Economic Mass Cultivation of Paramecium tetraurelia on a 200-Liter Scale1

ABSTRACT. A new and inexpensive medium is described for axenic mass cultivation of Paramecium tetraurelia stock 51s and the double mutant pawn A/pawn B. Skim milk powder is the major carbon and nitrogen source in this medium. Growth characteristics (proliferation rate, final cell density, and cell size) are similar to those observed with other axenic culture media. Cultures were run in one-liter erlenmeyer flasks, a 20-liter, and a 250-liter airlift bioreactor. The yield of a large bioreactor is 750 g (wet wt.) Paramecium or 5 × 10⁹ cells. This easy, economical culture technique will greatly facilitate the use of Paramecium as a model organism for extensive biochemical studies.     

Interactions among leaf toughness, chemistry, and harvesting by attine ants

Abstract. 1. Young and mature leaves of a tropical legume, Inga edulis var. minutula Schery, are strikingly different in secondary chemistry, especially condensed tannins, and leaf toughness.
2. Bioassays with the two different leaf types indicate that leaf cutter ants, Atta cephalotes (L.), always find mature leaves relatively more acceptable than young leaves when selection was based on chemical cues.
3. Since extracts of young leaves show greziter inhibition of fungal pectinases we suggest that leaf-cutter ants are capable of distinguishing which leaf types are most suitable for the growth of their symbiotic fungus.
4. However, mature leaves are 3 times tougher than young leaves and this prevents leaf-cutter ants from harvesting the more suitable mature leaves.
5. Consequently, bioassays which require cutting before leaf removal indicate that some colonies actually harvest more from the less suitable young leaves.
6. We suggest that the quality of a colony's habitat may indicate whether a colony will harvest more of the less suitable young leaves. Colonies which are harvesting from highly suitable host plants avoid the tropical legume I.edulis while those in poorer habitats accept I.edulis but, because of leaf toughness, mostly harvest the less suitable young leaves.     

Genetic and Epidemiologic Evaluation of Dysplastic Nevi

Dysplastic Nevus Syndrome (DNS) has been defined as that trait characterized by the presence of at least one dysplastic melanocytic nevus. DNS was originally described in kindreds having multiple members with melanoma. Various types DNS have been described in other situations to include individuals with apparently sporadic cases, familial DNS without melanoma and individuals with apparently sporadic DNS with melanoma. These categories are based on historical information in general, and not on examination of family members. In all cases, the presence of dysplastic nevi appear to confer some increased risk of melanoma, which varies between the groups. Similarly cutaneous melanoma is thought to occur in several distinct populations-random individuals without DNS, individuals with sporadic DNS, and those with familial DNS. Genetic analysis of DNS has been largely confined to the classically ascertained kindreds associated with melanoma. These studies have usually used diagnostic criteria based on pathology of clinically selected material, and that evidence suggests that DNS is inherited as an autosomal dominant trait in these families. Surveys of the general population have detected rates of dysplastic nevi of 5% 20%. In our Utah-based studies, we have evaluated probands and family members from three groups. These included kindreds with multiple occurrences of melanoma, random individuals with at least one dysplastic nevus, and cases of melanoma with unknown family history. Controls were spouses of study subjects. We sought to determine the percentage of each group associated with dysplastic nevi and/or genetic DNS. The range of phenotype of patients with dysplastic nevi was large with some individuals having few nevi, none of which were clinically atypical, and others having greater than 100 nevi. The prevalence of dysplastic nevi in at least one of two biopsies in Utah population controls is presently Wtimated at 62%. Some probands with melanoma as well as some of their relatives had elevated numbers of nevi, suggesting that this predisposition to melanoma may be inherited.     

The Role of Anaerobic Respiration in Germinating Muskmelon Seeds: II. EFFECT OF ANOXIA TREATMENT AND ALCOHOL DEHYDROGENASE ACTIVITY

Exposing muskmelon (Cucumis melo L.) cultivar seedlots to N₂atmosphere created totally anaerobic conditions which stimulatedethanol production and accumulation in both high and low vigourseeds. However, accumulation of ethanol was consistently higherin the low vigour seeds than in the high vigour ones. In addition,CO₂ production under N₂ and in air suggests the presence ofan apparent ‘Pasteur effect’ in the low vigour seedsbut not in the high vigour seeds. Acetaldehyde production underN₂ was very low and did not seem to be associated with seedvigour, probably because of its nature as an intermediate inethanol production. The fast shift toward ethanol may be dueto the fact that alcohol dehydrogenase, the enzyme which catalyzesthe conversion of acetaldehyde to ethanol, exists in sufficientamounts in the imbibing seeds so that it is not a limiting factorin the conversion to ethanol. Alcohol dehydrogenase activitydid not appear to be related to seed vigour. Key words: Cucumis melo L., Anaerobic respiration, Germination, Seeds.     

Cytotoxicity of Synthetic Fuel Products on Tetrahymena pyriformis. I. Phenol*

SYNOPSIS. Phenol is the major organic constituent of coal-conversion scrub water and is therefore a potential environmental contaminant. After Tetrahymena pyriformis strain GL-C, syngen 1 was exposed to phenol, its behavior, cytology, respiration, and growth rates were examined. Concentrations ≥ 75 mg/liter alter cell motility, shape, and contractile vacuole activity. O₂ uptake was abruptly reduced within 3 min of exposure to phenol in concentrations as low as 10 mg/liter. Concomitantly there was an increase in the electron density of the mitochondrial matrix. Recovery to normal rates of O₂ consumption was paralleled by a return to normal matrix density. Alterations of mucocysts, pellicle, and glycogen were also observed. The length of lag phase growth curves increased generally in proportion to concentration of toxicant. Phenol, however, did not affect the rate of cell multiplication during the exponential growth phase. The potential use of this system to examine the effects of other possible organic pollutants is discussed.     

