Buccal and Somatic Infraciliature of Lagynus elegans (Engelmann, 1862) Quennersted, 1867 (Ciliophora, Prostomatea): Remarks on its Systematic Position

The somatic and buccal infraciliature of Lagynus elegans are described, and aspects of its division and conjugation are reported. Its somatic infraciliature is made up of 37–46 meridianal kineties composed of isolated kinetosomes that have thick and long kinetodesmal fibers. In the anterior zone of the cell, the circumoral infraciliature can be observed: it is composed of short, slightly oblique kinetal segments, which are formed of three kinetosomes each. The brosse of this species consists of 3 or 4 groups that possess 4 to 6 ciliated kinetosomes each; these kinetosomes lack kinetodesmal fibers. On the apical pole of the cell, surrounding the oral opening, a crown of nematodesmata is observed; these nematodesmata are connected to each other by a fibrillar structure. Taking into account these features, we propose that this genus be transferred from the order Prostomatida to a new family, Lagynidae, of the order Prorodontida.     

Transfer of Mass and Energy in a Cassava Community (Manihot esculenta Crantz cv. Cubana) 2. CO2 Exchange in a Savanna Climate

The energy balance approach was applied to calculate the CO₂flux above and within a cassava community, growing during asavanna wet season. Data of the response of CO₂ exchange todiurnal changes in the savanna environment were integrated toa growth analysis of the cassava crop. The carbon budget of the entire community was calculated atdifferent development stages. Results indicate that CO₂ uptakein cassava appears to follow a linear net radiation responsecurve, dependent on crop age. The maximum net CO₂ uptake decreasedfrom 0.195 MJ m^–2 day^–1 at maximum leaf area development(August) to 0.028 MJ m^–1 day-1 2 months later. These ratesrepresent 41 and 19 per cent gross assimilation. Data of energy conversion efficiency show that at a maximumleaf area development, the crop fixed 2.2 and 0.9 per cent Rtas gross (_g) and net photosynthesis (n) respectively. As theseason proceeded,n decreased to 0.1, whereas g decreased to0.7, which indicates that dry matter lost by respiration isone of the determining factors in the seasonal trend of efficiencychanges. The comparison of growth characteristics calculated for cv.Cubana, growing during consecutive years in the same experimentalsite, indicate that yearly variability in dry matter accumulationis due to the wide range of environmental conditions presentduring the savanna wet season. Operational factors acting depressivelyon the cassava carbon budget and affecting dry matter productionwere also analysed. Manihot esculenta Crantz, cassava, microclimate, carbon budget, carbon dioxide fluxes     

Acid and Neutral Hydrolases in Trypanosoma cruzi. Characterization and Assay*

Twelve acid hydrolases, 4 near-neutral hydrolases and alkaline phosphatase were demonstrated in 0.34 M sucrose homogenates of Trypanosoma cruzi strain Y: p-nitrophenylphosphatase and α-naphthylphosphatase, with optimum pH at ? 6.0; α-galactosidase, β-galactosidase, β-glucosidase, N-acetyl-β-glucosaminidase, cathepsin A and peptidase I and III, with optimum pH between 5.0 and 6.0: and arylsulfatase cathepsin D, α-arabinase and α-mannosidase with optimum pH at ? 4.0 α-Glucosidase, gluccse-6-phosphatase and peptidase II had optimum pH at ? 7.0. β-Glycerophcsphatase had a broad pH-activity curve from 4.0 to 7.4, with maximum activity at pH 7.0. The main kinetic characteristics of these enzymes and their quantitative assay methods were studied. No activity was detected for α-fucosidase, β-xylosidase, β-glucuronidase, elaidate esterase. acid lipase, and alkaline phospho-diesterase.     

BOOK REVIEW

Beyond a Western Bioethics: Voices from the Developing World , edited by Angeles Tan Alora and Josephine M. Lumitao. Washington DC: Georgetown University Press, 2001. xiv + 162 pp. US$59.95 (hardback).     

