weight of about 105,000 contained radioactivity. These results indicate that the plant plasma membrane ATPase has a subunit composition and reaction mechanism similar to the cation-pumping ATPases of animal and fungal plasma membranes.     

Glucose transport in Entamoeba histolytica

That the uptake of glucose by the parasitic amoeba Entamoeba histolytica occurs by an equilibrative transport system is supported by the following observations. 1. The rate of glucose uptake is several orders of magnitude greater than the uptake by pinocytosis. 2. The uptake of glucose exhibits saturation kinetics, with K(m)=1.6mm and V(max.) ranging from 2 to 5mumol/min per ml of cells at 37 degrees C. 3. The glucose analogues 2-deoxyglucose, 3-O-methylglucose and d-xylose are transported by the glucose system although with much less affinity. Competitive inhibition was observed between pairs of substrates, with K(i) values for any sugar closely coincident with the corresponding K(m). 4. d-Xylose, a sugar not metabolized by the cells, equilibrated with 80% of the amoebal cell water. 5. Cells equilibrated with xylose exhibited countertransport of this sugar against its concentration gradient when another substrate was added to the medium. 6. Blocking of glycolysis by iodoacetate or F(-) has no immediate effect on transport. The presence of a glucose-transport system in E. histolytica contrasts with the situation found in the non-parasitic amoeba, where pinocytosis seems to be the only mechanism of solute uptake.     

Unusual properties of a cold-labile fraction of Atlantic cod (Gadus morhua) brain microtubules

A cold-labile fraction of microtubules with unusual properties was isolated from the brain of the Atlantic cod (Gadus morhua). The yield was low, approximately six times lower than that for bovine brain microtubules. This was mainly caused by the presence of a large amount of cold-stable microtubules, which were not broken down during the disassembly step in the temperature-dependent assembly-disassembly isolation procedure and were therefore lost. The isolated cold-labile cod microtubules contained usually only a low amount of microtubule-associated proteins (MAPs). Three high molecular mass proteins were found, of which one was recognized as MAP2. Cod MAP2 differed from mammalian brain MAP2; it was not heat stable and had a slightly higher molecular mass. In contrast to mammalian MAPs, MAP1 was not found in the cold-labile fraction of microtubules. A new heat-labile MAP of higher molecular mass (400 kilodaltons) was however present, as well as a heat-stable protein of slightly lower molecular mass than MAP2. These MAPs showed similar tubulin-binding characteristics as bovine brain MAPs, since they coassembled with taxol-assembled bovine brain microtubules consisting of pure bovine tubulin. In spite of the fact that Ca2+ bound equally to cod and porcine tubulins, it did not inhibit cod microtubule assembly even at high concentrations (greater than 1 mM). In contrast, rings, spirals, and macrotubules were formed. The results show that there are major differences between this fraction of cod microtubules and microtubules from mammalian brain.     

A comparative study of ciliated protozoa communities in activated-sludge plants

Abstract: Ciliated protozoa present in ten activated sludge plants at Madrid (Spain) were identified. The abundance of key groups of ciliates was determined at each plant; attached ciliates made up the most abundant and representative group. Multivariate statistical analysis was employed to study relationships between ciliates and both the physico-chemical and operational parameters of the plants. Partial correlation analysis revealed: (1) The indicator value of attached ciliates in assessing management and performance of the activated sludge process, (2) the relationship of swimming ciliates with short-aged sludges and lower quality effluents and (3) the direct association between swimming-crawling ciliates and bad settlement conditions of the sludge. Factor analysis showed the associations of the most frequent species of ciliates with the operational parameters of the plants, suggesting the indicator value of some of the species: Vorticella striata was related with poor quality of effluent; Aspidisca cicada with stable plant conditions, and Litonotus lamella with a deficiently settling sludge.     

The Glucose-Related Decrease in Polar Auxin Transport During Ripening and its Possible Role in Grapevine Berry Coloring

Journal of Plant Growth Regulation - Auxin is a hormone that delays ripening in part by reducing anthocyanin content and impairing color development. Auxin content declines during the ripening...     

Physical mapping of rDNA genes in the ground beetle Carabus and related genera (Carabidae: Coleoptera)

The major ribosomal DNA (rDNA) loci were localized on meiotic and mitotic chromosomes and in interphase nuclei of 18 ground-beetle species belonging to three tribes of the supertribe Carabitae by fluorescence in situ hybridization (FISH), using a PCR-amplified 18S rDNA as a probe. Meiotic observations indicate that the 18S rDNA sequences are located on the largest autosomal bivalent in 12 species of Carabus , two species of Calosoma (both genera belonging to the tribe Carabini), and three sibling species of Ceroglossus chilensis (tribe Ceroglossini). The data suggest the occurrence of a conservative pattern in these three genera despite the chromosomal rearrangements that have led to karyotypes with higher chromosome numbers in Ceroglossus . A different result is found in Cychrus caraboides (tribe Cychrini), where ribosomal cistrons are located in two medium-sized autosomal pairs. Further species of Cychrini should be studied for corroborating the occurrence of molecular and karyotypical apomorphies in Cychrus with regard to the genera Carabus, Calosoma and Ceroglossus .