Temporal Patterns of Apparent Leg Band Retention in North American Geese

ABSTRACT An important assumption of mark—recapture studies is that individuals retain their marks, which has not been assessed for goose reward bands. We estimated aluminum leg band retention probabilities and modeled how band retention varied with band type (standard vs. reward band), band age (1–40 months), and goose characteristics (species and size class) for Canada (Branta canadensis), cackling (Branta hutchinsii), snow (Chen caerulescens), and Ross's (Chen rossii) geese that field coordinators double-leg banded during a North American goose reward band study (N = 40,999 individuals from 15 populations). We conditioned all models in this analysis on geese that were encountered with ≥1 leg band still attached (n = 5,747 dead recoveries and live recaptures). Retention probabilities for standard aluminum leg bands were high ( = 0.9995, SE < 0.001) and constant over 1–40 months. In contrast, apparent retention probabilities for reward bands demonstrated an interactive relationship between 5 size and species classes (small cackling, medium Canada, large Canada, snow, and Ross's geese). In addition, apparent retention probabilities for each of the 5 classes varied quadratically with time, being lower immediately after banding and at older age classes. The differential retention probabilities among band type (reward vs. standard) that we observed suggests that 1) models estimating reporting probability should incorporate differential band loss if it is nontrivial, 2) goose managers should consider the costs and benefits of double-banding geese on an operational basis, and 3) the United States Geological Survey Bird Banding Lab should modify protocols for receiving recovery data.     

Nitrogen aboveground turnover and soil stocks to 8 m depth in primary and selectively logged forest in southern Amazonia

Extensive areas of Amazonia undergo selective logging, modifying forest structure and nutrient cycles. Anthropogenic‐accelerated rates of nitrogen (N) turnover could increase N loss and affect regeneration, carbon sequestration and timber production. We quantified leaf area reduction, canopy opening and downed biomass and resultant N flux from reduced impact logging (RIL) activities. We compared canopy reduction, surface soil moisture and nitrate to 8 m depth between logged gaps and intact primary forest to determine if logging activities increase subsoil nitrate. To test long‐term logging effects, we evaluated surface N stocks along a 12‐year postlogging chronosequence. At the harvest rate of 2.6 trees ha^?1, total N additions in logging gaps, including leaves and wood from felled crowns (24.8 kg N ha^?1) and other killed trees (41.9 kg N ha^?1), accounted for over 80% of the total N addition to aboveground necromass from all logging activities (81.9 kg N ha^?1). Despite this N turnover by logging, belowground nitrate storage to 8 m depth did not differ between logging gaps and primary forest at the low harvest rate and disturbance intensity of this study. Soil water depletion also did not differ between gaps and primary forest over 1 year, indicating the impact on belowground inorganic N was low. Compared with primary forest, nitrate concentrations to 8 m depth in logging gaps were only significantly higher at 60–100 cm, suggesting some N redistribution beyond the bulk of the fine roots in logging gaps. Extrapolated to the Amazon Basin scale, we provide a conservative estimate that logging damage and bole export under RIL would turn over 0.14 ± 0.07 to 0.23 ± 0.12 Tg N yr^?1 based on 1999–2002 selective logging rates. Greater damage during conventional selective logging would cause higher N turnover throughout the Amazon Basin than our results based on RIL.     

Evaluation of Root-n Bandwidth Selectors for Kernel Density Estimation

ABSTRACT The kernel density estimator is used commonly for estimating animal utilization distributions from location data. This technique requires estimation of a bandwidth, for which ecologists often use least-squares cross-validation (LSCV). However, LSCV has large variance and a tendency to under-smooth data, and it fails to generate a bandwidth estimate in some situations. We compared performance of 2 new bandwidth estimators (root-n) versus that of LSCV using simulated data and location data from sharp-shinned hawks (Accipter striatus) and red wolves (Canis rufus). With simulated data containing no repeat locations, LSCV often produced a better fit between estimated and true utilization distributions than did root-n estimators on a case-by-case basis. On average, LSCV also provided lower positive relative error in home-range areas with small sample sizes of simulated data. However, root-n estimators tended to produce a better fit than LSCV on average because of extremely poor estimates generated on occasion by LSCV. Furthermore, the relative performance of LSCV decreased substantially as the number of repeat locations in the data increased. Root-n estimators also generally provided a better fit between utilization distributions generated from subsamples of hawk data and the local densities of locations from the full data sets. Least-squares cross-validation generated more unrealistically disjointed estimates of home ranges using real location data from red wolf packs. Most importantly, LSCV failed to generate home-range estimates for >20% of red wolf packs due to presence of repeat locations. We conclude that root-n estimators are superior to LSCV for larger data sets with repeat locations or other extreme clumping of data. In contrast, LSCV may be superior where the primary interest is in generating animal home ranges (rather than the utilization distribution) and data sets are small with limited clumping of locations.