The Membrane-Bound Forms of the Mitochondrial ATPase of Turnip (Brassica napus L.) and Mung Bean (Phaseolus aureus): Characterization and Investigation of Factors Controlling Activity

Isolated intact plant mitochondria, including those from turnipand mung bean, show low endogenous Mg²⁺-ATPase activity and,unlike mammalian mitochondria, lack significant uncoupler-stimulatedATPase activity. In contrast, the rates of respiration-drivenATP synthesis are comparable to those in mammalian mitochondria,suggesting the presence of an ATPase inhibitor. Disruption ofintact turnip mitochondria only results in limited increasesin ATPase activity, indicating that a permeability barrier toATP transport is not primarily responsible for the low endogenousactivity. The ATPase activity of turnip mitochondria and membraneparticles can be increased up to 50-fold when assayed underoptimum conditions. Time-dependent increases in activity inducedby ageing, exposure to salts and trypsin treatment, are allconsistent with an inhibitor protein being responsible for thelow endogenous activity and lack of uncoupler-stimulation. TheATPase activity of particles under optimum conditions and afterageing is sufficient to account for the rates of ATP synthesis.After activation, turnip mitochondrial ATPase activity is similarto the mammalian enzyme in inhibitor sensitivity, pH optimum,bivalent cation requirement, and sensitivity to ‘activatinganions’. In mung bean mitochondria, a permeability barrierto ATP is only partly responsible for the low endogenous ATPaseactivity, together with the inhibitory factor. On the basisof variation in the relative Ca²⁺ and Mg²⁺ -ATPase activitiesafter various treatments, a Ca²⁺-regulatory site which affectsATPase activity is proposed to exist in the F₁ATPase complex. Key words: Plant mitochondrial ATPase, calcium/magnesium -ATPase, inhibitor+ nucleotide specificity, cation/anion effects     

A Companion to Psychological Anthropology

A Companion to Psychological Anthropology. Conerly Casey and Robert B. Edgerton, eds. Williston, VT: Blackwell Publishers, 2005. 523 pp.     

Ciliate communities in shallow groundwater: seasonal and spatial characteristics

1. Ciliated protozoans (Phylum Ciliophora) were collected from five sites in a shallow groundwater system in southern Ontario, Canada over a 13‐month period: one at the spring source, two along the channel banks, and two in the stream channel. Ciliates and environmental data were collected from surface water and at five depths into the sediment, located at 20, 40, 60, 80 and 100 cm. 2. Species richness was high (170 ciliate species belonging to 89 genera were identified) and variable, both spatially and temporally. Highest species richness (86) occurred between 20 and 60 cm, and typically decreased below 60 cm. 3. Ciliate densities were also seasonally and spatially variable. Densities peaked in March between 40 cm (as high as 69 900 cells L⁻¹) and 60 cm, and again in May and June at 80 and 100 cm. Densities were lowest in winter. The surface‐water ciliate community had a different species composition and lower population densities. 4. At all depths, small (<50 μm) bacterivorous ciliates typically dominated, but omnivorous and predatory species were also present (combined, up to 30% of the average density). 5. Several ciliate genera, traditionally considered planktonic, occurred at low densities from 40 cm down to 100 cm. 6. Ordination analysis indicated that the main factors influencing the shallow groundwater ciliate communities were depth and temperature. 7. Dissolved oxygen also appeared to influence these communities in that they typically comprised genera that preferred either low‐oxygen or anaerobic conditions.     

Growth of nestling Barn Owls Tyto alba in central Mali

Data on growth of 276 young Barn Owls were analysed with respect to the effects of year and month of hatching, hatch order and brood order. Growth characteristics considered were weight; lengths of culmen, tarsus, central tail feathers and quill of third outermost primary; standard wing length; and wing span. For weight the growth constant K was 0151 and time t ₁₀- t ₉₀ was 32-2 days. Least-squares analyses showed that gain in weight and culmen and tarsus length were affected by month of hatching with young hatched in the middle part of the breeding season showing the most rapid growth. Hatch order affected gain in weight. Differences in growth rates of all these characters were not, however, reflected in differences in weight or length at fledging except for the effects of brood on weight with second broods fledging at significantly lighter weights than first ones. Predictive equations for character against age are provided for all linear measurements. All characters examined attained apparent asymptotes before fledging except tail and standard wing length.     

Aspects of the reproductive ecology of the Hamerkop Scopus umbretta in central Mali

In a 4-year study of Hamerkops in central Mali, territories of breeding pairs overlapped and most clutches were laid in the late rainy or early dry seasons. Clutches averaged 4–8 eggs. Different pairs laid eggs having, on average, different dimensions. Eggs laid in the late rainy and early dry seasons were larger than those laid at other times. Eggs weighed, at 27-8 g, about 6% of adult female weight. Hatching success was 79% with a fledging rate of eggs hatched of 53%. Successful nests fledged 27 young but for all completed clutches the fledging rate was 0'9. Young hatched early in the sequence had a higher survival rate than those hatched later. Mean age at fledging was 47 days. Pairs fledged between 0–5 and 0–9 young per year.     

