Pollen placement and reproductive isolation between two brazilianPolygala species (Polygalaceae)

Polygala vauthieri andP. monticola var.brizoides have secondary pollen presentation from a basket-like structure on the style apex. This basket is loaded after the first visit by a bee. Pollen reception, therefore, can precede the issue of pollen. A sticky stigma secretion glues the pollen from the basket under the head of the bee visitor in an exactly predetermined spot on the left side only. This position mostly forms a kind of safe spot, where the bee can not remove the pollen. The exact position on the bee's head is determined by the species specific distance between style tip and nectary in the visited flower. In this way the two sympatric species deposit the pollen 2 mm apart on the visitor and so can avoid hybridization pollination, while being visited by the same group of bees.     

The inheritance of node number and rate of node production in Brussels sprouts

Summary The total vegetative node number, rate of node production and number of sprouts over 13 mm diameter were recorded for 10 F₁ Brussels sprout cultivars and 45 progenies derived by intercrossing and selfing them. Significant differences, resulting from additive gene action, were found between the 10 cultivars and between their progenies for both characters. For total node number there was also evidence of dominant gene action. Total node number and rate of node production were closely correlated as were total node number and the number of harvested sprouts. The factors causing differences in rate of node production are indicated and the relationship of this character to other Brussels sprout yield components is outlined.     

Photosensory transduction in Euglena gracilis: Effect of some metabolic drugs on the photophobic response

We have investigated the effect of some metabolic drugs, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), 2,4-dinitrophenol (DNP), sodium azide (NaN₃), on the photobehavior of single cells of Euglena gracilis, in order to clarify the relevance of different metabolic pathways in the process of photoperception and sensory transduction in this alga. The results obtained show that the photophobic response of Euglena is not affected by the action of these drugs. This suggests that neither the photosynthetic process nor oxidative phosphorylation play a significant role in the phenomenon of photosensory transduction in Euglena.List of Abbreviations DNP 2,4-dinitrophenol - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - PSI Photosystem I - PSII Photosystem II     

Saprobic sequence within the genus euglena

In total 73 species of Euglena were ordered according to their saprobic index (S) and saprobic valency starting with species tolerating a heavy organic pollution and ending with those from most clean water. This paper is meant as an addition to the Ergebnisse der Limnologie, Heft 7 (Sládeek, 1973).     

Light-Induced Body Movement of Euglena gracilis Coupled to Flagellar Photophobic Responses by Mechanical Stimulation*†

SYNOPSIS. In low viscosity media, Euglena gracilis strain Z responds to a sudden change in light intensity by a cessation of forward movement, followed by a reorientation of the locomotor flagellum which results in turning of the cell around the lateral axis (photophobic response). At a viscosity interface between low [～ 1 cP (centipoise)] and high (4000 cP) media, the cells exhibit avoidance responses or become immobilized in the higher viscosity medium. Upon changing the light intensity, free swimming cells have photophobic responses, while immobilized ones undergo body contractions. For cells immersed in media of varying viscosity, the delay between light stimulation and body contraction (transduction time) is shortest at high viscosities. From 500 to 2000 cP, where the cells are capable of both movement and light-induced body contractions, there is a logarithmic dependence of the transduction time on the viscosity. The transduction time does not vary appreciably with the intensity of the primary light stimulus within a range of 0.14-1.13 kW/m².     

Cyclic Changes in Chloroplast Structure in Synchronized Euglena gracilis*

SYNOPSIS. In populations of Euglena gracilis strain Z synchronized by cultivation on a repetitive light-dark cycle, chloroplasts undergo cyclic changes in structure. During most of the light period chloroplasts are relatively compact with closely appressed lamellae; during the dark (division) period the chloroplasts become quite distended. This change persists for at least one cycle even when the cells are left in continuous light, suggesting that the periodicity may be related more to the age of the cell than to a direct effect of light. In addition, the pyrenoid in synchronized cells has a transient existence, being present only in the first half of the light period.     

Efficacy of Oxamyl Against Heterodera schachtii on Cabbage

The efficacy of oxamyl in controlling Heterodera schachtii on cabbage was determined by applying various contbinations of soil drenches at 6.7 kg (a.i.)/ha and foliar sprays at 0.04 kg (a.i.)/100 liters of water to cabbage seedlings. Pretransplant drenches provided some control of H. schachtii over a 13-week period. A single foliar spray of oxamyl 1 week before transplanting apparently prevented penetration of H. schachtii larvae; post-transplant sprays were relatively ineffective. A pretransplant or transplant drench combined with a foliar application 2 weeks after transplanting provided the most effective control. The effectiveness of drenches plus post-transplant sprays is probably due to the spray augmenting the action of the drench in inhibiting the development of larvae after penelration.     

ATPase Activity in Flagella from Euglena gracilis. Localization of the Enzyme and Effects of Detergents*

SYNOPSIS. The biochemical effects of some detergents on the ATPase activity of isolated flagella from Euglena gracilis are related to morphologic obliterations induced by those detergents. Enzymic activity can be localized by electron microscopy along the microtubules and also on the paraflagellar rod. The nonionic detergent digitonin solubilizes the enzyme linked to dyneinic arms, whereas the activity linked to residual structures appears enhanced. These results support the hypothesis that the paraflagellar rod may be a structure actively related to the motility of this type of flagellum.     

Nitrofuran-Reducing Enzymes of Euglena*

SYNOPSIS. Euglena gracilis strain Z, green, dark-grown, and “bleached”with N-methyl-N-nitro-N-nitrosoguanidine, was found to contain 2 soluble enzymes which reduce nitrofurans. A small amount of activity was demonstrated also in a particulate fraction of sonic extracts, but none in isolated chloroplasts. The reduction of 5 nitrofurans, having widely differing bleaching activities, by each of the 2 enzymes was examined.