Mucilage in Cacti: Its Apoplastic Capacitance, Associated Solutes, and Influence on Tissue 5

Mucilage content in the stems of four sympatric cactus speciesvaried from none for Ferocactus acanthodes, 19% by dry weightfor Opuntia basilaris, 26% for Opuntia acanthocarpa, and 35%for Echinocereus engelmannii. Although the mucilage differedchemically among the species (the arabinose content ranged from17% to 51% of the sugar monomers), its relative capacitance(change in relative water content per unit change in water potential)remained about 15 Mpa^–1. The relative capacitance of thewater-storage parenchyma averaged 1·04 Mpa^–1 andwas consistent with the mucilage content, being lowest for F.acanthodes and highest for E. engelmannii. Mucilage isolatedfrom hydrated tissue was accompanied by solutes with an osmoticpressure of about 0·2 MPa. Such associated solutes influencethe water-release characteristics of mucilage and hence itsrole as an apoplastic capacitor. In particular, extracellularsolutes can facilitate the release of appreciable mucilage-boundwater to the cells at tissue water potentials occurring duringthe initial phases of drought. Key words: Echinocereus engelmannii, Ferocactus acanthodes, Opuntia acanthocarpa, Opuntia basilaris, water potential isotherms     

Annual survival rates of adult Red-necked Nightjars Caprimulgus ruficollis

Nothing is known about the survival rates of Nightjars. Here we estimate annual survival rates of adult Red-necked Nightjars Caprimulgus ruficollis in and around the Donana National Park, southwest Spain. During the period 1989-95, 557 adults were marked and 19.7% of them were recaptured at least once in subsequent years. Capture-recapture models were built to estimate separately survival and recapture probabilities. The final selected model showed that probabilities of recapture differed between years (0.06-0.30) but not between sexes, and were independent of recapture effort. Survival was dependent on the interaction between sex and rainfall, this effect being negative for females and positive for males. However, it is not clear why rainfall influences the survival of males and females differentially due to the lack of accurate information on other life history traits. Average adult survival for the whole period was 0.74 for males (95% CI: 0.63-0.82) and 0.64 for females (95% CI: 0.56-0.72).     

Morphological and Agronomic Traits of a Wild Population and an Improved Cultivar of Common Bean (Phaseolus vulgaris L.)

Through the process of domestication, bean varieties have beenselected from their wild ancestors for various anthropocentrically-importantcharacteristics. In order to compare some agronomic and morphologicaltraits of a wild population and a modern variety (cv. Bayo Mecentral),the following variables were evaluated: growth habit; numberof nodes on the main stem; number of branches and pods per plant;flower and pod colours; stem length; days to initiation of flowering;days to physiological maturity and duration of flowering. Variationin each trait was recorded, particularly in the wild population.The growth habits of the wild population were very diverse andthere were positive and significant correlations between 13pairs of variables, including the number of nodes on the mainstem, pods per plant, days to flowering and duration of flowering,whereas domesticated beans gave only a few significant correlations.The analysis of principal components indicated that the linearcombination of agronomic and morphological variables, involvingthe first three principal components, accounted for 70% of thetotal variability of the data, and the populations were clearlyseparated as two biological entities by the first principalcomponent. This study confirms that the process of domesticationhas acted to reduce variation in a range of characters. Growth; growth habit; Phaseolus vulgaris ; domestication     

Reproductive biology of the holoparasitic endophyte Bdallophyton bambusarum (Rafflesiaceae)

The reproductive biology of most species of Rafflesiaceae is unknown. We studied several aspects of that of Bdallophyton bambusarum Liebm. (Rafflesiaceae) in a subdeciduous tropical forest. Flowering of B. bambusarum is during the driest time of the year. Male flowers are more numerous, larger, and with more nectar than female flowers, but the nectar from female flowers has a higher sugar concentration. Flies ( Peckia spp., Perckiamya spp.; Diptera: Sarcophagidae) are the pollinators. They make frequent visits, spending more time in the male flowers. Fluorescent dyes applied to track movement indicated extensive pollen flow within populations, and pollen flow could also be occurring between populations. The latter is reflected in the higher genetic variability within, and the great similarity between, populations than previously recorded for the species. Secondary characteristics of dioecious species fit B. bambusarum , but not the trade-off of reproductive resource allocation. Parasitic plants may damage the host, but the mechanism and extent are still unknown.