Effects of Nosema bombi and its treatment fumagillin on bumble bee (Bombus occidentalis) colonies

We examined the effects of Nosema bombi (Microsporidia: Nosematidae) on colonies of bumble bees, Bombus occidentalis Greene (Hymenoptera: Apidae), used to pollinate tomatoes in commercial greenhouses. We assessed methods of detecting N. bombi and tested the effectiveness of fumagillin to control this parasite. N. bombi did not affect adult population size or amount of brood in B. occidentalis colonies. Fumagillin was not effective against N. bombi at the doses we tested, and frass samples did not provide accurate estimates of the intensity of N. bombi infections. The number of N. bombi spores per bee was highly variable among bumble bees within colonies, and accurate estimates could only be obtained by sampling a large proportion of bees in each colony. Therefore, whole bee and frass sampling is useful for determining if N. bombi is present or absent, but not for obtaining accurate estimates of the intensity of N. bombi infections.     

MICROTUBULE ORGANIZATION 1 regulates structure and function of microtubule arrays during mitosis and cytokinesis in the Arabidopsis root

MICROTUBULE ORGANIZATION 1 (MOR1) is a plant member of the highly conserved MAP215/Dis1 family of microtubule-associated proteins. Prior studies with the temperature-sensitive mor1 mutants of Arabidopsis (Arabidopsis thaliana), which harbor single amino acid substitutions in an N-terminal HEAT repeat, proved that MOR1 regulates cortical microtubule organization and function. Here we demonstrate by use of live cell imaging and immunolabeling that the mor1-1 mutation generates specific defects in the microtubule arrays of dividing vegetative cells. Unlike the universal cortical microtubule disorganization in elongating mor1-1 cells, disruption of mitotic and cytokinetic microtubule arrays was not detected in all dividing cells. Nevertheless, quantitative analysis identified distinct defects in preprophase bands (PPBs), spindles, and phragmoplasts. In nearly one-half of dividing cells at the restrictive temperature of 30 degrees C, PPBs were not detected prior to spindle formation, and those that did form were often disrupted. mor1-1 spindles and phragmoplasts were short and abnormally organized and persisted for longer times than in wild-type cells. The reduced length of these arrays predicts that the component microtubule lengths are also reduced, suggesting that microtubule length is a critical determinant of spindle and phragmoplast structure, orientation, and function. Microtubule organizational defects led to aberrant chromosomal arrangements, misaligned or incomplete cell plates, and multinucleate cells. Antiserum raised against an N-terminal MOR1 sequence labeled the full length of microtubules in interphase arrays, PPBs, spindles, and phragmoplasts. Continued immunolabeling of the disorganized and short microtubules of mor1-1 at the restrictive temperature demonstrated that the mutant mor1-1(L174F) protein loses function without dissociating from microtubules, providing important insight into the mechanism by which MOR1 may regulate microtubule length.     

Acute effects of 50 Hz, 100 μT magnetic field exposure on visual duration discrimination at two different times of the day

A two-alternative, forced-choice visual duration discrimination task was used to examine the effect of an intermittent, 50 Hz, 100 μT magnetic field on accuracy at two different times of the day. A total of 59 female and 40 male subjects with an age range of 18 to 46 years were studied under both field-exposed and sham-exposed conditions. The subject's task was to decide which of two sequentially presented light flashes had the longer duration, percentage correct being the measure of performance. The data were gathered under double-blind conditions with sham and real exposure counterbalanced. Exposure to the magnetic field produced a small improvement in accuracy but only at the most difficult level of the task, with female subjects showing a larger improvement than males. The time of day at which the study was run had no effect on performance. Despite the relatively large number of subjects used and a relaxed alpha level (P = .3), the statistical power of the test to detect the observed effect was still only 0.71. Bioelectromagnetics 19:310–317, 1998. © 1998 Wiley-Liss, Inc.     

Using independent nest survey data to validate changes in reporting rates of Martial Eagles between the Southern African Bird Atlas Project 1 and 2

Repeat monitoring is vital to measure biodiversity change. However, monitoring protocols may change, as survey techniques improve or different questions are asked. Such modifications may cause difficulties when examining changes in wildlife populations. The Southern African Bird Atlas Project (SABAP) 1 and 2 are repeat national bird surveys undertaken 20 years apart. These surveys therefore offer unrivalled potential to examine bird population changes in an African context. However, changes in protocols, both spatially and temporally, between the two surveys have raised concerns over using these data to infer population changes. In this study we use independ- ent nest survey data to test whether changes in reporting rates of Martial Eagles in the Kalahari Gemsbok National Park between the two SABAP surveys were reflected in real change in numbers of nesting pairs. From 11 quarter degree squares (QDS), covering c. 8 000 km2, both SABAP and nest surveys suggested a near identical 44% decline. Levels of agreement were weaker at the individual QDS scale, although in 67% of cases the direction of change was the same using both surveys. These results suggest that comparisons in the reporting rates between SABAP 1 and SABAP 2 accurately reflect changes in the breeding population size of this species.     

Vegetational stability and rare species from Early Holocene Lewis

Summary

Strata of complex geomorphological origin at Skigersta in the northeast of the Isle of Lewis include organic sediments which have provided a detailed pollen profile and two Early Holocene radiocarbon dates. These two sources of evidence suggest that a stable, pre-woodland, species-rich grass and sedge landscape may have existed for at least one thousand radiocarbon years (10,250 to 9250 BP). Included in the pollen taxa are Koenigia islandica and Polemonium caeruleum, neither of which is now native to Lewis. The former was present in the Middle Devensian (c. 30 kyr BP), perhaps hinting at survival in a local refugium during the Late Devensian glaciation.     

Detection of significant demographic differences between subpopulations of prehispanic Maya from Copan, Honduras, by survival analysis

Heterogeneity and small sample size are problems that affect many paleodemographic studies. The former can cause the overall distribution of age at death to be an amalgam that does not accurately reflect the distributions of any of the groups composing the heterogeneous population. The latter can make it difficult to separate significant from nonsignificant demographic differences between groups. Survival analysis, a methodology that involves the survival distribution function and various regression models, can be applied to distributions of age at death in order to reveal statistically significant demographic differences and to control for heterogeneity. Survival analysis was used on demographic data from a heterogeneous sample of skeletons of low status Maya who lived in and around Copan, Honduras, between A.D. 400 and 1200. Results contribute to understanding the collapse of Classic Maya civilization.     

Benedenia rohdei n. sp. (Monogenea: Capsalidae) from the gills of Lutjanus carponotatus (Perciformes: Lutjanidae) from the Great Barrier Reef,Queensland, Australia,with a description of the oncomiracidium

A benedeniine monogenean, Benedenia rohdei n. sp., is reported from the gills of the stripey Lutjanus carponotatus (Richardson, 1842) (Lutjanidae) from Heron Island and Lizard Island, Queensland, Australia. The oncomiracidium of the new species is also illustrated. B. rohdei n. sp. differs from all known species of the genus in the possession of a sclerite at the tip of the penis. Examination of type-specimens of B. jaliscana Bravo-Hollis, 1952 has shown that the three penis ‘hooks’ described by Bravo-Hollis are unsclerotised conical papillae.