Notes: SUMMARY. 1. The reliability of the simple frequency, Janetschek, Cassie and Dyar's law methods for determining or corroborating instars of mayflies and stoneflies was evaluated using data from published studies, a population of Baetisca rogersi and populations simulated through use of random numbers and generated normal distributions.2. The Janetschek and Cassie methods are variations of the simple frequency method that offer no significant advantage. Modes of the Cassie method, thought to represent instars, are much more difficult or impossible to detect than are the corresponding peaks of the other two methods.3. Overlap in size between adjacent instars can lead to false instar peaks or modes in frequency plots. The potential for overlap in mayflies and stoneflies is greatly increased, compared to other insects, because of their large number of instars and known developmental variability. The normal distribution simulations demonstrated that instar size variability as low as 5–7.5% COV (coefficient of variability) may lead to false instar peaks when the number of instars is in the typical range. These simulations also indicated that even simple frequency plots with distinct peaks may result in inaccurate instar determinations.4. The number of size classes used in an analysis was correlated with the number of peaks or modes revealed. The number of peaks greater than zero in the Janetschek plots for the Baetisca rogersi population varied from 5 to 53 as the number of size classes was varied from 20 to 188. Similarly for the random number simulations. the number of peaks varied from 6 to 41 as the number of size classes varied from 22 to 127.5. Dyar's law semi-logarithmic plots do not corroborate instars determined through frequency methods, because the uniform spacing of‘instar’data points is the direct result of the uniform spacing of peaks in frequency plots of most data sources (including random numbers), whether or not peaks actually indicate instars. Also Dyar's law plots will‘corroborate’different numbers of instars depending on the peak selection criteria used. The potential for corroborating instars through supplemental rearing and best-fit analysis is discussed.6. The future of mayfly—stonefly instar determination lies in the increased and more rigorous application of the rearing and Palmen body (mayflies only) methods.

Notes: Abstract By screening total human DNA with probes derived from the small polydisperse circular (spc) DNA fraction of cultured human cells, we identified three clones that carry long stretches of β-satellite DNA. Further experiments have shown that the three sequences belong to at least two different β-satellite subfamilies, which are characterized by different higher order subunits. Members of one of these subfamilies are located in the cytological satellites of all acrocentric chromosomes, whereas members of another are located on the short arms of the acrocentrics on both sides of the stalk regions and also in the centromeric regions of chromosomes 1 and 9. This is the first time that β-satellite sequences obtained from the spcDNA of human cells have been assigned to β-satellite subfamilies that are organized as long arrays of tandemly arranged higher order monomers. This indicates that β-satellite sequences can be excised from their chromosomal loci via intrastrand-recombination processes.

Notes: Summary Vitronectin (complement S-protein, serumspreading factor, epibolin) is a multifunctional glycoprotein that mediates cell-to-substrate adhesion, inhibits the cytolytic action of the terminal complement cascade in vitro and binds to several serine protease inhibitors of the serpin family, viz. antithrombin III, plasminogen activator inhibitor I (PAI-1) and II (PAI-2), heparin cofactor II and protease nexin. Using high resolution fluorescence in situ hybridization, we mapped the vitronectin gene to the centromeric region of the long arm of chromosome 17 corresponding to 17q11. The location was confirmed by co-hybridization with the centromerespecific alphoid probe p17H8 (D17Z1) and by chromosome banding with 4,6-diamidino-2-phenylindole-dihydrochloride (DAPI). None of the previously mapped genes that are evolutionary related to vitronectin are located on the same chromosome.