Rate of trypanosome killing by lectins in midguts of different species and strains of Glossina

The activity of lectins in different species of tsetse was compared in vivo by the time taken to remove all trypanosomes from the midgut following an infective feed and in vitro by agglutination tests. Teneral male Glossina pallidipes Austen, G. austeni Newstead and G. p. palpalis R-D. removed 50% of all Trypanosoma brucei rhodesiense Stephens & Fantham infections within 60 h. A 'refractory' line of G. m. morsitans Westwood took 170 h to kill 50% infections while a 'susceptible' line of the same species failed to kill 50%. Agglutination tests with midgut homogenates showed differences between fly stocks which accorded with differences in rate of trypanosome killing in vivo. Flies fed before an infective feed were able to remove trypanosomes from their midguts more quickly than flies infected as tenerals. Increasing the period of starvation before infection increased the susceptibility to trypanosome infection of non-teneral flies. Teneral flies showed little agglutinating activity in vitro, suggesting that lectin is produced in response to the bloodmeal. Feeding flies before infection also abolished the differences in rate of trypanosome killing found between teneral 'susceptible' and 'refractory' G. m. morsitans, suggesting that maternally inherited susceptibility to trypanosome infection is a phenomenon limited to teneral flies. Electron micrographs of midguts of G. m. morsitans suggest that procyclic trypanosomes are killed by cell lysis, presumably the result of membrane damage caused by lectin action.     

Microgeographic distribution of immature Ixodes dammini ticks correlated with that of deer

In order to determine whether the small-scale distribution of immature Ixodes dammini Spielman et al. corresponds closely to the activity patterns of white-tailed deer, Odocoileus virginianus (Zimmerman), these relationships were examined in a site on Long Island, New York, U.S.A. We first determined the extent and temporal pattern of adult ticks feeding on deer by examining twenty-three resident deer tranquilized during September-December 1985. I. dammini adults infested deer throughout this fall period, most abundantly during October and November. With radio-telemetry collars attached to deer we determined the relative frequency that they occupied 0.25 ha quadrats of the study site. During the following summer, we examined white-footed mice, Peromyscus leucopus (Rafinesque), that inhabited these quadrats and removed immature ticks from each. 8975 larval and 163 nymphal I. dammini were removed from 208 mice trapped in forty-three such quadrats. The frequency of deer using these quadrats was positively correlated with both the number of larval and of nymphal ticks per mouse. These results suggest that risk of I. damminiborne zoonotic disease may be decreased by locally reducing deer density in sites that experience intense human activity.     

Rhizocaline, Rooting Co-factors, and the Concept of Promoters and Inhibitors of Adventitious Rooting - A Review

In many studies, reviewed in this paper, eluates of separatedplant extracts and various known endogenous and exogenous substanceshave promoted or inhibited adventitious rooting when appliedto stem cuttings. Some of the promoters are thought to act inconcert with auxin (the co-factors) and include various phenolics. The mode of action of most rooting promoters and inhibitorsis obscure. There is no good evidence that rhizocaline, theoriginally postulated root-forming hormone, consists of an auxin-phenolicconjugate, and other explanations for the action of phenolicsare not well substantiated. It is suggested that the action of many rooting promoters andinhibitors is mediated by chemical injury. Irrespective of theirchemical identity, sublethal concentrations promote rooting,while higher concentrations are inhibitory. Rhizocaline, co-factors, promoters, inhibitors, adventitious rooting     

Changing Responses of Stomata to Abscisic Acid and CO2 as Leaves and Plants Age

Willmer, C. M., Wilson, A. B. and Jones, H. G. 1988. Changingresponses of stomata to abscisic acid and CO₂ as leaves andplants age.—J. exp. Bot. 39: 401–410. Stomatal conductances were measured in ageing leaves of Commelinacommunis L. as plants developed; stomatal responses to CO₂ andabscisic acid (ABA) in epidermal strips of C. communis takenfrom ageing leaves of developing plants and in epidermal stripsfrom the same-aged leaves (the first fully-expanded leaf) ofdeveloping plants were also monitored. Stomatal behaviour wascorrelated with parallel measurements of photosynthesis andleaf ABA concentrations. Stomatal conductance in intact leavesdecreased from a maximum of 0-9 cm s^{– 1} at full leaf expansionto zero about 30 d later when leaves were very senescent. Conductancesdeclined more slowly with age in unshaded leaves. Photosynthesisof leaf slices also declined with age from a maximum at fullleaf expansion until about 30 d later when no O₂ exchange wasdetectable. Exogenously applied ABA (0.1 mol m^{– 3}) didnot affect respiration or photosynthesis. In epidermal stripstaken from ageing leaves the widest stomatal apertures occurredabout 10 d after full leaf expansion (just before floweringbegan) and then decreased with age; this decrease was less dramaticin unshaded leaves. The inhibitory effects of ABA on stomatalopening in epidermal strips decreased as leaves aged and wasgreater in the presence of CO₂ than in its absence. When leaveswere almost fully-senescent stomata were still able to open.At this stage, guard cells remained healthy-looking with greenchloroplasts while mesophyll cells were senescing and theirchloroplasts were yellow. Similar data were obtained for stomatain epidermal strips taken from the same-aged leaves of ageingplants. The inhibitory effects of ABA on stomatal opening alsodecreased with plant age. In ageing leaves both free and conjugated ABA concentrationsremained low before increasing dramatically about 30 d afterfull leaf expansion when senescence was well advanced. Concentrationsof free and conjugated ABA remained similar to each other atall times. It is concluded that the restriction of stomatal movements inintact leaves as the leaves and plants age is due mainly toa fall in photosynthetic capacity of the leaves which affectsintracellular CO₂ levels rather than to an inherent inabilityof the stomata to function normally. Since stomatal aperturein epidermal strips declines with plant and leaf age and stomatabecome less responsive to ABA (while endogenous leaf ABA levelsremain fairly constant until leaf senescence) it is suggestedthat some signal, other than ABA, is transmitted from the leafor other parts of the plant to the stomata and influences theirbehaviour. Key words: Abscisic acid, CO₂, Commelina, leaf age, senescence, stomatal sensitivity