Fate of ochratoxin A in brewing.

The fate of ochratoxin A in brewing was investigated by adding (3H)ochratoxin A to the raw materials at 1- and 10-mug/g levels during mashing in a conventional microbrewing process. The results indicated that large portions (28 to 39%) of the added toxin were recovered in spent grains, with less recovery in the yeast (8 to 20%) and beer (14 to 18%). About 38 and 12% of the added toxin at levels of 1 and 10 mug/g, respectively, were degraded during brewing.     

The ultrastructure of the middle cerebral artery and its associated nerve fibers in the squirrel monkey and baboon

This study describes the ultrastructural characteristics of the middle cerebral artery and its related neural elements in the squirrel monkey and baboon. The cytoarchitecture of the M-1 segment as well as that of the smaller extracerebral and intracerebral vessels is comparable in both animals.Smooth muscle elements are occasionally found within the intimai lining. The nerve bundles associated with vessels contain fewer myelinated fibers as the vessel diameter decreases. The cytological relationship between the neural structures and the smooth muscle cells are discussed.     

Ultrastructure of the compound eye of the diploid female beetle,Xyleborus ferrugineus

Summary The compound eye of female (diploid) Xyleborus ferrugineus beetles was examined with scanning and transmission electron microscopy. The eye is emarginate, and externally consists of roughly 70–100 facets. Each ommatidium is composed of a thickly biconvex lenslet with about 50 electron dense and rare layers. The lens facet overlies a crystalline cone of the acone type which is roughly hourglass-shaped. Pigment cells envelop the entire ommatidium, and pigment granules also are abundant throughout the cytoplasm of the 8 retinular cells. The rhabdomeres of 2 centrally situated photoreceptor cells effectively fuse into a rhabdom that extends from the base of the crystalline cone deeply into the ommatidium. Six distal peripheral retinular cells encircle the 2 central cells, and their rhabdomeres join laterally to form a rhabdomeric ring around the central rhabdom. The rhabdom and rhabdomeric ring are effectively separated by the cytoplasm of the two central retinular cells which contains the usual organelles and an abundance of shielding pigment granules. Eight axons per ommatidium gather in a tracheae-less fascicle before exiting the eye through the fenestrate basement membrane. No tracheation was observed among the retinular cells. Each Semper cell of each observed crystalline cone contained an abundance of virus-like particles near the cell nucleus. The insect is laboratory reared, and the visual system seems very amenable to photoreceptor investigations.This research was supported by the Director of the Research Division, C.A.L.S., University of Wisconsin, Madison; and in part by research grant No. RR-00779 from the Division of Research Resources, National Institutes of Health and by funds from the Schoenleber Foundation, Milwaukee, WI to D.M.N.     

Variation in the transition from inside to outside work in the red harvester ant Pogonomyrmex barbatus

Summary. In laboratory colonies of the red harvester ant, Pogonomyrmex barbatus, we observed the sequence of tasks performed by marked individuals. Observations of about 760 ants in three laboratory colonies indicate that ants often move from inside to outside work. However, there was a great deal of variation in the sequence. If trends in sequence were weak because ants do move from inside to outside work but the duration of our observations was too short to see the transition, ants should be observed to stay either inside or outside. There was no significant tendency for ants to persist in inside or outside work, indicating the variability in sequence is real. Ants tended to perform midden work before they died. Foraging activity is low in laboratory colonies, and it may be that ants that would be foragers in the field end up as midden workers in the laboratory. High variability in task sequence, in uniform laboratory conditions, contrasts with the apparently more consistent sequence from inside to outside work in the field. This suggests that requirements imposed by variable external conditions and colony needs in the field have a strong influence on task sequence.Received 7 May 2004; revised 11 November 2004; accepted 18 November 2004.     

Evaluation of methods for the estimation of mutation rates in cultured mammalian cell populations

A systematic comparison of 5 different statistical methods for the estimation of mutation rate (mu) in cultured Chinese hamster V79 cells is presented. Fluctuation tests were performed with several large batches of parallel cell cultures each allowed to grow for a different length of time in order to reach different population size (Nt). Based on Lea and Coulson's theoretical distribution, a comparison has been made between the experimental data and the expected distribution of the number of ouabain-resistant mutants per culture in these hamster cell populations. The sum of squared deviation between the observed and expected values, or SSD, was used as a means of the adequacy of the estimation method; the method which gives the smallest SSD is regarded as the best one for the estimation of mu. Our results show that when Nt is small, the occurrence of mutation is infrequent, and SSDs from different methods are similar. However, when Nt is large, there is a great discrepancy of the SSD values, suggesting a preference of using the maximum likelihood method, the Po method, the median method, the upper quartile method and the mean method, in that order, for the estimation of mu. The order of preference is correlated with estimation efficiencies. Depending on the size of Nt and the method used, the estimated mu may vary up to more than 3-fold. At a large Nt, the mu obtained from the maximum likelihood method is very precise. This suggests the importance of choosing an appropriate Nt as well as method for the estimation of mu.     

Zoogeography of Intertidal Communities in the West Indian Ocean as Determined by Ocean Circulation Systems: Patterns from the Tetraclita Barnacles

The Indian Ocean is the least known ocean in the world with the biogeography of marine species in the West Indian Ocean (WIO) understudied. The hydrography of WIO is characterized by four distinct oceanographic systems and there were few glacial refugia formations in the WIO during the Pleistocene. We used the widely distributed intertidal barnacle Tetraclita to test the hypothesis that the distribution and connectivity of intertidal animals in the WIO are determined by the major oceanographic regime but less influenced by historical events such as Pleistocene glaciations. Tetraclita were studied from 32 locations in the WIO. The diversity and distribution of Tetraclita species in the Indian Ocean were examined based on morphological examination and sequence divergence of two mitochondrial genes (12S rDNA and COI) and one nuclear gene (histone 3, H3). Divergence in DNA sequences revealed the presence of seven evolutionarily significant units (ESUs) of Tetraclita in WIO, with most of them recognized as valid species. The distribution of these ESUs is closely tied to the major oceanographic circulation systems. T. rufotincta is distributed in the Monsoonal Gyre. T. ehsani is present in the Gulf of Oman and NW India. Tetraclita sp. nov. is associated with the Hydrochemical Front at 10°S latitude. T. reni is confined to southern Madagascan and Mauritian waters, influenced by the West Wind Drift. The endemic T. achituvi is restricted to the Red Sea. Tetraclita serrata consists of two ESUs (based on mtDNA analysis) along the east to west coast of South Africa. The two ESUs could not be distinguished from morphological analysis and nuclear H3 sequences. Our results support that intertidal species in the West Indian Ocean are associated with each of the major oceanographic circulation systems which determine gene flow. Geographical distribution is, however, less influenced by the geological history of the region.