X heterochromatin subdivision and cytogenetic analysis in Sciara coprophila (Diptera,Sciaridae)

Five new translocations recovered from irradiated sperm, each having a break-point in the proximal X heterochromatin, have been designated T23, T29, T32, T40, and T70. These translocations, together with Oak Ridge T1, make possible the precise localization of several genetic components including the X centromere, the controlling element, and the ribosomal cistrons. Only the data pertaining to centromere location are presented here. The ribosomal cistrons and controlling element will be dealt with separately. Full cytological details are given for each of the five translocations. The break-points on the X define three blocks of heterochromatin designated H₁, H₂, and H₃. Together they comprise the right arm of the X. H₃ is the smallest and forms the very end of the chromosome. H₁ lies immediately to the right of the centromere. In T23 and T70 the breakpoints are located between H₂ and H₃; in T29 and T32 between H₂ and H₁. In Oak Ridge T1 the break-point lies between H₁ and the centromere and in T40 between the centromere and the whole left arm of the chromosome. For the first time it has been possible to determine the exact breakpoints of the long paracentric inversion that is found on the X homologue.This series of papers is dedicated to Professor Sally Hughes-Schrader —cytologist, naturalist, scholar — who in her eighty-second year is still exulting in the wonders of chromosome behavior and still endowed with that understanding and grace which have heightened immeasurably the lives of those who have known her     

Extra Replications in the “DNA-puffs” ofSciara coprophila

Using the Zeiss UMSP-1, a spectrophotometric study was made of DNA increase in three DNA-puffs located on chromosome II ofSciara coprophila. Each puff showed excessive and disproportionate synthesis. During the course of study it became apparent that the DNA in at least one of the puffs (the most proximal) arises from a number of cytological subunits (bands). When the DNA in the entire puff was measured, only irregular synthesis was revealed. On the other hand, when DNA increase in one of the bands was measured, the absorbancy values formed a geometric series, indicating that the extra DNA arises by additional complete rounds of replication.I wish to acknowledge support by the National Science Foundation (Grant GB-4336), the Max Planck-Gesellschaft, and the U.S. Atomic Energy Commission (Contract No. AT-(40-1)-2690). I am indebted to ProfessorWolfgang Beermann and ProfessorHans Bauer for making possible my trip to Tübingen and for providing laboratory facilities.     

Effects of training and a single session of exercise on lipids and apolipoproteins in hypercholesterolemic men

Crouse, Stephen F., Barbara C. O'Brien, Peter W. Grandjean,Robert C. Lowe, J. James Rohack, and John S. Green. Effects oftraining and a single session of exercise on lipids and apolipoproteins in hypercholesterolemic men. J. Appl.Physiol. 83(6): 2019-2028, 1997.To differentiatebetween transient (acute) and training (chronic) effects of exercise attwo different intensities on blood lipids and apolipoproteins (apo), 26 hypercholesterolemic men (cholesterol = 258 mg/dl, age = 47 yr, weight = 81.9 kg) trained three times per week for 24 wk, 350 kcal/session athigh (80% maximal O₂ uptake,n = 12) or moderate (50% maximalO₂ uptake, n = 14) intensity. Serum lipid andapolipoprotein (apo) concentrations (plasma volume adjusted) weremeasured before and immediately, 24, and 48 h after exercise on fourdifferent occasions corresponding to 0, 8, 16, and 24 wk of training.Data were analyzed using three-way repeated-measures multivariateanalysis of variance followed by analysis of variance and Duncan'sprocedures ( = 0.05). A transient 6% rise inlow-density-lipoprotein cholesterol measured before training at the24-h time point was no longer evident after training. Triglyceridesfell and total cholesterol, high-density-lipoprotein cholesterol(HDL-C), HDL₃-C, apo A-I, and apoB rose 24-48 h after exercise regardless of training or intensity.Total cholesterol, HDL₃-C, apoA-I, and apo B were lower andHDL₂-C was higher after trainingthan before training. Thus exercise training and a single session ofexercise exert distinct and interactive effects on lipids andapolipoproteins. These results support the practice of training atleast every other day to obtain optimal exercise benefits.

     

Divergence of chloroplast gene organization in three legumes: Pisum sativum,Vicia faba and Phaseolus vulgaris

Summary Isolated chloroplasts from Pisum sativum were found to contain at least 32 tRNA species. Hybridization of in vitro labeled, identified, chloroplast tRNAs to Pisum chloroplast DNA fragments revealed the locations of the tRNA genes on the circular chloroplast genome. Comparison of this gene map to the maps of Vicia faba and Phaseolus vulgaris showed that the chloroplast genomes of Pisum and Phaseolus are otherwise more closely related than either genome is to the chloroplast genome of Vicia. Furthermore, the results suggest how possible recombination events could be involved in the evolution of these three closely related, but divergent, chloroplast genomes.     

Diverse responses across soil parent materials during ecological restoration

A major challenge to advancing the science and practice of ecological restoration is working across large landscapes containing diverse sites that may respond differently to restoration. We conducted a 5‐year restoration experiment, replicated across 9 sites spanning 3 soil parent material types within a 9,000‐ha Pinus ponderosa forest landscape. We evaluated plant community response to restoration Pinus thinning, grazing, and aqueous smoke application. We measured vegetation before (2003) and 3 (2006) and 5 (2008) years after treatment. Plant community responses of species richness, cover, and composition were diverse, ranging from increases, decreases, or no change depending on soil parent material, tree thinning, and presence or exclusion of grazing. Restoration outcomes were under hierarchical control: soil parent material constrained response to Pinus thinning, which in turn influenced grazing effects. On limestone‐derived soil, responses included no change in species richness but increased plant cover with Pinus thinning. Both plant richness and cover increased on benmorite soil after thinning, and cover generally increased more without grazing. On rocky, basalt soil, plant richness increased but cover did not after any treatment. Diversity of responses to restoration has implications for: (1) setting goals or monitoring indicators tailored to inherent soil capability; (2) identifying where grazing most affects restoration outcomes; and (3) forecasting responses to restoration across landscapes. Diverse responses to restoration along physiographic gradients such as soil parent material warrant consideration when developing restoration across degraded landscapes.     

Effects of nisin on growth of bacteria attached to meat

Nisin had an inhibitory effect on gram-positive bacteria (Listeria monocytogenes, Staphylococcus aureus, and Streptococcus lactis) but did not have an inhibitory effect on gram-negative bacteria (Serratia marcescens, Salmonella typhimurium, and Pseudomonas aeruginosa) attached to meat. Nisin delayed bacterial growth on meats which were artificially inoculated with L. monocytogenes or Staphylococcus aureus for at least 1 day at room temperature. If the incubation temperature was 5 degrees C, growth of L. monocytogenes was delayed for more than 2 weeks, and growth of Staphylococcus aureus did not occur. We also found that the extractable activity of nisin decreased rapidly when the meats were incubated at ambient temperatures and that this decrease was inversely related to the observed inhibitory effect. These findings disclosed that nisin delays the growth of some gram-positive bacteria attached to meat. However, nisin alone may not be sufficient to prevent meat spoilage because of the presence of gram-negative and other nisin-resistant gram-positive bacteria.